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Showing papers on "Vortex-induced vibration published in 2005"


Journal ArticleDOI
TL;DR: A review of mathematical models used to investigate vortex-induced vibration (VIV) of circular cylinders is given in this article, with a focus on single-degree-of-freedom (SFOF) models.

602 citations


Journal ArticleDOI
TL;DR: In this paper, measurements of the vortex-induced vibrations of a model vertical tension riser in a stepped current were described, and the response in the in-line and cross-flow directions was inferred from measurements of bending strains at 32 equally spaced points along its length.

321 citations


Book ChapterDOI
01 Jan 2005

76 citations


Journal ArticleDOI
TL;DR: In this article, the E-CUSP upwind scheme is extended to the moving grid system and is applied to calculate the flow-induced vibration based on a fully coupled fluid-structure interaction methodology.

66 citations


Journal ArticleDOI
TL;DR: In this article, both linear and non-linear analyses of sheet flutter in a narrow passage caused by fluid-structure interaction are presented, where the sheet is considered as a combination of massless beam elements, springs and discrete mass particles, in which the mass of each particle and spring coefficients are calculated based on the beam model.

37 citations


Journal ArticleDOI
TL;DR: In this paper, a monitored cylinder equipped with two accelerometers inside was flexibly mounted in a water tunnel, surrounded by one to six identical cylinders elastically mounted in rotated triangular pattern.

33 citations


Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this paper, the initial results from vortex-induced-vibration (VIV) field testing of a long, flexible, model riser at a high mode number were presented.
Abstract: This paper presents the initial results from vortex-induced-vibration (VIV) field testing of a long, flexible, model riser at a high mode number. The experiments were designed to gain understanding of the dynamic behavior of a long riser in uniform flow responding at mode numbers ranging from 10 to 25 in crossflow vibration. The observed reduced velocity and root-mean-square (RMS) displacement-response levels were reported. Mean values of the drag coefficient, C d , and hydrodynamic damping derived from measured data were compared with calculated values from formulas commonly used in engineering design of offshore systems.

30 citations


Patent
18 Mar 2005
TL;DR: In this paper, the authors remotely install vortex-induced vibration reduction and drag reduction devices on elongated structures in flowing fluid environments, such as clamshell-shaped strakes, shrouds, fairings, sleeves and flotation modules.
Abstract: Methods for remotely installing vortex-induced vibration (VIV) reduction and drag reduction devices on elongated structures in flowing fluid environments. The devices installed can include clamshell-shaped strakes, shrouds, fairings, sleeves and flotation modules.

25 citations


Journal ArticleDOI
TL;DR: In this paper, the Bogolyubov-Mitropolsky method is used to find approximate periodic solutions to the system of nonlinear equations that describes the large-amplitude vibrations of cylindrical shells interacting with a fluid flow.
Abstract: The Bogolyubov-Mitropolsky method is used to find approximate periodic solutions to the system of nonlinear equations that describes the large-amplitude vibrations of cylindrical shells interacting with a fluid flow. Three quantitatively different cases are studied: (i) the shell is subject to hydrodynamic pressure and external periodical loading, (ii) the shell executes parametric vibrations due to the pulsation of the fluid velocity, and (iii) the shell experiences both forced and parametric vibrations. For each of these cases, the first-order amplitude-frequency characteristic is derived and stability criteria for stationary vibrations are established

20 citations


Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this article, it was found that six to seven simulation planes are required per half-wavelength of pipe vibration in order to obtain convergence, despite the questionable usage of simulation planes at high angles to the flow direction.
Abstract: The paper reports results from two strip theory CFD investigations of the Vortex-Induced Vibrations of model riser pipes. The first investigation is concerned with the vibrations of a vertical riser pipe that was subjected to a stepped current profile. An axial spatial resolution study was conducted to determine the number of simulation planes required to achieve tolerably converged numerical solutions. It was found that six to seven simulation planes are required per half-wavelength of pipe vibration in order to obtain convergence. The second investigation is concerned with the simultaneous in-plane and out-of-plane vibrations of a model Steel Catenary Riser that was subjected to a uniform current profile. The pipe’s simulated vibrations were found to agree very well with those determined experimentally. This result was achieved despite the questionable usage of simulation planes at high angles to the flow direction.© 2005 ASME

19 citations


Journal ArticleDOI
TL;DR: In this article, the dynamics of a low-viscosity fluid layer inside a rotating cylinder under transverse translational vibration relative to the rotation axis is investigated experimentally, and a novel vibrational effect, the generation of intense azimuthal fluid flows with velocities comparable with the cavity rotation velocity, is revealed.
Abstract: The dynamics of a low-viscosity fluid layer inside a rotating cylinder under transverse translational vibration relative to the rotation axis is investigated experimentally. A novel vibrational effect, the generation of intense azimuthal fluid flows with velocities comparable with the cavity rotation velocity, is revealed. The structure and intensity of the vibrational flows and the flow transformation with variation of the determining dimensionless parameters (frequency and vibrational acceleration) are studied.

Journal ArticleDOI
TL;DR: In this paper, a closed-loop control algorithm with the introduction of Lorentz forces has been applied successfully in controlling of the vortex-induced vibration of a circular cylinder has been simulated two-dimensionalally through the direct numerical simulation at Reynolds number Re=100 and 200.

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this article, a 1/3 scale flow-induced vibration test facility that simulates the hot-leg piping of the JNC sodium-cooled fast reactor (JSFR) is used to investigate the pressure fluctuations of the pipe, where the high velocity fluid flows inside the piping.
Abstract: A 1/3 scale flow-induced vibration test facility that simulates the hot-leg piping of the JNC sodium-cooled fast reactor (JSFR) is used to investigate the pressure fluctuations of the pipe, where the high velocity fluid flows inside the piping. By the measurement of the pressure drop in the elbow piping while changing the Reynolds number, the similarity law of this model is confirmed. To evaluate the flow-induced vibrations for the hot-leg and cold-leg pipes, the random force distributions along the pipe and their correlations are measured with pressure sensors in a water loop. It is found that a flow velocity-dependent periodic phenomenon in the rear region of the elbow, and the maximum flow-induced random vibration force in the pipe are observed in the region of flow separation downstream the elbow. Finally, a design method is proposed with power spectral densities of the pressure fluctuations classified into four sections, correlation lengths in the axial direction divided into three sections, and with correlation lengths in the tangential direction into four sections.Copyright © 2005 by ASME

Journal ArticleDOI
TL;DR: In this article, the effect of the nature of the flow separation point on the vortex-induced vibration of an elastic square cylinder on fixed supports at both ends, in a uniform cross flow was measured using fiber-optic Bragg sensors.
Abstract: The vortex-induced structural vibration of an elastic square cylinder, on fixed supports at both ends, in a uniform cross flow was measured using fiber-optic Bragg grating sensors. The measurements are compared to those obtained for an elastic circular cylinder of the same hydraulic diameter in an effort to understand the effect of the nature (fixed or oscillating) of the flow separation point on the vortex-induced vibration. It is found that a violent vibration occurs at the third-mode resonance when the vortex-shedding frequency coincides with the third-mode natural frequency of the fluid-structure system, irrespective of the cross-sectional geometry of the cylinder. This is in distinct contrast to previous reports of flexibly supported rigid cylinders, where the first-mode vibration dominates, thus giving little information on the vibration of other modes. The resonance behavior is neither affected by the incidence angle (a) of the free stream, nor by the nature of the flow separation point. However, the vibration amplitude of the square cylinder is about twice that of the circular cylinder even though theflexural rigidity of the former is larger. This is ascribed to a difference in the nature of the flow separation point between the two types of structures. The characteristics of the effective modal damping ratios, defined as the sum of structural and fluid damping ratios, and the system natural frequencies are also investigated. The damping ratios and the system natural frequencies vary little with the reduced velocity at α=0 deg, but appreciable at α≥15 deg; they further experience a sharp variation, dictated by the vortex-shedding frequency, near resonance.

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this article, the authors conducted flow-induced vibration experiments on a valve with a very weak support and investigated the characteristics of the vibration mode under the middle-opening condition, and found that under the specific lift condition of the region where rotating pressure fluctuation occurs, lock-in phenomena between the rotating pressure fluctuations and the valve vibration occur and large-amplitude vibration can be seen.
Abstract: In some cases, a steam control valve in a power plant causes a large vibration of the piping system under partial valve opening. For rationalization of maintenance and management of a plant, it is favorable to optimize the valve geometry to prevent such vibration. However, it is difficult to understand the flow characteristics in detail only from experiments because the flow around a valve has a complex 3D structure and becomes supersonic (M>1). Therefore, it is useful to combine experiments and CFD (Computational Fluid Dynamics) for the clarification of the cause of vibration and optimization of valve geometry. In previous researches involving experiment and CFD calculation using “MATIS” code, we found that an asymmetric flow attached to the valve body (named “valve-attached flow”) occurs and pressure increases where the valve-attached flow collides with the flow from the opposite side under the middle opening condition. This high-pressure region rotates circumferentially (named “rotating pressure fluctuation”) and causes cyclic side load on the valve body. However, because we assumed the valve support is rigid, we cannot clarify the interaction between the rotating pressure fluctuation and the valve vibration when the valve stiffness is small. Thus, in this paper, we conducted flow-induced vibration experiments on a valve with a very weak support and investigated the characteristics of the vibration mode under the middle-opening condition. As a result, under the specific lift condition of the region where rotating pressure fluctuation occurs, lock-in phenomena between the rotating pressure fluctuation and the valve vibration occur and large-amplitude vibration can be seen.Copyright © 2005 by ASME



Journal Article
TL;DR: In this paper, the effect of the internal flow velocity on the response of VIV and the fatigue life of the riser was analyzed using finite-element method, and it was shown that when the natural frequency of riser is near the vortex shedding frequency due to the change of initial velocity, response of the VIV will increase and fatigue life will decrease greatly.
Abstract: Based on Biolley‘s wake oscillator model, the differential equation for the response of the vortex-induced vibrations (VIV) of the riser is derived. The effect of the internal flowing fluid and the external marine environmental condition are taken into account. The effect of the internal flowing fluid on the response of VIV of the riser is studied using finite-element method. The fatigue life of the marine riser is analyzed by Miner’s theory. The effect of the internal flow velocity on the response of VIV and the fatigue life of the riser is analyzed. Results show that when the natural frequency of the riser is near the vortex shedding frequency due to the change of initial velocity, the response of the VIV will increase and the fatigue life of the riser will decrease greatly.

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this article, the results from forced IL oscillation experiments of a smooth, rigid cylinder in uniform flow are presented as dynamic in-line coefficients for the pure IL regime, i.e. reduced velocity between 1 and 4, at Reynolds number 24.000.
Abstract: For subsea pipelines installed in areas with uneven seabed free spans may occur and fatigue failure due to vortex induced vibrations (VIV) is one of the main concerns related to these spans. In order to install pipelines in such areas the safety against fatigue failure from in-line (IL) and cross-flow (CF) VIV must be documented. Although maximum oscillation amplitudes in the IL direction are considerably smaller than the maximum amplitudes in the CF direction, the IL fatigue damage normally prevails and may limit the allowable span length. The reason for this is that the IL vibrations initiate at a lower current velocity (i.e., reduced velocity) than the CF vibrations and would hence be excited for a longer period of time. Prediction tools for VIV may be split into parametric Response Models such as described in DNV-RP-F105 and methods based on empirical coefficients such as SHEAR7 and VIVANA. Methods based on force coefficient have until recently been limited to CF VIV due to lack of hydrodynamic coefficients for IL response. This paper presents results from forced IL oscillation experiments of a smooth, rigid cylinder in uniform flow. The results are presented as dynamic in-line coefficients for the pure IL regime, i.e. reduced velocity between 1 and 4, at Reynolds number 24.000. The results are compared with IL results from free oscillation experiments found in the literature.Copyright © 2005 by ASME

Chen Wen-qu1
01 Jan 2005
TL;DR: In this paper, two circular cylinders in tandem arrangement elastically mounted with a mass-spring-damping system were studied by solving the primitive variable Navier-Stokes equations incorporating the Arbitrary Lagrangian Eulerian (ALE) method.
Abstract: Flow-induced vibration of two circular cylinders in tandem arrangement elastically mounted with a mass-spring-damping system was studied by solving the primitive variable Navier-Stokes equations incorporating the Arbitrary Lagrangian-Eulerian (ALE) method. The convection term and dissipation term were discretized using the third-order upwind compact scheme and the fourth-order central compact scheme, respectively. The typical spacing between the cylinders is 4 diameters, which is close to the critical value. The dynamic response of the vibrations on two cylinders with two-degree-of-freedom motion is different from that of an isolated cylinder, and also different from that of a cylinder vibrating in the wake of a fixed upstream one. Different flow patterns were found in the wake, and proved to be relevant to the discontinuities observed in the response of the oscillatory cylinders.

