Nonlinear aeroelastic response of an airfoil

The authors investigate nonlinear aeroelastic behavior and, in particular, examine nonlinear dynamic response characteristics. Measurements derived from wind-tunnel experiments and predictions derived from an analytical model are presented for a wing section mounted to permit two-degree-of-freedom pitch and plunge response. Nonlinear structural behavior is introduced in the experiments by using a unique model support system designed to permit prescribed nonlinear stiffness characteristics. Aerodynamic nonlinearities, such as those introduced by stall conditions, are examined as well. Results from tailored experiments are presented which explore pathological nonlinear responses such as limit-cycle oscillations and internal resonances induced by spring-hardening and aerodynamic stall nonlinearities. (Author)