JP2911258B2 - Underwater parametric low frequency sound source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater parametric low frequency sound source provided on a moving body such as a ship and radiating sound waves of a predetermined frequency into water by a parametric transmission system.

[0002]

2. Description of the Related Art Normally, a low-frequency sound source of a linear transmission system has a large sound source weight and is difficult to miniaturize. On the other hand, a parametric transmission using a non-linear system can easily reduce the size and weight of a transmitter. There is an advantage that it becomes.

[0003] This non-linear parametric transmission is
It generates a low-frequency secondary wave from a high-frequency primary wave due to the nonlinearity of the medium in the propagation region, and is shown in, for example, Japanese Utility Model Publication No. 1-40069.

[0004]

In a conventional low-frequency sound source (parametric low-frequency sound source) using a transmitter of a parametric transmission system, as described in the above publication, the electro-acoustic conversion efficiency, that is, 1 unit. There is a problem that the conversion efficiency from the secondary wave to the secondary wave is low, and there is a disadvantage that the voltage for driving the sound source must be increased in order to increase the transmitted sound pressure of the secondary wave.

Further, the above publication discloses a device provided with a so-called bubble screen which uses air bubbles for the purpose of blocking the primary wave, but this screen only blocks the primary wave. It does not contribute to the improvement of the conversion efficiency from the primary wave to the secondary wave, and requires a large-scale generator of the bubble screen. Can not.

The present invention has been made in consideration of the above-mentioned problems of the prior art, and has as its object to radiate a secondary wave into water using a moving body such as a ship. A new underwater parametric low-frequency sound source that can be used to improve the efficiency of conversion from primary waves to secondary waves, further reduce the size, and add new members It is another object of the present invention to make it possible to easily adjust the characteristics without any difficulty, and to emit a secondary wave into water with desired characteristics.

[0007]

In order to achieve the above object, in the underwater parametric low-frequency sound source of the present invention, a parametric transmission type transmitter for generating a primary wave is provided to a moving body, and A sound propagation medium positioned between the transmitter and the wall of the moving body and forming a propagation path of the radiated sound of the transmitter;
A secondary wave sound source, which is made of a urethane resin or silicon resin material containing bubbles that are arranged on the propagation path of the radiation sound wave and vibrate by the radiation sound wave to generate a secondary wave having a lower frequency than the radiation sound wave; Solidified 2 to form
A second wave generation layer, and a polymer material property adjusting material that is contained in the second wave generation layer and that adjusts sound velocity and density properties;
A secondary wave is radiated into the water through the moving body wall.

[0008]

In the underwater parametric low-frequency sound source of the present invention having the above-described structure, the sound wave (primary wave) emitted from the transmitter serving as a sounding body is transmitted by the sound wave propagation medium and the secondary wave generation layer. At this time, when the primary wave propagates to the bubbles in the secondary wave generation layer, bubble vibration is actively generated due to nonlinearity in the respiratory motion of the bubble, and this bubble vibration is generated by the secondary wave. It greatly contributes to generation.

That is, the secondary wave generation layer has a function of limiting the finite length of the parametric array, but not only has a function of blocking (attenuating) the primary wave, but also has a function of newly converting the primary wave by the bubble vibration. A secondary wave is generated to form a secondary wave sound source.

Therefore, a secondary wave is actively formed from the primary wave by the secondary wave generation layer, and the secondary wave is generated by only two times as compared with the case where the secondary wave is passively generated only depending on the nonlinearity of the medium. The order of the next wave is remarkably increased, and the conversion efficiency from the primary wave to the secondary wave can be improved. As a result, the drive voltage of the transmitter can be made lower than before so that the size can be reduced.

Next, characteristics such as directivity control and array length (secondary wave generation distance) control are adjusted by adjusting the thickness, size, physical properties (sound speed, density) and the like of the secondary wave generation layer. I can do it.

According to the present invention, the secondary wave generating layer contains a property adjusting material, and the adjusting material can freely and easily adjust the properties of the secondary wave generating layer such as the physical properties described above,
By this adjustment, the secondary wave generation layer does not impair the broadband property of the parametric transmission, and the broadband of the sound source can be performed.

