Wave-structure interaction study, in the context of floating wind turbines, by mean of coupled rigid body code and Fluidity CFD software

Master thesis (2017)

Authors

M. Baudino Bessone Electrical Engineering, Mathematics and Computer Science

Contributors

A.C. Viré (supervisor 1)
Faculty
Electrical Engineering, Mathematics and Computer Science
Copyright: © 2017 Matteo Baudino Bessone
Waves CFD Windenergy Wave-structure interaction
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Published Date

30-11-2017

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

Offshore wind energy is a fast-growing sector in the energy industry, and the cost of electricity per kilowatt-hour from offshore wind is decreasing significantly. Until now, offshore wind turbines are mainly installed on bottom-mounted foundations, which are economically feasible in shallow waters. This factor has limited the development of offshore wind to those countries that can benefit from abundant wind resources located in shallow waters. To further extend the wind energy market, floating support structures for wind turbines are being studied and developed. This technology allows harvesting the wind energy resources located in deep waters, avoiding the costly construction and installation of large towers.
A floating support introduces different challenges with respect to a bottom mounted one, not least the fact that the dynamics of the system are significantly different. The aim of this Master thesis is to generate a numerical model that can predict the dynamics of a geometrically simple, two-dimensional floater under the action of a train of regular waves. The wave-structure interaction problem is solved coupling the CFD solver fluidity with a rigid body code developed in Python that numerically solves the equations of motion for a rigid body and uses NURBS to define the geometry of the body. The immersed body method is used to represent the solid body into the fluid.
The results obtained with this approach are then compared with potential flow results, experimental results and results obtained with other CFD solvers available in the literature. Similarities and differences are outlined for the different numerical experiments that have been simulated. In general, good agreement has been found with experimental results and other CFD solvers results. With respect to potential flow theory, good agreement has been found for low-frequency waves, while differences have been noticed for the high-frequency waves.