Optimizing Power Generation of a Bottomraised Oscillating Surge Wave Energy Converter Using a Theoretical Model: Paper No. 2202

N. Nguyen, J. Davis, K. Thiagarajan, Nathan Tom, C. Burge

Research output: Contribution to conferencePaper

Abstract

Preliminary sizing of an oscillating surge wave energy converter (OSWEC) is an iterative process that relies on knowledge of the relevant hydrodynamic coefficients for a given geometry. Often, the complex definition of the device geometry requires coefficients to be obtained through experiments or numerical boundary element solvers such as WAMIT. These techniques demand significant user and computational effort, therefore inhibiting the fine scale parametrization of object dimensions. In this study, a theoretical model, originally presented in Michele et al. (2016), is developed and demonstrated to efficiently optimize the power production for an OSWEC device (subjected to certain environmental conditions) with variations in device widths, heights, and distances from the seabed. Assuming negligible device thickness, the OSWEC motions are modelled as a bottom-raised two-dimensional flap in regular waves using potential flow theory formulated in elliptical coordinates. The solutions to this diffraction-radiation problem are obtained using Mathieu functions with appropriate boundary conditions. The resulting potentials are then used to derive frequency-dependent expressions for the added mass and radiation damping coefficients, along with wave excitation magnitude in surge, pitch, and coupled surge-pitch motions. Good agreement in hydrodynamic coefficient curves is shown between the theoretical model and the numerical results obtained from the boundary element-based program WAMIT. The theoretical model is then employed to maximize the time-averaged output power while maintaining or reducing the hinge reaction force, with variations in device dimensions, wave frequency and amplitude.
Original languageAmerican English
Number of pages10
StatePublished - 2021
EventEuropean Wave and Tidal Energy Conference (EWTEC 2021) -
Duration: 5 Sep 20219 Sep 2021

Conference

ConferenceEuropean Wave and Tidal Energy Conference (EWTEC 2021)
Period5/09/219/09/21

Bibliographical note

See NREL/CP-5700-79929 for preprint

NREL Publication Number

  • NREL/CP-5700-81756

Keywords

  • ACE
  • added moment of inertia
  • hydrodynamic coefficients
  • OSWEC
  • power production
  • wave energy converter
  • wave excitation
  • wave radiation damping

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