A thick aerodynamic profile with regions of negative lift slope and possible implications on profiles for wind turbine blades

Abstract

In the high pressure wind tunnel (HochDruckkanal Goettingen [HDG]) of Deutsch–Niederländische Windkanäle—German–Dutch Wind Tunnels (DNW) a 47% thick airfoil-like symmetrical profile was investigated at a high (3 to 12 million) Reynolds number. As an unusual feature, a negative lift slope dcL/dα < 0 close to zero lift has been re-observed under specific circumstances. We describe the findings and offer some explanations using two-dimensional (2D) unsteady, transitional computational fluid dynamics. Possible implications for very thick aerodynamic profiles for use on wind turbine blades are discussed.