scholarly journals Experimental investigation of flow-induced vibration of a rotating circular cylinder

2017 ◽  
Vol 829 ◽  
pp. 486-511 ◽  
Author(s):  
K. W. L. Wong ◽  
J. Zhao ◽  
D. Lo Jacono ◽  
M. C. Thompson ◽  
J. Sheridan
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Rotation Rate ◽  
Rotating Cylinder ◽  
Flow Induced Vibration ◽  
Amplitude Response ◽  
Number Range ◽  
Rotating Circular Cylinder ◽  
Numerical Predictions

While flow-induced vibration of bluff bodies has been extensively studied over the last half-century, only limited attention has been given to flow-induced vibration of elastically mounted rotating cylinders. Since recent low-Reynolds-number numerical work suggests that rotation can enhance or suppress the natural oscillatory response, the former could find applications in energy harvesting and the latter in vibration control. The present experimental investigation characterises the dynamic response and wake structure of a rotating circular cylinder undergoing vortex-induced vibration at a low mass ratio ($m^{\ast }=5.78$) over the reduced velocity range leading to strong oscillations. The experiments were conducted in a free-surface water channel with the cylinder vertically mounted and attached to a motor that provided constant rotation. Springs and an air-bearing system allow the cylinder to undertake low-damped transverse oscillations. Under cylinder rotation, the normalised frequency response was found to be comparable to that of a freely vibrating non-rotating cylinder. At reduced velocities consistent with the upper branch of a non-rotating transversely oscillating cylinder, the maximum oscillation amplitude increased with non-dimensional rotation rate up to $\unicode[STIX]{x1D6FC}\approx 2$. Beyond this, there was a sharp decrease in amplitude. Notably, this critical value corresponds approximately to the rotation rate at which vortex shedding ceases for a non-oscillating rotating cylinder. Remarkably, at $\unicode[STIX]{x1D6FC}=2$ there was approximately an 80 % increase in the peak amplitude response compared to that of a non-rotating cylinder. The observed amplitude response measured over the Reynolds-number range of ($1100\lesssim Re\lesssim 6300$) is significantly different from numerical predictions and other experimental results recorded at significantly lower Reynolds numbers.

Unsteady flow past a rotating circular cylinder at Reynolds numbers 103 and 104

1990 ◽  
Vol 220 ◽  
pp. 459-484 ◽  
Author(s):  
H. M. Badr ◽  
M. Coutanceau ◽  
S. C. R. Dennis ◽  
C. Ménard
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Unsteady Flow ◽  
Rotation Rate ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Number Range ◽  
Flow Past

The unsteady flow past a circular cylinder which starts translating and rotating impulsively from rest in a viscous fluid is investigated both theoretically and experimentally in the Reynolds number range 103 [les ] R [les ] 104 and for rotational to translational surface speed ratios between 0.5 and 3. The theoretical study is based on numerical solutions of the two-dimensional unsteady Navier–Stokes equations while the experimental investigation is based on visualization of the flow using very fine suspended particles. The object of the study is to examine the effect of increase of rotation on the flow structure. There is excellent agreement between the numerical and experimental results for all speed ratios considered, except in the case of the highest rotation rate. Here three-dimensional effects become more pronounced in the experiments and the laminar flow breaks down, while the calculated flow starts to approach a steady state. For lower rotation rates a periodic structure of vortex evolution and shedding develops in the calculations which is repeated exactly as time advances. Another feature of the calculations is the discrepancy in the lift and drag forces at high Reynolds numbers resulting from solving the boundary-layer limit of the equations of motion rather than the full Navier–Stokes equations. Typical results are given for selected values of the Reynolds number and rotation rate.

scholarly journals Experimental investigation of in-line flow-induced vibration of a rotating circular cylinder

2018 ◽  
Vol 847 ◽  
pp. 664-699 ◽  
Author(s):  
J. Zhao ◽  
D. Lo Jacono ◽  
J. Sheridan ◽  
K. Hourigan ◽  
M. C. Thompson
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Rotation Rate ◽  
Free Stream ◽  
Flow Induced Vibration ◽  
Wake Structure ◽  
Rate Range ◽  
Structure System ◽  
Line Flow

