TY - JOUR
T1 - The three-dimensional leading-edge vortex of a "hovering' model hawkmoth
AU - van den Berg, C.
AU - Ellington, C.P.
PY - 1997
Y1 - 1997
N2 - Recent flow visualization experiments with the hawkmoth, Manduca sexta, revealed a small but clear leading-edge vortex and a pronounced three-dimensional flow. Details of this flow pattern were studied with a scaled-up, robotic insect ('the flapper') that accurately mimicked the wing movements of a hovering hawkmoth. Smoke released from the leading edge of the flapper wing confirmed the existence of a small, strong and stable leading-edge vortex, increasing in size from wingbase to wingtip. Between 25 and 75% of the wing length, its diameter increased approximately from 10 to 50% of the wing chord. The leading-edge vortex had a strong axial flow velocity, which stabilized it and reduced its diameter. The vortex separated from the wing at approximately 75% of the wing length and thus fed vorticity into a large, tangled tip vortex. If the circulation of the leading-edge vortex were fully used for lift generation, it could support up to two-thirds of the hawkmoth's weight during the downstroke. The growth of this circulation with time and spanwise position clearly identify dynamic stall as the unsteady aerodynamic mechanism responsible for high lift production by hovering hawkmoths and possibly also by many other insect species.
AB - Recent flow visualization experiments with the hawkmoth, Manduca sexta, revealed a small but clear leading-edge vortex and a pronounced three-dimensional flow. Details of this flow pattern were studied with a scaled-up, robotic insect ('the flapper') that accurately mimicked the wing movements of a hovering hawkmoth. Smoke released from the leading edge of the flapper wing confirmed the existence of a small, strong and stable leading-edge vortex, increasing in size from wingbase to wingtip. Between 25 and 75% of the wing length, its diameter increased approximately from 10 to 50% of the wing chord. The leading-edge vortex had a strong axial flow velocity, which stabilized it and reduced its diameter. The vortex separated from the wing at approximately 75% of the wing length and thus fed vorticity into a large, tangled tip vortex. If the circulation of the leading-edge vortex were fully used for lift generation, it could support up to two-thirds of the hawkmoth's weight during the downstroke. The growth of this circulation with time and spanwise position clearly identify dynamic stall as the unsteady aerodynamic mechanism responsible for high lift production by hovering hawkmoths and possibly also by many other insect species.
U2 - 10.1098/rstb.1997.0024
DO - 10.1098/rstb.1997.0024
M3 - Article
SN - 0962-8436
VL - 352
SP - 329
EP - 340
JO - Philosophical Transactions of the Royal Society B. Biological Sciences
JF - Philosophical Transactions of the Royal Society B. Biological Sciences
ER -