A sound-absorbing sheet

Abstract

The present invention relates to the technical field of muffler sheets, and in particular to a muffler sheet. The muffler sheet comprises: a muffler sheet shell, at least part of which is composed of a perforated plate; and a sound absorbing material, which is uniformly filled inside the muffler sheet shell; the muffler sheet shell is sequentially constructed into a leading edge plate, a middle panel and a tapered panel along the airflow direction S, wherein the middle panel and the tapered panel are respectively composed of two perforated plates with different perforation rates. The muffler sheet provided by the present invention can muffle different spectral parts of the noise source by using different perforation rates in the middle panel part and the tapered panel part, thereby achieving the best overall sound reduction under the same pressure loss conditions.

Description

Technical Field

[0001] The invention relates to the technical field of sound-absorbing sheets, and in particular to a sound-absorbing sheet. Background Art

[0002] Mufflers can block and weaken the propagation of sound waves and allow airflow to pass through, and are an effective tool for noise control. Resistive mufflers are widely used in air conditioning and ventilation systems in civil and industrial buildings to prevent the outward radiation and propagation of operating noise from equipment such as air conditioning units, fans, cooling towers, boilers and generators. The muffler performance of resistive mufflers mainly depends on factors such as the length, thickness, spacing, shape of the muffler channel, perforated plate characteristics and properties of the sound absorbing material.

[0003] By reducing the distance between the sheets or increasing the thickness of the silencer sheets, the amount of sound attenuation can be increased, but the flow resistance and aerodynamic regeneration noise will increase; by lengthening the length of the silencer, the amount of sound attenuation can be increased, but the cost will increase accordingly, and there will be no significant change in the low-frequency sound attenuation performance. In heavy industries such as thermal power generation, chemical industry, and metallurgy, the amount of silencers used in a single project is huge, and the long-term operation of the equipment is also sensitive to flow resistance. The flow resistance generated by the fluid inside the silencer will hinder the normal flow of the fluid, thereby affecting production efficiency. Therefore, there are high requirements for the silencer's sound attenuation characteristics and flow resistance characteristics. It is urgent to provide a wide-band silencer that is suitable for high-frequency, medium-frequency, and low-frequency silencers, and has low flow resistance characteristics. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art due to the lack of a silencer having both broadband sound elimination and low flow resistance characteristics, thereby providing a silencer sheet having both broadband sound elimination and low flow resistance characteristics.

[0005] In order to solve the above technical problems, the present invention provides a sound-absorbing sheet, comprising:

[0006] a sound-absorbing sheet housing at least partially formed of a perforated plate; and

[0007] Sound absorbing material, the sound absorbing material is evenly filled inside the shell of the sound-absorbing sheet;

[0008] The outer shell of the muffler sheet is sequentially constructed into a leading edge plate, a middle panel and a tapered panel along the airflow direction S, wherein the middle panel and the tapered panel are respectively composed of two perforated plates with different perforation rates.

[0009] Furthermore, the perforation rate of the middle panel is greater than the perforation rate of the tapered panel.

[0010] Furthermore, the cross-section of the tapered panel along the width direction is trapezoidal, conical or arc-shaped, and the small end of the trapezoid or the cone is located at the front end position in the airflow direction.

[0011] Furthermore, the cross-section of the leading edge plate along the width direction is semicircular, semi-elliptical or conical.

[0012] Furthermore, the cross-section of the middle panel along the width direction is rectangular or square.

[0013] Furthermore, the tapered angle of the tapered panel along the width direction is 1.5°≤α≤10°.

[0014] Furthermore, the tapered angle of the tapered panel along the width direction is α=3.5°.

[0015] Furthermore, the perforation rate of the middle panel is greater than 20%.

[0016] Furthermore, the perforation rate of the tapered panel is less than 0.5%.

[0017] The technical solution of the present invention has the following advantages:

[0018] 1. The sound-absorbing sheet provided by the present invention can absorb sound at different frequency spectrum parts of the noise source by adopting different perforation rates in the middle panel part and the tapered panel part, thereby achieving the best overall sound absorption under the same pressure loss conditions.

[0019] 2. The sound-absorbing sheet provided by the present invention is conducive to medium and high frequency sound absorption by using a perforated plate with a large perforation rate in the middle panel, which facilitates medium and high frequency sound waves to enter the internal sound-absorbing material through the perforated plate with a large perforation rate and be absorbed. By using a perforated plate with a small perforation rate in the tapered panel, it is conducive to low frequency sound absorption, which facilitates low frequency sound waves to enter the internal sound-absorbing material through the perforated plate with a small perforation rate and be absorbed.

