Numerical modeling and analysis of a hybrid-spar floating wind turbine

In this paper, numerical modeling and analysis of a hybrid-spar floating wind turbine is presented. The hybrid-spar consists of steel at the upper part and precast prestressed concrete at the lower part. Such a configuration is referred to as a hybrid-spar in this paper. The hybrid spar was successfully installed offshore of Kabashima island, Goto city, Nagasaki prefecture, Japan, on Oct. 18, 2013 (see Utsunomiya et al., 2015, "Design and Installation of a Hybrid-Spar Floating Wind Turbine Platform," ASME Paper No. OMAE2015-41544 for details). In this paper, some details on numerical modeling of the hybrid-spar for design load analysis are presented. Then, the validation of the numerical analysis model is presented for a full-scale hybrid-spar model with 2-MW wind turbine. The comparison has been made for the natural periods and the response during rated power production test. Basically, both comparisons have shown good agreement between the measured values and the simulation, showing reliability of the developed code and the numerical model.