JP2006232050A - Method of shielding discharge water noise of ship, and device for shielding discharge water noise of ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of shielding discharge water noise of a ship, and a device for shielding discharge water noise of a ship, capable of shielding underwater noise generated from discharge water to outboard. <P>SOLUTION: By mixing micro babbles into the discharge water W discharged from the ship 1 to the outside, the underwater noise generated when the discharge water W is discharged into the water is sound-insulated by the micro bubbles mixed into the discharge water and supplied into the water. Mixed water Wb of the micro bubbles is supplied into at least a part around the discharge water W discharged from the ship 1 to the outside, thereby sound-insulating the underwater noise generated when the discharge water W is discharged into the water by the micro bubbles supplied into the water with the mixed water Wb. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ship that uses an acoustic sensor such as a marine observation ship to absorb and shield the underwater noise generated when water discharged outside the ship, such as equipment-cooled seawater, enters the water. The present invention relates to a method for shielding water discharge noise and a device for shielding water discharge noise from a ship.

  In the case of ships, when water discharged to the outside of the ship, such as equipment cooling seawater and fire extinguishing lines, is released on the surface of the water (hereinafter also referred to as sea, lake, etc.), the water surface (hereinafter referred to as sea level, lake level) If there is underwater noise in the vicinity, and if it is released into the water, the cavitation sound or motor sound of the pipe system riding on the pipe for discharge and the fluid in the pipe is released directly into the water. Cause underwater noise. In ordinary ships, even if this underwater noise occurs, there is no particular problem. There is a problem that accurate observation data cannot be obtained due to the influence of observation. In particular, when the ship is stopped, there is no underwater noise generated by the propulsion device, so this underwater noise due to the discharged water becomes conspicuous. Therefore, if the underwater noise generated from the water discharged to the outside of the ship can be shielded, the observation can be performed more accurately and efficiently.

  On the other hand, it is known that a bubbly fluid containing bubbles has sound absorption and sound insulation effects in water. In other words, the frequency with good absorption efficiency has a close relationship with the natural vibration frequency of bubbles, and when water and seawater contain bubbles, the specific gravity and elastic modulus change, the sound propagation speed decreases, and absorption loss Will increase. In addition, when the bubbles are mixed in water, they rise due to buoyancy and disappear on the surface of the water. However, when the bubbles become fine bubbles of about 10 μmφ to 100 μmφ called microbubbles and the bubble diameter becomes smaller, the levitation speed becomes slower and Disappears in a form absorbed by The lifetime of this microbubble is said to be 10 seconds to several tens of seconds, for example, in a seawater microbubble bar of about 10 μmφ to 40 μmφ.

And although it is not microbubbles, this bubble property is used to generate a group of bubbles from a bubble generator arranged so as to surround the sand pile, thereby reducing radiation noise caused by vibration of the sand pile steel pipe. Proposed a sand pile driving ship with noise prevention device, or proposed a side thruster device for a ship that reduces the radiation noise from the side thruster by injecting bubbles from the bubble blowing device with openings before and after the tunnel type side thruster (For example, see Patent Document 1 and Patent Document 2).
Japanese Utility Model Publication No. 01-119431 Japanese Utility Model Publication No. 03-40198

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a method for shielding the discharged water noise of a ship capable of shielding the underwater noise generated from the discharged water to the outside of the ship and the discharged water of the ship. It is to provide a noise shielding device.

  In order to achieve the above-mentioned object, the method of shielding the discharge water noise of the ship according to the present invention is generated when the discharge water is discharged into the water by mixing microbubbles into the discharge water discharged to the outside from the ship. The underwater noise is sound-insulated by the microbubbles mixed in the discharged water and supplied to the water.

  The “water” includes a wide variety of water such as seawater, river water and lake water. That is, “underwater” includes underwater, river, lake water, and the like. In addition, “released into water” includes the case where the discharged water released onto the water surface enters the water via the water surface and the case where it is released directly into the water.

  According to the above configuration, the microbubbles contained in the discharged water stay in the water without disappearing for a while, so the microbubbles spread as the discharged water spreads, and the discharged water can surround the part entering the water, Underwater noise generated when the discharged water enters the water can be absorbed and insulated.

