Numerical investigation on combustion system optimization for direct injection of aviation kerosene in a two-stroke SI engine for unmanned aerial vehicle

In recent years, the transition from gasoline to heavy fuel has received more and more attention in the appli-cation of unmanned aerial vehicles (UAVs). This study aims to convert a two-stroke port fuel injection (PFI) gasoline engine as the prototype engine to a direct injection (DI) aviation kerosene engine by numerical simu-lations. The direct-injection combustion system was designed, and then the effects of fuel injection timing and ignition strategy on combustion and knock of a two-stroke direct injection spark-ignition (DISI) engine with aviation kerosene as fuel were evaluated. The results show that the direct-injection combustion system can in-crease the airflow velocity, thereby accelerating fuel diffusion and flame propagation. The knock intensity (KI) and indicated mean effective pressure (IMEP) all decrease with the retardation of the injection timing and spark timing. Injection timing has a greater impact on IMEP than spark timing. For different injection timings, spark timing has a more obvious impact on KI when injection timing is advanced. The coordinated control strategy of advancing injection timing and retarding spark timing can effectively suppress the tendency of knock and broaden its load range, which can make the power recovery rate reach 88.57% compared to the baseline engine.