Author: Himanshu RaiPublisher:
ISBN:
Category :
Languages : en
Pages : 214
Book Description
Simulation of Spray Combustion in a Direct-injected, Spark-ignited, Two-stroke Engine
Author: Himanshu RaiAutomotive Spark-Ignited Direct-Injection Gasoline Engines
Author: F. ZhaoPublisher: Elsevier
ISBN: 008055279X
Category : Technology & Engineering
Languages : en
Pages : 129
Book Description
The process of fuel injection, spray atomization and vaporization, charge cooling, mixture preparation and the control of in-cylinder air motion are all being actively researched and this work is reviewed in detail and analyzed. The new technologies such as high-pressure, common-rail, gasoline injection systems and swirl-atomizing gasoline fuel injections are discussed in detail, as these technologies, along with computer control capabilities, have enabled the current new examination of an old objective; the direct-injection, stratified-charge (DISC), gasoline engine. The prior work on DISC engines that is relevant to current GDI engine development is also reviewed and discussed. The fuel economy and emission data for actual engine configurations have been obtained and assembled for all of the available GDI literature, and are reviewed and discussed in detail. The types of GDI engines are arranged in four classifications of decreasing complexity, and the advantages and disadvantages of each class are noted and explained. Emphasis is placed upon consensus trends and conclusions that are evident when taken as a whole; thus the GDI researcher is informed regarding the degree to which engine volumetric efficiency and compression ratio can be increased under optimized conditions, and as to the extent to which unburned hydrocarbon (UBHC), NOx and particulate emissions can be minimized for specific combustion strategies. The critical area of GDI fuel injector deposits and the associated effect on spray geometry and engine performance degradation are reviewed, and important system guidelines for minimizing deposition rates and deposit effects are presented. The capabilities and limitations of emission control techniques and after treatment hardware are reviewed in depth, and a compilation and discussion of areas of consensus on attaining European, Japanese and North American emission standards presented. All known research, prototype and production GDI engines worldwide are reviewed as to performance, emissions and fuel economy advantages, and for areas requiring further development. The engine schematics, control diagrams and specifications are compiled, and the emission control strategies are illustrated and discussed. The influence of lean-NOx catalysts on the development of late-injection, stratified-charge GDI engines is reviewed, and the relative merits of lean-burn, homogeneous, direct-injection engines as an option requiring less control complexity are analyzed.
A Simulation of Combustion of JP-8 and Gasoline in a Direct-injected, Spark-ignited Two-stroke Engine
Author: Ge ShenFundamentals of Fuel Injection and Emission in Two-stroke Engines
Author: Wadysaw MitianiecPublisher: Nova Science Publishers
ISBN: 9781536124729
Category : Two-stroke cycle engines
Languages : en
Pages : 0
Book Description
The main goal of the book is the presentation of the last theoretical and experimental works concerning fuel injection systems, mainly in small power two-stroke engines as well as in marine engines. This book includes thirteen chapters devoted to the processes of fuel injection and the combustion that takes place in a stratified charge within the cylinders of two-stroke engines. In the first two chapters, the division into different injection systems in two-stroke engines and each injection system is briefly described. Various theoretical and practical solutions of fueling system designs are described. In Chapter Three, mathematical models, the spatial movement of gas in the cylinder and the combustion chamber are introduced, taking into account the turbulence of the charge. Chapter Four relates to the behavior of fuel injected into the gaseous medium, including evaporation processes, disintegration and processes occurring while the fuel drops connect with the wall. The next section describes the zero-dimensional model of fuel injection in two-stroke engines along with examples of numerical calculations. The sixth chapter is devoted to CFD multi-dimensional models of movement and evaporation of the fuel in a closed gaseous medium, occurring also in other engine types. Chapter Seven describes a two-zone model of the combustion process and the effect of the geometry of the combustion chamber on the flame propagation with a simplified verification model of combustion. Chapter Eight compares the propagation phase of gas and liquid fuels concerning direct fuel injection as well as the direct fuel injection from the cylinder head and the thermodynamic parameters of the charge. The formation of the components during the combustion process in the direct fuel injection two-stroke engine was obtained by numerical calculations and results are discussed in Chapter Nine. Chapter Ten describes the parameters of the two-stroke engine with a direct fuel injection carried out at the Cracow University of Technology. Additionally, the chapter presents CFD simulations of fuel propagation and combustion processes, taking into account the formation of toxic components and exhaust gas emission. The processes of two direct rich mixture injection systems FAST and RMIS developed in CUT are presented in Chapter Eleven. Miscellaneous problems of direct fuel injection, such as characteristics of fuel injectors, problems of direct gaseous fuel injection, and the application of fuelling systems in outboard engines and snowmobile vehicles are presented in Chapter Twelve. A comparison of working parameters in two- and four stroke engines is also mapped out. The last chapters contain the final conclusions and remarks concerning fuel injection and emission of exhaust gases in small two-stroke engines. This book is a comprehensive monograph on fuel injection. The author presents a series of theoretical and design information from his own experience and on the basis of the works of other authors. The main text intends to direct fuel injection with respect to gas motion in the combustion chamber and influence the injection parameters for exhaust emission. The book presents its own theoretical work and experimental tests concerning a two-stroke gasoline engine with electrically controlled direct fuel injection. The book describes the processes of a general nature also occurring in other types of engines and presents a comparison of different injection systems on working parameters and gas emission. The book contains 294 images, 290 equations and 16 tables obtained from the CFD simulation and experimental works.
