Journal article
Vorticity transport and the leading-edge vortex of a plunging airfoil
Experiments in fluids, Vol.56(8), pp.1-15
07/26/2015
DOI: 10.1007/s00348-015-2014-7
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.
Details
- Title: Subtitle
- Vorticity transport and the leading-edge vortex of a plunging airfoil
- Creators
- Azar Eslam Panah - University of IowaJames M Akkala - University of IowaJames H. J Buchholz - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Experiments in fluids, Vol.56(8), pp.1-15
- Publisher
- Springer Berlin Heidelberg
- DOI
- 10.1007/s00348-015-2014-7
- ISSN
- 0723-4864
- eISSN
- 1432-1114
- Grant note
- FA9550-11-1-00190 / Air Force Office of Scientific Research (http://dx.doi.org/10.13039/100000181)
- Language
- English
- Date published
- 07/26/2015
- Academic Unit
- Mechanical Engineering
- Record Identifier
- 9984196638502771
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