Effect of surfactants on hydrodynamics characteristics of bubble in shear thinning fluids at low Reynolds number  

低雷诺数下表面活性剂对剪切变稀流体中气泡流动特性的影响

作　　者：LI Shao-bai FAN Jun-geng LI Run-dong WANG Lei LUAN Jing-de 李少白;范俊赓;李润东;王雷;栾敬德

机构地区：[1]Liaoning Key Laboratory of Clean Energy and College of Energy and Environment,Shenyang Aerospace University

出　　处：《Journal of Central South University》2018年第4期805-811,共7页中南大学学报（英文版）

基　　金：Project(21406141)supported by the National Natural Science Foundation of China;Project(20141078)supported by the National Basic Research Program,China;Project(L201733)supported by the Research Foundation of Education Bureau of Liaoning Province,China

摘　　要：In this study,the effects of surfactants on the hydrodynamic characteristics of bubbles in shear-thinning fluids at low Reynolds number(Re<50)are investigated.The bubble terminal velocity and drag coefficient of bubble in clean and contaminated carboxymethylcellulose(CMC)solutions are obtained using a high-speed camera for examining differences.The results show that the existence of surfactant could reduce the terminal velocity of bubble at small volume(0.25wt%CMC:<100 mm3;0.50wt%CMC:<110 mm3),attributed to stiffening the bubble interface.However,this negative effect decreases and finally disappears with increasing bubble volume.The drag coefficient curves of the bubble in contaminated CMC solution exhibit behavior similar to that exhibited by a solid sphere at Re<10,indicating that internal circulation flow is absent at the bubble interface as compared to that in clean CMC solution.However,for 10<Re<40,a transition of drag curve from 24/Re to 16/Re in contaminated CMC solution is observed,which is easy at low SDS concentrations and high CMC concentrations.研究了低雷诺数下(Re<50)表面活性剂对剪切变稀流体中气泡流动特性的影响。为便于比较,利用高速摄像机采集图片并处理得到了气泡在未添加以及添加表面活性剂的羧甲基纤维素钠(CMC)溶液中的终端速度和曳力系数。结果表明,当气泡体积较小时(0.25wt%CMC:<100 mm^3;0.50wt%CMC:<110 mm^3),由于表面活性剂导致气泡表面的刚化,其终端速度显著的降低。但随着气泡体积的增大,表面活性剂的影响逐渐减小,进而消失。由曳力系数曲线可知,当Re<10时,含有表面活性剂的CMC溶液中的气泡曳力系数曲线与固体小球相似,当10<Re<40时,曳力系数曲线开始由24/Re向16/Re转变,且CMC溶液浓度越高,表面活性剂浓度越低,转变越容易。

关 键 词：SURFACTANT single bubble shear thinning fluids VELOCITY drag coefficient 

分 类 号：O647.2[理学—物理化学]