连续搅拌槽内假塑性流体停留时间分布的数值模拟

应用计算流体力学商业软件（CFX）模拟了直径0.5m×0.35m的无挡板半球底搅拌槽的流场，计算了流体的停留时间分布(RTD)，研究了转速、流量、全槽平均表观黏度对RTD以及全混釜数（m）的影响。结果表明：基于CFX对假塑性流体连续搅拌槽内RTD的模拟结果与实验基本吻合；低转速下，转速的变化对假塑性流体RTD和(m)值的影响要大于牛顿流体，但当转速达到一定值时，对两流体的RTD和(m)值影响较小；转速较高趋于全混时，流量对假塑性流体及牛顿流体的RTD和(m)值影响较小，且对两流体的影响差别很小；高转速条件下，全槽平均表观黏度的变化对假塑性流体RTD和(m)值的影响较牛顿流体大。

Numerical simulation of the residence time distribution in a continuous stirred tank with a pseudoplastic fluid

Residence time distributions (RTD) of a pseudoplastic fluid have been investigated in a tank of 0.5m×0.35m with a 45° pitched blade impeller. The effects of volume flow, stirring speed and rheological character of material on RTD and the number of completely stirred tank reactors (CSTRs) have been analyzed by using a commercial computational fluid dynamics (CFD) code CFX. The simulated RTD curves showed a good agreement with experimental data. At low stirring speeds, the RTD and the number of CSTRs for a pseudoplastic fluid can be changed more easily by increasing the stirring speed than for a Newtonian fluid. But at high stirring speeds, changes in stirring speed have little impact on the RTD or the number of CSTRs. The influence of volume flow on the RTD of a pseudoplastic fluid is similar to that for a Newtonian fluid. The influence of average apparent viscosity on the RTD and the number of CSTRs is larger for a pseudoplastic fluid than for a Newtonian fluid.