Hostname: page-component-745bb68f8f-cphqk Total loading time: 0 Render date: 2025-01-08T04:30:22.606Z Has data issue: false hasContentIssue false
  • English
  • Français

On the mechanism of high-incidence lift generation for steadily translating low-aspect-ratio wings

Published online by Cambridge University Press:  17 January 2017

Adam C. DeVoria  and
Kamran Mohseni
Adam C. DeVoria
Affiliation:
Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA
Kamran Mohseni*
Affiliation:
Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

High-incidence lift generation via flow reattachment is studied. Different reattachment mechanisms are distinguished, with dynamic manoeuvres and tip vortex downwash being separate mechanisms. We focus on the latter mechanism, which is strictly available to finite wings, and isolate it by considering steadily translating wings. The tip vortex downwash provides a smoother merging of the flow at the trailing edge, thus assisting in establishing a Kutta condition there. This decreases the strength/amount of vorticity shed from the trailing edge, and in turn maintains an effective bound circulation resulting in continued lift generation at high angles of attack. Just below the static lift-stall angle of attack, strong vorticity is shed at the trailing edge indicating an increasingly intermittent reattachment/detachment of the instantaneous flow at mid-span. Above this incidence, the trailing-edge shear layer increases in strength/size representing a negative contribution to the lift and leads to stall. Lastly, we show that the mean-flow topology is equivalent to a vortex pair regardless of the particular physical flow configuration.

JFM classification

Aerodynamics: Aerodynamics Wakes/Jets: Separated flows Vortex Flows: Vortex Flows
Type
Papers
Information
Journal of Fluid Mechanics , Volume 813 , 25 February 2017 , pp. 110 - 126
Check for updates
Copyright
© 2017 Cambridge University Press 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