Spray and Combustion Visualization in a Production Direct Injection Spark Ignition Two-stroke Engine
Author: H. Kieran McCabeThe Effects of Spray Characteristics on Combustion and Emission Performance of a Two-stroke Direct-injection Engine
Author: Mark CasarellaLarge-Eddy Simulations of Motored Flow and Combustion in a Stratified-Charge Direct-Injection Spark-Ignition Engine
Author: Samuel KazmouzPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Stratified-charge, spray-guided, spark-ignition, direct-injection operation offers efficiency improvements to conventional engines used in light-duty vehicles. However, cycle-to-cycle variability (CCV) impedes extracting the full efficiency potential of such advanced engine operation modes. In this dissertation, multi-cycle motored and fired large-eddy simulation (LES) results of an optically-accessible single-cylinder four-valve direct-injection spark- ignition engine, called G4VDI, are presented and compared to experimental results. The main objective is to investigate the root causes of CCV in stratified-charge engines. For motored operation, four sets of 60 consecutive LES cycles, with different operating conditions, are compared with experiments. LES is able to capture the wave dynamics of the ports and the in-cylinder pressure with a difference of 0.12%-2.5%, compared to experimental results. The LES velocity fields are compared with particle-image velocimetry measurements at six cutting planes. Based on the local and volume-averaged structure and magnitude indexes, it is found that LES is able to reproduce key flow events and capture large-scale in-cylinder flow structures, especially in high tumble/swirl conditions. Using proper orthogonal decomposition, LES shows that high tumble/swirl conditions produce low CCV flow fields. CCV of in-cylinder pressure ranged between 0.13% and 0.23%. For fired operation, and using the thickened flame model (TFM), 20 consecutive LES cycles of a homogeneous-charge engine operation mode are presented followed by spray-characterization in four different ambient conditions. These results lay the foundation for two stratified-charge engine operation modes, in which 20 and 35 consecutive LES cycles are compared with experiments, respectively. TFM-LES is extended for partially premixed flames and is able to reproduce experimental in-cylinder pressure (0.5%-10%), cyclic variability (20.5%-22.7%) in global and local quantities, local fuel vapor distributions, and heat release curves for homogeneous and stratified burn. Tuning TFM to reduce the burn rate increases the tendency to produce misfires, as well as the levels of CCV. Correlation analysis done on the stratified-charge LES results suggests that the influence of the early burn on the subsequent flame development is more subtle for stratified combustion compared to homogeneous combustion, that is the local conditions at the spark plug when the flame starts propagating are more influential than the conditions at spark timing, and that the injection event creates velocity conditions which might be favorable or unfavorable for the combustion event. The main contributions of this dissertation are extending TFM to highly stratified spray combustion, showing that LES can reproduce experimentally measured flow and combustion behavior in a realistic engine, including CCV, and analyzing LES to provide new insight into CCV and misfires of stratified-charge engines.
Numerical Simulation of a Direct Injection Spark Ignition Engine Using Ethanol as Fuel
Author: Shalabh SrivastavaPublisher:
ISBN:
Category : Alcohol as fuel
Languages : en
Pages : 276
Book Description
Multi-dimensional Modeling of Mixing and Combustion of Direct Injection Spark Ignition Engines
Author: Li FanLarge-eddy Spray Simulation Under Direct-injection Spark-ignition Engine-like Conditions
Author: Hongjiang LiPublisher:
ISBN:
Category :
Languages : en
Pages : 157
Book Description
The focus of this dissertation is on the development and improvement of spray models for large-eddy simulation (LES) of turbulent two-phase flows in direct-injection spark-ignition (DISI) engines. The work can be regarded as a continuation of the development of LES framework at the Engine Research Center (ERC). The LES two-phase governing equations are solved using the Lagrangian-Eulerian (LE) approach in a variation of the OpenFOAM-2.3.x code developed by the OpenFOAM Foundation. A mixed-type one-equation dynamic structure turbulence model is used as the basis for turbulence modeling. LES models are developed for DISI spray breakup, Sub-grid scale (SGS) turbulent dispersion, and SGS energy dissipation rate. The spray breakup model builds on top of the hybrid Kelvin-Helmholtz (KH)/Rayleigh-Taylor (RT) model by incorporating the bag/bag-stamen breakup regimes. A concept of RT breakup length is introduced to account for the plume-interactions and the effective nozzle diameter of DISI spray. The SGS models are developed in the context of LES and require the SGS kinetic energy, which is obtained by solving its transport equation in the turbulence model. The performance of the new models is evaluated against a wide range of DISI spray experiments covering both early and late injection engine-like conditions. Examination of spray characteristics is performed for both global and local quantities such as penetration length, Sauter mean diameter (SMD), droplet velocity, liquid-phase concentrations, and spray envelop. The discussion focuses primarily on the DISI spray breakup, followed by \textit{a posteriori} test results of the SGS models. An uncertainty quantification (UQ) study is also performed to analyze the impact of spray boundary conditions and breakup model parameters on LES of DISI sprays. LES results show that the addition of models for bag/bag-stamen breakup regimes results in more accurate predictions of spray characteristics. The modified breakup length concept also predicts more realistic penetration curves across a range of ambient temperature and density conditions without tuning the model parameters. The improved SGS dispersion model correctly predicts local liquid-phase characteristics such as velocity and projected liquid volume fraction. A preliminary study of SGS dissipation rate modeling also shows that the SGS model is able to accurately predict the energy balance between the resolved and the SGS fields across various mesh resolutions.