Wavelet multi-scale analysis of the circular cylinder wake under synthetic jets control

Feng, Li-Hao; Ran, Ling-Ke

doi:10.1016/j.ijheatfluidflow.2017.12.003

Cited by 8 publications

(3 citation statements)

References 36 publications

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“…According to previous studies of scholars (Wang et al 2016, 2019b, Feng and Ran 2018, when a pair of synthetic jets ejected horizontally is symmetrically placed at the circular cylinder's leeward side, both asymmetric vortex shedding and VIV response of the circular cylinder can be suppressed by synthetic jets. Besides, Rabiee and Farahani (2020) analyzed the influence of synthetic jets injected vertically from the slots embedded in the bottom wall on the vortex shedding and VIV of a heated spring circular cylinder in a channel.…”

Section: Introductionmentioning

confidence: 96%

The influence of reduced velocity on the control of two-degree-of-freedom vortex induced vibrations of a circular cylinder via synthetic jets

Wang¹,

Yu²,

Sun³

et al. 2022

Fluid Dyn. Res.

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A two-dimensional numerical study is conducted to investigate the influence of the reduced velocity on two-degree-of-freedom VIVs of a circular cylinder controlled by synthetic jets ejected in horizontal and vertical directions (β = 0° and β = 90°). The Reynolds number is constant at Re = 150, and the reduced velocity varies in the range of 2.5 and 15 (U* = 2.5-15). The mass ratio of the circular cylinder is 2,0, and the in-flow to the cross-flow natural frequency ratio equals 1.0 (fnx/fny = 1.0). The oscillation characters, hydrodynamic forces and vortex shedding of circular cylinders with or without synthetic jets control are analyzed and compared. The results indicate that synthetic jets ejected in vertical direction (β = 90°) can intensify both in-flow and cross-flow oscillations of the circular cylinder in the whole reduced velocity range, the vortex shedding of the controlled case (β = 90°) becomes complicated even unstable with the reduced velocity increasing. Synthetic jets ejected in horizontal direction (β = 0°) have excellent performance on suppressing the cross-flow oscillation of the circular cylinder in the whole reduced velocity range. When U* ≥ 8.0, the in-flow oscillation of the circular cylinder can even be intensified by synthetic jets ejected in horizontal direction (β = 0°).

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Section: Introductionmentioning

confidence: 96%

The influence of reduced velocity on the control of two-degree-of-freedom vortex induced vibrations of a circular cylinder via synthetic jets

Wang¹,

Yu²,

Sun³

et al. 2022

Fluid Dyn. Res.

View full text Add to dashboard Cite

show abstract

“…Further, the flow dynamics were interpreted using the proper orthogonal decomposition (POD) method and the wavelet multi-scale analysis (Feng et al. 2011; Feng & Ran 2018). The synthetic jet was also placed at the front stagnation point of a circular cylinder (Wang, Feng & Xu 2007; Feng & Wang 2014).…”

Section: Introductionmentioning

confidence: 99%

“…For a certain stroke length, three wake vortex-shedding states were captured as the momentum coefficient increased: antisymmetric von Kármán vortex-shedding mode, shedding modes varying between the antisymmetric and symmetric ones, and symmetric shedding mode (Feng, Wang & Pan 2011). Further, the flow dynamics were interpreted using the proper orthogonal decomposition (POD) method and the wavelet multi-scale analysis (Feng et al 2011;Feng & Ran 2018). The synthetic jet was also placed at the front stagnation point of a circular cylinder (Wang, Feng & Xu 2007;.…”

Section: Introductionmentioning

confidence: 99%

Effect of excitation frequency on flow characteristics around a square cylinder with a synthetic jet positioned at front surface

Wang

Feng

et al. 2019

J. Fluid Mech.

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The flow over a square cylinder controlled by a slot synthetic jet positioned at the front surface is investigated experimentally at different excitation frequencies. The Reynolds number based on the free-stream velocity and the side length of the square cylinder is 1000. The flow visualization was conducted using the laser-induced fluorescence technique. The velocity fields upstream and downstream of the square cylinder were measured synchronously with the two-dimensional time-resolved particle image velocimetry technique. Both the evolution of vortex structures and the characteristic frequencies of upstream and downstream flow fields are presented. The flow dynamics vary significantly with the excitation frequency at a fixed stroke length. During one excitation cycle, the synthetic jet vortex pair deflects to one side and later swings to the other side at a quite small excitation frequency of $f_{e}/f_{0}=0.6$, while it only deflects toward one side and does not turn to the other side at $f_{e}/f_{0}=1.0$. Compared with the natural case, the wake characteristics for the above two cases are not changed much by the synthetic jet adopted. At a moderate excitation frequency of $f_{e}/f_{0}=2.0$, the synthetic jet deflects upwards and downwards alternatively. The upstream flow field has a dominant frequency identical to half of the excitation frequency. Under the perturbations of the synthetic jet, two wake vortex pairs are formed per shedding cycle with a shedding frequency equal to that of the square cylinder without control. At a higher excitation frequency of $f_{e}/f_{0}=3.4$, the synthetic jet keeps deflecting to one side, and the upstream flow field is governed by the excitation frequency. The flow separation on the deflected side is suppressed effectively, and no periodic vortex shedding can be observed in the wake. Statistically, the velocity profiles also change with control. The recirculation bubble length in the wake is shortened, and the time-averaged velocity fluctuation is weakened remarkably. The control effects of the synthetic jet and the continuous jet are compared in this paper when placed at the front surface of a square cylinder.

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Coherent pressure and acceleration estimation from triply decomposed turbulent bluff-body wakes

Shanmughan,

Passaggia,

Mazellier

et al. 2024

Exp Fluids

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Wavelet multi-scale analysis of the circular cylinder wake under synthetic jets control

Cited by 8 publications

References 36 publications

The influence of reduced velocity on the control of two-degree-of-freedom vortex induced vibrations of a circular cylinder via synthetic jets

The influence of reduced velocity on the control of two-degree-of-freedom vortex induced vibrations of a circular cylinder via synthetic jets

Effect of excitation frequency on flow characteristics around a square cylinder with a synthetic jet positioned at front surface

Coherent pressure and acceleration estimation from triply decomposed turbulent bluff-body wakes

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