Download or read book Optimization of Fuel air Mixing for a Scramjet Combustor Geometry Using CFD and a Genetic Algorithm written by and published by . This book was released on 2008 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coupling Computational Fluid Dynamics Analysis and Optimization Techniques for Scramjet Engine Design written by Nathan T. McGillivray and published by . This book was released on 2018 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Various aspects of hypersonic vehicles are being rapidly explored for improved functionality. One of the main areas of consideration is the fueling of a Supersonic Combusting Ramjet (scramjet) engine. Using Computational Fluid Dynamics (CFD), computer simulations can be performed to analyze the flow physics of a scramjet. In this research, an optimization code, Dakota, is integrated with the CFD to optimize a set of parameters to maximum thrust. In this study, the fuel injection and combustion is replaced with heat sources. This simplification greatly reduces the computational requirements. Additionally, the 3D geometry is reduced to an axisymmetric 2D geometry because three dimension effects like mixing and combustion are not being modeled. With this simplified model, the optimization and CFD algorithm is executed to find the heat addition for maximum thrust. Different optimization methods have been explored to reduce computational times. A genetic algorithm was selected because of its robust abilities. Additionally, a sampling algorithm was selected because of its abilities to explore the whole design space. Furthermore, the sampling method enables additional studies, such as sensitivity studies, to be completed. In addition to optimization studies, calibration studies are performed to obtain the heat source values that correspond to a given experimental wall pressure distribution. Knowledge of the optimized heat distribution will assist in the optimization of fueling splits and injector locations for a more detailed combustion investigation in which similar optimization techniques can be applied.
Download or read book A Variable Complexity Modeling Approach to Scramjet Fuel Injection Array Design Optimization written by Michael D. Payne and published by . This book was released on 1998-03-01 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: The analysis of fuel air mixing in a scramjet is often accomplished either with Computational Fluid Dynamics (CFD) algorithms or through experimental research. These approaches, while accurate and reliable, are extremely expensive and thus not well suited for use with conventional design optimization methods. In this investigation, Variable Complexity Modeling (VCM) is used to significantly reduce the number of complex, expensive analyses required to optimize the design of a scramjet fuel injection array. A design problem formulation for a lateral transverse injection array is developed and a VCM approach to design optimization is conducted in two stages. Initially, a simplified analysis model is used to provide relatively inexpensive predictions of design fuel air mixing characteristics. A parametric analysis is conducted to explore the design region, and a preliminary optimal design is found using both Sequential Quadratic Programming and a Genetic Algorithm. In the second stage, response surface methodology is supplemented with preliminary stage information to minimize the number of expensive analyses required to finalize the design. It is shown that only 25 design evaluations are required to develop a near optimal design.
Download or read book Scramjets written by Mostafa Barzegar Gerdroodbary and published by Butterworth-Heinemann. This book was released on 2020-07-21 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scramjet engines are a type of jet engine and rely on the combustion of fuel and an oxidizer to produce thrust. While scramjets are conceptually simple, actual implementation is limited by extreme technical challenges. Hypersonic flight within the atmosphere generates immense drag, and temperatures found on the aircraft and within the engine can be much greater than that of the surrounding air. Maintaining combustion in the supersonic flow presents additional challenges, as the fuel must be injected, mixed, ignited, and burned within milliseconds. Fuel mixing, along with the configuration and positioning of the injectors and the boundary conditions, play a key role in combustion efficiency. Scramjets: Fuel Mixing and Injection Systems discusses how fuel mixing efficiency and the advantage of injection systems can enhance the performance of the scramjets. The book begins with the introduction of the supersonic combustion chamber and explains the main parameters on the mixing rate. The configuration of scramjets is then introduced with special emphasis on the main effective parameters on the mixing of fuel inside the scramjets. In addition, basic concepts and principles on the mixing rate and fuel distribution within scramjets are presented. Main effective parameters such as range of fuel concentration for the efficient combustion, pressure of fuel jet and various arrangement of jet injections are also explained. This book is for aeronautical and mechanical engineers as well as those working in supersonic combustion who need to know the effects of compressibility on combustion, of shocks on mixing and on chemical reactions, and vorticity on the flame anchoring. - Explains the main applicable approaches for enhancement of supersonic combustion engines and the new techniques of fuel injection - Shows how the interaction of main air stream with fuel injections can develop the mixing inside the scramjets - Presents results of numerical simulations and how they can be used for the development of the combustion engines
