Effect of pre-chamber volume on combustion characteristics of an SI aircraft piston engine fueled with RP3

Abstract Four-stroke spark ignition (SI) aircraft piston engine is a good choice for small aircraft, however it has limited applications based on its high operational cost and security risk on account of its fuel use. In this context, switching from gasoline to aviation kerosene is an alternative option for such engines. Using a pre-chamber that facilitates fuel conversion is an alternative option to increase engine efficiency. In this study, a commercial four-stroke aircraft SI engine was modified to make sure the fuel is able to be replaced with aviation kerosene and then analyzed the combustion characteristics with different pre-chamber volumes. The relationship between pre-chamber volume and in-cylinder combustion under different working conditions were assessed. In addition, we also evaluated the effect of a pre-chamber on knocking suppression under different engine speeds. The experimental results indicate that the effect of pre-chamber on cylinder combustion depends on both engine load and pre-chamber volume. A 2.5-ml pre-chamber improves in-cylinder combustion significantly under heavy load conditions. The indicated mean effective pressure limited by knocking is increased by 38.3–43.9% at different engine speeds. The engine outputs enough power to meet the typical cruise working condition just adding a passive pre-chamber. The pre-chamber reduces the engine performance under low load conditions due to its poor ventilation and more heat dissipation.