深空探测要求低温推进剂能够实现长期在轨安全贮存。微重力下的气液两相流表现出不同于地面的特征。在空间热作用下，低温流体升温气化，导致贮箱压力持续升高。准确预测低温流体在轨时的界面形态与压力变化可以为贮箱结构设计与控压技术选用提供依据，而我国在该领域的研究尚处于起步阶段。本项目拟采用理论分析、数值模拟与地面实验相结合的手段就处于微重力下的低温贮箱内部两相流运动与增压规律开展研究。采用数值方法研究重力缺失对气液两相流界面分布的影响，探明两相流运动的形成机理；建立微重力气液热质传递模型；构建CFD模型预示贮箱压增过程，探究提高CFD计算经济性的途径；搭建实验平台研究贮箱自增压、氦气增压、喷射器混合工况下的温度场分布与压力变化规律；针对不同的贮存目标提出压力控制技术选用原则。本项目的研究可缩小我国在低温流体在轨安全管理领域与国际先进水平的差距，为我国载人登月及深空探测提供理论和技术支持。

Long term on-orbit security storage of cryogenic propellant is necessary for deep space exploration. The characteristics of gas-liquid two-phase flow in microgravity are quite different from that on earth. Under the effect of space radiation heat flux, cryogenic fluids will experience the processes of temperature rise and liquid vaporization, and then bring about a continuous pressure rise. Understanding the interfacial configuration and pressurization behaviors of on-orbit cryogenic fluid is beneficial to the tank structure design as well as the selection of pressure control approaches, while the correlation researches in our country is still at its initial stage. In this research project, theoretical analysis, numerical simulation, and experimental approach will be applied to study the two-phase flow and pressurization behaviors for cryogenic tank in microgravity. The numerical approach will be employed to analyze the influence of microgravity on gas-liquid interfacial configuration, and the formation mechanism of two-phase flow will also be explored. A new phase change model, which can account for the vapor-liquid heat and mass transfer effects in microgravity, will be constructed. Moreover, several CFD models will be built to study the tank pressurization behaviors and boil-off rate at different on-orbit operating conditions and a list of approaches will be attempted to reduce the time consumption of CFD computations. In addition, a test platform will be established to study the thermal distribution and tank pressurization rate in several operating conditions, including self-pressurization, helium pressurization, and fluid mixture by ejector. Based on the above researches, a selection principle of pressure control approaches, which aims at different on-orbit storage target of cryogenic propellant, will be provided. The works of this project will narrow the gap between our country and advanced countries in the field of on-orbit cryogenic fluid management, and the results will provide a theoretical and technical guideline for domestic human lunar project and other deep space explorations.