Experimental Research on the Effect of Hole-Inclined Angle on the Film Cooling Characteristics under High Mainstream Turbulence Intensity

To study the influence of inclined angle on the film cooling characteristics under high mainstream turbulence intensity, cylindrical holes with inclined angles 30° and 60° were studied using the transient liquid crystal measurement technique under high mainstream turbulence intensity (11.82%), and the result was compared with the result under low mainstream turbulence intensity. The results indicate that the film cooling effectiveness decreases with the increase of inclined angle. With the increase of mainstream turbulence intensity, the film cooling effectiveness increases in upstream region and decreases in downstream region, and in addition, the film cooling effectiveness distributes more uniform in the lateral direction. With the increase of blowing ratio, the heat transfer ratio is enhanced obviously for all cylindrical holes. At small blowing ratio, the heat transfer coefficient ratio decreases gradually along the flowing direction. And the heat transfer coefficient ratio has an undulation feature at large blowing ratios. The increase of the inclined angle leads to an enhancement of heat transfer intensity at the same blowing ratio. But the increase of the mainstream turbulence intensity may result in lower heat transfer intensity at the same blowing ratio. With the increase of blowing ratio, the mainstream turbulence intensity-induced differences of the film cooling parameters between two kinds of inclined-angle holes grow under two mainstream turbulence intensities in downstream region, while the influence of mainstream turbulence intensity is more complex in upstream region.