Accession Number : ADA134233

Title :   Propeller Cavitation Effects on Broadband Vessel-Radiated Acoustic Spectra.

Descriptive Note : Final rept. 1982-1983,

Corporate Author : NAVAL ACADEMY ANNAPOLIS MD

Personal Author(s) : Dixon,Daniel N

PDF Url : ADA134233

Report Date : 20 Jun 1983

Pagination or Media Count : 39

Abstract : To gain an understanding of ambient noise in the oceans today, the characteristics of merchant vessel acoustic spectra must be determined. Presently, it is believed that the major source of acoustic intensity emanating from a merchant is propeller noise. Data was gathered from a stationary vessel whose propellers were cavitating to determine exactly how much of the far field spectrum was propeller dominated. Considerations such as propagation delay and multi-path effects had to be dealt with prior to the processing procedure. Digital signal processing techniques along with the coherence function were applied to the gathered data. The resulting coherence values for frequencies of interest to Navy sonar systems (0-500 Hz) were studied and compared to the corresponding signal-to-noise level in the far field spectrum. The coherence accurately displays that, contrary to present belief, propeller cavitation is not the dominant source of merchant vessel acoustic power in the far field over the entire frequency band of interest.

Descriptors :   *Cavitation noise, *Underwater acoustics, *Ship noise, Spectra, Coherence, Merchant vessels, Propeller noise, Marine propellers, Acoustic data, Spectrum analyzers, Sound transmission, Multipath transmission, Broadband, Radiated noise, Far field, Ambient noise, Sonar targets, Signal to noise ratio, Acoustic signatures, Signal processing

Subject Categories : Marine Engineering
      Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE