Effects of Rib Height on Heat Transfer Performance inside a High Aspect Ratio Channel with Inclined Ribs

摘要

Heat transfer and pressure drop experiments were performed in a rectangular high aspect ratio channel (5:1, 45×9 mm) representing a turbine blade trailing edge cooling passage. The oblique ribs were attached to two opposing long side walls and they were intended to function as secondary flow inducers as well as turbulators to improve the heat transfer of the both rib-roughened and Rear (one of the short side walls) walls. The experiments were performed for three different rib heights 1) h = 3mm, 2) h = 2mm and 3) h = 1mm (h-rib height) for two rib arrangements, the transverse (90°) and inclined (60°) ribs, respectively. It was verified that (1) the heat transfer enhancement at the Rear wall was attributed to the rib-induced secondary flow, which carries the cold air from the passage core region towards the Rear wall and enhances the heat transfer appreciably and (2) the heat transfer and pressure drop strongly deteriorate with a decreasing rib height due to the weakening of the rib induced positive effects as a turbulence promoter and secondary flow inducer.