The Effect of Compound Angle on Nozzle Pressure Side Film Cooling

Abstract

The effect of film cooling hole compound angle on nozzle pressure side film cooling effectiveness was experimentally investigated using a single row of shaped hole injection. The engine operating conditions were simulated in a scaled warm cascade, which was built based on industrial gas turbine nozzle vanes. Local film effectiveness measurements were made using a computerized pressure sensitive paint (PSP) technique. Nitrogen gas was used to simulate cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy. Three separate nozzle test models were fabricated, which have same cooling supply plenum configurations. One of them has a row of shaped hole on the pressure surface without a compound angle. The other two test models have same size film holes at the same location, but one with a 30-degree compound angle in co-flow and the other in counter-flow direction to the cooling supply. Four cooling mass flow ratios (MFR, blowing ratio) were studied for each of the nozzle test models and two-dimensional film effectiveness distributions were measured. Then the film effectiveness distributions were spanwise averaged for comparison. For all three cases, the overall film effectiveness increased with the MFR (or the blowing ratio), but not significantly. Film effectiveness by a compound angle injection is higher compared to those without a compound angle near the injection, further downstream the difference is insignificant.