A Preliminary Research on Turbulent Flame Propagation Combustion Modeling Using a Direct Chemical Kinetics Model 2013-24-0023
The present work focused on modeling turbulent flame propagation combustion process using a direct chemical kinetics model. Firstly, the theory of turbulent flame propagation combustion modeling directly using chemical kinetics is given in detail. Secondly, two important techniques in this approach are described. One technique is the selection of chemical kinetics mechanism, and the other one is the selection of AMR (adaptive mesh refinement) level. A reduced chemical kinetics mechanism with minor modification by the authors of this paper which is suitable for simulating gasoline engine under warm up operating conditions was selected in this work. This mechanism was validated over some operating conditions close to some engine cases. The effect of AMR level on combustion simulation is given, and an optimum AMR level of both velocity and temperature is recommended. Thirdly, the primary models used in MESIM-Converge code, which combines Ford in house code MESIM and a commercial code Converge, are described, and a unified version of simulation setup is presented. With this unified version of models and simulation setup, validation of engine combustion modeling has been completed. The validated engine conditions range from high load, medium load to low load, from high speed, medium speed to low speed. Also different engine types were validated.
All the validated cases are engine warm up operating conditions. The simulated in-cylinder pressures, burn rates and emissions including CO, NOx and UHC (unburned hydrocarbon) are compared with experimental data and good agreements are found. Engine cold start operating conditions and high EGR (exhaust gas recirculation) cases will be the next step of research.