Designing Short Term Wave Traces to Assess Wave Power Devices

Pal Schmitt, Lucas Danisch, Paul Lamont-Kane, Bjoern Elsaesser

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    Abstract

    In recent years modern numerical methods have been employed in the design of Wave Energy Converters (WECs), however the high computational costs associated with their use makes it prohibitive to undertake simulations involving statistically relevant numbers of wave cycles. Experimental tests in wave tanks could also be performed more efficiently and economically if short time traces, consisting of only a few wave cycles, could be used to evaluate the hydrodynamic characteristics of a particular device or design modification. Ideally, accurate estimations of device performance could be made utilizing results obtained from investigations with a relatively small number of wave cycles. However the difficulty here is that many WECs, such as the Oscillating Wave Surge Converter (OWSC), exhibit significant non-linearity in their response. Thus it is challenging to make accurate predictions of annual energy yield for a given spectral sea state using short duration realisations of that sea. This is because the non-linear device response to particular phase couplings of sinusoidal components within those time traces might influence the estimate of mean power capture obtained. As a result it is generally accepted that the most appropriate estimate of mean power capture for a sea state be obtained over many hundreds (or thousands) of wave cycles. This ensures that the potential influence of phase locking is negligible in comparison to the predictions made. In this paper, potential methods of providing reasonable estimates of relative variations in device performance using short duration sea states are introduced. The aim of the work is to establish the shortness of sea state required to provide statistically significant estimations of the mean power capture of a particular type of Wave Energy Converter. The results show that carefully selected wave traces can be used to reliably assess variations in power output due to changes in the hydrodynamic design or wave climate. 
    Original languageEnglish
    Title of host publication The Proceedings of the 26th (2016) International Offshore and Polar Engineering Conference
    PublisherInternational Society of Offshore and Polar Engineers (ISOPE)
    Number of pages8
    ISBN (Print)978-1-880653-88-3
    Publication statusPublished - 26 Jun 2016
    EventThe 26th International Ocean and Polar Engineering Conference - Rodos Palace Hotel, Rhodes, Greece
    Duration: 26 Jun 201602 Jul 2016
    Conference number: 26
    http://www.isope.org/conferences/2016

    Conference

    ConferenceThe 26th International Ocean and Polar Engineering Conference
    Abbreviated titleISOPE2016
    CountryGreece
    CityRhodes
    Period26/06/201602/07/2016
    Internet address

    Keywords

    • Sea State; Wave trace; Experimental tank testing; wave parameters; non-linear effects; statistics

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  • Cite this

    Schmitt, P., Danisch, L., Lamont-Kane, P., & Elsaesser, B. (2016). Designing Short Term Wave Traces to Assess Wave Power Devices. In The Proceedings of the 26th (2016) International Offshore and Polar Engineering Conference International Society of Offshore and Polar Engineers (ISOPE).