液氧煤油补燃发动机起动过程氧预压泵加速起旋方案研究

Investigation on Schemes for Accelerating Oxidizer Boost Pump during Start-up of LOX/kerosene Staged Combustion Rocket Engine

关键词:  液体火箭发动机  补燃发动机  预压泵  主泵  起动  汽蚀

Key words:  Liquid rocket engine  Staged combustion engine  Boost pump  Main pump  Start  Cavitation

摘要:

为降低液氧煤油补燃发动机起动所需入口压力,需解决起动过程氧预压泵起旋迟缓产生附加阻力导致主泵入口压力过低而发生断裂汽蚀的问题。开展了两种预压泵加速起旋方案研究,分别为已工程应用的液氧涡轮方案和本文提出的氦起动涡轮方案。对比介绍了两种方案对发动机气液系统和预压泵结构的影响。建立了预压泵加速起旋相关的数学模型,针对加速起旋机理、效果和影响因素等进行了仿真分析。结果表明：液氧涡轮方案,预压泵结构变化较小,为提升加速起旋效果,涡轮供应路应尽量增大通径、缩短长度,降低动态流阻和静态流阻,涡轮喷嘴流通面积则需根据其对涡轮流量和压降的综合影响来选择。氦起动涡轮方案,预压泵结构和流路变化较大,起动涡轮速比和效率是降低氦气用量的限制性因素。

Abstract:

In order to reduce inlet pressure for start of LOX/kerosene staged combustion rocket engine, the spin-up delay problem of oxidizer boost pump needs to be solved to eliminate its flow resistance influence on main pump cavitation. Two schemes for accelerating boost pump were studied, which are the liquid oxygen turbine scheme that has been applied in engineering and the helium starting turbine scheme proposed in this paper. Effects of the two schemes on engine gas-liquid system and boost pump structure were compared. Mathematical model was established to examine mechanism, effect and influencing factors of boost pump accelerating. Results show that for the liquid oxygen turbine scheme, the structure of boost turbopump has little change. To improve acceleration performance, the turbine supply pipeline should increase the diameter and shorten the length to reduce dynamic and static flow resistance. Meanwhile, the turbine nozzle flow area should be selected according to its comprehensive impact on the turbine flow and pressure drop. In the scheme of helium starting turbine, boost turbopump varies greatly in both structure and flow path, and reduction of helium consumption is limited by relatively low velocity ratio and efficiency of the starting turbine.