Experimental and Numerical Analysis of the Behavior of a Monocolumn With a Moonpool

Torres, Fernando Gómez; Alho, Alexandre T. P.; Sales, Joel Sena; Sphaier, Sergio H.; Nishimoto, Kazuo

doi:10.1115/omae2008-57657

Cited by 7 publications

(2 citation statements)

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“…This has also been shown in model tests, e.g. by Torres et al (Torres et al 2008) and Kristiansen et al (Kristiansen et al 2011). The drawback of appendage plates, from a practical point of view, is that they reduce the effective area of the moonpool.…”

Section: Flow Separation and Vortex Shedding At Inletmentioning

confidence: 58%

Hydrodynamic Forces Acting on Objects in a Moonpool

Aspelund

Pettersen

Visscher

et al. 2014

Volume 1B: Offshore Technology

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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.

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Section: Flow Separation and Vortex Shedding At Inletmentioning

confidence: 58%

Hydrodynamic Forces Acting on Objects in a Moonpool

Aspelund

Pettersen

Visscher

et al. 2014

Volume 1B: Offshore Technology

View full text Add to dashboard Cite

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“…Masetti et al [7] carried out experiments to study the influence of different skirts on the response of monocolumn floating production structure and the influence of variation of the external diameter along the vertical axis. Torres et al [11] published works by changing the internal geometry of the moonpool. Changes of the moon pool internal geometry modified the behaviour of vertical oscillation of the water inside the moonpool.…”

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confidence: 99%

Parametric Study on the Hydrodynamic Response of Dsi Polygonal Shaped Fpso

Vijayalakshmi¹,

Ramalingam²,

Srinivasan³

et al. 2017

Brod

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SummaryIn the present paper, numerical investigations was carried out on a 1:45 scaled model of DSI nine sided polygonal non-ship shaped FPSO, by varying different parameters of the model. Parameters such as inlet pipe radius, and moonpool radius was considered for the study and the variation of the RAO in surge and heave were plotted and reported in the present paper. Previously, experiment were conducted by the author on a 1:45 scale DSI nine sided polygonal non-ship shaped FPSO model with three different mooring arrangements viz. 100% turret mooring, 50% vessel and 50% turret mooring, and 100% vessel mooring. Author also conducted experiments on the model with different sizes of damping plates attached at the keel and skirt portion of the model to study its influence on the responses of the vessel and comparison was made with numerical result obtained from Wave analysis, MIT (WAMIT) software. Numerical study was carried out in WAMIT on the scaled model and the results were compared with those obtained from model tests in the wave basin.

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