© 2020, Krishtel eMaging Solutions Private Limited.Background: The quasi-3D finite element model includes the smart actuation on a three-layer sandwich plate with laminated composite face-sheets. In the model, the face-sheets are represented as Reissner-Mindlin plates and the core is modeled as a three-dimensional continuum. Purpose: This representation allows accurate modeling for a wide range of core types. In this model, the electrical constitutive relations of piezoelectric layers are included in the formulation of the face-sheets. In previous publications, this quasi-3D finite element formulation has demonstrated some advantages in comparison with solid finite element models. The aspect ratio of three-dimensional elements can make it rather inconvenient to use on very thin faces-sheets, which makes the number of degrees of freedom very high. Methods: Analytical through-thickness integration of the energy expressions is used to reduce the three-dimensional problem to two dimensions for the evaluation of mass and stiffness matrices. In the same way, the analytical integration of the electrical voltages work applied to the piezoelectric layers produces the piezoelectric actuation force vector. Result: This research assesses the accuracy of the proposed model for dynamic responses of sandwich plates using a broad range of core-to-face-sheet stiffness ratio. Conclusions: The numerical results show that deflections promoted by the voltage applied to piezoelectric layers of the sandwich plate are very small, even if the core is very flexible. The results also indicate that the core flexibility strongly affects the natural frequencies of the higher bending modes.

© 2023 Elsevier B.V.The current study proposes a shot peening model which enables the residual stress interaction with grinding, a typical combination for gear finishing. The effect of the interaction on the stress state development was addressed by comparing the residual stress state from a standalone shot peening procedure, against the residual stress state arising from a manufacturing route where the interaction of shot peening and grinding takes place. In the interaction model, the grinding procedure generates a pre-loaded condition on the material, modifying the internal strain system of the gear tooth. This pre-loaded system, when disturbed by shot peening, reaches a new internal strain equilibrium. In the interaction model, a 24% less compressive stress state was attained when compared with the standalone shot peening process. A significant shift in the depth and magnitude of the peak compressive stress was also observed. On account of the numerical study of the processes’ interaction, the developed model substantially contributed to understanding the residual stress formation during manufacturing chains.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.This work employs a micromechanical theory and kinematic relationships to describe the displacement field in individual unidirectional composite plies. The technique relies on an incremental approach where the misalignment angle of fibers is the main variable in the analysis. Upon convergence at a certain loading level, stresses and strains are evaluated in the fibers and matrix using micromechanics, and a specific failure criterion is applied. The Ramberg–Osgood relations are used to correct degraded mechanical properties of the resin in the nonlinear regime. The use of a 2D finite element model with a 3° initial misalignment angle of fibers, showed a good approach to complement the problem solution. The Hashin-Rotem failure criterion and experimental data obtained by Matsuo (Compos Part A: Appl Sci Manuf, 93:117-125, 2017) are used to validate the technique. It is observed that the numerical and experimental results obtained correlate well.

© 2022 Elsevier Masson SASDue to the unique characteristics of composite materials, the study of composite beams is far more complex than the study of homogeneous beams. The finite element method has proven to be a powerful approach to analyze composites subjected to the most distinctive situations. In the present work, two element solutions using cubic polynomials are considered: with continuous stresses and with discontinuous stresses along the transverse direction. Both converge to the analytical solution as the number of elements increase, i.e. with a finer mesh. Besides satisfying the boundary conditions at the surfaces and interfaces, the first solution gives better outcomes close to the center of the beam. On the other hand, the second solution gives better outcomes close to the borders of the beam, but it has a larger number of nodal parameters. The results are compared to a zig-zag element solution which has a number of nodal parameters independent of the number of layers. An element based on the Reissner mixed variational theorem is also included for additional comparisons. It is concluded that the cubic polynomials used to expand the cross section functions, must be different in each layer in order to achieve a reasonable agreement between the analytical and the calculated transverse normal stress.

© 2023 IEEE.The paper describes the constitution of the Engineering Research Center for the Aerial Mobility of the Future (ERC-AMF) having ITA as the host institution, Embraer as the industrial partner, and researchers from the University of São Paulo and the University of Campinas. The objective of the ERC-AMF is the realization of R&D to contribute to overcoming challenges to the shaping of aerial mobility in the upcoming decades. These challenges arise from the necessity of reducing pollutant and noise emissions, and the need for increased efficiency of manufacturing processes, besides the trend of introducing in the market novel aircraft adapted for operation in urban environments and short-range travels. Five research areas are focused on the first operation phase of the Center: Machine Control for Electric Propulsion; Aeropropulsion Integration in Electric Aircraft; Methods for Decision Making in Autonomous Systems; Advanced Design for Metallic Additive Manufacturing; and Intelligent Aircraft Final Assembly. Each line will be developed by researchers from partner universities and engineers from Embraer. It is expected that the Center will contribute to the appropriation, by the Brazilian aeronautical industry, of scientific and technological knowledge generated, and, as a result, increase its preparedness to face challenges that shall be overcome in the process of shaping the aerial mobility of the upcoming decades.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Thicker blunt trailing edge airfoils are extensively employed in many applications, especially in wind turbines. Their structural properties, such as strength section and area moment of inertia, and aerodynamic characteristics, such as higher curve slope and maximum lift coefficient, are particularly specials to design a blade that operates under varying cyclic loads and speeds, which establish dynamic conditions of creep loading, and fatigue stress. The main disadvantages are the higher drag and an intense and broadband noise, caused by the vortex shedding downstream. Many improvements have been achieved using passive flow controls to mitigate those problems, but there is still wide design space for better solutions. In this sense, the aim of this study is to investigate the potential of waviness applied on truncated trailing edge of thick airfoils as a possible efficient flow control mechanism. For this purpose, experiments in wind tunnel is carried out in order to understand the effects of different wavy geometries on truncated airfoil. A NACA 0020 airfoil is selected as a baseline profile, truncated at 15% from the trailing edge, and three configurations of waviness are tested: A = 0.11c, λ = 0.40c; A = 0.03c, λ = 0.40c; and A = 0.03c, λ = 0.11c. The phenomena is evaluated measuring forces in a wind tunnel at a Reynolds numbers of 200,000, and applying a technique of oil flow visualization. Main results shows that the wavy model presents much higher values of aerodynamic efficiency for lower angles of attack up to α = 5º. Besides that, another wavy configuration overcame the efficiency of the smooth truncated model for almost all pre and pos-stall regions. For low angles, a possible explanation is the break of vortex shedding coherence spanwise in the base, while for higher angles waviness allows to avoid flow separation over the surface.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Recently, waviness applied on leading edge of airfoils has been extensively researched. As a biomimetic solution, the also called tubercle has brought up many insights on passive flow control mechanisms and inspired other studies. Therefore, the present study aims to investigate the potential of waviness now applied on the trailing edge of airfoils. For this purpose, experimental tests in wind tunnel is carried out in order to understand the effects of different wavy geometries on the flow. A NACA 0020 airfoil is selected as a baseline profile and three configurations of waviness are tested: A = 0.11c, λ = 0.40c; A = 0.03c, λ = 0.40c; and A = 0.03c, λ = 0.11c. The phenomena are evaluated measuring forces at a single Reynolds numbers of 250,000, and correlating it with a flow topology analysis provided by an oil flow visualization technique. Main results show that the wavy model with parameters A = 0.11c, λ = 0.40c presents the best aerodynamic efficiency, with similar lift values compared to the baseline profile, but with reduced drag coefficients, also briefly delaying stall separation. Flow visualization shows that this case has larger regions of attached flow.

© 2023 Elsevier B.V.The interaction of single Fe, Co, Ni, and Cu atoms with polar terminations of orthorhombic Mo2C(0 0 1) surface has been investigated at low surface coverage by using density functional theory. Calculations indicate high stability of all considered adsorbates, regardless the surface termination. The presence of a single foreign atom has a localized impact on the properties of the surface, causing charge redistribution in the adsorbate/surface interface. As the result lowering of the work function is observed for both Mo2C(0 0 1) terminations. Another effect is shifting the position of d-band center further away from the Fermi level for surface Mo atoms of metal-terminated carbide, while no changes are seen for carbon's near-Fermi level electronic states in the case of C-terminated modified surface. Results demonstrate a short-range effect on the stability of atomic hydrogen caused by the foreign adatom on both terminations. Specifically, the observed adsorption energy weakening would entail an enhancement in the catalytic activity of Mo2C toward hydrogen evolution reaction according to the Sabatier principle. Results evidence that molybdenum carbide modified by cobalt and iron is expected to be more active toward hydrogen evolution reaction than Mo2C modified by nickel and copper or than unmodified carbide.

© 2023 The Authors.Market movement towards sustainability and electromobility impose new demands on the gear Industry in terms of materials, design and manufacturing. In this context, laser powder bed fusion (L-PBF) has been under the spotlight for being one of the most promising technologies in additive manufacturing (AM), allowing the designer to think beyond traditional constraints. On the other hand, anisotropic properties, distortions, and heterogeneous residual stress may lead to excessive stress states during finishing processes. For carburizing materials, such as 20MnCr5, the mechanisms leading to residual stress and distortions go beyond the temperature gradient mechanism (TGM) and incorporate significant microstructural changes due to phase transformation. The combination of these phenomena with the gear manufacturing chain places a significant challenge to the gear industry. Therefore, this study investigates the potential and challenges of manufacturing 20MnCr5 gears through L-PBF with focus on the surface integrity evolution along the manufacturing chain. The study addresses the processability of the material and investigates the surface integrity of the gears through the manufacturing chain. The composition of thermal and microstructural phenomena simultaneously occurring during print generates heterogeneous residual stress along the gear orientation. Contrary to the literature, the stress relief did not equalize the residual stress entirely. Therefore, the heterogeneous residual stress distribution observed in the as-built condition propagated through the entire chain. Even after three manufacturing operations, the pattern of residual stress after printing directly influenced the final residual stress state.

© The Author(s), 2023. Published by Cambridge University Press.We present the results of direct numerical simulations of a NACA 0012 airfoil, with Mach number 0.3 and angle of attack of, examining the dynamics of the flow with increasing Reynolds numbers. Two-dimensional simulation results are obtained with chord-based Reynolds numbers in the range, where each simulation uses the last time step of the previous one as a starting point, to capture the evolution of dynamics as a function of. The development of the pressure fluctuations with time shows a transition from periodic to quasi-periodic attractor for, leading to the emergence of secondary tones in the wall and acoustic field pressure spectra, different from peaks related to the fundamental frequency and the respective harmonics; a second, incommensurate frequency appears, leading to several secondary tones with frequency, with and integers. Further increase of the Reynolds number leads to the emergence of a tertiary frequency, indicating a route to chaos of the Ruelle-Takens-Newhouse type. Such a mechanism is related to the ladder-type characteristic structure of the tones, indicating that dynamic systems theory is an important tool for understanding airfoil tonal noise.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.When solving differential equations, one must often use spatial discretization. However, this process introduces errors that are mesh dependent. Thus, improving solution quality while saving computational resources requires adequate spatial resolution. One way of doing so is to treat this issue as an optimization problem that targets the reduction of discretization error. The current work presents an approach to mesh optimization using r-adaptation and the adjoint method for one-dimensional steady equations. The two equations selected to display this methodology are the heat equation with a forcing term and the viscous burgers equation. The discretization method is a second-order finite differences scheme. The results present a substantial reduction in discretization error when the optimized meshes are employed.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Up to this day, the Computational Fluid Dynamics (CFD) field struggles to generate accurate and computationally viable turbulent flow simulations for aeronautical problems. The absence of a proper spatial resolution reduces the accuracy of simulations and may lead to nonphysical results and numerical instabilities. This problem may be addressed by increasing the number of degrees of freedom in the simulation. Since this also leads to higher computational costs, this process must be performed parsimoniously and focus on where it is the most efficient. However, the process of identification and refinement of those regions can be far from trivial. The current work is an initial step to investigate the performance of adaptation drivers that can be used to make industrial simulations more viable. The drivers are based on a jump indicator for high-order spectral/hp schemes. It takes the difference between averaged values on overlapping borders of two different elements as a measurement of error. The chosen adaptation method is a p-adaptation framework that increases the polynomial order of 10% of the mesh elements. The governing equations employed in the study are the two-dimensional Navier-Stokes equations, and the simulated test case is one of a tilted flat plate.

© 2023 American Physical Society.A resolvent-based methodology is employed to obtain spatiotemporal estimates of turbulent pipe flow from probe measurements of wall shear-stress fluctuations. Direct numerical simulations (DNSs) and large-eddy simulations (LESs) of turbulent pipe flow at a friction Reynolds number of 550 are used as databases. We consider a DNS database as the true spatiotemporal flow field, from which wall shear-stress fluctuations are extracted and considered as measurements. A resolvent-based estimator is built following our earlier work [Amaral, J. Fluid Mech. 927, A17 (2021)0022-112010.1017/jfm.2021.764], requiring a model for the nonlinear (or forcing) terms of the Navier-Stokes equations system, which are obtained from another DNS database, as in our earlier work, and from a series of computationally cheaper LES databases with coarser grids; the underlying idea is that LESs may provide accurate statistics of nonlinear terms related to large-scale structures at a low computational cost. Comparisons between the DNS and the estimates indicate that sufficiently accurate results can be achieved with estimators built with statistics from LESs with an order of magnitude fewer grid points than the DNSs, with estimates closely matching the reference DNS results up to the buffer layer and reasonable agreement up to the beginning of the log layer.

© 2023 American Physical Society.Reactive flow control has been shown to be a promising tool to improve, among other aspects, the aerodynamic characteristics of an aircraft. This paper focuses on the use of reactive flow control to attenuate Tollmien-Schlichting (TS) waves over a wing profile. TS waves are an instability mechanism that is one of the first stages of boundary layer transition to turbulence. The Wiener-Hopf technique was used in this work for the experimental boundary layer control. The approach improves previous wave-cancellation techniques that, by constructing control kernels in the frequency domain, lead to control kernels with a noncausal part, i.e., actuation would need future sensor information to be constructed. In practical applications, it is unfeasible to access this type of information. Ignoring the noncausal part of the kernel leads to suboptimal solutions that might significantly degrade the performance of the controller. The Wiener-Hopf formalism allows us to take into account causality constraints in the formulation of the control problem, leading to an optimal realistic solution and a control kernel that is causal by construction. Moreover, it is possible to construct the control strategy based only on the power and cross-spectra obtained experimentally in a data-driven approach. The present work shows how to apply experimentally the Wiener-Hopf resolvent-based formalism using signals from a wind tunnel experiment, demonstrating that the TS waves can be effectively attenuated via a Wiener-Hopf-based controller, which yielded better results than a typical wave-cancellation approach.

© The Author(s), 2023. Published by Cambridge University Press.We present the results of direct numerical simulations of a NACA 0012 airfoil, with Mach number 0.3 and angle of attack of, examining the dynamics of the flow with increasing Reynolds numbers. Two-dimensional simulation results are obtained with chord-based Reynolds numbers in the range, where each simulation uses the last time step of the previous one as a starting point, to capture the evolution of dynamics as a function of. The development of the pressure fluctuations with time shows a transition from periodic to quasi-periodic attractor for, leading to the emergence of secondary tones in the wall and acoustic field pressure spectra, different from peaks related to the fundamental frequency and the respective harmonics; a second, incommensurate frequency appears, leading to several secondary tones with frequency, with and integers. Further increase of the Reynolds number leads to the emergence of a tertiary frequency, indicating a route to chaos of the Ruelle-Takens-Newhouse type. Such a mechanism is related to the ladder-type characteristic structure of the tones, indicating that dynamic systems theory is an important tool for understanding airfoil tonal noise.

© 2023 by the American Institute of Aeronautics and Astronautics, Inc..In this work, a kinematic wave-packet model is used to predict installed-jet noise. Large-eddy simulation results of freejets, for Mach numbers 0.4 and 0.9, are used to obtain parameters of wave packets representing large-scale turbulent structures, which were used to provide a model source for the Lighthill analogy used to predict far-field noise spectra. The source amplitude in the model is calibrated using noise measurements for a freejet, and such a wave-packet source is used to predict noise of the same jet in an installed configuration using a tailored Green’s function. Results from the prediction model are compared to installed-jet experimental data for four different observer positions and a large range of frequencies. Overall, the model predicts both directivities and amplitudes similar to the experimental data, with a hump in the generated noise for lower Strouhal numbers and a clear peak near a Strouhal number of 0.2. This low-order model is fast and flexible, and it is expected to be helpful in preliminary aircraft design.

© 2023 American Physical Society. Stochastic linear modeling proposed in Tissot, Mémin, and Cavalieri [J. Fluid Mech. 912, A51 (2021)0022-112010.1017/jfm.2020.1168] is based on classical conservation laws subject to a stochastic transport. Once linearized around the mean flow and expressed in the Fourier domain, the model has proven its efficiency to predict the structure of the streaks of streamwise velocity in turbulent channel flows. It has been in particular demonstrated that the stochastic transport by unresolved incoherent turbulence allows us to better reproduce the streaks through lift-up mechanism. In the present paper, we focus on the study of streamwise-elongated structures, energetic in the buffer and logarithmic layers. In the buffer layer, elongated streamwise vortices, named rolls, are seen to result from coherent wave-wave nonlinear interactions, which have been neglected in the stochastic linear framework. We propose a way to account for the effect of these interactions in the stochastic model by introducing a stochastic forcing, which replaces the missing nonlinear terms. In addition, we propose an iterative strategy in order to ensure that the stochastic noise is decorrelated from the solution, as prescribed by the modeling hypotheses. We explore the prediction abilities of this more complete model in the buffer and logarithmic layers of channel flows at Reτ=180, Reτ=550, and Reτ=1000. We show an improvement of predictions compared to resolvent analysis with eddy viscosity, especially in the logarithmic layer.

© 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Colistin remains one of the few available options for the treatment of infections caused by resistant bacteria. Pharmacokinetic (PK) studies have been successful in estimating the appropriate colistin methanesulfonate (CMS) dose to achieve a target colistin concentration. Currently, there is a consensus that the dose of CMS should vary according to the patient renal function since CMS is mainly eliminated by renal route. For this same reason, the loading dose should vary according to the patient's renal capacity; however, this is not the current clinical practice. In this study we develop a framework to determine two key parameters for the loading dose regimen: (1) the optimal dose according to the characteristics (renal function and weight) of the patient; (2) the waiting time before the maintenance dose. Based on a previous PK model, our framework allows a fast parameter sweep so as to select optimal loading dose and waiting time minimizing the deviation between the plasma concentration and a target value. The results showed that patients presenting low creatinine clearance (CrCL) should receive a lower CMS loading dose with longer interval to start maintenance treatment to avoid nephrotoxic colistin concentrations. In cases of high CrCL, the dose should be higher and the interval to the next dose shorter to avoid subtherapeutic concentrations. Optimization of the loading dose should considerably improve colistin therapy, as the target concentration is reached more quickly, without reaching toxic values.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.In recent years, flow control has become increasingly important for the aeronautical field, as it is seen as a promising tool to design safer, quieter and more efficient aircraft. Since non-causality is observed in several flow control problems solved in the frequency domain, we consider here the use of the Wiener-Hopf technique for the control of a forced turbulent jet. Such approach allows us to enforce causality when obtaining the control kernel, which provides an optimal causal solution, and with this, prevents the drop in performance that may be observed in flow control applications that use a truncated solution. The experimental results presented here shows a significantly better performance of the Wiener-Hopf method with respect to that of a truncated kernel obtained using a wave-cancellation approach.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Large-eddy simulations of a Blasius boundary layer over a flat plate, without a leading edge, at multiple levels of incoming free stream turbulence are considered. The data from the saved snapshots are then applied to an input-output model where non-linear terms of the Navier-Stokes equations are treated as an external forcing. By separating the inputs corresponding to the perturbations coming through the inflow boundary and non-linear forcing, we can perform the full reconstruction of the statistics of the flow observed in the simulations and discriminate which frequencies and wavenumbers are more affected by either linear or non-linear dynamics. Different frequency-wavenumber combinations reveal streaks that grow predominantly through linear or non-linear mechanisms, the former occurring upstream and the latter at downstream stations of the boundary layer.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.This paper reports aeroacoustic experiments on round jets containing tab elements adhered to the nozzle internal surface with the purpose of generating steady streaks in the nozzle boundary-layer. Such streaks are theoretically expected to reduce growth rates associated with the Kelvin-Helmholtz mechanism and, in turn, to reduce jet noise. Nozzle configurations with and without a boundary-layer transition trigger element (carborundum trip), were studied. Stereo particle image velocimetry (stereo PIV) was employed to measure the three components of the velocity for a series of planes parallel to the nozzle exit at Mj = 0.7 in the 0.03 xD 10 streamwise range, where x is the streamwise distance and D is the jet diameter. Such measurements clearly show alternating regions of high and low speed flow due to the streaks that were induced by the tabs on the nozzle boundary-layer and are sustained in the jet shear-layer up to at least xD = 3. The acoustic experiments were performed in an anechoic facility, using an azimuthal array containing 18 equally-spaced microphones to characterize the acoustic field. The antenna was employed to conduct measurements at 15 streamwise stations in the 20 deg θ 90 deg polar range. All acoustic experiments were conducted in the 0.4 Mj 0.9 Mach number range. The presence of the tab elements leads to noise reductions of up to 6 dB/St, observed for Strouhal numbers in the 0.1 St 0.5 range, Mj = 0.4, axisymmetric azimuthal mode and untripped boundary-layer case. When the trip mechanism is present, the noise reduction is up to 3 dB/St. An overall sound pressure level (OASPL) reduction of up to 3 dB was measured for axisymmetric mode of the tabbed case for Mj = 0.4. As the tabs were designed based on boundary-layer measurements at Mj = 0.4, the noise reduction decreases with increasing Mach number. Nevertheless, significant noise reductions of up to 1.5 dB are still observed up to Mj = 0.9 and axisymmetric mode. Moreover, the noise reduction is up to 6 dB for the two first helical modes. The noise reduction was measured at both lower and higher polar angles and for almost the entire frequency range, up to at least St 2. Streak-inducing devices such as the present tabs are thus a promising approach to reduce jet noise

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.In a combined experimental and numerical effort we investigate aerofoil tonal noise generation and reduction. The means of noise control are streak generators in form of cylindrical roughness elements. These elements are placed periodically along the span of aerofoil at the mid chord streamwise position. Experiments are performed for a wide range of Reynolds number and angle of attack. In the present work we concentrate on our numerical investigations. We have performed wall-resolved large-eddy simulations for a given angle of attack of 0 degree and Mach 0.3. Two Reynolds numbers 0.8 × 105 and 1.0 × 105 have been investigated, showing acoustic results consistent with experiments at the same Reynolds but lower Mach numbers. Roughness elements attenuate tones in the acoustic field, and, for the higher Reynolds number, suppress them. Through Fourier decomposition and POD analysis of streamwise velocity data, dominating structures have been identified. Further, the coupling between structures generated by surface roughness and instability modes (Kelvin-Helmholtz) of shear layer has been identified, suggesting stabilisation mechanisms by which the sound generation by the airfoil is reduced by the roughness elements.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.This experimental work investigates the trailing-edge (TE) noise from a NACA0012 airfoil in an open-jet wind tunnel, for chord-Reynolds numbers between 105 and 4.6 × 105 and angles of attack between 0° and 6°. The range of parameters for which TE noise is either tonal or broadband in the present experiments is in good agreement with existing literature results. One of the main objectives of this work is to test the assumption of recent modelling approaches based on the linearised Navier-Stokes operator. These studies focus on spanwise coherent structures in the turbulent boundary layer to investigate the mechanisms responsible for trailing edge noise, as they always satisfy the trailing edge scattering condition. However, numerical simulations routinely use a narrow numerical domain and periodic lateral boundary conditions, which could favour spanwise coherent dynamics. Therefore, particular emphasis is placed on the experimental characterisation of the spanwise wavenumber content of the pressure fluctuations on the airfoil surface and in the acoustic field. A good agreement with theoretical and numerical observations is found, as the spanwise wavenumber contents of the acoustic field are in good agreement with the edge scattering condition. Furthermore, the coherence between the surface pressure fluctuations and the acoustic fields is significantly improved when considering spanwise-coherent structures by spanwise averaging of the temporal signals, even in the case of broadband noise.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.An array of cylindrical roughness elements was used to reduce the tonal noise introduced by the separation bubble over a NACA 0012 airfoil at low angles of attack. Experiments were performed for four configurations: a baseline smooth airfoils, two with roughness elements at only one of the airfoil surfaces (pressure side or suction side), and the other with roughness elements at both airfoil surfaces. Arowof spanwise periodically spaced cylinderswas placed close to the mid-chord position in order to induce streaks that render the bubble three-dimensional, decreasing separation and stabilizing the Kelvin-Helmholtz instability of the separated shear layer, which is related to tonal noise. Our results show a decrease, and in some cases the total suppression, of the tonal noise at Reynolds numbers ranging from 0.6×105 to 2.5×105, and angles of attack ranging from 0 to 4 degrees.

© 2023 Elsevier Masson SAS. All rights reserved.An attempt to improve the accuracy of resolvent-based predictions by including velocity correlations in the linear model is developed here. Closure assumptions for unresolved nonlinearities are thus pushed back to a higher order. Turbulent channel flow is considered as a test case: response and forcing modes obtained from singular value decomposition of the new resolvent model are compared to Spectral Proper Orthogonal Decomposition (SPOD) modes extracted from a Direct Numerical Simulation (DNS) database. The performance of the approach is also measured against previous resolvent-based models. The new model does not yield significant global improvement, but does improve predictions in some regions. Further work on the method should target the linear modeling of the velocity-pressure gradient correlation tensor.

