Effect of rotation on the leading-edge region film cooling of a twisted turbine blade

An experimental investigation was performed to investigate the effects of the rotation and blowing ratio on the film cooling effectiveness distributions of the leading-edge regions of a twist gas turbine blade using a thermochromic liquid crystal (TLC) technique. The experiments were carried out at three rotating speeds, including 400 r/min (positive incidence angle), 550 r/min (zero incidence angle), and 700 r/min (negative incidence angle). The averaged blowing ratio varied from 0.5 to 1.25. Nitrogen was used as the coolant to ensure that the coolant-to-mainstream density ratio kept at 1.04. The Reynolds number, based on the mainstream velocity of the turbine outlet and the rotor blade chord length, was 60 800. The results show that rotating speed is one of the most critical parameters in determining the film cooling effectiveness distributions on the leading edge. The position of the stagnation line moved from the pressure side (PS) to the suction side (SS) with the increase in rotating speed. Under the same blowing ratio, the area-averaged film cooling effectiveness increases monotonously with the increase in rotating speed. Under the same rotating speed, the area-averaged film cooling effectiveness increases with the increase in blowing ratio.