Multi-band omnidirectional ventilated acoustic barrier and acoustic device based on subwavelength gradient microcavity

Abstract

This invention discloses a multi-band, omnidirectional, ventilated acoustic barrier and acoustic device based on a subwavelength gradient microcavity. The acoustic barrier comprises a substrate and a plurality of microcavity structures located on the substrate. The microcavity structures comprise a main body and a plurality of labyrinthine units distributed circumferentially outside the main body. The labyrinthine units contain a plurality of air channels, with the opening angles of the labyrinth units gradually increasing, and the opening angles of the slots between adjacent labyrinthine units are equal. By utilizing the resonance effect of the microcavity structure with a gradient opening angle, the invention can achieve multi-band and even broadband sound insulation at a subwavelength scale. The acoustic barrier exhibits excellent sound insulation and maintains good air circulation, which is of great significance for the design and application of a new generation of acoustic devices.

Description

Technical Field

[0001] The present invention belongs to the field of acoustic propagation technology, and specifically relates to a multi-band omnidirectional ventilated acoustic barrier and acoustic device based on a subwavelength gradient microcavity. Background Art

[0002] Over the past two decades, scientists have proposed a variety of acoustic metamaterial sound insulation structures to overcome the inherent limitations of natural materials in handling low-frequency sound. Compared to traditional porous materials, these structures offer a compact design and can be used in harsh environments such as humid and confined spaces, making them particularly advantageous for noise control and improving the acoustic environment. However, in everyday life and practical applications, noise generation is often associated with instabilities in the background fluid, particularly in pipes, turbines, and nozzles. Furthermore, the background fluid, such as air or water, often requires a relatively free passage for the devices containing these structures to function properly. These practical limitations render many previous metamaterial sound isolators ineffective, as they only function fully when the passages are completely sealed, as sound can penetrate any small pores. Otherwise, the presence of transmission channels causes these metamaterial sound isolators to drastically degrade in performance, often dropping below 50% in sound insulation.

[0003] Recently, some ventilated metamaterial sound insulators have been demonstrated. However, their sound absorption or ventilation performance is still less than satisfactory, and there are few studies on achieving efficient sound insulation and ventilation performance at the same time. This can be mainly explained by the fact that a smaller opening area ratio leads to lower ventilation performance, or low sound insulation efficiency in experiments. Among them, the solution based on local Fano resonance is widely used due to its simple principle and stability. It can dissipate and absorb sound waves within a certain frequency range in the structure. Such a design makes it possible to adjust low-frequency sound waves with subwavelength unit structures. However, in general, resonant structures have narrow resonance peaks, making it difficult to achieve multi-frequency or even broadband sound insulation effects. Although multi-frequency resonance effects can be achieved by superimposing multiple microcavities with different resonant frequencies, this often increases the complexity and stability of the structure, and the gradual coupling of the superimposed structure may also cause significant interference to the resonant frequency.

[0004] Therefore, in response to the above technical problems, it is necessary to provide a multi-band omnidirectional ventilation acoustic barrier based on subwavelength gradient microcavity. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a multi-band omnidirectional ventilated acoustic barrier and acoustic device based on a subwavelength gradient microcavity.

[0006] In order to achieve the above-mentioned purpose, the technical solution provided by one embodiment of the present invention is as follows:

[0007] A multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity, the acoustic barrier comprising a substrate and a plurality of microcavity structures on the substrate, the microcavity structure comprising a main body and a plurality of labyrinth units distributed circumferentially outside the main body, the labyrinth units comprising a plurality of air channels, the opening angles of the labyrinth units gradually increasing, and the opening angles of the slots between adjacent labyrinth units being equal.

[0008] In one embodiment, the radius r of the main body is 0.5 cm to 2 cm, and the radius R of the microcavity structure is 2 cm to 10 cm.

[0009] In one embodiment, the main body is cylindrical, and the number of the labyrinth units outside the main body is 4 to 20.

[0010] In one embodiment, the minimum opening angle θ0 of the maze unit is 30° to 50°, and the increase amplitude Δθ is 1° to 3°; the sum of the opening angles of the empty slots is 8° to 24°, and the opening angle of a single empty slot is 1° to 3°.

[0011] In one embodiment, the maze unit includes a plurality of arcuate portions arranged from the inside to the outside, a first connecting portion connecting adjacent arcuate portions, and a second connecting portion connecting the innermost arcuate portion and the main body portion, and air passages are formed between adjacent arcuate portions and between the innermost arcuate portion and the main body portion.

[0012] In one embodiment, the number of the arc-shaped portions is 2 to 10, the thickness t1 of the arc-shaped portions is 0.1 to 0.5 cm, and the thickness t2 of the air passage is 0.1 to 0.5 cm.

[0013] In one embodiment, the thickness of the main body is greater than the thickness of the labyrinth unit.

[0014] In one embodiment, the transmission coefficient spectrum of the microcavity structure is TL=10log 10 (p t / p inc ), p t and p inc are the incident energy and transmitted energy of the microcavity structure, respectively.

[0015] In one embodiment, the radius r of the main body is 1 cm, and the radius R of the microcavity structure is 2.5 cm; and / or,

[0016] The number of the labyrinth units outside the main body is 8; and / or,

[0017] The minimum opening angle θ0 of the maze unit is 36°, and the increase amplitude Δθ is 2°; and / or,

[0018] The sum of the opening angles of the slots is 16°, and the opening angle of a single slot is 2°; and / or,

[0019] The number of the arc-shaped portions is 5, the thickness t1 of the arc-shaped portions is 0.25 cm, and the thickness t2 of the air passage is 0.25 cm.

[0020] Another embodiment of the present invention provides a technical solution as follows:

[0021] An acoustic device, comprising the above-mentioned acoustic barrier.

[0022] The present invention has the following beneficial effects:

[0023] The present invention utilizes the resonance effect of the microcavity structure with a gradual angle variation to achieve multi-band and even broadband sound insulation effects at the subwavelength scale. The acoustic barrier has good sound insulation effect and can maintain air circulation well, which is of great significance for the design and application of the new generation of acoustic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of the structure of the acoustic barrier in the present invention.

[0026] Figure 2a Schematic diagram of the three-dimensional structure of the microcavity structure of the present invention;

[0027] Figure 2b Schematic diagram of the planar structure of the microcavity structure in the present invention.

[0028] Figure 3a is the transmission coefficient spectrum of the acoustic barrier in a specific embodiment of the present invention;

[0029] Figures 3b to 3e 1 is a diagram showing the distribution of resonance modes in a microcavity structure at different resonance frequencies in a specific embodiment of the present invention.

[0030] Figure 4 This is a diagram of the sound pressure distribution field of the acoustic barrier under different excitation frequencies in a specific embodiment of the present invention.

[0031] Figure 5a This is a graph showing changes in the transmission coefficient spectrum of an acoustic barrier structure under different loss conditions in a specific embodiment of the present invention;

[0032] Figure 5b This is a diagram showing the wind speed variation at the transmission end when airflows of different wind speeds pass through the microcavity structure in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0034] Ginseng Figure 1 As shown, the present invention discloses a multi-band omnidirectional ventilated acoustic barrier based on a sub-wavelength gradient microcavity, comprising a substrate 10 and a plurality of microcavity structures 20 located on the substrate.

[0035] Ginseng Figure 2a 、 2b As shown, the microcavity structure in the present invention includes a main body 21 and a plurality of labyrinth units 22 distributed circumferentially on the outside of the main body. The labyrinth units 22 include a plurality of air channels. The opening angle of the labyrinth units gradually increases, and the opening angles of the slots 23 between adjacent labyrinth units 22 are equal.

[0036] Preferably, the radius r of the main body 21 is 0.5 cm to 2 cm, and the radius R of the microcavity structure 20 is 2 cm to 10 cm.

[0037] Preferably, the main body 21 is cylindrical, and the number of the labyrinth units 22 outside the main body is 4 to 20.

[0038] Preferably, the minimum opening angle θ0 of the labyrinth unit 22 is 30° to 50°, and the increase amplitude Δθ is 1° to 3°; the sum of the opening angles of the empty slots is 8° to 24°, and the opening angle of a single empty slot is 1° to 3°.

[0039] Preferably, the labyrinth unit 22 includes a plurality of arcuate portions 221 arranged from the inside to the outside, a first connecting portion 222 connecting adjacent arcuate portions, and a second connecting portion 223 connecting the innermost arcuate portion and the main body, and air passages are formed between adjacent arcuate portions and between the innermost arcuate portion and the main body.

[0040] Preferably, the number of the arc-shaped portions 221 is 2 to 10, the thickness t1 of the arc-shaped portions 221 is 0.1 to 0.5 cm, and the thickness t2 of the air passage is 0.1 to 0.5 cm.

[0041] Preferably, the thickness of the main body 21 is greater than the thickness of the labyrinth unit 22 .

[0042] Preferably, the transmission coefficient spectrum of the microcavity structure 20 is TL=10log 10 (pt / p inc ), p t and p inc are the incident energy and transmitted energy of the microcavity structure, respectively.

[0043] The present invention proposes an angularly gradient maze-type resonant microcavity, which can enable a single subwavelength microunit to simultaneously support multiple low-order resonant modes of different frequencies. This is of great significance for the design of multi-frequency and even broadband sound insulation barriers. Through simulation and numerical calculation analysis, the present invention demonstrates the multi-frequency capture effect of the structure and shows the superiority of the present invention's research with the actual application device of a multi-band omnidirectional ventilated acoustic barrier. The hollow structural design gives it good ventilation characteristics and can meet the requirements of fluid sound insulation scenarios. In addition, the structural geometric parameters can be tailored according to specific needs to obtain the required resonant frequency position or number of resonance peaks, providing new ideas for the design of acoustic multifunctional devices.

[0044] Ginseng Figure 1 The figure shows the structural principle diagram of the multi-band omnidirectional ventilated acoustic barrier. When sound waves pass through the acoustic barrier, they will be blocked and achieve the sound insulation effect. However, air fluid can pass through the acoustic barrier, thus achieving the sound insulation while still maintaining the ventilation effect.

[0045] Ginseng Figure 2a 、 2b The figure shows the basic unit of the acoustic barrier, namely the microcavity structure 20, which has an air groove with a gradient angle in the resin structure. 3D printing technology can easily realize sample preparation. The inner radius is r, the outer radius is R, the thickness of the arc portion is t1, the thickness of the air channel is t2, and the size of the maze unit 22 gradually increases along the angular direction of the structure. The smallest unit angle is θ0, and the angle gradually increases in the counterclockwise direction with an increasing size of Δθ. This micro-unit design scheme is the key to the realization of subwavelength multi-frequency resonance in the present invention, and a single microcavity structure supports multiple low-order resonance modes at the same time, which is of fundamental importance for realizing the design of a multi-band omnidirectional ventilated acoustic barrier structure.

[0046] In one embodiment of the present invention, the specific parameters of the microcavity structure are:

[0047] The radius r of the main body is 1 cm, and the radius R of the microcavity structure is 2.5 cm;

[0048] The number of maze units outside the main body is 8;

[0049] The minimum angle θ0 of the maze unit is 36°, and the increase amplitude Δθ is 2°, that is, the angles are θ0 = 36°, θ1 = 38°, θ2 = 40°, θ3 = 42°, θ4 = 44°, θ5 = 46°, θ6 = 48°, and θ7 = 50°.

[0050] The sum of the opening angles of the slots is 16°, and the opening angle of a single slot is 2°;

[0051] The number of the arc-shaped portions is 5, the thickness t1 of the arc-shaped portions is 0.25 cm, and the thickness t2 of the air passage is 0.25 cm.

[0052] In order to further explore the structural performance of the multi-band omnidirectional ventilated acoustic barrier with subwavelength gradient microcavity, the present invention considers a beam of sound waves incident on the acoustic barrier structure, and uses a numerical solver based on the finite element method to calculate the transmission coefficient spectrum and sound pressure mode distribution of the barrier.

[0053] The mode response of the microcavity structure can be accurately described by calculating the transmission coefficient spectrum (TL), where TL = 10log 10 (p t / p inc ), p t and p inc are the incident energy and transmitted energy of the microcavity structure, respectively. Figure 3a The transmission coefficient spectrum of the present invention is shown in Figure 1. The structure is surrounded by periodic boundary conditions, the sound velocity is 343 m / s, and the resin density is 1.21 kg / m 3 , the sound speed is 2200m / s. Due to the unique unit structure design, the microcavity structure of the present invention has 8 different resonant frequencies, and the transmission loss value TL>10dB within a certain range, which shows that the structure can achieve efficient sound insulation effect within a certain bandwidth range and has good practical performance.

[0054] In order to more intuitively display the resonant mode distribution of the structure, the present invention selects the field distribution at the frequencies corresponding to the four transmission peaks to display, such as Figures 3b to 3e As shown in the figure, it can be found that when the microcavity structure is excited at different frequencies, the microcavity of a specific size will respond, and most of the energy will be concentrated inside the microcavity, thereby achieving the effect of sound insulation. Moreover, by tailoring the geometric dimensions of the structure, such as the inner and outer radii, the sound insulation frequency position can be flexibly adjusted.

[0055] In addition, the present invention has universal applicability and can design more resonance units according to specific application requirements. The microcavity structure can simultaneously achieve resonance responses at ultra-multiple frequencies, which is of great significance for the design of broadband sound insulation devices.

[0056] In order to more intuitively demonstrate the sound insulation effect of the acoustic barrier designed by the present invention, Figure 4Figure 1 shows the sound pressure distribution of the acoustic barrier at different excitation frequencies. The arrows represent the direction of the incident wave. The lower sound pressure distribution at the transmission end indicates that the structure has good sound insulation. The structure is surrounded by periodic boundary conditions. When sound waves are incident on the upper side of the structure, the subwavelength microcavity structure blocks most of the energy through resonance, achieving sound insulation at the transmission end. The structural field distribution at four frequencies is shown here, and it can be intuitively seen that the sound wave energy is effectively blocked by the barrier structure. This means that the structure has good sound insulation at multiple frequencies and can meet the practical application requirements of multi-band omnidirectional ventilated acoustic barriers.

[0057] Considering that in practical applications, viscous loss and thermoviscous loss usually have a certain impact on acoustic resonance devices. Therefore, the transmission coefficient spectrum of the sound barrier structure under different environmental loss conditions was calculated using finite element simulation software. Figure 5a It can be found that compared with the lossless case, the transmission amplitude of the structure is greatly weakened. This is due to the weakening of the microcavity resonance effect under the loss condition. However, TL>10dB can still be maintained at most frequencies, which proves that the structure has good environmental stability and will also have strong adaptability for practical applications.

[0058] In addition, it can be found that as the loss increases, the resonance peak area of ​​the structure tends to be stable, which means that the actual loss may be beneficial to the design of a broadband acoustic barrier in the present invention, which has important reference significance for the design of real devices.

[0059] Due to the specific geometric design, the microcavity structure of the present invention has an air opening with a duty cycle of 16%. Therefore, when airflows of different speeds pass through a section of the structure, different wind speeds can be monitored at the transmission end of the structure, such as Figure 5b The results indicate that the acoustic barrier structure of the present invention has excellent ventilation performance. Furthermore, ventilation efficiency can be further improved by adjusting the size of the internal radial openings of the structure. In summary, a high-performance, multi-band, omnidirectional ventilated acoustic barrier based on a subwavelength gradient microcavity has been achieved.

[0060] This paper constructs and studies an acoustic barrier with a subwavelength gradient microcavity structure. This barrier provides omnidirectional ventilation while also offering excellent low-frequency sound insulation. This means the structure can meet the required sound insulation performance at multiple frequencies, even within a certain bandwidth. The acoustic barrier structure studied in this paper is based on multi-frequency resonance, offering significant advantages over traditional single-frequency resonant sound insulation structures.

[0061] In addition, the number and geometric dimensions of the microcavity structure can be adjusted according to actual needs to achieve flexible control of the number of resonances and the resonance frequency.

[0062] Furthermore, the microcavity structure exhibits efficient ventilation, meeting the practical application requirements of modern acoustic devices. Ventilation efficiency can be further enhanced by adjusting the structure's inner radius. Theoretically, the acoustic barrier structure can be scaled to any desired operating frequency, providing new insights into the design of next-generation multi-frequency resonant microcavities and the application of next-generation sound insulation equipment.

[0063] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0064] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A multi-band omnidirectional ventilated acoustic barrier based on a sub-wavelength gradient microcavity, characterized in that: The acoustic barrier includes a substrate and a plurality of microcavity structures located on the substrate. The microcavity structure includes a main body and a plurality of maze units distributed circumferentially on the outside of the main body. The maze units include a plurality of air channels. The opening angles of the maze units gradually increase, and the opening angles of the slots between adjacent maze units are equal.

2. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 1 is characterized in that: The radius r of the main body is 0.5 cm to 2 cm, and the radius R of the microcavity structure is 2 cm to 10 cm.

3. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 1 is characterized in that: The main body is cylindrical, and the number of the maze units outside the main body is 4 to 20.

4. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 1 is characterized in that: The minimum opening angle θ0 of the maze unit is 30°~50°, and the increase amplitude Δθ is 1°~3°; the sum of the opening angles of the empty slots is 8°~24°, and the opening angle of a single empty slot is 1°~3°.

5. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 1 is characterized in that: The labyrinth unit includes a plurality of arcuate portions arranged from the inside to the outside, a first connecting portion connecting adjacent arcuate portions, and a second connecting portion connecting the innermost arcuate portion and the main body. Air passages are formed between adjacent arcuate portions and between the innermost arcuate portion and the main body.

6. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 5 is characterized in that: The number of the arc-shaped portions is 2 to 10, the thickness t1 of the arc-shaped portions is 0.1 to 0.5 cm, and the thickness t2 of the air passage is 0.1 to 0.5 cm.

7. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 1 is characterized in that: The thickness of the main body is greater than the thickness of the labyrinth unit.

8. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 1 is characterized in that: The transmission coefficient spectrum of the microcavity structure is TL=10log 10 (p t / p inc ), p t and p inc are the incident energy and transmitted energy of the microcavity structure, respectively.

9. The multi-band omnidirectional ventilated acoustic barrier based on subwavelength gradient microcavity according to claim 5 is characterized in that: The radius r of the main body is 1 cm, and the radius R of the microcavity structure is 2.5 cm; and / or, The number of the labyrinth units outside the main body is 8; and / or, The minimum opening angle θ0 of the maze unit is 36°, and the increase amplitude Δθ is 2°; and / or, The sum of the opening angles of the slots is 16°, and the opening angle of a single slot is 2°; and / or, The number of the arc-shaped portions is 5, the thickness t1 of the arc-shaped portions is 0.25 cm, and the thickness t2 of the air passage is 0.25 cm.

10. An acoustic device, characterized in that: The acoustic device comprises the acoustic barrier according to any one of claims 1 to 9.

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