Deng, Jian, Ren, An-lu, Chen, Wen-qu 
01 Jan 2005
TL;DR: In this article, the authors studied flow-induced vibration of two circular cylinders in tandem arrangement elastically mounted with a mass-spring-damping system by solving the primitive variable Navier-Stokes equations incorporating the Arbitrary Lagrangian-Eulerian (ALE) method.
Abstract: Flow-induced vibration of two circular cylinders in tandem arrangement elastically mounted with a mass-spring-damping system was studied by solving the primitive variable Navier-Stokes equations incorporating the Arbitrary Lagrangian-Eulerian (ALE) method.The convection term and dissipation term were discretized using the third-order upwind compact scheme and the fourth-order central compact scheme, respectively.The typical spacing between the cylinders is 4 diameters, which is close to the critical value.The dynamic response of the vibrations on two cylinders with two-degree-of-freedom motion is different from that of an isolated cylinder, and also different from that of a cylinder vibrating in the wake of a fixed upstream one.Different flow patterns were found in the wake, and proved to be relevant to the discontinuities observed in the response of the oscillatory cylinders.

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this article, an analytical model based on disk rotary dynamics including the functional air bearing stiffness and bearing damping of the air shroud was developed to evaluate the effectiveness of the shroud on the disk vibration suppression.
Abstract: The growth trend of the recording density of hard disk drives (HDD) makes a demand for higher head positioning accuracy at faster disk rotation speed. However, the higher rotational speed of disk generates the greater flow induced vibration known as disk flutter, which causes the increase of the track misregistration (TMR). In this paper, air shroud is evaluated with numerical simulation and analytical results for disk vibration suppression. Firstly, the finite element model (FEM) for computational fluid dynamics (CFD) analysis based on the 3D Navier Stokes equations is built up for air shroud. The turbulence air flow velocity and the pressure distribution are simulated and evaluated for the air shroud with different opening. The parameters describing the air bearing function of the shroud, such as the stiffness and damping, are calculated based on the simulation results. It is found that with the decreasing of the shroud opening angle, the air flow has a more uniform flow pattern with higher bearing stiffness and better damping. The CFD simulation results also indicate that the bearing stiffness and damping of the air shroud can be further increased with smaller shroud-disk spacing of the air shroud. To evaluate the effectiveness of the air shroud on the disk vibration suppression, an analytical model based on disk rotary dynamics including the functional air bearing stiffness and bearing damping of the air shroud is developed. The analytical results demonstrate 15.8% suppression in disk vibration amplitude for the flutter vibration mode at resonance frequency 550 Hz, mainly by the damping effect of the air shroud

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this paper, an empirical model for the analysis of vortex induced vibrations (VIV) of multi-span pipelines is presented, based on a non-linear finite element method, and the dynamic analysis is carried out in time domain.
Abstract: Pipelines are the most convenient and safe medium of oil and gas transportation from offshore fields. Such pipelines will often have free spans when passing through areas with uneven sea floor. These free spans may experience vibrations due to vortex shedding when subjected to ocean current, which may lead to unacceptable accumulation of fatigue damage. The bottom topography may result in multi-span pipelines with short contact area between adjacent spans. Such neighbor spans may interact dynamically, meaning that the response of one span can not be found unless its neighbors are taken into account. The purpose of the present paper is to illustrate possible consequences of interaction and present a consistent method for classification of interaction. Two aspects of interaction are studied, namely the possible energy transfer due to hydrodynamic forces from one span to its neighbor of different length, and how the stiffness properties and length of the contact area between spans influence the interaction. The first aspect is studied by using an empirical model for the analysis of vortex induced vibrations (VIV) of multi-span pipelines. This model applies a frequency domain solution procedure that must describe the interaction between the pipe and the seafloor by linear theory. It was observed from the results that the spans interact dynamically, and the distribution of lift forces along the length of pipe shows that energy is transferred from the span with smallest amplitude to the span with largest amplitude. The second aspect is studied by use of an analysis model where the contact between pipe and seafloor has a more realistic representation. This model is based on a non-linear finite element method, and the dynamic analysis is carried out in time domain. By using this model it is possible to characterize the mechanical coupling between the spans. A systematic study illustrates how seafloor stiffness and local profile of the seafloor will influence the interaction.Copyright © 2005 by ASME

