Comparative Analysis of Vortex-Induced Vibration Models on Risers Caused by Vessel Motion

2020 ◽  
Keyword(s):  
Comparative Analysis ◽  
Vortex Induced Vibration ◽  
Vessel Motion

Vortex-Induced Vibration of Steel Catenary Riser Under Vessel Motion

2014 ◽  
Author(s):  
Jungao Wang ◽  
Shixiao Fu ◽  
Rolf Baarholm
Keyword(s):  
Wave Speed ◽  
Ocean Basin ◽  
Mean Square ◽  
Wall Effects ◽  
Vortex Induced Vibration ◽  
Steel Catenary Riser ◽  
Out Of Plane ◽  
Push Down ◽  
Vessel Motion ◽  
Scr Model

A truncated steel catenary riser (SCR) model was experimentally tested in the ocean basin by oscillating the top end of the model to simulate the heave and surge vessel motion in order to investigate the vortex-induced vibration (VIV) features. Out-of-plane VIV responses were generally analyzed revealing that although the root mean square (RMS) strain distributed rather broadband, the displacement was quite consistent within a narrowband from 0.2D to 0.3D, and the touch-down point (TDP) area was found not to be the place suffering the maximum out-of-plane VIV response due to near wall effects. What’s more, strong wave propagations were firstly reported and summarized as a distinguished feature for VIV of a SCR under vessel motions, and further results reveal that wave propagation during the ‘lift up’ phase was quite different from that during ‘push down’ in terms of both wave speed and ‘power-in’ region location which is assumed to be caused by the tension variation along the model.

Coupled Analysis of Deepwater Floating System Including VIV in Time Domain

2007 ◽  
Author(s):  
Jun-Bumn Rho ◽  
Alexander A. Korobkin ◽  
Jong-Jun Jung ◽  
Hyun-Soo Shin ◽  
Woo-Seob Lee
Keyword(s):  
Finite Element ◽  
Time Domain ◽  
Torsional Stiffness ◽  
Time Step ◽  
Vortex Induced Vibration ◽  
Coupled Equations ◽  
Floating System ◽  
Vessel Motion ◽  
Floating Systems ◽  
The Way

Deepwater floating systems consist of a vessel, risers, and mooring lines. To accurately simulate the floating systems in current, wind, and waves considering (1) bending and torsional stiffness of riser, (2) elongation of the mooring/riser elements, (3) complex end conditions, (4) internal flow effects, and (5) vortex induced vibration, it is necessary to evaluate the vessel motions and mooring/riser behaviors simultaneously in time domain. However, because the size of the system matrix increases significantly as the number of mooring/riser increases, it is quite time-consuming to solve all equations including both mooring/riser and vessel dynamics simultaneously. The present study was performed in order to develop a program for this problem. The 6DOF vessel dynamics is described by the Cummins equation. And the mooring and riser are modeled with the help of finite-element beam. The Newmark method is used as the time marching scheme of the FEM equations for each mooring/riser and the vessel. The coupled equations of the mooring/riser segments and vessel are solved alternatively at each time step. Mooring/riser and the vessel motion affect to each other in the way that the components of the forces at the segment ends are determined as functions of displacements and slopes of them. This procedure makes it possible to consider the coupling effects between vessel and mooring/riser efficiently. Also no iterations are required to match the vessel motion with the riser dynamics. This new approach allows us to use parallel computations and to deal with as many mooring/riser at the same time as necessary. The hydrodynamic forces induced by current are calculated by using the Morison’s formula. The VIV (Vortex Induced Vibration) effects are included in the way that the frequency and the shape of the riser vibration due to VIV are pre-calculated by iterations in the frequency domain. Then the finite element mooring/riser model is modified to consider the hydrodynamic loads including VIV and integrated in the final equations of the floating system in time domain.

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

2016 ◽  
Author(s):  
Jungao Wang ◽  
Shixiao Fu ◽  
Muk Chen Ong ◽  
Huajun Li
Keyword(s):  
Prediction Models ◽  
Ocean Basin ◽  
Dynamic Responses ◽  
Test Cases ◽  
Response Frequency ◽  
Vortex Induced Vibration ◽  
Motion Trajectories ◽  
Out Of Plane ◽  
Future Prediction ◽  
Vessel Motion

A model test of a free-hanging riser under vessel motion was performed in the ocean basin at Shanghai Jiao Tong University to confirm whether vortex-induced vibration (VIV) can happen due to pure vessel motion, to investigate the equivalent current velocity and Keulegan–Carpenter (KC) number effect on the VIV responses and to obtain the correlations for free-hanging riser VIV under vessel motion with VIV for other compliant risers. Top end of the riser was forced to oscillate at given vessel motion trajectories. Fiber Brag Grating (FBG) strain sensors were used to measure the riser dynamic responses. Experimental results confirmed that the free-hanging riser would experience significant out-of-plane VIV. Meanwhile, VIV responses in terms of response amplitude, response frequency and cross-section trajectories under different test cases were further compared and discussed. Most importantly, the correlation among VIV response frequency, vortex shedding pairs and maximum KC number KCmax was revealed. The presented work is supposed to provide useful references for gaining a better understanding on VIV induced by vessel motion, and for the development of future prediction models.

