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Effect and optimization of backward hole parameters on film cooling performance by Taguchi method

In recent years, increasing inlet temperature of gas turbines has far exceeded the melting point of the metalmaterials.Filmcoolingtechnologyhaswidelybee nu sedtoprotectgasturbinebladesfromerosionofthehigh - temperature gases. The film cooling performance can be improved by optimization of the hole configurations.Results show that the backward injection hole has a smaller exit momentum and a thinner velocity boundarylayer near the wall compared to the forward hole. For the backward hole, high blowing ratio is beneficial toimprove the film cooling effectiveness. It was found that the overall average film cooling effectiveness for thebackward hole increases by 677% at a blowing ratio of 1.5 compared to that for the forward hole. In addition, the coupling effects of hole length, inclination angle and blowing ratio on the film cooling effectiveness wereinvestigatedbasedontheTaguchimethod.Anewsche me ofthree-factorfour- levelorthogonalcalculationswasdesigned. It is found that the inclination angle has the greatest effect on the film cooling effectiveness of thebackward hole. When the blowing ratio is 2.0, the backward hole with a hole length of 3Dand an inclinationangle of 35° is the optimal cooling hole configuration.

Film cooling ; Taguchi method ; Computational fluid dynamics ; Backward injection ; Gas turbine

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