Study on the Effect of Crater-and-Twin-Hole Design Structure on the Cooling Performance of Films

Abstract

This study proposes a twin-crater hole design based on contoured-shaped crater to enhance the cooling efficiency of film cooling holes under various blowing ratios. The cooling performance is experimentally explored using Pressure Sensitive Paint (PSP) testing technique, and numerical simulations are employed to analyze the effects of crater depth variation on the flow structure of film cooling over a flat plate model. In this study, after covering the contoured-shaped crater with film cooling holes, a vortex pairs with an opposite direction to the counter-rotating vortex pairs is generated under operational conditions. This vortex pairs promotes the attachment of the cooling film to the wall surface. The cooling performance of the proposed hole design is calculated for crater depths ranging from 0.2D to 1.0D. The twin-crater holes generated by a crater depth of H=0.8D and an inclination angle of 30° produce reverse vortex pairs that effectively suppress the lift-off of the cooling jets.

Keywords: Film cooling effectiveness, Vorticity distribution, PSP measurement, Gas turbine