© 2021 by Antônio B. Guimarães Neto, Guilherme C. Barbosa, Juliano A. Paulino, Rafael M. Bertolin, Jéssica S. M. Nunes, Pedro J. González, Flávio L. Cardoso-Ribeiro, Maurício A. V. Morales, Roberto G. A. da Silva, Flávio L. S. Bussamra, Flávio J. Silvestre, Fernando J. O. Moreira, and Carlos E. S. Cesnik. Published by the American Institute of Aeronautics and Astronautics,.The challenges of modeling flexible aircraft include appropriate fidelity capturing and validation with experimental data. In fact, the validation of formulations and models for the flexible flight dynamics is indispensable to ensure that all the important phenomena are correctly captured. With this objective, two high-aspect-ratio flexible aircraft have been flight-tested, and coupled aeroelastic–flight dynamics data have been collected to support model validation. Additional ground vibration and static tests were carried out to fully characterize the structural dynamic properties. Numerical models were built based on a linear structural representation but with geometrically nonlinear aerodynamics. Low Reynolds number effects were included in a simplified way with lookup tables of two-dimensional airfoil data. Wing-tip effects were considered via the vortex-and doublet-lattice methods. Propulsive data were obtained with wind-tunnel tests. This paper describes the numerical models, the two aircraft, and their instrumentation and presents the data collected from the aircraft sensors during flight tests. Numerical and experimental results are compared for angular velocities, accelerations, and strains measured at different points of the aircraft. Despite its limitations and simplifications, the numerical model captures the real aircraft main aeroelastic and flight dynamic behaviors.

© 2023 by the authors.In the presented study, a novel approach for thermal atomic layer deposition (ALD) of Al2O3 thin films using plasma-activated water (PAW) as a co-reactant, replacing traditionally employed deionized (DI) water, is introduced. Utilizing ex situ PAW achieves up to a 16.4% increase in the growth per cycle (GPC) of Al2O3 films, consistent with results from plasma-enhanced atomic layer deposition (PEALD). Time-resolved mass spectrometry (TRMS) revealed disparities in CH4 partial pressures between TMA reactions with DI water and PAW, with PAW demonstrating enhanced reactivity. Reactive oxygen species (ROS), namely H2O2 and O3, are posited to activate Si(100) substrate sites, thereby improving GPC and film quality. Specifically, Al2O3 films grown with PAW pH = 3.1 displayed optimal stoichiometry, reduced carbon content, and an expanded bandgap. This study thus establishes “PAW-ALD” as a descriptor for this ALD variation and highlights the significance of comprehensive assessments of PAW in ALD processes.

© 2023 Elsevier LtdSurface acoustic wave (SAW) sensors enhanced by a graphenic sensitive layer offer improved electrical response uniformity, and recent research has explored their potential for use in point-of-care platforms. These devices offer a unique combination of cost effectiveness, ease of handling, manufacturability, and remarkable sensor performance. This article summarizes the latest advancements in SAW sensors with graphenic-based nanomaterials, including their fabrication, operation mechanisms, and properties. Several recent studies are reviewed and compared to conventional SAW sensors. Furthermore, the challenges and prospects of using graphenic-based structures to enhance SAW devices and produce rapid actionable results are discussed.

© 2023AlGaN thin films with different Al content were grown via reactive magnetron sputtering onto glass substrates using independent Al and Ga targets. The quality of the films was analyzed using X-ray diffraction, Raman spectroscopy, energy dispersive spectroscopy, and UV-Vis spectrophotometry. The results show that the Al content can be effectively controlled by tuning the power ratio applied to the independent targets in different absolute situations. Moreover, all produced samples presented only wurtzite structure without indication of other phases on both X-ray diffraction and Raman spectroscopy analyses. Overall, the properties of the films had a strong correlation with the composition, such as the expected blue shift of the optical bandgap and the Raman phonon modes, and the lattice cell expansion with increasing Al content. In addition, a higher c-orientation texture together with a sharper diffraction peak were observed for samples with more Al.

© 2023 by the authors.In this study, we report the use of a radiofrequency plasma-assisted chemical vapor deposition (RF-CVD) system with a hollow cathode geometry to hydrogenate anatase TiO2 thin films. The goal was to create black TiO2 films with improved light absorption capabilities. The initial TiO2 was developed through magnetron sputtering, and this study specifically investigated the impact of hollow cathode hydrogen plasma (HCHP) treatment duration on the crucial characteristics of the resulting black TiO2 films. The HCHP treatment effectively created in-bandgap states in the TiO2 structure, leading to enhanced light absorption and improved conductivity. Morphological analysis showed a 24% surface area increase after 15 min of treatment. Wettability and surface energy results displayed nonlinear behavior, highlighting the influence of morphology on hydrophilicity improvement. The anatase TiO2 phase remained consistent, as confirmed by diffractograms. Raman analysis revealed structural alterations and induced lattice defects. Treated samples exhibited outstanding photodegradation performance, removing over 45% of methylene blue dye compared to ~25% by the pristine TiO2 film. The study emphasized the significant impact of 15-min hydrogenation on the HCHP treatment. The research provided valuable insights into the role of hydrogenation time using the HCHP treatment route on anatase TiO2 thin films and demonstrated the potential of the produced black TiO2 thin films for photocatalytic applications.

© 2023 The Author(s)We report a joint experimental and theoretical study of the structural and vibrational properties of C-type bulk Y2O3 under hydrostatic compression. The combination of high-pressure X-ray diffraction and Raman scattering experimental measurements with ab initio theoretical calculations on bulk Y2O3 allows us to confirm the cubic (C-type) – monoclinic (B-type) – trigonal (A-type) phase transition sequence on the upstroke and the trigonal-monoclinic phase transition on the downstroke. This result reconciles with the results already found in related rare-earth sesquioxides of cations with similar ionic radii as Y, such as Ho2O3 and Dy2O3, and ends with the controversy regarding the existence of the intermediate monoclinic phase between the cubic and trigonal phases in pure bulk Y2O3 on the upstroke. As a byproduct, the good agreement between experimental and calculated results allows us to use extensive theoretical data to discuss the structural and vibrational behavior of the three phases of Y2O3 under compression, thus allowing a more detailed understanding of the effect of pressure on rare-earth sesquioxides than previous studies.

© 2023, The Author(s), under exclusive licence to the Korean Fiber Society.This work presents permethrin (15%)-based monomers polymerisation in polyamide fabrics using hybrid corona–dielectric barrier discharge (DBD) to potentiate insect–parasite repellency functionalities in polyamide fabrics. First of all, the electric characterisation of the discharge was made using the Lissajous figure method for determining the plasma dosage (2841 W min m−2). Before the polymerisation process, the polyamide fabric was activated by DBD discharge, operating at 23 kHz and voltage amplitude of 12.5 kV in atmospheric pressure. After that, the polymerisation process is initiated by injecting permethrin into the system, maintaining the operational parameters used in the activation process. The non-activated and activated polyamide fabrics measured the static and dynamic contact angle, showing a variation from 120° (non-activated) to 34° (immediately after plasma activation). The chemical structure of synthesised permethrin was evaluated by Fourier transformed infrared (FTIR) spectroscopy to confirm the polymerisation (deposition) of permethrin on the fabric surface; it is possible to observe the 648 cm−1 bands that are associated with asymmetric vibration of the C–Cl bonds, but most evident change occurs at 1045 cm−1, which is associated with cyclopropyl group vibrations. Field emission scanning electron microscopy (FESEM) analysis was used to evaluate the possible degradation of the fabric surface when exposed to plasma activation and the homogeneity of the permethrin coating in the fibres after the polymerisation. The energy dispersive spectrometer (EDS) was used to confirm the polymerisation and the distribution of the permethrin in the fabric.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.This work reports on the properties of GaN films grown by reactive magnetron sputtering onto glass substrate kept at relatively low temperature (400°C), using different RF power applied to the Ga target. Their structural, morphological, vibrational and optical properties were characterized by X-ray diffraction, atomic force and scanning electron microscopies, Raman spectroscopy and UV-vis spectrophotometry. The films have wurtzite phase with strong preferential orientation in the c-axis direction. Moreover, two clear contributions to the (0002) diffraction peak could be found, indicating the presence of two different morphologies, which were discussed in terms of the formation of an intermediate layer between the substrate and a dominating columnar-like microstructured film.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.In this work, a thermal plasma-based ablation test system was used to evaluate the ablative performance of the EPDM composite. The system produces a high enthalpy plasma jet generated by a plasma (DC) torch, operating at atmospheric pressure using compressed air as working gas, enabling the variation of the thermal flux concerned with the studied EPDM composites. The samples were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Fourier-Transform Infrared spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) to investigate the morphology, mass-loss rate, the reaction layer (char formation), and chemical changes of the samples for each thermal flux. For a complete evaluation, the thermal fluxes were varied in 0.30, 0.45, 0.60, 0.75, and 0.90 MW/m2 and for each thermal flux, disk-shape samples remained exposed to the plasma jet for 10s. During the plasma jet exposure time, the temperatures of the surface and the back of the samples were collected to verify the formed char layer’s insulator capacity and the samples’ thermal diffusivity for each experimental condition. The mass loss is continuous under the thermal fluxes of 0.30 and 0.45 MW/m2, stabilizing at 60% until 0.75 MW/m2. The formed char layer begins to lose its protective capacity, evidenced by the size decrease (from 800 µm to 700 µm), due to the ablation process of the reaction layer from the thermal flux of 0.90 MW/m2

© 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Thermal plasma-assisted processing is an effective process for the synthesis of gas (CO and H2) and carbonaceous materials production from industrial waste. In this paper, a DC plasma torch designed with two vortices chambers has been developed, and its characteristics have been experimentally tested. The plasma torch operates with different plasma working gases, including steam. The results of coal tar pitch (CTP) processing will be presented as a possible ecological application. CTP is a waste from the steel industry mainly composed of polycyclic aromatic hydrocarbons. The experimental results will be discussed with thermodynamic calculations and numerical simulation of the heat and mass transfer in the DC plasma torch and the chemical reaction chamber. The simulations were carried out to clarify the regions of gas flow and temperatures for producing synthesis gas and carbon nanomaterial. The results enable one to predict the produced gas composition and carbon nanomaterial properties. The physicochemical properties of carbon nanomaterial and synthesis gas show high efficiency in converting CTP into high-value-added products.

© 2022 Society.This is an experimental study on the decolorization efficiency and the degradation of organic compounds from textile wastewater by the ozonation process in a batch system. The effects of different sample volumes of textile wastewater over time were investigated. The experiments were performed in a 1 L glass reactor with a magnetic stirrer and a bubble diffuser at the bottom to feed the ozone. The applied cumulative ozone dosage varied at 120 gO3 L−1, 60 gO3 L−1, and 30 gO3 L−1, and the total interaction time for each test was 1 h. To investigate the physicochemical properties of the textile wastewater (solid and liquid phases) before and after the treatment, multiple analytical characterization methods were used: Thermal Gravimetric Analysis, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, and Spectrophotometer. The most perceptive change was observed in the color of the liquid medium, which turned from black to transparent, and a visual color number indicator known as DurchsichtFarbZahl (DFZ) was used for the evaluation of this process. Absorbance values decreased about 3.5 times after 5 min of treatment with a 0.15 L sample volume, and these values differed for tests with larger sample volumes. FTIR spectroscopy demonstrated that the bands’ intensities associated with the C − H, C − N, and C − O decrease during treatment. On the other hand, it was possible to conclude that combining treatment methods to improve the degradation of persistent compounds after the ozonation process is necessary. Finally, the ozonation of the textile wastewater proved to be effective at removing color due to its high reaction capacity.

© 2021 Informa UK Limited, trading as Taylor & Francis Group.The processing of coal tar pitch (CTP) to produce clean fuel gas and carbon black (CB) is studied in a plasma reactor equipped with a direct-current plasma torch. The composition of the gas produced and energy costs were estimated theoretically for the CTP pyrolysis and gasification processes by two oxidants, namely oxygen and water vapor. We have found that the main gaseous compounds obtained in the pyrolysis and gasification processes are hydrogen (H2), carbon monoxide (CO), and very often carbon dioxide (CO2). For the pyrolysis case, the mean value of the synthesis gas concentration reaches a major value of 98 vol.% (H2–81 vol.%, CO–17. vol.%). However, only 23% of the initial CTP is transformed into gas phase at 1100 K and its content increases up to 37.4% at a temperature of 3000 K. For oxygen gasification, the syngas quantity is little less compared to the pyrolysis case and attains 96.6 vol.% (H2–26.5 vol.%, CO–70.1 vol.%) for T > 1100 K. An intermediate syngas content for the water steam gasification is 97.8 vol.% (with H2–55.8 vol.% and CO–42.0 vol.%). The CB produced was composed of well-defined spherical particles of 30-nm size. Furthermore, it is composed of carbon (98.2%), and followed by oxygen (1.8%) with a surface area of 97 m2 g−1. The thermal plasma system shows high efficiency in conversion of CTP into high-value-added products.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.The Turbofan engine represents the type of propulsive technology mostly used in commercial aircrafts, and until that the new disruptive technologies take place, researches to optimize this propulsive system shall be continued to reduce the environmental impacts. The aim of this paper is to propose a methodology for the low-pressure system preliminary design (fan/low-pressure turbine), based on aircraft cruise thrust adjustment from commercial off-the-shelf turbofan engine, focusing on reducing specific fuel consumption for the individual aircraft mission. This work is carried out according to the following steps: (i) model development with calculation methodology for velocity diagram flow angles applied to the low-pressure system; (ii) estimation of baseline low-pressure system design parameters from limited engine data (an integrated engine aircraft model developed in the Gasturb and MATLAB commercial softwares are applied); (iii) evaluation of the strategies to increase the low-pressure system component efficiencies and their implementation by computer simulation; (iv) reapplication of the calculation methodology for estimation of the velocity diagram flow angles considering the adjusted low-pressure system components; and (v) analysis of the adjustment proposal results considering the matching between the lowest specific fuel consumption and the net thrust required for the cruise flight phase of the aircraft. As a final result, it demonstrates that the proposed strategies are promising for the adjustment of the low-pressure system in the preliminary design scope, and this approach may be considered feasibility from the standpoint of the engine manufacturer implementation, since the engine core and its external sizing do not affected.

© 2023 by ASME.Evaporative cooling systems are commonly used in thermoelectric plants to cool the air at gas turbines inlet, improving the performance of these engines. Normally, the evaporative cooling is modeled as adiabatic saturation and, in this case, the water-air equilibrium temperature depends only on the atmospheric air properties. However, other factors such as the water temperature that supplies the equipment and the ratio between the mass flow rates of water and air, also affect the equilibrium conditions of these systems. This work presents three methodologies to calculate the air temperature in equilibrium state, considering all the factors mentioned. The methodologies were implemented in a computer program written in FORTRAN. In all cases tested, the results obtained by the three models showed high convergence. As an example, for 70 different sets of inputs, the absolute and relative differences of the results were below 0.3236°C and 1.2480%, respectively. A statistical study, also on this sample of results, revealed that, for a confidence level of 99%, the hypothesis of the equivalence between the methods cannot be rejected.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Correction Notice Reference 5 should be: L. Vesely, J. S. Kapat, C. Bringhenti, J. T. Tomita, M. F. Stoia, and K. Jui, “sCO2 Waste Heat Recovery System for Aircraft Engines,” AIAA 2022-1407. AIAA SCITECH 2022 Forum. January 2022. doi: https://doi.org/10.2514/6.2022-1407.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.The present work investigates the effect of reordering the nodes and elements of a grid according to the Hilbert curves on the cache utilization in an in-house parallel CFD code. A sorting algorithm is proposed based on domain decomposition techniques and the execution times are compared to those obtained by the structured grid format.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Waste Heat Recovery is one of the key pathways to achieving reduced emissions and improving system efficiency. The Waste Heat Recovery (WHR) may be used to convert the waste energy to electric power by using a bottoming cycle. One of the potential bottoming cycles for aircraft application is a Supercritical CO2 (sCO2) power system. The sCO2 power system has advantages because of the component compactness, which is a key factor for aircraft integration. The present work focuses on the performance of the Supercritical CO2 power system in both the current and the next-generation aircraft engines considering the techno-economic evaluation of the bottoming cycle. The techno-economic evaluation needs to consider bottoming cycle integration and potential fuels, such as hydrogen, ammonia, or sustainable aviation fuel (SAF). The first part of the work is focused on the analysis of the sCO2 WHR system for an aircraft engine. The second part of the work is focused on a detailed techno-economic evaluation, including the capital, operation, and maintenance costs. The simulation was done using in-house computer programs for gas turbine performance and the sCO2 cycle. The results show the potential utilization of WHR in different operational regimes: idling on the ground, cruise, landing, and takeoff. The results show that the Waste Heat Recovery unit may generate an additional 100 - 200 kW. However, the additional power will require an additional cost for the system, approximately $ 2 Million.

Copyright © 2023 by ASME.The industry and the academy are continuously developing new approaches, technologies, and models for gas turbine design. However, there was not enough time to cover all the relevant subjects for undergraduate or graduate students in one or two-semester courses. So, in previous works, the authors described a developed interactive platform for the preliminary design of multistage axial flow turbines for uncooled blades and improved it based on the student’s feedback, so it could be as didactic as possible. Its application in the courses offered by the Turbomachines Department at Aeronautics Institute of Technology (ITA) successfully accelerated the learning process of the basics. In the graduate courses, the use of the program granted time to more complex topics, e.g., blade cooling, off-design performance, CFD simulations, manufacture, and machine learning applied to turbomachine design, which were not covered in previous years. The program initiates with the data from thermodynamic cycle calculation and the definition of the main design parameters. Then, it computes the aerothermodynamic properties of the flow stage-by-stage, from hub to tip, and the geometry of the blades. Finally, it estimates the losses by source, iteratively, through the models of Ainley and Mathieson [1], Dunham and Came [2], or Kacker and Okapuu [3]. This work presents some studies performed by the students using the platform. Firstly, it was varied some design key parameters such as loading and flow coefficients, the aspect ratio and the pitch-to-chord ratio of the blades, the airfoil section geometry, and the tip clearance, once at a time while maintaining the others. Then, it was possible to observe how these modifications affected the number of stages required, the stress levels, the machine size, and the isentropic efficiency, tracking the primary sources of loss. After, the students implemented other loss models, such as the one by Craig and Cox [4], aiming to analyze the effect of surface roughness on the losses. Finally, they compared the platform results with CFD simulations and experimental data from turbines developed at the Department. The paper concludes with the students’ insights through the project and comments on how the employed methodology improved their learning process.

Copyright © 2023 by ASME.The inducer is an axial pump that is part of the propellant injection system of Liquid Propellant Rocket Engines (LPRE). It is located at the inlet of the turbopump assembly and is critical for designing high performance LPREs. Its geometric and operational characteristics allow it to operate at low inlet pressures, delaying the appearance of cavitation and allowing the propellant tanks to operate at lower pressures. This allows the tanks to be lighter due to a reduced wall thickness requirement. The inducer also needs to operate harmoniously with the other components of the turbopump, especially with the main impeller which is located just downstream in the system. Therefore, it is important that the flow conditions at the inducer inlet and outlet are known and integrated with the turbopump and tank design. The present work aims to develop a methodology for inducer design based on literature established methods in order to obtain geometry and evaluate the flow conditions in liquid-propelled rocket engine inducer pumps. This work will assess outlet flow and pressure conditions in a way that it is possible to match them with the main impeller inlet. Performance criteria are evaluated in terms of the outlet pressure coefficient, flow coefficient and efficiency focusing exclusively on non-cavitating conditions. Two established analytical methods were implemented, one to provide inducer geometry in terms of system operational requirements and another, from National Aeronautics and Space Administration (NASA), for performance prediction based on geometrical and operational parameters. Further analysis is complemented by simulating the generated geometry in a CFD software. The methods were validated using published experimental data and the performances of the analytical, numerical and experimental results were compared. Results showed that the 3D turbulent CFD simulations provided very good agreement of efficiency. Satisfactory results were obtained for the general trends of characteristic curves over a range of flow rates and the spanwise distribution of key performance parameters near design point. The pressure coefficient was significantly overestimated. The results of the analytical models showed good agreement with simulated CFD results, indicating appropriate calibration of loss coefficients.

Copyright © 2023 by ASME.The use of inducers in turbopumps for liquid propellant rocket engines allowed operation at high rotational speeds, contributing to global vehicle performance improvement. Methods for designing inducers have been explored using analytical methods, experimental data and numerical solutions. The use of CFD for simulating and designing rocket turbopump inducers is a relevant practice because it can rapidly explore scenarios untested in the experimental endeavors for determining empirical functions. This technique also captures more problem details than reduced order analytical solutions. Turbomachines have a different accuracy in terms of solution prediction for different turbulence models and application. The flow specificity of the turbomachinery changes the adequate turbulence model to obtain a more accurate solution. For this reason, it is of interest to investigate how different turbulence modeling predicts the fluid flow behavior and their accuracy to calculate the inducers' performance. The present work aims to investigate the capability of different turbulence models on the performance and flowfield obtained via CFD simulations of an inducer pump. The CFD simulations were performed using a commercial software for k-ε, RNG k-ε and Shear Stress Transport turbulence models. The simulations were performed on a known inducer geometry for which published experimental performance data as a function of operational conditions is available in literature. The present paper discusses the differences in the performance prediction and the flow field calculated for the turbulence models simulated. For the cases studied, the k-ε standard model shows better predictions for the efficiency and head coefficient compared with the experimental data demonstrating their accuracy in solving rotational flows.

Copyright © 2023 by ASME.The boundary layer ingestion (BLI) concept has emerged as a novel technology for reducing aircraft fuel consumption. Several studies designed BLI-fans for aircraft. BLI-propellers, although, have still received little attention, and the choice of open-rotors or ducted propellers is still an open question regarding the best performance. The blade design is also challenging because the BLI-propulsors ingest a nonuniform flow. These aspects emphasize further investigation of unducted and ducted BLI-propulsors and the use of optimization frameworks, coupled with computational fluid dynamics simulations, to design the propeller to adapt to the incoming flow. This paper uses a multi-objective NSGA-II optimization framework, coupled with three-dimensional RANS simulations and radial basis function (RBF) metamodeling, used for the design and optimization of three propeller configurations at cruise conditions: (a) conventional propeller operating in the freestream, (b) unducted BLI-propeller, and (c) ducted BLI-propeller, both ingesting the airframe boundary layer. The optimization results showed a significant increase in chord and a decrease in the blade angles in the BLI configurations, emphasizing that these geometric parameters optimization highly affects the BLI-blade design. The unducted BLI-propeller needs approximately 40% less shaft power than the conventional propeller to generate the same amount of propeller force. The ducted BLI-propeller needs even less power, 47%. The duct contributes to the tip vortex weakening, recovering the swirl, and turning into propeller force, as noticed from 80% of the blade span to the tip. However, the unducted and ducted BLI-configurations presented a higher backward force, 26% and 46%, respectively, compared to the conventional propeller, which can be detrimental and narrow the use of these configurations.

© 2023 by the authors.The aim of this paper is to evaluate the energy self-sufficiency of the tyre pyrolysis process using the pyrolysis gas produced as a heat source. Experimental data on the properties of the tyre and the main pyrolysis products (char, pyrolysis gas, and condensable vapours) have been compiled for a pyrolysis temperature range from 698 to 848 K. The laws of thermodynamics were used to calculate the energy demand of the tyre pyrolysis process, which was divided into heat for the pyrolysis reaction and heat transferred to the carrier gas. The pyrolysis gas was composed of 15 components, and its composition was calculated using a nonstoichiometric equilibrium model. For the temperature range studied, the heat required for the pyrolysis reaction was between 1.41 and 2.16 kJ/g of tyre. In addition, hydrocarbons (71 to 73 wt.%) were the major components in the calculated pyrolysis gas composition. An average lower heating value of 37.3 MJ/kg was calculated for the pyrolysis gas. The heat required for the tyre pyrolysis reaction was provided for burning 30–50% of the pyrolysis gas produced, thus making it self-sustaining. Energy self-sufficiency may not be achieved if the heat losses due to poor reactor insulation are high. However, this problem can be overcome by heating the combustion air using the heat released by the pyrolysis products during cooling.

© 2023 by the authors.This paper discusses the performance characteristics of a paraffin-based blend of liquid ethanol with paraffin as compared to pure paraffin in a hybrid rocket motor. Since the disclosure of the high regression rates of liquefying fuels as compared to classic fuels such as hydroxyl-terminated polybutadiene (HTPB), many studies using paraffin have been reported in the literature. Although pure paraffin regresses three to four times faster than HTPB, it is not an ideal fuel for launcher applications for the following reasons: it does not provide the optimum mechanical strength, it may suffer from combustion instability, and it offers low combustion efficiency. The proposed blend is biphasic, with drops of liquid ethanol trapped in a paraffin binder; and a nonionic surfactant was employed to emulsify the ethanol into paraffin wax. The results indicated that at a mean prefiring O∕F of 0.6 and a Gox of 60, both the P95E05 and P90E10 fuels demonstrated no significant statistical difference compared to pure paraffin in terms of thrust, specific impulse, fuel mass flow rate, characteristic velocity, and combustion efficiency. However, the P95E05 and P90E10 fuels did show damping in the pressure oscillations relative to paraffin, indicating a reduction in the low-frequency combustion instability observed in the ballistic responses of paraffin.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.Tire pyrolysis oil (TPO) shows promise as alternative fuels, not only for the raw material from which they can be produced (waste tires), but also their physical characteristics. In this work, the atomisation quality of TPO and its blends with diesel oil was evaluated from a statistical perspective. A 35 kW Y-jet atomiser, operating at an air-fuel mass ratio (AFR) in the range of 0.075 to 0.150, was used to produce the fuel sprays. The Log-Normal density function was used to describe the droplet size distribution of the sprays. Additionally, the d2-law was integrated into the density function to simulate TPO spray evaporation. The results showed that the increase in TPO in the fuel blend decreased the uniformity of droplet sizes in the spray, as well as increased the presence of larger droplets. However, operating the atomiser at a AFR = 0.150 reduced the presence of larger droplets and increased the volume fractions of smaller droplets.

