Acoustic holography and acoustic array mutual radiation impedance measurement method based on equivalent source method
By using a near-field acoustic holography method with an equivalent source inside the sound source, the near-field radiated sound field of the transducer array is reconstructed, solving the accuracy problem of transducer array mutual radiation impedance measurement under high power and improving design efficiency and accuracy.
Patent Information
- Application Number
- CN202511107112.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-08
- Publication Date
- 2026-01-13
AI Technical Summary
Existing technologies cannot accurately measure the mutual radiation impedance of transducer arrays at high power. Traditional methods are prone to damaging equipment and have complex errors. Near-field acoustic holography has many error factors and is difficult to meet practical needs.
A near-field acoustic holography method based on the equivalent source method is adopted. By arranging equivalent sources inside the target sound source, matching the sound pressure of the holographic surface to solve the source strength of the equivalent source, the near-field radiation sound field information of the transducer array is reconstructed, and the mutual radiation impedance is accurately evaluated.
It improves the accuracy of transducer array mutual radiation impedance measurement under high power, solves the problem of insufficient resolution and stability of conventional Fourier transform reconstruction algorithm, provides design parameters, and improves the design efficiency of transducer array.
Smart Images
Figure CN121328169A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of underwater acoustic sensor parameter testing, and particularly relates to a sound array mutual radiation impedance measurement method based on an equivalent source method. BACKGROUND
[0002] In the field of underwater acoustics, with the need for underwater long-range detection, the transmitting transducer array develops in the direction of low frequency, large size and large power, which determines that the transducer array elements need to be densely arranged to achieve greater transmitting power in limited space. The dense arrangement of the array elements will interact between the array elements, thereby affecting the performance of the transducer array and causing the technical and tactical indicators to be unable to be achieved, and even causing damage to the transducer array in serious cases. Therefore, it is necessary to carry out testing and evaluation of the mutual radiation impedance characteristics of the transducer array elements to provide design parameters for speed control of the transducer array. The traditional transducer array mutual radiation testing and analysis method is mainly to measure the radiation impedance, and the commonly used methods include impedance analysis method, three-voltage method and vector decomposition method. There is also a method of measuring the vibration distribution on the surface of the array element by using a vibration sensor. These methods all belong to the intrusive type and can only be used at low power, but cannot reflect the actual working condition of the transducer array. At high power, the test equipment is easily damaged. Therefore, the transducer array radiation impedance testing at actual high power is rarely used, and the non-intrusive method is mostly used abroad, in which the near-field acoustic holography method is mostly used. However, the error factors caused by the near-field acoustic holography method are complex, and the problem of accurate analysis of the measurement error of the near-field acoustic holography method needs to be solved. SUMMARY
[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a sound array mutual radiation impedance measurement method based on an equivalent source method.
[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a sound array mutual radiation impedance measurement method based on an equivalent source method, the steps of which are as follows: (1) An equivalent source acoustic model is established for a measured transmitting array object; (2) Equivalent sources are arranged inside a target sound source, and the equivalent source source strength is solved by matching the measured sound pressure of a holographic surface, so as to realize space sound field transformation; (3) The near-field radiation sound field information of the transmitting transducer array is reconstructed by using the equivalent source method, and accurate evaluation of the mutual radiation impedance of the transducer array elements is realized.
[0005] In some embodiments, according to step (2), the array type of the equivalent sources arranged inside the target sound source corresponds to the array type of the equivalent source acoustic model established for the measured transmitting array object.
[0006] In some embodiments, the equivalent source inside the target sound source is matched with the measured near-field sound pressure.
[0007] In some embodiments, the object under test is working underwater, and the normal vibration of the transducer's outer surface is not constant. Therefore, the impedance cannot be calculated in the form of a planar piston, and the outer surface of the transducer needs to be discretized.
[0008] In some embodiments, the specific algorithm steps are as follows: Let L be the number of elements in the hydrophone array. Then, the holographic sound pressure measured on the holographic surface H in the near-field region of the low-frequency large-size transmitting array is... It can be represented as: (1) Suppose that each transducer has W equivalent sources distributed inside, and the number of transducers under test is M. Then the total number of equivalent sources in the model is N = M × W, and the vector composed of the source intensities of these equivalent sources is... It can be represented as: (2) In the formula, the subscript E indicates that all these equivalent sources are on the equivalent source surface E; According to the equivalent source method, the sound field generated by a vibrating body can be replaced by the superposition of sound fields generated by a series of equivalent sources placed inside the vibrating body. Therefore, the holographic surface sound pressure measured by the hydrophone array... The relationship between the equivalent source strength and the equivalent source strength is as follows: (3) in, For the transfer function, under free field conditions, its specific expression is: (4) Based on relation (3), the transfer relationship between the holographic surface sound pressure column vector and the equivalent source strength column vector can be established. (5) in, Let be the L×N transfer matrix composed of transfer functions.
