KNSwing - On the Mooring Loads of a Ship-Like Wave Energy Converter

Kim Nielsen*, Jonas Bjerg Thomsen

*Corresponding author

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

The critical function of keeping a floating Wave Energy Converter in position is done by a mooring system. Several WECs have been lost due to failed moorings, indicating that extreme loads, reliability and durability are very important aspects. An understanding of the interaction between the WEC’s motion in large waves and the maximum mooring loads can be gained by investigating the system at model scale supported by numerical models. This paper describes the testing of a novel attenuator WEC design called KNSwing. It is shaped like a ship facing the waves with its bow, which results in low mooring loads and small motions in most wave conditions when the structure is longer than the waves. The concept is tested using an experimental model at scale 1:80 in regular and irregular waves, moored using rubber bands to simulate synthetic moorings. The experimental results are compared to numerical simulations done using the OrcaFlex software. The experimental results show that the WEC and the mooring system survives well, even under extreme and breaking waves. The numerical model coefficient concerning the nonlinear drag term for the surge motion is validated using decay tests. The numerical results compare well to the experiments and, thereby, the numerical model can be further used to optimize the mooring system.
Original languageEnglish
Article number29
JournalJournal of Marine Science and Engineering
Volume7
Issue number2
Number of pages17
ISSN2077-1312
DOIs
Publication statusPublished - 2019

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Mooring
wave energy
Ships
mooring system
Numerical models
breaking wave
durability
rubber
Surges (fluid)
drag
ship
software
Drag
Loads (forces)
Rubber
Durability
simulation
Computer simulation
Testing
experiment

Bibliographical note

Special Issue Advances in Ocean Wave Energy Conversion.

Keywords

  • Wave power
  • Attenuator
  • Mooring system
  • Extreme loads
  • Synthetic mooring
  • Numerical
  • NEMOH
  • OrcaFlex

Cite this

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title = "KNSwing - On the Mooring Loads of a Ship-Like Wave Energy Converter",
abstract = "The critical function of keeping a floating Wave Energy Converter in position is done by a mooring system. Several WECs have been lost due to failed moorings, indicating that extreme loads, reliability and durability are very important aspects. An understanding of the interaction between the WEC’s motion in large waves and the maximum mooring loads can be gained by investigating the system at model scale supported by numerical models. This paper describes the testing of a novel attenuator WEC design called KNSwing. It is shaped like a ship facing the waves with its bow, which results in low mooring loads and small motions in most wave conditions when the structure is longer than the waves. The concept is tested using an experimental model at scale 1:80 in regular and irregular waves, moored using rubber bands to simulate synthetic moorings. The experimental results are compared to numerical simulations done using the OrcaFlex software. The experimental results show that the WEC and the mooring system survives well, even under extreme and breaking waves. The numerical model coefficient concerning the nonlinear drag term for the surge motion is validated using decay tests. The numerical results compare well to the experiments and, thereby, the numerical model can be further used to optimize the mooring system.",
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KNSwing - On the Mooring Loads of a Ship-Like Wave Energy Converter. / Nielsen, Kim ; Thomsen, Jonas Bjerg.

In: Journal of Marine Science and Engineering, Vol. 7, No. 2, 29, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

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