RU2603875C2 - Multi-section noise suppressor - Google Patents

Abstract

FIELD: engines.

SUBSTANCE: invention relates to compressor stations and test boxes noise suppression equipment for gas turbine engines. Silencer incorporates cylindrical base, rigidly connected with end inlet and outlet nozzles, rigidly connected with central partitions, having perforation. Sound-absorbing unit sound-absorbing lining is made in form of two layers, one of which, adjoining rigid wall, is sound-absorbing, and other, adjoining perforated wall, is made from complex shaped sound reflecting material. Complex shaped sound-reflecting material consists of uniformly distributed hollow tetrahedrons, which enable to reflect sound waves incoming from all directions. Each of perforated walls has following perforation parameters: holes diameter of 3÷7 mm, perforation percentage of 10 %÷15 %, wherein by form holes can be of circular, triangular, square, rectangular or rhomboid shape, wherein in case of non-circular holes, maximum diameter of circle inscribed into polygon shall be considered as nominal diameter, and plates from mineral wool on basalt base of “Rockwool” type are used as sound absorbing material, or “URSA” type mineral wool, or P-75 type basalt wool, or glass wool with glass felt, wherein sound absorbing element over its entire surface is lined with acoustically transparent material, glass-fiber fabric of E3-100 type or polymer of "poviden" type.

EFFECT: technical result is higher efficiency of noise suppression.

1 cl, 9 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.

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. A sound absorber is located between the shells of the perforated sleeve, and a layer of acoustically transparent shell is located outside the perforated cylindrical sleeve.

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. 2280176 [6], F01N 1/00 (prototype), containing a cylindrical socle, an ejector, an alignment grating, on which a sound-absorbing block consisting of a layer is fixed 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 two concentric volumetric surfaces of regular polyhedra, one of the surfaces: external - perforated, and the other: internal - solid, and in between heel surfaces located between the sound-absorbing element, wherein the surfaces are interconnected by at least two bushings that perform functions necks Helmholtz resonator formed by the cavity inside a solid 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 containing a cylindrical base, rigidly connected to the end inlet and outlet pipes, rigidly connected to the central partitions having perforations, a leveling grid connected to the adapter is mounted on the base, on which a sound-absorbing unit consisting of individual series-connected sections, each of which is made of a layer of sound-absorbing material (ZPM), thickness "a", lined with a perforated shell from the inside, with than the section consists of four subsections with a characteristic size “c”, in which single sound absorbers with a certain step “b” are located, moreover, single sound absorbers are made of a spherical shape, while the ZPM is enclosed in hemispheres made of perforated material, and the hemispheres are attached to each other and in sections can be carried out by means of fasteners in the form of rods and rings. The single sound-absorbing element of the muffler is made of a cylindrical shape, the frame of which is made up of rods, covers with holes, the central shaft being fixed with a cotter pin. A single sound-absorbing element of a silencer is made of a cylindrical reactive type, consisting of a central shaft with disks fixed to it with a variable pitch, and the cylinder body is made in the form of a glass and contains resonant holes, and the glass itself has a lid on top, inside one of which in all cavities, ZPM can be located.

Figure 1 presents a General view of the proposed muffler; figure 2 is a section aa of figure 1; figure 3, figure 4, figure 5 is a sound-absorbing element of a spherical silencer and its mounting options in the silencer; Fig.6 is a sound-absorbing element of a muffler of a cylindrical shape; figure 7 shows a top view of figure 6; in Fig.8 is a sound-absorbing element of a muffler of a cylindrical shape of a reactive type, in Fig.9 is a sound-absorbing lining of a sound-absorbing block.

The multi-section silencer contains a cylindrical base 7, into which an ejector 1 enters perpendicular to its axis. An alignment grating connected to an adapter 6 is mounted on the base 7, on which a sound-absorbing unit 3 is mounted, consisting of separate, connected in series sections 8, a section of one of which is shown figure 2. Each of the sections 8 is made with sound-absorbing cladding 4, thickness "a". Section 8 consists of four subsections with a characteristic size “c” (for example, the side of the square), in which there are single sound absorbers 5 with a step “b”. Section 8 can be made in a section perpendicular to the axis, rectangular, cylindrical and any other shape, and also have any number of subsections, starting from one, and in a section perpendicular to the axis, have a rectangular, cylindrical and any other shape (not shown ) Single sound absorbers 5 can be made spherical in shape, as shown in figure 3-figure 5. In this case, the ZPM 10 is enclosed in hemispheres 9 made of perforated material. The hemispheres can be fixed to each other and in sections 8 by means of fasteners 11 and 12 in the form of rods and rings, as shown in FIG. 3-FIG. 5. Figure 6 shows a single sound-absorbing element of a muffler of cylindrical shape, the frame of which is made up of rods 12, covers 11 and 13 with holes 15, the central shaft 14 being fixed with a cotter pin 16. ZPM 10 in the form of balls of various shapes is located in an acoustically transparent shell 9 ( for example, in a perforated flexible shell). On Fig depicts a single sound-absorbing element of a cylindrical-shaped muffler of the reactive type, consisting of a central rod 17, with disks 18 mounted on it with a variable pitch. . Inside the glass, in one or in all cavities, can be located ZPM 10.

