US3890060A - Acoustic duct with asymmetric acoustical treatment - Google Patents

Acoustic duct with asymmetric acoustical treatment Download PDF

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Publication number
US3890060A
US3890060A US442893A US44289374A US3890060A US 3890060 A US3890060 A US 3890060A US 442893 A US442893 A US 442893A US 44289374 A US44289374 A US 44289374A US 3890060 A US3890060 A US 3890060A
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United States
Prior art keywords
duct
acoustic
asymmetric
lining
sound
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Expired - Lifetime
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US442893A
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English (en)
Inventor
Norman J Lipstein
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General Electric Co
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General Electric Co
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Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US442893A priority Critical patent/US3890060A/en
Priority to GB2762/75A priority patent/GB1499724A/en
Priority to IT19841/75A priority patent/IT1031366B/it
Priority to DE2504073A priority patent/DE2504073C2/de
Priority to JP50018112A priority patent/JPS6010168B2/ja
Priority to BE153342A priority patent/BE825517A/xx
Priority to FR7504695A priority patent/FR2261583B1/fr
Application granted granted Critical
Publication of US3890060A publication Critical patent/US3890060A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/663—Sound attenuation
    • F04D29/664—Sound attenuation by means of sound absorbing material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/78—Other construction of jet pipes
    • F02K1/82—Jet pipe walls, e.g. liners
    • F02K1/827—Sound absorbing structures or liners
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
    • B64D33/00—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for
    • B64D33/02—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes
    • B64D2033/0206—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes comprising noise reduction means, e.g. acoustic liners
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
    • B64D33/00—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for
    • B64D33/02—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes
    • B64D2033/0266—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of power plants
    • B64D2033/0286—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of power plants for turbofan engines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

  • ABSTRACT Asymmetric or peripherally discontinuous acoustic [52] 415/119 Bl/33 linings for absorbing sound radiating within acoustic ducts, when properly located in the peripheral or cirgi gqtg gg 142: curnferential direction, alter the directivity of sound m; 50 137/15 emitted from an end of the duct to provide preferential enhanced suppression in a predetermined general direction.
  • treating the upper [56] Rderences Cited half produces approximately the same noise suppres- UNITED STATES PATENTS sion on the ground as a fully treated duct.
  • This invention relates to sound-absorbing acoustic ducts, and more particularly to an acoustic duct with asymmetric or peripherally discontinuous acoustical treatment. As a typical application, the invention relates to an asymmetric noise suppressing acoustic lining for the inlet of an aircraft jet engine fan.
  • Sound-absorbing acoustical material used as a lining in acoustic ducts is ordinarily applied symmetrically in the axial or longitudinal direction. That is, the acoustical material is circumferentially or peripherally continuous at any given axial or longitudinal location.
  • the sound absorbing linings at the inlet air passage of a jet engine fan in an airplane are applied over a full 360 of the internal surface of the fan cowling or casing. This is illustrated in U.S. Pat. No. 3,542,152 to A. P. Adamson, G. D. Oxx, .Ir., and W. R.
  • the acoustical material is a honeycombtype panel with tuned resonant cavity structures for the absorption of broadband noise. Provision is made for drainage of ingested liquid both in the sound-absorbing panel itself and in the cowling. Although advantageous for this application. the improved asymmetric acoustical treatment technique has utility in numerous other applications such as silencers for industrial gas turbines, and modifying the directivity patterns of acoustical horns.
  • an asymmetric or peripherally discontinuous acoustic lining for absorbing sound radiating within an acoustic duct, depending upon its location and extent in the peripheral direction. has the capability of selectively altering the directivity of sound emitted from an end of the duct.
  • the altered directivity of radiated sound or noise is employed to provide preferential enhanced suppression of sound in a preselected angular sector of the directivity pattern.
  • fan noise produced in an aircraft jet engine fan duct is selectively suppressed in the sector generally beneath the fan duct inlet by treating only the upper portion of the inner surface of the duct.
  • a fibrous acoustic material with a higher sound absorption coefficient can be used, and for a l80 semicylindrical acoustic lining, for example, the amount of noise suppression as to a ground observer is approximately the same as for the full 360 treatment.
  • the advantage is thus a reduction of required acoustic material or weight, or conversely an increased effect for the same amount of treatment. It is believed that the theoretical explanation relates to the better reflection of sound by the untreated lower inner surface of the rigid or hard walled duct.
  • a second acoustic lining is used to treat all or a portion of the remaining inner surface of the fan or other acoustic duct.
  • the firstmentioned asymmetric lining has a higher sound absorption coefficient than the second lining.
  • Another embodiment is an asymmetrically treated acoustical duct for side lobe suppression, which includes an acoustic lining with a pair of opposing sound-absorbing strips, each of which effects selective suppression of the opposite side lobe in the directivity pattern.
  • FIG. I is a diagrammatic side elevational view, par tially in longitudinal cross section, of the forward portion ofa ducted fan type aircraft jet engine having a fan duct provided with an asymmetric semicylindrical acoustic lining according to the teaching of the invention;
  • FIG. 2 is a vertical cross-sectional view of only the inlet fan duct or casing taken on the line 22 of FIG. 1 and showing the l asymmetric acoustical treat ment for preferential noise suppression as to a ground observer;
  • FIG. 3 shows three typical experimentally obtained directivity patterns for a cylindrical jet engine fan duct for the cases when the duct is untreated, has 360 acoustical treatment, and has a acoustical treatment;
  • FIG. 4 is a cross section similar to FIG. 2 illustrating another aspect of the invention using two different acoustic lining materials for optimum economic and noise suppression effect;
  • FIG. 5 is a cross section through an acoustic duct with asymmetric treatment for side lobe suppression.
  • FIG. I there is shown generally at 10 a ducted fan type turbojet engine having an annular streamlined fan duct air passage 11 formed by an annular cowling or fan casing 12 of streamlined cross section and a suitable engine nacelle structure 13 projecting within the cowling 12.
  • the nacelle structure 13 houses a suitable compressor, combustor, and turbomachinery for, as part of its functions, driving a fan 14 disposed in the air passage 11 between the forward end of the cowling 12 and the nacelle structure 13.
  • the fan 14 drives inlet air axially through the primary air passage 11 to provide propulsive thrust to the engine as well as to supply air to the compressor through a second, inner air passage 15.
  • the major part of the fan flow exits through an annular exhaust nozzle opening 16 formed by the inner surface of the cowling l2 and the outer surface of a gas generator pod casing 17.
  • the compressor inlet air passage 15 is formed between the inner casing 17 and the forwardly projecting, tear-shaped, fan mounting and drive structure 18.
  • the inside surface of the cowling 12 has an attached, asymmetrical semicylindrical acoustic lining 20 which, in this embodiment of the invention, covers only the top half of the inner surface.
  • This structure will hereafter be referred to as an asymmetrically treated fan duct.
  • the suppression of noise as to a ground observer is almost the same, or approximately the same, as if the prior known 360 acoustical treatment were used.
  • the directivity of noise emitted by the fan 14 is altered such that there is preferential or enhanced suppression of the noise pressure level in a selected direction, in this case generally beneath the noise source.
  • the fan 14 produces broadband noise, and is the major source ofjet engine noise.
  • a va riety of acoustic lining materials can be used, including the honeycombed, resonant chamber sound-absorbing panels shown in the previously mentioned US. Pat. No. 3,542,152, but it is preferred to employ a fibrous acoustic material with a higher sound absorption coefficient. Since the acoustic lining 20 covers only the top half of the fan duct, the need to use a material which provides for drainage of ingested liquids is diminished if not substantially eliminated.
  • suitable fibrous acoustic materials are fiberglass, stainless steel wool, and mineral wool for high temperature portions of the duct.
  • the advantage of the 50 percent or asymmetrically treated fan duct is evident, since practically the same noise suppression effect is obtained with only half the cost and weight as the previously full 360 treatment.
  • the cost per square foot of the above and other fibrous acoustic materials may be less than that of the honeycombed, resonant chamber sound-absorbing panels.
  • the altered, asymmetric directivity pattern of noise radiating from the inlet end of a semicylindrically, 50 percent treated fan duct is shown in FIG. 3.
  • the upper half of the experimental fan duct 21 is the acoustically treated semicylinder, while the bottom half is the untreated semicylinder.
  • Measurements were made in an anechoic chamber using a one-third scale model of the General Electric CF6 jet engine fan run at 90 percent design speed.
  • the symmetrical directivity patterns for an untreated fan duct and a 360 fully treated fan duct using the same acoustic material are illustrated respectively in dashed and dotted lines.
  • the reduction in sound pressure level produced by the full acoustical treatment is about 8 decibels.
  • the asymmetrical directivity pattern obtained by using the new 180 treatment is shown in full lines. It will be observed that over a large angular sector generally beneath and in front of the duct inlet, the amount of noise suppression using the 180 treatment is approximately the same as for the full 360 treatment. For the data taken, the noise reduction with the 180 treatment as compared to full treatment is almost the same over the sector from 50 to 1 measured downwardly with reference to the forwardly projected duct axis.
  • the noise suppression effect immediately in front of the duct inlet is not as favorable as that obtained by use of the full treatment, but there is less concern about noise suppression in these spatial regions since the primary objective of the acoustical treatment is the reduction of noise heard by human beings at ground level.
  • the noise suppression effect of the treatment is about half that of the full 360 treatment.
  • the redirection of noise obtained by use of the asymmetrical acoustical treatment, shown here for an axisymmetrical noise source is independent of the type ofacoustic material employed, and it is understood that the circumferential location of the asymmetric treatment determines the general direction at which the preferential noise suppression is obtained.
  • the preferential, enhanced noise suppression is obtained above the duct inlet rather than be low.
  • the directivity pattern is asymmetrical, with the preferential or enhanced noise suppression being determined by the circumferential placement of the acoustic material.
  • results are generally applicable to arcuate asymmetric treatments with an angular extent greater or less than 180, the limits being determined at either side by practical considerations and the intended application, weighing the cost of the acoustic material versus the amount of preferential noise suppression desired.
  • the invention is applicable in general to acoustic ducts with cross sections other than circular, such as rectangular and square.
  • a modification is the use of two different acoustic lining materials for optimum noise suppression effect. This is particularly well illustrated in the case of the fan duct for the aircraft jet engine.
  • the upper half of the inner surface of the cowling 12 is lined with the fibrous acoustic material 20, while the lower half is lined with the previously mentioned honeycombed, resonant chamber sound-absorbing structural panel material 22.
  • the first acoustic treatment material 22 has the advantage of durability and good drainage for ingested liquids, while the second acoustical treatment material is desirably selected to obtain the combination of lower cost with a higher sound absorption coefficient.
  • the structural acoustic panels 22 are made of, or have 21 facing sheet made of, a rigid material such as a suitable metal or plastic, and reflect sound more readily than the fibrous acoustic material 20.
  • FIG. 5 Another embodiment of the invention shown in FIG. 5 illustrates the applicability of the principle of asymmetric acoustical treatment to the suppression of side lobes.
  • the duct 23 in this case is a hard-walled acoustical duct suitable for other applications such as a silencer for an industrial gas turbine, or in an acoustical horn structure.
  • a silencer for an industrial gas turbine or in an acoustical horn structure.
  • two diametrically opposing arcuate strips 240 and 24b of the same acoustic material are used.
  • the duct 23 has a length at least equal to or greater than the diameter and that the sound-absorbing strips 240 and 24b extend axially throughout the length of the duct or a specified portion of the length.
  • the effect of the asymmetric left-hand acoustic treatment 24a is to suppress the side lobe at the right-hand side of the directivity pattern
  • the effect of the asymmetric right-hand acoustic treatment 24b is to suppress the side lobe at the left-hand side of the directivity pattern.
  • the explanation for the resulting altered directivity pattern, with preferential noise suppression at both sides, is similar to that for the fan duct application and need not be repeated.
  • the required arcuate extent of the acoustic material strips 240 and 24b to produce side lobe suppression can be determined easily. As in the fan duct case (see FIG. 4), overall noise reduction is improved by the use of two different acoustic materials, with the understanding that the side lobe suppression strips 24a and 24b are made of a material with a higher sound absorption coefficient.
  • asymmetric acoustic linings for suppressing sound and noise emitted from acoustic ducts when properly located in the peripheral or circumferential direction, have the advantage of minimizing the amount of acoustic material needed for a desired result, or conversely achieve an increased effect with the same amount of treatment.
  • the reduction ofjet engine fan noise on the ground, and acoustic ducts for side lobe suppression have been discussed, but many other applications are possible.
  • An improved noise-suppressing fan duct for an aircraft jet engine having a fan disposed within an annular fan duct air passage comprising a generally streamlined rigid fan duct with a circular cross section having an asymmetric, circumferentially discontinuous acoustic lining attached to the inner surface thereof for absorbing noise which radiates within said duct,
  • said asymmetric acoustic lining being located on the upper portion of the circumference of said duct and being effective to alter the directivity of noise emitted from an end of said fan duct and produce an asymmetric directivity pattern characterized by preferential enhanced suppression of noise in an angular sector generally below the jet engine,
  • asymmetric acoustic lining is approximately semicylindrical and is continuous and uninterrupted in both the axial and circumferential directions
  • a second acoustic lining attached to the lower half of the circumference of said duct, said first-mentioned asymmetric acoustic lining having a higher sound absorption coefficient than said second acoustic lining.
  • An improved noise-suppressing fan duct for an aircraft jet engine having a fan disposed within an annular fan duct air passage comprising a generally streamlined rigid fan duct with a circular cross section having an asymmetric, circumferentially discontinuous acoustic lining attached to the inner surface thereof for absorbing noise which radiates within said duct,
  • said asymmetric acoustic lining being located on the upper portion of the circumference of said duct and being effective to alter the directivity of noise emitted from an end of said fan duct and produce an asymmetric directivity pattern characterized by preferential enhanced suppression of noise in an angular sector generally below the jet engine,
  • said asymmetric acoustic lining is made of a fibrous acoustic material and is continuous and substantially uninterrupted in both the axial and circumferential directions, and further including a second acoustic lining attached to the lower portions of the circumference of said duct, said firstmentioned asymmetric acoustic lining having a higher sound absorption coefficient than said second acoustic lining.
  • An improved noise-suppressing fan duct for an aircraft jet engine having a fan disposed within an annular fan duct air passage comprising a generally streamlined rigid fan duct with a circular cross section having an asymmetric, circumferentially discontinuous acoustic lining attached to the inner surface thereof for absorbing noise which radiates within said duct,
  • said asymmetric acoustic lining being located on the upper portion of the circumference of said duct and being effective to alter the directivity of noise emitted from an end of said fan duct and produce an asymmetric directivity pattern characterized by preferential enhanced suppression of noise in an angular sector generally below the jet engine,
  • said asymmetric acoustic lining is made of a fibrous acoustic material, and further including a second acoustic lining attached to the lower portion of the circumference of said duct, said second acoustic lining having provision for drainage of ingested liquids and a lower sound absorption coefficient than said first-mentioned asymmetric acoustic lining,
  • said first-mentioned asymmetric acoustic lining and second acoustic lining in combination being circumferentially continuous. each individual lining further being continuous and substantially uninterrupted in both the circumferential and axial direc tions.
  • a sound suppressing acoustic duct comprising an axially extending, relatively rigid hard-walled duct having attached to a portion of the periphery of the inner surface thereof a first asymmetric sound absorbing acoustic lining, a second sound absorbing acoustic lining attached to the remaining portion of the periphery of the inner surface of said duct, said first and second acoustic linings in combination being peripherally continuous and functioning to absorb sound which radiates longitudinally through said duct and is reflected internally each of said acoustic linings individually being continuous and substantially uninterrupted in both the axial and peripheral directions, said first acoustic lining further having a higher sound absorption coefficient than said second acoustic lining,
  • said first asymmetric sound absorbing lining being peripherally located at any desired peripheral locaclaim 4 wherein said duct is an aircraft jet engine fan duct and at least said first acoustic lining is made of a fibrous acoustic material.
  • a sound suppressing acoustic duct comprising an axially extending, relatively rigid duct having a hard-walled inner surface into which is recessed an attached acoustic lining for preferential side lobe suppression comprised by a pair of opposing sound absorbing strips for absorbing sound which radiates longitudinally through said duct and is reflected internally,
  • each of said sound absorbing strips being made of the same acoustic material and each being continuous and substantially uninterrupted in both the axial and peripheral directions.
  • said pair of opposing sound absorbing strips being peripherally spaced from one another and peripherally located and dimensioned to obtain preferential enhanced side lobe suppression of the sound emitted from an end of said duct.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Exhaust Silencers (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
US442893A 1974-02-15 1974-02-15 Acoustic duct with asymmetric acoustical treatment Expired - Lifetime US3890060A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US442893A US3890060A (en) 1974-02-15 1974-02-15 Acoustic duct with asymmetric acoustical treatment
GB2762/75A GB1499724A (en) 1974-02-15 1975-01-22 Acoustic ducts
IT19841/75A IT1031366B (it) 1974-02-15 1975-01-31 Condotto acustico con trattamento acustico asimmetrico pa rtico larmente per turbomotori a gas
DE2504073A DE2504073C2 (de) 1974-02-15 1975-01-31 Schalldämpfer für ein in einem Strömungskanal angeordnetes Gasturbinentriebwerk
JP50018112A JPS6010168B2 (ja) 1974-02-15 1975-02-14 非対称吸音処理を施した吸音ダクト
BE153342A BE825517A (fr) 1974-02-15 1975-02-14 Canal a insonorisation asymetrique
FR7504695A FR2261583B1 (de) 1974-02-15 1975-02-14

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US442893A US3890060A (en) 1974-02-15 1974-02-15 Acoustic duct with asymmetric acoustical treatment

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US (1) US3890060A (de)
JP (1) JPS6010168B2 (de)
BE (1) BE825517A (de)
DE (1) DE2504073C2 (de)
FR (1) FR2261583B1 (de)
GB (1) GB1499724A (de)
IT (1) IT1031366B (de)

Cited By (40)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3947148A (en) * 1973-12-27 1976-03-30 Chrysler United Kingdom Limited Fan assemblies
US4104002A (en) * 1976-12-02 1978-08-01 General Electric Company Spiral strip acoustic treatment
US4989886A (en) * 1988-12-30 1991-02-05 Textron Inc. Braided filamentary sealing element
EP0412454A1 (de) * 1989-08-09 1991-02-13 Mitsubishi Denki Kabushiki Kaisha Gebläse
US5029875A (en) * 1989-07-07 1991-07-09 Textron Inc. Fluid seal structure
US5594218A (en) * 1995-01-04 1997-01-14 Northrop Grumman Corporation Anechoic chamber absorber and method
US5702231A (en) * 1996-08-09 1997-12-30 The Boeing Company Apparatus and method for reducing noise emissions from a gas turbine engine inlet
US5709529A (en) * 1995-11-14 1998-01-20 Westinghouse Electric Corporation Optimization of turbomachinery harmonics
EP1010884A1 (de) * 1998-12-17 2000-06-21 Turbomeca Akustich verkleideter Mehrring-Abgaskanal für Turbomaschinen
US6557799B1 (en) 2001-11-09 2003-05-06 The Boeing Company Acoustic treated thrust reverser bullnose fairing assembly
US20030152455A1 (en) * 2002-02-14 2003-08-14 James Malcolm R. Engine casing
US6811372B1 (en) * 1999-12-07 2004-11-02 A2 Acoustics Ab Device at an acoustic liner
FR2898870A1 (fr) 2006-03-24 2007-09-28 Aircelle Sa Structure de virole d'entree d'air
US20070251212A1 (en) * 2006-04-26 2007-11-01 Rolls-Royce Plc Aeroengine noise reduction
WO2008029062A2 (fr) * 2006-09-07 2008-03-13 Airbus France Dispositif permettant d'améliorer l'efficacité des traitements acoustiques dans un conduit d'une motorisation d'aéronef
US20080074841A1 (en) * 2006-09-26 2008-03-27 Robert Boyd Curtis Dampening acoustic vibrations within an electronic system
WO2008060944A2 (en) * 2006-11-15 2008-05-22 Mcclellan Thomas W High-efficiency, frequency-tunable, acoustic wool and method of attenuating acoustic vibrations
WO2008132009A2 (de) * 2007-04-25 2008-11-06 Eads Deutschland Gmbh Schallschutzvorrichtung für ein strahltriebwerk oder eine turbine
US20090045009A1 (en) * 2007-08-15 2009-02-19 Rohr, Inc. Linear acoustic liner
US20110016737A1 (en) * 2008-01-25 2011-01-27 Christophe Gaillard Silencer for drying appliance and quiet hairdryer
US20120269619A1 (en) * 2011-04-20 2012-10-25 Rolls-Royce Deutschland Ltd & Co Kg Fluid-flow machine
US20130000273A1 (en) * 2011-06-29 2013-01-03 United Technologies Corporation Gas-driven propulsor with tip turbine fan
WO2013092279A1 (de) 2011-12-21 2013-06-27 Eads Deutschland Gmbh Schallschutzvorrichtung und damit versehenes triebwerk und verfahren zur bereitstellung
US20150000252A1 (en) * 2012-11-12 2015-01-01 Matthew D. Moore Rotational annular airscrew with integrated acoustic arrester
WO2014189572A3 (en) * 2013-02-26 2015-01-08 United Technologies Corporation Acoustic treatment to mitigate fan noise
US20160129988A1 (en) * 2014-04-29 2016-05-12 Autogyro Ag Aircraft
US20160186690A1 (en) * 2013-08-12 2016-06-30 United Technologies Corporation Non-axisymmetric fan flow path
US9512727B2 (en) 2011-03-28 2016-12-06 Rolls-Royce Deutschland Ltd & Co Kg Rotor of an axial compressor stage of a turbomachine
US20170022903A1 (en) * 2015-07-21 2017-01-26 The Boeing Company Sound attenuation apparatus and method
US9587563B2 (en) 2015-07-21 2017-03-07 The Boeing Company Sound attenuation apparatus and method
US9822795B2 (en) 2011-03-28 2017-11-21 Rolls-Royce Deutschland Ltd & Co Kg Stator of an axial compressor stage of a turbomachine
US9850850B2 (en) * 2013-10-23 2017-12-26 Rohr, Inc. Acoustically treated thrust reverser track beam
US10161357B2 (en) 2016-06-17 2018-12-25 Rohr, Inc. Acoustically treated thrust reverser track beam
CN111741899A (zh) * 2018-02-19 2020-10-02 赛峰飞机发动机公司 具有声音可透过壁的涡轮机短舱
US10814966B2 (en) 2015-05-25 2020-10-27 Dotterel Technologies Limited Shroud for an aircraft
US10823060B2 (en) * 2015-12-18 2020-11-03 Raytheon Technologies Corporation Gas turbine engine with short inlet, acoustic treatment and anti-icing features
US11097828B2 (en) 2017-07-24 2021-08-24 Dotterel Technologies Limited Shroud
US11131322B2 (en) * 2018-07-03 2021-09-28 Rolls-Royce Deutschland Ltd & Co Kg Structural assembly for a compressor of a fluid flow machine
USRE48980E1 (en) 2013-03-15 2022-03-22 Raytheon Technologies Corporation Acoustic liner with varied properties
US11721352B2 (en) 2018-05-16 2023-08-08 Dotterel Technologies Limited Systems and methods for audio capture

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2820715B1 (fr) 2001-02-15 2003-05-30 Eads Airbus Sa Procede de degivrage d'un capot d'entree d'air de moteur a reaction et dispositif pour sa mise en oeuvre
FR2820716B1 (fr) 2001-02-15 2003-05-30 Eads Airbus Sa Procede de degivrage par circulation forcee d'un fluide, d'un capot d'entree d'air de moteur a reaction et dispositif pour sa mise en oeuvre

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2909235A (en) * 1955-11-03 1959-10-20 Gen Dynamics Corp Muffler
US3263771A (en) * 1964-05-21 1966-08-02 Seifert Kurt Sound absorbing pipe lining having packing with different densities
US3508838A (en) * 1968-09-16 1970-04-28 Gen Electric Sound suppression of compressors used in gas turbine engines
US3542152A (en) * 1968-04-08 1970-11-24 Gen Electric Sound suppression panel
US3655008A (en) * 1971-01-28 1972-04-11 Rohr Corp Sound suppressing apparatus
US3692141A (en) * 1968-07-26 1972-09-19 Dassault Avions Method of and means for noise attenuation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2909235A (en) * 1955-11-03 1959-10-20 Gen Dynamics Corp Muffler
US3263771A (en) * 1964-05-21 1966-08-02 Seifert Kurt Sound absorbing pipe lining having packing with different densities
US3542152A (en) * 1968-04-08 1970-11-24 Gen Electric Sound suppression panel
US3692141A (en) * 1968-07-26 1972-09-19 Dassault Avions Method of and means for noise attenuation
US3508838A (en) * 1968-09-16 1970-04-28 Gen Electric Sound suppression of compressors used in gas turbine engines
US3655008A (en) * 1971-01-28 1972-04-11 Rohr Corp Sound suppressing apparatus

Cited By (72)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3947148A (en) * 1973-12-27 1976-03-30 Chrysler United Kingdom Limited Fan assemblies
US4104002A (en) * 1976-12-02 1978-08-01 General Electric Company Spiral strip acoustic treatment
US4989886A (en) * 1988-12-30 1991-02-05 Textron Inc. Braided filamentary sealing element
US5029875A (en) * 1989-07-07 1991-07-09 Textron Inc. Fluid seal structure
EP0412454A1 (de) * 1989-08-09 1991-02-13 Mitsubishi Denki Kabushiki Kaisha Gebläse
US5110258A (en) * 1989-08-09 1992-05-05 Mitsubishi Denki Kabushiki Kaisha Blower having a sound-damping structure
US5594218A (en) * 1995-01-04 1997-01-14 Northrop Grumman Corporation Anechoic chamber absorber and method
US5688348A (en) * 1995-01-04 1997-11-18 Northrop Grumman Corporation Anechoic chamber absorber and method
US5709529A (en) * 1995-11-14 1998-01-20 Westinghouse Electric Corporation Optimization of turbomachinery harmonics
US5702231A (en) * 1996-08-09 1997-12-30 The Boeing Company Apparatus and method for reducing noise emissions from a gas turbine engine inlet
EP0823547A1 (de) 1996-08-09 1998-02-11 The Boeing Company Einrichtung und Verfahren zum Reduzieren der Schallemision eines Lufteinlasses für Gasturbinen
EP1010884A1 (de) * 1998-12-17 2000-06-21 Turbomeca Akustich verkleideter Mehrring-Abgaskanal für Turbomaschinen
FR2787513A1 (fr) * 1998-12-17 2000-06-23 Turbomeca Dispositif d'echappement multicanal de turbomachine traite acoustiquement
US6672424B2 (en) 1998-12-17 2004-01-06 Turbomeca Acoustically treated turbomachine multi-duct exhaust device
US6811372B1 (en) * 1999-12-07 2004-11-02 A2 Acoustics Ab Device at an acoustic liner
US6557799B1 (en) 2001-11-09 2003-05-06 The Boeing Company Acoustic treated thrust reverser bullnose fairing assembly
US20030152455A1 (en) * 2002-02-14 2003-08-14 James Malcolm R. Engine casing
US6905305B2 (en) * 2002-02-14 2005-06-14 Rolls-Royce Plc Engine casing with slots and abradable lining
CN101410300B (zh) * 2006-03-24 2013-07-31 埃尔塞乐公司 空气入口护罩结构
FR2898870A1 (fr) 2006-03-24 2007-09-28 Aircelle Sa Structure de virole d'entree d'air
WO2007110491A1 (fr) * 2006-03-24 2007-10-04 Aircelle Structure de virole d'entree d'air
US20100232932A1 (en) * 2006-03-24 2010-09-16 Guy Bernard Vauchel Air inlet shroud structure
US8231332B2 (en) 2006-03-24 2012-07-31 Aircelle Air inlet shroud structure
US20070251212A1 (en) * 2006-04-26 2007-11-01 Rolls-Royce Plc Aeroengine noise reduction
WO2008029062A2 (fr) * 2006-09-07 2008-03-13 Airbus France Dispositif permettant d'améliorer l'efficacité des traitements acoustiques dans un conduit d'une motorisation d'aéronef
WO2008029062A3 (fr) * 2006-09-07 2008-05-29 Airbus France Dispositif permettant d'améliorer l'efficacité des traitements acoustiques dans un conduit d'une motorisation d'aéronef
US20100038476A1 (en) * 2006-09-07 2010-02-18 Airbus France Device that makes it possible to improve the effectiveness of the acoustic treatments in a pipe of an aircraft power plant
US8167232B2 (en) 2006-09-07 2012-05-01 Airbus Operations Sas Device that makes it possible to improve the effectiveness of the acoustic treatments in a pipe of an aircraft power plant
US8780550B2 (en) * 2006-09-26 2014-07-15 Hewlett-Packard Development Company, L.P. Dampening acoustic vibrations within an electronic system
US20080074841A1 (en) * 2006-09-26 2008-03-27 Robert Boyd Curtis Dampening acoustic vibrations within an electronic system
WO2008060944A3 (en) * 2006-11-15 2008-07-10 Thomas W Mcclellan High-efficiency, frequency-tunable, acoustic wool and method of attenuating acoustic vibrations
WO2008060944A2 (en) * 2006-11-15 2008-05-22 Mcclellan Thomas W High-efficiency, frequency-tunable, acoustic wool and method of attenuating acoustic vibrations
WO2008132009A3 (de) * 2007-04-25 2009-02-26 Eads Deutschland Gmbh Schallschutzvorrichtung für ein strahltriebwerk oder eine turbine
WO2008132009A2 (de) * 2007-04-25 2008-11-06 Eads Deutschland Gmbh Schallschutzvorrichtung für ein strahltriebwerk oder eine turbine
US8196704B2 (en) 2007-08-15 2012-06-12 Rohr, Inc. Linear acoustic liner
US20090045009A1 (en) * 2007-08-15 2009-02-19 Rohr, Inc. Linear acoustic liner
US7921966B2 (en) 2007-08-15 2011-04-12 Rohr, Inc. Linear acoustic liner
US20110162910A1 (en) * 2007-08-15 2011-07-07 Rohr, Inc. Linear acoustic liner
US20110016737A1 (en) * 2008-01-25 2011-01-27 Christophe Gaillard Silencer for drying appliance and quiet hairdryer
US8601713B2 (en) * 2008-01-25 2013-12-10 Velecta Paramount S.A. Silencer for drying appliance and quiet hairdryer
US9512727B2 (en) 2011-03-28 2016-12-06 Rolls-Royce Deutschland Ltd & Co Kg Rotor of an axial compressor stage of a turbomachine
US9822795B2 (en) 2011-03-28 2017-11-21 Rolls-Royce Deutschland Ltd & Co Kg Stator of an axial compressor stage of a turbomachine
US9816528B2 (en) * 2011-04-20 2017-11-14 Rolls-Royce Deutschland Ltd & Co Kg Fluid-flow machine
US20120269619A1 (en) * 2011-04-20 2012-10-25 Rolls-Royce Deutschland Ltd & Co Kg Fluid-flow machine
US8943792B2 (en) * 2011-06-29 2015-02-03 United Technologies Corporation Gas-driven propulsor with tip turbine fan
US20130000273A1 (en) * 2011-06-29 2013-01-03 United Technologies Corporation Gas-driven propulsor with tip turbine fan
DE102011056826B4 (de) * 2011-12-21 2014-06-26 Eads Deutschland Gmbh Schallschutzvorrichtung und damit versehenes Triebwerk und Verfahren zur Bereitstellung
WO2013092279A1 (de) 2011-12-21 2013-06-27 Eads Deutschland Gmbh Schallschutzvorrichtung und damit versehenes triebwerk und verfahren zur bereitstellung
DE102011056826A1 (de) 2011-12-21 2013-06-27 Eads Deutschland Gmbh Schallschutzvorrichtung und damit versehenes Triebwerk und Verfahren zur Bereitstellung
US20150000252A1 (en) * 2012-11-12 2015-01-01 Matthew D. Moore Rotational annular airscrew with integrated acoustic arrester
US9476385B2 (en) * 2012-11-12 2016-10-25 The Boeing Company Rotational annular airscrew with integrated acoustic arrester
EP2730501A3 (de) * 2012-11-12 2017-11-15 The Boeing Company Luftschraube mit akustischem Ableiter
WO2014189572A3 (en) * 2013-02-26 2015-01-08 United Technologies Corporation Acoustic treatment to mitigate fan noise
US9957840B2 (en) 2013-02-26 2018-05-01 United Technologies Corporation Acoustic treatment to mitigate fan noise
USRE48980E1 (en) 2013-03-15 2022-03-22 Raytheon Technologies Corporation Acoustic liner with varied properties
US20160186690A1 (en) * 2013-08-12 2016-06-30 United Technologies Corporation Non-axisymmetric fan flow path
US10415505B2 (en) * 2013-08-12 2019-09-17 United Technologies Corporation Non-axisymmetric fan flow path
US9850850B2 (en) * 2013-10-23 2017-12-26 Rohr, Inc. Acoustically treated thrust reverser track beam
US20160129988A1 (en) * 2014-04-29 2016-05-12 Autogyro Ag Aircraft
US9868507B2 (en) * 2014-04-29 2018-01-16 Autogyro Ag Aircraft having keel tube with structure that reduces noise emissions
US10814966B2 (en) 2015-05-25 2020-10-27 Dotterel Technologies Limited Shroud for an aircraft
US9587563B2 (en) 2015-07-21 2017-03-07 The Boeing Company Sound attenuation apparatus and method
US9963238B2 (en) 2015-07-21 2018-05-08 The Boeing Company Sound attenuation apparatus and method
US9771868B2 (en) * 2015-07-21 2017-09-26 The Boeing Company Sound attenuation apparatus and method
US20170022903A1 (en) * 2015-07-21 2017-01-26 The Boeing Company Sound attenuation apparatus and method
US10823060B2 (en) * 2015-12-18 2020-11-03 Raytheon Technologies Corporation Gas turbine engine with short inlet, acoustic treatment and anti-icing features
US10161357B2 (en) 2016-06-17 2018-12-25 Rohr, Inc. Acoustically treated thrust reverser track beam
US11097828B2 (en) 2017-07-24 2021-08-24 Dotterel Technologies Limited Shroud
CN111741899A (zh) * 2018-02-19 2020-10-02 赛峰飞机发动机公司 具有声音可透过壁的涡轮机短舱
CN111741899B (zh) * 2018-02-19 2023-12-22 赛峰飞机发动机公司 具有声音可透过壁的涡轮机短舱
US11721352B2 (en) 2018-05-16 2023-08-08 Dotterel Technologies Limited Systems and methods for audio capture
US11131322B2 (en) * 2018-07-03 2021-09-28 Rolls-Royce Deutschland Ltd & Co Kg Structural assembly for a compressor of a fluid flow machine

Also Published As

Publication number Publication date
JPS6010168B2 (ja) 1985-03-15
FR2261583B1 (de) 1981-02-13
GB1499724A (en) 1978-02-01
FR2261583A1 (de) 1975-09-12
IT1031366B (it) 1979-04-30
JPS50118114A (de) 1975-09-16
BE825517A (fr) 1975-05-29
DE2504073A1 (de) 1975-08-21
DE2504073C2 (de) 1983-12-01

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