Floating offshore wind turbines (FOWT) have many pros and cons. Among the pros, we can mention the availability of more constant winds and a velocity more suitable to the use of turbines in their optimum efficiency. Among the cons, there are the high costs for installation, mooring lines and the large length of cables required for the energy transmission. In this context, saving structural weights of the floater is, certainly, very welcome.
This paper describes the results of an experimental campaign of a 1/80th scale model FOWT performed in a wave basin. The model consists of a central column connected by pontoons to three equally spaced columns by an angle of 120 degrees. The offset columns are connected to the central tower by guywires. Being structurally light, both pontoons and guywires are subject to the effects of hydroelasticity. In these preliminary tests of the concept, only waves were considered, hence wind effects are not yet addressed. The analysis is based on the first order motions of the FOWT, the tension at the guywires, and the strain at the pontoons.
The results are compared with numerical simulations obtained with the software NK-UTWind, developed at the University of Tokyo, and METiS - USP, currently being developed at the University of São Paulo. Furthermore, the floater motions are also analyzed using the commercial software WAMIT, to provide a better insight on the physics involved by using a different approach to the calculation of hydrodynamic forces.