[0020] 3. The silencer provided by the present invention has a tapered panel portion that is wide at first and narrow at the end, which can form a gradually expanding flow channel between the two silencer plates used in conjunction with each other, guide the airflows of the two adjacent flow channels to converge relatively smoothly, restore the kinetic energy to pressure energy to the greatest extent, and reduce flow losses. Therefore, the silencer provided by the present invention can achieve high-frequency, medium-frequency, and low-frequency silencers while ensuring low flow resistance.

[0021] 4. The muffler provided by the present invention has a leading edge plate portion that is narrow at first and then wide along the airflow direction S, which can smoothly separate the airflow and play a guiding role.

[0022] 5. The sound-absorbing sheet provided by the present invention has a parallel plate in the middle panel portion, which can form a straight flow path between two sound-absorbing sheets used in conjunction with each other, thereby ensuring smooth passage of airflow.

[0023] 6. The muffler plate provided by the present invention ensures that a gradually diverging flow channel is formed between two muffler plates used in conjunction with each other by adopting a smaller contraction angle, so that serious flow separation does not occur in the gradually diverging flow channel section, thereby reducing flow losses.

[0024] 7. The sound-absorbing sheet provided by the present invention has two perforation rates for the perforated plate of the sound-absorbing sheet. The perforation rate of the perforated plate of the middle panel part is greater than 20%. The cooperation of this perforated plate and the internal sound-absorbing material plays a major role in medium and high frequency sound absorption, which is beneficial for sound waves to enter the internal sound-absorbing material and achieve the purpose of high-frequency sound absorption; the rear tapered panel part of the sound-absorbing sheet adopts a perforated plate with a small perforation rate, and the perforation rate is less than 0.5%. The cooperation of this perforated plate and the internal sound-absorbing material plays a major role in low-frequency sound absorption, which is beneficial for sound waves to enter the internal sound-absorbing material and increase the low-frequency sound absorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is a schematic diagram of the structure of the outer shell of the muffler sheet of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the muffler sheet of the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of the muffler of the present invention;

[0029] Figure 4 It is a schematic diagram of the cross-sectional structure of the muffler of the present invention;

[0030] Figure 5 is a schematic diagram of the cross-sectional structure of a reference muffler;

[0031] Figure 6 It is the cumulative energy spectrum of the noise energy integrated with frequency after noise elimination.

[0032] Description of reference numerals:

[0033] 1-muffler outer shell, 2-muffler plate outer shell, 21-front edge plate, 22-middle panel, 23-tapered panel, 3-sound absorbing material. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] Embodiment 1

[0039] Combination Figure 1 , Figure 2 As shown, a sound-absorbing sheet comprises:

[0040] A sound-absorbing plate housing 2, which is at least partially formed of a perforated plate; and

[0041] Sound absorbing material 3, the sound absorbing material 3 is uniformly filled in the interior of the sound-absorbing sheet housing 2, and the sound absorbing material is made of loose porous material, such as slag wool, sponge, etc., which is not too limited in this embodiment;

[0042] The sound-absorbing sheet shell 2 is sequentially structured into a leading edge plate 21, a middle panel 22 and a tapered panel 23 along the airflow direction S, wherein the middle panel 22 and the tapered panel 23 are respectively composed of two perforated panels with different perforation rates, and specifically, the leading edge plate 21, the middle panel 22 and the tapered panel 23 are made of metal or hard plastic. At the same time, in order to achieve the sound wave entering the interior of the sound-absorbing sheet, the sound wave enters the sound-absorbing material 3 through the perforations of the perforated plate.

[0043] The sound-absorbing sheet provided by the present invention can absorb sound at different frequency spectrum parts of the noise source by adopting different perforation rates in the middle panel part and the tapered panel part, thereby achieving the best overall sound absorption under the same pressure loss condition.

[0044] By using the outer shell of the sound-absorbing sheet as the protective surface of the sound-absorbing material, the structural integrity of the sound-absorbing material is ensured and the structural strength is increased.

[0045] It should be noted that the perforation rate refers to the ratio of the sum of the perforation areas to the total area of ​​the plate.

[0046] Specifically, the perforation rate of the middle panel 22 is greater than the perforation rate of the tapered panel 23. By using a perforated plate with a large perforation rate in the middle panel 22, it is beneficial to medium and high frequency sound absorption, and it is convenient for medium and high frequency sound waves to enter the internal sound absorbing material through the perforated plate with a large perforation rate and be absorbed. By using a perforated plate with a small perforation rate in the tapered panel 23, it is beneficial to low frequency sound absorption, and it is convenient for low frequency sound waves to enter the internal sound absorbing material through the perforated plate with a small perforation rate and be absorbed.

[0047] Specifically, the muffler shell 2 is sequentially constructed into a leading edge plate 21, a middle panel 22 and a tapered panel 23 along the airflow direction S, wherein the first end of the leading edge plate 21 is the windward surface. Figure 1 As shown, the leading edge plate 21 extends from the first end to the second end and is constructed as a structure with gradually increasing thickness; the first end of the middle panel 22 is connected to the second end of the leading edge plate 21, and the middle panel 22 extends from the first end to the second end and is constructed as a square structure with uniform thickness; the first end of the tapered panel 23 is connected to the second end of the middle panel 22, and the thickness gradually decreases from the first end of the tapered panel 23 to the second end of the tapered panel 23.

[0048] Specifically, the cross-sectional form of the leading edge plate 21 along the width direction is semicircular, semi-elliptical or conical; the cross-sectional form of the middle panel 22 along the width direction is rectangular or square; the cross-sectional form of the tapered panel 23 along the width direction is trapezoidal, conical or arc-shaped, and the small end of the trapezoid or the cone is located at the front end position in the airflow flow direction.

[0049] The shell structure of the silencer plate of the present invention is that the front edge plate 21 is narrow at first and then wide along the airflow direction S, which can smoothly separate the airflow and play a guiding role; the middle panel 22 is a parallel plate, which can form a straight flow channel between the two silencers used in conjunction with each other, ensuring the smooth passage of the airflow; the rear tapered panel 23 is wide at first and then narrow, which can form a gradually expanding flow channel between the two silencers used in conjunction with each other, guiding the airflows of the two adjacent flow channels to converge relatively smoothly, restoring kinetic energy to pressure energy to the greatest extent, and reducing flow losses. This structural shape of the silencer plate can ensure that the overall flow resistance of the silencer composed of multiple silencer plates placed in parallel and having a straight flow channel and a gradually expanding flow channel is small, and has a low flow resistance characteristic; it can increase the thickness of the straight part of the silencer plate and increase the total volume of the silencer plate under the condition of ensuring that the flow resistance does not increase, thereby enhancing the silencer ability.

[0050] In this embodiment, the front edge plate 21 and the middle panel 22, and the middle panel 22 and the tapered panel 23 are fixedly connected. The specific fixing method is not limited. When plastic material is used, it can be connected by glue; when metal material is used, it can be connected by welding. At the same time, the surface of the front edge plate 21 facing the middle panel 22, and the surface of the middle panel 22 facing the tapered panel 23 can be a complete plane, or a part of it can be hollowed out.

[0051] Specifically, Figure 4 As shown, the tapered angle of the tapered panel 23 along the width direction is 1.5°≤α≤10°.

[0052] Specifically, the tapered angle α of the tapered panel 23 along the width direction is 3.5°.

[0053] By adopting a smaller contraction angle, a gradually expanding flow channel is ensured to be formed between the two silencer plates used in conjunction with each other, so that serious flow separation does not occur in the gradually expanding flow channel section, thereby reducing flow losses.

[0054] As a specific implementation form, the selection of the angle value of the tapered angle requires the flow parameter requirements to be optimized to ensure that the muffler pressure loss does not exceed the allowable value.

[0055] Specifically, the perforation rate of the middle panel 22 is greater than 20%.

[0056] Specifically, the perforation rate of the tapered panel 23 is less than 0.5%.

[0057] The perforated plate of the muffler sheet adopts two perforation rates. The perforation rate of the middle panel is greater than 20%. The combination of this perforated plate and the internal sound-absorbing material plays a major role in medium and high-frequency sound absorption, which is conducive to the sound waves entering the internal sound-absorbing material to achieve the purpose of high-frequency sound absorption;

[0058] The tapered panel at the rear of the silencer uses a perforated plate with a small perforation rate of less than 0.5%. The combination of this perforated plate and the internal sound-absorbing material plays a major role in low-frequency sound absorption, which is beneficial for sound waves to enter the internal sound-absorbing material and increase the low-frequency sound absorption effect.

[0059] In addition, the straight flow channel part between the two silencer plates used in conjunction with each other is relatively narrow, which is also beneficial to high-frequency silencer. The gradually expanding flow channel part is narrow at first and then wide, which is beneficial to medium and low frequency silencer, achieving the purpose of wide-band silencer.

[0060] As an improved implementation form, under specific working conditions, the length ratio of the two perforated plates can be adjusted according to the high-frequency and low-frequency noise energy ratios of the noise source to achieve the best overall noise reduction effect. If the high-frequency noise ratio of the noise source is large, the length of the perforated plate with a large perforation ratio is increased; if the low-frequency noise ratio of the noise source is large, the length of the perforated plate with a small perforation ratio is increased. If necessary, the perforated plate with a small perforation ratio of the tapered panel can be extended to the middle panel part.

