Corner reflector, corner reflector and strength evaluation method with acoustic metasurface

Abstract

The present invention relates to a corner reflector, a reflector and an intensity assessment method with an acoustic metasurface, wherein the metasurface is a narrow well acoustic metasurface with a specific gradient, and the corner reflector is a combination of multiple "concave" surfaces. The target intensity assessment method of this article, based on the existing plate element method, combines ray tracing theory to establish a plate element acoustic target intensity calculation model based on ray tracing theory, and develops a fast calculation method for "concave" surface targets of underwater corner reflectors based on improved plate elements. This method can calculate the scattered sound field of underwater corner reflectors, study their acoustic scattering characteristics, and carry out structural design technology of corner reflector groups, echo field reconstruction technology based on spatial strong scattering target characteristics, passive interference and simulation body confrontation effect assessment technology research based on corner reflectors, solve the basic problems of passive interference and simulation body design and application, and realize typical passive interference and model design.

Description

Technical Field

[0001] The present invention relates to the field of underwater acoustic engineering technology, and in particular to a corner reflector with an acoustic metasurface, a reflector, and a target intensity assessment method. Background Art

[0002] In sonar systems, active sonar jamming is usually achieved by reducing the intensity of the target and simulating the target echo. Acoustic decoy technology has been widely recognized in the fields of mine jamming, deception, and mine sweeping. Acoustic decoys include active and passive modes. Due to the special acoustic scattering characteristics of corner reflectors, they are often used as the object of underwater passive jammer research. The purpose of underwater multi-domain scattering sound field regulation is achieved by studying and calculating the combined design of corner reflector structures.

[0003] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0004] The present invention aims at the technical problem of multiple scattering of underwater corner reflectors, improves the existing plate element calculation method by using the virtual source method, and combines the ray tracing theory to calculate the multiple scattering of multi-faceted corner reflectors, obtain the contribution of n-th scattering to the sound field, and superimpose all scattered sound fields to obtain the scattered sound field and target intensity, effectively improving the calculation speed and accuracy of corner reflectors.

[0005] The technical solution of the present invention to solve the above-mentioned multiple scattering calculation of underwater angular emitters is as follows:

[0006] Based on the virtual source method, the emission point is mirrored to the corresponding position of the plate irradiated by the sound wave. The incident sound wave is regarded as a number of rays, and the virtual source point is taken as the sound wave emission point. The fast ray tracing method is used to determine the path of multiple scattering of the sound wave on the surface of the corner reflector until the ray does not intersect the surface of the corner reflector. The scattered sound field of n-times scattering is calculated according to the physical acoustics theory, and all the calculated scattered sound fields are superimposed and approximated to obtain the scattered sound field with an acoustic super surface reflector at the receiving point.

[0007] The present invention also provides a method for evaluating the target intensity of a corner reflector with a metasurface:

[0008] S1. First, the surface structural plate element of the diagonal reflector;

[0009] The surface of the corner reflector is divided by several small triangular plates. To simplify the calculation, the acoustic metasurface is equivalent to a flat plate surface with phase difference at the narrow well. The metasurface equivalent plate is divided into regions, and the narrow well position is meshed separately.

[0010] S2. Calculate the primary scattered sound field PS1 of the corner reflector;

[0011] The sound wave starts from the incident point O, with a pitch incident angle of θ and a horizontal incident angle of Φ. The ray tracing method is used to determine whether the ray intersects with the plate element after primary scattering. If they do not intersect, the physical acoustic method is used to calculate the primary scattering sound field PS1 of the receiving point; if they intersect, secondary scattering is performed.

[0012] S3. Calculate the secondary scattered sound field PS2 of the corner reflector;

[0013] When point O is known, the fast ray tracing method is used to find the corresponding secondary scattering plate element, and the virtual source method is used to find the corresponding virtual source point O1; the ray tracing method is used to determine whether the ray after secondary scattering intersects with the plate. If not, the physical acoustic method is used to calculate the primary scattering sound field PS2 of the receiving point; if intersecting, three scattering is performed;

[0014] S4. Calculate the multiple scattered sound field PSn of the corner reflector;

