Wyniki wyszukiwania - Biblioteka Nauki

1

Ship's underwater noise measurements using sound intensity method

100%

Gloza I.

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tom Vol. 12

53-60

EN

Ship noise is a most important part of the field of underwater acoustics. Its reduction and monitoring is an important aspect in the performance of underwater acoustic systems and in the habitability of the vessel for the crew and passengers. In naval operations the noise radiated by a ship is also dominant source of information for underwater sonar systems. Sound intensity is the vector quantity which informs us about the sound power flux, the position and the direction of the sound source. The probe tracks the position of source and at the same time, measures the component of sound-intensity vector. Generally only one component of vector sound intensity was measured, perpendicular to a given measurement surface. The sound intensity of a moving source includes effects such as flow noise that are not present when the source is stationary. The accuracy of measuring acoustic intensity using two closely spaced hydrophones by correcting the phase mismatch error by measuring the transfer function between the two detector systems was examined. The two measuring hydrophone instrumentation systems were earlier calibrated. Our results have been obtained using digital methods, where was used PULSE measuring system.

2

Sound Emitted by Ships and Grey Seals into Water Environment

100%

Gloza I.

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tom T. 23, z. 2

161-168

EN

In this paper we give a brief introduction to the marine behaviour of the grey seals and describe the current state of knowledge about their hearing and influence of ship noise into their life. The Naval University had the opportunity to record these sea mammals vocalizations in the Polish peninsula Hel. The waters of the Baltic Sea are major area for shipping, military exercises and activities including: merchant vessels movement, surface warships and submarines exercises, torpedo testing and firing ranges, therefore they are full of noise. Ship noise spectra are usually in two categories: broad-band noise, which has a continuous spectrum; and tonal noise, which contains discrete frequencies or lines. Additionally the acoustic radiation is also characterized by passing and irregular noise caused by impacts, loose equipment and machinery changes of state. Propeller cavitation is also a major problem here.

PL

Dźwięki emitowane przez obiekty podwodne są źródłem fal akustycznych rozchodzących się w środowisku wodnym. Proces ten może mieć szkodliwy wpływ na równowagę ekologiczną, zwłaszcza w przypadku takich źródeł jak statki i okręty, w akwenach o dużym nasileniu ruchu. Głównym celem artykułu jest przedstawienie wyników obszernych badań doświadczalnych związanych z transmisją do wody energii akustycznej przez jednostki pływające. W pracy przedstawiono metodykę oceny transmisji do wody energii drgań mechanizmów okrętowych znajdujących się wewnątrz kadłuba. Przedstawiono również wyniki badań dźwięków emitowanych przez fokę szarą w postaci wąskopasmowych widm mocy. Mając na uwadze, że rozkład drgań na powierzchni kadłuba, a także warunki propagacji fal akustycznych w morzu płytkim są procesami nieliniowymi, zależnymi od wielu czynników, wnioski oparto głównie na wieloletnich badaniach prowadzonych w warunkach naturalnych.

3

Sound intensity distribution as an underwater acoustic investigation process

63%

Gloza I. , Buszman K.

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2014

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tom Vol. 17

57--62

EN

The subject matter of this research is underwater noise generated by sailing vessels in shallow seas. The classical method for measurement of underwater noise involves measuring effective acoustic pressure and fits for purposes in the free far field of the source. Despite its popularity, the method does have some significant limitations. Investigations of underwater noise generated by moving vessels in shallow seas are almost solely confined to the near field. In addition, this has a high level of interference and numerous wave reflections. This is why, as well as using the acoustic pressure measurement method, a complementary method for measuring acoustic wave intensity is used increasingly often. The measurements were taken using an underwater measurement module equipped with a set of detectors. Submerged at 20m, the object moved along a designated trajectory at a preset speed (as determined by the parameters of the ship’s machinery). Because all of the on-board equipment generates ship-specific noise, additional measurements were taken of the vibrations generated by selected ship’s machines to identify those sources. If known, the distribution of the acoustic field from vessels helps to identify the characteristic frequencies generated by the ship’s equipment and machinery. The paper includes a comparison of acoustic wave intensity and acoustic pressure measurements taken under the same ambient conditions and over the same period.

4

Identyfikacja źródeł zaburzeń podwodnych okrętu z wykorzystaniem funkcji koherencji

63%

Baranowska A. , Gloza I.

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tom Vol. 83, nr 27

245-250

PL

W pracy przedstawiono metodę identyfikacji źródeł zaburzeń podwodnych okrętu. Badano wpływ pracy silników głównych oraz zespołu prądotwórczego na całkowity szum podwodny okrętu. Zaproponowana metoda koherencyjna pozwala z jednej strony na identyfikację źródeł zaburzeń, z drugiej zaś na określenie ich udziału w szumie okrętu. Znajomość źródeł szumu podwodnego okrętu może być pomocna między innymi przy opracowaniu metod ich tłumienia a tym samym minimalizacji szumu podwodnego okrętu. Wyniki przeprowadzonych badań znajdą zastosowanie w dalszych pracach dotyczących wpływu parametrów pracy urządzeń okrętowych na zaburzenia podwodne okrętu. Przedstawione w niniejszej pracy wyniki dotyczą badań zaburzeń hydroakustycznych pochodzących od okrętu na uwięzi. W przyszłości będą również przeprowadzenie badania dotyczące źródeł zaburzeń poruszającego się okrętu.

