Experimental Analysis of the Combining Effects of Endwall Contouring and Film Cooling through Shaped Holes

The present paper shows the results of an experimental investigation on film cooling of a nozzle vane cascade with endwall contouring. In film cooled endwall the front area, especially close to the leading edge, is one of the most critical regions to be cooled; in case of a contoured endwall the thermal protection becomes even more difficult because of the endwall curvature effects. Two geometries with four rows of holes have been considered: a first one with cylindrical holes, the second one with fan-shaped holes. Compared to the former, the latter was expected to improve effectiveness levels. For both configurations tests have been carried out at low speed (M2is = 0.2) and low inlet turbulence intensity level, with coolant mass flow ratio varied within the 0.5-2.5% range. For each injection condition aerodynamic and thermal performance have been determined. Fan shaped holes provided a better thermal coverage compared to cylindrical ones nevertheless an increase in coolant consumption, but the front area cooling remained unsatisfactory.