[0009] After obtaining the equivalent source strength column vector Then, combining the sound pressure-velocity transfer function matrix, the first... n Normal vibration velocity on the surface of transducer No. (6) In the formula This represents a point on surface S of the nth transducer; The normal derivative of the Green's function of the free field on the transducer surface S is denoted by . Will Intermediate sources are grouped according to their respective transducers; (7) from Take out separately and arrange in the first n The equivalent sources inside the transducer Then use Reconstructing the first by combining the free field Green's function n Transducer No. 1 i Sound pressure distribution generated on the surface of transducer No. 1 : (8) get Then, according to the first i Discrete cases of M small regions on the outer surface of transducer No. 1, Sound pressure levels divided into M small regions , Thus obtaining the first n Transducer No. 1 i The first transducer surface m The acoustic radiation pressure generated in a small area; similarly, the acoustic radiation pressure obtained from the previous reconstruction... n Normal vibration velocity on the surface of transducer No. Divide the surface of the i-th transducer to obtain the first... m Vibration velocity in a small area Then calculate the first according to formula (9). n The mutual radiation impedance of sound source i to sound source i , (9)
[0010] Compared with existing technologies, the beneficial effects of this invention are: a method for measuring the mutual radiation impedance characteristics of acoustic array elements using a non-invasive equivalent source near-field acoustic holography method under high power conditions. It achieves this through equivalent source reconstruction of the near-field radiated acoustic field information of the acoustic array, solving the problems of insufficient resolution and stability in conventional Fourier transform reconstruction algorithms, and improving the accuracy of measuring the mutual radiation impedance characteristics of acoustic array elements. This enables accurate evaluation of the mutual radiation impedance of low-frequency, high-power active transducer arrays, providing element velocity control parameters for the design of novel transducer arrays, and improving the design efficiency and level of transducer arrays.
[0011] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. The embodiments of this application will provide a detailed description and understanding of the application. Attached Figure Description
[0012] Figure 1 A flowchart for measuring the cross-radiation impedance of a transducer array based on near-field acoustic holography; Figure 2 A roadmap for near-field acoustic holography based on the equivalent source method in non-free space; Figure 3 This is a schematic diagram of the calculation model for the mutual radiation impedance between transducer array columns. Detailed Implementation
[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0014] To address the problem of accurate testing of the mutual radiation impedance of transducer array elements under low-frequency, high-power conditions using near-field acoustic holography, and considering the insufficient resolution of existing Fourier transform-based reconstruction algorithms, this invention proposes a method for measuring the mutual radiation impedance of acoustic arrays based on equivalent source near-field acoustic holography. This method solves the problems of insufficient resolution and stability of conventional Fourier transform reconstruction algorithms, and improves the accuracy of measuring the mutual radiation impedance characteristics of acoustic array elements.
[0015] Principle of near-field acoustic holography for measuring the mutual radiation impedance of transducer array elements: Measuring the mutual radiation impedance of transducer array elements using near-field acoustic holography requires calculating the mutual radiation impedance of the transducer array elements based on the classical theory of acoustic array mutual radiation impedance. The specific measurement process is as follows: Figure 1 As shown.
[0016] Near-field information of the radiated sound field of the transducer array under test is obtained by measuring the scanning of the hydrophone array. Then, the acoustic quantities of the source surface sound field are reconstructed using the near-field measurement data. This yields the complex sound pressure and normal velocity distribution of the source surface of the transducer array elements, as well as the total complex sound pressure and complex velocity distribution generated by other array elements on its radiation. Thus, the self-radiation impedance of the array elements and the mutual radiation impedance between array elements are obtained. The specific method is as follows: Assume the transducer array consists of N elements, each element being... The vibration velocity of the transducer array then the first n The array element is paired with the first i The mutual radiation impedance of the array elements It can be defined as the first n The sound pressure radiated by the array element is at the... i Force generated on the surface of the array element With the i Normal vibration velocity of array element The ratio, i.e. (1) From the relationship between force and pressure, we can know that Through the first n The array element is in the... i Sound pressure distribution generated on the surface of the array element The integral of the surface S of the antagonistic element radiation is obtained as follows: (2) Substituting equation (1) into equation (2), we get the first... n The array element is paired with the first i The mutual radiation impedance of the array elements It can be represented as (3) when n = i When, formula (3) is the first... i The self-radiation impedance of the array element is used as follows: express.
