Engineering Solutions to Noise and Vibration Problems

Sonar Self-Noise

underwater noise

NCE has predicted and controlled the sonar self-noise on naval and commercial vessels - both mono-hulled or SWATH. This is basically a two step process to optimizing the acoustic operation of on-board sonars. The first is to evaluate the radiated or platform noise of the vessel for various operating conditions. The second is to compare this platform noise to the allowable noise based on the sonar self noise goals and sonar system processing capabilities. The self-noise goals account for the operating characteristics of the various sonar suites or can also be derived based on expected operating conditions, including speed, ocean depth, bottom properties, etc.

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Another important design parameter is to ensure the sonars are not located in the vicinity of any bubble sweep-down. Flow modeling of the vessel will reveal the general nature of the flow around the hull and can provide guidance in locating sonar equipment in areas expected to be free from bubble sweepdown.

Machinery systems and propeller contribution calculation procedures, based on the machinery, isolation system, and general arrangement configuration of the vessel, are utilized to evaluate the vessel's platform noise. Airborne, structureborne, fluidborne (hull grazing), and hull-to-hull (for SWATH vessels) paths are all considered.

NCE has utilize its predicted or measured sonar platform noise and vibration database from many research vessels, including NOAA's FRV, R/V KNORR, USN AGOR-24 Class vessels, the USCG ice breaker HEALY, a RAN hydrographic survey vessel, and R/V PALMER and R/V GOULD.