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EP2200818A2 - Cellular-core structure for an acoustic panel - Google Patents

Cellular-core structure for an acoustic panel

Info

Publication number
EP2200818A2
EP2200818A2 EP08852512A EP08852512A EP2200818A2 EP 2200818 A2 EP2200818 A2 EP 2200818A2 EP 08852512 A EP08852512 A EP 08852512A EP 08852512 A EP08852512 A EP 08852512A EP 2200818 A2 EP2200818 A2 EP 2200818A2
Authority
EP
European Patent Office
Prior art keywords
cellular
acoustic panel
cells
acoustic
end sheets
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Withdrawn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
EP08852512A
Other languages
German (de)
French (fr)
Inventor
Laurent Valleroy
Emmanuel Drevon
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.)
Safran Nacelles SAS
Original Assignee
Aircelle 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 Aircelle SA filed Critical Aircelle SA
Publication of EP2200818A2 publication Critical patent/EP2200818A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/02—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by features of form at particular places, e.g. in edge regions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
    • B32B3/12—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/266—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/10—Properties of the layers or laminate having particular acoustical properties
    • B32B2307/102—Insulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2605/00—Vehicles
    • B32B2605/18—Aircraft
    • 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 in particular to a honeycomb core structure formed of at least one cellular unit suitable for use in an acoustic panel for a turbojet nacelle.
  • Aircraft turbojets generate significant noise pollution. There is a strong demand to reduce this pollution, especially as the turbojets used become more and more powerful.
  • the design of the nacelle surrounding a turbojet contributes to a large extent to the reduction of this noise pollution.
  • nacelles are equipped with acoustic panels to reduce the noise generated by the turbojet engine and vibration structures.
  • acoustic panels are well known structures for absorbing these noises. These panels usually comprise one or more layers of honeycomb core structures (commonly called “honeycomb” structure). These layers are generally coated on their underside, that is to say not in contact with the air flow inside the nacelle, a skin impermeable to air, called “full”, and on their upper face, that is to say in contact with the air flow inside the nacelle, a perforated skin permeable to air, called “acoustic”.
  • the acoustic panel may further comprise several layers of cellular core structures between which is inserted, for example glued, a porous or multi-perforated skin, called "septum".
  • Such panels constitute acoustic resonators suitable for
  • honeycomb core structure is made from joined honeycomb unit (s), called “honeycomb block (s)".
  • honeycomb unit is generally obtained by superimposing several sheets of metal, light alloy or composite on which are arranged punctually bonding means which adhere the sheets together at certain points, called junction pads.
  • the cellular unit thus produced is said to be in "compacted” form.
  • the unit undergoes a stretching so as to separate the leaves that remain attached between they at the junction pads.
  • the alveolar unit thus produced is said to be in the form of "expanded”.
  • the acoustic properties of the acoustic panel that is to say its rate of absorption of noise as a function of the frequency and the noise level of the noise, depend in particular on the junction of the cellular unit or units, which form a structure with alveolar soul.
  • the junction of the lateral ends of cellular units is currently carried out using a foaming glue, such as the FM 410® glue, which has a large expansion capacity.
  • Glue generally in the form of a film, is inserted between the adjacent edges of two cellular units which, during its expansion, obstructs the honeycomb cells by creating extra thicknesses at the cell walls of the junction zone. These extra thicknesses have the disadvantage of reducing the effective acoustic surface of the honeycomb structure and also of causing sudden impedance breaks which contribute to the reduction of the acoustic performance of the acoustic panel, by redistribution of the modal energy of the noise by the rotating parts, during operation of the turbojet engine.
  • honeycomb core structure is complex and does not provide a completely homogeneous acoustic treatment.
  • An object of the present invention is to provide a honeycomb core structure comprising one or more cellular units, simple to implement and having an effective attenuation of the noise induced by the operation of the turbojet engine.
  • the subject of the invention is a honeycomb core structure suitable for use in an acoustic panel for a turbojet engine nacelle comprising at least one cellular unit, each cellular unit comprising two end sheets, characterized in that the end sheets are joined together by junction pads arranged to form honeycomb cells.
  • the structure according to the invention comprises one or more alveolar units joined (s) so as not to obstruct the cellular cells.
  • the junction zone of the structure according to the invention is limited to the cellular cells formed by the junction pads and the end sheets.
  • no honeycomb cell of the structure according to the invention is obstructed totally or partially.
  • the junction zone has new cellular cells substantially filled with air, which increases the effective acoustic surface of the structure according to the invention.
  • the structure according to the invention advantageously allows an effective reduction of the noise without breaking impedance.
  • the structure of the invention offers a higher mechanical strength than the structures of the prior art. Indeed, the structure according to the invention behaves as an unassembled whole block consisting of cellular cells. According to other features of the invention, the structure according to the invention comprises one or more of the following optional features considered alone or according to all the possible combinations:
  • the junction pads consist of a material selected from metals, alloys or polymers, in particular an epoxy-based resin, which makes it possible to withstand external stresses and does not critically increase the nacelle in which it is intended to be incorporated the structure according to the invention;
  • the structure according to the invention has a surface substantially of revolution in order to optimally constitute an acoustic panel nacelle turbojet in order to mitigate noise pollution from the turbojet engine.
  • the subject of the invention is a process for preparing a honeycomb core structure according to the invention comprising at least one cellular unit, characterized in that it comprises the steps aimed at:
  • substantially expanded cellular cells By “substantially compacted form” is meant herein alveolar units in which the alveolar cells have not been formed but are likely to be formed after stretching of these cells.
  • substantially flattened alveolar cells that can be expanded after stretching.
  • stretched cellular cells By “expanded cellular cells” is meant stretched cellular cells capable of forming acoustic attenuation means.
  • the method according to the invention has the advantage of being simple to implement insofar as the alveolar unit (s) is (are) initially manipulated in their compacted form and then they are stretched from one block to another. another step in order to form the structure according to the invention.
  • the method according to the invention has the advantage of providing a honeycomb core structure which may have non-regular cellular cells.
  • the expansion means can stretch the structure resulting from step B of the process according to the invention in a non-homogeneous manner.
  • the method according to the invention comprises one or more of the following optional characteristics considered alone or according to all the possible combinations:
  • the method according to the invention also comprises a step (D) in which a perforated acoustic skin and / or a non-perforated skin is reported on at least one face of the cellular core structure obtained at the end of the step (C) for protecting the structure according to the invention and increasing the acoustic attenuation;
  • the bonding means consist of a polymer, metal or alloy used for a weld ensuring the structure according to the invention a good mechanical strength;
  • the bonding means consist of material whose position and thickness are such that these bonding means induce a non-zero space filled with air between two end sheets allowing the formation of cellular cells, these ideally hexagonal cells being able to take degraded geometries while ensuring their role of acoustic attenuation;
  • the expansion means are mechanical means capable of stretching the structure obtained at the end of step (B) in a direction substantially perpendicular or radial to the inner and outer faces for finely stretching the structure from step B to the desired shape.
