Experimental Evaluation of Pure In-Line Vortex Induced Vibration (VIV-X) in Subsea Jumper Subject to Ocean Current

2015 ◽  
Author(s):  
M. M. Amini ◽  
A. C. Fernandes
Keyword(s):  
Experimental Evaluation ◽  
Ocean Current ◽  
Vortex Induced Vibration ◽  
Line Vortex

The prediction on in-line vortex-induced vibration of slender marine structures

2012 ◽  
Vol 28 (5) ◽  
pp. 1303-1308 ◽  
Author(s):  
Wan-Hai Xu ◽  
Xi-Feng Gao ◽  
Jie Du
Keyword(s):  
Marine Structures ◽  
Vortex Induced Vibration ◽  
Line Vortex

Experimental Investigation on Vortex-Induced Vibration of a Free-Hanging Riser Under Vessel Motion and Uniform Current

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Jungao Wang ◽  
Shixiao Fu ◽  
Jiasong Wang ◽  
Huajun Li ◽  
Muk Chen Ong
Keyword(s):  
Prediction Models ◽  
Ocean Basin ◽  
Dynamic Responses ◽  
Ocean Current ◽  
Response Frequency ◽  
Vortex Induced Vibration ◽  
Out Of Plane ◽  
Future Prediction ◽  
Uniform Current ◽  
Vessel Motion

A model test of a free-hanging riser under vessel motion and uniform current is performed in the ocean basin at Shanghai Jiao Tong University to address four topics: (1) confirm whether vortex-induced vibration (VIV) can happen due to pure vessel motion; (2) to investigate the equivalent current velocity and Keulegan–Carpenter (KC) number effect on the VIV responses; (3) to obtain the correlations for free-hanging riser VIV under vessel motion with VIV for other compliant risers; and (4) to study the similarities and differences with VIV under uniform current. The top end of the riser is forced to oscillate or move, in order to simulate vessel motion or ocean current effects. Fiber Bragg Grating (FBG) strain sensors are used to measure the riser dynamic responses. Experimental results confirm that the free-hanging riser will experience significant out-of-plane VIV under vessel motion. Meanwhile, vessel motion-induced VIV responses in terms of response amplitude, response frequency, and cross section trajectories under different test cases are further discussed and compared to those under ocean uniform current. Most importantly, the correlation among VIV response frequency, vortex shedding pairs, and maximum KC number KCmax is revealed. The presented work is supposed to provide useful references for gaining a better understanding on VIV of a free-hanging riser and for the development of future prediction models.

Hydrokinetic Energy Conversion by Flow-Induced Oscillation of Two Tandem-Cylinders of Different Stiffness

2020 ◽  
Author(s):  
Wenyong Yuan ◽  
Hai Sun ◽  
Nicholas Beltsos ◽  
Michael M. Bernitsas
Keyword(s):  
Structural Parameters ◽  
Damping Ratio ◽  
Great Influence ◽  
Clean Energy ◽  
Shielding Effect ◽  
Ocean Current ◽  
Vortex Induced Vibration ◽  
Hydrokinetic Energy ◽  
Energy Harnessing ◽  
The Impact

