Experimental study of aviation kerosene engine with PJI system

The spark-ignition (SI) piston engine has become the main power source for unmanned aerial vehicles owing to its small size and large power/weight ratio. While gasoline is the commonly used fuel in SI engines, it affords poor safety and stability. Aviation kerosene is highly suitable as an alternative to gasoline; however, its high kinematic viscosity and low saturated vapour pressure afford poor evaporation and atomisation in SI engine. Moreover, aviation kerosene has a low octane number, and easy to cause knock, particularly in four-stroke engines. Those issue limits the wide use of kerosene in SI engines. In this study, the pre-chamber jet ignition (PJI) technology is used to suppress the knock of kerosene engine. The combustion characteristics of gasoline-SI, kerosene-SI and kerosene-PJI were compared and analysed. The variation law of indicated mean effective pressure (IMEP) at different speeds is obtained. It is found that PJI system can accelerate the flame propagation speed and shorten the combustion duration, and IMEP can be increased by 10%–27%. The experimental results show that PJI can optimise kerosene combustion to a certain extent and broaden its knock limit in SI engine. It is one of the effective ways to suppress knock in kerosene engine.