Heat transfer and flow phenomena in a swirl chamber simulating turbine blade internal cooling

Heat transfer and fluid mechanics results are given for a swirl chamber whose geometry models an internal passage used to cool the lending edge of a turbine blade. The Reynolds numbers investigated, based on inlet duct characteristics, include values that are the sa,ne as in the application (18,000-19,400). The ratio of absolute air temperature between the inlet and wall of the swirl chamber ranges from 0.62 to 0.86 for the heat transfer measurements. Spatial variations of surface Nusselt numbers along swirl chamber surfaces are measured using infrared thermography in conjunction with thermocouples, energy balances, digital image processing, and in situ calibration procedures. The structure and streamwise development of arrays of Gortler vortex pairs, which develop along concave surfaces, are apparent front Pow visualizations. Overall swirl chamber structure is also described from time-averaged surveys of the circumferential component of velocity total pressure, static pressure, and the circumferential component of vorticity. Important variations of surface Nusselt numbers and time-averaged flow characteristics are present due to arrays of Gortler vortex pairs, especially near each of the two inlets, where Nusselt numbers are highest. Nusselt numbers then decrease and become more spatially uniform along the interior surface of the chamber as the flows advect away from each inlet.