The examination of position of ship's noises sources based on hydroacoustics method (original) (raw)
Related papers
Influence of Vibration of Ship's Generating Set on Emitted Acoustic Energy
The article presents the investigations of influence of vibration of generating sets on the hydroacoustic spectrum's structure generated through hull of ship to water environment. The investigations were conducted on anchor and during movement of the ship, with characteristic parameters of movement of the ship. The influence of change of speed governor driving engine was considered on produced the voltage's frequency under of load variations the ship's electrical system. It the tests, there were conducted the vibrations' measurements on engine-bed of the individual generating set, on the ship's hull of directly under sets, as well as the measurements of underwater noise under hull of ship. The analysis consist with the qualification of levels of the measured parameters and the changes spectrum's vibrations of underwater noise as well as their correlations. It was analysed with possible exploational states of the ship, number of working generating sets, ...
Acoustical Impact Of The Ship Source
The ship as whole represents quite a complex noise source. The generated noise affects definitely people on board the vessel (crew and passengers, directly exposed to sound pressure levels) but third parties as well, which may be reached by airborne or underwater noise transmission from the ship: inhabitants of areas near the coastline and near ports, the marine fauna living in zones with intense maritime traffic). The threefold aspect of the acoustical impact of ships (internal to the vessel, external in air and in water) is covered in the paper, which identifies in each context the main sources of noise, the potential receivers and the transmission paths linking sources and receivers. The state of the art and new trends in the characterization of the sources are evaluated, as well as the means available to model the transmission of acoustical power along the various effective paths. The available means for charactering the perception by the receivers in the various contexts are considered, in order to assess the impact of the noise radiation. The more or less recent introduction of norms and requirements in the different fields are discussed and analyzed, in order to highlight the evolution of the societal concern about the ship noise impact on second and third parties of the maritime transportation process. Such concern justifies the undergoing process of further implementations in the normative framework. The trends of this evolution are finally discussed, with description and motivation of pre-normative proposals covering the three aspects above mentioned. The work builds on the results of project SILENV, recently funded by the EU.
Disturbances in noise propagation generated by a moving ship in shallow water
2014
Noise propagation generated by a moving ship in shallow water is always associated with energy loss because of absorption and the fact that sound is scattered by medium inhomogeneities, also resulting in a decrease of sound intensity with range. Furthermore sound propagation is strongly dependent on fluid space geometry and dimension, as well as reflection and transmission loss through the sea bottom. The geometrical dimensions of the measured ship and shallow water are comparable. The depth of water is usually less than the length of the ship, so machinery vibration-due to propulsion machinery and auxiliary machinery-acoustic noise in the compartments below the waterline, flow noise and propeller noise are not generated by the hull of the ship from one point only. Hydroacoustic measurement range is designed with the purpose of exploiting and distinguishing these effects because of the amount of information they each bring; they allow to identify a different class of ship, although interpretation of spatial distribution is very difficult because of sound propagation in shallow water. This paper presents experimental research into the noises of moving ships, measured on the sea bottom, with reflection about the influences of sound propagation on the results of underwater acoustic measurement ranges.
Underwater noise radiated by ships, their propulsion and auxiliary machinery, and propellers
2001
These underwater radiated noise and vibration measurements were conducted on a full-scale ship in August 2000. During the trails it was found that several spike noises are dominant. To find the location oj high vibration level places and its frequencies, and the machines, which generated high level point noise components, 4 accelerometers were fixed in the engine and auxiliary rooms .We were using this system to find the relationship between certain manoeuvres and the vibratlon level caused by them. Propellers and engines are usually the major sources of noise in ships but gearboxes can also be significant contributors. The way of mounting of the machines and the resulting vibration oj the hull are determining issues in the radiation ot underwater noise. Naval Test and Evaluation Acoustic Ranges contain an accurate radiated noise measurement system consisting of a bottom-mounted hydrophone array for sailing condition and a stationary range. The sophisticated digital narrow-band inst...
