# US 9,038,774 B2 · Thermal-acoustic sections for an aircraft

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- Number: US 9,038,774 B2
- Document ID: US9038774B2
- Status: Granted
- Kind: B2
- Application number: 14/096,833
- Filed: 2013-12-04
- Published: 2014-08-07
- Granted: 2015-05-26
- Earliest claimed: 2011-12-08
- Assignees: Gulfstream Aerospace Corporation
- Applicants: Gulfstream Aerospace Corporation
- Inventors: Tongan Wang; John Maxon; Andrew Foose; David Charles Hornick; Josef Fila
- Web page: https://patentgrep.com/patent/US9038774B2

## CPC

- B64C 1/40: Sound or heat insulation {, e.g. using insulation blankets}
- B29C 65/00: Joining {or sealing} of preformed parts {, e.g. welding of plastics materials}; Apparatus therefor {(general aspects of processes or apparatus for joining preformed parts B29C66/00; using porous material formed by internal pressure generated therein for joining preformed parts B29C44/1228, B29C44/326)}
- B29C 66/11: {Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section (B29C66/12 and subgroups take precedence)}
- B29C 66/1122: {Single lap to lap joints, i.e. overlap joints (B29C66/45, B29C66/472, B29C66/52272 take precedence)}
- B29C 66/1142: {Single butt to butt joints}
- B29C 66/43: {Joining a relatively small portion of the surface of said articles (B29C66/45 takes precedence)}
- B32B 3/12: characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
- B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)}
- B32B 5/32: {at least two} layers being foamed {and next to each other}
- B32B 7/02: Physical, chemical or physicochemical properties
- B64C 1/00: Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
- E04B 1/82: specifically with respect to sound only ({of floors or ceilings E04B9/001;} noise damping in ducts or channels E04F17/00; noise damping in general G10K11/16)
- E04B 1/84: Sound-absorbing elements
- G10K 11/00: Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K 11/02: Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
- B29K 2105/04: cellular or porous
- B32B 2250/02: 2 layers
- B32B 2250/03: 3 layers
- B32B 2250/04: 4 layers
- B32B 2250/05: 5 or more layers
- B32B 2250/20: All layers being fibrous or filamentary
- B32B 2250/22: All layers being foamed
- B32B 2266/0257: Polyamide
- B32B 2266/0285: Condensation resins of aldehydes, e.g. with phenols, ureas, melamines
- B32B 2266/06: Open cell foam
- B32B 2307/102: Insulating
- B32B 2307/718: Weight, e.g. weight per square meter
- B32B 2605/18: Aircraft
- Y02T 50/40: Weight reduction
- Y10T 428/24149: Honeycomb-like
- B64C: AEROPLANES; HELICOPTERS
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- E04B: GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS (border constructions of opening in walls, floors or ceilings E06B1/00; {electromagnetic shielding H05K9/0001})
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Embodiments of thermal-acoustic sections for an aircraft for reducing noise along an acoustic path produced from an acoustic source are provided herein. The thermal-acoustic section comprises a first porous layer having a first characteristic acoustic impedance. A second porous layer is disposed adjacent to the first porous layer and has a second characteristic acoustic impedance that is greater than the first characteristic acoustic impedance. The thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise from the acoustic source is directed through the first porous layer to the second porous layer to promote absorption of the noise.

## Claims

### Claim 1

A thermal-acoustic section for an aircraft for reducing noise along an acoustic path produced from an acoustic source, the thermal-acoustic section comprising:
a plurality of juxtaposed porous layers forming a thermal-acoustic stack that has a first outermost portion, a second outermost portion, and a central portion that is disposed between the first and second outermost portions, wherein the thermal-acoustic stack is configured to be positioned along the acoustic path such that the noise from the acoustic source is incident to the first outermost portion, and wherein the first outermost portion has a first relatively high characteristic acoustic impedance that is effective to reflect a substantial portion of the noise away from the thermal-acoustic stack and to allow a transmitted portion of the noise to enter the thermal-acoustic stack, and wherein the thermal-acoustic stack has a gradually decreasing characteristic acoustic impedance from the first outermost portion to the central portion and a gradually increasing characteristic acoustic impedance from the central portion to the second outermost portion to promote transmission loss of the transmitted portion of the noise through the thermal-acoustic stack.

