Design and research of high-tumble scavenging system for spark ignition two-stroke aviation heavy fuel engine

The spark ignition two-stroke heavy fuel piston engine has significant application prospects in the unmanned aerial vehicle field due to its high power-to-weight ratio, low maintenance costs, and enhanced fuel safety. However, challenges such as the difficulty of heavy fuel evaporation, improper mixing, and two-stroke scavenging short circuits lead to serious fuel escape problems, which negatively affect the engine's economy and power performance. To address these issues, it is essential to ensure that fuel evaporation and mixing in the cylinder occur within a very short time. In this study, a high-tumble scavenging system for a spark ignition two-stroke aviation heavy fuel engine is proposed. The impact of key structural parameters of the cross-flow port on cylinder flow and mixing is analyzed. The results demonstrate that the total intake volume of the high-tumble scavenging system is 8.5 % greater than that of the original scavenging system, with a 4.1 % improvement in scavenging efficiency, a 24 % reduction in residual exhaust gas mass, and a 14.3 % increase in in-cylinder tumble intensity, leading to improved fuel evaporation and mixing.