  • step B 1 is attached in step B 1 alongside the end sheets so as to obtain a surface structure substantially of revolution, which allows to optimally achieve acoustic attenuation panel, in particular an acoustic panel turbojet air intake.
  • the invention relates to an acoustic panel for nacelle comprising at least one honeycomb core structure according to the invention or obtainable by the method according to the invention.
  • the acoustic panel comprises a plurality of cellular core structures arranged in layers between which is a porous or multi-perforated skin, preferably a septum.
  • the invention relates to a turbojet engine nacelle comprising an acoustic panel according to the invention.
  • FIG. 1a is a partial schematic cross section of the structure according to the invention.
  • FIG. 2 is a perspective view of one embodiment of the structure according to the invention.
  • FIGS. 3a to 3c are schematic and partial sections of embodiments of the steps of the method according to the invention.
  • FIG. 1a illustrates an embodiment of a honeycomb core structure 10 according to the invention intended to be used in an acoustic panel for a turbojet engine nacelle, not shown.
  • the structure 10 of the invention may consist of a honeycomb unit joined to itself or a plurality of honeycomb units joined together edge to edge, in particular two or three.
  • the structure 10 according to the invention consists of two cellular units 12 and 14.
  • the cellular units 12 and 14 typically comprise intermediate sheets 15 and 16 and two end sheets, one of which 18, 20 of each cellular unit 12, 14 is shown, as well as junction pads 22 and 24.
  • the end sheets 18 and 20 are joined together by the junction pads 24 arranged, particularly punctually, over extended areas or substantially continuously, so as to form cells alveolar.
  • the sheets 15 and 16 form the walls of honeycomb cells 26 whose vertices are located at the junction pads 22.
  • the junction zone 30 between the alveolar units 12 and 14 is formed of cellular cells 32 coming from the point junction of the end sheets 18 and 20 at the junction pads 24.
  • the cellular cells 32 participate, like the other cells 26 in the noise attenuation of the structure 10 according to the invention since they are not obstructed or clogged but in addition these cells alveolar 32 increase the attenuation capacity noise of the structure 10 according to the invention.
  • the alveolar cells 26 and 32 are, for example, alveolar cells of geometric shape, in particular hexagonal, or else curved.
  • the alveolar cells 26 and 32 are of regular shape.
  • the honeycomb cells 26 and 32 typically have a width d of between 3 mm and 40 mm, in particular between 8 mm and 12 mm and a height h in particular between 3 mm and 100 mm, in particular between 8 mm and 40 mm.
  • the cellular cells 26 and 32 are empty of material and typically filled with air.
  • junction pads 24 are preferably made of a material chosen from metals, alloys or polymers, in particular an epoxy-based resin.
  • the intermediate sheets 15 and 16 and the end sheets 18 and 20 are made of a material resistant to external stresses and do not critically increase the nacelle in which the structure 10 according to the invention is intended to be incorporated.
  • the intermediate sheets 15 and 16 and the end sheets 18 and 20 are made of the same material.
  • the intermediate sheets 15 and 16 and the end sheets 18 and 20 are made of a material selected from metals, light alloys and thermoplastic polymers, including aluminum, titanium and a composite.
  • the junction pads 24 may have a thickness, in particular, greater than that of the end sheets 18 and 20.
  • the end sheets 18 and 20 have a thickness substantially identical to intermediate sheets 15 and 16, in particular between 10 microns and 200 microns.
  • the thickness of the junction pads 24 is between 5 microns and 1 mm, in particular between 0.1 mm and 0.4 mm.
  • the thickness of a unit 12 and 14 corresponds to that of the structure 10 according to the invention and is in particular between 3 mm and 100 mm or between 8 mm and 40 mm.
  • the structure 10 according to the invention has a suitable form to constitute an acoustic panel turbojet nacelle to best mitigate the noise pollution from the latter.
  • the structure 10 has a substantially axis-revolution surface 34.
  • the structure 10 according to the invention is not of regular shape and is for example of non-regular "barrel" shape, namely that the radius of the cross section is not constant neither along nor radially with respect to the axis of revolution 34 of the structure 10 according to the invention.
  • This geometry typically corresponds to a turbojet air intake acoustic conduit.
  • the method according to the invention advantageously comprises three steps A, B and C, simple to implement in order to prepare the structure 10 according to the invention.
  • FIG. 3a illustrates an embodiment of step A of the method according to the invention in which at least one alveolar unit is selected, two cellular units 112 and 114 being represented here, in a substantially compacted and substantially flat form.
  • Each honeycomb unit 112 and 114 typically comprises two end sheets, one of each honeycomb unit 112, 114 is shown respectively 118, 120, intermediate sheets 115 and 116 and junction pads 122 located between the intermediate sheets 115 and 116 .
  • the end sheets 118 and 120 have a free surface 124 and 126 capable of being joined on which gluing means are intended to be arranged.
  • step B of the method according to the invention shown in FIG. 3b the end sheets 118 and 120 are joined in facing relation by means of gluing means 200 arranged on a of the end sheets 118 or 120 so as to form substantially compacted cellular cells 202.
  • the gluing means 200 may be deposited on one of the end sheets 118 or 120 punctually, over wide areas or even substantially continuously.
  • one of the two insulated units 112 or 114 may have on the free surface of its end sheet 118 or 120 to be joined gluing means previously arranged in step B.
  • the bonding means 200 are typically made of material whose position and thickness are such that these bonding means 200 induce a non-zero space 203 filled with air between two end sheets 118 and 120, which makes it possible to form alveolar cells.
  • This space 203 has a thickness substantially equal to the thickness of the bonding means 200.
  • the bonding means 200 are preferably made of polymers, metal or alloy used for welding.
  • the bonding means 200 become junction pads which delimit with the end sheets 118 and 120 substantially compacted cellular cells 202.
  • a structure 204 having an internal surface, not shown, intended to be the closest to the axis of the motor not shown, and an external face not shown, intended to be furthest from the motor axis.
  • step B the end sheets 118 and 120 are joined edge to edge so as to obtain a structure 204 of substantially circular surface, in particular substantially cylindrical or barrel-shaped surface.
  • the inner face is intended to be the closest radially to the axis of the motor not shown and the outer face intended to be furthest radially from the axis of the motor.
  • step C of the process according to the invention shown in FIG. 3c the structure 204 obtained in step B is stretched by an expansion means to form expanded cellular cells 332 in order to obtain the honeycomb core structure 310 according to the invention.
  • the expansion means are unrepresented mechanical means able to stretch the structure 204 in a direction radial or perpendicular to the internal and external faces of the structure 204.
  • the method according to the invention also comprises a step D in which a perforated acoustic skin and / or a non-perforated skin, full skin, is reported on at least one face of the structure 310 obtained at the end of step C.
  • the acoustic skin is generally perforated substantially uniformly.
  • the acoustic skin and the solid skin are usually made of a multilayer composite material consisting of a reinforcing fiber impregnated with a polymerized resin.
  • the acoustic panel may further comprise several structures 10 according to the invention or 310 obtained according to the method of the invention arranged in layers between which is a porous or multiperforated skin, preferably a septum, in order to constitute a multi-stage resonator.
  • the septum consists of a porous layer or a microperforated skin of holes having a diameter of between 0.1 mm and 1 mm.
  • the acoustic panel is then assembled by arranging the various layers, namely internal acoustic skin, structure (s) 10 according to the invention or 310 obtained (s) according to the invention, possibly septum and full skin, glued on a mold to the form required.
  • the assembly undergoes an assembly cycle so as to clamp the layers and form a sandwich assembly using for example an autoclave to polymerize the adhesives.
  • the full skin can be made and glued in one operation on the acoustic panel.

