A device for efficiently absorbing the multiple harmonic noise of a power equipment

Abstract

The application discloses a device for efficiently absorbing multi-harmonic noise of radiation of power equipment, which is composed of one or more different sound absorption units arranged in space, and comprises a 100Hz sound absorption unit, wherein the 100Hz sound absorption unit comprises a first panel and a first labyrinth layer which are attached to each other, the first labyrinth layer comprises a first frame, the inside of the first frame is divided into a first spiral labyrinth channel by a first partition plate, and the first panel is provided with a first perforation in the middle. The sound pressure level at the entrance of the labyrinth channel and the sound pressure level at the end of the labyrinth channel have a large gradient, and since the vibration speed u of air particles is proportional to the gradient of sound pressure p, the vibration speed of air in the spiral labyrinth channel will sharply increase. Considering the thermal viscous loss of air near the channel wall surface, the strong air vibration will convert the sound energy localized in the spiral labyrinth channel into heat energy and be lost, so that quasi-perfect sound absorption is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of noise control, in particular to a device for efficiently absorbing multiple harmonic noise radiated by power equipment. BACKGROUND

[0002] With the rapid development of China's economy and society, the power load is growing, and the total number of transformers in different voltage level substations and power system terminal residential areas in the transformer distribution room reaches tens of millions. The noise level in the transformer distribution room is relatively high.

[0003] Studies have shown that the body noise of power equipment such as transformers mainly comes from magnetostriction and electrostriction noise, which shows obvious low-frequency harmonic characteristics. The sound energy at 2nd and 4th harmonic frequencies (100Hz and 200Hz) accounts for more than 90% of the total radiated sound energy. In order to reduce the noise in the transformer room of the indoor substation and the transformer distribution room in the residential area, sound absorption technology can be used to reduce indoor reflected sound, such as using porous sound absorption materials (such as glass wool, rock wool, etc.), resonance sound absorption structure (such as thin plate, thin film resonance sound absorption structure, etc.).

[0004] Porous sound absorption materials are suitable for absorbing medium and high frequency noise, and the sound absorption coefficient of low frequency sound is very low. The resonance sound absorption structure is suitable for absorbing medium and low frequency noise, and the sound absorption coefficient of 100Hz and 200Hz noise with lower frequency is still low.

[0005] In addition, the patent specification with publication number CN111785520A discloses a noise reduction device suitable for power capacitors, which reduces noise radiation noise by setting a fully enclosed damping shell and setting a sponge layer and a vacuum tube in the shell. The patent specification with publication number CN110767446A discloses a power filter capacitor noise reduction device and a noise reduction method, which includes a sound insulation cover installed on the top of the capacitor shell and a sound absorption cavity structure installed on the bottom of the capacitor shell. The sound absorption coefficient of 100Hz and 200Hz noise with lower frequency is still low in the above two schemes.

[0006] Therefore, it is necessary to develop a device for efficiently absorbing 100Hz and 200Hz low frequency noise in the transformer distribution room to reduce noise pollution in the transformer distribution room. SUMMARY

[0007] The purpose of the present application is to provide a device for efficiently absorbing multiple harmonic noise radiated by power equipment. The device can efficiently absorb low frequency noise radiated by power equipment, especially 100Hz and 200Hz noise with dominant sound energy.

[0008] The device is composed of one or more different sound absorption units arranged in space, and the device comprises a 100Hz sound absorption unit, the 100Hz sound absorption unit comprising a first panel and a first labyrinth layer in close contact; the first labyrinth layer comprises a first frame, the inside of the first frame is divided into a first spiral labyrinth channel by a first partition plate, and the first panel is provided with a first perforation.

[0009] Preferably, the thickness of the first labyrinth layer is 32mm±5mm; the diameter of the first perforation is 3mm±1mm; the turning angles of the first spiral labyrinth channel are all right angles, the center line length of the first spiral labyrinth channel is 680mm±50mm, and the width of the first spiral labyrinth channel is 13mm±3mm.

