主管部门: 中国航天科技集团有限公司
主办单位: 中国航天空气动力技术研究院
中国宇航学会
中国宇航出版有限责任公司

关于沿内角的自发毛细流动现象回顾

Review of Spontaneous Capillary Driven Flow along Interior Corners

  • 摘要: 文章从静力和动力学的角度简要回顾了关于沿内角的自发毛细流动研究的最近进展.作为一个通用几何形状,内角在地面微观尺度下或处于失重状态的航天飞行器系统内大尺度下为液体提供有效的输运通道.当一定的几何条件得到满足并且当毛细力远远大于体力比如重力的时候,沿着内角会发生自发毛细力驱动流动现象.从静力学的角度来说,本文讨论的自发毛细驱动流动和当特定的边界条件发生突然变化,比如重力作用突然消失时带有内角的容器内部单值有限高度的平衡自由面的非存在性有关系. Concus-Finn方法可以用来确定这样的平衡自由面在一个横截面处处一致的柱形容器内的非存在性.用这个方法可以推导出在失重状态下一个内角为2α的通常柱形容器里,当接触角小于π/2-α时,平衡曲面不存在.通常来说,沿内角的自发毛细驱动流动属于层流.利用尺度分析和摄动法,成功分析了该流动的动力学特性,并且推导出对设计有用的封闭形式的解析解.一个典型的结果是在黏性流的范畴里毛细面端点的移动和t1/2成正比

     

    Abstract: This paper briefly reviews the recent development in understanding the spontaneous capillary driven flow along interior corners from both static and dynamic point of views. Interior corners are a common geometric element for effective liquid transport in micro-scale in terrestrial condition or in large length scale in micro-gravity onboard spacecraft system. Spontaneous capillary driven flows take place along the interior corners when certain geometric conditions are satisfied and when capillary forces dominate body forces such as gravitational forces. From the static point of view, the spontaneous capillary driven flow discussed herein is related to the non-existence of equilibrium capillary surfaces in containers possessing the interior corners when certain boundary conditions undergo sudden changes such as gravity vanishing abruptly. The non-existence of the equilibrium surface in a cylindrical container of uniform cross section can be identified using Concus-Finn method. In a generic cylindrical container with an interior corner of 2α, the method can be applied to show that the equilibrium surface fails to exist in zero gravity when contact angle is less than π/2-α. In general the spontaneous capillary flow along the interior corners is in the regime of laminar flows. The dynamics of such flow has been analyzed successfully using scaling and perturbation method yielding closed form analytic solutions which are useful for design purpose. A typical result is that in the viscous regime the movement of the meniscus tip is proportional to t1/2.

     

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