© 2019 Elsevier LtdAnhydrous ethanol can be considered as one of the main alternatives to replace fossil fuels. However, the removal of water consumes the greatest fraction of the energy necessary for its production. Thus, the use of hydrous ethanol arises from a new fuel possibility and it has been successfully tested in a device such as a spark-ignition engine. For this reason, there is a need for the determination of fundamental properties of the ethanol-water-air mixtures. There are few experimental works in this area and the majority of them have been carried out in test conditions of pressure up to 1 atm. Thus, the main goal of the present work is to bridge this data gap. For this, the laminar burning velocities and Markstein length of ethanol-water–air flames at water content up to 30% v/v over a range of equivalence ratios from 0.7 to 1.4 up to 5 MPa and 380 and 450 K were experimentally determined. The method used was a constant volume bomb method with a central ignition. The results were compared to literature data and with predictions carried out with CHEMKIN-PRO using the three different kinetic mechanisms. In general, the results of the mechanisms lead to an overprediction in relation to the experimental results, though all of them predicted the burning velocity peaks at an equivalence ratio close to 1.1, which agreed with the experiments. The experiments conducted that increased water content of water fuel mixtures have a tendency to remain stable under a stretch influence. Also, it is possible to observe a linear relationship describing the influence of the diluent on the laminar burning velocity.

© 2020 IOP Publishing Ltd.A single-image nitric-oxide molecular tagging velocimetry (NO-MTV) is reported and employed in a real air driven hypersonic shock tunnel and provided velocities of 3240 170(5.2%) and 3030 160(5.3%) m , insignificantly different from previous results of 3037 98(3.2%) obtained by an ordinary multi-image MTV technique. The proposed methodology relies on an one-dimensional analytical description of the spatial intensity profile registered by a single MTV image.

Copyright © 2018 by ASME.A laser-induced fluorescence (LIF)-based nitric-oxide flow-tagging technique was applied to measure both velocity and NO lifetime in a hypersonic shock tunnel from two experimental test runs. The results were supported by an analytical profile proposed in this paper that provides a way to correct velocity measurements under unknown systematic error sources. This procedure provided velocities with discrepancies lower than 3% for a total of five measurements, and lower than 2% when compared with that obtained from a linear fit. Additionally, the comparison between the proposed and experimental profiles allowed us to obtain the fluorescence NO lifetime from only one image.

© 2018 IEEE.Shape memory alloy (SMA) wires have extensive use in many areas of the industry nowadays and its development continues reaching new applications as studies progress. This paper proposes a SMA measurement device that uses affordable components, such as the Arduino micro-controller and a LabVIEW programming language interface. With an antagonistic mechanism design, data on temperature, strain and stress is acquired to confirm the measuring capabilities of the full equipped instrument, rendering visualizations of phase transformations and opening way for further development in control and detailed acquisition of shape memory alloy wire properties.

© 2018 IADIS Press. All Rights Reserved.The development of transversal competences is essential for the success of engineers, who need to have the ability to adapt to the new and changing demands posed by modern society and scientific advances. It is a challenge for professors to teach and evaluate transversal competences, since such competences are related to attitudes and values. We present a program, held in an Engineering school, with the goal of motivating young people in STEM (Science, Technology, Engineering and Mathematics) areas. Results from the designed initiatives pointed to success in the development of transversal competences, including problem solving, communication, leadership, teamwork, self-management, creativity and innovation.

© 2018 IADIS Press. All Rights Reserved.Despite the technological development, the digital era, and the fact that Science, Technology, Engineering and Mathematics (STEM) permeates all the modern world, the number of students choosing to pursue a career in STEM areas is very small in comparison to other careers. In particular, considering the gender, the gap increases even more. In this work, we present an industry-university program designed to stimulate STEM education and fostering the female interest and development in these areas. Considering our female undergrad students, the proposal was to engage them in the process, as the main agents. Our students prepared and gave lectures in schools about STEM areas. Together with some faculty members, they also developed and applied workshops based on hands-on and minds-on learning activities to spark young girls’ curiosity in STEM areas. In all activities, it was performed an evaluation of learning outcomes, as STEM skills and interest. The program showed to be effective producing very positive remarks.

