RU2604262C2 - Multi-section silencer by kochetov for noise reduction of gas-dynamic plants exhaust - 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 base, ejector, leveling grid on which sound-absorbing unit is fixed, consisting of sound-absorbing material layer, lined from inside with perforated shell. Unit consists of individual sequentially connected sections, in each section single sound absorbers are arranged in layers, and in silencer upper part screen is arranged, which includes cylindrical shell, from above connected with cover consisting of perforated layer and sound absorber, wherein exhaust openings are made in form of slits, made along shell periphery, and lined with sound absorbing material. Sound absorber is made in form of two regular polyhedrons concentric dimensional surfaces, wherein one of surfaces: external is made perforated, and other one: internal is made solid, and in gap between surfaces sound-absorbing element is arranged. Surfaces are connected to each other by means of, at least, two bushings, which perform functions of Helmholtz resonator necks, formed by cavity inside regular polyhedron solid surface. Element is made in form of three layers: central layer from complex shaped sound reflecting material, composed of evenly distributed hollow tetrahedrons, allowing to reflect sound waves incident in all directions, and sound-absorbing layers from materials of different density symmetrically adjacent thereto. Over its entire surface element is lined with acoustically transparent material.

EFFECT: technical result is increasing of noise absorption efficiency and structure reliability.

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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.

A single sound-absorbing element is known 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 an 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.

Known sound absorber according to the patent of the Russian Federation No. 2392501 [5], 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 cross section may be triangular.

Their disadvantages are 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 a multi-section exhaust silencer according to the patent of the Russian Federation No. 2318124 [6], F01N 1/00 (prototype), containing a cylindrical socle, an ejector, an alignment grating, on which is mounted a sound-absorbing block consisting of a layer sound-absorbing material lined with a perforated shell from the inside, and the sound-absorbing block consists of separate series-connected sections, in each section single sound absorbers are located, and in the upper part of the muffler there is a screen-type element including a cylindrical shell, connected to the top with a cover consisting of a perforated layer and a sound absorber, and the exhaust holes are made in the form of slots made on the periphery of the shell and are lined with sound-absorbing material, single sound absorbers are made in the form of two concentric volumetric surfaces of regular polyhedrons, one of the surfaces: external - perforated, and the other: internal - continuous, and in between A sound-absorbing element is located between the surfaces, while the surfaces are interconnected by at least two bushings that serve as the necks of the Helmholtz resonator formed by a cavity inside a continuous surface of a regular polyhedron.

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 and the reliability of the structure as a whole by introducing sound-reflecting layers into the sound-absorbing element that perform the function of sound insulation at high frequencies.

This is achieved by the fact that in a multi-section silencer to reduce the exhaust noise of gas-dynamic installations containing a cylindrical base, an ejector, an alignment grate, on which a sound-absorbing block is mounted, consisting of a layer of sound-absorbing material, lined with a perforated shell from the inside, and the sound-absorbing block consists of separate series-connected sections , in each section single sound absorbers are located in layers, and in the upper part of the muffler there is an element of screen type, I include a cylindrical shell, connected at the top with a cover consisting of a perforated layer and a sound absorber, the exhaust holes made in the form of slots made on the periphery of the shell and lined with sound-absorbing material, single sound absorbers are made in the form of two concentric volumetric surfaces of regular polyhedra, and one of the surfaces: the outer one is perforated, and the other: the inner one is solid, and a sound-absorbing element is located between the surfaces, while m of the surface are interconnected by at least two bushings that serve as the necks of the Helmholtz resonator formed by a cavity inside the continuous surface of a regular polyhedron, the sound-absorbing element of the silencer is made in the form of three layers: the central layer of sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedra, allowing to reflect sound waves incident in all directions, and sound absorbing layers symmetrically adjacent to it from the mother fishing 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, with 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-type mineral wool boards are used as sound-absorbing material Rockwool, or URSA mineral wool, or P-75 basalt wool, or glass wool lined with glass wool, and the sound-absorbing element is lined with an acoustically transparent material over its entire surface, such as E3-100 fiberglass or “see” polymer .

Figure 1 presents a General view of the proposed multi-section silencer; figure 2 - design of a single sound absorber, figure 3 is a section of a sound-absorbing element of a single sound absorber located between its concentric volumetric surfaces.

