scholarly journals Effects of Mass and Damping on Flow-Induced Vibration of a Cylinder Interacting with the Wake of Another Cylinder at High Reduced Velocities

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5148
Author(s):  
Md. Mahbub Alam
Keyword(s):  
Reynolds Number ◽  
Vibration Amplitude ◽  
Amplitude Ratio ◽  
Damping Ratio ◽  
Shear Layers ◽  
Mass Ratio ◽  
Flow Induced Vibration ◽  
Flow Induced Vibrations ◽  
Unique Parameter

Flow-induced vibration is a canonical issue in various engineering fields, leading to fatigue or immediate damage to structures. This paper numerically investigates flow-induced vibrations of a cylinder interacting with the wake of another cylinder at a Reynolds number Re = 150. It sheds light on the effects of mass ratio m*, damping ratio, and mass-damping ratio m*ζ on vibration amplitude ratio A/D at different reduced velocities Ur and cylinder spacing ratios L/D = 1.5 and 3.0. A couple of interesting observations are made. The m* has a greater influence on A/D than ζ although both m* and ζ cause reductions in A/D. The m* effect on A/D is strong for m* = 2–16 but weak for m* > 16. As opposed to a single isolated cylinder case, the mass-damping m*ζ is not found to be a unique parameter for a cylinder oscillating in a wake. The vortices in the wake decay rapidly at small ζ. Alternate reattachment of the gap shear layers on the wake cylinder fuels the vibration of the wake cylinder for L/D = 1.5 while the impingement and switch of the gap vortices do the same for L/D = 3.0.

Experimental Flow-Induced Vibration Analysis of the Crossflow Past a Single Cylinder and Pairs of Cylinders in Tandem and Side-by-Side

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Roberta Fátima Neumeister ◽  
Adriane Prisco Petry ◽  
Sergio Viçosa Möller
Keyword(s):  
Vibration Amplitude ◽  
Damping Ratio ◽  
Sudden Increase ◽  
Blockage Ratio ◽  
Flow Induced Vibration ◽  
Single Cylinder ◽  
Reference Velocity ◽  
Continuous Wavelets ◽  
Constant Height ◽  
Spacing Ratio

Abstract Flow-induced vibration of a single cylinder and two cylinders in tandem and side-by-side configurations is experimentally investigated in this paper in the subcritical regime. The natural frequency of the system varied from 8.8 Hz to 46.2 Hz. The mass ratio, m*, ranged between 158 and 643 while the damping ratio, ζ, between 0.0005 and 0.009. The pairs of cylinders present a spacing ratio of 1.26 (P/D and L/D). In all cases, one and both cylinders (BV) were free to vibrate. Experiments were performed in an aerodynamic channel with a constant height and a variable width, for the evaluation of the influence of the blockage ratio (BR), using accelerometers and hot wire anemometry. The reference velocity, measured at the entrance of the test section was used to calculate the reduced velocity, Vr = U/fnD, with values from 4 to 132 and the Reynolds number between 3 × 103 and 8 × 104. The root-mean-square-values of the displacement amplitudes, Y/D, were obtained through the integration of the acceleration signals. Fourier and continuous wavelets were employed in the analysis. For a single cylinder free to vibrate, the higher amplitudes occur at two distinct reduced velocities, associated with the vibration modes of the cylinder. The vibration amplitude of a single cylinder increased as the blockage ratio increased, decreasing for the highest blockage ratio investigated. For the case of cylinders in tandem, the presence of the fixed cylinder in the wake of the cylinder free to vibrate amplifies the vibration response at high reduced velocities. When the blockage ratio is increased, a sudden increase in the vibration amplitude is observed. When both cylinders are free to vibrate, the relation between the natural frequencies of both cylinders influences the response amplitudes. In the case with two cylinders side-by-side, the vibration amplitude remains similar to a single cylinder, but when both cylinders are free to vibrate, the presence and the influence of flow bistability is observed.

