The effect of yaw angle on VIV suppression for an inclined flexible cylinder fitted with helical strakes

Most deepwater tubulars experiencing high currents frequently require vortex-induced vibration (VIV) suppression to maintain an acceptable fatigue life. Helical strakes and fairings are the most popular VIV suppression devices in use today. Marine growth can significantly affect the VIV of a bare riser, often within just a few weeks or months after riser installation. Marine growth can have a strong influence on the performance of helical strakes and fairings on deepwater tubulars. This influence affects both suppression effectiveness as well as the drag forces on the helical strakes and fairings. Unfortunately, many VIV analyses and suppression designs fail to account for the effects of marine growth at all, even on a bare riser. This paper utilizes results from both high and low Reynolds number VIV test programs to provide some design considerations for managing marine growth for VIV suppression devices.

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Experimental Investigation on the Suppression Device of VIV of a Flexible Riser

Volume 2: CFD and VIV ◽

10.1115/omae2014-23427 ◽

2014 ◽

Cited By ~ 1

Author(s):

Yun Gao ◽

Shixiao Fu ◽

Leijian Song ◽

Tao Peng ◽

Runpei Lei

Keyword(s):

Fatigue Damage ◽

Experimental Results ◽

Experimental Investigations ◽

Flexible Riser ◽

Excited Mode ◽

Response Characteristics ◽

Helical Strakes ◽

Uniform Current ◽

Viv Suppression ◽

Synchronization Regime

Experimental investigations were conducted on a flexible riser with and without helical strakes. A uniform current was obtained by towing a riser model in a tank, and the vortex-induced vibration (VIV) suppression of strakes with different heights and pitches was studied. The results of the bare riser show that the characteristics of the synchronization of the VIV for a flexible riser have many orders, and the excited mode jumps from one to another abruptly. During the high order synchronization regime, the VIV response decreases with the increased order of the synchronization. The experimental results also indicate that the response characteristics of a bare riser can be quite distinct from those of a riser with helical strakes, and the suppression performance depends on the geometry of the helical strakes. The fatigue damage in the CF direction is of the same order as that in the IL direction for the bare riser. However, for the riser fitted with helical strakes, the fatigue damage in the CF direction is much smaller than that in the IL direction. The experimental results also confirmed that strake height has a greater influence on the VIV response than the strake pitch, and the drag exerted on the riser increases with strake pitch and height.

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Fairing Evaluation Based on Numerical Simulation

Volume 5: Ocean Engineering; CFD and VIV ◽

10.1115/omae2012-83883 ◽

2012 ◽

Cited By ~ 2

Author(s):

Juan P. Pontaza ◽

Mohan Kotikanyadanam ◽

Piet Moeleker ◽

Raghu G. Menon ◽

Shankar Bhat

Keyword(s):

Fluid Dynamics ◽

Numerical Simulation ◽

Current Speed ◽

Full Scale ◽

Attractive Alternative ◽

Element Analysis ◽

Vortex Induced Vibrations ◽

Helical Strakes ◽

Computational Fluid Dynamics Cfd ◽

Viv Suppression

It is well established that strakes are effective at suppressing vortex-induced vibrations (VIV). Fairings are an attractive alternative to helical strakes, because they are a low drag VIV suppression solution. The paper presents an evaluation of a fairing design, based on numerical simulations — to be complemented at a later stage with current tank testing. This paper documents the computational fluid dynamics (CFD) and finite element analysis (FEA) of the evaluation: (1) 3-D CFD in the laboratory scale: 4.5 inch pipe, 3 ft/s current speed, (2) 3-D CFD in the full scale: 14 inch riser, 4 knots current speed, and (3) 3-D FEA of the full-scale fairing module latching mechanism, under service loads corresponding to 4 knots current speed. The analysis results show that the fairing design (1) is effective at suppressing VIV, (2) yields a low drag coefficient (0.52 at Re ∼ 106), and (3) its latching mechanism is adequate for use in calm sea states with 4 knots current speeds.

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VIV and WIV Suppression With Parallel Control Plates on a Pair of Circular Cylinders in Tandem

Volume 5: Polar and Arctic Sciences and Technology; CFD and VIV ◽

10.1115/omae2009-79081 ◽

2009 ◽

Cited By ~ 1

Author(s):

Gustavo R. S. Assi ◽

Peter W. Bearman

Keyword(s):

Circular Cylinder ◽

Drag Reduction ◽

Flow Direction ◽

Cross Flow ◽

Offshore Structures ◽

Circular Cylinders ◽

Parallel Plates ◽

Tandem Cylinders ◽

Helical Strakes ◽

Viv Suppression

Experiments have been carried out on two-dimensional devices fitted to a rigid length of circular cylinder to investigate the efficiency of pivoting parallel plates as wake-induced vibration suppressors. Measurements are presented for a circular cylinder with low mass and damping which is free to respond in the cross-flow direction. It is shown how VIV and WIV can be practically eliminated by using free to rotate parallel plates on a pair of tandem cylinders. Unlike helical strakes, the device achieves VIV suppression with 33% drag reduction when compare to a pair of fixed tandem cylinders at the same Reynolds number. These results prove that suppressors based on parallel plates have great potential to suppress VIV and WIV of offshore structures with considerable drag reduction.

