液体火箭贮箱增压排液过程温度场数值研究

针对某液体火箭贮箱增压排液过程,采用二维数值模拟方法对其温度场进行计算.选用低雷诺数k-ε模型分析流体与固壁间的耦合换热,考虑到气液之间发生热质转移现象,编写了控制相变的用户自定义程序(UDF)并植入Fluent软件.采用文献实验数据对相同工况下的计算结果进行验证,对比结果表明所建立的二维模型能够有效预测气枕温度、壁面温度沿轴向分布规律.数值模拟结果发现:气体扩散器入口方向、入口面积对气枕温度、壁面温度的轴向分布影响较弱,而对靠近增压口附近的温度场影响明显.当增压气体竖直向下进入气枕时,贮箱上封头附近气枕温度较低,有利于保障安全阀的可靠运行.当增压气体水平进入气枕时,扩散器直径变大,贮箱顶端高温区范围相应扩大. 

Numerical study on temperature distribution of tank pressurization process of liquid rocket during outflow

In view of the tank pressurization process of a certain liquid rocket during outflow, a two-dimensional numerical simulation method was adopted to study the law of temperature distribution in the ullage gas and in the tank wall. In this model, the low-Re k-ε model was selected to calculate the coupled heat transfer between fluid and tank wall, and a user-defined function (UDF) for phase transition was compiled and embedded into Fluent so as to research the effect of heat and mass transfer at the liquid surface. Certain experimental data in reference were selected to verify the results of this model on the same condition. The comparison results show that this two-dimensional model can forecast axial temperature distribution in ullage gas and in tank wall correctly. In addition, the computation results show that the effect of the direction and the area of pressurized gas injector on the axial temperature distribution in the ullage gas and in the tank wall is weak, but the temperature field nearby gas inlet is little affected by them. When pressurized gas is injected downstream into the tank ullage, the gas temperature nearby tank top is lower, which may be favorable to the normal operation of relief value. When pressurized gas is injected into the tank ullage horizontally, the bigger diameter of the injector means larger high-temperature region nearby the tank top.