JPS6044836A - Method and apparatus for detecting underwater noise of ship - Google Patents

Abstract

PURPOSE:To detect the underwater noises in the vicinity of the outer plating of the bottom of a ship, by forming an inverted funnel shaped space in the inner side of the outer plating of the bottom of the ship, filling a liquid, whose intrinsic acoustic impedance is equal to the external water, in the space, preventing the vibration of the hull to said liquid, and using an underwater microphone, which is inserted in the space. CONSTITUTION:In order to detect underwater noises, at first, liquid L, whose intrinsic acoustic impedance becomes equal to outer water (sea water), e,g., sea water, castor oil, or the like, is injected in an inverted funnel shaped space 3, which is formed by a main body 1 of a device of a detecting apparatus S at the inner side of an outer plating 2 of a hull. Then, only the underwater radiation noises in the vicinity of the apparatus S are transmitted to the liquid L in inspection. At this time, the vibration of the hull of the ship is absorbed by a vibration controlling member 4. Therefore, only the underwater radiation noises are transmitted without attenuation. The underwater radiation noises transmitted to the liquid L are propagated to an underwater microphone 5, which is provided in the space 3 without resistance, and the noises can be detected efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting underwater noise on a ship.

In the conventional measurement of underwater sound in ships, a device for measuring underwater radiation noise of own ship has not yet been provided.

Therefore, conventionally, the underwater radiation noise of ships has been measured by other ships specialized in measurement, but with such conventional measurement methods, the measurement work is extensive and the measured data does not cover the entire area of the own ship. There is a problem in that the underwater radiation noise emitted from each piece of equipment cannot be measured because they overlap.

The present invention aims to solve these problems, and aims to provide a method and device for detecting underwater noise on a ship, which allows underwater radiation noise to be easily detected on the own ship. do.

For this reason, the method for detecting underwater noise in a ship of the present invention involves forming an inverted funnel-shaped cavity inside the bottom skin of the ship, and injecting a liquid whose specific acoustic impedance is equal to that of the outside water into the cavity. In addition, after preventing the propagation of hull vibrations to the liquid, underwater noise in the vicinity of the bottom shell plate is detected by an underwater microphone inserted into the cavity.

Further, the underwater noise detection device for a ship of the present invention includes a device main body that forms an inverted funnel-shaped cavity inside the bottom skin of the ship, and a liquid inlet that is connected to the upper end of the cavity. and an air vent, and an underwater microphone disposed so that its head protrudes into the cavity, and the lower peripheral edge of the cavity is attached to the inside of the hull shell plate through a rubber packing, and the It is characterized in that a dividing material covering the lower end opening of the void space is adhered to the inside of the bottom outer plate.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
1 to 4 show a means for carrying out an underwater noise detection method for a ship and an underwater noise detection device for a ship as an embodiment of the present invention, and FIG. 1 is a schematic diagram of a ship showing the arrangement thereof; FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a sectional view taken along the line ■-■ in FIG. 2, and FIG. 4 is a schematic diagram showing a modification thereof.

As shown in FIGS. 1 to 3, a donut-shaped seat plate 11 is fixed to the inside of the hull outer plate 2 by welding or the like.
A plurality of stud bolts 12 are attached to the upper surface of.

On the seat plate 11, the device main body 1, which has an oblong hole in the upper part and a hole shape in the lower part as shown in FIG. 3, is attached via a rubber gasket 11a, and a rubber washer 1
4. Washer 15. Tightening is fixed by a stud bolt 12 and a nut 13, and an inverted funnel-shaped cavity (measuring part) 3 is formed.

A liquid inlet 6, a stopcock 6a, and an air vent 7 are provided at the upper end of the device main body 1 so as to be connected to the upper end of the cavity 3, and the pressure inside the cavity 3 is kept constant. It is designed to play the role of keeping the

Further, an underwater microphone 5 is mounted on the upper part of the main body 1 of the apparatus, and a bushing 8. Sleeve 9. It is mounted horizontally via a tightening gland 10 so that its head protrudes into the cavity (measuring section) 3.

On the other hand, at the lower end of the space 3 formed inside the device main body 1, a plate-shaped dividing material 4 that covers the lower end opening of the space 3 is attached to the inside of the hull outer plate 2 with adhesive. has been done.

The detection device S configured in this way is arranged at each measurement target position on the hull outer plate 2, as shown in FIG.

