Inverse identification of the acoustic pressure inside a U-shaped pipe line based on acceleration measurements

International audience; In Oil & Gas industry, the high internal sound pressure levels in pipe lines often cause significant structural vibrations. Quantification of the internal acoustic pressures is therefore an important step in understanding the global fluid-structure behaviour of such systems. However, direct acoustic measurements are often not possible since they generally require intrusive access to the pipe interior. In this paper an inverse procedure is proposed to identify the internal sound pressure field within the bend of a U-shaped pipe, from non-intrusive acceleration measurements on the mechanical structure. First, the accelerance transfer functions are measured in the bends and synthesized using a modal expansion. Under operational excitation conditions, the internal sound pressure is then obtained from a Tikhonov regularization of the inverse problem. The limits of the methodology are investigated numerically and experimentally to serve as a fast diagnostic tool for in situ vibration treatment of piping systems.