[0015] In the known O n-2 In the case of point, the fast ray tracing method is used to find the corresponding n-th scattering plate element, and the virtual source method is used to find the corresponding virtual source point O n-1 ; Use the ray tracing method to determine whether the ray intersects with the plate after n scattering. If not, use the physical acoustic method to calculate the n-1 scattering sound field PS of the receiving point n-1 ; If they intersect, perform n scattering;

[0016] S5. Calculate the target intensity TS of the corner reflector; calculate the scattered sound field of n-time scattering according to the physical acoustic theory, perform superposition approximation processing on all the calculated scattered sound fields, and obtain the scattered sound field with the acoustic super surface reflector at the receiving point; use the target lightness calculation formula to obtain a certain point in the sound field: TS = 20*log10|(PS1+PS2+…+PS n )*R2|.

[0017] The evaluation method of the present invention has the following beneficial effects:

[0018] By using the virtual source method to improve the plate element and combine it with the ray tracing method, the ray path of the "concave" target, the plates it passes through and the number of ray reflections can be determined, and the plate area where primary scattering, secondary scattering and multiple scattering occur can be determined. The contribution of primary scattering, secondary scattering and multiple scattering to the scattered sound field of the target surface can be determined, and the acoustic metasurface can be quickly approximated by dividing the approximate flat plate area of ​​the metasurface. This method improves the calculation speed of the acoustic metasurface and has a certain accuracy. It further provides a method with a certain accuracy for studying the acoustic characteristics of the passive interference corner reflector combination in space. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a structural schematic diagram of the structure of a reflector having an acoustic metasurface at a corner of the present invention;

[0021] Figure 2 yes Figure 1 Schematic diagram of scattering of corner reflectors with acoustic metasurfaces;

[0022] Figure 3 It is a structural schematic diagram of the acoustic super surface body of the present invention;

[0023] Figure 4 yes Figure 3 Schematic diagram of scattering of acoustic metasurface;

[0024] Figure 5 is a schematic diagram of the scattering of the dihedral angle of the acoustic metasurface of the present invention;

[0025] Figure 6 It is a schematic structural diagram of the corner reflector of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Corner reflector 10 with acoustic metasurface, see attached Figure 1 As shown, a "concave" target is composed of two acoustic metasurface bodies (serial number 11a and serial number 11b) and a plane body 12; the acoustic metasurface body (serial number 11a and serial number 11b) is provided with x narrow well units 13 with gradient variation, and the depth of the narrow well unit 13 is used to regulate the phase of the sound wave; the two acoustic metasurface bodies (serial number 11a and serial number 11b) are perpendicularly combined to form an acoustic metasurface dihedral angle 14, and the two acoustic metasurface bodies (serial number 11a and serial number 11b) are respectively arranged perpendicularly to the plane body 12, and the vertical surface 131 between the plane body 12 and the acoustic metasurface body (serial number 11a and serial number 11b) is a smooth surface.

[0033] As a preferred embodiment of the present invention, refer to the attached Figure 3 and attached Figure 4 The narrow well unit 13 is composed of a narrow well 131 with a width of d0 and a narrow area 132 with a width of d1. The total width of a narrow well unit 13 is d=d1+d0, and the narrow well array gradient is a fixed constant g=h imax / d0, when the incident sound wave frequency is The designed groove phase variation is 0 to 2π with a step size of 2π / x.

[0034] As a preferred embodiment of the present invention, the two acoustic metasurfaces (serial number 11a and serial number 11b) have the same structural dimensions; the narrow well gradient and phase adjustment designs of the two acoustic metasurfaces (serial number 11a and serial number 11b) are the same or different.

[0035] As a preferred solution of the present invention, the three surfaces of the corner reflector 10 are in the shape of a square, a fan or a triangle.

[0036] As a preferred embodiment of the present invention, refer to Figure 2 As shown, the scattered sound field inside the corner reflector 10 is mainly divided into primary scattering, secondary scattering and tertiary scattering.

[0037] As a preferred embodiment of the present invention, refer to the attached Figure 5 As shown, after the first scattering of the dihedral angle 14 of the corner reflector acoustic metasurface, part of the sound waves undergo a phase mutation due to the metasurface, and when the second scattering occurs, part of the sound waves undergo another phase mutation. The scattered sound field of the first scattering of the acoustic metasurface is the scattering generated by the narrow area 132 between the narrow wells 131 and the scattering of the bottom surface of the narrow well 131.

