关键词: 柔性膜翼, 动力学模态分解, 增升效应, 能量反馈, 流动控制

Abstract: Membrane airfoils can adaptively improve the flow distribution on the surface of the airfoil using aeroelastic effects in the low Reynolds number flow, which offers a novel aerodynamic design concept for smart aerocraft. Hereby, the membrane material is directly applied to the design of airfoil. The numerical calculations for the fluid-structure interaction of the mem-brane airfoil under different angles of attack and length of membrane are conducted. The modal analysis of the flow field of the membrane airfoil is performed based on the dynamics mode decomposition. The results indicated that the mem-brane airfoil show the lift enhancement compared to the rigid airfoil when there exists a lock-in phenomenon between flow and membrane structure. The lift enhancement of the membrane airfoil at angle of attack 16° is 21.74%, which is attribut-ed to the energy feedback of pressure propagation generated by the membrane vibration on the shear layer of the flow. However, the membrane airfoil shows a negative lift enhancement due to the interference of pressure propagation on the upper surface of the airfoil at angle of attack 8°; The lift enhancement of the membrane airfoil with length of membrane of 0.65 times the chord length is 14.22%. The upper surface of the membrane airfoil under this configuration can generate a rightward pressure propagation with a large pressure phase gradient, which allows the flow on the surface can obtain maximum energy from structural vibration feedback. The lift enhancement of the membrane airfoil under this configuration is much greater than other configurations. The proposed methods and research conclusions can provide important theoretical support for active flow control.

Key words: membrane airfoil, dynamic mode decomposition, lift improvement, energy feedback, flow control