Preliminary study on the aerodynamic characteristics of an adaptive reconfigurable airfoil

A balloon-type airfoil, which has the classic airfoil shape but is full of air is designed in this paper. When the angle of attack changes, the pressure distribution on the airfoil surface will correspondingly be changed: the airfoil surface where the pressure is high will be pushed toward the inside of the airfoil resulting in the reduced curvature of this part of the airfoil and even a concave surface formed, but on the other hand, the curvature of the airfoil surface where the pressure is low will be increased. The initial shape of this adaptive reconfigurable airfoil used in this paper is NACA0012. As the forces acting on the airfoil surface should be in balance, a force balance equation is established at first. Then, the surface curvature of the airfoil as well as its shape can thereby be predicted. The flow field and the pressure distribution over the surface of the deformed airfoil can be simulated by use of the variational finite element method. In this paper, the pressure distribution over this adaptive airfoil as well as its corresponding shape under different incoming flows at angles of attack from −14° to 14° has been studied. At last, the XFoil software is used to calculate the coefficient of lift and drag and lift-to-drag ratio of the deformed airfoil. It has been found that this adaptive reconfigurable airfoil can automatically change its shape according to the pressure distribution over its surface and achieve better aerodynamic performance than NACA0012 airfoil in a wide range of application.