Unsteady aerodynamic characteristics of airfoil with local oscillation at low Reynolds number

The unsteady numerical simulation method based on the dynamic mesh is used to study the effects of skin oscillation at different locations and with different frequencies and amplitudes on the aerodynamic characteristics and flow field structures of the airfoil at low Reynolds number, and reveal the mechanism of lift augmentation and drag reduction. The research shows that the local oscillation of the airfoil surface can improve the aerodynamic characteristics of the airfoil at low Reynolds number. Compared with that of the rigid airfoil, local oscillation of the airfoil surface can improve the lift coefficient, reduce the drag coefficient and improve the lift to drag ratio of the airfoil. Locations of oscillation have significant effects on the aerodynamic characteristics and flow field structures of the airfoil. When the oscillation surface is at the leading edge or the center of the laminar separation bubble, oscillation can control the laminar separation of the airfoil effectively, so the aerodynamic characteristics of the airfoil are improved. Frequencies of oscillation have significant effects on locations of laminar separation and transition of the airfoil. With the increase of the frequency, the aerodynamic characteristics of the airfoil have the optimal value. Compared with the rigid airfoil, oscillation makes the transition move upstream and the viscous drag increased, but makes the equivalent relative thickness of the airfoil decreased and the pressure drag reduced observably. In the range of small amplitudes, with the increase of the amplitude, the unsteady characteristics are more significant and the lift to drag ratio increases.