CN107807172B - Sound insulation measurement device and measurement method of random incident underwater acoustic cover under pressurized condition - Google Patents

Abstract

The invention provides a sound insulation measuring device and a sound insulation measuring method of a random incidence underwater acoustic covering layer under a pressurization condition. The device comprises a sound source chamber, a sample chamber and a receiving chamber, wherein the side part and the bottom of the sound source chamber are made of rectangular seamless steel pipes to form a plurality of frames, an inflatable air bag is arranged in the middle of each frame, the sample chamber is of a structure with hemispherical shells at two ends and a middle cylindrical section, a pressure-resistant vibration isolator is arranged between each hemispherical shell and each cylindrical section, the receiving chamber is made of rectangular seamless steel pipes to form a plurality of frames, the inflatable air bag is arranged in the middle of each frame, and the measuring method comprises the steps of checking the sound insulation coefficient of a water layer of the sample chamber and measuring the sound insulation coefficient of an underwater acoustic. The device and the method for measuring the sound insulation coefficient of the material under the pressurization condition in the national standard are supplemented, and the device and the method for measuring the sound insulation coefficient of the randomly incident acoustic covering layer under the pressurization condition only need to pressurize the acoustic covering layer without considering the pressurization design problem of the transmitting transducer and the hydrophone, so that the implementation process of the experiment is greatly simplified.

Description

Sound Insulation Measurement Device and Measurement of Random Incident Underwater Acoustic Covering Layers under Pressure method

technical field

The invention relates to a sound insulation measuring device of an underwater acoustic covering layer. The invention also relates to a sound insulation measurement method of an underwater acoustic cover.

Background technique

At present, the sound insulation performance test of structural materials in the air has formed an international standard (ISO140-3) and a national standard (GB/T 19889.3-2005), which specify the measurement devices and measurement methods of sound insulation performance in detail, and Measurement uncertainty evaluation, etc. Since these two standards are based on the reverberation method, when the experiment is implemented, it is necessary to construct a sound source room (reverberation room) and a receiving room (reverberation room or anechoic room), and the two standards stipulate The measurement methods are all carried out at normal temperature and pressure (1atm), which can only meet the sound insulation performance test requirements of acoustic coverings in air, because sound insulation materials in air are rarely used in pressurized environments.

For underwater acoustic coverings, due to the influence of hydrostatic pressure, the sound insulation performance under pressurized conditions is usually concerned, and the sound insulation performance under normal pressure is rarely concerned. According to the national standard (GB/T 19889.3-2005), the sound insulation performance measurement device of the underwater acoustic covering layer in the pressurized environment is established. When the design pressure is 3MPa, the wall thickness of the sound source room needs to reach the meter level. The thickness of steel should not be less than 800mm, which greatly increases the development cost. Therefore, it is almost impossible to establish the sound insulation performance measurement device of the underwater acoustic cover under pressure according to the national standard (GB/T 19889.3-2005). of.

Theoretical and Experimental Research on Underwater Low-Frequency Sound Insulation Characteristics (Scholar Tan, Master's Thesis of Harbin Engineering University, 2010) carried out the experimental measurement of the low-frequency sound insulation performance of the muffler in a water-filled pressure tank, and his research found that the designed pressure The low-frequency acoustic coupling of the tank is particularly serious, so that the measurement results of the near-field sound intensity measurement array are unreliable, and the sound insulation performance test under random incidence conditions is not involved.

A method for measuring the sound insulation amount of underwater acoustic passive materials under limited space conditions (CN 105223271A) is based on the space-time focusing characteristic of underwater acoustic time reversal, which can suppress the reverberation of transmitted signals in the sound insulation amount measurement, and is suitable for solving low-frequency strong Difficulties in the measurement of sound insulation of passive materials under the background of reverberation, the patent noted the influence of reverberation in large pressure anechoic tanks on sound insulation measurement, but did not carry out random incident underwater acoustic covering under pressure conditions sound insulation performance measurement.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a sound insulation measuring device with a simple test process and easier implementation under pressure conditions with random incidence of underwater acoustic covering layers. The purpose of the present invention is also to provide a sound insulation measurement method of random incident underwater acoustic cover under pressurized conditions.

