The response and symmetry properties of a cylinder wake subjected to localized surface excitation

Williams, David R.; Mansy, Hansen A.; Amato, C. W.

doi:10.1017/s0022112092000703

Cited by 80 publications

(44 citation statements)

References 27 publications

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“…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. Given a properly set perturbation frequency, both vortex shedding and vortex-induced vibration were significantly reduced as a result from actuator-generated surface perturbation.…”

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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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: 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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“…Steady blowing effect, tangentially to the cylinder model through a slot has been investigated by Waka et al (1985) and illustrates the modification of the flow for various positions and shapes of the injector. The recent development of synthetic or pulsed jets (Amitay et al, 1997;Williams et al, 1992) on cylinder models has proved that such a new technique is a very efficient way to manipulate the flow. These types of unsteady pneumatic actuators have the characteristics of being possibly miniaturized, they do not produce any average mass addition to the near wake and they require very little energy.…”

Section: Introductionmentioning

confidence: 99%

Modification of the wake behind a circular cylinder by using synthetic jets

Tensi

Boué

Paille

et al. 2002

J Vis

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Experimental tests were conducted to control the flow around a cylinder by means of unsteady blowing (synthetic jet) through a single slot disposed on the wall of the model. The flow Reynolds number (based on the diameter of the model) was RD =10 5 • The efficiency of the syntheticjet is quantified in terms of delaying separation and modifying the drag coefficient. The investigations were of three types: measurements of the mean pressure distribution, wall visualizations of the separation line position and measurementsof the mean flow-field in the wake.

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“…An important aspect of the synthetic jet for flow control is to manipulate the flow seperation around a circular cylinder. In most of the previous works, the jet exit was usually positioned near the separation point or inside the separation region [3][4][5][6] . Amitay et al [3] experimentally investigated the cylinder flow control with synthetic jets, which issued from a pair of slots with the jet exit angle α from 0° to 180°.…”

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confidence: 99%

“…They both found that the synthetic jets could efficaciously delay flow seperation and enable the seperation region to become much smaller and even completely disappearing, which led to a reduction in drag. Besides, Williams et al [6] also placed the jet exit orifice near the upstream of the separation point and they pointed out that the jet could substantially alter the mode of the near-wake vortex formation, including a limiting case where the formation of large-scale Karman vortices were controlled.…”

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confidence: 99%

Experimental investigations on separation control and flow structure around a circular cylinder with synthetic jet

Wang

Feng

2007

SCI CHINA SER E

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Circular cylinder separation control and flow structure influenced by the synthetic jet have been experimentally investigated in a water channel. The synthetic jet issues from a slot and ejects toward upstream from the front stagnation point of the cylinder. It has been found that, similar to the traditional synthetic jet which is positioned near the separation point or inside the separation region, the present synthetic jet arrangement constitutes an efficient way to control flow separation of the circular cylinder, but with a different control mechanism. The present synthetic jet leads to an upstream displacement of the front stagnation point and the formation of a vortex pair near both sides of the exit orifice. When Re U based on the synthetic jet average exit orifice velocity is about lower than 43, a closed envelope forms in front of the windward side of the cylinder during the blowing cycle of synthetic jet, which acts as an apparent modification for the cylinder configuration. When Re U is high enough, an open envelope forms upstream of the cylinder, and the flow around the cylinder becomes much energetic. Thus, regardless of Re U , the present synthetic jet can improve separation for flow around a circular cylinder. With regard to the leeward side, as Re U increases, the flow separation region behind the cylinder gradually disappears. The flow over cylinder may be fully attached when the open envelope forms upstream of the cylinder and Re U is greater than 344. Then, the flow past the cylinder will converge near the back stagnation point of the cylinder, where a new vortex pair shedding periodically is generated due to the high shear layer. flow control, synthetic jet, flow around a cylinder, vortex structureThe synthetic jet is a kind of new active flow control technology improved by the research group of Glezer [1] in the late 1990s. They carried out a deep study on the synthetic jet formation and evolution mechanism, and divided the flow field into two different regions: near-field region and

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The response and symmetry properties of a cylinder wake subjected to localized surface excitation

Cited by 80 publications

References 27 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

Modification of the wake behind a circular cylinder by using synthetic jets

Experimental investigations on separation control and flow structure around a circular cylinder with synthetic jet

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