This study experimentally investigates the in-line flow-induced vibration (FIV) of an elastically mounted circular cylinder under forced axial rotation in a free stream. The present experiments characterise the structural vibration, fluid forces and wake structure of the fluid–structure system at a low mass ratio (the ratio of the total mass to the displaced fluid mass) over a wide parameter space spanning the reduced velocity range $5\leqslant U^{\ast }\leqslant 32$ and the rotation rate range $0\leqslant \unicode[STIX]{x1D6FC}\leqslant 3.5$, where $U^{\ast }=U/(\,f_{nw}D)$ and $\unicode[STIX]{x1D6FC}=|\unicode[STIX]{x1D6FA}|D/(2U)$, with $U$ the free-stream velocity, $D$ the cylinder outer diameter, $f_{nw}$ the natural frequency of the system in quiescent water and $|\unicode[STIX]{x1D6FA}|$ the angular velocity of the cylinder rotation. The corresponding Reynolds number (defined by $Re=UD/\unicode[STIX]{x1D708}$, with $\unicode[STIX]{x1D708}$ the kinematic viscosity of the fluid) was varied over the interval $1349\leqslant Re\leqslant 8624$, where it is expected that the FIV response is likely to be relatively insensitive to the Reynolds number. The fluid–structure system was modelled using a low-friction air-bearing system in conjunction with a free-surface water-channel facility. Three vibration regions that exhibited vortex-induced vibration (VIV) synchronisation, rotation-induced galloping and desynchronised responses were observed. In both the VIV synchronisation and rotation-induced galloping regions, significant cylinder vibration was found to be correlated with wake–body synchronisation within the rotation rate range $2.20\lesssim \unicode[STIX]{x1D6FC}\lesssim 3.15$. Of significant interest, the frequency of the streamwise fluid force could be modulated by the imposed rotation to match that of the transverse lift force, resulting in harmonic synchronisation. Measurements using the particle image velocimetry (PIV) technique were performed to identify the wake structure. Interestingly, the imposed rotation can cause regular vortex shedding in in-line FIV at rotation rates that see suppression of the Bénard–von-Kármán vortex shedding in the case of a rigidly mounted cylinder ($\unicode[STIX]{x1D6FC}\gtrsim 1.75$). There is a monotonic increase in the drag coefficient with rotation rate beyond $\unicode[STIX]{x1D6FC}=2$ for a non-oscillating rotating cylinder. This suggests that the mechanism for sustaining the large rotation-induced galloping oscillations at higher $\unicode[STIX]{x1D6FC}$ is due to a combination of aerodynamic forcing from the locked induced vortex shedding associated with the oscillations, assisted by aerodynamic forcing, evaluated using quasi-steady theory.

Numerical investigation of wake flow regimes behind a high-speed rotating circular cylinder in steady flow

2019 ◽  
Vol 878 ◽  
pp. 875-906
Author(s):  
Adnan Munir ◽  
Ming Zhao ◽  
Helen Wu ◽  
Lin Lu
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Rotation Rate ◽  
High Speed ◽  
Three Dimensional ◽  
Flow Regimes ◽  
Reynolds Numbers ◽  
Wake Flow ◽  
Rotating Circular Cylinder

