Abstract: On the direct-connect high altitude experiment system,the ramjet models were successfully ignited and combusted stably at the pressure between 40 kPa and 60 kPa.According to these tests,the influence parameters on combustion efficiency were studied under variable conditions,including the combustor configuration,the inflow condition at the entrance of the combustor and the equivalent ratio.Results show that the combustion efficiency at the low pressure is lower than that at the normal and high pressure,but the variation trend is almost the same.The increase of the length of the combustor,the total temperature,the total pressure,and the equivalent ratio,the decrease of the flight altitude,and the enhancement of atomization and mixing can increase the combustion efficiency.However,the decrease of the ratio of length-to-depth can improve the combustion efficiency.

Key words: Ramjet engine;Combustion chamber;Combustion efficiency;Low pressure;Cavity+

摘要： 在亚燃冲压发动机直连式高空试验系统上,实现了模型冲压发动机在40～60 kPa条件下的点火和稳定燃烧,研究了燃烧室构型、燃烧室入口来流条件以及燃料当量比对燃烧效率的影响。试验结果表明:低压条件下的燃烧效率比常压和高压条件下的燃烧效率都要低;但低压条件下燃烧效率随燃烧室构型、模拟来流条件和燃料当量比的变化规律与常压和高压下的情况基本一致,增加燃烧室长度、提高来流总压和总温、增大燃料当量比,降低飞行高度,以及增强煤油的雾化和混合,都有利于提高燃烧效率;与常压和高压下的情况不同的是减小凹腔长深比能进一步提高燃烧效率。

关键词: 冲压喷气发动机;燃烧室;燃烧效率;低压;凹腔+