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On the distribution of leading-edge vortex circulation in samara-like flight

Published online by Cambridge University Press:  10 July 2015

Eric Limacher  and
David E. Rival
Eric Limacher*
Affiliation:
Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB, T2L 1Y6, Canada
David E. Rival
Affiliation:
Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB, T2L 1Y6, Canada Department of Mechanical and Materials Engineering, Queen’s University, Kingston, ON, K7L 3N6, Canada
*
†Email address for correspondence: ejlimach@ucalgary.ca
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Abstract

As an abstraction of natural samara flight, steadily rotating plates in a free-stream flow have been studied. Particle image velocimetry on span-normal planes has been conducted to show that increasing rotation, as captured by the dimensionless parameter of tip speed ratio, causes a transition of the mean wake topology from that of a bluff body to that of a stable leading-edge vortex. Despite its notable effect on topology, a change in tip speed ratio has negligible effect on leading-edge circulation at a given spanwise position, local effective angle of attack and local effective velocity. The effective angle-of-attack distribution was held constant at different tip speed ratios by comparing rotating plates with different twist profiles. The shear-layer velocity profile at the leading edge was also resolved, allowing quantification of the vorticity flux passing through the leading-edge shear layer. Interestingly, the observed equilibrium values of circulation are not sensitive to changes in shear-layer vorticity flux.

JFM classification

Biological Fluid Dynamics: Biological Fluid Dynamics Vortex Flows: Vortex Flows
Type
Papers
Information
Journal of Fluid Mechanics , Volume 776 , 10 August 2015 , pp. 316 - 333
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Copyright
© 2015 Cambridge University Press 

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References

van den Berg, C. & Ellington, C. P. 1997 The vortex wake of a ‘hovering’ model hawkmoth. Phil. Trans. R. Soc. Lond. A 352, 317–328.Google Scholar
Bross, M., Ozen, C. A. & Rockwell, D. 2013 Flow structure on a rotating wing; effect of steady incident flow. Phys. Fluids 25, 081901.Google Scholar
Ellington, C. P., van den Berg, C., Willmott, A. P. & Thomas, A. L. R. 1996 Leading-edge vortices in insect flight. Nature 384, 626–630.Google Scholar
Garmann, D. J., Visbal, M. & Orkwis, P. D. 2013 Three-dimensional flow structure and aerodynamic loading on a revolving wing. Phys. Fluids 25, 034101.Google Scholar
Harbig, R. R., Sheridan, J. & Thompson, M. C. 2013 Reynolds number and aspect ratio effects on the leading-edge vortex for rotating insect wing planforms. J. Fluid Mech. 717, 166–192.CrossRefGoogle Scholar
Jones, A. R. & Babinsky, H. 2010 Unsteady lift generation on rotating wings at low Reynolds numbers. J. Aircraft 47 (3), 1013–1021.Google Scholar
Jones, A. R. & Babinsky, H. 2011 Reynolds number effects on leading edge vortex development on a waving wing. Exp. Fluids 51, 197–210.CrossRefGoogle Scholar
Lee, S. J., Lee, E. J. & Sohn, M. H. 2014 Mechanism of autorotation flight of maple samaras (Acer palmatum). Exp. Fluids 55, 1718.CrossRefGoogle Scholar
Lentink, D. & Dickinson, M. H. 2009 Rotational accelerations stabilize leading edge vortices on revolving fly wings. J. Expl Biol. 212, 2705–2719.Google Scholar
Lentink, D., Dickson, W. B., van Leeuwen, J. L. & Dickinson, M. H. 2009 Leading-edge vortices elevate lift of autorotating plant seeds. Science 324, 1438–1440.Google Scholar
Lugt, H. J. 1985 Vortex flow and maximum principles. Am. J. Phys. 53, 649–653.CrossRefGoogle Scholar
Maxworthy, T. 2007 The formation and maintenance of a leading-edge vortex during the forward motion of an animal wing. J. Fluid Mech. 587, 471–475.Google Scholar
Ozen, C. A. & Rockwell, D. 2012 Flow structure on a rotating plate. Exp. Fluids 52, 207–223.Google Scholar
Salcedo, E., Trevino, C., Vargas, R. O. & Martinex-Suastegui, L. 2013 Stereoscopic particle image velocimetry measurements of the three-dimensional flow field of a descending autorotating mahogany seed (Swietenia macrophylla). J. Expl Biol. 216, 2017–2030.Google Scholar
Sattari, P., Rival, D. E., Martinuzzi, R. J. & Tropea, C. 2012 Growth and separation of a start-up vortex from a two-dimensional shear layer. Phys. Fluids 24, 107102.Google Scholar
Usherwood, J. R. & Ellington, C. P. 2002 The aerodynamics of revolving wings: I. Model hawkmoth wings. J. Expl Biol. 205, 1547–1564.Google Scholar
Wojcik, C. J. & Buchholz, J. H. J. 2014 Vorticity transport in the leading-edge vortex on a rotating blade. J. Fluid Mech. 743, 249–261.Google Scholar
Wong, J. G., Kriegseis, J. & Rival, D. E. 2013 An investigation into vortex growth and stabilization for two-dimensional plunging and flapping plates with varying sweep. J. Fluids Struct. 43, 231–243.Google Scholar
Zannetti, L. & Gourjii, A. 2014 Two-vortex equilibrium in the flow past a flat plate at incidence. J. Fluid Mech. 755, 50–61.Google Scholar

Limacher supplementary movie

Dye visualization videos at four tip speed ratios (increasing from left to right), and two fixed inclination angles of the flat plate relative to the swept disk (τ = 0 and 20 degrees). Purple streaklines of dye emanate from a port 1mm from the leading edge on the pressure side of the plate. The streakline is observed to draw closer to the suction side of the plate with increasing tip speed ratio, and clearly stagnates onto the suction side of the plate at the highest tip speed ratio. Span-wise flow also becomes more prominent as tip speed ratio increases.

Download Limacher supplementary movie(Video)
Video 4 MB