[0017] The first transducer array i The mutual radiation impedance of the array elements can be expressed as: (4) Arbitrary array element on transducer array i The radiation impedance is: (5) As can be seen from the above principles, as long as the complex vibration velocity, complex sound pressure distribution and radiation sound pressure generated by other array elements at the position of the array element are measured, the self-radiation impedance and mutual radiation impedance of each array element can be obtained by formulas (4) and (5).
[0018] Impedance measurement principle based on equivalent source (ESM) near-field acoustic holography Conventional near-field acoustic holography algorithms are based on Fourier algorithms. However, the conventional Fourier algorithm has a significant drawback: its reconstruction resolution is not high, which can easily lead to errors in the reconstruction algorithm. To address this issue, a near-field acoustic holography reconstruction algorithm based on the equivalent source method is proposed. This algorithm improves the resolution of the reconstructed sound field and the stability of the algorithm, and enables accurate evaluation of the mutual radiation impedance of the acoustic array.
[0019] In practical engineering applications, the free-field conditions required for holographic measurement are often unsatisfactory. To ensure the accuracy and validity of NAH measurement data, the finite element method is used to obtain the sound field of a virtual point source in a finite space. The sound field data on the holographic surface is extracted as input to obtain the Green's function at each point on the holographic surface of the virtual point source in space. Then, a near-field acoustic holography algorithm based on the equivalent source method is used to obtain the source intensity of each equivalent source, realizing the reconstruction of the sound field in the free field. The technical route is as follows: Figure 2 As shown.
[0020] The main idea of ESM-based NAH is that the sound field generated by a vibrating body can be replaced by the superposition of sound fields generated by a series of equivalent sources placed inside the vibrating body. The source strength of these equivalent sources can be obtained by matching the normal velocity of the vibrating body surface or the holographic surface sound pressure in the sound field. Therefore, using ESM-based NAH requires arranging equivalent sources inside the target sound source, and solving for the source strength of the equivalent sources by measuring the sound pressure of the holographic surface, thereby realizing the spatial sound field transformation and solving for the sound field intensity. as well as Equal acoustic quantities are used to calculate the acoustic radiation impedance characteristics of the transmitting array. Therefore, based on the characteristics of the tested transmitting array structure and its transducer acoustic radiation surface being lateral, a method is established as follows: Figure 3 The acoustic model for impedance measurement of the transducer array shown is as follows: The transducer array under test, consisting of two sets of transducers, is located in a free field space filled with a medium (water), with the origin of the coordinate system located at the center of the array. The hydrophone array being measured is located in the near-field radiation region of the transducer array under test. Since the transducers radiate sound waves both in front of and behind them, the hydrophone array must completely cover the two main radiation regions in front of and behind the transducer array under test.
[0021] Assuming a transducer array consisting of N transducer elements operates in water and radiates a sound field, since the normal vibration velocity of the transducer's outer surface is not constant, impedance calculation cannot be performed using a planar piston approach. Therefore, the transducer's outer surface needs to be discretized, such as... Figure 3 As shown.
[0022] Assume that the outer surface of each transducer element in the transducer array is discretized into M small regions. Since the discretized regions are small, their normal vibration velocities can be considered constant. Then the... n Transducer No. 1 for the first i On the No. 1 transducer m mutual radiation impedance of a small region It can be defined as the first n The radiated sound pressure of the transducer is at the [number]th [number]. i The surface of transducer No. 1 m Force generated in a small area With the i The sound source m Vibration velocity in a small area The ratio, i.e. (6) Thus, the first n Transducer No. 1 for the first i The mutual radiation impedance of the transducer can be obtained from the first... n The sound source is the first i The summation of the mutual radiation impedance of all small regions on the transducer is obtained by... (7) From equations (6) and (7), it can be seen that the requirement is... First, we need to find the first... n The force generated by the radiated sound pressure of transducer i on all small areas of the surface of transducer i. and the i The surface normal vibration velocity of all discrete small regions on the transducer. From the relationship between force and pressure, we can know that... Through the first n Transducer No. 1 i The surface of transducer No. 1 m Sound pressure distribution in a small area For the m The surface of a small area The integral yields: (8) Therefore, we obtain the first... n Transducer No. 1 for the first i Mutual radiation impedance of transducer No. It can be represented as: (9) As can be seen from equation (9), to accurately measure mutual radiation impedance... It needs to be obtained precisely. i Normal vibration velocity of all small areas on the surface of the transducer and the n Transducer No. 1 i The sound pressure generated on all small areas of the transducer surface Since the sum of all the discrete small regions constitutes the outer surface of the transducer, the practical requirement is to accurately obtain... i Surface normal vibration velocity of transducer No. and the n Transducer No. 1 i Transducer surface distribution .
[0023] Because there are multiple transmitting array elements, therefore the first i The surface acoustic pressure of a single transducer is the sum of the sound pressures generated by all transducers, and cannot be directly measured by a sensor. ;and The measurement needs to be performed in water using a non-contact method, which is quite difficult in practice. To solve the above problem, a near-field acoustic holography (NAH) technique based on the equivalent source method (ESM) is proposed, which can be used for sound sources of arbitrary shapes. as well as The problem of accurate acquisition.
[0024] Using the ESM-based NAH method requires placing an equivalent source inside each transducer of the transducer array under test, such as... Figure 3 The blue dot located inside the array transducer is a grid surface formed by the equivalent source that conforms to the geometry of the transducer surface under test. In the near-field acoustic holographic calculation based on the ESM method, the sound field radiated by each transducer unit under test can be considered as being generated by the equivalent source arranged inside it, thus forming a multi-source mixed field NAH model. After obtaining the source strength of all equivalent sources using the ESM method, the radiated sound pressure of a transducer working alone can be separated by extracting the source strength of the equivalent sources contained inside a certain transducer. Then, combined with the surface normal vibration velocity obtained by NAH reconstruction, the mutual radiation impedance can be calculated according to Equation (9), realizing the indirect measurement of mutual radiation impedance.
[0025] The specific algorithm steps for measuring the radiation impedance of a transmitter array based on the equivalent source method are as follows: Based on the ESM-based acoustic model of the transmitter array, the solution is obtained for the... n Transducer No. 1 for the first i Taking the mutual radiation impedance of the transducer as an example, this paper details the algorithm process for solving the mutual radiation impedance using NAH based on ESM. Figure 3 As shown.
[0026] Let the hydrophone array elements be (from) Figure 3 The red asterisks in the middle indicate the number L), then the holographic sound pressure measured on the holographic surface H in the near-field region of the low-frequency large-size transmitting array of the hydrophone array. It can be represented as: (10) Suppose that each transducer has W equivalent sources distributed inside, and the number of transducers under test is M. Then the total number of equivalent sources in the model is N = M × W, and the vector composed of the source intensities of these equivalent sources is... It can be represented as: (11) The subscript E in the formula indicates that all these equivalent sources are on the equivalent source surface E.
[0027] According to the equivalent source method, the sound field generated by a vibrating body can be replaced by the superposition of sound fields generated by a series of equivalent sources placed inside the vibrating body. Therefore, the holographic surface sound pressure measured by the hydrophone array... The relationship between the equivalent source strength and the equivalent source strength is as follows: (12) in, For the transfer function, under free field conditions, its specific expression is: (13) Based on relation (12), the transfer relationship between the holographic surface sound pressure column vector and the equivalent source strength column vector can be established. (14) in, Let be the L×N transfer matrix composed of transfer functions.
[0028] After obtaining the equivalent source strength column vector Then, combining the sound pressure-velocity transfer function matrix, the first... n Normal vibration velocity on the surface of transducer No. (15) In the formula This represents a point on surface S of the nth transducer; Let S represent the normal derivative of the Green's function of the free field on the transducer surface S.
[0029] To calculate the first n Transducer No. 1 for the first i The mutual radiation impedance of the first transducer also needs to be obtained. n Transducer No. 1 i Sound pressure distribution generated on the surface of transducer No. 1 This means that other transducers need to be removed in the first... i The sound pressure generated on the surface of the transducer. Therefore, the calculated equivalent source strength cannot be directly used. Instead of performing sound pressure reconstruction, it is necessary to... Intermediate sources are grouped according to their respective transducers.
