EP1213703A1 - Sandwich acoustic panel - Google Patents

Sandwich acoustic panel Download PDF

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Publication number
EP1213703A1
EP1213703A1 EP01403144A EP01403144A EP1213703A1 EP 1213703 A1 EP1213703 A1 EP 1213703A1 EP 01403144 A EP01403144 A EP 01403144A EP 01403144 A EP01403144 A EP 01403144A EP 1213703 A1 EP1213703 A1 EP 1213703A1
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EP
European Patent Office
Prior art keywords
guides
acoustic panel
separator
panel
panel according
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Granted
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EP01403144A
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German (de)
French (fr)
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EP1213703B1 (en
Inventor
Alain Porte
Jacques Lalane
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Airbus Operations SAS
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Airbus Operations SAS
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    • 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

Definitions

  • the invention relates to an acoustic panel sandwich, i.e. a reducing sandwich panel noise, designed to attenuate an incident sound wave facing an outside face of the panel.
  • An acoustic panel according to the invention can in particular be used in nacelle walls or in turbojet engine housings, in conduits to be soundproofed, etc.
  • Existing acoustic panels include generally one or more quarter wave resonators, superimposed on a total reflector.
  • Each resonator itself consists of a resistive layer, more or less breathable, and of a honeycomb structure, most often of the honeycomb type.
  • Layer resistive covers the face of the honeycomb structure facing outward, i.e. towards the wave incident sound.
  • the total reflector covers the face of the resonator opposite to this wave incident.
  • front face the face of the panel carrying the resistive layer and “face back "the opposite side of the panel, covered by the reflector.
  • the resistive layer has a dissipative role.
  • viscous effects that transform acoustic energy in heat.
  • the height of the honeycomb structure allows to tune the panel to the characteristic frequency noise to be mitigated.
  • Noise dissipation in the resistive layer is maximum when the height of cells of the dimpled core is equal to a quarter of the wavelength of the frequency of the noise to be attenuated.
  • the cells of the honeycomb structure behave then like waveguides perpendicular to the surface of the panel, which gives them a response of "localized reaction” type.
  • the cells form a assembly of quarter-wave resonators in parallel.
  • Rear reflector produces conditions of total reflection, essential for behavior described above of the honeycomb core.
  • an acoustic panel should meet acoustic requirements.
  • a first of these requirements concerns the acoustic uniformity of the panel.
  • the acoustic treatment is all the more effective that it conforms to its specification on its entire surface. Compliance with this requirement depends the nature of the elements making up the panel, their relative arrangement and adhesives used for their assembly.
  • lateral energy leakage Another acoustic requirement is the requirement called “localized reaction”. If this requirement is not not respected, it occurs inside the panel a transverse propagation of sound waves, called “lateral energy leakage”, which opposes the "quarter wave” type of structure dimpled.
  • an acoustic panel integrated into a aircraft engine must be able to withstand conditions severe use.
  • the panel should not delamination, even in the presence of strong depressions, the panel must be able to withstand corrosion and erosion due, for example, to sand, must have good electrical conductivity so including resisting sweeping lightning and it must ability to contribute to mechanical shock absorption following a loss of dawn.
  • An acoustic panel integrated into a motor aircraft must also have structural strength allowing him to bear the weight of a man as well that the transfer of aerodynamic forces and inertial from the air intake to the engine housing.
  • acoustic panels can be classified into three categories: single panels nonlinear degree of freedom or SDOF ("simple degree of freedom ”) non-linear, single-degree panels linear freedom or linear SDOF, and the panels two degrees of freedom or DDOF ("double degree of freedom ").
  • SDOF simple degree of freedom
  • DDOF double degree of freedom
  • the resistive layer consists of a metallic or composite perforated layer.
  • a panel of this type has the advantages of allow good control of the area percentage open, to have good structural strength and be easy to perform.
  • the resistive layer is a layer micro porous made for example of a fabric metallic, of a perforated sheet associated with a fabric acoustic or a metallic fabric associated with a fabric acoustic.
  • a panel of this type allows to adjust the acoustic resistance by modifying the components of the micro porous layer. Its beach frequency is reasonable.
  • Such panel also has the advantages of having a non-linearity low to moderate as well as a low dependence of the acoustic resistance on the speed of tangential flow at the surface.
  • the realization of a panel single linear freedom sandwich is more complicated than that of a single degree panel of nonlinear freedom, because the resistive layer has two components. If the components or assembly processes are not under control, the structure may have areas of non-homogeneity acoustic as well as risks of delamination of the resistive layer. In addition, the risk of corrosion of the resistive layer impose a constraint additional regarding the choice of materials used. In addition, the method of assembling such a panel is long and expensive.
  • a double degree acoustic panel of freedom includes, in addition to a resistive layer perforated and a rear reflector, two cores superimposed dimples, separated by a layer resistive intermediate called "septum”, generally micro porous.
  • Double degree acoustic panels of freedom has the disadvantage that areas of acoustic non-homogeneity appear due to the poor alignment of the cells of the two souls alveolate, which inevitably occurs during the panel shaping. There are also parasitic phenomena of transverse propagation in areas where the cells of the two dimpled souls are not not aligned. Finally, the process of assembling a panel of this type is long and expensive because it takes assemble one by one the various elements of the structure.
  • the subject of the invention is precisely a acoustic panel whose original design allows you to benefit from the advantages of several degrees of freedom, while removing the disadvantages due to misalignment of cells alveolar structures, such as risks acoustic inhomogeneity and transverse propagation acoustic waves.
  • this result is obtained by means of a sandwich acoustic panel comprising a resistive layer forming a front face of the panel, a honeycomb structure formed of at least two superimposed honeycomb layers each comprising a network of cells, a porous separator interposed between adjacent honeycomb layers and a reflector forming a rear face of the panel, characterized in that that the porous separator carries, on each of its faces, guides penetrating at least some of the cells of the honeycomb layers adjacent to the separator, distributed over the entire surface of the separator.
  • the resistive layer, the layers dimpled, the porous separator and the reflector are joined together by gluing.
  • the resistive layer, the honeycomb layers, the porous separator and the reflector are all made of materials identical or compatible with the adhesive which ensures their assembly.
  • These materials are preferably chosen in the group comprising metallic materials, composites and thermoplastics.
  • the guides include either aligned elements, reported on both sides of the porous separator, i.e. elements crossing the porous separator.
  • the guides are tubular or shaped solid rod, of circular section.
