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Development Of A Turbulent Burning Velocity Model Based On Flame Stretch Concept For Spark Ignition Engines
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Book Synopsis DEVELOPMENT OF A TURBULENT BURNING VELOCITY MODEL BASED ON FLAME STRETCH CONCEPT FOR SPARK IGNITION ENGINES by :
Download or read book DEVELOPMENT OF A TURBULENT BURNING VELOCITY MODEL BASED ON FLAME STRETCH CONCEPT FOR SPARK IGNITION ENGINES written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : This PhD dissertation develops a turbulent burning velocity model based on flame stretch concept and couples it with an engine cycle simulation program (GT-Power) to improve its turbulent combustion modeling capability. In a non-turbulent mixture, flame propagation is laminar and the flame has a smooth surface. However, in a turbulent flow field (i.e. internal combustion engines), the flame front is no longer smooth. This was the motivation to experimentally study the burning velocity and flame stretch under engine in-cylinder conditions. Flame front propagation analysis showed that during the flame propagation period, the flame stretch decreased until the flame front touched the piston surface. This was a common trend for stoichiometric, lean and rich mixtures, which occurred because the flame radius was the dominant factor in flame stretch calculation. In addition, the rich fuel-air mixture (ɸ = 1.18) showed a lower flame stretch compared to stoichiometric (ɸ = 1.0) or lean mixtures (ɸ = 0.84). This was due to the lower Markstein number, the representation of flame sensitivity to flame stretch, for the rich fuel-air mixture compared to the stoichiometric or lean mixtures. The ratio of the thermal to mass diffusivity appeared to be the dominant factor in the Markstein number. Furthermore, comparing the flame stretch at three different engine speeds revealed that increasing the speed increases the flame stretch; especially during the early flame development period. In addition, dimensional analysis was utilized and a turbulent burning velocity model was developed based on the flame stretch concept. The model showed that the turbulent burning velocity decreased due to flame stretching. Although it was shown that increasing engine speed increases turbulent burning velocity by increasing the turbulent intensity (and hence the turbulent flame surface), a tradeoff between the AT/AL and the flame stretch due to higher engine speed was observed in the model. In cases where the flame distortion was very high, the flame stretch may cancel out any benefits of a large enflamed area. While the turbulent burning velocity model was developed for an optically-accessible DISI engine at low engine speed and load, it was also tested using data from a four-stroke, liquid-cooled, two-cylinder, carbureted engine at higher speeds and loads. Comparison of the engine in-cylinder pressure, heat release and performance parameters from simulation and experiments for the engine revealed that the developed turbulent burning velocity model coupled with GT-Power significantly improved the turbulent combustion modeling capability of GT-Power. In addition, simulation results showed that the flame stretch may result in a 35% reduction in turbulent burning velocity at very early (MFB This research also investigated combustion variations using 2D intensity images and compared the results to COV of IMEP computed from in-cylinder pressure data. The results revealed a strong correlation between the variations of the luminosity field during the main phase of combustion and the COV of IMEP. However, during the ignition and early (MFB Since the images consist of pixels, uncertainty analysis was conducted to determine the effect of image quality on the flame stretch. Results showed that a maximum relative uncertainty of 4.5% in the flame stretch calculation occurred during the early flame development period and it decreased to less than 1% with increasing flame radius.
Book Synopsis DEVELOPMENT OF A TURBULENT FLAME SPEED MODEL BASED ON FLAME STRETCH CONCEPT FOR SPARK IGNITION ENGINES by :
Download or read book DEVELOPMENT OF A TURBULENT FLAME SPEED MODEL BASED ON FLAME STRETCH CONCEPT FOR SPARK IGNITION ENGINES written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : This is an MSc report to develop a turbulent combustion model and couple it with engine simulation software to improve its predictive capability. For liquid or gaseous fuels one of the most important quantities is the velocity at which the flame front propagates normal to itself and relative to the flow into the unburned mixture. In a non-turbulent mixture, flame propagation is laminar and the flame has smooth surface. However, in a turbulent flow field, the flame front is no longer smooth and the reaction zone is thicker than that in laminar case. According to Damkohler theory, the increase in flame front area due to turbulence causes to increase the flame speed. However, recent studies show that the ratio of turbulent to laminar flame speed (ST/SL) depends on both the relative increase in flame surface area as a result of turbulence, and the relative drop in local flame speed as a result of stretching. The proposed research will empirically study the effect of stretching on flame speed under engine-like conditions and develop a model for flame speed base on that. For this reason, flame surface area and speed will be found by processing high speed images which are taken from flame inside cylinder. Then, the developed combustion model will be coupled with GT-Power engine simulation software in order to, first, evaluate the developed model and then, improve the GT-Power predictive combustion capability. To specify initial conditions correctly, the initial swirl and tumble values will be measured by using the steady-flow-rig method. Finally, to verify the simulation and developed turbulent combustion model, a V-twin, four-stroke, air cooled, ECH 749 Kohler engine will be used.
Book Synopsis Turbulent Flame Development in a High-pressure Combustion Vessel by : Matthew P. Ormsby
Download or read book Turbulent Flame Development in a High-pressure Combustion Vessel written by Matthew P. Ormsby and published by . This book was released on 2005 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Turbulence on Flame Initiation and Combustion Cyclic Variation in Spark Ignition Engines by : Mazen Hammoud
Download or read book Effect of Turbulence on Flame Initiation and Combustion Cyclic Variation in Spark Ignition Engines written by Mazen Hammoud and published by . This book was released on 1996 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fundamentals of Premixed Turbulent Combustion by : Andrei Lipatnikov
Download or read book Fundamentals of Premixed Turbulent Combustion written by Andrei Lipatnikov and published by CRC Press. This book was released on 2012-10-24 with total page 551 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lean burning of premixed gases is considered to be a promising combustion technology for future clean and highly efficient gas turbine combustors. Yet researchers face several challenges in dealing with premixed turbulent combustion, from its nonlinear multiscale nature and the impact of local phenomena to the multitude of competing models. Filling a gap in the literature, Fundamentals of Premixed Turbulent Combustion introduces the state of the art of premixed turbulent combustion in an accessible manner for newcomers and experienced researchers alike. To more deeply consider current research issues, the book focuses on the physical mechanisms and phenomenology of premixed flames, with a brief discussion of recent advances in partially premixed turbulent combustion. It begins with a summary of the relevant knowledge needed from disciplines such as thermodynamics, chemical kinetics, molecular transport processes, and fluid dynamics. The book then presents experimental data on the general appearance of premixed turbulent flames and details the physical mechanisms that could affect the flame behavior. It also examines the physical and numerical models for predicting the key features of premixed turbulent combustion. Emphasizing critical analysis, the book compares competing concepts and viewpoints with one another and with the available experimental data, outlining the advantages and disadvantages of each approach. In addition, it discusses recent advances and highlights unresolved issues. Written by a leading expert in the field, this book provides a valuable overview of the physics of premixed turbulent combustion. Combining simplicity and topicality, it helps researchers orient themselves in the contemporary literature and guides them in selecting the best research tools for their work.
Book Synopsis A Level Set Based Flamelet Model for the Prediction of Combustion in Homogeneous Charge and Direct Injection Spark Ignition Engines by :
Download or read book A Level Set Based Flamelet Model for the Prediction of Combustion in Homogeneous Charge and Direct Injection Spark Ignition Engines written by and published by Cuvillier Verlag. This book was released on 2006-03-01 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Concord Clothing Gazette written by and published by . This book was released on 1878 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling of End-Gas Autoignition for Knock Prediction in Gasoline Engines by : Andreas Manz
Download or read book Modeling of End-Gas Autoignition for Knock Prediction in Gasoline Engines written by Andreas Manz and published by Logos Verlag Berlin GmbH. This book was released on 2016-08-18 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: Downsizing of modern gasoline engines with direct injection is a key concept for achieving future CO22 emission targets. However, high power densities and optimum efficiency are limited by an uncontrolled autoignition of the unburned air-fuel mixture, the so-called spark knock phenomena. By a combination of three-dimensional Computational Fluid Dynamics (3D-CFD) and experiments incorporating optical diagnostics, this work presents an integral approach for predicting combustion and autoignition in Spark Ignition (SI) engines. The turbulent premixed combustion and flame front propagation in 3D-CFD is modeled with the G-equation combustion model, i.e. a laminar flamelet approach, in combination with the level set method. Autoignition in the unburned gas zone is modeled with the Shell model based on reduced chemical reactions using optimized reaction rate coefficients for different octane numbers (ON) as well as engine relevant pressures, temperatures and EGR rates. The basic functionality and sensitivities of improved sub-models, e.g. laminar flame speed, are proven in simplified test cases followed by adequate engine test cases. It is shown that the G-equation combustion model performs well even on unstructured grids with polyhedral cells and coarse grid resolution. The validation of the knock model with respect to temporal and spatial knock onset is done with fiber optical spark plug measurements and statistical evaluation of individual knocking cycles with a frequency based pressure analysis. The results show a good correlation with the Shell autoignition relevant species in the simulation. The combined model approach with G-equation and Shell autoignition in an active formulation enables a realistic representation of thin flame fronts and hence the thermodynamic conditions prior to knocking by taking into account the ignition chemistry in unburned gas, temperature fluctuations and self-acceleration effects due to pre-reactions. By the modeling approach and simulation methodology presented in this work the overall predictive capability for the virtual development of future knockproof SI engines is improved.
