Film Cooling on a Flat Surface With a Single Row of Cylindrical Angled Holes: Effect of Discrete Tabs

Abstract

The effect of discrete delta-shaped tabs on the film cooling performance from a row of cylindrical holes is investigated. The holes are inclined at 35° along the streamwise direction. Three tab locations are investigated: (1) tabs placed along the upstream edge of the hole; (b) tab placed along the downstream edge of the hole; and (3) tabs placed along the lateral edges of the hole. Measurements were carried out in a low-speed wind tunnel using the transient liquid crystal technique. The mainstream velocity and free-stream turbulence intensity in the low speed wind tunnel are 8.5 m/s and 6% respectively and the Reynolds number based on hole diameter is 6375. Three blowing ratios of 0.56, 1.13, and 1.7 are tested. Results show that the tab placed upstream of the hole covering the 33% of the hole exit provides the highest film effectiveness compared to other tab locations studied. This is because the jet lift-off in the presence of the tabs is reduced and there is greater lateral spreading of the jet.