International Journal of Naval Architecture and Ocean Engineering

The Society of Naval Architects of Korea (대한조선학회)
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Heaving displacement amplification characteristics of a power buoy in shoaling water with insufficient draft

  • Kweon, Hyuck-Min (Department of Railway Construction and Environmental Engineering, Gyeongju University) ;
  • Cho, Il-Hyoung (Department of Ocean System Engineering, Jeju National University) ;
  • Cho, Hong-Yeon (Principal Research Scientist, Marine Environments & Conservation Research Department, Korea Institute of Ocean Science & Technology)
  • Published : 2013.12.31
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Abstract

The resonance power buoy is a convincing tool that can increase the extraction efficiency of wave energy. The buoy needs a corresponding draft, to move in resonance with waves within the peak frequency band where wave energy is concentrated. However, it must still be clarified if the buoy acts as an effective displacement amplifier, when there is insufficient water depth. In this study, the vertical displacement of a circular cylinder-type buoy was calculated, with the spectrum data observed in a real shallow sea as the external wave force, and with the corresponding draft, according to the mode frequency of normal waves. Such numerical investigation result, without considering Power Take-Off (PTO) damping, confirmed that the area of the heave responses spectrum can be amplified by up to about tenfold, compared with the wave energy spectrum, if the draft corresponds to the peak frequency, even with insufficient water depth. Moreover, the amplification factor of the buoy varied, according to the seasonal changes in the wave spectra.

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References

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