Abstract The VIVACE (Vortex-Induced Vibration for Aquatic Clean Energy) Converter harnesses hydrokinetic energy by enhancing flow-induced oscillations (FIOs) of elastically supported rigid cylinders in a river, tide, or ocean current. The harnessing power depends on the intensity of the oscillation, which is a consequence of the flow-structure interaction. The inflow condition for the downstream (2nd) cylinder is slowed down and perturbed by the upstream (1st) cylinder, due to the shielding effect. Therefore, the optimal structural parameters, i.e., stiffness and damping ratio, for the 2nd cylinder may be different from the 1st cylinder, in terms of energy harnessing. To improve the performance of the VIVACE Converter, a series of experiments are conducted in a recirculating water channel, with various stiffness combinations of two cylinders in tandem. Three center-to-center spacings, six damping ratios, and seven combinations of spring stiffness are tested. The stiffness of the 1st cylinder, K1, is 600 N/m or 1,000 N/m, while the stiffness of the 2nd cylinder, K2, varies from 400 N/m to 1,200 N/m in increments of 200N/m. Results show that K2 does not affect the energy harnessing power in vortex-induced vibration (VIV) occurring at low speeds, but has great influence on the harnessing power at higher velocities in the transition region from VIV to galloping and in galloping. Decreasing K2 onsets and enhances galloping at lower flow velocity and harnesses up to 110% more energy than the case of K1 = K2. For K1 = 1,000 N/m, the harnessed power is the same for all the combinations of K1 and K2. The overall performance is best when K1 = K2. As spacing increases, the impact of K2 is diminished as explain by the dependence of power on the amplitude and frequency of cylinder oscillations.

Vortex-Induced Vibration of a Free-Hanging Riser Under Irregular Vessel Motion

2016 ◽  
Author(s):  
Jungao Wang ◽  
Rajeev Kumar Jaiman ◽  
Peter Francis Bernad Adaikalaraj ◽  
Linwei Shen ◽  
Sue Ben Tan ◽  
...  
Keyword(s):  
Literature Review ◽  
Experimental Validation ◽  
Ocean Current ◽  
Current Profile ◽  
Vortex Induced Vibration ◽  
Norwegian Sea ◽  
Irregular Wave ◽  
Riser Design ◽  
Similarities And Differences ◽  
Vessel Motion

In this paper, we focus on vortex-induced vibration (VIV) of a free-hanging riser attached to a vessel under irregular wave conditions. The global in-plane responses of the hanging riser are firstly studied numerically in order to generate the equivalent current profile under vessel motion, and a simplified irregular vessel motion-induced VIV prediction methodology is then proposed based on the understanding from previous experimental observations and literature review. Further comparison on irregular vessel motion-induced VIV and ocean current-induced VIV at the same operation site with the same return period is performed to emphasize the importance of vessel motion-induced VIV. Numerical results highlight that vessel motion-induced VIV can cause similar stresses, fatigue damage and drag amplification similar to the steady ocean current cases, especially to the operation site like Norwegian Sea where strong wave field exists with mild current condition. It should be mentioned that although the simplified methodology proposed in this paper requires further experimental validation, it is believed that the presented numerical pre-study would help the industry and the researchers to have initial understanding on the possible occurrence of vessel motion-induced VIV. We further show the similarities and differences of vessel motion-induced VIV with respect to the ocean current-induced VIV and its implications on riser design and operation.

Hydrokinetic Energy Conversion by Flow-Induced Oscillation of Two Tandem-Cylinders of Different Stiffness

2021 ◽  
pp. 1-17
Author(s):  
Wenyong Yuan ◽  
Hai Sun ◽  
Eun Soo Kim ◽  
H Li ◽  
Nicholas Beltsos ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Damping Ratio ◽  
Water Channel ◽  
Great Influence ◽  
Clean Energy ◽  
Shielding Effect ◽  
Ocean Current ◽  
Vortex Induced Vibration ◽  
Hydrokinetic Energy ◽  
Energy Harnessing

Abstract The VIVACE (Vortex-Induced Vibration for Aquatic Clean Energy) Converter harnesses hydrokinetic energy by enhancing flow-induced oscillations (FIOs) of elastically supported rigid cylinders in a river, tide, or ocean current. The harnessing power depends on the intensity of the oscillation, which is a consequence of the flow-structure interaction. The inflow condition for the downstream (2nd) cylinder is slowed down and perturbed by the upstream (1st) cylinder, due to the shielding effect. Therefore, the optimal structural parameters, i.e., stiffness and damping ratio, for the 2nd cylinder may be different from the 1st cylinder, in terms of energy harnessing. To improve the performance of the VIVACE Converter, a series of experiments are conducted in a recirculating water channel, with various stiffness combinations of two cylinders in tandem. Results show that the stiffness of the 2nd cylinder, K2, does not affect the energy harnessing power in vortex-induced vibration (VIV) occurring at low speeds, because the oscillation of the downstream cylinder in this velocity range is completely dominated by the wake of the upstream cylinder. K2 has a great influence on the harnessing power at higher velocities in the transition region from VIV to galloping and in galloping. Changing K2 onsets and enhances galloping at lower flow velocity and harnesses up to 110% more energy than the case of K1 = K2.

