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Formation of vortices and spanwise flow on an insect-like flapping wing throughout a flapping half cycle

  • N. Phillips (a1) and K. Knowles (a1)


This paper presents an experimental investigation of the evolution of the leading-edge vortex and spanwise flow generated by an insect-like flapping-wing at a Reynolds number relevant to flapping-wing micro air vehicles (FMAVs) (Re = ~15,000). Experiments were accomplished with a first-of-its-kind flapping-wing apparatus. Dense pseudo-volumetric particle image velocimetry (PIV) measurements from 18% – 117% span were taken at 12 azimuthal positions throughout a flapping half cycle. Results revealed the formation of a primary leading-edge vortex (LEV) which saw an increase in size and spanwise flow (towards the tip) through its core as the wing swept from rest to the mid-stroke position where signs of vortex breakdown were observed. Beyond mid-stroke, spanwise flow decreased and the tip vortex grew in size and exhibited a reversal in its axial direction. At the end of the flapping half cycle, the primary LEV was still present over the wing surface, suggesting that the LEV remains attached to the wing throughout the entire flapping half cycle.


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1. Ansari, S.A. A nonlinear, unsteady, aerodynamic model for insect-like flapping wings in the hover with micro air vehicle applications. PhD thesis, Cranfield University, Shrivenham, UK, 2004.
2. van den Berg, C. and Ellington, C.P. The three-dimensional leading-edge vortex of a hovering model hawkmoth, Philosophical Transactions of the Royal Society of London Series B, 1997, 352, (1351), pp 329340.
3. van den Berg, C. and Ellington, C.P. The vortex wake of a hovering model hawkmoth, Philosophical Transactions of the Royal Society of London Series B, 1997, 352, (1351), pp 317328.
4. Birch, J.M. and Dickinson, M.H. Spanwise flow and the attachment of the leading-edge vortex on insect wings, Nature, 2001, 412, (6848), pp 729733.
5. Bomphrey, R.J. Insects in flight: direct visualization and flow measurements, Bioinspiration & Biomimetics, 2006, 1, (1-9).
6. Bomphrey, R.J., Lawson, N.J., Harding, N.J, Taylor, G.K. and Thomas, A.L.R. The aerodynamics of Manduca sexta: digital particle image velocimetry analysis of the leading-edge vortex, J Experimental Biology, 2005, 208, pp 10791094.
7. Bomphrey, R.J., Lawson, N.J., Harding, N.J., Taylor, G.K. and Thomas, A.L.R. Application of digital particle image velocimetry to insect aerodynamics: measurement of the leading-edge vortex and near wake of a hawkmoth, Experiments in Fluids, 2006, 40, (4), pp 546554.
8. Dickinson, M.H., Lehmann, F.-O. and Sane, S.P. Wing rotation and the aerodynamic basis of insect flight, Science, 1999, 284, (5422), pp 19541960.
9. Ellington, C.P., van den Berg, C., Willmott, A.P. and Thomas, A.L.R. Leading-edge vortices in insect flight, Nature, 1996, 384, pp 626630.
10. Galin’ski, C. and Żbikowski, R. Materials challenges in the design of an insect-like flapping wing mechanism based on a four-bar linkage, Materials & Design, 2007, 28, (3), pp 783796.
11. Hunt, J.C.R., Wray, A.A. and Moin, P. Eddies, stream, and convergence zones in turbulent flows. Technical report, Center for Turbulence Research, 1988. Report CTR-S88.
12. Jones, A. and Babinsky, H. Reynolds number effects on leading edge vortex development on a waving wing, Experiments in Fluids, 2011, 51, (1), pp 197210.
13. Jones, A. and Babinsky, H. Unsteady lift generation on rotating wings at low Reynolds numbers, J Aircr, 2010, 47, (3), pp 10131021.
14. Knowles, R.D., Finnis, M.V., Saddington, A.J. and Knowles, K. Planar visualization of vortical flows. Proceedings of the Institution of Mechanical Engineering, Part G: J Aerospace Engineering, 2006, 220, (6), pp 619627.
15. N.J., Lawson and J., Wu Three-dimensional particle image velocimetry: error analysis of stereoscopic techniques, Measurement Science and Technology, 1997, 8, pp 894900.
16. Leibovich, S. Vortex stability and breakdown: survey and extension, AIAA J, 1984, 22, (9), pp 11921206.
17. Lentink, D. and Dickinson, M.H. Rotational accelerations stabilize leading edge vortices on revolving fly wings, J Experimental Biology, 2009, 212, pp 27052719.
