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The Unsteady Lift on Bluff Cylindrical Bodies in Unsteady Flow

Published online by Cambridge University Press:  07 June 2016

H. Stapountzis  and
J.M.R. Graham
H. Stapountzis
Affiliation:
Department of Aeronautics, Imperial College of Science and Technology, London
J.M.R. Graham
Affiliation:
Department of Aeronautics, Imperial College of Science and Technology, London
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Summary

The unsteady lift generated on a NACA 0015 aerofoil, a D cylinder (with the flat face down-stream) and an elliptic cylinder was measured when these bodies were exposed to a flow with a two-dimensional sinusoidal upwash at reduced frequencies 0.05 to 0.8. The mean flow Reynolds numbers were in the range 1.2 × 105 to 3 × 105. Unsteady thin aerofoil theory was used in an attempt to predict the unsteady lift on the bluff bodies, as well as the aerofoil section for fequencies in the low range below the vortex shedding frequency. The results were quite accurate for the aerofoil and the D cylinder, but the aerodynamic admittance predicted by this theory for the elliptic cylinder was significantly above that measured experimentally. The movement of the two free separation points was found to play an important role in the characteristic lift behaviour of the elliptic cylinder.

Type
Research Article
Information
Aeronautical Quarterly , Volume 33 , Issue 3 , August 1982 , pp. 219 - 236
Copyright
Copyright © Royal Aeronautical Society. 1982

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