Gas-liquid cavity piston frequency identification and positioning method and device

Abstract

The present application provides a method and device for identifying and locating the piston frequency of a gas-liquid cavity, the method comprising: analyzing the noise data collected by a single hydrophone during the navigation of an underwater vehicle at different water depths according to a first preset rule, and determining the piston frequency of at least one gas-liquid cavity at each water depth, wherein the first preset rule comprises: the noise amplitude of the piston frequency at the same water depth is a local peak value, and for the same gas-liquid cavity, the piston frequency is linearly related to the water depth; and locating the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data. Through the present application, the problem of inaccurate calculation and unclear identification of traditional evaluation methods is overcome, and the piston frequency of the gas-liquid cavity can be accurately identified from the measured noise and its source can be located.

Description

Technical Field

[0001] The present application relates to the field of ship acoustic technology, and in particular to a method and device for frequency identification and positioning of a gas-liquid cavity piston. Background Art

[0002] There are a large number of line spectrum features in underwater vehicle noise. The identification and positioning of these characteristic frequencies is an important basis for improving underwater vehicle noise. Open cavity (hereinafter referred to as cavity) is an important source of line spectrum noise of underwater vehicles. Compared with the line spectrum features generated by mechanical systems or propulsion systems, the line spectrum features generated by cavities have diverse sources and are sensitive to navigation status, making them more difficult to identify and locate.

[0003] Reference Figure 1 Traditional theory holds that the cavity of an underwater vehicle is filled with liquid, and its characteristic frequencies mainly include shear oscillation frequency, acoustic cavity modal frequency, structural natural frequency, Helmholtz frequency, etc. Relevant studies in recent years have found that the cavity of an underwater vehicle is not always filled with liquid. During use, an indefinite amount of gas will be mixed into it. The introduction of gas causes a series of changes in the characteristic frequencies of this type of gas-liquid cavity. Figure 2 In the gas-liquid cavity, when the liquid in the cavity is disturbed, the gas in the cavity will expand / compress, thereby forming a pressure difference between the upper and lower surfaces of the liquid in the cavity, driving the liquid in the cavity to vibrate up and down. In this vibration mode, the liquid in the cavity moves in a form similar to a piston, so the frequency of this movement is called the piston frequency.

[0004] In the related art, the piston frequency of the target cavity is estimated through a theoretical model. When the measured line spectrum characteristic frequency shows a consistent frequency, it is determined that its source is the piston frequency of the target cavity. Figure 3 In relevant experiments, the measured line spectrum characteristic frequency often deviates from the piston frequency estimated by the theoretical model. When the line spectrum is dense, this deviation will cause the piston frequency estimated by the theoretical model to be close to the measured frequency of non-cavity causes, making it difficult to determine whether the difference between the evaluation results and the measured results comes from calculation errors or different essential causes. Therefore, it is impossible to accurately identify the piston frequency of the gas-liquid cavity from the measured noise and locate its source through existing technologies. Summary of the invention

[0005] The present application provides a method and device for identifying and locating the piston frequency of a gas-liquid cavity, which can accurately identify the piston frequency of the gas-liquid cavity from the measured noise and locate its source.

[0006] In a first aspect, an embodiment of the present application provides a method for frequency identification and positioning of a gas-liquid cavity piston, the method comprising:

[0007] Analyze the noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths according to a first preset rule, and determine the piston frequency of at least one gas-liquid cavity at each water depth, wherein the first preset rule includes: the noise amplitude of the piston frequency at the same water depth is a local peak value, and for the same gas-liquid cavity, the piston frequency is linearly related to the water depth;

[0008] The sound source is localized based on the piston frequency of the gas-liquid cavity identified from the noise data.

[0009] Furthermore, in one embodiment, the step of analyzing the noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths according to the first preset rule to determine the piston frequency of at least one gas-liquid cavity at each water depth includes:

[0010] The noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths is converted from the time domain to the frequency domain to obtain a first noise spectrum, the first noise spectrum is stored as a first matrix, and the first matrix is ​​plotted as a frequency-water depth cloud diagram;

[0011] Draw a first target oblique line on the frequency-water depth cloud map, wherein each first target oblique line passes through a local peak area of ​​the noise amplitude at all water depths, and the frequency corresponding to the local peak area changes with the water depth;

[0012] The piston frequency of a corresponding gas-liquid cavity at each water depth is determined according to each first target oblique line.

[0013] Furthermore, in one embodiment, the step of locating the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data includes:

[0014] For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency;

[0015] Comparing the noise amplitudes collected by multiple hydrophones at different positions of the underwater vehicle at the target piston frequency during navigation at the target water depth, and determining the hydrophone with the largest noise amplitude as the target hydrophone;

[0016] Analyze the noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds according to the second preset rule, and determine the shear oscillation frequency of at least one order of at least one cavity at each speed, wherein the second preset rule includes: the noise amplitude of the shear oscillation frequency at the same speed is a local peak value, for the same cavity, the shear oscillation frequency of the same order is linearly related to the speed, and the shear oscillation frequency of the same speed is proportional to the order;

[0017] Finding a shear oscillation frequency equal to a target piston frequency from at least one order of shear oscillation frequencies of at least one cavity at each ship speed;

[0018] For each shear oscillation frequency equal to the target piston frequency, the ship speed corresponding to the current shear oscillation frequency is used as the ship speed to be measured, and according to the noise amplitude collected by the target hydrophone at the target piston frequency during the navigation of the underwater vehicle at the target water depth, the ship speed to be measured and its adjacent ship speeds, it is judged whether the current shear oscillation frequency meets the resonance condition, wherein the resonance condition includes: the difference between the average value of the noise amplitude corresponding to the ship speed to be measured and the average value of the noise amplitude corresponding to the adjacent ship speed is greater than or equal to a preset threshold;

[0019] Determine any shear oscillation frequency that meets the resonance condition as the target shear oscillation frequency, and determine the corresponding speed and order as the target speed and target order;

[0020] The target size is calculated based on the target speed, target order and target shear oscillation frequency;

[0021] Around the target hydrophone, the air-liquid cavity whose absolute value of the difference between the opening size in the flow direction and the target size is within the error range is determined as the sound source.