  Alternatively, by supplying the microbubble mixed water to at least a part of the periphery of the discharged water discharged to the outside from the ship, the underwater noise generated when the discharged water is discharged into the water, together with the mixed water Sound insulation is provided by microbubbles supplied in water.

  According to this configuration, a pipe for supplying new microbubble mixed water is provided without processing the existing discharge pipe, and microbubbles are added to the discharge water by supplying the microbubble mixed water around the discharge water. Mixing or providing a wall of water mixed with microbubbles between the discharged water and the acoustic sensor can absorb and block underwater noise generated when the discharged water enters the water.

  In order to achieve the above-mentioned object, the ship discharge water noise shielding apparatus of the present invention comprises a microbubble mixing device for mixing microbubbles into the discharge water discharged to the outside from the ship. Alternatively, a microbubble mixed water supply device for supplying mixed water of microbubbles is provided around at least a part of the periphery of the discharged water discharged to the outside from the ship.

  The method for shielding the water discharge noise of the ship described above can be implemented by the ship water discharge noise shielding apparatus having these configurations.

  According to the method for shielding water discharge noise from a ship and the apparatus for shielding water discharge from a ship according to the present invention, the water discharged from the hull includes microbubbles or discharges microbubble mixed water around the discharge water. Thus, underwater noise generated from the discharged water can be shielded by the microbubbles, and adverse effects on the acoustic sensor and the like can be reduced.

  Embodiments of a method for shielding water discharge noise from a ship and a device for shielding water discharge from a ship according to the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 to 4, the ship 1 having the shielding apparatus 10 </ b> A for the discharged water noise of the ship according to the first embodiment is opened on the shore side 2 for discharging the discharged water W such as engine cooling seawater. A discharge pipe 3 having a portion 3a is provided. 1 and 2, the opening 3a is disposed on the water surface, and in FIGS. 3 and 4, the opening 3a is disposed below the water surface, that is, in water.

  A buffer tank 11 is provided in the middle of the discharge pipe 3, and the microbubble generator 12 provided in the buffer tank 11 causes the microbubble mixed water (typically that microbubbles are contained in black lines or portions). Wb is generated, the microbubble mixed water Wb is mixed into the discharged water W, and discharged together from the opening 3a on the heel side 2.

  1 and 3, the buffer tank 11 and the microbubble generator 12 are provided to generate microbubbles. However, the buffer tank 11 and the microbubble generator 12 are not provided as shown in FIGS. In addition, the microbubble mixing device 13 may be provided outside the discharge pipe 3 to produce the microbubble mixed water Wb, and then the microbubble mixed water Wb may be mixed into the discharge water W of the discharge pipe 3 by the mixing pipe 14.

  According to these configurations, the microbubbles are discharged into the water together with the discharged water W. The microbubbles do not disappear immediately and stay on the water surface from which the discharged water W is discharged or in the vicinity of the water. Due to the sound absorption effect and sound insulation effect of the accumulated microbubbles, the underwater noise generated when the discharged water W that is released one after another collides with the water surface or creates a vortex, or the sound that is riding on the discharge pipe 3 Absorbs and isolates underwater noise generated by being directly released into the water. Thereby, the influence of underwater noise on the acoustic sensor 4 mounted on the ship 1 can be reduced.

  Next, a second embodiment will be described. As shown in FIGS. 5-8, the ship 1 provided with the shielding apparatus 10B of the discharged water noise of the ship of 2nd Embodiment is opened by the shore side 2 for discharging | emitting discharged water W, such as engine cooling seawater. A discharge pipe 3 having a portion 3a is provided. Microbubbles that discharge the microbubble mixed water Wb produced by the microbubble mixing device 13 in the vicinity of the opening 3a of the discharge tube 3 or in the vicinity of the portion where the discharge water W discharged from the discharge tube 3 collides with the water surface. A discharge pipe 15 is provided. 5 and 7 show the case where the opening 15a of the microbubble discharge tube 15 is provided on the water surface, and FIGS. 6 and 8 show the case where the opening 15a of the microbubble discharge tube 15 is provided below the water surface, that is, in water. Show.

