Dynamic responses of a 5 MW semi-submersible floating vertical-axis wind turbine: A model test study in the wave basin

Abstract

Floating vertical-axis wind turbines (VAWTs) are potential solutions for capturing wind energy due to their potential to lower the cost of energy. In this study, a floating VAWT concept is proposed for a water depth of 42 m, comprising a 5 MW three-bladed H-rotor and a semi-submersible platform. Dynamic response characteristics of the floating VAWT concept are experimentally investigated in the wave basin with a scale ratio of 1:50. To tackle the Reynolds number scaling effect, a performance-scaled rotor (PSR) was first designed to match the thrust and side forces. After calibrating the wind and wave fields, free decay and white noise tests are conducted to identify the properties of the floating VAWT system. Wind and wave tests were then performed to analyze the dynamic responses of the floating VAWT, including platform motions, tower-base bending moment, and mooring line tensions. The results show that wind loads primarily influence the mean values of these responses, the fluctuations of the tower-base bending moment and mooring tension are dominated by three-times-per-revolution (3P), while wave loads mainly affect the oscillations of platform motions. This study provides a basis for validating a coupled numerical model and contributes to revealing dynamic response characteristics of floating VAWTs.