CN210663282U - Air return device - Google Patents
Air return device Download PDFInfo
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- CN210663282U CN210663282U CN201921791021.4U CN201921791021U CN210663282U CN 210663282 U CN210663282 U CN 210663282U CN 201921791021 U CN201921791021 U CN 201921791021U CN 210663282 U CN210663282 U CN 210663282U
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- passageway
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Abstract
The utility model relates to a send wind device back to, including air intake, noise elimination passageway, return air inlet and air outlet, the air intake with the air outlet sets up respectively the both ends of noise elimination passageway, the middle part of noise elimination passageway is the rectangle structure, the return air inlet sets up on the lateral wall of noise elimination passageway, wherein, all set up the noise elimination subassembly on the lateral wall in the noise elimination passageway, the noise elimination subassembly includes noise elimination material and noise elimination orifice plate, noise elimination material passes through the noise elimination orifice plate is fixed on the inner wall of noise elimination passageway, evenly set up a plurality of perforation on the noise elimination orifice plate, the fenestrate aperture is 3.0 mm. In order to improve the medium-high frequency noise elimination volume, the utility model discloses a design of the resistive noise elimination structure of annular runner can also reduce the loss of air pressure.
Description
Technical Field
The utility model belongs to the technical field of send back the wind, concretely relates to send back wind device.
Background
The original feeding back device is made of metal, heat insulation materials are coated outside the feeding back device, the defects are that the appearance is not attractive, the weight is large, condensation exists, noise is large, air supply is uneven, and the feeding back device is made of nonmetal at present, the inner layer has a sound absorption function, and the nonmetal has a shock absorption function and a condensation prevention function. The non-metal is one sixth of stainless steel in density and therefore is very light. The non-metal outer layer does not need to be coated with a heat-insulating material, and is very attractive after being baked with paint. The air outlet is provided with a top grille air supply device, a spherical air supply device and a personal positioning air supply device, and air is uniformly supplied without condensation. With the development of noise control technology, air dielectric muffler technology is becoming mature. According to the investigation situation, the silencer of the ventilation air-conditioning system has the characteristics of limited installation space, and the noise energy of each fan is mainly concentrated in a medium-high frequency range and a wide frequency band. In practical use, the novel ventilation air supply/return device adopts a resistive silencing structure and an impedance conforming structure. When noise sound waves pass through the pipe section of the resistive noise elimination structure lined with the porous sound absorption material, the sound waves excite air molecules in countless pores in the porous material to vibrate, and a part of sound energy is used for overcoming friction resistance and viscous force and is converted into heat energy, so that the purpose of eliminating noise is achieved. Generally speaking, the resistive noise elimination structure has good medium-high frequency noise elimination performance, and the low-frequency noise elimination performance is poor. Through introducing the perforated pipe, and choose for use lower perforation rate, make resistive noise elimination structure possess wide band noise elimination ability. Considering the indoor specificity, the selected sound absorption material has the characteristics of moisture resistance, flame retardance, aging resistance, no pollution, no harmful gas release and the like. The air return device is provided with a filter device which can be replaced regularly. In the noise reduction design of civil buildings (the wind speed is less than 10 m/s), damp-proof superfine glass wool products are usually adopted, wind erosion can be generated under the action of high-speed ventilation air flow (the wind speed of an outlet pipeline of an air conditioner fan is about 22m/s), the glass wool can become fragments which are blown into a cabin and can be itch when being stuck on the skin, a suction air pipe can cough people, even lung suction diseases are caused, and the damp-proof superfine glass wool products are not easy to select.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem, the utility model provides a send wind device back to, including air intake, noise elimination passageway, return air inlet and air outlet, the air intake with the air outlet sets up respectively the both ends of noise elimination passageway, the middle part of noise elimination passageway is the rectangle structure, and the casing of this rectangle structure is made by XL7408 type inorganic fiber composite material, the return air inlet sets up on the lateral wall of noise elimination passageway, wherein, all set up the noise elimination subassembly on the lateral wall in the noise elimination passageway, the noise elimination subassembly includes noise elimination material and noise elimination orifice plate, the noise elimination material passes through the noise elimination orifice plate is fixed on the inner wall of noise elimination passageway, evenly set up a plurality of perforation on the noise elimination orifice plate, fenestrate aperture is 3.0 mm.
