液氢贮箱停放过程中的力热分析

为了寻找到运载火箭长时间停放过程中液氢贮箱的最经济液位，用于制定合理的发射流程以及紧急处置方法，采用计算流体力学(CFD)技术，对某型运载火箭停放期间液氢贮箱的力、热情况进行了仿真计算和分析。计算选用了VOF(Volume-of-fluid)两相流模型以及Lee相变模型，为了提高Lee模型在不同压力情况下对相变过程的模拟精度，采用安托因方程修正了该模型。修正后的模型首先由试验数据校验了其精确性，随后开展的液氢贮箱停放过程仿真结果表明：贮箱的竖直方向与径向均存在温度分层的现象，液相内会形成大的漩涡，该漩涡会使得冷热流体不断进行热交换，并导致贮箱内部的液氢出现气化。贮箱停放期间蒸发率最大值超过2 m 3/h，发生在停放4 h左右；而贮箱液位充填至37 m 3以上或17 m 3以下时蒸发率较低，最小值接近1 m 3/h。

Thermodynamic Analysis in Liquid Hydrogen Tank while Parking

 In order to find the most economical liquid level of the hydrogen tank during a launch vehicle’s long-term parking, then to formulate a reasonable launch process and emergency disposal method, the computational fluid dynamics (CFD) technology is used to simulate and analyze the thermodynamics in the hydrogen tank of the launch vehicle while parking. The Volume-of-fluid (VOF) two-phase flow model and Lee phase transfer model are selected. In order to improve the Lee model’s simulation accuracy under different pressure conditions, the Antoine equation is employed to modify it. The modified model is firstly validated by the test data, and the subsequent simulation of the liquid hydrogen tank parking indicates that there is the temperature stratification phenomenon in both the vertical and radial directions in the tank, a large vortex is formed in the liquid phase, and it will cause the continuous thermal change between the cold fluid and hot fluid and lead to the liquid hydrogen’s evaporation in the inner part of the tank. The maximum evaporation rate exceeds 2 m 3/h and occurs at about 4 h after parking, the evaporation rate is relatively low when the tank is filled to more than 37 m 3 or less than 17 m 3, and the minimum value is close to 1 m 3/h.