不同供氢方式对X 型转子发动机 性能影响的仿真研究

To further improve the performance of X-type rotary engine(XRE), a new-type power unit, hydrogen-blended combustion is adopted to enhance the engine's combustion process. Firstly, by numerical simulation, a CFD model of the XMv3 engine with hydrogen-blending is established and verified. On this basis, two hydrogen supply modes, port injection(PI)at intake and direct injection(DI)at combustion chamber, are selected for comparison to investigate the influence of hydrogen-blending on in-cylinder flow, combustion and emission process, thus revealing effects of hydrogen contents and hydrogen supply modes on in-cylinder turbulent kinetic energy and vorticity, free radicals, in-cylinder temperature and pressure, as well as CO and NOx emissions. The results show that a main flow field accompanied by two vortexes is formed in the cylinder during the intake process and the gas is brought to both sides of the combustion chamber for mixing with air and fuel, thus facilitating the combustion. Upon hydrogen-blending, the combustion area expands to the slits on both sides of the combustion chamber so that the combustion performance is improved. It is also shown that hydrogen DI yields better performance than hydrogen PI. Meanwhile, the combustion strategy with a high equivalent ratio and the increased in-cylinder temperature due to hydrogen-blending lead to significant increase of CO and NOx emissions, respectively. Compared with combustion without hydrogen, the peak cylinder pressure is increased by 16.71% and 43.15% for PI and DI respectively with a hydrogen-blending energy fraction of 5%. This study provides a reference for the hydrogen supply design of XRE.