Experimental study of the dynamic response of a spar buoy floating structure under wind and wave action

Abstract

Floating Wind Turbines (F-WT) represent an important trade-off in terms of wind energy potential and economic feasibility. Among the floating concepts, Spar Buoy (SB) wind turbine is particularly suitable for deep waters. The motion response of such a structure depends on wind, wave and rotor conditions. Nowadays, only a limited number of experimental studies have been conducted on the dynamic response of F-WT even if the recent interest in renewable energies has increased the demand of quality physical model tests to optimize the design of innovative F-WT and to collect reliable and accurate data for further calibration and verification of numerical models. In the present work, the experience gained from the conduction of a 3D physical model experiment performed within the EU-Hydralab IV Integrated Infrastructure Initiative (http://hydralab.eu/) will be described. The objectives of the research activity have been mainly oriented: (i) to investigate the dynamic behavior of a SB floating structure and (ii) to overcome the limitation in the available public domain dataset. Observations of displacements of the floating structure and wave/wind induced tensions at the mooring lines have been carried out. In the present study, a frequency domain analysis is conducted in order to investigate the dynamic effects on the SB under co-directional and misaligned irregular waves/wind loads and extreme conditions. In particular, waves head in two directions, 0\ub0 and 20\ub0, respectively, with reference to the structure. The results show that the dynamic response of the SB wind turbine in coupled wave-wind-induced analyses is influenced by both wave and wind loads effects