Effect of the Injection Angle on the Leading Edge Film Cooling of a Rotating Turbine Blade

Experimental investigations were performed to study the effect of the injection angle of cylindrical holes on the leading edge region film cooling of a turbine blade under rotating conditions based on stroboscopic imaging technique and thermochromic liquid crystal. The Reynolds number was 6.3378×10⁴ at the leading edge. Turbine speed was 574 r/min and the rotating number was 0.0018. The average blowing ratio ranging from 0.5 to 1.25. N₂ was used as the coolant to achieve a density ratio of 1.04. Results show that the span-wise average film cooling effectiveness monotonously increases as the blowing ratio increases with the best blowing ratio M = 1.25. At each blowing ratio, the α = 30° case always yields the highest average film cooling effectiveness in the region of -4:3 < X=D < 3. When M = 0.5, 0.75 and 1.0, the area average film cooling effectiveness decreases as the injection angle increases. When M = 1.25, the area average film cooling effectiveness first decreases and then increases slightly as the injection angle increases.