EP0161458A1 - Revetement de paroi absorbant les ondes acoustiques - Google Patents

Revetement de paroi absorbant les ondes acoustiques Download PDF

Info

Publication number
EP0161458A1
EP0161458A1 EP85104033A EP85104033A EP0161458A1 EP 0161458 A1 EP0161458 A1 EP 0161458A1 EP 85104033 A EP85104033 A EP 85104033A EP 85104033 A EP85104033 A EP 85104033A EP 0161458 A1 EP0161458 A1 EP 0161458A1
Authority
EP
European Patent Office
Prior art keywords
fluid
conduits
acoustic waves
coating according
ambient
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.)
Withdrawn
Application number
EP85104033A
Other languages
German (de)
English (en)
French (fr)
Inventor
René Perret
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.)
Alstom SA
Original Assignee
Alstom SA
Alsthom Atlantique SA
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 Alstom SA, Alsthom Atlantique SA filed Critical Alstom SA
Publication of EP0161458A1 publication Critical patent/EP0161458A1/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • 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
    • G10K11/00—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
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
    • 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24149—Honeycomb-like

Definitions

  • the present invention relates to a wall covering absorbing acoustic waves.
  • a noise source and a rigid-walled body are placed in a fluid medium where sound waves can propagate, part of the energy carried by the waves hitting the wall is reflected by it, part is transmitted through the wall, and a small part is absorbed by the material constituting the wall or its coating.
  • the value of the ratio of the energy absorbed to the incident energy, or absorption coefficient depends on the nature of the material constituting or coating the wall, and on the frequency of the sound.
  • the known coatings appear to be very insufficient when the ambient medium is constituted by a liquid, especially for low frequencies below 1000 Hz.
  • the present invention aims to obtain an effective absorption of acoustic waves, even in a liquid ambient medium, and even at low frequencies.
  • the coating according to the invention has an inner face intended to be applied to a rigid base wall and an outer face intended to bathe in an ambient fluid traversed by acoustic waves.
  • the ambient fluid is air, and also the dissipating fluid.
  • the above equality means that an acoustic wave will theoretically be perfectly absorbed if the equality is exactly verified, if the frequency of the wave has a precise value, and if the thickness of the auxiliary walls and the separating membrane have no influence on the propagation of the waves.
  • the indication that this equality must be checked “substantially” means that the ratio of his two terms must be chosen as close as possible to 1 and in practice must remain between approximately 0.2 and 5.
  • the perforation rate is the ratio of the total open section S2 of a large number of conduits adjacent to the surface S1 of the covering occupied by these conduits and the auxiliary walls which limit them. It should be understood that these various quantities retain their meanings when the adjacent conduits are not completely separated from each other by the auxiliary walls; the important point according to the invention is that there are zones, the conduits, in which the dissipating fluid can practically move under the influence of acoustic waves, and solid elements which, by friction, practically cancel the speed of movement of this fluid in their immediate vicinity.
  • the equivalent hydraulic diameter d is equal to the diameter of the conduits if they have a circular section. If their section has a different regular shape, the equivalent hydraulic diameter can be defined as equal to four times the ratio of the area of the straight section of the duct to the wet perimeter.
  • the above wet perimeter is the length, in each straight section, of the line which constitutes the border between the immobilization zone and the zone where the movement of the fluid is possible. This movement is more or less braked by internal friction in the fluid, depending on the distance at which one is from the nearest border line.
  • the kinematic viscosity v of the dissipating fluid is higher or at least slightly lower than the product fo .d 2 of this frequency by the square of the equivalent diameter d, so that the distribution of the alternating velocities in the section of the dissipation duct is analogous to that which appears in a permanent laminar unidirectional flow.
  • This viscosity is preferably greater than half of this product.
  • the stiffness K presented by said elastic compression volumes to the dissipating fluid is chosen to be substantially equal to so that said adaptation frequency is the frequency f, the stiffness K being the ratio of a force to a displacement, this force being a longitudinal force which can be applied to the bottom of a dissipation duct by an acoustic wave, this displacement being the longitudinal displacement which is caused by this force and which is equal to the variation of total volume of these compression volumes under the action of this force, this variation being divided by the section of this conduit.
  • the separating membrane can be very thin and very flexible so as not to oppose any obstacle to the passage of acoustic waves, but such a thin membrane is very fragile and can hardly be used except in the laboratory.
  • the present invention seems especially interesting at sea, at sometimes significant depths. This is why, preferably, the separating membrane is made of a material having a value of the product P 2 .C 2 equal to that of the product P o .C o of the ambient fluid, this product being that of the specific mass of the material by the speed of the acoustic waves in the material, so as to allow this membrane to be given a thickness allowing it to resist external aggressions and differences in hydrostatic pressures.
  • the dissipating fluid is an auxiliary liquid and the more compressible fluid is a gas enclosed in flexible enclosures, the total interior volume of this or these flexible enclosures at the bottom of each energy dissipation duct being chosen to obtain substantially said value of the stiffness K.
  • This gas is enclosed in these flexible enclosures under an inflation pressure which is higher than atmospheric pressure so as to prevent the volume of these enclosures from being too reduced when the hydrostatic pressure of the ambient liquid increases.
  • this inflation pressure will often be chosen to be greater than two absolute bars.
  • the dissipating fluid As for the dissipating fluid, it consists of water added with long-chain organic molecules to increase its viscosity.
  • the metal honeycomb shown in FIG. 2 is replaced by an embossed paper coated with resin delimiting, by gluing, damping conduits.
  • the conduits containing the viscous fluid are of substantially rectangular section and constituted by the stacking of ribbed plates 14.
  • the ribs 15 of these plates are of a height close to 1 mm and they delimit conduits between them 16 whose length, in the direction normal to the wall is close to 30 mm.
  • the elastic medium 6 foam rubber for example.
  • the plates are covered with the separating wall 3.
  • the energy losses of the acoustic waves are produced by the friction of the viscous liquid against a multitude of bristles 21 arranged in a "brush" and constituting said auxiliary walls.
  • the bristles of these brushes have a diameter close to 1 mm; their intervals are between 1 and 2 mm and constitute said conduits, which are therefore here in communication laterally the with each other.
  • the bristles are pricked on a support plate 22 which is itself placed against the base wall 1.
  • the separating membrane 25 is thick.
  • the compression volumes are produced by placing small hollow plastic spheres 24 between the bristles, against the support plate. It would also be possible to use hollow bristles full of air or gas.
  • the length of the bristles of the brush is about 5 cm.
  • the product P 2 .C 2 of the wall 25 is equal to that of water.
  • the thick separating membrane As for the thick separating membrane previously mentioned and having a value of the product C close to that of the ambient liquid, it can be constituted, when this ambient liquid is water, by a polymethyl methacrylate analogous to that distributed commercially under the Plexiglas brand or better by a polycarbonate analogous to that distributed commercially under the Macrolon brand. It is also possible to use certain polyethylenes or a known neoprene for the protection of hydrophones.
  • the aforementioned damping liquid can consist of water with a cellulose hydroxyl ether obtained by treating the cellulose with sodium hydroxyl and reacting it with ethylene oxide.
  • the product of this reaction is purified and delivered in the form of a fine white powder. It is marketed under the Natrosol brand by the French company Hercules France, cios anonyme, Tour Albert 1er 92507 Rueil Malmaison Cedex.
  • the fourth embodiment of the invention according to FIG. 7 seems particularly advantageous on flat rectangular base walls.
  • the coating is then formed by a juxtaposition of open boxes 30 of rectangular section whose bottom is glued to the base wall 1.
  • the auxiliary walls are purchased in the form of a honeycomb 5 sandwiched between two very thin and flexible sheets 5a and 5b.
  • the sheet 5a is glued to the bottom of the box on a layer of foam rubber 31 constituting the elastic compression volumes.
  • the sheet 5b is slightly recessed from the edges of the side walls of the box.
  • a rigid plate 32 of polymethyl methacrylate is glued on these edges and constitutes the separating membrane separated from the honeycomb 5 by the gap 32a.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Building Environments (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Devices Affording Protection Of Roads Or Walls For Sound Insulation (AREA)
EP85104033A 1984-04-09 1985-04-04 Revetement de paroi absorbant les ondes acoustiques Withdrawn EP0161458A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8405558A FR2562699B1 (fr) 1984-04-09 1984-04-09 Revetement de paroi absorbant les ondes acoustiques
FR8405558 1984-04-09

Publications (1)

Publication Number Publication Date
EP0161458A1 true EP0161458A1 (fr) 1985-11-21

Family

ID=9302969

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85104033A Withdrawn EP0161458A1 (fr) 1984-04-09 1985-04-04 Revetement de paroi absorbant les ondes acoustiques

Country Status (4)

Country Link
US (1) US4560028A (enrdf_load_stackoverflow)
EP (1) EP0161458A1 (enrdf_load_stackoverflow)
JP (1) JPS60237491A (enrdf_load_stackoverflow)
FR (1) FR2562699B1 (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2582847A1 (fr) * 1985-05-31 1986-12-05 Vibrasonic Dispositif destine a absorber les ondes sonores
EP0292877A1 (fr) * 1987-05-25 1988-11-30 Gec Alsthom Sa Revêtement de paroi absorbant les ondes acoustiques en milieu liquide
FR2622333A1 (fr) * 1987-10-27 1989-04-28 Thomson Csf Revetement anechoique pour ondes acoustiques
FR2656718A1 (fr) * 1989-12-28 1991-07-05 Thomson Csf Absorbeur acoustique pour milieu fluide, notamment pour milieu marin.
FR2664868A1 (fr) * 1990-07-19 1992-01-24 Bertin & Cie Revetement anechouide, en particulier pour coques de navires et de sous-marins.
WO1992022053A1 (en) * 1991-05-30 1992-12-10 Short Brothers Plc Noise attenuation panel
EP0897176A1 (fr) * 1997-08-14 1999-02-17 Thomson Marconi Sonar Sas Absorbeur acoustique sous-marin

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4667768A (en) * 1986-05-01 1987-05-26 Lockheed Corporation Sound absorbing panel
DE19653850C2 (de) * 1996-12-21 1999-01-28 Daimler Benz Aerospace Airbus Wandelement
DE19804718C2 (de) 1998-02-06 2001-09-13 Eurocopter Deutschland Schall absorbierende Sandwichwand
US6123171A (en) * 1999-02-24 2000-09-26 Mcnett; Christopher P. Acoustic panels having plural damping layers
DE10231791C1 (de) * 2002-07-15 2003-12-18 Airbus Gmbh Mehrschichtplatte zur Verringerung der Schallabstrahlung
US7837008B1 (en) 2005-09-27 2010-11-23 The United States Of America As Represented By The Secretary Of The Air Force Passive acoustic barrier
US20110100747A1 (en) * 2006-05-24 2011-05-05 Airbus Operations Gmbh Sandwich element for the sound-absorbing inner cladding of means of transport, especially for the sound-absorbing inner cladding of aircraft
CA2645106A1 (en) * 2006-05-24 2007-11-29 Airbus Deutschland Gmbh Sandwich element for the sound-absorbing inner cladding of means of transport, especially for the sound-absorbing inner cladding of aircraft
US8065903B2 (en) * 2009-07-30 2011-11-29 Lockheed Martin Corporation Impact energy absorber for underwater applications
US8127889B1 (en) * 2009-09-15 2012-03-06 The Boeing Company Noise reduction system for structures
US8662249B2 (en) * 2009-09-25 2014-03-04 Schlumberger Technology Corporation Multi-layered sound attenuation mechanism
JP5650429B2 (ja) * 2010-04-06 2015-01-07 株式会社荏原製作所 回転電機
RU177394U1 (ru) * 2017-05-29 2018-02-20 Общество С Ограниченной Ответственностью "Пенополиуретан" Звукоизолирующая сотопластовая панель
RU201724U1 (ru) * 2020-03-03 2020-12-29 Общество с ограниченной ответственностью "МАЛАИВК" Самонесущая звукоизолирующая многослойная панель

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3961305A (en) * 1975-02-14 1976-06-01 The United States Of America As Represented By The Secretary Of The Navy Fluid for filling sonar transducers
US4421455A (en) * 1981-12-22 1983-12-20 The Garrett Corporation Duct lining

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3136380A (en) * 1959-10-15 1964-06-09 Riverside Plastics Corp Sonar dome and self-damping component thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3961305A (en) * 1975-02-14 1976-06-01 The United States Of America As Represented By The Secretary Of The Navy Fluid for filling sonar transducers
US4421455A (en) * 1981-12-22 1983-12-20 The Garrett Corporation Duct lining

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2582847A1 (fr) * 1985-05-31 1986-12-05 Vibrasonic Dispositif destine a absorber les ondes sonores
EP0292877A1 (fr) * 1987-05-25 1988-11-30 Gec Alsthom Sa Revêtement de paroi absorbant les ondes acoustiques en milieu liquide
FR2615994A1 (fr) * 1987-05-25 1988-12-02 Alsthom Revetement de paroi absorbant les ondes acoustiques en milieu liquide
US4817757A (en) * 1987-05-25 1989-04-04 Alsthom Wall covering for absorbing sound waves in a liquid medium
FR2622333A1 (fr) * 1987-10-27 1989-04-28 Thomson Csf Revetement anechoique pour ondes acoustiques
EP0317380A1 (fr) * 1987-10-27 1989-05-24 Thomson-Csf Revêtement anéchoique pour ondes acoustiques
US4883143A (en) * 1987-10-27 1989-11-28 Thomson-Csf Anechoic coating for acoustic waves
FR2656718A1 (fr) * 1989-12-28 1991-07-05 Thomson Csf Absorbeur acoustique pour milieu fluide, notamment pour milieu marin.
FR2664868A1 (fr) * 1990-07-19 1992-01-24 Bertin & Cie Revetement anechouide, en particulier pour coques de navires et de sous-marins.
WO1992001599A1 (fr) * 1990-07-19 1992-02-06 Bertin & Cie Revetement anechoide, en particulier pour coques de navires ou de sous-marins
WO1992022053A1 (en) * 1991-05-30 1992-12-10 Short Brothers Plc Noise attenuation panel
EP0897176A1 (fr) * 1997-08-14 1999-02-17 Thomson Marconi Sonar Sas Absorbeur acoustique sous-marin
FR2767410A1 (fr) * 1997-08-14 1999-02-19 Thomson Marconi Sonar Sas Absorbeur acoustique sous-marin

Also Published As

Publication number Publication date
US4560028A (en) 1985-12-24
JPS60237491A (ja) 1985-11-26
FR2562699B1 (fr) 1986-12-05
FR2562699A1 (fr) 1985-10-11
JPH059037B2 (enrdf_load_stackoverflow) 1993-02-03

Similar Documents

Publication Publication Date Title
EP0161458A1 (fr) Revetement de paroi absorbant les ondes acoustiques
Krylov Acoustic black holes: recent developments in the theory and applications
EP1488043B1 (fr) Mur antibruit
EP3411874A1 (fr) Resonateur acoustique de faible epaisseur de type mille-feuille perfore pour l'absorption ou le rayonnement acoustique tres basses frequences
EP0852050B1 (fr) Procede d'attenuation des vibrations et de l'onde de pression rayonnee par un materiau
EP0378021A1 (fr) Capteur de signaux insensible aux variations de la pression statique
EP0292877B1 (fr) Revêtement de paroi absorbant les ondes acoustiques en milieu liquide
CA3216884A1 (fr) Dispositifs perfores et vitrages les comprenant
FR2625640A1 (fr) Capteur piezo-electrique tubulaire a grande sensibilite
EP0282479B1 (fr) Procede et dispositif pour l'attenuation de la houle
EP2066843A1 (fr) Installation et procede pour l'amortissement et/ou la recuperation de l'energie de la houle
EP0897176B1 (fr) Absorbeur acoustique sous-marin
EP0740287A1 (fr) Matériau absorbant les ondes sonores, notamment en acoustique sous-marine
JP3062159B2 (ja) 水中吸音装置
FR2656718A1 (fr) Absorbeur acoustique pour milieu fluide, notamment pour milieu marin.
FR2664868A1 (fr) Revetement anechouide, en particulier pour coques de navires et de sous-marins.
FR2715244A1 (fr) Procédé et dispositif d'absorption de l'énergie d'ondes acoustiques.
WO2021224500A1 (fr) Dispositif d'absorption d'ondes sonores et vibratoires à l'émission comme à la transmission sur base de mélange contenant du silicone, application possible pour tout type de transducteur audio.
Kozhevnikova et al. Nonlinear acoustical properties of suspended sediment
FR2486932A1 (fr) Panneaux d'insonorisation speciaux pour basses frequences a inserer dans les conduits et gaines de ventilation pour former des silencieux
FR2695666A1 (fr) Procédé et dispositif destinés à atténuer la houle.
FR2615950A1 (fr) Dispositif pour l'absorption des ondes de gravite dans un fluide
JPH0771356B2 (ja) 光フアイバハイドロホン
Stuart The entrapped elasticity of a fluid‐loaded plate
Dubbelday et al. Dispersion relation for composite waveguide with application to measurements in acoustic impedance tube

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): BE CH DE FR GB IT LI NL SE

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: ALSTHOM

17P Request for examination filed

Effective date: 19860520

17Q First examination report despatched

Effective date: 19880706

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19890131

RIN1 Information on inventor provided before grant (corrected)

Inventor name: PERRET, RENE