Suppression of vortex shedding around a square cylinder using blowing

Saha, A.; Shrivastava, Ankit

doi:10.1007/s12046-014-0331-9

Cited by 24 publications

(9 citation statements)

References 28 publications

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“…The continuous jet is a common form of injection. Based on the previous studies (Kim et al 2003;Koutmos, Papailiou & Bakrozis 2004;Akansu & Firat 2010a;Saha & Shrivastava 2015;Akansu, Firat & Hacialiogullari 2017), similar flow phenomena were observed with the variation of injection ratio R (the ratio of jet velocity to free-stream velocity) when a continuous jet was issued from the rear surface of a square cylinder. At low injection ratios, the jet does not have enough momentum to affect the main vortices.…”

Section: Introductionsupporting

confidence: 69%

“…2017), plasma actuator (Anzai et al. 2017), jet (Kim, Yang & Eom 2003; Akansu & Firat 2010 a ; Saha & Shrivastava 2015), synthetic jet (Akansu & Firat 2010 b ; Qu et al. 2017) and blowing/suction (Sohankar, Khodadadi & Rangraz 2015; Sohankar & Najafi 2018).…”

Section: Introductionmentioning

confidence: 99%

“…While at high injection ratios, the jet is strong enough to penetrate the vortex formation region and precludes the entrainment of the shear layers like a splitter plate, which may lead to the suppression of wake vortex shedding (Kim et al. 2003; Saha & Shrivastava 2015). Additionally, Kim et al.…”

Section: Introductionmentioning

confidence: 99%

“…Passive control methods, which do not need external power input, include control rod (Igarashi 1997;Zhang et al 2005;Shao & Wei 2008), splitter plate (Bearman & Trueman 1972;Ali, Doolan & Wheatley 2011), corner modification (Hu, Zhou & Dalton 2006;Ueda et al 2009;He, Li & Wang 2014), surface roughness (van Hinsberg, Schewe & Jacobs 2018), and so on. Active control methods, which need extra energy supply, include but are not limited to, rotation (Chatterjee & Gupta 2015a,b), oscillation (Bearman & Obasaju 1982;Fu et al 2017), plasma actuator (Anzai et al 2017), jet (Kim, Yang & Eom 2003;Akansu & Firat 2010a;Saha & Shrivastava 2015), synthetic jet (Akansu & Firat 2010b;Qu et al 2017) and blowing/suction (Sohankar, Khodadadi & Rangraz 2015;Sohankar & Najafi 2018). Compared with passive control, active control is much easier to change the control parameters according to the external flow conditions, and it can be more efficient and energy-saving if sensors are introduced to establish a feedback system.…”

Section: Introductionmentioning

confidence: 99%

“…The jet induces small vortices behind the cylinder and pushes the main recirculation region further downstream, elongating the overall recirculation length in the streamwise direction. While at high injection ratios, the jet is strong enough to penetrate the vortex formation region and precludes the entrainment of the shear layers like a splitter plate, which may lead to the suppression of wake vortex shedding (Kim et al 2003;Saha & Shrivastava 2015). Additionally, Kim et al (2003) performed the numerical simulation in both laminar (Re = 200) and turbulent (Re = 8520) conditions.…”

Section: Introductionmentioning

confidence: 99%

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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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