Sustainable Maritime Transportation and Exploitation of Sea Resources, 2011
The evaluation of the acoustic impact of ships is a complex problem, involving not only different sources but also different kinds of receivers and transmission paths. The problem of health and comfort for crew and passengers on board has been considered since a few decades, leading to quite a structured and detailed framework of Norms and Requirements. On the other hand, only in recent years a growing attention has been devoted to air-borne noise emissions outside the ship, for which requirements are not present. Underwater noise emissions have, even more recently, gained attention for their potential interference with mammals' communications and with the sophisticated use such animals make of acoustic signals for interacting with their living environment. An aim of the present work is to review the state of the art in the three areas above identified outlining the differences in the specific fields as regards: the present knowledge of the phenomena involved; the accuracy of the models available for the description of noise propagation; the accuracy of the models available for the quantification of noise effects.
2019
Great concern has been raised to emphasize significant amount of the underwater noise generated by human activity related to commercial shipping recently. Rising noise levels that is generated by the human activities can negatively impact ocean life especially for marine mammals in both short and long terms. International Maritime Organization (IMO) and other bodies have been trying to set-up guidelines in order to reduce noise levels at sea [IMO, 2014]. As clearly stated in mentioned guidelines, for the prediction purposes of the underwater noises, Computational Fluid Dynamics (CFD) methodologies could be applied to predict and visualize flow characteristics related to hull and appendages as well as propellers. Many researches have been undertaken to measure underwater noise originating from propeller rotation. In addition to propellers, hull shape is also crucial for ship-generated noise. Uneven and non-homogeneous wake fields are known to increase cavitation. Therefore; the ship ...
Acoustic impact of ships: noise-related needs, quantification and justification
The evaluation of the acoustic impact of ships is a complex problem, involving not only different sources but also different kinds of receivers and transmission paths. The problem of health and comfort for crew and passengers on board has been considered since a few decades, leading to quite a structured and detailed framework of Norms and Requirements. On the other hand, only in recent years a growing attention has been devoted to air-borne noise emissions outside the ship, for which requirements are not present. Underwater noise emissions have, even more recently, gained attention for their potential interference with mammals' communications and with the sophisticated use such animals make of acoustic signals for interacting with their living environment. An aim of the present work is to review the state of the art in the three areas above identified outlining the differences in the specific fields as regards: the present knowledge of the phenomena involved; the accuracy of the models available for the description of noise propagation; the accuracy of the models available for the quantification of noise effects.
Measurements of hydro-acoustic noise emitted from vessels are a.o. a subject of the tests carried out in the control measurement ranges of the Navy. The measurements are performed both on anchored and floating vessels. Acoustic field of vessels is changing along with their speed changing and is associated with acoustic activity of wave sources installed in vessel's hull (main engines, electric generating sets, reduction gears, pumps, shaft-lines, piping, ventilating ducts etc) as well as hydro-dynamic sources such as screw propellers and water flow around the hull . Vibration energy generated by the onboard devices is transferred through ship structural elements to water where it propagates in the form of hydro-acoustic waves of a wide frequency band.
Modelling of ships as a source of underwater noise
Ocean Science, 2018
In this paper, a methodology is presented for modelling underwater noise emissions from ships based on realistic vessel activity in the Baltic Sea region. This paper combines the Wittekind noise source model with the Ship Traffic Emission Assessment Model (STEAM) in order to produce regular updates for underwater noise from ships. This approach allows the construction of noise source maps, but requires parameters which are not commonly available from commercial ship technical databases. For this reason, alternative methods were necessary to fill in the required information. Most of the parameters needed contain information that is available during the STEAM model runs, but features describing propeller cavitation are not easily recovered for the world fleet. Baltic Sea ship activity data were used to generate noise source maps for commercial shipping. Container ships were recognized as the most significant source of underwater noise, and the significant potential for an increase in their contribution to future noise emissions was identified.
Modeling of ships as a source of underwater noise
In this paper, a methodology is presented for modeling underwater noise emissions from ships based on realistic vessel activity in the Baltic Sea area. This paper combines the Wittekind noise source model with the Ship Traffic Emission Assessment Model (STEAM) in order to produce regular updates for underwater noise from ships. This approach allows the construction of noise source maps, but requires parameters which are not commonly available from commercial ship technical databases. For this reason, alternative methods to fill in the required information were necessary. Most of the parameters needed contain information which are available during the STEAM model runs, but features describing propeller cavitation are not easily recovered for the world fleet. Baltic Sea ship activity data was used to generate noise source maps for commercial shipping. Containerships were identified as the most significant source of underwater noise, with a significant potential for increasing contribution to future noise emissions.