An experimental investigation of curvature and freestream turbulence effects on heat transfer and fluid mechanics in transitional boundary layer flows

An experimental investigation of the effects of convex curvature and free-stream turbulence on momentum and heat transfer in a boundary layer undergoing natural transition was performed. The unique feature of the test wall was its flexibility to be bent to various radii of curvature. A qualification test was found for a case in which only laminar flow is present throughout the test section. Mild convex curvature (R = 180cm) is shown to delay transition substantially. Bending the test wall to a smaller radius of curvature (90cm) resulted in no further delay of transition. Increasing the free-stream turbulence intensity results in an earlier transition. Cases with both effects present a pronounced dominance of the free-stream turbulence effect over that of convex curvature. Heat transfer rates and temperature profiles are shown to change more slowly after transition than wall shear stress values and velocity profiles.