SHEAR STRESSES ON THE WALLS OF AGITATED VESSELS

Characteristics of flow near the walls of baffled vessels equipped with a six blade Rushton type turbine were measured by an electrochemical method. A directionally sensitive probe was used for determination of velocity gradient vector fields. It was found that the flow conditions near the wall could be described by a meridional profile of the friction coefficient. An extensive set of experimental data obtained by the limiting current technique showed that the profile depends on the Reynolds number, on the flow index of the (power-law) fluids and on the d/D simplex. The maximum values of the friction coefficient characterizing flow near the impeller plane can be correlated by a simple relation of the laminar boundary layer type.