Effect of injection strategy on a novel hydrogen direct injection stratified combustion rotary engine

Direct-injection hydrogen rotary engines suffer from the problem of the injection flow rate due to the limitation of the injector. Supplying hydrogen in the pre-chamber(PC) can reduce the injection pressure and increase the hydrogen flow rate. Therefore, a novel hydrogen direct injection stratified combustion rotary engine(HDISC-RE) based on the concept of PC is proposed in this study. For the proposed HDISC-RE, all of the hydrogen is supplied in the PC and is ignited during injection to achieve stratified combustion. HDISC under different injection strategies was investigated in this study. The results show that the reliability of ignition is enhanced as the injection duration(ID) is shortened. As the injection ratio increases (referring to the ratio of hydrogen mass injected before and after ignition), the hydrogen gradually moves towards the minor semi-axis, stabilizing the flame in the rotor pocket. The distribution of hydrogen becomes more ideal with the shortening of ID and the increase of injection ratio. Thus, HDISC can achieve the highest ITE of 29.8 % and the lowest unburned hydrogen of 8.11 %. The result shows that the combustion mode of HDISC is more promising, and the variation of injection strategy can effectively control the hydrogen combustion process.