液体姿控发动机76km高空模拟试验系统性能仿真

为研究液体姿控发动机76 km高空模拟试验系统的工作性能,建立了考虑燃气相变的试验系统集中参数动态仿真模型。模型由真空抽气系统、冷凝管束和液氮外流程3个子模型组成。根据燃气、霜、液氮之间的传热和传质过程将各子模型耦合在一起。以四氧化二氮/甲基肼双组元姿控发动机为实例,计算了稳态和脉冲点火试验时系统的工作参数,分析了关键设计参数对其工作性能的影响。结果表明:试验系统能够为最大流量6.4 g/s(推力约16.5 N)的发动机提供脉冲和6×10~4s长程稳态试验环境;在长程稳态试验中,冷凝管束霜层将依次饱和,失去对二氧化碳和水蒸汽的抽吸能力,导致真空舱压力逐渐升高;在脉冲点火试验中,真空舱压力将随发动机工作而脉冲波动,15 ms开关脉冲时的压力波动幅度约70%。研究结果为液体姿控发动机高空模拟试验系统的设计与改进提供了参考。

Performance simulation of a 76 km simulated high-altitude test system for liquid attitude-control engines

To study the performance of a 76 km high-altitude test system for attitude-control liquid rocket engines,a transient test system simulation model with lumped parameters was built,which considers the phase change of the exhaust.The systetn model consists of a vacuum pumping sub-model,a liquid nitrogen flow submodel and a condensing pipe sub-model.The sub-models were coupled through the heat and mass transfer process between the gas,frost and liquid nitrogen.The system working parameters during the steady and the pulsed tests of a bipropellant nitrogen-tetroxide/mono-methylhydrazine attitude-control engine were calculated,and effects of the important system design parameters on working performance were explored.The results show that the current test system could provide environment for the engine pulse tests and 6 × 104 s steady tests with a maximum propellant flow rate of 6.4 g/s (trust is about 16.5 N);in long-term test,the frost on the surface of condensing pipes will get saturated and lose the ability to absorb carbon dioxide and water vapor,leading to the gradually increase of the vacuum tank pressure;during the engine pulsed test,the vacuum tank pressure will fluctuate with the pulses,up to about 70％ in the 15 ms pulse case.The conclusion of the study could be a guide in the design and upgrade of the high-altitude test system for the liquid attitude-control engines.