Tags

Type your tag names separated by a space and hit enter

Three-dimensional flow structures and evolution of the leading-edge vortices on a flapping wing.
J Exp Biol. 2008 Apr; 211(Pt 8):1221-30.JE

Abstract

Following the identification and confirmation of the substructures of the leading-edge vortex (LEV) system on flapping wings, it is apparent that the actual LEV structures could be more complex than had been estimated in previous investigations. In this experimental study, we reveal for the first time the detailed three-dimensional (3-D) flow structures and evolution of the LEVs on a flapping wing in the hovering condition at high Reynolds number (Re=1624). This was accomplished by utilizing an electromechanical model dragonfly wing flapping in a water tank (mid-stroke angle of attack=60 degrees) and applying phase-lock based multi-slice digital stereoscopic particle image velocimetry (DSPIV) to measure the target flow fields at three typical stroke phases: at 0.125 T (T=stroke period), when the wing was accelerating; at 0.25 T, when the wing had maximum speed; and at 0.375 T, when the wing was decelerating. The result shows that the LEV system is a collection of four vortical elements: one primary vortex and three minor vortices, instead of a single conical or tube-like vortex as reported or hypothesized in previous studies. These vortical elements are highly time-dependent in structure and show distinct ;stay properties' at different spanwise sections. The spanwise flows are also time-dependent, not only in the velocity magnitude but also in direction.

Authors+Show Affiliations

Full Flow Field Observation and Measurement, Institute of Fluid Mechanics, Beijing University of Aeronautics and Astronautics, Beijing 100083, People's Republic of China.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18375846

Citation

Lu, Yuan, and Gong Xin Shen. "Three-dimensional Flow Structures and Evolution of the Leading-edge Vortices On a Flapping Wing." The Journal of Experimental Biology, vol. 211, no. Pt 8, 2008, pp. 1221-30.
Lu Y, Shen GX. Three-dimensional flow structures and evolution of the leading-edge vortices on a flapping wing. J Exp Biol. 2008;211(Pt 8):1221-30.
Lu, Y., & Shen, G. X. (2008). Three-dimensional flow structures and evolution of the leading-edge vortices on a flapping wing. The Journal of Experimental Biology, 211(Pt 8), 1221-30. https://doi.org/10.1242/jeb.010652
Lu Y, Shen GX. Three-dimensional Flow Structures and Evolution of the Leading-edge Vortices On a Flapping Wing. J Exp Biol. 2008;211(Pt 8):1221-30. PubMed PMID: 18375846.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Three-dimensional flow structures and evolution of the leading-edge vortices on a flapping wing. AU - Lu,Yuan, AU - Shen,Gong Xin, PY - 2008/4/1/pubmed PY - 2008/6/21/medline PY - 2008/4/1/entrez SP - 1221 EP - 30 JF - The Journal of experimental biology JO - J. Exp. Biol. VL - 211 IS - Pt 8 N2 - Following the identification and confirmation of the substructures of the leading-edge vortex (LEV) system on flapping wings, it is apparent that the actual LEV structures could be more complex than had been estimated in previous investigations. In this experimental study, we reveal for the first time the detailed three-dimensional (3-D) flow structures and evolution of the LEVs on a flapping wing in the hovering condition at high Reynolds number (Re=1624). This was accomplished by utilizing an electromechanical model dragonfly wing flapping in a water tank (mid-stroke angle of attack=60 degrees) and applying phase-lock based multi-slice digital stereoscopic particle image velocimetry (DSPIV) to measure the target flow fields at three typical stroke phases: at 0.125 T (T=stroke period), when the wing was accelerating; at 0.25 T, when the wing had maximum speed; and at 0.375 T, when the wing was decelerating. The result shows that the LEV system is a collection of four vortical elements: one primary vortex and three minor vortices, instead of a single conical or tube-like vortex as reported or hypothesized in previous studies. These vortical elements are highly time-dependent in structure and show distinct ;stay properties' at different spanwise sections. The spanwise flows are also time-dependent, not only in the velocity magnitude but also in direction. SN - 0022-0949 UR - https://www.unboundmedicine.com/medline/citation/18375846/Three_dimensional_flow_structures_and_evolution_of_the_leading_edge_vortices_on_a_flapping_wing_ L2 - http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=18375846 DB - PRIME DP - Unbound Medicine ER -