Full-scale CFD investigations of helical strakes as a means of reducing the vortex induced forces on a semi-submersible

Vegard Holland, Tahsin Tezdogan, Elif Oguz

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

As the search for oil in the Gulf of Mexico (GoM) moves into deeper waters, floating platforms such as semisubmersibles are in increasing demand. As semi-submersibles increase in size, the effect of vortex-induced motions (VIMs) becomes a significant problem in their design. VIMs stem from transverse forces caused by the current affecting the platform, with vortexes moving downstream on either side of the structure. The loop/eddy current phenomenon in the GoM leads to a constant current being present in the area, with speeds of up to 1.8 m/s. The accurate prediction of the vertical and transverse motions of semi-submersibles is crucial for the design of the riser systems. It is therefore beneficial to investigate the hydrodynamic forces acting on the geometry, and means of reducing these forces. A common method of reducing transverse forces is the addition of column appendages, such as helical strakes. In this paper, full-scale computational fluid dynamic analyses are carried out to examine the transverse forces caused by this vortex shedding using realistic current velocities in the GoM. Helical strakes are attached to the geometry to break up the coherence of the vortex shedding and the performance of these strakes is investigated numerically.
LanguageEnglish
Pages338-351
Number of pages14
JournalOcean Engineering
Volume137
DOIs
Publication statusPublished - 18 Apr 2017

Fingerprint

Semisubmersibles
Computational fluid dynamics
Vortex flow
Vortex shedding
Geometry
Eddy currents
Hydrodynamics
Water

Keywords

  • vortex induced motion
  • semisubmersible
  • CFD
  • helical strakes

Cite this

@article{50c9c1c62f3c4605a20044b426dd242b,
title = "Full-scale CFD investigations of helical strakes as a means of reducing the vortex induced forces on a semi-submersible",
abstract = "As the search for oil in the Gulf of Mexico (GoM) moves into deeper waters, floating platforms such as semisubmersibles are in increasing demand. As semi-submersibles increase in size, the effect of vortex-induced motions (VIMs) becomes a significant problem in their design. VIMs stem from transverse forces caused by the current affecting the platform, with vortexes moving downstream on either side of the structure. The loop/eddy current phenomenon in the GoM leads to a constant current being present in the area, with speeds of up to 1.8 m/s. The accurate prediction of the vertical and transverse motions of semi-submersibles is crucial for the design of the riser systems. It is therefore beneficial to investigate the hydrodynamic forces acting on the geometry, and means of reducing these forces. A common method of reducing transverse forces is the addition of column appendages, such as helical strakes. In this paper, full-scale computational fluid dynamic analyses are carried out to examine the transverse forces caused by this vortex shedding using realistic current velocities in the GoM. Helical strakes are attached to the geometry to break up the coherence of the vortex shedding and the performance of these strakes is investigated numerically.",
keywords = "vortex induced motion, semisubmersible, CFD, helical strakes",
author = "Vegard Holland and Tahsin Tezdogan and Elif Oguz",
year = "2017",
month = "4",
day = "18",
doi = "10.1016/j.oceaneng.2017.04.014",
language = "English",
volume = "137",
pages = "338--351",
journal = "Ocean Engineering",
issn = "0029-8018",
publisher = "Elsevier",

}

Full-scale CFD investigations of helical strakes as a means of reducing the vortex induced forces on a semi-submersible. / Holland, Vegard; Tezdogan, Tahsin; Oguz, Elif.

In: Ocean Engineering, Vol. 137, 18.04.2017, p. 338-351.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Full-scale CFD investigations of helical strakes as a means of reducing the vortex induced forces on a semi-submersible

AU - Holland, Vegard

AU - Tezdogan, Tahsin

AU - Oguz, Elif

PY - 2017/4/18

Y1 - 2017/4/18

N2 - As the search for oil in the Gulf of Mexico (GoM) moves into deeper waters, floating platforms such as semisubmersibles are in increasing demand. As semi-submersibles increase in size, the effect of vortex-induced motions (VIMs) becomes a significant problem in their design. VIMs stem from transverse forces caused by the current affecting the platform, with vortexes moving downstream on either side of the structure. The loop/eddy current phenomenon in the GoM leads to a constant current being present in the area, with speeds of up to 1.8 m/s. The accurate prediction of the vertical and transverse motions of semi-submersibles is crucial for the design of the riser systems. It is therefore beneficial to investigate the hydrodynamic forces acting on the geometry, and means of reducing these forces. A common method of reducing transverse forces is the addition of column appendages, such as helical strakes. In this paper, full-scale computational fluid dynamic analyses are carried out to examine the transverse forces caused by this vortex shedding using realistic current velocities in the GoM. Helical strakes are attached to the geometry to break up the coherence of the vortex shedding and the performance of these strakes is investigated numerically.

AB - As the search for oil in the Gulf of Mexico (GoM) moves into deeper waters, floating platforms such as semisubmersibles are in increasing demand. As semi-submersibles increase in size, the effect of vortex-induced motions (VIMs) becomes a significant problem in their design. VIMs stem from transverse forces caused by the current affecting the platform, with vortexes moving downstream on either side of the structure. The loop/eddy current phenomenon in the GoM leads to a constant current being present in the area, with speeds of up to 1.8 m/s. The accurate prediction of the vertical and transverse motions of semi-submersibles is crucial for the design of the riser systems. It is therefore beneficial to investigate the hydrodynamic forces acting on the geometry, and means of reducing these forces. A common method of reducing transverse forces is the addition of column appendages, such as helical strakes. In this paper, full-scale computational fluid dynamic analyses are carried out to examine the transverse forces caused by this vortex shedding using realistic current velocities in the GoM. Helical strakes are attached to the geometry to break up the coherence of the vortex shedding and the performance of these strakes is investigated numerically.

KW - vortex induced motion

KW - semisubmersible

KW - CFD

KW - helical strakes

UR - http://www.sciencedirect.com/science/article/pii/S0029801817301993

U2 - 10.1016/j.oceaneng.2017.04.014

DO - 10.1016/j.oceaneng.2017.04.014

M3 - Article

VL - 137

SP - 338

EP - 351

JO - Ocean Engineering

T2 - Ocean Engineering

JF - Ocean Engineering

SN - 0029-8018

ER -