The switch from diffusive combustion to premixed combustion in a modern gas turbine will change the combustor exit temperature profile to a more uniform one. Hot spot may occur from 10% to 90% vane span. This will directly affect the cooling of the first stage vane especially the endwall region. Cooling characteristics and metal temperature prediction of endwall become critical.
A typical endwall configuration with matched non-dimensional parameters to the engine condition was investigated experimentally in this study. Two endwall cooling arrangements at four different coolant to mainstream mass flow ratios (MFR) were tested in a linear cascade. Detailed measurements of aerodynamic, heat transfer coefficient, adiabatic film cooling effectiveness and overall effectiveness of the endwall were performed. The temperature sensitive paint (TSP) and pressure sensitive paint (PSP) were used to acquire these parameters. The conjugate heat transfer characteristic of endwall with film cooling and impingement cooling was discussed. Besides, the influence of coolant mass flow ratio on conjugate heat transfer of endwall was analyzed. The results suggested that for film only case the overall effectiveness increases with the increase of MFR but for the combination case with both film cooling and impingement cooling the growth slows down. 1D and 2D method for overall effectiveness prediction based on experimental data for separate parameters and correlations were also studied.