Full-Coverage Film Cooling—Part I: Comparison of Heat Transfer Data for Three Injection Angles

Abstract

Wind tunnel experiments were carried out at Stanford between 1971 and 1977 to study the heat transfer characteristics of full-coverage film cooled surfaces with three geometries: normal-, 30 deg slant-, and 30 deg × 45 deg compound-angled injection. A flat full-coverage section and downstream recovery section comprised the heat transfer system. The experimental objectives were to determine, for each geometry, the effects on surface heat flux of injection blowing ratio (M), injection temperature ratio (θ), and upstream initial conditions. Spanwise-averaged Stanton numbers were measured for blowing ratios from 0 to 1.3, and for two values of injection temperature at each blowing ratio. The heat transfer coefficient was defined on the basis of a mainstream-to-wall temperature difference. Initial momentum and enthalpy thickness Reynolds numbers were varied from 500 to about 3000. This paper compares the experimental results for the three injection geometries. In addition, the effects of hole spacing and number of rows of holes were examined.