Copyright © 2018 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved.Engineering technical competence is an indisputable need in an engineer professional life. However, to be a complete engineer, able to work in an ever changing globalized world, but sensible to cultural differences, it is necessary more than technical skills. It is then important for students acquiring non-technical competences, such as intercultural appreciation, leadership, self management, service and civic responsibility, teamwork, and understanding of engineering ethics. Here, we present the "Women in STEM2D" Program, developed with undergraduate engineering students, whose goal is to attract and keep female students in the technological and science areas. We provide a critical analysis about how the planning and execution of the program activities contribute to the development of non-technical skills in the engineering students.

© 2017 The Authors. Published by Elsevier Ltd.Experimental studies on the laminar burning velocity (LBV) and the flame propagation speed close to the wall of premixed methane-air flames at a pressure of 1 bar and ambient temperature, for poor and rich mixtures, have been conducted and analyzed. The methane-air mixture LBV and flame propagation speed are studied in a constant volume combustion chamber with acrylic windows using the shadowgraph technique and a high-speed camera. The recorded images are analyzed using a Matlab script and both the system and the Matlab code have been validated against literature data. The results are in quite good agreement with available literature for LBV that shows its decreasing with pressure increase. For the flame propagation speed little literature has been found for validation but using a different set-up. The results show that the flame propagation speed decreases almost linearly except close to the wall where some oscillations are present, due to a combination of multiple phenomena such as compression and heating of the unburned mixture, a combination of radiative heat loss to the wall, flame curvature and flame stretch.

© 2016 Elsevier LtdDeveloping exact models of combustion instabilities is not an easy task to carry out and requires a great deal of time prior to obtaining success. The present study proposes a low-order model for pressure oscillations that does not require any knowledge of the systems, any new physical findings nor intricate details regarding its operating condition. This new approach is obtained using a Modified Van der Pol's equation (MVDP) which is tuned by use of a Dual Extended Kalman Filter (DKEF) as a recursive estimator with perspectives in control by computer. This phenomenological model is used to predict the pressure signal from a variety of different combustors. Input data were taken from experimental cases such as a Rijke tube, a gas turbine and a liquid-fuel aero-engine combustor. Furthermore, a simulation considering high frequency oscillations to show the capability of the new approach is presented. In all cases, the results demonstrated the feasibility of applying the tractable model MVDP and DKEF running together to investigate pressure oscillations in practical cases.

© 2016The recently increasing interest in plasma assisted combustion is mainly motivated by new possibilities for ignition and flame stabilization, in addition to pollutant emission reduction and control. In a chemically active environment, the plasma generates radicals, excited chemical species and ions, thus increasing the combustion process reaction rate. In this paper, the effect of plasma assisted combustion on pollutant emissions of a premixed flame of natural gas and air is investigated by using two gas analyzer systems to acquire a diversity of pollutant gases. The plasma is created by using a gliding arc discharge at the equivalence ratios of ϕ = 1.2 and 1.4, with applied electrical power ranging between 220 W and 370 W. The use of a gliding arc discharge leads to a reduction in the emissions of hydrocarbons and carbon monoxide. Meanwhile, the carbon dioxide emissions increase due to a faster oxidation of carbon monoxide and the water concentration in the exhaust gases is reduced with the use of plasma at the expense of higher hydrogen generation.

© 2016 Elsevier LtdA detailed literature review of laminar burning velocity and flammability limits of biogas mixtures combustion is presented. Biogas alone and in mixtures with other fuels is particularly significant because of its capability of application as fuels for internal combustion engines (ICEs). Therefore, a strict determination of the fundamental combustion characteristics required for their application in ICEs is crucial. Producing energy from biogas has the additional advantage of preventing its release into the atmosphere, where it results into significant air pollution. CH4 and CO2 are the main compounds of biogas, such as landfill, agricultural and sewage gas, after the removal of the trace amounts of organic compounds. For the same equivalence ratio, the presence of CO2 in the fuel feed results in substantial reduction of the laminar flame speed and flammability limits. Several research projects have shown that the decrease in the laminar flame speed of a fuel mixture containing dilution components is caused by the increase in specific heat capacity and the decrease in heat release, flame temperature and thermal diffusivity. The most promising strategies to increase the laminar burning velocity and the flammability limits of biogas are revised and discussed. The thermodynamic conditions under which these properties are determined are analyzed and the work still required for a comprehensive laminar burning velocity and flammability limits determination, at typical ICEs thermodynamic conditions, is addressed. The article provides a brief review of pollutant emissions of ICEs running on biogas and the current and future technological solutions to meet the increasing strict regulation.

