An acoustic structure with low frequency and wide band noise reduction and a design method of the acoustic structure

Abstract

The application belongs to the field of acoustics, and discloses a low-frequency and wide-band noise reduction acoustic structure and a design method of the acoustic structure. The acoustic structure comprises a plurality of acoustic structural members and an embedded member. At least one embedded member is arranged in the plurality of acoustic structural members. On the same embedded member, the acoustic structural members in communication with the two open ends of the embedded member are arranged in pairs and jointly form a first unit. The acoustic structural member not in communication with the embedded member is a second unit. The first unit and the second unit are arranged in parallel. Compared with the prior art, when sound waves pass through the acoustic structural members arranged in pairs, the coupling resonance generated in the acoustic structural members can widen the noise reduction frequency band at a certain resonance frequency in the low-frequency range. The added embedded member can generate a new noise reduction frequency band. The weak coupling effect between the parallel units can further widen the noise reduction frequency band. Finally, the low-frequency and wide-band noise reduction effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of acoustic technology, and in particular to a low-frequency, broadband noise reduction acoustic structure and a design method for the acoustic structure. Background Technology

[0002] Aircraft engine noise control is crucial for meeting noise compliance standards and improving cabin comfort. Besides active noise control and geometric optimization, passive noise reduction can be achieved by laying damping materials in the air intake, thrust reversers, and exhaust nozzle systems. Initially, porous sound-absorbing materials were primarily used as damping materials, later improved to single-degree-of-freedom acoustic structures. With advancements in science and technology, aircraft manufacturers and engine suppliers have conducted numerous studies on noise reduction structures, leading to the development of a mesh-cap acoustic structure designed to enhance noise reduction capabilities across different noise frequency bands.

[0003] However, the mesh cap structure in this type of acoustic structure not only presents challenges in industrial production, such as difficult adhesive bonding, leading to long development cycles and high costs due to repeated trial and error, but also poses a risk of breakage and detachment under the influence of engine blade rotational vibration, making effective acoustic performance control difficult. With the use of high-bypass ratio engines and the introduction of more stringent noise airworthiness standards, this structure will no longer be able to meet the actual needs of aircraft in terms of comfort and quietness.

[0004] To overcome the aforementioned long-standing problems, designing acoustic structures with characteristics such as wide sound absorption bandwidth, multiple resonant sound absorption peaks, and strong overall mechanical properties has become the main development trend for new anechoic nacelle acoustic liners. Summary of the Invention

[0005] The purpose of this invention is to provide a low-frequency, broadband noise reduction acoustic structure and a design method for the acoustic structure, which aims to enhance the low-frequency noise reduction capability, broaden the low-frequency noise reduction band, and maintain high mechanical performance.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] On one hand, a low-frequency, broadband noise reduction acoustic structure is provided. The low-frequency, broadband noise reduction acoustic structure includes multiple acoustic structural components and an embedded component. Each of the multiple acoustic structural components has a resonant chamber inside and at least one microhole communicating with the resonant chamber. The embedded component is a hollow structure with open ends. At least one embedded component is inserted through the multiple acoustic structural components. On the same embedded component, acoustic structural components communicating with the open ends of the embedded component are arranged in pairs and together with the embedded component to form a first element. Between the two acoustic structural components communicating with the embedded component, there is at least one acoustic structural component that is not communicating with the embedded component. The acoustic structural component that is not communicating with the embedded component is a second element. The first element and the second element are arranged in parallel.

[0008] Optionally, the acoustic structural component includes a through-hole panel and a structural component body. The structural component body is a hollow shell with one open side. The structural component body has at least one connection notch that matches the shape of the embedded component. The through-hole panel covers the open side of the structural component body to form the resonant chamber. The micropores are formed on the through-hole panel.

[0009] Optionally, the porosity of the through-hole panels of the two acoustic structural members connected to both ends of the insert is the same.

[0010] Optionally, the porosity of the acoustic structural member connected to the insert and the through-hole panel of the acoustic structural member not connected to the insert are different.

[0011] Optionally, the end of the insert extends in the resonant chamber of the acoustic structure communicating with the insert, but does not abut against the inner wall of the resonant chamber.

