Identification of hydroacoustic wave sources of ship in motion

Abstract

This paper deals with results of identification tests of acoustic field spectrum of underwater noise generated by ship in motion. The field is connected with acoustic activity of ship mechanisms and devices in operation. Vibration energy generated by the mechanisms and devices is transferred through ship structural elements to surrounding water where it propagates in the form of acoustic waves of a broad band of frequencies. In the publication results of identification tests of underwater noise generated by a ship in motion, arepresented.

Shipping Low Frequency Noise and Its Propagation in Shallow Water

“…On the basis of the simultaneous measurements of underwater noise and vibration of main mechanisms and auxiliary equipment of the ship, it is possible to define unambiguously the components visible in the first of area distinguished in the spectrogram [4,5]. To identify the components, the spectral analysis with using constant band width filters is often performed.…”

“…4 discrete components are noticeable which are the effect of activity of main engines, shaft lines and propeller, and also an electric generating set. Each particular component was distinguished by a successive number, namely one group of numbers (2, 4, 6, 8, 10, 12, 14, 17, 19, 21) indicate components coming from propeller and shaft lines, and other group of numbers (1,3,5,7,9,11,13,15,16,17,18,20,22,23,24,25) show components coming from working main engines. The identification results obtained by using the method in question have been confirmed in the following papers [4][5][6][7].…”

“…7. Just as the ship was directly above the sensor, a wavelength of standing wave was 40 m. The length of this wave sets the creation of the fundamental mode, which is associated with the depth [3,6].…”