侧进式搅拌器三维流场的数值模拟

Numerical simulation of 3-D flow field in side-entering agitator

现有的侧进式搅拌器设计大都依赖运行经验的积累,精度较差。为此,采用流体力学软件Fluent对具有4台侧进式搅拌器的搅拌槽内流场进行了三维模拟,计算了不同雷诺数下此类搅拌器的功率准数,并得到了功率曲线。采用有限体积法对计算域离散化,在每个网格单元内求解质量守恒方程和动量守恒方程。模拟结果表明,侧近式搅拌器的功率准数在不同的流动区域随雷诺数Re改变而变化的趋势不同,在湍流区NP值保持在0.54左右,在过渡流区域,采用层流与湍流2种方法计算的结果相差不大;搅拌槽内流体流速仅在槽下4个桨叶区附近较大,槽体中部与上部流体流速均较小;流速值小于0.4m/s的区域体积约占槽体总体积的80%。

The existing design of side-entering agitator are mostly based on the accumulation of operating experiences,thus its accuracy is poor.For this reason,the 3-D simulation of flow field in agitating tank with four side-entering agitators is carried out by means of fluid dynamics software Fluent and the power number of this kind of agitator is calculated under different Reynolds numbers,and the power curve is obtained.In addition,the discretization of calculation domain is performed by using finite volumetric method,and the mass conservation equation and momentum conservation equation are obtained within each grid element.The simulation results show that the change tendency of power number of side-entering agitator is different with the change of Reynolds Re in different flow regions.In turbulent flow region,NP value remains around 0.54;in transition region,the calculation results from layer flow and turbulent flow have slight difference.The fluid velocity within agitating tank is relatively big only around the four impellers below the tank,but the fluid velocities in the middle and above the tank are both small.