RU2581969C1 - Kochetov acoustic absorber for noise silencers of compressor stations - Google Patents

Abstract

FIELD: acoustics; instrumentation.

SUBSTANCE: sound absorber is designed for damping noise of compressor stations and test boxes for gas turbine engines. Sound absorber comprises a cylindrical frame in form of perforated sleeve and cover, filled with sound absorber, and outside bushing there is a layer of acoustically transparent cover, and frame comprises cover with circular collars for fixing the cylindrical bushing, covers are central rod with hooks on both ends, and cylindrical sleeve consists of two perforated shells, inner and outer, space between which is filled with sound absorbing element outside perforated cylindrical bushing there is a layer of acoustically transparent shell, wherein sound-absorbing material placed in inner cavity of sound absorber is made of unwinding roll, one end of which is rigidly fixed on central rod, and free end rests against inner shell to form in cross-section perpendicular to rod, a closed shape in form of Archimedean spiral with increasing from centre to periphery air gaps, wherein it has higher porosity in comparison to sound absorber located inside shells and covers have outer surfaces of fairings conical shape, and sound-absorbing element comprises perforated walls, between which there are layers of sound reflecting and sound-absorbing materials of different density arranged in two layers, wherein layers of sound reflecting material are made from complex profile composed of evenly distributed hollow tetrahedrons, which enable to reflect sound waves incident in all directions and which are located respectively at perforated walls, and layers of sound reflecting material are made from heat-insulating material, wherein sound-absorbing element over its entire surface is lined with acoustically transparent material.

EFFECT: high efficiency of soundproofing at high frequencies.

1 cl, 2 dwg

Description

The invention relates to techniques for damping the noise of compressor stations and test boxes for gas turbine engines.

Known sound absorber according to the patent of the Russian Federation No. 2394162 [1], F01N 1/00, containing a cylindrical frame in the form of a perforated sleeve and covers, filled with a sound absorber, and on the outside of the sleeve there is a layer of acoustically transparent shell made of nylon mesh or fiberglass.

The closest technical solution to the technical nature and the achieved result is a single sound absorber according to RF patent No. 2392501 [2], F01N 1/00, which is made of a cylindrical shape, and its frame is made of covers connected by a central rod with a perforated cylindrical sleeve, which consists of two perforated shells.

The disadvantage of the prototype is the relatively low efficiency of sound attenuation at high frequencies, since the sound-absorbing element located inside the shells of the perforated cylindrical sleeve is single-layer and has no sound-reflecting layers that perform sound insulation functions at high frequencies.

The technical result is to increase the efficiency of sound attenuation at high frequencies by introducing into the sound-absorbing element located inside the shells of the perforated cylindrical sleeve, sound-reflecting layers that perform the function of sound insulation at high frequencies.

This is achieved by the fact that in the sound absorber for silencers of compressor stations containing a cylindrical frame in the form of a perforated sleeve and covers, filled with a sound absorber, and on the outside of the sleeve there is a layer of an acoustically transparent shell made of nylon mesh or fiberglass, and the frame contains covers with ring beads for attaching a cylindrical bushings, while the covers are connected by a central rod with hooks at both ends, and the cylindrical sleeve consists of two perforated shells - external and internal d, the space between which is filled with a sound-absorbing element, and on the outside of the perforated cylindrical sleeve there is a layer of an acoustically transparent shell made of nylon mesh or fiberglass, while the sound-absorbing material located in the inner cavity of the sound absorber is made of a spinning roll, one end of which is rigidly fixed to the central rod, and the free end abuts against the inner shell with the formation in the cross section perpendicular to the rod, closed in the form of a joint Archimedes ’rails with air gaps increasing from the center to the periphery, while it has a higher porosity compared to the sound absorber located inside the shells, and the covers have conical shaped fairings on the outer surfaces, and the sound-absorbing element contains perforated walls, between which sound-reflecting layers are located, as well as sound-absorbing materials of different densities.

In FIG. 1 is a perspective view of a single sound absorber of a noise suppressor; FIG. 2 is a diagram of a sound-absorbing element located inside the shells of a perforated cylindrical sleeve.

