تاثیرات کوپلینگ انعطاف پذیر استوار توربین های بادی شناور در دریا
Abstract
1- Introduction
2- Theories and methodology
3- Results and discussion
4- Conclusions
References
Abstract
In order to account for rigid-flexible coupling effects of floating offshore wind turbines, a nonlinear rigid-flexible coupled dynamic model is proposed in this paper. The proposed nonlinear coupled model takes the higher-order axial displacements into account, which are usually neglected in the conventional linear dynamic model. Subsequently, investigations on the dynamic differences between the proposed nonlinear dynamic model and the linear one are conducted. The results demonstrate that the stiffness of the turbine blades in the proposed nonlinear dynamic model increases with larger overall motions but that in the linear dynamic model declines with larger overall motions. Deformation of the blades in the nonlinear dynamic model is more reasonable than that in the linear model as well. Additionally, more distinct coupling effects are observed in the proposed nonlinear model than those in the linear model. Finally, it shows that the aerodynamic loads, the structural loads and global dynamic responses of floating offshore wind turbines using the nonlinear dynamic model are slightly smaller than those using the linear dynamic model. In summary, compared with the conventional linear dynamic model, the proposed nonlinear coupling dynamic model is a higher-order dynamic model in consideration of the rigid-flexible coupling effects of floating offshore wind turbines, and accord more perfectly with the engineering facts.
Introduction
In recent years, floating offshore wind turbines (FOWTs) have been receiving increasing attention due to their prominent advantages, such as steadier and stronger wind available resources, lower operational noise, reduced visual pollution and fewer space limitations (Karimirad et al., 2011; Bachynski and Moan, 2012; Pérez-Collazo et al., 2015; Ma et al., 2015). FOWTs are complex rigid-flexible coupled multi-body systems (Namik and Stol, 2010; Wang and Sweetman, 2013; Nejad et al., 2015). Moreover, because the slender blades of an FOWT system typically work at a high rotational speed and are influenced by the motions of the floating platform, rigid-flexible coupled dynamic responses of FOWT systems are more complicated than those of the fixed bottom wind turbines. Rigid-flexible coupled multi-body dynamics have received considerable attentions during the development of modern high-speed airplanes (Shabana, 1997; Bauchau, 2011). In the 1970s, Winfrey (1971) proposed the “kinetoelastodynamics” (KED) method to model the dynamic behaviour of rigid-flexible coupled multi-body systems. In this method, the system is first modelled as a rigid multi-body system to calculate the motion and inertia forces on the system.