Optimising power take-off of an oscillating wave surge converter using high fidelity numerical simulations

Pal Schmitt, Henrik Asmuth, Bjoern Elsaesser

    Research output: Contribution to journalArticlepeer-review

    15 Citations (Scopus)
    281 Downloads (Pure)

    Abstract

    Oscillating wave surge converters are a promising technology to harvest ocean wave energy in the near shore region. Although research has been going on for many years, the characteristics of the wave action on the structure and especially the phase relation between the driving force and wave quantities like velocity or surface elevation have not been investigated in detail. The main reason for this is the lack of suitable methods. Experimental investigations using tank tests do not give direct access to overall hydrodynamic loads, only damping torque of a power take off system can be measured directly. Non-linear computational fluid dynamics methods have only recently been applied in the research of this type of devices. This paper presents a new metric named wave torque, which is the total hydrodynamic torque minus the still water pitch stiffness at any given angle of rotation. Changes in characteristics of that metric over a wave cycle and for different power take off settings are investigated using computational fluid dynamics methods. Firstly, it is shown that linearised methods cannot predict optimum damping in typical operating states of OWSCs. We then present phase relationships between main kinetic parameters for different damping levels. Although the flap seems to operate close to resonance, as predicted by linear theory, no obvious condition defining optimum damping is found.
    Original languageEnglish
    Pages (from-to)196-208
    Number of pages13
    JournalInternational Journal of Marine Energy
    Volume16
    Early online date25 Jul 2016
    DOIs
    Publication statusPublished - Dec 2016

    Keywords

    • Oscillating wave surge converter; Computational fluid dynamics; Wave excitation; Wave energy converter; Control theory; Resonance; Power take-off

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