Experiments in Fluids

, 54:1575

Flow structures around a flapping wing considering ground effect

Authors

  • Tien Van Truong
    • Department of Aerospace Information EngineeringKonkuk University
  • Jihoon Kim
    • Department of Mechanical EngineeringSungkyunkwan University
  • Min Jun Kim
    • Department of Mechanical EngineeringDrexel University
  • Hoon Cheol Park
    • Department of Advanced Technology FusionKonkuk University
  • Kwang Joon Yoon
    • Department of Aerospace Information EngineeringKonkuk University
    • Department of Mechanical EngineeringSungkyunkwan University
Research Article

DOI: 10.1007/s00348-013-1575-6

Cite this article as:
Van Truong, T., Kim, J., Kim, M.J. et al. Exp Fluids (2013) 54: 1575. doi:10.1007/s00348-013-1575-6

Abstract

Over the past several decades, there has been great interest in understanding the aerodynamics of flapping flight, namely the two flight modes of hovering and forward flight. However, there has been little focus on the aerodynamic characteristics during takeoff of insects. In a previous study we found that the Rhinoceros Beetle (Trypoxylusdichotomus) takes off without jumping, which is uncommon for other insects. In this study we built a scaled-up electromechanical model of a flapping wing and investigated fluid flow around the beetle’s wing model. In particular, the present dynamically scaled mechanical model has the wing kinematics pattern achieved from the real beetle’s wing kinematics during takeoff. In addition, we could systematically change the three-dimensional inclined motion of the flapping model through each stroke. We used digital particle image velocimetry with high spatial resolution, and were able to qualitatively and quantitatively study the flow field around the wing at a Reynolds number of approximately 10,000. The present results provide insight into the aerodynamics and the evolution of vortical structures, as well as the ground effect experienced by a beetle’s wing during takeoff. The main unsteady mechanisms of beetles have been identified and intensively analyzed as the stability of the leading edge vortex (LEV) during strokes, the delayed stall during upstroke, the rotational circulation in pronation periods, and wake capture in supination periods. Due to the ground effect, the LEV was enhanced during half downstroke, and the lift force could thus be increased to lift the beetle during takeoff. This is useful for researchers in developing a micro air vehicle that has a beetle-like flapping wing motion.

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© Springer-Verlag Berlin Heidelberg 2013