Influence of internal acoustic excitation upon flow passing a circular cylinder

Hsiao, Fei‐Bin; Shyu, J.Y.

doi:10.1016/0889-9746(91)90429-s

Cited by 50 publications

(17 citation statements)

References 8 publications

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“…Without perturbation, C D was 1.88, falling in the range of 1.7-2.0, as previously reported by, e.g., Lee, 24 3 observed a reduced C D in an acoustically excited circular-cylinder wake. The observation was linked with a narrower wake and the smaller defect of mean velocity profile.…”

Section: ͑1͒supporting

confidence: 65%

“…Typical examples of the open-loop control include acoustic excitation, 3 oscillating or rotating cylinders, 4 -6 and surface bleeding. 7 Recently, Cheng et al 8 investigated a novel perturbation technique using curved piezoceramic actuators embedded underneath the surface of a square cylinder to alter interactions between a flexibly supported cylinder and cross flow.…”

Section: Introductionmentioning

confidence: 99%

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Closed-loop-controlled vortex shedding and vibration of a flexibly supported square cylinder under different schemes

Zhang

Zhou

2004

Physics of Fluids

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Different schemes were experimentally investigated of the closed-loop control of vortex shedding from a spring-supported square cylinder in cross flow. The control action was implemented through the perturbation of one cylinder surface, which was generated by three piezoelectric ceramic actuators, embedded underneath the surface and controlled by a proportional-integral-derivative controller. Three control schemes were investigated using different feedback signals, including the turbulent flow signal measured by a hot wire, flow-induced structural oscillation signal obtained by a laser vibrometer, and a combination of both signals. An investigation was conducted at the resonance condition, when the vortex-shedding frequency coincided with the natural frequency of the fluid-structure system. The flow and structural vibration were measured using particle image velocimetry, laser-induced fluorescence flow visualization, a laser Doppler anemometer, and a laser vibrometer. It was observed that the control scheme based on the feedback of both flow and structural oscillation led to the almost complete destruction of the Kármán vortex street and a reduction in the structural vibration, vortex shedding strength, and drag coefficient by 82%, 65%, and 35%, respectively, outperforming by far an open-loop control as well as the other two closed-loop schemes.

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Section: ͑1͒supporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Closed-loop-controlled vortex shedding and vibration of a flexibly supported square cylinder under different schemes

Zhang

Zhou

2004

Physics of Fluids

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“…The drift, which changes its sign following θ xy in Eq. (20) (Fig. 7a, b), is almost totally eliminated with LC.…”

Section: Parametric Investigation and Discussionmentioning

confidence: 99%

“…However, it is well known that the introduction of such devices along the long slender structure modifies the structural configuration and increases the drag forces, apart from their high costs in manufacturing, installation, and maintenance. Alternatively, active flow controls by introducing, for instance, a surface suction and blowing [8], an acoustic actuation [15,21], and a neighboring rotational cylinder [14,20,24] have also been explored with the aim of delaying, interrupting, or intervening in the vortex formation process in the wake. Nevertheless, due to the frequent changes and uncertainties in ocean environments, it might be impractical to accurately predict the space-time-varying vortex formations and implement the active flow control methods in real time for deep-water structures.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional vortex-induced vibration suppression through the cylinder transverse linear/nonlinear velocity feedback

Srinil

2017

Acta Mech

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Suppressing vortex-induced vibration (VIV) has recently attracted numerous researchers due to its practical significance in many engineering applications. Most of the previous studies have focused on a passive or active flow control. A structurally active control approach to mitigate a two-dimensional, nonlinear coupled, cross-flow/in-line VIV has not been well studied. This paper presents a reduced-order fluid-structure dynamic model and combined analytical-numerical solutions for the efficient suppression of two-dimensional VIV of a flexibly mounted circular cylinder in uniform flows. The theoretical model is based on the use of coupled Duffing-Rayleigh oscillators with three variables describing the cylinder cross-flow/in-line displacements and the strength of the fluid vortex circulation in the cylinder wake. These equations of fluid-structure motions contain geometric and hydrodynamic nonlinearities. Closed-loop linear and nonlinear velocity feedback controllers are implemented in the transverse direction governing the larger cross-flow response than the associated in-line counterpart. Approximated analytical expressions are derived by using the harmonic balance to explicitly capture the system nonlinear dynamic features and the effects of key dimensionless parameters. Parametric investigations are carried out to evaluate the linear versus nonlinear controller performance in terms of the maximum response suppression capability and the power requirement in a wide range of reduced flow velocities, mass ratios, and control gains. Over the main lock-in resonance region with coupled cross-flow/inline responses, the linear controller is found to be more efficient in suppressing the two-dimensional VIV by also modifying the system frequencies and phase relationships. Nevertheless, based on the power comparison, the nonlinear control is superior to the linear control for very small targeted controlled amplitudes of a very low-mass cylinder. These active control strategies may be further applied to the multimode VIV suppression of a long flexible cylinder with multi degrees of freedom.

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“…The acoustic perturbations generated from two 5 W loudspeakers were funneled into the interior of the models from both ends, and then emitted outwards to the #ow "eld through the slot exit. For most of the investigations in this study, the orientation of the slot was placed at 903 from the stagnation point of the cylinder, which has been proved to be the most e!ective angle of excitation [13]. The block diagram of the excitation system in the experiments is shown in Figure 2.…”

Section: Experimental Facility and Data Processingmentioning

confidence: 99%

Spanwise Coupling of Cellular Structures in 2-D and Tapered Circular Cylinder Wake Under Acoustic Excitation

Hsiao

Chiang

2000

Journal of Sound and Vibration

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Influence of internal acoustic excitation upon flow passing a circular cylinder

Cited by 50 publications

References 8 publications

Closed-loop-controlled vortex shedding and vibration of a flexibly supported square cylinder under different schemes

Closed-loop-controlled vortex shedding and vibration of a flexibly supported square cylinder under different schemes

Two-dimensional vortex-induced vibration suppression through the cylinder transverse linear/nonlinear velocity feedback

Spanwise Coupling of Cellular Structures in 2-D and Tapered Circular Cylinder Wake Under Acoustic Excitation

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