For this reason, the characteristics of the secondary wave generation layer and the sound wave propagation medium are adjusted to easily make the directional characteristics and the like of the secondary waves into desired characteristics, and the secondary waves are efficiently radiated into water with the desired characteristics. be able to.

Since the secondary wave generation layer is solidified, it can be used in a moving body such as a ship to emit a secondary wave having desired characteristics at a frequency lower than that of the primary wave into water. Thus, it is possible to provide a novel underwater parametric low frequency sound source having excellent characteristics.

[0015]

Embodiments will be described with reference to the drawings. FIG.
1 shows a characteristic configuration of an underwater parametric low-frequency sound source according to the present invention, and 1 is a transmitter of a parametric transmission system for generating a primary wave, which simultaneously transmits primary waves of slightly different two frequencies. And is molded in the mold layer 2 here.

Reference numeral 3 denotes a solidified secondary wave generation layer disposed on the radiation path of the sound wave from the transmitter 1, and is a group of bubbles having a certain range of diameters determined by the frequency used in the urethane resin or silicon resin material. (Bubble group)
This resin is formed by incorporating a property adjusting material of a polymer material for adjusting the physical properties of sound speed and density.

FIG. 3 shows an actual measurement example in which the underwater parametric low-frequency sound source having the configuration of FIG. 1 is used as the low-frequency sound source A. When the observation distance h from the low-frequency sound source A is 1 m, the distance from the sound axis B is assumed. When the secondary wave sound pressure at the lateral movement distance 1 was measured,
The result as shown in FIG. 4 was obtained.

FIG. 1 shows a low-frequency sound source A as a sound source of an embodiment,
The sound source having a configuration in which the secondary wave generation layer 3 is omitted from the sound source is used as a conventional sound source, and the measurement results of the respective secondary waves are compared. As is clear from FIG. It was confirmed that the embodiment having the above-mentioned structure improved the conversion efficiency of the secondary wave by about 20 dB as compared with the conventional example having no such structure. In this example, the primary wave is about 186 KHz, and the secondary wave is 20 KHz.

FIG. 2 shows an embodiment of an underwater parametric low frequency sound source according to the present invention when the moving object is a ship. In FIG. 1, a transmitter 1 is provided near a ship bottom 4 as a moving body wall, and a sound wave propagation medium 5 is provided between the wave transmitter 1 and the ship bottom 4. A propagation path of the radiation sound wave (primary wave) of the vessel 1 is formed. Castor oil is preferred as the sound wave propagation medium 5. Further, a secondary wave generation layer 3 is disposed at the bottom of the ship along the propagation path of the radiation sound wave.

Then, the radiated sound wave of the transmitter 1 propagates to the secondary wave generation layer 3 and the bubbles in the layer 3 vibrate. Due to the nonlinearity of the vibration, a secondary wave having a lower frequency than the primary wave is generated. The newly generated secondary wave remarkably increases as compared with the case where the secondary wave is passively generated only depending on the nonlinearity of the medium, and the primary wave is efficiently converted to the secondary wave.

Further, the sound wave velocity and density of the sound wave propagation path of the sound wave propagation medium 5 are adjusted by the characteristic adjusting material contained in the sound wave propagation medium 5, and the directivity of the propagation is adjusted. It is possible to freely and easily adjust characteristics such as the length and the array length.

By this adjustment, it is possible to broaden the sound source so that the secondary wave generation layer 3 does not impair the broadband property of the parametric transmission, and adjust the array length to adjust the secondary wave. Can be shortened.

Since the characteristics of the sound source including the secondary wave generation layer 3 can be easily made to the desired characteristics by the above adjustment, the secondary wave having the desired characteristics is radiated from the bottom 4 into the water. Can be.

Since the secondary wave generation layer 3 is solidified and formed in a small size, it can be easily applied to ships or various underwater vehicles.

