Experimental and Numerical Study of a Towing Test for a Barge-Type Floating Offshore Wind Turbine

Several experimental and numerical studies have been conducted on the towing behavior of floating offshore wind turbines (FOWTs); however, these studies mainly focus on tension-leg platform (TLP) and semi-submersible designs with cylindrical features. The University of Maine’s VolturnUS+ concept is a cruciform-shaped barge-type FOWT with distinctive hydrodynamic properties that have not been characterized in previous research. This study presents basin-scale experiments that characterize the hydrodynamic drag properties of the VolturnUS+ platform, as well as observing the motion behavior of the platform and added resistance during towing in calm water and waves. The towing experiments are conducted in two towing configurations, with differing platform orientations and towline designs. The basin experiments are supplemented with a numerical study using computational fluid dynamic (CFD) simulations to explore flow-induced motion (FIM) on the platform during towing. In both the experiments and the CFD simulations, it was determined that the towing configuration significantly impacted the drag and motion characteristics of the platform, with the cruciform shape producing FIM phenomena. Observations from the towing tests confirmed the feasibility of towing the VolturnUS+ platform in the two orientations. The results and observations developed from the experimental and numerical towing studies will be used to inform numerical models for planning towing operations, as well as develop informed recommendations for towing similar cruciform-shaped structures in the future.