[0010] Preferably, the device further comprises a 200Hz sound absorption unit, the 200Hz sound absorption unit comprising a second panel and a second labyrinth layer in close contact; the second labyrinth layer comprises a second frame, the inside of the second frame is divided into a second spiral labyrinth channel by a second partition plate, and the second panel is provided with a second perforation;

[0011] The thickness of the second labyrinth layer is 20mm±4mm; the diameter of the second perforation is 3mm±1mm; the turning angles of the second spiral labyrinth channel are all right angles, the center line length of the second spiral labyrinth channel is 320mm±30mm, and the width of the second spiral labyrinth channel is 13mm±3mm.

[0012] Simulation results show that at 100Hz, the normalized surface acoustic impedance Im(Z s / Z0) of the 100Hz sound absorption unit tends to 0, and the normalized surface acoustic resistance Re(Z s / Z0) tends to 1, indicating that the acoustic impedance of the structure matches the acoustic impedance of the air, and most of the sound energy enters the inside of the structure. At the above-mentioned 100Hz frequency, the sound energy entering the inside of the 100Hz sound absorption unit will be gathered in the corresponding channel and produce FP resonance. At 200Hz, the normalized surface acoustic impedance Im(Z s / Z0) of the 200Hz sound absorption unit tends to 0, and the normalized surface acoustic resistance Re(Z s / Z0) tends to 1, indicating that the acoustic impedance of the structure matches the acoustic impedance of the air, and most of the sound energy enters the inside of the structure. At the above-mentioned 200Hz frequency, the sound energy entering the inside of the 200Hz sound absorption unit will be gathered in the corresponding channel and produce FP resonance.

[0013] To clarify the mechanism of structural FP resonance, the sound pressure level and air particle velocity distribution in the labyrinth channel at 100Hz and 200Hz are simulated. At the sound absorption peak of the 100Hz and 200Hz sound absorption units, the sound energy is localized in the channel, and there is a large gradient between the sound pressure level at the entrance of the labyrinth channel and the sound pressure level at the end of the channel. Since the vibration velocity u of the air particle is proportional to the gradient of the sound pressure p, that is, Therefore, the air vibration velocity in the channel will increase sharply. Considering the thermal viscous loss of air near the channel wall, the strong air vibration will convert the sound energy localized in the channel into heat energy and be lost, thereby realizing quasi-perfect sound absorption.

[0014] The structural parameters such as the height of the labyrinth layer and the width of the labyrinth channel affect the structural sound absorption performance by changing the balance of the loss factor and the leakage factor of the system, wherein the first labyrinth layer thickness of the 100Hz sound absorption unit is preferably 32mm±5mm, and the channel net width is preferably 13mm±3mm; the second labyrinth layer thickness of the 200Hz sound absorption unit is preferably 20mm±4mm, and the channel net width is preferably 13mm±3mm, which is close to the critical coupling state and has the best sound absorption performance.

[0015] As a preferred embodiment, adjacent 100Hz sound absorption units are paired, adjacent 200Hz sound absorption units are paired, or adjacent 100Hz sound absorption units and 200Hz sound absorption units are paired, and the paired sound absorption units are connected through a through hole on the frame at the end of the labyrinth channel. The maximum width of the cross section of the through hole is not more than 30% of the width of the labyrinth channel.

[0016] The through hole at the end of the labyrinth channel changes the acoustic impedance of the channel, and the maximum width of the cross section of the through hole is controlled to be less than 30% of the net width of the channel, so that most of the sound energy is reflected, and a small part of the sound energy can be transmitted into the labyrinth channel of the paired sound absorption unit. The transmitted sound enters the paired sound absorption unit through the through hole, which effectively extends the length of the channel, thereby improving the low-frequency sound absorption amount below 100Hz or 200Hz, while ensuring the sound absorption effect at 100Hz and 200Hz, and widening the sound absorption frequency band.

[0017] As a preferred embodiment, the device further comprises a Helmholtz resonance sound absorption unit, which comprises a first perforated plate and a cavity layer in close contact. The resonance frequency of the Helmholtz resonator is below 500Hz, thereby widening the sound absorption frequency band and improving the sound absorption coefficient.

[0018] As a preference, the device further comprises a resistive sound absorption unit, which comprises a second perforated plate and a porous sound absorption material layer. The porous sound absorption material layer absorbs sound energy by viscous resistance of air in the pores, friction between air and pore wall, etc., has good mid-high frequency sound absorption performance and a wide sound absorption frequency band, thereby improving the mid-high frequency sound absorption coefficient and widening the sound absorption frequency band.