[0022] Further, in one embodiment, the step of analyzing the noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds according to the second preset rule to determine the shear oscillation frequency of at least one order of at least one cavity at each speed includes:

[0023] The noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds are converted from the time domain to the frequency domain to obtain a second noise spectrum, the second noise spectrum is stored as a second matrix, and the second matrix is ​​plotted as a frequency-speed cloud diagram;

[0024] Draw a second target oblique line on the frequency-speed cloud diagram, wherein each second target oblique line passes through a local peak area of ​​the noise amplitude at all speeds, and the frequency corresponding to the local peak area changes with the speed;

[0025] If there is only one second target oblique line, the first-order shear oscillation frequency of a cavity at each ship speed is determined according to the second target oblique line;

[0026] If there are multiple second target oblique lines, the second target oblique lines are grouped according to the ratio of the slopes, and the first to Nth order oscillation frequencies of a cavity at each speed are determined according to a group of second target oblique lines, wherein, in the slopes of a group of second target oblique lines, the ratio of the maximum value to each value is 1 to N, and N is a positive integer.

[0027] Further, in one embodiment, the step of searching for a shear oscillation frequency equal to the target piston frequency from at least one order of shear oscillation frequencies of at least one cavity at each ship speed comprises:

[0028] Draw a target straight line with a frequency equal to the target piston frequency on the frequency-speed cloud diagram;

[0029] Find the shear oscillation frequency of the second target oblique line intersecting the target straight line at the intersection of the two.

[0030] Furthermore, in one embodiment, before the step of analyzing the noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths according to the first preset rule to determine the piston frequency of at least one gas-liquid cavity at each water depth, the method further includes:

[0031] In a single voyage, the underwater vehicle is controlled to naturally decelerate from the maximum speed to zero at different preset water depths, and noise data is collected through multiple hydrophones at different positions, where the target water depth is one of the preset water depths.

[0032] Furthermore, in one embodiment, the target size is calculated as follows: ;

[0033] Among them, L is the target size, a is a constant with a value range of [0.47, 0.53], n is the target order, U is the target speed, and f is the target shear oscillation frequency.

[0034] Furthermore, in one embodiment, the number of hydrophones on the underwater vehicle is greater than or equal to 3, the multiple hydrophones are arranged along the bow-midship-stern direction, and the interval between adjacent hydrophones is less than or equal to 10 m.

[0035] Furthermore, in one embodiment, the step of locating the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data includes:

[0036] For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency;

[0037] comparing the noise amplitudes collected by a plurality of hydrophones at different positions at the target piston frequency during the navigation of the underwater vehicle at the target water depth, and determining the hydrophone with the largest noise amplitude as the first hydrophone;

[0038] A second hydrophone is arranged next to each air-liquid cavity around the first hydrophone;

[0039] The noise amplitudes collected by multiple second hydrophones at the target piston frequency during the navigation of the underwater vehicle at the target water depth are compared, and the air-liquid cavity next to the second hydrophone with the largest noise amplitude is determined as the sound source.

[0040] In a second aspect, the embodiment of the present application further provides a gas-liquid cavity piston frequency identification and positioning device, the gas-liquid cavity piston frequency identification and positioning device comprising:

[0041] an identification module, configured to analyze noise data collected by a single hydrophone during navigation of the underwater vehicle at different water depths according to a first preset rule, and determine a piston frequency of at least one gas-liquid cavity at each water depth, wherein the first preset rule includes: a noise amplitude of the piston frequency at the same water depth is a local peak value, and for the same gas-liquid cavity, the piston frequency is linearly related to the water depth;

[0042] The positioning module is used to locate the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data.

[0043] In this application, a variable water depth test is designed to target the characteristics of piston frequency being sensitive to water depth. Instead of using the frequency distribution under a single water depth condition as the criterion, the frequency identification is carried out based on the frequency variation trend with the ship speed under multiple water depth conditions. The local peak frequency that is linearly related to the water depth is identified as the piston frequency. Knowing that the sound source is the gas-liquid cavity and the cause is the piston frequency, the sound source can be accurately located. This application overcomes the problem of inaccurate calculation and unclear identification of traditional evaluation methods, and can accurately identify the piston frequency of the gas-liquid cavity from the measured noise and locate its source. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the characteristic frequency of a pure liquid cavity in traditional theory;

[0045] Figure 2 This is a schematic diagram of the structure of the gas-liquid pore cavity in related research;

[0046] Figure 3 is a schematic diagram of the measured line spectrum in the relevant experiment;

[0047] Figure 4 This is a flow chart of a method for frequency identification and positioning of a gas-liquid cavity piston in one embodiment of the present application;

[0048] Figure 5 is a schematic diagram of a first noise spectrum in an embodiment of the present application;

[0049] Figure 6 for Figure 5 A schematic diagram of a frequency-water depth cloud diagram corresponding to the first noise spectrum shown;

[0050] Figure 7 is a schematic diagram of a second noise spectrum in an embodiment of the present application;

[0051] Figure 8 for Figure 7A schematic diagram of a frequency-velocity cloud diagram corresponding to the second noise spectrum is shown;

[0052] Fig. 9 FIG. 1 is a schematic diagram of the arrangement of hydrophones in an embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0054] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0055] In a first aspect, an embodiment of the present application provides a method for frequency identification and positioning of a gas-liquid cavity piston.

[0056] Figure 4 A schematic flow chart of a method for frequency identification and positioning of a gas-liquid cavity piston in one embodiment of the present application is shown.

[0057] Reference Figure 4 In one embodiment, the gas-liquid cavity piston frequency identification and positioning method comprises the following steps:

[0058] S1. Analyze the noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths according to the first preset rule, and determine the piston frequency of at least one gas-liquid cavity at each water depth, wherein the first preset rule includes: the noise amplitude of the piston frequency at the same water depth is a local peak value, and for the same gas-liquid cavity, the piston frequency is linearly related to the water depth.

[0059] Specifically, among the noise amplitudes of different frequencies at the same speed, if the noise amplitude of a certain frequency is significantly higher than the noise amplitudes of other nearby frequencies, the noise amplitude of this frequency is called a local peak, and this frequency is called a local peak frequency.

[0060] For example, the noise amplitude at the peak frequency f is more than 3 dB higher than the average value of the noise amplitude in the frequency band f±5 Hz.

[0061] In this embodiment, based on the rule that "the noise amplitude of the piston frequency at the same water depth is a local peak", the frequency points that may be the piston frequency at each water depth can be screened out one by one, and based on the rule that "for the same gas-liquid pore cavity, the piston frequency and the water depth are linearly related", the piston frequencies generated by different gas-liquid pore cavities at all water depths can be screened out in groups.

[0062] It should be noted that the “linear relationship” is a general description of the trend of change. When analyzing the measured noise, a certain degree of error can be allowed. For example, if a scatter plot of frequency-water depth is drawn, a series of points in a linear relationship do not need to all fall on the ideal inclined line, but can be distributed near it.

[0063] For example, by analyzing the noise data, it was found that when the water depth is 10m, the local peak frequencies are 21Hz and 27Hz, when the water depth is 20m, the local peak frequencies are 27Hz and 32Hz, when the water depth is 30m, the local peak frequencies are 27Hz and 42Hz, and when the water depth is 40m, the local peak frequencies are 27Hz and 53Hz.

[0064] It was found that 21Hz, 32Hz, 42Hz, and 53Hz were linearly related to the water depth. It was determined that this set of frequencies was the piston frequency of a gas-liquid cavity at different water depths, while 27Hz at water depths of 10m, 20m, 30m, and 40m was not a piston frequency.

[0065] S2. Localize the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data.

[0066] At present, in engineering practice, when abnormal line spectrum characteristics are monitored, it is usually necessary to deploy a large number of vibration and noise sensors on the underwater vehicle. Since the closer the sensor is to the noise source, the larger the amplitude of the line spectrum captured, the area where the noise source is located can be preliminarily determined. By further encrypting the sensors in the noise source area, the actual noise source location can be further approached. Finally, by performing comparative tests on several suspected noise sources in the positioning area under different states, the source of the line spectrum can be identified and located.

[0067] One voyage is from leaving the sea to entering the port. One voyage can last for multiple days, during which multiple tests are completed. The existing solution requires continuous encryption of sensors to approach the location of the sound source due to the uncertainty of the specific cause and location of the sound source. The encrypted sensors need to be carried out in the port, which requires multiple voyage tests. Therefore, the existing solution requires a large number of sensors and multiple voyage tests, which has problems such as high cost and low efficiency.

[0068] In this embodiment, since it is confirmed that the sound source is the gas-liquid cavity and the cause is the piston frequency, more effective information can be used for positioning, thereby reducing costs and improving efficiency while achieving accurate positioning.

[0069] Therefore, in this embodiment, a variable water depth test is designed to target the characteristics of the piston frequency being sensitive to water depth. Instead of using the frequency distribution under a single water depth condition as the criterion, the frequency identification is carried out based on the frequency variation trend with the ship speed under multiple water depth conditions. The local peak frequency that is linearly related to the water depth is identified as the piston frequency. When it is known that the sound source is the gas-liquid cavity and the cause is the piston frequency, the sound source can be accurately located. This embodiment overcomes the problem of inaccurate calculation and unclear identification of traditional evaluation methods, and can accurately identify the piston frequency of the gas-liquid cavity from the measured noise and locate its source.

[0070] Furthermore, in one embodiment, step S1 specifically includes:

[0071] The noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths is converted from the time domain to the frequency domain to obtain a first noise spectrum, the first noise spectrum is stored as a first matrix, and the first matrix is ​​plotted as a frequency-water depth cloud diagram;

[0072] Draw a first target oblique line on the frequency-water depth cloud map, wherein each first target oblique line passes through a local peak area of ​​the noise amplitude at all water depths, and the frequency corresponding to the local peak area changes with the water depth;

[0073] The piston frequency of a corresponding gas-liquid cavity at each water depth is determined according to each first target oblique line.

[0074] In this embodiment, the local peak is found by drawing a frequency-water depth cloud map, and the piston frequency of the same bore at different water depths is found by drawing a first target oblique line, thereby reducing the difficulty of analysis and intuitively displaying the analysis results.

