Experimental investigation of leading edge jet impingement with varying jet geometries and inlet supply conditions for turbine cooling applications.

Jordan, C. Neil.
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Jet impingement is often employed within the leading edge of modern gas turbine airfoils to combat the extreme heat loads incurred within this region. This experimental investigation employs a transient liquid crystal technique to obtain detailed Nusselt number distributions on a concave, cylindrical surface that models the leading edge of a turbine blade. The effect of hole shape, varying edge conditions at the jet orifice, as well as varying inlet crossflow conditions are investigated. Cylindrical and racetrack shaped jets with three inlet and exit conditions are investigated for each jet shape: a square edge, a partially filleted edge, and a fully filleted edge. Results show that racetrack shaped jets generally provide enhanced heat transfer when compared to the cylindrical holes. However, engine designers should be cautious when introducing edge fillets and inlet crossflow, as these modifications generally degrade the heat transfer from the leading edge target surface.

Gas turbine heat transfer., Leading edge impingement., Shaped impinging jets., Liquid crystal thermography.