Comparisons on vibration reduction effect of two types of particle dampers for offshore wind turbine structures

Abstract

Offshore wind power (OWP) is developing towards large capacity, high towers, and long blades, which causes offshore wind turbines (OWT) to bear more severe environmental loads and increase the risk of vibration and fatigue. Although dampers can effectively control vibration, they are mostly difficult to apply in practice due to the limited space in the nacelle and tower. To solve this problem, two types of particle dampers with strong robustness and flexible layout characteristics were introduced in this research, and their vibration reduction performance was compared. Firstly, considering the actual spatial layout inside OWT, two types of particle dampers, respectively, called the vibration reduction particle deck (VR-PD) and particle damping-tuned mass damper (PD-TMD), were proposed. Then, the finite-element method (FEM) and discrete-element method (DEM) were both used to establish the coupled FEM-DEM numerical model of OWT structure, and its effectiveness was demonstrated through a classic physical model experiment. Finally, the tuned mass damper (TMD) was installed on the numerical model of OWT structures and compared with two newly proposed dampers for vibration reduction effect under the seven conditions, including modal analysis, impact condition, extreme condition, seismic condition, vibration amplification condition, operation condition, and fatigue condition. It can be shown that VR-PD and PD-TMD can better control the vibration of OWT structures under the condition of large displacement and reduce the maximum displacement by 81.40 % and 81.05 %, respectively, under the vibration amplification condition. Simultaneously, VR-PD and TMD have good vibration reduction effects under operational conditions, which can reduce the root mean square (RMS) value of displacement by 30.1 % and 31.1 %, and the peak displacement by 30.95 % and 23.56 %, respectively. Additionally, VR-PD and TMD are more excellent in increasing the fatigue life of OWT structures.