Calculation of the Vibration of an Elastically Mounted Cylinder Using Experimental Data From Forced Oscillation

1983 ◽  
Vol 105 (2) ◽  
pp. 225-229 ◽  
Author(s):  
T. Staubli
Keyword(s):  
Experimental Data ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Forced Oscillation ◽  
Structure Interaction ◽  
Fluid Forces ◽  
Sinusoidal Motion ◽  
Nonlinear Relation ◽  
Lock In ◽  
Excitation Method

Several methods for investigating the fluid-structure interaction of bodies vibrating due to vortex shedding are compared briefly. The advantage of employing a forced-displacement excitation method is asserted. This method has been adopted to measure the response of the fluid forces acting on an oscillating circular cylinder in crossflow. With the results of these measurements, and a calculation based on the assumption of sinusoidal motion, the vibrations of a freely oscillating cylinder are predicted in the lock-in range. It is shown that hysteresis effects, which are observed in experiments with elastically mounted cylinders of certain damping and mass ratios, are caused by the nonlinear relation between the fluid force and the amplitude of oscillation.

Fluid Forces Induced by Vortex Shedding

1976 ◽  
Vol 98 (1) ◽  
pp. 19-24 ◽  
Author(s):  
R. D. Blevins ◽  
T. E. Burton
Keyword(s):  
Experimental Data ◽  
Vortex Shedding ◽  
Model Parameters ◽  
Amplitude Dependence ◽  
Fluid Forces ◽  
At Resonance ◽  
Elastic Cylinders ◽  
Random Vibration Theory ◽  
Semi Empirical ◽  
Good Agreement

A semi-empirical, dynamic model for investigating the fluid forces induced on a bluff cylinder by vortex shedding is developed using random vibration theory. The model includes both spanwise correlation effects and the amplitude dependence of the correlated vortex forces. Model parameters are determined by experimental data. The results are then applied to determine the forces exerted on elastic cylinders at resonance with vortex shedding. The predictions are in good agreement with experimental data.

Numerical Simulation of Vortex Shedding and Lock-in Characteristics for a Thin Cambered Blade

2007 ◽  
Vol 129 (10) ◽  
pp. 1297-1305 ◽  
Author(s):  
Baoshan Zhu ◽  
Jun Lei ◽  
Shuliang Cao
Keyword(s):  
Numerical Simulation ◽  
Vortex Shedding ◽  
Forced Oscillation ◽  
Tvd Scheme ◽  
Convective Term ◽  
Variation Diminishing ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency ◽  
Lock In ◽  
Phase Differences

In this paper, vortex-shedding patterns and lock-in characteristics that vortex-shedding frequency synchronizes with the natural frequency of a thin cambered blade were numerically investigated. The numerical simulation was based on solving the vorticity-stream function equations with the fourth-order Runge–Kutta scheme in time and the Chakravaythy–Oscher total variation diminishing (TVD) scheme was used to discretize the convective term. The vortex-shedding patterns for different blade attack angles were simulated. In order to confirm whether the vortex shedding would induce blade self-oscillation, numerical simulation was also carried out for blade in a forced oscillation. By changing the pitching frequency and amplitude, the occurrence of lock-in at certain attack angles was determined. Inside the lock-in zone, phase differences between the blade’s pitching displacement and the torque acting on the blade were used to infer the probability of the blade self-oscillation.

Hydrodynamics of the Flow Around a Circular Cylinder Sheathed by a Porous Layer

2004 ◽  
Author(s):  
M. P. Sobera ◽  
C. R. Kleijn ◽  
P. Brasser ◽  
H. E. A. van den Akker
Keyword(s):  
Experimental Data ◽  
Circular Cylinder ◽  
Porous Layer ◽  
Vortex Shedding ◽  
Small Distance ◽  
Grid Refinement ◽  
Solid Cylinder ◽  
Local Grid Refinement ◽  
Local Grid ◽  
Good Agreement

A detailed study of the turbulent flow at Re = 3900 around a circular cylinder, sheathed at some small distance by a porous layer, has been performed by means of Direct Numerical Simulation with a commercial unstructured finite volume based Computational Fluid Dynamics solver. First, to benchmark the performance of this code and the validity of the applied local grid refinement, simulations of the flow around a bare circular cylinder at the same Re were performed. Results were compared to that of an academic CFD solver and to numerical and experimental data from literature and good agreement was found. Subsequently, a detailed study of the flow around a porous layer sheathed cylinder at the same Re, was performed. The flow in the space between the outer porous and the inner solid cylinder was found to be laminar and periodic, with a frequency locked to that of the vortex shedding in the wake behind the cylinder. A good agreement was found to experimental data from literature.

