Sound transmission and generation in ducts with flow

Abstract

Sound generation in hard-walled ducts with flow is treated theoretically. Axial standing waves are allowed for in the theoretical model, by applying an impedance boundary condition at the ends of the duct. The results show the effects of axial and swirling flow on the radiated sound power, for different types of source contained in the duct. Suggestions are also put forward for analysing the generation of sound by sources at a mean-flow discontinuity.