Corrugated pipes are used in the oil and gas industry because they are flexible. Such pipes may generate large levels of noise when carrying a gas flow. The noise source is due to the cavities in the corrugations in which vortices form and interact with acoustic waves. The resulting flow-acoustic interaction may result in noise levels sufficient to cause structural vibration which may lead to pipework failure due to fatigue. The interaction between the vortex shedding and the acoustic wave is that of a self-sustained oscillation. The objective of the paper is to attempt to produce an analytical model of these oscillations starting from first principles. Although the model does require some experimental input much information is obtained concerning the details of the mechanism and factors controlling how it scales with the geometry, flow velocity and other relevant parameters. The model requires three constants to complete its formulation. These three constants describe the source strength at low acoustic amplitudes, the nonlinearity as the amplitude is increased and a delay term that relates the vortex shedding to the local acoustic velocity. It emerges that the nonlinear parameter is the most important for determining the maximum acoustic amplitude.

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