Blowing the Top on Parametric Resonance: Relief Valve Control for the Stabilisation of an OWC Spar Buoy

Josh Davidson, Rui P. F. Gomes , Roberto Galeazzi, João C. C. Henriques

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

    Abstract

    An active control method, to suppress the onset of pitch/roll parametric resonance on an oscillating water column (OWC) spar buoy, is proposed in this paper, which utilises a pressure relief valve at the top of the OWC air chamber. The paper examines the hypothesis that by opening the relief valve, to reduce the air chamber pressure difference and to decouple the dynamics of the spar buoy and the OWC within, the natural pitch/roll frequencies of the system will be shifted, allowing parametric resonance to be cancelled when its onset is detected. The paper reports on experiments, performed to test the stated hypothesis, with a small-scale model OWC spar buoy in a wave flume. Two configurations are considered and tested in a range of monochromatic waves (1) fully closed air chamber; (2) fully open chamber. The results partially confirm the hypothesis, demonstrating that the occurrence of parametric resonance observed for certain wave frequencies when the chamber is closed does not occur when the chamber is open. However, the change in the natural pitch/roll frequencies between the two configurations is very small, and parametric resonance occurs in both confurations for waves with twice this frequency.
    Original languageEnglish
    Title of host publicationProceedings of the ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering
    Number of pages10
    VolumeVolume 9: Ocean Renewable Energy
    PublisherThe American Society of Mechanical Engineers (ASME)
    Publication date2020
    Article number OMAE2020-19128
    ISBN (Electronic) 978-0-7918-8441-6
    DOIs
    Publication statusPublished - 2020
    Event39th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2020) - Virtual Conference
    Duration: 3 Aug 20207 Aug 2020

    Conference

    Conference39th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2020)
    LocationVirtual Conference
    Period03/08/202007/08/2020

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