Experimental investigation of the cooling effectiveness of a leading-edge showerhead configuration with counter-inclined compound holes under the influence of freestream turbulence

To enhance the film cooling effectiveness of the leading-edge showerhead on turbine vanes, combined compound angle configurations of film holes were incorporated into the cooling structure design. Pressure-sensitive paint (PSP) technology was used to measure the film cooling effectiveness under various momentum flux ratios ranging from 0.09 to 6.04 and the mainstream turbulence intensity ranging from 2.03 %∼23.58 %. The effects of the momentum flux ratio and mainstream turbulence intensity were compared. The results revealed that the effect of the mainstream turbulence intensity on the film cooling effectiveness at the leading-edge was related to the momentum flux ratio. For the vane leading-edge pressure side, the effect of mainstream turbulence intensity on the film cooling effectiveness was related to the momentum flux ratio. Under a low momentum flux ratio, an increase in mainstream turbulence intensity led to a sharp decline in the film cooling effectiveness, resulting in a maximum reduction of 52.5 % in the area-averaged film cooling effectiveness on the pressure side. When the momentum flux ratio was high, the increased mainstream turbulence intensity enhanced the energy dissipation of the cooling jet, thereby improving the film cooling performance in this region, with a maximum increase of 13.8 % in the film cooling effectiveness. As for the vane leading-edge suction side, the film cooling effectiveness decreases with increasing mainstream turbulence intensity, with a maximum reduction of 36.9 %. Moreover, within the varied range of mainstream turbulence intensities and momentum flux ratios studied in this paper, an increase in the film hole compound angle improved the film cooling effectiveness and relieved the degree of reduction in the film cooling effectiveness caused by the film jet blown off. However, for the pressure side, excessively large film hole compound angle did not significantly improve the film cooling effectiveness. In contrast, to ensure good film cooling characteristics, larger compound-angle film holes can be designed on the vane leading-edge suction side, whereas smaller compound-angle film holes can be created on the vane leading-edge pressure side.