Session: 05-05-02 Floating System for Renewable Energy II

Paper Number: 79153

79153 - Motion Characteristics of a Floating Model With Moonpools for VAWTs 

This paper describes motion behaviours of a floating body and water regions of moonpools. The floating model to be focused in this study has moonpools and is for offshore wind turbine system with two vertical axis wind turbines. Motion behaviours of water region in moonpools strongly affect on motion characteristics of a floating body itself. Often the effects lead to non-linear motion of the floating body. Beside, when the floating body is a system of vertical axis offshore wind turbines, the system becomes more complicated. However such as moolpools would be able to reduce motion of a floating system by optimizing configurations of moonpools.

This study conducted theoretical calculations and model experiments in a wave tank. Behaviours of moonpools were measured in regular waves and we measured motions of the floating model and tether tensions. Also the study considered effects of VAWT model’s rotation on the motion.

From the results behaviours of moonpools were often non-linear to incident waves and the behaviours affected on motion of the floating model. The experimental results were compared with the calculation results. When non-linearity was strong, the calculations could not reproduce the motion. However we confirmed reduction effects due to the moonpools on the motion. In particular, when motion of moonpools each was opposite phase difference with a piston mode motion, body motion was reduced and steady tensions due to the mean drifting forces were also reduces.

Presenting Author: Tomoki Ikoma Nihon University

Authors:

Katsuhide Fujishima Nihon University
Tomoki Ikoma Nihon University
Yasuhiro Aida Nihon University
Lei Tan Kyushu University
Koichi Masuda Nihon University