JPH06504631A - noise damping panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] noise damping panel The present invention relates to noise attenuating panels, particularly, but not exclusively, to aircraft Noise attenuation panel for use in attenuating engine noise.

In Patent Application Publication No. GB-A-2223448, a back surface component and a surface component are and a cellular component having a plurality of juxtaposed cells with open ends. A noise attenuating panel is disclosed, wherein the backside component includes a cell of the cellular component. extending across the end on its back side, the surface feature comprising a cellular feature; It extends across the edge of the material cell on its front side.

In one embodiment of the invention described in GB-A-2,223448 , the cellular component comprises a single cellular element having walls, the walls being extending across the element from its front surface to its back surface, the walls of which are cellular components for an array of juxtaposed cells with open ends extending from the front side of the provides a boundary surface.

In another embodiment of the invention described in GB-A-2223448 The cellular component has a front cellular element and a back side located on the back side of the front cellular element. It is divided into cellular elements, with a partition element extending between the two cellular elements.

Each cellular element extends across the element from its front side to its back side and Boundary for an array of juxtaposed cells with open ends extending from the front to the back of the element It has a wall portion that provides a surface.

In the panel disclosed in GB-A-2223448, preferred Porous, permeable thermoplastics produced by powder sintering of thermoplastics surface component for a panel comprising or including an external surface sheet of a synthetic material; material is used. As proposed in GB-A-2223448 The external face sheet manufactured by The density of the cells is then increased by the cellular components on the back side of the top sheet. G such that it is sufficiently transparent for the transmission of sound energy to be absorbed by the As disclosed in No. B-A-2223448 and described with the outer face sheet. In particular, panels formed in e) a surface that receives the passage of a gas flow across it as an inlet air flow across the internal surface of the It has been used successfully in aircraft engine environments in locations that provide I've been exposed to it. However, it is particularly important for complex structures with single or double curvature. The production of panels with different shapes requires the use of complex and costly manufacturing techniques. One object of the present invention is that it can be manufactured easily and inexpensively and, if desired, Noise attenuation according to rough geometries, especially suitable for use in aircraft engine environments The purpose is to provide panels.

According to a first aspect of the invention, a cellular component having an open cell structure and a damping member are provided. In a noise attenuating panel with a front surface exposed to sound to be , including a front surface in which a cell structure is adapted for the passage of a gas flow across this front surface. Normal ingress of liquid into the component through this front surface, providing low resistance mutual having a predetermined first size and a predetermined first density effective to prevent a front area that provides communication cells; The structure has a predetermined second size and a predetermined second density effective for absorbing sound energy. a base region providing interconnecting cells with A damping panel is provided.

An "open cell structure" is formed by agglomeration of particulate matter or by the formation of a body of material in the liquid phase. by displacing the substance by dispersion or similar techniques and then subjecting it to a solidification step. refers to a cellular structure having a large number of interconnected cells obtained by

In one embodiment of the invention described below, the cells in the front region of the cellular component are The shaped structure is obtained by agglomeration of particulate matter and has a predetermined first size and a predetermined first size. a cellular structure in the base region of the cellular component; The process involves displacing a substance from the body of the substance in a liquid phase by dispersion or similar techniques and then obtained by subjecting it to the solidification step, and has a predetermined second size and a predetermined second density. Provides a large number of interconnecting cells at one time.

In one embodiment of the invention described and illustrated below, the front region is made of thermoplastic material. Made from a porous and permeable thermoplastic material produced by powder sintering. provided by a surface cellular component comprising or including an external surface sheet that is The base region of the cellular component is an open cell rigid or flexible plastic film. It is provided from a base material formed from ohms.

One embodiment of the invention, described below but not shown, includes surface cellular The component has an inner surface sheet that is porous and provides structural support for the outer surface sheet. Including root. The inner facing sheet is formed by openings between adjacent warp and weft threads of the fabric. Manufactured from open square weave fabric woven to give openings configured It is preferable. This fabric has a ratio of open aperture area to total surface area of the sheet is preferably about 30% or substantially 30%.

In an alternative embodiment of the invention described below, cellular HIIIi, a member of The cellular structure of the front and base regions provides dispersion from the main body of material in the liquid phase. persion) or similar techniques and then subjected to a solidification step. and a predetermined first size and a predetermined first size in the front region. density and having a predetermined second size and a predetermined second density in the base region. Provides a certain number of interconnected cells. The components may be open cell rigid or flexible plastics. Preferably, it is formed from plastic foam.

In further embodiments of the invention described below, the front surface and The cellular structure in the front and basal regions is obtained by agglomeration of particulate matter, and the cellular structure in the front region is has a predetermined first size and a predetermined first density in the base region. a plurality of interconnecting cells of a predetermined second size and a predetermined second density;

The components are porous and permeable fabricated by powder sintering of thermoplastics. Preferably, it is made from a thermoplastic material.

