Flow phenomena in stirred tanks. Part I. The impeller stream

Flow parameters were measured in a baffled, turbulent, stirred tank agitated by a six‐blade, disk style turbine. The working fluid was air. Mean and fluctuating velocities were measured between the blades of the impeller with a probe mounted on the spinning impeller. Mean velocities, turbulent velocities, one‐dimensional energy spectra, and Eulerian autocorrelation functions were measured in the impeller stream by using the shielded hot‐wire anemometer of Gunkel et al. (1971) which permits the measurement of turbulence parameters in flows of very high turbulence intensity. Reliable impeller pumping capacities were obtained yielding Qrad/ND3 = 1.0 at the impeller periphery. An energy balance on a control volume containing the impeller and the impeller stream showed that the energy put into the tank via the impeller appeared as a net efflux of kinetic energy leaving the control volume. Therefore, most of the energy input to the tank is dissipated in the bulk of the tank.