Towards Understanding Two-Phase Flow Induced Vibration of Piping Structure With a U-Bend

2019 ◽  
Author(s):  
Olufemi E. Bamidele ◽  
Wael H. Ahmed ◽  
Marwan Hassan
Keyword(s):  
Void Fraction ◽  
Vibration Amplitude ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Void Fractions ◽  
Flow Induced Vibrations

Abstract The current work investigates two-phase flow induced vibrations in 90° U-bend. The two-phase induced vibration of the structure was investigated in the vertical, horizontal and axial directions for various flow patterns from bubbly flow to wavy and annular-dispersed flow. The void fractions at various locations along the piping including the fully developed void fraction and the void fraction at the entrance of the U-bend were fully investigated and correlated with the vibration amplitude. The results show that the excitation forces of the two-phase flow in a piping structure are highly dependent on the flow pattern and the flow conditions upstream of the bend. The fully developed void fraction and slip between phases are important in modelling of forces in U-bends and elbows.

On Cross Flow-Induced Vibration of a Flexible Cylinder

2014 ◽  
Author(s):  
H. Cen ◽  
D. S-K. Ting ◽  
R. Carriveau
Keyword(s):  
Reynolds Number ◽  
Degrees Of Freedom ◽  
Cross Flow ◽  
Mass Ratio ◽  
Flexible Cylinder ◽  
Flow Induced Vibration ◽  
Slowing Down ◽  
Mode Vibration ◽  
Inner Diameter ◽  
Multi Mode

An experiment study on the cross flow-induced vibration of a flexible cylinder with two degrees of freedom had been conducted in a towing tank. The test cylinder was a 45 cm long Tygon tubing with outer and inner diameter of 7.9 mm (5/16 in) and 4.8 mm (3/16 in), giving a mass ratio of 0.77 and an aspect ratio of 56. It was towed from rest up to 1.6 m/s before slowing down to rest again over a distance of 1.6 m in still water, covering the range of Reynolds number from 1500 to 13000 and reduced velocity from 4 to 35. Multi-mode vibration and sudden shift between different modes were observed. The vibration amplitude, frequency and mode were quantified. The results obtained during the brief constant towing speed were expressed in term of the corresponding Reynolds number or reduced velocity. These findings were cast with respect to the existing knowledge in the literature.

Flow-Induced Vibration and Hydrokinetic Power Conversion of Two Staggered Rough Cylinders for 2.5 × 104 < Re < 1.2 × 105

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Wanhai Xu ◽  
Chunning Ji ◽  
Hai Sun ◽  
Wenjun Ding ◽  
Michael M. Bernitsas
Keyword(s):  
Flow Regime ◽  
Damping Ratio ◽  
Water Channel ◽  
Field Tests ◽  
Circular Cylinders ◽  
Total Power ◽  
Mass Ratio ◽  
Flow Induced Vibration ◽  
Oscillation System ◽  
Turbulence Control

Flow-induced vibration (FIV), primarily vortex-induced vibrations (VIV), and galloping have been used effectively to convert hydrokinetic energy to electricity in model-tests and field-tests by the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan. It is known that the response of cylinders with passive turbulence control (PTC) undergoing vortex shedding differs from the oscillation of smooth cylinders in a similar configuration. Additional investigation on the FIV of two elastically mounted circular cylinders in a staggered arrangement with low mass ratio in the TrSL3 flow-regime is required and is contributed by this paper. The two PTC-cylinders were allowed to oscillate in the transverse direction to the oncoming fluid flow in a recirculating water channel. The cylinder model with a length of 0.895 m and a diameter of 8.89 cm, a mass ratio of 1.343 was used in the tests. The Reynolds number was in the range of 2.5 × 104 < Re < 1.2 × 105, which is a subset of the TrSL3 flow-regime. The center-to-center longitudinal and transverse spacing distances were T/D = 2.57 and S/D = 1.0, respectively. The spring stiffness values were in the range of 400 < K (N/m) <1200. The values of harnessing damping ratio tested were ζharness = 0.04, 0.12 and 0.24. For the values tested, the experimental results indicate that the response of the upstream cylinder is similar to the single cylinder. The downstream cylinder exhibits more complicated vibrations. In addition, the oscillation system of two cylinders with stiffer spring and higher ζharness could initiate total power harness at a higher flow velocity and obtain more power.

