| Abstract:In order to investigate how the coupling effect of the complex turbulent field and ignition position in the unique combustion chamber of a X-type rotary engine affects the mixture combustion process, a three-dimensional CFD model of the X-type rotary engine was established and validated with test results. The in-cylinder combustion pro-cess of the X-type rotary engine under different ignition positions was numerically investigated, revealing the in-fluence of ignition position on flame propagation, combustion characteristics and pollutant formation. Results showed that at the late stage of compression stroke, the complex turbulence field including vortex and unidirec-tional flow is formed in the combustion chamber of the X-type rotary engine, which significantly affects the flame propagation process by the coupling effect with the ignition position. In order to obtain the high flame propagation speed, the ignition position is not suitable to be located at the vortex region. When the ignition position is located in the middle of the recess, the flame propagation can be accelerated by taking full advantage of the surrounding space and the higher velocity field formed at the transition between the vortex mass and the unidirectional flow field, thus advancing the center of gravity of combustion and increasing the rate of heat release, and the peak pres-sure has been increased by 25%, with an indicated thermal efficiency of more than 30%; it also has a low emission of HC and CO. However, due to the larger peak in-cylinder temperature, it leads to an increase in NO emissions. |