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Nonlinear Effects in Transonic Flutter with Emphasis on Manifestations of Limit Cycle Oscillations

Schewe, G. and Mai, H. and Dietz, G. (2002) Nonlinear Effects in Transonic Flutter with Emphasis on Manifestations of Limit Cycle Oscillations. IUTAM Symposium Transsonicum IV, Göttingen, September 2-6, 2002.

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In order to study the typical transonic phenomena in as pure a form as possible, we used a model having a simple geometry (2 D wing) for our flutter experiments in the Transonic Wind-Tunnel. We found that various manifestations of small-amplitude limit-cycle oscillations occurred in which either one or two degrees of freedom were involved. In addition, we observed an alternating excitation and coexisting limit cycle. We have also demonstrated how very small control forces were sufficient to influence the state of the system, as is generally the case in nonlinear systems, and thereby suppress flutter oscillations. Limit cycles occur under free and forced transition in both a perforated and an adaptive test section, so we can exclude the possibility that they are artifacts. The results of corresponding experiments with a conventional NACA 0012 airfoil showed no comparable small-amplitude limit-cycle oscillations. Flutter calculations based on measured aerodynamic forces yield stability limits whose values show good agreement with directly measured ones. The insight gained from these investigations leads to the conclusion that, for limiting the amplitude of transonic flutter, we have to take account of the three possible mechanisms responsible for it, viz., the flow separation at the trailing edge, 3D effects, and the interactions between the shock and the marginal region of separated flow beneath it.

Item URL in elib:https://elib.dlr.de/14366/
Document Type:Conference or Workshop Item (Speech)
Additional Information: LIDO-Berichtsjahr=2003,
Title:Nonlinear Effects in Transonic Flutter with Emphasis on Manifestations of Limit Cycle Oscillations
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:Transonic Flutter, Limit Cycle Oscillations, Nonlinear Effects
Event Title:IUTAM Symposium Transsonicum IV, Göttingen, September 2-6, 2002
Organizer:DLR Göttingen
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:other
DLR - Research area:Aeronautics
DLR - Program:L ST - Starrflüglertechnologien
DLR - Research theme (Project):UNSPECIFIED
Location: Göttingen
Institutes and Institutions:Institute of Aeroelasticity
Deposited By: Erdmann, Daniela
Deposited On:16 Sep 2005
Last Modified:14 Jan 2010 21:45

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