表面活性剂流体弹性应力对颗粒沉降的影响  

Effect of elastic stress of viscoelastic surfactant fluid on particle sedimentation

作　　者：王治国[1] 蔺靖杰 刘凯 郭姜汝 苏晓辉 张恒 Wang Zhiguo;Lin Jingjie;Liu Kai;Guo Jiangru;Su Xiaohui;Zhang Heng(School of Mechanical Engineering,Xi’an Shiyou University,710065,Xi’an,China;Engineering Technology Research Institute of PetroChina Coalbed Methane Company Limited,710082,Xi’an,China)

机构地区：[1]西安石油大学机械工程学院,西安710065 [2]中石油煤层气有限责任公司工程技术研究院,西安710082

出　　处：《应用力学学报》2021年第4期1415-1422,共8页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(52074220,51906202);陕西省自然科学基金(2019JM-268)。

摘　　要：颗粒在粘弹性表面活性剂流体中的沉降问题是复杂固液两相流研究的基础问题。采用实验和数值模拟的方法研究了单颗粒在粘弹性表面活性剂流体中的沉降过程。实验结果表明,粘弹性表面活性剂流体的粘弹性会引起颗粒的终端速度随时间产生波动。Giesekus本构方程可以描述颗粒在表面活性剂流体中沉降的非线性剪切变稀行为和弹性导致的拉伸变形。颗粒在粘弹性表面活性剂流体中沉降时其尾部会出现负尾迹现象,负尾迹区随着松弛时间的增大向下游延伸,表征流体弹性的松弛时间越大,负尾迹区越长。颗粒表面剪切速率大于临界剪切速率时,负尾迹的出现使颗粒在粘弹性表面活性剂流体中沉降所受曳力减小,沉降速度增加;颗粒表面剪切速率小于临界剪切速率时,粘弹性表面活性剂流体负尾迹区的拉伸效应与颗粒表面的弹性应力的共同作用,导致颗粒终端速度随着松弛时间的增加先增大后减小。Particle settling is a fundamental problem for solving the complexity of solid-liquid two-phase flow,especially in viscoelastic surfactant fluid(VES).In this work,the sedimentation process of a single particle in a VES is investigated by experiment and numerical simulation method.Experiments results show that the final settling velocity of the particles fluctuates with the viscoelasticity in VES.The behavior of non-linear shear thinning and extensional stress in the process of particle settlement can be interpreted correctly utilizing the Giesekus constitutive model.There would be a negative wake at the rear of particle in the process of particle settling in the VES.The negative wake can extend downstream as the relaxation time increases.If the shear rate is greater than the critical shear rate,the negative wake can reduce the drag force of the fluid on the particle settlement.As a result,the settling velocity of particle increases.If the shear rate is less than the critical shear rate,both the negative wake and elastic stress can produce the final sedimentation velocity to fluctuate.As a result,the settling velocity firstly increases and then decreases with the increase of relaxation time.

关 键 词：颗粒沉降 粘弹性表面活性剂流体 Giesekus模型 负尾迹 弹性应力 

分 类 号：O373[理学—流体力学]