The Influence of Wind Characteristic on Aeroelastic Stability for Wind Turbine Blades

Modern wind turbine blades become larger and larger. Careful analysis in the blade development is needed to avoid unstable vibration of the blade. In this paper, a numerical model is developed for investigating the aeroelastic response of a single wind turbine blade. The structural dynamic model is developed based on the Hamilton variation principle combining with FEM. Each element is a 15 degree-of-freedom (DOF) elastic beam element with five nodes including three translation DOFS, two rotation DOFS and one torsion DOF in each end. And Hodges-Dowell´s partial differential equations are adopted as the basis. A nonlinear aerodynamic analysis for attached flow separated flow and dynamic stall based on a modified B-L model for low mach numbers is incorporated and used to investigate rotor blade section aerodynamic loads. Then, the equations of motion for the nonlinear periodic time variant system are calculated by implicit Newmark scheme. Wind speed in the real wind farm is random. So, the running wind turbine blade will encounter complex situations which can´t be predicted in the designing procedure. In order to find the function of the wind characteristic in the aeroelastic stability analysis, many wind speed signal serials with different frequency are feed into the coupled model. Results are presented and discussed for a paper blade.