PIV Measurements in Confined Swirling Flows of Polymer Solutions with Vortex Shedding

摘要

Using particle image velocimetry (PIV) system, a ring vortex shedding phenomenon observed in the confined swirling flows of polyacrylamide (PAA) solutions whose concentration was 0.5 wt% was investigated. It was found that the fluid within the ring vortex formed near the rotating disc rotates with semi-rigid body rotation, where the angular velocity of ring votex was about 0.9 times that of the rotating disc. The high shear layer was found to exist at the boundary between the ring vortex and the outer large-scale secondary flow. After the ring vortex was shed, the surrounding large-scale secondary flow rushed into near the rotating axis, so that the strong axial flow was observed near the rotating axis.