基于VOF法的絮凝搅拌器流场数值模拟

Numerical Simulation of Flow Field in Flocculation Stirrer Based on VOF Method

应用流体体积函数(volume fluid,VOF)法和RNGk-ε湍流模型,对絮凝搅拌器在不同搅拌速度时的流场进行了三维数值模拟。结果表明:VOF法可以较好地模拟气液界面,速度矢量模拟结果可以解释液面下凹现象;不同搅拌速度时的液相体积平均速度梯度模拟结果与搅拌机给定的平均速度梯度值非常接近;搅拌器内液相的局部速度梯度差异显著(可达2～3个数量级,桨叶附近的局部速度梯度最大),然而不同截面的平均速度梯度差异并不显著(1个数量级之内)。

Based on VOF method and RNGk-e turbulence model, the three-dimensional flow fields in a flocculation stirrer for different stirring speeds are numerically simulated. The results show that VOF method is a better method for simulating the liquid-vapor interface, and the interface concave phenomenon could be explained by the velocity vector simulation results. The simulation resluts of volume-average velocity gradient for different stirring speeds ars very close to the given values in stirrer. The difference of local velocity gradients in liquid phase of stirrer are significant （ about 2 ~ 3 orders of magnitude, the maximum velocity gradient presents in the region near the blades）, whereas the difference of cross-sectional average velocity gradient ars not significant （ within an order of magnitude）.