Plate-mold composite sound absorption structure and building wall surface of transformer substation

Abstract

The invention discloses a plate-formwork composite sound absorption structure and a building wall surface of a transformer substation. Relates to the field of sound absorption structures, and the structure comprises a microwell plate which is provided with a plurality of first through holes; a plurality of second through holes are formed in the microporous film, the microporous film is attached to the microporous plate, the second through holes are smaller than or equal to the first through holes, and the second through holes are communicated with the first through holes. According to the invention, the technical problem of low use flexibility of the sound absorption structure caused by the sound absorption effect of the sound absorption structure based on the microplate in the related art is solved.

Description

Technical Field

[0001] The present invention relates to the field of sound absorption structures, and more particularly, to a plate-mould composite sound absorption structure and a building wall surface of a substation. Background Art

[0002] With the rapid development of industrial technology, mechanical equipment plays an increasingly important role in all walks of life. However, the operation of these devices is often accompanied by vibration and noise. Long-term or abnormal vibration and noise not only affect the performance and lifespan of the devices, but may also have an adverse impact on the production environment and the health of personnel. Especially in substations, due to their operating characteristics, facilities such as transformers, reactors, and ventilation facilities operate at different times, and the overall emitted noise frequency changes with the load. Therefore, the application of sound absorption structures is very important. Currently, the sound absorption structures in related technologies achieve the sound absorption effect based on micro-perforated plates, resulting in the problem of low flexibility in the use of sound absorption structures.

[0003] In response to the above problems, no effective solution has been proposed yet. Summary of the Invention

[0004] Embodiments of the present invention provide a plate-mould composite sound absorption structure and a building wall surface of a substation to at least solve the technical problem that the sound absorption structure in related technologies achieves the sound absorption effect based on micro-perforated plates, resulting in low flexibility in the use of the sound absorption structure.

[0005] According to one aspect of the embodiments of the present invention, a plate-mould composite sound absorption structure is provided, including: a micro-perforated plate provided with a plurality of first through-holes; a micro-perforated film provided with a plurality of second through-holes, the micro-perforated film being attached to the micro-perforated plate, the second through-holes being smaller than or equal to the first through-holes, and the second through-holes communicating with the first through-holes.

[0006] Further, the number of the first through-holes is the same as that of the second through-holes.

[0007] Further, the hole pitch of the first through-holes is the same as that of the second through-holes.

[0008] Further, the axis of the first through-hole is the same as that of the second through-hole.

[0009] Further, the first through-holes and the second through-holes are arranged in a square grid pattern.

[0010] Further, the second through-holes are circular holes or slit holes.

[0011] Further, the thickness of the micro-perforated plate is greater than the thickness of the micro-perforated film.

[0012] Further, the micro-perforated plate is one of the following: an aluminum plate, an iron plate, a steel plate, a copper plate, a wooden plate.

[0013] Furthermore, the microporous film is aluminum foil.

[0014] According to another aspect of the embodiments of the present invention, a building wall surface of a substation is further provided, and the above-mentioned board-mold composite sound-absorbing structure is arranged on the building wall surface of the substation.

[0015] In the embodiments of the present invention, since the second through-hole is smaller than the first through-hole, in the board-mold composite sound-absorbing structure provided by the present invention, the sound-absorbing effect is substantially achieved based on the microporous board provided with the second through-hole. Furthermore, since the microporous film is more convenient to process than the microporous board, and the microporous board only needs to be adhered to the microporous board, when it is necessary to adjust the sound-absorbing performance of the board-mold composite sound-absorbing structure, it is not necessary to replace the microporous board, but only to replace the microporous film, and the replacement of the microporous film is more convenient than the replacement of the microporous board. Therefore, the flexibility of use of the board-mold composite sound-absorbing structure can be effectively improved. In addition, laminating the film on a board with a larger pore diameter and thickness helps to increase the mechanical strength of the structure, and the additional acoustic impedance of the large pores is smaller, having less influence on the sound-absorbing performance of the overall structure.

[0016] It can be seen that the solution provided by the present application achieves the purpose of realizing the sound-absorbing effect based on the microporous film, thereby realizing the technical effect of improving the flexibility of use of the board-mold composite sound-absorbing structure, and further solving the technical problem that the flexibility of use of the board-mold composite sound-absorbing structure in the related art is low due to the sound-absorbing effect being achieved based on the microporous board. Description of the Drawings

[0017] The drawings described herein are used to provide a further understanding of the present invention, form a part of this application, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 is a schematic diagram of an optional board-mold composite sound-absorbing structure according to an embodiment of the present invention Figure 1 ;

[0019] Figure 2 is a schematic diagram of an optional board-mold composite sound-absorbing structure according to an embodiment of the present invention Figure 2 ;

[0020] Figure 3 is a schematic diagram of an optional simulation model according to an embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of an optional cross-sectional average sound pressure distribution according to an embodiment of the present invention;

[0022] Figure 5 is a schematic diagram of an optional cross-sectional average velocity distribution according to an embodiment of the present invention;

[0023] Figure 6 is a schematic diagram of an optional cross-sectional average energy loss density distribution according to an embodiment of the present invention;

[0024] Figure 7 is a schematic diagram of the relative acoustic resistance of an optional first structure according to an embodiment of the present invention;

[0025] Figure 8 is a schematic diagram of the relative acoustic reactance of an optional first structure according to an embodiment of the present invention;

[0026] Figure 9 is a schematic diagram of the relative acoustic resistance of an optional second structure according to an embodiment of the present invention;

[0027] Figure 10 is a schematic diagram of the relative acoustic reactance of an optional second structure according to an embodiment of the present invention;

[0028] Figure 11 is a schematic diagram of the sound absorption coefficient curve of an optional first structure according to an embodiment of the present invention;

[0029] Figure 12 is a schematic diagram of the sound absorption coefficient curve of an optional second structure according to an embodiment of the present invention;

[0030] Figure 13 is a schematic diagram of an optional experimental sample corresponding to the second structure according to an embodiment of the present invention Figure 1 ;

[0031] Figure 14 is a schematic diagram of an optional experimental sample corresponding to the second structure according to an embodiment of the present invention Figure 2 ;

[0032] Figure 15 is a schematic diagram of the test results of an optional experimental sample according to an embodiment of the present invention. Detailed implementation manners

[0033] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0035] Embodiment 1

[0036] According to an embodiment of the present invention, an embodiment of a plate-mold composite sound-absorbing structure is provided. Figure 1 is a schematic diagram of an optional plate-mold composite sound-absorbing structure according to an embodiment of the present invention Figure 1 , as Figure 1 shown, the device includes:

[0037] A microporous plate 10, on which a plurality of first through holes 11 are provided;

[0038] A microporous film 20, on which a plurality of second through holes 21 are provided. The microporous film 20 is attached to the microporous plate 10. The second through holes 21 are smaller than or equal to the first through holes 11, and the second through holes 21 communicate with the first through holes 11.

[0039] According to the microporous sound absorption and noise reduction theory, the thin film sound absorption theory, and the variable cross-section plate-mold composite sound absorption structure, reducing the pore diameter and the perforation rate and increasing the plate thickness contribute to increasing the acoustic resistance of the microperforated plate-mold composite sound absorption structure. Reducing the pore diameter and the plate thickness and increasing the perforation rate are beneficial to reducing the acoustic reactance of the structure. Therefore, a balance between sufficient acoustic resistance and small acoustic reactance can be achieved by means of a smaller pore diameter matching a larger perforation rate and plate thickness.

[0040] In some embodiments, the second through holes 21 being smaller than or equal to the first through holes 11 means that the opening area of the second through holes 21 is smaller than or equal to the opening area of the first through holes 11.

[0041] For example, the second through holes 21 being smaller than or equal to the first through holes 11 means that the diameter of the second through holes 21 is smaller than or equal to the diameter of the first through holes 11.

[0042] For another example, the second through holes 21 being smaller than or equal to the first through holes 11 means that both the length and width of the second through holes 21 are smaller than or equal to the diameter of the first through holes 11.

[0043] For another example, the second through-hole 21 being less than or equal to the first through-hole 11 means that the diameter of the second through-hole 21 is less than or equal to the length and width of the first through-hole 11.

[0044] For another example, the second through-hole 21 being less than or equal to the first through-hole 11 means that the length of the second through-hole 21 is less than or equal to the length of the first through-hole 11, and the width of the second through-hole 21 is less than or equal to the width of the first through-hole 11.

[0045] In this embodiment, as Figure 1 shown, a relatively large first through-hole 11 is machined on the microplate 10, and a relatively small second through-hole 21 is machined on the microfilm 20. The microfilm 20 is attached to the microplate 10, and the second through-hole 21 and the first through-hole 11 communicate with each other so that sound waves can effectively pass through the second through-hole 21 and the first through-hole 11 and enter the sound-absorbing back cavity, where the diameter of the small hole is d 1 , the diameter of the large hole is d 2 , the thickness of the small hole (i.e., the thickness of the microfilm 20) is t 1 , the thickness of the large hole (i.e., the thickness of the microplate 10) is t 2 , and the hole pitch is b. An optional set of parameters can be as shown in Table 1:

[0046] Table 1

[0047]

[0048] The acoustic impedance of the structure can be obtained by superimposing the acoustic impedance of the plate, the acoustic impedance of the film vibration, the acoustic impedance of the holes on the film, and the acoustic impedance at the abrupt change between the two holes. For Figure 1 the structure formed by the microplate 10 and the microfilm 20 shown in, only the film at the large hole (i.e., the first through-hole 11) will vibrate. Since the diameter of the large hole is small, the additional acoustic impedance due to the film vibration is also small and its influence can be neglected. Also, for the above structure, machining micro-holes with a relatively large perforation rate on the film is likely to achieve better sound-absorbing performance. In addition, by changing specific parameters such as the hole diameter, perforation rate, plate thickness, cavity depth, and hole shape, the purpose of adjusting the noise absorption ratio can be achieved.

[0049] In some embodiments, the plate-mold composite sound-absorbing structure further includes a groove member, on which there is a groove. The microporous plate 10 is disposed at the notch end of the groove member, and a closed sound-absorbing back cavity is formed between the microporous plate 10 and the groove member. The microporous film 20 is single-layered and is attached to the side of the microporous plate 10 away from the groove member. Sound waves pass through the second through-holes 21 and the first through-holes 11 in sequence and enter the sound-absorbing back cavity. When the sound waves propagate in the through-holes, they will rub against the hole walls, and at the same time, the viscous effect of the sound waves will also occur in the holes. These effects will convert the energy of the sound waves into heat energy, thereby achieving sound absorption. When the sound waves enter the sound-absorbing back cavity, the sound-absorbing back cavity can effectively shift the resonance sound-absorbing frequency towards the low-frequency direction and increase the sound-absorbing coefficient. The vibration of the gas in the back cavity and the microporous plate 10 act together to enhance the sound-absorbing effect.

[0050] It should be noted that in the embodiments of the present invention, since the second through-holes 21 are smaller than the first through-holes 11, in the plate-mold composite sound-absorbing structure provided by the present invention, the sound-absorbing effect is substantially achieved based on the microporous plate 10 provided with the second through-holes 21. Further, since the microporous film 20 is more convenient to process than the microporous plate 10, and the microporous film 20 only needs to be attached to the microporous plate 10, when it is necessary to adjust the sound-absorbing performance of the plate-mold composite sound-absorbing structure, it is not necessary to replace the microporous plate 10, but only to replace the microporous film 20. Moreover, the replacement of the microporous film 20 is more convenient than the replacement of the microporous plate 10. Therefore, the use flexibility of the plate-mold composite sound-absorbing structure can be effectively improved. In addition, laminating the film on a plate with a larger pore diameter and thickness helps to increase the mechanical strength of the structure, and the additional acoustic impedance of the large holes is small, having little impact on the sound-absorbing performance of the overall structure.