[0075] Figure 5 A schematic diagram showing a first noise spectrum in an embodiment of the present application is shown; Figure 6 Shows Figure 5 A schematic diagram of a frequency-water depth cloud diagram corresponding to the first noise spectrum is shown.

[0076] For example, a variable depth test is carried out at a speed of 5 m / s, with a water depth range of 10~40 m / s. The noise data collected by a single hydrophone in the underwater vehicle is converted from the time domain to the frequency domain to obtain Figure 5 The first noise spectrum shown in the figure has a large number of line spectrum features in each water depth condition, and their respective sources cannot be intuitively distinguished. The first noise spectrum is stored as a first matrix, and the first matrix is ​​plotted using the pcolor command in Matlab as Figure 6 In the frequency-water depth cloud diagram shown, the areas corresponding to different noise amplitudes have different colors. For example, the red area sandwiched between the yellow areas belongs to the local peak area, and the yellow area sandwiched between the green areas belongs to the local peak area. Figure 6 It can be seen that there is a group of red areas showing a trend of linear increase in frequency with water depth, and a first target oblique line can be drawn, which is consistent with the characteristics of the piston frequency of the gas-liquid pore cavity.

[0077] Furthermore, in one embodiment, step S2 specifically includes:

[0078] For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency;

[0079] Comparing the noise amplitudes collected by multiple hydrophones at different positions of the underwater vehicle at the target piston frequency during navigation at the target water depth, and determining the hydrophone with the largest noise amplitude as the target hydrophone;

[0080] Analyze the noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds according to the second preset rule, and determine the shear oscillation frequency of at least one order of at least one cavity at each speed, wherein the second preset rule includes: the noise amplitude of the shear oscillation frequency at the same speed is a local peak value, for the same cavity, the shear oscillation frequency of the same order is linearly related to the speed, and the shear oscillation frequency of the same speed is proportional to the order;

[0081] Finding a shear oscillation frequency equal to a target piston frequency from at least one order of shear oscillation frequencies of at least one cavity at each ship speed;

[0082] For each shear oscillation frequency equal to the target piston frequency, the ship speed corresponding to the current shear oscillation frequency is used as the ship speed to be measured, and according to the noise amplitude collected by the target hydrophone at the target piston frequency during the navigation of the underwater vehicle at the target water depth, the ship speed to be measured and its adjacent ship speeds, it is judged whether the current shear oscillation frequency meets the resonance condition, wherein the resonance condition includes: the difference between the average value of the noise amplitude corresponding to the ship speed to be measured and the average value of the noise amplitude corresponding to the adjacent ship speed is greater than or equal to a preset threshold;

[0083] Determine any shear oscillation frequency that meets the resonance condition as the target shear oscillation frequency, and determine the corresponding speed and order as the target speed and target order;

[0084] The target size is calculated based on the target speed, target order and target shear oscillation frequency;

[0085] Around the target hydrophone, the air-liquid cavity whose absolute value of the difference between the opening size in the flow direction and the target size is within the error range is determined as the sound source.

[0086] In this embodiment, the hydrophone with the largest noise amplitude (here, the target hydrophone) is closest to the cavity to be located, which can narrow the search range. On this basis, considering that the piston frequency is the natural frequency of the system, its characteristics are most prominent when it resonates with the excitation frequency (here, the shear oscillation frequency). By finding the shear oscillation frequency that resonates with the target piston frequency, the positioning problem of the piston frequency can be equivalently converted into the positioning problem of the shear oscillation frequency. With the help of the relationship between the shear oscillation frequency and the speed, order, and opening size, the opening size of the cavity to be located in the flow direction is estimated and compared with the cavity around the target hydrophone to achieve accurate sound source positioning.

[0087] To find the shear oscillation frequency that resonates with the target piston frequency, we must first find the shear oscillation frequency that is equal to the target piston frequency. After finding the equal shear oscillation frequency, we can find the corresponding speed, and then determine whether it is resonant by whether the noise amplitude at the corresponding speed is significantly higher than other noise amplitudes at adjacent speeds. Since shear oscillation is a local phenomenon that exists near the opening, its influence range is very small, so the piston frequency of the gas-liquid cavity can only be excited by the shear oscillation frequency of the same gas-liquid cavity. When there are multiple shear oscillation frequencies that meet the resonance conditions, these shear oscillation frequencies can only be shear oscillation frequencies of different orders of the same gas-liquid cavity, and cannot be shear oscillation frequencies of different gas-liquid cavities. You can select any shear oscillation frequency for positioning.

[0088] Based on the rule that "the noise amplitude of the shear oscillation frequency at the same speed is the local peak", the frequency points that may be the shear oscillation frequencies at each speed can be screened out one by one. Based on the rule that "for the same cavity, the shear oscillation frequency of the same order is linearly related to the speed", the shear oscillation frequencies generated by the cavity at all speeds can be screened out in groups. Based on the rule that "for the same cavity, the shear oscillation frequency at the same speed is proportional to the order", it can be determined whether the shear oscillation frequencies of different groups are shear oscillation frequencies of different orders generated by the same cavity, or shear oscillation frequencies generated by different cavities.

[0089] Therefore, in view of the fact that the shear oscillation frequency is sensitive to the ship speed, a variable speed test was designed. The shear oscillation frequency was identified based on the changing trend of the frequency with the ship speed under multiple speed conditions, rather than the frequency distribution under a single speed condition. The local peak frequency that is linearly related to the ship speed is identified as the shear oscillation frequency, and the proportional relationship between the shear oscillation frequency and the order is used to analyze whether the multiple shear oscillation frequencies come from different orders of the same cavity or from different cavities.

