GB2258841A - Sound absorber member for use at high temperatures - Google Patents

Sound absorber member for use at high temperatures Download PDF

Info

Publication number
GB2258841A
GB2258841A GB9214863A GB9214863A GB2258841A GB 2258841 A GB2258841 A GB 2258841A GB 9214863 A GB9214863 A GB 9214863A GB 9214863 A GB9214863 A GB 9214863A GB 2258841 A GB2258841 A GB 2258841A
Authority
GB
United Kingdom
Prior art keywords
flow resistance
sound absorber
member according
absorber member
absorbent material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9214863A
Other versions
GB9214863D0 (en
GB2258841B (en
Inventor
Lank Gerd De
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Isover G+H AG
G&H Montage GmbH
Original Assignee
G&H Montage GmbH
Gruenzweig und Hartmann AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by G&H Montage GmbH, Gruenzweig und Hartmann AG filed Critical G&H Montage GmbH
Publication of GB9214863D0 publication Critical patent/GB9214863D0/en
Publication of GB2258841A publication Critical patent/GB2258841A/en
Application granted granted Critical
Publication of GB2258841B publication Critical patent/GB2258841B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
    • F01N1/082—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling the gases passing through porous members
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B32B5/022—Non-woven fabric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2305/00—Condition, form or state of the layers or laminate
    • B32B2305/38—Meshes, lattices or nets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/10—Properties of the layers or laminate having particular acoustical properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2310/00—Selection of sound absorbing or insulating material
    • F01N2310/02—Mineral wool, e.g. glass wool, rock wool, asbestos or the like

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Exhaust Silencers (AREA)

