HYDRODYNAMICS OF SUSPENSIONS AGITATED BY PITCHED-BLADE TURBINE

The complete local fluid velocity vector was determined by three-dimen sional phase-Doppler anemometry, while the velocity vector of suspende d process particles was being measured. Three-dimensional mean and flu ctuating velocities complete Reynolds stresses, 3-D length macroscales , and turbulent energy dissipation rates are presented. The difference in mean and fluctuating velocities of the process particles and the f luid is also examined. Tangential mean flow opposite to the impeller r otation is observed at certain locations just outside and above the im peller, and impeller fluctuations are found also in the inflow to the impeller. The outflow of the impeller exhibits strong spatial variatio ns Length macroscales are essentially independent of impeller speed, b ut vary significantly in the tank. Local energy dissipation rates incr ease with agitation rate raised to power three. Differences in mean an d fluctuating velocities of the two phases are normally small, but inc rease in the discharge flow, where differences in the direction are al so observed.