Aeroelastic simulations of a large horizontal-axis wind tubine

With the floating frame of reference used to represent the entire motion of the flexible bodies, in which the rigid body motion is represented by the motion of the floating frames and the elastic motion is represented by mode shapes, the governing equations of the multi-body system which considers aeroelastic effects are derived using the first class Lagrange equations, where the algebraic equations are composed of point and vector constraint equations derived from revolute joints and motion joints. The resulting differential-algebraic equations are transformed to algebraic equations using Taylor predictor and BDF (Backward differential formula) Corrector. The nonlinear algebraic equations are solved using Broyden method, then a multi-body numerical method is established. The NH1500 wind turbine is built using the previous method, where the nacelle and hub are considered rigid, the blades and tower are considered flexible. A motion joint is added to represent the transmission chain between the nacelle and the hub. Unsteady aerodynamic loads are calculated by free vortex wake method. With the previous multi-body methods and free vortex wake method, the aeroelastic responses of the wind turbine system are numerically solved in time domain. The results show the wind shear effect leads to the vibration of the blade, and flexibility of the tower increases the responses of the blade. ©, 2015, Nanjing University of Aeronautics an Astronautics. All right reserved.