[0061] As an improved implementation form, under specific working conditions, in addition to adjusting the length ratio of perforated plates with large and small perforation rates according to the ratio of high-frequency and low-frequency noise energy in the noise source, more than two perforation rate designs can be selected as needed to achieve the best broadband noise reduction effect.

[0062] Embodiment 2

[0063] Combination Figure 3 As shown, a plate-type muffler comprises at least one muffler plate as described above, and the plate-type muffler further comprises:

[0064] The muffler outer shell 1 is suitable for accommodating at least two muffler plates at intervals, and an air flow channel is formed between the two muffler plates.

[0065] As an improved implementation form, at least two of the sound-absorbing plates are placed parallel to each other.

[0066] As a further improved implementation, at least two of the muffler sheets are parallel to each other and arranged at equal intervals. Combined with the specific structural form of the muffler sheets, the muffler sheets are placed in parallel at equal intervals to construct a front flat flow channel and a rear gradually expanding flow channel of the muffler.

[0067] The middle panel 22 is a parallel plate, which can form a straight channel between the two silencer sheets used in conjunction with each other, ensuring smooth passage of airflow; the rear tapered panel 23 is first wide and then narrow, which can form a gradually expanding channel between the two silencer sheets used in conjunction with each other, guiding the airflows of the two adjacent channels to converge relatively smoothly, restoring kinetic energy to pressure energy to the greatest extent, and reducing flow losses. The structural shape of the silencer sheet can ensure that the overall flow resistance of the silencer with a straight channel and a gradually expanding channel composed of multiple silencer sheets placed in parallel is small, and has low flow resistance characteristics; it can increase the thickness of the straight part of the silencer sheet and increase the total volume of the silencer sheet under the condition of ensuring that the flow resistance does not increase, thereby enhancing the silencer capacity. In addition, the straight channel part between the two silencer sheets used in conjunction with each other is relatively narrow, which is also conducive to high-frequency silencer, and the gradually expanding channel part is first narrow and then wide, which is conducive to medium and low-frequency silencer, achieving the purpose of broadband silencer.

[0068] The pressure loss of the plate-type muffler provided by the present invention is mainly controlled by the channel size of the front flat channel. The larger the channel size, the smaller the pressure loss, and the smaller the channel size, the greater the pressure loss.

[0069] As an improved implementation form, the balance between acoustic performance and pressure loss can be achieved by fine-tuning the thickness of the middle panel 22 and the channel size of the flat channel according to specific engineering design requirements. If the sound-absorbing material of the middle panel 22 is thin, the pressure loss is low and the relative noise reduction is also reduced. On the contrary, if the sound-absorbing material of the middle panel 22 is thick, the pressure loss is large and the noise reduction is increased; by balancing the thickness of the middle panel 22 and the channel size of the flat channel, the best comprehensive product effect can be achieved.

[0070] Embodiment 3

[0071] In order to prove that the silencer sheet and the corresponding sheet silencer provided by the present invention have better silencer effect than the traditional silencer structure, a detailed description is given below through a control experiment.

[0072] For the convenience of description, the silencer sheet provided by the present invention is referred to as the silencer sheet, and the sheet-type silencer provided by the present invention is referred to as the silencer.

[0073] Combination Figure 5 As shown, as a comparison, a silencer without a tapered panel is used as a reference silencer, and the silencer corresponding to the reference silencer, which is a uniform channel along the airflow direction S and has a given pressure loss, is defined as the reference silencer. When designing this silencer, it is ensured that the thickness of the parallel part of this silencer is greater than the thickness of the reference silencer, and the total volume of this silencer is greater than the reference silencer, so as to ensure that the overall sound attenuation of this silencer is greater than that of the reference silencer. This silencer adopts a gradually expanding flow channel and a guide design of the leading edge plate of this silencer to ensure that the pressure loss of this silencer is less than that of the reference silencer under conditions such as the narrowing of the straight part.

[0074] The following combination Figure 4 , Figure 5 As shown, by comparing the performance of the present muffler with that of the reference muffler, the specific experimental effect of the present muffler is specifically explained from three aspects: flow resistance performance, broadband muffler performance, and low-frequency muffler performance.