Book Synopsis Phenomenology and Modelling of Flame-Wall-Interactions in Spark-Ignition-Engines by : Dominik Suckart
Download or read book Phenomenology and Modelling of Flame-Wall-Interactions in Spark-Ignition-Engines written by Dominik Suckart and published by Cuvillier Verlag. This book was released on 2019-01-03 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optimization of combustion in reciprocating engines necessitates an in-depth understanding of the underlying processes as well as accurate and comprehensive physical models. In this respect, the current knowledge on the last stage of combustion in which the flame interacts with the combustion chamber walls is limited. Hence, the objective of this book is to improve the understanding of flame-wall interaction and its modelling. Using a comprehensive analysis of the existing literature on flame-wall interactions as a starting point, the quenching process in a direct-injection spark-ignition engine is investigated via a combination of highly resolved wall heat flux measurements and extensive numerical simulations in order to gain insight into the underlying physical processes. Building on the results, a consistent modelling approach is systematically derived based on the physics of flame quenching and post-flame oxidation. The resulting flame-wall interaction model is based on the G-equation combustion model and incorporates the effects of flame quenching and near-wall turbulence. Finally, the model is applied to simulate combustion in a turbulent channel flow as well as in spark-ignition engines. The results are highlighting the importance of flame-wall interactions for premixed combustion processes in engines and their prediction via simulation.
Book Synopsis Modeling Engine Spray and Combustion Processes by : Gunnar Stiesch
Download or read book Modeling Engine Spray and Combustion Processes written by Gunnar Stiesch and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: The utilization of mathematical models to numerically describe the performance of internal combustion engines is of great significance in the development of new and improved engines. Today, such simulation models can already be viewed as standard tools, and their importance is likely to increase further as available com puter power is expected to increase and the predictive quality of the models is constantly enhanced. This book describes and discusses the most widely used mathematical models for in-cylinder spray and combustion processes, which are the most important subprocesses affecting engine fuel consumption and pollutant emissions. The relevant thermodynamic, fluid dynamic and chemical principles are summarized, and then the application of these principles to the in-cylinder processes is ex plained. Different modeling approaches for the each subprocesses are compared and discussed with respect to the governing model assumptions and simplifica tions. Conclusions are drawn as to which model approach is appropriate for a specific type of problem in the development process of an engine. Hence, this book may serve both as a graduate level textbook for combustion engineering stu dents and as a reference for professionals employed in the field of combustion en gine modeling. The research necessary for this book was carried out during my employment as a postdoctoral scientist at the Institute of Technical Combustion (ITV) at the Uni versity of Hannover, Germany and at the Engine Research Center (ERC) at the University of Wisconsin-Madison, USA.
Book Synopsis 1D and Multi-D Modeling Techniques for IC Engine Simulation by : Angelo Onorati
Download or read book 1D and Multi-D Modeling Techniques for IC Engine Simulation written by Angelo Onorati and published by SAE International. This book was released on 2020-04-06 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1D and Multi-D Modeling Techniques for IC Engine Simulation provides a description of the most significant and recent achievements in the field of 1D engine simulation models and coupled 1D-3D modeling techniques, including 0D combustion models, quasi-3D methods and some 3D model applications.
