LASER-DOPPLER VELOCIMETRY IN AGITATED VESSELS - EFFECT OF CONTINUOUS LIQUID STREAM ON FLOW PATTERNS

Liquid velocities were measured by laser Doppler velocimetry for a sta ndard Rushton turbine and an axial-flow Mixel TT agitator, with a stre am of liquid, having a volumetric flowrate such that the residence tim e was approximately 1/10 of the mixing time, being fed continuously in the agitated vessel. Measurements taken in the feeding-tube plane sho wed a major disruption of the flow pattern, especially of axial veloci ties, due to the continuous liquid stream. The incoming liquid jet com bined with the stream discharged by the impeller in a complex 3-D way; however, the disruption of the flow gradually attenuated, and measure ments taken in the plane rotated 90 degrees clockwise indicated a flow pattern, with characteristics like velocity magnitudes, turbulence in tensity and energy dissipation, similar to the batch case (with no thr ough flow).