二冲程重油直喷发动机混合气形成研究

In view of the problems of difficulty in evaporation of aviation kerosene and high fuel consumption of two⁃stroke engines, a three⁃dimensional simulation model of a two⁃stroke direct injection engine fueled with aviation kerosene was established, and the accuracy of the model was verified through experiments.On this basis, scavenging and mixture formation process was studied.The research results showed that postponing fuel injection reduced the short⁃circuit time of fuel, and at the same time avoided the free exhaust phase with large exhaust mass flow, which can improve the fuel capture rate.Utilizing the high temperature of exhaust gas can speed up the evaporation process of kerosene.Injection too late could lead to incomplete evaporation and uneven mixture of fuel and fresh charge.For this engine, 80° before bottom dead center indicated an appropriate injection timing enabling fuel evaporation and uniform mixing while increasing the fuel capture rate.At this time, the engine had higher indicated power and lower indicated thermal efficiency, which were 84.0 kW and 360.3 g/kWh, respectively.The research results can provide theoretical support for the optimization of the fuel injection parameters of the two⁃stroke direct injection engine.