Choi, Jungho (2004-12). An experimental investigation of turbine blade heat transfer and turbine blade trailing edge cooling. Doctoral Dissertation. Thesis uri icon


  • This experimental study contains two points; part1 ? turbine blade heat transfer

    under low Reynolds number flow conditions, and part 2 ? trailing edge cooling and

    heat transfer. The effect of unsteady wake and free stream turbulence on heat transfer

    and pressure coefficients of a turbine blade was investigated in low Reynolds number

    flows. The experiments were performed on a five blade linear cascade in a low speed

    wind tunnel. A spoked wheel type wake generator and two different turbulence grids

    were employed to generate different levels of the Strouhal number and turbulence

    intensity, respectively. The cascade inlet Reynolds number based on blade chord

    length was varied from 15,700 to 105,000, and the Strouhal number was varied from 0

    to 2.96 by changing the rotating wake passing frequency (rod speed) and cascade inlet

    velocity. A thin foil thermocouple instrumented blade was used to determine the

    surface heat transfer coefficient.

    A liquid crystal technique based on hue value detection was used to measure

    the heat transfer coefficient on a trailing edge film cooling model and internal model of

    a gas turbine blade. It was also used to determine the film effectiveness on the trailing

    edge. For the internal model, Reynolds numbers based on the hydraulic diameter of

    the exit slot and exit velocity were 5,000, 10,000, 20,000, and 30,000 and

    corresponding coolant ? to ? mainstream velocity ratios were 0.3, 0.6, 1.2, and 1.8 for

    the external models, respectively. The experiments were performed at two different

    designs and each design has several different models such as staggered / inline exit,

    straight / tapered entrance, and smooth / rib entrance. The compressed air was used in

    coolant air. A circular turbulence grid was employed to upstream in the wind tunnel

    and square ribs were employed in the inlet chamber to generate turbulence intensity

    externally and internally, respectively.

publication date

  • December 2004