A multi-section muffler to reduce the exhaust noise of gas-dynamic installations contains a cylindrical base 1 (Fig. 1), into which an ejector enters perpendicular to its axis. A leveling grating 2 is placed on the base 1, on which a sound-absorbing block 3 is mounted, consisting of a layer of sound-absorbing material (ZPM), lined from the inside with a perforated shell 4. The sound-absorbing block 3 consists of separate series-connected sections 6. In each section 6, single sound absorbers 5 are arranged in layers. . In the upper part of the silencer housing is a screen-type silencer element 7. It includes a cylindrical shell 8, top connected to the cover 9, consisting of a perforated layer 10 and a sound absorber 11, and the exhaust holes are made in the form of slots 13 made on the periphery of the shell 7, and lined with sound-absorbing material 12.

A single sound-absorbing element 5 of the muffler (Fig. 2) is made in the form of two concentric volumetric surfaces of regular polyhedrons in the form of Platonic solids, for example, a cube, tetrahedron, octahedron, dodecahedron, icosahedron (not shown in the drawing), one of which is external 14 made perforated, and the other inner 15 is solid, between which is located a sound-absorbing element 16, wrapped in an acoustically transparent material 17.

The sound-absorbing element 16 is located in the gap between the surfaces, which are interconnected by means of at least two bushings 19, which serve as the necks of the Helmholtz resonator (not shown in the drawing), formed by a cavity inside a continuous surface of a regular polyhedron. For mounting the element 5 hooks 18 are provided.

The sound-absorbing element is made in the form of a continuous 15 and perforated 14 walls (surfaces), between which there is a multilayer sound-absorbing element made in the form of three layers: the central layer 21 of sound-reflecting material, a complex profile consisting of uniformly distributed hollow tetrahedrons that allow reflecting falling in all directions of sound waves, and sound-absorbing layers 20 and 22 symmetrically adjacent to it from materials of different densities. The perforated wall 14 has the following perforation parameters: the diameter of the holes is 3 ÷ 7 mm, the percentage of perforation is 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 as the conditional diameter should be considered the maximum diameter of the circle inscribed in the polygon.

Each of the walls 14 and 15 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 to one or two sides of the material, 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 walls 14 and 15 can be made of stainless steel or galvanized sheet with a thickness of 0.7 mm with a protective and decorative polymer coating of the type “Pural” 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 coating thickness 25 microns. The perforation coefficient of perforated sheets is taken to be equal to or more than 0.25.

Each of the walls 14 and 15 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, such as fiberglass type E3-100 or a polymer of the “poviden” type, or nonwoven materials, for example, “lutrasil”.

As the material of the sound-reflecting layer 21, 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 0.5 ... 0.9 kg / m ³ with the following strength properties: compressive strength in the range 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 ^{3 were used} .

As sound-absorbing material of layers 20 and 22, 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 20 and 22, a porous sound-absorbing material can be used, for example, foam aluminum or cermets or a stone shell with a degree of porosity in the range of optimal values: 30–45%, or metal foam, or a material in the form of pressed chips from solid vibration-damping materials, for example, elastomer, polyurethane, or plastic compound such as “Agate”, “Anti-Vibrate”, “Shvim”, moreover, the size of the fractions of the crumbs lies in the optimal range of values: 0.3 ... 2.5 mm, and could also porous mineral piece materials were used, for example, pumice, vermiculite, kaolin, slag with cement or other binder, or synthetic fibers, while the surface of the fibrous sound absorbers is treated with special porous airborne paints, for example, Acutex T type, or coated with breathable fabrics or non-woven materials e.g. Lutrasil.

A multi-section muffler to reduce the exhaust noise of gas-dynamic plants works as follows.

Sound waves together with a turbulent stream of compressed air from the ejector enter through the leveling grid 2 in the cavity of the sections 6 of the ZPM. Moreover, the phenomenon of radiation effect is completely eliminated due to the location in the cavities of these sections of single sound-absorbing elements 5 of a muffler of a cylindrical shape.

Increasing the efficiency of sound attenuation occurs due to the elimination of the "radiation effect" by installing a screen-type silencer element 7 in the upper part of the housing, as well as performing a single sound-absorbing element 5 combined, consisting of the active and reactive parts.