Flow around a high-speed rotating circular cylinder for $Re\leqslant 500$ is investigated numerically. The Reynolds number is defined as $UD/\unicode[STIX]{x1D708}$ with $U$, $D$ and $\unicode[STIX]{x1D708}$ being the free-stream flow velocity, the diameter of the cylinder and the kinematic viscosity of the fluid, respectively. The aim of this study is to investigate the effect of a high rotation rate on the wake flow for a range of Reynolds numbers. Simulations are performed for Reynolds numbers of 100, 150, 200, 250 and 500 and a wide range of rotation rates from 1.6 to 6 with an increment of 0.2. Rotation rate is the ratio of the rotational speed of the cylinder surface to the incoming fluid velocity. A systematic study is performed to investigate the effect of rotation rate on the flow transition to different flow regimes. It is found that there is a transition from a two-dimensional vortex shedding mode to no vortex shedding mode when the rotation rate is increased beyond a critical value for Reynolds numbers between 100 and 200. Further increase in rotation rate results in a transition to three-dimensional flow which is characterized by the presence of finger-shaped (FV) vortices that elongate in the wake of the cylinder and very weak ring-shaped vortices (RV) that wrap the surface of the cylinder. The no vortex shedding mode is not observed at Reynolds numbers greater than or equal to 250 since the flow remains three-dimensional. As the rotation rate is increased further, the occurrence frequency and size of the ring-shaped vortices increases and the flow is dominated by RVs. The RVs become bigger in size and the flow becomes chaotic with increasing rotation rate. A detailed analysis of the flow structures shows that the vortices always exist in pairs and the strength of separated shear layers increases with the increase of rotation rate. A map of flow regimes on a plane of Reynolds number and rotation rate is presented.

scholarly journals Unconfined laminar nanofluid flow and heat transfer around a rotating circular cylinder in the steady regime

2017 ◽  
Vol 38 (2) ◽  
pp. 3-20
Author(s):  
Rafik Bouakkaz ◽  
Fouzi Salhi ◽  
Yacine Khelili ◽  
Mohamed Quazzazi ◽  
Kamel Talbi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Rotation Rate ◽  
Volume Fraction ◽  
Steady Regime ◽  
Volume Fractions ◽  
Nusselt Numbers ◽  
Rotating Circular Cylinder ◽  
Flow And Heat Transfer

AbstractIn this work, steady flow-field and heat transfer through a copper- water nanofluid around a rotating circular cylinder with a constant nondimensional rotation rate α varying from 0 to 5 was investigated for Reynolds numbers of 5–40. Furthermore, the range of nanoparticle volume fractions considered is 0–5%. The effect of volume fraction of nanoparticles on the fluid flow and heat transfer characteristics are carried out by using a finite-volume method based commercial computational fluid dynamics solver. The variation of the local and the average Nusselt numbers with Reynolds number, volume fractions, and rotation rate are presented for the range of conditions. The average Nusselt number is found to decrease with increasing value of the rotation rate for the fixed value of the Reynolds number and volume fraction of nanoparticles. In addition, rotation can be used as a drag reduction technique.

scholarly journals Heat transfer from a rotating circular cylinder in the steady regime: Effects of Prandtl number

2012 ◽  
Vol 16 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Varun Sharma ◽  
Kumar Dhiman
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Circular Cylinder ◽  
Prandtl Number ◽  
Rotation Rate ◽  
Average Nusselt Number ◽  
Steady Regime ◽  
Rotating Circular Cylinder ◽  
Prandtl Numbers

In this work, effects of Prandtl number on the heat transfer characteristics of an unconfined rotating circular cylinder are investigated for varying rotation rate (? = 0 - 5) in the Reynolds number range 1 - 35 and Prandtl numbers range 0.7 - 100 in the steady flow regime. The numerical calculations are carried out by using a finite volume method based commercial CFD solver FLUENT. The isotherm patterns are presented for varying values of Prandtl number and rotation rate in the steady regime. The variation of the local and the average Nusselt numbers with Reynolds number, Prandtl number and rotation rate are presented for the above range of conditions. The average Nusselt number is found to decrease with increasing value of the rotation rate for the fixed value of the Reynolds and Prandtl numbers. With increasing value of the Prandtl number, the average Nusselt number increases for the fixed value of the rotation rate and the Reynolds number; however, the larger values of the Prandtl numbers show a large reduction in the value of the average Nusselt number with increasing rotation rate.

scholarly journals Experimental Investigation of Two-Degree-of-Freedom VIV of Circular Cylinder With Low Equivalent Mass and Variable Natural Frequency Ratio