[0019] As a preference, the resistive sound absorption unit is located in the same plane as the 100Hz sound absorption unit, the 200Hz sound absorption unit and the Helmholtz resonance sound absorption unit, or directly above the 100Hz sound absorption unit, the 200Hz sound absorption unit and the Helmholtz resonance sound absorption unit.

[0020] As a preference, the 100Hz sound absorption unit, the 200Hz sound absorption unit, the Helmholtz resonance sound absorption unit and the resistive sound absorption unit each comprise a bottom plate attached to the first labyrinth layer, the second labyrinth layer, the cavity layer and the porous sound absorption material layer, respectively.

[0021] As a preference, the 100Hz sound absorption unit, the 200Hz sound absorption unit, the Helmholtz resonance sound absorption unit and the resistive sound absorption unit each have a rectangular cross section.

[0022] Advantages of the present application:

[0023] The device designed by the present application is capable of efficiently absorbing multiple harmonic noise radiated by power equipment. The device integrates a 100Hz sound absorption unit, a 200Hz sound absorption unit, a Helmholtz resonance sound absorption unit and a resistive sound absorption unit in the sound absorption device, thereby ensuring efficient absorption (close to perfect sound absorption) of 100Hz or 200Hz and realizing wideband sound absorption. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a structural schematic diagram of an embodiment of the present application;

[0025] Figure 2 FIG. 2 is a structural schematic diagram of a first labyrinth layer of the embodiment 1 of the present application;

[0026] Figure 3 FIG. 3 is a side view of a 100Hz sound absorption unit of the present application;

[0027] Figure 4 FIG. 4 is a structural schematic diagram of the 100Hz sound absorption unit of the present application;

[0028] Figure 5 FIG. 5 is a structural schematic diagram of a first labyrinth layer of the 100Hz sound absorption unit of the present application;

[0029] Figure 6 FIG. 6 is a top view of the first labyrinth layer of the 100Hz sound absorption unit of the present application;

[0030] Figure 7 Fig. 7 is a schematic diagram of simulation results of the sound absorption coefficient of the 100Hz sound absorption unit of the present application;

[0031] Figure 8 Fig. 8 is a schematic diagram of the structure of the embodiment 2 of the present application;

[0032] Figure 9 Fig. 9 is a schematic diagram of the structure of the second labyrinth layer of the embodiment 2 of the present application;

[0033] Figure 10 Fig. 10 is a side view of the 200Hz sound absorption unit of the present application;

[0034] Figure 11 Fig. 11 is a schematic diagram of the structure of the 200Hz sound absorption unit of the present application;

[0035] Figure 12 Fig. 12 is a schematic diagram of the structure of the second labyrinth layer of the 200Hz sound absorption unit of the present application;

[0036] Figure 13 Fig. 13 is a top view of the second labyrinth layer of the 200Hz sound absorption unit of the present application;

[0037] Figure 14 Fig. 14 is a schematic diagram of simulation results of the sound absorption coefficient of the 200Hz sound absorption unit of the present application;

[0038] Figure 15 Fig. 15 is a schematic diagram of the structure of the embodiment 3 of the present application;

[0039] Figure 16 Fig. 16 is a schematic diagram of the structure of the embodiment 4 of the present application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0041] Embodiment 1

[0042] As shown in Figs. 1-3, a device for efficiently absorbing multiple harmonic noise radiated by power equipment, which is arranged by 16 100Hz sound absorption units 1. Figure 1 2 As shown in Figs. 4-6, a device for efficiently absorbing multiple harmonic noise radiated by power equipment, which is arranged by 16 200Hz sound absorption units 1.

[0043] As shown in Figs. 7-9, a device for efficiently absorbing multiple harmonic noise radiated by power equipment, which is arranged by 16 100Hz sound absorption units 1. Figures 3-6 ​As shown, the 100Hz sound-absorbing unit 1 has a sandwich panel structure, consisting of a first panel 11, a first labyrinth layer 12, and a first base plate 13 bonded together in sequence, wherein the first base plate 13 is optional. The 100Hz sound-absorbing unit 1 has a square cross-section; the thickness D1 of the first labyrinth layer 12 is 32mm ± 5mm; the first panel 11 faces the sound incident side and has a hole p1 in the middle, with a hole diameter of... The first maze layer 12 includes a first frame 121. The interior of the first frame 121 is divided by a first partition 122 to form a first spiral maze passage. All turns of the passage are right angles. The length of the center line of the passage is 680mm ± 50mm, and the net width of the passage r1 is 13mm ± 3mm.