A single sound absorber for compressor station noise suppressors consists of a frame that contains covers 1 and 2 with annular collars 3 for fastening a cylindrical sleeve, with the covers being connected by a central rod 4 to hooks at both ends, and the cylindrical sleeve consists of two perforated shells - external 7 and inner 8, the space between which is filled with a sound absorber 9. Outside of the perforated cylindrical sleeve there is a layer of an acoustically transparent shell 11 made, for example, of kapron mesh or fiberglass. Sound-absorbing material 10, located in the inner cavity of the sound absorber, is made of a spinning roll, one end of which is rigidly fixed on the central shaft 4, and the free end abuts against the inner shell 8 with the formation in the cross section perpendicular to the shaft 4 of a closed shape in the form of an Archimedes spiral with increasing from the center to the periphery by air gaps (not shown), while it has a higher porosity compared to the sound absorber 9 located inside the shells 7 and 8. In this case, the cover 1 and 2 are the outer surfaces 5 and 6 fairings conical shape to reduce the hydraulic resistance when installed in a single absorber sound attenuation systems, compressor stations, and a cylindrical sleeve fixed cover members 1, 2 by means of nuts 12 on the rod 4.

The lateral closed surfaces of the shells 7 and 8 can have in cross section not only a circle in the case of a cylindrical shape, but also the shape of a triangle, a polyhedron, an ellipse, or any combination of these figures.

Shells 7 and 8 are made of perforated stainless steel sheet or galvanized sheet with a thickness of 0.7 mm with a protective and decorative polymer coating such as Pural 50 microns thick or Polyester 25 microns thick, or an aluminum sheet 1.0 mm thick and thick coatings 25 microns.

As the sound-absorbing material of the sound absorber 9, a porous sound-absorbing material is used, for example, foam aluminum or cermets, or metal foam, or in the form of pressed crumbs of solid vibration-damping materials, for example elastomer, polyurethane, or plastic compound such as “Agate”, “Anti-vibration”, “Shvim”, and the size of the crumbs fractions lies in the optimal range of values: 0.3 ... 2.5 mm (not shown).

As sound-absorbing material 10 located in the inner cavity of a single sound absorber, rockwool-type mineral wool, or URSA-type mineral wool, or P-75 type cotton wool, or glass wool lined with glass wool, or foamed polymer are used, for example polyethylene or polypropylene.

The sound-absorbing element (Fig. 2) for acoustic screens, piece sound absorbers, partitions is made in the form of symmetrically arranged perforated 13 and 18 walls, between which are layers of sound-reflecting 14 and 17 materials, as well as sound-absorbing 15 and 16 materials of different densities, located in two layers moreover, the layers of sound-reflecting material are made of a complex profile consisting of uniformly distributed hollow tetrahedrons, which allow reflecting sound waves incident in all directions and which are located respectively, for perforated 13 and 18 walls, and each of the perforated walls has the following perforation parameters: hole diameter - 3 ÷ 7 mm, perforation percentage 10% ÷ 15%, and the shape of the hole can be made in the form of round, triangular, square holes , rectangular or diamond-shaped 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.

Each of the perforated walls 13 and 18 can be made of structural materials, with a layer of soft vibration-damping material, for example, VD-17 mastic or Gerlen-D type material, deposited on their surface from one or two sides, and the ratio between the thicknesses of the material and vibration damping coating lies in the optimal range of values: 1 / (2.5 ... 3.5).

Each of the perforated walls 13 and 18 can be made of stainless steel or galvanized sheet with a thickness of 0.7 mm with a polymer protective and decorative coating of the Pural type with a thickness of 50 μm or Polyester with a thickness of 25 μm, or an aluminum sheet with a thickness of 1.0 mm and a coating thickness of 25 microns. The perforation coefficient of perforated sheets is taken to be equal to or more than 0.25.

As the material of the sound-reflecting layers 14, 17, a material based on aluminum-containing alloys can be used, 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, for example foam aluminum.

As the material of the sound-reflecting layers 14, 17, sound-proofing plates based on glass noise staple fiber of the “Shumostop” type with a material density of 60 ÷ 80 kg / m ³ can be used.

To reduce or correct the reverberation time of premises, sound-absorbing materials and structures (sound absorbers) are used in its decoration.

Porous sound absorbers are made in the form of plates, which are attached to the enclosing surfaces directly or on the basis of light and porous mineral piece materials - pumice, vermiculite, kaolin, slag, etc., with cement or another binder. Such materials are strong enough and can be used to reduce noise in corridors, foyers, staircases of public and industrial buildings.

The raw materials for their production are wood fibers, mineral wool, glass wool, synthetic fibers. The surface of the fibrous sound absorbers is treated with special porous paints that allow air to pass through (for example, Acutex T), or covered with breathable fabrics or non-woven materials, such as Lutrasil.

Currently, fibrous sound absorbers are the most common in construction practice. They not only proved to be the most effective from an acoustic point of view in a wide frequency range, but also meet the increased requirements for room design.

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. 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. The sound absorption coefficient α is equal to the ratio of the energy of the air vibration not reflected (absorbed inside and passed through) from the surface to the total energy acting on the surface.

