絮凝搅拌器内部流场特性数值模拟

Numerical Simulation on Characteristics of Internal Flow Field in Flocculation Agitator

在气液交界面形态对比和LDV试验验证基础上,基于CFX侵入式实体模型,应用标准k-ε湍流模型对容积为1 L的絮凝搅拌器内部流场特性进行了数值研究.结果表明:下循环区的流体运动速度和速度梯度较大;搅拌强度增加,速度梯度增大;转速对叶轮附近切向速度梯度影响最大,该区域切向速度梯度值与其他区域最大相差两个数量级;下循环区湍流耗散率、湍流动能和涡流黏度较高;在研究转速范围内,转子转速对湍流动能影响相对较大,对涡流黏度影响相对较小.

Based on the gas-liquid interface morphology comparison,LDV test verification and CFX immersed solid model,a numerical study was conducted on the characteristics of internal flow field in a 1 L flocculation agitator by using the standard k-εturbulence model.Results indicated that the velocity and its gradient are higher in the downward recirculating flow region,and the velocity gradient increases with the increase of stirring intensity.The rotational speed has larger influence on the tangential velocity gradient near the impeller,where the tangential velocity gradient is larger than that in other regions by two orders of magnitude.The turbulent dissipation rate,turbulent kinetic energy and eddy viscosity are higher in the downward circulation area.The rotational speed of impeller in the range of investigation has a larger impact on the turbulence kinetic energy,and a relatively small impact on the eddy viscosity.