Internal Aerodynamics and Heat Transfer Problems Associated to Film Cooling of Gas Turbines

Abstract

Heat transfer and aerodynamic processes within coolant ducts and film emission holes of high temperature gas turbine components have been investigated at ONERA by means of specially devised test rigs affording an adequate similitude of geometrical or aerothermal parameters. Results obtained in tests at steady or transient thermal regime are reported for several points of interest concerning internal coolant circuits: • Heat transfer through multihole parts of turbine airfoils • Aerodynamics of flows within perforated ducts, with special attention to coolant mass flow distribution, to pressure losses and heat transfer coefficients in small or scaled up turbine blade models • Heat transfer over a perforated wall, with mass transfer of the coolant flow through holes of various patterns and pitch-to-diameter ratio. Experimental data are discussed in regard to desired accuracy for the analysis of heat transfer in air-cooled gas turbines, except for the effects of rotation.