초록 ▼

Acoustic liners for aircraft noise reduction include one or more chambers that are configured to provide a pressure-release surface such that the engine noise generation process is inhibited and/or absorb sound by converting the sound into heat energy. The size and shape of the chambers can be selec

Acoustic liners for aircraft noise reduction include one or more chambers that are configured to provide a pressure-release surface such that the engine noise generation process is inhibited and/or absorb sound by converting the sound into heat energy. The size and shape of the chambers can be selected to inhibit the noise generation process and/or absorb sound at selected frequencies.

대표청구항 ▼

1. An aircraft comprising: a fuselage defining outwardly-facing surfaces and lift-generating wings extending outwardly in generally opposite directions away from the fuselage and defining outer wing surfaces;at least one engine having a thrust-generating element, and wherein the aircraft includes a

1. An aircraft comprising: a fuselage defining outwardly-facing surfaces and lift-generating wings extending outwardly in generally opposite directions away from the fuselage and defining outer wing surfaces;at least one engine having a thrust-generating element, and wherein the aircraft includes a source of noise that produces noise during operation of the aircraft;a noise absorbing acoustic liner disposed on the outer surfaces of the fuselage and the wings, and having a depth dimension, the noise absorbing liner including: a porous outer surface that permits a portion of noise incident on the porous surface to pass therethrough, wherein the depth dimension extends between the porous outer surface and the portion of the outer surfaces of the fuselage or wings on which the acoustic liner is disposed; anda plurality of internal chambers of different lengths interconnected by internal passageways to permit sound to travel between the internal chambers,wherein each of the plurality of internal chamber has an opening; connected to the porous outer surface,wherein each of the plurality of internal chambers, receives sound through the porous outer surface, and has a first internal surfaces defining the internal chamber,wherein each of the plurality of internal chambers includes a first portion that extends into the depth dimension of the acoustic liner away from the porous outer surface to a depth that is greater than the dimension of the opening,wherein each of the plurality of internal chambers converts a first portion of the sound that enters the internal chambers through the porous outer surface into heat energy, and transmits sound that has not been converted into the heat energy out of the internal chambers through the porous surface, andwherein each of the plurality of internal chambers contains an acoustic filler material that absorbs a second portion of the sound that enters the internal chamber. 2. The aircraft of claim 1, wherein: the internal chambers comprise first and second chambers each having respective first and second opposite ends and respective first and second openings, and wherein at least one of the first and second opposite ends of the first and second chambers is connected to the porous surface through the respective first and second openings. 3. The aircraft of claim 2, wherein: the porous surface includes first and second portions that are directly adjacent one another, and wherein the opening of the first chamber is connected to the first portion of the porous surface, and wherein the opening of the second chamber is connected to the second portion of the porous surface. 4. The aircraft of claim 3, wherein the internal chambers are each separated by a respective partition such that sound is not transmitted from the first chamber to the second chamber through the partition other than through the internal passageways, and such that sound is not transmitted from the second chamber to the first chamber through the partition other than through the internal passageways. 5. The aircraft of claim 4, wherein: sound exits the first and second chambers through the respective openings of the first and second chambers at the porous surface. 6. The aircraft of claim 1, wherein: the internal chambers of the liner includes first and second chambers, a substantial portion of the first chamber is filled with a first acoustic filler material having a first composition, and a substantial portion of the second chamber is filled with a second acoustic filler material having a second composition that is significantly different than the first composition. 7. The aircraft of claim 1, wherein: the porous surface comprises a sheet of material defining a plurality of openings therethrough. 8. The aircraft of claim 1, wherein: the internal chambers of the liner include first and second chambers that are separated by a partition such that sound is not transmitted from the first chamber to the second chamber through the partition other than through the internal passageways, and such that sound is not transmitted from the second chamber to the first chamber through the partition other than through the internal passageways. 9. The aircraft of claim 1, wherein: the internal chambers have a quadrilateral shape in cross section, a length dimension extending into the depth dimension of the acoustic liner, and a width dimension extending transverse to the length dimension, wherein the length dimension is greater than the width dimension. 10. The aircraft of claim 1, wherein: the porous surface is approximately planar; and wherein:each of the internal chambers defines an outer portion that extends into the depth dimension of the acoustic liner and transverse relative to the porous surface, and an inner portion that extends generally parallel to the porous surface. 11. A method of reducing noise in an aircraft having an outer surface that does not form part of an engine nacelle, the method comprising: determining a region on the outer surface that is exposed to a significant amount of noise generated by the aircraft in operation;determining a spectral profile of the noise that is incident on the region of the outer surface during operation of the aircraft;providing at least a portion of the outer surface with an acoustic liner having a depth dimension, a porous surface, and a plurality of internal chambers of different lengths interconnected by internal passageways to permit sound to travel between the internal chambers, and acoustically connected to the porous surface such that sound travels through the porous surface into the internal chamber, wherein the depth dimension of the acoustic liner extends between the porous surface and the outer surface;determining frequencies at which peak noise levels occur;determining a placement and surface acoustic impedance spectrum of the acoustic liner through the use of acoustic scattering prediction methods; andconfiguring the plurality of internal chambers to absorb sound in frequency ranges corresponding to a frequency of at least one peak of the spectral profile, wherein the plurality of internal chambers includes a first portion that extends into the depth dimension of the acoustic liner away from the porous surface toward the outer surface and to a distance that is greater than the dimension of the opening, and wherein the plurality of internal chambers contain an acoustic filler material that absorbs a portion of the sound that enters the plurality of internal chambers. 12. The aircraft of claim 11, wherein: a first chamber, from the plurality of chambers, includes a first portion and an inner portion, the inner portion-extending transversely from the first portion, whereby the first and inner portions of the first chamber together form an L-shape in a side cross-section of the acoustic liner. 13. The aircraft of claim 12, wherein: the first chamber includes a third portion extending transversely from the inner portion, whereby the first, inner, and third portions of the first chamber together form a J-shape in a side cross-section of the acoustic liner, and wherein at least a portion of a second chamber, from the plurality of chambers, is disposed between the inner portion of the first chamber and the porous surface. 14. An aircraft comprising: a fuselage defining outwardly-facing surfaces and lift-generating wings extending outwardly in generally opposite directions away from the fuselage and defining outer wing surfaces;at least one engine having a thrust-generating element, and wherein the aircraft includes a source of noise that produces noise during operation of the aircraft; anda noise absorbing acoustic liner disposed on at least a portion of one of the outer surfaces of the fuselage and the wings, the noise absorbing liner including: a porous outer surface that permits a portion of noise incident on the porous surface to pass therethrough;a first and a second chamber connected to the porous outer surface and extending into a depth dimension of the acoustic liner away from the porous outer surface and toward the outer surfaces of the fuselage or wings;a partition connected to the porous outer surface and disposed between first and second internal chambers, wherein the partition is substantially impervious such that sound is not transmitted from the first internal chamber to the second internal chamber, and such that sound is not transmitted from the second internal chamber to the first internal chamber;wherein the first and second chambers contains an acoustic filler material that absorbs a first portion of the sound that enters the first and second chambers through the porous surface,wherein the first and second chambers convert at least a portion of the sound enters the first and second chambers through the porous surface into beat energy, and transmits sound that has not been converted to heat energy out of the first and second internal chambers through the porous surface whereby a portion of the sound from the source of noise is absorbed by the acoustic liner. 15. The aircraft of claim 14, wherein each of the first and second chambers comprise a first end connected to the porous outer surface, and each of the first and second chambers comprise a second end terminating and embedded within the partition.