Needle bubble generator device and sound insulation measuring method

Abstract

The invention discloses a needle head bubble generator device and a sound insulation measurement method, which can reduce noise propagation by generating a bubble curtain in a needle head device and utilizing the sound absorption characteristic of the bubble curtain. The method mainly comprises the following steps: determining parameters of a needle device, and constructing a bubble curtain model of the needle device; a high-speed camera is used for shooting clear pictures of the bubbles, and an edge detection algorithm is used for solving a bubble diameter distribution rule; the emission frequency is changed, and sound insulation optimization is carried out on the resonance radius of the bubble curtain; the layer number and the inflation flow of the needle head device are changed, and sound insulation optimization is carried out on the volume concentration of the bubble curtain. The method has the advantages of being easy and convenient to operate, wide in application range, remarkable in noise reduction effect and the like, and has application value for various underwater noise control occasions.

Description

Technical Field

[0001] The present invention relates to the field of sound insulation measurement methods, and particularly to a needle bubble generator device and a sound insulation measurement method. Background Art

[0002] The bubble curtain sound insulation technology is an underwater sound insulation method that uses the curtain formed by bubbles in water to reduce the propagation of noise. With the development of marine resources and the increase of marine activities, the problem of underwater noise pollution has become increasingly serious, which has an adverse impact on the survival of marine organisms and human activities. In order to effectively reduce underwater noise and protect the marine ecological environment, the bubble curtain sound insulation technology has emerged.

[0003] When implementing the bubble curtain sound insulation technology, bubbles are usually injected into water through special equipment to form a bubble curtain with a certain thickness and density. When sound waves encounter the bubble curtain, part of the sound energy is absorbed by the bubbles and part is scattered, greatly reducing the energy of the sound waves, thus achieving the purpose of noise reduction. The bubble curtain sound insulation technology is widely used in scenarios such as offshore wind farms, ship docks, and underwater construction, effectively reducing the potential hazards of these activities to marine organisms and human health.

[0004] The background technology of the bubble curtain noise reduction technology mainly includes the following aspects: First, the speed and distance of sound propagation in water are much greater than in air, so the control of underwater noise is particularly important. Second, during the rising process of bubbles in water, due to the physical property differences between air and water, sound waves will be scattered and absorbed, thereby reducing the propagation energy of sound waves. However, the sound insulation effect is related to the diameter and concentration of bubbles, and also has a direct relationship with the frequency of sound waves. Summary of the Invention

[0005] The object of the present invention is to provide a needle bubble generator device and a sound insulation measurement method. The method is different from the conventional sound insulation measurement methods of bubble curtains, and improves the sound insulation effect by respectively targeting the bubble diameter, concentration of the bubble curtain, and the sound wave frequency.

[0006] A needle bubble generator device includes:

[0007] A gas cylinder;

[0008] A flow meter connected to the air outlet of the gas cylinder through a gas pipe;

[0009] A check valve connected to the flow meter through a gas pipe;

[0010] A shunt connected to the check valve through a gas pipe;

[0011] A plurality of needles installed on the shunt.

[0012] The outlet of the gas cylinder is connected to a pressure reducing valve, and the outlet of the pressure reducing valve is connected to the flowmeter through the trachea.

[0013] The check valve is connected to the inlet of the diverter through the trachea.

[0014] The multiple needles are installed on the outlet of the diverter.

[0015] A sound insulation measurement method using the needle bubble generator device includes the following steps:

[0016] 1) Place the diverter and needles in the needle bubble generator device in a water container, and install a hydrophone and a transmitting transducer in the water container. Adjust the pressure reducing valve and flowmeter in the needle bubble generator device to obtain a stable and uniform bubble curtain;

[0017] 2) Determine the bubble radius;

[0018] 3) Obtain the resonance frequency of the bubble curtain according to the bubble radius;

[0019] 4) Set an anechoic wedge in the water container, place the diverter and needles between the hydrophone and the transmitting transducer. The transmitting transducer is connected to a signal generator, and the hydrophone is connected to a signal collector. The signal generator sets multiple single frequencies. The hydrophone receives the sound pressure p1 of the acoustic wave signals of different frequencies passing through the bubble-free curtain, and the sound pressure of the acoustic wave signals of different frequencies passing through the bubble curtain is p t , and convert the two sound pressures into insertion loss According to the insertion loss Draw a curve graph of the insertion loss changing with frequency;

[0020] 5) The signal generator is set to a fixed single frequency. Control the flowmeter to measure the sound pressure level of the acoustic wave signals received by the hydrophone passing through the bubble-free curtain at different flow rates, and the sound pressure level of the acoustic wave signals received by the hydrophone passing through the bubble curtain at different flow rates, and draw a curve graph of the sound pressure level changing with the flow rate;

[0021] 6) Combine the curve graph of the insertion loss changing with frequency and the curve graph of the sound pressure level changing with the flow rate, and select the points on the curve with the best sound insulation effect.

[0022] In step 2), to determine the bubble radius, it specifically includes:

[0023] 2.1) Adjust the positions of the high-speed camera and the LED lamp to take a clear picture of the bubble curtain;

[0024] 2.2) Use the Canny edge detection algorithm to perform erosion and dilation processing on the clear picture to obtain the diameter sizes of all the bubbles in the bubble curtain, and then solve for the average radius R of the bubble curtain.

[0025] In step 3), the resonant frequency of the bubble screen is obtained according to the bubble radius, specifically including:

[0026] According to the calculation formula of the pressure inside the bubble Resonant frequency calculation formula The resonant frequency f of the bubble screen is obtained;

[0027] In the formula: γ is the specific heat ratio of the gas, p0 is the atmospheric pressure, R is the average radius of the bubble screen, ρ is the density of water, h is the distance of the bubble below the water surface, and T is the surface tension of water.

[0028] In step 4), the anechoic wedge is made of polyurethane material.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The needle bubble generator device and the sound insulation measurement method of the present invention generate a bubble screen in the needle device and utilize the sound absorption characteristics of the bubble screen to reduce the noise propagation. This method mainly includes the following steps: determining the parameters of the needle device and constructing a bubble screen model of the needle device; using a high-speed camera to take clear pictures of the bubbles and adopting an edge detection algorithm to obtain the distribution law of the bubble diameters; changing the emission frequency to optimize the sound insulation of the resonant radius of the bubble screen; changing the number of layers and the inflation flow rate of the needle device to optimize the sound insulation of the volume concentration of the bubble screen. This method has the advantages of simple operation, wide application range, and remarkable noise reduction effect, and has application value in various underwater noise control occasions. Brief Description of the Drawings

[0031] Figure 1 It is a two-dimensional installation diagram of the flow divider 1 and the needle 2;

[0032] Figure 2 It is a schematic diagram of the bubble generating device;

[0033] Figure 3 It is a flowchart of the implementation method;

[0034] Figure 4 It is a schematic diagram of bubble imaging;

[0035] Figure 5 It is a high-speed camera bubble image;

[0036] Figure 6 It is an optimized diagram of the Canny algorithm;

[0037] Figure 7 It is a diameter distribution diagram of the bubbles;

[0038] Figure 8 It is a mean result diagram of the bubble data;

[0039] Figure 9It is the experimental schematic diagram for acoustic wave emission and acquisition;

[0040] Figure 10 It is the TL diagram for changing the frequency;

[0041] Figure 11 It is the sound pressure level diagram for changing the volume concentration of the gas;

[0042] Figure 12 It is the TL comparison diagram under two flow rates. Specific implementation mode

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation modes.

[0044] A needle bubble generator device and a sound insulation measurement method of the present invention at least include the following steps:

[0045] (1) Generate a stable and uniform bubble curtain, specifically including:

[0046] As Figure 1 、 2 shown, the present invention provides a needle bubble generator device. The device mainly consists of a flow divider 1, a needle 2, a pressure reducing valve 3, a flowmeter 4, a nitrogen cylinder 5, an air pipe 6, a check valve 7, etc. The air outlet of the nitrogen cylinder 5 is connected to the pressure reducing valve 3, the air outlet of the pressure reducing valve 3 is connected to the flowmeter 4 through the air pipe 6, the flowmeter 4 is connected to the check valve 7 through the air pipe 6, and then connected to the air inlet of the flow divider 1 through the air pipe 6, and a unified needle 2 is installed at the air outlet of the flow divider 1. By controlling the pressure reducing valve 3 and the flowmeter 4, a uniform and stable bubble curtain is generated.

[0047] (2) Analyze the diameter of the bubbles, specifically including:

[0048] a) As Figure 4 shown, a reference frame is used to locate the position of the bubble curtain, and the bubble curtain is divided into multiple regions through the reference frame.

[0049] b) Set parameters such as the resolution, sampling rate, and exposure time of the high-speed camera and adjust the position of the LED light source, and use the adjusted high-speed camera to take pictures of the bubbles in each region to obtain clear pictures of the bubbles.

[0050] c) Transmit the obtained clear pictures to the information analysis system, analyze the clear images, and obtain the bubble diameter distribution rules under different pressures and different flow rates.

[0051] (3) Analyze the sound insulation effect of changing the frequency, specifically including:

[0052] a) According to the calculation formula of the resonance frequency Calculation formula for the pressure inside the bubble Obtain the resonance frequency of the bubble curtain.

[0053] b) Set parameters such as the waveform, frequency, amplitude, and phase of the sound wave in the signal generator. The given frequency range is 1000 Hz above and below the resonance frequency.

[0054] c) Receive the sound pressure without the bubble curtain at different frequencies as p1, and receive the sound pressure with the bubble curtain at different frequencies as p t , and convert it into the insertion loss TL to observe the sound insulation effect of the bubble curtain at different frequencies.

[0055] (4) Analyze the sound insulation effect of changing the volume concentration of the bubbles, specifically including:

[0056] a) Set parameters such as the waveform, frequency, amplitude, and phase of the sound wave in the signal generator. Then conduct experiments with the sound wave signal of the same parameters.

[0057] b) Increase the number of shunt 1 and change the flow rate of flowmeter 4.

[0058] c) Receive the sound pressure without the bubble curtain as p1, and receive the sound pressure with the bubble curtain at different flow rates as p t , to observe the sound insulation effect of the bubble curtain at different volume concentrations.

[0059] (5) Combine the sound insulation effects of changing the frequency and changing the volume concentration of the gas to find the optimal sound insulation effect, specifically including:

[0060] a) Set parameters such as the waveform, frequency, amplitude, and phase of the sound wave in the signal generator. The given frequency range is 1000 Hz above and below the resonance frequency.

[0061] b) Control the number of shunt 1 and increase the flow rate of flowmeter 4, and adjust to the optimal volume concentration in step (4).

[0062] c) Receive the sound pressure without the bubble curtain at different frequencies as p1, and receive the sound pressure with the bubble curtain at different frequencies as p t , and convert it into the insertion loss TL, and compare it with the insertion loss in step (3).

[0063] Taking a needle 2 with an outer diameter of 0.24 mm, an inner diameter of 0.1 mm, and an exposed length of 25.5 mm as an example, it is installed with the shunt 1 as Figure 1 shown. The schematic diagram of the bubble generation device and the schematic diagram of the bubble camera are as Figure 2 , Figure 4 shown, Figure 2 This is the flow chart of the implementation method of the present invention, and the specific steps are as follows:

[0064] 1. Generate a stable and uniform bubble curtain:

[0065] (1) Connect the bubble generating device completely as shown. Figure 2 Connect the bubble generating device completely as shown.

[0066] (2) Adjust the reading of the pressure reducing valve 3 to 0.025 mpa.

[0067] (3) Adjust the reading of the flowmeter 4 to 2 L / min.

[0068] 2. Analyze the diameter distribution of the bubble curtain:

[0069] (1) The size of the bubble curtain is 25 cm wide and 30 cm high. The reference frame divides the bubble curtain into 30 square areas of 5 * 5 cm.

[0070] (2) Enter the pcc software and set the parameters of the high-speed camera. The specific settings are as follows:

[0071] Resolution: 1024 * 1024, sampling rate: 200 fps, exposure time: 200 us, EDR: 0 us, exposure index: 32000.

[0072] (3) Adjust the positions of the high-speed camera and the LED light source as shown. The set high-speed camera takes separate pictures of the 30 areas, and the high-speed camera bubble images are obtained as shown. Figure 4 Adjust the positions of the high-speed camera and the LED light source as shown. The set high-speed camera takes separate pictures of the 30 areas, and the high-speed camera bubble images are obtained as shown. Figure 5 as shown.

[0073] (4) Use the Canny edge detection algorithm in the python software to perform erosion and dilation processing on the obtained bubble pictures to filter out the noise in the pictures and obtain the optimized processed images, as shown. Figure 6 as shown.

[0074] (5) Enter the image J software to calculate the size of the optimized bubble images and obtain the size distribution statistical table of the bubbles, as shown in Table 1.

[0075] Table 1

[0076] Diameter / cm Number of bubbles / each ＜0.09 0 0.09～0.10 7 0.10～0.11 43 0.11～0.12 88 0.12～0.13 192 0.13～0.14 254 0.14～0.15 416 0.15～0.16 347 0.16～0.17 293 0.17～0.18 165 0.18～0.19 75 0.19～0.20 26 ＞0.20 1 Total 1907

[0077] (6) Import the obtained bubble size data into the origin software and draw the diameter distribution diagram of the bubbles, as shown. Figure 7 as shown.

[0078] (7) Perform operations such as mean and standard deviation on the obtained bubble size data. The mean result diagram of the bubble data is as shown. Figure 8 as shown.

[0079] 3. Analyze the sound insulation effect of changing the frequency:

[0080] (2) Assign the mean result of Figure 8 to R. According to the resonant frequency calculation formula The calculation formula for the pressure inside the bubble The specific data in the formula are as follows:

[0081] The specific heat ratio γ of nitrogen is approximately equal to 1.4;

[0082] The radius R of the bubble is equal to 0.1484 cm;

[0083] The density ρ of water is equal to 1 g / cm 3 ;

[0084] The atmospheric pressure p0 is equal to 101.325 kMpa;

[0085] The underwater position h of the bubble is equal to 30 cm;

[0086] The surface tension T of water is equal to 72.8 mN / m.

[0087] The resonant frequency of the bubble curtain is obtained to be approximately 4433 Hz.

[0088] (2) As Figure 9 shown, arrange the experimental equipment for acoustic wave emission and acquisition.

[0089] (3) Set the parameters of the acoustic wave in the signal generator. The specific parameters are as follows:

[0090] The waveform is a sine wave, the amplitude is 10 v, the phase is 0°, the frequency range is 3500 Hz to 5300 Hz, which are 3500 Hz, 3700 Hz, 3900 Hz, 4100 Hz, 4300 Hz, 4400 Hz, 4500 Hz, 4700 Hz, 4900 Hz, 5100 Hz, 5300 Hz respectively.

[0091] (4) Set the parameters of the acquisition equipment. The specific parameters are as follows:

[0092] The number of samples is 5000, the sampling rate is 50000, the maximum voltage is 5 v, the minimum voltage is -5 v, and the acquisition time is 3 seconds.

[0093] (5) The acquisition equipment respectively receives the sound pressure p1 without the bubble curtain at each single frequency generated by the signal generator.

[0094] (6) The acquisition equipment respectively receives the sound pressure p t .

[0095] (7) Convert the two sound pressures received at each single frequency into the insertion loss TL to observe the sound insulation effect of the bubble curtain on different frequencies, asFigure 10 as shown

[0096] 4. Analyze the sound insulation effect of changing the bubble volume concentration:

[0097] (1) Set the parameters of the sound wave in the signal generator. The specific parameters are as follows:

[0098] The waveform is a sine wave, the amplitude is 10V, the phase is 0°, and the frequency is 5000Hz.

[0099] (2) The number of shunt 1 is 1, and control the flow rates of the flowmeter 4 to be 1L / min, 1.5L / min, 2L / min, 4L / min, and 6L / min respectively.

[0100] (3) Set the parameters of the acquisition device. The specific parameters are as follows:

[0101] The number of samples is 5000, the sampling rate is 50000, the maximum voltage is 5V, the minimum voltage is -5V, and the acquisition time is 3 seconds.

[0102] (4) The acquisition device receives the sound pressure p1 under the bubble curtainless.

[0103] (5) The acquisition device respectively receives the sound pressures p t .

[0104] (6) Draw the sound pressure level diagrams at different flow rates, as Figure 11 shown, to observe the sound insulation effect of the bubble volume concentration.

[0105] 5. Combine the sound insulation effects of changing the frequency and changing the volume concentration of the gas to find the optimal sound insulation effect:

[0106] (1) Set the parameters of the sound wave in the signal generator. The specific parameters are as follows:

[0107] The waveform is a sine wave, the amplitude is 10V, the phase is 0°, the frequency range is 3500Hz to 5300Hz, which are 3500Hz, 3700Hz, 3900Hz, 4100Hz, 4300Hz, 4400Hz, 4500Hz, 4700Hz, 4900Hz, 5100Hz, and 5300Hz respectively.

[0108] (2) The number of shunt 1 is 1, and control the flow rate of the flowmeter 4 to be 4L / min.

[0109] (3) Set the parameters of the acquisition device. The specific parameters are as follows:

[0110] The number of samples is 5000, the sampling rate is 50000, the maximum voltage is 5V, the minimum voltage is -5V, and the acquisition time is 3 seconds.

[0111] (4) The acquisition device respectively receives the sound pressure p1 without the bubble curtain at each single frequency generated by the signal generator.

[0112] (5) The acquisition device respectively receives the sound pressure p t .

[0113] (6) Convert the two sound pressures received at each single frequency into the insertion loss TL and compare it with the insertion loss in step 3, as Figure 12 shown.

Claims

1. A needle bubble generator device, characterized in that: include: Gas cylinders; a flow meter connected to the gas outlet of the gas bottle through a gas pipe; a check valve connected to the flow meter via an air pipe; A flow divider connected to the check valve via an air pipe; A plurality of needles are mounted on the shunt.

2. The needle bubble generator device according to claim 1, characterized in that: The gas outlet of the gas bottle is connected to the pressure reducing valve, and the gas outlet of the pressure reducing valve is connected to the flow meter through the air pipe.

3. The needle bubble generator device according to claim 1, characterized in that: The check valve is connected to the air inlet of the diverter through the air pipe.

4. The needle bubble generator device according to claim 1, characterized in that: The plurality of needles are mounted on the gas outlet of the diverter.

5. A sound insulation measurement method, characterized in that: The needle bubble generator device according to any one of claims 1 to 4 comprises the following steps: 1) placing the diverter and the needle in the needle bubble generator device in a water container, installing a hydrophone and a transmitting transducer in the water container, and adjusting the pressure reducing valve and the flow meter in the needle bubble generator device to obtain a stable and uniform bubble curtain; 2) Determine the bubble radius; 3) Obtain the resonant frequency of the bubble curtain according to the bubble radius; 4) A silencing wedge is set in the water container, and the diverter and the needle are placed between the hydrophone and the transmitting transducer. The transmitting transducer is connected to the signal generator, and the hydrophone is connected to the signal collector. The signal generator is set with multiple single frequencies. The hydrophone receives sound wave signals of different frequencies at a sound pressure of p1 when passing through the bubble curtain, and receives sound wave signals of different frequencies at a sound pressure of p when passing through the bubble curtain. t , converting the two sound pressures into insertion loss According to the insertion loss Plot a graph of insertion loss versus frequency; 5) The signal generator is set to a fixed single frequency, and the flowmeter is controlled to receive the sound pressure level of the sound wave signal passing through the bubble curtain at different flow rates by the hydrophone, and the sound pressure level of the sound wave signal passing through the bubble curtain at different flow rates, and a curve graph of the sound pressure level changing with the flow rate is drawn; 6) Combine the graph of insertion loss versus frequency and the graph of sound pressure level versus flow rate to select the point on the curve with the best sound insulation effect.

6. The sound insulation measurement method according to claim 5, characterized in that: In step 2), the bubble radius is determined, specifically including: 2.1) Adjust the position of the high-speed camera and LED light to take clear pictures of the bubble curtain; 2.2) Use the Canny edge detection algorithm to perform corrosion and expansion processing on the clear image to obtain the diameter size of all bubbles in the bubble curtain, and then solve the average radius R of the bubble curtain.

7. The sound insulation measurement method according to claim 5, characterized in that: In step 3), the resonant frequency of the bubble curtain is obtained according to the bubble radius, specifically including: According to the formula for calculating the pressure inside the bubble Resonance frequency calculation formula Get the resonant frequency f of the bubble curtain; Where: γ is the specific heat ratio of the gas, p0 is the atmospheric pressure, R is the average radius of the bubble curtain, ρ is the density of water, h is the distance of the bubble under water, and T is the surface tension of water.

8. The sound insulation measurement method according to claim 5, characterized in that: In step 4), the sound-absorbing wedge is made of polyurethane material.

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