An experimental investigation of film cooling effectiveness for slots of various exit geometries

The effect different slot geometries have on film effectiveness in the vicinity of slot breakout region is studied. Four different slot lip thickness to height ratios (t/s) and three different slot width to height ratios (w/s) are tested over a blowing ratio range of 0 to 1.3. All geometries are tested at a constant density ratio of 1.4. Slot surface film effectiveness measurements are made over a range of downstream surface distance to slot ratios of 0 to 15. Five different density ratios, spanning the typical engine operating range, are tested for one geometry to determine the effect of density ratio on film effectiveness. The results show that film effectiveness is highly sensitive to t/s but not significantly sensitive to either w/s or density ratio, and that an optimum injection angle of 8.5 deg exists for nondimensionalized downstream distance values less than 60.