Download or read book Scramjet Combustion written by Gautam Choubey and published by Butterworth-Heinemann. This book was released on 2022-07-08 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scramjet Combustion explores the development of a high-speed scramjet engine operating in the supersonic/hypersonic range for various air and space transport applications. The book explains the basic structure, components, working cycle, and the relevant governing equations in a clear manner that speaks to both advanced and more novice audiences. Particular attention is paid to efficient air–fuel combustion, looking at both the underlying fundamentals of combustion as well strategies for obtaining optimum combustion efficiency. Methods for reaching the chemically correct air–fuel ratio, subsequent flame, and combustion stabilization as air enters at supersonic speed are also outlined. Further, it includes the continuous on-going efforts, innovations, and advances with respect to the design modification of scramjet combustors, as well as different strategies of fuel injections for obtaining augmented performance while highlighting the current and future challenges. - Outlines the fundamentals of scramjet engines including their basic structure and components, working cycle, governing equations, and combustion fundamentals affecting the combustion and mixing processes - Presents new design modifications of scramjet combustors and different fuel injection strategies including combined fuel injection approaches - Discusses core topics such as chemical kinetics in supersonic flow, fuel–air mixing methods, strategies for combating combustion difficulties, and subsequent flame and combustion stabilization that can be applied to scramjets - Describes the pedagogy for computational approaches in simulating supersonic flows
Download or read book Modeling Control and Optimization of Fuel Air Mixing in a Lean Premixed Swirl Combustor Using Fuel Staging to Reduce Pressure Pulsations and NOx Emissions written by Arnaud Lacarelle and published by Univerlagtuberlin. This book was released on 2011 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of Improved CFD Tools for the Optimization of a Scramjet Engine written by Francis A. Centlivre and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the present work, a plugin has been developed for use with the DoD HPCMP CREATE-AV Kestrel multi-physics solver that adds volumetric source terms to the energy equation. These source terms model the heat released due to combustion, but are much more computationally efficient than a full chemistry model. A thrust-based optimization study was then carried out under the control of Sandia National Laboratories' Dakota toolkit. Dakota was allowed to control the amount of heat added to three regions of the scramjet combustor. The plugin was then extended to consider ignition delay time. By comparing ignition delay time to dwell time, it is possible to determine whether the fuel in a cell should be combusted. Results from this analysis are compared to results gathered using a 22-species chemistry model. The ignition delay source term is shown to capture relevant flow physics at a reduced computational cost. Additionally, the expression for second-law (exergetic) efficiency for a scramjet engine is derived and optimized using Dakota. Finally, Dakota was extended to control the geometry of the scramjet engine, allowing for the numerical optimization of the scramjet expansion system. The results from these computationally-efficient optimizations can then be used to inform researchers of potentially optimal solutions before higher-fidelity models are used.
Download or read book Analysis of Fuel Vaporization Fuel Air Mixing and Combustion in Integrated Mixer Flame Holders written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-27 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Requirements to limit pollutant emissions from the gas turbine engines for the future High-Speed Civil Transport (HSCT) have led to consideration of various low-emission combustor concepts. One such concept is the Integrated Mixer-Flame Holder (IMFH). This report describes a series of IMFH analyses performed with KIVA-II, a multi-dimensional CFD code for problems involving sprays, turbulence, and combustion. To meet the needs of this study, KIVA-II's boundary condition and chemistry treatments are modified. The study itself examines the relationships between fuel vaporization, fuel-air mixing, and combustion. Parameters being considered include: mixer tube diameter, mixer tube length, mixer tube geometry (converging-diverging versus straight walls), air inlet velocity, air inlet swirl angle, secondary air injection (dilution holes), fuel injection velocity, fuel injection angle, number of fuel injection ports, fuel spray cone angle, and fuel droplet size. Cases are run with and without combustion to examine the variations in fuel-air mixing and potential for flashback due to the above parameters. The degree of fuel-air mixing is judged by comparing average, minimum, and maximum fuel/air ratios at the exit of the mixer tube, while flame stability is monitored by following the location of the flame front as the solution progresses from ignition to steady state. Results indicate that fuel-air mixing can be enhanced by a variety of means, the best being a combination of air inlet swirl and a converging-diverging mixer tube geometry. With the IMFH configuration utilized in the present study, flashback becomes more common as the mixer tube diameter is increased and is instigated by disturbances associated with the dilution hole flow.Deur, J. M. and Cline, M. C.Glenn Research CenterGAS TURBINE ENGINES; FLAME HOLDERS; VAPORIZING; COMBUSTION; COMPUTATIONAL FLUID DYNAMICS; MIXERS; FUEL INJECTION; CONVERGENT-DIVERGENT NOZZLES; COMBUSTION CHAMBERS; FLAME PROPAGATION; FUEL SPRAY...
