Effects of Inclination Angle, Orientation Angle and Hole Length on Film Cooling Effectiveness of Rectangular Diffusion Holes

[+] Author and Article Information
Dr. Bai-tao An

Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China

Jian-jun Liu

Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China

Si-Jing Zhou

Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China

1Corresponding author.

ASME doi:10.1115/1.4040101 History: Received August 01, 2017; Revised April 27, 2018


Film-cooling effectiveness of rectangular diffusion holes under an inclination angle a=45o, orientation angle ß=45o, and length-to-diameter ratio of L/D=8.5 were, respectively, examined in a flat-plate experimental facility using the PSP technique. Experiments were performed at a density ratio of DR=1.38 and a mainstream turbulence intensity of Tu=3.5%. The semi-circle sidewall rectangular diffusion hole varied at three cross-sectional aspect ratios, i.e., AS=3.4, 4.9, and 6.6. The tested results were compared with the baseline design with an inclination angle a=30o, orientation angle ß=0o, and length-to-diameter ratio L/D=6. A 3D CFD method was employed to analyze the flow field. The experimental results showed that the increased inclination angle converted the bi- or tri- peak effectiveness pattern of the baseline design to a single-peak pattern, weakened the lateral diffusion of coolant, consequently decreased cooling effectiveness obviously. The decreased magnitude amplified with the increase of cross-sectional aspect ratio and blowing ratio. The adding of orientation angle seriously weakened the cooling effectiveness of the baseline design, and the blowing ratio and cross-sectional aspect ratio had almost no effect on overall cooling effectiveness. The elongated hole length provided a uniform distribution of lateral cooling effectiveness, which produced differential effects on the bi- or tri- peak pattern. The elongated hole length decreased the cooling effectiveness on the near hole region, but had less effects on overall cooling effectiveness, except the high blowing ratio.

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