In any of the above schemes, preferably, the air inlet and the air outlet are both provided with flange structures, and the size of the flange structures is set according to CB/T64-2007.
In any of the above schemes, preferably, the flange structure is uniformly provided with a plurality of connecting holes.
In any of the above schemes, preferably, the air return opening is provided with a spherical air return opening.
In any of the above aspects, preferably, the sound-deadening material is flame-retardant hemp velvet.
The utility model has the advantages that: in order to meet the installation requirement, the size of the flange selected by the utility model is set according to CB/T64-2007, and the specification of the interface form of the utility model in the technical requirement is met; the XL7408 type inorganic fiber composite material is selected as the middle material of the utility model, so that the anti-corrosion performance can be improved, the weight is reduced, the appearance design is simple and beautiful, and the material is fashionable; in order to improve the medium-high frequency noise elimination volume, the utility model discloses a design of the resistive noise elimination structure of annular runner can also reduce the loss of air pressure.
Drawings
Fig. 1 is a schematic view of a preferred embodiment of a return air device according to the present invention;
fig. 2 is a top view of the embodiment of fig. 1 of a return air device according to the present invention;
fig. 3 is a left side view of the embodiment of fig. 1 of a return air device according to the present invention;
fig. 4 is a schematic view of the perforated structure of the embodiment of fig. 1 of the air return device according to the present invention.
The figures are labeled as follows: 1-an air inlet; 2-flange structure; 3-a shell; 4-a sound-deadening material; 5-silencing orifice plate; 6-spherical air supply outlet; 7-air outlet; 8-connecting holes; 9-perforation.
Detailed Description
In order to further understand the present invention, the present invention will be described in detail with reference to the following embodiments.
As shown in fig. 1 to 4, the utility model provides a return air device, which comprises an air inlet 1, a noise elimination channel, a return air inlet and an air outlet 7, wherein the air inlet 1 and the air outlet 7 are respectively arranged at two ends of the noise elimination channel, the air inlet 1 and the air outlet 7 are both provided with flange structures 2, the size of the flange structures is set according to CB/T64-2007, the specification of the interface form of the utility model in the technical requirements is satisfied, a plurality of connecting holes 8 are evenly arranged on the flange structure 1, the utility model can be fixed through the connecting holes 8, the middle part of the noise elimination channel is a rectangular structure, the shell of the rectangular structure is made of XL7408 type inorganic fiber composite material, the return air inlet is arranged on the side wall of the noise elimination channel, the return air inlet is a spherical return air inlet 6, wherein, the side wall in the noise elimination channel is provided with noise elimination components, the noise elimination assembly comprises a noise elimination material 4 and a noise elimination pore plate 5, the noise elimination material 4 is fixed on the inner wall of the noise elimination channel through the noise elimination pore plate 5, a plurality of through holes 9 are uniformly formed in the noise elimination pore plate 5, the hole diameter of each through hole 9 is 3.0mm, and the noise elimination material 4 is made of flame-retardant hemp velvet.
Performance testing
The silencer of the ventilation pipeline is of a resistance type and impedance composite structure, and due to the fact that the frequency range needing to be calculated is wide, the three-dimensional numerical calculation method is used in the project. In view of the fact that the acoustic finite element method is mature and is suitable for calculating the acoustic performance of the silencer, the acoustic performance of the designed silencer is calculated by using the three-dimensional finite element method. The basic theory of the acoustic finite element method is presented below.
Considering the existence of two media of air and sound absorption material in the impedance composite muffler, the muffler is formed byThe internal acoustic domain is divided into two regions: omegaaAnd ΩbDividing the boundary into an inlet, an outlet, a rigid wall and a perforated wall, respectively expressed by Si、So、SwAnd SpTo indicate. The three-dimensional sound wave propagation control equation in each region is a Helmholtz equation, namely:
in the region omegaaInternal:
in the region omegabInternal:
wherein: p is a radical ofaAnd pb，kaAnd kbSound pressure and wave number in air and sound absorbing material, respectively.
