Film cooling of a contoured endwall nozzle vane through fan-shaped holes

The present paper shows the results of an experimental investigation into a nozzle vane cascade with endwall contouring and film cooling. In a 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 effect. Two film cooling hole geometries with four rows of holes were tested: cylindrical holes and conical expanded holes. Tests were performed at low speed (M2is = 0.2) and low inlet turbulence intensity level, with coolant to main stream mass flow ratio varied within the 0.5–2.5% range. Aerodynamic and thermal performances were evaluated in every injection condition. Compared to cylindrical holes, results showed that shaped film cooling holes generate slightly higher secondary losses and provide a better thermal coverage, at the expense of a higher coolant flow injection.