  • This section can be uniform over the entire length of the guide or, otherwise have tapered ends to facilitate their installation. They can also present a different section, such as a section star-shaped with at least three branches, without depart from the scope of the invention.
  • the rods can be made of any material porous or not.
  • a sandwich acoustic panel conforming to the invention consists of a stack of several constituents, joined together. For facilitate understanding, these constituents are shown slightly spaced from each other. In practice they are in close contact throughout the panel surface.
  • the acoustic panel according to the invention can be flat, as shown by way of example. However, it can also take any other form, and in particular a curved shape, as is the case when integrated into the nacelle or crankcase of a turbojet engine.
  • the acoustic panel according to the invention comprises successively a resistive layer 14, a structure dimpled 16 and a rear reflector 17.
  • the resistive layer 14 is porous or perforated. It is in contact with the outside air and struck in first by the acoustic wave that we want to dampen. As in existing double acoustic panels degree of freedom, the resistive layer 14 is designed to transform the incident acoustic energy into heat.
  • the resistive layer 14 When the panel is integrated in the nacelle of a turbojet engine, the resistive layer 14 also allows receive and transfer to links structural engine nacelle aerodynamic forces and inertials, as well as those related to the maintenance of the nacelle.
  • the honeycomb structure 16 comprises at least two superimposed honeycomb layers 18.
  • the number of layers 18 forming the honeycomb structure 16 is equal to number of degrees of freedom desired for the panel acoustic.
  • the acoustic panel is two degrees from freedom and the honeycomb structure 16 therefore includes two acoustic layers 18. This number can however be greater than two without departing from the scope of the invention.
  • Each of the honeycomb layers 18 of the structure 16 comprises a network of cells 20, the cells of each network being delimited by partitions 22.
  • the cell networks 20 of the different layers 18 are identical so that cells 20 and their partitions 22 can be aligned, as illustrated in figure 1. To this end, the shapes, dimensions and distribution of cells 20 of each layers 18 are the same.
  • the honeycomb layers 18 have the form of honeycombs.
  • the cells 20 then have a hexagonal section.
  • honeycomb layers with cells 20 of different sections can be used without departing from the scope of the invention.
  • honeycomb structure 16 comprising the honeycomb layers 18 has the same function as in acoustic panels with several degrees of freedom from prior art. This function is well known to skilled in the art, so she won't developed here.
  • a separator 24 is interposed between each pair of adjacent honeycomb layers 18 of the honeycomb structure 16. In the case of a panel with two degrees of freedom as illustrated in figure 1, a only separator is placed between the two layers dimpled 18. More generally, the number of separators 24 is one unit lower than honeycomb layers 16.
  • Each separator 24 is made in one porous material. This material is chosen for its qualities of acoustic resistance, for its resistance to corrosion and for its low mass, because the level of structural stress to which it is subject is weak.
  • the porous material of the separator 24 can be metallic, synthetic or fiber-based fabric variety. It can also be a material thermoplastic or porous plastic. It ensures the same function that the porous separators interposed between the honeycomb layers of art acoustic panels prior to several degrees of freedom. This function is well known to those skilled in the art, so that it no description will be given here.
  • the separator porous 24 carries, on each of its faces, guides 26. These guides 26 are regularly distributed throughout the surface of the separator 24, according to a network superimposable on that of cells 20 of the layers dimpled 18. In addition, the shape and sizing guides 26 are such that each of them can enter one of the 20 cells with a clearance too limited as possible.
  • each of the guides 26 is located opposite a cell 20 when the honeycomb layers 18 and the or the separators 24 are superimposed. This result can be obtained either by providing on each side of the separator 24 as many guides 26 as there are cells 20 on the honeycomb layer 18 adjacent either, preferably by equipping the separator 24 with a number guides 26 lower than that of cells 20, as illustrated in Figure 1. In the latter case, the number guides 26 simply need to be sufficient for a correct alignment of cells 20 and partitions 22 is provided on the entire panel (we can provide, for example, a guide 26 for three to five cells 20 aligned). In order to satisfy this condition, the number of guides 26 is greater the greater the curvature of the panel is important.
  • the shape presented by the guides 26 can be any, provided that the positioning effect sought mechanical is obtained.
  • the guides 26 are tubular. However, they may also present a different shape such as a shaped section star with three or four branches, without leaving the part of the invention.
  • the guides 26 When the guides 26 are tubular, they may in particular have a cross section circular or polygonal. This section can be uniform, as shown in Figure 1, or at otherwise variable, for example reduced and rounded in going towards the ends, to facilitate assembly, as shown in Figure 2a.
  • the guides 26 are made up of solid rods.
  • the rod is terminated by one end conical.
  • the rod has, in section along its longitudinal axis, a shape rounded, for example substantially oval or elliptical.
  • Guides 26 can be produced in any materials, which mainly depend on the material chosen for the separator that carries them. according to the materials, the guides 26 can be fixed to the separator by welding, gluing, interlocking, etc.
  • the guides 26 include pairs of tubes 2 aligned, reported separately on either side of the separator 24.
  • the alignment of the tubes 28 is ensured by the use of appropriate tools when the tubes are fixed to the separator, for example by bonding.
  • the guides 26 include elements 28 (in the form of tubes on FIG. 1) which cross the separator 24. The alignment is then ensured by construction, without that it is necessary to use a tool particular. However, in the case of guides tubular, they are then devoid of separator, unless you use tubular guides that you internally equipped with individual separators, before or after their attachment to the separator.
  • the rear reflector 17 is made of the same way as in art acoustic panels previous, according to the usual knowledge of the skilled person. So it will not be special description.
  • the adhesive used to bond the different components of the panel can occur in the form of a film or be projected or sprayed on at least one of the components to be assembled.
  • the different components of the panel can be made of various materials metallic, composite, thermoplastic, etc.
  • separator 24 in accordance with the invention enables the panel to be produced in materials identical or compatible with the adhesive used, i.e. in a single family of materials (for example, any composite). We thus avoid corrosion and galvanic torque problems. In addition, quality bonding is guaranteed between the different components.
  • a separator 24 equipped with guides 26 ensures continuity of cells and partitions of the honeycomb layers 18, between the layer resistive front 14 and rear reflector 17.
  • the cells 20 are thus automatically aligned whatever whatever the shape of the panel, and especially when it is a complex aerodynamic form or not developable. This arrangement also makes it possible to eliminate lateral energy leaks and, as a result, keep a localized acoustic reaction.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Building Environments (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Laminated Bodies (AREA)