[0090] Through this embodiment, the density of the hydrophones arranged on the underwater vehicle can be reduced, and there is no need to add hydrophones during the positioning process, thereby reducing costs and improving efficiency while achieving accurate positioning.

[0091] Further, in one embodiment, the step of analyzing the noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds according to the second preset rule to determine the shear oscillation frequency of at least one order of at least one cavity at each speed includes:

[0092] The noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds are converted from the time domain to the frequency domain to obtain a second noise spectrum, the second noise spectrum is stored as a second matrix, and the second matrix is ​​plotted as a frequency-speed cloud diagram;

[0093] Draw a second target oblique line on the frequency-speed cloud diagram, wherein each second target oblique line passes through a local peak area of ​​the noise amplitude at all speeds, and the frequency corresponding to the local peak area changes with the speed;

[0094] If there is only one second target oblique line, the first-order shear oscillation frequency of a cavity at each ship speed is determined according to the second target oblique line;

[0095] If there are multiple second target oblique lines, the second target oblique lines are grouped according to the ratio of the slopes, and the first to Nth order oscillation frequencies of a cavity at each speed are determined according to a group of second target oblique lines, wherein, in the slopes of a group of second target oblique lines, the ratio of the maximum value to each value is 1 to N, and N is a positive integer.

[0096] In this embodiment, the local peak is found by drawing a frequency-speed cloud diagram, the shear oscillation frequency of the same order of the same cavity at different speeds is found by drawing the second target oblique line, and the shear oscillation frequencies corresponding to different second target oblique lines are distinguished by comparing the slopes of the second target oblique lines to determine whether they come from the same cavity, thereby reducing the difficulty of analysis and providing an intuitive display of the analysis results.

[0097] Figure 7 A schematic diagram showing a second noise spectrum in an embodiment of the present application is shown; Figure 8 Shows Figure 7 A schematic diagram of a frequency-speed cloud diagram corresponding to the second noise spectrum is shown.

[0098] For example, the target water depth is set to 10m for variable speed test, the speed range is 5~10m / s, and the noise data collected by the target hydrophone in the underwater vehicle is converted from time domain to frequency domain to obtain Figure 7 The second noise spectrum shown in the figure has a large number of line spectrum features in each speed condition, and their respective sources cannot be intuitively distinguished. The second noise spectrum is stored as a second matrix, and the second matrix is ​​plotted using the pcolor command in Matlab as Figure 8In the frequency-speed cloud diagram shown, the areas corresponding to noise amplitudes of different sizes have different colors. For example, the red area sandwiched between the yellow areas belongs to the local peak area, and the yellow area sandwiched between the green areas belongs to the local peak area.

[0099] from Figure 8 It can be seen that there are two groups of red areas showing a trend of linear increase in frequency with speed, and two second target oblique lines can be drawn, which are consistent with the characteristics of the cavity shear oscillation frequency. The slope of the first second target oblique line is twice that of the second second target oblique line, which is consistent with the order characteristics of the shear oscillation frequency. Based on this, it can be judged that the frequencies corresponding to these two second target oblique lines are the first-order shear oscillation frequency and the second-order shear oscillation frequency of the same cavity at different speeds.

[0100] Further, in one embodiment, the step of searching for a shear oscillation frequency equal to the target piston frequency from at least one order of shear oscillation frequencies of at least one cavity at each ship speed comprises:

[0101] Draw a target straight line with a frequency equal to the target piston frequency on the frequency-speed cloud diagram;

[0102] Find the shear oscillation frequency of the second target oblique line intersecting the target straight line at the intersection of the two.

[0103] In this embodiment, a target straight line is drawn to find a shear oscillation frequency that is equal to a target piston frequency, thereby reducing the difficulty of analysis and displaying the analysis results intuitively.

[0104] For example, continue to refer to Figure 6 and Figure 8 ,from Figure 6 The target piston frequency is read as 21 Hz. Figure 8 A target straight line with a frequency of 21 Hz is drawn in the figure. The target straight line intersects with the first and second target oblique lines. The shear oscillation frequency at the intersection of the two is the first-order shear oscillation frequency of a certain cavity at a speed of 8 m / s.

[0105] Furthermore, in one embodiment, before step S1, the following steps are further included:

[0106] In a single voyage, the underwater vehicle is controlled to naturally decelerate from the maximum speed to zero at different preset water depths, and noise data is collected through multiple hydrophones at different positions, where the target water depth is one of the preset water depths.

[0107] Specifically, when the speed of the underwater vehicle reaches the maximum speed stably, the power of the underwater vehicle is turned off to decelerate naturally from the maximum speed to zero, thereby continuously traversing all speeds from zero to the maximum speed. In this way, no matter what the speed to be measured corresponds to the shear oscillation frequency equal to the target oscillation frequency, the noise amplitude at the speed to be measured and its adjacent speeds can be directly queried.

[0108] Through this embodiment, all noise data required for identifying and locating the piston frequency of the gas-liquid cavity can be collected in advance. During the identification and positioning process, only relevant data needs to be extracted for calculation operations, and no data collection is required, thereby further improving efficiency.

[0109] Furthermore, in one embodiment, the target size is calculated as follows: ;

[0110] Among them, L is the target size, a is a constant with a value range of [0.47, 0.53], n is the target order, U is the target speed, and f is the target shear oscillation frequency.

