Study of Turbulent Flow of Film Cooling Holes with Lateral Expanded Exits

Hot wire measurements and flow visualization are presented for studying the turbulent flow field over a flat gas turbine film cooling blade with lateral expanded holes. Three mass flux ratios of jet-to-free stream, M = 0.5, 0.89, 1.5, are tested. The stream wise velocity, the turbulent intensities and the Reynolds shear stress are measured. The effect of the lateral expanded holes on the improvement of the turbulent flow field for film cooling of gas turbines can be analyzed from the measured spatial distributions of the turbulence quantities along the downstream direction and spanwise respectively. An experimental device of producing mist of dry ice (solid CO2) has been developed and applied in visualizing the complex jet-in-crossflow interaction. The flow visualization provides a direct understanding to the effect of the lateral expanded holes.