The object of the present invention is achieved in this way:

The sound insulation measurement device of the randomly incident underwater acoustic covering layer of the present invention under pressure conditions includes a sound source room, a sample room and a receiving room; the side and bottom of the sound source room are made of rectangular seamless steel pipes It consists of a grid-like frame and an inflatable air bag installed in the middle of the grid. The upper part of the sound source chamber is empty, and casters are installed at the bottom of the sound source chamber; the sample chamber includes hemispherical shells at both ends and a cylindrical section in the middle. A pressure-resistant vibration isolator is respectively arranged between the hemispherical shell and the cylindrical section; the side and bottom of the receiving chamber are made of rectangular seamless steel pipes to make a grid-like frame, and an inflatable air bag is installed in the middle of the grid. The upper part of the receiving chamber If it is empty, casters are installed at the bottom of the receiving room; there is a mechanism for adjusting the distance between the sound source room and the receiving room, and the sample room is connected with the sound source room and the receiving room by a waterproof rubber cloth.

The pressure-resistant vibration isolator is composed of a combination of thin spherical shells with different diameters, and the interior is filled with inert gas.

The measurement method of the sound insulation measuring device measuring device of the random incident underwater acoustic covering layer based on the pressurized condition of the present invention is:

In the first step, the sound source room is filled with water, the sample room is filled with water, and the receiving room is filled with water;

The second step is to put a transmitting transducer in the sound source room to transmit a single-frequency sine wave;

The third step, according to the sound wave wavelength in the air corresponding to the frequency sine wave emitted by the transducer, adjust the distance between the sample room and the sound source room to be an integer multiple of 1/4 of the sound wave wavelength;

The fourth step is to pressurize the sample chamber;

The fifth step is to place hydrophones in the sound source room and the sample room respectively, measure the mean square sound pressure at different spatial points, calculate the radiated sound power W ₁ of the sound source room, and the radiated sound power W ₂ of the receiving room. A water layer in the sample chamber is determined, and its sound insulation coefficient is evaluated according to formula (1):

When the value of formula (1) is 0, carry out the work of the sixth step;

The sixth step is to place the acoustic cover in the sample room, and according to the method of the fifth step, measure the radiated sound power W ₃ of the sound source room, the radiated sound power W ₄ of the receiving room, and the insulation of the underwater acoustic cover respectively. The acoustic coefficient is calculated according to formula (2):

The calculated value of formula (2) is the sound insulation coefficient of the underwater acoustic cover when the sound waves are randomly incident under different pressure conditions.

The sound insulation measurement device of the random incident underwater acoustic cover under pressurized conditions includes a sound source room, a sample room and a receiving room. The side and bottom of the sound source room are made of rectangular seamless steel tubes. Multiple frames, An inflatable air bag is installed in the middle of the frame, the upper part of the sound source chamber is air, and the bottom of the sound source chamber is installed with casters. The sample chamber is a hemispherical shell at both ends and a middle cylindrical section. Vibrator, the receiving chamber is made of multiple frames made of rectangular seamless steel pipes, a pressurized air bag is installed in the middle of the frame, the upper part of the receiving chamber is air, and casters are installed at the bottom of the receiving chamber; between the sound source chamber and the receiving chamber A mechanism for adjusting the spacing; the sample chamber and the sound source chamber are connected by a waterproof rubber cloth; the sample chamber and the receiving chamber are connected by a waterproof rubber cloth; the pressure-resistant vibration isolator is composed of a combination of thin spherical shells of different sizes and diameters. The interior is filled with high pressure inert gas.

The advantages of the present invention are: firstly, the sound source room and the receiving room are made of a frame and an inflatable air bag, the air bag wall is very thin, the acoustic interface composed of water, the air bag wall and the air is absolutely soft, and the sound wave passes through the air bag wall. The sound energy incident into the air is very small (about one thousandth), so that most of the sound energy is reflected back between the sound source room and the receiving room, so that the sound source room and the receiving room become a good reverberation room; secondly, The frame is made of seamless steel pipe, filled with air, which has a strong ability to reflect sound waves, and its surface area is relatively small compared with the total surface area of the sound source room and the receiving room, so that the sound source room and the receiving room are generated by the frame. The sound energy leakage capacity is limited; thirdly, the pressure-resistant vibration isolators made of thin spherical shells with different apertures have very thin shell walls, which are much smaller than the thickness of the cylindrical section of the sample chamber, which can well attenuate the sound source The ability of the sound wave of the chamber to propagate through the wall of the sample chamber, so that the sound wave of the sound source chamber can only propagate to the receiving chamber through the water in the sample chamber;