  The microbubble discharge pipe 15 is not necessarily fixed on the hull side, and a flexible hose or the like extending from the deck may be used as necessary. If comprised in this way, since the work which provides the new opening part 15a in the existing hull becomes unnecessary, the shielding apparatus 10B of the discharge water noise of a ship can also be easily provided also in the existing ship.

  Further, as shown in FIG. 9, a double tube structure in which a microbubble discharge tube 15 is provided around the discharge tube 3 and the discharge water W is discharged while being wrapped in the microbubble mixed water Wb. Good.

  The microbubbles discharged from the microbubble discharge pipe 15 do not disappear immediately, but some of them become smaller and disappear in water, but stay for a while near the water surface near the discharge part or in water. For this reason, the microbubbles are mixed with the discharge water W or surround the discharge water W, and the discharge water W released one after another collides with the water surface due to the sound absorption effect and the sound insulation effect of the microbubbles. The underwater noise generated and the underwater noise generated by the sound that has been riding on the discharge pipe 3 being directly released into the water are absorbed and insulated. Thereby, the influence of underwater noise on the acoustic sensor 4 mounted on the ship 1 is reduced.

  As the microbubble generator 12, an excessively dissolved gas is obtained by using a pressurized dissolved water tank to dissolve the gas sent by a pump by blowing a gas with a compressor to form pressurized water and reducing the pressure. A device for precipitating as a bubble can be used. This device is widely used in the levitation separation method, and the space of the device increases, but the flow rate and pressure can be adjusted, the bubble diameter can be made smaller and uniform, and the number of bubbles can be increased. On the other hand, there is a problem that the initial state cannot be maintained in the case of long-time driving and a problem that the operation is complicated.

  In addition, the microbubble generator 12 generates a two-layer swirling flow of liquid and gas at the center of the device, forms a cavity in the rotating shaft, and makes this cavity into a tornado shape for powerful rotation. A microbubble aerator device that generates a large amount of microbubbles by generating shearing force, sucking gas from the upper part of the device into the cavity, and shearing and crushing this gas cavity by rotation control action, and many fine holes A device using a diffuser plate that creates air bubbles by aeration, a stirring and mixing device that shears gas by agitating a liquid containing gas, and dissolves gas in liquid under pressure. There is a pump suction device or the like that precipitates dissolved gas that has become excessive as a result of decompression as bubbles.

  As the microbubble mixing device 13, the above-mentioned device can be used. However, by using an ejector, a device that dissolves gas in a liquid by vigorous gas-liquid mixing and bubbles by shearing can be used. This device is used as a device for gas-liquid contact, and has a simple structure, a relatively large bubble diameter, a relatively small number of bubbles, but a large liquid flow rate and a jet flow. There is.

    The bubble size distribution of the microbubbles varies depending on the type and control of the microbubble generator 12 and the microbubble mixing device 13, and the frequency components of the sound that can be absorbed and insulated by the bubble size and the bubble size distribution. In other words, since the attenuation coefficient for each frequency is different, it is necessary to control these devices 12 and 13 in order to absorb and insulate sound more efficiently. Although this attenuation coefficient is an example, it becomes about 20 dB / cm to about 40 dB / cm at 40 kHz to 100 kHz.

  Therefore, in these 1st Embodiment and 2nd Embodiment, emitted sound is received with the hydrophone (not shown) equipped with own acoustic sensor 4 or exclusive use, and the frequency analyzer 16 uses it. Underwater noise frequency analysis is performed, and based on the result, the output controller 17 controls the microbubble generator and the mixing devices 12 and 13 so that the microbubble diameter and amount reduce the underwater noise of the target frequency. To be configured.

  Alternatively, the relationship between the target frequency and the diameter and amount of the microbubbles, and the target frequency for reducing the underwater noise generated from the discharged water W are obtained in advance by actual measurement or experiment, and the target frequency is a micro that absorbs and blocks sound. The output controller 17 controls the microbubble generator and the mixing devices 12 and 13 so as to generate the bubble diameter and amount.

  According to the method of shielding the discharged water noise of the ship and the discharged water noise shielding apparatus having the above-described configuration, the microbubble mixed water Wb is mixed with the discharged water W, the surrounding of the discharged water W discharge, or the discharged water. Since it can be supplied between the water W and the acoustic sensor 4 or the like, underwater noise generated from the discharged water W can be shielded, and adverse effects on the acoustic sensor 4 and the like can be reduced.