Effects of Damping on Flow-Mediated Interaction Between Two Cylinders

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Zhonglu Lin ◽  
Dongfang Liang ◽  
Ming Zhao
Keyword(s):  
Vibration Amplitude ◽  
Amplitude Ratio ◽  
Damping Factor ◽  
Structural Damping ◽  
Mass Ratio ◽  
Low Frequencies ◽  
Master Cylinder ◽  
High Frequencies ◽  
Gap Ratio ◽  
Highly Sensitive

This study investigates the flow-mediated interaction between two vibrating cylinders of the same size immersed in an otherwise still fluid. The master cylinder carries out forced vibration, while the slave cylinder is elastically mounted with one degree-of-freedom along the centerline between the two cylinders. We examined the stabilized vibration of the slave cylinder. In total, 6269 two-dimensional (2D) cases were simulated to cover the parameter space, with a fixed Reynolds number of 100, the structural damping factor of the slave cylinder ranging from 0 to 1.4, the mass ratio of the slave cylinder ranging from 1.5 to 2.5, the initial gap ratio ranging from 0.2 to 1.0, the vibration amplitude ratio of the master cylinder ranging from 0.025 to 0.1, and the vibration frequency ratio ranging from 0.05 to 2.4. We found that the vibration amplitude of the slave cylinder is highly sensitive to damping when the damping coefficient is small. The two cylinders' vibration is in antiphase at low frequencies but in phase at high frequencies. The phase of the slave cylinder changes abruptly at resonance when it has little damping, but the phase change with the frequency becomes increasingly gradual with increasing damping. With a nonzero damping factor, the maximum vibration amplitude of the slave cylinder is inversely correlated with its mass ratio. The response of the slave cylinder is explained by examining the pressure distribution and velocity field adjacent to it.

scholarly journals Parametric Analysis of an Energy-Harvesting Device for a Riser Based on Vortex-Induced Vibrations

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 414
Author(s):  
Xu Bai ◽  
Chuanyu Han ◽  
Yong Cheng
Keyword(s):  
Energy Harvesting ◽  
Degrees Of Freedom ◽  
Amplitude Ratio ◽  
Damping Ratio ◽  
Capture Efficiency ◽  
Mass Ratio ◽  
Energy Capture ◽  
Dimensionless Amplitude ◽  
Vortex Induced Vibrations ◽  
Low Mass Ratio

An energy-harvesting device for a riser based on vortex-induced vibration is proposed to overcome the power supply problem for a marine deep-water riser-monitoring device. To estimate the upper limit of its energy-capture efficiency, as well as the weight and size of the device designed, a discrete model of the riser was configured. With the experimental settings of Stappenbelt and Blevins, vortex-induced vibrations of the discrete cylinder with two degrees of freedom were simulated, and the parameters affecting the energy-acquisition efficiency of the riser were analyzed. The analysis of the dimensionless amplitude ratio showed that this ratio for the system decreased with increasing mass ratio and damping ratio. An analysis showed that the influences of the damping ratio on the energy-capture efficiency were different under medium and low-mass-ratio conditions. A maximum value of 38.44% was achieved when the mass ratio was 2.36 and the damping ratio was 0.05.

