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Showing papers on "Vortex-induced vibration published in 1999"


Journal ArticleDOI
TL;DR: In this article, the effects of the bed proximity, the thickness of the boundary layer, and the velocity gradient on the pressure distribution, the hydrodynamic forces and the vortex shedding behavior were examined.

258 citations


Patent
06 Aug 1999
TL;DR: In this article, a crosslink is placed between two or more steel tubular lines in order to enhance the stability of the riser system, which increases the stability and/or decreases sensitivity to vortex induced vibration of risers.
Abstract: A riser arrangement increases the stability and/or decreases sensitivity to vortex induced vibration of risers of a riser system including steel tubular lines, SCRIBS and flexible hose risers leading to a floating storage/production vessel. A cross-link is placed between two or more steel tubular lines in order to enhance the stability of the riser system. Devices are coupled to the steel tubular lines for increasing their tension in order to increase the natural frequency of vibration in order to reduce sensitivity to vortex induced vibration.

46 citations



Journal ArticleDOI
TL;DR: In this article, two-and three-dimensional simulation models for the computation of flow-induced vibration of tube bundles subjected to single-phase cross-flow are applied for a full flexible tube row and a tube bundle.
Abstract: Two- and three-dimensional simulation models for the computation of flow-induced vibration of tube bundles subjected to single-phase cross-flow are applied for a full flexible tube row and a tube bundle. The flow-induced vibration is simulated with the CFD (Computational Fluid Dynamics) program STAR-CD in combination with a coupled solver for the differential equations of parallel vibrating tubes for two- and three-dimensional calculations. Additionally a coupled FEM (Finite Element Method) program is used for the three-dimensional simulation of different tube support conditions. The CFD program solves the Navier–Stokes equations with different ke-models or an implemented kω-model for the unsteady turbulent viscous and incompressible flow field. The object of this project is to find a model, which describes the fluidelastic vibration excitation and enables an accurate computation of critical velocities in tube bundles comparable to those determined with the new design recommendation by K. Schroder and H. Gelbe, New design recommendations for fluidelastic instability in heat exchanger tube bundles, ASME AD-Vol. 53–2, Fluid-Structure Interaction, Aeroelasticity, Flow-Induced Vibration and Noise, 1997, Volume II, pp. 211-219 (s. a. Journal of Fluids and Structures, 13 (1999), to be published). Then it will be possible to investigate independently the influence of the structure data and the fluid properties on the onset of instability. The presented model is validated with experimental data and compared with existing models in the literature. Different grid discretizations of the flow field and turbulence models were tested for rigid and flexible tubes and the simulation results for the fluid forces, the pressure distributions and the onset of instability are compared with experimental data for a tube, a tube row and a tube bundle subjected to cross flow.

35 citations


Journal ArticleDOI
TL;DR: In this article, a methodology for computing vortex-induced vibrations (VIV) on risers is presented based on computation of the flow by a CFD program, structural dynamics by a nonlinear structural (CSD) code, and a coupling between them.
Abstract: A methodology for computing vortex-induced vibrations (VIV) on risers is presented. It is based on computation of the flow by a CFD program, structural dynamics by a nonlinear structural (CSD) code, and a coupling between them. The CFD computations are performed in 2-D at a number of sections along the riser. The load is imposed on the riser in a strip theory manner. The coupling between the CFD planes takes place through the response of the riser. The local deformation of the riser is taken into account by the CFD program, thus completing a fluid-structure interaction loop each time step. The methodology is validated by comparing results from simulations with results from model tests.

28 citations


Journal ArticleDOI
TL;DR: In this paper, the response amplitudes of a roughened cylinder oscillating in the transverse (cross-flow) direction in the flow were measured and the measured range of reduced velocity is about 1·5-8, which includes the critical velocity.

25 citations


Journal ArticleDOI
TL;DR: In this article, an inverse method for identifying a distributed random excitation acting on a dynamic system has been developed at EDF, whose applications go far beyond the flow-induced vibration field, has been implemented into the Meidee ® software.

