Experimental study on film cooling and heat transfer characteristics of a twisted vane with staggered counter-inclined film-hole and laid-back-shaped-hole

The present study first proposes the counter-inclined film-hole with the staggered arrangement applied on the vane leading edge. The film cooling effectiveness (η) distribution of a twisted vane with the new cooling scheme of the leading edge and laid-back-shaped-holes is measured by the pressure Sensitive Paint (PSP) technique in a fan-shaped wind tunnel. The transient Thermochromic Liquid Crystal (TLC) technique is used to measure the heat transfer coefficient (h). The effects of density ratios and mass flow ratios (blowing ratios) are studied. The experiments are carried out at four mass flow ratios 12%, 9%, 8%, and 7.5% and three density ratios 1.0, 1.5, and 2.0. The pressure in the mid-span of the vane is measured to understand the η and h distributions. The results indicate that the increase rate of the span-wise averaged η upstream of the pressure surface is more prominent with the density ratio increasing from 1.0 to 1.5, and the maximum is about 86.9%; whereas increasing the density ratio from 1.5 to 2.0 significantly improves the span-wise averaged η of the suction surface. Increasing mass flow rates of the trailing and leading cavities has positive effects on the η of the whole vane surface except for the leading edge near the end wall at the density ratio 1.5; whereas it only increases the η on the pressure surface at the density ratio 1. Increasing the mass flow ratio of the leading cavity from 7% to 10% increases the h ratio of the whole cane, and it enlarges the high h ratio of leading edge the mid-chord regions at the suction side. The span-wise averaged heat flux ratio in the region between film hole rows at the density ratio 1.5 is lower than that at the density ratio 1.