Abstract

The acoustic panel comprises a resistive layer (14), a honeycomb structure (16) formed from at least two superposed honeycombed layers (18) and a rear reflector (17). A porous separator (24) placed between each pair of adjacent honeycombed layers carries on each of its surfaces tubular guides (26) which penetrate into certain honeycomb cells (20).

Description

Domaine techniqueTechnical area

L'invention concerne un panneau acoustique sandwich, c'est-à-dire un panneau sandwich réducteur de bruit, conçu pour atténuer une onde sonore incidente dirigée vers une face extérieure du panneau.The invention relates to an acoustic panel sandwich, i.e. a reducing sandwich panel noise, designed to attenuate an incident sound wave facing an outside face of the panel.

Un panneau acoustique conforme à l'invention peut notamment être utilisé dans des parois de nacelles ou dans des carters de turboréacteurs, dans des conduits devant être insonorisés, etc..An acoustic panel according to the invention can in particular be used in nacelle walls or in turbojet engine housings, in conduits to be soundproofed, etc.

Etat de la techniqueState of the art

Les panneaux acoustiques existants comprennent généralement un ou plusieurs résonateurs quart d'onde, superposés sur un réflecteur total. Chaque résonateur est lui-même constitué d'une couche résistive, plus ou moins perméable à l'air, et d'une structure alvéolée, le plus souvent de type nid d'abeilles. La couche résistive recouvre la face de la structure alvéolée tournée vers l'extérieur, c'est-à-dire vers l'onde sonore incidente. Au contraire, le réflecteur total recouvre la face du résonateur opposée à cette onde incidente. Par convention, on appelle "face avant" la face du panneau portant la couche résistive et "face arrière" la face opposée du panneau, recouverte par le réflecteur.Existing acoustic panels include generally one or more quarter wave resonators, superimposed on a total reflector. Each resonator itself consists of a resistive layer, more or less breathable, and of a honeycomb structure, most often of the honeycomb type. Layer resistive covers the face of the honeycomb structure facing outward, i.e. towards the wave incident sound. On the contrary, the total reflector covers the face of the resonator opposite to this wave incident. By convention, we call "front face" the face of the panel carrying the resistive layer and "face back "the opposite side of the panel, covered by the reflector.

Dans cet agencement classique des panneaux acoustiques, la couche résistive a un rôle dissipatif. Lorsqu'une onde sonore la traverse, il se produit des effets visqueux qui transforment l'énergie acoustique en chaleur.In this classic arrangement of panels acoustic, the resistive layer has a dissipative role. When a sound wave passes through it, viscous effects that transform acoustic energy in heat.

La hauteur de la structure alvéolée permet d'accorder le panneau sur la fréquence caractéristique du bruit à atténuer. La dissipation du bruit dans la couche résistive est maximale lorsque la hauteur des cellules de l'âme alvéolée est égale au quart de la longueur d'onde de la fréquence du bruit à atténuer. Les cellules de la structure alvéolée se comportent alors comme des guides d'ondes perpendiculaires à la surface du panneau, ce qui leur confère une réponse de type "réaction localisée". Les cellules forment un assemblage de résonateurs quart d'onde en parallèle.The height of the honeycomb structure allows to tune the panel to the characteristic frequency noise to be mitigated. Noise dissipation in the resistive layer is maximum when the height of cells of the dimpled core is equal to a quarter of the wavelength of the frequency of the noise to be attenuated. The cells of the honeycomb structure behave then like waveguides perpendicular to the surface of the panel, which gives them a response of "localized reaction" type. The cells form a assembly of quarter-wave resonators in parallel.

Le réflecteur arrière produit des conditions de réflexion totale, indispensables au comportement décrit ci-dessus de l'âme alvéolée.Rear reflector produces conditions of total reflection, essential for behavior described above of the honeycomb core.

De façon générale, un panneau acoustique doit satisfaire à des exigences acoustiques.In general, an acoustic panel should meet acoustic requirements.

Une première de ces exigences concerne l'homogénéité acoustique du panneau. En d'autres termes, le traitement acoustique est d'autant plus efficace qu'il est conforme à sa spécification sur toute sa surface. Le respect de cette exigence dépend de la nature des éléments composant le panneau, de leur disposition relative et des adhésifs utilisés pour leur assemblage.A first of these requirements concerns the acoustic uniformity of the panel. In others terms, the acoustic treatment is all the more effective that it conforms to its specification on its entire surface. Compliance with this requirement depends the nature of the elements making up the panel, their relative arrangement and adhesives used for their assembly.

Une autre exigence acoustique est l'exigence dite de "réaction localisée". Si cette exigence n'est pas respectée, il se produit à l'intérieur du panneau une propagation transversale des ondes sonores, dite "fuite d'énergie latérale", qui s'oppose au fonctionnement de type "quart d'onde" de la structure alvéolée.Another acoustic requirement is the requirement called "localized reaction". If this requirement is not not respected, it occurs inside the panel a transverse propagation of sound waves, called "lateral energy leakage", which opposes the "quarter wave" type of structure dimpled.

Lorsque le panneau équipe un moteur d'avion, il s'ajoute à ces exigences acoustiques des exigences de résistance à l'environnement, des exigences structurales et des exigences aérodynamiques.When the panel equips an aircraft engine, in addition to these acoustic requirements, requirements environmental resistance, requirements structural and aerodynamic requirements.

Ainsi, un panneau acoustique intégré dans un moteur d'avion doit pouvoir résister à des conditions sévères d'utilisation. En particulier, il ne doit pas se produire de délaminage, même en présence de fortes dépressions, le panneau doit pouvoir résister à la corrosion et à l'érosion due, par exemple, au sable, il doit présenter une bonne conductivité électrique afin notamment de résister à la foudre balayante et il doit pouvoir contribuer à l'absorption mécanique du choc consécutif à une perte d'aube.Thus, an acoustic panel integrated into a aircraft engine must be able to withstand conditions severe use. In particular, it should not delamination, even in the presence of strong depressions, the panel must be able to withstand corrosion and erosion due, for example, to sand, must have good electrical conductivity so including resisting sweeping lightning and it must ability to contribute to mechanical shock absorption following a loss of dawn.

Un panneau acoustique intégré dans un moteur d'avion doit aussi présenter une résistance structurale lui permettant de supporter le poids d'un homme ainsi que le transfert des efforts aérodynamiques et inertiels de l'entrée d'air vers le carter du moteur.An acoustic panel integrated into a motor aircraft must also have structural strength allowing him to bear the weight of a man as well that the transfer of aerodynamic forces and inertial from the air intake to the engine housing.

Enfin, l'état de surface d'un panneau acoustique intégré dans un moteur d'avion doit être cohérent avec les lignes aérodynamiques et les exigences de continuité des surfaces en contact avec l'air en écoulement.Finally, the surface condition of a panel acoustics built into an aircraft engine must be consistent with aerodynamic lines and continuity requirements of surfaces in contact with flowing air.

Les panneaux acoustiques connus peuvent être classés en trois catégories : les panneaux à un seul degré de liberté non linéaire ou SDOF ("simple degree of freedom") non linéaire, les panneaux à un seul degré de liberté linéaire ou SDOF linéaire, et les panneaux à deux degrés de liberté ou DDOF ("double degree of freedom").Known acoustic panels can be classified into three categories: single panels nonlinear degree of freedom or SDOF ("simple degree of freedom ") non-linear, single-degree panels linear freedom or linear SDOF, and the panels two degrees of freedom or DDOF ("double degree of freedom ").

Dans les panneaux à simple degré de liberté non linéaire la couche résistive est constituée d'une couche perforée métallique ou composite.In single degree of freedom panels nonlinear the resistive layer consists of a metallic or composite perforated layer.

Un panneau de ce type a pour avantages de permettre une bonne maítrise du pourcentage de surface ouverte, de présenter une bonne résistance structurale et d'être facile à réaliser.A panel of this type has the advantages of allow good control of the area percentage open, to have good structural strength and be easy to perform.

En revanche, il a pour inconvénients de présenter une forte non-linéarité acoustique ainsi qu'une forte dépendance de la résistance à la vitesse de l'écoulement tangentielle en surface. De plus, puisque la fréquence amortie par chaque cellule dépend de sa profondeur et comme toutes les cellules du panneau ont la même profondeur, la plage de fréquences amortie par un tel panneau est restreinte. En outre, lorsque la couche résistive est en matériau composite, la structure présente une faible résistance à l'érosion.On the other hand, it has the disadvantages of exhibit strong acoustic non-linearity as well that a strong dependence on speed resistance of tangential flow at the surface. Moreover, since the frequency damped by each cell depends of its depth and like all the cells of the panel have the same depth, the frequency range damped by such a panel is restricted. In addition, when the resistive layer is made of composite material, the structure has a low resistance to erosion.

Dans les panneaux acoustiques à simple degré de liberté linéaire, la couche résistive est une couche micro poreuse constituée par exemple d'un tissu métallique, d'une tôle perforée associée à un tissu acoustique ou d'un tissu métallique associé à un tissu acoustique.In single-degree acoustic panels of linear freedom, the resistive layer is a layer micro porous made for example of a fabric metallic, of a perforated sheet associated with a fabric acoustic or a metallic fabric associated with a fabric acoustic.

L'utilisation d'un panneau de ce type permet d'ajuster la résistance acoustique en modifiant les composants de la couche micro poreuse. Sa plage fréquentielle d'efficacité est raisonnable. Un tel panneau a aussi pour avantages de présenter une non-linéarité faible à modérée ainsi qu'une faible dépendance de la résistance acoustique à la vitesse de l'écoulement tangentiel en surface.The use of a panel of this type allows to adjust the acoustic resistance by modifying the components of the micro porous layer. Its beach frequency is reasonable. Such panel also has the advantages of having a non-linearity low to moderate as well as a low dependence of the acoustic resistance on the speed of tangential flow at the surface.

Toutefois, la réalisation d'un panneau sandwich à simple degré de liberté linéaire est plus compliquée que celle d'un panneau à simple degré de liberté non linéaire, du fait que la couche résistive comprend deux constituants. Si les composants ou les procédés d'assemblage ne sont pas maítrisés, la structure peut présenter des zones de non-homogénéité acoustique ainsi que des risques de délaminage de la couche résistive. De plus, les risques de corrosion de la couche résistive imposent une contrainte supplémentaire concernant le choix des matériaux utilisés. En outre, le procédé d'assemblage d'un tel panneau est long et coûteux.However, the realization of a panel single linear freedom sandwich is more complicated than that of a single degree panel of nonlinear freedom, because the resistive layer has two components. If the components or assembly processes are not under control, the structure may have areas of non-homogeneity acoustic as well as risks of delamination of the resistive layer. In addition, the risk of corrosion of the resistive layer impose a constraint additional regarding the choice of materials used. In addition, the method of assembling such a panel is long and expensive.

Enfin, un panneau acoustique à double degré de liberté comprend, en plus d'une couche résistive perforée et d'un réflecteur arrière, deux âmes alvéolées superposées, séparées par une couche résistive intermédiaire appelée "septum", généralement micro poreuse.Finally, a double degree acoustic panel of freedom includes, in addition to a resistive layer perforated and a rear reflector, two cores superimposed dimples, separated by a layer resistive intermediate called "septum", generally micro porous.

Par rapport aux autres type de panneaux acoustiques, les panneaux à double degré de liberté présentent une plage de fréquences amorties plus large, une possibilité d'ajustement de la résistance acoustique à l'aide des deux couches résistives et une non-linéarité acoustique faible à modérée.Compared to other types of panels acoustic, double degree of freedom panels have a wider damped frequency range, possibility of resistance adjustment acoustics using two resistive layers and one weak to moderate acoustic non-linearity.

Les panneaux acoustiques à double degré de liberté ont toutefois pour inconvénient que des zones de non-homogénéité acoustique apparaissent du fait du mauvais alignement des cellules des deux âmes alvéolées, qui se produit inévitablement lors de la mise en forme du panneau. Il existe aussi des phénomènes parasites de propagation transverse dans les zones où les cellules des deux âmes alvéolées ne sont pas alignées. Enfin, le procédé d'assemblage d'un panneau de ce type est long et coûteux, car il faut assembler un par un les divers éléments de la structure.Double degree acoustic panels of freedom, however, has the disadvantage that areas of acoustic non-homogeneity appear due to the poor alignment of the cells of the two souls alveolate, which inevitably occurs during the panel shaping. There are also parasitic phenomena of transverse propagation in areas where the cells of the two dimpled souls are not not aligned. Finally, the process of assembling a panel of this type is long and expensive because it takes assemble one by one the various elements of the structure.

Exposé de l'inventionStatement of the invention

L'invention a précisément pour objet un panneau acoustique dont la conception originale lui permet de bénéficier des avantages des panneaux à plusieurs degrés de liberté, tout en supprimant les inconvénients dus aux défauts d'alignement des cellules des structures alvéolaires, tels que les risques d'inhomogénéité acoustique et de propagation transverse des ondes acoustiques.The subject of the invention is precisely a acoustic panel whose original design allows you to benefit from the advantages of several degrees of freedom, while removing the disadvantages due to misalignment of cells alveolar structures, such as risks acoustic inhomogeneity and transverse propagation acoustic waves.

Conformément à l'invention, ce résultat est obtenu au moyen d'un panneau acoustique sandwich comprenant une couche résistive formant une face avant du panneau, une structure alvéolée formée d'au moins deux couches alvéolées superposées comportant chacune un réseau de cellules, un séparateur poreux interposé entre les couches alvéolées adjacentes et un réflecteur formant une face arrière du panneau, caractérisé en ce que le séparateur poreux porte, sur chacune de ses faces, des guides pénétrant dans au moins certaines des cellules des couches alvéolées adjacentes au séparateur, réparties sur toute la surface du séparateur.According to the invention, this result is obtained by means of a sandwich acoustic panel comprising a resistive layer forming a front face of the panel, a honeycomb structure formed of at least two superimposed honeycomb layers each comprising a network of cells, a porous separator interposed between adjacent honeycomb layers and a reflector forming a rear face of the panel, characterized in that that the porous separator carries, on each of its faces, guides penetrating at least some of the cells of the honeycomb layers adjacent to the separator, distributed over the entire surface of the separator.

