Experiments in Fluids

, 56:131 | Cite as

Aerodynamics of dynamic wing flexion in translating wings

  • Yun Liu
  • Bo Cheng
  • Sanjay P. Sane
  • Xinyan DengEmail author
Research Article


We conducted a systematic experimental study to investigate the aerodynamic effects of active trailing-edge flexion on a high-aspect-ratio wing translating from rest at a high angle of attack. We varied the timing and speed of the trailing-edge flexion and measured the resulting aerodynamic effects using a combination of direct force measurements and two-dimensional PIV flow measurements. The results indicated that the force and flow characteristics depend strongly on the timing of flexion, but relatively weakly on its speed. This is because the force and vortical flow structure are more sensitive to the timing of flexion relative to the shedding of starting vortex and leading-edge vortex. When the trailing-edge flexion occurred slightly before the starting vortex was shed, the lift production was greatly improved with the instantaneous peak lift increased by 54 % and averaged lift increased by 21 % compared with the pre-flexed case where the trailing-edge flexed before wing translation. However, when the trailing-edge flexed during or slightly after the leading-edge vortex shedding, the lift was significantly reduced by the disturbed development of leading-edge vortex. The force measurement results also imply that the trailing-edge flexion prior to wing translation does not augment lift but increases drag, thus resulting in a lower lift–drag ratio as compared to the case of flat wing.


Vortex Flexion Hinge Wing Model Average Lift Maximum Lift Coefficient 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This work was funded by Air Force Office of Scientific Research (AFSOR) Grant number FA9550-11-1-0058. SPS was funded by the Ramanujan fellowship from the Department of Science and Technology, Government of India.

Supplementary material

Supplementary material 1 (MP4 579 kb)

Supplementary material 2 (MP4 2955 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Yun Liu
    • 1
  • Bo Cheng
    • 2
  • Sanjay P. Sane
    • 3
  • Xinyan Deng
    • 1
    Email author
  1. 1.School of Mechanical EngineeringPurdue UniversityWest LafayetteUSA
  2. 2.Department of Mechanical and Nuclear EngineeringPennsylvania State UniversityUniversity ParkUSA
  3. 3.National Center for Biological SciencesTata Institute of Fundamental Research, GKVK CampusBangaloreIndia

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