[0051] It can be seen that the solution provided by the present application achieves the purpose of realizing the sound-absorbing effect based on the microporous film 20, thereby achieving the technical effect of improving the use flexibility of the plate-mold composite sound-absorbing structure, and further solving the technical problem that the use flexibility of the plate-mold composite sound-absorbing structure in the related art is low because the sound-absorbing effect is achieved based on the microporous plate 10.

[0052] In an alternative embodiment, the number of the first through-holes 11 is the same as that of the second through-holes 21.

[0053] For example, Figure 1 the number of the first through-holes 11 and the second through-holes 21 shown in

[0054] It should be noted that based on this structure, each first through-hole 11 has a second through-hole 21 communicating with it, and each second through-hole 21 has a first through-hole 11 communicating with it, thus avoiding the ineffective setting of the first through-holes 11 and the second through-holes 21, which affects the manufacturing cost, manufacturing efficiency and sound-absorbing effect of the plate-mold composite sound-absorbing structure.

[0055] In an alternative embodiment, the hole pitch of the first through-hole 11 is the same as that of the second through-hole 21.

[0056] For example, Figure 1 the hole pitch of the first through-hole 11 and the second through-hole 21 shown in is the same. The hole pitch of the first through-hole 11 and the second through-hole 21 can be set to 2.5 mm.

[0057] Optionally, the hole pitch of the first through-hole 11 (or the second through-hole 21) is determined based on the distance between the axes of adjacent first through-holes 11 (or second through-holes 21).

[0058] It should be noted that based on this structure, it is convenient to align the first through-hole 11 with the second through-hole 21, so that each second through-hole 21 can effectively communicate with the first through-hole 11, thereby improving the sound absorption effect.

[0059] In an alternative embodiment, the axis of the first through-hole 11 is the same as the axis of the second through-hole 21.

[0060] For example, as Figure 1 shown, when both the first through-hole 11 and the second through-hole 21 are circular holes, the cross-sections of the first through-hole 11 and the second through-hole 21 are concentric circles.

[0061] It should be noted that based on this structure, a part of the holes of the second through-hole 21 is prevented from being blocked by the plate surface of the micro-perforated plate 10, thereby further improving the sound absorption effect.

[0062] In an alternative embodiment, the first through-holes 11 and the second through-holes 21 are arranged in a square grid.

[0063] For example, Figure 1 the first through-holes 11 and the second through-holes 21 shown in are arranged in a square grid.

[0064] It should be noted that based on this structure, the plate-film composite structure has a uniform sound absorption effect in all directions, thereby improving the overall sound absorption effect of the plate-film composite structure.

[0065] In an alternative embodiment, the second through-hole 21 is a circular hole or a slit hole.

[0066] Optionally, the circular hole and the slit hole can be selected according to specific sound absorption requirements. The circular hole is easy to process, convenient for practical engineering applications, and has stable sound absorption performance under the same cross-sectional area. Under specific conditions, the slit hole has more advantages. For example, Figure 1 the second through-hole 21 in is a circular hole.

[0067] Optionally, the slit hole can be a micro-slit opening formed by scratching the microporous film 20 with a wallpaper knife, and the slit width is about 0.1 mm. The slit hole has the advantage of the smallest acoustic reactance under the same acoustic resistance or being able to provide the largest acoustic resistance with the smallest acoustic reactance. The smaller acoustic reactance and the smaller change rate of the acoustic reactance with frequency contribute to expanding the sound absorption bandwidth of the micro-perforated plate structure.

[0068] For example, Figure 2 is a schematic diagram of an optional plate-mold composite sound absorption structure according to an embodiment of the present invention Figure 2 , such as Figure 2 shown, the first through holes 11 with larger apertures are processed on the microporous plate 10, and the second through holes 21 with smaller slit widths are processed on the microporous film 20, where the slit width of the second through hole 21 is l 11 , and the slit length is l 12 . An optional parameter can be as shown in Table 2:

[0069] Table 2

[0070]

[0071] It should be noted that based on this structure, the flexibility of the application of the plate-mold composite sound absorption structure is improved.

