The problem of duct-generated noise and its prediction

In this paper, some of the more fundamental notions of the phenomena classified as "subsonic aerodynamic noise" are prsented. In light of these, the authors wish to discuss the mechanisms of noise generation responsible for the self-noise of sound-traps, dampers, diffusers and other duct-located flow discontinuities. Then they suggest on the basis of some recent experimental studies, that the intensity and frequency spectrum of self-noise in ventilation systems can be predicted in a general sense. Tentative formulae are presented to this effect. Finally, recommendations are presented for future work in this area.