Study on the structural and aeroelastic response of long flexible wind turbine blade based on wavelet time-frequency analysis

In order to achieve higher power generation efficiency, modern wind turbine blades are showing a clear trend towards larger size. The length of largest wind turbine blade has already exceeded 140 meters. The structural and aeroelastic response of long flexible wind turbine blade becomes nonlinear because of geometric nonlinearity from the large deformation, which will cause time-frequency vibration characteristics and pose challenges to the safety of wind turbine blade. To study the nonlinear characteristics of structural and aeroelastic response of large wind turbine blade, wavelet time-frequency analysis will be carried out based on the structural response from geometrically exact beam theory model (GEBT) and aeroelastic response from NREL FAST8 for IEA 22MW wind turbine. From the time-frequency analysis result, it can be found that the dominant frequency is changing periodically under large deflection condition, and the nonlinear structural coupling between torsion and deflection exhibit an obvious time-frequency characteristics.