Description

2 2 5 33,3 41 1 Sound Absorber Member for Use at High Temperatures
Description
This invention relates to a sound absorber member for use in hightemperature gas flows, said member comprising an absorber body consisting of an absorbent material and extending in its longitudinal extension substantially in the direction of flow.
Sound absorber members which can be used at high temperatures are above all needed for sound absorption in exhaust gas ducts of large combustion machines, in particular gas turbines in power stations or on test stands. Known sound absorber members which are used for these purposes have homogeneous fillings of glass or rock wool. Sound absorber members are also known whose absorber body consists of a layered structure of partition plates covered at one side with glass or rock wool, the plates extending with their covers in a direction transverse to the flow direction of the hot gas within a repeating layered structure of partition plate, mineral wool and air cavity. The constructional dimension of this layered structure is several decimeters in these so- called resonator sound absorber members.
Sound absorber members of this type have the disadvantage that after a short operating time the glass wool or rock wool oxidizes, becomes brittle and disintegrates because of its iron content at temperatures above 5000C and due to the simultaneous action of dynamic stress caused by gases flowing past the members. As a result of this and of the discharge of the decomposed or partly decomposed absorber material by the gas flow, these known absorber members become-inefficient after a short operating time.
2 It is the object of the present invention to provide a sound absorber member of the above-mentioned type which is better suited for use in hightemperature gas flows, in particular gas flows having temperatures above 5000C, than the known sound absorber members.
The sound absorber member for attaining this object is characterized in that the absorber body has a layered structure composed of layers of material that extend in a direction transverse to the flow direction and are alternately of an absorbent material exhibiting a high flow resistance and a low flow resistance, respectively.
With this embodiment of the invention, it is possible to produce sound absorber members which can be used at high temperatures, in particular above 5000C. On the one hand, a suitable average flow resistance which ensures the necessary attenuation/frequency characteristic can be achieved owing to the layered structure consisting of layers of absorbent materials alternately exhibiting a high flow resistance and a low flow resistance, respectively, and,' on the other hand, corresponding absorbent materials of a high or low flow resistance and adequate temperature resistance are now available. For instance, ceramic wool which is resistant to temperatures of up to about 10000C can be used as an absorbent material having a high flow resistance. This material, however, does not exhibit a flow resistance that would permit the exclusive use of this material as an absorbent material in the absorber body. A special-steel needle-punched nonwoven fabric which exhibits sufficient heat resistance up to 10000C can e.g. be used as an absorbent material with a low flow resistance. Advantageous developments of the invention become apparent from the subclaims.
The present invention shall now be explained and described in more detail with reference to an embodiment taken in 3 conjunction with the attached drawings which main] illustrate th-is embodiment and in which:
FIG. 1 i s a horizontal sectional view of an embodiment of a sound absorber member according to the invention; FIG. 2 is a vertical sectional view of an embodiment according to FIG. 1, taken along sectional line A-A of FIG. 1; and FIG. 3 is a diagram showing an attenuation/frequency characteristic of an assembly of sound absorber members according to the invention in comparison with attentuation/frequency characteristics of conventional members.
Reference numeral 1 in FIG. 1 designates a sound absorber member which comprises a surrounding sheet metal frame 2 with vertically and horizontally extending frame parts. Sheet metal frame 2 is covered with lateral covers 3 and 3' made from a plate having evenly arranged perforations 4. A box is formed by frame 2 and lateral covers 3 and 31 for receiving an absorber body 5 substantially filling the box. The absorber body has a layered structure consisting of layers of material extending in a direction perpendicular to the perforated plates 3 and 3f. This layered structure alternately includes layers 6 consisting of ceramic wool and layers 7 consisting of a needle-punched nonwoven fabric of special steel. Sound absorber member 1 is positioned within a gas flow outlined by arrows 8 and is arranged such that the different layers of the absorber body extend in a direction perpendicular to the flow direction.
In the present embodiment the flow resistance of the ceramic wool forming layers 6 is above 15 M x s /m4. and the density of the ceramic wool may here range between 30 4 and 150 kg per m3. The flow resistance of the special-steel needle- punched nonwoven fabric forming layers 7 is substantially smaller and below 1 kN x s / m4 in the present embodiment. Instead of a special-steel needlepunched nonwoven fabric, wire mesh or a filling of small ceramic balls could be used as the absorbent material for layers 7 whose flow resistance is to be smaller than the flow resistance of layers 6. The layer thickness of the layers is preferably between 5 and 100 mm and in particular between 10 and 50 mm.
In the present embodiment the longitudinal extension of the sound absorber members in the direction of the gas flow is 1200 mm. The length of the sound absorber members may be greater or smaller, depending on the desired attenuation effect. A range of from 300 to 5000 mm is preferred.
A plurality of sound absorber members as shown in FIGS. 1 and 2 are arranged in spaced-apart parallel relationship with each other for sound absorption, the width of the sound absorber members and the distance between the members being preferably within the range between 50 and 1000 mm.
The sound waves of the hot gases flowing past the members are absorbed by the layers consisting of absorbent material. The materials used for layers 6 and 7 are resistant to temperatures of up to about 10000C, so that the members can be used for sound absorption in correspondingly hot gas flows.
FIG. 3 shows the attentuation/frequency characteristic of an assembly of sound absorber members as illustrated in FIGS. 1 and 2, with the members being arranged in parallel with each other at a spacing of 267 mm, in comparison with the attenuation/frequency characteristics of corresponding assemblies of sound absorber members having a homogeneous absorber body of ceramic wool or rock wool. The curve drawn in broken line relates to the sound absorber member of the invention. The curve drawn in unbroken line relates to sound absorber members with a conventional rock wool filling which is not resistant to temperatures above 5000C, and the gate-like curve represents the sound attenuation of a homogeneous absorber body of ceramic wool, as used for forming layers 6.
As follows from FIG. 3Y the attenuation for the sound absorber arrangement comprising absorber bodies consisting solely of ceramic wool has only small values within the low frequency range. These values do not comply with the demands to be made on sound absorber members of this type. Although the absorber assembly comprising absorber bodies consisting solely of rock wool exhibits an adequate attenuation in the low frequency range, rock wool is not resistant to temperatures above 5000C, as already mentioned, so that the sound absorber members would become inefficient at these temperatures after a short operating time due to the decomposition of the rock wool and its discharge out of the members by the gas flow. In the low frequency range the assembly of sound absorber members of the invention exhibits an expecially high damping action; a resonance magnification which is effected by the layers with the low flow resistance according to the principle of the resonator sound absorber takes even place at about 250 Hz in the present embodiment. By contrast, both the ceramic wool and the special-steel needle-punched nonwoven fabric that can be used in the sound absorber members of the invention are resistant up to 10000C. The layered structure of the absorber body effects a suitable average flow resistance by which attentuation values are achievable in the lower frequency range that are at least as high as those achievable by means of sound absorber members with conventional absorber bodies that do not contain temperature-resistant rock wool.
6 In the illustrated embodiment, the layers which consist of ceramic wool and a special-steel needle-punched nonwoven fabric, respectively, and alternately exhibit different flow resistances have the same thickness. The layers may also have different thicknesses. In particular, a specific distribution of the thicknesses and densities of the individual layers is possible for suitably changing the attenuation/frequency characteristic within the layered structure, i.e. also in the direction of the gas flow. Moreover, the type of absorber material could also be variable in a suitable way for changing the attenuation/frequency characteristic. It would even be possible to provide a changing width of the layers within the 'Layered structure.
Instead of the above-described square configuration of the absorber members, the members might also be in the form of hollow cylinders which could be concentrically arranged relative to one another in an exhaust gas duct for the purpose of sound absorption.
7

