高レイノルズ数域でのSpar構造物のVIM特性

Abstract

FOWTs, i.e. Floating Offshore Wind Turbines, are recently planned to be set in the offshore, where bottom-mounted type's one is not feasible, to generate natural resource electricity. One of the ways for FOWTs' application is that a wind turbine facility is mounted on a slender column type floater to keep buoyancy and stability in the sea, that is called as Spar type. In this case, the characteristic of VIM, i.e. Vortex Induced Motion, on the column type floater is concerned about to keep mooring safety of the FOWT. Then VIM characteristic on the column type floater was investigated using a huge experimental model in supper critical Reynolds number at the large towing tank in the National Maritime Research Institute, Japan. The results of the experiment were compared with ones of small similar figure models under lower Reynolds number, and the VIM amplitudes against reduced velocity parameter were clearly understood. Using these results the amplitude distribution relating to duration time for the huge experimental model is investigated having the effect on fatigue damage of mooring lines. These unique and precious results on the column type floater have important role for safety assessment on FOWT mooring lines.