Landscapes

  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Laminated Bodies (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

The invention relates to a cellular-core structure (10) that can be used in an acoustic panel for a turbojet nacelle, comprising at least one cellular unit (12; 14), each cellular unit (12; 14) comprising two end sheets (18; 20), the end sheets (18; 20) being joined together by joining elements (24) that are placed so as to form cellular cells (32). The subject of the invention is also a method of producing such a structure, an acoustic panel comprising such a structure, and a nacelle comprising such an acoustic panel.

Description

Structure à âme alvéolaire pour panneau acoustique Honeycomb core structure for acoustic panel
La présente invention concerne notamment une structure à âme alvéolaire formée d'au moins une unité alvéolaire apte à être utilisée dans un panneau acoustique pour une nacelle de turboréacteur.The present invention relates in particular to a honeycomb core structure formed of at least one cellular unit suitable for use in an acoustic panel for a turbojet nacelle.
Les turboréacteurs d'aéronef sont générateurs d'une pollution sonore importante. Il existe une forte demande visant à réduire cette pollution, et ce d'autant plus que les turboréacteurs utilisés deviennent de plus en plus puissants. La conception de la nacelle entourant un turboréacteur contribue pour une grande partie à la réduction de cette pollution sonore.Aircraft turbojets generate significant noise pollution. There is a strong demand to reduce this pollution, especially as the turbojets used become more and more powerful. The design of the nacelle surrounding a turbojet contributes to a large extent to the reduction of this noise pollution.
Afin d'améliorer d'avantage les performances acoustiques des aéronefs, les nacelles sont dotées de panneaux acoustiques visant à atténuer les bruits générés par le turboréacteur ainsi que les vibrations des structures.To further improve the acoustic performance of aircraft, nacelles are equipped with acoustic panels to reduce the noise generated by the turbojet engine and vibration structures.
Les panneaux acoustiques sont des structures bien connues pour absorber ces bruits. Ces panneaux comportent habituellement une ou plusieurs couches de structures à âme alvéolaire (structure couramment appelée « en nid d'abeille »). Ces couches sont généralement revêtues sur leur face inférieure, c'est-à-dire non en contact avec le flux d'air à l'intérieur de la nacelle, d'une peau imperméable à l'air, dite « pleine », et sur leur face supérieure, c'est-à-dire en contact avec le flux d'air à l'intérieur de la nacelle, d'une peau perforée perméable à l'air, dite « acoustique ».Acoustic panels are well known structures for absorbing these noises. These panels usually comprise one or more layers of honeycomb core structures (commonly called "honeycomb" structure). These layers are generally coated on their underside, that is to say not in contact with the air flow inside the nacelle, a skin impermeable to air, called "full", and on their upper face, that is to say in contact with the air flow inside the nacelle, a perforated skin permeable to air, called "acoustic".
Le panneau acoustique peut comprendre en outre plusieurs couches de structures à âme alvéolaire entre lesquelles est insérée, par exemple collée, une peau poreuse ou multiperforée, dite « septum » . De tels panneaux constituent des résonateurs acoustiques aptes àThe acoustic panel may further comprise several layers of cellular core structures between which is inserted, for example glued, a porous or multi-perforated skin, called "septum". Such panels constitute acoustic resonators suitable for
« piéger » le bruit et donc à atténuer les émissions sonores en direction de l'extérieur de la nacelle."Trapping" the noise and thus to reduce noise emissions towards the outside of the nacelle.
D'une façon connue, la structure à âme alvéolaire est réalisée à partir d'unité(s) alvéolaire(s) jointes, dite(s) « bloc(s) de nids d'abeilles ». Une unité alvéolaire est obtenue généralement en superposant plusieurs feuilles de métal, d'alliage léger ou en composite sur lesquelles sont disposés ponctuellement des moyens de collage qui font adhérer les feuilles entre elles en certains points, appelés plots de jonction. L'unité alvéolaire ainsi produite est dite sous forme « compactée ». Afin de former les cellules alvéolaires, l'unité subit un étirement de sorte à séparer les feuilles qui restent jointes entre elles au niveau des plots de jonction. L'unité alvéolaire ainsi produite est dite sous forme « expansée ».In a known manner, the honeycomb core structure is made from joined honeycomb unit (s), called "honeycomb block (s)". A honeycomb unit is generally obtained by superimposing several sheets of metal, light alloy or composite on which are arranged punctually bonding means which adhere the sheets together at certain points, called junction pads. The cellular unit thus produced is said to be in "compacted" form. In order to form the alveolar cells, the unit undergoes a stretching so as to separate the leaves that remain attached between they at the junction pads. The alveolar unit thus produced is said to be in the form of "expanded".
Les propriétés acoustiques du panneau acoustique, c'est-à-dire son taux d'absorption du bruit en fonction de la fréquence et du niveau sonore du bruit, dépendent notamment de la jonction de la ou des unités alvéolaires, qui forment une structure à âme alvéolaire.The acoustic properties of the acoustic panel, that is to say its rate of absorption of noise as a function of the frequency and the noise level of the noise, depend in particular on the junction of the cellular unit or units, which form a structure with alveolar soul.
La jonction des extrémités latérales d'unités alvéolaires est couramment réalisée à l'aide d'une colle moussante, telle que la colle FM 410®, qui a une importante capacité d'expansion. De la colle, généralement sous forme de film, est insérée entre les bords adjacents de deux unités alvéolaires qui, lors de son expansion, obstrue les cellules alvéolaires en créant des surépaisseurs au niveau des cloisons des alvéoles de la zone de jonction. Ces surépaisseurs présentent l'inconvénient de diminuer la surface acoustique efficace de la structure alvéolaire et aussi de provoquer des ruptures brutales d'impédance qui contribuent à la diminution de la performance acoustique du panneau acoustique, par redistribution de l'énergie modale du bruit par les parties tournantes, lors du fonctionnement du turboréacteur.The junction of the lateral ends of cellular units is currently carried out using a foaming glue, such as the FM 410® glue, which has a large expansion capacity. Glue, generally in the form of a film, is inserted between the adjacent edges of two cellular units which, during its expansion, obstructs the honeycomb cells by creating extra thicknesses at the cell walls of the junction zone. These extra thicknesses have the disadvantage of reducing the effective acoustic surface of the honeycomb structure and also of causing sudden impedance breaks which contribute to the reduction of the acoustic performance of the acoustic panel, by redistribution of the modal energy of the noise by the rotating parts, during operation of the turbojet engine.
La mise en oeuvre d'une telle structure à âme alvéolaire est complexe et ne permet pas d'obtenir un traitement acoustique complètement homogène.The implementation of such a honeycomb core structure is complex and does not provide a completely homogeneous acoustic treatment.
Un but de la présente invention est de fournir une structure à âme alvéolaire comportant une ou plusieurs unités alvéolaires, simple à mettre en oeuvre et présentant une atténuation efficace du bruit induit par le fonctionnement du turboréacteur.An object of the present invention is to provide a honeycomb core structure comprising one or more cellular units, simple to implement and having an effective attenuation of the noise induced by the operation of the turbojet engine.
A cet effet, selon un premier aspect, l'invention a pour objet une structure à âme alvéolaire apte à être utilisée dans un panneau acoustique pour une nacelle de turboréacteur comprenant au moins une unité alvéolaire, chaque unité alvéolaire comportant deux feuilles d'extrémité, caractérisée en ce que les feuilles d'extrémité sont jointes entre elles par des plots de jonction disposés de façon à former des cellules alvéolaires.For this purpose, according to a first aspect, the subject of the invention is a honeycomb core structure suitable for use in an acoustic panel for a turbojet engine nacelle comprising at least one cellular unit, each cellular unit comprising two end sheets, characterized in that the end sheets are joined together by junction pads arranged to form honeycomb cells.
La structure selon l'invention comporte une ou plusieurs unités alvéolaires jointe(s) de manière à ne pas obstruer les cellules alvéolaires. En effet, la zone de jonction de la structure selon l'invention se limite aux cellules alvéolaires formées par les plots de jonction et les feuilles d'extrémité. De ce fait, aucune cellule alvéolaire de la structure selon l'invention n'est obstruée totalement ou partiellement. Au contraire, la zone de jonction présente de nouvelles cellules alvéolaires sensiblement remplies d'air ce qui augmente la surface acoustique efficace de la structure selon l'invention. Ainsi, la structure selon l'invention permet de façon avantageuse une diminution efficace du bruit sans rupture d'impédance.The structure according to the invention comprises one or more alveolar units joined (s) so as not to obstruct the cellular cells. Indeed, the junction zone of the structure according to the invention is limited to the cellular cells formed by the junction pads and the end sheets. As a result, no honeycomb cell of the structure according to the invention is obstructed totally or partially. On the contrary, the junction zone has new cellular cells substantially filled with air, which increases the effective acoustic surface of the structure according to the invention. Thus, the structure according to the invention advantageously allows an effective reduction of the noise without breaking impedance.
D'un point de vue mécanique, la structure de l'invention offre une résistance mécanique supérieure à celle des structures de la technique antérieure. En effet, la structure selon l'invention se comporte comme un bloc entier non jointe constitué de cellules alvéolaires. Selon d'autres caractéristiques de l'invention, la structure selon l'invention comporte l'une ou plusieurs des caractéristiques optionnelles suivantes considérées seules ou selon toutes les combinaisons possibles:From a mechanical point of view, the structure of the invention offers a higher mechanical strength than the structures of the prior art. Indeed, the structure according to the invention behaves as an unassembled whole block consisting of cellular cells. According to other features of the invention, the structure according to the invention comprises one or more of the following optional features considered alone or according to all the possible combinations:
-les plots de jonction sont constitués d'une matière choisie parmi les métaux, les alliages ou les polymères, notamment une résine à base époxyde, permettant de résister aux contraintes extérieures et n'alourdissant pas de manière critique la nacelle dans laquelle est destinée à être incorporée la structure selon l'invention ;the junction pads consist of a material selected from metals, alloys or polymers, in particular an epoxy-based resin, which makes it possible to withstand external stresses and does not critically increase the nacelle in which it is intended to be incorporated the structure according to the invention;
-la structure selon l'invention présente une surface sensiblement de révolution afin de constituer de manière optimale un panneau acoustique de nacelle de turboréacteur dans le but d'atténuer les nuisances acoustiques issues du turboréacteur.the structure according to the invention has a surface substantially of revolution in order to optimally constitute an acoustic panel nacelle turbojet in order to mitigate noise pollution from the turbojet engine.
Selon un deuxième aspect, l'invention a pour objet un procédé de préparation d'une structure à âme alvéolaire selon l'invention comprenant au moins une unité alvéolaire, caractérisé en ce qu'il comporte les étapes visant à :According to a second aspect, the subject of the invention is a process for preparing a honeycomb core structure according to the invention comprising at least one cellular unit, characterized in that it comprises the steps aimed at:
A- sélectionner au moins une unité alvéolaire sous une forme sensiblement compactée et sensiblement plane, chaque unité alvéolaire comportant deux feuilles d'extrémité ;A- selecting at least one cellular unit in a substantially compacted and substantially planar form, each alveolar unit having two end sheets;
B- joindre les feuilles d'extrémité disposées en vis-à-vis par l'intermédiaire de moyens de collage disposés sur une feuille d'extrémité de façon à former des cellules alvéolaires sensiblement compactées ;B- joining the end sheets disposed vis-a-vis via bonding means disposed on an end sheet so as to form substantially compacted cells cells;
C- étirer la structure obtenue à l'issue de l'étape (B) par des moyens d'expansion pour former les cellules alvéolaires sensiblement expansées. Par «forme sensiblement compactée », on entend ici des unités alvéolaires dans lesquelles les cellules alvéolaires n'ont pas été formées mais sont susceptibles de l'être après étirement de ces cellules.C-stretching the structure obtained at the end of step (B) by expansion means to form the substantially expanded cellular cells. By "substantially compacted form" is meant herein alveolar units in which the alveolar cells have not been formed but are likely to be formed after stretching of these cells.
Par « cellules alvéolaires compactées », on entend ici des cellules alvéolaires sensiblement aplaties susceptibles d'être expansées après étirement.By "compacted alveolar cells" is meant herein substantially flattened alveolar cells that can be expanded after stretching.
Par « cellules alvéolaires expansées », on entend ici des cellules alvéolaires étirées aptes à former des moyens d'atténuation acoustique.By "expanded cellular cells" is meant stretched cellular cells capable of forming acoustic attenuation means.
Le procédé selon l'invention présente l'avantage d'être simple à mettre en oeuvre dans la mesure où la ou les unités alvéolaires est(sont) dans un premier temps manipulées sous leur forme compactée puis elles sont étirées d'un bloc dans une autre étape afin de former la structure selon l'invention.The method according to the invention has the advantage of being simple to implement insofar as the alveolar unit (s) is (are) initially manipulated in their compacted form and then they are stretched from one block to another. another step in order to form the structure according to the invention.
De plus, le procédé selon l'invention présente l'avantage de fournir une structure à âme alvéolaire qui peut présenter des cellules alvéolaires non régulières. En effet, les moyens d'expansion peuvent étirer la structure issue de l'étape B du procédé selon l'invention de façon non homogène.In addition, the method according to the invention has the advantage of providing a honeycomb core structure which may have non-regular cellular cells. Indeed, the expansion means can stretch the structure resulting from step B of the process according to the invention in a non-homogeneous manner.
Selon d'autres caractéristiques de l'invention, le procédé selon l'invention comporte l'une ou plusieurs des caractéristiques optionnelles suivantes considérées seules ou selon toutes les combinaisons possibles:According to other characteristics of the invention, the method according to the invention comprises one or more of the following optional characteristics considered alone or according to all the possible combinations:
- le procédé selon l'invention comprend en outre une étape (D) où l'on rapporte une peau acoustique perforée et/ou une peau non perforée sur au moins une face de la structure à âme alvéolaire obtenue à l'issue de l'étape (C) permettant de protéger la structure selon l'invention et d'augmenter l'atténuation acoustique ;the method according to the invention also comprises a step (D) in which a perforated acoustic skin and / or a non-perforated skin is reported on at least one face of the cellular core structure obtained at the end of the step (C) for protecting the structure according to the invention and increasing the acoustic attenuation;
- les moyens de collage sont constitués d'un polymère, de métal ou d'alliage utilisés pour une soudure assurant à la structure selon l'invention une bonne résistance mécanique ;- The bonding means consist of a polymer, metal or alloy used for a weld ensuring the structure according to the invention a good mechanical strength;
- les moyens de collage sont constitués de matière dont la position et l'épaisseur sont telles que ces moyens de collage induisent un espace non nul rempli d'air entre deux feuilles d'extrémité permettant la formation de cellules alvéolaires, ces cellules idéalement hexagonales pouvant prendre des géométries dégradés tout en assurant leur rôle d'atténuation acoustique;the bonding means consist of material whose position and thickness are such that these bonding means induce a non-zero space filled with air between two end sheets allowing the formation of cellular cells, these ideally hexagonal cells being able to take degraded geometries while ensuring their role of acoustic attenuation;
- les moyens d'expansion sont des moyens mécaniques aptes à étirer la structure obtenue à l'issue de l'étape (B) suivant une direction sensiblement perpendiculaire ou radiale aux faces internes et externes permettant d'étirer finement la structure issue de l'étape B à la forme voulue.the expansion means are mechanical means capable of stretching the structure obtained at the end of step (B) in a direction substantially perpendicular or radial to the inner and outer faces for finely stretching the structure from step B to the desired shape.
- on joint, dans l'étape B1 bord à bord les feuilles d'extrémité de façon à obtenir une structure de surface sensiblement de révolution, ce qui permet de réaliser de manière optimale un panneau d'atténuation acoustique, en particulier un panneau acoustique d'entrée d'air de turboréacteur.- is attached in step B 1 alongside the end sheets so as to obtain a surface structure substantially of revolution, which allows to optimally achieve acoustic attenuation panel, in particular an acoustic panel turbojet air intake.
Selon un troisième aspect, l'invention a pour objet un panneau acoustique pour nacelle comprenant au moins une structure à âme alvéolaire selon l'invention ou susceptible d'être obtenue par le procédé selon l'invention. Selon un mode de réalisation préféré, le panneau acoustique comprend plusieurs structures à âme alvéolaire disposées en couches entre lesquelles se situe une peau poreuse ou multiperforée, de préférence un septum.According to a third aspect, the invention relates to an acoustic panel for nacelle comprising at least one honeycomb core structure according to the invention or obtainable by the method according to the invention. According to a preferred embodiment, the acoustic panel comprises a plurality of cellular core structures arranged in layers between which is a porous or multi-perforated skin, preferably a septum.
Selon un quatrième aspect, l'invention a pour objet une nacelle de turboréacteur comprenant un panneau acoustique selon l'invention.According to a fourth aspect, the invention relates to a turbojet engine nacelle comprising an acoustic panel according to the invention.
L'invention sera davantage comprise à la lecture de la description non limitative qui va suivre, faite en référence aux figures ci-dessous annexées :The invention will be better understood on reading the following nonlimiting description, with reference to the appended figures below:
- la figure 1a est une coupe transversale schématique partielle de la structure selon l'invention ;- Figure 1a is a partial schematic cross section of the structure according to the invention;
- la figure 1b est un agrandissement de la zone Z de la figure 1a ; -la figure 2 est une vue en perspective d'un mode de réalisation de la structure selon l'invention ;- Figure 1b is an enlargement of the zone Z of Figure 1a; FIG. 2 is a perspective view of one embodiment of the structure according to the invention;
-les figures 3a à 3c sont des coupes schématiques et partielles de modes de réalisation des étapes du procédé selon l'invention.FIGS. 3a to 3c are schematic and partial sections of embodiments of the steps of the method according to the invention.
La figure 1a illustre un mode de réalisation d'une structure à âme alvéolaire 10 selon l'invention destinée à être utilisée dans un panneau acoustique pour une nacelle de turboréacteur, non représentés.FIG. 1a illustrates an embodiment of a honeycomb core structure 10 according to the invention intended to be used in an acoustic panel for a turbojet engine nacelle, not shown.
La structure 10 de l'invention peut être constituée d'une unité alvéolaire jointe sur elle-même ou d'une pluralité d'unités alvéolaires jointes entre elles bord à bord, notamment deux ou trois.The structure 10 of the invention may consist of a honeycomb unit joined to itself or a plurality of honeycomb units joined together edge to edge, in particular two or three.
Selon le mode de réalisation représenté à la figure 1 a, la structure 10 selon l'invention est constituée de deux unités alvéolaires 12 et 14.According to the embodiment represented in FIG. 1a, the structure 10 according to the invention consists of two cellular units 12 and 14.
Les unités alvéolaires 12 et 14 comportent typiquement des feuilles intermédiaires 15 et 16 et deux feuilles d'extrémité, dont une 18, 20 de chaque unité alvéolaire 12, 14 est représentée, ainsi que des plots de jonction 22 et 24. Les feuilles d'extrémité 18 et 20 sont jointes entre elles par les plots de jonction 24 disposés, notamment ponctuellement, sur des zones étendues voire sensiblement continuement, de façon à former des cellules alvéolaires. De façon générale, les feuilles 15 et 16 forment les parois de cellules alvéolaires 26 dont les sommets se situent au niveau des plots de jonction 22.The cellular units 12 and 14 typically comprise intermediate sheets 15 and 16 and two end sheets, one of which 18, 20 of each cellular unit 12, 14 is shown, as well as junction pads 22 and 24. The end sheets 18 and 20 are joined together by the junction pads 24 arranged, particularly punctually, over extended areas or substantially continuously, so as to form cells alveolar. In general, the sheets 15 and 16 form the walls of honeycomb cells 26 whose vertices are located at the junction pads 22.
Comme illustré à la figure 1b, la zone de jonction 30 entre les unités alvéolaires 12 et 14 est formée de cellules alvéolaires 32 provenant de la jonction ponctuelle des feuilles d'extrémité 18 et 20 au niveau des plots de jonction 24. Ainsi de façon avantageuse, non seulement les cellules alvéolaires 32 participent comme les autres cellules alvéolaires 26 à l'atténuation du bruit de la structure 10 selon l'invention puisqu'elles ne sont ni obstruées ni bouchées mais en plus ces cellules alvéolaires 32 augmentent la capacité d'atténuation du bruit de la structure 10 selon l'invention.As illustrated in FIG. 1b, the junction zone 30 between the alveolar units 12 and 14 is formed of cellular cells 32 coming from the point junction of the end sheets 18 and 20 at the junction pads 24. Thus advantageously , not only the cellular cells 32 participate, like the other cells 26 in the noise attenuation of the structure 10 according to the invention since they are not obstructed or clogged but in addition these cells alveolar 32 increase the attenuation capacity noise of the structure 10 according to the invention.
Les cellules alvéolaires 26 et 32 sont par exemple des cellules alvéolaires de forme géométrique, notamment hexagonale, ou encore courbe.The alveolar cells 26 and 32 are, for example, alveolar cells of geometric shape, in particular hexagonal, or else curved.
Selon un mode de réalisation, les cellules alvéolaires 26 et 32 sont de forme régulière. Les cellules alvéolaires 26 et 32 ont typiquement une largeur d comprise entre 3 mm et 40 mm, notamment entre 8 mm et 12 mm et une hauteur h notamment comprise entre 3 mm et 100 mm, notamment entre 8 mm et 40 mm.According to one embodiment, the alveolar cells 26 and 32 are of regular shape. The honeycomb cells 26 and 32 typically have a width d of between 3 mm and 40 mm, in particular between 8 mm and 12 mm and a height h in particular between 3 mm and 100 mm, in particular between 8 mm and 40 mm.
De façon générale, les cellules alvéolaires 26 et 32 sont vides de matière et typiquement remplies d'air.In general, the cellular cells 26 and 32 are empty of material and typically filled with air.
Les plots de jonction 24 sont préférentiellement constitués d'une matière choisie parmi les métaux, les alliages ou les polymères, notamment une résine à base époxyde.The junction pads 24 are preferably made of a material chosen from metals, alloys or polymers, in particular an epoxy-based resin.
Les feuilles intermédiaires 15 et 16 et les feuilles d'extrémité 18 et 20 sont réalisées dans une matière résistant aux contraintes extérieures et n'alourdissant pas de manière critique la nacelle dans laquelle la structure 10 selon l'invention est destinée à être incorporée. Selon un mode de réalisation intéressant, les feuilles intermédiaires 15 et 16 et les feuilles d'extrémité 18 et 20 sont constituées de la même matière. De manière préférentielle, les feuilles intermédiaires 15 et 16 et les feuilles d'extrémité 18 et 20 sont constituées dans une matière choisie parmi les métaux, les alliages légers et les polymères thermoplastiques, notamment l'aluminium, le titane et un composite. Par ailleurs, les plots de jonction 24 peuvent avoir une épaisseur notamment supérieure à celle des feuilles d'extrémité 18 et 20. Selon un mode de réalisation, les feuilles d'extrémité 18 et 20 ont une épaisseur sensiblement identique aux feuilles intermédiaires 15 et 16, notamment comprise entre 10 μm et 200 μm.The intermediate sheets 15 and 16 and the end sheets 18 and 20 are made of a material resistant to external stresses and do not critically increase the nacelle in which the structure 10 according to the invention is intended to be incorporated. According to an interesting embodiment, the intermediate sheets 15 and 16 and the end sheets 18 and 20 are made of the same material. Preferably, the intermediate sheets 15 and 16 and the end sheets 18 and 20 are made of a material selected from metals, light alloys and thermoplastic polymers, including aluminum, titanium and a composite. Moreover, the junction pads 24 may have a thickness, in particular, greater than that of the end sheets 18 and 20. embodiment, the end sheets 18 and 20 have a thickness substantially identical to intermediate sheets 15 and 16, in particular between 10 microns and 200 microns.
Typiquement, l'épaisseur des plots de jonction 24 est comprise entre 5 μm et 1 mm, notamment entre 0,1 mm et 0,4 mm.Typically, the thickness of the junction pads 24 is between 5 microns and 1 mm, in particular between 0.1 mm and 0.4 mm.
Typiquement, l'épaisseur d'une unité 12 et 14 correspond à celle de la structure 10 selon l'invention et est notamment comprise entre 3 mm et 100 mm ou encore entre 8 mm et 40 mm.Typically, the thickness of a unit 12 and 14 corresponds to that of the structure 10 according to the invention and is in particular between 3 mm and 100 mm or between 8 mm and 40 mm.
De façon générale, la structure 10 selon l'invention a une forme adéquate pour constituer un panneau acoustique de nacelle de turboréacteur afin d'atténuer au mieux les nuisances acoustiques issues de ce dernier. Selon le mode de réalisation représenté à la figure 2, la structure 10 présente une surface sensiblement de révolution d'axe 34. Selon d'autres modes de réalisation non représentés, la structure 10 selon l'invention n'est pas de forme régulière et est par exemple de forme « tonneau » non régulier, à savoir que le rayon de la section transversale n'est pas constant ni le long, ni radialement par rapport à l'axe de révolution 34 de la structure 10 selon l'invention. Cette géométrie correspond typiquement à un conduit acoustique d'entrée d'air de turboréacteur. Le procédé selon l'invention comporte avantageusement trois étapes A, B et C, simples à mettre en oeuvre afin de préparer la structure 10 selon l'invention.In general, the structure 10 according to the invention has a suitable form to constitute an acoustic panel turbojet nacelle to best mitigate the noise pollution from the latter. According to the embodiment shown in FIG. 2, the structure 10 has a substantially axis-revolution surface 34. According to other embodiments that are not shown, the structure 10 according to the invention is not of regular shape and is for example of non-regular "barrel" shape, namely that the radius of the cross section is not constant neither along nor radially with respect to the axis of revolution 34 of the structure 10 according to the invention. This geometry typically corresponds to a turbojet air intake acoustic conduit. The method according to the invention advantageously comprises three steps A, B and C, simple to implement in order to prepare the structure 10 according to the invention.
