液滴接触变形对融合过程影响的实验研究

魏存驹; 李应杰; 王鲁海; 杨基明

doi:10.11729/syltlx20160146

液滴接触变形对融合过程影响的实验研究

1.
中国科学技术大学近代力学系, 合肥 230027
2.
中国水利水电科学研究院, 北京 100038

详细信息

作者简介:
魏存驹(1994-), 男, 甘肃兰州人, 本科生。研究方向:实验多相流体力学。通信地址:安徽省合肥市蜀山区黄山路443号中国科学技术大学西校区(230027)。E-mail:wcj1320@mail.ustc.edu.cn

通讯作者:
杨基明, E-mail:jmyang@nstc.edu.cn

中图分类号: O359.1
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出版历程
- 收稿日期: 2016-09-22
- 修回日期: 2016-12-26
- 刊出日期: 2017-06-24

Experimental study of the effects of contact deformation on drop coalescence scenario

1.
Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China
2.
China Institute of Water Resources and Hydropower Research, Beijing 100038, China

摘要

摘要: 采用一种产生大尺寸液滴和顶视视角观测的新方法，借助高速阴影系统，捕捉到液滴融合过程中液桥截面形态的变化。从光学观测的角度验证了以前电测法所得到的初期融合过程描述。利用顶视方法所特有的辨别液桥几何形状、中心位置等优势，观测了不同液滴靠近速度（v_a）下2种融合模式。根据液桥中心演变特征分别判定为中心融合和边缘融合模式，并发现两者之间存在一临界液滴靠近速度（v_cross），当v_a < v_cross时，融合过程始于接触中心，而当v_a >v_cross时，融合自液滴挤压形成的液膜边缘开始，与融合前液滴接触变形密切相关。
- 液滴融合 /
- 液滴碰并 /
- 液滴变形
Abstract: The evolution of cross section of the liquid bridge during drop coalescence is captured with a new type of experimental setup which contains the generation of large drops, top-view observation and high-speed shadowgraph. The optical results support the previous findings obtained with electrical measurements in the initial stage of the coalescence. Thanks to the unique advantages of the top-view observation, the shape and position of the liquid bridge connecting the drops is clearly demonstrated in this paper. Two coalescence scenarios with different approaching speed of the drops, v_a, are distinguished as the center scenario and the off-center scenario based on the location of the starting point of coalescence. The critical speed, v_cross, which divides the scenarios, is noticed and measured with the present device. It is found that the approaching speed has little influence on the coalescence process in the center scenario when v <v_cross. On the contrary, the onset of coalescence switches to the edge of the contacting film formed by the approaching drops and the off-center scenario appears consequently when v> v_cross.
- drop coalescence /
- drop collision /
- drop deformation

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图 1 实验装置原理图

Fig. 1 Schematic of experimental setup

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图 2 较低靠近速度下圆形融合过程

Fig. 2 The coalescing process at lower approaching speed

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图 3 较高靠近速度下形变融合过程

Fig. 3 The coalescing process at higher approaching speed

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图 4 液桥半径随时间变化关系

Fig. 4 Liquid bridge radius versus time

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图 5 液桥中心偏移与融合前接触变形示意图

Fig. 5 The displacement of bridge center and drop deformation before coalescence

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图 6 不同靠近速度下液桥中心偏移曲线

Fig. 6 The displacement of liquid bridge center versus time with different approaching speeds

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图 7 不同靠近速度下液桥最大中心偏移与理论液膜半径关系

Fig. 7 The displacement of bridge center and theoretical bridge radius versus approaching speed

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图 8 实际液膜半径r_f与液桥最大中心偏移l_r关系

Fig. 8 The radius of liquid film r_f versus the displacement of bridge center l_r

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表 1 液滴与环境液体的相关物性参数

Table 1 The properties of the drop and ambient fluid

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