AIAA Standards2003 Calibration and use of internal strain-gage balances with application to wind tunnel testing. Report AIAA Recommended Practice R-091-2003.Google Scholar
Batchelor, G. K. 1956 A proposal concerning laminar wakes behind bluff bodies at large Reynolds number. J. Fluid Mech. 1, 388–398.Google Scholar
Bernal, L. P. 2016 Unsteady aerodynamics of pitching low-aspect-ratio wings: a review of AVT 202 panel results (invited paper). In Proceedings of the 54th AIAA Aerospace Sciences Meeting (San Diego, CA, USA), pp. 1–17.Google Scholar
Birch, J. M. & Dickinson, M. H. 2001 Spanwise flow and the attachment of the leading-edge vortex on insect wings. Nature 412 (6848), 729–733.Google Scholar
Carr, Z. R., DeVoria, A. C. & Ringuette, M. J. 2015 Aspect-ratio effects on rotating wings: circulation and forces. J. Fluid Mech. 767, 497–525.CrossRefGoogle Scholar
Clark, R. W., Smith, J. H. B. & Thompson, C. W.1975 Some series expansion solutions for slender wings with leading-edge separation. Report ARC R&M 3785. Ministry of Defence, London, UK.Google Scholar
DeVoria, A. C. & Mohseni, K. 2015 Vortex structure of low-aspect-ratio wings in sideslip. In Proceedings of the AIAA Aerospace Sciences Meeting (Kissimmee, FL, USA).Google Scholar
DeVoria, A. C. & Ringuette, M. J. 2012 Vortex formation and saturation for low-aspect-ratio rotating flat-plate fins. Exp. Fluids 52 (2), 441–462.Google Scholar
Dickinson, M. H. & Gotz, K. G. 1993 Unsteady aerodynamic performance of model wings at low Reynolds numbers. J. Expl Biol. 174, 45–64.CrossRefGoogle Scholar
Eldredge, J. D., Wang, C. & Ol, M. 2009 A computational study of a cononical pitch-up, pitch-down wing maneuver. In Proceedings of the 39th AIAA Fluid Dynamics Conference (San Antonia, TX, USA), pp. 1–14.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 (6610), 626–630.CrossRefGoogle Scholar
Garmann, D. J. & Visbal, M. R. 2014 Dynamics of revolving wings for various aspect ratios. J. Fluid Mech. 748, 932–956.Google Scholar
Goldstein, S. 1938 Modern Developments in Fluid Dynamics, Volumes 1 & 2, 1st edn. Oxford University Press.Google Scholar
Hunt, J. C. R., Abell, C. J., Peterka, J. A. & Woo, H. 1978 Kinematical studies of the flows around free or surface-mounted obstacles; applying topology to flow visualization. J. Fluid Mech. 86, 179–200.Google Scholar
Jardin, T., Farcy, A. & David, L. 2012 Three-dimensional effects in hovering flapping flight. J. Fluid Mech. 702, 102–125.CrossRefGoogle Scholar
Jian, T. & Ke-Qin, Z. 2004 Numerical and experimental study of flow structure of low-aspect-ratio wings. J. Aircraft 41, 1196–1201.CrossRefGoogle Scholar
Kaplan, S. M., Altman, A. & Ol, M. 2007 Wake vorticity measurements for low-aspect-ratio wings at low Reynolds number. J. Aircraft 44, 241–251.Google Scholar
Katz, J. 1981 A discrete vortex method for the non-steady separated flow over an airfoil. J. Fluid Mech. 102, 315–328.Google Scholar
Kim, D. & Gharib, M. 2010 Experimental study of three-dimensional vortex structures in translating and rotating plates. Exp. Fluids 49, 329–339.Google Scholar
Koochesfahani, M. 1989 Vortical patterns in the wake of an oscillating airfoil. AIAA J. 27 (9), 1200–1205.Google Scholar
Lighthill, M. J. 1973 On the Weis–Fogh mechanism of lift generation. J. Fluid Mech. 60 (1), 1–17.Google Scholar
Lipinski, D., Cardwell, B. & Mohseni, K. 2008 A Lagrangian analysis of a two-dimensional airfoil with vortex shedding. J. Phys. A 41 (34), 344011.Google Scholar
Mancini, P., Manar, F., Granlund, K., Ol, M. & Jones, A. R. 2015 Unsteady aerodynamic characteristics of a translating rigid wing at low Reynolds number. Phys. Fluids 27, 123102.Google Scholar
Maxworthy, T. 1979 Experiments on the Weis–Fogh mechanism of lift generation by insects in hovering flight. J. Fluid Mech. 93 (1), 47–53.CrossRefGoogle Scholar
McCroskey, W. J. 1982 Unsteady airfoils. Annu. Rev. Fluid Mech. 14, 285–311.Google Scholar
Mejia, O. D. L., Moser, R. D., Brzozowski, D. P. & Glezer, A. 2011 Effects of trailing-edge synthetic jet actuation of an airfoil. AIAA J. 49 (8), 1763–1777.CrossRefGoogle Scholar
Ol, M. & Babinsky, H. 2016 Unsteady flat plates: a cursory review of AVT-202 research (invited). In Proceedings of the 54th AIAA Aerospace Sciences Meeting (San Diego, CA, USA), pp. 1–17.Google Scholar
Ol, M. V., Bernal, L., Kang, C.-K. & Shyy, W. 2009 Shallow and deep dynamic stall for flapping low Reynolds number airfoils. Exp. Fluids 46, 883–901.Google Scholar
Ozen, C. & Rockwell, D. 2012 Three-dimensional vortex structure on a rotating wing. J. Fluid Mech. 707, 541–550.Google Scholar
Pitt Ford, C. W. & Babinsky, H. 2013 Lift and the leading-edge vortex. J. Fluid Mech. 720, 280–313.CrossRefGoogle Scholar
Polhamus, E. C.1966 A concept of the vortex lift of sharp-edge delta wings based on a leading-edge suction analogy. Tech. Rep. TN D-3767. NASA, Langley Research Center, Hampton, Virginia.Google Scholar
Rae, W. H. & Pope, A. 1984 Low-Speed Wind Tunnel Testing, 2nd edn. Wiley.Google Scholar
Raffel, M., Willert, C. E. & Kompenhans, J. 1998 Particle Image Velocimetry. Springer.Google Scholar
Rival, D. E., Kriegseis, J., Schuab, P., Widmann, A. & Tropea, C. 2014 Characteristic length scales for vortex detachment on plunging profiles with varying leading-edge geometry. Exp. Fluids 55 (1), 1660.Google Scholar
Saffman, P. G. & Sheffield, J. S. 1977 Flow over a wing with an attached free vortex. Stud. Appl. Maths 57, 107–117.CrossRefGoogle Scholar
Saffman, P. G. & Tanveer, S. 1984a Prandtl-batchelor flow past a flat plate with a forward-facing flap. J. Fluid Mech. 143, 351–365.Google Scholar
Saffman, P. G. & Tanveer, S. 1984b Vortex induced lift on two dimensional low speed wings. Stud. Appl. Maths 71, 65–78.Google Scholar
Shields, M. & Mohseni, K. 2013 Roll stall for low-aspect-ratio wings. J. Aircraft 50 (4), 1060–1069.Google Scholar
Shyy, W., Trizila, P., Kang, C.-K. & Aono, H. 2009 Can tip vortices enhance lift of a flapping wing? AIAA J. 47 (2), 289–293.Google Scholar
Taira, K. & Colonius, T. 2009a Effect of tip vortices in low-Reynolds-number poststall flow control. AIAA J. 47 (3), 187–207.Google Scholar
Taira, K. & Colonius, T. 2009b Three-dimensional flows around low-aspect-ratio flat-plate wings at low Reynolds numbers. J. Fluid Mech. 623, 187–207.CrossRefGoogle Scholar
Visbal, M., Yilmaz, T. O. & Rockwell, D. 2013 Three-dimensional vortex formation on a heaving low-aspect-ratio wing: computations and experiments. J. Fluids Struct. 38, 58–76.Google Scholar
Weis-Fogh, T. 1973 Quick estimates of flight fitness in hovering animals, including novel mechanisms for lift production. J. Expl Biol. 59, 169–230.Google Scholar
Winter, H.1936 Flow phenomena on plates and airfoils of short span. Tech. Mem. 798. National Advisory Committee for Aeronautics.Google Scholar
Wojcik, C. J. & Buccholz, J. H. J. 2014 Vorticity transport in the leading-edge vortex on a rotating blade. J. Fluid Mech. 743, 249–261.Google Scholar
Xia, X. & Mohseni, K. 2013 Lift evaluation of a two-dimensional pitching flat plate. Phys. Fluids 25 (9), 091901.Google Scholar
Xia, X. & Mohseni, K. 2016 Unsteady aerodynamics and trailing-edge vortex sheet of an airfoil. In Proceedings of the AIAA Aerospace Sciences Meeting (San Diego, CA, USA).Google Scholar
Yilmaz, T. O. & Rockwell, D. 2012 Flow structure on finite-span wings due to pitch-up motion. J. Fluid Mech. 691, 518–545.CrossRefGoogle Scholar