Linear sound propagation in an axisymmetric corrugated pipe with shear flow is studied numerically and experimentally. The acoustic and hydrodynamic perturbations are described by the linearized Euler equations (LEEs) in a parallel shear flow. Wave propagation and scattering are computed by means of a multimodal method where the disturbances are expressed as a linear combination of acoustic modes and hydrodynamic modes. The Floquet-Bloch approach is used to calculate the wavenumber in the periodic system. Both sound amplification and absorption, depending on the Strouhal number, are well predicted compared to experiments, which means that the flow-acoustic coupling in the system is effectively described by the present model. It is also shown that the corrugated pipe can amplify the sound even if the shear layer over the cavities is stable everywhere.
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