[0025]

Since the present invention is configured as described above, it has the following effects. Mobile 1
The radiated sound wave (primary wave) of the transmitter 1 oscillates on the propagation path of the radiated sound wave composed of the sound wave propagation medium located between the transmitter 1 for generating the next wave and the moving body wall. Since the solidified secondary wave generation layer 3 made of a urethane resin or silicon resin material containing bubbles and generating a low frequency secondary wave and forming a sound source of the secondary wave is arranged, the transmitter 1 When the primary wave (radiated sound wave) is transmitted to the bubbles in the secondary wave generation layer 3, the bubble vibration is actively generated due to the non-linearity in the respiratory motion of the bubble, and this bubble vibration causes the generation of the secondary wave. Contribute greatly.

That is, the secondary wave generation layer 3 not only has a function of blocking (attenuating) the primary wave, but also newly generates a secondary wave from the primary wave by the bubble vibration, and generates a secondary wave sound source. To form

Therefore, the secondary wave can be positively formed by the secondary wave generation layer 3 from the primary wave, and the secondary wave is passively generated only depending on the nonlinearity of the medium. As a result, the secondary wave is significantly increased, and the conversion efficiency from the primary wave to the secondary wave can be improved.
Can be downsized by lowering the driving voltage than before, and a small and lightweight underwater parametric low-frequency sound source can be obtained.

Furthermore, since the secondary wave generation layer 3 contains a polymer material property adjusting material, the sound speed and density of the secondary wave generating layer 3 and thus the sound wave propagation medium 5 are adjusted by this adjusting material to propagate the material. The characteristics such as the directivity and the array length can be freely and easily adjusted.
Makes it possible to broaden the sound source without deteriorating the broadband characteristics of the parametric transmission, so that the characteristics of the secondary wave generation layer 3 and the sound propagation medium 5 can be easily set to desired characteristics. Secondary waves can be radiated into water with desired characteristics.

Since the secondary wave generation layer 3 is solidified, a new small-sized underwater having excellent characteristics can emit a secondary wave having desired characteristics at a lower frequency than the primary wave into the water. For providing a parametric low frequency sound source. Further, castor oil is preferable as the sound wave propagation medium 5,
A better effect can be expected.

[Brief description of the drawings]

FIG. 1 is a cutaway front view illustrating a characteristic configuration of the present invention.

FIG. 2 is a cutaway front view of one embodiment of the present invention.

FIG. 3 is an explanatory diagram of an actual measurement example of the low frequency sound source of FIG. 1;

FIG. 4 is a characteristic diagram of a secondary sound pressure showing the measurement result of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitter 3 Secondary wave generation layer 5 Sound propagation medium

Continuation of the front page (72) Inventor Yoshiaki Watanabe 601 Karasuma Higashiiribu-cho, Imadegawa-dori, Kamigyo-ku, Kyoto Inside the Doshisha University Faculty of Engineering (72) Inventor Akiharu Kitamura 5-28 Nishikujo, Konohana-ku, Osaka-shi Inside Hitachi Construction & Shipbuilding Co., Ltd. (72) Inventor Akira Ogura 5-28 Nishikujo, Konohana-ku, Osaka City Inside Hitachi Construction & Shipbuilding Co., Ltd. (56) References JP-A-62-200998 (JP, A)

Claims (2)

(57) [Claims] To 1. A moving body, the wave transmitter parametric transmitting scheme for primary wave generating, located between the wave transmitter and moving body wall, the propagation path of the radiation waves of the transmitters and Ruoto wave propagation medium quality to form, are arranged in the propagation path before Symbol radiation waves, the urethane resin containing bubbles group to generate a second-order wave of lower frequency than the radiation waves to vibrate by the radiation waves or It consists silicone down tree fat material, and the secondary wave solidified second wave generation layer to form a source of, contained in the second wave generation layer, a polymer for adjusting the sound velocity, the density characteristics underwater parametric low-frequency sound, characterized in that a wood charge properties adjusting material, which emits the second wave in the water through the mobile wall. 2. The method according to claim 1, wherein the sound propagation medium comprises castor oil.
The underwater parametric low frequency according to claim 1, characterized in that:
sound source.