Film cooling sensitivity of laidback fanshape holes to variations in exit configuration and mainstream turbulence intensity

Abstract

Experimental measurements and numerical simulations have been performed to investigate the sensitivity of film cooling of laidback fanshape hole to the variations in hole exit configuration and mainstream turbulence intensity. The measurements are conducted on a flat plate model with low-speed, incompressible mainstream. Film cooling performances of two laidback fanshape hole configurations are measured under four blowing ratios using transient liquid crystal measurement technique which can process the nonuniform initial wall temperature. Hole exit corner shape is changed from sharp corner to round corner to simulate the effect of real manufacturing and/or deposition on the exit configuration of ideal laidback fanshape hole. The lateral film coverage as well as the film cooling effectiveness of laidback fanshape hole with round corner exit are reduced due to the smaller lateral expansion caused by round corner shape, especially under low turbulence condition. Large mainstream turbulence intensity can enhance the lateral diffusion of film jets which is beneficial to film cooing of laidback fanshape hole with round corner under larger blowing ratios. For the heat transfer coefficient distributions of the two film hole configurations, variation in film hole exit configuration has very small influence on both the spatial features and the averaged values under the same mainstream turbulence conditions. However, the variation in mainstream turbulence intensity has notable influences on the heat transfer coefficient distributions for both film hole configurations, because the enhancement effect of film jets on heat transfer and the strength of counter-rotating vortex pair are different between high and low mainstream turbulence conditions. The discharge coefficients of laidback fanshape hole configurations are not sensitive to the variations in hole exit configuration and mainstream turbulence intensity under the same blowing ratio.