Coalescence dynamics of two droplets of different viscosities in T-junction microchannel with a funnel-typed expansion chamber  

作　　者：Weixi Guo Chunying Zhu Taotao Fu Youguang Ma 

机构地区：[1]State Key Laboratory of Chemical Engineering,School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China

出　　处：《Chinese Journal of Chemical Engineering》2021年第10期43-52,共10页中国化学工程学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(92034303,91834303 and 21776200);the aid of Program of Introducing Talents of Discipline to Universities(BP0618007)。

摘　　要：The coalescence behavior of two droplets with different viscosities in the funnel-typed expansion chamber in T-junction microchannel was investigated experimentally and compared with droplet coalescence of the same viscosity.Four types of coalescence regimes were observed:contact non-coalescence,squeeze non-coalescence,two-droplet coalescence and pinch-off coalescence.For droplet coalescence of different viscosities,the operating range of non-coalescence becomes narrowed compared to the droplet coalescence of same viscosity,and it shrinks with increasing viscosity ratioηof two droplets,indicating that the difference in the viscosity of two droplets is conducive to coalescence,especially when1<η<6.Furthermore,the influences of viscosity ratio and droplet size on the film drainage time(Tdr)and critical capillary number(Ca)c)were studied systematically.It was found that the film drainage time declined with the increase of average droplet size,which abided by power-law relation with the size difference and viscosity ratio of the two droplets:Tdr~(ld)^(0.25±0.04)and Tdr~(η)^(﹣0.1±0.02).For droplet coalescence of same viscosity,the relation of critical capillary number with two-phase viscosity ratio and dimensionless droplet size is Cac=0.48λ^(0.26)l^(﹣2.64),while for droplet coalescence of different viscosities,the scaling of critical capillary number with dimensionless average droplet size,dimensionless droplet size difference and viscosity ratio of two droplets is Cac=0.11η^(﹣0.07)ls^(﹣2.23)l^(0.16)_(d).

关 键 词：MICROCHANNEL DROPLET COALESCENCE Viscosity ratio Critical capillary number 

分 类 号：TQ02[化学工程]