Skip to main content
SpringerLink
Log in

An experimental study of the unsteady vortex structures in the wake of a root-fixed flapping wing

  • Research Article
  • Published:
Experiments in Fluids Aims and scope Submit manuscript

Abstract

An experimental study was conducted to characterize the evolution of the unsteady vortex structures in the wake of a root-fixed flapping wing with the wing size, stroke amplitude, and flapping frequency within the range of insect characteristics for the development of novel insect-sized nano-air-vehicles (NAVs). The experiments were conducted in a low-speed wing tunnel with a miniaturized piezoelectric wing (i.e., chord length, C = 12.7 mm) flapping at a frequency of 60 Hz (i.e., f = 60 Hz). The non-dimensional parameters of the flapping wing are chord Reynolds number of Re = 1,200, reduced frequency of k = 3.5, and non-dimensional flapping amplitude at wingtip h = A/C = 1.35. The corresponding Strouhal number (Str) is 0.33, which is well within the optimal range of 0.2 < Str < 0.4 used by flying insects and birds and swimming fishes for locomotion. A digital particle image velocimetry (PIV) system was used to achieve phased-locked and time-averaged flow field measurements to quantify the transient behavior of the wake vortices in relation to the positions of the flapping wing during the upstroke and down stroke flapping cycles. The characteristics of the wake vortex structures in the chordwise cross planes at different wingspan locations were compared quantitatively to elucidate underlying physics for a better understanding of the unsteady aerodynamics of flapping flight and to explore/optimize design paradigms for the development of novel insect-sized, flapping-wing-based NAVs.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11

Similar content being viewed by others

Abbreviations

A :

Flapping amplitude

b :

Span of the flapping frequency

C :

Chord length of the flapping wing

f :

Flapping frequency

h :

Non-dimensional flapping amplitude, h = A/C

k :

Reduced frequency, k = 2πfC/U ∞

Str:

Strouhal number, Str = fA/U ∞

U ∞ :

Forward flying speed or incoming flow velocity

U, V :

Mean flow velocity

u, v :

Instantaneous flow velocity

x, y, z :

Cartesian coordinate system

ω z :

Spanwise vorticity

References

  • Anderson JM, Streitlien K, Barrett DS, Triantafyllou MS (1998) Oscillating foils of high propulsive efficiency. J Fluid Mech 360:41–72

    Article  MathSciNet  MATH  Google Scholar 

  • Bohl DG, Koochesfahani MM (2009) MTV measurements of the vortical field in the wake of an airfoil oscillating at high reduced frequency. J Fluid Mech 620:63–88

    Article  MATH  Google Scholar 

  • Bohorquez F, Samuel P, Sirohi J, Pines D, Rudd L, Perel R (2003) Design analysis and hover performance of a rotating wing Micro Air Vehicle. J Am Helicopter Soc 48(2):80–90

    Article  Google Scholar 

  • Chung HC, Kummari KL, Croucher SJ, Lawson NJ, Guo S, Whatmore RW, Huang Z (2009) Development of piezoelectric fans for flapping wing application. Sens Actuator A 149:136–142

    Article  Google Scholar 

  • Clemons L (2009) An experimental study of the vortex structures in the wake of a piezoelectric flapping plate for Nano Air Vehicle applications. MS thesis. Department of Aerospace Engineering of Iowa State University

  • Cox A, Monopoli D, Cveticanin D, Goldfarb M, Garcia E (2002) The development of elastodynamic components for piezoelectrically actuated flapping micro air vehicles. J Intell Mater Syst Struct 13:611–615

    Article  Google Scholar 

  • Dickinson MH, Lehmann FO, Sane SP (1999) Wing rotation and the aerodynamic basis of insect flight. Science 284:1954–1960

    Article  Google Scholar 

  • Freymuth P (1988) Propulsive vortical signatures of plunging and pitching airfoils. AIAA J 26(7):881–883

    Article  Google Scholar 

  • Garrick IE (1936) Propulsion of a flapping and oscillating airfoil. NACA Report. 567, May 1936

  • Hu H, Gopa-Kumar A, Abate G, Albertani R (2010) An Experimental study of flexible membrane wings in flapping flight. Aerosp Sci Technol 14(8):575–586

    Article  Google Scholar 

  • Jones KD, Dohring CM, Platzer MF (1996) Wake structures behind plunging airfoils: a comparison of numerical and experimental results. 34th Aerospace sciences meeting and exhibit, Reno, NV, AIAA Paper 96-0078, 1996

  • Koochesfahani MM (1989) Vortical patterns in the wake of an oscillating airfoil. AIAA J 27(9):1200–1205

