Journal of Ocean Engineering and Technology (한국해양공학회지)

Korean Society of Ocean Engineers (한국해양공학회)
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Model Test for Heave Motion Reduction of a Circular Cylinder by a Damping Plate

감쇠판에 의한 원기둥의 상하운동 저감 모형시험

  • Koh, Hyeok-Jun (Multidisciplinary Graduate School for Wind Energy, Jeju National Univerisity) ;
  • Kim, Jeong-Rok (Ocean System Engineering, Jeju National Univerisity) ;
  • Cho, Il-Hyoung (Ocean System Engineering, Jeju National Univerisity)
  • 고혁준 (제주대학교 풍력특성화협동과정) ;
  • 김정록 (제주대학교 해양시스템공학과) ;
  • 조일형 (제주대학교 해양시스템공학과)
  • Received : 2013.06.12
  • Accepted : 2013.08.12
  • Published : 2013.08.31
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Abstract

Motion reduction of an offshore structure at resonant frequency is essential for avoiding critical damage to the topside and mooring system. A damping plate has a distinct advantage in reducing the motion of a floating structure by increasing the added mass and the damping coefficient. In this study, the heave motion responses of a circular cylinder with an impermeable and a permeable damping plate attached at the bottom of the cylinder were investigated thru a model test. The viscous damping coefficients for various combinations of porosity were obtained from a free-decay test by determining the ratio between any pair of successive amplitudes. Maximum energy dissipation occurred at a porous plate with a porosity P = 0.1008. Experimental results for regular and irregular waves were compared with an analytical solution by Cho (2011). The measured heave RAO and spectrum reasonably followed the trends of the predicted values. A significant motion reduction at resonant frequency was pronounced and the heaving-motion energy calculated by the integration of the area under the heave motion spectrum was reduced by more than 75% by the damping plate. However, additional energy dissipation by eddies of strong vorticity and flow separation inside a porous damping plate was not found in the present experiments.

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References

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  1. A Numerical Study on the Appendage Shape for a Heave Motion Reduction of Floating Cylindrical Structure vol.21, pp.4, 2015, https://doi.org/10.7837/kosomes.2015.21.4.449