Three-dimensional composite superstructure muffler module and muffler

Abstract

The application discloses a three-dimensional composite super-structure muffler module and a muffler. The muffler module comprises a rigid three-dimensional zigzag cavity structure and porous or fibrous material located around the cavity. The cavity structure is composed of a perforated panel, a multilayer coiled cavity and a partition. The coiled cavity is a multilayer structure, and each layer of the cavity is separated into a labyrinth-shaped channel by a coiled plug. The coiled porous or fibrous material around the cavity has high porosity. The application utilizes the high-frequency muffling characteristics of the porous or fibrous material and the low-frequency muffling characteristics of the super-structure material. The designed composite muffler has low-frequency and broadband muffling effects, can attenuate low-frequency single-frequency noise or broadband noise, and simultaneously greatly reduces the use of porous or fibrous material compared with a traditional resistive muffler. Furthermore, the muffler can be designed as an array-type muffler, and can be used in actual production and life, such as a substation, a mine site, a cooling tower and the like, which have a fan system and require large-area muffling and noise reduction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pipeline noise reduction, and particularly relates to a three-dimensional composite superstructure muffler. BACKGROUND

[0002] In the work of substations, cooling towers and tunnel construction, ventilation and heat dissipation are carried out by fan systems, and a large amount of noise is generated during the work of large equipment in production, and the fan also generates noise, mainly including rotating noise and vortex noise, which is brought out by the fan, damages people's hearing, affects the quality of life, and over a long period of time, may seriously affect people's physical and mental health.

[0003] In view of the problem of serious noise pollution of these large systems, a muffler is usually used at the end of the fan system to attenuate noise. Due to the characteristics of simple structure, easy processing and convenient installation, a passive muffler is mainly used, which has obvious economic efficiency. In the working conditions of substations, cooling towers and tunnel construction, which require large-area noise reduction, an array muffler can be used, and multiple muffler units are installed in the noise reduction pipeline through a truss to reduce noise. At present, the passive muffler mainly uses a resistive muffler, and the noise reduction unit mainly uses a flow guide cover, a surface layer and a porous foam or fiber resistive material, which has the characteristics of good high-frequency noise reduction effect, but it is difficult to eliminate low-frequency noise below 300 Hz. For people, low-frequency noise is often strong and harmful, and both the electromagnetic noise of the transformer in the substation and the rotating and vortex noise generated by the fan in the cooling tower and tunnel construction are mainly low-frequency noise. At present, the muffler mainly reduces high-frequency noise, and the problem of medium and low-frequency noise reduction and wide-frequency noise reduction has not been solved, so how to eliminate these low-frequency noises is a problem to be solved in practical engineering. SUMMARY

[0004] The application provides a three-dimensional composite superstructure muffler module and a muffler, which can attenuate low-frequency noise and realize multi-frequency wideband sound absorption.

[0005] To achieve the above object, the three-dimensional composite superstructure muffler module comprises a cavity structure and a sound absorption part outside the cavity, the cavity structure comprises a plurality of layers of coiled cavities connected in sequence, a first layer of spiral coiled cavity has a protruding section protruding outward, a perforated plate is arranged on the protruding section, and the remaining wall plates are all hard rigid wall surfaces; a plurality of through holes are formed in the perforated plate, each layer of spiral coiled cavity is divided into a spiral shape by a plug plate, and a partition plate is arranged in the last layer of spiral coiled cavity; the partition plates between adjacent spiral coiled cavities have central openings between odd layers and even layers, and have end openings between even layers and odd layers.

[0006] Further, the inside of the coiled cavity is spiral-shaped.

[0007] Further, the plugboard comprises a first arc-shaped plate, a connecting plate and a second arc-shaped plate connected in sequence, the connecting plate is rectangular, the cross sections of the first arc-shaped plate and the second arc-shaped plate are both circular arcs, and the two circular arcs are concentrically arranged, and the first arc-shaped plate is located inside the second arc-shaped plate.

[0008] Further, the sound absorption part is made of porous or fibrous material.

[0009] Further, the sound absorption part is coated with a protective layer.

[0010] Further, the through holes on the perforated plate are arranged in an array.

[0011] Further, the porosity of the perforated plate is 5% to 15%.