scholarly journals Vortex-Induced Vibration of Catenary Riser: Reduced-Order Modeling and Lock-In Analysis Using Wake Oscillator

2009 ◽  
Author(s):  
Narakorn Srinil ◽  
Marian Wiercigroch ◽  
Patrick O’Brien ◽  
Rae Younger
Keyword(s):  
Interaction Model ◽  
Single Mode ◽  
Dynamic Responses ◽  
Ocean Current ◽  
Flexible Cylinder ◽  
Vortex Induced Vibration ◽  
Reduced Order ◽  
Wake Oscillator ◽  
Lock In ◽  
Multi Mode

A novel reduced-order fluid-structure interaction model for the vortex-induced vibration of catenary riser subject to the ocean current is developed and systematically investigated. The semi analytical-numerical approach accommodates multi-mode nonlinear dynamic responses and accounts for the effect of varying initial curvature of the inclined flexible cylinder. The geometrically nonlinear equations of riser motion are based on a pinned-pinned beam-cable model with bending and extensibility stiffness. The empirical hydrodynamic model is based on a distributed van der Pol wake oscillator which approximates the space-time varying fluid forces. In this initial study, the incoming current flow is assumed to be steady, uniform, unidirectional and perpendicular to the riser initial plane of curvatures. Thus, emphasis is placed on evaluating the riser cross-flow responses due to fluctuating lift forces. A preliminary validation of model and analysis results has been performed. Several insights into the vortex-induced vibration of catenary risers are highlighted through a series of parametric studies. These include the characterization of single-mode vs. multi-mode lock-in, the limitations of a single-mode solution through a convergence analysis which accounts for a varying number of considered riser modes, the prediction of riser maximum response amplitudes, the quantitative/qualitative behaviors of tension- or beam-dominant catenary risers and the overall influence of fluid-riser parameters. Moreover, recent industrial concepts of modes switching/sharing are discussed along with the meaningful effect of Reynolds number.

scholarly journals New Method in Suppressing Vortex-Induced Vibration of Marine Riser

2012 ◽  
Vol 226-228 ◽  
pp. 9-12
Author(s):  
Xing Fu Zhong ◽  
Li Ming Lin ◽  
Ying Xiang Wu ◽  
Shi Ying Shi
Keyword(s):  
Vortex Shedding ◽  
Bluff Body ◽  
New Method ◽  
Ocean Current ◽  
Vortex Induced Vibration ◽  
Marine Risers ◽  
Production Platform ◽  
Marine Engineering ◽  
Viv Suppression ◽  
Relationship Of

Marine risers are key apparatus in connecting the subsea wells to the oil production platform. When the ocean current flow past a riser, the vortex shedding behind riser may induce vibration. If the frequency of vortex shedding is approaching or equal to the natural frequency of riser, the resonance will be generated. Such phenomenon leads to the potential fatigue damage of riser. Therefore, the safety and assurance of marine risers are widely arousing the interest of offshore engineering. In present paper, previous apparatus or methods in suppressing vortex-induced vibration (VIV) of risers used in marine engineering are firstly analyzed, and correspondingly the conditions in design of VIV suppressors are proposed. Based on the Bernoulli equation, the disturbance in flow around a bluff body and the relationship of vortex shedding in span-wise direction, a new method of VIV suppression is proposed. The numerical results have shown that the vibration of risers could be reduced by such disturbance.

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