A simple theory, based on quasi-steady, one-dimensional flow arguments, is presented for the reflection of a compressive wave in air in a pipe when incident upon a coaxial, convergent nozzle situated at the end of the pipe.
Preliminary shock-tube experiments using quadrant arc nozzles confirm the validity of the theory, and thus enable it to be used to predict the discharge coefficients of sharp-edged orifices from pressure measurements taken in the pipe in the immediate vicinity of the orifices during further shock-tube experiments.
Steady flow discharge coefficients measured experimentally differ from the unsteady flow values by a maximum of 7 per cent.
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