Lift enhancement mechanism study of the airfoil with a dielectric elastic membrane skin

Lift enhancement mechanism of an airfoil with the dielectric elastic membrane skin is studied numerically for smart flow control. The flexible membrane is made of dielectric highly elastic polymer material. Such kind of material can deform and oscillate under the prescribed electric potential difference. The dynamic modeling of the dielectric elastic structure is established to describe the electromechanical behaviors. A high-fidelity aero-electromagnetic-structural coupling model is proposed and verified based on CFD/CSD coupling technique. The aerodynamic characteristics of the airfoil with the dielectric elastic membrane skin is analyzed at various angles of attack. The results show that the lift coefficient of the airfoil is 12.33% higher than that of the rigid airfoil at AOA=14°. The effects of coupling oscillation and applied voltages on the aerodynamic performance of the airfoil are emphasized. In the nonlinear coupling, the high-order lock-in frequency plays a significant role in lift enhancement. The lift coefficient is greatly improved when the second-order frequency lock-in occurs and the second-order lock-in frequency is no less than the second-order fundamental frequency of the flow past the rigid airfoil. The corresponding flow pattern is characterized with the formation and maintain of the vortices with similar scale.