JPH0326465Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is based on three methods for measuring underwater noise of ships.
This invention relates to a dimensional underwater acoustic intensity measuring device.

[Conventional technology and its problems]

Whereas the conventional sound pressure measurement method evaluates the sound source by measuring only the intensity of the sound, the sound intensity method directly measures the energy flow and evaluates the sound source from its intensity and direction. It is characterized by being able to accurately analyze sound field information.

By using this method to measure a suitable surface surrounding a sound source and finding the sound intensity distribution on that surface, you can know the radiation state of the sound source and the radiation power of the sound source.
Furthermore, by measuring the space in which sound is radiated, it is possible to know the state of sound propagation.

By the way, as shown in Fig. 10, underwater noise measurement of ships at anchor, which has been widely adopted in the past, involves suspending a plurality of hydrophones (underwater sound receivers) 51 from the side 50 and measuring the sound at each point. The pressure is measured to evaluate the sound source level and directional characteristics.

The hydrophone 51 is covered with a cover 52, as shown in FIG. 11, and a weight 55 is suspended from the lower end of the cover 52 via a rope 53.

In the underwater noise measurement of the above-mentioned ships, the directivity of the sound source,
The sound field becomes complex due to the effects of reflections from the sea surface and propagation characteristics of the sea area. For this reason, it is difficult to evaluate sound source characteristics based only on the intensity of the sound.

Therefore, it is conceivable to apply the above acoustic intensity method, which focuses on the energy flow from the sound source, to underwater noise measurement. However, the sound intensity method evaluates the sound source based on the intensity and direction of the sound, and for this purpose, it is necessary to accurately set the positional relationship between the sound source and the measurement point and the measurement direction. Therefore, when applying the intensity method for air sound, in which the measurement point can be easily fixed and moved, to underwater noise measurement, the intensity measurement device is easily shaken by waves, and the positional relationship between the sound source and the measurement point, Another problem was that it was difficult to accurately set the measurement direction.

To explain the sound intensity method here, the sound intensity is determined by the sound pressure p and particle velocity v
It is expressed as the product pv, and is a vector quantity indicating the flow of acoustic energy at an arbitrary position.

As a method of measuring one-dimensional intensity, a method using two microphones located close to each other is known. This calculates the sound pressure gradient of two microphones in close proximity, and measures the particle velocity from the relationship of Euler's equation. This particle velocity is determined by the two microphones 56 and 5 as shown in FIG.
In this figure, when an intensity vector exists, the direction cosine component toward the probe axis 60
_x is measured and is expressed as _x = | | cos α.
Here || represents the magnitude of the intensity vector, and α is the direction of the vector.

In order to extend this to the measurement of intensity vectors on a plane, intensity measurements may be performed on two orthogonal axes components to obtain the X and Y components of the intensity vectors. In the orthogonal coordinate system shown in Figure 13, vector components of the X axis are _x , Y
If the vector component of the axis is _y , the magnitude of the resultant vector is ||, and its direction is α, the resultant vector is ||=√ ^z + ^z , α=tan ^- (y/x)
It can be easily determined from the relationship. In addition, in FIG. 13, 61, 62, and 63 are microphones.

Furthermore, in order to extend the measurement of intensity vectors in three dimensions (space), it is necessary to
It is sufficient to measure each axis component of the intensity vector with respect to the axis and the Z axis. In the orthogonal coordinate system shown in Figure 14, the vector component of the X axis _{is x} , the vector component of the Y axis is _y , the vector component of the Z axis is _z , the magnitude of the composite vector is ||, and the composite vector is projected onto the XY plane. The angle that the composite vector xy of the Y-axis component and the Y-axis component made with the X-axis is α,
If the angle between the composite vector and composite vector xy is β, the composite vector is =√ ^z + ^z + ^z , α=tan ^- (y/
x), β=tan ^- (z/√ ^z + ^z ). In addition, in Fig. 14, 6
5, 66, 68, and 69 are microphones.

Figure 15 shows the principle of a conventional sound intensity measurement device using a three-dimensional intensity probe. Microphones 65, 66, 68, and 69 are set at the origin O, which is the coordinate, and the X, Y, and Z axes, respectively.The probe axis of the microphone 65 is set at the origin O, and each probe of the microphones 66, 68, and 69 The axes are arranged to coincide with the X, Y, and Z axes, respectively.

For example, as shown in FIGS. 16 and 17, four microphones 70, 71, 72, and 73 are mounted on a support base 76 fixed to a support leg 75 at the origin of the probe and along the X, Y, and Z axes. With a sound intensity measuring device arranged in three dimensions, it is easy to align the coordinate axes with the probe axis during measurement, but the direction of the sound receiving surface of the microphone between the origin and the X axis, the origin and the Y axis, and the origin If the directions of the microphone's sound receiving surface on the and Z-axes are not aligned, the microphone's directivity characteristics at high frequencies will differ, so the characteristics of sound waves incident on the X- and Y-axes will be different from the characteristics of sound waves incident on the Z-axis. However, there was a problem that measurement errors occurred.

