Investigation of high lift force generation of dragonfly wing by a novel advanced mode in hover

Xiaohui Su, Kaixuan Zhang, Juan Zheng, Yong Zhao, Ruiqi Han, Jiantao Zhang

Research output: Contribution to journalArticle

Abstract

In the paper, a novel flapping mode is presented that can generate high lift force by a dragonfly wing in hover. The new mode, named partial advanced mode (PAM), starts pitching earlier than symmetric rotation during the downstroke cycle of the hovering motion. As a result, high lift force can be generated due to rapid pitching coupling with high flapping velocity in the stroke plane. Aerodynamic performance of the new mode is investigated thoroughly using numerical simulation. The results obtained show that the period-averaged lift coefficient, CL, increases up to 16% compared with that of the traditional symmetrical mode when an earlier pitching time is set to 8% of the flapping period. The reason for the high lift force generation mechanism is explained in detail using not only force investigation, but also by analyzing vortices produced around the wing. The proposed PAM is believed to lengthen the dynamic stall mechanism and enhance the LEV generated during the downstroke. The improvement of lift force could be considered as a result of a combination of the dynamic stall mechanism and rapid pitch mechanism. Finally, the energy expenditure of the new mode is also analyzed.

Original languageEnglish
Article number59
JournalFluids
Volume5
Issue number2
DOIs
Publication statusPublished - Jun 2020

Keywords

  • Dragonfly wing
  • High lift force generation
  • Hovering motion
  • Partial advanced motion
  • Vortex dynamics

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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