Heat transfer investigation of the channels with 90° rib turbulators and double-row bleed holes

The detailed heat transfer distributions of the wall with bleed holes in a channel with 90° rib turbulators and double-row bleed holes were measured by using transient liquid crystal technique. The effects of the relative positions of rib turbulators and bleed holes, channel Reynolds numbers and bleed ratios on heat transfer characteristics were studied. The results show that: the heat transfer distributions are affected by the combined effect of the flow separation, reattachment and bleeding;the heat transfer characteristics for the bleed holes near the upstream ribs are best because of the heat transfer improvement in backflow region and heat transfer enhancement in reattachment region by bleed effect. For the case of the bleed holes near the downstream ribs, the heat transfer characteristics turn worse since higher heat transfer regions behind the holes are confined by ribs;the change of bleed hole location do not modify 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 growing Reynolds number, and slightly increases with the increase of bleed ratio.