An experimental study of the chocked jet was made using axisymmetric nozzles to investigate the flow property and the acoustical characteristics. The character of the choked jet noise had been shown by many authors to be determined by that of the flow itself and, in particular, by the regular shock wave spacing. This experiment showed that the exit velocity had signigicant relation with the peak frequency of the noise generated by the flow.
A new method for calculating the boundary of the choked jet is presented which is simpler than other methods, that is, the characteristics method and so all. The new method is based on the fact that the underexpanded flow is determined by the exit nozzle configuration, the exit vellocity and, above all, the static pressure of the flow at the exit. The results were compared with photographs of actual jets and other author's ones. Favorable agreement was obtained.
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