[0012] Further, the effective path of the cavity structure is 1 / 4 of the wavelength of the sound wave to be absorbed.

[0013] A three-dimensional composite superstructure sound absorber comprises a plurality of arrayed sound absorber units, and the sound absorber units comprise a plurality of the above-mentioned sound absorber modules.

[0014] Further, the sound absorber modules have different positions of the partition plates.

[0015] Compared with the prior art, the sound absorber has at least the following beneficial technical effects:

[0016] The application provides a three-dimensional composite superstructure sound absorber, which combines the high-frequency sound absorption characteristics of porous or fibrous material with the low-frequency sound absorption characteristics of a cavity superstructure material, and designs a composite sound absorber module with high and low frequency sound absorption performance.

[0017] Compared with general resistive sound absorbers, the sound absorber has excellent high-frequency sound absorption characteristics, low-frequency designability and modularization, and can be used as a sound absorption unit to form an arrayed sound absorber. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to facilitate the understanding of the technical solutions and embodiments of the present application, the following briefly describes the drawings required in the embodiments of the present application, which are used together with the specific embodiments below to explain the present application, and do not limit the present application.

[0019] Figure 1a is an axial section view of a three-dimensional curved space composite superstructure noise cancellation module provided by the present application;

[0020] Figure 1b is an axial perspective view of a three-dimensional curved space composite superstructure noise cancellation module provided by the present application;

[0021] Figure 2 is an axial section view of a second layer cavity of a superstructure composite noise cancellation module;

[0022] Figure 3a is an axial perspective view of a noise cancellation cavity structure in a superstructure composite noise cancellation module;

[0023] Figure 3b is an external shape schematic diagram of a noise cancellation cavity in a superstructure composite noise cancellation module;

[0024] Figure 4 is a schematic diagram of a sound wave propagation path in a superstructure noise cancellation cavity;

[0025] Figure 5 is a schematic diagram of a cavity-coated glass fiber wool;

[0026] Figure 6 is a combined superstructure composite noise cancellation unit calculation model;

[0027] Figure 7 is a transmission loss curve of a combined superstructure composite noise cancellation unit;

[0028] Wherein: 1: perforated plate; 2: labyrinth plugboard; 3: partition; 4: facing layer; 5: partition plate; 6: front panel; 7: glass fiber wool; 8: rear panel. DETAILED DESCRIPTION

[0029] In order to make the purpose and technical solutions of the present application clearer and easier to understand. The following further describes the present application in combination with the drawings and embodiments, and the specific embodiments described herein are only used to explain the present application, and do not limit the present application.

[0030] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more. In the description of the present application, it needs to be explained that, unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] The present application utilizes the quarter wavelength wave absorption principle and gives the specific structure, carries out the targeted attenuation to the low frequency noise, and adopts the new design idea of modular combination to realize the multi-frequency point wideband sound absorption.

[0032] The present application provides a kind of composite superstructure muffler module of three-dimensional tortuous space, comprising: rigid three-dimensional tortuous cavity structure and the porous or fibrous material located at the four around cavities.Cavity structure is combined by arc perforated plate, periodic multilayer spiral coiled cavity and tail partition plate.Cavity is multilayer structure, each layer is separated into spiral by coiled plug-in board;Four around coiled porous or fibrous material has high porosity, and the cavity is wrapped into circular or square and the like easy to assemble shape.

[0033] Reference Figure 1a And Figure 1bA composite superstructure muffler module of three-dimensional tortuous space, which is a composite structure with glass fiber cotton and three-dimensional tortuous space cavities embedded therein around the periphery, comprises a low-frequency muffler module and glass fiber cotton 7 surrounding the low-frequency muffler module, and the outer side of the glass fiber cotton is covered with a facing layer 4 for constraining and fixing the glass fiber cotton; the low-frequency muffler module comprises a perforated plate 1, an insert plate 2 for separating to form a cavity and expand the effective length of the sound wave path in the cavity, a baffle 3 for adjusting the effective length of the muffler to control the muffling frequency, a partition plate 5 with a through hole between layers, a front panel 6 outside the first layer, and a rear panel 8 outside the last layer.