[0012] Optionally, when multiple embedded members are inserted within multiple acoustic structural members, the multiple embedded members have the same or different cross-sectional shapes.

[0013] Optionally, the cross-sectional shape of the micropore is circular, elliptical, or polygonal;

[0014] The cross-sectional shape of the resonant cavity is polygonal or circular;

[0015] The longitudinal cross-sectional shape of the embedded part is polygonal, semi-circular, or semi-elliptical.

[0016] On the other hand, a design method for an acoustic structure is also provided, which is used to design a low-frequency, broadband noise reduction acoustic structure as described in any of the preceding claims, comprising the following steps:

[0017] S1: Obtain the structural dimensions of the multiple acoustic structural components and the number and diameter of the micropores opened on the multiple acoustic structural components, and generate a structural model of the combination of the multiple acoustic structural components;

[0018] S2: Based on the structural model, construct the sound absorption function for the required sound frequency band;

[0019] S3: Based on the sound absorption function, formulate the required sound absorption spectrum according to the design requirements, use the optimization algorithm to find the size parameters of the embedded part that meet the sound absorption requirements, combine the embedded part with the acoustic structural parts in the structural model, and generate the overall model of the low-frequency, broadband noise reduction acoustic structure.

[0020] S4: Further adjust the size parameters of the overall model, the number and position of the embedded parts, so that the low-frequency, broadband noise reduction acoustic structure meets the design requirements.

[0021] Optionally, in step S3, the optimization algorithm is a reinforcement learning algorithm or a genetic algorithm.

[0022] Optionally, in step S4, the adjustable dimensional parameters in the overall model include the structural dimensions of the plurality of acoustic structural components, the number, diameter and arrangement of the micropores opened on the acoustic structural components, and the dimensional parameters of the embedded components.

[0023] The beneficial effects of this invention are:

[0024] This invention provides a low-frequency, broadband noise reduction acoustic structure. When sound waves enter a pair of acoustic structural components with resonant chambers connected by an embedded element, the resulting coupling resonance effect broadens the anechoic band at a certain resonant frequency in the low-frequency range. The added embedded element further enables the paired acoustic structural components to generate new anechoic bands, which, combined with their own anechoic bands, further broaden the low-frequency anechoic band. Furthermore, at least one acoustic structural component not connected to the embedded element is provided between the acoustic structural components connected at both ends of the embedded element. This creates two parallel primitives, where sound waves generate a weak coupling resonance effect, achieving low-frequency, wider-bandwidth noise reduction. Compared to existing diaphragm-type acoustic structures, this acoustic structure has stronger mechanical properties and can improve the problems of structural damage and detachment under long-term vibration environments.

[0025] This invention also provides a design method for an acoustic structure, used to design the aforementioned low-frequency, broadband noise reduction acoustic structure, ensuring that all parameters are accurate and reasonable, thereby ensuring that the low-frequency, broadband noise reduction acoustic structure meets the design requirements, so as to obtain a wider low-frequency noise reduction bandwidth and a better noise reduction effect. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the acoustic structure for low-frequency, broadband noise reduction in Embodiment 1 of the present invention;

[0027] Figure 2 This is a top view of the acoustic structure for low-frequency, broadband noise reduction in Embodiment 1 of the present invention;

[0028] Figure 3 This is a schematic diagram of the first basic element of the acoustic structure for low-frequency, broadband noise reduction in Embodiment 1 of the present invention;

[0029] Figure 4 This is a top view of the acoustic structural component in the first basic element of Embodiment 1 of the present invention;

[0030] Figure 5 yes Figure 4 A cross-sectional view along the AA direction;

[0031] Figure 6 This is a schematic diagram of the second element of the acoustic structure for low-frequency, broadband noise reduction in Embodiment 1 of the present invention;

[0032] Figure 7 This is a top view of the acoustic structural component in the second basic element of Embodiment 1 of the present invention;

[0033] Figure 8 yes Figure 7 A cross-sectional view along the BB direction;

[0034] Figure 9 This is a perspective view of the acoustic structure for low-frequency, broadband noise reduction in Embodiment 2 of the present invention;

[0035] Figure 10 This is a top view of the acoustic structure for low-frequency, broadband noise reduction in Embodiment 3 of the present invention;

[0036] Figure 11 This is a first-view view of the third acoustic structural component in Embodiment 3 of the present invention;

[0037] Figure 12 This is a second-view view of the third acoustic structural component in Embodiment 3 of the present invention;

[0038] Figure 13 This is a top view of the acoustic structure for low-frequency, broadband noise reduction in Embodiment 4 of the present invention;

[0039] Figure 14 This is a flowchart illustrating the design steps of the acoustic structure of the present invention.

[0040] In the picture:

[0041] 100, First Element; 200, Second Element;

[0042] 1. Acoustic structural component; 11. Through-hole panel; 111. Micro-hole; 12. Structural component body; 121. Connection notch;

[0043] 2. Embedded components. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention and not the entire structure.

[0045] In the description of this invention, unless otherwise specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0047] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0048] Example 1

[0049] To enhance low-frequency noise reduction capabilities and broaden the low-frequency noise reduction bandwidth, this embodiment provides an acoustic structure for low-frequency, broadband noise reduction.

[0050] The low-frequency, broadband noise reduction acoustic structure includes multiple acoustic structural components 1 and an embedded component 2. Each of the multiple acoustic structural components 1 has a resonant chamber inside and at least one micropore 111 communicating with the resonant chamber. The embedded component 2 is a hollow structure with open ends. At least one embedded component 2 is inserted through the multiple acoustic structural components 1. On the same embedded component 2, acoustic structural components 1 communicating with the open ends of the embedded component 2 are arranged in pairs and together with the embedded component 2 to form a first element 100. Between the two acoustic structural components 1 communicating with the embedded component 2, there is at least one acoustic structural component 1 that is not communicating with the embedded component 2. The acoustic structural component 1 that is not communicating with the embedded component 2 is a second element 200. The first element 100 and the second element 200 are arranged in parallel.

[0051] In this embodiment Figures 1 to 8 In this embodiment, the low-frequency, broadband noise reduction acoustic structure includes four acoustic structural components 1 and one embedded component 2. Two acoustic structural components 1 are located at both ends of the embedded component 2 and are connected to it. The other two acoustic structural components 1 are not connected to the embedded component 2 and are located between the two acoustic structural components 1 connected to the embedded component 2. The embedded component 2 and the two acoustic structural components 1 connected to the embedded component 2 together constitute a first element 100. The remaining two acoustic structural components 1 not connected to the embedded component 2 constitute a second element 200. The first element 100 and the second element 200 are arranged in parallel, and there are no sound waves flowing into the second element 200 from the embedded component 2. In this embodiment, the resonant chamber is a Helmholtz resonant chamber.

[0052] Optionally, the acoustic structural component 1 includes a through-hole panel 11 and a structural component body 12. The structural component body 12 is a hollow shell with one side open. The structural component body 12 has at least one connection notch 121 that matches the shape of the insert 2. The through-hole panel 11 covers the opening of the structural component body 12 to form a resonant chamber. Microholes 111 are formed on the through-hole panel 11.

[0053] By creating at least one connection notch 121 on the structural component body 12 that matches the shape of the embedded component 2, the embedded component 2 can be easily inserted into multiple acoustic structural components 1. In this embodiment, the structural component body 12 of the acoustic structural component 1 that communicates with the embedded component 2 has one connection notch 121, through which the end of the embedded component 2 extends into the resonant cavity; the structural component body 12 of the acoustic structural component 1 that does not communicate with the embedded component 2 has two oppositely arranged connection notches 121, through which the embedded component 2 is inserted and removed. The number of micro-holes 111 on the through-hole panel 11 can be freely set according to requirements. In this embodiment, the through-hole panel 11 of the acoustic structural component 1 that communicates with the embedded component 2 has one micro-hole 111, and the through-hole panel 11 of the acoustic structural component 1 that does not communicate with the embedded component 2 has three micro-holes 111.

[0054] Optionally, the through-hole panels 11 of the two acoustic structural members 1 connected to both ends of the embedded member 2 have the same porosity, which is intended to enable sound waves to couple and resonate within the two acoustic structural members 1 connected by the embedded member 2, thereby widening the noise reduction frequency band at a certain resonant frequency in the low-frequency range.

[0055] In this embodiment, since the two acoustic structural components 1 connected by the embedded component 2 are arranged in pairs and have the same porosity, the manufacturing materials, structural shape and size of these two acoustic structural components 1, as well as the number, geometric dimensions and arrangement of the micropores 111, are all consistent. In this embodiment, among the four acoustic structural components 1, the two acoustic structural components 1 that are not connected to the embedded component 2 are also arranged in pairs, and their manufacturing materials, structural shape and size, as well as the number, geometric dimensions and arrangement of the micropores 111, are all consistent.

[0056] Optionally, the porosity of the through-hole panel 11 of the acoustic structural member 1 connected to the embedded member 2 and the acoustic structural member 1 not connected to the embedded member 2 are different. By making the porosity of the through-hole panel 11 of the acoustic structural member 1 connected to the embedded member 2 different from the porosity of the through-hole panel 11 of the acoustic structural member 1 not connected to the embedded member 2, the acoustic structure generates two different noise reduction bands at the resonant frequency in the low-frequency range, thereby widening the low-frequency noise reduction band.

[0057] Optionally, the end of the insert 2 extends within the resonant cavity of the acoustic structure 1, which is connected to the insert 2, but does not abut against the inner wall of the resonant cavity. This ensures that sound waves can propagate within the insert 2 and that the newly generated anechoic band is close to the resonant frequency of the paired acoustic structures 1.

[0058] Optionally, when multiple acoustic structural components 1 are fitted with multiple embedded components 2, the multiple embedded components 2 have the same or different cross-sectional shapes. By fitting multiple embedded components 2 with the same or different cross-sectional shapes into multiple acoustic structural components 1, different combinations can be used to construct low-frequency noise reduction bands with different bandwidths, thereby widening the low-frequency noise reduction band.

[0059] Optionally, the cross-sectional shape of the micropore 111 is circular, elliptical, or polygonal; the cross-sectional shape of the resonant cavity is polygonal or circular; and the longitudinal cross-sectional shape of the insert 2 is polygonal, semi-circular, or semi-elliptical. Various selectable shapes are used to obtain the low-frequency noise reduction band that satisfies the structural design. In this embodiment, the cross-sectional shape of the micropore 111 is circular, the cross-sectional shape of the resonant cavity is hexagonal, and the longitudinal cross-section of the insert 2 is rectangular.

[0060] Figure 9 Embodiment 2 is shown, wherein components that are the same as or corresponding to those in Embodiment 1 are referred to using the same reference numerals as those in Embodiment 1. For simplicity, only the differences between Embodiment 2 and Embodiment 1 are described.

[0061] The difference lies in that, in Embodiment 2, the acoustic structure comprises three acoustic structural components 1 and one embedded component 2. Two acoustic structural components 1 are located at both ends of the embedded component 2 and are connected to it. The remaining acoustic structural component 1 is located between the two acoustic structural components 1 connected to the embedded component 2 and is not connected to the embedded component 2. In this case, the two acoustic structural components 1 connected to the embedded component 2 together with the embedded component 2 constitute the first basic element 100, and the acoustic structural component 1 not connected to the embedded component 2 constitutes the second basic element 200. In this embodiment, the longitudinal cross-sectional shape of the embedded component 2 is triangular. Each acoustic structural component 1 in the first basic element 100 has a micro-hole 111 and a connection notch 121. The acoustic structural component 1 in the second basic element 200 has four micro-holes 111 and two oppositely arranged connection notches 121.

[0062] Example 3

[0063] Figures 10 to 12 Embodiment 3 is shown, wherein components that are the same as or corresponding to those in Embodiments 1 and 2 are represented by the same reference numerals as those in Embodiments 1 and 2. For simplicity, only the differences between Embodiment 3 and Embodiments 1 and 2 are described.

[0064] The difference is that, in embodiment three, the acoustic structure is provided with four acoustic structural components 1 and two embedded components 2. One of the embedded components 2 is responsible for connecting the acoustic structural components 1 located in the first and third positions. The embedded component 2 and the acoustic structural components 1 located in the first and third positions constitute the first basic element 100. At this time, the acoustic structural component 1 located in the second position is not connected to the embedded component 2 and is the second basic element 200 in the structure.

[0065] Another embedded component 2 connects the acoustic structural components 1 located at the second and fourth positions. This embedded component 2, together with the acoustic structural components 1 at the second and fourth positions, constitutes the first element 100. The acoustic structural component 1 located at the third position is not connected to this embedded component 2 and forms the second element 200 in this structure. In this embodiment, two first elements 100 and two second elements 200 can be defined. Adding an additional embedded component 2 allows the acoustic structure to generate a new noise reduction frequency band.

[0066] In this embodiment, the longitudinal section of the insert 2 is rectangular. The first and fourth acoustic structural components 1 are provided with a connection notch 121, and the second and third acoustic structural components 1 are provided with three connection notches 121. Since the two acoustic structural components 1 connected by the insert 2 are arranged in pairs, the first and third acoustic structural components 1 are each provided with a microhole 111, and the second and fourth acoustic structural components 1 are each provided with two microholes 111.

[0067] Example 4

[0068] Figure 13 Embodiment 4 is shown, wherein components that are the same as or corresponding to those in Embodiments 1, 2, and 3 are referred to by the same reference numerals as those in Embodiments 1, 2, and 3. For simplicity, only the differences between Embodiment 4 and Embodiments 1, 2, and 3 are described.

[0069] The difference lies in the fact that, in the acoustic structure of embodiment four, when there are multiple acoustic structural components 1 that are not connected to the embedded component 2, the porosity of the through-hole panel 11 and the cross-sectional shape of the micro-hole 111 of the multiple acoustic structural components 1 that are not connected to the embedded component 2 can be different.

[0070] In this embodiment, the low-frequency, broadband noise reduction acoustic structure includes four acoustic structural components 1 and one embedded component 2. Two acoustic structural components 1 are located at both ends of the embedded component 2 and are connected to it. The other two acoustic structural components 1 are not connected to the embedded component 2 and are located between the two acoustic structural components 1 connected to the embedded component 2. The embedded component 2 and the two acoustic structural components 1 connected to the embedded component 2 together constitute a first element 100. The remaining two acoustic structural components 1 not connected to the embedded component 2 constitute a second element 200. Each of the two acoustic structural components 1 in the first element 100 has a micro-hole 111. In the second element 200, one of the two acoustic structural components 1 has two micro-holes 111, and the other has three micro-holes 111. The different acoustic structural components 1 in the second element will construct a new resonant noise reduction band, which can broaden the bandwidth of the low-frequency noise reduction band.

[0071] To obtain the aforementioned low-frequency, broadband noise reduction acoustic structure, a design method for the acoustic structure is also provided, such as... Figure 14 As shown, the design method of this acoustic structure includes the following steps:

[0072] S1: Obtain the structural dimensions, number and corresponding diameter of multiple acoustic structural components 1 in the first primitive 100 and the second primitive 200, as well as the arrangement of the first primitive 100 and the second primitive 200, to generate a structural model after the acoustic structural components 1 are combined.

[0073] S2: Based on the structural model, construct the sound absorption function for the required sound frequency band;

[0074] S3: Based on the sound absorption function, formulate the required sound absorption spectrum according to the design requirements, use the optimization algorithm to find the size parameters of the embedded part 2 that meet the sound absorption requirements, combine the embedded part 2 with the acoustic structural part 1 in the structural model, construct the corresponding first primitive 100 and second primitive 200, and generate the overall model of the low-frequency, broadband noise reduction acoustic structure.

[0075] S4: Further adjust the overall model's size parameters, the number and position of the embedded parts 2, so that the acoustic structure for low-frequency, broadband noise reduction meets the design requirements.

[0076] By employing the above methods to design the acoustic structure for low-frequency, broadband noise reduction, all parameters are made accurate and reasonable, thereby ensuring that the acoustic structure for low-frequency, broadband noise reduction meets the design requirements, so as to obtain a wider low-frequency noise reduction bandwidth and a better noise reduction effect.

[0077] Optionally, in step S3, the optimization algorithm is a reinforcement learning algorithm or a genetic algorithm.

[0078] Optionally, in step S4, the adjustable dimensional parameters in the overall model include the structural dimensions of the acoustic structural component 1 in the first primitive 100 and the second primitive 200, the number, diameter and arrangement of the micro-holes 111, and the dimensional parameters of the insert 2.

[0079] Because the acoustic structure of this low-frequency, broadband noise reduction is simple and easy to manufacture, after setting the relevant parameters of the acoustic structure of the low-frequency, broadband noise reduction through the above design method, it can be manufactured by either traditional forming method or integral forming by additive manufacturing technology.

[0080] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the theory and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A low-frequency, broadband noise reduction acoustic structure, characterized in that, The device includes multiple acoustic structural components (1) and an embedded component (2). Each of the multiple acoustic structural components (1) has a resonant chamber and at least one microhole (111) communicating with the resonant chamber. The embedded component (2) is a hollow structure with open ends. At least one embedded component (2) is inserted through the multiple acoustic structural components (1). On the same embedded component (2), the acoustic structural components (1) communicating with the open ends of the embedded component (2) are arranged in pairs and together with the embedded component (2) to form a first basic unit (100). Between the two acoustic structural components (1) communicating with the embedded component (2), there is at least one acoustic structural component (1) that is not communicating with the embedded component (2). The acoustic structural component (1) that is not communicating with the embedded component (2) is a second basic unit (200). The first basic unit (100) and the second basic unit (200) are arranged in parallel. The acoustic structural component (1) includes a through-hole panel (11) and a structural component body (12). The structural component body (12) is a hollow shell with one side open. The structural component body (12) has at least one connection notch (121) that matches the shape of the insert (2). The through-hole panel (11) covers the opening of the structural component body (12) to form the resonant chamber. The micropores (111) are formed on the through-hole panel (11). The through-hole panels (11) of the two acoustic structural members (1) connected to both ends of the embedded member (2) have the same porosity; The porosity of the acoustic structural member (1) that is connected to the embedded member (2) and the through-hole panel (11) of the acoustic structural member (1) that is not connected to the embedded member (2) are different; The end of the insert (2) extends in the resonant cavity of the acoustic structure (1) that is in communication with the insert (2), but does not abut against the inner wall of the resonant cavity; When multiple acoustic structural members (1) are provided with multiple embedded members (2), the multiple embedded members (2) have the same or different cross-sectional shapes.

2. The acoustic structure for low-frequency, broadband noise reduction according to claim 1, characterized in that, The cross-sectional shape of the micropore (111) is circular, elliptical, or polygonal; The cross-sectional shape of the resonant cavity is polygonal or circular; The longitudinal cross-sectional shape of the insert (2) is polygonal, semi-circular, or semi-elliptical.

3. A method for designing an acoustic structure, characterized in that, The acoustic structure design method is used to design the low-frequency, broadband noise reduction acoustic structure as described in any one of claims 1-2, and includes the following steps: S1: Obtain the structural dimensions of multiple acoustic structural components (1) and the number and diameter of the microholes (111) opened on the multiple acoustic structural components (1), and generate a structural model of the combination of multiple acoustic structural components (1); S2: Based on the structural model, construct the sound absorption function for the required sound frequency band; S3: Based on the sound absorption function, formulate the required sound absorption spectrum according to the design requirements, use the optimization algorithm to find the size parameters of the embedded part (2) that meet the sound absorption requirements, combine the embedded part (2) with the acoustic structural part (1) in the structural model, and generate the overall model of the low-frequency, broadband noise reduction acoustic structure. S4: Further adjust the size parameters of the overall model, the number and position of the embedded parts (2), so that the low-frequency, broadband noise reduction acoustic structure meets the design requirements.

4. The acoustic structure design method according to claim 3, characterized in that, In step S3, the optimization algorithm is a reinforcement learning algorithm or a genetic algorithm.

5. The design method for the acoustic structure according to claim 3, characterized in that, In step S4, the adjustable size parameters in the overall model include the structural dimensions of the multiple acoustic structural components (1), the number, diameter and arrangement of the microholes (111) on the acoustic structural components (1), and the size parameters of the insert (2).

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