Drag Reduction by Manipulation of Afterbody Vortices

Bulathsinghala, Dinitha; Zhijin, Wang; Gursul, Ismet

doi:10.2514/1.c034957

Cited by 12 publications

(7 citation statements)

References 27 publications

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“…Similar to some other studies (e.g. Bulathsinghala et al, 2018), in our experiments the boundary layer developing along the model was not tripped. According to the study of Britcher and Alcorn (1991) in which the drag of a slanted-base cylinder with the boundary layer tripped and untripped was measured, the effect of boundary layer states on the drag was negligible.…”

Section: Experimental Facility and The Test Modelsupporting

confidence: 91%

“…The flow physics of the vortex mode have been studied experimentally by Epstein et al, (1994), Bury et al, (2013) and Jackson et al, (2015) and a summary of the flow topology was given by Zigunov et al, (2020a). Bulathsinghala et al, (2018) studied the effect of small flaps and spoilers installed perpendicularly onto the slanted-base and reported that these passive flow control devices could interrupt and displace the streamwise vortex pair, resulting in a drag reduction of about 5%.…”

Section: Introductionmentioning

confidence: 99%

“…The surface pressure is seen to increase further downstream. The pressure data obtained byBulathsinghala et al, (2018) for a slanted-base cylinder with a slant angle of 28 • is also shown for comparison in the same figure. Note, the…”

mentioning

confidence: 99%

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Control of afterbody vortices from a slanted-base cylinder using sweeping jets

et al. 2022

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In this paper, a sweeping jet is applied to control the afterbody vortices behind a slanted-base cylinder for the first time at Reynolds numbers from 87,000 to 200,000. The control effects are examined using stereo Particle Image Velocimetry (PIV) and surface pressure measurements with the jet momentum coefficient (Cμ) varying from 0.056 to 0.893. It is found that the sweeping jet results in increasingly diffused and larger afterbody vortices as Cμ increases. While an increase in Cμ up to 0.167 leads to a reduction in the circulation of the afterbody vortices and their earlier detachment from the slanted base, a further increase in Cμ introduces additional vorticity into the afterbody vortices leading to higher vortex strength, which could be detrimental to the control purpose. The interaction mechanism of sweeping jets lies in that turbulence is injected into the afterbody vortices as the sweeping jet intersects with these vortices and this subsequently causes diffusion of velocity gradient in the vortices which weakens their strength. As the sweeping jet spreads itself sideways while it propagates downstream along the endplate, it pushes the afterbody vortices upwards and to the side. The impact of the sweeping jet has resulted in the dominant vortex wandering frequency of the afterbody vortex being locked to that of the sweeping jet. This also causes the afterbody vortices detach themselves from the endplate earlier resulting in a shorter low-pressure footprint on the surface.

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Section: Experimental Facility and The Test Modelsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Control of afterbody vortices from a slanted-base cylinder using sweeping jets

et al. 2022

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“…Several studies have elucidated the sequence of events that result in the vortex regime of interest in this work [1,[4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Despite the known drag reduction benefits of diminishing the strength of the counter-rotating streamwise vortices, there is relatively little understanding of the underlying instabilities which could provide guidance for flow control. As such, passive control efforts to date have considered trial and error strategies such as vertical strakes [7], vortex generators [8] and flaps/spoilers [5,9] on the aft-body. Active flow controls [10] explored the inception and formation of the vortices through specific energy inputs and drag reductions of 3 − 11% were observed depending on model incidence.…”

Section: Introductionmentioning

confidence: 99%