A U-shaped spatial array for radiated noise measurement

Abstract

This invention discloses a U-shaped spatial array for measuring radiated noise, relating to the field of noise measurement technology. It includes three surface arrays, an underwater acoustic array frame, and a side balancing device. The first surface array is laid flat on the underwater acoustic array frame. The second and third surface arrays are respectively mounted at both ends of the first surface array and kept vertical by the side balancing device to ensure attitude stability. The second and third surface arrays, together with the first surface array, form a U-shaped spatial array. This utilizes the scale and directivity advantages of a three-dimensional volumetric array to significantly improve the spatial array gain of low-frequency signals, thereby enhancing the measurement capability of radiated noise from underwater vehicles.

Description

Technical Field

[0001] The invention relates to the technical field of noise measurement, in particular to a U-shaped space array for radiated noise measurement. Background Art

[0002] With the development of vibration and noise reduction technologies such as float valve isolation, anechoic tiles, and mechanical finishing, the radiated noise level of underwater vehicles has been decreasing year by year. The trend of quieter and lower-frequency development has continuously increased the performance requirements of measurement arrays. The existing noise measurement systems are increasingly unable to meet the test requirements of new underwater targets. It is of great significance to carry out research on low-frequency, high-gain acoustic array test technology.

[0003] The radiated noise test array has gone through a development process from single hydrophone, distributed multi-hydrophone to linear array. The measurement system on the Hayes survey ship in the United States and the underwater noise test system on the Italian WAAS ship both use vertical linear arrays. However, in shallow water conditions, due to the limitation of sea depth, linear arrays still have limitations in measuring low-frequency radiated noise under low signal-to-noise ratio conditions. Summary of the invention

[0004] In response to the above-mentioned problems and technical needs, the inventors have proposed a U-shaped spatial array for radiated noise measurement, which utilizes the scale and directivity advantages of the three-dimensional volume array, greatly improves the spatial array gain of low-frequency signals, and enhances the measurement capability of radiated noise of underwater vehicles.

[0005] The technical solution of the present invention is as follows:

[0006] A U-shaped space array for radiated noise measurement comprises three surface arrays, an underwater acoustic array frame and a side balancing device. The first surface array is laid flat on the underwater acoustic array frame, the second and third surface arrays are respectively mounted on both ends of the first surface array and are kept in a vertical state by the side balancing device. The second and third surface arrays and the first surface array form a U-shaped space array.

[0007] Its further technical solution is that each array includes M The line arrays are evenly spaced, with an encrypted nested line array located in the middle. M -1 uniform linear array is evenly distributed on both sides of the encrypted nested linear array.

[0008] Its further technical solution is that the encrypted nested linear array includes N The spacing is d The first hydrophone array and N The spacing is d / 2 second hydrophone array is formed by concentric nesting, and only one hydrophone is set at the overlapping position of the nested part. The total length of the encrypted nested linear array is ( N -1) dThe encrypted nested linear array is used to improve the directivity of noise measurement in the middle of the U-shaped spatial array to improve the gain of the spatial array.

[0009] Its further technical solution is that each uniform line array includes N The spacing is d The total length of the first hydrophone array is ( N -1) d。

[0010] A further technical solution is that, on a vertical slice, a line array in each plane array is spliced ​​to form a planar U-shaped array. M The interval between two U-shaped arrays is l , the total size of the U-shaped space array is ( N -1) d ×( M -1) l ×( N -1) d .

[0011] Its further technical solution is that the side balancing device includes a surface buoy and an underwater balancing buoy. The upper end of each linear array in the second and third arrays is fixed with a surface buoy, and the lower end is fixed on the underwater balancing buoy. The underwater balancing buoys are distributed on both sides of the underwater acoustic array frame. The side balancing device maintains the linear arrays in the second and third arrays in a vertical state through the action of buoyancy.

[0012] Its further technical solution is to derive a second signal-to-noise ratio gain expression related to the focusing weighted vector of each array element in the planar array based on a first signal-to-noise ratio gain expression of a U-shaped space array established based on the signal power and noise power received by each array element in the planar array; to simplify the second signal-to-noise ratio gain expression by directing the array focusing point to the center of the U-shaped space array; and to further derive a third signal-to-noise ratio gain expression related to the array element spacing matrix under isotropic uniform noise field conditions as a calculation formula for the signal-to-noise ratio gain of the U-shaped space array.

[0013] A further technical solution is that the first signal-to-noise ratio gain expression is:

[0014] ;

[0015] in, , is the signal power and noise power received by a single array element, , are the signal power and noise power output by the U-shaped spatial array.

[0016] A further technical solution is that the derived second signal-to-noise ratio gain expression is:

[0017] ;

[0018] in, w is the focusing weight vector of each array element, is the noise covariance matrix, is the array manifold vector;

[0019] The array focus is pointed to the center of the U-shaped space array, which means that .

[0020] A further technical solution is that the derived third signal-to-noise ratio gain expression is:

[0021] ;

[0022] in, w is the focusing weight vector of each array element, is the wavelength of the sound wave, for dimensional array element spacing matrix.

[0023] The beneficial technical effects of the present invention are:

[0024] The above structure uses three surface arrays to form a three-dimensional U-shaped space array, which improves the space array gain at the scale level compared to the traditional vertical linear array, and can more effectively suppress noise interference compared to the low-dimensional array; the linear arrays that make up each surface array are provided with uniform linear arrays and encrypted nested linear arrays, and the encrypted nested linear arrays are located in the middle, which improves the ability of the U-shaped space array to measure radiated noise in the middle, making it more directional; the present invention makes full use of the scale advantage and directional advantage of the three-dimensional space array, greatly improves the space array gain of low-frequency signals, and can obtain 10dB~20dB of space array gain in the 25Hz~100Hz frequency band, and 20dB~28dB of space array gain in the 100Hz~5000Hz frequency band. At the same time, the spatial sound array is stably fixed to the bottom of the water through the underwater sound array rack and the side balancing device, which effectively reduces the impact of waves and improves the test signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the U-shaped space array model provided by this application.

[0026] Figure 2 (a) is a scale diagram of a uniform linear array provided in this application.

[0027] Figure 2 (b) is a scale diagram of the encrypted nested linear array provided by this application.

[0028] Figure 3 (a) is a front view of the array element distribution of the U-shaped spatial array provided in this application.

[0029] Figure 3 (b) is a left view of the array element distribution of the U-shaped spatial array provided in this application.

[0030] Figure 3 (c) is a top view of the array element distribution of the U-shaped spatial array provided in this application.

[0031] Figure 4 It is a schematic diagram of array gain comparison of the U-shaped spatial array provided in this application.

[0032] Figure 5 (a) is the vertical two-dimensional distance directivity slice of the U-shaped spatial array at the 50Hz frequency point.

[0033] Figure 5 (b) is the horizontal two-dimensional distance directivity slice of the U-shaped spatial array at the 50Hz frequency point.

[0034] Figure 6 (a) is the vertical two-dimensional distance directivity slice of the U-shaped spatial array at the 500Hz frequency point.

[0035] Figure 6 (b) is the horizontal two-dimensional distance directivity slice of the U-shaped spatial array at the 500Hz frequency point.

[0036] Among them: 1-water surface buoy; 2-uniform linear array; 3-encrypted nested linear array; 4-underwater acoustic array rack; 5-underwater balance buoy. DETAILED DESCRIPTION

[0037] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0038] like Figure 1 As shown, a U-shaped space array for radiated noise measurement includes three surface arrays, an underwater acoustic array frame 4 and a side balancing device. The first surface array is laid flat on the underwater acoustic array frame 4, and the second and third surface arrays are respectively mounted on both ends of the first surface array and are kept in a vertical state by the side balancing device. The second and third surface arrays form a U-shaped space array with the first surface array.

