Investigation of Heat Transfer in a Film Cooled Transonic Turbine Cascade: Part II — Unsteady Heat Transfer

This paper reports on an investigation of the heat transfer on the suction side of a transonic film cooled turbine rotor blade in a linear cascade. A shock wave is generated in a shock tube and passes into the cascade upstream of the blade row to simulate the interaction of a shock emerging from the trailing edge of an upstream nozzle guide vane on the downstream rotating blade row. The unsteady heat transfer caused by the shock wave passing over the suction side of the rotor blade is analyzed and compared to predictive models published in the literature. The investigation includes experiments with and without film cooling and a variation of the most relevant physical parameters. From the analysis and the comparison of the unsteady heat flux it is concluded that the heat transfer coefficient is not affected strongly by the passing shock. Most of the unsteady heat transfer is induced by the variation of temperature caused by the shock wave.