Book Synopsis Modelling Spark Ignition Combustion by : P. A. Lakshminarayanan
Download or read book Modelling Spark Ignition Combustion written by P. A. Lakshminarayanan and published by Springer Nature. This book was released on with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulent Combustion by : Norbert Peters
Download or read book Turbulent Combustion written by Norbert Peters and published by Cambridge University Press. This book was released on 2000-08-15 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combustion of fossil fuels remains a key technology for the foreseeable future. It is therefore important that we understand the mechanisms of combustion and, in particular, the role of turbulence within this process. Combustion always takes place within a turbulent flow field for two reasons: turbulence increases the mixing process and enhances combustion, but at the same time combustion releases heat which generates flow instability through buoyancy, thus enhancing the transition to turbulence. The four chapters of this book present a thorough introduction to the field of turbulent combustion. After an overview of modeling approaches, the three remaining chapters consider the three distinct cases of premixed, non-premixed, and partially premixed combustion, respectively. This book will be of value to researchers and students of engineering and applied mathematics by demonstrating the current theories of turbulent combustion within a unified presentation of the field.
Download or read book Unsteady Combustion written by F. Culick and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains selected papers prepared for the NATO Advanced Study Institute on "Unsteady Combustion", which was held in Praia da Granja, Portugal, 6-17 September 1993. Approximately 100 delegates from 14 countries attended. The Institute was the most recent in a series beginning with "Instrumentation for Combustion and Flow in Engines", held in Vimeiro, Portugal 1987 and followed by "Combusting Flow Diagnostics" conducted in Montechoro, Portugal in 1990. Together, these three Institutes have covered a wide range of experimental and theoretical topics arising in the research and development of combustion systems with particular emphasis on gas-turbine combustors and internal combustion engines. The emphasis has evolved roughly from instrumentation and experimental techniques to the mixture of experiment, theory and computational work covered in the present volume. As the title of this book implies, the chief aim of this Institute was to provide a broad sampling of problems arising with time-dependent behaviour in combustors. In fact, of course, that intention encompasses practically all possibilities, for "steady" combustion hardly exists if one looks sufficiently closely at the processes in a combustion chamber. The point really is that, apart from the excellent paper by Bahr (Chapter 10) discussing the technology of combustors for aircraft gas turbines, little attention is directed to matters of steady performance. The volume is divided into three parts devoted to the subjects of combustion-induced oscillations; combustion in internal combustion engines; and experimental techniques and modelling.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1983 with total page 876 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modelling Spark Ignition Combustion by : P. A. Lakshminarayanan
Download or read book Modelling Spark Ignition Combustion written by P. A. Lakshminarayanan and published by Springer. This book was released on 2024-05-02 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a comprehensive overview of combustion models used in different types of spark ignition engines. In the first generation of spark ignition (SI) engines, the turbulence is created by the shear flow passing through the intake valves, and significantly decays during the intake and compression strokes. The residual turbulence enhances the laminar flame velocity, which is characteristic of the fuel and increases the relative effectiveness of the engine. In this simple two-zone model, the turbulence is estimated empirically; the spherical flame propagation model considers ignition delay, thermodynamics, heat transfer and chemical equilibrium, to obtain the performance and emissions of an SI engine. The model is used extensively by designers and research engineers to handle the fuel-air mixture prepared in the inlet and different geometries of open combustion chambers. The empiricism of the combustion model was progressively dismantled over the years. New 3D models for ignition considering the flow near a spark plug and flame propagation in the bulk gases were developed by incorporating solutions to Reynolds-averaged Navier-Stokes (RANS) equations for the turbulent flow with chemical reactions in the intense computational fluid dynamics. The models became far less empirical and enabled treating new generation direct-injection spark-ignition (DISI) gasoline and gas engines. The more complex layout of DISI engines with passive or active prechamber is successfully handled by them. This book presents details of models of SI engine combustion progressively increasing in complexity, making them accessible to designers, researchers, and even mechanical engineers who are curious to explore the field. This book is a valuable resource for anyone interested in spark ignition combustion.
Book Synopsis Fundamentals of Premixed Turbulent Combustion by : Andrei Lipatnikov
Download or read book Fundamentals of Premixed Turbulent Combustion written by Andrei Lipatnikov and published by CRC Press. This book was released on 2012-10-24 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lean burning of premixed gases is considered to be a promising combustion technology for future clean and highly efficient gas turbine combustors. Yet researchers face several challenges in dealing with premixed turbulent combustion, from its nonlinear multiscale nature and the impact of local phenomena to the multitude of competing models. Filling
