INVESTIGATION ON FLOW STRUCTURE BEHIND A RING BY IMPLEMENTING OPTICAL PARTICLE CHARACTERIZATIONS.

The flow structure behind circular and elliptical type rings embedded in a cross-flow was investigated experimentally using a particle image velocimetry (PIV), implementing optical particle characterizations. The experiments were performed in a circulating water channel with a test section of 0.2m height × 0.3m width × 1.2m length. The Reynolds number based on the ring hoop cord length is about Re=1200. The velocity fields near the ring hoop were measured using the two-frame cross-correlation PIV method. As a result, the flow near the sharp-edged end of ring hoop ascends fast and showed a conventional vortical structure appeared in a bluff body wake. In the mean velocity field behind a circular ring, there were two large vortices rotating in different directions from each other in the near wake regime caused by the interaction between the central jet flow and the entrained ambient fluids from outer side of ring hoop. [ABSTRACT FROM AUTHOR]