Accession Number : AD0013144


Title :   HIGH AMPLITUDE SOUND ABATEMENT RESEARCH PROGRAM


Descriptive Note : Final rept.


Corporate Author : BODINE ENGINE CO LOS ANGELES CA


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/013144.pdf


Report Date : Feb 1953


Pagination or Media Count : 29


Abstract : A sound source was developed which is capable of delivering continuous acoustic power into a 10-in.-diam tube at acoustic levels up to 100 kw, provided the tube temperature does not exceed 170 deg. F. An accurate and reliable condenser microphone system was developed for essentially continuous use in acoustic fields with pressure swings approaching 1 atm. Theories were developed for the attenuation of high-amplitude plane waves; however, the predicted attenuation rates were higher than those obtained experimentally. Preliminary measurements of water-spray influence on attenuation rates indicated no significant attenuation effect due to water spray and no clear evidence of frequency dependence. Measurements of the shunting impedance presented by a Helmholtz resonator placed in the 10-in.-tube wall indicated that, for an approximate 56-c low-amplitude frequency, the combination of the resonator and the downstream portion of the tube appeared resistive when the sound frequency matched the low-amplitude resonator frequency. An analysis of the standing-wave structure at this frequency for 6 particle-velocity amplitudes established that the impedance was given by R = 1/2 P rho U sub o, where P rho sub o is the equilibrium density of air, U sub o is the particle velocity amplitude, and S is the cross-sectional area of the neck of the resonator. (See also AD10268)


Descriptors :   *SOUND GENERATORS , *SOUND PRESSURE , *NOISE POLLUTION , WATER , RATES , ACCURACY , EQUILIBRIUM(GENERAL) , RELIABILITY , CROSS SECTIONS , ACOUSTICS , RESONATORS , ACOUSTIC ATTENUATION , AMPLITUDE , MICROPHONES , ATMOSPHERIC DENSITY , ACOUSTIC FIELDS , FIELD INTENSITY , NOISE(SOUND) , UNINTERRUPTABLE POWER GENERATION , TEMPERATURE , HELMHOLTZ EQUATIONS , VELOCITY , FREQUENCY


Subject Categories : Acoustics
      Noise Pollution and Control


Distribution Statement : APPROVED FOR PUBLIC RELEASE