[0075] The total length of the muffler is L, the length of the middle panel of the muffler is L1, the width is h, the length of the tapered panel is L2, the spacing between two adjacent muffler panels is b, and the tapered angle of the tapered panel along the width direction is α. The total length of the reference muffler is L, the spacing between two adjacent muffler panels is b', and the width of the middle panel is h'. L>0m, L1>0m, L2>0m, b>0m, α>0°, b'>0m, h'>0m.

[0076] The present muffler 1 and the present muffler 2 with different size parameters and the reference muffler, the design description of the muffler sheets of the three mufflers are listed in Table 1. The inside of the muffler is filled with the same resistive sound absorbing material, which is glass wool with a bulk density of 24-48kg / m3.

[0077] Table 1 Design description of muffler

[0078]

[0079] Through specific experiments, the comparison of the sound attenuation test results of the present muffler 1, the present muffler 2 and the reference muffler is shown in Table 2 below.

[0080] Table 2 Insertion loss test results of this muffler 1, this muffler 2 and reference muffler (dBA)

[0081]

[0082]

[0083] Note: The test wind speed of the reference silencer and this silencer 1 is 5.1m / s, and the test wind speed of this silencer 2 is 5m / s.

[0084] The flow resistance measurement results of the three types of mufflers are shown in Table 3 below.

[0085] Table 3 Pressure loss test results of muffler 1, muffler 2 and reference muffler

[0086] Wind speed (m / s) Reference Muffler This muffler 1 This muffler 2 5.1 35.9 24.6 36.5 6.6 62.1 45.6 59.7 8.1 93.8 67.3 91.2

[0087] Note: The test wind speeds of this muffler 2 are 5m / s, 6.5m / s and 8m / s respectively.

[0088] From Table 2 and Table 3, it can be seen that compared with the reference muffler, the flow resistance of the present muffler 1 is significantly reduced, with an average reduction of about 29%, and the noise reduction is slightly improved (2.23dB). Compared with the reference muffler, the noise reduction of the present muffler 2 is 6.78dB higher, and the flow resistance of the two mufflers is similar.

[0089] At the same time, the low-frequency silencing capabilities of the present muffler 1 and the present muffler 2 are significantly higher than those of the reference muffler. Figure 6 As shown, in order to more intuitively compare the effects of the three mufflers, Figure 6 The cumulative energy spectrum of noise energy after silencing is given, and the sound source is the cooling tower noise spectrum. Among them, A0 is the reference silencer, A1 is the present silencer 1, and A2 is the present silencer 2.

[0090] It can be seen that after the reference silencer, the 100-200Hz part of the noise energy curve increases very quickly, and the slope is large, indicating that the noise energy in this frequency band is still very large, and the low-frequency sound absorption capacity of the silencer is limited. Compared with the reference silencer, the slope of the present silencers 1 and 2 is significantly reduced relative to the reference silencer, indicating that the low-frequency sound absorption performance is much better. The sound absorption performance of traditional straight silencer sheets is mainly concentrated in the mid-frequency. Low-frequency noise has always been a difficult point in noise reduction. The sheet-type silencer provided by the present invention can solve the low-frequency noise problem well.

[0091] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A sound-absorbing sheet, characterized in that: include: A sound-absorbing plate housing (2) at least partially formed of a perforated plate; as well as A sound absorbing material (3), wherein the sound absorbing material (3) is uniformly filled inside the outer shell (2) of the sound-absorbing sheet; The outer shell (2) of the muffler sheet is sequentially constructed into a leading edge plate (21), a middle panel (22) and a tapered panel (23) along the airflow direction S, wherein the middle panel (22) and the tapered panel (23) are respectively composed of two perforated plates with different perforation rates; The cross-section of the leading edge plate (21) along the width direction is semicircular, semi-elliptical or conical, so that the leading edge plate (21) is narrow first and then wide along the airflow direction S; The cross-section of the tapered panel (23) along the width direction is a trapezoid, a cone or an arc, and the small end of the trapezoid or the cone is located at the front end of the airflow direction, so that the tapered panel (23) is first wide and then narrow, so that a gradually expanding flow channel can be formed between the two muffler sheets used in conjunction with each other; The perforation rate of the middle panel (22) is greater than the perforation rate of the tapered panel (23); the perforation rate of the middle panel (22) is greater than 20%; and the perforation rate of the tapered panel (23) is less than 0.5%.

2. The sound-absorbing sheet according to claim 1, characterized in that: The cross-section of the middle panel (22) along the width direction is rectangular or square.

3. The sound-absorbing sheet according to claim 1, characterized in that: The tapered angle of the tapered panel (23) along the width direction is 1.5°≤α≤10°.

4. The sound-absorbing sheet according to claim 1, characterized in that: The tapered angle α of the tapered panel (23) along the width direction is 3.5°.

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