Development of the wake of an airfoil with riblets

Tests were conducted on a NACA 0012 airfoil with riblets at a freestream Reynolds number of 2.5 x 105 in an indraft wind tunnel. The riblets used in the investigation were of symmetric v-groove type with the heights of 0.0229, 0.076, and 0.152 mm. Measurements of the mean velocity profiles, turbulence, and integral quantities in the near and intermediate wakes indicated that the growth of the wake of an airfoil with riblets was similar to that of a clean airfoil. It was also observed that even at a distance of 600 momentum thicknesses downstream of the trailing edge wake equilibrium has not been reached for any of the configurations tested; however, riblet effectiveness was indicated by a marked decrease in the level of maximum shear stress, especially for the 0.152 mm riblets.