Abstract:
In order to improve the cooling effect of a film, the configuration of backward-expanding shoulder arm hole was presented. The cooling characteristics were compared by CFD method for a flat plate with circular hole, expanding hole, original shoulder arm hole, and backward-expanding shoulder arm hole. The spanwise averaged film cooling efficiency was mainly analyzed for all the configurations at 0.5~2.0 blowing ratio.The results show that the flat plate with the backward-expanding shoulder arm hole can improve the spanwise averaged film cooling efficiency. This configuration has better film cooling performance than the other three ones. The performance of the expanding hole configuration is better than that of the original shoulder arm hole one and the circular hole one, and the shoulder arm hole provides slightly better behavior than the circular hole. Based on the comparison between these configurations for the flow field and the film cooling efficiency of cooled wall at 2.0 blowing ratio, the flow field and temperature field of the backward-expanding shoulder arm hole are similar with those of the expanding hole at the center of outlet section downstream. The small holes on both sides of the backward-expanding shoulder arm suppress the kidney-shape vortex at the center of the flow field. This suppression leads to that the adiabatic film cooling efficiency near the center line of the backward-expanding shoulder arm hole is higher than that of the expanding hole. The reliability of the present calculation model was validated by the good agreement between the numerical and the experimental results for the circular hole configuration.