Vibroacoustic modelling of fluid filled cylindrical shells coupled to ring stiffeners and excited by deterministic or stochastic wall pressure field

This study has been carried out within the R&D framework on sodium water heat exchangers, mainly used in the cooling of Fast Sodium Reactors. The aim is to develop a monitoring technique based on vibration measurements for detecting a leak of water into the sodium. In order to study the efficiency of the developed monitoring technique, numerical and experimental investigations have been carried out on a laboratory mock-up composed of a straight pipe coupled to a hydraulic circuit through two flanges. In this paper, one presents the vibroacoustic model developed for simulating the vibratory signal due to the acoustic source and the vibratory noise induced by the turbulent flow. The model consists in an infinite cylindrical shell filled with water and coupled to two ring stiffeners representing the flanges. A deterministic excitation as an acoustic monopole inside the fluid or a stochastic excitation as the turbulent boundary layer induced by the water flow are considered. The theoretical developments are based on the circumferential admittance approach and a spectral decomposition of the vibratory/pressure fields. The results of the developed model are compared with experimental measurements on the mock-up for the two types of excitation.