Complex moving sound source simulation method based on moving monopole and dipole sound sources

Abstract

A method for simulating complex moving sound sources based on the superposition of moving monopoles and dipoles, including: simulating the Doppler effect caused by movement; constructing wave equations of moving monopoles and dipoles; deriving analytical solutions of moving monopole and dipole sound sources through Lorentz transformation; simulating complex moving sound sources based on the superposition principle. The invention can realize the simulation of complex sound sources superimposed by any combination of monopole sources and dipole sources; using Lorentz transformation and coordinate system conversion as tools, it provides new ideas and solutions for the simulation of sound field distribution of complex moving sound sources.

Description

Technical Field

[0001] The invention belongs to the technical field of marine engineering, and in particular relates to a sound source simulation method based on moving monopoles and dipoles, which is suitable for acoustic simulation of complex moving underwater sound sources. Background Art

[0002] In the field of underwater acoustic engineering, underwater target positioning plays a vital role, and the study of moving target radiation is particularly interesting. In this field, the ranging and azimuth estimation technology of underwater moving target noise has attracted widespread attention, among which the equivalent source method stands out due to its simplicity and efficiency. However, the main problem with the current equivalent source method is that it requires a large number of point sources, and most of them are based on monopole sound source theory. Therefore, how to further explore the dipole sound source theory and its calculation, and how to reduce the number of basic sound sources to improve efficiency and practicality has become an urgent problem to be solved in the field of underwater acoustic engineering.

[0003] At the same time, target motion analysis is also crucial in the field of underwater acoustic engineering. Target motion analysis is committed to determining the motion parameters of unknown targets in order to achieve accurate target positioning and tracking. Traditional motion analysis and positioning techniques for underwater targets usually rely on active positioning methods. This type of method uses an active source to emit a directional beam to the underwater target and extract the target motion information from the echo signal. Although this method has high accuracy and feasibility, its inherent problem of reduced concealment cannot be ignored. As an alternative, passive acoustic detection technology uses the noise characteristics released by underwater targets to obtain necessary information including position and motion. Due to its enhanced concealment and practicality, this method has attracted widespread attention from researchers at home and abroad. However, it is worth noting that the movement of the target will cause the radiated and scattered sound fields to produce Doppler frequency shift, which is particularly important in passive acoustic detection technology. Summary of the invention

[0004] In view of the deficiencies in the prior art and the characteristics of Doppler frequency shift of the sound field due to target motion, the present invention proposes a complex moving sound source simulation method based on the superposition of moving monopoles and dipoles, which can simulate complex moving sound sources and freely control the positions and distribution arrangements of monopole sound sources and dipole sound sources.

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

[0006] A complex moving sound source simulation method based on the superposition of moving monopoles and dipoles, comprising:

[0007] Simulate the Doppler effect due to motion;

[0008] Construct wave equations for moving monopoles and dipoles;

[0009] Derivation of analytical solutions for moving monopole and dipole sound sources via Lorentz transformation;

[0010] Simulate complex moving sound sources based on the superposition principle.

[0011] The working principle of the present invention is that the relative movement of the sound source affects the distribution of the sound field, and this phenomenon can be used to identify the motion state of the sound source. Based on the Lorentz transformation, the calculation formulas and analytical solutions for the sound field radiated by a single moving monopole sound source and a dipole sound source are derived respectively. Based on the superposition principle of the sound field, by reasonably setting a combination of moving monopole and dipole sound sources with arbitrary parameters, the sound field of a complex moving sound source can be effectively simulated.

[0012] A complex moving sound source simulation method based on the superposition of moving monopoles and dipoles specifically comprises the following steps:

[0013] S1. Establish two reference systems: global coordinate system and motion coordinate system;

[0014] S2. Construct the wave equations of moving monopoles and dipoles in the global coordinate system;

[0015] S3. Transform the wave equation into a motion coordinate system through Lorentz transformation and obtain the analytical solution of the wave equation based on parameter substitution;

[0016] S4. Obtain the analytical solution of the wave equations of moving monopoles and dipoles in the global coordinate system by inverse transformation;

[0017] S5. Perform simulation analysis on the obtained analytical solution of the sound field distribution, compare the Doppler effect caused by the motion at different times and speeds, and obtain the simulation model of the moving monopole and dipole;

[0018] S6. Based on the obtained model of moving monopoles and dipoles, any complex moving sound source can be simulated based on the superposition principle.

[0019] Preferably, the complex motion sound source can be formed by the superposition of a moving monopole sound source and a moving dipole sound source. The monopole sound source can be regarded as a mass source, and its intensity is determined by the homeotropic flow rate generated by the sound source; the dipole sound source can be regarded as a time-dependent force applied to a certain point in the fluid medium, causing the disturbances on both sides of the oscillating ball to exhibit opposite phases.

[0020] Preferably, the moving coordinate system in step S1 refers to a coordinate system that moves with the monopole or dipole sound source; the global coordinate system is a stationary coordinate system that does not move with the sound source and can truly reflect the sound field distribution.

[0021] Preferably, the Lorentz transformation in step S3 refers to the conversion relationship performed when an observer measures physical quantities between different inertial reference systems, which is mathematically expressed as a set of equations. The Lorentz transformation establishes a connection between the established global coordinate system and the motion coordinate system. The form of the wave equation in different coordinate systems can be obtained through the transformation, which reflects the close connection between space and time and can reasonably explain the Doppler effect caused by motion.

[0022] Preferably, the analytical solution of the wave equation in step S4 in the global coordinate system is obtained by using a coordinate transformation method under alternative parameters, and then the analytical solution of the moving monopole and dipole wave equation in the global coordinate system is obtained by inverse transformation.

[0023] Preferably, the superposition principle in step S6 includes a single sound source with arbitrary speed, direction of movement, and frequency; and when there are multiple sound sources, the positions and distribution arrangements of monopole sound sources and dipole sound sources.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) Through the Lorentz transformation and parameter transformation methods, the analytical solution of the wave equation of the moving monopole and dipole sound source in the global coordinate system is directly obtained, avoiding complex numerical calculations; the frequency and speed of the sound source can be adjusted arbitrarily, which is convenient for comparing the size of the Doppler frequency shift under different parameter conditions.

[0026] (2) To overcome the limitation of excessive computational complexity of conventional finite element methods, a complex sound source simulation method and related technology based on moving monopoles and dipoles based on the superposition principle are proposed, which can simulate any complex moving sound source and has a high degree of integration and modularity. Compared with the traditional finite element method, the present invention adopts monopoles and dipoles as basic sound sources, providing new ideas and technical solutions for the simulation of complex moving sound sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the complex moving sound source simulation method based on the superposition of moving monopoles and dipoles of the present invention;

[0028] Figure 2 This is an example diagram of constructing the global coordinate system and the motion coordinate system;

[0029] Figure 3 It is a flow chart for solving the wave equation of a moving monopole sound source;

[0030] Figure 4 It is a flow chart for solving the wave equation for a moving dipole sound source;

[0031] Figure 5Schematic diagram of the sound field distribution of a moving sound source at different speeds at the same time, where (a) is the sound field distribution diagram of a moving monopole sound source at speeds of 100m / s, 300m / s, and 500m / s, and (b) is the sound field distribution diagram of a moving dipole sound source at speeds of 100m / s, 300m / s, and 500m / s;

[0032] Figure 6 It is a complex moving sound source simulated sound field generated by the superposition of two monopole sound sources and one dipole sound source, where a is the sound field distribution diagram when the monopole and dipole sound sources move at the same frequency of 5000 Hz, and b is the sound field distribution diagram when the frequency of the dipole sound source is twice the frequency of the monopole sound source, that is, 10000 Hz. DETAILED DESCRIPTION

[0033] The invention scheme of the present invention will be described completely and clearly below in conjunction with the embodiments and drawings, but this should not limit the protection scope of the present invention.

[0034] like Figure 1 As shown, a complex moving sound source simulation method based on the superposition of moving monopoles and dipoles includes the following contents:

[0035] The two coordinate systems used in the present invention are as follows: Figure 2 The global coordinate system is a stationary coordinate system that does not move with the sound source and can truly reflect the distribution of the sound field; the moving coordinate system is a coordinate system that moves with the monopole or dipole sound source.

[0036] Establishment and solution of wave equations. Construct the wave equations of the moving monopole sound source and the moving dipole sound source in the global coordinate system. Transform the wave equation from the global coordinate system to the moving coordinate system through the Lorentz transformation, and solve the equation after substituting variables again.

[0037] Obtain an analytical solution to the wave equation. After obtaining the analytical solution of the wave equation under the newly created variables, perform an inverse transformation on it to obtain its analytical solution in the global coordinate system, which describes the sound field distribution generated by the moving monopole sound source and the dipole sound source. The process of solving the wave equation of the moving monopole sound source described in the present invention is as follows: Figure 3 As shown in the figure, the solution process of the wave equation of the moving dipole sound source is as follows Figure 4 shown.

[0038] The sound field distribution of the moving sound source at different speeds at the same time is obtained. The Doppler frequency shift will change the frequency received by different observation points in the sound field, so the sound field will be distorted to different degrees under different speeds. The sound field distribution diagram of the moving monopole sound source at speeds of 100m / s, 300m / s, and 500m / s is shown in the figure below. Figure 5As shown in (a), the sound field distribution diagram of the moving dipole sound source at speeds of 100m / s, 300m / s, and 500m / s is as follows: Figure 5 (b) The greater the speed of the sound source, the more obvious the Doppler effect. Note that the actual speed of underwater targets is generally no more than 100 m / s. The larger speed is selected to clearly demonstrate the Doppler effect.

[0039] Complex moving sound source simulation. Based on the superposition principle of the sound field, the sound field of complex moving sound sources can be effectively simulated by reasonably setting a combination of moving monopole and dipole sound sources with arbitrary parameters.

[0040] The complex motion sound source may be formed by superposition of a motion monopole sound source and a motion dipole sound source.

[0041] The acoustic monopole sound source can be regarded as a mass source, and its intensity is determined by the down-flow rate generated by the sound source.

[0042] The dipole sound source can be regarded as a time-dependent force exerted on a certain point in the fluid medium, causing the disturbances on both sides of the oscillating ball to exhibit opposite phases.

[0043] The Lorentz transformation refers to the conversion relationship between physical quantities measured by an observer between different inertial reference frames, which is mathematically expressed as a set of equations. The Lorentz transformation establishes a connection between the established global coordinate system and the motion coordinate system. Through the transformation, the form of the wave equation in different coordinate systems can be obtained, which reflects the close connection between space and time and can reasonably explain the Doppler effect caused by motion.

[0044] The Doppler effect means that the received frequency of a wave becomes higher when the wave source moves toward the observer, and the received frequency becomes lower when the wave source moves away from the observer.

[0045] The superposition principle includes a single sound source with any speed, direction of motion, and frequency; and when there are multiple sound sources, the positions and distribution arrangements of the monopole sound source and the dipole sound source are used to simulate complex moving sound sources. The method includes the following steps:

[0046] (1) When a single monopole sound source is used, a global coordinate system and a moving coordinate system are established. The Lorentz transformation and quadratic variable substitution are used to obtain the analytical solution of the wave equation of the moving monopole sound source under the newly created parameters. By inverse variable substitution, its analytical solution in the global coordinate system is obtained, that is, the true distribution of the sound field of the single moving monopole sound source. The speed, direction, frequency and other parameters of the monopole sound source are arbitrarily adjusted, and verification and calibration are performed.

[0047] (2) When there is a single dipole sound source, a global coordinate system and a moving coordinate system are established. The Lorentz transformation and quadratic variable substitution are used to obtain the analytical solution of the wave equation of the moving dipole sound source under the newly created parameters. By inverse variable substitution, its analytical solution in the global coordinate system is obtained, that is, the true distribution of the sound field of a single moving dipole sound source. The parameters such as the speed, direction, vibration frequency, and vibration direction of the dipole sound source can be adjusted arbitrarily, and then tested and calibrated.

[0048] (3) When multiple monopole and dipole sound sources are superimposed, the position and distribution arrangement of each sound source is determined based on the superposition principle of the sound field, and the speed, movement direction, frequency and other parameters of each monopole and dipole sound source are adjusted as required; several sound sources can be directly added or deleted from the system to observe the sound field distribution of complex moving sound sources under different combinations.

[0049] The present invention uses a complex sound source simulation method based on the superposition principle of moving monopoles and dipoles. The analytical solution of the wave equation of the moving monopole and dipole sound source in the global coordinate system is directly obtained, avoiding complex numerical calculations; the frequency and speed of the sound source can be adjusted arbitrarily, which is convenient for comparing the size of the Doppler frequency shift under different parameter conditions, and can realize the simulation of any complex moving sound source, with high integration and modular characteristics.

[0050] Example

[0051] The following is an example of a complex moving sound source simulation using a superposition of moving monopoles and dipoles.

[0052] Two monopole sound sources and one dipole sound source are used as basic sound sources.

[0053] In Example 1, the radiated noise sources at the frequencies of interest under the motion conditions of underwater vehicles can be simulated by moving monopole and dipole sound sources, providing support for structural acoustic stealth and target detection. Taking engineering applications into consideration, a two-dimensional cylindrical transducer with monopole and dipole directivity can be used to simulate the complex sound field characteristics of underwater moving structures by selecting a number of sound sources, operating frequencies, and moving directions. The frequencies of the monopole and dipole sound sources are both 5000 Hz. The two monopole sound sources move in the positive and negative directions of the x-axis, respectively, and the dipole sound source moves in the negative direction of the y-axis. The vibration direction of the dipole sound source is consistent with its motion direction, and the sound field distribution diagram simulated by the complex moving sound source is obtained at this time, as shown in FIG. Figure 6 (a) shown.

[0054] In Example 2, the frequency of the monopole sound source is 5000 Hz, the frequency of the dipole sound source is 10000 Hz, the two monopole sound sources move along the positive and negative directions of the x-axis respectively, the dipole sound source moves along the positive direction of the y-axis, and the vibration direction of the dipole sound source is consistent with its movement direction. The sound field distribution diagram of the complex moving sound source simulation at this time is obtained, as shown in FIG. Figure 6 (b) as shown.

[0055] Description In this embodiment, the simulation of complex moving sound sources based on the superposition of moving monopoles and dipoles can be realized, and parameters such as the moving speed, direction, and frequency can be adjusted arbitrarily.

Claims

1. A method for simulating complex moving sound sources based on the superposition of moving monopoles and dipoles, characterized in that: include: S1. Establish two reference coordinate systems, a global coordinate system and a motion coordinate system, wherein the global coordinate system is stationary and does not move with the sound source, and is used to truly reflect the sound field distribution; the motion coordinate system moves together with the monopole or dipole sound source; S2. Construct the wave equations of the moving monopole and dipole respectively in the global coordinate system; S3. Transform the wave equation into a motion coordinate system through Lorentz transformation and obtain the analytical solution of the wave equation based on parameter substitution; S4. performing an inverse transformation on the analytical solution to obtain analytical solutions of the moving monopole and dipole wave equations in a global coordinate system to describe the sound field distribution generated by the moving monopole sound source and the dipole sound source; S5. Simulate and analyze the sound field distribution, compare the Doppler effect caused by movement at different times and speeds, and obtain the simulation model of the moving monopole and dipole; S6. According to the superposition principle of the sound field, the simulation model of the moving monopole and dipole is set to simulate the sound field of any complex moving sound source.

2. The complex moving sound source simulation method based on the superposition of moving monopoles and dipoles according to claim 1 is characterized in that: The complex motion sound source can be formed by the superposition of a moving monopole sound source and a moving dipole sound source. The monopole sound source can be regarded as a mass source, and its intensity is determined by the homeotropic flow rate generated by the sound source; the dipole sound source can be regarded as a time-dependent force applied to a certain point in the fluid medium, causing the disturbances on both sides of the oscillating ball to show opposite phases.

3. The complex moving sound source simulation method based on the superposition of moving monopoles and dipoles according to claim 1 is characterized in that: The moving coordinate system in step S1 refers to a coordinate system that moves along with the monopole sound source or the dipole sound source.

4. The complex motion sound source simulation method based on the superposition of moving monopoles and dipoles according to claim 1 is characterized in that: The Lorentz transformation in step S3 refers to the conversion relationship performed when an observer measures physical quantities between different inertial reference frames, and is used to measure physical quantities between different inertial reference frames to reflect the Doppler effect caused by motion.

5. The complex moving sound source simulation method based on the superposition of moving monopoles and dipoles according to claim 1 is characterized in that: The analytical solution of the wave equation in step S4 in the global coordinate system is obtained by using the coordinate transformation method under the substitution parameter, and then the analytical solution of the moving monopole and dipole wave equation in the global coordinate system is obtained by inverse transformation.

6. The complex motion sound source simulation method based on the superposition of moving monopoles and dipoles according to claim 1 is characterized in that: In the step S6, any complex moving sound source is constructed based on the superposition principle, including a single sound source with any speed, moving direction, and frequency; and when there are multiple sound sources, the position and distribution arrangement of the monopole sound source and the dipole sound source.

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