In the embodiments of the invention described below, the back surface component is the back surface of the cellular component. fixed to the surface. It is non-porous and consists of a non-porous and non-permeable material.

According to a second aspect of the invention, a surface receiving the passage of a gas flow across it; forming said surface or a part of said surface whose front surface receives the passage of a gas flow across it; a noise attenuating panel according to the first aspect of the invention, positioned to An aircraft engine is provided.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings. diagram in drawing 1 is a schematic isometric top view of a noise attenuation panel according to a first embodiment of the present invention. and Figure 2 shows the panel shown in Figure 1 secured to a support channel member. FIG. 3 is a schematic cross-sectional view in the end region of the FIG. 3 is a schematic cross-sectional view of a noise attenuation panel according to a second embodiment of the present invention. 4 is a schematic cross-section of an aircraft engine embodying a noise attenuating panel according to the invention It is a diagram.

Referring first to FIGS. 1 and 2, the noise attenuating panel 10 includes a backsheet 11 and a It includes a cellular component 12 and a topsheet 14.

As shown in FIG. It is fixed with a fat adhesive E1. Surface Sea H4 is the ability to bond materials together is fixed to the upper surface of the cellular component I2. However, if desired, use adhesive. Use T Kotoda Saru. Epoxy combination agent E1 is available from UK Gu/Bridge, for example. Bar Geigy Plastics and Additives Company Limited (Ci) ba-Geigy Plastics & Additives Coa+pa (Limited).

However, the adhesive and resin need not be epoxy resin adhesives, but e.g. For example, it can be a phenol, a polyimide or a thermoplastic.

The surface/surface 14 is a porous material produced by powder sintering of a thermoplastic material. with a sheet of permeable thermoplastic material. Examples of suitable thermoplastics include po rietherketone, polyetheretherketone, polyaromatic ketone, polyphene Nylene sulfide, polyamide-imide, thermoplastic poly Includes imides, polyether-imides, polyurethanes and polyethylenes.

Cellular component I2 can be manufactured from any suitable thermoplastic material. open-cell plastic foam tics foam> shape. An example of a suitable thermoplastic is polyether Ketone, polyetheretherketone, polyaromatic ketone, polyphenylene sulfate fido, polyamide-imide, thermoplastic polyimide, polyether-imide, polyamide Includes urethane and polyethylene. That is, the top sheet 14 is formed. 2 can be advantageously formed from the same thermoplastic material.

The back sheet) 11 is non-porous and made of a non-porous and non-permeable material, Can be manufactured from any of the materials listed below.

(i) For example, if the thermoplastic is a polyetheretherketone, carbon Composite of element/thermoplastic substance. This material is automatically tape wrapped. (wound) or semi-molded (hand 1 aid).

(ii) Carbon/epoxy resin.

(ii) Aluminum alloy.

Panel 10 is of arcuate form, possibly with double curvature, and As a structural component for the duct of the nose cowl of an aircraft engine. The panel lO will be placed immediately upstream of the engine fan. This is one of the few bow-shaped panels. Of course, the panel will not deteriorate during use, especially It is extremely important that no part of it become detached from its supporting structure. be.

This structure usually includes support 'i:' and groove members (a), of which only one member; is shown in x2. The surface sheet 14 is connected to the groove member 1 using carbon-carbon bonds 19. 7 to the outer surface of the flange 18 of the The panel is removed by joining the groove 11 to the outer surface of the flange 20 of the groove member I7. The lever 10 is fixed to the member J7. between the panel IO and the base 22 of the groove member 17. The gap can be sealed or sealed using mastic 23.

An external surface system made of porous thermoplastic material as described with reference to Figures 1 and 2. The panel with 14 points has several advantages over conventionally proposed panels, including: It has been found that it gives rise to advantages.

(1) The cellular structure of the top sheet when manufactured by powder sintering technology can be used in a wide range of can be manufactured to meet permeability requirements across the environment. This cellular structure The construction spans a wide range of tightly controlled flow and resistance requirements that are engine dependent. Permeable to gas flow and impermeable to a wide range of liquid and solid contaminants can be manufactured to be, (2) The cellular structure of the topsheet when produced by powder sintering technology is very Provides a complex interference flow path and, as a result, the noise attenuation properties are improved by the porosity (ρerfor (3) powder sintering techniques, which are greatly enhanced over other forms of porous materials. The very smooth surface of the topsheet when manufactured by more substantial acoustic/air flow than porous and porous forms.

W) has jl1 point. There is a lower flow resistance to high velocity airflow and therefore , overall aircraft engine power plant efficiency is an improvement over that obtained using previously proposed panels, (4 ) Sound attenuation is greater than previously proposed panels, covering a wider frequency range. There is, (5) Thermoplastic components are subject to metal galvanic corrosion (n+metal galvanic corrosion). There is no problem of corrosion. (6) The panel is lighter than previously proposed panels; (7) Previously proposed structure Compared to the improved [blade-on] J Energy - absorption, and (8) improved appearance.

