Slack coupled modeling method and dynamic analysis on floating vertical axis wind turbine with helical blades

The working performance of floating vertical axis wind turbine (FVAWT) with helical blades under complex ocean environment is greatly influenced by its dynamic characteristics. For better grasping the dynamic characteristics of helical blade FVAWT, a slack coupled modeling method is proposed in this paper. During the modeling process, the wind turbine system is divided into two configurations, which are connected through the transmission of large overall motion of the blade. Then the reliability of the proposed model is verified by validating the motions of floating foundation and deformations of blade, respectively. Afterwards, the dynamic characteristics of a 5 MW helical blade FVAWT are analyzed. Results show that the amplitude and the equilibrium position of floater motions are influenced by wave loads and wind loads, respectively. And the blade deformation is dominated by aerodynamic frequency components. In addition, the relative angle between orientation of blade section and direction of the wind are sensitive to the helical twist angle, which will lead to the phase difference of aerodynamic loads and the blade deformations between different sections. This study could provide a reasonable mathematical model on design and investigation of the helical blade FVAWT.