Suppression of vortex-induced vibration using moving surface boundary-layer control

Korkischko, Ivan; Meneghini, Júlio Romano

doi:10.1016/j.jfluidstructs.2012.05.010

Cited by 123 publications

(38 citation statements)

References 32 publications

(45 reference statements)

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“…The measurements of mean drag demonstrate that these con gurations do not reduce the mean drag coe cients as much as reported experimentally by Korkischko & Meneghini (2012) and with numerical simulation by Mittal (2001). A considerable reduction of the mean drag coe cient was achieved when the eight control cylinders are xed (U c /U = 0).…”

Section: Resultssupporting

confidence: 61%

“…For the con guration of two xed control cylinders Korkischko & Meneghini (2012) , 1971). Korkischko & Meneghini (2012) suggested that the fact that the xed control cylinders x the boundary-layer separation points, the cylinder could be subjected to this phenomenon.…”

Section: Response With Four Control Cylindersmentioning

confidence: 99%

“…Korkischko & Meneghini (2012) suggested that the fact that the xed control cylinders x the boundary-layer separation points, the cylinder could be subjected to this phenomenon.…”

Section: Response With Four Control Cylindersmentioning

confidence: 99%

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Suppression of vortex-induced vibration of a circular cylinder with fixed and rotating control cylinders.

Ortega¹

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Section: Resultssupporting

confidence: 61%

Section: Response With Four Control Cylindersmentioning

confidence: 99%

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Suppression of vortex-induced vibration of a circular cylinder with fixed and rotating control cylinders.

Ortega¹

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“…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 proposed means include splitter plates (Bearman 1965;Kwon & Choi 1996;Assi et al 2009;Gu et al 2012;Bao & Tao 2013), (Serson et al 2014), suction based flow control (Dong et al 2008;Chen et al 2013), moving boundary layer control (Korkischko & Meneghini 2012), slits parallel to the incoming flow (Baek & Karniadakis 2009), stream-lining of the structural geometry (Pontaza & Menon 2008;Corson et al 2014), helical strakes (Allen et al 2003;Trim et al 2005), and other add-on devices for passive control (Owen et al 2001;Bearman & Branković 2004). …”

Section: Introductionmentioning

confidence: 99%

U-shaped fairings suppress vortex-induced vibrations for cylinders in cross-flow

Xie

Constantinides

et al. 2015

J. Fluid Mech.

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We employ three-dimensional direct and large-eddy numerical simulations of the vibrations and flow past cylinders fitted with free-to-rotate U-shaped fairings placed in a cross-flow at Reynolds number 100Re 10, 000. Such fairings are nearly-neutrally buoyant devices fitted along the axis of long circular risers to suppress vortex-induced vibrations (VIV). We consider three different geometric configurations, a homogeneous fairing, and two configurations (denoted A and AB) involving a gap between adjacent segments. For the latter two cases, we investigate the effect of the gap on the hydrodynamic force coefficients and the translational and rotational motions of the system. For all configurations, as the Reynolds number increases beyond 500, both the lift and drag coefficients decrease. Compared to a plain cylinder, a homogeneous fairing system (no gaps) can help reduce the drag force coefficient by 15% for reduced velocity U * = 4.65, while a type A gap system can reduce the drag force coefficient by almost 50% for reduced velocity U * = 3.5, 4.65, 6, and, correspondingly, the vibration response of the combined system, as well as the fairing rotation amplitude are substantially reduced. For a homogeneous fairing, the cross-flow amplitude is reduced by about 80%, whereas for fairings with a gap longer than half a cylinder diameter, VIV are completely eliminated, resulting in additional reduction in the drag coefficient. We have related such VIV suppression or elimination to the features of the wake flow structure. We find that a gap causes the generation of strong streamwise vorticity in the gap region that interferes destructively with the vorticity generated by the fairings, hence disorganizing the formation of coherent spanwise cortical patterns. We provide visualization of the incoherent wake flow that leads to total elimination of the vibration and rotation of the fairing-cylinder system. Finally, we investigate the effect of the frictional coefficient between cylinder and fairing; the effect overall is small, even when the frictional coefficients of adjacent segments are different. In some cases the equilibrium positions of the fairings are rotated by a small angle on either side of the centerline, in a symmetry-breaking bifurcation, which depends strongly on Reynolds number.

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Suppression of vortex-induced vibration using moving surface boundary-layer control

Cited by 123 publications

References 32 publications

Suppression of vortex-induced vibration of a circular cylinder with fixed and rotating control cylinders.

Suppression of vortex-induced vibration of a circular cylinder with fixed and rotating control cylinders.

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

U-shaped fairings suppress vortex-induced vibrations for cylinders in cross-flow

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