Nonlinear Interactions in Wind Turbine Wings

The present Ph.D. project deals with problems concerning large deformations of wind turbines. The aim is to understand nonlinear interactions in the wing response due to geometrical and inertial nonlinearities in the structural response, and due to nonlinear aeroelastic loads. A 2DOF nonlinear structural model of a wind turbine wing is developed. The wing is assumed to be decoupled from the nacelle and tower systems by introducing the nacelle movement as support point motion of the wings. Nonlinear couplings between the structural model and the excitation is analyzed. The excitation have a periodic component with the rotor frequency due to rotation in the boundary layer flow field and tower passage. On top of that a stochastic turbulence component is present in the wind field. To determine loads on wing sections a dynamic stall model for the aeroelastic loads, only including components relevant for wind turbines, has been developed. The nonlinear couplings are analyzed and stochastic stability criteria of the system is to be found. (Jesper Winther Larsen, Søren R.K. Nielsen)