The advantages of the invention are also that: when the sample chamber is pressurized, the water in the sample chamber is pressurized water, while the water in the sound source chamber and the receiving chamber is normal pressure water, which solves the problem of underwater acoustic coverage well. The pressure problem during the sound insulation performance test of the layer; since the elastic modulus of water (10°C) is 2.1×10 ⁹ , that is, 2100MPa, the volume of water decreases by 1/2100 for every 1MPa increase in pressure, so 1MPa can be obtained. The density of water under normal pressure is only 0.8‰ higher than that under normal pressure, the density of water under 2MPa is 1.6‰ higher than that under normal pressure, and the density of water under 3MPa is 2.5‰ higher than that under normal pressure; With an increase of 1MPa, the sound speed only increases by 1.75m/s. Under the pressure condition of 0-3MPa, the acoustic reflection coefficient caused by the impedance change between the normal pressure water and the pressurized water can be calculated by formula (3):

In the formula, ρ=1500, is the speed of sound of water; c=1000, is the density of water; x=0, 1, 2, 3; k=0, 0.0008, 0.0016, 0.0025;

For example, when the pressure is 3MPa, the sound wave in the sound source chamber is incident into the sample chamber, and the sound wave reflection coefficient caused by the difference in density and sound speed caused by the water pressure is only 0.00296, which is negligible, that is, The acoustic reflection coefficient caused by the difference in acoustic impedance between the source chamber and the sample chamber, as well as the sample chamber and the receiving chamber due to the increase in pressure can be ignored, so the sound waves can travel smoothly from the source chamber to the sample chamber. , and then propagates to the receiving chamber through the sample chamber, which enables the measurement of the sound insulation performance of the underwater acoustic cover under pressurized conditions under the condition that only the sample chamber is pressurized; Under the condition of random incidence of the sound insulation measurement device of the underwater acoustic covering layer, by adjusting the distance between the sound source room and the receiving room, it avoids the "full transmission" phenomenon of sound energy in the common sound insulation wall, and can make the sound source room , the sample chamber and the receiving chamber maintain a good reverberation state, which improves the signal-to-noise ratio of the measurement and makes the measurement data more reliable.

The invention is also beneficial in that it is only necessary to pressurize the sample chamber during the test, but the sound source chamber and the receiving chamber need not be pressurized, so that the pressurization of the transmitting transducer and the receiving hydrophone need not be considered It is not necessary to consider the pressure design of the scanning structure of the hydrophone, thus greatly simplifying the test and testing process and making it easier to implement.

Description of drawings

Fig. 1 is a kind of overall block diagram of the sound insulation measurement device of random incident underwater acoustic cover under pressurized condition;

Figure 2 is a side view of the sound source room/receiving room;

Figure 3 is a schematic diagram of the connection between the inflatable airbag and the frame;

4 is a schematic diagram of adjusting the spacing between the sound source room and the receiving room;

Figure 5 is a schematic diagram of the connection of the experimental system for the measurement of the sound insulation performance of the randomly incident underwater acoustic cover under pressure conditions.

Detailed ways

The meanings of the reference signs in the accompanying drawings 1-4 of the present invention are: 1 is the sound source room, 101 is the frame, 102 is the inflatable air bag, 1021 is the fixing frame, 1022 is the bolt, 103 is the universal caster, 104 is the Universal caster, 105 is flange, 106 is distance adjustment mechanism, 107 is distance adjustment mechanism, 2 is receiving room, 201 is frame, 202 is inflatable air bag, 203 is universal caster, 204 is universal caster, 205 is method Lan, 206 is the distance adjusting mechanism, 207 is the distance adjusting mechanism, 3 is the sample chamber, 31 is the flange, 32 is the flange, 33 is the flange, 34 is the flange, 35 is the pressure isolator, 36 is the flange Acoustic covering layer clamping mechanism, 37 is acoustic covering layer clamping mechanism, 38 is water discharge valve, 39 is water inlet pressure valve, 310 is steel cable, 311 is steel cable, 4 is waterproof rubber cloth, 41 is flange, 42 is a flange, 5 is a lead screw, 51 is a nut with a handle, and 52 is a nut with a handle. The meanings of the reference symbols in the accompanying drawing 5 of the description are: 6 is the signal source, 7 is the power amplifier, and 8 is the data. Collector, 9 is a transmitting transducer, 10 is a hydrophone, and 11 is a hydrophone.