[0044] Adjacent 100Hz sound-absorbing units are paired up. A through-hole S1 is provided between the corresponding frames at the ends of the labyrinthine channel of the paired sound-absorbing units. The maximum width of the cross-section of the through-hole S1 is less than 30% of the net width of the channel. This through-hole S1 causes a change in the acoustic impedance at the end of the channel. By controlling the maximum width of the through-hole S1 to be less than 30% of the net width of the channel, most of the sound energy is reflected, while a small portion is transmitted into the paired sound-absorbing unit. The transmitted sound enters the paired sound-absorbing unit through the through-hole, effectively extending the channel length and thus increasing the low-frequency sound absorption below 100Hz. While ensuring the sound absorption effect at 100Hz, it also broadens the sound absorption frequency band.

[0045] To verify the sound absorption performance of this sound-absorbing unit, COMSOL was used to perform simulation calculations on the 100Hz sound-absorbing unit 1. The calculation results are shown below. Figure 7 .Depend on Figure 7 It can be seen that the 100Hz sound absorption unit 1 has good sound absorption performance in the mid-low frequency range and has a high sound absorption coefficient near 100Hz, with a sound absorption coefficient greater than 0.95. It is evident that this sound absorption unit has a very good sound absorption effect at 100Hz.

[0046] Example 2

[0047] like Figure 8 and 9 As shown, a device for efficiently absorbing multiple harmonic noise radiated by power equipment is provided, which consists of 16 200Hz sound-absorbing units 2 arranged together.

[0048] like Figures 10-13 As shown, the 200Hz sound-absorbing unit 2 has a sandwich panel structure, consisting of a second panel 21, a second labyrinth layer 22, and a second base plate 23 sequentially bonded together, wherein the second base plate 23 is optional. The 200Hz sound-absorbing unit 2 has a square cross-section; the thickness D2 of the second labyrinth layer 12 is 20mm ± 4mm; the second panel 21 faces the sound incident side and has a hole p2 in the middle, with a hole diameter of... The first labyrinth layer 21 includes a first frame 211, and the inside of the first frame 211 is divided into a first spiral labyrinth channel by a first partition 212. The channel has a turning angle of 90 degrees, and a center line length of 320 mm±30 mm. A net width r1 of the channel is 13 mm±3 mm.

[0049] The adjacent 200 Hz sound absorption units 2 are paired, and a through hole S2 is arranged between the corresponding frames at the end of the paired sound absorption unit labyrinth channel. A maximum cross-sectional width of the through hole S2 is less than 30% of the net width of the channel. The through hole S2 causes the sound impedance at the end of the channel to change. By controlling the maximum cross-sectional width of the through hole S2 to be less than 30% of the net width of the channel, most of the sound energy is reflected, and a small part of the sound energy is transmitted into the paired sound absorption unit. The transmitted sound enters the paired sound absorption unit through the through hole, which equivalently extends the channel length, thereby improving the low-frequency sound absorption amount below 200 Hz, and widening the sound absorption frequency band while ensuring the 200 Hz sound absorption effect.

[0050] To verify the sound absorption performance of the sound absorption unit, COMSOL is used to simulate and calculate the 200 Hz sound absorption unit 2, and the calculation results are shown in Figure 14 . It can be seen from Figure 14 that the 200 Hz sound absorption unit 2 has good sound absorption performance in the medium and low frequency range, and has a high sound absorption coefficient near 200 Hz, which is greater than 0.95. It can be seen that the sound absorption unit has very good sound absorption effect at 200 Hz.

[0051] Example 3

[0052] As shown in Figure 15 , a device for efficiently absorbing multiple harmonic noise radiated by power equipment includes 18 100 Hz sound absorption units 1, 18 200 Hz sound absorption units 2, and 18 Helmholtz sound absorption units 3.

