推进式搅拌混合器内湍流特性研究

Investigation of the Turbulent Flow Characteristic in a Stirred Mixer With Propeller

利用计算流体力学湍流模型和多重参考系法对典型的推进式搅拌混合器内湍流特性进行分析，得到了混合器内时均速度和湍动能的分布特性。研究结果表明，随着半径的增大，时均速度数值先增大后降低，桨叶顶端附近的时均速度较大，与文献试验相吻合；叶轮下端排出区时均速度数值随着轴向位置的增加呈现先增大后急剧下降趋势，在叶轮以上区域沿轴向变化趋于一致；叶轮排出区湍动呈现非均匀性，同一轴向或径向位置各点湍动能最大相差7～9倍。推进式桨叶与45°三叶折叶桨相比具有较好的轴流特性和相对较远传输距离。

The turbulent flow characteristic in a stirred mixer with propeller was predicted based on multi--reference frame by using CFD turbulent model. Some detailed information about the velocity and turbulence kinetic energy was obtained. The simulated results show that the mean velocities increase firstly then decrease as radial position increasing, while the values of mean velocities close to the impeller are larger which were found in good agreement with the experimental results reported in the literature. Though the velocity distributions at different axial position above the stirrer are also much smoother, the values of velocity increase firstly then decrease in the discharged zone. The turbulence in the discharged zone tends to be nonuniform and the magnitude of the turbulent kinetic may have 7-9 times difference at the same axial or radial position. It is priority to select propeller for the axial speed field as main field, long distance transmission compared with traditional typical three-- blade impeller of 45°.