Flow field investigation of detached turbulators by using PIV

In the present study, experimental flow field investigation behind a detached turbulator in a rectangular channel representing turbine internal cooling duct has been carried out. Flow characteristics of detached turbulators were studied by using PIV for seven clearance ratios and RE number varied from 33k to 60k. Flow characteristics behind a detached turbulator were reported by means of streamlines, normalized axial and radial velocities and vorticity. Secondary flow characterictics such as vortex structure and strength, position related to the rib and rotating direction were compared for different clearance ratios. As turbolator was elevated from the channel wall, transition of vortex structure and displacement of recirculation zone toward rib were noticed. Clearance ratio of b/h=0.14 was the transition clearance ratio for double-vortex structure to triple vortex structure. Triple-vortex structure was clearly seen at the ratio of b/h=0.18. For clearance values above b/h=0.18, flow reattachment on the channel wall was not observed. Furthermore, as clerance ratio increases counter rotating double cell vortex structures approach the rib in the axial direction.