Limit Cycles in Vortex-Induced Vibrations: a Critical Analysis. (2017)

• Record Type: Journal Article
• Authors: Lupi, Francesca; Niemann, Hans-Jürgen; Höffer, Rüdiger
• Is Part Of: Procedia engineering. Volume 199(2017)
• Page Start: 699
• Page End: 704
• Publication Date: 2017
• Subjects: Cross-wind vibrations -- Vortex shedding from a circular cylinder -- Van der Pol -- Rayleigh oscillators -- Aerodynamic Damping -- Limit cycle; Engineering -- Congresses; Engineering -- Periodicals; Engineering; Conference proceedings; Periodicals; 620.005
• DOI: 10.1016/j.proeng.2017.09.127
• Languages: English
• ISSNs: 1877-7058

Abstract

Abstract: The fluid-structure interaction in vortex-induced vibrations of circular structures is modelled as a non-linear damping force. The Van der Pol and Rayleigh oscillators are classic examples of physical systems, which attain a limit cycle under self-induced vibrations. Their application for the case of vortex-induced vibrations has a theoretical justification in Marris, who found an analogy with the Magnus effect for a rotating cylinder, because the lift force on a vibrating cylinder is produced by the non-symmetric boundary layer separation from the top and bottom surfaces. In accordance with the Rayleigh formulation, Vickery&Basu propose for the aerodynamic damping a parabolic relationship function of the rms oscillation. This approach is recommended in many international codes (e.g. Eurocode) for the design of circular structures with regard to cross-wind vibrations, even though the predictions result extremely conservative. Recent wind tunnel experiments performed at WISt (Ruhr-Universität Bochum, Germany) on a circular cylinder in forced-oscillations evidenced a behaviour of the aerodynamic damping with positive curvature, which is in contrast with the negative curvature in Rayleigh oscillator. These experimental results require a critical analysis of the Vickery formulation and its theoretical background.