[0111] Through this embodiment, the target size can be calculated quickly and accurately.

[0112] Furthermore, in one embodiment, the number of hydrophones on the underwater vehicle is greater than or equal to 3, the multiple hydrophones are arranged along the bow-midship-stern direction, and the interval between adjacent hydrophones is less than or equal to 10 m.

[0113] Through this embodiment, accurate sound source positioning can be achieved with the help of fewer hydrophones, thereby reducing costs.

[0114] Fig. 9 A schematic diagram of the arrangement of hydrophones in an embodiment of the present application is shown.

[0115] For example, the length of the underwater vehicle is 50m. Fig. 9 , a hydrophone is arranged every 10m, and a total of 5 hydrophones are arranged from bow to stern, and they are numbered H1 to H5. Set the target water depth to 10m, from Figure 6The target piston frequency is read as 21Hz. The noise amplitudes collected by hydrophones H1~H5 at 21Hz during the navigation of the underwater vehicle at a depth of 10m are compared. It is found that the noise amplitude collected by hydrophone H2 is the largest. The noise data collected by hydrophone H2 at a water depth of 10m and a speed range of 5~10m / s are analyzed. It is found that the first-order shear oscillation frequency collected at a speed of 8m / s is also 21Hz. The noise amplitudes collected by hydrophone H2 at 21Hz during the navigation of the underwater vehicle at a water depth of 10m and a speed range of 7m / s, 8m / s and 9m / s are obtained. It is found that the noise amplitude corresponding to the speed of 8m / s is 3dB higher than the average value of the noise amplitude corresponding to the speed of 7m / s and 9m / s. Therefore, the target speed is determined to be 8m / s, the target order is 1, and the target shear oscillation frequency is 21Hz. Take a=0.52 and substitute it into the formula , the target size is calculated to be 0.198m. There are several cavities around the hydrophone H2, and the opening sizes in the flow direction are 0.05m, 0.2m, and 0.25m respectively. Among them, 0.2m is closest to the target size, and the corresponding cavity is determined as the sound source.

[0116] Furthermore, in one embodiment, step S2 specifically includes:

[0117] For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency;

[0118] comparing the noise amplitudes collected by a plurality of hydrophones at different positions at the target piston frequency during the navigation of the underwater vehicle at the target water depth, and determining the hydrophone with the largest noise amplitude as the first hydrophone;

[0119] A second hydrophone is arranged next to each air-liquid cavity around the first hydrophone;

[0120] The noise amplitudes collected by multiple second hydrophones at the target piston frequency during the navigation of the underwater vehicle at the target water depth are compared, and the air-liquid cavity next to the second hydrophone with the largest noise amplitude is determined as the sound source.

[0121] In this embodiment, the hydrophone with the largest noise amplitude is closest to the gas-liquid cavity to be located, which can narrow the search range. On this basis, since it is known that the sound source is the gas-liquid cavity, by setting a hydrophone next to each gas-liquid cavity in the narrowed search range and then comparing the noise amplitude, accurate sound source positioning can also be achieved. Through this embodiment, only one hydrophone needs to be added during the positioning process, and the sound source positioning can be completed through two voyages. Compared with the solution of multiple encrypted hydrophones in the prior art, it can also reduce costs and improve efficiency.

[0122] In a second aspect, an embodiment of the present application also provides a gas-liquid cavity piston frequency identification and positioning device.

[0123] In one embodiment, the gas-liquid cavity piston frequency identification and positioning device includes:

[0124] an identification module, configured to analyze noise data collected by a single hydrophone during navigation of the underwater vehicle at different water depths according to a first preset rule, and determine a piston frequency of at least one gas-liquid cavity at each water depth, wherein the first preset rule includes: a noise amplitude of the piston frequency at the same water depth is a local peak value, and for the same gas-liquid cavity, the piston frequency is linearly related to the water depth;

[0125] The positioning module is used to locate the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data.

[0126] Furthermore, in one embodiment, the identification module is used to:

[0127] The noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths is converted from the time domain to the frequency domain to obtain a first noise spectrum, the first noise spectrum is stored as a first matrix, and the first matrix is ​​plotted as a frequency-water depth cloud diagram;

[0128] Draw a first target oblique line on the frequency-water depth cloud map, wherein each first target oblique line passes through a local peak area of ​​the noise amplitude at all water depths, and the frequency corresponding to the local peak area changes with the water depth;

[0129] The piston frequency of a corresponding gas-liquid cavity at each water depth is determined according to each first target oblique line.

[0130] Furthermore, in one embodiment, the positioning module is used to:

[0131] For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency;

[0132] Comparing the noise amplitudes collected by multiple hydrophones at different positions of the underwater vehicle at the target piston frequency during navigation at the target water depth, and determining the hydrophone with the largest noise amplitude as the target hydrophone;

[0133] Analyze the noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds according to the second preset rule, and determine the shear oscillation frequency of at least one order of at least one cavity at each speed, wherein the second preset rule includes: the noise amplitude of the shear oscillation frequency at the same speed is a local peak value, for the same cavity, the shear oscillation frequency of the same order is linearly related to the speed, and the shear oscillation frequency of the same speed is proportional to the order;

[0134] Finding a shear oscillation frequency equal to a target piston frequency from at least one order of shear oscillation frequencies of at least one cavity at each ship speed;