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this article, the authors carried out an experimental investigation on the fluid-structure interaction caused by Karman vortices in the wake of a truncated 2D hydrofoil.
Abstract: In the present study, we have carried out an experimental investigation on the fluid-structure interaction caused by Karman vortices in the wake of a truncated 2D hydrofoil. The instrumentation involves a high frequency accelerometer and high speed visualisation. The mechanical response of the hydrofoil to the hydrodynamic excitation is monitored with the help of a portable digital vibrometer. Moreover, a specific optical device is developed to investigate the dynamic of the cavitating wake. The survey of the generation frequency of the Karman vortices with respect to the flow velocity reveals a Strouhal behaviour and three resonances of the hydrofoil. Out of hydro-elastic coupling conditions, the observation of the vortex structures reveals a strong 3D pattern despite the fact that the hydrofoil is 2D. The maximum fluid-structure interaction occurs for the torsional mode where lock-in is observed for upstream velocities ranging from 11 to 13 m/s. In this case, the vortices exhibit a 2D structure. The cavitation occurrence within the core of Karman vortices leads to a significant increase of their generation frequency. We have observed that hydrofoil resonance may be whether avoided or triggered by cavitation development. The study of the Karman vortices dynamic reveals that their advection velocity increases (4%) with the development of the wake cavitation meanwhile their streamwise spacing decreases.

01 Jan 2005
TL;DR: In this article, the effect of internal flow on the vortex-induced vibration of the free spans of a submarine free spanning pipeline was investigated and the Newmark method combined with simple iteration was used to solve the system of equations.
Abstract: At present, most researches on the vortex-induced vibration of submarine free spanning pipelines ignore the effect of internal flowing fluid; furthermore, there are no research reports considering the coupling effect of internal and external fluid with the free span. In this paper, combining Iwan's wake oscillator model with the differential equation derived for the dynamic response of submarine free spanning pipelines with inclusion of internal flow, the pipe-fluid coupling equations are developed to investigate the effect of internal flow on the vortex-induced vibration of the free spans. The finite element approximation is implemented to derive the matrix equations of equilibrium. The Newmark method combined with simple iteration is used to solve the system of equations. The results indicate that the internal fluid flow may cause the shift of resonance band to the lower frequency and a slight decrease in the peak value; the effect will be more pronounced with the increase of the span length and can be weakened in the presence of the axial tension.

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this paper, a multi-strip numerical method combining solution of the incompressible Reynolds Averaged Navier-Stokes (RANS) equations with a finite-element structural dynamics response has been developed previously to analyze the flow-structure interaction of a flexible riser subjected to fixed and non-uniform, two-dimensional shear currents.
Abstract: A multi-strip numerical method combining solution of the incompressible Reynolds Averaged Navier-Stokes (RANS) equations with a finite-element structural dynamics response has been developed previously to analyze the flow-structure interaction of a flexible riser subjected to fixed and non-uniform, two-dimensional shear currents. In this paper, we expand on the previous work using the tool to numerically compute the VIV loads and motions of a vertically tensioned riser in a stepped current. The flow conditions for this stepped current configuration were chosen to match a set of laboratory experiments carried out in the Delta Flume at Delft Hydraulics. In addition to the stepped current, the multi-strip method was extended to accommodate a three-dimensional skew current exposed to a vertically tensioned riser. Note that in this case, the skew current is non-uniform in both direction and magnitude, and the flow conditions and riser configuration were chosen to match a set of rotating-rig experiments made by Marintek. For both configurations (stepped and skewed currents), comparisons of in-line and transverse VIV displacements are presented between numerical and experimental results.Copyright © 2005 by ASME

