Resonant cavity broadband sound barrier based on double-helix acoustic black holes

Abstract

The invention provides a resonant cavity broadband sound barrier based on a double-helix acoustic black hole. The resonant cavity broadband sound barrier comprises a plurality of double-helix acoustic black hole resonant cavity broadband sound absorption structure cells and a supporting and connecting assembly. The multiple double-spiral acoustic black hole resonant cavity broadband sound absorption structure cells are connected together through the supporting and connecting assemblies, and a plate-shaped sound barrier is formed; the double-spiral acoustic black hole resonant cavity broadband sound absorption structure cell is in the shape of a hollow regular hexagon nut, the inner side face of the cell is open, and six cavities with the inner sides open are formed in the cell. Two spiral curved surface rolling plates with the same or different spiral curve parameters are arranged in each cavity; the curved surface of the spiral curved surface rolling plate is perpendicular to the upper end face and the lower end face of the double-spiral acoustic black hole resonant cavity broadband sound absorption structure cell. A plurality of protruding teeth are distributed on the inner side face and the outer side face of the spiral curved-surface rolling plate. The invention has the advantages that the broadband sound absorption characteristic is realized; certain ventilation and lighting performance is achieved, and the driving environment of an inner channel of the closed traffic sound barrier can be more comfortable.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of traffic noise reduction, and particularly relates to a resonant cavity broadband sound barrier based on a double-helix acoustic black hole. BACKGROUND

[0002] In the increasingly diverse noise pollution pattern of modern cities, traditional sound barriers have shown many limitations that they cannot overcome. As the main force of physical barriers, the noise reduction effect of such barriers is often limited by their physical height. Even if a 5-meter or even higher barrier is set up, it can only effectively protect the adjacent area; the floors beyond the height of the barrier still face the impact of traffic noise, and the noise reduction effect of the barrier decreases sharply with distance and height. More importantly, for low-frequency noise with strong penetration power (such as vibrations caused by heavy vehicles), and sound waves that can bypass the edge of the barrier, traditional structures based on diffraction principles often seem helpless.

[0003] More alarmingly, highly urbanized areas are often accompanied by the superposition of complex noise sources. Large interchanges or dense elevated areas will form a "noise network" in which multiple noise sources overlap each other, and traditional barriers cannot meet the noise reduction needs of global coverage. Modern urban space is scarce, and deploying continuous large-area barriers in the city area often encounters the dilemma of sharply increasing engineering difficulty and uncontrolled cost. In addition, continuous heavy barriers will cut the urban visual space, causing aesthetic controversy and psychological pressure.

[0004] The field of acoustic metamaterials has begun to flourish, and its unique subwavelength size and functional characteristics have shown absolute advantages in sound wave manipulation, such as anomalous refraction and reflection, acoustic holography, and compact perfect sound absorbers. In recent years, the emergence of acoustic metamaterials has also provided new possibilities for the preparation of ventilated sound barriers, using local resonance units (such as Helmholtz resonators, membranes, etc.) to achieve low-frequency noise control at subwavelength scales. Although there have been studies that use multiple resonance methods to broaden the effective sound absorption frequency band, they still limit the bandwidth or reduce the ventilation effect to some extent. Generally, metamaterials used for sound insulation only focus on the internal path design of sound waves and can only achieve narrow-band sound insulation. There have been studies that use the method of multiple resonances of Helmholtz resonators to broaden the effective sound absorption frequency band, but they still limit the bandwidth or reduce the ventilation effect to some extent. In addition, traditional ventilated sound insulation windows are usually composed of curved ventilation pipes lined with sound-absorbing materials or sound-absorbing structures, which increases the flow resistance and is far less effective than direct ventilation paths.

[0005] Acoustic black hole (ABH) is a passive vibration control technology. From a general point of view, the ABH effect is achieved by embedding local inhomogeneities in thin-walled structures (usually beams or plates). According to the spatial power law distribution, this inhomogeneity is characterized by a change in the geometric properties. The combination of local stiffness reduction due to the power law variation of the wall thickness and the local damping increase provided by the simultaneous application of a viscoelastic layer leads to a significant reduction of the wave speed and to a significant enhancement of the attenuation properties. When an elastic wave propagates inside the ABH, its speed smoothly and continuously decreases. In the ideal case, i.e. when the wall thickness vanishes at the center of the ABH, the wave speed reduces to zero, thus achieving the effect of sound absorption and noise reduction.

[0006] In addition, the actual use of the road sound barrier is mainly in the "upright type", and the diffraction attenuation effect is obviously insufficient. In order to improve this shortcoming, the commonly used method is to increase the top structure on the basis of the "upright type" sound barrier. These top structures mainly change the angle and shape of the top end of the sound barrier, and increase the equivalent height of the sound barrier. However, the increase of the traditional sound barrier top structure makes the overall height of the sound barrier higher, thereby reducing the light transmittance of the sound barrier; the traditional closed sound barrier will cause the internal temperature to rise, form a reverberation effect inside, and at the same time affect the driving vision under natural light conditions, in addition, in order to guarantee the ventilation and air exchange inside the sound barrier, an additional ventilation system must be installed, which directly increases the budget, so the traditional closed sound barrier needs to be improved. SUMMARY

[0007] The purpose of the present application is to overcome the defects of the overall height of the existing sound barrier being too high, and the poor light transmittance and ventilation.

[0008] In order to achieve the above purpose, the present application provides a double-helix acoustic black hole based resonant cavity broadband sound barrier, which comprises: a plurality of double-helix acoustic black hole resonant cavity broadband sound absorption structure cells and a support connecting assembly; The support connecting assembly connects the plurality of double-helix acoustic black hole resonant cavity broadband sound absorption structure cells together to form a plate-shaped sound barrier; The double-helix acoustic black hole resonant cavity broadband sound absorption structure cell is in the shape of a hollow regular hexagonal nut, and the inner surface is open; The six faces formed by the lines connecting the six outer vertices of the upper and lower end faces of each double-helix acoustic black hole resonant cavity broadband sound absorption structure cell with the corresponding inner vertices divide the double-helix acoustic black hole resonant cavity broadband sound absorption structure cell into six cavities, and each cavity is closed to each other; Each cavity is internally provided with two spiral curved surface coils with the same or different spiral curve parameters; The curved surface of the spiral curved surface coil is perpendicular to the upper and lower end faces of the double-helix acoustic black hole resonant cavity broadband sound absorption structure cell. The starting end of the two spiral curved plates in the cavity is fused together to form a flat plate; the starting end of the flat plate is located in the middle of the opening side of the cavity and extends to the inside of the cavity; the end of the flat plate is spirally curled to form two spiral curved plates on both sides of the middle of the cavity; the inner and outer sides of the spiral curved plates are provided with a plurality of protruding teeth.

[0009] As an improvement of the above-mentioned sound barrier, the height of the teeth on the inner and outer sides of the spiral curved plate gradually increases from the outer ring to the inner ring.

[0010] As an improvement of the above-mentioned sound barrier, the height of the highest tooth on the spiral curved plate is less than the spacing between the inner and outer rings of the spiral curved plate.

[0011] As an improvement of the above-mentioned sound barrier, the positions of the teeth on the inner and outer sides of the spiral curved plate are staggered.

[0012] As an improvement of the above-mentioned sound barrier, the outer side of the outermost ring and the inner side of the innermost ring of the spiral curved plate are not provided with teeth.

[0013] As an improvement of the above-mentioned sound barrier, the shell thickness of the double-helix acoustic black hole resonant cavity wide-frequency sound absorption structure cell is uniform.

[0014] As an improvement of the above-mentioned sound barrier, the material of the double-helix acoustic black hole resonant cavity wide-frequency sound absorption structure cell is aluminum alloy.

[0015] As an improvement of the above-mentioned sound barrier, the material of the support connecting assembly is cast iron or stainless steel.

[0016] Compared with the prior art, the advantages of the present application are: 1. The closed sound barrier has wide-frequency sound absorption characteristics because it combines the Helmholtz resonant cavity and the acoustic black hole, which makes up for the narrow sound absorption frequency band of the traditional closed traffic sound barrier.

[0017] 2. In the present application, the center of the double-helix acoustic black hole resonant cavity wide-frequency sound absorption structure is through, so it also has certain ventilation and lighting performance, which can make the driving environment in the internal passage of the closed traffic sound barrier more comfortable. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure shows the formation principle of the spiral curved plate in the spiral acoustic black hole resonant cavity wide-frequency sound absorption structure cell; Figure 2 The figure shows a cavity structure of the spiral acoustic black hole resonant cavity wide-frequency sound absorption structure cell; Figure 3It is shown that the double helix acoustic black hole resonant cavity broadband sound absorption structure cell structure schematic diagram and sectional view. Figure 4 It is shown that the double helix acoustic black hole resonant cavity broadband sound barrier structure schematic diagram. Figure 5 It is shown that the spiral curve of the spiral curved surface roll plate. Figure 6 It is shown that the double helix acoustic black hole resonant cavity broadband sound barrier sound insulation schematic diagram. DETAILED DESCRIPTION

[0019] The technical scheme of the present application will be described in detail below with reference to the accompanying drawings.

[0020] The technical problem solved by the present application is to provide a double helix acoustic black hole resonant cavity broadband sound barrier, which can not only have good sound absorption function, but also have certain ventilation and lighting performance, so that the noise of high-speed rail viaduct, highway, urban light rail and subway can be significantly reduced by 60~75dB, and the environmental noise limit value suitable for work and life can be reached.

[0021] As Figures 1-4 The double helix acoustic black hole resonant cavity broadband sound barrier provided by the present application comprises a double helix acoustic black hole resonant cavity broadband sound absorption structure cell 2 and a support connecting assembly 1, the double helix acoustic black hole resonant cavity broadband sound absorption structure cell 2 is combined into a whole through the support connecting assembly 1, and the support connecting part is sealed.

[0022] The double helix acoustic black hole resonant cavity broadband sound absorption structure cell 2 is a hexagonal structure with equal thickness shell, six double helix Helmholtz acoustic black hole resonant cavity units with different volumes are built in the center of the hexagon, the volume of the Helmholtz resonant cavity can be changed by changing the parameters of the spiral curve, and the frequency range of sound absorption can be changed; and the acoustic black hole can absorb the energy of the incident sound wave and convert it into heat energy, and the sound absorption coefficient can be improved by adjusting the distance between the partitions. Therefore, a series of double helix Helmholtz acoustic black hole resonant cavities ensure that the sound absorption structure has a broadband sound absorption effect.

[0023] The double-helix acoustic black hole resonator broadband sound absorption structure cell 2 is a hollow regular hexagonal nut shape with an equal thickness shell, and the inner surface is open. The regular hexagonal nut structure exhibits excellent mechanical properties when subjected to tensile, compressive and shear loads, so the hexagonal nut structure is used as the sound absorption unit in the present application, which can ensure sound absorption effect while also considering structural strength. The six faces formed by the lines connecting the six outer vertices of the upper and lower end faces of each double-helix acoustic black hole resonator broadband sound absorption structure cell 2 and the corresponding inner vertices divide the double-helix acoustic black hole resonator broadband sound absorption structure cell 2 into 6 cavities, and each cavity is closed by the shell. Two spiral curved surface coils with the same or different spiral curve parameters are placed in each cavity to form spiral Helmholtz resonators with the same or different volumes. The curved surfaces of the two spiral curved surface coils are perpendicular to the upper and lower end faces of the double-helix acoustic black hole resonator broadband sound absorption structure cell 2. Different spiral curve parameters form different Helmholtz resonator volumes, thereby changing the sound absorption frequency range. The starting ends of the two spiral curved surface coils are fused together to form a flat panel. The starting end of the flat panel is a flat panel extending from the middle of the opening side of the cavity to the inside of the cavity. The end of the flat panel is spirally curled to form two spiral curved surface coils on both sides of the middle of the cavity. The inner and outer sides of the spiral curved surface coils are distributed with multiple protruding teeth, and the height of the teeth gradually increases from the outer ring to the inner ring, but the height of the highest tooth is less than the distance between the inner and outer rings. The positions of the inner and outer teeth are staggered. The outer side of the outermost ring and the inner side of the innermost ring have no teeth.

[0024] As shown in Figure 5 , the spiral curve of the spiral curved surface coil can be represented as: x=A*(1+t)*cos(2*π*t) y=B*(1+t)*sin(2*π*t) Where A, B are parameters that control the spiral line, i.e., control the volume of the wheel spiral coil.

[0025] As shown in Figure 6As shown, the application provides a double-helix acoustic black hole resonant cavity broadband sound barrier, in terms of sound absorption, using a double-helix Helmholtz resonant cavity for sound absorption, when sound waves propagate to the inside of the spiral resonant cavity of different volumes, and then resonance effect is produced to reduce the sound pressure value; at the same time, the acoustic black hole can absorb acoustic energy to a certain extent, thereby reducing the noise pollution caused by vehicles and trains; the sound absorption structure is connected at both ends, so the sound barrier can combine the advantages of ventilation and lighting, and comprehensively optimize the driving experience in the sound barrier. The size and thickness of the honeycomb unit can be changed, and the volume of the resonant cavity can be changed to comprehensively optimize the ventilation and sound absorption performance of the barrier, so as to achieve the best. It can be said that the barrier is an organic combination of the concepts of sound barrier, light and wind barrier, which has the advantages of high efficiency, rationality, simplicity, convenience, novelty and beauty, is suitable for promotion, and has obvious economic benefits.

[0026] In a preferred embodiment of the application, the material of the double-helix acoustic black hole resonant cavity broadband sound absorption structure cell 2 is aluminum alloy and its products, and the material of the support connecting assembly 1 can use cast iron or stainless steel and its products.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the application and are not limiting. Although the application has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the application do not deviate from the spirit and scope of the application, and they should be covered in the scope of the claims of the application.

Claims

1. A broadband sound barrier with a resonant cavity based on a double-helix acoustic black hole, characterized in that, The sound barrier includes: Multiple double-helix acoustic black hole resonant cavity broadband sound-absorbing structural cells and supporting connection components; The supporting connection assembly connects multiple double-helix acoustic black hole resonant cavity broadband sound-absorbing structural cells together to form a plate-shaped sound barrier. The broadband sound-absorbing structure cell of the double-helix acoustic black hole resonant cavity is a hollow regular hexagonal nut shape with an opening on the inner side. The six faces formed by connecting the six outer vertices of the upper and lower end faces of each of the double-helix acoustic black hole resonant cavity broadband sound-absorbing structural cells with the corresponding inner vertices divide the double-helix acoustic black hole resonant cavity broadband sound-absorbing structural cells into six cavities, and each cavity is mutually closed. Each cavity contains two spiral surface plates with the same or different spiral curve parameters; The surface of the spiral curved plate is perpendicular to the upper and lower end faces of the broadband sound-absorbing structure cell of the double-helix acoustic black hole resonant cavity. The starting ends of the two spiral curved plates in the cavity are fused together to form a flat plate; the starting end of the flat plate is located in the middle of the cavity opening side and extends into the cavity; the end of the flat plate spirals outwards to both sides in the middle of the cavity to form two spiral curved plates; the inner and outer sides of the spiral curved plates are distributed with multiple protruding teeth.

2. The broadband sound barrier based on a double-helix acoustic black hole according to claim 1, characterized in that, The height of the teeth on the inner and outer sides of the spiral curved plate gradually increases from the outer ring to the inner ring.

3. The broadband sound barrier based on a double-helix acoustic black hole according to claim 2, characterized in that, The height of the highest tooth on the helical surface plate is less than the distance between the inner and outer rings of the helical surface plate.

4. The broadband sound barrier based on a double-helix acoustic black hole according to claim 3, characterized in that, The teeth on the inner and outer sides of the spiral curved plate are arranged in an alternating pattern.

5. The broadband sound barrier based on a double-helix acoustic black hole according to claim 4, characterized in that, The outermost edge and the innermost edge of the spiral curved plate have no teeth.

6. The broadband sound barrier based on a double-helix acoustic black hole according to claim 1, characterized in that, The shell thickness of the broadband sound-absorbing structure cell of the double-helix acoustic black hole resonant cavity is uniform.

7. The broadband sound barrier based on a double-helix acoustic black hole according to claim 1, characterized in that, The cell of the broadband sound-absorbing structure of the double-helix acoustic black hole resonant cavity is made of aluminum alloy.

8. The broadband sound barrier based on a double-helix acoustic black hole according to claim 1, characterized in that, The supporting connection component is made of cast iron or stainless steel.

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