The application of thin-film technology to measure turbine-vane heat transfer and effectiveness in a film-cooled, engine-simulated environment

Abstract Thin-film technology has been used to measure the heat transfer coefficient and cooling effectiveness over heavily film cooled nozzle guide vanes (NGVs). The measurements were performed in a transonic annular cascade which has a wide operating range and simulates the flow in the gas turbine jet engine. Engine-representative Mach and Reynolds numbers were employed and the upstream free-stream turbulence intensity was 13%. The aerodynamic and thermodynamic characteristics of the coolant flow (momentum flux and density ratio between the coolant and mainstream) have been modelled to represent engine conditions by using a foreign gas mixture of SF 6 and Argon. Engine-level values of heat transfer coefficient and cooling effectiveness have been obtained by correcting for the different molecular (thermal) properties of the gases used in the engine-simulated experiments to those which exist in the true engine environment. This paper presents the best combined heat transfer coefficient and effectiveness data currently available for a fully cooled, three-dimensional NGVs at engine conditions.

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