20 citations


Journal ArticleDOI
Junji Tani1, J. Qiu1, Y. Liu1
TL;DR: In this paper, a robust control of the vortex-induced vibration of a rigid circular cylinder supported by an elastic cantilever beam in which the fluid force is considered as an external excitation on the structure is presented.

9 citations


Journal ArticleDOI
TL;DR: In this paper, a simple thermowell, a uniform cantilever subjected to a combination of vortex shedding and drag forces, was used to obtain the dynamic stresses for a complete range of flows.
Abstract: Traditional thermowell selection methods based on velocity rating tables are no longer a match for the demands of modern processes, and a new approach, involving dynamic analysis methods, is needed. Starting with the simplest possible thermowell, a uniform cantilever subjected to a combination of vortex shedding and drag forces, the dynamic stresses are obtained for a complete range of flows. This establishes a basis for extending the standard thermowell stress model to cover a wider range of processes and flow conditions.

8 citations


Proceedings ArticleDOI
20 Jun 1999
TL;DR: In this paper, the same finite element model is applied to both the blading and the fluid, resulting in consistency between the fluid and structure, and a coupled interacting fluid-structure analysis enables the aerodynamic damping of multiple vibration modes to be predicted from a single time domain flow simulation.
Abstract: Flow induced vibration of turbomachine blade rows is a coupled fluid-structure problem. Thus, rather than separate fluid and structural models, a coupled interacting fluid-structures analysis is needed. This research addresses this need by extending the finite element code ALE3D that solves the three-dimensional Euler equations to model the unsteady aerodynamics of turbomachine blade rows. The same finite element model is applied to both the blading and the fluid, resulting in consistency between the fluid and structure. This coupled interacting fluid-structure analysis enables the aerodynamic damping of multiple vibration modes to be predicted from a single time domain flow simulation. This novel approach to predict aerodynamic damping is demonstrated by considering a modem transonic compressor blade row. The blading is first impulsed in its first bending and first torsion modes in a vacuum. It is then immersed in the designpoint flow field and impulsed in its first bending and first torsion modes again. Signal processing tools applied to the predicted blade response time history extract the difference in the decay rate ofboth modes. ai A A bi pg f hi M ni Q'< q S t Ui Ui "lX; £iJK r p O'jj t CD, C. I;. 1;.. Subscripts e I I J superscripts n List of Symbols acceleration speed of sound amplitude ofresponse envelop body force per unit volume specific internal energy hourglass viscous force impulse force coefficient hourglass deformation rate mass ofelement normal pointing out of control surface hourglass viscosity coefficient shock smearing factor surface of element time material velocity mesh velocity volume of element position vector alternating unit vector hourglass deformation basis vector density stress tensor pseudo-time/damping time constant frequency non-dimensional damping constant in vacuum non-dimensional damping constant due to aerodynamics only total non-dimensional damping constant Description elemental value spatial coordinate, i = I. 2, 3 nodal value. node number spatial coordinate, j = 1.2, 3 Descr;pl;on time step level node-centered element quantity

8 citations


Journal ArticleDOI
TL;DR: A finite element method based on ALE formulation has been adopted in order to examine the effect of periodic velocity excitation on the aerodynamic characteristics of an oscillating circular cylinder, and numerical results showed that some excitation can reduce negative damping, which is caused by unsteady lift force, and thereby stabilize the aerodynamics of the cylinder as mentioned in this paper.
Abstract: A finite element method based on ALE formulation has been adopted in order to examine the effect of periodic velocity excitation on the aerodynamic characteristics of an oscillating circular cylinder. Periodic excitation, which was placed on the cylinder surface, stimulated the separated shear layers around the cylinder, and numerical results showed that some excitation can reduce negative damping, which is caused by unsteady lift force, and thereby stabilize the aerodynamics of the cylinder. Furthermore, the change of lift phase caused by periodic excitation seems to be important in stabilizing the aerodynamics of the cylinder. The simulation also confirmed that periodic excitation can suppress the vortex-induced vibration of the cylinder.

