RU2599214C1 - Plate-type noise suppressor with unified plates - Google Patents

Abstract

FIELD: manufacturing technology.

SUBSTANCE: invention relates to noise suppression. Silencer comprises a housing of rectangular section, rigidly connected with end inlet and outlet pipes, sound-absorbing plates made of a frame comprising perforated sheets, filled with sound absorber, positioned inside housing with certain spacing and forming therein flat channels, between sound absorber and perforated sheets there is an acoustically transparent material. Sound absorber is made of mineral wool on basalt base of “Rockwool” type, or “URSA” mineral wool, basalt wool P-75, or glass wool with glass felt, or foamed polymer, for example, polyethylene or polypropylene, sound absorbing element over its entire surface is lined with acoustically transparent material, for example, glass fiber fabric EZ-100 or polymer of “Poviden” type.

EFFECT: higher efficiency of noise suppression.

1 cl, 3 dwg

Description

The invention relates to a technique for damping noise.

The closest technical solution to the technical nature is a silencer according to RF Patent No. 2305776, F01N 1/00, comprising a housing, an inlet and outlet pipe and a sound absorber (prototype).

Its disadvantage is the relatively low efficiency of sound attenuation.

The technical result is an increase in the efficiency of sound attenuation.

This is achieved by the fact that in a plate silencer containing a rectangular section housing, rigidly connected to the end inlet and outlet pipes, sound-absorbing plates made of a frame containing perforated sheets filled with sound absorbers located in a case with a certain step and forming flat channels in it moreover, the perforation coefficient of the perforated sheets is taken to be equal to or more than 0.25, and an acoustically transparent mat is located between the sound absorber and the perforated sheets ial, sound absorber is made in the form of a rigid and perforated wall, between which two layers are located: a sound-reflecting layer adjacent to the rigid wall, and a sound-absorbing layer adjacent to the perforated wall, while the layer of sound-reflecting material is made of a complex profile consisting of uniformly distributed hollow tetrahedrons, allowing reflecting sound waves incident in all directions, and the perforated wall has the following perforation parameters: hole diameter - 3 ÷ 7 mm, perforation percentage 10% ÷ 15%, p in shape, the holes can be made in the form of holes of a round, triangular, square, rectangular or rhomboid profile, while in the case of non-circular holes, the maximum diameter of the circle inscribed in the polygon should be considered as the conditional diameter, and basalt mineral wool is used as sound-absorbing material basis of the Rockwool type, or mineral wool of the URSA type, or basalt cotton wool of the P-75 type, or glass wool with glass fiber lining.

In FIG. 1 shows a diagram of the proposed silencer assembly, FIG. 2 is a diagram of a sound absorbing plate filled with a sound absorber; FIG. 3 is a diagram of a sound-absorbing element for a sound-absorbing plate.

The plate silencer (Fig. 1) contains a rectangular housing 1, rigidly connected to the end inlet and outlet pipes (not shown in the drawing), sound-absorbing plates 2 made of a frame containing perforated sheets (not shown), filled with a sound absorber, and located in the housing 1 with a certain step A, and forming flat channels in it with a width A. The optimal modes of operation of the muffler occur under the following conditions:

the ratio of the width of the silencer body B to its height lies in the optimal range of values B / N = 0.4 ... 4.0; the ratio of the width of the silencer body B to its length L lies in the optimal range of values B / L = 0.53 ... 2.0; the ratio of the height of the silencer body H to its length L lies in the optimal range of values H / L = 0.33 ... 2.0; the ratio of the width B _{1 of the} plates to the width of the silencer body B lies in the optimal range of values B ₁ / B = 0.05 ... 0.5; the ratio of the width A of the flat channels between the plates to the width of the silencer body B lies in the optimal range of values A / B = 0.05 ... 0.5; the width B _{2 of the} flat channels between the plates and the body lies in the optimal range of values B ₂ = 0 ... A / 2; the ratio of the free cross-sectional area F of the muffler to its length L lies in the optimal range of values F / L = 0.2 / 1000 ... 0.2 / 1500;

Sound-absorbing plates 2 (Fig. 2) are made in such a way that the ratio of the width of the muffler plate B ₁ to its height lies in the optimal range of values B ₁ / H = 0.1 ... 0.8; the ratio of the width of the muffler plate B ₁ to its length L lies in the optimal range of values B ₁ / L = 0.1 ... 0.54; the ratio of the height of the muffler plate H to its length L lies in the optimal range of values H / L = 0.5 ... 1.0.

A silencer case 1 with nozzles and sound-absorbing plates 2 made of a frame containing perforated sheets are made of structural materials with a layer of soft vibration-damping material applied on their surface from one or two sides, for example, VD-17 mastic or “Gerlen-D” type material while the ratio between the thicknesses of the material and the vibration damping coating lies in the optimal range of 1 / (2.5 ... 3.5).

The silencer case 1 and the sound-absorbing plates 2 made of a frame containing perforated sheets are made of stainless steel or galvanized sheet 0.7 mm thick with a protective and decorative polymer coating of the Pural type 50 μm thick or Polyester 25 μm thick, or an aluminum sheet with a thickness of 1.0 mm and a coating thickness of 25 μm. The perforation coefficient of perforated sheets is taken to be equal to or more than 0.25. To prevent the shedding of the soft sound absorber, an acoustically transparent material is provided (not shown in the drawing), for example, fiberglass type EZ-100, located between the sound absorber and the perforated sheet.

