Flap/Lead-lagAeroelasticStabilityAnalysisforWindTurbineBlades

The nonlinear partial differential equations which govern the coupled flap-lead/lag vibration of wind turbine blades were established based on the Euler-Bernoulli beam theory and the Kelvin-Voigt theory for cohesive elastic composite materials. By decomposing blade displacement into static displacement and dynamic displacement, the nonlinear governing equations were linearized to the linear equations for the dynamic displacement. And then, the characteristic equation of the coupled vibration was obtained. The Galerkin method based on the method of weighted residuals was employed to solve the characteristic equation and analyze the aeroelastic stability of the blades. The influence of wind speed, installation angle, coupling effect and material damping on the aeroelastic stability and nonlinear self- excited oscillation of the blades was discussed. Results show that the coupling effect between flap and lead-lag may be employed to improve the aeroelastic stability of the blades, but very strong coupling effect between them due to the large installation angle may bring about vibration instability.