为改善流动分离造成叶片气动效率降低，基于鸟鹰类翅膀羽毛在大范围流动分离时自适应弹起的特点，在翼型吸力面设置功能类似羽毛的弹片。弹片在未发生大范围流动分离时贴附翼型表面，使原始翼型轮廓发挥作用，并于攻角增大时弹起以改善翼型失速特性。以NREL S809为原始翼型，对不同攻角下多个弹片角度进行了数值计算，并对所得气动参数进行分析。研究表明：在大范围流动分离时，弹片可有效提高升阻比，最高达50%~60%；气流贴附弹片流动至其末端，从而抑制和拖延了涡的发展，进而提高了流场稳定性，使波动更规律且幅度更小；所研究攻角范围内，改善翼型气动性能的最佳弹片角度随攻角呈近似线性变化。

Flow separation is the main factor causing the decreasing of airfoil aerodynamic efficiency.We put attached bionic flexible flap on the front half of airfoil suction surface to simulate bird feathers that have the selfadaptive bounce characteristics to decrease the largescale of flow separation.The flap was compressed and kept at the surface of the airfoil before the leadingedge flow separation occurs,which makes the original airfoil profile work.When the angle of attack increases to be high enough,the flap will unfold from the suction surface naturally and then improves the stall characteristics.To analyze aerodynamic performances,numerical simulation of different angles of flap at different angles of attack has been done on the airfoil NREL S809.The results show that bionic flexible flap can improve the liftdrag ratio up to 50 percent to 60 percent when the large scale of flow separation occurs.The flap delays the development of the separation vortex by forcing the air flow to attach on the flap surface and flow to the end,so as to improve the stability of flow field and reduces the amplitude of aerodynamic parameters fluctuation.The optimal angles of flap approximately linearly vary with the angles of attack,which improves airfoil aerodynamic performance.

TK83

国家自然科学基金（51676131，51176129）；上海市科学技术委员会项目（13DZ2260900）