Skip to main content Accessibility help
×
Home

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

  • Adam C. DeVoria (a1) and Kamran Mohseni (a1) (a2)

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.

Copyright

Corresponding author

Email address for correspondence: mohseni@ufl.edu

References

Hide All
AIAA Standards2003 Calibration and use of internal strain-gage balances with application to wind tunnel testing. Report AIAA Recommended Practice R-091-2003.
Batchelor, G. K. 1956 A proposal concerning laminar wakes behind bluff bodies at large Reynolds number. J. Fluid Mech. 1, 388398.
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. 117.
Birch, J. M. & Dickinson, M. H. 2001 Spanwise flow and the attachment of the leading-edge vortex on insect wings. Nature 412 (6848), 729733.
Carr, Z. R., DeVoria, A. C. & Ringuette, M. J. 2015 Aspect-ratio effects on rotating wings: circulation and forces. J. Fluid Mech. 767, 497525.
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.
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).
DeVoria, A. C. & Ringuette, M. J. 2012 Vortex formation and saturation for low-aspect-ratio rotating flat-plate fins. Exp. Fluids 52 (2), 441462.
Dickinson, M. H. & Gotz, K. G. 1993 Unsteady aerodynamic performance of model wings at low Reynolds numbers. J. Expl Biol. 174, 4564.
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. 114.
Ellington, C. P., van den Berg, C., Willmott, A. P. & Thomas, A. L. R. 1996 Leading-edge vortices in insect flight. Nature 384 (6610), 626630.
Garmann, D. J. & Visbal, M. R. 2014 Dynamics of revolving wings for various aspect ratios. J. Fluid Mech. 748, 932956.
Goldstein, S. 1938 Modern Developments in Fluid Dynamics, Volumes 1 & 2, 1st edn. Oxford University Press.
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, 179200.
Jardin, T., Farcy, A. & David, L. 2012 Three-dimensional effects in hovering flapping flight. J. Fluid Mech. 702, 102125.
Jian, T. & Ke-Qin, Z. 2004 Numerical and experimental study of flow structure of low-aspect-ratio wings. J. Aircraft 41, 11961201.
Kaplan, S. M., Altman, A. & Ol, M. 2007 Wake vorticity measurements for low-aspect-ratio wings at low Reynolds number. J. Aircraft 44, 241251.
Katz, J. 1981 A discrete vortex method for the non-steady separated flow over an airfoil. J. Fluid Mech. 102, 315328.
Kim, D. & Gharib, M. 2010 Experimental study of three-dimensional vortex structures in translating and rotating plates. Exp. Fluids 49, 329339.
Koochesfahani, M. 1989 Vortical patterns in the wake of an oscillating airfoil. AIAA J. 27 (9), 12001205.
Lighthill, M. J. 1973 On the Weis–Fogh mechanism of lift generation. J. Fluid Mech. 60 (1), 117.
Lipinski, D., Cardwell, B. & Mohseni, K. 2008 A Lagrangian analysis of a two-dimensional airfoil with vortex shedding. J. Phys. A 41 (34), 344011.
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.
Maxworthy, T. 1979 Experiments on the Weis–Fogh mechanism of lift generation by insects in hovering flight. J. Fluid Mech. 93 (1), 4753.
McCroskey, W. J. 1982 Unsteady airfoils. Annu. Rev. Fluid Mech. 14, 285311.
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), 17631777.
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. 117.
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, 883901.
Ozen, C. & Rockwell, D. 2012 Three-dimensional vortex structure on a rotating wing. J. Fluid Mech. 707, 541550.
Pitt Ford, C. W. & Babinsky, H. 2013 Lift and the leading-edge vortex. J. Fluid Mech. 720, 280313.
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.
Rae, W. H. & Pope, A. 1984 Low-Speed Wind Tunnel Testing, 2nd edn. Wiley.
Raffel, M., Willert, C. E. & Kompenhans, J. 1998 Particle Image Velocimetry. Springer.
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.
Saffman, P. G. & Sheffield, J. S. 1977 Flow over a wing with an attached free vortex. Stud. Appl. Maths 57, 107117.
Saffman, P. G. & Tanveer, S. 1984a Prandtl-batchelor flow past a flat plate with a forward-facing flap. J. Fluid Mech. 143, 351365.
Saffman, P. G. & Tanveer, S. 1984b Vortex induced lift on two dimensional low speed wings. Stud. Appl. Maths 71, 6578.
Shields, M. & Mohseni, K. 2013 Roll stall for low-aspect-ratio wings. J. Aircraft 50 (4), 10601069.
Shyy, W., Trizila, P., Kang, C.-K. & Aono, H. 2009 Can tip vortices enhance lift of a flapping wing? AIAA J. 47 (2), 289293.
Taira, K. & Colonius, T. 2009a Effect of tip vortices in low-Reynolds-number poststall flow control. AIAA J. 47 (3), 187207.
Taira, K. & Colonius, T. 2009b Three-dimensional flows around low-aspect-ratio flat-plate wings at low Reynolds numbers. J. Fluid Mech. 623, 187207.
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, 5876.
Weis-Fogh, T. 1973 Quick estimates of flight fitness in hovering animals, including novel mechanisms for lift production. J. Expl Biol. 59, 169230.
Winter, H.1936 Flow phenomena on plates and airfoils of short span. Tech. Mem. 798. National Advisory Committee for Aeronautics.
Wojcik, C. J. & Buccholz, J. H. J. 2014 Vorticity transport in the leading-edge vortex on a rotating blade. J. Fluid Mech. 743, 249261.
Xia, X. & Mohseni, K. 2013 Lift evaluation of a two-dimensional pitching flat plate. Phys. Fluids 25 (9), 091901.
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).
Yilmaz, T. O. & Rockwell, D. 2012 Flow structure on finite-span wings due to pitch-up motion. J. Fluid Mech. 691, 518545.
MathJax
MathJax is a JavaScript display engine for mathematics. For more information see http://www.mathjax.org.

JFM classification

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

  • Adam C. DeVoria (a1) and Kamran Mohseni (a1) (a2)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed