The cooling performance of multiple rows of film holes on the suction surface of a turbine blade under rotating conditions

Abstract

In this paper, the experimental results on the cooling performance of multiple rows of holes on the suction surface of a turbine blade were indicated. The effects of hole arrangement, blowing ratio, and rotation on the film cooling performance were analyzed. Four different film hole arrangements were studied. Each blade was modeled with three rows of cylindrical holes with streamwise angle of 45°. The first and the second injection rows were fixed at the position of 12.4% and 17.8% of the streamwise length of the suction surface, respectively. The third injection row was located at streamwise location of either 23.2% or 34%. To investigate the rotation effect, experiments were performed at three rotational speeds of 400 rpm, 600 rpm, and 800 rpm corresponding to the rotational Reynolds number of 3.57 × 105, 5.36 × 105, and 7.15 × 105, respectively. Average blowing ratios of 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0 were tested. Adiabatic film cooling effectiveness was obtained using pressure sensitive paint (PSP) technique. The results showed that inward deflection for the trajectories complicates the superposition principle. Staggered rows of holes can achieve more uniform film coverage and higher film cooling effectiveness. For the case with small array spacing between each adjacent rows, the film cooling area is too concentrated and can achieve better film cooling performance only at a small blowing ratio. The increasing rotational speed slightly weakens the tendency of inward film deflection and increases the film cooling effectiveness at a low blowing ratio.