EXPERIMENTAL STUDY ON LOCAL SCOUR AT THE BASE OF A MONOPILE OFFSHORE WIND GENERATOR

Abstract

 Regarding the local scour phenomenon at the base of a monopile type offshore wind power generator, although some existing formulas have been proposed, the effect of the countermeasure construction has been still unclear. In this study, we investigated the effect of countermeasure construction and conducted the reproduction of the local scour phenomenon using large-scale experiments and numerical calculations. We conducted the experiment under the condition that waves, current, and both waves and current are existed using 50 cm monopile with a scale of 1/13, then investigated the scuring depth in case that countermeasure construction was installed and not installed. As a result, it was confirmed that the countermeasure construction has a effect to reduce scaring around the monopile. We then conducted the calculation of flow around the monopile using three-dimensional numerical simulation. The computed results were consistent with the measured values, thus the validity of our simulation was confirmed. Although the scouring depth and its mechanism have not been elucidated, it is qualitatively inferred that the scouring was occurred due to the relationship with the local velocity and vorticity.