FILM COOLING EFFECTIVENESS ON A TURBINE BLADE.

The present study examines the importance of curvature on film cooling with two rows of staggered injection holes on both the pressure (concave) and suction (convex) sides of a turbine blade. The results of the experiments indicate that curvature plays an important role in determining film-cooling effectiveness even with multiple-row injection. At low and moderate blowing rates the effectiveness is better on a convex than on a concave surface. At high blowing rates the effectiveness is not greatly influenced by the surface curvature. The influence of curvature, however, is much less than was found with injection through a single row of holes where the individual jet tend to act more independently. In general, the two rows of holes provide higher effectiveness on any of the surfaces than does a single row of holes - certainly at the same blowing rate and, in general, also for the same mass addition per unit span of the blade.