[0034] The outer shape of the cavity is a protruding arc structure, and the arc wall surface of the protruding section is provided with a perforated plate 1, and the remaining wall plates are all hard rigid wall surfaces.

[0035] The cavity is internally provided with a tortuous cavity structure connected by multiple layers, an insert plate 2 is arranged inside to form an internal passage, increase the path length, and change the muffling frequency, and the layers are separated by a partition plate 5 with a through hole, and the sound wave is propagated between the layers through the through hole. A baffle 3 is arranged at the end to adjust the effective length of the muffler to control the muffling frequency. The partition plate 5 is circular, and the partition plate 5 between the first layer and the second layer is provided with a central opening, and the sound wave is propagated from the center between the layers. The partition plate 5 between the odd layer and the even layer should be provided with a central opening, and the sound wave is propagated from the central opening to the next layer; the partition plate between the even layer and the odd layer should be provided with an end opening, and the sound wave is propagated from the end opening to the next layer. Further, in order to facilitate industrial manufacturing, maintenance and overall structural consistency, the perforated plate 1 is an arc-shaped panel with a plurality of small through holes of a certain size and arrangement, the hole diameter is generally 1-3 mm, the plate thickness is 1-2 mm, and the porosity is generally 5%-15% to ensure the muffling capacity of the cavity.

[0036] Except for the transition of the first layer with the perforated plate 1, the sound propagation passage shape of each layer is consistent, and the sound wave is propagated from the periphery to the center in the odd layer and from the center to the periphery in the even layer.

[0037] Further, the insert plate 2 arranged inside the tortuous cavity has a thickness of 1-2 mm, which is convenient for industrial processing.

[0038] Further, the internal passage shape of the muffling cavity is a spiral shape.

[0039] Further, the effective length of the entire muffling unit cavity is calculated as follows:

[0040] Suppose that the cross-sectional area of the fluid in the pipe is S, and the length is L, the fluid in the pipe is driven by a piston at x=0, and the pipe is closed at x=L. If the opening is propagated by a plane wave, then the acoustic impedance Z(x) of any point in the pipe is:

[0041]

[0042] where p0 is air density, c0 is sound speed, e is natural logarithm, j is imaginary unit, and its value is P i and P r are the amplitude of incident and reflected sound pressure, and k is sound wave number.

[0043] Substitute x = 0 into the above equation, we get:

[0044]

[0045] Substitute x = L into the above equation, we get the acoustic impedance at this point:

[0046]

[0047] By Euler formula, the above equation can be written as:

[0048]

[0049] Substitute the expression of Z(L) and Z(0) together, eliminate P i , P r , we get the relationship between output acoustic impedance Z(L) and input acoustic impedance Z(0):

[0050]

[0051] For the closed end, its acoustic impedance tends to infinity, i.e. Z(L)→∞, then according to the above equation, we get:

[0052]

[0053] Acoustic impedance can be written as the sum of acoustic resistance and acoustic reactance:

[0054] Z = R + jX

[0055] where R and X are the real and imaginary parts of impedance, respectively. When the acoustic reactance is 0, the structure will resonate, for a pipe with one open end and one closed end, it is:

[0056]

[0057] When cotkL = 0, the reactance is 0, at this time resonance occurs, i.e.:

[0058] kL = (2n-1)π / 2 n = 1, 2, 3,...

[0059] Wave number k = 2π / λ, so the above equation can be written as:

[0060] L = (2n-1) / 4 n = 1, 2, 3,...

[0061] According to the above formula, when the tube length is 1 / 4 of the sound wave wavelength, the structure resonates, and the sound loss effect of the cavity is the best at this time.

[0062] Therefore, when the effective length of the designed three-dimensional tortuous cavity is 1 / 4 of the sound wave wavelength, it can effectively dissipate noise of this wavelength.

[0063] Furthermore, the silencing cavity is surrounded by porous or fibrous materials, such as fiberglass wool or melamine foam, so that the contact between the perforated plate 1 and the flow channel is not blocked while arranging porous or fibrous materials.

[0064] Furthermore, through the sound absorption design of the single-frequency silencing module, the present invention can combine multiple silencing modules to obtain a composite superstructure silencer, so as to achieve multi-frequency point and broadband noise control of pipelines.