The sound-absorbing lining 4 (Fig. 9) of the sound-absorbing block 3 is made in the form of a rigid wall 21 and a perforated wall 22, between which there is a two-layer combined sound-absorbing element, the layer 23 adjacent to the rigid wall 21 is made sound-absorbing, and the layer 24 adjacent to the perforated wall It is made of sound-reflecting material, a complex profile consisting of uniformly distributed hollow tetrahedrons, allowing to reflect sound waves incident in all directions. The perforated wall 22 has the following perforation parameters: 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. At the same time, the sound-absorbing layer 23 is placed in an acoustically transparent material, for example, fiberglass type EZ-100, or a polymer of the “visible” type, or a non-woven material, for example, “lutra-force”.

Each of the walls 21 and 22 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 21 and 22 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” 50 μm thick or “Polyester” 25 μm thick, or an aluminum sheet 1.0 mm thick 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 21 and 22 can be made of solid, decorative vibration damping materials, such as plastic compounds such as "Agate", "Anti-vibration", "Shvim".

As the material of the sound-reflecting layer 24, 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 were used.

As sound-absorbing material of layer 23, 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. Moreover, the sound-absorbing material is lined with an acoustically transparent material over its entire surface, for example, EZ-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 layer 23, a porous sound-absorbing material can be used, for example, foam aluminum or cermet or a shell rock with a degree of porosity in the range of optimal values: 30–45%, or metal foam, or a material in the form of pressed crumbs made of hard 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, and can also be used porous mineral piece materials are used, for example, pumice, vermiculite, kaolin, slag with cement or another binder, or synthetic fibers, while 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, 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 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.

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.

Multi-section silencer operates as follows.

Sound waves together with a turbulent flow of compressed air from the ejector 1 enter through the leveling grating 2 in the cavity of the sections 8 of the ZPM. In this case, 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 the muffler of a cylindrical (Fig.6-Fig.8) or spherical shape (Fig.3-Fig.5). An increase in the efficiency of sound attenuation occurs due to the elimination of the "radiation effect" and the increased surface of sound absorption due to the implementation of single sound-absorbing elements in the form of a spherical shape, as well as the expansion of the frequency band of sound attenuation due to the presence of resonant elements.

Sound-absorbing lining 4 of the sound-absorbing block 3 operates as follows. Sound energy from equipment located in the room, or another object that emits intense noise, passing through the perforated wall 22 enters the layer 24 of sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedrons, which allow reflecting sound waves incident in all directions, and part of the sound energy passes through the layer 24 of sound-reflecting material, and interacts with the layer 23 of sound-absorbing material, where the final dispersion of sound energy occurs WGIG. 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 a model of Helmholtz resonators, 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, which has the form of a branched pore network sound absorber. 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.

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

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

4. Kochetov O.S. Single sound absorber for silencer. // 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 No. 2392501. Published 06/20/2010. Bulletin of inventions No. 17.

6. Kochetov O.S., Kochetova M.O., Khodakova T.D., Shesterninov A.V., Lvov G.V., Kulichenko A.V. Multisection silencer. // RF patent for the invention No. 2280176. Published on July 20, 2006. Bulletin of inventions No. 20.

Claims (1)

A multi-section silencer containing a cylindrical base rigidly connected to the end inlet and outlet pipes rigidly connected to the central partitions having perforations, the sound-absorbing lining of the sound-absorbing block is made in the form of two layers, one of which adjacent to the rigid wall is sound-absorbing, and the other adjacent to the perforated wall is made of a sound-reflecting material of a complex profile, characterized in that the sound-reflecting material of a complex profile consists of of numerically distributed hollow tetrahedra, allowing to reflect sound waves incident in all directions, 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 round holes, triangular, square, rectangular or rhomboid profile, while in the case of non-circular holes, the conditional diameter should be considered the maximum diameter of the circle inscribed in the polygon, and as a sound of absorbing material, slabs made of rockwool basalt mineral wool or URSA mineral wool or P-75 basalt wool or glass wool lined with glass wool are used, and the sound-absorbing element is lined with acoustically transparent material, fiberglass over its entire surface type E3-100 or polymer type "poviden."

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