Numerical Simulation Of Hydrodynamic Characteristics In A Continuous Rotor-Stator Mixer

Although rotor-stator mixers are a particular class of mixers commonly used in many industrial processes, the knowledge of the hydrodynamics in this regime is very limited and deserved to be studied systematically。 Computational fluid dynamics (CFD) can provide an effective method for the simulation of the complicated flow in advanced devices. It can investigate the flow thoroughly on the whole to acquire specific internal information of the mixer, and thus make the predicted results visual.On the basis of the principle of CFD and the theory of the turbulence model, the hydrodynamic characteristics in a continuous rotor-stator mixer (CRS) were numerically simulated by CFD package FLUENT6.2with the SIMPLE algorithm. Further, the influence of different models and methods on the computational parameters was studied. It is found that the rotor-stator interaction analysed by SM method is better than that of the MRF. However, good results can also be obtained when MRF method was introduced to deal with different geometric positions of the rotor-stator. The single liquid simulation system in the high-speed flow is inaccurate, while for the gas-liquid flow, reasonable results are unable to achieve from the simulation with cavitation model. In addition, the distribution of the flow field, the shear rate, the turbulent kinetic energy and the energy dissipation rate are also obtained and approved to be asymmetric from the simulation. Furthermore, each stator slot has a different circulation and re-entrainment pattern as the rotor is passing by the stators, which is in agreement with the literature. The analysis of the fluid field showed the important characterization of the hydrodynamics in the gap between the rotor and the stator.Hydraulic characteristics was calculated and the simulated date was compared with the experimental date based on the flow field simulation. The power number and hydraulic characteristics under the lower flow rate conditions predicted by CFD are in good agreement with experimental, even though the hydraulic characteristics are not suitable with reference to the larger flow rate resulting from the liquid entrainment. The results show that the efficiency of the pumping capacity of the CRS is very low and the power draw is mainly used for high shear mixing.The results are of reference to the optimum design of industrial CRS.