Mean and Turbulent Velocity Profile Measurements on the Suction Side of a Film Cooled Turbine Vane

Abstract

Boundary layer velocity and turbulence profiles were measured on the suction side of a scaled up, film-cooled turbine vane airfoil. There have been a number of previous studies of the velocity profile on a turbine vane, but few have taken velocity profile data with film cooling, and none have taken such data on the suction side of the vane. Velocity and turbulence profile data were taken at two locations on the suction side of the vane — one at a high curvature region and one further downstream in a low curvature region. Data were collected for high (20%) and low (0.5%) mainstream turbulence conditions. For the upstream, high curvature location, velocity and turbulence profiles were found with and without the showerhead blowing and within and outside of the merged showerhead coolant jet. The data for the low curvature, downstream location was taken with injection from the showerhead alone, a second upstream row of holes alone, and the combination of the two cases. It was found that the presence of an active upstream row of holes thickens the boundary layer and increases urms both within and beyond the extent of the boundary layer. Span-wise variations showed that these effects are strongest within the core of the coolant jets. At the downstream location, the boundary layer velocity profile was most strongly influenced by the row of holes immediately upstream of that location. Finally, turbulence integral length scale data showed the effect of large scale mainstream turbulence penetrating the boundary layer. The increase in turbulence, thickening of the boundary layer, and large scale turbulence all play important roles in row to row coolant interactions and affect the film cooling effectiveness.