© 2023, The Author(s), under exclusive licence to Springer Nature B.V.This paper is concerned with the robust guidance and control of fully actuated multirotor aerial vehicles in the presence of moving obstacles, linear velocity constraints, and matched model uncertainties and disturbances. We address this problem by adopting a hierarchical flight control architecture consisting of a supervisory outer-loop guidance module and an inner-loop stabilizing control one. The position and attitude control laws are designed using a proportional–derivative approach combined with a high-order sliding mode disturbance observer. The resulting inner-loop control strategy is arbitrarily smooth and robust (in the sliding mode sense) with respect to model disturbances and uncertainties. On the other hand, we propose a robust collision-free guidance strategy that extends the continuous-control-obstacles method to drive the vehicle to a target pose under velocity constraints, disturbances, and uncertainties, in an environment containing moving obstacles. The overall method has been numerically evaluated and shown to be effective in providing satisfactory tracking performance, collision-free guidance, satisfaction of linear velocity constraints, and computational viability. Furthermore, it is shown to outperform an analogous scheme based on the original continuous-control-obstacles method and conventional sliding mode inner-loop control laws.

© 2023 by the authors.This paper is concerned with the robust collision-free guidance and control of underactuated multirotor aerial vehicles in the presence of moving obstacles capable of accelerating, linear velocity and rotor thrust constraints, and matched model uncertainties and disturbances. We address this problem by using a hierarchical flight control architecture composed of a supervisory outer-loop guidance module and an inner-loop stabilizing control one. The inner loop is designed using a typical hierarchical control scheme that nests the attitude control loop inside the position one. The effectiveness of this scheme relies on proper time-scale separation (TSS) between the closed-loop (faster) rotational and (slower) translational dynamics, which is not straightforward to enforce in practice. However, by combining an integral sliding mode attitude control law, which guarantees instantaneous tracking of the attitude commands, with a smooth and robust position control one, we enforce, by construction, the satisfaction of the TSS, thus avoiding the loss of robustness and use of a dull trial-and-error tweak of gains. On the other hand, the outer-loop guidance is built upon the continuous-control-obstacles method, which is incremented to respect the velocity and actuator constraints and avoid multiple moving obstacles that can accelerate. The overall method is evaluated using a numerical Monte Carlo simulation and is shown to be effective in providing satisfactory tracking performance, collision-free guidance, and the satisfaction of linear velocity and actuator constraints.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Real-time fluid engineering simulations require significant computational power and high-resolution grids to ensure accuracy. This paper proposes a novel CUDA-C-based simulation algorithm nemesys that leverages GPU devices to solve the Navier-Stokes equations with precision and speed. The algorithm uses a Successive Over Relaxation (SOR) iterative process on a multi-dimensional CUDA core to accelerate solving speed. The co-located Rhie and Chow interpolation scheme is applied to unstructured grids to solve the equations using an implicit finite volume method. Benchmark simulations are performed on two problems aimed to validate the effectiveness of the proposed methodology: the classical lid-driven cavity and closed-channel flow. Results exhibit a significant advantage of the proposed method in terms of convergence rate compared to state-of-the-art techniques using varying grid resolutions and Reynolds numbers. Specifically, the strategy is nearly 850 times faster than parallel CPU-based code when utilizing an RTX 3090 Nvidia graphics card. Furthermore, the algorithm's performance is investigated on an airfoil simulation, confirming the approach's effectiveness. The findings highlight that GPU-based parallel programming is a promising approach for achieving realtime simulations, and the proposed algorithm presents a significant improvement over CPU-based techniques.

© 2017 IEEE.This letter is concerned with the collision avoidance for mobile robots with uncertain dynamics in the presence of obstacles that can considerably change their velocities over time. To address this problem, we propose a robust collision-avoidance method based on the continuous-control-obstacles one. The proposed method uses an arbitrary-order overdamped low-pass filter to generate sufficiently smooth position commands for the robot and a high-order sliding mode differentiator to robustly estimate the obstacles' maximum accelerations. Based on these estimates, we define a set of possible future positions for the obstacles according to how each one is changing its velocity to calculate a robust position command for the robot. The method has been numerically evaluated using a conventional quadcopter flying among moving obstacles and has been shown to be effective in providing collision avoidance and velocity constraints satisfaction.

© 2013 IEEE.The ability of multiple manned and unmanned aircraft systems to cooperatively engage and disable an aerial threat plays a decisive role in modern warfare scenarios. In this paper, we apply key methods to enable the so-called cooperative threat engagement capability among multiple networked agents, e.g., a swarm of drones, with combat and communication capabilities. In particular, this research combines AI-based decision-making and control techniques for a swarm of loyal wingman drones to coordinate efficient defense actions in a cooperative and autonomous manner. We apply these concepts in a defense scenario that is modeled to analyze the loyal wingman concept, which we consider an interesting testbed for cooperative decision-making and low-level control techniques. The investigated methods were implemented in a realistic 3D UAV simulator for demonstration and evaluation.

© 2023, Marcílio Alves. All rights reserved.Recent research on structural dynamics has steered towards elastic metamaterials, as band gap phenomena can be explored to mitigate vibration. A challenge in their design is the determination of configurations resulting in wider band gaps in lower frequency ranges. Since some level of damping is unavoidable in any real engineering structure, it is necessary to extend the current methodology of optimal design to provide a deeper understanding of how damping may affect the desired performance. Therefore, the main objective of this article is to propose and evaluate a numerical procedure for the optimization of band gaps in damped metamaterials. Specifically, a modified objective function that incorporates an evanescence index integral is used and two optimization schemes are implemented, each reflecting whether the structure is undamped or damped. It is shown that the optimal damped metamaterial has wider range of attenuation than the undamped optimal one, but with decreased attenuation levels. The optimization procedure is validated numerically for a finite structure, demonstrating reduced transmissibility of wave motions.

© 2023 IEEE.The paper describes the constitution of the Engineering Research Center for the Aerial Mobility of the Future (ERC-AMF) having ITA as the host institution, Embraer as the industrial partner, and researchers from the University of São Paulo and the University of Campinas. The objective of the ERC-AMF is the realization of R&D to contribute to overcoming challenges to the shaping of aerial mobility in the upcoming decades. These challenges arise from the necessity of reducing pollutant and noise emissions, and the need for increased efficiency of manufacturing processes, besides the trend of introducing in the market novel aircraft adapted for operation in urban environments and short-range travels. Five research areas are focused on the first operation phase of the Center: Machine Control for Electric Propulsion; Aeropropulsion Integration in Electric Aircraft; Methods for Decision Making in Autonomous Systems; Advanced Design for Metallic Additive Manufacturing; and Intelligent Aircraft Final Assembly. Each line will be developed by researchers from partner universities and engineers from Embraer. It is expected that the Center will contribute to the appropriation, by the Brazilian aeronautical industry, of scientific and technological knowledge generated, and, as a result, increase its preparedness to face challenges that shall be overcome in the process of shaping the aerial mobility of the upcoming decades.

© 2023 by the authors.In the presented study, a novel approach for thermal atomic layer deposition (ALD) of Al2O3 thin films using plasma-activated water (PAW) as a co-reactant, replacing traditionally employed deionized (DI) water, is introduced. Utilizing ex situ PAW achieves up to a 16.4% increase in the growth per cycle (GPC) of Al2O3 films, consistent with results from plasma-enhanced atomic layer deposition (PEALD). Time-resolved mass spectrometry (TRMS) revealed disparities in CH4 partial pressures between TMA reactions with DI water and PAW, with PAW demonstrating enhanced reactivity. Reactive oxygen species (ROS), namely H2O2 and O3, are posited to activate Si(100) substrate sites, thereby improving GPC and film quality. Specifically, Al2O3 films grown with PAW pH = 3.1 displayed optimal stoichiometry, reduced carbon content, and an expanded bandgap. This study thus establishes “PAW-ALD” as a descriptor for this ALD variation and highlights the significance of comprehensive assessments of PAW in ALD processes.

© 2023 Elsevier LtdSurface acoustic wave (SAW) sensors enhanced by a graphenic sensitive layer offer improved electrical response uniformity, and recent research has explored their potential for use in point-of-care platforms. These devices offer a unique combination of cost effectiveness, ease of handling, manufacturability, and remarkable sensor performance. This article summarizes the latest advancements in SAW sensors with graphenic-based nanomaterials, including their fabrication, operation mechanisms, and properties. Several recent studies are reviewed and compared to conventional SAW sensors. Furthermore, the challenges and prospects of using graphenic-based structures to enhance SAW devices and produce rapid actionable results are discussed.

© 2023 Elsevier B.V.In this research, a magnetic graphite nanocomposite (MGN) was synthesized by an easy and efficient hydrothermal process from magnetite nanoparticles (NP-SYN) and graphite nanoplatelets (GR). MGN was characterized by X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), N2 adsorption and desorption analysis, X-ray photoelectron spectroscopy (XPS), and point of zero charge (pHpzc) analysis. The thickness for GR was found to be 34 nm, and crystallite sizes for NP-SYN and MGN were around 37 and 48 nm, respectively. MGN shows the presence of GR and iron oxides from the NP-SYN. The surface areas for GR, NP-SYN, and MGN were around 191, 18, and 121 m2 g−1, respectively. The pHpzc results for GR, NP-SYN, and MGN ranged from 6 to 7. The NP-SYN, GR, and MGN were used as adsorbents to remove reactive black 5 (RB5) dye from aqueous solution. This method's batch removal process was designed based on a central composite rotational design (CCRD). The efficiency of RB5 uptake for all adsorbents was obtained from the quadratic model under optimum conditions of prominent parameters by desirability function (mass of adsorbent 6.6 mg, dye concentration 85.1 mg L−1, and agitation speed 902.7 rpm). Under these conditions, the adsorption capacity values were 10.16, 92.08, and 28.83 mg g−1 for NP-SYN, GR, and MGN, respectively, indicating that the adsorption power of the nanoparticle increased after incorporating GR, maintaining its magnetic properties. Therefore, the proposed adsorbents in this work have potential for removing RB5 dye from water solutions.

© 2023AlGaN thin films with different Al content were grown via reactive magnetron sputtering onto glass substrates using independent Al and Ga targets. The quality of the films was analyzed using X-ray diffraction, Raman spectroscopy, energy dispersive spectroscopy, and UV-Vis spectrophotometry. The results show that the Al content can be effectively controlled by tuning the power ratio applied to the independent targets in different absolute situations. Moreover, all produced samples presented only wurtzite structure without indication of other phases on both X-ray diffraction and Raman spectroscopy analyses. Overall, the properties of the films had a strong correlation with the composition, such as the expected blue shift of the optical bandgap and the Raman phonon modes, and the lattice cell expansion with increasing Al content. In addition, a higher c-orientation texture together with a sharper diffraction peak were observed for samples with more Al.

© 2023 by the authors.In this study, we report the use of a radiofrequency plasma-assisted chemical vapor deposition (RF-CVD) system with a hollow cathode geometry to hydrogenate anatase TiO2 thin films. The goal was to create black TiO2 films with improved light absorption capabilities. The initial TiO2 was developed through magnetron sputtering, and this study specifically investigated the impact of hollow cathode hydrogen plasma (HCHP) treatment duration on the crucial characteristics of the resulting black TiO2 films. The HCHP treatment effectively created in-bandgap states in the TiO2 structure, leading to enhanced light absorption and improved conductivity. Morphological analysis showed a 24% surface area increase after 15 min of treatment. Wettability and surface energy results displayed nonlinear behavior, highlighting the influence of morphology on hydrophilicity improvement. The anatase TiO2 phase remained consistent, as confirmed by diffractograms. Raman analysis revealed structural alterations and induced lattice defects. Treated samples exhibited outstanding photodegradation performance, removing over 45% of methylene blue dye compared to ~25% by the pristine TiO2 film. The study emphasized the significant impact of 15-min hydrogenation on the HCHP treatment. The research provided valuable insights into the role of hydrogenation time using the HCHP treatment route on anatase TiO2 thin films and demonstrated the potential of the produced black TiO2 thin films for photocatalytic applications.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.This work reports on the properties of GaN films grown by reactive magnetron sputtering onto glass substrate kept at relatively low temperature (400°C), using different RF power applied to the Ga target. Their structural, morphological, vibrational and optical properties were characterized by X-ray diffraction, atomic force and scanning electron microscopies, Raman spectroscopy and UV-vis spectrophotometry. The films have wurtzite phase with strong preferential orientation in the c-axis direction. Moreover, two clear contributions to the (0002) diffraction peak could be found, indicating the presence of two different morphologies, which were discussed in terms of the formation of an intermediate layer between the substrate and a dominating columnar-like microstructured film.

© 2023 Elsevier LtdIn the field of heat transfer, inverse problems deal with the estimation of parameters that are difficult to measure directly. The usefulness of inverse techniques is such that, due to severe conditions, direct measurement of a certain variable becomes inaccessible. This works aims to perform inverse estimation in two problems. The first case is related to the estimation of the heat flux boundary condition and thermal contact resistance between two SAE 1020 steel plates. The first case is used as validation for the second case and is solved using the finite volume method for the discretization of the diffusion equation and Successive Over Relaxation (SOR) for solving the system of linear eqs. A set of seven one-dimensional experiments were performed varying the roughness and contact pressure at the interface of the samples and, as expected, it was found that the thermal conductance is a function of these parameters. The second case consists in the estimation of three thermal resistances in an aircraft embedded system consisting of four components and ambient air. In this case, the direct problem is solved using fourth-order Runge-Kutta to solve the system of ODEs. In both cases a future times regularization technique approach combined with Markov Chain Monte Carlo (MCMC) optimization method is used to solve the inverse problem. The embedded system inverse problem is also solved using a new and simple approach based on the Quadrilateral Optimization Method (QOM) with future time steps regularization and the result is compared with the MCMC method. The results of this work consolidate a low-cost inverse estimation setup and attest to the capacity of multivariate estimation in inverse heat transfer problems.

© 2023In this work, a methodology is presented to simulate heat transfer in wellbores for plugging & abandonment operations, where the thermal input is provided by a thermite reaction. The operation of burning a thermite column inside the well's production tubing to form a metal plug is studied. The objective is to eliminate the need to simulate the thermite domain and chemical reaction during the process, simplifying the physical model and reducing computational cost. In this model, it is assumed that the thermal input from the thermite reaction is provided to the model through multiple heat flux boundary conditions along the inner wall of the production tubing. The unknown heat flux from the thermite to the inner wall of the tube is estimated by solving an inverse heat conduction problem (IHCP). The Adaptive Function Specification Method is used to estimate multiple heat flux functions at the boundary through information from multiple temperature sensors located on the outer surface along the tube's height. A characteristic behavior of the heat flux curve was verified in all segments of the tube, and the average heat flux curve was used to simulate heat transfer during a 15 m thermite burning process inside a well.

© 2023The advancement of Plug and Abandonments (P&A) procedures is pivotal for reducing the costs associated with current operations. A novel technology concept proposes a heat emitter that will produce enough energy to melt the casing steel without critically affecting the cement layer. However, recent studies concerning this proposal have not given enough attention to the potential impact on the primary cement, which is a crucial material to guarantee the plug's integrity. This study models the heat emitter as a thermite mixture with constant volumetric heat generation, and the oil well structure was approached as a 2-D axisymmetric domain. The finite volume method with a static melting/solidification model is employed to solve the governing equations numerically. A C++ code was developed and compared with the commercial software Ansys® Fluent was performed to verify the present code. The thermal parameters of the heat emitter, including density (1983.6 and 2192.4 kg m−3), specific heat (919.6 and 1016.4 J kg−1 K−1), conductivity (5 and 15 W m−1 K−1), latent heat (1267.79 and 1147.05 kJ kg−1), volumetric heat generation (104.59 and 115.6 MW m−3), and reaction time (71.25 and 78.75 s), are evaluated through a 26 factorial design. The responses analyzed are the maximum melted volume of steel and the volume of cement critically affected. The high variability associated with thermal conductivity indicated a strong dependence on this parameter. Most importantly, this study highlights that melting the casing steel could unintentionally degrade the cement layer, increasing potential leakages paths and integrity problems.

© 2023 by the authors.Implementing input parameters that match the experimental weld shape is challenging in LASER beam welding (LBW) simulation because the computed heat input and spot for temperature acquisition strongly affect the outcomes. Therefore, this study focuses on investigating the autogenous LBW of AISI 1020 using a three-dimensional heat transfer model that assumes a modified Gaussian heat flux distribution depending on LASER power (Qw), radius (R), and penetration (hp). The influence of such variables on the simulated weld bead was assessed through analysis of variance (ANOVA). The ANOVA returns reliable results as long as the data is normally distributed. The input radius exerts the most prominent influence. Taguchi’s design defined the studied data reducing about 65% of the simulations compared to a full factorial design. The optimum values to match the computed outcomes to lab-controlled experiments were 2400 W for power (80% efficiency), 0.50 mm for radius, and 1.64 mm for penetration. Moreover, the experimental errors regarding thermocouples positioning were corrected using linear interpolation. A parallel computing algorithm to obtain the temperature field reduces computational costs and may be applied in real-world scenarios to determine parameters that achieve the expected joint quality. The proposed methodology could reduce the required time to optimize a welding process, saving development and experimental costs.

© 2023, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.Welding processes are a fundamental part of modern engineering manufacturing. The simulation of materials joining techniques requires the application of thermal models capable of mathematically describing the applied heat source distribution. Many different approaches have been developed since the beginning of the CFD revolution. However, one of the most important published works regarding the review and detailing of heat source models was performed almost two decades ago. Hence, the present work was developed specifically focusing on organizing, cataloging, describing, and statistically quantifying the most relevant models already published, with a special focus on the techniques developed in the last twenty years. The reviewed approaches were individually listed concerning their most common applications and limitations. The gathered data includes classified details and condensed information about scientific references, the suitability of each model, and the welding heat source thermal modeling terminology. Additionally, each modeling form was geometrically illustrated in coupling with its equations for an enhanced description and comparison of the geometrical parameters and its expected resultant temperature distributions. The reviewed papers were quantified and statistically enumerated by modeling methodology, welding process type, and number of published works by year. The approaches were also organized chronologically and visually illustrated in a welding heat source modeling timeline. Lastly, the most relevant achievements of the last decades, the research trends, and possibilities for future review works in the field were discussed.

© 2023Recently, there was an increase in the study of phase change materials mainly due to thermal storage studies or modeling of manufacturing processes. Usually, these problems, which have a moving boundary, are solved with the enthalpy formulation. This paper presents a new methodology to address the unsteady enthalpy term in the heat diffusion equation. The Volumetric Thermal Capacitor method is developed to solve the non-linear heat diffusion equation with the enthalpy function. The alternative method applies the integration by parts rule to divide the enthalpy term into three components. This approach allows the use of non-linear thermal properties without simplifications or generalized considerations. The method is compared to the classical formulation. The routines were implemented and executed in parallel on a CUDA-C in-house code. Simulated and lab-controlled experiments validated the proposed methodology. The results highlighted the differences between the models for experiments with intense heat flux. The proposed model presented a better agreement with the experimental data than the classical model for high-temperature cases. The Volumetric Thermal Capacitor method proved to be more stable and accurate than the classical method.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Real-time fluid engineering simulations require significant computational power and high-resolution grids to ensure accuracy. This paper proposes a novel CUDA-C-based simulation algorithm nemesys that leverages GPU devices to solve the Navier-Stokes equations with precision and speed. The algorithm uses a Successive Over Relaxation (SOR) iterative process on a multi-dimensional CUDA core to accelerate solving speed. The co-located Rhie and Chow interpolation scheme is applied to unstructured grids to solve the equations using an implicit finite volume method. Benchmark simulations are performed on two problems aimed to validate the effectiveness of the proposed methodology: the classical lid-driven cavity and closed-channel flow. Results exhibit a significant advantage of the proposed method in terms of convergence rate compared to state-of-the-art techniques using varying grid resolutions and Reynolds numbers. Specifically, the strategy is nearly 850 times faster than parallel CPU-based code when utilizing an RTX 3090 Nvidia graphics card. Furthermore, the algorithm's performance is investigated on an airfoil simulation, confirming the approach's effectiveness. The findings highlight that GPU-based parallel programming is a promising approach for achieving realtime simulations, and the proposed algorithm presents a significant improvement over CPU-based techniques.

© 2022 Elsevier Masson SASA numerical-experimental methodology is presented in this study to estimate the absorption efficiency in a laser welding process by estimating the rate of energy transferred to a metal plate. The iterative Function Specification Method was modified to account for moving temperature sensor thermal sensitivity as a function of time and position relative to the welding bead. Thus, highly nonlinear problems can be solved by using a high-temperature gradient in the measurement sensor region. Three experiments on an AISI 1020 steel sheet were carried out using a 3 kW fiber laser and a 3 m/min welding speed. A thermo-fluid model was used with solid–liquid phase changes, buoyancy forces, and the Marangoni effect in the welding pool to model the physical phenomena. A code in Matlab was developed to solve the inverse problem. The direct problem was solved using COMSOL Multiphysics through the Livelink for Matlab feature. The average absorption efficiency was 79.5% for the welding process. A comparison was made between the geometry of the welding bead obtained in experiments with the numerically calculated welding bead to validate the model. The results obtained in this article are intended to assist simulations in laser welding processes and are in agreement with the literature data.

© 2023 Elsevier B.V.This work presents a novel approach for 3D scanning inspection of industrial sealed parts based on data fusion from a 2D-laser beam sensor and the motion pattern of a robotic arm. The method provides as output the 3D geometrical shape and volume of the inspected part in order to allow for automatic compliance check according to process requirements. The solution is implemented and tested in sealed riveted fasteners, which are common in the automotive and aerospace industry. The effectiveness and robustness of the method is evaluated through the comparison of the obtained results with those from a 3D laser scanner system. The evaluation campaign was performed in a noisy environment (i.e., without illumination and temperature control), representative of an industrial shop floor. Statistical analyses show the system can perform geometry prediction with an overall error of 0.340 mm and is able to reject non-compliant sealed structures with a reliability of 96.6%, confirming that the proposed method is suitable to modern collaborative robotized aerospace and automotive assembly cells.

© 2023 The AuthorsPilot training has been, for decades, aided by flight simulators with different characteristics and degrees of fidelity. However, many studies indicate that, despite the recognized contribution of simulator training, actual flying practice is still necessary, depending on the trained task. This work introduces the proposal of using augmented reality for in-flight training, where elements in the environment outside the aircraft are displayed through an augmented reality headset to create a simulation scenario. The training of basic formation flight is used as an example, as it requires flying with at least two aircraft, resulting in high operational costs and risk of collision between aircraft. In this case, the augmented reality system replaces the real leader aircraft with a projection. In order to evaluate the Technology Readiness Level (TRL) of this proposal, this work presents a prototype of an augmented reality system integrated into a flight simulator to conduct an evaluation campaign. We investigate how the introduction of the augmented reality system impacts on human factors, such as stress and workload, as well as performance. Although the results obtained in a simulated environment are not equivalent to those from an in-flight campaign, the experimental campaign performed in the flight simulator provides a way of evaluating the impact on the pilot of some aspects of the proposed solution, such as the performance of occlusion routines and some ergonomic aspects of the augmented reality headset.

© 2023 IEEE.In this work, a photorealistic virtual simulator is developed to simulate the flight dynamics of an unmanned aerial vehicle (UAV - quadcopter drone) with a camera embedded, whose photographing process can be also emulated to gather image and flight data that can be further used to point cloud generation and 3D reconstruction as in digital photogrammetry process. The system is intended to simulate the UAV-based digital photogrammetry of large structures (industrial structures, small buildings, residences). To accomplish this goal, the mathematical modeling of the dynamics of a commercial-of-the-shelf drone was developed and a flight controller was designed and verified in Matlab. Finally, the simulator is verified, generating a descriptive point cloud of an inspection mission that is virtually simulated. The 3D reconstruction of the object of analysis was properly performed in the photorealistic environment.

© 2023 IEEE.This paper discusses an approach for implementing predictive and reliability displays in aircraft manufacturing processes. The aim is to support the operator to complete all operations with quality, safety, efficient resource utilization, and on schedule. This study presents the first step of the design process to assess different ways of conveying automation information to operators. The primary goal here is to propose a first iteration that aids in future display design iterations prior to behavioral studies. Additionally, this paper presents the design and testing of a representative test demonstrator for aircraft manufacturing processes, which will be used to evaluate the effectiveness of these displays. The authors used the Human Readiness Level (HLR) framework to design the test demonstrator, considering the specific needs and requirements of the aircraft manufacturing industry. The paper presents simulation and test demonstrator results and the collected feedback from participants. The findings suggest that the test demonstrator can be a valuable tool for improving the overall efficiency of the manufacturing process. The paper contributes to the body of knowledge on the use of advanced technologies in improving manufacturing processes by providing insights into the potential benefits and limitations of predictive and reliability displays and identifying areas for further research and development.

© 2023 IEEE.The paper describes the constitution of the Engineering Research Center for the Aerial Mobility of the Future (ERC-AMF) having ITA as the host institution, Embraer as the industrial partner, and researchers from the University of São Paulo and the University of Campinas. The objective of the ERC-AMF is the realization of R&D to contribute to overcoming challenges to the shaping of aerial mobility in the upcoming decades. These challenges arise from the necessity of reducing pollutant and noise emissions, and the need for increased efficiency of manufacturing processes, besides the trend of introducing in the market novel aircraft adapted for operation in urban environments and short-range travels. Five research areas are focused on the first operation phase of the Center: Machine Control for Electric Propulsion; Aeropropulsion Integration in Electric Aircraft; Methods for Decision Making in Autonomous Systems; Advanced Design for Metallic Additive Manufacturing; and Intelligent Aircraft Final Assembly. Each line will be developed by researchers from partner universities and engineers from Embraer. It is expected that the Center will contribute to the appropriation, by the Brazilian aeronautical industry, of scientific and technological knowledge generated, and, as a result, increase its preparedness to face challenges that shall be overcome in the process of shaping the aerial mobility of the upcoming decades.

© 2021 by Antônio B. Guimarães Neto, Guilherme C. Barbosa, Juliano A. Paulino, Rafael M. Bertolin, Jéssica S. M. Nunes, Pedro J. González, Flávio L. Cardoso-Ribeiro, Maurício A. V. Morales, Roberto G. A. da Silva, Flávio L. S. Bussamra, Flávio J. Silvestre, Fernando J. O. Moreira, and Carlos E. S. Cesnik. Published by the American Institute of Aeronautics and Astronautics,.The challenges of modeling flexible aircraft include appropriate fidelity capturing and validation with experimental data. In fact, the validation of formulations and models for the flexible flight dynamics is indispensable to ensure that all the important phenomena are correctly captured. With this objective, two high-aspect-ratio flexible aircraft have been flight-tested, and coupled aeroelastic–flight dynamics data have been collected to support model validation. Additional ground vibration and static tests were carried out to fully characterize the structural dynamic properties. Numerical models were built based on a linear structural representation but with geometrically nonlinear aerodynamics. Low Reynolds number effects were included in a simplified way with lookup tables of two-dimensional airfoil data. Wing-tip effects were considered via the vortex-and doublet-lattice methods. Propulsive data were obtained with wind-tunnel tests. This paper describes the numerical models, the two aircraft, and their instrumentation and presents the data collected from the aircraft sensors during flight tests. Numerical and experimental results are compared for angular velocities, accelerations, and strains measured at different points of the aircraft. Despite its limitations and simplifications, the numerical model captures the real aircraft main aeroelastic and flight dynamic behaviors.

© The Author(s) 2021.This work presents the experimental determination of fracture mechanics parameters of composite specimens manufactured by fused filament fabrication (FFF) with continuous carbon fiber reinforced thermoplastic filaments, based on Linear Elastic Fracture Mechanics (LEFM). The critical mode I translaminar fracture toughness (KIc) and the critical energy release rate (GIc) are found for unidirectional and cross-ply laminates. The specimens were submitted to quasi-static tensile testing. Digital Image Correlation (DIC) is used to find the stress field. The stress fields around the crack tip are compared to linear elastic finite element simulations. The results demonstrate the magnitude of fracture toughness is in the same range as for polymers and some metals, depending on lay-up configuration. Besides, fractographic analyses show some typical features as river lines, fiber impression, fiber pulls-out and porosity aspects.

© 2021 by Antônio B. Guimarães Neto, Guilherme C. Barbosa, Juliano A. Paulino, Rafael M. Bertolin, Jéssica S. M. Nunes, Pedro J. González, Flávio L. Cardoso-Ribeiro, Maurício A. V. Morales, Roberto G. A. da Silva, Flávio L. S. Bussamra, Flávio J. Silvestre, Fernando J. O. Moreira, and Carlos E. S. Cesnik. Published by the American Institute of Aeronautics and Astronautics,.The challenges of modeling flexible aircraft include appropriate fidelity capturing and validation with experimental data. In fact, the validation of formulations and models for the flexible flight dynamics is indispensable to ensure that all the important phenomena are correctly captured. With this objective, two high-aspect-ratio flexible aircraft have been flight-tested, and coupled aeroelastic–flight dynamics data have been collected to support model validation. Additional ground vibration and static tests were carried out to fully characterize the structural dynamic properties. Numerical models were built based on a linear structural representation but with geometrically nonlinear aerodynamics. Low Reynolds number effects were included in a simplified way with lookup tables of two-dimensional airfoil data. Wing-tip effects were considered via the vortex-and doublet-lattice methods. Propulsive data were obtained with wind-tunnel tests. This paper describes the numerical models, the two aircraft, and their instrumentation and presents the data collected from the aircraft sensors during flight tests. Numerical and experimental results are compared for angular velocities, accelerations, and strains measured at different points of the aircraft. Despite its limitations and simplifications, the numerical model captures the real aircraft main aeroelastic and flight dynamic behaviors.

© 2023 by the authors.In this study, Plasma-Activated Water (PAW) was synthesized using a coaxial Dielectric Barrier Discharge (DBD) reactor, benefiting from the elevated capacity of air-flow-assisted DBD discharges to enhance nitrogen-based species concentration. By manipulating operational parameters, including gas flow rate, activation time, and DI water volume, we achieved significant concentrations of reactive oxygen and nitrogen species (RONS). As a result, the PAW obtained displayed pronounced physicochemical attributes: a pH of 2.06, an ORP of 275 mV, conductivity of 3 mS/cm, and TDS of 1200 mg/L. A pivotal aspect of this research was the evaluation of the reactor’s efficiency, as indicated by metrics like the specific input energy and ozone efficiency yield. The antimicrobial potential of the PAW was also assessed against pathogenic microbes, with remarkable reductions in viability for both Staphylococcus aureus and Escherichia coli (99.99%) and a more moderate decrease for Candida albicans (37%). These findings underscore the capability of coaxial DBD reactors in crafting high-quality PAW with significant antimicrobial properties, necessitating further studies to validate its broad-spectrum and safe applications.

© 2023, The Author(s), under exclusive licence to the Korean Fiber Society.This work presents permethrin (15%)-based monomers polymerisation in polyamide fabrics using hybrid corona–dielectric barrier discharge (DBD) to potentiate insect–parasite repellency functionalities in polyamide fabrics. First of all, the electric characterisation of the discharge was made using the Lissajous figure method for determining the plasma dosage (2841 W min m−2). Before the polymerisation process, the polyamide fabric was activated by DBD discharge, operating at 23 kHz and voltage amplitude of 12.5 kV in atmospheric pressure. After that, the polymerisation process is initiated by injecting permethrin into the system, maintaining the operational parameters used in the activation process. The non-activated and activated polyamide fabrics measured the static and dynamic contact angle, showing a variation from 120° (non-activated) to 34° (immediately after plasma activation). The chemical structure of synthesised permethrin was evaluated by Fourier transformed infrared (FTIR) spectroscopy to confirm the polymerisation (deposition) of permethrin on the fabric surface; it is possible to observe the 648 cm−1 bands that are associated with asymmetric vibration of the C–Cl bonds, but most evident change occurs at 1045 cm−1, which is associated with cyclopropyl group vibrations. Field emission scanning electron microscopy (FESEM) analysis was used to evaluate the possible degradation of the fabric surface when exposed to plasma activation and the homogeneity of the permethrin coating in the fibres after the polymerisation. The energy dispersive spectrometer (EDS) was used to confirm the polymerisation and the distribution of the permethrin in the fabric.

© The Author(s) 2022.As a major international public health emergency, COVID-19 has posed many challenges for healthcare professionals who have been heavily exposed to contamination. This article describes the development of a high-filtration capacity mask consisting of filter-element layers interspersed with super-activated carbon fiber fabric, non-woven polypropylene for dental–medical–hospital use and antiviral polyamide with nanostructured SiO2 thin film coating. The study found 98.18% particle filtration efficiency and determined 2.11 mmH2O/cm2 differential pressure, while fluid repellency complied with Brazilian standard NBR ABNT 15052:2004.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.In this work, a thermal plasma-based ablation test system was used to evaluate the ablative performance of the EPDM composite. The system produces a high enthalpy plasma jet generated by a plasma (DC) torch, operating at atmospheric pressure using compressed air as working gas, enabling the variation of the thermal flux concerned with the studied EPDM composites. The samples were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Fourier-Transform Infrared spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) to investigate the morphology, mass-loss rate, the reaction layer (char formation), and chemical changes of the samples for each thermal flux. For a complete evaluation, the thermal fluxes were varied in 0.30, 0.45, 0.60, 0.75, and 0.90 MW/m2 and for each thermal flux, disk-shape samples remained exposed to the plasma jet for 10s. During the plasma jet exposure time, the temperatures of the surface and the back of the samples were collected to verify the formed char layer’s insulator capacity and the samples’ thermal diffusivity for each experimental condition. The mass loss is continuous under the thermal fluxes of 0.30 and 0.45 MW/m2, stabilizing at 60% until 0.75 MW/m2. The formed char layer begins to lose its protective capacity, evidenced by the size decrease (from 800 µm to 700 µm), due to the ablation process of the reaction layer from the thermal flux of 0.90 MW/m2

© 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Thermal plasma-assisted processing is an effective process for the synthesis of gas (CO and H2) and carbonaceous materials production from industrial waste. In this paper, a DC plasma torch designed with two vortices chambers has been developed, and its characteristics have been experimentally tested. The plasma torch operates with different plasma working gases, including steam. The results of coal tar pitch (CTP) processing will be presented as a possible ecological application. CTP is a waste from the steel industry mainly composed of polycyclic aromatic hydrocarbons. The experimental results will be discussed with thermodynamic calculations and numerical simulation of the heat and mass transfer in the DC plasma torch and the chemical reaction chamber. The simulations were carried out to clarify the regions of gas flow and temperatures for producing synthesis gas and carbon nanomaterial. The results enable one to predict the produced gas composition and carbon nanomaterial properties. The physicochemical properties of carbon nanomaterial and synthesis gas show high efficiency in converting CTP into high-value-added products.

© 2022 Society.This is an experimental study on the decolorization efficiency and the degradation of organic compounds from textile wastewater by the ozonation process in a batch system. The effects of different sample volumes of textile wastewater over time were investigated. The experiments were performed in a 1 L glass reactor with a magnetic stirrer and a bubble diffuser at the bottom to feed the ozone. The applied cumulative ozone dosage varied at 120 gO3 L−1, 60 gO3 L−1, and 30 gO3 L−1, and the total interaction time for each test was 1 h. To investigate the physicochemical properties of the textile wastewater (solid and liquid phases) before and after the treatment, multiple analytical characterization methods were used: Thermal Gravimetric Analysis, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, and Spectrophotometer. The most perceptive change was observed in the color of the liquid medium, which turned from black to transparent, and a visual color number indicator known as DurchsichtFarbZahl (DFZ) was used for the evaluation of this process. Absorbance values decreased about 3.5 times after 5 min of treatment with a 0.15 L sample volume, and these values differed for tests with larger sample volumes. FTIR spectroscopy demonstrated that the bands’ intensities associated with the C − H, C − N, and C − O decrease during treatment. On the other hand, it was possible to conclude that combining treatment methods to improve the degradation of persistent compounds after the ozonation process is necessary. Finally, the ozonation of the textile wastewater proved to be effective at removing color due to its high reaction capacity.

© 2021 Informa UK Limited, trading as Taylor & Francis Group.The processing of coal tar pitch (CTP) to produce clean fuel gas and carbon black (CB) is studied in a plasma reactor equipped with a direct-current plasma torch. The composition of the gas produced and energy costs were estimated theoretically for the CTP pyrolysis and gasification processes by two oxidants, namely oxygen and water vapor. We have found that the main gaseous compounds obtained in the pyrolysis and gasification processes are hydrogen (H2), carbon monoxide (CO), and very often carbon dioxide (CO2). For the pyrolysis case, the mean value of the synthesis gas concentration reaches a major value of 98 vol.% (H2–81 vol.%, CO–17. vol.%). However, only 23% of the initial CTP is transformed into gas phase at 1100 K and its content increases up to 37.4% at a temperature of 3000 K. For oxygen gasification, the syngas quantity is little less compared to the pyrolysis case and attains 96.6 vol.% (H2–26.5 vol.%, CO–70.1 vol.%) for T > 1100 K. An intermediate syngas content for the water steam gasification is 97.8 vol.% (with H2–55.8 vol.% and CO–42.0 vol.%). The CB produced was composed of well-defined spherical particles of 30-nm size. Furthermore, it is composed of carbon (98.2%), and followed by oxygen (1.8%) with a surface area of 97 m2 g−1. The thermal plasma system shows high efficiency in conversion of CTP into high-value-added products.

© 2023In this work, our original glycol thermal method was applied to obtain borate bioactive glasses of the 45B5 composition (46.1 B2O3 – 26.9 CaO – 24.4 NaO – 2.6 P2O5, mol%) doped with therapeutic ions Co2+, Cu2+, and Zn2+ aiming toward wound healing applications. The structural analysis performed demonstrated the successful vitreous network obtention, while the apatite mineralization assay exhibited fast conversion into hydroxyapatite (HA, Ca5(PO4)3(OH)). Cell viability findings performed with human keratinocytes revealed an absence of cytotoxicity at concentrations below 0.5 mg/mL at day 1, manifested after 3- and 7-days, demonstrating a time- and dose-dependence in vitro outcome. The inhibition halo assay confirmed the antibacterial activity of all glasses against S. aureus. Considering the set of properties evaluated (i.e., bioactivity, cytocompatibility, and antibacterial activity), the synthesized glasses demonstrate potential for wound healing applications when incorporated into nanofibers, hydrogels, and dermal patches.

© 2023 Elsevier LtdSurface acoustic wave (SAW) sensors enhanced by a graphenic sensitive layer offer improved electrical response uniformity, and recent research has explored their potential for use in point-of-care platforms. These devices offer a unique combination of cost effectiveness, ease of handling, manufacturability, and remarkable sensor performance. This article summarizes the latest advancements in SAW sensors with graphenic-based nanomaterials, including their fabrication, operation mechanisms, and properties. Several recent studies are reviewed and compared to conventional SAW sensors. Furthermore, the challenges and prospects of using graphenic-based structures to enhance SAW devices and produce rapid actionable results are discussed.

© 2023, The Polymer Society, Taipei.Due to their extraordinary properties, functionalized carbon nanotubes (CNTs) have been added to epoxy matrices. In the marine industry, CNT/epoxy composite is applied in current turbines to obtain energy. For this, it is fundamental to understand the nanocomposites’ seawater absorption process. Therefore, this work aims to study how amino-functionalized CNTs and epoxy’s post-cure reaction influences the nanocomposites’ seawater absorption. The nanocomposites were prepared with ethylenediamine functionalized CNTs (0.25 wt%). Part of the samples was exposed to a post-cure treatment and artificial seawater for 504 days, accompanied by mass measurement. Then, the percentage of water absorbed throughout the period was obtained, and the post-cured samples absorbed the highest water amount, as well as showed the highest values of the glass transition temperature. The action of water as a plasticizer or pseudo-curing agent was observed by luminescence spectroscopy. Additionally, the three-point bending test showed that the highest modulus of elasticity was presented by the post-cured nanocomposites exposed to water, which also presented fracture with little plastic deformation, while the equivalent sample without the presence of CNT showed significant plastic deformation. Thus, since the marine industry requires materials with high bending forces, the amino-CNT/epoxy nanocomposites are suitable for this application.

© 2023 Elsevier Ltd and Techna Group S.r.l.The present work reports the development and application of potassium niobate (KNbO3) as a catalyst in a novel hybrid piezophotocatalytic ozonation process aimed at wastewater remediation. Pure KNbO3 samples were produced through a simple solid-state synthesis using water-soluble ammonium niobate (V) oxalate hydrate (C4H4NNbO9·xH2O) as niobium source, employing different potassium precursors (KNO3, K2CO3, KOH, and C8H5KO4). The synthesis was also carried out using powdered niobium oxide as a precursor, aiming to evaluate the differences between the niobates obtained. The results achieved in this study show that all the niobates produced using ammonium niobate (V) oxalate hydrate were composed solely of the orthorhombic structure of KNbO3, while the materials synthesized using niobium oxide exhibited the rhombohedral structure of KNbO3 along with niobium-rich potassium niobates (K3Nb8O21, K2Nb4O21, and KNb3O8) and residual niobium oxide. This behavior was attributed to the enhanced chemical homogeneity derived from the synthesis using ammonium niobate (V) oxalate hydrate, which facilitated the reaction between the components during the thermal treatment step. Furthermore, the optical and morphological properties of the niobates were considerably influenced by the application of different potassium salts. Owing largely to its morphological and electrical properties, the material synthesized using potassium hydrogen phthalate displayed the highest photocatalytic activity in terms of methylene blue discoloration among the niobates produced using C4H4NNbO9·xH2O. Finally, the proposed piezophotocatalytic ozonation process was found to be a highly efficient strategy for the discoloration of methylene blue, as it successfully harnessed the synergy between the multiple mechanisms involving active radical generation toward the development of a highly promising hybrid advanced oxidation process.

© 2023 Elsevier B.V.This work explored the development of C-Nb2O5 materials through the use of kraft lignin/cellulose carbon xerogel as a structure-directing agent in a simple precipitation synthesis pathway. This strategy was based on xerogel's low-cost and environmentally friendly nature, as well as the lignin's ability to promote structural changes through the chelation of metallic ions and stabilization of crystalline phases. The results showed that the addition of higher quantities of the kraft lignin/cellulose xerogel during the synthesis resulted in the formation of the hexagonal crystalline structure of niobium oxide, whereas the synthesis without the carbonaceous phase led to hexagonal K3NbO2F4 structure. The presence of the carbon xerogel also led to significant morphological changes, such as the formation of rod-like particles with smaller sizes and the augmentation of the specific surface area and pore volume. EDS and XPS show that the hexagonal Nb2O5 obtained was also doped with K and F atoms. The addition of the carbonaceous phase also led to the reduction of the bandgap energy of materials, whereas an increase in the calcination temperature caused a similar bandgap reduction. The material with the highest carbon content (Nb-0.25L) achieved the highest photoresponse under simulated solar light for the simultaneous photodegradation of methylene blue (MB) and photoreduction of Cr (VI), probably due to its lower bandgap energy, higher surface area, and enhanced methylene blue adsorption capacity. The effect of the calcination temperature implied that dye sensitization was an important factor for the Cr (VI) photoreduction, as faster MB degradation rates led to the suppression of Cr (VI) reduction. Finally, the study of the pH effect on the process showed that higher MB adsorption capacities are linked to higher MB removal rates, which coupled with mechanistic evaluation, proves that MB photodegradation is mainly linked to the direct oxidation reaction promoted by photogenerated vacancies.

© 2022 by the authors.The efficient remediation of the persistent organic pollutant known as 4-chlorophenol (4CP) in aqueous effluent presents a challenge for a wide array of industries due to its elevated toxicity and resistance to natural degradation processes. This study proposes the development of a hybrid photocatalyst composed of titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4), aiming to increase the efficiency of photocatalytic degradation of 4CP under solar and visible radiation through the formation of Z-scheme heterojunction between the semiconductors. The results showed that the synthesis of the TiO2/g-C3N4 binary material was successful by X-ray diffractometry and infrared spectrometry. Furthermore, the addition of g-C3N4 to TiO2 led to optical and morphological modifications, such as the pore volume increase and gap energy of TiO2/g-C3N4. Concerning the photocatalytic evaluation, the main results indicate that photocatalytic activity under visible radiation of the TiO2/g-C3N4 improved by 44.8% compared to pure TiO2, whereas an improvement of 30.5% was obtained under simulated solar radiation. This improvement in efficiency was further corroborated by chronoamperometry tests, which demonstrated a higher photocurrent generation for the TiO2/g-C3N4. The radical generation mechanism suggested the creation of an effective Z-scheme heterojunction between the semiconductors, as the formation of both hydroxyl and superoxide radicals was observed.

© 2023 The Author(s)This work proposed the study of a new lignin/cellulose carbon xerogel/ZnO/Bi2O3/Bi° composite photocatalyst for the degradation of bisphenol-A under sunlight. The reasoning behind the application of each component is based on the formation of multiple heterojunctions (p-n heterojunction between semiconductors, metal-semiconductor heterojunction, and carbon-semiconductor heterojunction) to hinder the recombination of photogenerated charges during the photocatalytic process. The lignin/cellulose carbon xerogel was employed as both a solid electron mediator and a reducing agent, promoting the reduction of the bismuth oxide into metallic bismuth. The results obtained from the characterization tests confirm the formation of all the intended phases in the hybrid photocatalyst. Furthermore, the inclusion of the carbon xerogel led to morphological modifications such as the formation of plate-like particles and the increase of specific surface area. The efficient formation of the heterojunctions between the composing phases of the hybrid composite led to an enhanced photocatalytic activity for the degradation of the bisphenol-A (BPA) molecule, under both simulated sunlight and visible light. The optimized composite achieved 84% degradation of the BPA under simulated sunlight and 27% under visible light irradiation, which is a great improvement in comparison to the pure ZnO, which obtained 55% degradation under simulated sunlight and 19% degradation under visible light. The enhanced photocatalytic activity of the lignin/cellulose carbon xerogel/ZnO/Bi2O3/Bi° composite was further verified by chronoamperometry tests, which evidenced its greater photocurrent generation capabilities.

© 2023 by the authors.The objective of this study was to investigate the osteogenic and antimicrobial effect of bioactive glass S53P4 incorporated into β-tricalcium phosphate (β-TCP) scaffolds in vitro and the bone neoformation in vivo. β-TCP and β-TCP/S53P4 scaffolds were prepared by the gel casting method. Samples were morphologically and physically characterized through X-ray diffraction (XRD) and scanning electron microscope (SEM). In vitro tests were performed using MG63 cells. American Type Culture Collection reference strains were used to determine the scaffold’s antimicrobial potential. Defects were created in the tibia of New Zealand rabbits and filled with experimental scaffolds. The incorporation of S53P4 bioglass promotes significant changes in the crystalline phases formed and in the morphology of the surface of the scaffolds. The β-TCP/S53P4 scaffolds did not demonstrate an in vitro cytotoxic effect, presented similar alkaline phosphatase activity, and induced a significantly higher protein amount when compared to β-TCP. The expression of Itg β1 in the β-TCP scaffold was higher than in the β-TCP/S53P4, and there was higher expression of Col-1 in the β-TCP/S53P4 group. Higher bone formation and antimicrobial activity were observed in the β-TCP/S53P4 group. The results confirm the osteogenic capacity of β-TCP ceramics and suggest that, after bioactive glass S53P4 incorporation, it can prevent microbial infections, demonstrating to be an excellent biomaterial for application in bone tissue engineering.

© 2022 Elsevier Ltd and Techna Group S.r.l.This work was performed aiming to develop a new and straightforward route for bioactive glasses obtention with minimal equipment and explore the structural, physical, and bioactivity properties of the resulting glass and its glass ceramics. Herein, the synthesis of the borate bioactive glass in the 45B5 composition (46.1 B2O3 – 26.9 CaO – 24.4 NaO – 2.6 P2O5, mol%) by the glycol thermal method was proposed; an original chemical route for bioactive glass obtention based on transesterification reaction between the precursors with a glycol. The suggested mechanism for the borate network formation was proven accurate, revealing a vitreous structure formed by ring-type metaborate structural units with a lamellar morphology upon calcination. Glass-ceramics obtained at 500 (45B5-500) and 700 °C (45B5-700) indicate the oxides were effectively incorporated into the network by crystallization of Ca–Na–B, Ca–B, and Na–B phases. The in vitro apatite mineralization assay performed on the glass and glass-ceramics revealed their great solubility and conversion rate into hydroxyapatite (HA, Ca5(PO4)3(OH)), which is taken as an indication of bioactivity. Besides HA, however, calcium carbonate species were identified at the early stages of mineralization for 45B5 and 45B5-500, suggesting the 45B5-700 glass-ceramic has a higher ability to form apatite as the majority of Ca2+ are directed to precipitate into hydroxyapatite. Overall, the 45B5 glass and glass-ceramics demonstrated their great bioactivity, having high application potential in soft tissue engineering on wound healing materials and devices, as incorporation in hydrogels and nanofibers. Furthermore, the glycol thermal method generated new perspectives for the synthesis of a broad range of bioactive glasses compositions and their application in tissue engineering.

© 2022 Elsevier B.V.This work proposed new black-wattle tannin/kraft lignin H3PO4-activated carbon xerogels as sustainable and efficient adsorbents. The precursors were chosen based on their eco-friendly and cost-effective nature, aiming to achieve adsorbents with high adsorption capacities. Carbon xerogels were synthesized through polycondensation with formaldehyde and alkaline catalyst in a simple one-pot procedure. Activation was performed using H3PO4 in a tubular furnace (500 °C), under a nitrogen atmosphere. Results show that the inclusion of the kraft lignin led to changes in the morphology of the materials, facilitating the development of their porous structure and increasing specific surface area and pore volume. The best adsorbent (XLT 50 %) was synthesized using a 1:1 tannin/kraft lignin mass ratio. This material presented an adsorption capacity of nearly 1150 mg g−1 of methylene blue (pH = 5 and T = 298 K), which was linked to its high specific surface area of 1348 m2 g−1. The adsorption process followed the pseudo-second-order kinetic model, whereas the adsorption isotherms were best fitted by the Sips model. The XLT 50 % presented good reusability properties, maintaining its adsorption capacity for 3 cycles. Finally, the XLT 50 % presented good adsorptive properties toward other pollutants (methyl orange, 4-chlorophenol, and hexavalent chromium), indicating its versatility for adsorption processes.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.Bacterial infections after implant surgical procedures are a complication observed in many surgeries to treat bone injuries or diseases. Bacteria can attach to the surface of the implant producing biofilms, and if treatment with antibiotics does not work, further surgery is necessary to remove the infected implant. Among the biomaterials for bone implants, bioceramics based on calcium phosphates (CaPs) such as β-TCP stand out, due to their chemical similarity with bone and high bioresorbability. β-TCP has the characteristic of easily accommodating in its crystalline structure reasonable amounts of doping elements, such as monovalent and trivalent ions, which makes it an efficient transporter of drugs, molecules, and therapeutic ions The objective of this work was the incorporation of bioactive glass (BG 45S5) via sol-gel and silver nanoparticles (Ag-NPs) in β-TCP scaffolds, aiming to confer antimicrobial activity to the scaffolds, without prejudice to biocompatibility. XRD and FT-IR analysis indicated structural changes after the incorporation of BG 45S5 and Ag-NPs in β-TCP scaffolds, and these compounds induced the partial transformation of the β-TCP phase into α-TCP phase and the formation of sodium-calcium silicates and silver silicates. The FT-IR spectra showed characteristic bands of α-TCP after incorporation, in addition to the predominant bands of β-TCP. Biocompatibility after incorporation of BG 45S5 was improved, with a significant increase in cell viability. After the incorporation of Ag-NPs, cell viability was maintained at an acceptable level, no cytotoxic behavior was observed, and the scaffolds showed antibacterial and antifungal activity. The results indicate that BG 45S5 and the Ag-NPs incorporated showed a synergistic behavior, conferring antimicrobial activity to the scaffolds without compromising biocompatibility, showing great potential for applicability in tissue engineering.