[0053] The 100 Hz sound absorption unit 1 and the 200 Hz sound absorption unit 2 are paired, and the transmitted sound enters the paired sound absorption unit through the through hole, which equivalently extends the channel length, thereby improving the low-frequency sound absorption amount, and widening the sound absorption frequency band while ensuring the 100 Hz and 200 Hz sound absorption effect.

[0054] The Helmholtz resonance sound absorption unit 3 is composed of a first perforated plate, a cavity layer and a bottom plate which are sequentially attached. The Helmholtz resonator has a resonance frequency below 500 Hz, thereby widening the sound absorption frequency band and improving the sound absorption coefficient.

[0055] Example 4

[0056] The embodiment is based on the embodiment 3, and a resistive sound absorption unit 4 is added. The resistive sound absorption unit 4 is a sandwich structure, which is composed of a second perforated plate, a porous sound absorption material layer and a bottom plate which are sequentially attached. The resistive sound absorption unit 4 is stacked on the 100Hz sound absorption unit 1, the 200Hz sound absorption unit 2 and the Helmholtz resonance sound absorption unit 3, so as to improve the sound absorption coefficient of the middle and high frequencies and widen the sound absorption frequency band.

[0057] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can make modifications to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An apparatus for efficiently absorbing the multiple harmonic noise of the radiation of a power device, characterized by, The device is arranged and combined in space by one or more different sound absorption units, and the device includes 100Hz sound absorption units and 200Hz sound absorption units, and Helmholtz resonance sound absorption units, the 100Hz sound absorption units include a first panel and a first labyrinth layer that are attached together; the first labyrinth layer includes a first frame, the inside of the first frame is separated by a first partition to form a first spiral labyrinth channel, and the first panel is provided with a first perforation in the middle; The thickness of the first labyrinth layer is 32mm±5mm; the diameter of the first perforation is 3mm±1mm; the turning angles of the first spiral labyrinth channel are all right angles, the center line length of the first spiral labyrinth channel is 680mm±50mm, the width of the first spiral labyrinth channel is 13mm±3mm, adjacent 100Hz sound absorption units are paired, and the two 100Hz sound absorption units that are paired are connected through a through hole on the frame at the end of the spiral labyrinth channel, and the maximum width of the cross section of the through hole is not more than 30% of the width of the spiral labyrinth channel; The 200Hz sound absorption units include a second panel and a second labyrinth layer that are attached together; the second labyrinth layer includes a second frame, the inside of the second frame is separated by a second partition to form a second spiral labyrinth channel, and the second panel is provided with a second perforation in the middle; The thickness of the second labyrinth layer is 20mm±4mm; the diameter of the second perforation is 3mm±1mm; the turning angles of the second spiral labyrinth channel are all right angles, the center line length of the second spiral labyrinth channel is 320mm±30mm, and the width of the second spiral labyrinth channel is 13mm±3mm; Adjacent 200Hz sound absorption units and 100Hz sound absorption units or adjacent 200Hz sound absorption units are paired, and the paired 200Hz sound absorption units and 100Hz sound absorption units or two 200Hz sound absorption units are connected through a through hole on the frame at the end of the spiral labyrinth channel, and the maximum width of the cross section of the through hole is not more than 30% of the width of the spiral labyrinth channel; The Helmholtz resonance sound absorption units include a first perforated panel and a cavity layer that are attached together.

2. The apparatus of claim 1, wherein, The device further includes a resistive sound absorption unit, and the resistive sound absorption unit includes a second perforated panel and a porous sound absorption material layer that are attached together.

3. The apparatus of claim 2, wherein, The resistive sound absorption unit is located in the same plane as the 100Hz sound absorption units, the 200Hz sound absorption units and the Helmholtz resonance sound absorption units, or is located directly above the 100Hz sound absorption units, the 200Hz sound absorption units and the Helmholtz resonance sound absorption units.

4. The apparatus of claim 2, wherein, The 100Hz sound absorption units, the 200Hz sound absorption units, the Helmholtz resonance sound absorption units and the resistive sound absorption units all include a bottom plate that is attached to the first labyrinth layer, the second labyrinth layer, the cavity layer and the porous sound absorption material layer respectively.

5. The apparatus of claim 2, wherein, The cross sections of the 100Hz sound absorption units, the 200Hz sound absorption units, the Helmholtz resonance sound absorption units and the resistive sound absorption units are all rectangular.

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