膨胀循环氢氧发动机低箱压起动特性研究

Research on low-pressure start-up characteristics of expander cycle LOX/LH2 engine

为满足长时间在轨低温上面级对发动机低入口压力起动的需求,对膨胀循环氢氧发动机低箱压起动特性进行了仿真和试验研究,建立了较为准确的起动特性仿真模型,完成了地面环境和高空模拟环境氢入口低箱压起动试验。结果表明,氢入口压力越低,发动机起动加速性越慢,两者呈类似双曲线关系;降低喷管出口背压有利于发动机起动,氢入口压力越低,背压对起动加速性的影响越大。

In order to meet the demand for low inlet pressure start-up of the cryogenic upper stage,simulation and experimental research on the low tank pressure start-up characteristics of the expander cycle LOX/LH2 engine were conducted.An relatively accurate simulation model for start-up process was established,and the start-up tests of low hydrogen inlet pressure in both ground and simulated high altitude environment were completed.The results show that the start-up acceleration slows down with the decrease of hydrogen inlet pressure,which is similar to hyperbolic relation.Reducing the back pressure at the nozzle outlet is beneficial to start-up,the lower the hydrogen inlet pressure,the greater the effect of back pressure on the starting acceleration.