Journal ArticleDOI
Three-dimensional vortex structure on a rotating wing
C. A. Ozen,Donald Rockwell +1 more
TLDR
In this article, the three-dimensional structure of the leading-edge vortex on a rotating wing is addressed using a technique of particle image velocimetry, where organized patterns of chordwise-oriented vorticity arise from the spanwise flow along the surface of the wing, which can attain a velocity the same order as the wing at its radius of gyration.Abstract:
The three-dimensional structure of the leading-edge vortex on a rotating wing is addressed using a technique of particle image velocimetry. Organized patterns of chordwise-oriented vorticity, which exist within the vortex, arise from the spanwise flow along the surface of the wing, which can attain a velocity the same order as the velocity of the wing at its radius of gyration. These patterns are related to the strength (circulation) and coherence of the tip and root vortices. The associated distributions of spanwise-oriented vorticity along the leading-edge vortex are characterized in relation to the vorticity flux and downwash along the wing.read more
Citations
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Journal ArticleDOI
Vorticity transport in the leading-edge vortex on a rotating blade
Craig Wojcik,James Buchholz +1 more
TL;DR: In this paper, the leading edge vortex generated on a rectangular flat plate of aspect ratio 4 undergoing a starting rotation motion in a quiescent fluid is analyzed and two analyses are conducted on the inboard half of the blade to better understand the vorticity transport mechanisms responsible for maintaining the quasi-equilibrium state of the leading-edge vortex.
Journal ArticleDOI
Dynamics of revolving wings for various aspect ratios
TL;DR: In this article, high-fidelity, direct numerical simulations are conducted to examine the vortex structure and aerodynamic loading of unidirectionally revolving wings in quiescent fluid.
Journal ArticleDOI
Hydrodynamics of swimming in stingrays: numerical simulations and the role of the leading-edge vortex
TL;DR: In this paper, large-eddy simulations of a self-propelled stingray, modelled closely after the freshwater stingray Potamotrygon orbignyi, are performed.
Journal ArticleDOI
Finite-span rotating wings: three-dimensional vortex formation and variations with aspect ratio
TL;DR: In this article, the effect of aspect ratio on the three-dimensional flow structure of flat-plate wings rotating from rest at 45° angle of attack was investigated experimentally, and the results showed that the resulting vorticity and velocity increased with the number of wing rotations.
Journal ArticleDOI
Aspect-ratio effects on rotating wings: circulation and forces
TL;DR: In this article, the authors employ experiments to study aspect ratio effects on the vortex structure, circulation and lift force for flat-plate wings rotating from rest at 45°-angle of attack, which represents a simplified hovering-wing halfstroke.
References
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Journal ArticleDOI
Leading-edge vortices in insect flight
Charles P. Ellington,Coen van den Berg,Coen van den Berg,Alexander P. Willmott,Adrian L. R. Thomas,Adrian L. R. Thomas +5 more
TL;DR: In this article, the authors visualized the airflow around the wings of the hawkmoth Manduca sexta and a 'hovering' large mechanical model, and found an intense leading-edge vortex was found on the downstroke, of sufficient strength to explain the high-lift forces.
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Spanwise flow and the attachment of the leading-edge vortex on insect wings
TL;DR: It is reported that, at the Reynolds numbers matching the flows relevant for most insects, flapping wings do not generate a spiral vortex akin to that produced by delta-wing aircraft, and it is found that limiting spanwise flow with fences and edge baffles does not cause detachment of the leading-edge vortex.
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Rotational accelerations stabilize leading edge vortices on revolving fly wings
TL;DR: The analysis and experiments suggest that the mechanism responsible for LEV stability is not dependent on Reynolds number, at least over the range most relevant for insect flight (100
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A computational fluid dynamic study of hawkmoth hovering
TL;DR: This CFD analysis has established an overall understanding of the viscous and unsteady flow around the flapping wing and of the time course of instantaneous force production, which reveals that hovering flight is dominated by the unsteadY aerodynamics of both the instantaneous dynamics and also the past history of the wing.
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Force production and flow structure of the leading edge vortex on flapping wings at high and low Reynolds numbers.
TL;DR: The results suggest that the transport of vorticity from the leading edge to the wake that permits prolonged vortex attachment takes different forms at different Re, analogous to the flow structure generated by delta wing aircraft.