© 2025 Elsevier LtdAs an effort to reduce energy demand, researchers have been exploring the use of ejector pumps on cooling, heating and recirculation systems. To increase the ejectors efficiency, several studies propose optimizing the entrainment ratio and pressure ratio using CFD-based surrogate models. However, no study attempted to include an outlet temperature constraint, and there is no consensus on which surrogate model to use, or how to improve the models accuracy. The main goal of this paper is to develop a high-accuracy surrogate model, used to find optimal ejector geometries, that consider three functions of interest: maximizing the entrainment ratio, on various pressure ratios, constraining the outlet temperature. The methodology was implemented for a supersonic air ejector pump used to heat an aircrafts compartment. This work explore the correlation between the ejectors geometry and the functions of interest, the prediction accuracy of ten surrogate models, and a refinement process that increases the models accuracy at the pareto front. The resulting Universal Kriging model provided geometries that complied with the outlet temperature constraint and improved the entrainment ratio by 11.6% and 108.1% for the pressure ratios of 0.97 and 1.05, respectively, when compared to a geometry from the literature.

© The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering 2025.The aircraft flying qualities are assessed during preliminary design phases through dynamic stability derivatives and an adequate accuracy is necessary to avoid costly fixes after flight testing. The dynamic stability derivatives estimation process uses unsteady CFD or dynamic data acquisition in wind tunnel testing, but both are very expensive. However, using the Navier–Stokes equations rewritten in non-inertial reference frame embedded in a CFD software it is possible to estimate dynamic aerodynamic coefficients using steady-state CFD, which is demonstrated in the present work with adequate accuracy for both 2D and 3D study cases.

© The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering 2025.Optimizing the energy conversion processes within aircraft and developing novel aircraft configurations have become imperative for fostering a more sustainable aviation sector. Exergy analysis emerges as a valuable tool in pinpointing areas for improvement and evaluating innovative configurations. The present work intends to expand upon the exergy concept in the assessment of airfoil aerodynamics. This is achieved through drag breakdown and flow field analysis utilizing the exergetic method. The study employs computational fluid dynamics analysis, utilizing the airfoil NACA 0012 for subsonic compressible flow and NACA 2315, NACA 2312, and NACA 2309 for transonic compressible flow as test cases to illustrate the concept. Rates of exergy destruction and a thorough flow field analysis are presented along the wake downstream of the airfoil, comparing four turbulence models. The theoretical exergy method is juxtaposed with the classical near-field method and validated through technical reports. Ultimately, the findings indicate a potential for improvement using the exergy method in aerodynamics, resulting in a 12% reduction in drag in a 2D flow field, translating into potential energy savings up to 31000 W. Furthermore, it is also demonstrated that the impact of airfoil thickness variation on exergy destruction in the transonic regime is found to be negligible.

© The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering 2024.This study focuses on 2D RANS (Reynolds Averaged Navier-Stokes) simulations using Spalart-Allmaras and k- ω SST turbulence models for a supersonic air inlet featuring two different passive control systems: an air bleed system in the external ramp of the inlet and a two-dimensional bump. The supersonic inlet serving to capture and decelerate the high-speed incoming flows is aerodynamically indispensable to an airbreathing supersonic aircraft. Sometimes, depending on the conditions of the entry flow, the shock wave boundary layer interaction (SWBLI) can lead to inlet unstart if not controlled, due to thickened boundary layer. To verify the impact of the passive control systems, the inlet was tested at freestream Mach number of 2.0 and 2.03 as the geometry is very sensitive to Mach number change. Results indicate that the air bleed system is more effective for Mach 2.0 and reduces the bubble size of approximately 80.0%. In the case of the two-dimensional bump, it was noticed that the bump should be placed after the impinging shock on the geometry. Even though the bubble size does not reduce as much as for the air bleed system, for the two-dimensional bump, the SWBLI is weakened.

© 2024, Scipedia S.L., All rights reserved.Spectral element methods (SEM) are receiving increased attention over recent years given their capability to yield LES-type results without turbulence models (implicit LES - iLES). There is, though, a lack of fundamental studies on the suitability of continuous Galerkin (CG) methods, as most studies have focused on discontinuous SEM. This work aims to investigate solution quality and numerical robustness of CG-iLES by discussing simulations of the Taylor- Green Vortex and of spatially-developing turbulent channel flows. The performance of a recently developed stabilization technique (GJP) receives special attention. We show that CG-iLES with GJP can outperform traditional LES and be competitive alongside discontinuous SEM iLES.

© 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.

© (2022) by International Council of Aeronautical Sciences (ICAS) All rights reserved.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 good estimations for most cases.