Vortex structures around a flat paddle impeller in a stirred vessel (vortex structures and Reynolds stresses)

Abstract

Vortex structures and Reynolds stresses around a flat paddle in a mixing vessel have been investigated experimentally by 2-component LDV measurement. Phase-averaged mean velocity and Reynolds stresses were obtained to observe relative relation between the vortical structures and momentum transport. Development of Reynolds shear stress can be recognized along with the separated shear layer released from a flat paddle. Discharge and inflow induced by the roll vortex have certain effect on the magnitude of Reynolds shear stress in the separated shear layer. The four quadrant analysis was applied to find turbulent motions contributing production of the Reynolds shear stress. It is seen that most of the Reynolds shear stresses are produced by two turbulent motions, inflow just behind the paddle and large-scale motion passing through behind the paddle vertically. The two turbulent motions are closely associated with the roll vortex.