Claims (28)

1. A sound absorber member for use in high-temperature gas flows, comprising an absorber body (1) consisting of an absorbent material and extending in its longitudinal extension substantially in the direction of flow, characterized in that said absorber body (1) has a layered structure composed of layers of material (6, 7) that extend in a direction transverse to the flow direction and are alternately of an absorbent material exhibiting a high flow resistance and a low flow resistance, respectively.
2. A sound absorber member according to claim 1, characterized in that at least two of said layers (6, 7) exhibiting a high flow resistance and/or a low flow resistance have different flow resistance values within the layered structure of an absorber body for obtaining a predetermined attenuation/frequency characteristic.
3. A sound absorber member according to claim 1 or 2, characterized in that at least two of said layers (6, 7) exhibiting a high flow resistance and/or low flow resistance have different thicknesses within said layered structure of an absorber body for obtaining a predetermined attenuation/frequency characteristic.
4. A sound absorber member according to any one of claims 1 to 3, characterized in that at least two of said layers (6, 7) exhibiting a high flow resistance and/or a low flow resistance have different densities within said layered structure of an absorber body for obtaining a predetermined attenuation/frequency characteristic.
8 -
5. A sound absorber member according to any one of claims 1 to 4, characterized in that at least two of said layers 16, 7) exhibiting a high flow resistance and/or a low flow resistance have different extensions within said layered structure of an absorber body for obtaining a predetermined attentuation/frequency characteristic.
6. A sound absorber member according to any one of claims to 5, characterized in that the kind of material of said layers (6, 7) exhibiting a high flow resistance and/or a low flow resistance is to be variable within said layered structure of an absorber body for changing said attentuation/frequency characteristic.
7. A sound absorber member according to claim 1, characterized in that one value or a plurality of values for flow resistance.. thickness, density, extension, and/or kind of material of said layers (6, 7) exhibiting a high flow resistance and/or a low flow resistance are constant within said layered structure of an absorber body.
8. A sound absorber member according to any one of claims 1 to 7, characterized in that the flow resistance value of said absorbent material with the high flow resistance is 4 above 15 kN x s / m
9. A sound absorber member according to claim 8, characterized in that the flow resistance value of said absorbent material with the high flow resistance is above 4 20 kN x s / m
10. A sound absorber member according to any one of claims 1 to 9, characterized in that the flow resistance value of said absorbent material with the low flow resistance is 4 below 1 kN x s / m - 9
11. A sound absorber member according to any one of claims 1 to 10, characterized in that the thickness of said layer consisting of an absorbent material with a high flow resistance and/or the thickness of said layer consisting of an absorbent material with a low flow resistance ranges between 5 and 100 mm.
12. A sound absorber member according to claim 11, characterized in that the thickness of said layer consisting of an absorbent material with a high flow resistance and/or the thickness of said layer consisting of an absorbent material with a low flow resistance ranges between 5 and 50 mm.
13. A sound absorber member according to any one of claims 1 to 12, characterized in that said absorbent material exhibiting a high flow resistance has a density of from 30 3 Lo 150 kg per m
14. A sound absorber member according to claim 13, characterized in that said absorbent material exhibiting a high flow resistance has a density of from 50 to 150 kg per 3 m
15. A sound absorber member according to any one of claims 1 to 14, characterized in that the extension of said layers in a direction transverse to said flow direction is between 50 and 1000 mm.
16. A sound absorber member according to claim 15, characterized in that the extension of said layers in a direction transverse to said flow direction is about 400 min.
17. A sound absorber member according to any one of claims 1 to 16, characterized in that said absorbent material exhibiting a high flow resistance includes ceramic wool.
18. A sound absorber member according to any one oi- claims l to 17, characterized in that said absorbent material exhibiting said low flow resistance is a special-steel needle-punched nonwoven fabric.
19. A sound absorber member according to any one of claims 1 to 18, characterized in that said absorbent material exhibiting said low flow resistance is wire mesh.
20. 1% sound absorber member according to any one of claims 1 to 19, characterized in that said absorbent material exhibiting said low flow resistance is a ceramic ball filling.
21. A sound absorber member according to any one of claims 1 to 20, characterized in that the extension of said absorber body in flow direction ranges between 300 and 5000 MM.
22. A sound absorber member according to claim 21, characterized in that the extension of said absorber body in flow direction ranges between 300 and 2000 mm.
23. A sound absorber member according to claim 21, characterized in that the longitudinal extension of said absorber body is at about 1200 mm.
24. A sound absorber member according to any of claims 1 to 23, characterized in that said sound absorber member is arranged at a spacing of from 50 to 1000 mm within a parallel assembly consisting of a plurality of said sound absorber members.
25. A sound absorber member according to claim 24, characterized in that said sound absorber member is arranged at a spacing of from 50 to 500 mm, within a k 11 parallel assembly consisting of a plurality of said sound absorber members.
26. A sound absorber member according to claim 24, characterized in that said sound absorber member is arranged at a spacing of about 250 mm within a parallel assembly consisting of a plurality of said' sound absorber members.
27. A sound absorber member according to any one of claims 1 to 26, characterized in that said absorber member includes a frame comprising lateral covers made from a perforated plate for the reception of said absorber body.
28. A sound absorber member substantially as herein described with reference to the accompanying drawings.
GB9214863A 1991-08-19 1992-07-13 Sound absorber member for use at high temperatures Expired - Fee Related GB2258841B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE4127401A DE4127401A1 (en) 1991-08-19 1991-08-19 MUFFLER BACKGROUND FOR USE AT HIGH TEMPERATURES

