微重力条件下初始液氢温度对低温推进剂贮箱气枕压力的影响

自生增压液氢推进剂贮箱在轨滑行阶段将长期(数百秒)处于微重力环境下,其贮箱压力受多种因素影响.液氢低温推进剂接近饱和温度时,因传热等影响而极易产生相变,从而影响贮箱压力.通过建立贮箱三维CFD模型,研究了不同初始液氢推进剂温度对于贮箱压力和温度变化等的影响.计算结果表明,气液界面附近推进剂温度与当前气体压力下饱和温度之差(过冷度)越大,压力下降速率越大.随着气体压力下降,气枕温度降低,压力下降速率也逐渐减小,压力变化曲线趋于平缓.在初始液体推进剂温度低于平衡温度的情况下,初始液体推进剂温度越高,平衡压力越高.

Effect of Initial Liquid Hydrogen Temperature on the Pressure Changes in the Cryogenic Propellant Tank

The cryogenic propellant tank will be in microgravity environment for more than several hundred seconds during the MECO (Main Engine Cut-off) phase. Liquid hydrogen propellant works near its saturation temperature, which can easily cause phase transition due to heat transfer and other effects, thus affecting the pressure change of the tank. The effects of different initial cryogenic propellant temperatures on tank pressure and temperature are studied by establishing a three-dimensional CFD model. The results show that the larger the difference between the temperature of the propellant near the gas-liquid interface and the saturation temperature under the current gas pressure is, the greater the pressure drop rate is. As the gas pressure drops, the overall temperature of the ullage gas decreases, the pressure drop rate also gradually decreases, and the pressure change curve tends to flatten out. When the initial liquid propellant temperature is lower than the equilibrium temperature, the higher the initial liquid propellant temperature is, the higher the equilibrium pressure is.