改进型INTER-MIG搅拌槽内固液悬浮特性的数值模拟

应用CFD软件Fluent 12.0和并行计算机工作站对双层改进型INTER-MIG桨式搅拌槽内的固液悬浮特性、临界离底悬浮转速及功率消耗进行数值模拟，分析了在固体体积分数as=30%下，转速n、桨叶离底距离C1和桨间距C2等因素对搅拌槽内颗粒悬浮特性的影响. 结果表明，在一定的转速和桨径下，改变C1和C2会改变流场的局部结构，选取适合的C1和C2可使固液混合更均匀，有利于颗粒悬浮和整个搅拌槽传质传热的进行. 最佳桨叶离底高度与槽径比为0.36，最佳桨叶间距与槽径比为0.44；在该最佳工况下临界离底悬浮转速Njs=118.3 r/min；得到既能达到完全离底悬浮、又能使搅拌功耗最小的最佳转速为n=124 r/min.

Numerical Simulation of Solid-Liquid Suspension Characteristics in a Stirred Tank with Improved INTER-MIG Impeller

The solid-liquid suspension characteristics, critical suspension speed of impeller and power consumption of a stirred tank with dual improved INTER-MIG impeller were numerically simulated with the software Fluent 12.0 on a parallel computer workstation. The effects of rotation speed (n), impeller off-bottom clearance height (C1) and spacing between impellers (C2) on particles suspension characteristics in the stirred tank were analyzed under the particle volume fraction as at 30%. The results show that at a constant rotation speed and impeller diameter, local structure of flow field changes with C1 and C2, appropriate of C1 and C2 can make solid-liquid mixed more evenly and good for suspension of particles and the mass and heat transfer. The optimal value of C1/D is 0.36, D is the tank diameter, and the optimal value of C2/D 0.44. Under the optimum working conditions, the critical suspension speed of impeller, Njs is 118.3 r/min, and the optimum speed, n, 124 r/min, which ensures the solids just suspended off the bottom and the minimum consumption of power.