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Power extraction in regular and random waves from an OWC in hybrid wind-wave energy systems

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posted on 30.09.2019, 13:55 authored by Simone Michele, Emiliano RenziEmiliano Renzi, Carlos Perez-Collazo, Deborah Greaves, Gregorio Iglesias
A mathematical model is developed to analyse the hydrodynamics of a novel oscillating water column (OWC) in a hybrid wind-wave energy system. The OWC has a coaxial cylindrical structure in which the internal cylinder represents the mono-pile of an offshore wind turbine while the external cylinder has a skirt whose scope is to guide the wave energy flux inside the chamber. This layout is not casual, but consistent with the current approach to harnessing wave energy through hybrid systems. The device shape is rather complex and the boundary value problem is solved by applying the matchingmethod of eigenfunctions. Within the framework of a linearised theory, we model the turbine damping effects by assuming the airflow to be proportional to the air chamber pressure. Consequently, the velocity potential can be decomposed into radiation and diffraction problems. We study the effects of both skirt and internal radius dimensions on the power extraction efficiency for monochromatic and random waves. We show that the skirt has strong effects on the global behaviour, while the internal cylinder affects the values of the sloshing eigenfrequencies. Finally, we validate the analytical model with laboratory data and show a good agreement between analytical and experimental results.

Funding

Royal Society - CNR International Fellowship (Grant NF170771)

History

School

  • Science

Department

  • Mathematical Sciences

Published in

Ocean Engineering

Volume

191

Publisher

Elsevier

Version

AM (Accepted Manuscript)

Rights holder

© Elsevier Ltd

Publisher statement

This paper was accepted for publication in the journal Ocean Engineering and the definitive published version is available at https://doi.org/10.1016/j.oceaneng.2019.106519.

Acceptance date

29/09/2019

Publication date

2019-10-03

Copyright date

2019

ISSN

0029-8018

Language

en

Depositor

Dr Emiliano Renzi

Article number

106519

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