Analysis of mode and dynamic stability for wind turbine rotating blades

For large-scale offshore wind turbine rotating blades (NREL 5MW), the theoretical model of vibration due to fluid-structure interaction (FSI) is established, and the basic equations for modal analysis are given. Based on ANSYS WORKBENCH platform, the blade modal characteristics at different rotating speeds are analyzed, and further research on dynamic stability is carried out. The results indicate that the FSI and the blade rotation have a great influence on modal frequencies, which increase with the rotating speed of the blade under FSI. When the frequency of the periodic wind speed is close to the first order natural frequency of the blade, both the maximum flapping displacement and the maximum von Mises stress increase with time, and the vibration divergence appears. At the safe tower clearance of 4.50 m, the critical value of the blade maximum von Mises stress shows a linear upward trend with the increase of the elasticity modulus, which provides technical references for optimization design and safe operation of wind turbine blades.