Visualization experiment on film distribution characteristics of shaped film holes based on thermochromic liquid crystal

Black nylon net coated with thermochromic liquid crystal was set at different locations downstream the film holes. The film distribution of cylindrical hole, water-drop hole and fan-shaped hole were visualized according to the colorful dimensionless temperature images on the nylon net under three blowing ratios of 0.5, 1 and 2.Results show that the stream-wise expansion of film hole weakens the exit mean momentum and intensity of kidney eddies slightly, so the coverage area and thickness of film are increased. The lateral expansion greatly improves the film coverage area and attachment performance by decreasing the intensity of the kidney eddies, exit mean momentum and film thickness and increasing the velocity in the spanwise direction. High blowing ratios make the film lift off the wall and decrease the film coverage aera. In addition, the interaction of jets issued from adjacent holes of film holes row has the effects of pressing the film towards the surface, making the cooling and coverage performance of film holes row better than that of an individual film hole.