La présence des guides sur chacune des faces du séparateur poreux permet d'assurer la continuité des cloisons et, par conséquent, des cellules de la structure alvéolée, entre 1a surface intérieure de la couche résistive et le réflecteur. Les problèmes de désalignement locaux des cellules, qui apparaissent nécessairement sur les panneaux à plusieurs degrés de liberté de l'art antérieur, constitués de plusieurs structures alvéolées superposées, sont donc supprimés. Par conséquent, les risques d'inhomogénéité n'existent plus.The presence of guides on each side porous separator ensures continuity of partitions and therefore cells of the honeycomb structure, between the interior surface of the resistive layer and reflector. The problems of local cell misalignments, which appear necessarily on panels with several degrees of freedom of the prior art, consisting of several superimposed honeycomb structures, are therefore deleted. Consequently, the risks of non-uniformity do not exist more.

Selon un mode de réalisation préféré de l'invention, la couche résistive, les couches alvéolées, le séparateur poreux et le réflecteur sont assemblés entre eux par collage.According to a preferred embodiment of the invention, the resistive layer, the layers dimpled, the porous separator and the reflector are joined together by gluing.

Avantageusement, la couche résistive, les couches alvéolées, le séparateur poreux et le réflecteur sont tous réalisés en des matériaux identiques ou compatibles avec l'adhésif qui assure leur assemblage.Advantageously, the resistive layer, the honeycomb layers, the porous separator and the reflector are all made of materials identical or compatible with the adhesive which ensures their assembly.

Ces matériaux sont choisis, de préférence, dans le groupe comprenant les matériaux métalliques, composites et thermoplastiques.These materials are preferably chosen in the group comprising metallic materials, composites and thermoplastics.

Selon le cas, les guides comprennent soit des éléments alignés, rapportés de part et d'autre du séparateur poreux, soit des éléments traversant le séparateur poreux.Depending on the case, the guides include either aligned elements, reported on both sides of the porous separator, i.e. elements crossing the porous separator.

Dans les modes de réalisation préférés de l'invention, les guides sont tubulaires ou en forme de tige pleine, de section circulaire. Cette section peut être uniforme sur toute la longueur du guide ou, au contraire, comporter des extrémités de section effilée pour faciliter leur mise en place. Ils peuvent aussi présenter une section différente, telle qu'une section en forme d'étoile à au moins trois branches, sans sortir du cadre de l'invention. En outre, les tiges peuvent être réalisées indifféremment en un matériau poreux ou non.In the preferred embodiments of the invention, the guides are tubular or shaped solid rod, of circular section. This section can be uniform over the entire length of the guide or, otherwise have tapered ends to facilitate their installation. They can also present a different section, such as a section star-shaped with at least three branches, without depart from the scope of the invention. In addition, the rods can be made of any material porous or not.

Brève description des dessinsBrief description of the drawings

On décrira à présent, à titre d'exemple non limitatif, un mode de réalisation préféré de l'invention, en se référant aux dessins annexés, dans lesquels :

  • la figure 1 est une vue en coupe qui représente schématiquement un panneau acoustique sandwich conforme à l'invention ; et
  • les figures 2a à 2c sont des vues en coupe, à plus grande échelle, qui représentent des variantes de réalisation des guides portés par le séparateur poreux.
A preferred embodiment of the invention will now be described, by way of nonlimiting example, with reference to the appended drawings, in which:
  • Figure 1 is a sectional view which schematically shows an acoustic sandwich panel according to the invention; and
  • Figures 2a to 2c are sectional views, on a larger scale, which show alternative embodiments of the guides carried by the porous separator.

Description détaillée d'un mode de réalisation préféré de l'inventionDetailed description of a preferred embodiment of the invention

Comme on l'a représenté schématiquement sur la figure 1, un panneau acoustique sandwich conforme à l'invention est constitué par un empilement de plusieurs constituants, solidarisés entre eux. Pour faciliter la compréhension, ces constituants sont représentés légèrement espacés les uns des autres. Dans la pratique, ils sont en contact étroit sur toute la surface du panneau.As shown schematically on the Figure 1, a sandwich acoustic panel conforming to the invention consists of a stack of several constituents, joined together. For facilitate understanding, these constituents are shown slightly spaced from each other. In practice they are in close contact throughout the panel surface.

Le panneau acoustique selon l'invention peut être plan, comme on l'a représenté à titre d'exemple. Toutefois, il peut aussi présenter toute autre forme, et notamment une forme incurvée, comme c'est le cas lorsqu'il est intégré à la nacelle ou au carter moteur d'un turboréacteur.The acoustic panel according to the invention can be flat, as shown by way of example. However, it can also take any other form, and in particular a curved shape, as is the case when integrated into the nacelle or crankcase of a turbojet engine.

La structure du panneau va à présent être décrite en allant de la face extérieure 10 de celui-ci, appelée "face avant", vers sa face intérieure 12, appelée "face arrière". Sur la figure 1, les faces avant 10 et arrière 12 sont orientées respectivement vers le bas et vers le haut.The panel structure will now be described from the outside face 10 thereof, called "front face", towards its inner face 12, called "back side". In Figure 1, the faces front 10 and rear 12 are oriented respectively down and up.

Ainsi, en partant de la face avant 10, le panneau acoustique selon l'invention comprend successivement une couche résistive 14, une structure alvéolée 16 et un réflecteur arrière 17.Thus, starting from the front face 10, the acoustic panel according to the invention comprises successively a resistive layer 14, a structure dimpled 16 and a rear reflector 17.

La couche résistive 14 est poreuse ou ajourée. Elle est en contact avec l'air extérieur et heurtée en premier par l'onde acoustique que l'on désire amortir. Comme dans les panneaux acoustiques existants à double degré de liberté, la couche résistive 14 est conçue pour transformer l'énergie acoustique incidente en chaleur.The resistive layer 14 is porous or perforated. It is in contact with the outside air and struck in first by the acoustic wave that we want to dampen. As in existing double acoustic panels degree of freedom, the resistive layer 14 is designed to transform the incident acoustic energy into heat.

Lorsque le panneau est intégré dans la nacelle d'un turboréacteur, la couche résistive 14 permet aussi de recevoir et de transférer vers les liaisons structurales nacelle-moteur les efforts aérodynamiques et inertiels, ainsi que ceux qui sont liés à la maintenance de la nacelle.When the panel is integrated in the nacelle of a turbojet engine, the resistive layer 14 also allows receive and transfer to links structural engine nacelle aerodynamic forces and inertials, as well as those related to the maintenance of the nacelle.

La structure alvéolée 16 comprend au moins deux couches alvéolées 18 superposées. Le nombre des couches 18 formant la structure alvéolée 16 est égal au nombre de degrés de liberté souhaité pour le panneau acoustique. Dans le mode de réalisation représenté sur la figure 1, le panneau acoustique est à deux degrés de liberté et la structure alvéolée 16 comprend donc deux couches acoustiques 18. Ce nombre peut toutefois être supérieur à deux sans sortir du cadre de l'invention.The honeycomb structure 16 comprises at least two superimposed honeycomb layers 18. The number of layers 18 forming the honeycomb structure 16 is equal to number of degrees of freedom desired for the panel acoustic. In the embodiment shown on Figure 1, the acoustic panel is two degrees from freedom and the honeycomb structure 16 therefore includes two acoustic layers 18. This number can however be greater than two without departing from the scope of the invention.

