Accession Number:

ADA053395

Title:

Spatial Impulse Response of an Acoustic Line Radiator - A Study of Boundary-Diffraction-Wave Phenomena and their Experimental Detection.

Descriptive Note:

Interim rept.,

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s):

Report Date:

1978-02-22

Pagination or Media Count:

240.0

Abstract:

The field radiated by a finite-length line source was investigated theoretically and experimentally. A new closed-form, time-domain theoretical expression of this field was derived. This result, which supports the ideas advanced in the Rubinowicz-Maggi diffraction theory, shows the field of a line source to be comprised of three components a spatially discontinuous cylindrical wave geometrical wave and two directional boundary diffraction waves radiated by the ends of the line. The theory is tested by measuring the spatial impulse response of a line transducer. The experiments were conducted in a water tank, using bursts of pseudorandom noise to excite the transducer electrically. By crosscorrelating these electric signals with the acoustic signals that the transducer radiates, the waveform of the sources spatial impulse response is obtained at a number of observation points. Experimental waveforms are compared to the waveforms theoretically expected. Agreement between theory and experiment is excellent. The experiments constitute the first definitive test of the Rubinowicz-Maggi theory in acoustics. Existence of the geometrical and boundary diffraction waves was confirmed. Moreover, since a standard underwater transducer was used as a source in the experiments, this research demonstrates that the Rubinowicz-Maggi theory is applicable in practical situations. Author

Subject Categories:

  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE