Nonlinear vortex-induced vibration of wind turbine towers: Theory and experimental validation

Vortex-induced vibration (VIV) of wind turbine tower is a common occurrence in practical engineering, significantly impacting the safety and reliability of structure. An effective method is developed to investigate the VIV characteristics of a wind turbine tower with an elastic foundation and a lumped mass. To simulate the fluid-structure interaction, the van der Pol equation is utilized. The equations of motion of wind turbine tower, accounting for aerodynamic force, are established using Hamilton's principle and the assumed mode method, and they are solved by the method of multiple scales. Modal functions of the wind turbine tower are obtained through the finite element method (FEM). The analysis further explores the influences of various parameters on the VIV characteristics of wind turbine tower. The results show that the VIV occurs within the frequency lock-in and multi-value ranges, and the critical wind speeds are mainly determined by the diameters of the segments near the tower top. Moreover, as the lumped mass increases or the foundation stiffness decreases, the occurrence of VIV shifts to lower wind speeds. A wind tunnel experiment of a scaled wind turbine tower model validates the frequency lock-in range of the VIV analysis results.