Simulations of Injection, Mixing, and Combustion in Supersonic Flow Using a Hybrid RANS/LES Approach PDF Download

Author: David Michael Peterson
Publisher:
ISBN:
Category :
Languages : en
Pages : 122

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Author: Peter Cocks
Publisher:
ISBN:
Category :
Languages : en
Pages :

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This work evaluates the capabilities of the RANS and LES techniques for the simulation of high speed reacting flows. These methods are used to gain further insight into the physics encountered and regimes present in supersonic combustion. The target application of this research is the scramjet engine, a propulsion system of great promise for efficient hypersonic flight. In order to conduct this work a new highly parallelised code, PULSAR, is developed. PULSAR is capable of simulating complex chemistry combustion in highly compressible flows, based on a second order upwind method to provide a monotonic solution in the presence of high gradient physics. Through the simulation of a non-reacting supersonic coaxial helium jet the RANS method is shown to be sensitive to constants involved in the modelling process. The LES technique is more computationally demanding but is shown to be much less sensitive to these model parameters. Nevertheless, LES results are shown to be sensitive to the nature of turbulence at the inflow; however this information can be experimentally obtained. The SCHOLAR test case is used to validate the reacting aspects of PULSAR. Comparing RANS results from laminar chemistry and assumed PDF combustion model simulations, the influence of turbulence-chemistry interactions in supersonic combustion is shown to be small. In the presence of reactions, the RANS results are sensitive to inflow turbulence, due to its influence on mixing. From complex chemistry simulations the combustion behaviour is evaluated to sit between the flamelet and distributed reaction regimes. LES results allow an evaluation of the physics involved, with a pair of coherent vortices identified as the dominant influence on mixing for the oblique wall fuel injection method. It is shown that inflow turbulence has a significant impact on the behaviour of these vortices and hence it is vital for turbulence intensities and length scales to be measured by experimentalists, in order for accurate simulations to be possible.

Author: Riccardo Bonazza
Publisher: Springer
ISBN: 331916838X
Category : Science
Languages : en
Pages : 822

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This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion, Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interested in these fields.

Author: Mohammed Kamel
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659387043
Category :
Languages : en
Pages : 208

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The design and off-design studies of the hypersonic air-breathing engines face many challenges, due to the complexity of their internal flows. The mixing and combustion processes in Supersonic-Combustion Ramjet (scramjet) engines involve complicated aerothermochemical features, such as: the interactions between shock-waves and boundary-layer, the shock induced-combustion and the recirculation zones. In this study, a numerical solver is developed and validated to be an efficient design tool capable of simulating these complicated flow features of the supersonic combustors. For the code validation, several test cases are considered to monitor the code ability to solve for the diffusive and turbulent fluxes, and the chemical source term. In addition, the code is validated by resolving the transverse sonic injection into supersonic air flow in the case of Helium injection from a flat plate, and in the case of Hydrogen injection in a single-strut scramjet engine. The effectiveness of this injection technique in mixing and flame-holding is demonstrated. The results show good agreement with the previous numerical and experimental investigations, and prove the simulator's accuracy.

Author: Heeseok Koo
Publisher:
ISBN:
Category :
Languages : en
Pages : 398

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The main objective of this dissertation is to develop large-eddy simulation (LES) based computational tools for supersonic inlet and combustor design. In the recent past, LES methodology has emerged as a viable tool for modeling turbulent combustion. LES computes the large scale mixing process accurately, thereby providing a better starting point for small-scale models that describe the combustion process. In fact, combustion models developed in the context of Reynolds-averaged Navier Stokes (RANS) equations exhibit better predictive capability when used in the LES framework. The development of a predictive computational tool based on LES will provide a significant boost to the design of scramjet engines. Although LES has been used widely in the simulation of subsonic turbulent flows, its application to high-speed flows has been hampered by a variety of modeling and numerical issues. In this work, we develop a comprehensive LES methodology for supersonic flows, focusing on the simulation of scramjet engine components. This work is divided into three sections. First, a robust compressible flow solver for a generalized high-speed flow configuration is developed. By using carefully designed numerical schemes, dissipative errors associated with discretization methods for high-speed flows are minimized. Multiblock and immersed boundary method are used to handle scramjet-specific geometries. Second, a new combustion model for compressible reactive flows is developed. Subsonic combustion models are not directly applicable in high-speed flows due to the coupling between the energy and velocity fields. Here, a probability density function (PDF) approach is developed for high-speed combustion. This method requires solution to a high dimensional PDF transport equation, which is achieved through a novel direct quadrature method of moments (DQMOM). The combustion model is validated using experiments on supersonic reacting flows. Finally, the LES methodology is used to study the inlet-isolator component of a dual-mode scramjet. The isolator is a critical component that maintains the compression shock structures required for stable combustor operation in ramjet mode. We simulate unsteady dynamics inside an experimental isolator, including the propagation of an unstart event that leads to loss of compression. Using a suite of simulations, the sensitivity of the results to LES models and numerical implementation is studied.

