Assessment of shaped film cooling holes at high density ratios for gas turbine cooling using S-PIV and PSP.

During film-hole cooling, relatively cold air is extracted from the compressor of a gas turbine engine and forced through the turbine airfoils in order to lower their surface temperatures. To investigate the effects of various film cooling hole geometries on film-cooling hole performance, shaped film cooling holes are observed using Stereo-Particle Image Velocimetry (S-PIV). Experiments are performed at various locations where the coolant-to-mainstream interaction is captured using multiple density ratios and blowing ratios. Using S-PIV the three-dimensional flow field is measured and coupled with surface film-cooling effectiveness measurements obtained through a pressure sensitive paint (PSP) technique. Flow vorticity distributions are derived from velocity measurements. Results clearly show that film cooling is enhanced by dispersing coolant from racetrack shaped inlets and incorporating anti-vortex designs within a laidback, fanshaped hole.