© 2023, Faculdade de Odontologia de Bauru da Universidade de Sao Paulo. All rights reserved.The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.

© 2022 Wiley Periodicals LLC.The objective was to synthesize and characterize fine polycaprolactone (PCL) fibers associated with a new 58S bioglass obtained by the precipitated sol–gel route, produced by the electrospinning process in order to incorporate therapeutic ions (Mg and Li). In PCL/acetone solutions were added 7% pure bioglass, bioglass doped with Mg(NO3)2 and Li2CO3 and were subjected to electrospinning process. The fibers obtained were characterized morphologically, chemically and biologically. The results showed the presence of fine fibers at the nanometric scale and with diameters ranging from 0.67 to 1.92 μm among groups. Groups containing bioglass showed particles both inside and on the surface of the fibers. The components of the polymer, bioglass and therapeutic ions were present in the fibers produced. The produced fibers showed cell viability and induced the formation of mineralization nodules. It was observed the applicability of that methodology in making an improved biomaterial, which adds the osteoinductive properties of the bioglass to PCL and to those of therapeutic ions, applicable to guided bone regeneration.

© 2023 Elsevier LtdScramjet engines, also known as supersonic combustion ramjet engines, are frequently regarded as a compelling alternative for launching payloads into Earth's orbit. These air-breathing engines have streamlined designs with minimal movement of components. However, the successful design of scramjet engines necessitates overcoming various challenges such as managing the high heat fluxes and pressure loads exerted on the engine walls. Additionally, addressing issues such as shockwave-boundary-layer interactions and the potential occurrence of choked flow within the isolator channel are critical considerations during the scramjet design process. Therefore, this study aims to evaluate sidewall compression in the isolator region to deal with the high heat fluxes and pressure loads inside the scramjet isolator. In addition, this work also investigates how the variation in the angle of attack influences the mass flow rate of the intake and at which range of the angle of attack the intake becomes choked. The CFD analyses include contour images of properties such as Mach number, total pressure, heat flux, and pressure distribution on the walls, and the calculation of performance parameters, including the analysis of the second law of thermodynamics. The study involved varying the compression angle within the range of 4° to 10°. The results of this study demonstrate that implementing sidewall compression in the isolator region allows for the effective management of the position of the heat flux and pressure peaks on the upper wall of the isolator. Regarding the pressure distribution along the upper wall of the isolator, the 10°case presented a pressure peak of approximately 130000 Pa while the 4°case presented 155000 Pa. In addition to this significant decrease in the pressure peak value, its location also changed, with an increase of approximately 8 mm downstream of the isolator by decreasing the compression angle from 10° to 4°. This engineering approach presents a viable solution for mitigating the challenges posed by high heat flux and pressure loads in the intake section. The cost of applying such a solution is to decrease the intake performance – a decrease of approximately 30 % in the isentropic efficiency when comparing a case with no sidewall compression with the sidewall compression cases. In the choked flow study, angles of attack ranging from 4 to 30°were considered. The analysis shows that the choked-flow condition gradually occurs as the angle of attack increases beyond 4°, owing to the shock-on-lip condition. The results at approximately 20° indicate that the isolator becomes completely choked once the mass flow rate abruptly decreases – from around 0.30 to 0.15 Kg/s when comparing the 20°-of-AoA case with the 30° one. This work aims to contribute to the early phase of engine design by avoiding critical failures in the scramjet structure owing to aerodynamic load, thermal stress, and engine unstart.

© 2023The advancement of Plug and Abandonments (P&A) procedures is pivotal for reducing the costs associated with current operations. A novel technology concept proposes a heat emitter that will produce enough energy to melt the casing steel without critically affecting the cement layer. However, recent studies concerning this proposal have not given enough attention to the potential impact on the primary cement, which is a crucial material to guarantee the plug's integrity. This study models the heat emitter as a thermite mixture with constant volumetric heat generation, and the oil well structure was approached as a 2-D axisymmetric domain. The finite volume method with a static melting/solidification model is employed to solve the governing equations numerically. A C++ code was developed and compared with the commercial software Ansys® Fluent was performed to verify the present code. The thermal parameters of the heat emitter, including density (1983.6 and 2192.4 kg m−3), specific heat (919.6 and 1016.4 J kg−1 K−1), conductivity (5 and 15 W m−1 K−1), latent heat (1267.79 and 1147.05 kJ kg−1), volumetric heat generation (104.59 and 115.6 MW m−3), and reaction time (71.25 and 78.75 s), are evaluated through a 26 factorial design. The responses analyzed are the maximum melted volume of steel and the volume of cement critically affected. The high variability associated with thermal conductivity indicated a strong dependence on this parameter. Most importantly, this study highlights that melting the casing steel could unintentionally degrade the cement layer, increasing potential leakages paths and integrity problems.

© 2023 by the authors.The ability to treat saltwater to make it suitable for human consumption has long been sought by mankind. More than three-quarters of the earth’s surface is covered with saltwater. Although this water is important for some forms of transportation and fishing, it contains too much salt to sustain human life or agricultural activities. The current work consists of building a low-cost solar still and numerically modeling this device to predict the performance of the solar still without using any experimental measurements. The simulated results were compared with the best experimental values obtained from the water-covering temperatures and desalinated water yield under Brazilian climatic conditions (coordinates: 23°26′31.344″ S and 46°27′27.468″ W). The simulation results were in acceptable agreement with the experimental data. The main results obtained indicate that the solar still has greater efficiency when the volume of water is smaller inside the equipment owing to the lower height of the water and when the global radiation has greater intensity. In addition, numerical modeling allows the analysis of the behavior of the volume fraction over time for water and vapor and indicates better performance in water production after 30 min.

© 2023 Elsevier LtdIn this study, the characteristics, penalties, gains, and challenges in the electrification and hybridization process for long-range aircraft were investigated. A system and mission analysis was conducted on thermodynamics and cost. A reference aircraft was compared with other more-electric and hybrid-electric versions of the same type. These latter versions may carry batteries to supply the aircraft system and/or engine. A state-of-the-art propulsion and system architecture were also implemented in these innovative aircraft. A full factorial analysis was conducted to vary the battery energy density and the hybridization ratio for the hybrid configurations. A typical mission profile was developed to match the boundary conditions in all cases. The hybrid powertrains were confirmed in our results as exhibiting superior behavior compared to those of the other cases. The least efficient hybrid configuration, which employed an intermediate battery choice, reduced fuel consumption by 10.7% in the conventional aircraft and by 1% in the battery-powered more-electric type. Moreover, both baseline models were surpassed by the worst intermediate-battery hybrid aircraft by 3.6% and 1% in terms of overall mission exergy efficiency. Considering the actual low density of batteries available on the market, long-range hybrid-electric aircraft will require substantial time to become viable.

© 2023 International Committee on Composite Materials. All rights reserved.The transport sector has long had a demand for weight reduction, typically achieved by changing materials or reducing part thickness. Steel and aluminum are the primary materials used in this sector. However, advancements in Fiber Reinforced Polymers (FRPs) technology have allowed for their application in non-structural parts of commercial vehicles and airplanes. The challenge is applying FRPs to structural parts while satisfying requirements for structural performance, quality, and production rate. To achieve both, the manufacturing processes involved must be carefully investigated, including the machining process. This work presents an experimental milling approach to investigate six factors' influence on the quality and production rate of a unidirectional CFRP part. The experiments were conducted using a traditional milling machine tool and a robot-based milling cell. The main objective is to achieve maximum material removal while maintaining defined part quality parameters.

© 2023 by ASME.Evaporative cooling systems are commonly used in thermoelectric plants to cool the air at gas turbines inlet, improving the performance of these engines. Normally, the evaporative cooling is modeled as adiabatic saturation and, in this case, the water-air equilibrium temperature depends only on the atmospheric air properties. However, other factors such as the water temperature that supplies the equipment and the ratio between the mass flow rates of water and air, also affect the equilibrium conditions of these systems. This work presents three methodologies to calculate the air temperature in equilibrium state, considering all the factors mentioned. The methodologies were implemented in a computer program written in FORTRAN. In all cases tested, the results obtained by the three models showed high convergence. As an example, for 70 different sets of inputs, the absolute and relative differences of the results were below 0.3236°C and 1.2480%, respectively. A statistical study, also on this sample of results, revealed that, for a confidence level of 99%, the hypothesis of the equivalence between the methods cannot be rejected.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Correction Notice Reference 5 should be: L. Vesely, J. S. Kapat, C. Bringhenti, J. T. Tomita, M. F. Stoia, and K. Jui, “sCO2 Waste Heat Recovery System for Aircraft Engines,” AIAA 2022-1407. AIAA SCITECH 2022 Forum. January 2022. doi: https://doi.org/10.2514/6.2022-1407.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.The present work investigates the effect of reordering the nodes and elements of a grid according to the Hilbert curves on the cache utilization in an in-house parallel CFD code. A sorting algorithm is proposed based on domain decomposition techniques and the execution times are compared to those obtained by the structured grid format.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Waste Heat Recovery is one of the key pathways to achieving reduced emissions and improving system efficiency. The Waste Heat Recovery (WHR) may be used to convert the waste energy to electric power by using a bottoming cycle. One of the potential bottoming cycles for aircraft application is a Supercritical CO2 (sCO2) power system. The sCO2 power system has advantages because of the component compactness, which is a key factor for aircraft integration. The present work focuses on the performance of the Supercritical CO2 power system in both the current and the next-generation aircraft engines considering the techno-economic evaluation of the bottoming cycle. The techno-economic evaluation needs to consider bottoming cycle integration and potential fuels, such as hydrogen, ammonia, or sustainable aviation fuel (SAF). The first part of the work is focused on the analysis of the sCO2 WHR system for an aircraft engine. The second part of the work is focused on a detailed techno-economic evaluation, including the capital, operation, and maintenance costs. The simulation was done using in-house computer programs for gas turbine performance and the sCO2 cycle. The results show the potential utilization of WHR in different operational regimes: idling on the ground, cruise, landing, and takeoff. The results show that the Waste Heat Recovery unit may generate an additional 100 - 200 kW. However, the additional power will require an additional cost for the system, approximately $ 2 Million.

Copyright © 2023 by ASME.The industry and the academy are continuously developing new approaches, technologies, and models for gas turbine design. However, there was not enough time to cover all the relevant subjects for undergraduate or graduate students in one or two-semester courses. So, in previous works, the authors described a developed interactive platform for the preliminary design of multistage axial flow turbines for uncooled blades and improved it based on the student’s feedback, so it could be as didactic as possible. Its application in the courses offered by the Turbomachines Department at Aeronautics Institute of Technology (ITA) successfully accelerated the learning process of the basics. In the graduate courses, the use of the program granted time to more complex topics, e.g., blade cooling, off-design performance, CFD simulations, manufacture, and machine learning applied to turbomachine design, which were not covered in previous years. The program initiates with the data from thermodynamic cycle calculation and the definition of the main design parameters. Then, it computes the aerothermodynamic properties of the flow stage-by-stage, from hub to tip, and the geometry of the blades. Finally, it estimates the losses by source, iteratively, through the models of Ainley and Mathieson [1], Dunham and Came [2], or Kacker and Okapuu [3]. This work presents some studies performed by the students using the platform. Firstly, it was varied some design key parameters such as loading and flow coefficients, the aspect ratio and the pitch-to-chord ratio of the blades, the airfoil section geometry, and the tip clearance, once at a time while maintaining the others. Then, it was possible to observe how these modifications affected the number of stages required, the stress levels, the machine size, and the isentropic efficiency, tracking the primary sources of loss. After, the students implemented other loss models, such as the one by Craig and Cox [4], aiming to analyze the effect of surface roughness on the losses. Finally, they compared the platform results with CFD simulations and experimental data from turbines developed at the Department. The paper concludes with the students’ insights through the project and comments on how the employed methodology improved their learning process.

Copyright © 2023 by ASME.The inducer is an axial pump that is part of the propellant injection system of Liquid Propellant Rocket Engines (LPRE). It is located at the inlet of the turbopump assembly and is critical for designing high performance LPREs. Its geometric and operational characteristics allow it to operate at low inlet pressures, delaying the appearance of cavitation and allowing the propellant tanks to operate at lower pressures. This allows the tanks to be lighter due to a reduced wall thickness requirement. The inducer also needs to operate harmoniously with the other components of the turbopump, especially with the main impeller which is located just downstream in the system. Therefore, it is important that the flow conditions at the inducer inlet and outlet are known and integrated with the turbopump and tank design. The present work aims to develop a methodology for inducer design based on literature established methods in order to obtain geometry and evaluate the flow conditions in liquid-propelled rocket engine inducer pumps. This work will assess outlet flow and pressure conditions in a way that it is possible to match them with the main impeller inlet. Performance criteria are evaluated in terms of the outlet pressure coefficient, flow coefficient and efficiency focusing exclusively on non-cavitating conditions. Two established analytical methods were implemented, one to provide inducer geometry in terms of system operational requirements and another, from National Aeronautics and Space Administration (NASA), for performance prediction based on geometrical and operational parameters. Further analysis is complemented by simulating the generated geometry in a CFD software. The methods were validated using published experimental data and the performances of the analytical, numerical and experimental results were compared. Results showed that the 3D turbulent CFD simulations provided very good agreement of efficiency. Satisfactory results were obtained for the general trends of characteristic curves over a range of flow rates and the spanwise distribution of key performance parameters near design point. The pressure coefficient was significantly overestimated. The results of the analytical models showed good agreement with simulated CFD results, indicating appropriate calibration of loss coefficients.

Copyright © 2023 by ASME.The boundary layer ingestion (BLI) concept has emerged as a novel technology for reducing aircraft fuel consumption. Several studies designed BLI-fans for aircraft. BLI-propellers, although, have still received little attention, and the choice of open-rotors or ducted propellers is still an open question regarding the best performance. The blade design is also challenging because the BLI-propulsors ingest a nonuniform flow. These aspects emphasize further investigation of unducted and ducted BLI-propulsors and the use of optimization frameworks, coupled with computational fluid dynamics simulations, to design the propeller to adapt to the incoming flow. This paper uses a multi-objective NSGA-II optimization framework, coupled with three-dimensional RANS simulations and radial basis function (RBF) metamodeling, used for the design and optimization of three propeller configurations at cruise conditions: (a) conventional propeller operating in the freestream, (b) unducted BLI-propeller, and (c) ducted BLI-propeller, both ingesting the airframe boundary layer. The optimization results showed a significant increase in chord and a decrease in the blade angles in the BLI configurations, emphasizing that these geometric parameters optimization highly affects the BLI-blade design. The unducted BLI-propeller needs approximately 40% less shaft power than the conventional propeller to generate the same amount of propeller force. The ducted BLI-propeller needs even less power, 47%. The duct contributes to the tip vortex weakening, recovering the swirl, and turning into propeller force, as noticed from 80% of the blade span to the tip. However, the unducted and ducted BLI-configurations presented a higher backward force, 26% and 46%, respectively, compared to the conventional propeller, which can be detrimental and narrow the use of these configurations.

© 2023 The AuthorsWe review the recent progress that have led to the development of porous materials based on cellulose nanostructures found in plants and other resources. In light of the properties that emerge from the chemistry, shape and structural control, we discuss some of the most promising uses of a plant-based material, nanocellulose, in regenerative medicine. Following a brief discussion about the fundamental aspects of self-assembly of nanocellulose precursors, we review the key strategies needed for material synthesis and to adjust the architecture of the materials (using three-dimensional printing, freeze-casted porous materials, and electrospinning) according to their uses in tissue engineering, artificial organs, controlled drug delivery and wound healing systems, among others. For this purpose, we map the structure–property–function relationships of nanocellulose-based porous materials and examine the course of actions that are required to translate innovation from the laboratory to industry. Such efforts require attention to regulatory aspects and market pull. Finally, the key challenges and opportunities in this nascent field are critically reviewed.

© 2022 Elsevier B.V.In this work, we report the synthesis and characterization of sol-gel bioactive glasses containing niobium (Nb) and gallium (Ga), a multifunctional glass that synergistically combines the respective effects of these species in potentiating bone repair and regeneration, concomitantly with a bone cancer targeted therapy. We found that the entry of Ga3+ into the vitreous network promotes an increase in the network connectivity, contributing to an increase in the degree of polymerization of the glass, since part of the calcium ions that behave as network modifying agents were replaced by gallium ions that act as network formers, and hence a replacement of part of the Si-O−…Ca2+…−O-Si by Si-O-Ga-O-Si bonds. Such results confirmed an increase in bridging oxygen bond density associated with a decrease in the number of bonds per unit volume of the glass due to the expansion of the glassy network. Furthermore, the incorporation of Ga2O3 at the expense of CaO in the composition of SNb3Ga3 decreased the ionicity of the chemical bonds. The study of pH variation revealed that the presence of Ga decreases the solubility of the glass influenced by a reduction in non-bridging oxygens (NBOs) concentration, which in turn is associated with an increase in glass network connectivity.

© 2023 The AuthorsThe integrity evolution induced by manufacturing involving dissimilar TWIP and mild steel weld spots was investigated. Focus was given to the effect of manufacturing parametrization on controlling the dilution of the alloying elements and the resulting weld integrity. Samples manufactured with different conditions were characterized by chemical and phase composition, morphology, and mechanical properties. The findings showed that the distribution of chemical composition and metallurgical features are sensitive to the welding parameters. The influence of manufacturing on weld morphology was noticed. Manganese distribution is affected by the welding cycle, thus leading to austenite destabilization and brittle behavior upon a quasi-static tensile shear strength test. A processing set was proposed to control manganese dilution and martensite transformation.

© 2023Background: Esophageal thermal injury is a complication of atrial fibrillation (AF) ablation, and it can be avoided by esophageal deviation during left atrial posterior wall radiofrequency catheter ablation. Objective: This study aimed to evaluate the safety of a nitinol-based mechanical esophageal displacement device (MEDD) and its performance. Methods: This preclinical safety study was conducted on 20 pigs, with 10 undergoing radiofrequency AF ablation using the MEDD and 10 serving as a control group under anticoagulation but without radiofrequency application. Esophageal traumatic injuries were classified from 0 to 4 and were grouped as absent (grade 0), minor (grade 1 or 2), moderate (grade 3), or major risk lesions (grade 4) by anatomopathological study. Grades 1 and 2 were considered acceptable. Fluoroscopy was used to measure displacement. Results: Five (25%) pigs developed traumatic lesions, 4 with grade 1 and 1 with grade 2 (2-mm superficial ulcer). There was no difference in lesion occurrence between the radiofrequency and control groups (30% and 20%, respectively; P =.43). Under rightward displacement, the right edge moved 23.9 (interquartile range [IQR] 21.3–26.3) mm and the left edge moved 16.3 (IQR 13.8–18.4) mm (P <.001) from baseline. Under leftward displacement, the right edge moved 13.5 (IQR 10.9–15.3) mm and the left edge moved 16.5 (IQR 12.3–18.5) mm (P =.07). A perforation to the pharyngeal diverticulum occurred in 1 pig, related to an accidental extubation. Conclusion: In pigs, the MEDD demonstrated safety in relation to esophageal tissue, and successful deviation. Esophageal traumatic injuries were acceptable, but improper manipulation led to pharyngeal lesion.

© 2023 by the authors.In this work, the influence of heat treatment on the corrosion resistance of shape memory stainless steel based on FeMnSiCrNiCo was evaluated. Deformed samples were annealed from 250 °C to 1050 °C for 1 h. Scanning electron microscopy (SEM-EDS) and a Vickers microhardness test were used to characterize the microstructure. Thermal analysis was performed to identify phase transformations. Corrosion resistance was evaluated in an electrochemical test in a 3.5% NaCl solution. FeMnSiCrNiCo in the deformed state had better corrosion resistance compared to other conditions. However, as the annealing temperature increased, the corrosion resistance decreased due to the formation of precipitates.

Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.Molecular dynamics simulations have emerged as a powerful tool for studying the passivation of metal surfaces by oxygen, providing insights into the mechanisms underlying this process at the atomic scale. In this study, we have used molecular dynamics simulations to investigate the passivation of an aluminium particle by oxygen, as aluminium is one of the most used metallic additives of solid rocket propellants. Specifically, the interaction between a single aluminium particle and oxygen molecules in a controlled environment. The simulations were performed using ReaxFF forcefield and involved the use of a variety of analytical techniques to analyse the results. The results of the simulations showed that the passivation of the aluminium particle by oxygen occurred through a sequence of reactions. Initially, the oxygen molecules adsorbed onto the surface of the particle, forming oxygen atoms that diffused into the bulk of the metal. This diffusion led to the formation of an oxide layer on the surface of the particle, which effectively passivated the underlying metal. Based on the behaviour observed, the passivation process was highly dependent on the temperature of the system. At low temperatures, the formation of the oxide layer was slower and incomplete, leading to the formation of a highly disordered oxide layer. At higher temperatures, the oxide layer formed much more quickly and was much more ordered, with a crystalline structure. Overall, the study provides valuable insights into the passivation of aluminium particles by oxygen, highlighting the importance of molecular dynamics simulations in the study of materials science. In particular, the results of the study shed light on the mechanisms underlying the passivation process and suggest that temperature plays a critical role in determining the structure and properties of the resulting oxide layer.

Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.Molecular dynamics is a computational method used to study the behavior of molecules and atoms over time. By simulating the interactions between individual particles, researchers can improve insights into the physical and chemical properties of materials at the atomic scale. This approach has been applied to a wide range of fields, from drug design to materials science and even rocket propulsion. In this case, for ducted rocket. One area where molecular dynamics has been particularly useful is in the study of boron oxidation. Boron is a lightweight and high-strength material that has potential applications in the aerospace industry. However, boron is also highly reactive with oxygen, which can lead to oxidation and degradation of its mechanical properties. By using molecular dynamics simulations, researchers can study the process of boron oxidation in detail and identify ways to mitigate its negative effects. One potential application of boron in the aerospace industry is in ducted rocket motors. Ducted rockets are a type of propulsion system that use a duct to compress air before mixing it with fuel and igniting it to burn and then generate thrust. This approach has several advantages over traditional rocket motors, including higher efficiency and lower noise levels. However, ducted rockets also require materials that can withstand the high temperatures and pressures generated during operation. Boron-based materials are well-suited for use in ducted rocket motors because of their high strength and heat resistance. However, boron oxidation can also be a concern in this context, as the high temperatures and pressures can accelerate the oxidation process. By using molecular dynamics simulations, researchers can study the interactions between boron and oxygen at the atomic level and identify ways to protect the material from oxidation. In summary, molecular dynamics simulations have a wide range of applications in materials science and engineering. In the context of boron oxidation and ducted rocket motors, this approach can be used to study the behavior of molecules and atoms at the atomic scale and identify ways to protect boron-based materials from oxidation and degradation. With continued research and development, boron-based materials could play an important role in the development of next-generation propulsion systems for aerospace exploration and other applications. Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) was used in this study. LAMMPS is a classical molecular dynamics code with a focus on materials modelling.

Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.Electrostatic discharge is recognized as a form of ignition of energetic materials and unanticipated events of this nature get attention due to the magnitude, delay in the development of projects and loss of life. Studies have established the correlation between metallic aluminum present in formulations and the sensitivity of solid propellants to electrostatic discharge (ignition and cracking). To evaluate the influence of the electric field on the formation of cracks in the composite, models were used in the software COMSOL Multiphysics relating the amount of aluminum and the sensitivity to ESD. An experimental design for simplex network mixtures with pseudocomponents was adopted and electrical permittivity was the property observed in hypothetical AP/HTPB/Al mixtures. A model built in the COMSOL simulated external and internal discharges in a rocket motor indicating sensitive points load accumulation - in its structure, represented by the superficial density of load. Furthermore, a model assigned by the Hong group of mechanics and structural materials from Iowa State University was used to evaluate crack formation and its relation to electrical permissiveness. The results associated to the equation obtained from the experimental planning show that the model presented for the study of rupture is in accordance with the literature. The studies carried out presented a new methodology for the study of the influence of electric fields on aluminized solid composites indicating the possibility of ignition via ESD.

© 2023 Sociedade Brasileira de Quimica. All rights reserved.DETERMINATION OF DEGRADATION KINETIC PARAMETERS AND FAILURE TIME ESTIMATION OF MAGNESIUM TEFLON® VITON® ELECTRONIC “FLARE” COUNTERMEASURES. Flare type countermeasures that use the composition designated as MTV (Magnesium, Teflon®, Viton®), are the most used by Air Forces around the world. In Brazil, these “flares” are used in several locations and are subjected to different handling, storage and operation conditions that can affect their performance and compromise their service life. In this work, the Monte Carlo method was applied to estimate an empirical model to predict the lifetime of these countermeasures, using as variables the temperature and the relative humidity of the place where the material is used. The results were analyzed using multiple linear regression and analysis of variance. The kinetic parameters of material thermal degradation, such as Activation Energy and Pre-exponential Factor, and the estimated failure times of these countermeasures were determined. The results pointed out to strong temperature influence on material degradation resulting in different lifetimes for each site studied.

