微重力状态下，重力的影响基本消失，液体的内聚力、表面张力等在地面时影响较小的次级力此时发挥了主要作用，所以处于微重力水平中的液体形貌特征和流动行为与地面上的液体行为迥异。贮箱在航天器的轨道维持和姿态调整中发挥了重要作用，贮箱提供的推进剂若夹气，对轨道控制危害极大；排空率不高，将会缩短卫星寿命。航天器在变轨、制动以及交会对接过程中，液态推进剂可能会出现明显的晃动，因此造成的晃动力和晃动力矩可能对整星的系统动力学产生显著的影响。因此，需要深入探究微重力环境下贮箱内的流体行为，包括液体推进剂的重定位过程、表面张力驱动流动、液体晃动及气液分离等。配合空间站首批空间科学实验项目之一——“空间流体储存、输运及界面行为研究”，本文从理论分析、数值模拟和实验探究三个方面开展了表面张力驱动流动和贮箱结构参数优化设计的研究，深入分析了流动机理和流动行为特征，总结得到了一系列有价值和创新性的研究成果，主要的工作内容有：

推导出了微重力环境下椭圆管内表面张力驱动流动爬升高度的二阶微分方程，通过落塔实验和基于有限体积（VOF）方法的数值模拟进行验证，为贮箱集液管的设计提供理论基础。并对该方程进行无量纲化得到了无量纲方程，可为研究模型的缩比提供理论依据。对椭圆管内表面张力驱动流动的机理做了深入的分析。在低Oh数情况下，流动过程可以分成三个阶段，三个阶段液体爬升高度分别与t²、t和t^1/2成正比。在高Oh数的情况下，流动只可以分成两个阶段，在第一阶段，液体爬升高度依然与t²成正比；在第二阶段，当流动距离足够远，可以忽略h₀时，依然可以认为爬升高度与t^1/2成正比。

推导出了微重力环境下同心圆管间表面张力驱动流动爬升高度的二阶微分方程，通过落塔实验和数值模拟进行了验证，为贮箱蓄液器的设计提供参考。对其流动机理进行了深入的分析。在高Oh数情况或者低Oh数低Re数下，流动过程可以分成两个阶段；当低Oh数高Re数时，流动过程可以分成三个阶段，爬升高度分别与t²、t和t^1/2成正比。引入运动边界条件，推导出了具有轴向恒定运动速度圆管内的流动方程，基于此方程可以精确预测运动圆管内液体流动距离和形位特征，并对其机理进行了初步的分析。

推导出了微重力环境下成一定夹角的两块平板间表面张力驱动流动爬升高度的二阶微分方程，通过数值模拟进行了验证，并对其流动机理进行了深入的分析。流动过程在所有情况下都可以分成三个阶段，爬升高度分别与t²、t和t^1/2成正比。该研究可为贮箱导流板等的设计提供理论依据。

基于上述基础理论研究，构建了板式贮箱参数设计优化方法，通过对不同宽度的导流板、不同尺寸的间隙的贮箱模型进行落塔实验和数值模拟，对它们的性能展开了对比和验证，发现流动速度并不随着间隙单调变化，合理选择间隙尺寸有利于提高液体流动速度；流动速度也并不随着导流板宽度单调变化，合理选择导流板宽度有利于取得最优的传输效率。同时，对防晃板的性能进行了仿真验证。

In microgravity environment, the influence of gravity basically disappears. The cohesive force, surface tension of the liquid and other secondary forces that have a small influence on the ground play a major role in this condition. So the free surface and flow behaviour of liquid are totally different from that on the ground. The tank plays an important role in the orbit maintenance and attitude adjustment of the spacecraft. If the propellant provided by the tank is trapped, it will be extremely harmful to the orbit control. If the extrusion rate is not high, it will shorten the satellite’s life. And during the process of spacecraft's orbit change, rendezvous and docking, the propellant may vibrate significantly, and the sloshing force and swaying moment caused by these may have a significant impact on the system dynamics of the entire sattelite. Therefore, it is necessary to deeply explore the fluid behavior in the tank under microgravity, including the repositioning process of the liquid propellant, capillary driven flow, liquid sloshing, and gas-liquid separation. Preferred with one of the first space station science experiment projects—“Fluid Storage, Transportation and Interface Behavior Research in Space”, capillary driven flow and optimization of tank structure parameters are sdudied in this thesis from three aspects: theoretical analysis, numerical simulation and experimental exploration. The mechanism and flow behavior characteristics are analyzed in depth. A series of valuable and innovative research results are obtained in this thesis, the main work contents are as follows:

The second-order differential equation of the meniscus height vs time in oval tubes under microgravity is derived, and it’s verified by drop tower experiments and numerical simulations based on Volume of Fluid (VOF) method. This study can provide theoretical basis for design of collecting pipes in tanks. The dimensionless equation is also obtained, which provides theoretical basis for the reduction ratio of the model. At the same time, an in-depth analysis is made on the mechanism of capillary driven flow in oval tubes. In case of low Oh numbers, the flow process can be divided into three stages. In these three stages, the meniscus height is proportional to t², t and t^1/2. In case of high Oh numbers, the flow can only be divided into two stages. In the first stage, the meniscus height is still proportional to t². In the second stage, when the flow distance is long enough to ignore h₀, the meniscus height can also considered to be proportional to t^1/2.

The second-order differential equation of meniscus height vs time in concentric annuli under microgravity is derived, and it’s verified by drop tower experiments and numerical simulation. This study can provide theoretical basis for design of the accumulator in tanks. And the flow mechanism is analysed deeply. In case of high Oh numbers or low Oh numbers and Re numbers, the flow process can be divided into two stages. In case of low Oh numbers and high Re numbers, the flow can be divided into three periods, and the meniscus height is proportional to t², t and t^1/2 respectively. Combined with moving boundary conditions, the equation of meniscus height vs time in cylinder tubes with a constant axial speed under microgravity is derived. Based on this equation, it is possible to accurately predict the flow distance and behavior. and its mechanism is preliminary analyzed.

The second-order differential equation of meniscus height vs time between two plates with a certain angle under microgravity is derived, and it’s verified by numerical simulation. The mechanism is analyzed in depth. The flow process can be divided into three stages in all cases, and the meniscus height in three stages is proportional to t², t and t^1/2. These results will be helpful for deflectors’ design in tanks.   

Based on basic theoretical research above, a method for designing and optimizing the parameters of plate tanks is proposed. Drop tower experiments and numerical simulation are carried out on the tank models with different deflectors and gaps of different sizes, and their performance is compared and verified. It is found that the flow velocity does not change monotonously with the gap size. A reasonable selection of the gap size is beneficial to increase the liquid flow speed. The flow speed does not change monotonously with the width of deflectors, and a reasonable selection of deflectors’ width is helpful for achieving the best transmission efficiency. At the same time, the performance of the anti-sloshing baffles is simulated and verified.