微重力环境低温流体无排气加注过程数值研究

针对加注系统受注贮箱,采用CFD方法就液氮贮箱无排气加注过程开展数值仿真,对比了不同重力水平下的无排气加注性能,分析了加注口结构、壁面初始温度、加注流体温度和加注流量等因素对微重力无排气加注性能的影响规律。所构建的二维轴对称模型将流体区与固壁区一起作为求解区域并划分网格,并通过植入用户自定义程序(UDF)计算加注口液体闪蒸过程及气液之间的热质交换。经过实验数据验证,该模型能够合理展示箱内温度场分布和相分布情况,并获得贮箱压力等参数变化信息。数值计算结果表明:(1)加注条件相同时,微重力工况较常重力工况体现出更好的无排气加注性能。(2)微重力条件下,无排气加注性能几乎不受加注口结构的影响,壁面初始温度和加注流体温度越高,贮箱压力越高,加注流量仅对加注时间有显著影响。

Numerical investigation of no-vent fill process of cryogens under microgravity condition

A numerical study using CFD simulation method was performed on the no-vent fill process in a liquid nitrogen tank which is the received tank of the supply system.The no-vent filling performances under different gravities are comparatively analyzed and the effects caused by the inlet structure,the initial wall temperature,the inlet fluid temperature and the flow rate were studied.In the built two-dimensional model,the fluid and the solid regions are both generated mesh as the analysis region,and the low-Re κ-ε model is selected to calculate the coupled heat transfer between fluid and tank wall.An user-defined function (UDF) is compiled and embedded into Fluent so as to research the liquid flash at the inlet and the effect of heat and mass transfer at the liquid surface.Verified by the experimental data,this model could display temperature and phase distribution in the tank and forecast other parameters information correctly.The computation results show that:(1)The no-vent fill performance at microgravity is better than that at normal gravity under the same fill conditions.(2)At microgravity,the inlet structure has slight effect on the performance of novent fill process,and the pressure in the tank increases with the initial temperature of the wall and the temperature of the injected fluid.Moreover,the inlet mass flux only has an apparent influence on the fill time.