A master thesis from Aalborg University
Wave Loads and Motions of the Exowave Wave Energy Converter
[Bølgelaster og Bevægelser for Exowave Bølgekraftanlægget]
Author(s)
Term
4. term
Education
Publication year
2024
Submitted on
2024-06-06
Pages
421 pages
Abstract
The purpose of this master thesis is to investigate the accuracy of different approaches for modelling the wave-structure interaction of the floater of the Exowave WEC. The Exowave WEC is a fixed oscillating wave surge converter. The wave-structure interaction is investigated for four different floater geometries. The wave-structure interaction is investigated by examining the wave excitation forces on the floaters in a fixed position. Afterwards, the motions of the floaters due to wave excitation forces are examined. Two experiments are conducted to determine a benchmark for the forces and motions. To describe the wave excitation forces on the floaters, two calculation methods are considered: A method based on the Morison equation and a BEM-based method using NEMOH. The calculation methods are compared to the measured data, showing that both methods can be used to estimate the wave forces adequately. Several numerical models based on the equation of motion are investigated using the calculation methods. A numerical model based on the calculation method using the Morison equation shows a significant deviation for the motions of the floaters compared to the measured motion from the experiment. A BEM-based numerical model with a drag contribution calculated with a relative velocity formulation of the Morison equation shows promising results. It is attempted to improve the BEM-based numerical model by implementing experimentally determined damping coefficients. It is determined that the wave-structure interaction of the floater of the Exowave WEC can be described with an acceptable degree of accuracy using BEM-based numerical models utilising both experimental and BEM-based damping.
Keywords
Documents
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