Fluid dynamics and flow patterns in stirred tanks with a turbine impeller

Abstract

Velocity profiles were measured in a stirred tank with a turbine impeller using a three‐dimensional, pitot tube probe. A tangential jet model was used to describe the flow in the region of the impeller, and two‐dimensional potential flow models and a circular jet were used to describe the flow in the rest of the tank. The tangential jet model accurately predicted the measurements from this work and comparable measurements reported in the literature for water and air, for varying impeller diameter and speeds and for different tank diameters. In the rest of the tank a three‐dimensional, low velocity, flow field exists; and the center of circulation is not a true stagnation point. The flow at this point is tangential. The two‐dimensional models only qualitatively described the flow in this region, and a three‐dimensional model would be required. It was experimentally and theoretically confirmed that standard practice of using 10% baffles effectively controls the flow in the tank.