Film cooling characteristics on pressure side of rotating turbine blade

Experimental investigations were carried on to indicate the rotating film cooling characteristics in a 1.5 turbine stage. The length of the tested blade in chordwise and spanwise was 124.3 mm and 99 mm respectively with a 4 mm film hole in the middle span oriented 28° to the tangential of the pressure side in streamwise. The mainflow Reynolds number Re_g was 8 × 10⁴. The blowing ratio varied from 0.3 to 3.0. Three rotating number (Rt) of 2.092, 2.324 and 2.448 were focused on. Air and CO₂ worked as coolant to achieve the coolant to mainflow density ratio of 1.03 and 1.57 respectively. Thermo liquid crystal was employed to show the temperature distribution on pressure side surface which was captured by CCD. Results show that the film cooling effectiveness is increased with the blowing ratio rising while it is decreased with the Rt rising. Meanwhile, increasing Rt could lead the film trajectory to deflect more centrifugally. But it deflect less centrifugally with the blowing ratio rising under the same Rt. High density ratio could improve the film cooling effectiveness dramatically.