[0038] The corner reflector 1 with acoustic metasurface is composed of a plurality of corner reflectors 10 with the same surface structure or a plurality of corner reflectors 10 with different surfaces. Figure 6 As shown, eight of the above-mentioned corner reflectors 10 are used, four of which are in a group, and the acoustic metasurface bodies of the four corner reflectors 10 are arranged adjacent to each other, and the bottom surfaces of the plane bodies 123 of the two groups of corner reflectors 10 are arranged adjacent to each other.

[0039] As a preferred embodiment of the present invention, the array of corner reflectors 1 is a combination of one-dimensional, two-dimensional and three-dimensional displays.

[0040] As a preferred embodiment of the present invention, the corner reflector 1 is a multi-layer corner reflector composed of a plurality of isosceles corner reflectors 10 symmetrically and tightly combined.

[0041] Embodiment 1

[0042] As attached Figure 1 As shown, the triangular corner reflector 10 with an acoustic metasurface designed by the present invention has a side length of 0.321m at the connection between the surfaces of the corner reflector 10. The corner reflector 10 is composed of two acoustic metasurface bodies (serial number 11a and serial number 11b) and a plane body 12, and the three surfaces are perpendicular to each other.

[0043] like Figure 3As shown, the acoustic super surface designed by the present invention has a total length D = 0.312m and a total width l = 0.08m. It is composed of fifteen narrow wells 131 with a width of 0.012m. The narrow area 132 between the narrow wells has a width of 0.008m. The total width of a narrow well unit 13 is d = d1 + d0 = 0.02m. The gradient of the narrow well array is a fixed constant g = 0.004. When the incident sound wave frequency is When the designed groove phase changes, it is 0~2π, and the step length is 2π / 15.

[0044] The present invention is based on multiple scattering calculations of the octahedral reflector 1 of the acoustic metasurface, such as Figure 6 As shown in the figure, the equivalent plate of the metasurface is divided into regions, region 111 (black thick line) is a separate grid for the narrow well area, and region 112 is a narrow area between narrow wells. When the sound wave reaches region 111, the phase of the reflected wave changes due to the effect of the metasurface. If it reaches region 112, the virtual source method is directly used for calculation.

[0045] like Figure 5 As shown, the schematic diagram of multiple scattering of the dihedral angle 14 of the acoustic metasurface designed by the present invention, the scattering conditions of the dihedral angle 14 of the acoustic metasurface are mainly four kinds: primary scattering of the acoustic metasurface body 11a; primary scattering of the acoustic metasurface body 11b; secondary scattering of the reflected sound wave of the acoustic metasurface body 11a on the acoustic metasurface body 11b; secondary scattering of the reflected sound wave of the acoustic metasurface body 11b on the acoustic metasurface body 11a. The scattering field of the entire dihedral angle 14 reflector is the scattering sound field formed by the superposition of the above four parts of the scattering sound field.

[0046] The primary scattering of the acoustic metasurface 11a and the acoustic metasurface 11b can be divided into two parts, namely, the scattering generated by the narrow area 132 between the narrow wells 131 and the scattering of the bottom surface of the narrow well 131. The secondary scattering of the acoustic metasurface 11a and the acoustic metasurface 11b includes the scattering of the reflected sound waves of the acoustic metasurface 11a on the acoustic metasurface 11b and the scattering of the reflected sound waves of the acoustic metasurface 11b on the acoustic metasurface 11a. The scattering of the reflected sound waves of the acoustic metasurface 11a on the surface acoustic metasurface 11b includes the scattering of the reflected sound waves of the acoustic metasurface 11a in the narrow area between the narrow wells of the acoustic metasurface 11b and the scattering of the reflected sound waves of the acoustic metasurface 11b in the narrow well 131 of the acoustic metasurface 11b.

[0047] like Figure 4As shown, a schematic diagram of multiple scattering of a corner reflector with an acoustic metasurface designed in the present invention, the scattering conditions of the corner reflector are mainly: primary scattering, acoustic scattering of sound waves on the acoustic metasurface body 11a, the acoustic metasurface body 11b, and the plane body 12; secondary scattering, acoustic scattering of sound waves reflected by the plane body 12 to reach the acoustic metasurface body 11a, acoustic scattering of sound waves reflected by the plane body 12 to reach the acoustic metasurface body 11b, acoustic scattering of sound waves reflected by the acoustic metasurface body 11a to reach the acoustic metasurface body 11b, acoustic scattering of sound waves reflected by the acoustic metasurface body 11a to reach the acoustic metasurface body 11b, acoustic scattering of sound waves reflected by the acoustic metasurface body 11b to reach the plane body 12, and acoustic scattering of sound waves reflected by the acoustic metasurface body 11b to reach the plane body 12. Three scatterings: the sound wave is reflected by the plane body 12 to reach the acoustic metasurface body 11a, and then reflected by the acoustic metasurface body 11a to reach the acoustic metasurface body 11b. The sound wave is reflected by the plane body 12 to reach the acoustic metasurface body 11b, and then reflected by the acoustic metasurface body 11b to reach the acoustic metasurface body 11a. The sound wave is reflected by the acoustic metasurface body 11a to reach the plane body 12, and then reflected by the plane body 12 to reach the acoustic metasurface body 11b. Scattering: The sound wave is reflected by the acoustic metasurface 11a to reach the acoustic metasurface 11b, and then reflected by the acoustic metasurface 11b to reach the plane body 12. Acoustic scattering: The sound wave is reflected by the acoustic metasurface 11b to reach the plane body 12, and then reflected by the plane body 12 to reach the acoustic metasurface 11a. Acoustic scattering: The sound wave is reflected by the acoustic metasurface 11b to reach the acoustic metasurface 11a, and then reflected by the acoustic metasurface 11a to reach the plane body 12.

[0048] Method for evaluating target intensity of corner reflectors with metasurfaces:

[0049] S1. First, the surface structural plate element of the diagonal reflector;

[0050] The surface of the corner reflector 1 is divided by several small triangular plates. To simplify the calculation, the acoustic metasurface is equivalent to a flat plate surface with a phase difference at the narrow well. The metasurface equivalent flat plate is divided into regions, and the narrow well position is meshed separately.

[0051] S2. Calculate the primary scattered sound field PS1 of the corner reflector;

[0052] The sound wave starts from the incident point O, with a pitch incident angle of θ and a horizontal incident angle of Φ. The ray tracing method is used to determine whether the ray intersects with the plate element after primary scattering. If they do not intersect, the physical acoustic method is used to calculate the primary scattering sound field PS1 of the receiving point; if they intersect, secondary scattering is performed.

[0053] S3. Calculate the secondary scattered sound field PS2 of the corner reflector;

[0054] When point O is known, the fast ray tracing method is used to find the corresponding secondary scattering plate element, and the virtual source method is used to find the corresponding virtual source point O1; the ray tracing method is used to determine whether the ray after secondary scattering intersects with the plate. If not, the physical acoustic method is used to calculate the primary scattering sound field PS2 of the receiving point; if intersecting, three scattering is performed;

[0055] S4. Calculate the multiple scattered sound field PSn of the corner reflector;

[0056] In the known O n-2 In the case of point, the fast ray tracing method is used to find the corresponding n-th scattering plate element, and the virtual source method is used to find the corresponding virtual source point O n-1 ; Use the ray tracing method to determine whether the ray intersects with the plate after n scattering. If not, use the physical acoustic method to calculate the n-1 scattering sound field PS of the receiving point n-1 ; If they intersect, perform n scattering;

[0057] S5. Calculate the target intensity TS of the corner reflector; calculate the scattered sound field of n-time scattering according to the physical acoustic theory, perform superposition approximation processing on all the calculated scattered sound fields, and obtain the scattered sound field with the acoustic super surface reflector at the receiving point; use the target lightness calculation formula to obtain a certain point in the sound field: TS = 20*log10|(PS1+PS2+…+PS n )*R2|.

