Examining the Effects of Turbulence on Low-Speed Airfoil Lift Performance

Understanding how turbulence affects lift performance at low Reynolds numbers is important to predicting airfoil behavior in common flight conditions. Flow fields and force data were measured for full-span NACA 0012, Eppler 387, and SD 5060 airfoils at a Reynolds number of 12,000. Data was collected at static angles of attack from -5 to 20 degrees with freestream turbulence intensities of 0.5%, 2.5%, and 7%. Force data was also collected at Reynolds numbers of 30,000 and 60,000 with freestream turbulence intensities of 0.5% and 7%. This allowed for a broader investigation on the effects of turbulence across the low-Reynolds number regime for both symmetric and cambered airfoils. The tested airfoils were designed for laminar flow conditions, but the results of this work suggest that freestream turbulence makes the lift performance of these airfoils more linear, similar to their performance at higher Reynolds numbers.