[0072] In an optional embodiment, the thickness of the microporous plate 10 is greater than the thickness of the microporous film 20.

[0073] This difference in thickness can enhance the mechanical strength of the structure while maintaining good sound absorption performance, thereby reducing the degradation of acoustic performance caused by physical damage.

[0074] In an optional embodiment, the microporous plate 10 is one of the following: aluminum plate, iron plate, steel plate, copper plate, wood board.

[0075] Optionally, different material selections can meet different environmental requirements. For example, an aluminum plate is suitable for occasions that require light weight and corrosion resistance, and a copper plate has good thermal conductivity and is suitable for buildings or devices where heat dissipation requirements need to be considered. Thus, the applicability of the plate-mold composite sound absorption structure provided by the present application can be improved.

[0076] In an optional embodiment, the microporous film 20 is an aluminum foil.

[0077] Optionally, using an aluminum foil as the microporous film 20 not only has good sound absorption performance but also has excellent weather resistance and durability, and is suitable for sound absorption structures in outdoor or high-humidity environments, such as tunnels and bridges. Thus, the reliability of the plate-mold composite sound absorption structure provided by the present application can be improved.

[0078] In an alternative embodiment, a finite element model of the micro-perforated plate structure can be established by means of the numerical simulation acoustic module's thermo-viscous acoustic frequency domain physical field interface, and physical parameter distributions such as the sound pressure, velocity, temperature, and thermo-viscous energy loss of the structure can be accurately obtained, the acoustic behavior occurring inside and outside the holes can be explored, and the transfer impedance and sectional acoustic impedance of the structure can be calculated. Among them, the temperature refers to the actual working temperature of the micro-perforated plate structure under the action of sound waves and the influence of possible environmental factors, and the thermo-viscous energy loss refers to the energy loss generated by the sound waves during propagation due to viscous and heat conduction effects. Considering that the computational cost of solving thermo-viscous acoustic problems is extremely high, therefore, only solving the system components related to thermo-viscous physical phenomena can often effectively reduce the amount of computation. Generally, the micro-holes (i.e., the first through-hole and the second through-hole 21) are periodically distributed, and a basic unit can be selected for research. Without loss of generality, the micro-holes are distributed in a square lattice (i.e., a square grid), and the micro-holes are located at the center of the square panel. The unit is centrosymmetrically distributed. By performing three-dimensional numerical simulation of the thermo-viscous acoustic frequency domain interface on 1 / 4 of the unit, the physical problem can be illustrated and the computational cost can be significantly reduced.

[0079] Optionally, Figure 3 is a schematic diagram of an alternative simulation model according to an embodiment of the present invention, as Figure 3 shown. The simulation model is composed of pores, air domains at both ends of the pores, and perfectly matched layers (PMLs) at both ends of the air domains. Among them, the aforementioned pores refer to the pores jointly formed by the first through-hole 11 and the second through-hole 21. The perfectly matched layer is a special medium layer used to simulate an open domain or an infinite domain. The wave impedance of this layer of medium is completely matched with the wave impedance of the adjacent medium. Sound waves can pass through the interface without reflection and enter the perfectly matched layer, and are completely absorbed without reflected waves returning. The coordinate origin is set at the geometric center of the left end cross-section of the small hole segment (i.e., the simulation modeling corresponding to the second through-hole 21). The air domain with x < 0 is set as the background sound field with a unit amplitude of plane wave incidence. The thicknesses of the air domain and the perfectly matched layer are respectively set to 1 / 3 times and 2 / 3 times the total thickness of the structure. The holes and the air domain are both divided into free tetrahedral non-structural meshes. Among them, the maximum size of the meshes on the edges and faces in contact with the plate is set to the viscous boundary layer thickness, and the maximum size of the other meshes is set to 1 / 10 of the diameter of the large hole segment, i.e., d2 / 10. The meshes of the perfectly matched layer are divided by the sweeping method, and the number of mesh layers is not less than 6 layers. The faces in contact with the plate are all set as non-slip wall boundary conditions, the symmetry planes (y = 0 and z = 0) are all set as symmetric boundary conditions, and the sides of the air domain and the perfectly matched layer (y = b / 2 and z = b / 2) are all set as slip wall boundary conditions.

