Flow Fields in Agitated Tanks

The flow fields in agitated tanks with different geometry and impellers have been studied by many researchers. Qualitative and quantitative observations have been reported for the discharge flow from the impeller, the flow near and around impeller and the flow in the bulk of the tank. The flow field is generally affected by impeller and tank geometry, number of blades, liquid height and fluid properties. Most studies of flow fields have been performed for a standard tank geometry. 

In most investigations the discharge flow from a Rushton turbine in a baffled tank is considered, but also the discharge flow from pitched blade turbines, propellers and open flat blade turbines have been studied. The discharge flow patterns for three different impellers are illustrated in Fig 7.7. 

The strong periodicity in the discharge flow velocity near the blade is caused by the trailing vortices shed by the impeller. In these vortices, the circumferential velocity is of the order of the impeller tip velocity, vt, and the 

Vortex System High Discharge Fiow Vortex System 

The Duai Vortex System and High Veiocity Discharge Flow of the Disk Style Turbine 

The Single Vortex and Axial Flow of the Pitched Blade Turbine 

Schematic Two Dimensional View of the Flow Field in the Stirrer Blade Region. S, Stagnation Point 

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In a turbulent flow field, a random flow of eddies is commonly superimposed on the overall average fluid flow. In mixing equipment, the motor provides the power, which turns the impeller. This energy is transferred from the agitator into the largest scales of motion (eddies) of the fluid in the tank. This energy is then transferred (cascaded) from the largest... 

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