Furthermore, the panel described with reference to Figures and 2 has the following additional advantages: .

(1,) Cellular configuration #12 provides a well-distributed dissipation of sound energy. Provides a continuous layer of interconnecting cells, smoothing the glue actance as a function of frequency back cavity resonance that increases high frequency absorption ce) is attenuated.

(2) At low absorption frequencies, the cellular matrix produced by component 12 The sound velocity within the box is reduced, giving a greater apparent processing depth and absorbing low frequencies. increase. Furthermore, these inherently point-reactive arguments point reactinggargument), the axis and circumference within the material Directional wave movement can also be used to advantage.

(3) The use of surface sheets manufactured by powder sintering of thermoplastic materials is , which would normally destroy the acoustics of the panel and pose safety issues. micro-porous (m1cro-porous) which prevents normal ingress of liquids Ensure formation of topsheet.

(4) Thermoplastic foam (foai+) component 12 to provide structural strength while retaining the desired properties that characterize it. can do.

The topsheet 14 is described as being formed by powder sintering of a thermoplastic material. . However, it offers low resistance to gas flow across it and normal invasion of liquids. The required porous and permeable properties of the anti-fouling sheet can be achieved by techniques other than sintering. If they are considered more suitable, e.g. For example, wax model method (lost wax), salt pattern method (lost 5alt) Or manufactured by the starch prototype method (lost 5 tarch) technology. It will be understood that this is possible.

Referring to FIG. 3, panel 110 has a backsheet 111 and an open cell cellular configuration. A second embodiment of the invention is shown comprising a member 112. Back sheet 11 1 has the same shape as the back sheet of the panel 10 illustrated in FIGS. 1 and 2; It is joined in the same way to the cellular component 112 by adhesive E1.

The cellular component 112 is in the form of an open cell plastic foam and is shown in FIG. and 2 for the cellular component 12 in the embodiment of the invention described with reference to It can be manufactured by any of the thermoplastics proposed in . it is Additionally, the cell structure includes a front surface 141 in which the cell structure allows airflow to flow across the surface 141. Provides low resistance to overflow and is effective in preventing normal ingress of liquids a front region 140 that provides cells of a suitable size and density; Therefore, the cell structure has an effective size and density for absorbing sound energy. The base region 120 is manufactured in such a manner as to provide a base region 120 that provides a cell of 100 to 100 cm.

Cellular component 12 or in the embodiment of the invention described with reference to FIGS. Alternatively, the cellular component 112 of FIG. 3 may be made of plastic foam with an open cell structure. It can be manufactured by any technique well known for construction. example For example, the foam can be prepared by mixing a pore-forming material with a thermoplastic polymer and a solvent; and pore-forming material to interconnect each other at the contact points between the individual cells. can be manufactured to leave a system of cells that

In the embodiment of the invention illustrated in FIGS. 1 and 2, the front area comprises the topsheet 1 It is provided by a surface cellular component in the shape of 4. Alternative Embodiments of the Invention (Illustrated) (without), the surface cellular component has an external surface shell of the same shape as the sheet 14. an inner surface that is porous and provides structural support for the outer surface sheet. A face sheet can be provided. The inner surface sheet is made of carbon fiber/resin matrix. open 5 square weave line made from composite material of This method of weaving can be made from woven fabric. an opening formed by an opening between adjacent warp and weft threads of (aperture). This fabric covers the entire surface of the sheet. such that the ratio of open aperture area to area is 30% or substantially 30%; Preferably, it is woven.

In yet another embodiment of the invention, the embodiment described with reference to FIG. The cellular component 112 is in the form of an open cell plastic foam. However, a cellular structure for the front and base regions obtained by agglomeration of particulate matter is replaced by a cellular component having . This component includes the front surface 141 including a cell structure therein having a low resistance to the passage of gas flow across the surface 141. effective size and density to provide stability and prevent normal ingress of liquids a front area 140 providing cells for sound absorption; A base region below the front region 140 that provides cells with an effective size and density. 120. This component is made of powdered thermoplastic material. Manufactured from a porous, permeable thermoplastic material produced by pre-sintering Preferably, the thermoplastic material employed is as described with reference to Figures 1 and 2. The use as a thermoplastic material to form the top sheet 14 of the embodiment of the present invention is as follows. It includes any of those proposed in .

Cellular component 112 is manufactured by powder sintering a thermoplastic. If manufactured from a porous, permeable thermoplastic material, the front region 140 may be The panel has the same cellular structure shape as that of the topsheet 14 in 1 and 2; Above with respect to the panel with the topsheet 14 described with reference to FIGS. 1 and 2. It has all the advantages described above.

