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Bifurcation behavior of airfoil undergoing stall flutter oscillations in low-speed wind tunnel

journal contribution
posted on 07.09.2011 by Grigorios Dimitriadis, Jing Li
Stall flutter is a nonlinear aeroelastic phenomenon that can affect several types of aeroelastic systems such as helicopter rotor blades, wind turbine blades, and highly flexible wings. Although the related aerodynamic phenomenon of dynamic stall has been the subject of many experimental studies, stall flutter itself has rarely been investigated. This paper presents a set of experiments conducted on a NACA0012 airfoil undergoing stall flutter oscillations in a low-speed wind tunnel. The aeroelastic responses are analyzed with the objective of characterizing the local bifurcation behavior of the system. It is shown that symmetric stall flutter oscillations are encountered as a result of a subcritical Hopf bifurcation, followed by a fold bifurcation. The cause of these bifurcations is the occurrence of dynamic stall, which allows the transfer of energy from the freestream to the wing. A second bifurcation occurs at the system’s static divergence airspeed. As a consequence, the wing starts to undergo asymmetric stall flutter bifurcations at only positive (or only negative) pitch angles. The dynamic stall mechanism itself does not change but the flow only separates on one side of the wing.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Citation

DIMITRIADIS, G. and LI, J., 2009. Bifurcation behavior of airfoil undergoing stall flutter oscillations in low-speed wind tunnel. AIAA Journal, 47 (11), pp. 2577-2596

Publisher

© American Institute of Aeronautics and Astronautics (AIAA)

Version

NA (Not Applicable or Unknown)

Publication date

2009

Notes

This article is closed access. It was published in the AIAA Journal [© American Institute of Aeronautics and Astronautics] and is available from: http://www.aiaa.org/content.cfm?pageid=406&gTable=jaPaper&gid=39571

ISSN

0001-1452

Language

en

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