2013 ◽  
Author(s):  
Narakorn Srinil ◽  
Hossein Zanganeh ◽  
Alexander Day
Keyword(s):  
Experimental Investigation ◽  
Numerical Model ◽  
Circular Cylinder ◽  
Natural Frequency ◽  
Frequency Ratio ◽  
Cross Flow ◽  
Number Range ◽  
Numerical Predictions ◽  
Equivalent Mass ◽  
Wake Oscillators

This paper presents an experimental investigation and validation of numerical prediction model for a 2-DOF VIV of a flexibly mounted circular cylinder by also accounting for the effect of geometrically nonlinear displacement coupling. A mechanical spring-cylinder system, achieving a low equivalent mass ratio in both in-line and cross-flow directions, is tested in a water towing tank and subject to a uniform steady flow in a sub-critical Reynolds number range of about 2000–50000. A generalized numerical model is based on double Duffing-van der Pol (structure-wake) oscillators which can capture the structural geometrical coupling and fluid-structure interaction effects through system cubic and quadratic nonlinearities. Experimental results are compared with numerical predictions in terms of response amplitudes, lock-in ranges and time-varying trajectories of cross-flow/in-line motions. Some good qualitative and quantitative agreements are found which encourage the use of the proposed numerical model subject to calibration and tuning of empirical coefficients. Various features of figure-of-eight orbital motions due to dual resonances are observed experimentally as well as numerically, depending on the natural frequency ratio of the oscillating cylinder.

scholarly journals Experimental Investigation of the Vortex-Induced Vibration of a Curved Cylinder

2012 ◽  
Author(s):  
Gustavo R. S. Assi ◽  
Narakorn Srinil ◽  
Cesar M. Freire ◽  
Ivan Korkischko
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Water Channel ◽  
Vortex Formation ◽  
Cross Flow ◽  
Streamwise Direction ◽  
Number Range ◽  
Vortex Induced Vibration ◽  
Horizontal Part

Experiments have been conducted in a water channel in order to investigate the vortex-induced vibration (VIV) response of a rigid section of a curved circular cylinder. Two curved configurations were tested regarding the direction of the approaching flow, a concave or a convex cylinder, in addition to a straight cylinder that served as reference. Amplitude and frequency response are presented versus reduced velocity for a wide Reynolds number range between 750 and 15,000. Trajectories in the cross-flow and streamwise direction are presented as well for several reduced velocities. Results show a distinct behaviour from the typical VIV of a straight cylinder highlighting the effect of curvature on vortex formation and excitation. The concave configuration presents relatively high amplitudes of vibration that are sustained beyond the typical synchronisation region. The mechanism behind the response is not yet clear, although authors suggest it might be related to some kind of buffeting excitation due to the disturbed flow from the upstream horizontal part.

Vortex shedding from a circular cylinder in moderate-Reynolds-number shear flow

1980 ◽  
Vol 101 (4) ◽  
pp. 721-735 ◽  
Author(s):  
Masaru Kiya ◽  
Hisataka Tamura ◽  
Mikio Arie
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Shear Flow ◽  
Vortex Shedding ◽  
Transverse Velocity ◽  
Number Range ◽  
Uniform Shear ◽  
Reynolds Number Range ◽  
Moderate Reynolds Number ◽  
Shear Parameter

The frequency of vortex shedding from a circular cylinder in a uniform shear flow and the flow patterns around it were experimentally investigated. The Reynolds number Re, which was defined in terms of the cylinder diameter and the approaching velocity at its centre, ranged from 35 to 1500. The shear parameter, which is the transverse velocity gradient of the shear flow non-dimensionalized by the above two quantities, was varied from 0 to 0·25. The critical Reynolds number beyond which vortex shedding from the cylinder occurred was found to be higher than that for a uniform stream and increased approximately linearly with increasing shear parameter when it was larger than about 0·06. In the Reynolds-number range 43 < Re < 220, the vortex shedding disappeared for sufficiently large shear parameters. Moreover, in the Reynolds-number range 100 < Re < 1000, the Strouhal number increased as the shear parameter increased beyond about 0·1.

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