关键词: 大涡模拟(LES), 计算流体力学(CFD), 搅拌槽, 涡轮桨

Abstract: The single loop hydrodynamic characteristics in a baffled Rushton impeller stirred tank were investigated by using large eddy simulation (LES) method. The dynamic Smagorinsky-Lilly sub-grid scale (SGS) model was used in the simulation and compared with k-e model and experimental data. The results show that the two trailing vortices generated behind the impeller blades move down to the bottom of the tank, the upper one begins to damp at 30o. 800000 non-uniformly distributed grids and 30 impeller revolutions used for statistical analysis can give a more accurate LES prediction. Time-averaged velocities, root mean square velocities and turbulent kinetic energy predicted by the LES approach are in good agreement with the experiment, while the k-e model gives an erroneous estimation. Near the impeller, the flow is highly anisotropic, which is the main reason why the prediction by k-e model is inaccurate. The results confirm that LES is an effective approach for investigation of the complex flow in stirred tanks.

Key words: large eddy simulation, computational fluid dynamics, stirred tank, Rushton impelle