© 2015 Elsevier Ltd. All rights reserved.Among the motivating factors for studies involving thermal machines is the need to increase the range of options. Thus, various systems combinations can co-exist, causing the reduced reliance on a single source. This is the context of studies involving Dual-Fuel systems. Additional to this factor is the requirement to reduce emissions. Thus, the combination of fuel, one being an alternative fuel becomes a very convenient opportunity. In this work, emissions results of a Diesel-Ethanol Dual-Fuel system are presented. A single cylinder research engine with diesel direct injection and port ethanol injection that aim to form a homogeneous air-fuel mixture in the intake port was used. The initial idea was to achieve the highest possible diesel substitution rate by ethanol. After investigation, described in a previous study with different compression ratios, different flow structures, different diesel injectors' flows and injection pressures it was found that the highest substitution rate occurred with higher injector flow, compression ratio of 17:1, high swirl flow structure. The present work will discuss the emissions results obtained in that engine configuration which was considered optimal balance between diesel substitution rate and efficiency. Diesel Engine Operating in Diesel-Ethanol Dual-Fuel mode reduced the NOx emission in up to 60%. On the other hand, there was increase of the THC, the CO and the aldehydes, showing a trade-off that must be further investigated with a final design engine, in the beginning of product development process.

The use of engines is necessary to keep the world moving. Such engines are fed mainly by fossil fuels, among these, the diesel. The operation and the behavior of engines in different thermodynamic cycles, with common fossil fuels, it is still challenging but, in general, it has well known and documented data. On the other hand, for alternative fuels, there is still demand of experimental data, particularly considering that it is desirable, most of the times, the use of a system with dual mode (reversible). Such systems are called Dual-Fuel, it brings a greater degree of freedom, but imply in technological challenges. In this paper we used an engine operating with single cylinder direct injection diesel and port ethanol injection system in Dual-Fuel mode with a 100% electronically controlled calibration. The methodology applied was, once the engine calibration was given to achieve the best specific fuel consumption or the MBT (Maximum Brake Torque) in each load condition, to gradually substitute the diesel oil by ethanol in compliance with the requirements established. Comparisons were made among working conditions considering the rate of diesel substitution and the energy indicated efficiency. Initially, the flow structure in the combustion chamber was tested in both 'quiescent' and high "swirl" modes. Compression ratios were adjusted at 3 different levels: 14:1, 16:1 and 17:1. It was tested two injectors, the first one of 35 g/s and another of 45 g/s. Regarding pressure diesel injection, 4 levels were investigated namely 800, 1000, 1200 and 1400 bar. © 2014 Elsevier Ltd. All rights reserved.

© 2014 by Nova Science Publishers, Inc. All rights reserved.Diesel engines are not only among the most applicable internal combustion engines today, but they are also one of the biggest polluters. There is great concern, in particular, with the emissions of NOx and particulates; EGR (Exhaust Gas Recirculation) is among the techniques used to reduce NOx emissions. This technique involves, besides a detailed study of integrated devices, accurate calibration regarding the achievement of the ideal EGR rate. This is because in addition to the NOx emissions, particulate matter emissions should also be evaluated without losing sight of their performance parameters. This work will present a detailed experimental study carried out with ACTEON, a four-cylinder engine that meets Euro III emission standards. This engine has an urban application, i.e., it works most of the time at low rotational speeds. In this important, operating range, a high rate of EGR is required for emission levels to be met. Different EGR configurations were studied by varying the EGR rate from 2.5 to 28 %. The values of emissions and performance will also be presented. The definition of the study conditions was carried out after the application of the Design of Experiments (DoE) technique. Findings are detailed for the most critical operating conditions.