Download or read book Quasi one dimensional Scramjet Combustor Flow Solver Using the Numerical Propulsion System Simulation written by Long Vu and published by . This book was released on 2019 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow field inside a scramjet engine combustor involves complex phenomena such as fuel-air mixing, combustion chemistry, and flow separation. In order to determine the properties of the flow along the length of the combustor, mass, momentum and energy balance equations are solved simultaneously using a numerical method. While a full three dimensional computational simulation gives detailed results with high order of accuracy, it demands a great amount of time and computational resource. A low order analysis produces a fast overall picture of the combustor operation which in turn provides valuable information suitable for the preliminary design process. This research work aims to describe the analysis process of the scramjet combustor in which a quasi-one-dimensional, multi-species, reacting real gas model of the flow is developed to address the limitations in previous researches. The Numerical Propulsion System Simulation (NPSS), into which the NASA Chemical Equilibrium with Applications (CEA) code is integrated, is utilized as the platform to perform the analysis. The analytical model is validated by comparison with experimental data from previous researches. The results obtained by this method are expected to shed some light on the advantages of using detailed chemistry with lower order analysis to calculate scramjet engine performance.
Download or read book Fuel air Mixing and Combustion in Scramjets written by J. P. Drummond and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CFD Study on Hydrogen Engine Mixture Formation and Combustion written by Fushui Liu and published by Cuvillier Verlag. This book was released on 2004 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA 2008 6925 written by Chung-Jen Tam and published by . This book was released on 2008 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hypersonic Vehicles written by Giuseppe Pezzella and published by BoD – Books on Demand. This book was released on 2019-10-02 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the aviation field there is great interest in high-speed vehicle design. Hypersonic vehicles represent the next frontier of passenger transportation to and from space. However, several design issues must be addressed, including vehicle aerodynamics and aerothermodynamics, aeroshape design optimization, aerodynamic heating, boundary layer transition, and so on. This book contains valuable contributions focusing on hypervelocity aircraft design. Topics covered include hypersonic aircraft aerodynamic and aerothermodynamic design, especially aeroshape design optimization, computational fluid dynamics, and scramjet propulsion. The book also discusses high-speed flow issues and the challenges to achieving the dream of affordable hypersonic travel. It is hoped that the information contained herein will allow for the development of safe and efficient hypersonic vehicles.
Download or read book Multi mode Genetic Algorithm Optimization of Combustion Chamber Geometry for Low Emissions written by and published by . This book was released on 2002 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Innovative Techniques to Improve Mixing and Penetration in Scramjet Combustors written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Scramjet combustors are characterized by an extremely short residence time for the completion of fuel atomization, mixing and combustion. It is therefore desired to develop fuel injection schemes that will accelerate the mixing process by improving penetration, achieving small-dispersed fuel droplets, and enhancing mixing. To date, scramjet-fueling schemes require multiple fuel-injection locations in conjunction with flame-holding cavities. This thesis involves the design, development and testing of two innovative fuel injection strategies that could be used to precisely enhance mixing and control the fuel distribution in a scramjet combustor. The first approach employs a high frequency-forcing injector where the amplitude and frequency of excitation was chosen to affect both jet spread and penetration depth, independently, by excitation at different jet instability modes. Another novel fuel injection technique is to employ a vortex-breakdown-controlled injector, which includes a swirling annular jet combined with a control non-swirling jet. The vortex is stabilized by injection of a continuous jet near the core of the vortex. When the control jet introduces additional momentum along the vortex mean flow, the breakdown is delayed. This has been used to control both the intensity of vortex breakdown and penetration of the jet, which could be effectively applied to enhance mixing and penetration.
Download or read book Large Engine Technology Program Task 22 written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the task reported herein was to define, evaluate, and optimize variable geometry concepts suitable for use with a Rich-Quench-Lean (RQL) combustor. The specific intent was to identify approaches that would satisfy High Speed Civil Transport (HSCT) cycle operational requirements with regard to fuel-air ratio turndown capability, ignition, and stability margin without compromising the stringent emissions, performance, and reliability goals that this combustor would have to achieve. Four potential configurations were identified and three of these were refined and tested in a high-pressure modular RQL combustor rig. The tools used in the evolution of these concepts included models built with rapid fabrication techniques that were tested for airflow characteristics to confirm sizing and airflow management capability, spray patternation, and atomization characterization tests of these models and studies that were supported by Computational Fluid Dynamics analyses. Combustion tests were performed with each of the concepts at supersonic cruise conditions and at other critical conditions in the flight envelope, including the transition points of the variable geometry system, to identify performance, emissions, and operability impacts. Based upon the cold flow characterization, emissions results, acoustic behavior observed during the tests and consideration of mechanical, reliability, and implementation issues, the tri-swirler configuration was selected as the best variable geometry concept for incorporation in the RQL combustor evolution efforts for the HSCT. Tacina, Robert R. (Technical Monitor) and Cohen, J. M. and Padget, F. C. and Kwoka, D. and Wang, Q. and Lohmann, R. P. Glenn Research Center NAS3-26618; WBS 22-714-09-46
