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In PWR steam generators, appropriate supports like the anti-vibration bars are designed to prevent excessive vibrations of tubes submitted to flow-induced excitation. However degraded or unwanted situations where the gap between tubes and supports is widen have to be considered for safety reason.

In this context, correct modelling of fluidelastic forces is of first importance as they are responsible of hypothetical instability. Their identification is still an active research domain and requires both numerous experimental data and well-suited mathematical models.

In this paper, the Granger-Paidoussis model, also referred to as the quasi-unsteady model, is adopted and the computation of the fluidelastic forces in time domain a through convolution product, that has been  recently proposed, is adopted.

The efficient implementation of such a methodology in an industrial numerical code enables to deal with practical cases encountered in nuclear applications.

More particularly the GERBOISE toolbox is here considered. Based on the finite element code Cast3M developed at CEA (French Alternative Energies and Atomic Energy Commission) with the collaboration of AREVA, GERBOISE is a reference code to simulate the non-linear dynamics of heat-exchanger tubes taking into account, among other things, the specificity of flow-induced excitation and impact with friction.

In the present work, the application of the mentioned methodology to both an academic system for which experimental data are available (a rigid square bundle with one flexible tube) and to the more complex case of a realistic heat-exchanger tube with multiple contact zones are presented.

Essentially the dynamic behaviour of the academic case is compared to the industrial case in term of Rice frequency evolution, limit cycles, modal participation and effect of multiple contacts.

fluidelastic force; impact; heat exchanger; multiple contact