The liquid-liquid bipropellant pressure swirl atomizers have been widely used in rocket engines to take advantage of their high mixing efficiency within the short length of the combustion chamber. In this kind of engine, the uniform mass distribution and propellant mixture ratio have great influence on combustion efficiency and instability. The present work investigates the effect of the number of tangential passages on the spray cone angle, mass distribution, and propellant mixture ratio of a bipropellant atomizer. Thus, three atomizers were designed, manufactured, and evaluated experimentally. The results showed that the number of tangential passages has some influence on the circumferential mass distribution; however, spray angle and propellant mixture ratio have not presented significant variations. © The Brazilian Society of Mechanical Sciences and Engineering 2013.

ITA and EMBRAER are currently executing the research project Automation of Aircraft Structural Assembly (AASA) whose goal is to implement a robotic cell for automating the riveting process of aeronautical structures. The proposal described herein complements the AASA project, adds other manufacturing processes, namely sanding and polishing of aircraft surfaces. To implement the additional processes AASA project resources and facilities were used (robots and metrology systems) and devices designed and/or acquired to allow sharing of these resources. Among these, an Automatic Tooling Support for AERonautics structures (ATS-AER) was designed and built; also, a robot tool changer with high load capacity was acquired. The outcome of this research project is the evaluation of the feasibility of automating the processes of sanding and polishing metal surfaces in the aircraft manufacture using robots. The operating method adopted for surface treatment employed the 'U' type trajectory optimised to be run by a KUKA robot KR 500. The sanding process has been applied to aluminum metal sheet specimen sized 2.18ft2 (0.20m2) and used commercial 600 and 800 sandpaper. The automated sanding process yielded an average value of RA 0.48 ± 0.08 which is 25% more efficient when compared to the traditional, manual process whose average value of RA is 0.75 ± 0.51.

The main focus of the present work is to evaluate the performance of the Helmholtz resonators to control acoustic instabilities inside combustion chambers. In the present stage of this work, some tests were conducted with non-reactive flow inside the combustion chamber. This paper presents a methodology to design the resonators and the calculations to theoretically determine the acoustic performance of damp instabilities, an experimental setup especially developed to study instabilities in reactive and non-reactive flows, and the experimental results for non-reactive situation with and without flow. The results show that the resonator has an exceptional capacity to damp the oscillations in the frequency of the design; but, it has a narrow range of actuation close to the design frequency. In addition, the experiments show that the resonator presence can modify the spectrum of frequencies, and in some cases it amplifies the oscillations, having the flow velocity inside the chamber some considerable influence in the performance attenuation. © 2013 Elsevier Ltd. All rights reserved.

Diesel engine technology has been driven by increasingly stringent environmental legislation. To comply with these laws, emissions-control systems are being rapidly improved. Within this context, development of exhaust gas after-treatment systems undertakes a significant role. Among the techniques used is selective catalytic reduction (SCR), which converts nitrogen oxides (NO x) into diatomic nitrogen (N2) and water (H2O). A reducing agent containing ammonia (NH3) is added to the flow and absorbed by a catalyst. Different reducing agents are currently used, principally anhydrous NH3, aqueous NH3, and urea. This study analyzed behavior of different urea- and formamide-based agents to SCR. Results are compared to those obtained with Adblue. In relation to the SCR system as well as to NOx reduction, we concluded that urea-based mixtures are the most efficient, although they present higher values of NH 3 slip. Formamide-based mixtures are significantly less efficient than urea-based mixtures, but the NH3 slip levels produced by these mixtures are virtually none. A challenge is to find new reducing agent for SCR applications, considering that the deposits of urea formed during certain work conditions are a significant problem. © Copyright 2013, Mary Ann Liebert, Inc.

Diesel engines are among the most effective engines in the world. Known as strong, economical and robust, they are also recognized for their traditional smoke and high level of nitrous oxides, NOx emissions. In the present study, a basic diesel engine that meets Euro III emissions standards with NOx concentration limited to 5.0 g/kW h and the particulate matter limited to 0.100 g/kW h was performed in order to evaluate its potential of attending Euro VI standards by developing Exhaust Gas Recirculation (EGR) technique. Euro VI will be used in the European community only in 2013 with NOx limited to 0.4 g/kW h and particulate matter to 0.01 g/kW h. The main idea is to achieve Euro VI emissions level, changing the EGR components and tuning the injection system. In order to reduce the investigation phase, statistics evaluation were used to define one specific speed and load that render the worst condition to create a high EGR volume at lower speed. The study was driven in two steps. Firstly, it was identified the components of EGR system which had more influence towards NOx reduction associated with fuel consumption and the particulate matter. Secondly, the components improved were implemented to analyze the engine potential. In total three different EGR configurations were performed and the best results obtained with the last version was NOx value equal 0.58 g/kW h, what means 8.6 times less than the start values and MIRA, one indicative of particulate matter, which reached 0.1 g/kW h, 62.96% smaller than 0.27 g/kW h at the beginning. Also, the specific fuel consumption achieved of 208 g/kW h was less than the value early defined as a goal which was of 210 g/kW h. After these results were obtained in the worst operational condition, it was assumed that the engine had potential to reach Euro VI. Thus, it was submitted to one integral test, the same as the one done during the certification process. The final test showed satisfactory results which means that the strategies used in the present study can be applied to get some insight into engines nowadays and in the future. © 2010 Elsevier Ltd. All rights reserved.

The presence of an acoustic actuation can drastically change the structure of a diffusion flame produced in a cylindrical burner. This work presents a spectroscopic study of the soot and instable radicals (CH* and C2*) chemiluminescent emissions in an acoustic excited jet diffusion flame of Liquefied Petroleum Gas - LPG. Frequencies from 500 Hz to 600 Hz and sound pressures between 490 Pa and 2730 Pa were employed. Planar Image Velocimetry (PIV) experiments were carried out in order to understand the acoustic effect in the velocity field profile. Frequency of 575 Hz and 600 Hz conditions presented more effective acoustic performance, making the flame begin to show characteristics of a partially premixed flame. A reduction in the soot emission and an increase of the instable radicals were also observed. The PIV results showed a sequence of periods of expansion and compression of the fuel with the acoustic actuation, what led to an increased rate of air-fuel mixture, changing the flame structure. © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

This paper proposes the study of the first bending mode of the wing's UAV Vector-P using impact methodology. The data acquisition and signal processing was implemented using LabView. The analysis provides frequency response, but needs an algorithm which was made in MATLAB®. This algorithm, called Model Identification, also provide eigenvalues and eigenvectors. MEMS accelerometers were used for input measurement and an impact hammer for output. In this work, the accelerometers were calibrated based on ISO 16063-21 as reference. After this, one notch filter equation is provided for the bending mode frequency using MATLAB®. It was used the DIAMOND software that owns the capability of the modal identification, allowing directly explore the effects of test conditions on the identified modal parameters. © 2013 SAE INTERNATIONAL.

The main objective of this study was to experimentally obtain the most representative linear dynamic model of a two-stroke piston engine for small unmanned aerial vehicle applications with low-cost sensors and a friendly interface based on laboratory virtual instrument engineering workbench (LabVIEW®). The engine was mounted on a test bed equipped to measure the thrust and rotational speed. The throttle lever was actuated by a standard hobby servo motor, which controlled the carburettor's valve opening. Input command and data acquisition were performed in a two-layer approach: low-cost hardware, where a micro-controller unit managed the sensor's readings, servo input, and external communications through serial protocol; and LabVIEW for command signal generation, serial port write/read, data processing, and other high-level tasks. The motor dynamics, represented by its transfer function, was obtained by minimizing the output error between the experimental responses to various types of input signal and that obtained by the simulation of a fixed-topology, fixed-order reference model that included the servo and engine models in series. © 2011 IMechE.

Noise level in a marine environment has become an important topic of research for the scientific community as legislations in some countries have been increasingly severe in this field. Human-generated sound in the sea comes from a variety of inevitable sources, including commercial ship traffic, oil and gas exploration and production, marine and coastal construction, and hydro-acoustic research. The main objective of this work is to present a developed LabVIEW®-based interface virtual instrument that can assist in the acquisition and interpretation of data in a typical acoustic impact analysis in a marine environment. While other programming languages use text-based routines, LabVIEW uses a graphical programming language, G, allowing for a simple and customizable solution for underwater sound acquisition. © 2012 Elsevier Ltd.

In this work is proposed the automation of a gas injection (mass flow) system in order to generate timemultiplex SF6/CH4 radiofrequency plasma applied for silicon (Si) etching process. The control of the gas injection system is important in order to better control the process anisotropy, i.e., the high-aspect-ratio of mask pattern transfer to substrate surface. In other words, this control allows the attainment of deep Si etching process. Here, the automation of the gas injection system was realized through the interface between a computer and a data acquisition board. The automation software developed allows controlling the gas flow rate switching it on and off during whole process through the use of a square waveform routine, intermittent flow, beyond the conventional condition of a fixed value for gas flow rate, continuous flow. In order to investigate the time-multiplex SF6/CH4 plasma etching of Si, the residual gas analysis was performed. The investigations were made keeping the following process parameters: flow of SF6: 10 sccm, flow of CH4: 6 sccm, 100 W rf power, wave period: 20 sec. It were monitored the partial pressure of SF+ 5 (parent neutral specie: SF6), CH+4 (CH4) and SiF+ 3 (SiF4) species as a function of time for different gas flow switching and duty cycle. The results showed that with the generation of plasma occurs a drastic change in behavior of partial pressures of SF+ 5 and CH+4 species. Moreover, it is evidenced that the interactions between the SF6 and CH4 fragments promotes a high production rate of HF molecule and consequently a decrease of atomic fluorine, mainly when plasma is on. Finally, the behavior of partial pressure of SiF+ 3 specie for alternatively intermittent SF6 and CH4 flow operation shows us that both the etching processes and the deposition of a polymer passivation layer are occurring alternatively, a desirable feature for multi-step etching process. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The main objective of this work was to present the specification of an experimental firing test stand for liquid rocket engines (LRE) and develop a program for control and acquisition of data. It provides conditions to test rocket engines with thrust from 50 to 100 kgf. A methodology for laboratory work implementation using information technology, which will allow the automatic and remote functioning of the test stand, permits users to input the necessary data to conduct tests safely, achieve accurate measurements and obtain reliable results. The control of propellant mass flow rates by pressure regulators and other system valves, as well as the test stand data acquisition, are carried out automatically through LabVIEW commercial software. The test stand program is a readable, scalable and maintainable code. The test stand design and its development represent the state of art of experimental apparatus in LRE testing.

The effects of combustion driven acoustic oscillations in carbon monoxide and nitrogen oxides emission rates of a combustor operated with liquefied petroleum gas (LPG) were investigated. Because the fuel does not contain nitrogen, tests were also conducted with ammonia injected in the fuel, in order to study the formation of fuel NOx. The main conclusions were: (a) the pulsating combustion process is more efficient than the non-pulsating one and (b) the pulsating combustion process generates higher rates of NO x, with and without ammonia injection, as shown by CO and NO concentrations as function of the O2 concentration. An increase in the LPG flow rate, keeping constant the air to fuel ratio, increased the acoustic pressure amplitude and the frequency of oscillation. The injection of ammonia had no influence on either pressure amplitude or frequency. © 2005 Elsevier Ltd. All rights reserved.

This paper reports the construction of an axisymmetric nonpremixed piloted jet burner, with well-defined initial and boundary conditions, known as the Delft burner, to assess turbulence-chemistry interaction in non-premixed turbulent flames. Detailed experimental information is described, involving hot-wire anemometry, thin-wire thermocouples and chemiluminescence visualization measurements. Radial profile of the axial mean velocity indicates excellent agreement between flow patterns developed within Delft installation and the one described herein. Chemiluminescence emissions from CH and C2 free-radicals were acquired with a CCD camera. Tomography reconstruction analysis was utilised to compare radical emissions and temperature spatial distributions. There was a strong dependence between temperature and CH/C 2 emissions. This is an indication that these radicals can be used in flame front studies.