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Dual leading-edge vortices on flapping wings.
J Exp Biol. 2006 Dec; 209(Pt 24):5005-16.JE

Abstract

An experimental investigation was performed with two aims: (1) to clarify the existence of the dual leading-edge vortices (i.e. two vortices with the same sense of rotation located close to the leading edge above the leeward wing surface) observed on flapping wings in previous studies; (2) to study systematically the influences of kinematic and geometric parameters on such a vortical structure. Based on a scaled-up electromechanical model flapping in a water tank, the leading-edge vortex (LEV) cores were visualized via dye flow visualization, and the detailed sub-structures of LEV were revealed through digital particle image velocimetry (DPIV) with high spatial resolution. Five wing aspect ratios (AR) (1.3, 3.5, 5.8, 7.5 and 10), eight mid-stroke angles of attack (alpha(m)) (10-80 degrees), and six Reynolds numbers (Re) (160-3200) were examined. In addition, the well-studied case of the fruit fly Drosophila was re-examined. The results confirm for the first time the existence of dual LEVs on flapping wings. The sectional flow structure resembles the dual-vortex observed on non-slender delta wings. Insensitive to AR, a dual LEV system such as this could be created when alpha(m) and Re reached certain high levels. The primary vortex was attached to the wing, while at the outer wing the minor vortex shed, generating a same-sense vortex behind.

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 availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

17142689

Citation

Lu, Yuan, et al. "Dual Leading-edge Vortices On Flapping Wings." The Journal of Experimental Biology, vol. 209, no. Pt 24, 2006, pp. 5005-16.
Lu Y, Shen GX, Lai GJ. Dual leading-edge vortices on flapping wings. J Exp Biol. 2006;209(Pt 24):5005-16.
Lu, Y., Shen, G. X., & Lai, G. J. (2006). Dual leading-edge vortices on flapping wings. The Journal of Experimental Biology, 209(Pt 24), 5005-16.
Lu Y, Shen GX, Lai GJ. Dual Leading-edge Vortices On Flapping Wings. J Exp Biol. 2006;209(Pt 24):5005-16. PubMed PMID: 17142689.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Dual leading-edge vortices on flapping wings. AU - Lu,Yuan, AU - Shen,Gong Xin, AU - Lai,Guo Jun, PY - 2006/12/5/pubmed PY - 2007/3/1/medline PY - 2006/12/5/entrez SP - 5005 EP - 16 JF - The Journal of experimental biology JO - J. Exp. Biol. VL - 209 IS - Pt 24 N2 - An experimental investigation was performed with two aims: (1) to clarify the existence of the dual leading-edge vortices (i.e. two vortices with the same sense of rotation located close to the leading edge above the leeward wing surface) observed on flapping wings in previous studies; (2) to study systematically the influences of kinematic and geometric parameters on such a vortical structure. Based on a scaled-up electromechanical model flapping in a water tank, the leading-edge vortex (LEV) cores were visualized via dye flow visualization, and the detailed sub-structures of LEV were revealed through digital particle image velocimetry (DPIV) with high spatial resolution. Five wing aspect ratios (AR) (1.3, 3.5, 5.8, 7.5 and 10), eight mid-stroke angles of attack (alpha(m)) (10-80 degrees), and six Reynolds numbers (Re) (160-3200) were examined. In addition, the well-studied case of the fruit fly Drosophila was re-examined. The results confirm for the first time the existence of dual LEVs on flapping wings. The sectional flow structure resembles the dual-vortex observed on non-slender delta wings. Insensitive to AR, a dual LEV system such as this could be created when alpha(m) and Re reached certain high levels. The primary vortex was attached to the wing, while at the outer wing the minor vortex shed, generating a same-sense vortex behind. SN - 0022-0949 UR - https://www.unboundmedicine.com/medline/citation/17142689/Dual_leading_edge_vortices_on_flapping_wings_ L2 - http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=17142689 DB - PRIME DP - Unbound Medicine ER -