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中文核心期刊

基于磁补偿实验的微重力下毛细管内动态流动特性研究

INVESTIGATION ON FLUID DYNAMICS IN A CAPILLARY TUBE UNDER MICROGRAVITY BASED ON THE MAGNETIC COMPENSATION EXPERIMENT

  • 摘要: 微重力环境下流体由于受到毛细力的主导作用, 其流动特性相较于地面常重力环境有着本质上的不同. 基于磁补偿原理, 在地面上建立了具有高可调性的微重力模拟流动实验台, 通过将实验数据与理论模型进行对比的方法验证了实验系统的准确性, 并对不同等效重力水平下竖直毛细管内水基磁流体的动态流动行为进行研究. 实验数据与两种采用不同动态接触角模型的理论模型解的平均相对偏差分别为7.1%和13.7%, 验证了利用磁补偿方法开展微重力流动研究的可行性. 进一步, 定量研究了管径大小、等效重力水平以及接触角等因素对毛细管内动态流动特性的影响. 在近似零重力的环境下, 可将动态流动过程分成三个阶段: 即液面高度h先后与t2, t, \sqrt t 成线性关系. 管径对毛细爬升过程的影响复杂, 其对流动的影响并不随着管径呈线性变化, 在不同的流动阶段对流速的影响规律也不相同. 等效重力加速度越大, 水基磁流体在管内的毛细爬升能力越差, 且越难观察到第一毛细爬升阶段的存在. 相同条件下, 流体的前进接触角越大, 其毛细爬升速率越小.

     

    Abstract: Due to the dominance of capillary force, the flow characteristics of fluid in microgravity environment are essentially different from those in normal gravity environment. Based on the principle of magnetic compensation, an experiment platform simulating the flow under microgravity with high tunability is established on the ground. The accuracy of the experimental system is verified by comparing the experimental data with the theoretical models, and the dynamic flow behavior of water-based magnetic fluid in vertical capillary tube under different equivalent gravity levels is studied. By comparing the experimental data with the different theoretical model solutions, the feasibility of using the magnetic compensation method to carry out the investigation on microgravity flow is verified. The average deviation between the experimental results obtained by the magnetic compensation method and the two theoretical model solutions using different dynamic contact angle models is 7.1% and 13.7% respectively. Furthermore, the influence of factors such as pipe diameter, equivalent gravity level and dynamic advancing contact angle on the dynamic flow characteristics in the capillary tube has been quantitatively studied. In a near zero-gravity environment, the flow development process can be divided into three stages where the liquid level h has a linear relationship with t^2 , t, \sqrt t successively. The pipe diameter has a complicated affect on the capillary climbing process. The influence of pipe diameter on flow does not change linearly with pipe diameter and its influence on the flow velocity is different among flow stages. For the capillary flow in the vertical direction, the greater the equivalent gravitational acceleration, the worse the capillary climbing ability of the magnetic fluid in the tube, and the more difficult it is to observe the existence of the first capillary climbing stage. Under the same conditions, the larger the dynamic advancing contact angle of the fluid, the smaller the capillary climbing velocity.

     

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