Low-frequency sound absorption is due to membrane excitation of the walls of the housing and indirectly internal air volumes. Due to the large damping decrement, the absorption of sound energy during dissipation occurs in the material. The transition of sound energy into thermal energy (dissipation, energy dissipation) occurs in the pores of a 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 frequency of excitation on the neck wall, which has the form of a branched sound absorber pore network.

Information sources

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.30.

2. Kochetov OS Calculation of aerodynamic silencers. The journal "Labor safety in industry", No. 9, 2013, p. 60-63 (Fig. 2, p. 61 and Fig. 5, p. 62).

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

4. Kochetov O.S. A single sound absorber for a noise muffler // RF patent for the invention No. 2394162. Published on July 10th, 2010. Bulletin of inventions No. 19.

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

6. Kochetov O.S., Kochetova M.O., Kochetov S.S., Kochetov Sergey Sergeevich. Multisection silencer Kochetovyh exhaust noise // RF patent for the invention №2318124. Posted 02/27/2008. Bulletin of inventions No. 6.

Claims (1)

A multi-section silencer to reduce the exhaust noise of gas-dynamic installations, containing a cylindrical base, an ejector, an alignment grate, on which a sound-absorbing block is mounted, consisting of a layer of sound-absorbing material, lined from the inside with a perforated shell, and the sound-absorbing block consists of separate series-connected sections, in each section layered in layers single sound absorbers, and in the upper part of the muffler there is a screen-type element including a cylindrical a beech on top connected to a lid consisting of a perforated layer and a sound absorber, the exhaust holes being made in the form of slots made on the periphery of the shell and lined with sound-absorbing material, single sound absorbers are made in the form of two concentric volumetric surfaces of regular polyhedra, one of which is the outer surface made perforated, and the other: the interior is solid, and in the interval between the surfaces is a sound-absorbing element, while the surfaces are connected between through at least two bushings that serve as the necks of the Helmholtz resonator formed by a cavity inside the continuous surface of a regular polyhedron, the sound-absorbing element is made in the form of three layers: a central layer of sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedra that allow reflecting sound waves incident in all directions, and sound-absorbing layers symmetrically adjoining to it from materials of different densities, as sound the absorbing material of the sound-absorbing element, a porous sound-absorbing material, foam aluminum, or cermet, or a shell rock with a degree of porosity in the optimal value range: 30–45%, or metal foam, or a material in the form of pressed chips from solid vibration-damping materials, elastomer, polyurethane, are used or plastic compound such as “Agate”, “Anti-Vibrate”, “Shvim”, moreover, the size of the fractions of the crumbs lies in the optimal range of values: 0.3 ... 2.5 mm, and porous mineral wool can also be used fat materials, pumice, vermiculite, kaolin, slag with cement or another binder, or synthetic fibers, while the surface of the fibrous absorbers is treated with porous air-permeable paints such as Acutex T or coated with breathable fabrics or non-woven materials, Lutrasil, and as a sound-reflecting material applied alyuminesoderzhaschih material based alloys followed by filling them with the titanium hydride or the density of air within 0.5 ... 0.9 kg / m ³ with the following tensile properties: Ruggedness compression within 5 ... 10 MPa, the flexural strength in the range of 10 ... 20 MPa, foam aluminum, or sound insulating plate on the base glass staple fiber type "Shumostop" with material density of 60 ÷ 80 kg / m ^3, apertured wall soundabsorbing the silencer element is made of structural materials with a layer of soft vibration-damping material, VD-17 mastic or “Gerlen-D” type material deposited on their surface on one or two sides, while the ratio between the thicknesses of the material and the vibration-damping coating is l hedgehog in the optimal range of values: 1 / (2.5 ... 3.5), or from solid, decorative vibration-damping materials of plastic compounds such as Agate, Anti-Vibrate, Shvim, with the inner surface of the perforated surface facing the sound-absorbing structure lined with an acoustically transparent non-woven material Lutrasil, characterized in that as a sound-reflecting material of the sound-absorbing element of the muffler, a material based on foil, or fiberglass, or carbon fiber, or plastic containing as reinforcing filler carbon fiber.

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