An Investigation of Heat Transfer in a Film Cooled Transonic Turbine Cascade: Part I — Steady Heat Transfer

Abstract

Experiments were performed in a transonic cascade wind tunnel to investigate the film effectiveness and heat transfer coefficient on the suction side of a high-turning turbine rotor blade. The coolant scheme consisted of six rows of staggered, discrete cooling holes on and near the leading edge of the blade in a showerhead configuration. Air was cooled in order to match the density ratios found under engine conditions. Six high-frequency heat flux gauges were installed downstream of the cooling holes on the suction side of the blade. Experiments were performed with and without film and the coolant to freestream total pressure ratio was varied from 1.02 to 1.19. In order to simulate real engine flow conditions, the exit Mach number was set to 1.2 and the exit Reynolds number was set to 5×106. The freestream turbulence was approximately 1%. The heat transfer coefficient was found to increase with the addition of film cooling an average of 14% overall and to a maximum of 26% at the first gauge location. The average film cooling effectiveness over the gauge locations was 25%. Both the heat transfer coefficient and the film cooling effectiveness were found to have only a weak dependence upon the coolant to freestream total pressure ratio at the gauge locations used in this study.

Effects of High Intensity, Large-Scale Freestream Combustor Turbulence on Heat Transfer in Transonic Turbine Blades

“…At present, the KEP code data are the only numerical results available for this blade geometry for comparison with experimental measurements. The data for the suction surface location (SS1) without turbulence agree well with the data from Smith, et al (2000). The data from Holmberg (1996) on the pressure surface are much higher than the current data.…”

“…The methodology for determining heat transfer coefficients in the transient flows of the transonic wind tunnel has been described by and in Smith, et al (2000). The following section outlines the methodology.…”

“…Model results compared to data from Holmberg (1996) 82 3.10 Analytical model applied to film-cooled data from Smith, et al (2000) …”

“…The results with low and high turbulence were compared with GE KEP code predictions for the turbine blade and with data from Holmberg (1996) and Smith, et al (2000). The results are presented in Figure 3.7 with measurement uncertainty error bars.…”

Quantifying Thermal Boundary Condition Details Using a Hybrid Heat Flux Gage

“…A similar technique was used by Janssens [16] to quantify the heat transfer coefficient in the ASTM E1354 cone calorimeter [17] using calcium silicate. Heat transfer coefficients have also been measured in high speed flows using heat flux measurements and an energy balance at the gage/device surface to quantify the heat transfer coefficient in a purely convective environment with varying gas temperature [18].…”