Aerocoustic response of diffusers and bends: comparison of experiments with quasi-steady incompresibel flow models

Experimental results were obtained in the study of the aeroacoustic response of diffusers and abrupt expansions. An experimental study on the aeroacoustics of bends has also been carried out and shows similar results. In both cases the low-frequency aeroacoustic behaviour can be predicted by a quasi-steady flow model when the flow separation point is fixed by sharp edges in the geometry. At smooth pipe discontinuities nonlinear effects are more important and the response is essentially unsteady.