[0080] The sectional average sound pressure distribution at a frequency of 1000 Hz obtained by simulation is as Figure 4As shown, the cross-sectional average velocity distribution at a frequency of 1000 Hz is as follows Figure 5 As shown, the axial distribution of the cross-sectional average energy loss at a frequency of 1000 Hz is as follows Figure 6 As shown Figure 4 As shown, the cross-sectional average sound pressure approximately varies linearly in both the small-hole section (i.e., the simulation model corresponding to the second through-hole 21) and the large-hole section (i.e., the simulation model corresponding to the first through-hole 11), and the sound pressure gradient in the small-hole section is relatively large Figure 5 As shown, the cross-sectional average velocity approximately remains unchanged in both the small-hole section and the large-hole section. The velocity in the small-hole section is relatively large, and the velocity shows a trend of first increasing and then decreasing outward (or towards the large-hole end) at the abrupt change of the micro-hole geometric size Figure 6 As shown, the cross-sectional average viscous-thermal energy loss approximately remains unchanged in both the small-hole section and the large-hole section. The energy loss in the small-hole section is relatively large, and a peak value of the energy loss appears at the abrupt change and gradually decreases outward (or towards the large-hole end). Abrupt changes occur in the sound pressure, velocity, and energy loss at the geometric parameter discontinuities such as the end of the small hole, the connection between the small hole and the large hole, and the end of the large hole

[0081] Optionally, the structural transfer impedance obtained by simulation is as follows

[0082]

[0083] where Δp is the sound pressure difference across the pore ends where ta.p_t is the total sound pressure, S inlet is the plane where the inlet end of the micro-pore (i.e., the left end of the small-hole section) is located, S outlet is the plane where the outlet end of the micro-pore (i.e., the right end of the large-hole section) is located, U is the average volume velocity in the pore. For a variable cross-section structure where t is the plate thickness, ta.u_tx is the axial component of the total velocity of air particle vibration in the pore, and Ω is the region composed of the pores of the simulation unit. Considering the characteristic impedance of air, its relative acoustic impedance is z T =Z T / ρ 0 c 0 .

[0084] Optionally, the plate-mode composite sound-absorbing structure formed by the micro-pore film 20 and the micro-pore plate 10 when the second through-hole 21 is a circular hole is determined as the first structure, and the plate-mode composite sound-absorbing structure formed by the micro-pore film 20 and the micro-pore plate 10 when the second through-hole 21 is a slit hole is determined as the second structure

[0085] Optionally Figure 7 is a schematic diagram of the relative acoustic resistance of an optional first structure according to an embodiment of the present invention Figure 7 shows the comparison result of the relative acoustic resistance obtained by simulation of the first structure and the relative acoustic resistance calculated using the theoretical modelFigure 8 Schematic diagram of the relative acoustic resistance of an optional first structure according to an embodiment of the present invention, Figure 8 showing the comparison result of the relative acoustic resistance obtained by simulating the first structure and the relative acoustic resistance calculated using the theoretical model, Figure 9 Schematic diagram of the relative acoustic impedance of an optional second structure according to an embodiment of the present invention, Figure 9 showing the comparison result of the relative acoustic impedance obtained by simulating the second structure and the relative acoustic impedance calculated using the theoretical model, Figure 10 Schematic diagram of the relative acoustic resistance of an optional second structure according to an embodiment of the present invention, Figure 10 showing the comparison result of the relative acoustic resistance obtained by simulating the first structure and the relative acoustic resistance calculated using the theoretical model, as Figure 7 、 Figure 8 、 Figure 9 and Figure 10 shown, the calculation result of the theoretical model is in good agreement with the structural transfer impedance obtained by numerical analysis. Assuming that a back cavity with a thickness of 50 mm is provided at the rear of the micro-perforated panel, the sound absorption coefficient curve of the first structure is as Figure 11 shown, Figure 11 Schematic diagram of the sound absorption coefficient curve of an optional first structure according to an embodiment of the present invention, Figure 11 showing the comparison result of the sound absorption coefficient curve obtained by simulating the first structure and the sound absorption coefficient curve calculated using the theoretical model. The sound absorption coefficient curve of the second structure is as Figure 12 shown, Figure 12 Schematic diagram of the sound absorption coefficient curve of an optional second structure according to an embodiment of the present invention, Figure 12 showing the comparison result of the sound absorption coefficient curve obtained by simulating the second structure and the sound absorption coefficient curve calculated using the theoretical model. As Figure 11 、 12 shown, the resonance frequency, maximum sound absorption coefficient and effective sound absorption bandwidth calculated by the theoretical model are all in good agreement with the numerical simulation results. The maximum sound absorption coefficient of the first structure in the current scenario is 0.98, and the ratio of the upper and lower limits of the effective sound absorption frequency (the frequency range where the sound absorption coefficient is greater than 0.5) is 4.75. The maximum sound absorption coefficient of the second structure in the current scenario is 1.0, and the ratio of the upper and lower limits of the effective sound absorption frequency is 5.0. It can be seen that in the current scenario, the sound absorption performance of the second structure is better than that of the first structure.