© 2023 The AuthorsReduced-activation ferritic-martensitic oxide-dispersion-strengthened (RAFM-ODS) Eurofer steel is a potential candidate material for structural applications in fusion reactors. Microstructural stability during long-term exposure at high temperatures is a key issue. Depending on the amount of prior cold-rolling strain and service temperature, important solid-state restoration reactions occur such as recovery, recrystallization and particle coarsening. ODS-Eurofer steel was cold rolled up to 80% reduction in thickness and annealed at 800 °C for durations up to 4320 h. Changes in microstructure were tracked by X-ray diffraction measurements using synchrotron radiation in post-mortem specimens to estimate dislocation character and density. The volume fraction of recrystallized grains was estimated using grain orientation spread (GOS) maps from electron backscatter diffraction (EBSD). Most of the softening occur in the first hour of annealing and it seems to be closely related to discontinuous recrystallization where a few special grain boundaries overcome Zener-Smith pinning effects caused by fine and stable Y2O3-based particles. M23C6 carbides undergo coarsening upon annealing and, as a result, extended recovery is the predominant softening mechanism as annealing proceeds, although only about 15% softening is noticed after annealing for 4320 h. Using thermodynamic and kinetic calculations, the results were extrapolated to the predicted service temperature of 650 °C. The results suggest that the remarkable microstructural stability of ODS-Eurofer would withstand almost 180 years at high service temperatures without major loss of the mechanical properties of the materials.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.Aerospace and automotive industries utilize advanced high strength steels due to their exceptional mechanical strength and ductility. Laser beam welding has shown potential in reducing the melted zone, heat affected zone, and process time for these steels. This study focused on dissimilar welding between DP 780 and 300M steel sheets, commonly used in the automotive and aerospace industries, respectively. The aim was to expand the range of possibilities and innovations by enabling the use of these steels in both applications. The study investigated the optimal process parameters, microstructure, and mechanical properties for the laser welding process. It also examined the influence of intercritical quenching and tempering on the microstructure and mechanical properties of the laser welded steels. The materials underwent dilution and different phase transformations due to the welding process and heat treatments, as revealed by microstructural characterization. The weld showed a notable increase in hardness, however without compromising toughness. The fractures during tensile testing occurred in the DP 780 steel, far from the MZ and HAZ. Heat treatments increased ultimate tensile strength, but lowered ductility. Welding affected the fatigue life, especially in the intercritically quenched joint, which showed a quasi-cleavage crack growth mechanism and a decrease in fracture toughness.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.Hybrid casting is a new fabrication concept that can reduce costs and production time of large tools, such as stamping tools for the automotive industry. In this work, we analyzed a hybrid material composed of a high chromium cast iron (HCCI) and a low carbon steel (WCB). SEM analyses indicate that the interface is free of non-metallic inclusions and porosities. The metallurgical bonding between alloys is confirmed by the diffusion of chromium and carbon from HCCI to WCB. Vickers microhardness, EDS and XRD confirmed the presence of M7C3 carbides in the HCCI and at the interface. One set of the samples was submitted to regular quenching in calm air and tempering, while another set was additionally submitted to subzero quenching before tempering. In both cases, a slight reduction of the HCCI hardness and an increase of the interface hardness were observed. The subzero treatment was effective to reduce the amount of retained austenite at the HCCI and limiting its hardness reduction. WCB microstructure and hardness showed no significative change, making it an ideal material to use with HCCI in hybrid casts. The results showed that is possible to produce bimetallic reliable components for industrial applications by means of hybrid casting.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.The objective of this work is to study the possibility of obtaining dense parts using water atomized AISI 316L steel powder in the L-PBF process. Despite its irregular, non-spherical, particle morphology, it has a significantly lower cost. 25 samples were produced varying the laser power and the scanning speeds to determine the optimal processing conditions. Additionally, hot isostatic pressing (HIP) was performed after the L-PBF process to further increase densification. Selected samples were subjected to microstructural characterization. The best densification results obtained were for the sample produced with the laser power of 173 W and scanning speed of 600 mm/s, where densifications close to 98% were obtained. HIP post-processing promoted increased densification of samples with closed porosity, allowing samples with densification above 95% to reach values close to 100%. HIP did not promote the closure of open pores. The results indicate that the use of water atomized AISI 316L in the L-PBF process combined with post-processing by HIP can produce dense engineering components and at the same time reduce the production costs of the manufactured components, mainly because it is a lower cost raw material when compared to the commonly used feedstock obtained by gas atomization.

© 2023 Universidade Federal de Sao Carlos. All rights reserved.WC-Co cutting tools are widely used by the metalworking industry. In order to improve the properties of these tools, research on the application of wear-resistant coatings, such as polycrystalline diamond, are of great importance to several applications. It is known that the occurrence of high-stress levels between the coating and the substrate can lead to adhesion failures. One strategy to minimize these failures is applying an intermediate layer of SiC. In this work, the deposition of a SiC layer was carried out by a novel two-step laser cladding approach. Instead of cladding directly the presynthesized SiC on the substrates, a 200 µm silicon powder layer was pre-deposited on the WC-Co substrates and then irradiated with a 30 W CO2 laser. To improve metallurgical bonding between the tungsten and the Si layer, all substrates were chemically attacked. This attack allows cobalt removal from the surface and increases surface roughness, improving the laser cladding process. After the SiC laser cladding, samples were coated with a 200 µm graphite powder layer and irradiated again by a CO2 laser. The samples were characterized by SEM, EDS, and XRD analysis. The results showed that in the first step, an irradiation energy of about 0.27 J was enough to fuse the silicon powder to the substrate and in the second step, 0.13 J was enough to promote the reaction between silicon, carbon and the WC substrate, resulting in the in-situ synthesis of SiC. Finally, a new method was proposed for the deposition of SiC on WC-Co based substrates and the observed results allowed the proposal of an empirical equation to describe the chemical reactions of the process.

© 2022 Elsevier Inc.Austenite reversion, i.e., a’-martensite → γ phase transformation in UNS S32304 lean duplex steel was investigated. The material was cold rolled to a true strain (ε) of 1.61 and subjected to continuous annealing up to 1000 °C with a heating rate of 3 °C/min. From the dilatometric curve, an unexpected thermal expansion at around 545 °C was found within the temperature range where the austenite reversion occurs. Based on this unexpected behavior, additional samples were annealed at the same heating rate until key temperatures. Besides dilatometry, microstructural changes were followed by means of magnetic measurements at room temperature, Vickers microhardness testing, high-resolution electron backscatter diffraction (EBSD), and electron channeling contrast imaging (ECCI). From EBSD data, a protocol was developed to distinguish the different constituents in the material during the austenite reversion, i.e., α'-martensite, ferrite, and both reversed and untransformed austenite. The driving force for the austenite reversion was calculated using thermodynamic calculations. The a’-martensite → γ transformation begins at about 545 °C and ends at almost 800 °C. In the early beginning, the austenite reversion is governed by a shear mechanism. At higher temperatures, at about 725 °C, KAM (kernel average misorientation) distributions and texture of both reversed and untransformed austenite show evidence of a diffusion-controlled austenite reversion mechanism. These results are supported by thermodynamic calculations and microstructural evidence revealed by ECCI.

© IMechE 2022.Thermal processes and power generation systems may employ producer gas generated through gasification as an alternative to replace natural gas with lower carbon footprint. However, pure producer gas in engines is associated with a significant power derating that can be mitigated by blending it with other biofuels. This work evaluated the effects of methane and producer gas blends on the performance of a SI engine. The additions of methane were 10%, 25% and 50% on a molar basis. The results demonstrated that adding 25% methane to producer gas is enough to sustain the combustion reaction with good stability and a power derating of 10.8%. The addition of 50% methane to producer gas attains efficiency and combustion characteristics remarkably similar to pure natural gas with a power de-rating of 5.4%. Emissions indicated that carbon monoxide (CO) has decreased with the addition of methane to producer gas from 85 to 3.43 g/kWh, while nitrogen oxides ((Formula presented.)) emissions have increased from 0 to 8.85 g/kWh. In the case of unburned hydrocarbons (UHC), emissions did not considerably change before adding 25% methane to producer gas and stayed constant at approximately 10 g/kWh. Engines designed to run on natural-gas could use this mixture without significant modifications to the combustion chamber while decreasing NOx emissions.

© 2023 Euspen Headquarters.Tool and mould making is one of the most important sectors of industrial manufacturing. Currently, over a third of polymer products are manufactured by injection moulding or stamping. These processes are complex, as the melted or heated polymers are subject to thermomechanical changes. Since injection moulding and stamping are mostly used for mass production, process repeatability and quality of the final product are very important. Improper adjustments of process variables lead to various defects in the final product along with high amount of waste and rejects. The need for measurement and control of the process is mandatory. Frequently, the tool is not operated by the owner of the mold or the end user of the plastic components, respectively, but by an injection molding service provider within the supply chain. Consequently, it is impossible for the tool owner to trace the quality of parts regarding the parameters applied for processing. This is crucial information to connect parts outside the tolerances to the respective process characteristics. The increase of quality in the production is achievable through correlating the processing parameters applied with the produced components. Therefore, the aim of the research herein is to develop an autonomous sensor system for monitoring injection moulding and stamping processes. The system comprises an external component of the tool in order to record and document the parameters applied such as tool temperature, pressure, number of machined parts and geolocation among others. In conjunction with a connected laser marking system for injection moulding, the unique identification of the components and the unchangeable connection of the production parameters with an individual component is enabled. The direct technological added value is given by the fact that the customer is able to monitor the production at any time, any place, comparing the actual production with the agreed and specified conditions. Furthermore, this information enables the creation of new business models for the tool owner. Even though this work is at initial stages, the preliminary results detailed herein are rather encouraging.

© 2022, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.The aeronautic manufacturing industry has been seeking to enhance competitiveness and product quality by applying the Industry 4.0’s technologies. Particularly, on the roadmap of the digital twin era, a way to achieve a reduction in manufacturing time and thus production cost is to obtain prediction models of the main elementary assembly operations and functions within aircraft manufacturing process, such as the clamping force applied by the temporary fasteners on the aircraft’s structural parts. Besides being a mandatory operation, it affects multiple tasks along the product’s assembly lifecycle. This work focuses on the role of the clamping force in the assembly process, establishing its functional model by means of an experimental approach based upon resources used on a real shop floor of a major aircraft manufacturer. To evince the main requirements that the clamping force tools can achieve, this work employs the Taguchi Design method, design of experiments, and process capability analysis. The model resulted from the aforementioned methods and tools allows the assembly behavior prediction and thus the control of the manufacturing process, ultimately yielding a better geometry quality.

© 2023 COSPARThis work studies transfer between non-coplanar circular orbits around Earth with the space vehicle performing a powered lunar flyby maneuver. The complete transfer trajectory is accomplished by an application of two or three impulsive velocity increments. First and final velocity increments are applied tangentially, respectively, to the departing and the arrival orbits around Earth. An optional second velocity increment is applied at the perilune in order to increase the effects of the flyby maneuver. Despite many works consider the powered lunar flyby instead of a natural lunar flyby, it is important to compare both maneuvers in the context of the complete trajectory. In this direction, the present work formulates and solves multiple point boundary value problems that determine the transfer trajectories considering three models: a three-dimensional patched-conic approximation, a model based on the spatial restricted three-body problem, and, a model based on the spatial bi-circular restricted four-body in which the influence of the Sun is included. The transfer trajectory solutions are compared with classical maneuvers and with transfers that perform a natural flyby maneuver. An interesting result shows that a decelerating propulsion during the flyby maneuver can provide a transfer trajectory with a fuel consumption smaller than the one of bi-parabolic maneuver even if the Sun's attraction is considered. Moreover, the influence of the Sun can decrease the time of flight and the apogee of the trajectory and it can save fuel consumption if the Sun's initial phase angle is properly chosen.

© 2023: Instituto de Astronomía, Universidad Nacional Autónoma de México.This work describes several models to design optimal interplanetary trajectories. The transfer problem consists in transferring a space vehicle from a circular low Earth orbit (LEO) to a circular low orbit around a destiny planet (Venus or Mars). Models based on the two-body, four-body, and five-body problems are considered. Also, several versions of the patched-conic approximation are utilized including a detailed version that designs a lunar swing-by maneuver. The results show that the optimal trajectories for Earth-Mars and Earth-Venus missions collide with the Moon if a lunar swing-by maneuver with an unspecified altitude of the closest approach is included in the trajectory design; however, sub-optimal trajectories that do not collide with the Moon exist, presenting a smaller fuel consumption than the trajectories without lunar swing-by and with no greater changes in the time of flight.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.Operational modal analysis (OMA) has been widely used in many fields of study because it allows identifying the modal parameters of a flexible structure in its operating condition. The system is under unknown working loads assumed to be random with broadband spectral characteristics. These hypotheses are not always easy to fulfill, generating uncertainty about identified modal parameters. This study evaluates and compares the effectiveness of two OMA techniques, enhanced frequency-domain decomposition (EFDD) and Ibrahim time domain (ITD), in the accuracy of modal parameter estimation of an unmanned aerial vehicle (UAV) structure with output-only data obtained by flight testing. To evaluate the influence of the number of sensors used in the identification of the modes, different measurements setups were considered to carry out in-flight modal identification analyses. Some works have addressed uncertainty by focusing on retesting or subdivision of a single measurement record. This work innovates in presenting an uncertainty study considering the variables that intervene in the estimation of PSD. The uncertainty in the identified modal parameters is obtained using the variability of the values of the parameters found. The modal frequencies values observed employing EFDD and ITD do not present substantial variations associated with the PSD matrix estimates. The EFDD damping ratio values show significant variability because they are mainly affected by spectral leakage, while the ITD damping ratio values are less sensitive to Welch’s method parameters variation. The root mean square deviations (RMSDs) of the frequencies values for both techniques are compared with those resulting from ground vibration testing.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Synthetic Air Data Systems are air data parameters real-time estimation algorithms. Estimation of such parameters have been under study for a few decades. System Identification theory gives some tools for both time and frequency domain. Several studies have been conducted to investigate this problem in the time domain, but the applicability of frequency-domainal gorithms is still to be investigated. This work proposes a frequency-domain formulation for the synthetic air data problem, which is validated using a time-domain method (Recursive LeastS quares). Both methods are applied to real flight test data and estimation results are discussed. Effects of the availability of side-slip parameter are evaluated and estimates uncertainties due to model parameters accuracy (stability derivatives) are also presented.

© 2023, The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature.Solar sails have been investigated and explored since costs in space missions may be significantly reduced with the exploitation of a renewable energy source. This work investigates the dynamical effects on the phase space dynamics of a Solar Sail in the presence of the gravitational field of the Sun and Earth. For that, the Circular Restricted Three-Body Problem with the inclusion of the solar radiation pressure acceleration prescribes the time evolution of initial conditions settled in the Earth’s Hill region. In general, the dynamical system considered is conservative, in the sense of being area-preserving. However, only in the case of orthogonal incidence of the solar photons in the sail’s flat surface, the dynamics remain Hamiltonian, preserving a first integral of motion CJβ . To provide an overview of the dynamics of this system, Poincaré sections are presented for the Hamiltonian case of the model and with the motion restricted to the plane. Given that, the qualitative behavior of trajectories is followed as a function of the first integral of motion CJβ and the sail lightness number β , defined as the ratio between the solar radiation pressure acceleration and the gravitational acceleration of the Sun on the sail. Some remarkable dynamical features are reported. Possible applications and practical implications for trajectories design are discussed.

© 2023 Elsevier LtdIn this work, we performed a dynamical analysis of a spacecraft around a nearly equal-mass binary near-Earth asteroid with application to the asteroid 2017 YE5, which is also a possible dormant Jupiter-family comet. Thus, we investigated the motion of a particle around this binary system using the circular restricted three-body problem. We calculated the locations of the Lagrangian points of the system and their Jacobi constant. Through numerical simulations, using the Poincaré Surface of Sections, it was possible to find several prograde and retrograde periodic orbits around each binary system's primary, some exhibiting significantly-sized higher-order behavior. We also calculated the stability of these orbits. After finding the periodic orbits, we investigated the influence of solar radiation pressure on these orbits. For this analysis, we considered that the area-to-mass ratio equals 0.01 and 0.1. We also performed a spacecraft lifetime analysis considering the physical and orbital characteristics of the 2017YE5 system and investigated the behavior of a spacecraft in the vicinity of this system. We analyzed direct and retrograde orbits for different values of Jacobi's constant. This study investigated orbits that survive for at least six months, not colliding or escaping the system during that time. We also analyze the initial conditions that cause the spacecraft to collide with M1 or M2, or escape from the system. In this work, we take into account the gravitational forces of the binary asteroid system and the solar radiation pressure (SRP). Finally, we calculated optimal bi-impulsive orbital maneuvers between the collinear Lagrangian points. We found a family of possible orbital transfers considering times of flight between 0.1 and 1 day.

© 2023: Instituto de Astronomía, Universidad Nacional Autónoma de México.In this article, equilibrium points and families of periodic orbits in the vicinity of the collinear equilibrium points of a binary asteroid system are investigated with respect to the angular velocity of the secondary body, the mass ratio of the system and the size of the secondary. We assume that the gravitational fields of the bodies are modeled considering the primary as a mass point and the secondary as a rotating mass dipole. This model allows to compute families of planar and halo periodic orbits that emanate from the equilibrium points L1 and L2. The stability and bifurcations of these families are analyzed and the results are compared with the results obtained with the restricted three-body problem (RTBP). The results provide an overview of the dynamical behavior in the vicinity of a binary asteroid system.

© 2023 Elsevier LtdMotivated by a groundbreaking proposal to plug depleted oil wells using an exothermic reaction to melt the wellbore components, this work investigates the thermal behavior associated with the longitudinal propagation of a stoichiometric Fe2O3/Al thermite reaction. The primary objective of this study is to develop a reliable macroscopic numerical model capable of accurately estimating the heat generation and propagation during the reaction. A small-scale experiment is used to validate the numerical model, which approaches the experiment as a 2-D axisymmetric geometry within multiple regions. The reaction is modeled with a simplified zero-order kinetic model assuming a constant kinetic rate for all chemical species. A porous model assesses the impact of porosity on the overall heat diffusion, and a source-based phase change model is employed to evaluate the melting of the chemical species and the outer tube. Also, a disruptive model is included to consider the reaction between only condensed phases. The experimental validation demonstrated a good agreement between the numerical results with the disruptive model and transient temperature profiles measured experimentally. Varying the kinetic rate and porosity suggests that a slower reaction and denser mixture can enhance the heat transfer towards surrounding materials, potentially benefiting future applications in well sealing.

© 2023 by ASME.Land is a limited commodity that has always been fought over. Its use and allocation for various purposes have been the subject of much debate and for good reason. It is necessary for most industries. It is becoming more and more a topic of conversation as available land is used up. This review article explores land competition as it relates to the production of food and energy, as well as the ramifications of taking natural land and converting it to human use for these purposes. It also discusses the policies that some countries are enacting to deal with the ever-shrinking availability of free land and ways that society can decrease the necessity for more land.

© 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.This research investigates the effects of thermodynamic and kinetic parameters on simulated Fe 2 O 3 –2Al thermite reaction propagation. For that, a full-factorial design was applied. Five parameters were investigated: mixture density (A), thermal conductivity (B), specific heat (C), activation energy (D), and pre-exponential factor (E). Among these factors investigated, the activation energy, the specific heat, and their two-factor interaction had by far the highest percentage contribution of effects in the five responses observed: burning velocity, thickness of the reaction zone, peak temperature, ignition temperature, and ignition delay. Higher activation energy and specific heat resulted in a slower and thicker reaction propagation wave that required a longer time to ignite and reached a lower peak temperature. However, while activation energy affected the ignition temperature positively, the specific heat presented a negative effect. The remaining parameters had less pronounced effects but were significant in all five responses. Moreover, regression models of burning velocity, thickness, and ignition delay responses were estimated, which allowed mapping effects on these responses through contour plots of the main two-factor interactions.

© 2023 Elsevier LtdThermite reactions are self-sustained exothermic reactions commonly employed in welding processes of railway tracks, material synthesis and pyrotechnics, to mention a few applications. More recently, this reaction has been assessed to plug depleted oil wells. Motivated by the foregoing, this work numerically investigates a Fe2O3/Al thermite reaction. A two-dimensional axisymmetric domain with a thermite layer compressed between a PMMA lid and a stainless-steel disk is considered. A first-order kinetic is assumed and the reaction is controlled by the hematite consumption. A computational solver is developed based on the open-source OpenFOAM® software. Numerical results showed good agreement with experimental data for temperature levels. Numerical results further indicated thermal losses next to the thermite-steel interface. These heat losses affected the melting of the species as a small portion of alumina remained entirely solid during the reaction.

© 2023 Elsevier Masson SASIn this work, a hybrid analytical and numerical solution for transient heat conduction across a composite cylindrical sector is presented. A two-dimensional domain consisting of a multi-layer circular sector of angle φ was investigated (φ<2π). The Separation of Variables Method (SVM) was applied to solve the partial differential equation with non-homogeneous boundary conditions of the first, second and third kinds prescribed in the radial direction. Homogeneous boundary conditions of first and second kinds were arbitrated in the angular direction. A spatial time-independent source term gi(r,θ) was considered. The radial eigenvalues problem for the (r,θ) domain returns only real quantities and depends implicitly on the angular eigenvalues. Results for time dependent temperatures using the Separation of Variables Method were compared with numerical results, showing good accuracy. A second set of results was developed to investigate boundary conditions, material properties and the thermal source power required to rise temperature levels (mainly around the mid-angle φ/2) high enough to promote melting of certain layers of materials. These results might be useful for investigating a novel technology for the decommissioning of oil wells using thermal sources, often referred to in the literature as Thermal Plug and Abandonment (TP&A).

© 2023 Elsevier LtdThis paper presents an improved one-dimensional nonstationary model to simulate the reaction propagation of aluminum and iron-oxide in thermite mixtures. This model is motivated by the application of thermite mixtures for thermal plug and abandonment of oil wells. The main improvements of this model include the chemical source term correction in the energy conservation equation, and the imposition of a temperature limit to account for aluminum vaporization. A simplified, first-order, one-step mechanism governed by the Arrhenius relation was assumed, and different pairs of activation energy and pre-exponential factor were analyzed, including some pairs that reproduce the experimental propagation speed reported in the literature. Numerical simulations were done to generate contour plots that map the effects of the kinetics parameters, alumina dilution, and aluminum addition to the initial mixture in the main characteristics of the reaction wave, such as velocity, thickness, ignition delay, and initiation temperature. These simulations indicate that, at alumina dilution of 20% or more, the simulated thermite reaction does not reach the aluminum vaporization temperature and may not present disruption of the system. The model shows that aluminum addition to the initial mixture accelerates the propagation and the numerical results reproduces experimental data from literature. Also, below a burning velocity of 26 mm/s and alumina-dilution higher than 40%, the reaction does not self-propagate.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Global change from carbon-based to carbon-free economy has driven the development of a number of innovative technologies for decommissioning oil wells in mature fields. The common technology in use nowadays relies on cementing the borehole to permanently seal and abandon old wells. However, this procedure has a high cost and takes several weeks to be concluded, which constitutes a burden for offshore wells. This work investigates an innovative technology for plug and abandonment based on the release of large amounts of heat from thermite reactions at the sealing location in the borehole. Tubing and casing are melt forming a plug after the cool down period. Transitory transport of heat generated by a thermite mixture is numerically investigated by solving the energy equation using the control volume method. Time required to melt and subsequent solidification of the molten mass is estimated.

© 2023 Begell House Inc.. All rights reserved.This paper investigates the effects of Arrhenius parameters on the Fe2O3-2Al thermite system. Assuming a single-step kinetics mechanism, contour plots were generated to investigate the effects of the activation energy and pre-exponential factor on the velocity and thickness of the reaction wave. Higher activation energies and lower pre-exponential factors resulted in slower and thicker reaction waves. Also, the effect of activation energy on the burning velocity is enhanced at higher levels of the pre-exponential factor whereas the effect of pre-exponential factor is increased at lower levels of the activation energy. The opposite trend was observed on the thickness of the reaction wave. Finally, an exponential relationship between thickness and velocity of the reaction wave was identified regardless of the Arrhenius parameters.

© 2022 Elsevier B.V.Moving from a carbon-based to a carbon-free economy has driven the development of groundbreaking new technologies for permanent plugged and abandoned (P&A) of mature oil wells, including the use of thermites as the energetic material for the so-called “Thermal P&A” technology. Better knowledge is then much needed on such chemical reactions. Accordingly, this research presents an in-depth kinetic study of the Fe2O3-2Al thermite reaction by analyzing differential scanning calorimetry (DSC) data at three heating rates. After an endothermic peak corresponding to the aluminum melting process (∼660.3 °C), two exothermic peaks were identified corresponding to thermal stages of the overall thermite reaction: the first stage at 800–1000 °C and second stage at 1000–1300 °C. The apparent activation energy of each reaction stage was calculated using several isoconversional kinetics methods. All methods revealed significant variation of activation energy with the extent of conversion. However, the differential method of Friedmann and the flexible-integral methods of Popescu and Vyazovkin identified higher variations than the rigid-integral methods, with EA values between 188 and 356 kJ/mol for the first reaction stage and 280 and 509 kJ/mol for the second one. These high variations indicated a multi-step mechanism that requires multiple kinetic triplets. The pre-exponential factor at each extent of conversion and the reaction mode of each reaction stage were estimated by an approach based on Popescu's equation and the compensation effect. A contracting sphere and a random nucleation mechanism were identified as suitable models to describe the first and second reaction stage, respectively. Modeled data showed an excellent agreement with the experimental data of the first reaction stage, with average deviations up to 1.2 %. However, modeled data of the second stage presented more notable variations with average deviations up to 9.5 %.

© 2023 IOP Publishing Ltd.Ti-6Al-4V alloy is ideal for use in the aeronautical and aerospace industries because of its excellent strength/weight ratio and corrosion resistance. However, its applications at high temperatures are vulnerable due to its high affinity for interstitial elements, such as nitrogen and oxygen. The plasma immersion ion implantation (PIII) technique, performed at high temperature, allows formation of modified layers that can improve the mechanical and tribological properties without compromising the corrosion resistance, which is a characteristic of this alloy. In this work, the samples were treated by PIII at three different temperatures (700, 800, and 900 °C) for 120 min of exposure to evaluate PIII on the mechanical behavior of Ti-6Al-4V alloy compared to data already available in the literature. The aim of this process is to improve surface mechanical properties of the Ti-6Al-4V alloy. The techniques used in this work were x-ray diffraction microhardness, glow discharge optical emission spectrometer, and wear testing in a ball-on-disk tribometer. The results indicate a significantly increased material resistance, with a reduced wear for all treated samples and a reduced friction coefficient for samples treated at 800 and 900 °C. The best results were for alloy treated at 800 and 900 °C, because they maintain the low coefficient throughout the test, which indicates better wear resistance.