[0065] Example 1

[0066] This invention provides an embodiment of a three-dimensional tortuous space hyperstructure composite silencer. Figure 1a and Figure 1b This is an isometric sectional view of an embodiment of the composite silencer unit containing a 190Hz single-frequency silencer module and glass fiber cotton in this invention.

[0067] See Figure 1a , Figure 1b and Figure 2 The silencer unit consists of a single-frequency silencing module and fiberglass wool 7. The silencing module comprises a perforated plate 1, an insert plate 2, a partition plate 3, a divider plate 5, a front panel 6, and a rear panel 8. The fiberglass wool is covered and constrained by a protective layer 4. The spiral-shaped, tortuous cavity formed by these structures attenuates low-frequency single-frequency noise. The insert plate 2 is spiral-shaped, comprising a first arc-shaped plate, a connecting plate, and a second arc-shaped plate connected in sequence. The connecting plate is rectangular. The cross-sections of both the first and second arc-shaped plates are circular arcs, and the two arcs are concentrically arranged. The first arc-shaped plate is located inside the second arc-shaped plate, with a central angle of 270° for the first arc-shaped plate and 315° for the second arc-shaped plate.

[0068] The 190Hz silencing module can be considered as consisting of two interconnected tortuous cavities. The first layer has a perforated plate and its volume is larger than the tortuous cavity of the second layer. The shape of the labyrinthine cavity in the second layer is consistent with that of the first layer. The layers are connected by partitions 5 with circular through holes. In the first layer, sound waves propagate from the periphery to the center through the partition with the circular through holes, and then enter the next layer through the central opening. In the second layer, sound waves propagate from the center outwards. Third, fourth, and subsequent layers can be added as needed to further reduce the silencing frequency. Figure 2The position of the square baffle 3 at the end of the last layer can change the effective length of the sound absorption cavity, thereby adjusting the sound absorption frequency. For a 190 Hz sound absorption cavity with such a two-layer structure, the axial view of the entire sound absorption cavity is shown in Figure 3a The sound propagation path is shown in Figure 4 .

[0069] In addition to the perforated plate 1, the above-mentioned 190 Hz sound absorption module is wrapped with glass fiber cotton 7 around the periphery to form an impedance composite sound absorption module. In the finite element calculation of this embodiment, the wall thickness is ignored, and the first layer of the sound absorber module has a cross-sectional size of a 6 cm diameter circular spiral cavity and a quarter circular ring with a large diameter of 10 cm and a small diameter of 6 cm. The quarter circular ring is a transition section of the perforated plate 1 and the cavity, and the cross-sectional size of each subsequent layer is a 6 cm diameter circular spiral cavity, and the thickness of each layer is 2 cm. The inner part of the baffle is shaped as shown in FIG. 1, Figure 2 The perforated plate 1 is a quarter arc plate with a diameter of 10 cm, an area of π×10 cm×2 cm×1 / 4, a perforation rate of 10%, a hole diameter of 2 mm, and a plate thickness of 2 mm.

[0070] The sound absorption cavity shown in Figure 3b is wrapped with sound absorption glass fiber cotton around the perforated plate, forming a composite metamaterial sound absorber with a cross-sectional size of 10 cm in diameter without additional structural length. The composite metamaterial sound absorption module is shown in FIG. 1, and the wrapped glass fiber cotton is arranged as shown in Figure 5 The composite sound absorption and sound absorption cavity only contacts the flow passage with the perforated plate 1, greatly retaining the contact area of the glass fiber cotton with the flow passage, so that the sound absorption performance of the glass fiber cotton is largely retained. In order to obtain a wide frequency sound absorption effect, the position of the baffle of the metamaterial composite sound absorption module is adjusted, a total of 6 different baffle positions, the first sound absorption module without a baffle, the second sound absorption module with a baffle 45° from the end of the cavity, the third sound absorption module with a baffle 90° from the end of the cavity, and so on, each time moving away from the end of the cavity by 45°, and the sixth sound absorption module with a baffle 225° from the end of the cavity. The above-mentioned 6 sound absorption modules are a group, and 3 of each group are arranged in series in a 14 cm×14 cm pipeline to form a whole sound absorber unit. The transmission loss curve is obtained by numerical calculation using finite element software. The transmission loss is defined as the ratio of the inlet sound pressure to the outlet sound pressure, and the unit is dB. The greater the transmission loss, the better the sound absorption performance of the sound absorber.