Ainsi, la figure 3a illustre un mode de réalisation de l'étape A du procédé selon l'invention dans laquelle on sélectionne au moins une unité alvéolaire, deux unités alvéolaires 112 et 114 étant ici représentées, sous une forme sensiblement compactée et sensiblement plane. Chaque unité alvéolaire 112 et 114 comporte typiquement deux feuilles d'extrémité, dont une de chaque unité alvéolaire 112, 114 est représentée respectivement 118, 120, des feuilles intermédiaires 115 et 116 et des plots de jonction 122 situés entre les feuilles intermédiaires 115 et 116.Thus, FIG. 3a illustrates an embodiment of step A of the method according to the invention in which at least one alveolar unit is selected, two cellular units 112 and 114 being represented here, in a substantially compacted and substantially flat form. Each honeycomb unit 112 and 114 typically comprises two end sheets, one of each honeycomb unit 112, 114 is shown respectively 118, 120, intermediate sheets 115 and 116 and junction pads 122 located between the intermediate sheets 115 and 116 .
Les feuilles d'extrémité 118 et 120 ont une surface libre 124 et 126 apte à être jointe sur laquelle des moyens de collage sont destinés à être disposés.The end sheets 118 and 120 have a free surface 124 and 126 capable of being joined on which gluing means are intended to be arranged.
Dans un mode de réalisation de l'étape B du procédé selon l'invention représenté à la figure 3b, on joint les feuilles d'extrémité 118 et 120 en vis-à-vis par l'intermédiaire de moyens de collage 200 disposés sur une des feuilles d'extrémité 118 ou 120 de façon à former des cellules alvéolaires sensiblement compactées 202. A titre d'exemple, les moyens de collage 200 peuvent être déposés sur une des feuilles d'extrémité 118 ou 120 ponctuellement, sur des zones étendues voire sensiblement continuement. Selon un mode de réalisation non représenté, une des deux unités isolées 112 ou 114 peut avoir sur la surface libre de sa feuille d'extrémité 118 ou 120 destinée à être jointe des moyens de collage préalablement disposés à l'étape B.In one embodiment of step B of the method according to the invention shown in FIG. 3b, the end sheets 118 and 120 are joined in facing relation by means of gluing means 200 arranged on a of the end sheets 118 or 120 so as to form substantially compacted cellular cells 202. By way of example, the gluing means 200 may be deposited on one of the end sheets 118 or 120 punctually, over wide areas or even substantially continuously. According to an embodiment not shown, one of the two insulated units 112 or 114 may have on the free surface of its end sheet 118 or 120 to be joined gluing means previously arranged in step B.
Les moyens de collage 200 sont typiquement constitués de matière dont la position et l'épaisseur sont telles que ces moyens de collage 200 induisent un espace 203 non nul rempli d'air entre deux feuilles d'extrémité 118 et 120, ce qui permet de former des cellules alvéolaires. Cet espace 203 a une épaisseur sensiblement égale à l'épaisseur des moyens de collage 200. Les moyens de collage 200 sont constitués préférentiellement de polymères, de métal ou d'alliage utilisé pour une soudure.The bonding means 200 are typically made of material whose position and thickness are such that these bonding means 200 induce a non-zero space 203 filled with air between two end sheets 118 and 120, which makes it possible to form alveolar cells. This space 203 has a thickness substantially equal to the thickness of the bonding means 200. The bonding means 200 are preferably made of polymers, metal or alloy used for welding.
A la fin du collage, les moyens de collage 200 deviennent des plots de jonction qui délimitent avec les feuilles d'extrémité 118 et 120 des cellules alvéolaires sensiblement compactées 202.At the end of the bonding, the bonding means 200 become junction pads which delimit with the end sheets 118 and 120 substantially compacted cellular cells 202.
On obtient à l'issue de cette étape B une structure 204 comportant une face interne non représentée, destinée à être la plus proche de l'axe du moteur non représenté, et une face externe non représentée, destinée à être la plus éloignée de l'axe du moteur.At the end of this step B, a structure 204 having an internal surface, not shown, intended to be the closest to the axis of the motor not shown, and an external face not shown, intended to be furthest from the motor axis.
Selon un mode de réalisation préférentiel, on joint, dans l'étape B, bord à bord les feuilles d'extrémité 118 et 120 de façon à obtenir une structure 204 de surface sensiblement de révolution, notamment sensiblement cylindrique ou de forme tonneau. Dans le cas où la structure 204 est de surface de révolution, la face interne est destinée à être la plus proche radialement de l'axe du moteur non représenté et la face externe destinée à être la plus éloignée radialement de l'axe du moteur. Dans un mode de réalisation de l'étape C du procédé selon l'invention représenté à la figure 3c, on étire la structure 204 obtenue à l'étape B par un moyen d'expansion pour former les cellules alvéolaires expansées 332 afin d'obtenir la structure 310 à âme alvéolaire selon l'invention. D'une manière préférentielle, les moyens d'expansion sont des moyens mécaniques non représentés aptes à étirer la structure 204 suivant une direction radiale ou perpendiculaire aux faces internes et externes de la structure 204. Ainsi, il est possible d'étirer de manière non uniforme la structure 204 de sorte à avoir des cellules alvéolaires 332 de taille différente et ce, dans le but de constituer une âme alvéolaire monobloc de surface non développable, typiquement appliquée à un conduit acoustique d'entrée d'air de turboréacteur. Selon un mode de réalisation préférentiel non représenté, le procédé selon l'invention comprend en outre une étape D où l'on rapporte une peau acoustique perforée et/ou une peau non perforée, peau pleine, sur au moins une face de la structure 310 obtenue à l'issue de l'étape C.According to a preferred embodiment, in step B, the end sheets 118 and 120 are joined edge to edge so as to obtain a structure 204 of substantially circular surface, in particular substantially cylindrical or barrel-shaped surface. In the case where the structure 204 is surface of revolution, the inner face is intended to be the closest radially to the axis of the motor not shown and the outer face intended to be furthest radially from the axis of the motor. In one embodiment of step C of the process according to the invention shown in FIG. 3c, the structure 204 obtained in step B is stretched by an expansion means to form expanded cellular cells 332 in order to obtain the honeycomb core structure 310 according to the invention. In a preferential manner, the expansion means are unrepresented mechanical means able to stretch the structure 204 in a direction radial or perpendicular to the internal and external faces of the structure 204. Thus, it is possible to stretch the structure 204 in a non-uniform manner so as to have alveolar cells 332 of different size, with the aim of constituting a one-piece cellular core of non-developable surface, typically applied to an acoustic duct. turbojet air inlet. According to a preferred embodiment, not shown, the method according to the invention also comprises a step D in which a perforated acoustic skin and / or a non-perforated skin, full skin, is reported on at least one face of the structure 310 obtained at the end of step C.
La peau acoustique est généralement perforée de manière sensiblement uniforme.The acoustic skin is generally perforated substantially uniformly.
La peau acoustique et la peau pleine sont habituellement en matériau composite multicouche constitué d'une fibre renfort imprégnée d'une résine polymérisée.The acoustic skin and the solid skin are usually made of a multilayer composite material consisting of a reinforcing fiber impregnated with a polymerized resin.
De plus, le panneau acoustique peut en outre comprendre plusieurs structures 10 selon l'invention ou 310 obtenue selon le procédé de l'invention disposées en couches entre lesquelles se situe une peau poreuse ou multiperforée, préférentiellement un septum, dans le but de constituer un résonateur à étages multiples.In addition, the acoustic panel may further comprise several structures 10 according to the invention or 310 obtained according to the method of the invention arranged in layers between which is a porous or multiperforated skin, preferably a septum, in order to constitute a multi-stage resonator.
Généralement, le septum est constitué d'une couche poreuse ou d'une peau microperforée de trous possédant un diamètre compris entre 0,1 mm et 1 mm.Generally, the septum consists of a porous layer or a microperforated skin of holes having a diameter of between 0.1 mm and 1 mm.
Le panneau acoustique est ensuite assemblé en disposant les différentes couches, à savoir peau acoustique interne, structure(s) 10 selon l'invention ou 310 obtenue(s) selon l'invention, éventuellement septum et peau pleine, encollées sur un moule à la forme requise. L'ensemble subit un cycle d'assemblage de manière à serrer les couches et à former un ensemble sandwich solidaire en utilisant par exemple un autoclave pour polymériser les adhésifs. La peau pleine peut être réalisée et collée en une seule opération sur le panneau acoustique. The acoustic panel is then assembled by arranging the various layers, namely internal acoustic skin, structure (s) 10 according to the invention or 310 obtained (s) according to the invention, possibly septum and full skin, glued on a mold to the form required. The assembly undergoes an assembly cycle so as to clamp the layers and form a sandwich assembly using for example an autoclave to polymerize the adhesives. The full skin can be made and glued in one operation on the acoustic panel.

