剪切流场中分散相液滴行为研究

Investigation on dispersed droplets behavior in a shear flow

目前乳化液破乳机理研究领域对剪切流场作用下分散相液滴行为的研究仍存在一些需要解答的问题。通过设计内外筒反向旋转剪切实验装置,结合数字图像处理技术,从实验角度进行了系统研究。实验数据显示液滴在剪切流场中发生三维力学变形,通过提出液滴形变非仿射度和综合变形度的概念,对液滴变形规律及其机理进行了相应的实验及理论探讨。同时,通过新颖可靠的测量方法,探索了液滴变形过程中内外流场压差的变化规律,数据显示液滴内外压差变化显著,且影响液滴形态。此外,还对剪切流场中液滴的变形过程进行了数值模拟,结果与实验及理论符合较好。提出了一套系统的液滴模型描述方法,为今后精确液滴变形形态数学模型的建立打下基础。

The dispersed emulsion droplet behavior in shear tlow field is of great importance to demulsification and many industry applications. Aiming at providing fundamental insights into this field,this paper presents a systematic investigation on droplet deformation. Experiments were conducted with a novel experimental set-up,which includes a shear flow generator,image acquire system and digital image processing technique. Experimental results show that three-dimensional mechanical model is applicable to droplets deformation in shear flow. The non-affine degree and integral deformation degree concepts are proposed to study the droplets deformation behavior and related influence factors. Meanwhile, this study proposed a novel measuring technique,with which the differential pressure inside and outside the deformed droplet was studied. Data acquired show that there is a significant variation on the differential pressure when droplets are reformatting in the shear flow,and the droplet shape is a function of the differential pressure variation which in- creases with integral droplet deformation degree. In addition,a fundamental simulation was carried out to compare with the experiment and theory analysis, which shows good consistency. This paper presents a comprehensive system to describe and study the droplet behaviors in a shear flow.