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Offshore Technology

Experimental Comparative Study on Vortex-Induced Motion (VIM) of a Monocolumn Platform

[+] Author and Article Information
Rodolfo T. Gonçalves

TPN-Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica–University of São Paulo, Avenida Professor Mello Moraes, 2231 Cidade Universitária, São Paulo, SP, 05508-900, Brazilrodolfo_tg@tpn.usp.br

Guilherme F. Rosetti

TPN-Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica–University of São Paulo, Avenida Professor Mello Moraes, 2231 Cidade Universitária, São Paulo, SP, 05508-900, Brazilguilherme.feitosa@tpn.usp.br

André L. C. Fujarra

TPN-Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica–University of São Paulo, Avenida Professor Mello Moraes, 2231 Cidade Universitária, São Paulo, SP, 05508-900, Brazilafujarra@usp.br

Kazuo Nishimoto

TPN-Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica–University of São Paulo, Avenida Professor Mello Moraes, 2231 Cidade Universitária, São Paulo, SP, 05508-900, Brazilknishimo@usp.br

J. Offshore Mech. Arct. Eng 134(1), 011301 (Oct 12, 2011) (15 pages) doi:10.1115/1.4003494 History: Received December 11, 2009; Revised December 10, 2010; Published October 12, 2011; Online October 12, 2011

An analysis methodology is presented as well as a comparison of results obtained from vortex-induced motion (VIM) model tests of the MonoGoM platform, a monocolumn floating unit designed for the Gulf of Mexico. The choice of scale between the model and the platform in which the tests took place was a very important issue that took into account the basin dimensions and mooring design. The tests were performed in three different basins: the IPT Towing Tank in Brazil (Sept. 2005), the NMRI Model Ship Experimental Towing Tank in Japan (Mar. 2007), and the NMRI Experimental Tank in Japan (Jun. 2008). The purpose is to discuss the most relevant issues regarding the concept, execution, and procedures to comparatively analyze the results obtained from VIM model tests, such as characteristic motion amplitudes, motion periods, and forces. The results pointed out the importance of considering the 2DOF in the model tests, i.e., the coexistence of the motions in both in-line and transverse directions. The approach employed in the tests was designed to build a reliable data set for comparison with theoretical and numerical models for VIM prediction, especially that of monocolumn platforms.

Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Sketch with the main dimensions of the platform in meters

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Figure 2

Configuration of the tests at IPT-Brazil

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Figure 3

Type of roughness: (1) smooth, (2) low roughness, (3) high roughness and high density, and (4) high roughness and low density

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Figure 4

Details of the external appendages

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Figure 5

Sketch of the distribution of the spoiler plates at the monocolumn

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Figure 6

Configuration of the NMRI tests

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Figure 7

Spring system configuration at NMRI tests

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Figure 8

Calculation of transverse and in-line stiffnesses

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Figure 9

Comparison between A/D definitions

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Figure 10

Variation in nondimensional amplitudes as a function of reduced velocities for different types of roughness

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Figure 11

Variation in nondimensional periods as a function of reduced velocities for different types of roughness

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Figure 12

Motions on the XY plane (in-line and transverse directions) for different types of roughness: (a) smooth and (b) high roughness and high density

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Figure 13

Variation in drag coefficients as a function of reduced velocities for different types of roughness

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Figure 14

Variation in the lift coefficient (CL) above and the added mass (Ca) below as a function of the reduced velocity for different types of roughness

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Figure 15

Variation in drag coefficient as a function of reduced velocities for different types of roughness in captive tests

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Figure 16

Variation in nondimensional amplitudes as a function of reduced velocities for different headings

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Figure 17

Variation in nondimensional periods as a function of reduced velocities for different headings

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Figure 18

Variation in drag coefficients as a function of reduced velocities for different headings

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Figure 19

Motions on the XY plane (in-line and transverse directions) for different headings: (a) SE and (b) NW

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Figure 20

Variation in the lift coefficient (CL) above and the added mass (Ca) below as a function of the reduced velocity for different headings

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Figure 21

Variation in nondimensional amplitudes as a function of the reduced velocity due to the presence of spoiler plates

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Figure 22

Variation in nondimensional periods as a function of the reduced velocity due to the presence of spoiler plates

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Figure 23

Variation in drag coefficients as a function of the reduced velocity due to the presence of spoiler plates

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Figure 24

Variation in the lift coefficient (CL) above and the added mass (Ca) below as a function of the reduced velocity due to the presence of spoiler plates

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Figure 25

Motions on the XY plane (in-line and transverse directions) for different headings: (a) SE and (b) NW

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Figure 26

Variation in nondimensional amplitudes as a function of reduced velocities for different transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2007 tests

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Figure 27

Variation in nondimensional periods as a function of reduced velocities for different transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2007 tests

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Figure 28

Variation in drag coefficients as a function of reduced velocities for different transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2007 tests

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Figure 29

Variation in the lift coefficient (CL) above and the added mass (Ca) below as a function of the reduced velocity for transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2007 tests

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Figure 30

Motions on the XY plane (in-line and transverse directions) for different headings: (a) 180 deg and (b) 0 deg—transverse stiffness, 15 N/m—NMRI-2007 tests

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Figure 31

Variation in nondimensional amplitudes as a function of reduced velocities for different transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2008 tests

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Figure 32

Variation in nondimensional periods as a function of reduced velocities for different transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2008 tests

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Figure 33

Variation in drag coefficients as a function of reduced velocities for different transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2008 tests

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Figure 34

Variation in the lift coefficient (CL) above and the added mass (Ca) below as a function of the reduced velocity for transverse stiffness levels—0 deg and 180 deg incidences—NMRI-2008 tests

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Figure 35

Motions on the XY plane (in-line and transverse directions) for different headings: (a) 180 deg and (b) 0 deg—transverse stiffness, 15 N/m—NMRI-2008 tests

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