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过程工程学报 ›› 2019, Vol. 19 ›› Issue (1): 102-109.DOI: 10.12034/j.issn.1009-606X.218147

• 流动与传递 • 上一篇    下一篇

液滴滴浸微通道入口段的动力学特性分析

李培生, 连小龙, 张 莹*, 赵万东, 刘 强, 卢 敏, 杜 鹏   

  1. 南昌大学机电工程学院,江西 南昌 330031
  • 收稿日期:2018-03-01 修回日期:2018-09-21 出版日期:2019-02-22 发布日期:2019-02-12
  • 通讯作者: 张莹
  • 基金资助:
    国家自然科学基金

Dynamic analysis of droplet impregnation microchannel in entry

Peisheng LI, Xiaolong LIAN, Ying ZHANG*, Wandong ZHAO, Qiang LIU, Min LU, Peng DU   

  1. School of Electrical and Mechanical Engineering, Nanchang University, Nanchang, Jiangxi 330031, China
  • Received:2018-03-01 Revised:2018-09-21 Online:2019-02-22 Published:2019-02-12
  • Contact: Ying ZHANG

摘要: 采用流体体积(Volume of Fluid, VOF)函数捕捉气液相界面,研究液滴滴浸微通道入口段的运动,通过改变微通道入口段的截面宽度、润湿特性及液滴雷诺数(Re)和韦伯数(We)研究滴浸过程的动力学特性。结果表明,微通道入口段的截面宽度对液滴浸入微通道时的撞击过程影响最明显,随截面宽度减小,液滴撞击通道入口后通过微通道的难度增加,整个过程液滴所受阻力逐渐增大;当微通道截面宽度减至0.2 mm时,壁面润湿性效应凸显,表现为壁面静态接触角越大,液滴滴浸微通道时所受的阻力也越大。表面接触角较大时,为使液体通过微通道入口段,可适当增大液滴的Re,液体在通道内的浸润长度随Re增加成比例增大,当Re增至4000时,通道内开始出现射流现象。We减小,表面张力效应变得明显,通道内的流动阻力变大,液体流过微通道入口段的难度增大。

关键词: 液滴撞击, 微通道, 接触角, VOF

Abstract: Droplet impregnate microchannel was a widely existed phenomenon in microfluidic control, while the mechanism of dynamic motion during impact was not well addressed. A numerical model was developed using volume of fluid (VOF) method and the model was validated by experiments. In this work, the gas?liquid interface was captured using VOF method and the phenomenon of droplet impregnating microchannel was studied. Among the many simulation cases, it was found that the section width, contact angle, Re number and We number had significant influences. In the process, the effects of section width, contact angle, Re number and We number were studied in details. After comparing the results of each cases, it was clear that the cross section's width of the microchannel inlet had the most obvious impact on the process of the droplet impregnating in the microchannel. And it was found that the smaller the width was, the more difficult for the droplet to pass the microchannel after colliding with the entrance of the channel. When the microchannel's cross-sectional width was reduced to 0.2 mm, the effect of the static contact angle of the wall surface would appear. The larger the static contact angle of the wall, the greater the resistance of the droplet to microchannel. Under the condition of large static contact angle, the length of the liquid in the channel can be increased by appropriately increasing the Re number of the droplet so that the liquid passed through the microchannel. However, when the Re number reached 4000, jet phenomenon would happen. Then the liquid would flow through the microchannel in large quantities, and spread diameter would also increase significantly. As the We number decreased, the surface tension effect became obvious, the flow resistance in the microchannel became larger, and the liquid flowing through the microchannel would be more difficult, meanwhile the length of the infiltration was significantly reduced.

Key words: droplet impact, microchannel, contact angle, VOF