### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 4pNSb7. Parametric silencer.

**Vladimir V. Arabadzhi
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*Inst. of Appl. Phys., Russian Acad. of Sci., Dept. of Hydrophys. and
Hydroacoust., 603600 Nizhny Novgorod, Russia
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Total dimensions of the silencer of exhaust gas noise usually are in finite
relations with the sound wavelength, corresponding to the engine assigned
frequency. A silencer design independent of assigned frequency is suggested. An
ultrasound sirenlike flux cyclical switch ensures the N-cascade up-conversion of
the pulsing frequency into the ultrasound frequency range, where the
small-dimensional sound absorbers may be used. N cascades ensure low-frequency
pulsing amplitude decreasing by 2[sup N] times. The output cascade tube diameter
must be more than the input tube diameter by [radical 2] times to save the
average in time total flux cross section. This circumstance is the main factor
that limits a decrease in the size of the silencer dimensions. The results of
experimental investigations of the one-cascade system are presented.