活塞式航空煤油发动机性能优化及爆震抑制研究

Study on Performance Optimization and Knock Suppression of Piston Kerosene Engine

基于一台压缩比可变的单缸热力学发动机,使用自主开发的空气辅助喷射系统,在全负荷条件下开展了活塞式航空煤油发动机性能优化及爆震抑制的试验研究。探究了采用双点火、降低压缩比及使用CO_(2)辅助喷射对航空煤油发动机的性能及爆震抑制的影响研究。结果表明,采用双点火可以有效提高航空煤油火焰传播速率,提高燃烧相位,降低循环波动,并且有抑制爆震的作用;通过降低压缩比有效实现了爆震抑制,解决在较高压缩比下航空煤油发动机只能运行在低负荷区间的难题,压缩比降至6,发动机实现全负荷运行,动力性、经济性较好,且不易发生爆震;采用CO_(2)辅助航空煤油喷射时,随着CO_(2)脉宽的增加,同一点火提前角下,发动机的动力性经济性下降,但由于CO_(2)的抑制爆震的作用,最大制动转矩点火时刻最大可提前至上止点前14°,使得燃烧相位提前,发动机燃烧效率提高。

Based on a single-cylinder thermodynamic engine with variable compression ratio,a self-developed air-assisted injection system was used to carry out an experimental research on the performance optimization and knock suppression of a piston aviation kerosene engine under full load conditions.The effects of double ignition,reduction of compression ratio and CO_(2)-assisted injection on the performance and knock suppression of aviation kerosene engines were investigated.The results show that the use of double ignition can effectively increase the flame propagation rate of aviation kerosene,improve the combustion phase,reduce cyclic fluctuation,and have the effect of suppressing knocking.By reducing the compression ratio,knocking suppression is effectively achieved and it can solve the problem that the aviation kerosene engine can only run in a small load range at high compression ratio.When the compression ratio is reduced to 6,the engine can run on full load,with good power performance and economy,and is not prone to knock.When CO_(2)-assisted aviation kerosene injection is used,with the increase of CO_(2) pulse width,the engine performance and economy will decrease at the same ignition timing.However,due to the effect of CO_(2) in suppressing knocking,the maximum braking torque ignition timing can be advanced to 14°before top dead center,which advances the combustion phase and improves engine combustion efficiency.