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Abstract

This paper details some investigations relating to non-stationary wave interactions and their effects on the propagation of finite amplitude waves in ducts with either a gradual or sudden change in cross-section. The influence of the angle of divergence on the wave-front and the perturbed flow behind it has been examined in different diffuser configurations using Schlieren spark photography.

The variation with incident pressure of the net pressure (superimposition pressure) and the transmitted pressure are presented for incident pressure ratios up to 3·4. The results have been compared with a quasi-steady one-dimensional analysis and with the theory of Chisnell. Differences between measured and predicted results are attributed to the failure of the theories to account for the wave interactions. A complete analytical solution does not appear possible in view of the complexities of the flow and wave action, and numerical methods have to be employed.

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