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this paper, the authors developed a reliable numerical method that can deal economically with a large number of rigid particles moving in an incompressible Newtonian fluid at a reasonable cost.
Abstract: In an attempt to develop a reliable numerical method that can deal economically with a large number of rigid particles moving in an incompressible Newtonian fluid at a reasonable cost, we consider two fictitious-domain methods: a Constant-density Explicit Volumetric forcing method (CEV) and a Variable-density Implicit Volumetric forcing method (VIV). In both methods, the mutual interaction between the solid and the fluid phase is taken into account by an additional body force term to the Navier-Stokes equations, but the physical meaning of the forcing is different for the two methods. In the CEV method, which is built on a constant-density Navier-Stokes solver, the net forcing added to the fluid is generally not zero, and must be cancelled by applying Newton’s first law to a rigid particle template which has the same shape as the rigid particle and carries the “excess mass” of the rigid particle, i.e. the excess over the mass of the displaced fluid. The “target velocity” to which one forces the velocity within the particle is evaluated through the equation of motion for the rigid particle template. In the VIV method, built on a variable-density incompressible flow solver, the rigid particle (angular) velocity is determined by averaging the (angular) momentum, within the particle domain, of the fractional-step velocity field, and the net forcing is zero. By design, this method does not require any rigid particle template equations, so it can be applied for both neutral and non-neutral density ratios without any difficulties. We consider two test problems with single freely moving circular disks: a disk falling in quiescent fluid, and a disk in Poiseuille channel flow. At near-neutral density ratios, the CEV method is found to perform better, while the VIV method yields more accurate results at higher relative density ratios.Copyright © 2005 by ASME

Proceedings ArticleDOI
01 Jan 2005
TL;DR: In this paper, the authors present experimental results concerning flow-induced oscillations of rigid-circular cylinders in tandem, and the results for an isolated cylinder are in accordance with other measurements in the literature for m * ≈ 2 and m* ≈ 8.
Abstract: This paper presents experimental results concerning flow-induced oscillations of rigid-circular cylinders in tandem. Preliminary results are presented: new measurements on the dynamic response oscillations of an isolated cylinder and flow interference of two cylinders in tandem are shown. The oscillations are due to vortex-induced vibrations (VIV). Models are mounted on an elastic base fitted with flexor blades and instrumented with strain gages. The base is fixed on the test section of a water channel facility. The flexor blades possess a low damping characteristic [ζ ≈ 0.008 and less] and they are free to oscillate only in the cross-flow direction. The Reynolds number of the experiments is from 3,000 to 13,000 and reduced velocities, based on natural frequency in still water, range up to 12. The interference phenomenon on flow-induced vibrations can be investigated by conducting experiments in two ways: first, the upstream cylinder is maintained fixed and the downstream one is mounted on the elastic base; subsequently, an investigation will be carried out letting both cylinders oscillate transversally. The results for an isolated cylinder are in accordance with other measurements in the literature for m* ≈ 2 and m* ≈ 8. For the tandem arrangement (m* ≈ 2), the trailing cylinder oscillation presents what previous researchers have termed interference galloping behaviour for a centre-to-centre gap spacing ranging from 3·0D to 5·6D. These initial results validate the experimental set up and lead the way for future work; including tandem, staggered and side-by-side arrangements with the two cylinders free to move.Copyright © 2005 by ASME

Journal Article
TL;DR: In this paper, the authors combine the physical and numerical models to evaluate the flow-induced vibration of a hydraulic radial gate and calculate the dynamic response durations of the gate at different openings on which the fluctuating force acting is measured.
Abstract: The methodology of combining the physical and numerical models is employed to evaluate the flow-induced vibration of a hydraulic radial gate.The fluctuating force acting on the element of flow-gate interface,instead of that at a point,is surveyed with the newly developed equipment.The durations of fluctuating force acting on all elements are synchronistically measured.Meanwhile,the software,ANSYS,is used to compute the dynamic response durations of the gate at different openings on which the fluctuating force acting is measured.The properties of the natural vibration is different for the radial gate under the conditions with and without flow field,so that the effect of the flow on the gate vibration should be considered.The variation of the model property of the radial gate with the gate opening is discussed.

01 Jan 2005
TL;DR: In this paper, the effect of internal flow on the vortex-induced vibration of the free spans of a submarine free spanning pipeline was investigated and the Newmark method combined with simple iteration was used to solve the system of equations.
Abstract: At present, most researches on the vortex-induced vibration of submarine free spanning pipelines ignore the effect of internal flowing fluid; furthermore, there are no research reports considering the coupling effect of internal and external fluid with the free span. In this paper, combining Iwan's wake oscillator model with the differential equation derived for the dynamic response of submarine free spanning pipelines with inclusion of internal flow, the pipe-fluid coupling equations are developed to investigate the effect of internal flow on the vortex-induced vibration of the free spans. The finite element approximation is implemented to derive the matrix equations of equilibrium. The Newmark method combined with simple iteration is used to solve the system of equations. The results indicate that the internal fluid flow may cause the shift of resonance band to the lower frequency and a slight decrease in the peak value; the effect will be more pronounced with the increase of the span length and can be weakened in the presence of the axial tension.