FILM-COOLING WITH COMPOUND ANGLE HOLES - ADIABATIC EFFECTIVENESS

Film cooling effectiveness was studied experimentally in a flat plate test facility with zero pressure gradient using a single row of inclin ed holes, which injected high-density, cryogenically cooled air. Round holes and holes with a diffusing expanded exit were directed laterall y away from the free-stream direction with a compound angle of 60 deg. Comparisons were made with a baseline case of round holes aligned wit h the free stream. The effects of doubling the hole spacing to sh hole diameters for each geometry were also examined. Experiments were perf ormed at a density ratio of 1.6 with a range of blowing ratios from 0. 5 to 2.5 and momentum flux ratios from 0.16 to 3.9. Lateral distributi ons of adiabatic effectiveness results were determined at streamwise d istances from 3 D to 15 D downstream of the injection holes. All hole geometries had similar maximum spatially averaged effectiveness at a l ow momentum flux ratio of I = 0.25, but the round and expanded exit ho les with compound angle had significantly greater effectiveness at lar ger momentum flux ratios. The compound angle holes with expanded exits had a much improved lateral distribution of coolant near the hole for all momentum flux ratios.