PIV study of small-scale flow structure around a Rushton turbine

The structure of turbulent motions was measured in a region surrounding the blade tips of a Rushton turbine mixer. The tip vortices responsible for mi cromixing were created in this region, as was the radial jet that drives th e large-scale circulation responsible for macromixing. Measurements of inst antaneous velocity fields in axial- radial planes showed large cycle-to-cyc le variability relative to the mean. The average measurements of the azimut hal vorticity and the Reynolds stresses in the radial-axial plane showed th e growth and motion of the tip vortices as they drift away from the blades. Radial and axial spatial derivatives were measured to assess various metho ds of computing the turbulent viscous dissipation. The small scales were si gnificantly anisotropic at the Reynolds numbers studied.