EN

The identification problem of the ship disturbance sources was studied in the paper. The paper presents the method of measurements and investigations. The investigations were carried out on the basis of the results of underwater ship noise and vibration measurements. Underwater ship noise was measured by hydrophone. To find the sources of noise, the level of vibration was measured by accelerometer. The analysis of underwater ship noise shows that the ship's diesel engine and auxiliary machinery are very important components of ship disturbance. Therefore the influence of these ship noise sources were considered. The coherence method was used to identify the ship disturbance sources.

5

Identification of hydro-acoustic waves emitted from floating units during mooring tests

51%

Kozaczka E. , Domagalski J. , Grelowska G. , Gloza I.

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nr 4

EN

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 associatedwith 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 [5, 7]. Vibration energy generated by the onboard devicesis transferred through ship structural elements to water where it propagates in the form of hydro-acoustic waves of a wide frequency band

6

The one – third – octave spectrum as a method of vessel identification

51%

Gloza I. , Józwiak R. , Buszman K.

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2014

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tom Vol. 17

63--68

EN

The subject of the examinations carried out is hydroacoustic noise in coastal zones. Under these conditions natural noise and the noise from moving vessels affect each other, as well as interference from industrial infrastructure located close to the coast. Both natural noise and noise caused by human activity affect the detection and identification of noise sources in these conditions. Experiments have been performed by the mobile measuring module in the Gulf of Gdansk. This showed that it can extract spectrum components, based on the results of underwater noise. These components allow the detection of moving objects. The collected database of measurements enabled the comparison of one-third-octave spectra of three different ships. The components specific to the type of vessel could extracted as a result of comparison. Consequently one of the three tested vessels could be identified.

7

Uncertainty analysis of the determination noise source direction using the tetrahedron hydrophone array

51%

Gloza I. , Józwiak R. , Pawlik P. , Bartko W.

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tom Vol. 18

59-68

EN

The analysis of the uncertainty of the determination of the noise source direction in the aquatic environment is presented in this paper. The type A uncertainty of the bearing algorithm was determined on the bases of multiple measurements of the hydroacoustic pressure by means of the TC4032 type hydrophones and the GPS device data. The influence of the non-linearity of the amplitude-frequency characteristic on the uncertainty of the determination of the noise source direction, was also described. The influence of water density, electromagnetic disturbances and irregular noises on the final uncertainty was determined. On the bases of the determined uncertainty components the uncertainty budget, of the determination of the angle showing the direction from which hydroacoustic waves are coming, was prepared.

8

Determination of the ship detection area in the coastal region

51%

Kozaczka E. , Grelowska G. , Gloza I.

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tom Vol. 1

169--172

EN

The paper presents the results of the investigations of the noise produced by ships at the background of ambient sea noise in the coastal region. It has been noticed that the ships' spectra can be classified into a few groups. The shape of the broad-band noise spectrum envelope has been chosen as the criterium of classification. The area in which the signal generated by a ship can be distinguished from the ambient noise has been preliminarily estimated.

9

Identification of hydro-acoustic waves emitted from floating units during mooring tests

51%

Kozaczka E. , Domagalski J. , Grelowska G. , Gloza I.

Polish Maritime Research

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2007

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tom nr 4

40-46

EN

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 [5, 7]. 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.

10

Pomiar dźwięków foki szarej

51%

Malinowski S. J. , Gloza I. , Domagalski J.

Hydroacoustics

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2000

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tom Vol. 3

177--182

EN

Animals produce a wide range of sounds that can travel at great distances underwater. During the presentation you will listen to the real hydrophone recordings which were made here in Hel. The paper & recordings present the results of sound imitated by grey seals. Signature sounds differ between the individuals. Seals have a well-developed sense of hearing, especially in the water. In the air, their hearing ability is greatly reduced. They have large eyes and their underwater vision is better than a human 's, but even blind mammals are healthy, because the most important sense in the water is hearing, Researchers know that seals have an acute sense of smell on land. This sense is important for mothers identifying their pups. The results of the measurements show that the sound intensity method is worth using, especially in pools , shallow water, and to identify and find the direction of a sound source.

11

The character of underwater noise radiated by small vessels

51%

Malinowski S. J. , Gloza I. , Domagalski J.

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tom Vol. 4

161--164

EN

This paper presents an overview of our initiatives for underwater noise measurements and their acoustic characteristics, which years ago have been applied. Different kinds of surface ships and more importantly submarines radiate high levels of underwater noise which can be detected and tracked by passive sonars. Hostile navies use these signatures for detection and classification of targets. In many cases, not only a vessel as a specific class of warship, but also even the individual ship within a concrete class can be positively identified. The method of narrow-band filtration of the spectrum' s discrete lines at frequencies up to several H: is the basic standard of passive systems for long-distance detection. To find the source of noise, the level of vibration was also measured by accelerometers. Ship' s very own distinctive acoustic signature radiated at discrete frequencies, excited by the machinery, is easily detected and must be decreased as much as possible. Coherence between underwater sound pressure from a moving vessel and vibration during the same run was made.

12

Struktura pola akustycznego szumów podwodnych jednostki pływającej w polu bliskim

51%

Gloza I. , Dobrzeniecki J. , Domagalski J.

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tom Vol. 83, nr 27

269-274

EN

Investigations of acoustical field structure of the underwater ship noise in the near field are presented in the paper. These investigations were done for the purpose ship classification.

13

Underwater noise radiated by ships, their propulsion and auxiliary machinery, and propellers

51%

Malinowski S. J. , Gloza I. , Domagalski J.

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tom Vol. 4

165--168

EN

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 of 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 vibration 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 of the hull are determining issues in the radiation of 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 instruments and analogue recorders were used by us.