贮箱作为航天器推进系统的重要组成部件，其内部液体推进剂的管理对航天任务具有重大意义。特别是对于低温推进剂而言，在长期空间飞行过程中，由于低温推进剂易相变、黏度低、表面张力弱和相变潜热小等特性，贮箱系统存在着压力失衡、动力学不稳定等隐患，可能导致任务失败。因此，研究空间低重力和微重力环境中贮箱内低温推进剂的动力学行为及热量输运特性，有着极其重大的实用价值。本文采用数值模拟的方法来开展部分充液贮箱内界面行为和压力演化规律及相关热量输运特征的研究。

       首先，数值模拟了热平衡条件下重力跳降引起的界面波的传播及演化。基于 Bond 数准则设计了 3 个缩比模型,分析了原型贮箱和缩比模型中加速度变化引起 的贮箱内气液两相流动及气液界面上界面波的传播及特征，发现：基于 Bond 数 相似准则设计的缩比模型与原型贮箱之间流体的运动具有相似性，在满足 Bond 数相似准则的前提下，系统还近似满足 Weber 数相似准则，或等价地，近似满足 Froude 数相似准则。黏性耗散作用随着缩比比例的增大而增大，故在设计空间大 型贮箱地面模拟实验时，有必要适当约束缩比比例以避免缩比误差过大。大 Bond 数下，主波波谷的传播由重力和毛细力共同作用的界面波决定；而小 Bond 数下，主波波谷的传播由毛细力和惯性力共同作用的毛细爬升决定。

      其次，为了抑制重力跳降之后的界面波动，需引入近壁隔板来约束界面变动。同时，空间热辐射所引起的漏热自增压不可避免。因此采用数值模拟方法研究界面变动和热质输运耦合下近壁隔板的作用机理发现：在低重力条件下，位于液体中的隔板可以阻止隔板下方高温液体的上升，导致近壁区的液面温度偏低，从而使得有隔板贮箱的自增压速率比无隔板贮箱低 12%；在微重力条件下，近壁隔板能够显著减少质心的波动幅度。因此选择具有近壁隔板的贮箱能更好地应对复杂空间流体管理任务。此外，还针对隔板结构，采用数值模拟对隔板尺寸进行了管理性能的比较和方案推荐。

       最后，采用数值模拟的方法去研究关机滑行段大尺度低温贮箱内的失压过程 特征及抑制方法。分析了低重力和微重力环境下自旋速率对部分充液贮箱内失压 过程特征的影响：越大的自旋速度会使得贮箱内工质的质心在初始的半个周期内 更远地偏离初始位置，而这种更加剧烈的振荡会加剧低温推进剂与过热气体的掺 混换热，加速气体冷凝，导致降压速率显著增大。对于低重力条件，当自旋速率 从 0.05 增加到 0.1 rad/s 时，流体质心的振荡频率从 0.027 Hz 增加到了 0.029 Hz， 即增加了 7.41%。此外，异质气体的存在能显著抑制蒸气冷凝速率，从而极大地 降低失压速率。

   As an important component of the spacecraft propulsion system, the management of liquid propellant in the cryogenic tank is of great significance to space missions. Due to the characteristics of cryogenic propellants such as easy phase change, low viscosity, weak surface tension and low latent heat of phase change, the tank system is vulnerable to pressure imbalances and dynamic instability during long-term space flights, which may lead to mission failure. Therefore, it is of great practical value to study the dynamic behaviour and heat transfer characteristics of cryogenic propellants in tanks under low-gravity and microgravity environments. In this paper, numerical simulations are used to study the interfacial behaviour and pressure evolution laws, as well as the associated heat transfer characteristics in a partially filled tank.

  Firstly, the propagation and evolution of interface waves are numerically simulated upon step reduction in gravity under thermal equilibrium conditions. Based on the Bond number criterion, we design three scaled-down models and analyze the two-phase flow and the interface wave characteristics on the gas-liquid interface in both prototype and scaled-down models upon step reduction in gravity. We observe similarities in fluid motion between the scaled-down model and the prototype tank. Under the premise of satisfying Bond number similarity criterion, the system also approximately satisfies Weber number similarity criterion, or equivalently, the Froude number similarity criterion is approximately satisfied. With an increase in scaled-down ratio, the viscosity dissipation effect increases, and hence it is necessary to constrain the scaled-down ratio appropriately while designing ground simulation experiments of large space tanks to avoid substantial reduced-scale errors. Under large Bond numbers, the propagation of the main wave trough is governed by the interface waves jointly caused by gravity and capillary forces；Under small Bond numbers, the propagation of the main wave trough is governed by the capillary rise caused by both capillary and inertial forces.

  Secondly, in order to suppress the interface fluctuations upon step reduction in gravity, near-wall baffles are needed to constrain the interface motion. At the same time, the self-pressurisation of heat leakage caused by space heat radiation is inevitable. Therefore, numerical simulations are used to study the mechanism of action of the near-wall baffle under the coupling of interface motion and heat and mass transfer. It is found that under low gravity conditions, a baffle located in the liquid prevents the warm liquid below the baffle from rising, resulting in a lower liquid surface temperature in the near-wall zone, which results in a 12% lower self-pressurisation rate in a baffled tank than in a non-baffled tank. Under microgravity conditions, the near-wall baffles significantly reduce the amplitude of fluctuations in the centre of mass of the fluid in the tank. Therefore, the tank with near-wall baffles is better suited to fluid management tasks in space. In addition, numerical simulations are conducted to compare and optimize the management performance of baffle sizes in the baffle structure.

  Finally, numerical simulations are used to study the characteristics and suppression method of the pressure drop in the large-scale cryogenic tank during shutdown coasting phase. The effect of spin rate on the characteristics of the pressure drop process in the partially filled tank is analysed under low gravity and microgravity environments. It is found that larger spin rates cause the center of mass of the working fluid inside the tank to deviate further from the initial position during the first half period. The more intense oscillation intensifies the mixing and heat transfer between the subcooled propellant and the superheated gas to accelerate vapor condensation, resulting in a significant increase of the pressure drop rate. For low gravity conditions, when the spin rate increases from 0.05 to 0.1 rad/s, the oscillation frequency of the fluid centre of mass increases from 0.027 Hz to 0.029 Hz, which is an increase of 7.41%. Additionly, the presence of heterogeneous gases significantly suppresses the vapour condensation rate and therefore reduce the rate of pressure drop.