Flow Past Oscillating Cylinders

1993 ◽  
Vol 115 (4) ◽  
pp. 197-205 ◽  
Author(s):  
R. W. Yeung ◽  
M. Vaidhyanathan
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Vortex Method ◽  
Boundary Integral ◽  
Preliminary Evaluation ◽  
Computational Results ◽  
Variable Boundary ◽  
Marine Risers ◽  
Boundary Integral Formulation ◽  
Lock In

The phenomenon of vortex shedding by oscillating cylinders is a complex one. Its understanding is, however, of utmost importance in marine-related engineering, particularly in connection with motions of deep submersibles and marine risers. In this paper, computational results are presented so that the behavior of the shedding as a function of certain parameter space can be elucidated. A methodology based on the random vortex method and a complex-variable boundary-integral formulation is used to study both forced and vortex-induced oscillations of a circular cylinder. Preliminary evaluation of this method indicates that it has been successful in predicting a number of experimentally observed behavior, among which the phenomena of “lock-in” associated with oscillations of the cylinder are well captured.

Synchronized Vibrations of a Circular Cylinder in Cross Flow at Supercritical Reynolds Numbers1

2003 ◽  
Vol 125 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Tsutomu Kawamura ◽  
Toshitsugu Nakao ◽  
Masanori Takahashi ◽  
Masaaki Hayashi ◽  
Kouichi Murayama ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Excited Vibration ◽  
Karman Vortex ◽  
Lock In

Synchronized vibrations of a circular cylinder in a water cross flow at supercritical Reynolds numbers were measured. Turbulence intensities were varied to investigate the effect of the Strouhal number on the synchronization range. Self-excited vibration in the drag direction due to symmetrical vortex shedding began only when the Strouhal number was about 0.29, at a reduced velocity of 1.1. The reduced velocities at the beginning of lock-in vibrations caused by Karman vortex shedding decreased from 1.5 to 1.1 in the drag direction and from 2.7 to 2.2 in the lift direction, as the Strouhal number increased from 0.29 to 0.48.

Numerical Investigation of Vortex-Induced Vibration of a Circular Cylinder Close to a Plane Boundary

2010 ◽  
Author(s):  
Ming Zhao ◽  
Liang Cheng
Keyword(s):  
Experimental Data ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Stokes Equations ◽  
Degree Of Freedom ◽  
Plane Boundary ◽  
Structural Dynamic ◽  
Vortex Induced Vibration ◽  
Two Degree Of Freedom ◽  
Bounce Back

Two-degree of freedom vortex-induced vibration (VIV) of a circular cylinder close to a plane boundary is investigated numerically. Two-dimensional (2D) Reynolds-Averaged Navier-Stokes Equations (RANS) and structural dynamic equation are solved using a finite element method (FEM). If the cylinder is initially very close to the plane boundary, it will be bounced back after it collides with boundary. It is assumed that the bouncing back only alters the cylinder’s velocity component perpendicular to the boundary. After it is bounced back, the cylinder’s velocity are determined by Uc = Uc′, Vc = −bVc′, where Uc and Vc are the cylinder’s velocity parallel to the boundary and that perpendicular to the boundary respectively, Uc′ and Vc′ are the velocities before cylinder is bounced back, b is the bounce back coefficient which is between 0 and 1. Numerical results of the vibration amplitude and frequency of a one-degree-of-freedom vibration (transverse to flow direction) of a circular cylinder close to a plane boundary are compared with the experimental data by Yang et al. [1]. The overall trends of the variation of the VIV amplitude with the reduced velocity were found to be in agreement with the experimental results. The calculated amplitude is smaller than the measured data. The frequency of the vibration increases with the increase of reduced velocity. The calculated vibrating frequency agrees well with the experimental data. It was found in this study that vortex-induced vibration (VIV) occurs even when the gap between the cylinder and the plane boundary is zero. This contradicts a perception that VIV would not occur for a pipeline close to the seabed with a gap ratio smaller than 0.3, this is because it was understood that vortex shedding would have been suppressed if the gap between the cylinder and the plane boundary is less than about 0.3 times of cylinder diameter for a fixed cylinder. Two-degree-of-freedom VIV of a circular cylinder close to a plane boundary is studied. The XY-trajectories, the frequency and the amplitude of the vibration are studied. The effects of the cylinder-to-boundary gap and the bounce back coefficient on VIV and the link between the vortex shedding mode and the VIV are discussed.