© 2023 Elsevier LtdThe aim of this study is to present a novel Semi Analytical model to analyse Mode I delamination in DCB specimens with holes, and specimens with installed fasteners. For verification and validation results were obtained with experiments and with Finite Element Analysis (FEA) based on Cohesive Zone Modelling. The proposed model obtained results with a good correlation to the experimental and FEA results, with a significant reduction in computational time. It presents the first known analytical method to include holes and fasteners in Mode I delamination analysis, and it discusses complexities and limitations of the analysis methods.

© 2023 Elsevier LtdTwisted continuous-filament yarn models for estimating breaking force and mechanical behavior rely on information such as yarn radius or surface angle twist, that are not readily available for a new yarn design. An easy-to-implement mechanical model for twisted continuous-filament yarns under pure tension is proposed, where the yarn geometry is generated by packing techniques and each filament individual mechanical behavior is calculated using traditional continuum mechanics/differential geometry formulation, leading to the progressive collapse of the yarn with the failure of each individual filament. Simulation results show good correlation with experiments for predicting breaking force in low-twist yarns, but diverging from the experimental curves at high twist values.

© 2022 Elsevier LtdThe Vibration Correlation Technique (VCT) is a non-destructive method to predict buckling loads for imperfection-sensitive structures. While successfully used to validate numerical models and predict experimental buckling loads, recommendations for defining the VCT experiment are scarce. Here, its sensitivity towards the number of load steps and the maximum load level measured is studied, and an uncertainty quantification of the measured frequency affecting the VCT prediction is performed First, a series of finite element (FE) models representing nominally identical cylinders, and validated by buckling experiments, are used to perform a sensitivity study. When no frequency deviations are introduced in the FE results, a positive correlation between the VCT predictions and the maximum load used for measurements is found, the number of load steps used being only relevant in reducing the errors. Introducing frequency deviations deterred the predictions correlation with the maximum load, while using more load steps reduced this influence. Second, a sensitivity study based on experimental data confirmed most of the trends previously observed using the FE results, the exception being a poor prediction sensitivity as a function of the maximum load, owing to several cylinders for which the VCT method gave predictions that progressively decreased with increasing the load.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Aeronautical structures are subjected to damages such as fatigue cracks due to their inherently cyclic loading. Therefore, it is important to understand the process of nucleation and propagation of cracks for application in modern aeronautical projects that use the damage tolerant approach. In this context, there are situations in which components or structural details may present the nucleation and propagation of an initial or primary crack, and after a determined number of load cycles, it may occur the nucleation and propagation of a secondary crack, in the proximities of the primary crack, due to the load redistribution caused by the primary crack. The nucleation and interaction of primary and secondary cracks in structural aeronautical components is relevant to the design of damage tolerant structures. This work proposes an analysis methodology for the characterization of the nucleation, propagation and interaction of primary cracks (or leader cracks) and secondary cracks in aeronautical components, considering probabilistic aspects and the current practices employed for the treatment of riveted structures. The methodology developed considers a random distribution of stress by fatigue life curves (S-N), that results in cases in which secondary cracks initiate, and cases in which they do not initiate (in consequence of the catastrophic failure of the component occurring beforehand due the propagation of the primary crack). From the cases in which the initiation of secondary cracks occurs, the simultaneous propagation of leader and secondary cracks is analyzed to quantify how the cracks influence each other or interact during their propagation. The results obtained indicate that the distributions of leader crack lengths at the moment the secondary initiates tend to be normal, while the distributions of secondary crack lengths tend to be lognormal, in coherence with the Equivalent Initial Flaw Size methodology, currently employed in the industry. From the propagation analysis, it was identified that secondary cracks tend to grow faster than the leader cracks, and the relative sizes between secondaries and leader cracks followed the general behavior found in data from detailed fleet inspections. With this, the present work offers a contribution to improve the design of aeronautical structures with a probabilistic approach for evaluation of primary and secondary cracks, both in terms of initiation and simultaneous propagation of fatigue cracks.

© 2023 Elsevier LtdAs structures become slender their non-linear aspects become more apparent and needing of assessment. In that spirit, the authors proposed a theory for addressing the effects of these non-linearities in a highly flexible beam akin to an wing in aeroservoelastic analyses regarding piezoelectric control for flutter suppression. This framework was proven quite efficient for it allowed large displacements to be naturally incorporated by means of a set of generalized variables that encoded the beam mechanics (membrane and bending) and in which space some mechanical features could be linearized. Therefore, the authors investigated the consequences of solving analytically a cantilever beam problem subjected to a material load at its free tip by means of that theory and demonstrated the connection between that problem (in particular when it comes to the buckling problem) and the Weierstrass elliptic ℘-function, a relationship not yet demonstrated to the best of the authors’ knowledge. That demonstration is the subject of this article, as well as a comprehensive study of the solutions for some loading conditions in a reference slender beam and the suggestion of further applications that could be developed from the solution found, in particular in FE analysis.

© 2023 Elsevier LtdThe aim of this study is to present a novel Semi Analytical model to analyse Mode I delamination in DCB specimens with holes, and specimens with installed fasteners. For verification and validation results were obtained with experiments and with Finite Element Analysis (FEA) based on Cohesive Zone Modelling. The proposed model obtained results with a good correlation to the experimental and FEA results, with a significant reduction in computational time. It presents the first known analytical method to include holes and fasteners in Mode I delamination analysis, and it discusses complexities and limitations of the analysis methods.

© 2023, ASM International.The present work demonstrates that a non-associated Barlat’s Yld 2000-2D plastic flow stress potential gives better correlation accuracy with the Lankford and equal biaxial coefficients of plastic anisotropy than the associated flow rule. Additionally, new generalized exact equations are presented to calculate the Lankford and equal biaxial anisotropy coefficients deduced from the Yld 2000-2D function. The investigated metals were mildly and highly anisotropic Al 2024, Al 6022, Al 2090 aluminum alloys and AISI 409 steel sheets. The non-associated Barlat’s Yld 2000-2D flow stress potential is validated by plotting on the same graph predicted r-value, normalized yield stress curves and experimental data. Newton–Raphson numerical method with a relaxation factor was employed to calculate accurately the anisotropy coefficients. Present findings for slightly and highly anisotropic aluminum alloys and AISI 409 steel revealed that Barlat’s Yld 2000-2D function can be employed for accurate characterization of metal plastic anisotropy behavior by using two independent functions: the non-associated flow stress potential and the yield stress criterion. Consequently, this procedure requires a total of 12 experimental parameters of anisotropy in calibration for accurate r-value and s-value independent curves fitting. Therefore, the proposed non-associated Barlat’s Yld 2000-12p plastic potential and yield criterion give better correlation with experimental r-value and s-value data than the associated Barlat’s Yld 2004-18p flow rule. In addition, the predicted forming limit strain curves of AISI 409 steel are in good agreement with the experimental FLC, using the non-associated Barlat’s Yld 2000-2d plastic potential, better than the associated flow potential rule.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.Circular Cylindrical shells structures play an important role, mainly in the aerospace sectors. In general, they are subjected to external loads and internal pressure due to internal storage such as a propulsion fuel. In this work, a semi-analytical model using Ritz method is proposed to evaluate the axial critical buckling load and internal pressure behaviour of composite cylindrical shells. Simulations were performed for different laminate stacking sequences based on unidirectional tape carbon/epoxy. Conditions of simple support and clamped edges are evaluated. The model consists of using trigonometric functions to approximate the displacement field in the Ritz formulation. In this case, the functions are chosen to meet the geometrical boundary conditions and a suitable number of terms in the Ritz method are chosen to achieve convergence results. The Ritz method formulation is based on the total potential energy and the Reissner–Mindlin hypothesis is also considered in the strain–displacement relationships for buckling cases. The critical buckling loads and buckling modes are obtained from the resultant eigenproblem when the total potential energy is minimized. The results are compared with numerical predictions obtained using the commercial software Abaqus, based on finite element method (FEM) and results available in the literature.

© 2023 Elsevier LtdFiber-reinforced polymer matrix composites are often alternative materials for aerospace structures applications where high strength and stiffness at low weight are mandatory design requirements. However, there are still open issues related to thermal effects on composite parts' mechanical properties and fracture behavior, particularly under cryogenic conditions. This work aims to investigate the fracture aspects of carbon fiber composite joints made with co-curing, co-bonding, and secondary bonding technologies when subjected to cryogenic conditions. A detailed study was carried out on their mechanical performance under Mode I and Mixed Mode I/II loading by performing interlaminar fracture tests at −54 °C. Microscopy techniques were applied to better understand the failure mechanisms observed for each bonding technology. The manufacturing process has a direct influence on the crack propagation of the laminates at cryogenic temperature. The post-cure process results in a brittle behaviour for CB and SB composite joints tested at cryogenic temperature leading to significant reductions in the fracture toughness values. The CC composite joints exhibited a tougher behaviour in comparison to CB and SB composite joints. This is mainly due to the fact that these joints are not post-cured and the presence of an interlayer that delays crack propagation.

© 2023 Elsevier LtdThis paper describes a systematic review on the propagation of translaminar damage in FRP considering different specimen configurations, data reduction schemes, fracture analysis, and mechanical properties. In particular, the influence of the specimen configuration (open-hole, edge-notched family, compact compression, compact tension, and compact tension shear) in results is highlighted. In this review, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol was carried out as a guide. The VCCT (Virtual Crack Closure Technique) and CDM (Continuum Damage Mechanics) are the two main categories of numerical modeling approaches used to simulate the translaminar fracture in composites. Previous studies on translaminar fracture toughness characterization indicate that unwanted failure mechanisms commonly observed in opposite regions to the specimen's crack tip may be avoided by using edge-notched specimens and open-hole tensile tests combined with data reduction schemes based on Finite Fracture Mechanics criteria. Additionally, CTS (Compact Tension Shear) presents the most prominent advantage of resulting in higher stress concentration at the crack tip, avoiding unwanted compressive and other damage effects into fracture toughness behavior, adding the advantage of the mixed mode loading application and reliable R-curve. The main findings are discussed, and the shortcomings were identified to guide further investigations and provide a reference document to aid a better understanding of the benefits still to be exploited in this field.

© The Author(s) 2023.The industry of composite materials has grown in the last decade due to the requirements of light and high strength materials. The increasing demands of materials have to comply with low greenhouse gases emissions (GHG) as stated by international agreements, and reusing and recycling is a path to minimize the environmental impacts. This research aims to analyze the variables that influence the tensile strength of discontinuous laminate composites of short fibers from cutting operation process which is in the context of reusing. These variables were part of the equation of force equilibrium that involves shear strength failure criterium approach. In addition, the failure analysis and the results were compared with the literature data. Composites of glass fiber fabric wastes with varied fiber length (defined as short fiber) was designed and tested using polyethylene terephthalate (PET) as a matrix. A total of three different laminates with different fabric lengths were evaluated, totaling of seven interruptions/discontinuities along the thickness of each laminate. An image analysis of the failure sequence aided to assess the laminate behavior by comparing the stress–strain curve shape and they were in agreement with the results provided by the developed equation. The results show that this equation enables to identify the variables that influence the laminate strength: yielding stress; interface strength; stress concentration; and peel stress. In this particular research, the weak interface contributed to the low tensile strength of the laminates, and showed less influence of the “critical length,” limiting the micromechanical approach that considered a fiber filament.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.The Turbofan engine represents the type of propulsive technology mostly used in commercial aircrafts, and until that the new disruptive technologies take place, researches to optimize this propulsive system shall be continued to reduce the environmental impacts. The aim of this paper is to propose a methodology for the low-pressure system preliminary design (fan/low-pressure turbine), based on aircraft cruise thrust adjustment from commercial off-the-shelf turbofan engine, focusing on reducing specific fuel consumption for the individual aircraft mission. This work is carried out according to the following steps: (i) model development with calculation methodology for velocity diagram flow angles applied to the low-pressure system; (ii) estimation of baseline low-pressure system design parameters from limited engine data (an integrated engine aircraft model developed in the Gasturb and MATLAB commercial softwares are applied); (iii) evaluation of the strategies to increase the low-pressure system component efficiencies and their implementation by computer simulation; (iv) reapplication of the calculation methodology for estimation of the velocity diagram flow angles considering the adjusted low-pressure system components; and (v) analysis of the adjustment proposal results considering the matching between the lowest specific fuel consumption and the net thrust required for the cruise flight phase of the aircraft. As a final result, it demonstrates that the proposed strategies are promising for the adjustment of the low-pressure system in the preliminary design scope, and this approach may be considered feasibility from the standpoint of the engine manufacturer implementation, since the engine core and its external sizing do not affected.

© IMechE 2022.Thermal processes and power generation systems may employ producer gas generated through gasification as an alternative to replace natural gas with lower carbon footprint. However, pure producer gas in engines is associated with a significant power derating that can be mitigated by blending it with other biofuels. This work evaluated the effects of methane and producer gas blends on the performance of a SI engine. The additions of methane were 10%, 25% and 50% on a molar basis. The results demonstrated that adding 25% methane to producer gas is enough to sustain the combustion reaction with good stability and a power derating of 10.8%. The addition of 50% methane to producer gas attains efficiency and combustion characteristics remarkably similar to pure natural gas with a power de-rating of 5.4%. Emissions indicated that carbon monoxide (CO) has decreased with the addition of methane to producer gas from 85 to 3.43 g/kWh, while nitrogen oxides ((Formula presented.)) emissions have increased from 0 to 8.85 g/kWh. In the case of unburned hydrocarbons (UHC), emissions did not considerably change before adding 25% methane to producer gas and stayed constant at approximately 10 g/kWh. Engines designed to run on natural-gas could use this mixture without significant modifications to the combustion chamber while decreasing NOx emissions.

© IMechE 2022.The mandatory migration from fossil to renewable energy sources requires the characterization of new alternative fuels. One important step in fuel characterization is the test in optical engines, which allows the morphological characterization of flames. This analysis requires the post treatment of images by using segmentation. In many cases, an automatic threshold presents shortcomings as the flames may present different regions with variable luminosity, as also reflections from valves and cylinder liner. Consequently, a time-consuming manual image processing is required and, therefore, an automatic procedure would be welcome. The use of deep learning techniques for image segmentation is a promising alternative for such task, which has showed excellent results in several applications. In this study, two different models were trained to identify flames in images obtained from an optical engine operating at various conditions. The dataset used to train the models was generated by using images from tests with several types of fuels and combustion modes. The effects of image resolution and the generalization capabilities for different fuels and combustion operation were investigated. After analyzing the results, the use of deep learning methods to identify and characterize flames was validated as a mean for improving processing time.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.This paper aims to specify a methodology for an optimized inerting system conceptual design based on fuel tank flammability analysis defined by rules for commercial aircraft certification proposal to evaluate the impact on engine bleed consumption in a modernized commercial long-range aircraft model. This work was carried out according to the following steps: (1) estimation of aircraft geometric tank features from limited data; (2) development of tank thermal model to estimate bulk fuel temperature based on flight performance aircraft, fuel consumption/transfer in the tank, presence of heat sources and external airflow heat exchange; (3) flammability analysis based on Federal Aviation Administration (FAA) certification requirement methodology; (4) conception of an inerting system model as a flammability reduction means based on tank gas mixture model, onboard inert gas generation system publicly available data from FAA previous studies and proposed inerting gas distribution model; (5) incorporation of inerting system in the flammability model and reassessment of the fuel tank flammability; (6) analysis of the impact in engine bleed air consumption and specific fuel consumption due to the designed inerting system. As a final result, a methodology to increase the safety in aircraft operation was obtained, considering the current most common technology used to reduce the fuel tank flammability in commercial aircraft, the inerting system. This strategy is applicable for new aircraft in a development phase and also allows the accomplishment of modernizing designs for existing aircraft following current safety regulations.

© 2022 Elsevier LtdThe high environmental impact of fossil fuels combined with the rise of carbon dioxide in the atmosphere has made the search for renewable fuels imperative. The study assesses the technical and economic viability of replacing heavy fuel oil (HFO) with green hydrogen (H2) in industrial plants for high temperature generation (>1100 K). The study also estimates the emissions generated by the plants after the fuel switch in terms of particulate matter (PM), SO2, NOx and CO2 emissions. To illustrate the feasibility of this replacement, an assessment of a calcination furnace at a pulp plant in Chile in 2022 was carried out, taking into account two electricity generation scenarios for H2 production by water electrolysis. Replacing HFO with a mixture of H2 + HFO was beneficial in terms of emissions. The financial assessment showed that blending H2 with HFO of up to 20 % is the best solution, considering current fuel prices, and that full substitution of HFO with H2 after 2030 is economically viable.

© 2023 American Society of Mechanical Engineers (ASME). All rights reserved.To attend the high demand for high performance, low fuel consumption, and low emissions, ethanol has become a potential candidate to replace gasoline applications worldwide. In this scenario, ethanol market share has increased in two spaces, blended with gasoline, where the goal is just to increase the knock limit during engine operation, and then leverage the thermal efficiency, or in its pure form, where the benefits of its green characteristics contribute significantly to Green House Gas (GHG) credits benefitting car manufacturers. The objective of this research is to analyze the effects of different spark plug conditions, representing nominal and outwearing conditions, on flame propagation in engine-like conditions applying numerical modeling. The commercial software STAR-CD is adopted for the 3D Computational Fluid Dynamics (CFD) model mimicking the Direct Injection Spark Ignition (DISI) optical engine adopted for the experimental tests. The numerical model adopts a 3-Zones Extended Coherent Flame (ECFM-3Z) and Imposed Stretch Spark Ignition Model (ISSIM), for the combustion and the spark plug modeling, respectively. The engine operating conditions adopted consist of direct injection of ethanol (E100) partial load and low speed. The model was built and validated according to experimental measurements. Afterward, the tuned model was used to study a set of cases intended to evaluate how different spark plug discharge energy and electrode gaps influence flame propagation in engine-like conditions. The results obtained identified the influence of non-optimal spark plug conditions in combustion propagation and indicated the influence of the parameters studied in engine performance.

© 2023 by the authors.Global gas markets are changing as natural gas (NG) is replaced by biomethane. Biomethane is produced by upgrading biogas, which can have a molar concentration of methane to over 98%. This renewable energy has been injected into the pipeline networks of NG, which offers the possibility to increase its usage in industrial and residential applications. However, the expectation of the increase in biomethane proportion on the NG grids could increase the fluctuations on the composition of the NG–biomethane mixture in amplitude and frequency. In this context, the injection of biomethane into the existing network of NG raises a discussion about the extent to which variations in gas quality will occur and what permissible limits should exist, as variations in combustion characteristics can affect the operation of the combustion processes, with consequences for consumers, distributors and gas producers. This study describes a gas quality analysis with regard to the use of biomethane in industrial equipment, mixed or not mixed with NG, taking into account the indicators for gas interchangeability and provides a discussion on the necessary gas quality level to be achieved or maintained for efficient combustion in equipment originally designed to operate with NG. NG and biomethane real data collected for 92 consecutive days in 2022 and provided by two different companies in Brazil were used for this study. It is shown that the maximum deviation of the Wobbe Index (WI) of 5%, which is allowed for industrial plants, does not work for the operation of furnaces at temperatures of 1200 °C or more. In addition, it is shown that the WI, as defined in relation to the calorific value of the fuel, may allow inappropriate substitution of fuel gases, which is likely to reduce the range of blending of biomethane in NG pipelines. The results can be assessed to analyze how the addition of biomethane to NG grids will impact the WI and the equipment operation parameters such as the air-to-gas ratio, products-to-gas ratio, adiabatic flame temperature and furnace temperature.

© 2021 Taylor & Francis Group, LLC.A reverse vortex flow gliding arc discharge in a fuel-rich premixed mixture was applied to a high swirl fuel-lean global combustion to accelerate fuel oxidation. Both the discharge and flame were generated in natural gas and air. To evaluate the role of the gliding arc in the process, a gas analysis of the exhaust gas was performed in the same operational conditions with and without plasma. The chemical measurements show that the plasma reduces carbon monoxide and unburned hydrocarbons contents with a low impact on the NOx level. Furthermore, the comparison of the relative decrease of the hydrocarbon emissions shows that the hydrocarbons have different sensitivities to the plasma application.

© The Author(s) 2021.This work presents the experimental determination of fracture mechanics parameters of composite specimens manufactured by fused filament fabrication (FFF) with continuous carbon fiber reinforced thermoplastic filaments, based on Linear Elastic Fracture Mechanics (LEFM). The critical mode I translaminar fracture toughness (KIc) and the critical energy release rate (GIc) are found for unidirectional and cross-ply laminates. The specimens were submitted to quasi-static tensile testing. Digital Image Correlation (DIC) is used to find the stress field. The stress fields around the crack tip are compared to linear elastic finite element simulations. The results demonstrate the magnitude of fracture toughness is in the same range as for polymers and some metals, depending on lay-up configuration. Besides, fractographic analyses show some typical features as river lines, fiber impression, fiber pulls-out and porosity aspects.

Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.Molecular dynamics simulations have emerged as a powerful tool for studying the passivation of metal surfaces by oxygen, providing insights into the mechanisms underlying this process at the atomic scale. In this study, we have used molecular dynamics simulations to investigate the passivation of an aluminium particle by oxygen, as aluminium is one of the most used metallic additives of solid rocket propellants. Specifically, the interaction between a single aluminium particle and oxygen molecules in a controlled environment. The simulations were performed using ReaxFF forcefield and involved the use of a variety of analytical techniques to analyse the results. The results of the simulations showed that the passivation of the aluminium particle by oxygen occurred through a sequence of reactions. Initially, the oxygen molecules adsorbed onto the surface of the particle, forming oxygen atoms that diffused into the bulk of the metal. This diffusion led to the formation of an oxide layer on the surface of the particle, which effectively passivated the underlying metal. Based on the behaviour observed, the passivation process was highly dependent on the temperature of the system. At low temperatures, the formation of the oxide layer was slower and incomplete, leading to the formation of a highly disordered oxide layer. At higher temperatures, the oxide layer formed much more quickly and was much more ordered, with a crystalline structure. Overall, the study provides valuable insights into the passivation of aluminium particles by oxygen, highlighting the importance of molecular dynamics simulations in the study of materials science. In particular, the results of the study shed light on the mechanisms underlying the passivation process and suggest that temperature plays a critical role in determining the structure and properties of the resulting oxide layer.

Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.Currently Brazil has two rocket launch centers, they are the Hell Barrier Launch Center (CLBI), in the state of Rio Grande do Norte and the Alcântara Launch Center (CLA), in the state of Maranhão. The Alcântara Launch Center is the great Brazilian bet in terms of launches, because it has advantages in several areas: geographical aspect, CLA is located in a region close to the equator, less propellant is spent for positioning in geostationary orbit, there is no change in orbit after launch and there is a gain in momentum; geological aspect, there are no instabilities near the launch center, such as volcanoes; climatic aspect, since there are only occasional rains and no other varieties; aeronautical advantage: it is far from the major centers, so there is no significant air traffic volume of traffic on site, which allows a considerable amount of launches without putting air traffic at risk; demographic advantage: because it is a sparsely populated region, local releases do not put the population at risk. This paper objects to present the advantages of rocket launches in Brazilian launch centers and its potential to be a prominent commercial launch site, demonstrating how Brazil has reformulated its internal policy in search of entering the world aerospace market with the opening of Alcântara Space Center (CEA) to host propels by private companies, national or foreign. In the future, CEA can thus become one of the best locations in the world for commercial exploration or strategic rocket launches, heighten Brazil in the space field to a place compatible with its size.

Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.Molecular dynamics is a computational method used to study the behavior of molecules and atoms over time. By simulating the interactions between individual particles, researchers can improve insights into the physical and chemical properties of materials at the atomic scale. This approach has been applied to a wide range of fields, from drug design to materials science and even rocket propulsion. In this case, for ducted rocket. One area where molecular dynamics has been particularly useful is in the study of boron oxidation. Boron is a lightweight and high-strength material that has potential applications in the aerospace industry. However, boron is also highly reactive with oxygen, which can lead to oxidation and degradation of its mechanical properties. By using molecular dynamics simulations, researchers can study the process of boron oxidation in detail and identify ways to mitigate its negative effects. One potential application of boron in the aerospace industry is in ducted rocket motors. Ducted rockets are a type of propulsion system that use a duct to compress air before mixing it with fuel and igniting it to burn and then generate thrust. This approach has several advantages over traditional rocket motors, including higher efficiency and lower noise levels. However, ducted rockets also require materials that can withstand the high temperatures and pressures generated during operation. Boron-based materials are well-suited for use in ducted rocket motors because of their high strength and heat resistance. However, boron oxidation can also be a concern in this context, as the high temperatures and pressures can accelerate the oxidation process. By using molecular dynamics simulations, researchers can study the interactions between boron and oxygen at the atomic level and identify ways to protect the material from oxidation. In summary, molecular dynamics simulations have a wide range of applications in materials science and engineering. In the context of boron oxidation and ducted rocket motors, this approach can be used to study the behavior of molecules and atoms at the atomic scale and identify ways to protect boron-based materials from oxidation and degradation. With continued research and development, boron-based materials could play an important role in the development of next-generation propulsion systems for aerospace exploration and other applications. Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) was used in this study. LAMMPS is a classical molecular dynamics code with a focus on materials modelling.

Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.Electrostatic discharge is recognized as a form of ignition of energetic materials and unanticipated events of this nature get attention due to the magnitude, delay in the development of projects and loss of life. Studies have established the correlation between metallic aluminum present in formulations and the sensitivity of solid propellants to electrostatic discharge (ignition and cracking). To evaluate the influence of the electric field on the formation of cracks in the composite, models were used in the software COMSOL Multiphysics relating the amount of aluminum and the sensitivity to ESD. An experimental design for simplex network mixtures with pseudocomponents was adopted and electrical permittivity was the property observed in hypothetical AP/HTPB/Al mixtures. A model built in the COMSOL simulated external and internal discharges in a rocket motor indicating sensitive points load accumulation - in its structure, represented by the superficial density of load. Furthermore, a model assigned by the Hong group of mechanics and structural materials from Iowa State University was used to evaluate crack formation and its relation to electrical permissiveness. The results associated to the equation obtained from the experimental planning show that the model presented for the study of rupture is in accordance with the literature. The studies carried out presented a new methodology for the study of the influence of electric fields on aluminized solid composites indicating the possibility of ignition via ESD.

