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

4pNSb7. Parametric silencer.

Vladimir V. Arabadzhi

Inst. of Appl. Phys., Russian Acad. of Sci., Dept. of Hydrophys. and Hydroacoust., 603600 Nizhny Novgorod, Russia

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.