桨叶式搅拌槽内部流场数值模拟及PIV试验

Numerical simulation and PIV test of internal flow field in paddle stirred tank

对搅拌槽内的混合过程进行了三维数值模拟,采用多重参考系法(MRF)以及标准k-ε模型,分析了搅拌槽内液体的流动情况.为了了解采用的叶轮模型能否有效地搅拌液体,分析了搅拌槽内垂直面和水平面的速度分布情况.运用PIV技术对搅拌槽内的真实流动情况进行了研究和探讨.通过比较搅拌槽液面、叶轮排放区、叶轮流入区以及槽底的速度分布与数值模拟速度分布之间的差异,发现数值模拟和试验所反映的轴向速度增减趋势相同,但最大速度点的差别有所不同:模拟值和试验值在池底基本吻合,在叶轮排放区和流入区分别相差12.8%和14.2%,在池面相差较大.这肯定了数值模拟对试验研究的预测作用,可为搅拌器的选型和设计提供参考.

3-D flow field of mixing process in an agitator tank was simulated by using Multiple Reference Frame （ MRF） and standard k-ε model,and the liquid flow-status in the mixing tank was analyzed. In order to verify that the impellers can mix the liquid effectively,velocity distribution of vertical surface and horizontal surface were studied respectively. Meanwhile,PIV was used to study and discuss the real flow condition in the agitator tank. The experimental data of velocity distribution on agitator tank liquid level, impeller inflow area,impeller discharge area and tank bottom area are contrasted with the simulation results. It is discovered that the axial speed increasing trend obtained from numerical simulation is quite agreement with that of the experiment,while the point of highest speed has some difference： on tank bottom area the two results are consistent,and the highest speed of simulation on impeller discharge and impeller inflow region is lower 12. 8% and 14. 2% than that of experiment respectively,and on tank liquid level the two results are quite different. So the forecast function of the numerical simulation for experimental study was validated. This provides some useful reference for type election and design of agitator.