无人机用点燃式二冲程柴油机燃烧特性研究

To address the problems of poor combustion and knock caused by the difficulty of diesel fuel atomization and evaporation， the combustion characteristics of a two-stroke spark-ignition diesel engine has been investigated by adopting the air-assisted direct injection scheme. A three-dimensional simulation model of the two-stroke spark-ignition diesel engine is established， and the mixture characteristics and combustion characteristics are simulated and verified through bench tests. The results show that under hot engine conditions， 58% of the fuel evaporates at the ignition time， the average equivalent ratio of the cylinder increases from 0.2 to 0.8 compared with cold starting conditions， the quality of the mixture is high， and the in-cylinder combustion is excellent. Through the comparison test of engine performance with gasoline and diesel， it is found that under high speed and large load conditions， the combustion characteristic curves of the two fuels are extremely close， and the average distribution of indicated mean effective pressure （IMEP） for diesel combustion is only 1.2% lower than that for gasoline. In general， the combustion performance of diesel used in the two-stroke spark-ignition engine is similar to that of gasoline， and when using diesel， the maximum oscillation amplitude of the cylinder pressure is only 0.02 MPa， which is much lower than the knocking threshold， so there will be no knocking phenomenon occurs.