Numerical Simulation Of Oxygen-Enriched Combustion In Gasoline Engine

Compared with conventional PFI(Port Fuel Injection) gasoline engine, GDI(Gasoline Direct Injection) engine has more superior performance since it accessed to markets at the end of last century. The oxygen-enriched combustion technology can improve the combustion performance and the power performance of the engine and increase fuel efficiency. The gasoline engine working process was understood by researchers with the help of numerical simulation and the rule was controlled fundamentally. Then the improvement strategy of oxygen-enriched combustion in GDI engine provided significant information about the experiment.This thesis studied the numerical simulation of fuel spray with RANS and LES in KIVA3 under Fortran. Then the sensitivity of the spray to grid and the results of the two methods were analyzed. The air intake, compression stroke flow field characteristics, fuel injection, fuel-air mixture formation and combustion process were analyzed.The results prove that there are no obvious differences in revealing the combustion characteristic of the engine between RANS and LES, but LES has advantage of flow field and distribution of fuel equivalence ratio. LES is more independent to computing grid. This thesis shows that the oxygen-enriched intake air has significant effect to increase engine power and combustion efficiency. The emission performance shows better when the oxygen-enriched value is in a lower level.The numerical simulation in this thesis provides significant information about the working process of reciprocating internal combustion engine, which is great helpful to further research.