This invention was devised to solve the above problems, and its purpose is to ensure that the measurement device is fixed and the direction of the coordinate axes is accurately set when measuring underwater noise using the intensity measurement method. An object of the present invention is to provide a three-dimensional underwater acoustic intensity measuring device that can be easily operated and moved.

[Means for solving problems]

In order to achieve the above object, the three-dimensional underwater acoustic intensity measuring device of the present invention has the horizontal direction of a T-shaped flat plate as the Y axis, and three pipes are arranged in a straight line on this Y axis. Then, on a T-shaped flat plate, attach the pipe in the center in a direction perpendicular to the Y axis.
Arrange the book, stand it up perpendicular to the T-shaped flat plate so that each of the four pipes is parallel, insert a cylindrical hydrophone at the tip of each pipe, and use the central hydrophone to listen to the sound. The center is the acoustic origin, Y
The acoustic center of one of the other two hydrophones on the axis is the acoustic X axis, the acoustic center of the other hydrophone is the acoustic Y axis, and the acoustic center of the hydrophone perpendicular to the Y axis is placed so that it passes through the acoustic Z axis,
The angle between the X axis and the center line of the hydrophone passing through the X axis is 45° clockwise around the Z axis, and the angle between the Y axis and the center line of the hydrophone passing through the Y axis is Z.
45 degrees counterclockwise around the axis, the distance between the hydrophone at the origin and the hydrophone passing through the Z axis, the distance between the hydrophone at the origin and the hydrophone passing through the X axis, and the distance between the hydrophone at the origin and the hydrophone passing through the Y axis. The spacing between the hydrophones passing through the axis was equal.

[Effect]

According to the above configuration, mutual interference between the sound fields incident on the X-axis and the Y-axis becomes symmetrical, and the directivity of the hydrophone can be eliminated. In addition, the measurement point is fixed and the direction of the coordinate axis is set with high precision, and the measurement device does not swing due to waves, so the measurement point does not move and the distance between the sound source and the measurement point is always maintained constant. Ru.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

A three-dimensional underwater acoustic intensity measuring device 1 according to the present invention includes a three-dimensional intensity probe 2.
and a hydrophone stand 3.

As shown in FIGS. 1 to 3, the three-dimensional intensity probe 2 has pipes 6A, 6B, 6D, and 6E installed upright on a support base 5 and having notches 9A, 9B, 9C, 9D, and 9E. It consists of hydrophones 8A, 8B, 8D, and 8E each inserted into the
The acoustic centers O _A , O _B , O _D , and O _E of D and 8E are arranged so as to be located on the origin O and the X, Y, and Z axes. A notch 5a and a pin hole 5b for attachment to the hydrophone stand 3 are formed at one end of the support base 5.

As shown in FIGS. 4, 5, and 8, the hydrophone stand 3 is formed of a stainless steel pipe 11 whose outer periphery is surrounded by porous rubber 10, and a triangular truss structure bottom 12. , an upright part 13 standing upright from each apex of the bottom part 12 , a connecting part 15 connecting the top of each upright part 13 , and a probe integrally formed in the connecting part 15 so as to stand upright toward the bottom part 12 . It consists of a mounting part 16. A support stand 5 for the probe 2 is attached, and in this case, the X, Y, and Z axes shown in FIGS. 4 and 5 coincide with the probe axis of the three-dimensional intensity probe 2. It is set as follows.

Attachment portions 18 stand upright from each vertex of the bottom portion 12 of the hydrophone stand 3 in the opposite direction to the upright portion 13
As shown in FIG. 6, a universal joint 20 is attached to the hull outer plate 21.
(See Figure 7) Magnetic base 2 is attracted to
2 via vibration isolating rubber 23.

As shown in Figures 7 and 9, the hull marking 2 is placed at the position corresponding to the intensity measurement position.
5 is displayed, marking points 25A, 25
B, 25D is the bottom part 1 of the hydrophone stand 3
It is arranged to face the vertices 12A, 12B, and 12D of 2. In FIG. 9, L-1 is the center of the hydrostand 3, that is, the measurement point.

A three-dimensional intensity probe 2 fixed to a hydrophone stand 3 attached to a hull outer plate 21 is connected to a measurement chamber 31 of a measurement vessel 30 by a hydrophone cable 32, as shown in FIG.

Next, the operation of the embodiment of the present invention will be explained.

Hull markings are performed when the dog enters the ship, and at the time of measurement, a diver fixes a hydrophone stand 3 with a three-dimensional intensity probe 2 attached to the hull marking 25 position using a magnetic base 22. This allows the measurement point to be fixed and the direction of the coordinate axes to be set with high precision.The measurement device does not move due to waves, so the measurement point does not move, and the sound source and measurement point can always be equidistant. . Further, since the hull marking 25 is displayed on the hull, attachment of the hydrophone stand 3 becomes easy.

