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 micromixing were created in this region, as was the radial jet that drives the large-scale circulation responsible for macromixing. Measurements of instantaneous velocity fields in axial- radial planes showed large cycle-to-cycle variability relative to the mean. The average measurements of the azimuthal vorticity and the Reynolds stresses in the radial-axial plane showed the growth and motion of the tip vortices as they drift away from the blades. Radial and axial spatial derivatives were measured to assess various methods of computing the turbulent viscous dissipation. The small scales were significantly anisotropic at the Reynolds numbers studied.