Experimental and numerical study of radial velocity profiles in chemical stirred tanks

Stirred tanks are widely used in various industrial processes for mixing, and reactions understanding the flow behavior and optimizing the impeller design is crucial for improving mixing efficiency and product quality. This paper investigates the radial velocity profiles near the impeller tip in a baffled stirred tank using experimental measurements and computational fluid dynamics (CFD) simulations. A cylindrical tank with four baffles was used with four impeller types-anchor, counterflow, sawtooth, and Rushton turbine. The simulations utilized the k-omega turbulence model and the Reynolds stress model with a momentum source term to model the impeller. The results indicate that both the models predict the maximum radial velocities accurately compared to experiments capturing the flow behavior near the impeller edge. Double turbine impellers generate localized turbulence around the blade tip, while pitched blade turbines with down-pumping produce high-intensity turbulence zones throughout the tank. CFD velocity vector plots provide further insight into discharge flows and circulation patterns. The proposed momentum source term approach aligned closely with experimental data and performed better than multiple reference frame methods.