Vorticity transport and the leading-edge vortex of a plunging airfoil

Azar Eslam Panah, James M. Akkala, James H.J. Buchholz

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The three-dimensional flow field was experimentally characterized for a nominally two-dimensional flat-plate airfoil plunging at large amplitude and reduced frequencies, using three-dimensional reconstructions of planar PIV data at a chord-based Reynolds number of 10,000. Time-resolved, instantaneous PIV measurements reveal that secondary vorticity, of opposite sign to the primary vortex, is intermittently entrained into the leading-edge vortex (LEV) throughout the downstroke, with the rate of entrainment increasing toward the end of the stroke when the leading-edge shear layer weakens. A planar vorticity transport analysis around the LEV indicated that, during the downstroke, the surface vorticity flux due to the pressure gradient is consistently about half that due to the leading-edge shear layer for all parameter values investigated, demonstrating that production and entrainment of secondary vorticity is an important mechanism regulating LEV strength. A small but non-negligible vorticity source was also attributed to spanwise flow toward the end of the downstroke. Aggregate vortex tilting is notably more significant for higher plunge frequencies, suggesting that the vortex core is more three-dimensional.

Original languageEnglish (US)
Article number160
JournalExperiments in Fluids
Volume56
Issue number8
DOIs
StatePublished - Aug 27 2015

Fingerprint

airfoils
leading edges
Vorticity
Airfoils
vorticity
Vortex flow
vortices
shear layers
entrainment
particle image velocimetry
three dimensional flow
flat plates
strokes
Pressure gradient
pressure gradients
Reynolds number
Flow fields
flow distribution
Fluxes

All Science Journal Classification (ASJC) codes

  • Computational Mechanics
  • Mechanics of Materials
  • Physics and Astronomy(all)
  • Fluid Flow and Transfer Processes

Cite this

Eslam Panah, Azar ; Akkala, James M. ; Buchholz, James H.J. / Vorticity transport and the leading-edge vortex of a plunging airfoil. In: Experiments in Fluids. 2015 ; Vol. 56, No. 8.
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Vorticity transport and the leading-edge vortex of a plunging airfoil. / Eslam Panah, Azar; Akkala, James M.; Buchholz, James H.J.

In: Experiments in Fluids, Vol. 56, No. 8, 160, 27.08.2015.

Research output: Contribution to journalArticle

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