Finite-span rotating wings: three-dimensional vortex formation and variations with aspect ratio

Carr, Zakery R.; Chen, C.; Ringuette, Matthew

doi:10.1007/s00348-012-1444-8

Cited by 81 publications

(73 citation statements)

References 101 publications

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“…The disintegration of the TV also occurs in the case of pitching wing with shedding of secondary trailing edge vortices during the buildup phase; however, it is not as severe as for the surging case. In accordance with what was reported by Carr et al (2013), the liftoff of the LEV is observed at d * = 1 (φ = 25.8 • ) for the first time in the surging case. As of d * = 2, the flow fields display small-scale substructures appearing in the vortex system in both cases.…”

Section: Discussionsupporting

confidence: 76%

“…The inboard structure is not captured due to the limited extent of the measurement domain, but is presumed to display an inner leg reattachment inboards closer to the root. The revolving-surging wing has a similar arch-shaped structure, which was also reported by Garmann et al (2013) for a lower-aspect-ratio wing and different acceleration kinematics and by Carr et al (2013) for different acceleration kinematics. However, the outer leg of this structure does not attach to the wing surface at the front corner but slightly more toward the trailing edge (near 0.4c).…”

Section: Flow-field Structuresupporting

confidence: 48%

“…They also compared revolving and translating wings and reported that although similar patterns are present at the onset of the motion, the following period of the two motions generate significantly different flow fields. The liftoff and the subsequent breakdown of the LEV were also reported by Carr et al (2013). They investigated the effect of aspect ratio on the three-dimensional flow structures of revolving wings at 45º angle of attack.…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

Perçin

Oudheusden

2015

Exp Fluids

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Section: Discussionsupporting

confidence: 76%

Section: Flow-field Structuresupporting

confidence: 48%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

Perçin

Oudheusden

2015

Exp Fluids

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“…Widmann and Tropea [75] have recently used experiments to investigate mechanisms responsible for the formation and detachment of LEVs. Other recent contributions characterizing 3D vortical structures on unsteady plates using high-fidelity simulations and experiments include those by Visbal et al [72], Devoria and Ringuette [15], Carr et al [9], Jones and Babinsky [32,33], Panah et al [53], and Bos et al [5].…”

Section: Introductionmentioning

confidence: 99%

Leading-edge flow criticality as a governing factor in leading-edge vortex initiation in unsteady airfoil flows

Ramesh

Granlund

et al. 2017

Theor. Comput. Fluid Dyn.

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A leading-edge suction parameter (LESP) that is derived from potential flow theory as a measure of suction at the airfoil leading edge is used to study initiation of leading-edge vortex (LEV) formation in this article. The LESP hypothesis is presented, which states that LEV formation in unsteady flows for specified airfoil shape and Reynolds number occurs at a critical constant value of LESP, regardless of motion kinematics. This hypothesis is tested and validated against a large set of data from CFD and experimental studies of flows with LEV formation. The hypothesis is seen to hold except in cases with slow-rate kinematics which evince significant trailing-edge separation (which refers here to separation leading to reversed flow on the aft portion of the upper surface), thereby establishing the envelope of validity. The implication is that the critical LESP value for an airfoil-Reynolds number combination may be calibrated using CFD or experiment for just one motion and then employed to predict LEV initiation for any other (fast-rate) motion. It is also shown that the LESP concept may be used in an inverse mode to generate motion kinematics that would either prevent LEV formation or trigger the same as per aerodynamic requirements.

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“…Relative locations of the individual volumes were changed by adjusting the location of the mechanical wing, while the physical V3V measurement volume remained fixed at the centre of the tank. Note that this approach was based on the fact that the flow was repeatable between different strokes owing to the precise control of the wing kinematics and that similar approaches were applied when reconstructing the three-dimensional velocity field from stereoscopic PIV measurements on two-dimensional planes [13,16,35].…”

mentioning

confidence: 99%

Three-dimensional vortex wake structure of flapping wings in hovering flight

Cheng

Roll

Liu

et al. 2014

J. R. Soc. Interface.

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Flapping wings continuously create and send vortices into their wake, while imparting downward momentum into the surrounding fluid. However, experimental studies concerning the details of the three-dimensional vorticity distribution and evolution in the far wake are limited. In this study, the three-dimensional vortex wake structure in both the near and far field of a dynamically scaled flapping wing was investigated experimentally, using volumetric three-component velocimetry. A single wing, with shape and kinematics similar to those of a fruitfly, was examined. The overall result of the wing action is to create an integrated vortex structure consisting of a tip vortex (TV), trailing-edge shear layer (TESL) and leading-edge vortex. The TESL rolls up into a root vortex (RV) as it is shed from the wing, and together with the TV, contracts radially and stretches tangentially in the downstream wake. The downwash is distributed in an arc-shaped region enclosed by the stretched tangential vorticity of the TVs and the RVs. A closed vortex ring structure is not observed in the current study owing to the lack of well-established starting and stopping vortex structures that smoothly connect the TV and RV. An evaluation of the vorticity transport equation shows that both the TV and the RV undergo vortex stretching while convecting downwards: a three-dimensional phenomenon in rotating flows. It also confirms that convection and secondary tilting and stretching effects dominate the evolution of vorticity.

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Finite-span rotating wings: three-dimensional vortex formation and variations with aspect ratio

Cited by 81 publications

References 101 publications

Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

Leading-edge flow criticality as a governing factor in leading-edge vortex initiation in unsteady airfoil flows

Three-dimensional vortex wake structure of flapping wings in hovering flight

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