双层半圆管盘式涡轮桨搅拌槽气液分散特性的数值模拟

Numerical simulation of gas-liquid flow in a dual CD-6 impeller stirred tank

采用基于气泡聚并和破碎机理的群体平衡(PBM-MUSIG)模型,对双层半圆管盘式涡轮桨搅拌槽内的气液分散特性进行了数值模拟;考察了不同通气量和操作转速下气液搅拌槽内流体流动,局部气含率和气泡尺寸的分布规律。模拟结果表明:通气工况下搅拌槽内的液相流场具有双循环流动形式;采用PBM-MUSIG模型预测的局部气含率分布与文献实验数据吻合较好;搅拌槽内气泡尺寸随转速增加而减小,随气量增加而增大;桨叶排出流区域内气泡尺寸较小,近壁区和循环区内气泡尺寸较大。

The gas dispersion characteristics in a dual CD-6 impeller stirred tank have been numerically simulated using the population balance model（PBM） combined with the multiple size group（MUSIG） model,which is based on the principle of bubble coalescence and breakup.The effects of varying the gas flow rate and rotation speed on the fluid field,local void fraction distribution and bubble size distribution have been investigated.The results show that the liquid flow adopts a dual loop flow pattern under gas dispersion operating conditions.The local void fraction distributions simulated using the PBM-MUSIG model are in good agreement with the experimental data from the literature.Bubble size decreases as the rotation speed increases,and increases as the gas flow rate increases.The bubble size is smaller in the impeller discharge region,and larger in the near-wall and circulation regions.