Chacune des couches alvéolées 18 de la structure 16 comporte un réseau de cellules 20, les cellules de chaque réseau étant délimitées par des cloisons 22. Les réseaux de cellules 20 des différentes couches 18 sont identiques, afin que les cellules 20 et leurs cloisons 22 puissent être alignées, comme l'illustre la figure 1. A cet effet, les formes, les dimensions et la répartition des cellules 20 de chacune des couches 18 sont les mêmes.Each of the honeycomb layers 18 of the structure 16 comprises a network of cells 20, the cells of each network being delimited by partitions 22. The cell networks 20 of the different layers 18 are identical so that cells 20 and their partitions 22 can be aligned, as illustrated in figure 1. To this end, the shapes, dimensions and distribution of cells 20 of each layers 18 are the same.

Dans un mode de réalisation préféré de l'invention, les couches alvéolées 18 ont la forme de nids d'abeilles. Les cellules 20 présentent alors une section hexagonale. Toutefois, des couches alvéolées présentant des cellules 20 de sections différentes (circulaires, triangulaires, carrées, trapézoïdales, etc.) peuvent être utilisées, sans sortir du cadre de l'invention.In a preferred embodiment of the invention, the honeycomb layers 18 have the form of honeycombs. The cells 20 then have a hexagonal section. However, honeycomb layers with cells 20 of different sections (circular, triangular, square, trapezoidal, etc.) can be used without departing from the scope of the invention.

La structure alvéolée 16 comportant les couches alvéolées 18 a la même fonction que dans les panneaux acoustiques à plusieurs degrés de liberté de l'art antérieur. Cette fonction est bien connue de l'homme du métier, de sorte qu'elle ne sera pas développée ici.The honeycomb structure 16 comprising the honeycomb layers 18 has the same function as in acoustic panels with several degrees of freedom from prior art. This function is well known to skilled in the art, so she won't developed here.

Un séparateur 24 est interposé entre chaque paire de couches alvéolées 18 adjacentes de la structure alvéolée 16. Dans le cas d'un panneau à deux degrés de liberté tel qu'illustré sur la figure 1, un seul séparateur est placé entre les deux couches alvéolées 18. De façon plus générale, le nombre de séparateurs 24 est inférieur d'une unité à celui des couches alvéolées 16.A separator 24 is interposed between each pair of adjacent honeycomb layers 18 of the honeycomb structure 16. In the case of a panel with two degrees of freedom as illustrated in figure 1, a only separator is placed between the two layers dimpled 18. More generally, the number of separators 24 is one unit lower than honeycomb layers 16.

Chaque séparateur 24 est réalisé en un matériau poreux. Ce matériau est choisi pour ses qualités de résistance acoustique, pour sa résistance à la corrosion et pour sa faible masse, du fait que le niveau de contrainte structurale auquel il est soumis est faible.Each separator 24 is made in one porous material. This material is chosen for its qualities of acoustic resistance, for its resistance to corrosion and for its low mass, because the level of structural stress to which it is subject is weak.

Le matériau poreux du séparateur 24 peut être un tissu métallique, synthétique ou à base de fibres diverses. Il peut aussi s'agir d'un matériau thermoplastique ou plastique poreux. Il assure la même fonction que les séparateurs poreux interposés entre les couches alvéolées des panneaux acoustiques de l'art antérieur à plusieurs degrés de liberté. Cette fonction est bien connue de l'homme du métier, de sorte qu'il n'en sera pas fait de description ici.The porous material of the separator 24 can be metallic, synthetic or fiber-based fabric variety. It can also be a material thermoplastic or porous plastic. It ensures the same function that the porous separators interposed between the honeycomb layers of art acoustic panels prior to several degrees of freedom. This function is well known to those skilled in the art, so that it no description will be given here.

Conformément à l'invention, le séparateur poreux 24 porte, sur chacune de ses faces, des guides 26. Ces guides 26 sont régulièrement répartis sur toute la surface du séparateur 24, selon un réseau superposable à celui des cellules 20 des couches alvéolées 18. En outre, la forme et le dimensionnement des guides 26 sont tels que chacun d'entre eux puisse pénétrer dans l'une des cellules 20 avec un jeu aussi limité que possible.In accordance with the invention, the separator porous 24 carries, on each of its faces, guides 26. These guides 26 are regularly distributed throughout the surface of the separator 24, according to a network superimposable on that of cells 20 of the layers dimpled 18. In addition, the shape and sizing guides 26 are such that each of them can enter one of the 20 cells with a clearance too limited as possible.

L'expression "réseau superposable" signifie que chacun des guides 26 est situé en face d'une cellule 20 lorsque les couches alvéolées 18 et le ou les séparateurs 24 sont superposés. Ce résultat peut être obtenu soit en prévoyant sur chaque face du séparateur 24 autant de guides 26 qu'il existe de cellules 20 sur la couche alvéolée 18 adjacente soit, de préférence, en équipant le séparateur 24 d'un nombre de guides 26 inférieur à celui des cellules 20, comme l'illustre la figure 1. Dans ce dernier cas, le nombre des guides 26 doit simplement être suffisant pour qu'un alignement correct des cellules 20 et des cloisons 22 soit assuré sur l'ensemble du panneau (on peut prévoir, par exemple, un guide 26 pour trois à cinq cellules 20 alignées). Afin de satisfaire cette condition, le nombre des guides 26 est d'autant plus grand que la courbure du panneau est importante.The expression "stackable network" means that each of the guides 26 is located opposite a cell 20 when the honeycomb layers 18 and the or the separators 24 are superimposed. This result can be obtained either by providing on each side of the separator 24 as many guides 26 as there are cells 20 on the honeycomb layer 18 adjacent either, preferably by equipping the separator 24 with a number guides 26 lower than that of cells 20, as illustrated in Figure 1. In the latter case, the number guides 26 simply need to be sufficient for a correct alignment of cells 20 and partitions 22 is provided on the entire panel (we can provide, for example, a guide 26 for three to five cells 20 aligned). In order to satisfy this condition, the the number of guides 26 is greater the greater the curvature of the panel is important.

La forme présentée par les guides 26 peut être quelconque, à condition que l'effet de positionnement mécanique recherché soit obtenu. Dans le mode de réalisation représenté sur la figure 1, les guides 26 sont tubulaires. Toutefois, ils peuvent aussi présenter une forme différente telle qu'une section en forme d'étoile à trois ou quatre branches, sans sortir du cadre de l'invention.The shape presented by the guides 26 can be any, provided that the positioning effect sought mechanical is obtained. In the mode of embodiment shown in FIG. 1, the guides 26 are tubular. However, they may also present a different shape such as a shaped section star with three or four branches, without leaving the part of the invention.

Lorsque les guides 26 sont tubulaires, ils peuvent notamment avoir une section transversale circulaire ou polygonale. Cette section peut être uniforme, comme représenté sur la figure 1, ou au contraire variable, par exemple réduite et arondie en allant vers les extrémités, pour faciliter l'assemblage, comme l'illustre la figure 2a.When the guides 26 are tubular, they may in particular have a cross section circular or polygonal. This section can be uniform, as shown in Figure 1, or at otherwise variable, for example reduced and rounded in going towards the ends, to facilitate assembly, as shown in Figure 2a.

Dans une autre variante de réalisation, illustrée sur les figures 2b et 2c, les guides 26 sont constitués par des tiges pleines. Dans le cas de la figure 2b, la tige est terminée par une extrémité conique. Dans le cas de la figure 2c, la tige présente, en section selon son axe longitudinal, une forme arondie, par exemple sensiblement ovale ou elliptique.In another alternative embodiment, illustrated in FIGS. 2b and 2c, the guides 26 are made up of solid rods. In the case of Figure 2b, the rod is terminated by one end conical. In the case of FIG. 2c, the rod has, in section along its longitudinal axis, a shape rounded, for example substantially oval or elliptical.

Les guides 26 peuvent être réalisés en des matériaux quelconques, qui dépendent principalement du matériau choisi pour le séparateur qui les porte. Selon les matériaux, les guides 26 peuvent être fixés au séparateur par soudure, collage, emboítement, etc..Guides 26 can be produced in any materials, which mainly depend on the material chosen for the separator that carries them. according to the materials, the guides 26 can be fixed to the separator by welding, gluing, interlocking, etc.

Dans le mode de réalisation illustré sur la figure 1, les guides 26 comprennent des paires de tubes 28 alignés, rapportés séparément de part et d'autre du séparateur 24. L'alignement des tubes 28 est assuré par l'utilisation d'un outillage approprié, au moment où les tubes sont fixés au séparateur, par exemple par collage.In the embodiment illustrated in the Figure 1, the guides 26 include pairs of tubes 2 aligned, reported separately on either side of the separator 24. The alignment of the tubes 28 is ensured by the use of appropriate tools when the tubes are fixed to the separator, for example by bonding.

Dans une variante de réalisation, les guides 26 comprennent des éléments 28 (en forme de tubes sur la figure 1) qui traversent le séparateur 24. L'alignement est alors assuré par construction, sans qu'il soit nécessaire de recourir à un outillage particulier. Toutefois, dans le cas de guides tubulaires, ils sont alors dépourvus de séparateur, sauf si on utilise des guides tubulaires que l'on équipe intérieurement de séparateurs individuels, avant ou après leur fixation sur le séparateur.In an alternative embodiment, the guides 26 include elements 28 (in the form of tubes on FIG. 1) which cross the separator 24. The alignment is then ensured by construction, without that it is necessary to use a tool particular. However, in the case of guides tubular, they are then devoid of separator, unless you use tubular guides that you internally equipped with individual separators, before or after their attachment to the separator.

Le réflecteur arrière 17 est réalisé de la même manière que dans les panneaux acoustiques de l'art antérieur, selon les connaissances habituelles de l'homme du métier. Il n'en sera donc pas fait de description particulière.The rear reflector 17 is made of the same way as in art acoustic panels previous, according to the usual knowledge of the skilled person. So it will not be special description.

Les différents composants du panneau acoustique selon l'invention, c'est-à-dire la couche résistive 14, les couches alvéolées 18, le ou les séparateurs 24 et le réflecteur arrière 17, sont assemblés entre eux par collage. L'assemblage est réalisé :

  • 1)en plaçant la couche résistive 14 sur un moule ;
  • 2)en collant une première couche alvéolée 18 sur la couche résistive 14, au moyen d'un adhésif ;
  • 3)en collant le séparateur 24 muni de ses guides 26 sur la première couche alvéolée 18, en prenant soin de faire pénétrer dans les cellules de celle-ci les guides 26 montés sur la face du séparateur tournée vers la première couche alvéolée ;
  • 4)en collant une deuxième couche alvéolée 18 sur le séparateur 24, en prenant soin de faire pénétrer dans les cellules de la deuxième couche alvéolée les guides 26 montés sur la face du séparateur tournée vers cette dernière ; et
  • 5)en collant le réflecteur arrière 17 sur la deuxième couche alvéolée 18, au moyen d'un adhésif.
The various components of the acoustic panel according to the invention, that is to say the resistive layer 14, the honeycomb layers 18, the separator (s) 24 and the rear reflector 17, are assembled together by bonding. The assembly is carried out:
  • 1) by placing the resistive layer 14 on a mold;
  • 2) by bonding a first honeycomb layer 18 to the resistive layer 14, using an adhesive;
  • 3) by bonding the separator 24 provided with its guides 26 to the first honeycomb layer 18, taking care to make the guides 26 mounted on the face of the separator facing the first honeycomb layer penetrate into the cells thereof;
  • 4) by bonding a second honeycomb layer 18 on the separator 24, taking care to make the guides 26 mounted on the face of the separator facing the latter penetrate into the cells of the second honeycomb layer; and
  • 5) by gluing the rear reflector 17 to the second dimpled layer 18, using an adhesive.

Cette description concerne la fabrication d'un panneau à deux degrés de liberté, tel qu'illustré sur la figure 1. Lorsque le nombre des degrés de liberté est plus important, les étapes 3) et 4) sont répétées autant de fois que nécessaire.This description relates to the manufacture of a panel with two degrees of freedom, as illustrated on Figure 1. When the number of degrees of freedom is more important, steps 3) and 4) are repeated as many times as necessary.

L'adhésif utilisé pour lier entre eux les différents constituants du panneau peut se présenter sous la forme d'un film ou être projeté ou pulvérisé sur l'un au moins des composants à assembler.The adhesive used to bond the different components of the panel can occur in the form of a film or be projected or sprayed on at least one of the components to be assembled.

De façon générale, les différents composants du panneau peuvent être réalisés en divers matériaux métalliques, composites, thermoplastiques, etc.. In general, the different components of the panel can be made of various materials metallic, composite, thermoplastic, etc.

L'utilisation du séparateur 24 conforme à l'invention permet de réaliser le panneau dans des matériaux identiques ou compatibles avec l'adhésif utilisé, c'est-à-dire dans une famille unique de matériaux (par exemple, tout composite). On évite ainsi les problèmes de corrosion et de couples galvaniques. De plus, on garantit un collage de qualité entre les différents composants.The use of the separator 24 in accordance with the invention enables the panel to be produced in materials identical or compatible with the adhesive used, i.e. in a single family of materials (for example, any composite). We thus avoid corrosion and galvanic torque problems. In addition, quality bonding is guaranteed between the different components.

De plus, et de façon essentielle, l'utilisation d'un séparateur 24 équipé de guides 26 permet d'assurer la continuité des cellules et des cloisons des couches alvéolées 18, entre la couche résistive avant 14 et le réflecteur arrière 17. Les cellules 20 sont ainsi automatiquement alignées quelle que soit la forme du panneau, et notamment lorsqu'il s'agit d'une forme aérodynamique complexe ou non développable. Cet agencement permet en outre d'éliminer les fuites d'énergie latérales et, par conséquent, de conserver une réaction acoustique localisée.In addition, and most importantly, the use of a separator 24 equipped with guides 26 ensures continuity of cells and partitions of the honeycomb layers 18, between the layer resistive front 14 and rear reflector 17. The cells 20 are thus automatically aligned whatever whatever the shape of the panel, and especially when it is a complex aerodynamic form or not developable. This arrangement also makes it possible to eliminate lateral energy leaks and, as a result, keep a localized acoustic reaction.

Claims (10)

Panneau acoustique sandwich comprenant une couche résistive (14) formant une face avant du panneau, une structure alvéolée (16) formée d'au moins deux couches alvéolées (18) superposées comportant chacune un réseau de cellules (20), un séparateur poreux (24) interposé entre les couches alvéolées (18) adjacentes et un réflecteur (17) formant une face arrière du panneau, caractérisé en ce que le séparateur poreux (24) porte, sur chacune de ses faces, des guides (26) pénétrant dans au moins certaines des cellules (20) des couches alvéolées (18) adjacentes au séparateur, réparties sur toute la surface du séparateur.Sandwich acoustic panel comprising a resistive layer (14) forming a front face of the panel, a honeycomb structure (16) formed of at least two superimposed honeycomb layers (18) each comprising an array of cells (20), a porous separator (24 ) interposed between the adjacent honeycomb layers (18) and a reflector (17) forming a rear face of the panel, characterized in that the porous separator (24) carries, on each of its faces, guides (26) penetrating into at least some of the cells (20) of the honeycomb layers (18) adjacent to the separator, distributed over the entire surface of the separator. Panneau acoustique sandwich selon la revendication 1, dans lequel la couche résistive (14), les couches alvéolées (18), le séparateur poreux (24) et le réflecteur (17) sont assemblés entre eux par collage.Sandwich acoustic panel according to claim 1, in which the resistive layer (14), the honeycomb layers (18), the porous separator (24) and the reflector (17) are assembled together by bonding. Panneau acoustique sandwich selon l'une quelconque des revendications 1 et 2, dans lequel la couche résistive (14), les couches alvéolées (18), le séparateur poreux (24) et le réflecteur (17) sont tous réalisés en des matériaux identiques ou compatibles avec un adhésif qui assure leur assemblage.Sandwich acoustic panel according to one any of claims 1 and 2, wherein the resistive layer (14), the honeycomb layers (18), the porous separator (24) and reflector (17) are all made of identical or compatible materials with an adhesive which ensures their assembly. Panneau acoustique sandwich selon la revendication 3, dans lequel lesdits matériaux sont choisis dans le groupe comprenant les matériaux métalliques, composites et thermoplastiques.Sandwich acoustic panel according to claim 3, wherein said materials are chosen from the group comprising the materials metallic, composite and thermoplastic. Panneau acoustique sandwich selon l'une quelconque des revendications 1 à 4, dans lequel les guides (26) comprennent des éléments alignés (28), rapportés de part et d'autre du séparateur poreux (24).Sandwich acoustic panel according to one any of claims 1 to 4, wherein the guides (26) include aligned elements (28), reported on either side of the porous separator (24). Panneau acoustique sandwich selon l'une quelconque des revendications 1 à 4, dans lequel les guides (26) comprennent des éléments traversant le séparateur poreux (24).Sandwich acoustic panel according to one any of claims 1 to 4, wherein the guides (26) include elements passing through the porous separator (24). Panneau acoustique sandwich selon l'une quelconque des revendications 1 à 6, dans lequel les guides (26) sont tubulaires.Sandwich acoustic panel according to one any of claims 1 to 6, wherein the guides (26) are tubular. Panneau acoustique sandwich selon l'une quelconque des revendications 1 à 6, dans lequel les guides (26) sont des tiges pleines.Sandwich acoustic panel according to one any of claims 1 to 6, wherein the guides (26) are solid rods. Panneau acoustique sandwich selon l'une quelconque des revendications 1 à 8, dans lequel les guides (26) comportent des extrémitées effilées.Sandwich acoustic panel according to one any of claims 1 to 8, wherein the guides (26) have tapered ends. Panneau acoustique sandwich selon l'une quelconque des revendications 1 à 8, dans lequel les guides (26) présentent une section sensiblement uniforme sur toute leur longueur.Sandwich acoustic panel according to one any of claims 1 to 8, wherein the guides (26) have a cross section substantially uniform over their entire length.
EP01403144A 2000-12-08 2001-12-06 Sandwich acoustic panel Expired - Lifetime EP1213703B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0015981 2000-12-08
FR0015981A FR2817994B1 (en) 2000-12-08 2000-12-08 SANDWICH ACOUSTIC PANEL

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EP1213703A1 true EP1213703A1 (en) 2002-06-12
EP1213703B1 EP1213703B1 (en) 2004-05-19

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US (1) US6615950B2 (en)
EP (1) EP1213703B1 (en)
AT (1) ATE267442T1 (en)
CA (1) CA2364347C (en)
DE (1) DE60103352T2 (en)
ES (1) ES2220693T3 (en)
FR (1) FR2817994B1 (en)

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FR2925208A1 (en) * 2007-12-14 2009-06-19 Eurocopter France ABSORBENT STRUCTURE FOR ATTENUATING NOISE GENERATED IN PARTICULAR BY A ROTOR AND FAIRING COMPRISING SUCH A STRUCTURE
US7779965B2 (en) 2007-12-14 2010-08-24 Eurocopter Absorbent structure for attenuating noise particular by a rotor-generator noise, and a rotor duct including such a structure
FR2933224A1 (en) * 2008-06-25 2010-01-01 Aircelle Sa ACCOUSTIC PANEL FOR EJECTION TUBE
WO2010007263A1 (en) * 2008-06-25 2010-01-21 Aircelle Acoustic panel for an ejector nozzle
US8640825B2 (en) 2008-06-25 2014-02-04 Aircelle Acoustic panel for an ejector nozzle
US8763751B2 (en) 2008-10-10 2014-07-01 Airbus Operations Gmbh Silencer for an auxiliary power unit of an aircraft
WO2015023389A1 (en) * 2013-08-12 2015-02-19 Hexcel Corporation Sound wave guide for use in acoustic structures

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CA2364347C (en) 2010-10-19
FR2817994A1 (en) 2002-06-14
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DE60103352T2 (en) 2005-06-02
ES2220693T3 (en) 2004-12-16

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