Short Duration Measurements of Heat-Transfer Rate to a Gas Turbine Rotor Blade

Abstract

The paper describes the results of an experimental study of the effect of Mach number, Reynolds number, inlet flow angle, and free-stream turbulence level on heat transfer rate to a gas turbine rotor blade. The measurements were made in the VKI short-duration isentropic light piston tunnel using thin film heat transfer gages painted on a machinable ceramic blade of 80 mm chord and 100 mm height. The tests were performed for three cascade inlet Mach numbers: 0.62, 0.92, 1.15; inlet unit Reynolds number was varied from 0.3 × 107 m−1 to 1.2 × 107 m−1; the inlet flow angle from 30 to 45 deg (for an inlet blade angle of 30 deg); the turbulence level from 0.8 percent to approximately 5 percent. The effect of changing these parameters on boundary layer transition and separation, on leading edge and average heat transfer to the blade was examined. For typical situations, experimental blade heat distributions were compared with boundary layer predictions using a two-equation closure model.