RU2604263C2 - Element of kochetov noise suppressor - Google Patents

Abstract

FIELD: engines.

SUBSTANCE: invention relates to noise suppression equipment of compressor stations and test boxes for gas turbine engines. Silencer incorporates cylindrical frame in form of perforated bushing and covers, filled with sound absorber, layer of acoustic transparent shell made of capronic net of glass cloth is arranged outside of bushing, and frame comprises cover with circular collars for cylindrical bushing fixing, wherein covers are connected by central rod with hooks on both ends, and cylindrical bushing consists of two perforated shells, external and internal, space between which is filled with sound absorbing element. Sound-absorbing material placed in sound absorber inner cavity 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 perpendicular to rod cross-section, of closed shape in form of Archimedean spiral with air gaps increasing from center to periphery. Covers have conical shape fairings at outer surfaces. Sound absorbing element contains perforated walls, between which layers of sound reflecting, as well as sound-absorbing materials of different density are arranged.

EFFECT: technical result is higher efficiency of noise suppression.

1 cl, 2 dwg

Description

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

It is known that centrifugal fans, compressor stations, and test boxes use silencers for suction and bleed compressor units [1, 2], which contain a cylindrical body, a frame with a central shaft, and a perforated cylindrical sleeve that is filled with sound-absorbing material.

Its disadvantage is the relatively low efficiency of noise attenuation at medium and high frequencies.

Known single sound-absorbing element according to the patent of the Russian Federation No. 2280172 [3], 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.

Its disadvantage is the relatively low efficiency of noise attenuation at medium and high frequencies.

Known sound absorber according to the patent of the Russian Federation No. 2394162 [4], 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. Between the shells of the perforated sleeve there is a sound absorber made of profiled porous sheet, and the profile of the sheet in the section can be triangular, rectangular, trapezoidal, or in the form of circular arcs, or sinusoidal. In the case of two or more profiled porous sheets, they can be located both with gaps between them and without gaps. The lateral closed surfaces of the shells 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.

Its disadvantage is the relatively low efficiency of sound attenuation at high frequencies, since the porosity of sound-absorbing elements is the same both between the shells of the perforated sleeve and inside it.

The closest technical solution to the technical nature and the achieved result is an element of a silencer according to RF patent No. 2392501 [5], 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 space between which is filled with a sound-absorbing element, while a layer of an acoustically transparent shell is located outside the sleeve, and a sound-absorbing material located inside The lower cavity of the perforated cylindrical sleeve has a higher porosity compared to the sound absorber inside its shells, and is made of a spinning roll of sound absorber, one end of which is rigidly fixed to the central shaft, and the free end abuts against the inner shell of the perforated cylindrical sleeve with the formation in the cross section perpendicular axis, closed in the form of a spiral of Archimedes with increasing air gaps from the center to the periphery.

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 a single sound absorber for compressor station silencers, containing a cylindrical frame in the form of a perforated sleeve and covers, filled with a sound absorber, a layer of an acoustically transparent shell made of nylon mesh or fiberglass is located on the outside of the sleeve, 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 - the outer and the interior, 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 the rod, and the free end abuts against the inner shell with the formation in the cross section perpendicular to the closed rod in the form of an Archimedes spiral 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 cowls 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, arranged in two layers, the layers of sound-reflecting material made of a complex profile, consisting of uniformly distributed hollow 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 that can maintain a given microclimate in the room, and basalt mineral wool slabs are used as sound-absorbing material basis of the Rockwool type, or mineral wool of the URSA type, or basalt wool of the P-75 type, or glass wool with a glass-fiber lining, moreover, the sound-absorbing element is lined with an acoustically transparent material over its entire surface, for example, EZ-100 fiberglass or “visible” polymer, and each of the perforated walls has the following perforation parameters: hole diameter 3 ÷ 7 mm, perforation percentage 10% ÷ 15%, moreover, the shape of 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 in writable in a polygon circle.

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.

The noise suppressor element consists of a frame that contains covers 1 and 2 with annular flanges 3 for fastening the cylindrical sleeve, the covers being connected by a central rod 4 with hooks at both ends, and the cylindrical sleeve consists of two perforated shells - external 7 and internal 8, the space between which is filled with a sound absorber 9. Outside of the perforated cylindrical sleeve there is a layer of acoustically transparent shell 11 made, for example, of a nylon 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.

The shells 7 and 8 are made of a perforated sheet of stainless steel or galvanized sheet with a thickness of 0.7 mm with a polymer protective and decorative coating such as Pural 50 μm thick, or Polyester 25 μm thick, or an aluminum sheet 1.0 mm thick and coating thickness 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 structure (Fig. 2) is made in the form of symmetrically arranged perforated 13 and 17 walls, between which there is a sound-absorbing element made in the form of three layers: the central layer 15 of sound-reflecting material, a complex profile consisting of uniformly distributed hollow tetrahedrons that allow reflecting incident sound waves in all directions, and sound-absorbing layers 14 and 16 symmetrically adjoining to it from materials of different densities. 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 holes of a round, triangular, square, rectangular or rhomboid profile, while in the case of non-circular holes as the conditional diameter should be considered the maximum diameter of the circle inscribed in the polygon.

Each of the perforated walls 13 and 17 can be made of structural materials, with a layer of soft vibration-damping material, for example, VD-17 mastic or “Gerlen-D” type material applied 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 1 and 5 can be made of stainless steel or a galvanized sheet with a thickness of 0.7 mm with a protective and decorative polymer coating of 50 μm thick or Polyester 25 μm thick, or aluminum sheet 1.0 mm thick and a coating thickness of 25 microns. The perforation coefficient of perforated sheets is taken to be equal to or more than 0.25.

