Abstract: Large eddy simulations (LES) for mixing process in a stirred tank of 0.476 m diameter with dual Rushton turbines are reported. The computational fluid dynamics (CFD) package FLUENT6.1 was used. The turbulent flow field and mixing time were calculated by using LES with Smagorinsky-Lilly subgrid scale model. The impeller was modeled using the sliding mesh technique. LES results show a better agreement with the mixing experiments than those with standard k-ε model based on Reynolds-averaged Navier-Stokes (RANS) approach. The local curves of tracer response predicted by LES are also in good agreement with the experimental data. The results confirm that LES is a reliable approach for investigations of the unsteady and quasi-periodic behavior of the turbulent flow in stirred tanks.

Key words: 大涡模拟, 计算流体力学, 搅拌反应器, 混合时间, 双层涡轮桨

摘要： 采用计算流体力学(CFD)方法对直径为0.476 m双层涡轮桨搅拌反应器内的流动及混合进行了数值模拟，并实验测试了混合过程。利用大涡模拟（LES）及Smagorinsky-Lilly亚格子模型求解湍流流动与示踪剂传递过程，桨叶区域采用滑移网格技术。研究结果表明，大涡模拟得到的示踪剂响应曲线和混合时间与实验结果吻合良好，其预测精度明显优于基于雷诺平均（Reynolds-averaged Navier-Stokes，RANS）的标准k-ε模型的模拟结果。大涡模拟是研究搅拌反应器内非稳态及周期性湍流流动的有效方法。

关键词: 大涡模拟, 计算流体力学, 搅拌反应器, 混合时间, 双层涡轮桨