The sound insulation measurement device and measurement method of the present invention for randomly incident underwater acoustic covering layer under pressurized conditions will be described in detail below with reference to the accompanying drawings.

The sound source chamber 1 is made of a frame 101 made of a stainless steel tube with a rectangular cross-section. Holes are drilled and threads are tapped on the edge of each frame 101. The inflatable airbag 102 is a square shape with an outer surface of fiber cloth and an inner surface of white silicone rubber. In the structure, there is an inflation/deflation valve on the outer surface of the inflatable airbag 102, and a through hole is opened on the edge of the inflatable airbag 102, and the inflatable airbag 102 can be fixed on the frame 101 by the fixing frame 1021 and the bolt 1022 (M6), thereby The bottom surface and four sides of the sound source room 1 are made. A circular window is opened on one side of the sound source room 1. The flange 105 is installed on the edge of the window, and the universal direction is installed at the four bottom corners of the sound source room 1 respectively. Casters 103 and swivel casters 104 (the other two swivel casters, not shown in FIG. 1 ), are installed with a distance adjusting mechanism 106 and a distance adjusting mechanism 107 near the bottom corner of the side of the sound source room 1 where the window is opened.

The receiving chamber 2 is made of a frame 201 made of a stainless steel tube with a rectangular cross-section, and holes and threads are formed on the edge of each frame. The inflatable airbag 202 is a square structure with an outer surface of fiber cloth and an inner surface of white silicone rubber. There is an inflation/deflation valve on the outer surface of the inflatable airbag 202, and a through hole is opened on the edge of the inflatable airbag 202. The inflatable airbag 202 can be fixed on the frame 201 by using the fixing frame 1021 and the bolt 1022 (M6), thereby making The bottom surface and four sides of the receiving room 2, one side of the receiving room is opened with a circular window, the flange 205 is installed on the edge of the window, and the swivel casters 203 and swivel casters are respectively installed at the four bottom corners of the receiving room 2 204 (the other two swivel casters, not shown in FIG. 1 ), a distance adjusting mechanism 206 and a distance adjusting mechanism 207 are installed near the bottom corner of the side of the window of the receiving room 2 .

The middle of the sample chamber 3 is a cylindrical section, and the two ends are hemispherical shell structures. When the internal pressure is 3MPa, the thickness of the hemispherical shell cannot be less than 6.2mm. In this embodiment, the thickness of the spherical shell is 8mm. Weld flange 31 and flange 32 on the hemispherical shell, and both flanges 31 and 32 are open. There are through holes. According to the calculation of the thickness of the cylindrical section specified in the design standard for pressure vessels (GB150.3-2011), when the internal pressure of the cylindrical section is 3MPa, the thickness of the cylindrical section should not be less than 12.5mm. In this example The thickness of the cylindrical section is 15mm, and the cylindrical section is divided into two parts, one of which is welded with flange 33 and the other with welded flange 34. Both flanges 33 and 34 have through holes, and the pressure-resistant vibration isolator 35 is made of The two spherical shells are precisely welded together. The diameters of the two spherical shells are 30mm and 50mm, respectively, and the thickness is 1mm. The interior is filled with 3MPa argon gas. The mechanism 36 and the acoustic covering layer clamping mechanism 37 are annular structures used to fix the acoustic covering layer used for testing. A water discharge valve 38 is installed at the bottom of the sample chamber 3 and a water inlet is installed at the top of the sample chamber 3 The pressurizing valve 39 is used to wind the steel cable 310 and the steel cable 311 on the top of the sample chamber 3 for hoisting the sample chamber 3 .

The waterproof rubber cloth 4 is a micro-elastic plastic cloth with flanges 41 and 42 at both ends. The middle of the flange 41 and the flange 31 is filled with a silicone pad, which is fixed with bolts and nuts, and the middle of the flange 42 and the flange 105 is filled with silicone The gasket is fixed with bolts and nuts. At this time, one end of the sample chamber 3 is connected to the sound source chamber 1 , and the above process is repeated to connect the other end of the sample chamber 3 to the receiving chamber 2 .

One end of the lead screw 5 passes through the distance adjustment mechanism 106 of the sound source chamber 1, the nut 51 with the handle is screwed to one end of the lead screw 5, and the other end of the lead screw 5 passes through the distance adjustment mechanism 206 of the receiving chamber 2, and the belt The nut 52 of the handle is screwed to the other end of the lead screw 5 .