[0058] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A corner reflector with an acoustic metasurface, characterized in that: The corner reflector is a "concave" target composed of two acoustic metasurfaces and a plane body; The acoustic metasurface is provided with x narrow well units with gradient changes, and the depth of the narrow well units is used to control the phase of the acoustic wave; The two acoustic metasurface bodies are perpendicularly combined to form an acoustic metasurface dihedral angle, the two acoustic metasurface bodies are respectively arranged perpendicularly to the plane body, and the perpendicular surfaces between the plane body and the acoustic metasurface body are smooth surfaces; The narrow well unit is composed of a narrow well with a width of d0 and a narrow area with a width of d1. The total width of a narrow well unit is d=d1+d0, and the gradient of the narrow well array is a fixed constant g=h imax / d0, when the incident sound wave frequency is The designed groove phase variation is 0 to 2π with a step size of 2π / x.

2. The corner reflector with acoustic metasurface according to claim 1, characterized in that: The two acoustic metasurfaces have the same structural dimensions; the narrow well gradient and phase adjustment designs of the acoustic metasurfaces are different or the same.

3. The corner reflector with acoustic metasurface according to claim 2, characterized in that: The component surface shape of the corner reflector is square, fan-shaped or triangular.

4. The corner reflector with acoustic metasurface according to claim 3, characterized in that: The corner reflector is an isosceles corner reflector.

5. The corner reflector with acoustic metasurface according to claim 4, characterized in that: The scattered sound field of the corner reflector is divided into a primary scattered sound field, a secondary scattered sound field and a tertiary scattered sound field.

6. The corner reflector with acoustic metasurface according to claim 5, characterized in that: After the corner reflector acoustic metasurface body dihedral angle scatters once, part of the sound waves undergoes phase mutation due to the metasurface, and when scattered twice, part of the sound waves undergoes phase mutation again.

7. The corner reflector with acoustic metasurface according to claim 6, characterized in that: The scattered acoustic field of the primary scattering of the acoustic metasurface is the scattering generated by the narrow areas between the narrow wells and the scattering of the bottom surface of the narrow wells.

8. A corner reflector having an acoustic metasurface, characterized in that: The corner reflectors described in any one of eight claims 1-7 are used, wherein the acoustic metasurface bodies of four corner reflectors are arranged adjacent to each other in a group of four, and the bottom surfaces of the planar bodies of two groups of corner reflectors are arranged adjacent to each other.

9. An evaluation method using the corner reflector according to claim 8, characterized in that: Here are the steps: S1. First, the surface structural plate element of the diagonal reflector; The surface of the corner reflector is divided by several small triangular plates. To simplify the calculation, the acoustic metasurface is equivalent to a flat plate surface with phase difference at the narrow well. The metasurface equivalent plate is divided into regions, and the narrow well position is meshed separately. S2. Calculate the primary scattered sound field PS1 of the corner reflector; The sound wave starts from the incident point O, with a pitch incident angle of θ and a horizontal incident angle of Φ. The ray tracing method is used to determine whether the ray intersects with the plate element after primary scattering. If they do not intersect, the physical acoustic method is used to calculate the primary scattering sound field PS1 of the receiving point; if they intersect, secondary scattering is performed. S3. Calculate the secondary scattered sound field PS2 of the corner reflector; When the 0 point is known, the fast ray tracing method is used to find the corresponding secondary scattering plate element, and the virtual source method is used to find the corresponding virtual source point O1; the ray tracing method is used to determine whether the ray after secondary scattering intersects with the plate. If not, the physical acoustic method is used to calculate the primary scattering sound field PS2 of the receiving point; if intersecting, three scattering is performed; S4. Calculate the multiple scattered sound field PS of the corner reflector n ; In the known O n-2 In the case of point, the fast ray tracing method is used to find the corresponding n-th scattering plate element, and the virtual source method is used to find the corresponding virtual source point O n-1 ; Use the ray tracing method to determine whether the ray intersects with the plate after n scattering. If not, use the physical acoustic method to calculate the n-1 scattering sound field PS of the receiving point n-1 ; If they intersect, perform n scattering; S5. Calculate the target intensity TS of the corner reflector; According to the physical acoustic theory, the scattered sound field of n-time scattering is calculated, and all the calculated scattered sound fields are superimposed and approximated to obtain the scattered sound field with an acoustic super surface reflector at the receiving point; the target lightness calculation formula can be used to obtain a certain point in the sound field: TS = 20*log10|(PS1+PS2+…+PS n )*R2|.

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