The nose-down pitching moment and the positive aerodynamic damping caused by the dynamic stall effect of airfoils restrict the improvement of aerodynamic performance of aircraft, even might lead to unstable motions of aircraft. The dynamic deformation of leading edge (DDLE) technology, which could be applied to small size airfoils, is able to improve the velocity gradient of airfoil leading edge by real-timely changing the shape of leading edge, and then suppress the dynamic stall effect. The effects of such deformation of leading edge on the unsteady flow caused by airfoil pitching motions are studied by using a method of combining transition shear stress transport (SST) viscosity turbulence model with partitioned hybrid dynamic mesh, then the method of suppressing and delaying dynamic stall effect by deforming the leading edge with small amplitude is obtained, in order to improve the aerodynamic performance of aircraft. The comparison between numerical simulating results of NACA0012 airfoil and wind tunnel test data of dynamic stall effect shows that the numerical method applied can accurately simulate the lift coefficient and the pitching moment coefficient and be used to study the effect of leading edge deformation on the unsteady flow field. The numerical simulation reveals that the drooping deformation of leading edge with different amplitudes at a high angle of attack could suppress the occurrence of flow separation, and then suppress the dynamic stall effect. Exactly, the drooping deformation with small amplitude and high frequency at a large angle of attack would have a more efficient suppression on the dynamic stall effect; the effect of the amplitude of leading edge deformation and the deforming distribution along mean camber line on lift coefficient and pitching motion coefficient is slight.
Received: 14 June 2013
Published: 29 September 2013