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Leading-edge vortex dynamics on plunging airfoils and wings

Published online by Cambridge University Press:  11 April 2022

O. Son Open the ORCID record for O. Son [Opens in a new window] ,
A.-K. Gao Open the ORCID record for A.-K. Gao [Opens in a new window] ,
I. Gursul Open the ORCID record for I. Gursul [Opens in a new window] ,
C.D. Cantwell Open the ORCID record for C.D. Cantwell [Opens in a new window] ,
Z. Wang Open the ORCID record for Z. Wang [Opens in a new window]  and
S.J. Sherwin Open the ORCID record for S.J. Sherwin [Opens in a new window]
O. Son
Affiliation:
Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK
A.-K. Gao
Affiliation:
Department of Aeronautics, Imperial College London, London, SW7 2AZ, UK
I. Gursul*
Affiliation:
Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK
C.D. Cantwell
Affiliation:
Department of Aeronautics, Imperial College London, London, SW7 2AZ, UK
Z. Wang
Affiliation:
Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK
S.J. Sherwin
Affiliation:
Department of Aeronautics, Imperial College London, London, SW7 2AZ, UK
*
†Email address for correspondence: ensiag@bath.ac.uk
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Abstract

The vortex dynamics of leading-edge vortices on plunging high-aspect-ratio (AR = 10) wings and airfoils were investigated by means of volumetric velocity measurements, numerical simulations and stability analysis to understand the deformation of the leading-edge vortex filament and spanwise instabilities. The vortex filaments on both the wing and airfoil exhibit spanwise waves, but with different origins. The presence of a wing-tip causes the leg of the vortex to remain attached to the wing upper surface, while the initial deformation of the filament near the wing tip resembles a helical vortex. The essential features can be modelled as the deformation of an initially L-shaped semi-infinite vortex column. In contrast, the instability of the vortices is well captured by the instability of counter-rotating vortex pairs, which are formed either by the trailing-edge vortices or the secondary vortices rolled-up from the wing surface. The wavelengths observed in the experiments and simulations are in agreement with the stability analysis of counter-rotating vortex pairs of unequal strength.

JFM classification

Vortex Flows: Vortex dynamics
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 940 , 10 June 2022 , A28
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Copyright
© The Author(s), 2022. Published by Cambridge University Press

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