    Article  Google Scholar 

  • Lai JCS, Platzer MF (1999) Jet characteristics of a plunging airfoil. AIAA J 37(12):1529–1537

    Article  Google Scholar 

  • Lewin GC, Haj-Hariri H (2003) Modelling thrust generation of a two-dimensional heaving airfoil in viscous flow. J Fluid Mech 492:339–362

    Article  MATH  Google Scholar 

  • Maxworthy T (1981) The fluid dynamics of insect flight. Ann Rev Fluid Mech 13:329–350

    Article  Google Scholar 

  • Mueller TJ (2001) Fixed and flapping wing aerodynamics for Micro Air Vehicle applications (Progress in Astronautics and Aeronautics), ISBN 1-56347-517-0

  • Niezrecki C, Brei D, Balakrishnan S, Moskalik A (2001) Piezoelectric actuation: state of the art. Shock Vib Dig 33:269–280

    Article  Google Scholar 

  • Park HC, Kim KJ, Lee S, Lee SY, Cha YJ, Yoon KJ, Goo NS (2004) Biomimetic flapping devices powered by artificial muscle actuators. Proceedings of UKC2004 US–Korea Conference on Science, Technology and Entrepreneurship, August, 2004

  • Ramasamy M, Leishman JG, Lee TE (2006) Flow field of a rotating wing MAV. 62nd Annual National Forum Proceedings of the American Helicopter Society

  • Read DA, Hover FS, Triantafyllou MS (2003) Forces on oscillating foils for propulsion and maneuvering. J Fluid Struct 17:163–183

    Article  Google Scholar 

  • Sunada S, Ellington CP (2001) A new method for explaining the generation of aerodynamic forces in flapping flight. Math Methods Appl Sci 24:1377–1386

    Article  MATH  Google Scholar 

  • Taylor GK, Nudds RL, Thomas ALR (2003) Flying and swimming animals cruise at a Strouhal number tuned for high power efficiency. Nature (London) 425:707–711. doi:10.1038/nature02000

    Article  Google Scholar 

  • Toda M (1981) Voltage-induced large amplitude bending device—PVF2 bimorph—its properties and applications. Ferroelectrics 32:911

    Article  Google Scholar 

  • Triantafyllou MS, Triantafyllou GS, Gopalkrishnan R (1991) Wake mechanics for thrust generation in oscillating foils. Phys Fluids A 3:2835–2837

    Article  Google Scholar 

  • Triantafyllou GS, Triantafyllou MS, Grosenbaugh MA (1993) Optimal thrust development in oscillating foils with application to fish propulsion. J Fluids Struct 7:205–224

    Article  Google Scholar 

  • Wang ZJ (2000) Vortex shedding and frequency selection in flapping flight. J Fluid Mech 410:323–341

    Article  MATH  Google Scholar 

  • Wood RJ (2008) The first takeoff of a biologically-inspired at-scale robotic insect. IEEE Trans Robotics 24(2):341–347

    Article  Google Scholar 

  • Wu PR, Kingon A, Mulling J (2003) Piezoelectric resonating structures for microelectronic cooling. Smart Mater Struct 12:181–187

    Article  Google Scholar 

  • Yoo JH, Hong JI, Cao W (2000) Piezoelectric ceramic bimorph coupled to thin metal plate as cooling fan for electronic devices. Sens Actuator A 79:8–12

    Article  Google Scholar 

  • Young J, Lai JCS (2004) Oscillation frequency and amplitude effects on the wake of a plunging airfoil. AIAA J 42(10):2042–2052

    Article  Google Scholar 

  • Youngren H, Kroninger C, Chang M, Jameson S (2008) Low Reynolds number testing of the AG38 airfoil for the SAMARAI nano air vehicle. AIAA 2008-417, 46th AIAA Aerospace Sciences Meeting and Exhibit, 7–10 January 2008, Reno, Nevada

Download references

Acknowledgments

The authors also want to thank Mr. Bill Rickard of Iowa State University for his help in conducting the wind tunnel experiments. The support of National Science Foundation CAREER program under award number of CTS-0545918 is gratefully acknowledged.

Author information

Authors and Affiliations

  1. Department of Aerospace Engineering, Iowa State University, Ames, IA, 50011, USA

    Hui Hu, Lucas Clemons & Hirofumi Igarashi

Authors
  1. Hui Hu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Lucas Clemons
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Hirofumi Igarashi
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Hui Hu.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Hu, H., Clemons, L. & Igarashi, H. An experimental study of the unsteady vortex structures in the wake of a root-fixed flapping wing. Exp Fluids 51, 347–359 (2011). https://doi.org/10.1007/s00348-011-1052-z

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00348-011-1052-z

Keywords

Search

Navigation