Interactive Flow-Induced Vibrations of Two Staggered, Low Mass-Ratio Cylinders in the TrSL3 Flow Regime (2.5×104

2017 ◽  
Author(s):  
Chunning Ji ◽  
Wanhai Xu ◽  
Hai Sun ◽  
Michael M. Bernitsas
Keyword(s):  
Flow Regime ◽  
Damping Ratio ◽  
Circular Cylinders ◽  
Mass Ratio ◽  
Number Range ◽  
Parametric Plane ◽  
Staggered Arrangement ◽  
Flow Induced Vibrations ◽  
Low Mass ◽  
Low Mass Ratio

Flow-induced vibrations of two elastically mounted circular cylinders in staggered arrangement were experimentally investigated. The Reynolds number range for all experiments (2.5×104<Re<1.2×105) was in the TrSL3 flow regime. The oscillator parameters selected were: mass ratio m* = 1.343, spring stiffness K = 250N/m, and damping ratio ζ = 0.02. The experiments were conducted in the Low Turbulence Free Surface Water (LTFSW) Channel in the MRELab of the University of Michigan. A closed-loop, virtual spring-damper system (Vck) was used to facilitate quick and accurate parameter setting. Based on the characteristics of the displacement response, five vibration patterns were identified and their corresponding regions in the parametric plane of the in-flow spacing (1.57<L/D<4.57) and transverse cylinder-spacing (0<T/D<2) were defined. The hydrodynamic forces and frequency characteristics of the vibration response are discussed as well.

Interactive Flow-Induced Vibrations of Two Staggered, Low Mass-Ratio Cylinders in the TrSL3 Flow Regime (2.5 × 104 < Re < 1.2 × 105): Smooth Cylinders

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Chunning Ji ◽  
Wanhai Xu ◽  
Hai Sun ◽  
Rui Wang ◽  
Chunhui Ma ◽  
...  
Keyword(s):  
Flow Regime ◽  
Damping Ratio ◽  
Circular Cylinders ◽  
Mass Ratio ◽  
Number Range ◽  
Parametric Plane ◽  
Staggered Arrangement ◽  
Flow Induced Vibrations ◽  
Low Mass ◽  
Low Mass Ratio

Flow-induced vibrations (FIVs) of two elastically mounted circular cylinders in staggered arrangement were experimentally investigated. The Reynolds number range for all experiments (2.5 × 104 < Re < 1.2 × 105) was in the transition in shear layer 3 (TrSL3) flow regime. The oscillator parameters selected were: mass ratio m* = 1.343 (ratio of oscillating mass to displaced fluid mass), spring stiffness K = 250 N/m, and damping ratio ζ = 0.02. The experiments were conducted in the low turbulence free surface water (LTFSW) channel in the MRELab of the University of Michigan. A closed-loop, virtual spring–damper system (Vck) was used to facilitate quick and accurate parameter setting. Based on the characteristics of the displacement response, five vibration patterns were identified and their corresponding regions in the parametric plane of the in-flow spacing (1.57 < L/D < 4.57) and transverse cylinder spacing (0 < T/D < 2) were defined. The hydrodynamic forces and frequency characteristics of the vibration response are also discussed.

Vortex-Induced Vibrations of a Cylinder at Subcritical Reynolds Number

2011 ◽  
Author(s):  
Yoann Jus ◽  
Elisabeth Longatte ◽  
Jean-Camille Chassaing ◽  
Pierre Sagaut
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Cross Flow ◽  
Physical Analysis ◽  
Arbitrary Lagrangian Eulerian ◽  
Vortex Induced Vibrations ◽  
Low Mass

The present work focusses on the numerical study of Vortex-Induced Vibrations (VIV) of an elastically mounted cylinder in a cross flow at moderate Reynolds numbers. Low mass-damping experimental studies show that the dynamic behavior of the cylinder exhibits a three-branch response model, depending on the range of the reduced velocity. However, few numerical simulations deal with accurate computations of the VIV amplitudes at the lock-in upper branch of the bifurcation diagram. In this work, the dynamic response of the cylinder is investigated by means of three-dimensional Large Eddy Simulation (LES). An Arbitrary Lagrangian Eulerian framework is employed to account for fluid solid interface boundary motion and grid deformation. Numerous numerical simulations are performed at a Reynolds number of 3900 for both no damping and low-mass damping ratio and various reduced velocities. A detailed physical analysis is conducted to show how the present methodology is able to capture the different VIV responses.

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