Asymptotic and numerical analysis of resonance and lock-in by flow-acoustic interaction in an expansion chamber-pipe system

Abstract

The paper is concerned with the generation of sound by the flow through a closed, cylindrical expansion chamber, followed by a long tailpipe. The sound generation is due to self-sustained flow oscillations in the expansion chamber which, in turn, may generate standing acoustic waves in the tailpipe. The main interest is in the interaction between these two sound sources. An analytical, approximate solution of the acoustic part of the problem is obtained via the method of matched asymptotic expansions. The sound-generating flow is represented by a discrete vortex method, which is modified to include the effects of acoustic feedback. It is demonstrated that lock-in of the self-sustained flow oscillations to the resonant acoustic waves in the tailpipe can take place.