Vibration under flow

Objectives

• Know how to identify the mechanism causing a vibration problem of a structure placed in a flow.     

• Knowing how to choose the acquisition and processing parameters to identify the modes of an aeroelastic system by spectral analysis.

Description

I. Physics of the interaction     

• Examples and industrial context, classification by dimensional analysis, aerodynamic complements.     

• Vortex-induced vibration, lock-in     

• Stability analysis, damping and added stiffness (galloping, divergence)     

• Aeroelastic transients, dynamic stall, hereditary damping    

•  State formalism, modal analysis, antisymmetric stiffness coupling (flutter flexion-torsion of a wing).

II. Experimental identification    

• Periodic estimation of Welch, statistical properties    

•  Method of identification of fluidelastic coupling (direct or indirect)     

• Filtering relations (Wiener-Lee), consistency function     

• Practical application (TP) to spectral and correlation analysis "real time" of a flexible structure in a turbulent flow. Identification of a Movement Induced Vibration (MIV) coupling

Bibliography

• Polycopié Vibrations Sous Ecoulements Turbulents, Physique et modélisation du couplage aéroélastique, G. Harran
• Polycopié Vibrations Sous Ecoulements Turbulents, Démarche expérimentale et problème d'identification, G. Harran

• F. Axisa, Modélisation des systèmes mécaniques -Vibrations sous Ecoulements (Hermès)
• E. de Langre, Fluides et solides, Ecole Polytechnique, 2002
• A. Preumont, Random Vibration and Spectral Analysis, Kluwer, 1994
• P. Hémon, Vibrations des structures couplées au vent, Ecole Polytechnique, 2006
• E.H. Dowell, A modern course in aeroelasticity, Kluwer, 2004
• R.-J. Gibert, Vibrations des structures - Interactions avec les fluides, Sources d'excitation aléatoires, 1988

Session 1 ou session unique - Contrôle des connaissances

Session 2 - Contrôle des connaissances