The heat transfer distribution on a turbine blade shape has been measured in a linear cascade wind tunnel for turbulence levels between 0.5% and 15%. The measurements were conducted at a low Reynolds number (80,000). This is typical of low pressure turbine stages at high altitude where unpredicted losses, attributed to transition and separation, have been observed. The heat transfer distributions provide insight into the transition and separation behavior. Turbulence levels from 5% to 10% were generated with a passive biplane lattice grid, while turbulence levels from 10% to 15% were generated by an active air-jet grid. As turbulence levels increased, stagnation heat transfer increased and the location of the boundary layer transition advanced toward the leading edge on the suction side of the blade. The stagnation Nu/Re0.5 increased by 18.6% when going from a clean tunnel turbulence of 0.5% to 15% turbulence. The heat transfer was measured using a uniform heat flux liquid crystal technique. At turbulence intensities of 0.5% stream wise streaks of varying heat transfer were recorded on the concave pressure side of the turbine blade characteristic of Görtler vortices. At higher levels of turbulence these streaks disappeared. Turbulence decay rates, along with micro and macro length scales, are reported for both active and passive grid test conditions.

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