Each of the perforated walls 13 and 17 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."

As the material of the sound-reflecting layer 15, 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, or soundproof boards based on glass staple fiber of the Shumostop type with a material density of 60 ÷ 80 kg / m were used.

As sound-absorbing material of layers 14 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. Moreover, the sound-absorbing material is lined with an acoustically transparent material over its entire surface, for example, E3-100 fiberglass or a “visible” polymer, or the surface of the fibrous sound 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, e.g. Lutrasil. In addition, as the sound-absorbing material of the layers 14 and 16, a porous sound-absorbing material, for example, foam aluminum, or cermet, or a rock shell with a degree of porosity in the range of optimal values: 30–45%, or metal foam, or in the form of pressed crumbs from solid vibration-damping materials, for example elastomer, polyurethane, or plastic compound like “Agate”, “Anti-vibration”, “Shvim”, and the size of the fractions of the crumbs lies in the optimal range of values: 0.3 ... 2.5 mm, and I can also porous mineral piece materials, for example pumice, vermiculite, kaolin, slag with cement or other binder, or synthetic fibers, or the surface of the fibrous sound absorbers are treated with special porous airborne paints such as Acutex T or coated with breathable fabrics or non-woven materials e.g. Lutrasil.

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 that 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 other 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 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.

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. As sound-absorbing material of layers 14 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 17 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 acoustically transparent material for example, fiberglass type E3-100 or a polymer of the type "seen", or non-woven materials, such as "lutrasil."

The silencer element operates 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. The transition of sound energy into thermal energy (dissipation, energy dissipation) occurs in the pores of sound-absorbing material, which is a 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 walls of the mouth itself, having the form branched network of pore sound absorbers.

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

As a sound-reflecting material, a material based on foil, or fiberglass, or carbon fiber, or plastic containing carbon fibers as a reinforcing filler 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 sound-absorbing heat-resistant heat-resistant and highly porous heat-resistant material is used. made of mineral filler in the form of fibers of diox and silica (quartz fiber), a binder, a sintering aid, which is used as the amorphous boron or boron compound, and a surfactant.

As the sound-absorbing material used porous sound-absorbing ceramic material having a bulk density of 500 ÷ 1000 kg / m ³ and consisting of 100 wt. including perlite with a particle diameter of 0.5 ÷ 2.0 mm, 100 ÷ 200 wt. including one or more sintering materials and 10 ÷ 20 wt. including binding 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 another object that emits intense noise, passing through the perforated walls 13 and 17, enters the layer 15 of sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedrons, which allow reflecting sound waves incident in all directions , and which are located respectively at the perforated 13 and 17 walls, and then falls onto layers 14 and 16 of soft sound-absorbing material of different densities located in two layers (for example, ennogo basalt or glass fibers). 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 a sound absorber, which are Helmholtz resonator models, where energy losses occur due to friction of the mass of air in the cavity of the resonator, which vibrates 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.

LITERATURE

1. Kochetov O.S., Sazhin B.S. Noise and vibration reduction in production: theory, calculation, technical solutions. M .: MSTU im. A.N. Kosygina, 2001 .-- 319 p.: P. 278, fig. P. III. thirty.

2. Kochetov OS, Calculation of aerodynamic silencers. Journal of Occupational Safety in Industry, No. 9, 2013, pp. 60-63. (FIG. 2, Page 61 AND FIG. 5. Page 62).

3. Kochetov O.S., Kochetova M.O., Khodakova T.D. Multisection silencer of exhaust noise // RF patent for the invention No. 2280172. Publ. 07/20/2006. Bulletin of inventions No. 20.

4. Kochetov O.S. Single sound absorber for a noise muffler // RF patent for the invention No. 2394162. Publ. 07/10/2010. Bulletin of inventions No. 19.

5. Kochetov O.S. Single sound absorber Kochetova // RF patent for the invention No. 2392501. Publ. 06/20/2010. Bulletin of inventions No. 17.

Claims (1)

A silencer element comprising a cylindrical frame in the form of a perforated sleeve and covers filled with a sound absorber, an acoustic transparent layer of nylon mesh or fiberglass is located outside the sleeve, and the frame contains covers with ring beads for attaching the cylindrical sleeve, and the covers are connected by hooks to the central shaft at both ends, and the cylindrical sleeve consists of two perforated shells of the external and internal, the space between which is filled with a sound-absorbing element volume, 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 shaft, and the free end abuts against inner shell with the formation in the cross section perpendicular to the rod, closed in the form of a spiral of Archimedes with increasing from the center to the periphery of the air and gaps, while it has a higher porosity compared to the sound absorber located inside the shells, and the covers have conical shaped cowls on the outer surfaces, the sound-absorbing element contains perforated walls, between which are layers of sound-reflecting, as well as sound-absorbing materials of different densities located in two layers, the layers of sound-reflecting material made of a complex profile, consisting of uniformly distributed hollow tetrahedra, allowing to reflect the pad Sound waves emitting in all directions, and which are respectively located near the perforated walls, characterized in that the layers of sound-reflecting material are made of heat-insulating material that can maintain a given microclimate in the room, and rockwool basalt-based mineral wool boards are used as sound-absorbing material. ", Or mineral wool of the URSA type, or basalt wool of the P-75 type, or glass wool lined with glass wool, and the sound-absorbing element over its entire surface it is lined with an acoustically transparent material, fiberglass type E3-100 or a “visible” polymer, 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 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 a circle inscribed in a polygon should be considered as a conditional diameter.

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