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A Low Order Coupled Modelling Approach to the Hydrodynamics of Floating Tidal Energy Converters / JACK HUGHES

Swansea University Author: JACK HUGHES

  • E-Thesis – open access under embargo until: 16th May 2027

DOI (Published version): 10.23889/SUthesis.60075

Abstract

Floating Tidal Energy Converters (FTECs) can be desirable over fixed foundation al-ternatives for their accessibility and relative ease of deployment and decommissioning, although highly energetic and harsher environmental loading near the sea surface, inter-actions with mooring lines and platform m...

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Published: Swansea 2022
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Williams, Alison J. ; Masters, Ian
URI: https://cronfa.swan.ac.uk/Record/cronfa60075
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Abstract: Floating Tidal Energy Converters (FTECs) can be desirable over fixed foundation al-ternatives for their accessibility and relative ease of deployment and decommissioning, although highly energetic and harsher environmental loading near the sea surface, inter-actions with mooring lines and platform motion are additional complexities that must be considered. Despite a rising number of FTEC developers, computationally efficient open-source modelling tools remain few and far between. Computational fluid dynamics has been used, but with associated computational overhead. Therefore, an approach for mod-elling the operational system dynamics of FTECs is presented in this thesis and validated against physical modelling of the Sustainable Marine Energy FTEC device, PLAT-I. The coupled model utilises extensively validated, open-source, low order modelling codes from the wave energy sector for the floating platform hydrodynamics. This is extended to the modelling of FTECs with a modification allowing uniform or transient tidal currents and loading to be modelled via a drag coefficient approximation, which accounts for motions of the platform relative to the fluid. Operational turbine thrust and torque loads are solved using Blade Element Momentum Theory, with system interactions handled using multi-body dynamics. The ability to model coupled FTEC system in transient conditions in rela-tively short time and standard desktop configuration sets this approach out amongst others, which is demonstrated in a range of conditions and device scales. Firstly, tank-scale testing is simulated and agreement with platform motions was generally found to be within 20%over multiple wave climates and directions, including waves on the beam perpendicular to the dominant current direction. Then simulations are compared against motion data mea-sured in-situ at full-scale device testing, where the transient current approach is utilised and demonstrates the ability to model less controlled conditions. Using the presented re-search as a starting point, suggestions of future research routes are discussed with the intention of extending the application of the model to different FTEC designs and opera-tional environments, thus becoming a useful tool in commercial and academic applications alike.
Keywords: Mechanical engineering, tidal energy, hydrodynamics, CFD
College: College of Engineering