关键词：翼型；攻角；长宽比；非对称流动；岔流
摘 要：The purpose of this project is to is to investigate the possibility of exploiting the flexibility inherent to micro air vehicle structures to create small-amplitude oscillations that delay stall and increase lift. Initially two-dimensional rigid airfoils undergoing small amplitude plunging oscillations are considered, this is then expanded to finite wings and finally flexible wings. For the 2D airfoil case two mechanisms of lift generation are identified: deflected jets for pre-stall angles of attack and convected leading- edge vortices for post-stall angles of attack. For rigid airfoils plunging with small-amplitude, two mechanisms of lift enhancement have been identified: deflected jets and convected LEVs. For finite wings oscillating at post-stall incidence, similar lift-enhancing convected LEVs are observed, however the flow field is more complicated. For oscillating flexible wings appropriate spanwise flexibility can significantly enhance lift performance. In terms of the flow field, the rigid wing exhibits weak vortical structures near the leading-edge, which are essentially the three-dimensional version of the LEV dipole observed for flat plate airfoils. Conversely the flexible wing exhibits a strong convected LEV, strong tip vortex and thus high lift.