[0135] For each shear oscillation frequency equal to the target piston frequency, the ship speed corresponding to the current shear oscillation frequency is used as the ship speed to be measured, and according to the noise amplitude collected by the target hydrophone at the target piston frequency during the navigation of the underwater vehicle at the target water depth, the ship speed to be measured and its adjacent ship speeds, it is judged whether the current shear oscillation frequency meets the resonance condition, wherein the resonance condition includes: the difference between the average value of the noise amplitude corresponding to the ship speed to be measured and the average value of the noise amplitude corresponding to the adjacent ship speed is greater than or equal to a preset threshold;

[0136] Determine any shear oscillation frequency that meets the resonance condition as the target shear oscillation frequency, and determine the corresponding speed and order as the target speed and target order;

[0137] The target size is calculated based on the target speed, target order and target shear oscillation frequency;

[0138] Around the target hydrophone, the air-liquid cavity whose absolute value of the difference between the opening size in the flow direction and the target size is within the error range is determined as the sound source.

[0139] Furthermore, in one embodiment, the positioning module is used to:

[0140] The noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds are converted from the time domain to the frequency domain to obtain a second noise spectrum, the second noise spectrum is stored as a second matrix, and the second matrix is ​​plotted as a frequency-speed cloud diagram;

[0141] Draw a second target oblique line on the frequency-speed cloud diagram, wherein each second target oblique line passes through a local peak area of ​​the noise amplitude at all speeds, and the frequency corresponding to the local peak area changes with the speed;

[0142] If there is only one second target oblique line, the first-order shear oscillation frequency of a cavity at each ship speed is determined according to the second target oblique line;

[0143] If there are multiple second target oblique lines, the second target oblique lines are grouped according to the ratio of the slopes, and the first to Nth order oscillation frequencies of a cavity at each speed are determined according to a group of second target oblique lines, wherein, in the slopes of a group of second target oblique lines, the ratio of the maximum value to each value is 1 to N, and N is a positive integer.

[0144] Furthermore, in one embodiment, the positioning module is used to:

[0145] Draw a target straight line with a frequency equal to the target piston frequency on the frequency-speed cloud diagram;

[0146] Find the shear oscillation frequency of the second target oblique line intersecting the target straight line at the intersection of the two.

[0147] Furthermore, in one embodiment, the gas-liquid cavity piston frequency identification and positioning device further includes a collection module for:

[0148] In a single voyage, the underwater vehicle is controlled to naturally decelerate from the maximum speed to zero at different preset water depths, and noise data is collected through multiple hydrophones at different positions, where the target water depth is one of the preset water depths.

[0149] Furthermore, in one embodiment, the target size is calculated as follows: ;

[0150] Among them, L is the target size, a is a constant with a value range of [0.47, 0.53], n is the target order, U is the target speed, and f is the target shear oscillation frequency.

[0151] Furthermore, in one embodiment, the number of hydrophones on the underwater vehicle is greater than or equal to 3, the multiple hydrophones are arranged along the bow-midship-stern direction, and the interval between adjacent hydrophones is less than or equal to 10 m.

[0152] Furthermore, in one embodiment, the positioning module is used to:

[0153] For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency;

[0154] comparing the noise amplitudes collected by a plurality of hydrophones at different positions at the target piston frequency during the navigation of the underwater vehicle at the target water depth, and determining the hydrophone with the largest noise amplitude as the first hydrophone;

[0155] A second hydrophone is arranged next to each air-liquid cavity around the first hydrophone;

[0156] The noise amplitudes collected by multiple second hydrophones at the target piston frequency during the navigation of the underwater vehicle at the target water depth are compared, and the air-liquid cavity next to the second hydrophone with the largest noise amplitude is determined as the sound source.

[0157] Among them, the functional implementation of each module in the above-mentioned gas-liquid cavity piston frequency identification and positioning device corresponds to the various steps in the above-mentioned gas-liquid cavity piston frequency identification and positioning method embodiment, and its functions and implementation processes will not be repeated here one by one.

[0158] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0159] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0160] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0161] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; the “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0162] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0163] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0164] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for frequency identification and positioning of a gas-liquid cavity piston, characterized in that: The gas-liquid cavity piston frequency identification and positioning method comprises: Analyze the noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths according to a first preset rule, and determine the piston frequency of at least one gas-liquid cavity at each water depth, wherein the first preset rule includes: the noise amplitude of the piston frequency at the same water depth is a local peak value, and for the same gas-liquid cavity, the piston frequency is linearly related to the water depth; The sound source is localized based on the piston frequency of the gas-liquid cavity identified from the noise data.

2. The gas-liquid cavity piston frequency identification and positioning method according to claim 1, characterized in that: The step of analyzing the noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths according to the first preset rule to determine the piston frequency of at least one gas-liquid cavity at each water depth comprises: The noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths is converted from the time domain to the frequency domain to obtain a first noise spectrum, the first noise spectrum is stored as a first matrix, and the first matrix is ​​plotted as a frequency-water depth cloud diagram; Draw a first target oblique line on the frequency-water depth cloud map, wherein each first target oblique line passes through a local peak area of ​​the noise amplitude at all water depths, and the frequency corresponding to the local peak area changes with the water depth; The piston frequency of a corresponding gas-liquid cavity at each water depth is determined according to each first target oblique line.

