Computation of Flowfield Around an Airfoil with Leading-Edge Protuberances

The flowfield and the aerodynamic forces on a two-dimensional airfoil with sinusoidal leading-edge protuberances were computed numerically and compared with the baseline NACA 63(4)-021 airfoil. The amplitude and wavelength of the sinusoidal leading edge were 12 and 50% of the mean chord length. The sinusoidal leading-edge airfoil is dominated by the flow around and over the protuberances at all angles of attack, resulting in significant spanwise variation in all flow properties, in contrast to the baseline airfoil. The surface-pressure distribution on the modified airfoil consists of low-pressure pockets in the troughs that are symmetric and periodic at low angles of attack, and evolve into complicated patterns at higher angles. The low-pressure pockets persist to high angles of attack, resulting in the continued increase of lift. The modified airfoil has lower lift and higher drag in the prestall regime. The lift and drag characteristics at high angles of attack, as well as the dependence on Reynolds number, are addressed in this study.