  Further, in the first embodiment, the water is directly mixed into the discharged water W by the buffer tank 11 and the microbubble generator 12, or the microbubble mixed water Wb mixed with the microbubble is generated by the microbubble mixer 13 and then discharged. Since it mixes in the water W, the microbubbles can be mixed in the discharged water W more uniformly. Further, it is not necessary to newly provide the microbubble discharge tube 15 with the discharge tube 3 alone.

  Moreover, in 2nd Embodiment, since the microbubble mixed water Wb is supplied so that the discharge water W may be enclosed or the acoustic propagation path to the acoustic sensor 4 may be blocked, the change of the quantity of the discharge water W is changed. Regardless, the microbubble-mixed water Wb having a substantially predetermined concentration can be supplied to a predetermined portion, and the underwater noise generated from the discharged water W can be shielded stably. In addition, when the microbubble mixed water is supplied only between the discharged water W and the acoustic sensor 4, the amount of microbubbles generated is small.

It is a figure which shows the method of shielding the discharge water noise of the ship of 1st Embodiment based on this invention, and the shielding apparatus of the discharge water noise of a ship with respect to the discharge water discharge | released on the water surface using a buffer tank. . The figure which shows the method of shielding the discharge water noise of the other ship of 1st Embodiment based on this invention with respect to the discharge water discharged on the water surface which does not use a buffer tank, and the shielding apparatus of the discharge water noise of a ship It is. It is a figure which shows the method of shielding the discharge water noise of the ship of 1st Embodiment which concerns on this invention, and the shielding apparatus of the discharge water noise of a ship with respect to the discharge water discharge | released below the water surface using a buffer tank. . The figure which shows the method of shielding the discharge water noise of the other ship of 1st Embodiment based on this invention with respect to the discharge water discharged below the surface of the water which does not use a buffer tank, and the shielding apparatus of the discharge water noise of a ship It is. A method of shielding the discharged water noise of the ship of the second embodiment according to the present invention and the shielding of the discharged water noise of the ship against the discharged water that is provided on the water surface with the outlet of the microbubble discharge pipe It is a figure which shows an apparatus. A method of shielding the discharged water noise of the ship according to the second embodiment of the present invention and the shielding of the discharged water noise of the ship against the discharged water that is provided at the outlet of the microbubble discharge pipe below the water surface. It is a figure which shows an apparatus. A method of shielding the discharged water noise of the ship of the second embodiment according to the present invention and the shielding of the discharged water noise of the ship against the discharged water that is provided with the outlet of the microbubble discharge pipe above the water surface. It is a figure which shows an apparatus. A method of shielding the discharged water noise of the ship according to the second embodiment of the present invention and the shielding of the discharged water noise of the ship with respect to the discharged water discharged below the water surface by providing an outlet of the microbubble discharge pipe It is a figure which shows an apparatus. It is a figure which shows the double tube | pipe structure which provided the micro bubble discharge tube around the discharge tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ship 2 舷 Side 3 Release pipe 3a Opening part 4 Acoustic sensor 10A, 10B Shielding apparatus of the discharge water noise of a ship 11 Buffer tank 12 Microbubble generator 13 Microbubble mixing apparatus 14 Mixing pipe 15 Microbubble discharge pipe 15a Opening part W discharge | release Water Wb Microbubble mixed water

Claims (4)

  By mixing microbubbles into the discharge water discharged to the outside from the ship, the underwater noise generated when the discharge water is discharged into the water is sound-insulated by the microbubbles mixed into the discharge water and supplied to the water. A method for shielding discharged water noise of a ship.   By supplying microbubble mixed water to at least a part of the periphery of the discharged water discharged to the outside from the ship, underwater noise generated when the discharged water is discharged into the water is submerged in the water together with the mixed water. A method for shielding water discharge noise from a ship, characterized by sound insulation by supplied microbubbles.   A shielding apparatus for noise discharged from a ship, comprising a microbubble mixing device for mixing microbubbles into discharged water discharged to the outside from a ship. A shielding apparatus for discharged water noise of a ship, comprising a microbubble mixed water supply device that supplies mixed water of microbubbles to at least a part of the periphery of the discharged water discharged to the outside from the ship.

Images