增强大推力火箭发动机燃烧稳定性裕度的方法

Method to enhance combustion stability margin of high thrust rocket engine

针对重型运载大推力液体火箭发动机自发激励高频燃烧不稳定性的技术风险,总结和分析了影响大推力液氧煤油火箭发动机燃烧稳定性裕度的因素,主要包括燃烧室声学固有频率、燃烧室结构和喷嘴几何结构。结果表明:发动机喷注器附近的推进剂燃烧区、燃烧室收敛段对燃烧室声学固有频率有较大影响;燃烧室长度为燃烧室直径的0.205倍或0.205的奇数倍时有相对最好的燃烧稳定性;气液同轴式喷嘴长度为燃烧室一阶切向振荡频率的0.5倍时,能传递最大的振荡能量。最后,提出了一种增强燃烧稳定性裕度、避免出现切向振型高频燃烧不稳定性的燃烧室设计方法。

To overcome the high-frequency combustion instability of spontaneous excitation of high thrust liquid rocket engines(LRE),the main factors(including acoustic frequency of combustor,structural parameters of combustor and geometric structure of coaxial injector) which affect the combustion stability margin of high thrust LOX-kerosene rocket engine are summarized and analyzed.The results show that the propellant combustion area and combustor convergence section close to the injector have great effects on the acoustic inherent frequency of the combustion chamber,the relatively perfect combustion stability can be got when the combustion chamber length is 0.205 times longer than the combustion chamber diameter or is odd number of 0.205,and the maximum oscillation energy can be obtained when the length of the gas-liquid coaxial injector is 0.5 times the first-order tangential oscillation frequency.A combustor design method to enhance combustion stability margin and avoid high-frequency combustion instability is proposed to provide a reference for the engineering design of LRE.