Journal ArticleDOI
TL;DR: In this article, a theoretical method for predicting the fluttering of a flexible thin sheet or web of such a paper blown in high speed flow of fluid is proposed, which assumes self-excited aeroelastic oscillation of the sheet with infinitesimally small amplitude.
Abstract: A theoretical method has been proposed for prediction of the fluttering of a flexible thin sheet or web of such as paper blown in high speed flow of fluid. It assumes self-excited aeroelastic oscillation of the sheet with infinitesimally small amplitude. The flow and the sheet motion are expressed terms of discretized vortices over the sheet and the wake, and motions of a number of short segments of flexible beams connected each other. The connecting conditions yield a homogeneous linear simultaneous equations concerning the unknowns including the strength of vortices and the sheet motions at each connecting points. The coefficient matrix of the equations determines the oscillation modes, the frequencies, the amplifying/damping rates, and thus the modes and the stability/instability of the system. The method is particularly suited to solve the situation where the oscillation modes are far from those in vacuum and progressive waves are predominant.

Journal ArticleDOI
TL;DR: In this paper, the stability of annular leakage-flow-induced vibrations was investigated in terms of the acceleration, velocity, and displacement of the inner cylinder of a fixed outer cylinder.
Abstract: This study reports the stability of annular leakage-flow-induced vibrations. The pressure distribution of fluid between a fixed outer cylinder and a vibrating inner cylinder was obtained in the case of a translationally and rotationally coupled motion of the inner cylinder. The unsteady fluid force acting on the inner cylinder in the case of translational and rotational single degree-of-freedom vibrations was then expressed in terms proportional to the acceleration, velocity, and displacement. Then the critical flow rate (at which stability was lost) was determined for an annular leakage-flow-induced vibration. Finally, the stability was investigated theoretically. It is known that instability will occur in the case of a divergent passage, but the critical flow rate depends on the passage increment in a limited range: the eccentricity of the passage and the pressure loss factor at the inlet of the passage lower the stability.

01 Jan 1999
TL;DR: In this article, an analytical solution for fatigue response due to crossflow vibration of free spanning submarine pipelines supported on semi-infinite elastic soil bed at the ends is presented, which includes the second order bending effect of axial force present in the pipeline.
Abstract: An analytical solution is presented for fatigue response due to crossflow vibration of free spanning submarine pipelines supported on semi-infinite elastic soil bed at the ends. The formulation includes the second order bending effect of axial force present in the pipeline. Free vibration response parameters are obtained by solving the governing differential equations and satisfying the appropriate boundary conditions for both symmetric and anti-symmetric modes. These parameters are used for assessing the fatigue damage due to crossflow vortex induced vibration under wave and current action as per new draft guidelines of DNV. Results are presented illustrating the effect of axial force and soil stiffness on the fatigue life of a free span under a combined wave and current loading scenario. The maximum permissible spans obtained from the full fatigue analysis are compared with those obtained from onset of cross-flow vibration criteria.


Journal Article
TL;DR: In this article, the rotary inertia of concentrated masses on the natural vibrations of fluid conveying pipes has been studied by theoretical modeling and computer simulation and the critical velocities related to a system instability have been investigated.

01 Jan 1999
TL;DR: In this paper, the effect of internal flow on vibration due to vortex shedding can be reduced by the increase of top tensions, but careful consideration has to be given, in design point, in order to avoid the resonance band occurring near vortex shedding frequency.
Abstract: Combining Iwan-Blevin's model into the approximated form of the nonlinear model derived for the dynamic analysis of the riser system with the inclusion of internal flow, current-vortex model is developed to investigate the effect of internal flow on vortex-induced vibration due to inline current. Galerkin's finite element approximation is implemented to derive the matrix equation of equilibrium. It is found that the effect of internal flow on vibration due to vortex shedding can be reduced by the increase of top tensions. However, careful consideration has to be given, in design point, in order to avoid the resonance band occurring near vortex shedding frequency, particularly for the long riser.



Journal ArticleDOI
TL;DR: In this article, the non-linear vortex-excited vibration of a circular cylinder in steady and uniform flow in open chanel was investigated in the range of reduced velocity Vr = 4 to 10 for several values of reduced damping Ksa.
Abstract: This study describes experimental investigations into the non-linear vortex-excited vibration of a circular cylinder in steady and uniform flow in open chanel with emphasis being placed on the amplification of fluid forces caused by the fluid-structure interaction. The dynamic transverse responses of a spring supported circular cylinder were investigated in the range of reduced velocity Vr = 4 to 10 for several values of reduced damping Ksa. The value Ksa of deduced damping was adjusted by using a electromagnetic damper. Hydrodynamic forces, drag and lift, acting on the vortex-excited circular cylinder freely vibrating in uniform flow were measured by using a load cell installed in the test cylinder and a load cell supporting the test cylinder. The variation of amplification of the hydrodynamic forces acting on the vortex-excited vibrating cylinder in comparison with the hydrodynamic forces acting on the cylinder stationary mounted at the reduced velocities Vr and amplitudes of transverse vibration of cylinder were evaluated quantitatively.

Journal ArticleDOI
TL;DR: In this paper, the effects of vortex-induced vibrations of a circular cylinder in high Reynolds number (1×105
Abstract: Experiments have been conducted on vortex-induced vibrations of a circular cylinder in high Reynolds number (1×105

Journal ArticleDOI
TL;DR: In this article, the along-wind response of a surface-mounted elastic fence under the action of wind was investigated numerically, and two sets of equations, one for the simulation of the unsteady turbulent flow and the other for the calculation of the dynamic motion of the fence, were solved alternatively.
Abstract: The along‐wind response of a surface‐mounted elastic fence under the action of wind was investigated numerically. In the computations, two sets of equations, one for the simulation of the unsteady turbulent flow and the other for the calculation of the dynamic motion of the fence, were solved alternatively. The resulting time‐series tip response of the fence as well as the flow fields were analyzed to examine the dynamic behaviors of the two. Results show that the flow is unsteady and is dominated by two frequencies: one relates to the shear layer vortices and the other one is subject to vortex shedding. The resulting unsteady wind load causes the fence to vibrate. The tip deflection of the fence is periodic and is symmetric to an equilibrium position, corresponding to the average load. Although the along‐wind aerodynamic effect is not significant, the fluctuating quantities of the tip deflection, velocity and acceleration are enhanced as the fundamental frequency of the fence is near the vortex ...


Journal ArticleDOI
TL;DR: In this article, the authors derived an equation of motion of sound pressure from the mutual excited mechanism with the unsteady fluid dynamic forces and showed that the imaginary part of the fluid dynamic force acting on the tube bundle supplies the energy of sound and on the other hand, radiation of sound consumes the energy.
Abstract: Ducts containing a tube bundle undergo acoustic resonant vibration. It is considered that the acoustic vibration is a kind of forced vibration by means of Karman vortex. However, it will be more reasonable to think that the vibration is a kind of mutual excited vibration, because fluid dynamic force excites a sound pressure and the sound pressure also generates the new fluid dynamic force. Equation of motion of sound pressure was derived from the mutual excited mechanism with the unsteady fluid dynamic forces. It was revealed from the equation that the imaginary part of the fluid dynamic force acting on the tube bundle supplies the energy of sound and on the other hand, radiation of sound consumes the energy. By comparing the supplying and consuming energies, it became possible to calculate a boundary where the acoustic resonant vibration will occur. The mechanism of supplying and consuming energies is discussed in this paper.

