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Research Papers: CFD and VIV

Full-Scale Fairing Qualification Tests

[+] Author and Article Information
Yiannis Constantinides

Chevron Energy Technology Company,
Houston, TX 77002
e-mail: ycon@chevron.com

Stergios Liapis

Shell Oil Company,
Houston, TX 77079
e-mail: stergios.liapis@shell.com

Don Spencer

Oceanic Consulting Corporation,
St. John's, NL A1B 2X5, Canada
e-mail: Spencer.Don@oceaniccorp.com

Mohammed Islam

Oceanic Consulting Corporation,
St. John's, NL A1B 2X5, Canada
e-mail: Islam.Mohammed@oceaniccorp.com

Kjetil Skaugset

Statoil Oil Company,
Trondheim N-7004, Norway
e-mail: kjska@statoil.com

Apurva Batra

Chevron Energy Technology Company,
Houston, TX 77002
e-mail: apurva@chevron.com

Rolf Baarholm

Statoil Oil Company,
Trondheim N-7004, Norway
e-mail: rolbaa@statoil.com

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received April 27, 2016; final manuscript received March 15, 2017; published online May 16, 2017. Assoc. Editor: Celso P. Pesce.

J. Offshore Mech. Arct. Eng 139(4), 041802 (May 16, 2017) (9 pages) Paper No: OMAE-16-1047; doi: 10.1115/1.4036373 History: Received April 27, 2016; Revised March 15, 2017

Production risers as well as drilling risers are often exposed to ocean currents. Vortex-induced vibrations (VIVs) have been observed in the field and can cause fatigue failure and excessive drag on the riser. In order to suppress VIV, fairings are often used. This paper presents qualification tests for two types of fairings: the short-crab claw (SCC) fairings and the AIMS dual flow splitter (ADFS) fairings. The short-crab claw fairing design is a novel design patented by the Norwegian deepwater project (NDP). As will be detailed in this paper, both the SCC and ADFS designs offer very low drag, completely suppress VIV, and are effective even when they are in tandem. A model test campaign was undertaken in the 200-m towing tank facility at the ocean, coastal, and river engineering in St. John's, NF, Canada. A rigid pipe with a diameter of 0.3556 m (14 in) was utilized for the experiments. This corresponds to prototype size for a production riser and a 1:3.8 scaled model for a 1.3716 m (54 in) drilling riser. Given that these tests were conducted at prototype scale, they were used to qualify the fairings for field deployment. Both fairings (SCC and ADFS) were very effective in suppressing VIV and reducing drag. The ADFS fairings are most effective for a span to diameter ratio of 1.75. For all fairing geometries, it was found that a small taper increases the fairing effectiveness considerably.

Copyright © 2017 by ASME
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References

Figures

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Fig. 1

High Reynolds number rig in free VIV mode

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Fig. 2

SCC fairing: sectional view with dimensions in millimeter

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Fig. 3

SCC fairings installed on the pipe

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Fig. 4

Cross section of the ADFS fairing. The joint around the trailing edge is to change the chord/diameter from 1.75 to 1.50.

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Fig. 5

ADFS fairings being installed on the large pipe dynamometer

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Fig. 6

AIMS triple helix strake fitted to 0.168 m pipe dynamometer (scale 1:2.5)

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Fig. 7

VIV test setup of SCC in single pipe 0.387 m experiments

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Fig. 8

0.168 m diameter single pipe experiments: 17DR pitch, triple-start helical strakes

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Fig. 9

0.387 m SCC upstream of 0.387 m SCC (model scale)

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Fig. 10

0.387 m SCC upstream and 0.387 m ADFS downstream (model scale)

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Fig. 11

0.387 m ADFS fairing upstream of a 0.168 m riser with strakes

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Fig. 12

Single pipe experiments: drag coefficient of SCC fairing; comparison with previous experiments

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Fig. 13

Single pipe experiments: drag of ADFS as a function of chord length

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Fig. 14

Single pipe experiments: drag of ADFS as a function of the amplitude ratio, Astar

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Fig. 15

Single pipe experiments: drag coefficient of 0.168 m pipe with strakes; comparison with previous experiments

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Fig. 16

VIV amplitude of a single pipe with SCC fairings

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Fig. 17

Single pipe experiments; motion of ADFS with chord lengths of 1.75 and 1.5

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Fig. 18

Drag coefficient for SCC fairing in the wake of an SCC

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Fig. 19

Drag of the downstream pipe with ADFS fairings in the wake of a SCC at multiple lateral and offset distances

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Fig. 20

Drag coefficient of a 0.168 m pipe with strakes in the wake of a 0.387 m pipe with ADFS fairings

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Fig. 21

Motion of a SCC fairing in the wake of a SCC fairing

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Fig. 22

ADFS motion downstream of a SCC fairing

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Fig. 23

Motion of the pipe with strakes in the wake of a pipe with ADFS fairings

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