平行圆盘间电流变液的挤压流研究

A study of squeeze flow of ER fluids between two parallel disks

采用双粘度本构模型研究了两平行圆盘间电流变液的挤压流特性,壁面边界上采用Navier滑移模型。流场根据其特性被分为两个区域:对称轴附近的牛顿区以及远离对称轴的双粘区;双粘区存在屈服面。本文在牛顿区和双粘区分别求解出其速度场和压力梯度场。壁面上的滑移速度与当地的压力梯度成正比;而压力梯度在牛顿区与r成正比,在双粘区r值较大的地方与r近似成线性关系。通过将压力梯度在双粘区近似为r的线性函数,可积分出流场的压力分布与作用在圆盘上的挤压力。此外,本文还通过计算,考察了速度场的分布特点,分析了滑移系数对速度场、压力梯度场、屈服面位置以及挤压力的影响。

Squeeze flow between closely-spaced parallel disks of an electrorheological （ER） material is considered for a Bingham fluid with Navier slip condition. A Bi-viscous model avoiding the yield-surface paradox is used to describe the Bingham fluid. The flow field is divided into a Newtonian part with high viscous Newtonian fluid which is near the axis,and a Bi-viscous part with yielded and unyielded fluids which is far away from the axis. The radial velocities and the pressure gradients in those two parts are obtained respectively. The slip velocity is proportional to the pressure gradient,and the pressure gradient is proportional to r in the Newtonian part and is approximately proportional to larger r in the Bi-viscous part. Furthermore,the pressure and the squeeze force are acquired through the approximately linear relationship between the pressure gradient and r in the Bi-viscous part. Also,the distribution of the radial velocity and the effect of the sllp coefficient on the radial velocity,pressure gradient and yield surface are discussed.