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VIV suppression for a large mass-damping cylinder attached with helical strakes

Journal of Fluids and Structures ◽

10.1016/j.jfluidstructs.2016.01.005 ◽

2016 ◽

Vol 62 ◽

pp. 125-146 ◽

Cited By ~ 20

Author(s):

Juan Sui ◽

Jiasong Wang ◽

Shengping Liang ◽

Qilong Tian

Keyword(s):

Large Mass ◽

Helical Strakes ◽

Viv Suppression

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Performance Comparisons of Helical Strakes for VIV Suppression of Risers and Tendons

10.4043/16186-ms ◽

2004 ◽

Cited By ~ 5

Author(s):

Don W. Allen ◽

Dean L. Henning ◽

Li W. Lee

Keyword(s):

Helical Strakes ◽

Viv Suppression ◽

Performance Comparisons

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VIV Suppression and Drag Reduction With Pivoted Control Plates on a Circular Cylinder

Volume 5: Materials Technology; CFD and VIV ◽

10.1115/omae2008-57609 ◽

2008 ◽

Cited By ~ 3

Author(s):

Gustavo R. S. Assi ◽

Peter W. Bearman

Keyword(s):

Reynolds Number ◽

Circular Cylinder ◽

Drag Reduction ◽

Flow Direction ◽

Cross Flow ◽

Two Dimensional ◽

Dimensional Control ◽

Helical Strakes ◽

Low Mass ◽

Viv Suppression

Experiments have been carried out on two-dimensional devices fitted to a rigid length of circular cylinder to investigate the efficiency of pivoting control plates as VIV suppressors. Measurements are presented for a circular cylinder with low mass and damping which is free to respond in the cross-flow direction. It is shown how vortex-induced vibration can be practically eliminated by using free to rotate, two-dimensional control plates. Unlike helical strakes, the devices achieve VIV suppression with drag reduction. The device producing the largest drag reduction was found to have a drag coefficient equal to about 70% of that for a plain cylinder at the same Reynolds number.

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Coupled VIV and Heat Transfer Analyses: Design of VIV Suppression Configuration for the Independence Hub SCRs

Volume 4: Terry Jones Pipeline Technology; Ocean Space Utilization; CFD and VIV Symposium ◽

10.1115/omae2006-92575 ◽

2006 ◽

Author(s):

Raghu Menon ◽

Li Lee ◽

Basim Mekha

Keyword(s):

Heat Transfer ◽

Significant Risk ◽

Ambient Seawater ◽

Thermal Requirements ◽

Optimum Configuration ◽

Production Platform ◽

Helical Strakes ◽

Computational Fluid Dynamics Cfd ◽

Under Construction ◽

Viv Suppression

Independence Hub (IH), a semisubmersible production platform in the deepwater Gulf of Mexico is currently under construction and will produce gas and condensate from multiple subsea developments. The platform, installed in some 8000 feet of water, is located in a region of the Gulf that is well known for its severe environment, particularly persistent loop currents that could last several months out of a year. The current profiles are such that there is a significant risk of fatigue failure of the risers due to Vortex Induced Vibration (VIV) and adequate mitigation through installation of VIV suppression devices, such as strakes and fairings, are required. An additional challenge that impacts the topsides facility and flex joint design is the low arrival temperature of the produced gas due to Joule-Thomson (JT) cooling. In the case of a bare riser (one without any VIV suppression), the heat transferred from the ambient seawater to the produced gas is sufficient to exceed the target arrival temperature. However, installing VIV suppression devices along the span of the riser may insulate it, which in turn has the potential to decrease the arrival temperature significantly. This paper will discuss coupled VIV and heat transfer analyses carried out to assess the risk of both VIV and low arrival temperatures for the IH production risers. The heat transfer analyses were carried out rigorously using 3D Computational Fluid Dynamics (CFD) simulations of the riser with and without VIV suppression devices. Helical strakes and short fairings were analyzed and optimum suppression configurations for two production risers that meet both the VIV and thermal requirements are presented. The optimum configuration was also subject to the requirement that the suppressed risers be S-layable. A hybrid suppression design based on both strakes and fairings are presented that meets the fatigue and arrival temperature requirements while minimizing installation risks using the S-lay method.

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