Aerofoil flow separation suppression using dimples

Abstract

AbstractFlow separation is a source of aerodynamic inefficiency, by using vortex generators flow separation can be controlled. This is of particular benefit to flows around bodies which are susceptible to separated flows, such as bodies in ground effect. Previous studies on the ability of dimples to produce vortices for flow mixing concerned heat transfer applications. Experimental measurements using Laser Doppler Anemometry (LDA) were taken in the wake of the Tyrrell026 aerofoil (Rec= 0·5 × 105) with a dimple array machined in the surface. Results for a dimple array of three rows placed forward ofx/c= 0·23 with 1·5Ddimple to dimple spacing, showed significant flow recovery in the wake. The velocity deficit ofu/Uo,min= −0·1 recovered tou/Uo,min = 0·3 with the dimple array and the size of the wake reduced by 50%; at α = 10°,h/c= 0·313. The positive effect of the dimple array on the wing reduced as the wing was brought closer to the ground.