EFFECT OF RIBLETS ON TURBULENCE IN THE WAKE OF AN AIRFOIL
Measurements were made in the near and intermediate wake regions of a NACA 0012 airfoil with three different riblet sizes at a freestream Reynolds number of 2.5 x 105. The riblets tested were a symmetric v-groove type of heights 0.0229, 0.076, and 0.152 mm, respectively. To ensure turbulent flow on the airfoil, a transition strip was applied at 10% of the chord. Wake velocity profiles and turbulence parameters were measured with a temperature compensated hot-film x-probe. Riblet effectiveness was indicated by marked decrease in turbulence levels in the wake. Integration of the wake mean velocity profiles indicated a net reduction in drag of up to 13.3%, which was possibly caused by the combined effect of decreased turbulent shear stress and lower momentum exchange near the surface due to a viscosity-dominated region in the riblet valleys.
AIAA J, v 29 n 11, Nov 1991, p 1769 [2 p, 7 ref, 5 tab, 1 fig]
Caram, J M
Old TRIS Terms:
Marine Transportation; Vehicles and Equipment
British Maritime Technology
Aug 14 1995 12:00AM