3. The gas-liquid cavity piston frequency identification and positioning method according to claim 1, characterized in that: The step of locating the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data comprises: For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency; Comparing the noise amplitudes collected by multiple hydrophones at different positions of the underwater vehicle at the target piston frequency during navigation at the target water depth, and determining the hydrophone with the largest noise amplitude as the target hydrophone; Analyze the noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds according to the second preset rule, and determine the shear oscillation frequency of at least one order of at least one cavity at each speed, wherein the second preset rule includes: the noise amplitude of the shear oscillation frequency at the same speed is a local peak value, for the same cavity, the shear oscillation frequency of the same order is linearly related to the speed, and the shear oscillation frequency of the same speed is proportional to the order; Finding a shear oscillation frequency equal to a target piston frequency from at least one order of shear oscillation frequencies of at least one cavity at each ship speed; For each shear oscillation frequency equal to the target piston frequency, the ship speed corresponding to the current shear oscillation frequency is used as the ship speed to be measured, and according to the noise amplitude collected by the target hydrophone at the target piston frequency during the navigation of the underwater vehicle at the target water depth, the ship speed to be measured and its adjacent ship speeds, it is judged whether the current shear oscillation frequency meets the resonance condition, wherein the resonance condition includes: the difference between the average value of the noise amplitude corresponding to the ship speed to be measured and the average value of the noise amplitude corresponding to the adjacent ship speed is greater than or equal to a preset threshold; Determine any shear oscillation frequency that meets the resonance condition as the target shear oscillation frequency, and determine the corresponding speed and order as the target speed and target order; The target size is calculated based on the target speed, target order and target shear oscillation frequency; Around the target hydrophone, the air-liquid cavity whose absolute value of the difference between the opening size in the flow direction and the target size is within the error range is determined as the sound source.

4. The gas-liquid cavity piston frequency identification and positioning method according to claim 3, characterized in that: The step of analyzing the noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds according to the second preset rule to determine at least one order of shear oscillation frequency of at least one cavity at each speed includes: The noise data collected by the target hydrophone during the navigation of the underwater vehicle at the target water depth and different speeds are converted from the time domain to the frequency domain to obtain a second noise spectrum, the second noise spectrum is stored as a second matrix, and the second matrix is ​​plotted as a frequency-speed cloud diagram; Draw a second target oblique line on the frequency-speed cloud diagram, wherein each second target oblique line passes through a local peak area of ​​the noise amplitude at all speeds, and the frequency corresponding to the local peak area changes with the speed; If there is only one second target oblique line, the first-order shear oscillation frequency of a cavity at each ship speed is determined according to the second target oblique line; If there are multiple second target oblique lines, the second target oblique lines are grouped according to the ratio of the slopes, and the first to Nth order oscillation frequencies of a cavity at each speed are determined according to a group of second target oblique lines, wherein, in the slopes of a group of second target oblique lines, the ratio of the maximum value to each value is 1 to N, and N is a positive integer.

5. The gas-liquid cavity piston frequency identification and positioning method according to claim 4, characterized in that: The step of searching for a shear oscillation frequency equal to a target piston frequency from at least one order of shear oscillation frequencies of at least one cavity at each ship speed comprises: Draw a target straight line with a frequency equal to the target piston frequency on the frequency-speed cloud diagram; Find the shear oscillation frequency of the second target oblique line intersecting the target straight line at the intersection of the two.

6. The gas-liquid cavity piston frequency identification and positioning method according to claim 3, characterized in that: Before the step of analyzing the noise data collected by a single hydrophone during the navigation of the underwater vehicle at different water depths according to the first preset rule to determine the piston frequency of at least one gas-liquid cavity at each water depth, the step further includes: In a single voyage, the underwater vehicle is controlled to naturally decelerate from the maximum speed to zero at different preset water depths, and noise data is collected through multiple hydrophones at different positions, where the target water depth is one of the preset water depths.

7. The gas-liquid cavity piston frequency identification and positioning method according to claim 3, characterized in that: The target size is calculated as ; Among them, L is the target size, a is a constant with a value range of [0.47, 0.53], n is the target order, U is the target speed, and f is the target shear oscillation frequency.

8. The gas-liquid cavity piston frequency identification and positioning method according to claim 3, characterized in that: The number of the hydrophones on the underwater vehicle is greater than or equal to 3, the multiple hydrophones are arranged along the bow-midship-stern direction, and the interval between adjacent hydrophones is less than or equal to 10m.

9. The gas-liquid cavity piston frequency identification and positioning method according to claim 1, characterized in that: The step of locating the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data comprises: For each gas-liquid cavity identified from the noise data, the piston frequency at the target water depth is determined as the target piston frequency; comparing the noise amplitudes collected by a plurality of hydrophones at different positions at the target piston frequency during the navigation of the underwater vehicle at the target water depth, and determining the hydrophone with the largest noise amplitude as the first hydrophone; A second hydrophone is arranged next to each air-liquid cavity around the first hydrophone; The noise amplitudes collected by multiple second hydrophones at the target piston frequency during the navigation of the underwater vehicle at the target water depth are compared, and the air-liquid cavity next to the second hydrophone with the largest noise amplitude is determined as the sound source.

10. A gas-liquid cavity piston frequency identification and positioning device, characterized in that: The gas-liquid cavity piston frequency identification and positioning device comprises: an identification module, configured to analyze noise data collected by a single hydrophone during navigation of the underwater vehicle at different water depths according to a first preset rule, and determine a piston frequency of at least one gas-liquid cavity at each water depth, wherein the first preset rule includes: a noise amplitude of the piston frequency at the same water depth is a local peak value, and for the same gas-liquid cavity, the piston frequency is linearly related to the water depth; The positioning module is used to locate the sound source according to the piston frequency of the gas-liquid cavity identified from the noise data.

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