Experimental investigation of rotating single-hole film cooling performance on suction side of a turbine blade

Experimental investigations were carried out to study the rotating film cooling characteristics in a 1.5-stage turbine using stationary thermo liquid crystal method.The length of the test blade in chordwise and spanwise was 124.3 mm and 99 mm respectively with a 4 mm film hole in the middle span oriented 36° to the tangential of the suetion side in streamwise.The mainflow was compressed and heated to bring the turbine to rotate with an inlet Reynolds number Reg of 8×104.Air and CO2 acted as coolant to achieve the coolant to mainflow density ratio of 1.03 and 1.57,respectively.Three rotation numbers of 2.092,2.324 and 2.448 were considered.The blowing ratio varied from 0.3 to 3.0.Results show that on suction side there is an optimum blowing ratio to obtain the best film cooling effectiveness and coverage.Higher density ratio could generate larger film cooling coverage.Rotation is bad for film cooling effectiveness.Meanwhile,the film trajectory deflects centripetally a little due to the horseshoe vortex and rotating effect.