Cristin-resultat-ID: 1164766
Sist endret: 31. mai 2017, 08:42
NVI-rapporteringsår: 2014
Resultat
Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
2014

Hydrodynamic forces acting on objects in a moonpool

Bidragsytere:
  • Leiv Aspelund
  • Bjørnar Pettersen
  • Jan Hendrik Visscher og
  • Tor-Bjørn Idsøe Næss

Bok

33rd International Conference on Ocean, Offshore and Arctic Engineering Volume 1B: Offshore Technology
ISBN:
  • 978-0-7918-4538-7

Utgiver

The American Society of Mechanical Engineers (ASME)
NVI-nivå 1

Serie

International Conference on Offshore Mechanics and Arctic Engineering (OMAE) [proceedings]
ISSN 1523-651X
NVI-nivå 1

Om resultatet

Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
Publiseringsår: 2014
Volum: 33
Hefte: IB
Antall sider: 10
ISBN:
  • 978-0-7918-4538-7

Klassifisering

Fagfelt (NPI)

Fagfelt: Marin og maritim teknologi
- Fagområde: Realfag og teknologi

Beskrivelse Beskrivelse

Tittel

Hydrodynamic forces acting on objects in a moonpool

Sammendrag

Traditionally, it has often been assumed that the flow conditions in a moonpool are only moderately altered when an object is introduced therein. Moreover, the hydrodynamic forces acting on the object has typically been estimated by Morison’s equation for small volume structures, using the fluid kinematics of the empty moonpool as a basis and applying correction factors for the confined flow conditions, as for an object in a tube or a channel. To investigate the validity of the traditional approach, an experimental study on the forces acting on objects in a moonpool was performed at NTNU/MARINTEK in Trondheim, Norway in 2013. The experiments were done using a simplified 2-dimensional moonpool model which was given a forced heave motion. Two objects, both with square cross sections but of different sizes, were put inside the moonpool one at the time. The resulting wave elevations inside the moonpool and the forces acting on the objects were recorded and analyzed. To get a deeper understanding of the flow characteristics in the moonpool, PIV measurements were used to obtain the fluid velocity fields. The experiments revealed that even moderately sized objects (relative to the size of the moonpool) change the fluid motions in the moonpool to a large extent; the overall wave elevation amplitude is strongly reduced and the resonance period is altered. A consequence of this is that there is a large discrepancy between the hydrodynamic forces acting on the objects measured in the experiments and the forces calculated using the traditional approach. The PIV results showed the formation of vortices at the inlet of the moonpool and at the edges of the objects, which is the main source of non-linear damping of the wave elevation inside a moonpool.

Bidragsytere

Leiv Aspelund

  • Tilknyttet:
    Forfatter
    ved Diverse norske bedrifter og organisasjoner

Bjørnar Pettersen

  • Tilknyttet:
    Forfatter
    ved Institutt for marin teknikk ved Norges teknisk-naturvitenskapelige universitet

Jan Hendrik Visscher

  • Tilknyttet:
    Forfatter
    ved Skip og havkonstruksjoner ved SINTEF Ocean

Tor-Bjørn Idsøe Næss

  • Tilknyttet:
    Forfatter
    ved Diverse norske bedrifter og organisasjoner
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Resultatet er en del av Resultatet er en del av

33rd International Conference on Ocean, Offshore and Arctic Engineering Volume 1B: Offshore Technology.

Yeung, Ronald W.; Oakley, Owen. 2014, The American Society of Mechanical Engineers (ASME). Vitenskapelig antologi/Konferanseserie
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