Phase jump and energy transfer of forced oscillating circular cylinder in uniform flow

2016 ◽  
Vol 231 (2) ◽  
pp. 496-510
Author(s):  
Guoqiang Tang ◽  
Lin Lu ◽  
Ming Zhao ◽  
Mingming Liu ◽  
Zhi Zong
Keyword(s):  
Reynolds Number ◽  
Energy Transfer ◽  
Circular Cylinder ◽  
Phase Difference ◽  
Uniform Flow ◽  
Phase Jump ◽  
Fluid Forces ◽  
Special Cases ◽  
Lock In ◽  
Transfer Direction

The phase jump, energy transfer, and the associated vortex shedding modes of a circular cylinder undergoing forced oscillation normal to the incoming uniform flow are investigated numerically at Reynolds number ( Re) of 200. The dependence of the fluid forces on the non-dimensional oscillating amplitude A* =  A/ D ∈ [0.1, 0.6] and frequency f* =  fe/ fs ∈ [0.5, 2.0] is examined, where A is the oscillating amplitude, D is the cylinder diameter, fe is the cylinder oscillating frequency, and fs is the Strouhal frequency of fixed cylinder at the same Reynolds number, respectively. The lock-in region is identified by the combination of Fourier analysis and Lissajous phase diagram. The phase difference between displacement and lift fluctuation and the energy transfer between fluid and structure are discussed. Within the lock-in region, a jump in the phase difference is found to occur in the cases with A* = 0.5 and 0.55 without a wake mode transition. The numerical results reveal that the appearance of the phase jump is consistent with the reversal of the energy transfer direction. For the special cases of A* = 0.5 and 0.55, changes in the sign of energy transfer are observed, while no reversal of energy transfer is observed at other amplitudes. The energy transfer direction is either from fluid to cylinder when A* ∈ [0.1, 0.4] or from cylinder to fluid when A* ≥ 0.6. It is confirmed that the energy transfer between fluid and cylinder is not only dependent on cylinder oscillating frequency but also on cylinder oscillating amplitude.

Flow Induced Oscillation of a Set-In Circular Cylinder

2009 ◽  
Author(s):  
F. Oviedo-Tolentino ◽  
R. Romero-Mendez ◽  
A. Hernandez-Guerrero ◽  
J. M. Luna
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Flow Direction ◽  
Flow Behavior ◽  
Cross Flow ◽  
Close Relation ◽  
Structure Interaction ◽  
Visualization Techniques ◽  
Flow Experiments

This work studies the fluid-structure interaction of a set-in, large aspect-ratio circular cylinder in cantilever subjected to a cross flow. Experiments were conducted in a water tunnel and observations were obtained using flow visualization techniques and direct observation of the deflection of the cylinder. The flow behavior was observed using dye injection. The experiments show that the dominant vibration of the cylinder is transversal to the flow direction, and that the first mode of vibration of the cylinder appears at a particular Reynolds number, which is a function of the mechanical properties of the cylinder. The deflection stops when the Reynolds number is increased. The peak deflection and frequency of oscillation, as a function of the Reynolds number, were also determined. The analysis shows a close relation between the frequency of oscillation and the frequency of appearance of a vortex shedding. For large deflections of the cylinder the flow structure is modified substantially, and the frequency at which vortex appears is different to the frequency that occurs for fixed cylinders.

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