Claims

REVENDICATIONS
1. Structure (10 ; 310) à âme alvéolaire apte à être utilisée dans un panneau acoustique pour une nacelle de turboréacteur comprenant au moins une unité alvéolaire (12 ; 14 ; 112 ;114), chaque unité alvéolaire (12 ; 14 ; 112 ; 114) comportant deux feuilles d'extrémité (18 ; 20 ; 118 ; 120), caractérisée en ce que les feuilles d'extrémité (18 ; 20 ; 118 ; 120) sont jointes entre elles par des plots de jonction (24) disposés de façon à former des cellules alvéolaires (32 ; 332). 1. Structure (10; 310) with a cellular core suitable for use in an acoustic panel for a turbojet engine nacelle comprising at least one cellular unit (12; 14; 112; 114), each cellular unit (12; 14; 112; 114) having two end sheets (18; 20; 118; 120), characterized in that the end sheets (18; 20; 118; 120) are joined together by junction pads (24) arranged to form alveolar cells (32; 332).
2. Structure (10 ; 310) selon la revendication précédente, caractérisée en ce que les plots de jonction (24) sont constitués d'une matière choisie parmi les métaux, les alliages ou les polymères, notamment une résine à base époxyde.2. Structure (10; 310) according to the preceding claim, characterized in that the junction pads (24) consist of a material selected from metals, alloys or polymers, including an epoxy resin.
3. Structure (10 ; 310) selon l'une quelconque des revendications précédentes, caractérisée en ce qu'elle présente une surface sensiblement de révolution.3. Structure (10; 310) according to any one of the preceding claims, characterized in that it has a surface substantially of revolution.
4. Procédé de préparation d'une structure (310) à âme alvéolaire selon l'une quelconque des revendications précédentes comprenant au moins une unité alvéolaire (112 ; 114), caractérisé en ce qu'il comporte les étapes visant à :4. A method for preparing a honeycomb core structure 310 comprising at least one cellular unit 112, 114, comprising the steps of:
A- sélectionner au moins une unité alvéolaire (112 ; 114) sous une forme sensiblement compactée et sensiblement plane, chaque unité alvéolaire (112 ; 114) comportant deux feuilles d'extrémité (118 ; 120) ;A- selecting at least one cellular unit (112; 114) in a substantially compacted and substantially planar form, each cellular unit (112; 114) having two end sheets (118; 120);
B- joindre les feuilles d'extrémité (118 ; 120) disposées en vis- à-vis par l'intermédiaire de moyens de collage (200) disposés sur une feuille d'extrémité (118) de façon à former des cellules alvéolaires sensiblement compactées (202) ;B- joining the end sheets (118; 120) arranged facing each other by means of gluing means (200) arranged on an end sheet (118) so as to form substantially compacted honeycomb cells (202);
C- étirer la structure (204) obtenue à l'issue de l'étape (B) par des moyens d'expansion pour former les cellules alvéolaires sensiblement expansées (332).C-stretching the structure (204) obtained at the end of step (B) by expansion means to form the substantially expanded cellular cells (332).
5. Procédé selon la revendication précédente, caractérisé en ce qu'il comprend en outre une étape (D) où l'on rapporte une peau acoustique perforée et/ou une peau non perforée sur au moins une face de la structure à âme alvéolaire (310) obtenue à l'issue de l'étape (C). 5. Method according to the preceding claim, characterized in that it further comprises a step (D) where there is reported perforated acoustic skin and / or non-perforated skin on at least one face of the honeycomb core structure ( 310) obtained at the end of step (C).
6. Procédé selon la revendication 4 ou 5, caractérisé en ce que les moyens de collage (200) sont constitués d'un polymère, de métal ou d'alliage utilisés pour une soudure.6. Method according to claim 4 or 5, characterized in that the bonding means (200) consist of a polymer, metal or alloy used for welding.
7. Procédé selon l'une quelconque des revendications 4 à 6, caractérisé en ce que les moyens de collage (200) sont constitués de matière dont la position et l'épaisseur sont telles que ces moyens de collage (200) induisent un espace (203) non nul rempli d'air entre deux feuilles d'extrémité (118 ;120).7. Method according to any one of claims 4 to 6, characterized in that the bonding means (200) consist of material whose position and thickness are such that these bonding means (200) induce a space ( 203) filled with air between two end sheets (118; 120).
8. Procédé selon l'une quelconque des revendications 4 à 7, caractérisé en ce que les moyens d'expansion sont des moyens mécaniques aptes à étirer le structure (204) obtenue à l'issue de l'étape (B) suivant une direction sensiblement perpendiculaire ou radiale aux faces internes et externes.8. Method according to any one of claims 4 to 7, characterized in that the expansion means are mechanical means able to stretch the structure (204) obtained at the end of step (B) in a direction substantially perpendicular or radial to the inner and outer faces.
9. Procédé selon l'une quelconque des revendications 4 à 8, caractérisé en ce que l'on joint, dans l'étape B, bord à bord les feuilles d'extrémité (118 ; 120) de façon à obtenir une structure (204) de surface sensiblement de révolution.9. Method according to any one of claims 4 to 8, characterized in that is joined, in step B, edge to edge end sheets (118; 120) so as to obtain a structure (204; ) of substantially revolution surface.
10. Panneau acoustique pour nacelle comprenant au moins une structure (10 ; 310) à âme alvéolaire selon l'une quelconque des revendications précédentes ou susceptible d'être obtenue par le procédé selon l'une quelconque des revendications 4 à 9.Acoustic panel for a nacelle comprising at least one cellular core structure (10; 310) according to any one of the preceding claims or obtainable by the method according to any one of claims 4 to 9.
11. Panneau acoustique selon la revendication précédente, caractérisé en ce qu'il comprend plusieurs structures à âme alvéolaire (10 ; 310) disposées en couches entre lesquelles se situe une peau poreuse ou multiperforée, de préférence un septum.11. Acoustic panel according to the preceding claim, characterized in that it comprises a plurality of honeycomb core structures (10; 310) arranged in layers between which is a porous or multi-perforated skin, preferably a septum.
12. Nacelle de turboréacteur comprenant un panneau acoustique, caractérisé en ce que le panneau acoustique est selon la revendication 10 ou 11. 12. Turbojet engine nacelle comprising an acoustic panel, characterized in that the acoustic panel is according to claim 10 or 11.
EP08852512A 2007-10-16 2008-09-10 Cellular-core structure for an acoustic panel Withdrawn EP2200818A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0707247A FR2922152B1 (en) 2007-10-16 2007-10-16 ALVEOLAR STRUCTURE FOR ACOUSTIC PANEL
PCT/FR2008/001263 WO2009066036A2 (en) 2007-10-16 2008-09-10 Cellular-core structure for an acoustic panel

