The implications of low-speed fixed-wing aerofoil measurements on the analysis and performance of flapping bird wings
(2008) In Journal of Experimental Biology 211(2). p.215-223- Abstract
- Bird flight occurs over a range of Reynolds numbers (Re; 104Re105, where Re is a measure of the relative importance of inertia and viscosity) that includes regimes where standard aerofoil performance is difficult to predict, compute or measure, with large performance jumps in response to small changes in geometry or environmental conditions. A comparison of measurements of fixed wing performance as a function of Re, combined with quantitative flow visualisation techniques, shows that, surprisingly, wakes of flapping bird wings at moderate flight speeds admit to certain simplifications where their basic properties can be understood through quasi-steady analysis. Indeed, a commonly cited measure of the relative flapping frequency, or wake... (More)
- Bird flight occurs over a range of Reynolds numbers (Re; 104Re105, where Re is a measure of the relative importance of inertia and viscosity) that includes regimes where standard aerofoil performance is difficult to predict, compute or measure, with large performance jumps in response to small changes in geometry or environmental conditions. A comparison of measurements of fixed wing performance as a function of Re, combined with quantitative flow visualisation techniques, shows that, surprisingly, wakes of flapping bird wings at moderate flight speeds admit to certain simplifications where their basic properties can be understood through quasi-steady analysis. Indeed, a commonly cited measure of the relative flapping frequency, or wake unsteadiness, the Strouhal number, is seen to be approximately constant in accordance with a simple requirement for maintaining a moderate local angle of attack on the wing. Together, the measurements imply a fine control of boundary layer separation on the wings, with implications for control strategies and wing shape selection by natural and artificial fliers. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/954553
- author
- Spedding, Geoff ; Hedenström, Anders LU ; McArthur, John and Rosén, Mikael LU
- organization
- publishing date
- 2008
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- animal flight, aerofoil, lift-drag polar, wake analysis, Reynolds number
- in
- Journal of Experimental Biology
- volume
- 211
- issue
- 2
- pages
- 215 - 223
- publisher
- The Company of Biologists Ltd
- external identifiers
-
- wos:000253196300009
- scopus:39049149132
- pmid:18165249
- ISSN
- 1477-9145
- DOI
- 10.1242/jeb.007823
- language
- English
- LU publication?
- yes
- id
- 6672abec-1150-4d4e-9735-ede0ffa885d9 (old id 954553)
- date added to LUP
- 2016-04-01 12:06:46
- date last changed
- 2022-01-26 22:57:28
@article{6672abec-1150-4d4e-9735-ede0ffa885d9,
abstract = {{Bird flight occurs over a range of Reynolds numbers (Re; 104Re105, where Re is a measure of the relative importance of inertia and viscosity) that includes regimes where standard aerofoil performance is difficult to predict, compute or measure, with large performance jumps in response to small changes in geometry or environmental conditions. A comparison of measurements of fixed wing performance as a function of Re, combined with quantitative flow visualisation techniques, shows that, surprisingly, wakes of flapping bird wings at moderate flight speeds admit to certain simplifications where their basic properties can be understood through quasi-steady analysis. Indeed, a commonly cited measure of the relative flapping frequency, or wake unsteadiness, the Strouhal number, is seen to be approximately constant in accordance with a simple requirement for maintaining a moderate local angle of attack on the wing. Together, the measurements imply a fine control of boundary layer separation on the wings, with implications for control strategies and wing shape selection by natural and artificial fliers.}},
author = {{Spedding, Geoff and Hedenström, Anders and McArthur, John and Rosén, Mikael}},
issn = {{1477-9145}},
keywords = {{animal flight; aerofoil; lift-drag polar; wake analysis; Reynolds number}},
language = {{eng}},
number = {{2}},
pages = {{215--223}},
publisher = {{The Company of Biologists Ltd}},
series = {{Journal of Experimental Biology}},
title = {{The implications of low-speed fixed-wing aerofoil measurements on the analysis and performance of flapping bird wings}},
url = {{http://dx.doi.org/10.1242/jeb.007823}},
doi = {{10.1242/jeb.007823}},
volume = {{211}},
year = {{2008}},
}