The three-dimensional intensity probe 2 is constructed so that it can be easily assembled to align with the acoustic center by simply inserting a commercially available hydrophone 8 into the pipe 6 without interfering with the hydrophone cable 31 using a pipe 6 with a notch 9. is simple and inexpensive.
The spacing between hydrophones 8A, 8B, 8D, and 8E is
Since the accuracy is determined by the accuracy of the mounting positions of the pipes 6A, 6B, 6D, and 6E, high accuracy can be achieved through normal processing. Further, since the hydrophone 8 mounting portion has a pipe structure and has no protrusions, there is little disturbance in the sound field near the hydrophone 8. Further, mutual interference between the sound fields incident on the X-axis and the Y-axis is symmetrical.

The main structure of the hydrophone stand 3 is made of a stainless steel pipe 11, and the bottom part 12 has a triangular truss structure, so it is lightweight and has high rigidity. In addition, the porous rubber 10 surrounding the outer periphery of the stainless steel pipe 11 provides buoyancy and absorbs sound, thereby reducing the influence of reflected waves from the hydrostand 3 structure disturbing the sound field near the three-dimensional intensity probe 2. There is. The hydrophone stand 3 is attached to the hull outer plate 21 using a magnetic base 22 and a universal joint 20, and can be easily attached even if the hull outer plate 21 has a curvature. Further, the vibration of the ship body is absorbed by the anti-vibration rubber 23 and is not transmitted to the hydrophone stand 3.

[Effect of idea]

As mentioned above, according to the present invention, underwater noise is measured by attaching and detaching a hydrophone stand to which a three-dimensional intensity probe using a commercially available hydrophone is fixed, so that underwater noise can be measured easily by waves. Since the measurement device does not move, the measurement point does not move, making it possible to measure underwater noise with high accuracy. Furthermore, the structure is simple and costs can be significantly reduced.

[Brief explanation of drawings]

1 to 9 relate to an embodiment of the present invention, in which FIG. 1 is a schematic front view of a three-dimensional intensity probe, FIG. 2 is a side view taken in the direction of the arrow in FIG. 1, and FIG. Fig. 4 is a front view of the hydrophone stand, Fig. 5 is a plan view as seen from the arrow in Fig. 4,
Figure 6 is a front view showing the installed state of the hydrophone stand, Figure 7 is a perspective view of a measurement vessel equipped with the device according to the present invention, and Figure 8 is a perspective view of the hydrophone stand fixed at the hull marking position. , No. 9
The figure is a front view of the hull markings, Figure 10 is a perspective view of the vessel equipped with a hydrophone, and Figure 11 is a front view of the hull markings.
An enlarged view of part A in Figure 0, Figure 12 is a vector diagram of the one-dimensional sound intensity method, Figure 13 is a vector diagram of the two-dimensional sound intensity method, Figure 14 is a vector diagram of the three-dimensional sound intensity method, FIG. 15 is a principle diagram of a conventional three-dimensional sound intensity measuring device, FIG. 16 is a front view of another conventional three-dimensional sound intensity measuring device, and FIG.
2 is a side view of what is shown in the figure; FIG. 1... Three-dimensional underwater acoustic intensity measuring device, 2... Three-dimensional intensity probe, 3...
...Hydrophone stand, 8A, 8B, 8D, 8
E...Hydrophone, 21...Hull shell, 30...
...Ship, 0...Origin.

Claims (1)

[Scope of utility model registration request] The horizontal direction of the T-shaped flat plate is the Y-axis, and the three pipes are arranged in a straight line on this Y-axis, and the central pipe is placed in the direction perpendicular to the Y-axis on the T-shaped flat plate. Place one of the four pipes in parallel and perpendicular to the T-shaped flat plate, insert a cylindrical hydrophone into the tip of each pipe, and insert the cylindrical hydrophone into the center hydrophone. The acoustic center of the hydrophone is the acoustic origin, the acoustic center of one of the other two hydrophones on the Y axis is the acoustic X axis, and the acoustic center of the other hydrophone is the acoustic Y axis. , the acoustic center of the hydrophone perpendicular to the Y-axis is placed so as to pass through the acoustic Z-axis, and the angle between the X-axis and the center line of the hydrophone passing through the X-axis is
The angle between the Y axis and the center line of the hydrophone passing through the Y axis is 45 degrees counterclockwise around the Z axis, and the distance between the hydrophone at the origin and the hydrophone passing through the Z axis is A three-dimensional underwater acoustic intensity measuring device in which the distance between the hydrophone at the origin and the hydrophone passing through the X-axis is equal, and the distance between the hydrophone at the origin and the hydrophone passing through the Y-axis is equal.