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EP2200818A2 true EP2200818A2 (en) 2010-06-30

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US (1) US8245815B2 (en)
EP (1) EP2200818A2 (en)
CN (1) CN101827702B (en)
BR (1) BRPI0818630A2 (en)
CA (1) CA2700183A1 (en)
FR (1) FR2922152B1 (en)
RU (1) RU2477223C2 (en)
WO (1) WO2009066036A2 (en)

Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2961175B1 (en) 2010-06-14 2013-01-04 Aircelle Sa TURBOREACTOR NACELLE
DE102011008922A1 (en) * 2011-01-19 2012-07-19 Rolls-Royce Deutschland Ltd. & Co. Kg Method for producing a sound absorber, in particular for a gas turbine exhaust cone
FR2975943B1 (en) * 2011-06-01 2013-05-17 Aircelle Sa METHOD FOR MANUFACTURING AN ACOUSTICAL ATTENUATION PANEL
US8607924B2 (en) * 2011-09-08 2013-12-17 Hexcel Corporation Anchoring of septums in acoustic honeycomb
US9168716B2 (en) * 2012-09-14 2015-10-27 The Boeing Company Metallic sandwich structure having small bend radius
US9476359B2 (en) 2014-04-11 2016-10-25 Rohr, Inc. Acoustic liner
US9592918B2 (en) 2014-06-23 2017-03-14 Rohr, Inc. Acoustic liner
US9931825B2 (en) 2014-07-09 2018-04-03 The Boeing Company Septumization of cellular cores
DE102014218350A1 (en) 2014-09-12 2016-03-17 Rolls-Royce Deutschland Ltd & Co Kg Sound-absorbing arrangement for an engine nacelle and engine nacelle with such an arrangement
GB2531808A (en) 2014-11-03 2016-05-04 Short Brothers Plc Methods and precursors for manufacturing a perforated composite part
RU2579744C1 (en) * 2014-11-14 2016-04-10 Александр Ливиевич Ураков Cranial implant-heat insulation material
US9761216B2 (en) 2016-02-10 2017-09-12 Rohr, Inc. Acoustic panel with angled corrugated core structures
US9764818B2 (en) 2016-02-10 2017-09-19 Rohr, Inc. Structural, cellular core with corrugated support walls
US10414481B2 (en) 2017-02-14 2019-09-17 Rohr, Inc. Method for forming a structural panel
US10525636B2 (en) 2017-06-19 2020-01-07 Rohr, Inc. Process for forming a fiber-reinforced composite structure
US10695986B2 (en) 2017-08-22 2020-06-30 Rohr, Inc. Method for forming a structural panel
FR3070674B1 (en) * 2017-09-06 2019-09-13 Safran Nacelles INTEGRATION WITH ACOUSTIC LEVER DEGIVREE
US10906659B2 (en) 2018-04-03 2021-02-02 Rohr, Inc. Structured panel with structural reinforcement(s)
GB201816335D0 (en) 2018-10-08 2018-11-28 Rolls Royce Plc Sound absorber
CN109175569A (en) * 2018-11-08 2019-01-11 中国航空制造技术研究院 A kind of preparation method of metal honeycomb core body
US11242822B2 (en) 2018-12-14 2022-02-08 Rohr, Inc. Structured panel with multi-panel structure(s)
US11398214B2 (en) 2018-12-14 2022-07-26 Rohr, Inc. Forming a structured panel with one or more structural reinforcements
US11260641B2 (en) 2019-05-10 2022-03-01 American Honda Motor Co., Inc. Apparatus for reticulation of adhesive and methods of use thereof
US11572850B2 (en) 2019-06-04 2023-02-07 Rohr, Inc. Acoustic panel with one or more structural stiffeners
FR3107856B1 (en) * 2020-03-04 2022-02-04 Safran Nacelles Process for manufacturing a honeycomb core structure for a turbojet engine nacelle
DE102020127034B4 (en) * 2020-10-14 2024-08-14 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Ducted propeller of an aircraft, duct of the same and aircraft

Family Cites Families (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR605912A (en) * 1926-02-26 1926-06-04 Anciens Etablissements Alin Sa Body with removable and waterproof hood
FR2261872B1 (en) * 1974-02-26 1976-06-25 Snecma
US5445861A (en) * 1992-09-04 1995-08-29 The Boeing Company Lightweight honeycomb panel structure
EP0636780A1 (en) * 1993-06-25 1995-02-01 Nordam Noise suppression liner for jet engines
US5653836A (en) * 1995-07-28 1997-08-05 Rohr, Inc. Method of repairing sound attenuation structure used for aircraft applications
US5782082A (en) * 1996-06-13 1998-07-21 The Boeing Company Aircraft engine acoustic liner
GB9909581D0 (en) * 1999-04-26 1999-06-23 Short Brothers Plc Noise attenuation panel
FR2815900B1 (en) * 2000-10-31 2003-07-18 Eads Airbus Sa NOISE REDUCING SANDWICH PANEL, ESPECIALLY FOR AN AIRCRAFT TURBOREACTOR
FR2817994B1 (en) * 2000-12-08 2003-02-28 Eads Airbus Sa SANDWICH ACOUSTIC PANEL
ITMI20010078A1 (en) * 2001-01-17 2002-07-17 Aermacchi S P A IMPROVED COMPOSITE STRUCTURE ACOUSTIC PANEL
FR2840647B1 (en) * 2002-06-05 2004-10-29 Airbus France DEVICE FOR CONNECTING TWO TUBULAR PIECES OF AIRCRAFT TURBOREACTOR
RU2230208C2 (en) * 2002-06-05 2004-06-10 Открытое акционерное общество "Авиадвигатель" Sound-absorbing device in two-circuit turbojet engine
US6871725B2 (en) * 2003-02-21 2005-03-29 Jeffrey Don Johnson Honeycomb core acoustic unit with metallurgically secured deformable septum, and method of manufacture
EP1657708A4 (en) * 2003-05-29 2009-07-01 Rion Co ISOLATION / ABSORPTION STRUCTURE, AND STRUCTURE COMPRISING THE SAME
RU2267628C1 (en) * 2004-03-25 2006-01-10 Открытое акционерное общество "Авиадвигатель" Sound-absorbing panel for turbofan passage
DE102004053383A1 (en) * 2004-11-02 2006-05-04 Eads Deutschland Gmbh Acoustic absorber for aircraft engines
DE102005027314A1 (en) * 2005-06-13 2006-12-14 Müller, Ulrich, Dr.-Ing. Lightweight construction plate manufacturing method for e.g. gas turbine, involves providing face sheet, where construction plate receives defined surface curvature during connection of face sheet, intermediate layer and support layer
US7798285B2 (en) * 2008-11-14 2010-09-21 Rohr, Inc. Acoustic barrel for aircraft engine nacelle including crack and delamination stoppers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

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BRPI0818630A2 (en) 2015-04-07
WO2009066036A3 (en) 2009-07-16
RU2477223C2 (en) 2013-03-10
FR2922152B1 (en) 2009-11-20
FR2922152A1 (en) 2009-04-17
US8245815B2 (en) 2012-08-21
RU2010119056A (en) 2011-11-27
WO2009066036A2 (en) 2009-05-28
CA2700183A1 (en) 2009-05-28
CN101827702B (en) 2013-10-02
CN101827702A (en) 2010-09-08
US20100212998A1 (en) 2010-08-26

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