Noise radiated from fluid loaded stiffened cylindrical shells subject to a turbulent boundary layer

Cylindrical shells are often employed as simplified models to represent the physics of underwater vehicles. When a vehicle is moving underwater, the flow is likely to create a turbulent boundary layer (TBL) over the shell surface. The TBL induces vibrations on the shell, which results in the radiation of noise. Semi-analytical formulations are nowadays widely used to predict the vibro-acoustics of structures and re-design them to mitigate the flow-induced noise. However, most of the methods available in literature tackle the case of flat plates and only few results can be found for cylindrical shells. In this chapter, we give an overview of a method for calculating both the response of a fluid loaded cylindrical shell and the outward emitted noise, with different degrees of complexity. The considered test cases involve various phenomena and underlying physics. Aspects such as the role of propagative Bloch-Floquet waves in noise radiation by periodically stiffened structures, or the influence of mechanical coupling between the shell and non-axisymmetric inner structures are addressed. An explanation is also given for the very different behavior of the radiated acoustic pressure in the near and far fields.