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EXPERIMENTAL INVESTIGATION OF THE PARAMETERS AFFECTING THE PRESSURE PROFILES OF FINITE AMPLITUDE STANDING WAVES IN AIR-FILLED TUBES.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
It was found that the wave forms for different tubes would be the same if the following quantities were made equal 1 the ratio of the driver acceleration to the acoustic attenuation constant, and 2 the phase angle between the acceleration and the pressure at infinitesimal amplitudes. Values of the attenuation constant were determined by several different methods including measuring the decay of pressure after clamping the driver piston and by determining the ratio of acceleration to pressure. Observed attenuation constants were of the order of 0.0001 per cm. The resonant frequency for infinitesimal amplitude was observed to be the frequency maximizing both the average rectified pressure and the shock strength only for the stronger shocks. However, for week shocks the shock strength became a maximum at lower and lower frequencies as the pressure decreased. This tendency, as indicated by the amount of second harmonic distortion, continued in the weak finite amplitude region. Author