Performance characteristics of a conceptual ring-shaped spar-type VLFS with double-layered perforated-wall breakwater

Yufeng Kou, Longfei Xiao, Longbin Tao, Tao Peng

Research output: Contribution to journalArticle

Abstract

A ring-shaped spar-type Very Large Floating Structure (VLFS) is proposed as an intermediate base for supporting deepwater resource exploitation far away from the coast line. The proposed VLFS is composed of eight rigidly connected deep-draft spar-type modules and an inside harbor. A double-layered perforated-wall breakwater is vertically attached to the VLFS and pierces through the water surface to attenuate the wave energy in the inside harbor. The hydrodynamic performance characteristics of the ring-shaped VLFS was experimentally evaluated in the present study, focusing on the motion responses, wave elevations, and wave run-ups. The natural periods of the motions in vertical plane were determined to be larger than 40s, which is much larger than common wave periods. This enhanced the motion performance in vertical plane and afforded favorable habitation and operation condition on the VLFS. A large surge damping was induced by the vertical breakwater, which tended to significantly affect the surge and pitch motions, but had a negligible effect on the heave motion. The component frequencies of the wave elevations in the inside harbor and the wave run-ups were identical with those of the incident waves. The wave attenuation was frequency-dependent and effective for the common wave frequencies, with a smaller loss coefficient observed in higher sea state. The wave attenuation and wave run-ups tended to improve in the absence of the leeward walls.
LanguageEnglish
Pages28-39
Number of pages12
JournalApplied Ocean Research
Volume86
Early online date27 Feb 2019
DOIs
Publication statusPublished - 31 May 2019

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Breakwaters
Ports and harbors
Coastal zones
Hydrodynamics
Damping

Keywords

  • very large floating structure
  • breakwater
  • motion response
  • wave attenuation
  • wave run-up

Cite this

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abstract = "A ring-shaped spar-type Very Large Floating Structure (VLFS) is proposed as an intermediate base for supporting deepwater resource exploitation far away from the coast line. The proposed VLFS is composed of eight rigidly connected deep-draft spar-type modules and an inside harbor. A double-layered perforated-wall breakwater is vertically attached to the VLFS and pierces through the water surface to attenuate the wave energy in the inside harbor. The hydrodynamic performance characteristics of the ring-shaped VLFS was experimentally evaluated in the present study, focusing on the motion responses, wave elevations, and wave run-ups. The natural periods of the motions in vertical plane were determined to be larger than 40s, which is much larger than common wave periods. This enhanced the motion performance in vertical plane and afforded favorable habitation and operation condition on the VLFS. A large surge damping was induced by the vertical breakwater, which tended to significantly affect the surge and pitch motions, but had a negligible effect on the heave motion. The component frequencies of the wave elevations in the inside harbor and the wave run-ups were identical with those of the incident waves. The wave attenuation was frequency-dependent and effective for the common wave frequencies, with a smaller loss coefficient observed in higher sea state. The wave attenuation and wave run-ups tended to improve in the absence of the leeward walls.",
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Performance characteristics of a conceptual ring-shaped spar-type VLFS with double-layered perforated-wall breakwater. / Kou, Yufeng; Xiao, Longfei; Tao, Longbin; Peng, Tao.

In: Applied Ocean Research, Vol. 86, 31.05.2019, p. 28-39.

Research output: Contribution to journalArticle

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