The means for implementing the underwater noise detection method for a ship of the present invention and the underwater noise detection device for a ship as an embodiment are configured as described above, so in order to detect underwater noise of a ship, first, A liquid such as seawater or castor oil, for example, such as seawater or castor oil, is injected into the inverted funnel-shaped space 3 formed inside the device 2 by the device body 1 so that the specific acoustic impedance is equal to that of the outside water (seawater).

In this state, only underwater radiation noise in the open water near the device is transmitted to the liquid tank.

That is, since the hull vibration of the ship is absorbed by the allocation material 4, only the underwater radiation noise is transmitted without being attenuated.

Underwater radiation noise near the bottom shell plate transmitted to the liquid is detected by the underwater microphone 5 provided so as to protrude from the upper part of the cavity 3.

During this detection, since the acoustic impedance of the liquid is equal to that of the outside water, the noise is propagated to the underwater microphone 5 without resistance, and underwater radiation noise is efficiently detected.

Note that the underwater noise detection method for ships according to the present invention is applicable to
A hull inner shell 16 and a hull outer shell 17 as shown in the figure.
If the gap 18 is filled with a liquid such as seawater with almost no flow (for example, in a submersible), this can be implemented by installing the underwater microphone 5 in the gap 18. It is also possible to efficiently measure underwater sound.

As detailed above, according to the underwater noise detection method for a ship of the present invention, an inverted funnel-shaped cavity is formed inside the bottom skin of the ship, and the specific acoustic impedance of the cavity is made equal to that of the open water. By a simple means of injecting a liquid such as this, preventing the propagation of hull vibration to the liquid, and then detecting underwater noise in the vicinity of the bottom shell plate using an underwater microphone inserted into the cavity, It has the following effects or advantages.

(1) It becomes possible to efficiently detect the own ship's underwater radiation noise individually with a simple structure.

(2) By using rubber packing and damping material, underwater radiation noise of own ship can be detected efficiently without being affected by ship vibration.

(3) The shape of the cavity (measuring part) is shaped like an inverted funnel (wide tip), so the directivity toward the detection target is strong, and the underwater radiation noise of own ship at a specific position is efficiently suppressed. Becomes detectable.

Further, according to the underwater noise detection device for a ship of the present invention, the device body is provided to form an inverted funnel-shaped cavity inside the bottom shell plate, and a liquid is provided so as to be connected to the upper end of the cavity. An underwater microphone is provided with an inlet, an air vent, and an underwater microphone disposed so that its head protrudes into the cavity, and the lower peripheral edge of the cavity is attached to the inside of the hull shell plate via a rubber gasket. The detection method of the present invention can be easily and reliably realized with a simple configuration in which a damping material covering the lower end of the void +111 opening is attached to the inside of the bottom shell plate. This has the advantage of efficiently detecting underwater radiated noise.

[Brief explanation of the drawing]

1 to 4 show a means for carrying out an underwater noise detection method for a ship and an underwater noise detection device for a ship as an embodiment of the present invention, and FIG. 1 is a schematic diagram of a ship showing the arrangement thereof; FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a sectional view taken along the line ■-■ in FIG. 2, and FIG. 4 is a schematic diagram showing a modification thereof. 1. Equipment main body, 2. Hull shell, 3. Vacant space, 4.
Damping material, 5. Underwater microphone, 6. Liquid inlet, 6a. Liquid inlet stopper, 7. Air vent, 8.
Bushing, 9... Sleeve, 10... Tightening gland, 1
1.mLi1a..Rubber gasket, 12..Installation port), 13..Nut, 14..Rubber washer, 15..
Washer +, 16...Hull inner shell, Noah...Hull outer shell, 18
...Gap, L...Liquid, S...Detection device. Sub-Agent Patent Attorney Yoshihiko Iinuma Figure 1 Figure 3

Claims (2)

[Claims] (1) An inverted funnel-shaped cavity is formed inside the bottom shell plate, and a liquid whose specific acoustic impedance is equal to that of the outside water is injected into the cavity, and the propagation of hull vibrations to the liquid is prevented. A method for detecting underwater noise in a ship, comprising: detecting underwater noise in the vicinity of the bottom shell plate using an underwater microphone inserted into the cavity. (2) A device body is provided that forms an inverted funnel-shaped cavity inside the bottom shell, and a liquid inlet and an air vent are provided to connect to the upper end of the cavity, and a head is provided into the cavity. an underwater microphone disposed so as to protrude from the bottom; the bottom peripheral edge of the space is attached to the inside of the hull shell plate via a rubber seal, and a damping material covers the bottom opening of the space. An underwater noise detection device for a ship, characterized in that: is attached to the inside of the bottom outer plate of the ship.