### Claim 2 (depends on 1)

The thermal-acoustic section of claim 1, wherein the plurality of juxtaposed porous layers include a first porous layer disposed along the first outermost portion, a second porous layer disposed along the second outermost portion, and a third porous layer disposed along the central portion, and wherein the first porous layer has a first characteristic acoustic impedance, the second porous layer has a second characteristic acoustic impedance, and the third porous layer has a third characteristic acoustic impedance that is less than the first and second characteristic acoustic impedance.

### Claim 3 (depends on 2)

The thermal-acoustic section of claim 2, wherein the first porous layer is in a first compressed condition at a first percent compression such that the first porous layer has a first acoustic absorption coefficient that is about 95% or greater of a first maximum acoustic absorption value for the first porous layer over a first predetermined frequency range, the second porous layer is in a second compressed condition at a second percent compression such that the second porous layer has a second acoustic absorption coefficient that is about 95% or greater of a second maximum acoustic absorption value for the second porous layer over a second predetermined frequency range, and/or the third porous layer is in a third compressed condition at a third percent compression such that the third porous layer has a third acoustic absorption coefficient that is about 95% or greater of a third maximum acoustic absorption value for the third porous layer over a third predetermined frequency range.

### Claim 4 (depends on 2)

The thermal-acoustic section of claim 2, wherein the first porous layer has a first aerial weight, the second porous layer has a second aerial weight greater than the first aerial weight, and the third porous layer has a third aerial weight that is less than the second aerial weight.

### Claim 5 (depends on 2)

The thermal-acoustic section of claim 2, wherein the first and second porous layers have a porosity of about 85 vol. % or greater.

### Claim 6 (depends on 2)

The thermal-acoustic section of claim 2, wherein the first and second porous layers each comprise a material selected from the group consisting of open-cell foam, felt, fibers, fibers bonded with resin, and combinations thereof.

### Claim 7 (depends on 1)

The thermal-acoustic section of claim 1, wherein the first relatively high characteristic acoustic impedance is about 250,000 Pa·s/m or greater.

### Claim 8 (depends on 1)

The thermal-acoustic section of claim 1, wherein the first relatively high characteristic acoustic impedance is about 350,000 Pa·s/m or greater.

### Claim 9 (depends on 1)

The thermal-acoustic section of claim 1, wherein the first relatively high characteristic acoustic impedance is about 500,000 Pa·s/m or greater.

### Claim 10 (depends on 1)

The thermal-acoustic section of claim 1, wherein the second outermost portion has a second relatively high characteristic acoustic impedance that is effective to reflect at least a portion of the transmitted portion of the noise back through the thermal-acoustic stack.

### Claim 11 (depends on 10)

The thermal-acoustic section of claim 10, wherein the second relatively high characteristic acoustic impedance is about 250,000 Pa·s/m or greater.

### Claim 12 (depends on 10)

The thermal-acoustic section of claim 10, wherein the second relatively high characteristic acoustic impedance is about 350,000 Pa·s/m or greater.

### Claim 13 (depends on 10)

The thermal-acoustic section of claim 10, wherein the second relatively high characteristic acoustic impedance is about 500,000 Pa·s/m or greater.

### Claim 14 (depends on 1)

The thermal-acoustic section of claim 1, further comprising:
a first outer structure; and
a second outer structure, wherein the thermal-acoustic stack is interposed between the first and second outer structures such that the first outer structure is disposed adjacent to the first outermost portion and the second outer structure is disposed adjacent to the second outermost portion, and wherein the first outer structure is a fuselage or a panel attached to the fuselage, and the second outer structure is a closeout panel, a dado panel, a headliner, an acoustic layer, or an interior cabin panel.

### Claim 15

A thermal-acoustic section for an aircraft for reducing noise along an acoustic path produced from an acoustic source, the thermal-acoustic section comprising:
a first porous layer; and
a second porous layer disposed adjacent to the first porous layer, wherein the first porous layer is in a first compressed condition at a first percent compression such that the first porous layer has a first acoustic absorption coefficient that is about 95% or greater of a first maximum acoustic absorption value for the first porous layer over a first predetermined frequency range and/or the second porous layer is in a second compressed condition at a second percent compression such that the second porous layer has a second acoustic absorption coefficient that is about 95% or greater of a second maximum acoustic absorption value for the second porous layer over a second predetermined frequency range, and wherein the thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise is directed through the first porous layer to the second porous layer to promote absorption of the noise.