Effect of Turbulence on the Heat Transfer in a Laminar and Turbulent Boundary Layer Over a Gas Turbine Blade

This paper describes the results of the systematic investigations undertaken to identify the effect of free stream turbulence intensity on the local heat transfer coefficient distribution in the laminar and turbulent boundary layer present over a turbine blade profile in a two-dimensional cascade. The local heat-transfer coefficient was measured under constant heat flux boundary condition. Experiments were conducted at exit Reynolds numbers (based on blade chord) R_c = 2, 4.5 × 10⁵ and at turbulence intensities ε_i up to 21.3 percent. A novel type of turbulence generator was used, with which it was possible to vary the turbulence intensity in the plane of the cascade without changing the distance between the turbulence generator and the cascade and without significantly varying the integral length scale of the turbulence.