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.

scholarly journals Dominant parameters for vortex-induced vibration of a steel catenary riser under vessel motion

2017 ◽  
Vol 136 ◽  
pp. 260-271 ◽  
Author(s):  
Jungao Wang ◽  
Shixiao Fu ◽  
Carl Martin Larsen ◽  
Rolf Baarholm ◽  
Jie Wu ◽  
...  
Keyword(s):  
Vortex Induced Vibration ◽  
Steel Catenary Riser ◽  
Vessel Motion

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.

scholarly journals Comparative Analysis of Monitoring Methods for Vortex-induced Vibration of Multistage Pressure Reducing Valves

2021 ◽  
Author(s):  
Dongtao Xu ◽  
Ge Chang-rong ◽  
Li Ying ◽  
Liu Yue-juan
Keyword(s):  
Comparative Analysis ◽  
Vortex Shedding ◽  
Pressure Fluctuation ◽  
Lift Coefficient ◽  
Pressure Fluctuations ◽  
Vibration Characteristics ◽  
Monitoring Methods ◽  
Vortex Induced Vibration ◽  
Main Frequency ◽  
Superposition Effect

Abstract In this paper, a multistage pressure reducing valve is presented. The main frequency of vortex-induced vibration is evaluated by monitoring the lift coefficient during vortex shedding and the pressure fluctuation formed after vortex shedding in the flow field. By comparative analysis of two different methods, the number of vortices is relatively small at small openings. Due to the limitations of the location and quantity of monitoring points, accurately locating the most active position where pressure fluctuation occurs is difficult. Monitoring the lift coefficient is more suitable to evaluate the main frequency of vortex-induced vibration. At medium and large openings, due to the increase in the number of vortices, the superposition effect of the pressure fluctuation and the influence of the flow channel shape is more obvious. Monitoring the pressure fluctuation is more appropriate to evaluate the main frequency of vortex-induced vibration the valve. Therefore, a combination of the two methods can more accurately evaluate the vortex-induced vibration characteristics of the valve. When monitoring pressure fluctuation, the position and number of monitoring points directly affect the evaluation accuracy. The pressure fluctuations around the outlet and the multilayer sleeve are more active. It is more meaningful to monitor the pressure fluctuation at these points. The main frequency of the pressure fluctuation at these points better reflects the vortex-induced vibration characteristics of the valve.

Numerical Investigation on Vortex-Induced Vibration caused by Vessel Motion for a Free Hanging Riser Under Small Keulegan-Carpenter Numbers

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Jungao Wang ◽  
Rohan Shabu Joseph ◽  
Muk Chen Ong ◽  
Jasna Bogunović Jakobsen
Keyword(s):  
Numerical Investigation ◽  
Fatigue Damage ◽  
Frequency Model ◽  
Vortex Induced Vibration ◽  
Structural Fatigue ◽  
Marine Risers ◽  
Current Leads ◽  
Vessel Motion ◽  
Oscillatory Current ◽  
Good Agreement

A free-hanging riser (FHR) is a typical riser configuration seen in the disconnected drilling riser, the water-intake riser, and the deep-sea mining riser. In offshore productions, these marine risers will move back and forth in water and further generate an equivalent oscillatory current around themselves, due to the vessel motions. Both in full-scale marine operations and model tests, it has been reported that such oscillatory current leads to riser vortex-induced vibration (VIV) and therefore causes structural fatigue damage. Recently, there have been some attempts to numerically predict vessel motion-induced VIV on the compliant production risers, with emphasize on relatively large Keulegan–Carpenter (KC) numbers. In the real marine operations, the risers experience small KC number scenarios during most of their service life. Therefore, the investigation of vessel motion-induced VIV under small KC number is of great significance, especially considering its contribution to the fatigue damage. In this paper, numerical investigation of VIV of a FHR attached to a floating vessel is carried out. A new response frequency model for vessel motion-induced VIV under small KC numbers is proposed and implemented in vivana. Validation of the proposed numerical methodology is performed against the published experimental results, where a good agreement is achieved.

Mitigation of Pipeline Free Span Fatigue due to Vortex Induced Vibration Using Longitudinally Grooved Suppression

2018 ◽  
Author(s):  
Kanishka Jayasinghe ◽  
Hayden Marcollo ◽  
Andrew E. Potts ◽  
Craig Dillon-Gibbons ◽  
Phillip Kurts ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Vibration Amplitude ◽  
Vortex Induced Vibration ◽  
Suppression Efficiency ◽  
Low Profile ◽  
Actual Field ◽  
Field Deployment ◽  
Viv Suppression ◽  
Seabed Bathymetry ◽  
Subsea Pipelines

Irregular seabed bathymetry around subsea pipelines can lead to the formation of pipeline free spans. When exposed to on-bottom currents these free spans can be subject to Vortex-Induced Vibration (VIV), with consequential effects on the fatigue life of the pipeline. Traditional VIV suppression technologies such as strakes and fairings present installation challenges and durability concerns due to the significant increase in overall diameter associated with the geometric profiles of strakes and fairings. Longitudinally Grooved Suppression (LGS) technology was developed from a concept stage through to field deployment on active drilling risers (Johnstone et. al., OMAE 2017) [1]. The low profile and VIV suppression abilities of LGS present an opportunity for a more effective and operationally beneficial VIV suppression solution for pipeline free spans. Based on existing Class guidance for assessing pipeline free spans, a simplified framework for assessing free spans with LGS under a response based approach is presented. The simplified assessment implied a suppression efficiency (reduction in vibration amplitude) of up to 80%. An alternative comparative analysis using a force based approach was also performed in SHEAR7 of a bare pipeline and a LGS-wrapped pipeline. The requirements for qualification of new VIV mitigation technologies are also addressed and an example of an actual field installation of the device is presented, on an existing pipeline free span with low seabed clearance.

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