Heat transfer investigation of the channels with rib turbulators and double-row bleed holes

The detailed heat transfer distributions are measured for the wall of a channel with rib turbulators and double-row bleed holes by transient liquid crystal technique. The effects of the relative positions of rib turbulators and bleed holes, rib angles, channel Reynolds numbers and bleed ratios on heat transfer character are studied. The bleed holes are located near the upstream ribs, equidistant between ribs and near the downstream ribs. Three different rib angles of 60°, 90° and 120° are selected with the holes equidistant between ribs. The channel Reynolds numbers are changed from 30000 to 120000. The bleed ratios are between 0.09 and 0.22. The results show that angled ribs produces higher heat transfer enhancement in conjunction with the effect of bleed holes. The heat transfer characters are best when the bleed holes are located near the upstream ribs in the channels with 90° ribs. The change of bleed holes locations does not change the position of the flow reattachment, but affect the heat transfer distribution and intensity in the region. The average heat transfer enhancement decreases with the increasing of Reynolds number, and slight increases as the bleed ratio increases.