Aspects of Vane Film Cooling With High Turbulence: Part II—Adiabatic Effectiveness

A four-vane subsonic cascade was used to investigate the influence of turbulence on vane film cooling distributions. The influence of film injection on vane heat transfer distributions in the presence of high turbulence was examined in part I of this paper. Vane effectiveness distributions were documented in the presence of a low level of turbulence (1 percent) and were used to contrast results taken at a high level (12 percent) of large-scale turbulence. All data were taken at a density ratio of about 1. The three geometries chosen to study included one row and two staggered rows of downstream film cooling on both the suction and pressure surfaces as well as a showerhead array. Turbulence was found to have a moderate influence on pressure surface film cooling, particularly at the lower velocity ratios. The strong pressure gradients on the pressure surface of the vane were also found to alter film cooling distributions substantially. At lower velocity ratios, effectiveness distributions for two staggered rows of holes could be predicted well using data from one row superposed. At higher velocity ratios the two staggered rows produced significantly higher levels of effectiveness than values estimated from single row data superposed. Turbulence was also found to reduce effectiveness levels produced by showerhead film cooling substantially.