Author: Debi Prasad Mishra
Publisher: Springer Nature
ISBN: 9811934983
Category : Technology & Engineering
Languages : en
Pages : 334

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The book presents select proceedings of the International Conference on Mechanical Engineering (INCOME 2021). It presents the topics related to thermal and fluid mechanics including various sources of energy. The topics covered include theoretical and practical aspects of thermal and fluid systems and thermal design of the related equipment. The book also includes latest topics such as solar energy, computational techniques, enhancement of energy storage capacity, fluid solid interaction, and hybrid energy systems. The book will be a valuable reference for beginners, researchers, and professionals interested in research, design and development in thermal and fluid sciences.

Author: Mostafa Barzegar Gerdroodbary
Publisher: Butterworth-Heinemann
ISBN: 0128211407
Category : Technology & Engineering
Languages : en
Pages : 230

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Book Description
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

Author: Mingbo Sun
Publisher: Springer
ISBN: 9811360251
Category : Technology & Engineering
Languages : en
Pages : 284

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Book Description
Based on research into jets in supersonic crossflow carried out by the authors’ team over the past 15 years, this book summarizes and presents many cutting-edge findings and analyses on this subject. It tackles the complicated mixing process of gas jets and atomization process of liquid jets in supersonic crossflow, and studies their physical mechanisms. Advanced experimental and numerical techniques are applied to further readers’ understanding of atomization, mixing, and combustion of fuel jets in supersonic crossflow, which can promote superior fuel injection design in scramjet engines. The book offers a valuable reference guide for all researchers and engineers working on the design of scramjet engines, and will also benefit graduate students majoring in aeronautical and aerospace engineering.

Author: C. T. Bowman
Publisher:
ISBN:
Category :
Languages : en
Pages : 28

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Book Description
An experimental and computational investigation of supersonic combustion flows is in progress. The principal objective of the research is to gain a more fundamental understanding of mixing and chemical reaction in supersonic flows. The research effort comprises three inter-related elements: 1) an experimental study of mixing and combustion in a supersonic plane mixing layer; 2) development of laser-induced fluorescence techniques for time-resolved two-dimensional imaging of species concentration, temperature, velocity and pressure; and, 3) numerical simulations of compressible reacting flows. The design of the supersonic plane mixing layer was completed and the high-pressure gas storage system was installed. The pulsed lasers and camera systems, to be used for two-dimension flow field imaging, were installed and initial performance evaluations are in progress. This work has focussed on development of appropriate numerical methods for performing full-turbulence simulations of high-speed compressible flows and on the application of these methods to temporally and spatially developing compressible mixing layers. The effort to date has identified several promising numerical methods for compressible flow problems. In addition, a code was developed for compressible mixing layers, and initial simulation using this code shows interesting features, such as imbedded shock waves, in high-speed mixing layers. Keywords: Turbulent reacting flow, Laser diagnostics, Computational fluid dynamics.

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722913984
Category :
Languages : en
Pages : 108

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Book Description
Research has been undertaken to achieve an improved understanding of physical phenomena present when a supersonic flow undergoes chemical reaction. A detailed understanding of supersonic reacting flows is necessary to successfully develop advanced propulsion systems now planned for use late in this century and beyond. In order to explore such flows, a study was begun to create appropriate physical models for describing supersonic combustion, and to develop accurate and efficient numerical techniques for solving the governing equations that result from these models. From this work, two computer programs were written to study reacting flows. Both programs were constructed to consider the multicomponent diffusion and convection of important chemical species, the finite rate reaction of these species, and the resulting interaction of the fluid mechanics and the chemistry. The first program employed a finite difference scheme for integrating the governing equations, whereas the second used a hybrid Chebyshev pseudospectral technique for improved accuracy. Drummond, J. Philip Langley Research Center BOUNDARY LAYERS; CHEMICAL REACTIONS; FLUID MECHANICS; MIXING; MIXING LAYERS (FLUIDS); NUMERICAL ANALYSIS; SIMULATION; SUPERSONIC FLOW; CHEBYSHEV APPROXIMATION; COMPUTER PROGRAMS; FINITE DIFFERENCE THEORY; HYPERSONIC AIRCRAFT; SUPERSONIC COMBUSTION RAMJET ENGINES...