18. Liu, H., Ellington, C.P., Kawachi, K., van den Berg, C. and Wilmott, A.P. A computational fluid dynamic study of hawkmoth hovering, J Experimental Biology, 1998, 201, pp 461477.
19. Lu, Y. and Shen, G.X. Three-dimensional flow structures and evolution of the leading-edge vortices on a flapping wing, J Experimental Biology, 2008, 211, (8), pp 12211230.
20. Lu, Y., Shen, G.X. and Lai, G.J. Dual leading-edge vortices on flapping wings, J Experimental Biology, 2006, 209, pp 50055016.
21. Maxworthy, T. Experiments on the Weis-Fogh mechanism of lift generation by insects in hovering flight. part 1: dynamics of the ‘fing’, J Fluid Mechanics, 1979, 93, pp 4763.
22. Pedersen, C.B. An Indicial-Polhamus Model of Aerodynamics of Insect-Like Flapping Wings in Hover, PhD thesis, Cranfield University, Shrivenham, UK, 2003.
23. Phillips, N. and Knowles, K. Progress in the development of an adjustable, insect-like flapping-wing apparatus utilising a three degree-of-freedom parallel spherical mechanism. International Powered Lift Conference, London, UK, 2008. Royal Aeronautical Society.
24. Phillips, N. Experimental Unsteady Aerodynamics Relevant to Insect-Inspired Flapping-Wing Micro Air Vehicles, PhD thesis, Cranfield University (Shrivenham), 2011.
25. Poelma, C. and Dickson, W.B. and Dickinson, M.H. Time-resolved reconstruction of the full velocity field around a dynamically-scaled flapping wing, Experiments in Fluids, 2006, 41, pp 213225.
26. Prasad, A.K. Stereoscopic particle image velocimetry, Experiments in Fluids, 2000, 29, pp 103116.
27. Raffel, M. and Willert, C. and Kompenhans, J. Particle image velocimetry: a practical guide. Springer-Verlag, Berlin, Germany, 1998.
28. Scarano, F., David, L., Bsibsi, M. and Calluaud, D. S-PIV comparative assessment: image dewarping+misalignment correction and pinhole+geometric back projection, Experiments in Fluids, 2005, 39, pp 257266.
29. Srygley, R.B. and Thomas, A.L.R. Unconventional lift-generating mechanisms in free-flying butterflies, Nature, 2002, 420, pp 660664.
30. Tarascio, M.J., Ramasamy, M., Chopra, I. and Leishman, J.G. Flow visualization of micro air vehicle scaled insect-based flapping wings, J Aircr, 2005, 42, (2), pp 385390.
31. Thomas, A.l.R., Taylor, G.K., Srygley, R.B., Nudds, R.L. and Bomphrey, R.J. Dragonfly flight: free-flight and tethered flow visualizations reveal a diverse array of unsteady lift-generating mechanisms, controlled primarily via angle-of-attack, J Experimental Biology, 2004, 207, pp 42994323.
32. Usherwood, J.R. and Ellington, C.P. The aerodynamics of revolving wings I. model hawkmoth wings, J Experimental Biology, 2002, 205, pp 15471564.
33. Westerweel, J. Efficient detection of spurious vectors in particle image velocimetry data, Experiments in Fluids, 1994, 16, pp 236247.
34. Wilkins, P.C. and Knowles, K. The leading-edge vortex and aerodynamics of insect-based flapping-wing micro air vehicles, Aeronaut J, 2009, 113, (1143), pp 253262.
35. Wilkins, P.C. Some unsteady aerodynamics relevant to insect-inspired flapping-wing micro air vehicles. PhD thesis, Cranfield University (Shrivenham), 2008.
35. Willert, C.E. Stereoscopic digital particle image velocimetry for application in wind tunnel flows, Measurement Science and Technology, 1997, 8, pp 14651479.
36. Willert, C.E. and Gharib, M. Digital particle image velocimetry, Experiments in Fluids, 1991, 10, pp 181193.
37. Willmott, A.P. and Ellington, C.P. The mechanics of flight in the hawkmoth Manduca sexta: I. kinematics of hovering and forward flight, J Experimental Biology, 1997, 200, pp 27052722.
38. Woods, M.I., Henderson, J.F. and Lock, G.D. Energy requirements for the fight of micro air vehicles, Aeronaut J, 2001, 105, (1043), pp 135149.
39. Żbikowski, R. Flapping wing autonomous micro air vehicles: research programme outline, Fourteenth International Conference on Unmanned Air Vehicle Systems, 1999, pp 38.138.5.

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Formation of vortices and spanwise flow on an insect-like flapping wing throughout a flapping half cycle

  • N. Phillips (a1) and K. Knowles (a1)


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