CFD SIMULATION MODEL FOR MIXING TANK USING MULTIPLE REFERENCE FRAME (MRF) IMPELLER ROTATION

Abstract

In this work, CFD (Computational Fluid Dynamics) simulations have been conducted to investigate flow behavior of water in fully baffled stirred tank employed with Rushton impeller. The dimension of the inner rotating fluid zones in Multiple Reference Frame (MRF) impeller model plays an important role in accurately predicting the results on numerically based problems. Therefore, the aim of the paper is to develop CFD model, optimizing the dimensions of inner rotating fluid zone for MRF model (which is a numerical algorithm designed for modeling the rotating part i.e., impeller in stirred tank). Standard k–ε turbulence model which is a commonly used algorithm to model the turbulent fluid flow nature in the system is adopted. The velocity profile (radial and tangential velocity) are studied and compared with experimental results of Wu and Patterson (1989) and Rushton et al. (1950).Based on the comparison of correlation coefficient in the predictions of normalized mean velocities, zone 4 having diameter of 0.104 m and height of 0.032 m was found to be optimal for CFD modelling of stirred tank. The global flow parameters such as flow number predicted by CFD matched quite well with the data of Wu and Patterson (1989) and Rushton et al. (1950). The percentage deviation in the pumping number predictions at various radial locations show a percentage deviation less than 15% in comparison with experimental results.