[0086] Optionally, both the previous theoretical model calculations and numerical simulation results indicate that the acoustic resistance of the second structure is closer to the characteristic impedance of air in the current scenario, while the acoustic reactance is smaller, the maximum absorption coefficient is closer to 1.0, and the effective absorption frequency band is wider. Therefore, the second structure can be processed and the acoustic performance experimental tests can be carried out. For example, a layer of aluminum foil with a thickness of 0.06 mm is laminated on a perforated plate with large holes (i.e., the micro-perforated plate 10) with a thickness of 1.0 and a hole diameter of 1.2 mm. A micro-slit opening is formed by scratching with a wallpaper knife at the position of the aluminum foil corresponding to the large holes, and the slit width is about 0.1 mm. An experimental sample is processed by this method. Figure 13 is a schematic diagram of an experimental sample corresponding to an optional second structure according to an embodiment of the present invention Figure 1 , Figure 13 shows the experimental sample observed from one side of the micro-perforated film 20, Figure 14 is a schematic diagram of an experimental sample corresponding to an optional second structure according to an embodiment of the present invention Figure 2 , Figure 14 shows the experimental sample observed from one side of the micro-perforated plate 10.

[0087] Optionally, the transfer function method can be used in an impedance tube to test the acoustic impedance and absorption coefficient of the structure surface under normal incidence conditions. The impedance tube two-microphone method is used to carry out the impedance tube transfer function method test, and the test frequency range is 200 - 4000 Hz. The sample to be tested is processed into a disc slightly smaller than the tube diameter, and one or more layers of sealing films are coated around the disc according to the relative size of the sample and the tube diameter. The sample is installed in the tube, and an interference fit or a transition fit should not be used to avoid leakage of sound or vibration of the thin plate, which may lead to a decrease in test accuracy. A back cavity with a certain depth is provided at the rear of the sample. Although theoretically the depth of the back cavity has no effect on the acoustic impedance of the micro-perforated plate itself, in fact, the back cavity has a certain effect on both the acoustic resistance and acoustic reactance of the overall structure composed of the plate and the cavity, especially when the back cavity is relatively large or small. Therefore, during actual testing, it is advisable to adjust the depth of the back cavity to a reasonable range to reduce the influence of the acoustic impedance of the back cavity. The acoustic impedance reflected by the experimental test is that of the overall structure of the micro-perforated plate (plate + back cavity). Subtracting the acoustic reactance corresponding to the back cavity can obtain the acoustic impedance of the micro-perforated plate itself. The plane sound wave in the tube is generated by a random noise source (white noise). To avoid non-linearity during the test, the sound source intensity should not be set too large. The surrounding area should be kept quiet during the test to ensure that the signal-to-noise ratio is greater than 60 dB and reduce the influence of background noise interference.

