As the application of wind energy moves forward to deep water, different concepts have been put forward. This paper presents a floating vertical axis wind turbine (FVAWT) with a 5 MW Darrieus rotor and a floating horizontal axis wind turbine (FHAWT) with the 5 MW NREL reference wind turbine, both mounted on a semi-submersible. Fully coupled nonlinear time domain simulation tools allow these two different wind turbines to be compared. In the present paper, the FVAWT is modeled by the Simo-Riflex-DMS code while the FHAWT is modeled by Simo-Riflex-Aerodyn, which is a state-of-the-art time domain code for FHAWTs.
The present paper focuses on the comparison between the FVAWT and the FHAWT based on numerical simulations. A series of load cases with combined wave and wind conditions are selected to calculate dynamic responses of the FVAWT and the FHAWT, such as the global motions of the floater in six DOFs, the bending moment of the bottom of the tower and the tension at the fairleads of the mooring lines. Statistical analysis and power spectra are used to analyze the time domain results for this comparison study.
The results give more insight into the difference between the FVAWT and the FHAWT. The disadvantages of the FVAWT have been identified by comparing it with the FHAWT. The comparison provides valuable information for the further study of floating concepts with a vertical axis wind turbine.