As sound-absorbing material of layers 15 and 16, 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. 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.

Each of the perforated walls 13 and 18 can be made of solid, decorative vibration damping materials, such as plastic compounds such as Agate, Anti-Vibrate, Shvim, and the inner surface of the perforated surface facing the sound-absorbing structure is lined with an acoustically transparent material, for example fiberglass type EZ-100 or polymer type "poviden", or non-woven materials, such as "lutrasil."

Sound absorber for silencers of compressor stations works as follows.

Sound absorption at low and medium frequencies is due to membrane excitation of the walls of the housing and, indirectly, the internal volumes of air in the air gaps of the sound-absorbing material 10 located in a spiral of Archimedes.

As a sound-reflecting material, a material based on a magnesian binder with a reinforcing fiberglass or fiberglass was used.

Polyester is used as a sound-absorbing material.

As a sound-absorbing material, a porous fibrous or foamy sound-absorbing material is used, which is made on the basis of basalt or glass fibers, or open-cell polyurethane foam with a protective sound-transparent sheath made of thin fiberglass or aluminized lavsan film.

As a sound-absorbing material, a porous sound-absorbing ceramic material having a bulk density of 500 ÷ 1000 kg / m ³ and consisting of 100 mass parts of perlite with a particle diameter of 0.5 ÷ 2.0 mm, 100 ÷ 200 mass parts of one or more sintering materials and 10 ÷ 20 mass parts of binder materials. During sintering, perlite particles at adjacent points form adjacent pores. This material has good sound absorption in a wide frequency range, but has a high density associated with the content of a large number of sintering materials.

Sound-absorbing element operates as follows.

Sound energy from equipment located in the room, or other object emitting intense noise, passing through the perforated walls 13 and 18, enters the layers 14 and 17 of the sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedrons, allowing to reflect sound waves incident in all directions and which are located respectively at the perforated 13 and 18 walls, and then falls onto layers 15 and 16 of soft sound-absorbing material of different densities located in two layers (for example, flax from basalt or glass fiber). 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.

Information sources

1. Kochetov OS A single sound absorber for a noise muffler // RF patent for the invention No. 2394162, publ. 07/10/2010, bull. No. 19.

2. Kochetov OS Single sound absorber Kochetova // RF patent for the invention No. 2392501, publ. 06/20/2010, bull. Number 17.

Claims (1)

A sound absorber for compressor station noise suppressors, comprising a cylindrical frame in the form of a perforated sleeve and covers, filled with a sound absorber, and a layer of an acoustically transparent shell made of nylon mesh or fiberglass located outside the sleeve, and the frame contains covers with ring beads for attaching the cylindrical sleeve, while the covers are connected the central rod with hooks at both ends, and the cylindrical sleeve consists of two perforated shells - external and internal, the space between which it is filled with a sound-absorbing element, and on the outside of the perforated cylindrical sleeve there is a layer of an acoustically transparent shell made of nylon mesh or fiberglass, while the sound-absorbing material located in the internal cavity of the sound absorber is made of a spinning roll, one end of which is rigidly fixed to the central shaft, and the end abuts against the inner shell with the formation in a section perpendicular to the rod of a closed shape in the form of a spiral of Archimedes with air gaps from the center to the periphery, while it has a higher porosity compared to the sound absorber located inside the shells, and the covers have conical shaped cowls on the external surfaces, the sound-absorbing element contains perforated walls, between which are layers of sound-reflecting and sound-absorbing materials of different density, arranged in two layers, the layers of sound-reflecting material made of a complex profile, consisting of uniformly distributed hollows tetrahedra, which allow reflecting sound waves incident in all directions and which are located respectively near the perforated walls, and the layers of sound-reflecting material are made of heat-insulating material, and porous sound-absorbing material, foam aluminum, or cermet, or metal-porol, or material in the form of pressed crumbs from solid vibration-damping materials, elastomer, polyurethane or plastic compound such as "Agate", "Anti-Vibrate", "Shvim", characterized by m that a material based on a magnesian binder with a reinforcing fiberglass or fiberglass is used as a sound-reflecting material, and polyester, or a porous fibrous or foamy sound-absorbing material, which is made on the basis of basalt or glass fibers or an open-cell polyurethane foam with a protective soundproofing material, is used as a sound-absorbing material. from thin fiberglass or aluminized lavsan film, or porosity is used as sound-absorbing material th sound-absorbing ceramic material having a bulk density of 500 ÷ 1000 kg / m ³ and consisting of 100 mass parts of perlite with a particle diameter of 0.5 ÷ 2.0 mm, 100 ÷ 200 mass parts of one or more sintering materials and 10 ÷ 20 mass parts binding materials.

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