01 Jan 1999
TL;DR: In this article, the effect of both normal and parallel injection on the flow induced vibrations of a cylinder was investigated and it was found that at reduced velocities less than 8, the normal injection resulted in an increase in the dimension less vibration amplitude.
Abstract: This paper reports an experimental investigation on the ef- fect of a downstream secondary injection in the vicinity of an elasti- cally mounted cylinder on the flow induced vibration. The possibili- ties of using normal and parallel injection to the cylinder for controlling the flow induced vibration were investigated. Both smooth and rough cylinders were used. It was found that at reduced velocities less than 8 the effect of both normal and parallel injections on the flow induced vibrations of the cylinder are negligible for all locations of injection and all surface roughnesses used. However at reduced velocities greater than 8 the ef- fect of injection is very much dependent on the blowing rates , the lo- cation of the injection and the surface roughness of the cylinder. In general, the normal injection resulted in an increase in the dimension- less vibration amplitude.

Journal ArticleDOI
TL;DR: In this article, the authors proposed a method to solve the problem of the lack of a suitable vehicle for the purpose of reducing the number of vehicles in the world. But they did not specify a vehicle type.
Abstract: 塔状円柱の自由端近傍に発生する“自由端渦”が“高風速渦励振”を励起すると考えられている. 本研究では自由端渦の発生特性を調べるために, 円柱ロッキング模型の頂部に薄い円盤を設置して自由端近傍の流れを変化させることを試みた. 円盤の直径の増加とともに高風速渦励振の振幅は減少し, その発現風速は低風速側ヘシフトする傾向がみられた. 自由端近傍における後流風速変動の測定によって, この原因は自由端渦の発生が弱まると同時に, その周波数が増加するためであることを明らかにしている. また, 円盤の直径をある程度大きくすると, カルマン渦の放出周波数よりもやや低い周波数を有する渦の発生が自由端近傍において著しくなる. このことが応答に与える影響についても考察した.

Journal ArticleDOI
25 Jul 1999
TL;DR: In this paper, the power spectral density of cylinder vibration was measured at several Reynolds numbers, data of fluctuating force coefficients, Strouhal number and also correlation length were obtained, and the prediction method based on the random vibration theory introducing the correlation length has sufficient margin for actual turbulence-induced response.
Abstract: Experiments have been conducted on turbulence induced vibration of a circular cylinder in water flow with high Reynolds number (3×105

Journal ArticleDOI
TL;DR: In this paper, the authors measured the fluctuating lift and drag forces by Karman vortex shedding and pressure distributions around a stationary circular cylinder in a water cross flow at supercritical Reynolds numbers.
Abstract: Fluctuating lift and drag forces by Karman vortex shedding and pressure distributions around a stationary circular cylinder were measured in a water cross flow at supercritical Reynolds numbers. The surface roughness of the cylinder was a mirror-polished surface. Turbulence intensities of the incoming filow were changed from 1% to 13% in order to investigate the effect on vortex shedding characteristics. As the turbulence intensity increased in supercritical region, flow separation location of the boundary layer on the cylinder surface moved forward, Strouhal number decreased from about 0.48 to 0.29 and the fluctuating lift force by Karman vortex shedding increased.

Journal ArticleDOI
TL;DR: In this paper, the effect of the Strouhal number on the region of synchronization by symmetrical and Karman vortex shedding was investigated for a circular cylinder subjected to a water cross flow at supercritical Reynolds numbers for a wide range of reduced velocities.
Abstract: Vortex-induced vibrations were measured for a circular cylinder subjected to a water cross flow at supercritical Reynolds numbers for a wide range of reduced velocities. Turbulence intensities were changed from 1% to 13% in order to investigate the effect of the Strouhal number on the region of synchronization by symmetrical and Karman vortex shedding. The reduced damping of the test cylinder was about 0.1 in water. The surface roughness of the cylinder was a mirror-polished surface. Strouhal number decreased from about 0.48 to 0.29 with increasing turbulence intensity. Synchronized vibrations were observed even at supercritical Reynolds numbers where fluctuating fluid force was small. Reduced velocities at which drag and lift direction lock-in by Karman vortex shedding were initiated decreased with increasing Strouhal number. When Strouhal number was about 0.29, the self-excited vibration in drag direction by symmetrical vortex shedding began at which the frequency ratio of Karman vortex shedding frequency to the natural frequency of cylinder was 0.32.