Aerodynamic Improvements of Airfoils at Low Reynolds Number by Moving Surface Method

Abstract

The moving surface method (Wang Y., et al., J. Jpn. Soc. Aero. Space Sci., Vol. 58, 2010, pp. 239-244, in Japanese) is applied to low Reynolds number flows over thin airfoils as a flow separation control method for further aerodynamic enhancement. The moving surface method is based on Couette Flow-type momentum addition and is expected as a promising means in order to achieve lift enhancement. In order to evaluate aerodynamic effects of the moving surface method at a low Reynolds number, we employed NACA0006, Ishii airfoil, and Owl-like airfoil, and performed two dimensional CFD simulations. The results demonstrate that by applying the moving surface method, the leeward flow separation is successfully suppressed and lift-to-drag ratio is increased, particularly for the Owl-like airfoil. In addition, interestingly, a further drag reduction has been observed by increasing the surface-moving velocity, in which pressure suction at the leading edge is promoted. As a consequence, the maximum lift-to-drag ratio reached 44 (Owl-like airfoil with 9 degrees of attack angle), 2.2 times the case without the moving surface.