[0039] Each plane array includes nine linear arrays evenly spaced, one dense nested linear array 3 is located in the middle, and eight uniform linear arrays 2 are evenly distributed on both sides of the dense nested linear array 3. On the vertical slice, one linear array in each plane array is spliced ​​to form a planar U-shaped array. In this example, there are nine planar U-shaped arrays. Figure 2 As shown in (a), each uniform linear array includes twenty-one first hydrophone arrays with a spacing of 2m, so the total length of the uniform linear array is 40m 。 like Figure 2As shown in (b), the encrypted nested linear array 3 includes twenty-one first hydrophone arrays with a spacing of 2m and twenty-one second hydrophone arrays with a spacing of 1m, which are concentrically nested, and only one hydrophone is set at the overlapping position of the nested part. The number of hydrophones (that is, the number of array elements) in the encrypted nested linear array 3 is thirty-one, and the total length is 40m. The encrypted nested linear array 3 in this example is used to improve the directivity of noise measurement in the middle of the U-shaped space array to improve the space array gain.

[0040] Optionally, assuming that the nine planar U-shaped arrays are spaced 5 m apart from each other, the total size of the U-shaped spatial array is 40 m × 40 m × 40 m, with a total of 597 array elements.

[0041] Among them, the side balancing device includes a surface buoy 1 and an underwater balancing buoy 5. The upper end of each linear array in the second and third arrays is fixed with a surface buoy 1, and the lower end is fixed on the underwater balancing buoy 5. The underwater balancing buoy 5 is distributed on both sides of the underwater acoustic array frame 4. The side balancing device maintains the linear arrays in the second and third arrays in a vertical state through the buoyancy to ensure the stability of the U-shaped space array in the underwater posture.

[0042] This application also provides a method for calculating the signal-to-noise ratio gain of a U-shaped spatial array. The specific derivation process is as follows:

[0043] When conducting a radiation noise test on an underwater target, the target passes through the center of the U-shaped space array, and each array element of the U-shaped space array performs focusing compensation on the field point where the target is located. The first signal-to-noise ratio gain expression of the U-shaped space array is established based on the signal power and noise power received by each array element in the array, and the second signal-to-noise ratio gain expression related to the focusing weighted vector of each array element in the array is derived, where:

[0044] The first signal-to-noise ratio gain expression is:

[0045] ;

[0046] in, , is the signal power and noise power received by a single array element, , are the signal power and noise power output by the U-shaped spatial array.

[0047] The derived second signal-to-noise ratio gain expression is:

[0048] ;

[0049] in, w is the focusing weight vector of each array element, is the noise covariance matrix, is the array manifold vector.

[0050] The array focus is pointed to the center of the U-shaped space array, that is, , simplify the second signal-to-noise ratio gain expression.

[0051] Under the condition of isotropic uniform noise field, the third signal-to-noise ratio gain expression related to the array element spacing matrix is ​​further derived as the calculation formula of the signal-to-noise ratio gain of the U-shaped space array, where:

[0052] The derived third signal-to-noise ratio gain expression is:

[0053] ;

[0054] in, is the wavelength of the sound wave, for dimensional array element spacing matrix.

[0055] The effects of the present invention are analyzed below in conjunction with a simulation example.

[0056] Simulation 1: The array parameters of the U-shaped space array are as described in the above specific implementation, and the three-view diagram of its scale and array element distribution is as follows: Figure 3 (a) Figure 3 (b) Figure 3 As shown in (c), the spatial array gain comparison between this array and the linear array and planar array that make up this array in the frequency range of 10Hz~5000Hz is Figure 4 It can be seen that the U-shaped space array can obtain 10dB~20dB of space array gain in the frequency band of 25Hz~100Hz, and 20dB~28dB of space array gain in the frequency band of 100Hz~5000Hz; in the frequency band above 25Hz, it can obtain an additional 10dB of space array gain compared with the single linear array constituting the array, and an additional 4dB of space array gain compared with the single-sided planar array constituting the array.

