微重力下成一定夹角平板间的表面张力驱动流动的研究
CAPILLARY RISE OF LIQUID BETWEEN PLATES WITH A CERTAIN ANGLE UNDER MICROGRAVITY
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摘要:空间微重力环境中, 由于重力基本消失, 表面张力等次级力发挥主要作用, 流体行为与地面迥异, 因此有必要深入探究微重力环境中的流体行为规律和特征. 板式贮箱利用板式组件在微重力环境中对流体进行管理, 从而为推力器提供不夹气的推进剂, 这对航天器精确进行姿态控制、轨道调整具有重要意义. 板式组件中常包含成一定夹角的平板结构, 比如蓄液叶片之间. 本文研究了微重力环境中成一定角度平板间的表面张力驱动流动问题, 考虑了液体与壁面的动态接触角、对流引起的压力损失、黏滞阻力、液池内弯曲的液面等因素的影响, 推导出了表面张力驱动流动中液体爬升高度的二阶微分方程. 该方程可用四阶Runge−Kutta方法求解. 通过同时考虑两个主导力, 可将流动过程分为三个阶段, 并得到了不同阶段内的爬升高度的近似方程. 本研究建立了6个不同尺寸的计算模型、选用3种不同型号的硅油, 利用有限体积法开展仿真工作, 仿真结果与理论结果吻合良好, 验证了理论解的正确性. 本文的研究结果可为板式贮箱的研制和空间流体管理提供理论依据和数据支撑.Abstract:In space, because the gravity basically disappears and the secondary forces such as surface tension force play a major role, fluid behavior is quite different from that of the ground. Therefore, it is necessary to deeply explore the laws and characteristics of fluid behavior in microgravity environment. The plate-type tank uses plate-type components to manage the fluid in microgravity environment, so as to provide the thruster with gas-free propellant, which is of great significance for the precise attitude control and orbit adjustment of the spacecraft. Plate-type components often include plates with a certain included angle, such as liquid storage blades. The capillary rise of liquid between plates with a certain angle under microgravity is explored in this paper. The influences of the dynamic contact angle between the liquid and the plates wall, the pressure loss caused by convection, the viscous resistance, and the curved liquid surface in the reservoir are all considered. A second order differential equation of the capillary-driven flow is derived, which can be solved with forth-order Runge−Kutta method. By considering two dominant forces at the same time, the flow can be divided into three regions, and approximate equations of climbing height in different regions are obtained. Six kinds of numerical models are created, three kinds of silicone oil is chonsen and Volume of Fluid(VOF) method is used to carry out numerical simulation. Numerical results are in good agreement with theoretical results, which verifies theoretical analysis. This research can be theoretical basis for plate tanks’ design and fluid management in space.