© 2023 by the authors.The objective of this article is to characterize an aeroelastic system in terms of its dynamical behavior, which could be either chaotic or periodic before, during, and after achieving the flutter velocity. The aeroelastic system shown here is a wing with a high aspect ratio, which leads to a very flexible behavior subjected to unsteady flow. This paper compares the computational and experimental dynamical behavior of an aeroelastic system at the flutter velocity for the different dynamic stall models proposed. To understand the nonlinear behavior of this system, the traditional attractor reconstruction and Lyapunov exponent calculation are compared with the 0–1 test. In addition to this comparison, two dynamic stall semi-empirical models are applied directly to the time history. All these comparisons show that the computational and wind tunnel experiments are in good agreement, and the dynamic behavior usually gives close results for the 0–1 test and Lyapunov exponent. It is concluded that the system presents chaotic behavior when no dynamic stall correction is applied or when Gangwani’s correction is applied. However, Boeing–Vertol’s correction postpones the chaotic behavior, meaning that the chaotic behavior is only observed for velocities above the flutter.

© 2023 IEEE.The paper describes the constitution of the Engineering Research Center for the Aerial Mobility of the Future (ERC-AMF) having ITA as the host institution, Embraer as the industrial partner, and researchers from the University of São Paulo and the University of Campinas. The objective of the ERC-AMF is the realization of R&D to contribute to overcoming challenges to the shaping of aerial mobility in the upcoming decades. These challenges arise from the necessity of reducing pollutant and noise emissions, and the need for increased efficiency of manufacturing processes, besides the trend of introducing in the market novel aircraft adapted for operation in urban environments and short-range travels. Five research areas are focused on the first operation phase of the Center: Machine Control for Electric Propulsion; Aeropropulsion Integration in Electric Aircraft; Methods for Decision Making in Autonomous Systems; Advanced Design for Metallic Additive Manufacturing; and Intelligent Aircraft Final Assembly. Each line will be developed by researchers from partner universities and engineers from Embraer. It is expected that the Center will contribute to the appropriation, by the Brazilian aeronautical industry, of scientific and technological knowledge generated, and, as a result, increase its preparedness to face challenges that shall be overcome in the process of shaping the aerial mobility of the upcoming decades.

© 2021 by Antônio B. Guimarães Neto, Guilherme C. Barbosa, Juliano A. Paulino, Rafael M. Bertolin, Jéssica S. M. Nunes, Pedro J. González, Flávio L. Cardoso-Ribeiro, Maurício A. V. Morales, Roberto G. A. da Silva, Flávio L. S. Bussamra, Flávio J. Silvestre, Fernando J. O. Moreira, and Carlos E. S. Cesnik. Published by the American Institute of Aeronautics and Astronautics,.The challenges of modeling flexible aircraft include appropriate fidelity capturing and validation with experimental data. In fact, the validation of formulations and models for the flexible flight dynamics is indispensable to ensure that all the important phenomena are correctly captured. With this objective, two high-aspect-ratio flexible aircraft have been flight-tested, and coupled aeroelastic–flight dynamics data have been collected to support model validation. Additional ground vibration and static tests were carried out to fully characterize the structural dynamic properties. Numerical models were built based on a linear structural representation but with geometrically nonlinear aerodynamics. Low Reynolds number effects were included in a simplified way with lookup tables of two-dimensional airfoil data. Wing-tip effects were considered via the vortex-and doublet-lattice methods. Propulsive data were obtained with wind-tunnel tests. This paper describes the numerical models, the two aircraft, and their instrumentation and presents the data collected from the aircraft sensors during flight tests. Numerical and experimental results are compared for angular velocities, accelerations, and strains measured at different points of the aircraft. Despite its limitations and simplifications, the numerical model captures the real aircraft main aeroelastic and flight dynamic behaviors.

© 2023 Elsevier LtdThis study presents a comprehensive spatial eigenanalysis of fully-discrete discontinuous spectral element methods, now generalising previous spatial eigenanalysis that did not include time integration errors. The influence of discrete time integration is discussed in detail for different explicit Runge–Kutta (1st to 4th order accurate) schemes combined with either Discontinuous Galerkin (DG) or Spectral Difference (SD) methods, both here recovered from the Flux Reconstruction (FR) scheme. Selected numerical experiments using the improved SD method by Liang et al. (2009) [53,54] and Jameson (2010) [55] are performed to quantify the influence of time integration errors on actual simulations. These involve test cases of varied complexity, from one-dimensional linear advection equation studies to well-resolved and under-resolved inviscid vortical flows. When simulations are well-resolved, the overall order of accuracy of the (fully-discrete) method of choice is limited to that of the time integration scheme. Moreover, it is shown that, while both well-resolved and under-resolved simulations of linear problems correlate well with the eigenanalysis prediction of time integration errors, the correlation can be much worse for under-resolved nonlinear problems as observed via numerical experiments. In fact, in the numerical simulation of under-resolved vortical flows, the predominance of spatial errors made it practically impossible for time integration errors to be distinctly identified. As a result, the eigenanalysis predictions are expected to hold (even if partially) in direct numerical simulations of turbulence. This highlights that the interaction between space and time discretisation errors is more complex than otherwise anticipated, contributing to the current understanding about when eigenanalysis can effectively predict the behaviour of numerical errors in practical under-resolved nonlinear problems, including under-resolved turbulence computations.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.Nowadays, numerical simulations of wind turbines based on the Reynolds-averaged Navier–Stokes (RANS) formulation are becoming, in terms of computational cost, increasingly more viable tools for geometry optimization and design. Nevertheless, a judicious use of RANS-type methods is still required to guarantee acceptable accuracy at manageable computational cost. Here, we assess the accuracy and cost of several well-known turbulence models (Spalart–Allmaras, k- ε , k- ω SST, along with transitional modelling) with and without a zigzag tape modelling for a representative horizontal axis wind turbine within a range of moderate Reynolds numbers (Re ≈ 3 × 10 5 to 8 × 10 5). This range allowed for the assessment of turbulence models under various complex flow conditions. Significant differences in performance have been found and, for a notable portion of the test cases, the k- ε model was able to deliver good results (similar to k- ω SST results) with a considerably coarser mesh. This suggests that k- ε , although often recognized as less accurate than k- ω SST, might actually be more efficient for wind turbine simulations. Also, although the best results came only with a coupled transition model which required a higher computational cost, this increase in cost is not exceedingly high and might allow for this model’s usage in later design stages. Accordingly, the present study is a valuable source for future wind turbine simulations and design and we hope that it fosters further developments in the field.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Thicker blunt trailing edge airfoils are extensively employed in many applications, especially in wind turbines. Their structural properties, such as strength section and area moment of inertia, and aerodynamic characteristics, such as higher curve slope and maximum lift coefficient, are particularly specials to design a blade that operates under varying cyclic loads and speeds, which establish dynamic conditions of creep loading, and fatigue stress. The main disadvantages are the higher drag and an intense and broadband noise, caused by the vortex shedding downstream. Many improvements have been achieved using passive flow controls to mitigate those problems, but there is still wide design space for better solutions. In this sense, the aim of this study is to investigate the potential of waviness applied on truncated trailing edge of thick airfoils as a possible efficient flow control mechanism. For this purpose, experiments in wind tunnel is carried out in order to understand the effects of different wavy geometries on truncated airfoil. A NACA 0020 airfoil is selected as a baseline profile, truncated at 15% from the trailing edge, and three configurations of waviness are tested: A = 0.11c, λ = 0.40c; A = 0.03c, λ = 0.40c; and A = 0.03c, λ = 0.11c. The phenomena is evaluated measuring forces in a wind tunnel at a Reynolds numbers of 200,000, and applying a technique of oil flow visualization. Main results shows that the wavy model presents much higher values of aerodynamic efficiency for lower angles of attack up to α = 5º. Besides that, another wavy configuration overcame the efficiency of the smooth truncated model for almost all pre and pos-stall regions. For low angles, a possible explanation is the break of vortex shedding coherence spanwise in the base, while for higher angles waviness allows to avoid flow separation over the surface.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.When solving differential equations, one must often use spatial discretization. However, this process introduces errors that are mesh dependent. Thus, improving solution quality while saving computational resources requires adequate spatial resolution. One way of doing so is to treat this issue as an optimization problem that targets the reduction of discretization error. The current work presents an approach to mesh optimization using r-adaptation and the adjoint method for one-dimensional steady equations. The two equations selected to display this methodology are the heat equation with a forcing term and the viscous burgers equation. The discretization method is a second-order finite differences scheme. The results present a substantial reduction in discretization error when the optimized meshes are employed.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Up to this day, the Computational Fluid Dynamics (CFD) field struggles to generate accurate and computationally viable turbulent flow simulations for aeronautical problems. The absence of a proper spatial resolution reduces the accuracy of simulations and may lead to nonphysical results and numerical instabilities. This problem may be addressed by increasing the number of degrees of freedom in the simulation. Since this also leads to higher computational costs, this process must be performed parsimoniously and focus on where it is the most efficient. However, the process of identification and refinement of those regions can be far from trivial. The current work is an initial step to investigate the performance of adaptation drivers that can be used to make industrial simulations more viable. The drivers are based on a jump indicator for high-order spectral/hp schemes. It takes the difference between averaged values on overlapping borders of two different elements as a measurement of error. The chosen adaptation method is a p-adaptation framework that increases the polynomial order of 10% of the mesh elements. The governing equations employed in the study are the two-dimensional Navier-Stokes equations, and the simulated test case is one of a tilted flat plate.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Recently, waviness applied on leading edge of airfoils has been extensively researched. As a biomimetic solution, the also called tubercle has brought up many insights on passive flow control mechanisms and inspired other studies. Therefore, the present study aims to investigate the potential of waviness now applied on the trailing edge of airfoils. For this purpose, experimental tests in wind tunnel is carried out in order to understand the effects of different wavy geometries on the flow. A NACA 0020 airfoil is selected as a baseline profile and three configurations of waviness are tested: A = 0.11c, λ = 0.40c; A = 0.03c, λ = 0.40c; and A = 0.03c, λ = 0.11c. The phenomena are evaluated measuring forces at a single Reynolds numbers of 250,000, and correlating it with a flow topology analysis provided by an oil flow visualization technique. Main results show that the wavy model with parameters A = 0.11c, λ = 0.40c presents the best aerodynamic efficiency, with similar lift values compared to the baseline profile, but with reduced drag coefficients, also briefly delaying stall separation. Flow visualization shows that this case has larger regions of attached flow.

© 2023 Elsevier B.V.The current study proposes a shot peening model which enables the residual stress interaction with grinding, a typical combination for gear finishing. The effect of the interaction on the stress state development was addressed by comparing the residual stress state from a standalone shot peening procedure, against the residual stress state arising from a manufacturing route where the interaction of shot peening and grinding takes place. In the interaction model, the grinding procedure generates a pre-loaded condition on the material, modifying the internal strain system of the gear tooth. This pre-loaded system, when disturbed by shot peening, reaches a new internal strain equilibrium. In the interaction model, a 24% less compressive stress state was attained when compared with the standalone shot peening process. A significant shift in the depth and magnitude of the peak compressive stress was also observed. On account of the numerical study of the processes’ interaction, the developed model substantially contributed to understanding the residual stress formation during manufacturing chains.

© 2023 the authors.In recent years, the automotive sector has shown a trend toward electrification in all segments. The introduction of the electric motor brings with it a set of new challenging requirements for the transmission system, which can potentially be addressed by coatings technology. Doping MoS2 coatings with transition metals have recently received great attention in many engineering areas due to their unique optical, electrical, and excellent lubricating properties. These novel composite coatings are acclaimed for improving tribology performance under sliding-rolling conditions, especially with Ti doping. The focus of this research will be the replacement of Ti as dopant element by Nb, which presents similar physical properties and promising results in terms of its application as self-lubricant coating, according to few previously reported studies. In this work, investigations of MoS2-based coatings innovative doped with Nb obtained via PVD magnetron sputtering process considering different deposition parameters and substrate surface integrity were studied for gear applications. A deposition system with independent high-purity targets was used to obtain coatings with tailored microstructural, mechanical, and tribological properties. Some tests were performed to determine the coating microstructural and mechanical properties, the adhesion on carburized SAE 8620 steel samples, commonly used for gear applications, and also the influence of the substrate residual stress state on coating behavior. Preliminary results suggest a significant influence of the metal doping content on the mechanical and tribological properties of the coatings. The obtained coatings showed lower coefficient of friction and proper adhesion on carburized SAE 8620 steels, also influenced by the substrate surface integrity. Moreover, the results suggest that further studies on Nb:MoS2 coatings for transmission systems applications are promissory to enhance the durability and efficiency of gears.

© 2023 The Authors.Market movement towards sustainability and electromobility impose new demands on the gear Industry in terms of materials, design and manufacturing. In this context, laser powder bed fusion (L-PBF) has been under the spotlight for being one of the most promising technologies in additive manufacturing (AM), allowing the designer to think beyond traditional constraints. On the other hand, anisotropic properties, distortions, and heterogeneous residual stress may lead to excessive stress states during finishing processes. For carburizing materials, such as 20MnCr5, the mechanisms leading to residual stress and distortions go beyond the temperature gradient mechanism (TGM) and incorporate significant microstructural changes due to phase transformation. The combination of these phenomena with the gear manufacturing chain places a significant challenge to the gear industry. Therefore, this study investigates the potential and challenges of manufacturing 20MnCr5 gears through L-PBF with focus on the surface integrity evolution along the manufacturing chain. The study addresses the processability of the material and investigates the surface integrity of the gears through the manufacturing chain. The composition of thermal and microstructural phenomena simultaneously occurring during print generates heterogeneous residual stress along the gear orientation. Contrary to the literature, the stress relief did not equalize the residual stress entirely. Therefore, the heterogeneous residual stress distribution observed in the as-built condition propagated through the entire chain. Even after three manufacturing operations, the pattern of residual stress after printing directly influenced the final residual stress state.

© 2023 The Authors.Indirect Selective Laser Sintering (iSLS) has shown disruptive potential to meet electromobility requirements for gears in terms of materials and product design. iSLS manufacturing allows for solutions in mass production mainly due to the speed of printing, when compared to direct additive manufacturing. However, there are still challenges regarding the processability of iSLS with carburizing alloy steels. Low densities arising from the intrinsic characteristics of the coated powder influence the mechanical strength. Shot peening appears as a potential solution to densify surfaces by inducing localized plastic deformation, but its implications are still poorly addressed in the literature. The objective of the study is an experimental investigation of the densification process by shot peening with parameter variations on the surface properties produced by iSLS. Both the decision of the peening parameters and the explanation to the densification phenomena were based on a numerical approach of the shot peening process. The density of the samples and the surface integrity features induced from printing to peening, such as topography and the residual stress state, were evaluated. The result provides insights, in the perspective of automotive applications, into the density of iSLS processing with carburized steels densification achieved by shot peening.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.The insertion of a payload into orbit is a very complex and costly activity. Therefore, the best performance of the launch vehicle is important for each launch. To achieve this goal, usually the vehicle trajectory is determined via an optimization process which results in the maximum payload mass that can be inserted into orbit or, equivalently, the minimum propellant expenditure to achieve orbit. This is a specially complex problem belonging to the general class of optimal control problems. This work investigates the trajectory optimization of a multistage launch vehicle. The optimal control problem is transformed into a nonlinear programming problem with the use of two different transcription methods: Hermite–Simpson collocation and multiple shooting. To solve the resulting parameter optimization problem, the gradient-based algorithm called sequential conjugate gradient-restoration algorithm is used, and an extension of the algorithm is proposed which enhances its applicability to more general optimization problems. The proposed algorithm is used to optimize the trajectory of the Brazilian microsatellite launcher VLM-1, in missions with different complexities. To validate the methodology, the results are compared with those obtained with a commercial optimization tool.

© 2023 COSPARThis work studies transfer between non-coplanar circular orbits around Earth with the space vehicle performing a powered lunar flyby maneuver. The complete transfer trajectory is accomplished by an application of two or three impulsive velocity increments. First and final velocity increments are applied tangentially, respectively, to the departing and the arrival orbits around Earth. An optional second velocity increment is applied at the perilune in order to increase the effects of the flyby maneuver. Despite many works consider the powered lunar flyby instead of a natural lunar flyby, it is important to compare both maneuvers in the context of the complete trajectory. In this direction, the present work formulates and solves multiple point boundary value problems that determine the transfer trajectories considering three models: a three-dimensional patched-conic approximation, a model based on the spatial restricted three-body problem, and, a model based on the spatial bi-circular restricted four-body in which the influence of the Sun is included. The transfer trajectory solutions are compared with classical maneuvers and with transfers that perform a natural flyby maneuver. An interesting result shows that a decelerating propulsion during the flyby maneuver can provide a transfer trajectory with a fuel consumption smaller than the one of bi-parabolic maneuver even if the Sun's attraction is considered. Moreover, the influence of the Sun can decrease the time of flight and the apogee of the trajectory and it can save fuel consumption if the Sun's initial phase angle is properly chosen.

© 2023: Instituto de Astronomía, Universidad Nacional Autónoma de México.This work describes several models to design optimal interplanetary trajectories. The transfer problem consists in transferring a space vehicle from a circular low Earth orbit (LEO) to a circular low orbit around a destiny planet (Venus or Mars). Models based on the two-body, four-body, and five-body problems are considered. Also, several versions of the patched-conic approximation are utilized including a detailed version that designs a lunar swing-by maneuver. The results show that the optimal trajectories for Earth-Mars and Earth-Venus missions collide with the Moon if a lunar swing-by maneuver with an unspecified altitude of the closest approach is included in the trajectory design; however, sub-optimal trajectories that do not collide with the Moon exist, presenting a smaller fuel consumption than the trajectories without lunar swing-by and with no greater changes in the time of flight.

© 2023, Marcílio Alves. All rights reserved.Recent research on structural dynamics has steered towards elastic metamaterials, as band gap phenomena can be explored to mitigate vibration. A challenge in their design is the determination of configurations resulting in wider band gaps in lower frequency ranges. Since some level of damping is unavoidable in any real engineering structure, it is necessary to extend the current methodology of optimal design to provide a deeper understanding of how damping may affect the desired performance. Therefore, the main objective of this article is to propose and evaluate a numerical procedure for the optimization of band gaps in damped metamaterials. Specifically, a modified objective function that incorporates an evanescence index integral is used and two optimization schemes are implemented, each reflecting whether the structure is undamped or damped. It is shown that the optimal damped metamaterial has wider range of attenuation than the undamped optimal one, but with decreased attenuation levels. The optimization procedure is validated numerically for a finite structure, demonstrating reduced transmissibility of wave motions.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.In a combined experimental and numerical effort we investigate aerofoil tonal noise generation and reduction. The means of noise control are streak generators in form of cylindrical roughness elements. These elements are placed periodically along the span of aerofoil at the mid chord streamwise position. Experiments are performed for a wide range of Reynolds number and angle of attack. In the present work we concentrate on our numerical investigations. We have performed wall-resolved large-eddy simulations for a given angle of attack of 0 degree and Mach 0.3. Two Reynolds numbers 0.8 × 105 and 1.0 × 105 have been investigated, showing acoustic results consistent with experiments at the same Reynolds but lower Mach numbers. Roughness elements attenuate tones in the acoustic field, and, for the higher Reynolds number, suppress them. Through Fourier decomposition and POD analysis of streamwise velocity data, dominating structures have been identified. Further, the coupling between structures generated by surface roughness and instability modes (Kelvin-Helmholtz) of shear layer has been identified, suggesting stabilisation mechanisms by which the sound generation by the airfoil is reduced by the roughness elements.

© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.An array of cylindrical roughness elements was used to reduce the tonal noise introduced by the separation bubble over a NACA 0012 airfoil at low angles of attack. Experiments were performed for four configurations: a baseline smooth airfoils, two with roughness elements at only one of the airfoil surfaces (pressure side or suction side), and the other with roughness elements at both airfoil surfaces. Arowof spanwise periodically spaced cylinderswas placed close to the mid-chord position in order to induce streaks that render the bubble three-dimensional, decreasing separation and stabilizing the Kelvin-Helmholtz instability of the separated shear layer, which is related to tonal noise. Our results show a decrease, and in some cases the total suppression, of the tonal noise at Reynolds numbers ranging from 0.6×105 to 2.5×105, and angles of attack ranging from 0 to 4 degrees.

© Springer Nature Switzerland AG 2024. All rights reserved.In-flight ice protection is typically performed by mechanical, chemical, thermal, or hybrid systems. One of the most traditional, cost-effective, and still often used techniques is hot-air anti-icing, which normally heats the interior of the affected aerodynamic surfaces with an array of small hot-air jets generated by a perforated tube (piccolo). These devices are designed to optimally distribute the energy along the protected area, ensuring that the local heat demand for anti-icing can be satisfactorily achieved. In this chapter, an example of a low-cost numerical model to resolve the compressible internal flow along the length of a piccolo is provided. The governing equations are those of the thermodynamic state of air, mass continuity, momentum, and energy conservation. The equations are used in algebraic form and are solved in sequential control volumes that are axially distributed along with the piccolo. At each orifice of the piccolo, the airflow is also treated in one dimension, with the intrinsic three-dimensionality of the air efflux being modeled with the help of a discharge coefficient correlation. A correlation can be based on experimental data, which is the case in the comparisons to the experimental results presented later in this chapter. This technique is quite efficient since it allows the prediction of the flow distribution along with a piccolo without demanding a high computational effort. As a direct benefit, for instance, the use of such low-cost models allows the analysis of multiple piccolo configurations before the selection of one for laboratory testing or production.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.Nowadays, numerical simulations of wind turbines based on the Reynolds-averaged Navier–Stokes (RANS) formulation are becoming, in terms of computational cost, increasingly more viable tools for geometry optimization and design. Nevertheless, a judicious use of RANS-type methods is still required to guarantee acceptable accuracy at manageable computational cost. Here, we assess the accuracy and cost of several well-known turbulence models (Spalart–Allmaras, k- ε , k- ω SST, along with transitional modelling) with and without a zigzag tape modelling for a representative horizontal axis wind turbine within a range of moderate Reynolds numbers (Re ≈ 3 × 10 5 to 8 × 10 5). This range allowed for the assessment of turbulence models under various complex flow conditions. Significant differences in performance have been found and, for a notable portion of the test cases, the k- ε model was able to deliver good results (similar to k- ω SST results) with a considerably coarser mesh. This suggests that k- ε , although often recognized as less accurate than k- ω SST, might actually be more efficient for wind turbine simulations. Also, although the best results came only with a coupled transition model which required a higher computational cost, this increase in cost is not exceedingly high and might allow for this model’s usage in later design stages. Accordingly, the present study is a valuable source for future wind turbine simulations and design and we hope that it fosters further developments in the field.

© 2023, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.Distributed propulsion (DP) is not a new concept but recent advances in electric motors and batteries, along with the need for more environmentally friendly products, brought this concept back to the spotlight. This paper addresses two types of DP: wingtip-mounted propellers and distributed propellers along the wingspan. The benchmark of the analysis is NASA’s X-57 “Maxwell” demonstrator. Another goal of this paper is to evaluate how good is the VSPAERO code to modeling aerodynamic flows, from a simple case of the isolated wing to a more complex 14 rotors case. The overall results show that VSPAERO provides consistent estimations for most cases scenarios, becoming a powerful tool for the pre-design of aircraft with distributed propulsion.

© 2023 American Society of Mechanical Engineers (ASME). All rights reserved.The objective of this work is to develop and validate a computational fluid dynamics (CFD) model of a supersonic air ejector, a device largely used in aircraft, and to determine how its efficiency behaves when some of its geometric parameters vary, fully exploring the physical phenomena of the problem. It is important to highlight that in the aeronautical industry the competitiveness of any device intrinsically relies on its efficiency, such that a CFD model for an ejector is indispensable for proper design. This paper presents a study of several turbulence models Rk–e en, Rk–e std, k–x shear stress transport (SST), Spalart–Allmaras (SA), and generalized k–x (GEKO). A validation process was conducted by comparing CFD results with two supersonic air ejector experiments. The turbulence model was also validated with these experiments, and it was concluded that the k–x GEKO model is able to reproduce the physics of the supersonic air ejector problem with greater fidelity than traditional turbulence models in terms of entrainment ratio, with a 6% relative error reduction in relation to the traditional k–x SST model, which has been considered by multiple authors as the best Reynolds-averaged Navier–Stokes (RANS) approach in ejector’s CFD studies. After this validation process, the sensitivity of ejector efficiency to two geometric parameters was evaluated: the nozzle exit position and the ejector mixing chamber height.

© 2023, AIAA International. All rights reserved.Two configurations typical of fixed-wing aircraft are simulated with the actuator line method (ALM): a wing with winglets, and a T tail. The ALM is extensively used in rotor simulations to model the blades by body forces, which are calculated from airfoil data and the relative flow velocity. This method has not been used to simulate airplane aerodynamics, despite its advantage of allowing coarser grids. This may be credited to the failure of the uncorrected ALM to accurately predict forces near the tip of the wings, even for simple configurations. The recently proposed vortex-based smearing correction shows improved results, suggesting those limitations are part of the past. For the nonplanar configurations studied in this work, differences between the ALM with the original smearing correction and a nonlinear lifting line (LL) method are observed near the intersection of surfaces because the circulation generated in the numerical simulation differs from the calculated corrected circulation. A vorticity magnitude correction is proposed, which improves the agreement between the ALM and the LL method. This second-order correction resolves the ambiguity in the velocity used to define the lift force. The good results indicate that the improved ALM can be used for airplane aerodynamics, with an accuracy similar to the LL method.