The sound source room 1 is filled with water, the receiving room 2 is filled with water, and the sample room 3 is filled with water, and the transmitting transducer 9 and the hydrophone 10 are put into the sound source room 1, and the signal source 6 (model: Agilent33220) Output a single-frequency sine signal with a frequency of 1000Hz, connect it to the transmitting transducer 9 through the power amplifier 7 (model: B&K2713), put the hydrophone 11 into the receiving room 2, the hydrophone 10 and the hydrophone 11. Connect the data collector 8 (model: B&K3660), turn the nut 52 with the handle, and adjust the distance between the sound source room 1 and the receiving room 2 to 42.5cm, which corresponds to the 1000Hz sound wave wavelength in the air (34cm) quarter Then, the sound pressure in the sound source room 1 and the receiving room 2 are measured by the hydrophone 10 and the hydrophone 11 using the spatial averaging technique, respectively. After data processing, the formula (1) is used to calculate this time. The sound insulation coefficient of the water layer in the sample chamber 3. At this time, the sound insulation coefficient of the water layer is the sound insulation coefficient under normal pressure. Then, the water in the sample chamber 3 is pressurized through the water inlet pressure valve 39, According to the above process, the sound insulation coefficient of the water layer in the sample chamber 3 when the sound waves are randomly incident under different pressure conditions can be measured.

Put an acoustic covering layer in the sample chamber 3, and repeat the above process to obtain the sound insulation coefficient of the acoustic covering layer under random incidence under different pressure conditions, so as to evaluate the sound insulation performance of the underwater acoustic covering layer.

Claims (3)

1. a sound insulation measuring device of random incidence underwater acoustic covering layer under pressurized conditions, comprising a sound source room, a sample room and a receiving room; it is characterized in that: the side part and the bottom of the sound source room are made of rectangular The upper part of the sound source chamber is open, and the bottom of the sound source chamber is equipped with casters; the sample chamber includes hemispherical shells at both ends and a cylinder in the middle A pressure-resistant vibration isolator is installed between the two hemispherical shells and the cylindrical section. The cylindrical section is divided into two sections, and the external welding flange at the boundary of the two sections is provided with an acoustic covering layer clamping mechanism. The acoustic covering layer clamps The holding mechanism is a ring-shaped structure, the bottom of the sample chamber is installed with a water discharge valve, and the top of the sample chamber is installed with a water inlet pressure valve; the side and bottom of the receiving chamber are grid-shaped frames made of rectangular seamless steel pipes 2. It is composed of an inflatable air bag installed in the middle of the grid. The upper part of the receiving chamber is open, and the bottom of the receiving chamber is equipped with casters; there is a mechanism for adjusting the distance between the sound source chamber and the receiving chamber, and the sample chamber and the sound source chamber are connected to the receiving chamber. The chambers are respectively connected by waterproof rubber cloth. 2. The sound insulation measuring device of random incident underwater acoustic covering layer under pressurized conditions according to claim 1, is characterized in that: the pressure-resistant vibration isolator is composed of a combination of thin spherical shells with different diameters, and the interior is filled with There are inert gases. 3. a measuring method based on the sound insulation measuring device of random incident underwater acoustic covering layer under the pressurized condition according to claim 1, is characterized in that: In the first step, the sound source room is filled with water, the sample room is filled with water, and the receiving room is filled with water; The second step is to put a transmitting transducer in the sound source room to transmit a single-frequency sine wave; The third step, according to the sound wave wavelength in the air corresponding to the frequency sine wave emitted by the transducer, adjust the distance between the sample room and the sound source room to be an integer multiple of 1/4 of the sound wave wavelength; The fourth step is to pressurize the sample chamber; The fifth step is to place hydrophones in the sound source room and the sample room respectively, measure the mean square sound pressure at different spatial points, calculate the radiated sound power W ₁ of the sound source room, and the radiated sound power W ₂ of the receiving room. A water layer in the sample chamber is determined, and its sound insulation coefficient is evaluated according to formula (1):

When the value of formula (1) is 0, carry out the work of the sixth step; The sixth step is to place the acoustic cover in the sample room, and according to the method of the fifth step, measure the radiated sound power W ₃ of the sound source room, the radiated sound power W ₄ of the receiving room, and the insulation of the underwater acoustic cover respectively. The acoustic coefficient is calculated according to formula (2):

The calculated value of formula (2) is the sound insulation coefficient of the underwater acoustic cover when the sound waves are randomly incident under different pressure conditions.

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