Aerodynamically Generated Acoustic Resonance in a Pipe with Annular FlowEnlargements and Restrictors

摘要

The coupling between fluid dynamic instabilities and an acoustic field for thecase of flow within a pipe with annular restrictions is studied. It is found that two different behaviors may exist, depending on the distance between restrictors, and that the fluid flow can amplify the acoustic perturbations at the frequencies of the acoustic modes when the two restrictors are close enough. A physical explanation is proposed, linking the amplificiation of an acoustic perturbation to the phase and frequency of vortex shedding from the restrictors, and a general predictive model is found giving the critical Strouhal number of the phenomenon for any height of restrictor.