BOUNDARY LAYER HEAT TRANSFER AND FLUID MECHANICS MEASUREMENTS ON A MILDLY-CURVED CONVEX WALL.

Previous studies have demonstrated that even mild streamwise curvature has a marked effect on turbulence structure, heat transfer, and skin friction. This effect was further investigated in the present experiment where two cases of different radii of convex curvature were tested. An attached fully-turbulent boundary layer, grown on a flat plate was introduced to a constant radius of curvature convex wall followed by a flat recovery wall. The strength of curvature, the ratio of boundary layer thickness to radius of curvature, delta /R, was 0. 013 and 0. 03 for the two cases. Both cases were taken with the same test wall, bent to two radii of curvature and the same curvature entry conditions. In the curve, Stanton numbers and skin friction were reduced by 10% and 20% below flat plate values for delta /R equals 0. 013 and 0. 03, respectively. Recovery was slow. Turbulent Prandtl numbers were increased by 20-25% returning rapidly to flat-wall values on the recovery wall. Shear stress profiles responded quickly to curvature, reducing to about 65% of the upstream flat plate values for delta /R equals 0. 03.