Study on Effects of Film Hole Arrangements on Film Cooling and AerodynamicCharacteristics of Turbine Endwall

A numerical study was carried out for the effects of different film hole arrangements on film cooling characteristics of turbine endwall with mid-passage gap leakage. Firstly, the film cooling effectiveness of a gas turbine endwall was measured with PSP method, and the results was adopted for turbulence model validation. Then mesh independence analysis was carried out for the model under study. On this basis, the film cooling and aerodynamic loss characteristics under different film hole arrangements of the endwall with mid-passage gap leakage were studied. The film cooling and aerodynamic characteristics under five different blowing ratios(M=0.5, 1.0, 1.5, 2.0, 2.5)and four film hole arrangements were analyzed in detail. Results show that when the blowing ratio is 0.5, the endwall film cooling effectiveness reaches its maximum value under arrangement A(S=0.065Cax, γ2=-56.6°; S is the distance between second group film holes and mid-passage gap, Cax is the axial chord length of the blade, and γ2 is the compound angles of the second group film holes). With the increase of blowing ratio, the film coolant jets off from the endwall surface, and the film cooling effectiveness near the film hole decreases. Under the four different film hole arrangements, the total pressure loss coefficient in the near wall area decreases with the increase of the blowing ratio. The decrease amplitude under arrangement A is the greatest. The film hole arrangement has little effect on the endwall film cooling under a low blowing ratio(M=0.5). The film cooling effectiveness(S=0.1Cax, γ2=30°)is the highest under arrangement D and a high blowing ratio(M=2.5). © 2023 Xi'an Jiaotong University. All rights reserved.