In the acoustic finite element method, an interpolation function is selected to represent the sound pressure, i.e.:
pa＝{N}T{pa} (3)
pb＝{N}T{pb} (4)
wherein { paAnd { p }bAre respectively regions omegaaAnd ΩbThe node sound pressure column vector, { N } is the shape function column vector.
In the region omegaaIn the interior, by using Galerkin's weighted residue method,
from the green formula one can see:
also in the region omegabAnd in addition, the method can be obtained by utilizing a Galerkin weighted residue method:
the boundary conditions of the muffler can be classified into four types as follows:
(1) the rigid wall surface, i.e. the normal mass point, has a zero vibration velocity and thus
(2) Normal particle velocity is continuous and the normal pressure gradient is proportional to the density ratio at the air-sound absorber interface due to the presence of the perforation means (tube or plate), i.e. the
ua·na＝-ub·nb(9)
Wherein: u. ofaAnd ubThe particle vibration velocity, rho, in air and sound-absorbing material, respectivelyaAnd ρbDensity of air and sound-absorbing material, naAnd nbThe unit external normal directions of the air side and the sound absorption material side on the wall surface of the perforation respectively.
Both sides of the wall surface of the perforation (S)p1And Sp2) Acoustic pressure difference and normal particle vibration velocity unThe relationship between them can be related by the characteristic acoustic impedance of the perforations, i.e.
Wherein ξpAcoustic impedance, p, characteristic of perforationsp1And pp2The sound pressure on the air side and the sound absorbing material side at the perforated wall surface, respectively. The formula (11) is suitable for use with a uniform pore distribution, particularly for thin-walled structures with high perforation rates. If the perforation rate is low (i.e., only a few holes), the geometry of the real holes can be modeled directly using finite elements, rather than using equation (11). However, when the perforation rate is high (i.e., the number of holes is large), it is necessary to design a pattern if finite elements are directly used to simulate the geometry of each holeWhile taking a lot of data preparation time and computation time, sometimes even impractical, the use of perforation impedance does not require modeling the geometry of each hole, thus greatly increasing the computational efficiency.
From the momentum equation:
(3) if the inlet boundary condition is that the particle velocity is known and the vibration velocity of the particle is not controlled to be 1, then
(4) The exit is set to a non-reflective boundary condition, then
The boundary conditions (8), (12), (14) and (15) are substituted into the formula (6) to obtain the following formula:
the boundary conditions (8) and (13) are substituted into the formula (7) to obtain the final product:
adding the two expressions (16) and (17) to obtain:
the two formulas (3) and (4) are substituted into the formula (18) to obtain the final product:
wherein:
and solving the equation (19) to obtain the sound pressure at each node, and further calculating the insertion loss of the silencer.
The muffler uses flame-retardant hemp velvet as a sound absorption material, and the acoustic characteristic of the muffler can use complex impedance zbAnd complex wave number kbAnd the complex impedance and complex wave number are experimentally measured. The expression of the characteristic impedance and wave number of the sound absorption material obtained by experimental measurement is
In the formula zaIs the characteristic impedance of air, kaThe wave number in air.
Considering that one side of the perforated pipe is air and the other side is sound absorbing material, the perforation characteristic acoustic impedance is expressed as:
ξp＝{0.006+jka[t+0.375dh(1+zbkb/zaka)]}/φ (30)
where dh is the pore diameter and φ is the puncture rate.
To calculate the insertion loss of the muffler, it is first necessary to obtain the exhaust noise spectrum before the muffler is not mounted. Table 1 shows the 1/3 octave sound pressure level of the fan noise, and the insertion loss of the muffler can be calculated by inputting this data and the 1/3 octave insertion loss calculation result into the attached table B.
TABLE 1 Sound pressure level for 1/3 octaves of Fan noise
| Frequency, Hz | 100 | 125 | 160 | 200 | 250 | 315 | 400 |
| Sound pressure level, dB | 54.5 | 57 | 58.5 | 57.5 | 54.5 | 53.5 | 58.5 |
| Frequency, Hz | 500 | 630 | 800 | 1000 | 1250 | 1600 | 2000 |
Table 2 shows the calculation result of 1/3 octave insertion loss in this embodiment, where the insertion loss of the blower is 9.9dB (A) in the frequency range of 20-10kHz, and meets the performance index requirement that the insertion loss is not less than 5dB (A).
