Flow Properties of Turbulent Fiber Suspensions in a Stock Pump Impeller  

作　　者：杨炜 张启华 库晓珂 

机构地区：[1]Department of Mechanics, Zhejiang University, Hangzhou 310027, China [2]National Research Center of Pumps-and Pumping System Engineering and Technology, Jiangsu University, Zhenjiang 212013, China [3]Department of Energy and Process Engineering, Norwegian University of Science and Technology, Norway

出　　处：《Chinese Journal of Chemical Engineering》2013年第10期1089-1097,共9页中国化学工程学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China （51309118）, the National Key Technology R＆D Program of the Ministry of Science and Technology of China （2011BAF14B01）, the Postdoctoral Science Foundation of China （2013M531282） and the Doctorate Program of Higher Education of China （20120101110121）.

摘　　要：A numerical method for predicting fiber orientation is presented to explore the flow properties of turbulent fiber suspension flowing through a stock pump impeller. The Fokker-Planck equation is used to describe the distribution of fiber orientation. The effect of flow-fiber coupling is considered by modifying the constitutive mode.The three-dimensional orientation distribution function is formulated and the corresponding equations are solved in terms of second-order and fourth-order orientation tensors. The evolution of fiber orientation, flow velocity and pressure, additional shear stress and normal stress difference are presented. The results show that the evolutions of fiber orientation are different along different streamlines. The velocity and its gradient are large in the concave wall region, while they are very small in the convex wall region. The additional shear stress and normal stress difference are large in the inlet and concave wall regions, and moderate in the mid-region, while they are almost zero in most downstream regions. The non-equilibrium fiber orientation distribution is dominant at the inlet and the concave wall regions. The flow will consume more energy to overcome the additional shearing losses due to fibers at the inlet and the concave wall regions. The change of flow rates has effect on the distribution of additional shear stress and normal stress difference. The flow structure in the inlet and concave wall regions is essential in the resultant rheological properties of the fiber suspension through the stock pump impeller, which will directly affect the flow efficiency of the fiber suspension through the impeller.A numerical method for predicting fiber orientation is presented to explore the flow properties of turbu-lent fiber suspension flowing through a stock pump impeller. The Fokker-Planck equation is used to describe the distribution of fiber orientation. The effect of flow-fiber coupling is considered by modifying the constitutive mode. The three-dimensional orientation distribution function is formulated and the corresponding equations are solved in terms of second-order and fourth-order orientation tensors. The evolution of fiber orientation, flow velocity and pressure, additional shear stress and normal stress difference are presented. The results show that the evolutions of fiber orientation are different along different streamlines. The velocity and its gradient are large in the concave wall region, while they are very small in the convex wall region. The additional shear stress and normal stress difference are large in the inlet and concave wall regions, and moderate in the mid-region, while they are almost zero in most downstream regions. The non-equilibrium fiber orientation distribution is dominant at the inlet and the concave wall regions. The flow will consume more energy to overcome the additional shearing losses due to fibers at the inlet and the concave wall regions. The change of flow rates has effect on the distribution of additional shear stress and normal stress difference. The flow structure in the inlet and concave wall regions is essential in the resultant rheological properties of the fiber suspension through the stock pump impeller, which will directly affect the flow efficiency of the fiber suspension through the impeller.

关 键 词：fiber suspension flow property TURBULENT stock pump impeller numerical simulation 

分 类 号：O357.5[理学—流体力学] TS171[理学—力学]