Impacts of Injection Parameters on the Mixture Formation and Performance of Two-Stroke Spark-Ignition Direct-Injection Aviation Kerosene Engine

Two-stroke spark-ignition engines play a significant role in the field of power sources of small and medium unmanned aerial vehicles. There is a certain transition from burning gasoline to aviation kerosene (or heavy oil) and from carburetor or inlet injection system to direct-injection fuel system. However, the performance of two-stroke spark-ignition direct-injection engines fueled with aviation kerosene was not very ideal under heavy loads. Generally, the mixture formation is very important for engine combustion and performance, while injection parameters have great effects on mixture formation. Thus, various injection parameters of a two-stroke direct-injection kerosene engine were examined here. The results showed too early or too late injection timing (t_inj) would deteriorate the mixture formation, resulting in lower brake power and brake thermal efficiency. Here the most suitable t_inj was 150 deg CA BTDC. Too high or too low injection pressure (p_inj) caused fuel short circuit loss and poor mixture quality, so the optimum p_inj was 10 MPa. Too large injector installation angle (β) easily results in fuel spray impingement, and too small β causes fuel short circuit loss. Therefore, the best β was concluded to be 30 deg in this paper.