The sound absorber is made of rockwool basalt mineral wool or URSA mineral wool or P-75 basalt wool or glass wool lined with glass wool or foamed polymer, such as polyethylene or polypropylene, and the sound absorbing element is the surface is lined with an acoustically transparent material, such as fiberglass type EZ-100 or polymer type "Poviden." The sound absorber is made on the basis of aluminum-containing alloys, followed by filling them with titanium hydride or air with a density in the range of 0.5 ... 0.9 kg / m ³ with the following strength properties: compressive strength in the range of 5 ... 10 MPa, bending strength in the range of 10 ... 20 MPa.

The sound absorber is made of a rigid porous noise-absorbing material, for example foam aluminum, or cermets, or metal foam, or a shell rock with a degree of porosity in the range of optimal values of 30 ... 45%. The sound absorber is made in the form of crumbs from solid vibration-damping materials, for example, elastomer, polyurethane or plastic compound such as Agate, Anti-Vibrate, Shvim, and the size of the fractions of the crumbs lies in the optimal range of values 0.3 ... 2.5 mm.

Plate silencer operates as follows.

Sound waves together with a turbulent stream of compressed air enter the cavity of the silencer body 1 and interact with the sound absorber of the plates 2. The design of the noise silencer is simple to manufacture and maintain. The transition of sound energy into thermal energy (dissipation, energy dissipation) occurs in the pores of the sound absorber, which are the Helmholtz resonator model, where energy losses occur due to friction of the mass of air in the resonator neck oscillating with the excitation frequency against the wall of the neck itself, which has the form branched pore network of sound absorber plates 2.

A variant of the sound-absorbing element (Fig. 3) for the sound-absorbing plate, which is made in the form of a rigid 3 and perforated 6 walls, between which are two layers: a sound-reflecting layer 4 adjacent to the rigid wall 3, and a sound-absorbing layer 5 adjacent to the perforated wall 6 In this case, the layer of sound-reflecting material is made of a complex profile, consisting of uniformly distributed hollow tetrahedra, which allow reflecting sound waves incident in all directions, and the perforated wall has the following perforation parameters: hole diameter - 3 ÷ 7 mm, perforation percentage 10% ÷ 15%, and according to the shape of the hole can be made in the form of holes of a round, triangular, square, rectangular or rhomboid profile, while in the case of non-circular holes as a conditional diameter the maximum diameter of the circle inscribed in the polygon should be considered. As sound-absorbing material of layer 5, rockwool-type mineral wool or URSA-type mineral wool, or P-75-type basalt wool or glass wool lined with glass wool, or foamed polymer, such as polyethylene or polypropylene can be used. The surface of the fibrous absorbers is treated with special porous paints that allow air to pass through (for example, Acutex T) or coated with breathable fabrics or non-woven materials, such as Lutrasil.

Sound-absorbing element (Fig. 3) works as follows.

Sound energy from equipment located in the room, or other object emitting intense noise, passing through the perforated wall 6 enters the layer 5 of soft sound-absorbing material, where it is absorbed, and then to layer 4 of the sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedra, allowing to reflect sound waves incident in all directions, again directing them to sound-absorbing material for secondary absorption and dissipation of sound energy. In fibrous absorbers, the dissipation of the energy of air vibrations and its transformation into heat occurs at several physical levels. Firstly, due to the viscosity of the air, and there is a lot of it in the interfiber space, the oscillation of air particles inside the absorber leads to friction. The transition of sound energy into thermal energy (dissipation, energy dissipation) occurs in the pores of the sound absorber, which are the Helmholtz resonator model, where energy losses occur due to friction of the mass of air in the resonator neck oscillating with the excitation frequency against the wall of the neck itself, which has the form branched network of pore sound absorbers. In addition, there is air friction on the fibers, the surface of which is also large. Thirdly, the fibers rub against each other and, finally, energy dissipation occurs due to the friction of the crystals of the fibers themselves. This explains that at medium and high frequencies the sound absorption coefficient of fibrous materials is in the range of 0.4 ... 1.0.

Claims (1)

A plate silencer comprising a rectangular housing rigidly connected to the front inlet and outlet nozzles, sound-absorbing plates made of a frame containing perforated sheets filled with sound absorbers located in the body with a certain step and forming flat channels in it, and the perforation coefficient of perforated sheets taken equal to or more than 0.25, and between the sound absorber and the perforated sheets there is an acoustically transparent material, characterized in that the sound absorber is made in the form of a rigid and perforated wall, between which there are two layers: a sound-reflecting layer adjacent to the rigid wall, and a sound-absorbing layer adjacent to the perforated wall, while the layer of sound-reflecting material is made of a complex profile consisting of uniformly distributed hollow tetrahedrons that allow reflect sound waves incident in all directions, and the perforated wall has the following perforation parameters: hole diameter - 3 ÷ 7 mm, perforation percentage 10% ÷ 15%, comb the shape of the hole can be made in the form of holes of a round, triangular, square, rectangular or rhomboid profile, while in the case of non-circular holes, the maximum diameter of the circle inscribed in the polygon should be considered as a conditional diameter, and basalt-based mineral wool is used as sound-absorbing material type Rockwool, or mineral wool type URSA, or basalt wool type P-75, or glass wool with glass fiber lining.

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