[0071] The calculation model is shown in Figure 6 The sound wave enters from the incident end, passes through the sound absorber unit, and then enters the perfect matched layer from the outlet. The perfect matched layer is used to simulate the perfect sound absorption at the end of the sound absorption. By calculation, the transmission loss curve is compared with that of a resistive sound absorber of the same size, and the results are shown in Figure 7As shown, it can be seen that the silencer unit shows multiple strong silencing characteristics in the low frequency range of 190Hz-230Hz, the highest silencing peak is more than 50dB, the lowest is 20dB, the silencing frequency band is basically consistent with the design, and multiple high-order silencing peaks still exist in the subsequent frequency. The silencer unit is within 2000Hz, due to the reduction of the use of glass fiber cotton and the increase of the super-structure silencing module, the silencing effect of the low frequency single frequency is improved, and the transmission loss of other frequencies is correspondingly reduced; after 2000Hz, due to the existence of multiple high-order silencing peaks, the silencing amount of the super-structure composite silencer unit is higher than that of the resistive silencer with more glass wool content. As can be seen from the silencing curve, the three-dimensional zigzag space can effectively silencing the low frequency single frequency noise, the multiple single frequency silencing modules can silencing the wide frequency, and in the case of reducing the volume of glass fiber cotton, due to the existence of high-order resonance, the silencing effect at high frequency can be better than that of the same size resistive silencer.

[0072] Moreover, the silencer unit can be designed as an array silencer as a silencing unit, which can be designed for large size, multiple noise points or wideband noise silencing, and has good market prospects.

[0073] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application, any equivalent transformation or direct or indirect application in related technical fields by using the content of the present application specification and drawings are also included in the patent protection scope of the present application.

Claims

1. A three-dimensional composite metamorphic silencer module, characterized in that, It includes a cavity structure and a sound-absorbing part located outside the cavity. The cavity structure includes multiple spiral cavities connected in sequence. The first spiral spiral cavity has an outwardly protruding protrusion section. A perforated plate (1) is arranged on the protrusion section. The remaining wall panels are all rigid walls. Several through holes are opened on the perforated plate. Each spiral spiral cavity is divided into a spiral shape by an insert plate (2). A partition plate (3) is provided in the last spiral spiral cavity. There is a partition plate (5) between adjacent spiral spiral cavities. The partition plate (5) between odd-numbered layers and even-numbered layers has an opening in the center. The partition plate (5) between even-numbered layers and odd-numbered layers has an opening at the end.

2. The three-dimensional composite metamorphic silencer module according to claim 1, characterized in that, The interior of the coiled cavity is spiral-shaped.

3. A three-dimensional composite metamorphic silencer module according to claim 1 or 2, characterized in that, The insert plate (2) includes a first arc plate, a connecting plate and a second arc plate connected in sequence. The connecting plate is rectangular. The cross-sections of the first arc plate and the second arc plate are both circular arcs, and the two circular arcs are concentrically arranged. The first arc plate is located inside the second arc plate.

4. The three-dimensional composite metamorphic silencer module according to claim 1, characterized in that, The sound-absorbing part is made of porous or fibrous material.

5. A three-dimensional composite metamorphic silencer module according to claim 1 or 4, characterized in that, The sound-absorbing part is covered with a protective layer (4).

6. A three-dimensional composite metamorphic silencer module according to claim 1, characterized in that, The perforated plate (1) is arranged with an array of through holes.

7. A three-dimensional composite metamorphic silencer module according to claim 1, characterized in that, The porosity of the perforated plate (1) is 5% to 15%.

8. A three-dimensional composite metamorphic silencer module according to claim 1, characterized in that, The effective path of the cavity structure is 1 / 4 of the wavelength of the sound wave to be silenced.

9. A three-dimensional composite metamorphic silencer, characterized in that, It includes multiple muffler units arranged in an array, each muffler unit comprising several muffler modules as described in claim 1.

10. A three-dimensional composite metamorphic silencer according to claim 9, characterized in that, The positions of the partition plates in the muffler modules are different.

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