Table 2 insertion loss calculation results of the present embodiment
| Frequency, Hz | 100 | 125 | 160 | 200 | 250 | 315 | 400 |
| Insertion loss | 2.8 | 3.7 | 4.8 | 5.5 | 6.1 | 6.7 | 7.5 |
| Frequency, Hz | 500 | 630 | 800 | 1000 | 1250 | 1600 | 2000 |
| Insertion loss | 8.7 | 10.0 | 11.2 | 13.0 | 14.0 | 14.0 | 13.0 |
| Frequency, Hz | 2500 | 3150 | 4000 | 5000 | 6300 | 8000 | 10000 |
| Insertion loss | 12.0 | 8.2 | 7.8 | 7 | 6 | 5 | 4 |
The sound absorption coefficient comparison of the fibrilia and the glass wool fiber is shown in the table, and the table shows that the sound absorption coefficient of the fibrilia and the glass wool fiber is equivalent. By taking the past design and use experience as reference, flame-retardant hemp velvet is supposed to be adopted as a sound absorption material, and the material is already used for a silencer of a ventilation main pipe.
TABLE 350 mm thick comparison of average sound absorption coefficient of hemp fiber and glass wool fiber
In the design of the resistive noise elimination structure, the low-frequency noise elimination performance can be improved by properly increasing the thickness and the density of the sound absorption material and selecting a lower perforation rate.
The introduction of the perforated pipe enables the peak frequency of the resistive noise elimination structure to move towards the low-frequency direction, so that the low-frequency noise elimination performance is improved, but the medium-high frequency noise elimination performance is reduced. In order to obtain a good medium-high frequency noise elimination effect, the perforation rate should be increased, the peak value of the insertion loss curve of the noise elimination structure does not change obviously along with the increase of the perforation rate, and the insertion loss curve moves towards the high frequency direction. When the perforation rate is higher than 27%, the further increase in the perforation rate has little effect on the acoustic performance of the sound-deadening structure.
Comprehensive analysis, in order to improve the high-frequency noise elimination amount in the noise elimination structure and simultaneously give consideration to the low-frequency noise elimination performance, the perforation rate of the perforated pipe of the low-noise air pipeline accessory is designed to be about 30%, and the perforation aperture is designed to be 3.0 mm.
It will be understood by those skilled in the art that any combination of the above-described embodiments and embodiments of the present invention and the various parts shown in the drawings is not intended to limit the scope of the invention and the description to simplify the present disclosure. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The utility model provides a send wind device back to, includes air intake, noise elimination passageway, return air inlet and air outlet, the air intake with the air outlet sets up respectively the both ends of noise elimination passageway, the middle part of noise elimination passageway is the rectangle structure, the return air inlet sets up on the lateral wall of noise elimination passageway, its characterized in that, all set up the noise elimination subassembly on the lateral wall in the noise elimination passageway, the noise elimination subassembly includes noise elimination material and noise elimination orifice plate, the noise elimination material passes through the noise elimination orifice plate is fixed on the inner wall of noise elimination passageway, evenly set up a plurality of perforation on the noise elimination orifice plate, the fenestrate aperture of perforation is 3.0 mm.
2. The return air device as claimed in claim 1, wherein the air inlet and the air outlet are each provided with a flange structure.
3. A return air device as claimed in claim 2, wherein the flange is provided with a plurality of attachment holes arranged uniformly in the structure.
4. The return air device as claimed in claim 1, wherein a spherical return air inlet is provided at the return air inlet.
5. The return air system of claim 1, wherein the sound dampening material is fire retardant hemp.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921791021.4U CN210663282U (en) | 2019-10-23 | 2019-10-23 | Air return device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921791021.4U CN210663282U (en) | 2019-10-23 | 2019-10-23 | Air return device |
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| CN210663282U true CN210663282U (en) | 2020-06-02 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113899066A (en) * | 2021-11-03 | 2022-01-07 | 汉尔姆建筑科技有限公司 | Air duct structure for sound insulation and noise reduction |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113899066A (en) * | 2021-11-03 | 2022-01-07 | 汉尔姆建筑科技有限公司 | Air duct structure for sound insulation and noise reduction |
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