Spectral Extrapolation of Frequency-Dependent Fluidelastic Coupling Coefficients from Causality Enforcing
Résumé
Frequency-dependent coupling forces are common in many systems of practical interest, in particular when dealing with flow/structure interactions. The importance of fluidelastic forces in flow-excited vibrations should not be underemphasized in view of their damaging potential. Typically, fluidelastic coupling coefficients are experimentally obtained from vibration experiments, within a limited experimental frequency range. When performing nonlinear time-domain computations, conversion of limited fluidelastic data from the frequency-domain to the time-domain is mandatory, and non-causality will be artificially introduced in the frequency-dependent test data, if one simply assumes that it is nil outside the measured frequency range. Here, a new method is developed for causal frequency interpolation/extrapolation of experimental fluidelastic data. The proposed technique is nonlinear and iterates alternatively between the frequency and time-domains, while enforcing the experimentally available data, as well as causality and regularity conditions, at each iteration. The method is tested and illustrated using as reference data simulated fluidelastic coefficients based on the Granger-Païdoussis model, in the context of heat-exchanger tube bundle vibrations, although the problem addressed embraces a much wider range of applications. The frequency-extended data obtained fulfills the Kramers-Kronig relations and, although unable to recover the dynamical features of the flow-coupling forces which are totally absent from the measured frequency range, the approach has the significant advantage of being model independent and leads to augmented data that is regular and physically consistent.
Domaines
Vibrations [physics.class-ph]
Fichier principal
SMiRT 26 Extended Abstract _ AntunesEtAl_V2.pdf (356.48 Ko)
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