The interface distribution and self-pressurization phenomenon are the most important problems in the storage of cryogenic liquid on orbit, which are difficult to be predicted and assessed exactly due to the complex non-equilibrium thermal behavior. In this paper, one 3-D CFD model based on volume of fluid (VOF) method is established to investigate the interface evolution and self-pressurization process in the liquid oxygen (LOX) tank in microgravity environment with various heat loads and gravitational accelerations. The validity of the model is verified by both the present ground experiments and the drop tower experiments from literature. The impact of microgravity on the gas-liquid interface distribution in the cryogenic tank is analyzed. Different from the ground condition, the distribution behavior of the gas-liquid two-phase fluid in microgravity is that the liquid is covering the tank wall, and the ullage is staying at the top of the tank surrounded by the liquid. Then the pressurization rate of the tank with different gravitational accelerations is obtained. The tank pressure rise rate increases with the reducing of the gravity. The results are beneficial to the optimal design of the cryogenic propellant tank.

中文翻译：

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低温推进剂罐界面蠕变和增压行为的数值模拟

界面分布和自加压现象是低温液体在轨存储中最重要的问题，由于复杂的非平衡热行为而难以准确预测和评估。本文建立了一种基于流体体积（VOF）方法的3-D CFD模型，研究了在不同热负荷和重力加速度下微重力环境下液氧（LOX）储罐中的界面演化和自加压过程。现有的地面实验和文献中的落塔实验都验证了该模型的有效性。分析了微重力对低温罐中气液界面分布的影响。与地面情况不同 气液两相流体在微重力下的分布行为是液体覆盖罐壁，缺量停留在被液体包围的罐顶部。然后获得具有不同重力加速度的储罐的增压率。罐的压力上升率随着重力的减小而增加。结果有利于低温推进剂罐的优化设计。