Publications (3)

Publication Number Publication Date
GB9214863D0 GB9214863D0 (en) 1992-08-26
GB2258841A true GB2258841A (en) 1993-02-24
GB2258841B GB2258841B (en) 1995-08-16

Family

ID=6438617

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9214863A Expired - Fee Related GB2258841B (en) 1991-08-19 1992-07-13 Sound absorber member for use at high temperatures

Country Status (2)

Country Link
DE (1) DE4127401A1 (en)
GB (1) GB2258841B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2951495A1 (en) * 2009-10-20 2011-04-22 Faurecia Sys Echappement Exhaust volume i.e. exhaust silencer, for reducing acoustic emissions from exhaust line of internal combustion engine of motor vehicle, has wall with porous material whose air passage resistance has specific Newton-second per cubic meter

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19600040A1 (en) * 1996-01-02 1997-07-03 Gruenzweig & Hartmann Muffler element, especially for a backdrop silencer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2951495A1 (en) * 2009-10-20 2011-04-22 Faurecia Sys Echappement Exhaust volume i.e. exhaust silencer, for reducing acoustic emissions from exhaust line of internal combustion engine of motor vehicle, has wall with porous material whose air passage resistance has specific Newton-second per cubic meter

Also Published As

Publication number Publication date
DE4127401A1 (en) 1993-02-25
GB9214863D0 (en) 1992-08-26
GB2258841B (en) 1995-08-16

Similar Documents

Publication Publication Date Title
JP3463934B2 (en) Porous metal fiber plate
US20060124387A1 (en) Soundproof thermal shield
GB1490923A (en) Sound-absorbing structures
AU674369B2 (en) Porous sintered laminate containing metal fibers
EP0876539B1 (en) Soundabsorbing element and procedure for manufacture of this element and use of this element
WO1980002304A1 (en) Packless silencer
US2989136A (en) Sound attenuation
DE2534556B2 (en) Silencers for gas flows
CA2634192A1 (en) Woven laminate as a covering for sound absorption of input and output sound absorbers and method for producing an acoustic isolation unit
US2674336A (en) Acoustical panel
JPH0245461Y2 (en)
SE450656B (en) Muffler for ventilation ducts or ventilation equipment
GB2258841A (en) Sound absorber member for use at high temperatures
EP1382031B1 (en) Silencer
US3181646A (en) Silencer having contiguous concentric layers of sound absorbent material
US3709319A (en) Resonator chamber silencer for gas turbine
DE2244123A1 (en) GAS TURBINE SILENCER AND BRACKET
EP1954919B1 (en) Device for absorbing sound in power plants
DE2437947A1 (en) ARRANGEMENT FOR ABSORPTION OF AIR SOUND
US11549414B1 (en) Sound attenuator apparatus and method
RU61353U1 (en) SOUND ABSORBING CONSTRUCTION WITH PERFORATED FILLER IN THE FORM OF FOLDED STRUCTURE
EP1589200B1 (en) Heat and sound insulating element
DE3322204A1 (en) Sound absorber for gaseous media
DE19834136C1 (en) Exhaust gas conduit for internal combustion engine has double wall formed between outer tube and inner tube, inner tube being of metallic material with high porosity
EP4311892A1 (en) A damping and sound-absorbing plate made of fiber material and an acoustic silencer made of this plate

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19990713