Archives of Acoustics, 26, 2, pp. , 2001

Determination of the spatial distribution of ship's noise components

P. Bittner
Naval Academy

E. Kozaczka
Naval Academy; Technical University of Koszalin

The investigations of vibroacoustic activity of a ship is a
topic of interest for technical diagnostics, ecological and military reasons. A
ship may be treated as a coaxial sound source. Descriptions of the field
distribution for such sources are common in literature. The methods used for
solving the radiation problem include analytical solutions, numerical methods
and experimental investigations. As a ship is a complex sound source, it is
difficult to find an analytical description of its radiation in the near field
region. Therefore the paper describes a method which has the elements of a
numerical and an experimental one. The hull is surrounded with a surface which
replaces the ship as a source. The experimentally obtained distributions of
acoustic quantities were used to calculate the pressure value in any point in
space outside the virtual surface. A numerical method has been worked out basing
on the Helmholtz solution of the exterior radiation problem and the
superposition method. It was verified by comparing its results with the
approximate analytical dependence found out for a simple source of the shape
similar to the virtual surface. The method of measuring the acoustic quantities
is described next. The special attention was paid to the particle velocity
measurements. The theoretical background was followed with the results of
laboratory measurements. After the laboratory investigations, the method has
been checked during in situ measurements.

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