[0088] Optionally, Figure 15 is a schematic diagram of the test results of an optional experimental sample according to an embodiment of the present invention. The absorption coefficient curve of the experimental test is as Figure 15 shown. In this experimental scenario, the maximum absorption coefficient reaches 0.97, the ratio of the upper and lower limits of the limited absorption frequency exceeds 4.2, exceeding 2 octave bands, and it has good sound absorption performance. Figure 15The model calculation values ​​and numerical simulation results are also plotted, such as Figure 15 As shown in the figure, the peak value of the sound absorption coefficient, the resonance frequency and the effective sound absorption bandwidth calculated by the model are basically consistent with the measured values. The small maximum sound absorption coefficient and narrow bandwidth in the experimental test are mainly caused by the error of manual processing. The actual processed micro-width is small and the perforation rate is small, resulting in the experimental sample The acoustic resistance and acoustic reactance are large, resulting in insufficient sound absorption performance.

[0089] It can be seen that the solution provided in the present application achieves the purpose of realizing the sound absorption effect based on the microporous film 20, thereby achieving the technical effect of improving the flexibility of use of the board mold composite sound absorption structure, and further solves the technical problem that the board mold composite sound absorption structure in the related art realizes the sound absorption effect based on the microporous plate 10, resulting in low flexibility of use of the board mold composite sound absorption structure.

[0090] Example 2

[0091] According to an embodiment of the present invention, an embodiment of a building wall of a substation is provided, and the building wall of the substation is provided with any one of the plate formwork composite sound absorption structures in Embodiment 1.

[0092] Optionally, the building surface may be a wall or a ceiling.

[0093] Optionally, a plurality of plate-membrane composite sound-absorbing structures may be arranged on the building wall surface. For example, the plurality of plate-membrane composite sound-absorbing structures may be arranged in a grid pattern on the building wall surface.

[0094] Optionally, the microporous film 20 in the plate-membrane composite sound absorbing structure is close to the sound source, and the back cavity is far away from the sound source. For example, the plate-membrane composite sound absorbing structure is arranged in the building wall in a manner that the microporous film 20 faces the indoor environment.

[0095] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0096] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0097] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A plate formwork composite sound absorbing structure, characterized in that: include: A microporous plate (10), wherein a plurality of first through holes (11) are provided on the microporous plate (10); A microporous film (20), wherein a plurality of second through holes (21) are provided on the microporous film (20), the microporous film (20) is attached to the microporous plate (10), the second through holes (21) are smaller than or equal to the first through holes (11), and the second through holes (21) and the first through holes (11) are interconnected.

2. The plate formwork composite sound absorbing structure according to claim 1, characterized in that: The number of the first through holes (11) and the number of the second through holes (21) are the same.

3. The plate formwork composite sound absorbing structure according to claim 1, characterized in that: The hole spacing of the first through holes (11) is the same as the hole spacing of the second through holes (21).

4. The plate formwork composite sound absorbing structure according to claim 1, characterized in that: The axis of the first through hole (11) is the same as the axis of the second through hole (21).

5. The plate formwork composite sound absorbing structure according to any one of claims 2 to 4, characterized in that: The first through holes (11) and the second through holes (21) are arranged in a square grid.

6. The plate formwork composite sound absorbing structure according to any one of claims 2 to 4, characterized in that: The second through hole (21) is a circular hole or a slit hole.

7. The plate formwork composite sound absorbing structure according to any one of claims 2 to 4, characterized in that: The thickness of the microporous plate (10) is greater than the thickness of the microporous film (20).

8. The plate formwork composite sound absorbing structure according to any one of claims 2 to 4, characterized in that: The microporous plate (10) is one of the following: an aluminum plate, an iron plate, a steel plate, a copper plate, or a wooden plate.

9. The plate formwork composite sound absorbing structure according to any one of claims 2 to 4, characterized in that: The microporous film (20) is aluminum foil.

10. A building wall of a substation, characterized in that: The building wall of the substation is provided with the plate formwork composite sound absorbing structure as described in any one of claims 1 to 9.

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