The in-cylinder flow and spray process of a GDI engine with a high compression ratio were simulated with AVL FIRE software and the influences of different combustion chamber structures on incylinder flow were researched. The effects of different designs on gas mixture formation were determined based on eight kinds of evaluation parameters such as tumble, swirl, turbulent kinetic energy, incylinder equivalence ratio fraction and et al. Finally, the design of combustion chamber was evaluated by introducing optimization rate and analyzing the calculated results. The evaluation results show that the optimization rate of design can reach 25.3% and 23.4% in high and low speed conditions respectively according to the optimized design and hence the incylinder mixture formation process improves.
