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Trailing-edge flap flow control for dynamic stall

Published online by Cambridge University Press:  27 January 2016

R. B. Green ,
E. A. Gillies  and
Y. Wang
R. B. Green*
Affiliation:
Department of Aerospace Engineering, University of Glasgow, Glasgow, UK
*
richard.green@glasgow.ac.uk
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Abstract

Results of a series of oscillatory dynamic stall tests of a rotor aerofoil fitted with a pulsed, trailing-edge flap are presented. Flap deflection amplitude, motion profile, duration and starting phase were investigated to assess the potential of the flap for mitigating the adverse effects of dynamic stall, which is one of the limiting factors for rotor blades on the retreating side of a helicopter rotor. The tests were a continuation of the investigations by Ref. 1 who used a computational fluid dynamics method on a symmetric NACA section, and our results broadly confirm their conclusions by experimental test, using a modern rotor section. The results presented in this paper also confirm the observations from experimental work by Refs 2 and 3, which were undertaken at lower Reynolds number and with a larger flap. In the present study, the flap mitigates the high negative pitching moment and negative pitch damping seen in dynamic stall by strong suction being generated over the aerofoil lower surface, and it is the modification to the lower surface shape by the flap that creates this effect. The dynamic stall vortex acts to enhance the lower surface suction, and careful flap phasing and flap motion profile shaping can make the control more effective.

Type
Research Article
Information
The Aeronautical Journal , Volume 115 , Issue 1170 , August 2011 , pp. 493 - 503
Copyright
Copyright © Royal Aeronautical Society 2011 

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