Referring to FIG. 4, an aircraft engine 25 is schematically illustrated, from Byron 32. Turbofan mounted in a suspended nacelle 27 A power unit 26 is provided. Nacelle 27 has an outer wall 29 and an inner wall 30. It is equipped with a tip ventilation cap 28. The interior wall 30 is described and illustrated with reference to FIGS. Partly shaped by a noise damping panel P which can take the shape of the panel shown. will be accomplished. The panel P forms part of the inner wall of the tip vent cap 28 and is a part of the unit 26. In addition to reducing the noise generated by the fan blades, the to reduce noise generated by the high velocity flow of air passing through the power unit 26. Arranged to work a little.

The panel in Figure 4 is empty due to the reduction in air velocity due to the passage of air through the panel. Attenuation of sound waves in contrast, however, is employed to reduce noise is achieved without affecting the velocity of the air producing the noise, i.e. It should be emphasized that air does not pass through the noise damping panel P.

In the aircraft engine mounting arrangement illustrated in Figure 4, the power unit is wing-mounted. Carried by Byron 32. However, noise attenuation according to the present invention Panels are similarly employed to reduce noise in other aircraft engine equipment It will be understood that this can be done.

July 22, 1993

Claims (16)

[Claims] 1. A cellular component with an open cell structure and before being exposed to the sound to be attenuated. a noise attenuating panel comprising a front surface, wherein the component includes the front surface; wherein the cell structure provides low resistance to passage of gas flow across the front surface. and prevent normal ingress of liquid into said component passing through said front face. an interconnecting cell having a predetermined first size and a predetermined first density effective to a front area below said front area and in which said cell structure is provided; The structure has a predetermined second size and a predetermined second density effective for absorbing sound energy. and a base region providing interconnecting cells. Nell. 2. The cellular structure of the front region of the cellular component is configured to prevent agglomeration of particulate matter. a plurality of interconnected objects of said predetermined first size and predetermined first density; A panel according to claim 1, characterized in that it provides a through cell. 3. The cellular structure of the base region of the cellular component is capable of absorbing substances in a liquid phase. Substances are replaced from the main body by dispersion or similar techniques and then subjected to a solidification process. a large number of the predetermined second size and the predetermined second density. 3. A panel according to claim 2, characterized in that it provides interconnecting cells. 4. The front region is porous and manufactured by powder sintering a thermoplastic material. comprising or including an outer surface sheet made of a transparent and permeable thermoplastic material; provided by a surface cellular component, the base region of the cellular component being open; Base component formed from free-cell rigid or flexible plastic foam 4. A panel according to claim 3, characterized in that the panel is provided by: 5. the surface cellular component is porous and has a structure for the external surface sheet; 5. The panel of claim 4, further comprising an inner face sheet providing physical support. . 6. the inner surface sheet is constituted by openings between adjacent warp and weft yarns of the fabric; Manufactured from open square weave fabric woven to provide openings for The panel according to claim 5, characterized in that: 7. The fabric has a ratio of open openings to the total surface area of the sheet of 30% or more. 7. The fabric according to claim 6, wherein the fabric is woven so that the amount of Nell. 8. The cellular structure of the front and base regions of the cellular component is in a liquid phase. Substances are replaced by dispersion or similar techniques from the main body of the substance in the solid state chemical process. the predetermined first size in the front region; and a predetermined first density and a predetermined second density in the base region. characterized by providing a large number of interconnecting cells of a certain size and a predetermined second density. The panel according to claim 1. 9. The component is formed from open cell rigid or flexible plastic foam. 9. The panel according to claim 8, characterized in that the panel is made of: 10. The cellular structure of the front surface and base region of the cellular component has a particulate structure. obtained by agglomeration of the substance, in the front region the predetermined first size and and a predetermined first density and a predetermined second size in the base region. and a predetermined second density of interconnecting cells. Panel according to claim 1. 11. The component is manufactured by powder sintering a thermoplastic material. 11. The material according to claim 10, characterized in that it is manufactured from a porous and permeable thermoplastic material. panel. 12. A back surface component is provided on the back surface of the base region of the cellular component. 12. A panel according to any one of claims 1 to 11, characterized in that it is fixed. 13. The backing sheet is non-porous and consists of a non-porous, non-permeable material. 13. The panel of claim 12, characterized in that: 14. a surface that receives the passage of a gas flow across it and whose front surface receives the gas flow across it positioned to form said surface or a part of said surface through which flow passes; and the noise attenuation panel according to any one of claims 1 to 13. An aircraft engine featuring: 15. Substantially as described above with reference to FIGS. 1 and 2 or 3 of the accompanying drawings. Noise attenuating panel characterized in that it is similar in nature. 16. The accompanying drawings are substantially similar to those described above with reference to FIG. An aircraft engine characterized by: