Vortex-Induced Vibration and Coincident Current Velocity Profiles for a Deepwater Drilling Riser

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
T. Srivilairit ◽  
L. Manuel
Keyword(s):  
Current Velocity ◽  
Field Data ◽  
Numerical Technique ◽  
Spatial Coherence ◽  
Cross Flow ◽  
Velocity Profiles ◽  
Vortex Induced Vibration ◽  
Deepwater Drilling ◽  
Acceleration Data ◽  
Lock In

The objective of this study is to use full-scale field data on current velocities and riser motions to better understand the behavior of deepwater drilling risers. The data are comprised of riser accelerations and coincident current velocity profiles from the monitoring of vortex-induced vibration (VIV) of a drilling riser located at a 1000 m water depth site. Proper orthogonal decomposition (POD), an efficient numerical technique for characterizing the spatial coherence in a random field, is employed here to identify energetic current profiles. The accuracy resulting from the use of only a limited number of the most important POD modes is studied by comparing measured current velocity profiles with those reconstructed based on a reduced-order truncation. In addition to studying current velocity profiles, riser acceleration data from this deepwater drilling riser are also analyzed. In order to analyze the VIV response of this riser, in-line and cross-flow motions in different data segments are studied. Again, empirical POD procedures are employed—this time to derive energetic spatial vibration modes defining the riser motion. Importantly, these modes are identified without the need for either an analytical/computational model of the riser or any physical dimensions and material properties; instead, they are derived exclusively using the field data. Relationships between riser response and coincident current velocity profiles are investigated, especially for those data segments associated with observed lock-in response.

Vortex-Induced Vibration and Coincident Current Velocity Profiles for a Deepwater Drilling Riser

2007 ◽  
Author(s):  
T. Srivilairit ◽  
L. Manuel
Keyword(s):  
Current Velocity ◽  
Numerical Technique ◽  
Spatial Coherence ◽  
Cross Flow ◽  
Velocity Profiles ◽  
Vortex Induced Vibration ◽  
Deepwater Drilling ◽  
Acceleration Data ◽  
Lock In ◽  
Proper Orthogonal

The objective of this study is to use full-scale field data on current velocities and riser motions to better understand the behavior of deepwater drilling risers. The data are comprised of riser accelerations and coincident current velocity profiles from the monitoring of vortex-induced vibration (VIV) of a drilling riser located at a 1,000-meter water depth site. Proper Orthogonal Decomposition (POD), an efficient numerical technique for characterizing the spatial coherence in a random field, is employed here to identify energetic current profiles. The accuracy resulting from the use of only a limited number of the most important POD modes is studied by comparing measured current velocity profiles with those reconstructed based on a reduced-order truncation. In addition to studying current velocity profiles, riser acceleration data from this deepwater drilling riser are also analyzed. In order to analyze the VIV response of this riser, in-line and cross-flow motions in different data segments are studied. Again, empirical POD procedures are employed—this time to derive energetic spatial vibration modes defining the riser motion. The relationship between riser response and coincident current velocity profiles is investigated, especially for those data segments associated with observed lock-in response.

On Vortex Induced Vibration in Two-Degree-of-Freedoms of Flexible Cylinders

2011 ◽  
Author(s):  
Weiping Huang ◽  
Weihong Yu
Keyword(s):  
Natural Frequency ◽  
Current Velocity ◽  
Coupling Effect ◽  
Great Influence ◽  
Cross Flow ◽  
Flexible Cylinder ◽  
Fluid Structure ◽  
Vortex Induced Vibration ◽  
Flow Vortex ◽  
Lock In

In this paper, an experimental study on the in-line and cross-flow vortex-induced vibration (VIV) of flexible cylinders is conducted. The relationship of two-degree-of-freedoms of vortex-induced vibration of flexible cylinders is also investigated. The influence of natural frequency of flexible cylinders on vortex shedding and VIV are studied through the experiment in this paper. Finally, A nonlinear model, with fluid-structure interaction, of two-degree-of-freedom VIV of flexible cylinders is proposed. It is shown that the ratio of the frequencies and amplitudes of in-line and cross flow VIV of the flexible cylinders changes with current velocity and Reynolds number. The natural frequency of flexible cylinder has great influence on the vortex-induced virbation due to the strong fluid-structure coupling effect. Under given current velocity, the natural frequency of flexible cylinder determines its forms of vibration (in circular or ‘8’ form). The ratio of the VIV frequencies is 1.0 beyond the lock in district and 2.0 within the lock in district respectively. And the ratio of the VIV amplitudes is 1.0 beyond the lock in district and 1/3 to 2/3 within the lock in district. The results from this paper indicates that in-line vibration should be considerated when calculating the vibration response and fatigue damage.

Managing Vortex Induced Vibration in Well Jumper Systems

2008 ◽  
Author(s):  
Kenneth Bhalla ◽  
Lixin Gong
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Cross Flow ◽  
Mitigation Measures ◽  
Mode Shapes ◽  
Bottom Current ◽  
Vortex Induced Vibration ◽  
Flow Response ◽  
Out Of Plane ◽  
Lock In

The purpose of this paper is to present a method that has been developed to identify if vortex induced vibration (VIV) occurs in well jumper systems. Moreover, a method has been developed to determine when VIV mitigation measures such as strakes are required. The method involves determining the in-plane and out-of-plane natural frequencies and mode shapes. The natural frequencies are then used, in conjunction with the maximum bottom current expected at a given location to determine if suppression is required. The natural frequency of a jumper system is a function of many variables, e.g. span length, leg height, pipe diameter and thickness, buoyancy placement, buoyancy uplift, buoyancy OD, insulation thickness, and contents of the jumper. The suppression requirement is based upon calculating a lower bound lock-in current speed based upon an assumed velocity bandwidth centered about the lock-in current. The out-of-plane VIV cross-flow response is produced by a current in the plane of the jumper; whereas the in-plane VIV cross-flow response is produced by the out-of-plane current. Typically, the out-of-plane natural frequency is smaller than the in-plane natural frequency. Jumpers with small spans have higher natural frequencies; thus small span jumpers may require no suppression or suppression on the vertical legs. Whereas, larger span jumpers may require no suppression, suppression on the vertical legs or suppression on all the legs. The span of jumper systems (i.e. production, water injection, gas lift/injection ...) may vary in one given field; it has become apparent that not all jumper systems require suppression. This technique has allowed us to recognize when certain legs of a given jumper system may require suppression, thus leading to a jumper design whose safety is not compromised while in the production mode, as well as minimizing downtime and identifying potential savings from probable fatigue failures.

Study on the Test Results of Cross-Flow Vortex-Induced Vibration of a Towed Circular Cylinder

2014 ◽  
Author(s):  
Wei-Wu Wu ◽  
Quan-Ming Miao ◽  
Yan-Xia Wang
Keyword(s):  
Circular Cylinder ◽  
Natural Frequency ◽  
Cross Flow ◽  
Test Cases ◽  
Test Results ◽  
Vortex Induced Vibration ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Flow Vortex ◽  
Lock In

This paper gives a review on VIV experimental research. A detailed introduction of the experimental study on the cross-flow vortex-induced vibration of a towed circular cylinder in CSSRC’s towing tank is presented and classical VIV phenomena are explained and analyzed in this study. However, some results which are much different from those in the classical literatures in the past few decades are observed at the same time. For example, instead of reduced velocity Ur from 5 to 8, the “lock-in” region happened in the reduced velocity ranged from 10 to 14 in our tests, where the reduced velocity is calculated by the natural frequency. The non-dimensional frequency (oscillation frequency over natural frequency) of about 1.8 in the “lock-in” region is also different from that of 1.0 in the classical literatures. Interestingly, the author found that some of the results given by Moe and Wu (1990), Sarpkaya (1995), Govardhan and Williamson (2000), Pan zhiyuan (2005) and so on, reported the similar phenomenon. Since above listed papers have the same points of view, whether can we say that the results in this paper are possible for the case of low mass ratio. To conclude that, however, many questions need to be answered. In an effort to gain a better understanding of VIV phenomenon, this paper presents results of further analysis on the test cases and parameters.

scholarly journals Vortex-induced vibration and galloping of prisms with triangular cross-sections

2017 ◽  
Vol 817 ◽  
pp. 590-618 ◽  
Author(s):  
Banafsheh Seyed-Aghazadeh ◽  
Daniel W. Carlson ◽  
Yahya Modarres-Sadeghi
Keyword(s):  
Natural Frequency ◽  
Cross Sections ◽  
Flow Direction ◽  
Cross Flow ◽  
Low Frequency ◽  
Limited Range ◽  
Triangular Prism ◽  
Vortex Induced Vibration ◽  
Lock In ◽  
Type Response

Flow-induced oscillations of a flexibly mounted triangular prism allowed to oscillate in the cross-flow direction are studied experimentally, covering the entire range of possible angles of attack. For angles of attack smaller than $\unicode[STIX]{x1D6FC}=25^{\circ }$ (where $0^{\circ }$ corresponds to the case where one of the vertices is facing the incoming flow), no oscillation is observed in the entire reduced velocity range tested. At larger angles of attack of $\unicode[STIX]{x1D6FC}=30^{\circ }$ and $\unicode[STIX]{x1D6FC}=35^{\circ }$, there exists a limited range of reduced velocities where the prism experiences vortex-induced vibration (VIV). In this range, the frequency of oscillations locks into the natural frequency twice: once approaching from the Strouhal frequencies and once from half the Strouhal frequencies. Once the lock-in is lost, there is a range with almost-zero-amplitude oscillations, followed by another range of non-zero-amplitude response. The oscillations in this range are triggered when the Strouhal frequency reaches a value three times the natural frequency of the system. Large-amplitude low-frequency galloping-type oscillations are observed in this range. At angles of attack larger than $\unicode[STIX]{x1D6FC}=35^{\circ }$, once the oscillations start, their amplitude increases continuously with increasing reduced velocity. At these angles of attack, the initial VIV-type response gives way to a galloping-type response at higher reduced velocities. High-frequency vortex shedding is observed in the wake of the prism for the ranges with a galloping-type response, suggesting that the structure’s oscillations are at a lower frequency compared with the shedding frequency and its amplitude is larger than the typical VIV-type amplitudes, when galloping-type response is observed.

Features of Vortex-Induced Vibration in Oscillatory Flow

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Shixiao Fu ◽  
Jungao Wang ◽  
Rolf Baarholm ◽  
Jie Wu ◽  
C. M. Larsen
Keyword(s):  
Wavelet Transformation ◽  
Oscillatory Flow ◽  
Cross Flow ◽  
Ocean Basin ◽  
Mode Transition ◽  
Time Sharing ◽  
Flexible Cylinder ◽  
Vortex Induced Vibration ◽  
Flow Features ◽  
Lock In

Vortex-induced vibration (VIV) in oscillatory flow is experimentally investigated in the ocean basin. The test flexible cylinder was forced to harmonically oscillate in various combinations of amplitude and period with Keulegan-Carpenter (KC) number between 26 and 178 in three different maximum reduced velocities, URmax=4, URmax=6.5, and URmax=7.9 separately. VIV responses at cross-flow (CF) direction are investigated using modal decomposition and wavelet transformation. The results show that VIV in oscillatory flow is quite different from that in steady flow; features, such as intermittent VIV, hysteresis, amplitude modulation, and mode transition (time sharing) are observed. Moreover, a VIV developing process including “building-up,” “lock-in,” and “dying-out” in oscillatory flow, is further proposed and analyzed.

scholarly journals Influence of Frequency Ratio on the Hydroelastic Response of a Cylinder with Degrees of Freedom under Vortex Induced Vibration

2019 ◽  
Vol 8 (9S3) ◽  
pp. 307-312
Keyword(s):  
Natural Frequency ◽  
Frequency Ratio ◽  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Vortex Induced Vibration ◽  
Ocean Environment ◽  
Hydroelastic Response ◽  
Lock In

Vortex induced vibration of cylindrical structures is an extensively researched topic. Most of the studies have concentrated on the response of the cylinder in the cross flow (CF) direction. In a realistic ocean environment, structures such as drilling and marine risers are more or less free to vibrate both in CF and in line (IL) directions. It has also been observed that the IL vibrations have significant influence on the CF response. Interaction between the responses in inline and cross flow directions has still been not fully understood. This paper addresses the same through a simplified numerical method for understanding the interaction between these two responses using two dimensional computational fluid dynamics (CFD) simulations. Here analyzes two cases have been considered; where in the cylinder is modeled with two different values of ratio of natural frequency of the cylinder in the IL direction to that in the CF direction. The trends of variation of hydrodynamic and structural parameters have been analyzed to comprehend the effect of directional natural frequency ratio on the cylinder response and hydrodynamic force coefficients. The shedding pattern has also been studied in this paper. An increase by 18% in the value of the lift coefficient and 38 % of that in the drag coefficient has been observed when the frequency ratio is increased from 1 to 2. The results show that the cylinder with frequency ratio 2 is more prone to lock in vibration. This phenomenon may be related to the shifting of shedding pattern from 2S to P + S mode when the frequency ratio is 2.

scholarly journals Experimental Investigation on Vortex-Induced Vibration of a Flexible Pipe under Higher Mode in an Oscillatory Flow

2020 ◽  
Vol 8 (6) ◽  
pp. 408 ◽  
Author(s):  
Haojie Ren ◽  
Mengmeng Zhang ◽  
Jingyun Cheng ◽  
Peimin Cao ◽  
Yuwang Xu ◽  
...  
Keyword(s):  
Oscillatory Flow ◽  
Cross Flow ◽  
Dominant Frequency ◽  
Ocean Basin ◽  
Dominant Mode ◽  
Flexible Pipe ◽  
Vortex Induced Vibration ◽  
Displacement Reconstruction ◽  
Vessel Motion ◽  
Lock In

Different from the previous studies of the vortex-induced vibration (VIV) dominated by first mode of flexible pipe in an oscillatory flow, the features of a higher mode dominated are experimentally investigated in the ocean basin. The flexible pipe is forced to harmonically oscillate with different combinations of a period and amplitude. The design dominant mode consists of first and second modes under the maximum reduced velocity (VR) of approximately 5.5 with a KC number ranging from 22 to 165. The VIV responses between only the excited first mode and the excited higher mode are compared and studied using displacement reconstruction and wavelet transform methods. The discrepancies of spatial and temporal response between smaller and larger KC numbers (KC = 56 and 121) are first observed. The strong alternate mode dominance and lock-in phenomena occur in the case of larger KC numbers, while they cannot be observed in the case of smaller KC numbers under higher modes. The VIV dominant frequency in the in-line (IL) direction is found to be always triple the oscillatory flow frequency and not twice that in the cross flow (CF) direction. The dominant frequency in the CF direction can be predicted by the Strouhal law, and the Strouhal number is approximately 0.18 under VR = 5.5, which is not affected by the excited mode. Moreover, differences of response motion trajectory are also revealed in this paper. The present work improves the basic understanding of vessel motion induced VIV and provides helpful references for developing prediction methods of VIV in an oscillatory flow.

scholarly journals Fluid-Structure Energy Transfer of a Tensioned Beam Subject to Vortex-Induced Vibrations in Shear Flow

2011 ◽  
Author(s):  
Remi Bourguet ◽  
Michael S. Triantafyllou ◽  
Michael Tognarelli ◽  
Pierre Beynet
Keyword(s):  
Energy Transfer ◽  
Shear Flow ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Structural Vibrations ◽  
Fluid Structure ◽  
Vortex Induced Vibrations ◽  
Linear Shear ◽  
Structural Responses ◽  
Lock In

The fluid-structure energy transfer of a tensioned beam of length to diameter ratio 200, subject to vortex-induced vibrations in linear shear flow, is investigated by means of direct numerical simulation at three Reynolds numbers, from 110 to 1,100. In both the in-line and cross-flow directions, the high-wavenumber structural responses are characterized by mixed standing-traveling wave patterns. The spanwise zones where the flow provides energy to excite the structural vibrations are located mainly within the region of high current where the lock-in condition is established, i.e. where vortex shedding and cross-flow vibration frequencies coincide. However, the energy input is not uniform across the entire lock-in region. This can be related to observed changes from counterclockwise to clockwise structural orbits. The energy transfer is also impacted by the possible occurrence of multi-frequency vibrations.

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