Effects of water vapor concentration on the film cooling effectiveness of hydrogen gas turbine vane

Film cooling is a promising cooling method for turbine vanes. Inspired by hydrogen gas turbines, this paper investigates the effect of different water vapor volume fraction produced by hydrogen combustion on the film cooling of turbine vanes. Initially, to validate the turbulence model, the PSP experimental method was employed to conduct experiments on single-hole flat plate and vane models without water vapor in the mainstream. Through numerical simulation, laid-back fan-shaped and cylindrical holes in single-hole flat plate models were studied. Compared with different cases with varying water vapor volume fractions in the mainstream, the results show that the film cooling effects for both hole types weakened as the water vapor volume fraction increased. This phenomenon primarily occurs because the constant-pressure specific heat of the mainstream flow increases with higher water vapor concentration. By comparing different definitions of the cooling effectiveness, further verification confirmed that the weakening of the film cooling effect when there was water vapor in the mainstream flow is caused by changes in the constant-pressure specific heat. Numerical simulations were also performed on a real engine turbine vane model. The comparison between cases with and without water vapor showed that, although the film cooling effect of the blade was reduced under higher water vapor concentration, the position and type of holes in the vane also influenced the degree to which the film cooling effect weakened due to water vapor concentration.