[0030] (16) from Take out separately and arrange in the first n The equivalent sources inside the transducer Then use Reconstructing the first by combining the free field Green's function n Transducer No. 1 i Sound pressure distribution generated on the surface of transducer No. 1 : (17) get Then, according to the first iDiscrete cases of M small regions on the outer surface of transducer No. 1, Sound pressure levels divided into M small regions , Thus obtaining the first n Transducer No. 1 i The first transducer surface m The acoustic radiation pressure generated in a small area. Similarly, for the previously reconstructed... n Normal vibration velocity on the surface of transducer No. Divide the surface of the i-th transducer to obtain the first... m Vibration velocity in a small area Then calculate the first according to formula (18). n The mutual radiation impedance of sound source i to sound source i .
[0031] (18) This invention has been successfully applied multiple times to the mutual radiation impedance testing of low-frequency high-power underwater acoustic transmitter arrays, providing velocity control parameters for the design of various active sonar arrays, providing evaluation technology support for the improvement of new active transducer arrays, and solving the methodological problem required for evaluating the mutual radiation impedance of acoustic arrays under high power.
[0032] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for measuring the mutual radiation impedance of a acoustic holographic array based on the equivalent source method, characterized in that: The steps are as follows: (1) Establish an equivalent source acoustic model for the transmitted array under test; (2) Arrange an equivalent source inside the target sound source, and solve the source strength of the equivalent source by measuring the sound pressure of the matched holographic surface, thereby realizing the spatial sound field transformation; (3) The near-field radiation acoustic field information of the transmitting transducer array is reconstructed using the equivalent source method to achieve accurate evaluation of the mutual radiation impedance of the transducer array elements.
2. The method for measuring the mutual radiation impedance of a acoustic holographic array based on the equivalent source method according to claim 1, characterized in that: According to step (2), the equivalent source array arranged inside the target sound source corresponds to the array of the equivalent source acoustic model established for the tested emission array object.
3. The method for measuring the mutual radiation impedance of a acoustic holographic array based on the equivalent source method according to claim 2, characterized in that: The equivalent source inside the target sound source is matched with the measured near-field sound pressure.
4. The method for measuring the mutual radiation impedance of a acoustic holographic array based on the equivalent source method according to claim 3, characterized in that: The object under test is working underwater, and the normal vibration of the transducer's outer surface is not constant. Therefore, the impedance cannot be calculated in the form of a planar piston, and the outer surface of the transducer needs to be discretized.
5. The method for measuring the mutual radiation impedance of a acoustic holographic array based on the equivalent source method according to claim 4, characterized in that: The specific algorithm steps are as follows: Let L be the number of elements in the hydrophone array. Then, the holographic sound pressure measured on the holographic surface H in the near-field region of the low-frequency large-size transmitting array is... It can be represented as: （1） Suppose that each transducer has W equivalent sources distributed inside, and the number of transducers under test is M. Then the total number of equivalent sources in the model is N = M × W, and the vector composed of the source intensities of these equivalent sources is... It can be represented as: (2) In the formula, the subscript E indicates that all these equivalent sources are on the equivalent source surface E; According to the equivalent source method, the sound field generated by a vibrating body can be replaced by the superposition of sound fields generated by a series of equivalent sources placed inside the vibrating body. Therefore, the holographic surface sound pressure measured by the hydrophone array... The relationship between the equivalent source strength and the equivalent source strength is as follows: （3) in, For the transfer function, under free field conditions, its specific expression is: (4) Based on relation (3), the transfer relationship between the holographic surface sound pressure column vector and the equivalent source strength column vector can be established. (5) in, Let be the L×N transfer matrix composed of transfer functions. After obtaining the equivalent source strength column vector Then, combining the sound pressure-velocity transfer function matrix, the first... n Normal vibration velocity on the surface of transducer No. (6) In the formula This represents a point on surface S of the nth transducer; The normal derivative of the Green's function of the free field on the transducer surface S is denoted by . Will Intermediate sources are grouped according to their respective transducers; (7) from Take out separately and arrange in the first n The equivalent sources inside the transducer Then use Reconstructing the first by combining the free field Green's function n Transducer No. 1 i Sound pressure distribution generated on the surface of transducer No. 1 : (8) get Then, according to the first i Discrete cases of M small regions on the outer surface of transducer No. 1, Sound pressure levels divided into M small regions , Thus obtaining the first n Transducer No. 1 i The first transducer surface m The acoustic radiation pressure generated in a small area; similarly, the acoustic radiation pressure obtained from the previous reconstruction... n Normal vibration velocity on the surface of transducer No. Divide the surface of the i-th transducer to obtain the first... m Vibration velocity in a small area Then calculate the first according to formula (9). n The mutual radiation impedance of sound source i to sound source i , (9)。