Influence of bleed hole location on heat transfer in rectangular channels with ribs

Measurements of endwall heat transfer in the rectangular passage with ribs and bleed holes were made by using transient liquid crystal technique. The effects of bleed hole location on the heat transfer have been investigated. The ranges of the main-flow Reynolds number are 6×10⁴~8×10⁴ and the bleed ratio are 0.3~0.6. The bleed holes were located at 0.25, 0.50 and 0.75 rib distance downstream from the front rib. Detailed distributions show distinctive peaks in heat transfer levels around bleed holes and on rib turbulator tips. In given bleed hole location, heat transfer enhancement factor on the surface with ribs and bleed holes is higher than other surfaces. Changes in hole location do not significantly affect heat transfer enhancement factor on the surface with rib. Heat transfer enhancement factor on the smooth surfaces and the surface with ribs and bleed holes increases while the bleed holes are close to the front rib.