Manipulating the Flow over Spherical Protuberance in a Turbulent Boundary Layer

Woszidlo, Rene; Taubert, Lutz; Wygnanski, I.

doi:10.2514/1.39930

Cited by 14 publications

(5 citation statements)

References 17 publications

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“…A multitude of passive and active means to control flow separation have been proposed and investigated. Some of the most common approaches involve vortex generators [2,3] , miniature trailing edge devices [4] , continuous and oscillatory blowing and suction [5][6][7][8][9] , microjets [10][11][12][13] , and zero-net-mass-flux actuation (e.g., plasma actuators [14] and synthetic jets [15][16][17][18][19][20][21][22][23] ). These methods and their feasibility for full-scale applications have been reviewed and evaluated by numerous authors [24][25][26][27][28][29][30] .…”

Section: Introductionmentioning

confidence: 99%

Parameters Governing Separation Control with Sweeping Jet Actuators

Woszidlo

2011

29th AIAA Applied Aerodynamics Conference

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Section: Introductionmentioning

confidence: 99%

Parameters Governing Separation Control with Sweeping Jet Actuators

Woszidlo

2011

29th AIAA Applied Aerodynamics Conference

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“…The analysis presented in this paper further studies the same data and the transition from the partial hemisphere to hemisphere geometry. Submerged hemispherical turrets have been studied both experimentally [12,13] and computationally in [14][15][16]. However, from the results of these studies it is not clear what causes the dramatic change in flow behavior.…”

Section: Introductionmentioning

confidence: 99%

Modal analysis of pressure fields on and around turrets with different protrusions

Bukowski

Kalensky

Gordeyev

et al. 2022

Unconventional Imaging and Adaptive Optics 2022

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Wind tunnel experiments were conducted to measure the unsteady surface pressure field of a hemisphere-oncylinder turret in subsonic flow. These measurements were obtained using pressure transducers coupled with fast response pressure sensitive paint. The surface pressure field data resulting from Mach 0.5 flow (Re D ≈ 2 × 10 6 ) over three different turret protrusion distances were analyzed. Previously, dominant surface pressure modes on the turret were found using proper orthogonal decomposition. The results of which showed that greater turret protrusion into the freestream flow increased the prevalence of spanwise anti-symmetric surface pressure field fluctuations. These anti-symmetric pressure fluctuations are caused by anti-symmetrical vortex shedding. However, when a partially submerged hemispherical turret geometry is used, it was shown that this anti-symmetric mode was of much lower relative energy. This suggests that there is a transition in flow field phenomena as protrusion is changed from partially submerged to a full hemisphere configuration. Further investigation into this so-called "mode switching" is the emphasis of the work presented here. This research heavily relied on modal analysis to identify correlations between turret and wake surface pressure fields. The fluctuations in the surface pressure field around the partial hemisphere were found to be mostly dominated by the wake with little influence from fluidic structures on the turret itself. For the hemisphere and hemisphere-oncylinder configurations, both symmetric and anti-symmetric unsteady separation grew to be the largest influence and was coupled with the wake fluctuations.

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“…Conversely, when the support cylinder height is less than the radius, it is expected that shedding of the cylinder body becomes less important. In the limit case, the cylindrical support vanishes completely, and the turret geometry becomes either a hemispherical or spherical shell 9,10 . In such a case, the relative importance between vortices shed off the surface and formed at the juncture depends on the ratio of the incoming boundary layer thickness and the protrusion height.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Control of a Turret Wake, Part I: Aerodynamic Effects

Vukašinović

Glezer

Gordeyev

et al. 2010

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Effects of active and hybrid flow control on the aerodynamic characteristics of flow over a 0.254 m diameter conformal optical aperture embedded in the hemispherical cap of a cylinder turret model (D = 0.61 m) are investigated at M = 0.3-0.5 and Re D = 4.4-7.4•10 6. Resulting mean flows are characterized by surface static pressure distributions and oil-flow visualizations, while the separated flow dynamics is assessed by hot-film measurements. Active flow control is effected by arrays of piezoelectrically-driven synthetic jet modules distributed in multiple arrays upstream from the aperture. Active flow control is further assisted by global flow alterations induced by a passive forward partition plate, and, when combined, constitute hybrid flow control. It is shown that the hybrid flow control combines the positive effects of its component control elements to yield superior results in any cumulative aerodynamic aspect of the separated flow. This cumulative effect of the actuation is manifested by concomitant delay of flow separation and active, dissipative suppression of turbulent motions downstream of separation. It is also demonstrated by means of direct 2D wavefront measurements that the overall aerodynamic improvements correlate with substantial suppression of optical aberrations through the separated flow. Furthermore, estimated Strehl ratios for the laser beam indicate that nearly-invariant Strehl ratio is established within the range of tested aperture elevation angles, yielding improvement of about 50% for the highest elevation angle.

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Manipulating the Flow over Spherical Protuberance in a Turbulent Boundary Layer

Cited by 14 publications

References 17 publications

Parameters Governing Separation Control with Sweeping Jet Actuators

Parameters Governing Separation Control with Sweeping Jet Actuators

Modal analysis of pressure fields on and around turrets with different protrusions

Hybrid Control of a Turret Wake, Part I: Aerodynamic Effects

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