NUMERICAL STUDY OF A TUBE BUNDLE VIBRATIONS IN CROSS-FLOWS: ALE AND TRANSPIRATION METHODS

摘要

In this paper, we compare the performances of ALE and Transpiration methods. The ALE approach is a powerful tool to treat coupled problems. We can mention for ALE, more precisely, the approach in finite elements of Donea and Hughes. However, the ALE performance for determining fluid-elastic forces to small vibration amplitudes is still ignored. The Transpiration method is a simplified approach for calculating fluid-elastic forces to relatively small vibration amplitudes. Based on a first order development of velocity boundary conditions, this method allows the use of a fluid domain fixed in time during a dynamic computation, by avoiding the problems due to the mesh distortions. The purpose of this work is to provide a numerical estimate of the critical flow velocity for the threshold of fluid-elastic instability of tube bundle without experimental investigation. A staggered coupled numerical approach is suggested and applied to the numerical prediction of the vibration frequency of a flexible tube belonging to a fixed tube bundle in fluid flow. Numerical results turn out to be consistent with available experimental data obtained in the same configuration. This work presents our numerical results for a prediction of tube bundle vibrations induced by flows implemented in CAST3M , a numerical platform of French Nuclear Agency (CEA-Saclay).