[0057] Simulation 2: When the target passes through the center of the U-shaped spatial array, the vertical two-dimensional distance directivity slices and horizontal two-dimensional distance directivity slices of the U-shaped spatial array at 50Hz and 500Hz are as follows: Figure 5 , Figure 6 As shown, the shaded area in the figure represents the noise peak value of the test. When the frequency increases, the U-shaped spatial array of the present application can also test the radiation noise of the target.

[0058] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A U-shaped spatial array for radiated noise measurement, characterized in that: The invention comprises three arrays, an underwater acoustic array frame and a side balancing device, wherein the first array is laid flat on the underwater acoustic array frame, the second and third arrays are respectively mounted on two ends of the first array and are kept in a vertical state by the side balancing device, and the second and third arrays form a U-shaped space array with the first array; Each array includes M The line arrays are evenly spaced, with an encrypted nested line array located in the middle. M - 1 uniform linear array evenly distributed on both sides of the encrypted nested linear array; The encrypted nested linear array includes N The spacing is d The first hydrophone array and N The spacing is d / 2 of the second hydrophone array is formed by concentric nesting, and only one hydrophone is arranged at the overlapping position of the nested part. The total length of the encrypted nested linear array is ( N -1) d , the encrypted nested linear array is used to improve the directivity of the noise measurement in the middle of the U-shaped spatial array to improve the spatial array gain; Each of the uniform linear arrays comprises N The spacing is d The first hydrophone array, the total length of the uniform linear array is ( N -1) d .

2. The U-shaped spatial array for radiated noise measurement according to claim 1, characterized in that: On the vertical slice, a line array in each plane array is spliced ​​to form a planar U-shaped array. M The interval between the two plane U-shaped arrays is l , the total size of the U-shaped space array is ( N -1) d ×( M -1) l ×( N -1) d .

3. The U-shaped spatial array for radiated noise measurement according to claim 1, characterized in that: The side balancing device includes a water surface buoy and an underwater balancing buoy. The upper end of each linear array in the second and third arrays is fixed with the water surface buoy, and the lower end is fixed to the underwater balancing buoy. The underwater balancing buoy is distributed on both sides of the underwater acoustic array frame. The side balancing device maintains the linear arrays in the second and third arrays in a vertical state through the action of buoyancy.

4. The U-shaped spatial array for radiated noise measurement according to any one of claims 1 to 3, characterized in that: A first signal-to-noise ratio gain expression of a U-shaped spatial array is established based on the signal power and noise power received by each array element in the array, and a second signal-to-noise ratio gain expression related to the focusing weighted vector of each array element in the array is derived; the array focusing point is directed to the center of the U-shaped spatial array to simplify the second signal-to-noise ratio gain expression; under the condition of an isotropic uniform noise field, a third signal-to-noise ratio gain expression related to the array element spacing matrix is ​​further derived as a calculation formula for the signal-to-noise ratio gain of the U-shaped spatial array.

5. The U-shaped spatial array for radiated noise measurement according to claim 4, characterized in that: The first signal-to-noise ratio gain expression is: ； in, , is the signal power and noise power received by a single array element, , are the signal power and noise power output by the U-shaped spatial array.

6. The U-shaped spatial array for radiated noise measurement according to claim 4, characterized in that: The derived expression of the second signal-to-noise ratio gain is: ； in, w is the focusing weight vector of each array element, is the noise covariance matrix, is the array manifold vector; The array focusing point is directed to the center of the U-shaped space array, which means that .

7. The U-shaped spatial array for radiated noise measurement according to claim 4, characterized in that: The third signal-to-noise ratio gain expression derived is: ； in, w is the focusing weight vector of each array element, is the wavelength of the sound wave, for dimensional array element spacing matrix.

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