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On the prediction of aerofoil unsteady stall criticality

Published online by Cambridge University Press:  04 July 2016

M. W. Graceyt ,
F. N. Coton  and
R. A. McD. Galbraith
M. W. Graceyt*
Affiliation:
Department of Aerospace Engineering, University of Glasgow, Glasgow, UK
F. N. Coton
Affiliation:
Department of Aerospace Engineering, University of Glasgow, Glasgow, UK
R. A. McD. Galbraith
Affiliation:
Department of Aerospace Engineering, University of Glasgow, Glasgow, UK
*
†Currentiy at the Aerodynamics Department, GKN Westland Helicopters, Yeovil, Somerset, UK.
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Abstract

For practical purposes, it is beneficial to be able to predict the useful operating range of an aerofoil in oscillatory motion before the onset of the strong non-linear effects associated with dynamic stall. In the current work, a range of criteria which have been used to indicate the onset of dynamic stall are presented. It is observed that, since all of these are based on physical manifestations of the dynamic stall process, they may only provide an indication that the process has started rather than identifying the initiation itself. A more suitable criterion for this is the concept of critical angle, first proposed by Wilby. It is shown that the critical angle, which is normally determined through an extensive programme of oscillatory tests on a given aerofoil, is achieved in advance of all the other criteria. The present work presents a correlation which has the potential to determine the critical angle, and hence the useful oscillatory range of an aerofoil, on the basis of simple ramp function tests.

Type
Technical Note
Information
The Aeronautical Journal , Volume 101 , Issue 1007 , September 1997 , pp. 331 - 334
Copyright
Copyright © Royal Aeronautical Society 1997 

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