Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
  • B64C1/40—Sound or heat insulation, e.g. using insulation blankets
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/19—Sheets or webs edge spliced or joined
  • Y10T428/192—Sheets or webs coplanar

Definitions

• the present invention relates to a septum for acoustic panel, said septum being in particular pierced glass.
• the invention also relates to a single or dual acoustic resonator comprising such a septum.
• the invention also relates to an acoustic panel incorporating a single or dual resonator comprising the septum according to the invention, such an acoustic panel being more particularly intended to be mounted in an aircraft nacelle supporting a turbojet engine.
• 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.
• an acoustic panel includes an acoustic resonator, forming a so-called intermediate layer, said acoustic resonator being enveloped by a so-called internal skin and a so-called external skin in order to form said acoustic panel.
• An acoustic resonator typically includes one or more honeycomb core structures (commonly referred to as "honeycomb") separated by a porous multi-perforated skin called a septum.
• Such septum may be formed from a plurality of rectangular septum plates contacted edge-to-edge at a juncture edge, said septum plates being generally obtained by cutting into a strip, for example in aluminium .
• the septum may also consist of a plurality of glass plates. The septum provides better sound absorption.
• Simple acoustic resonators composed of a single honeycomb core structure on which a septum can be attached.
• Double acoustic resonators are also known, composed of at least two septum-wrapped cellular core structures (which may for example be bonded to one of the two structures or to both structures),
• An acoustic panel comprises in particular a single or double acoustic resonator as defined above and forming an intermediate layer of said panel.
• An acoustic panel may be simple and comprise a simple acoustic resonator as defined above and covered, on the one hand, on its outer face, with an outer skin attached to the nacelle, forming an outer layer of the acoustic panel and, on the other hand, on the other hand, on its inner face, an inner skin fixed on said inner face, forming an inner layer of the acoustic panel.
• a double acoustic resonator comprises a double acoustic resonator as defined above, on the internal face of which is fixed an internal skin, forming an inner layer of the acoustic panel, and on the outer face of which an external skin is attached. to the nacelle forms an outer layer of said acoustic panel.
• acoustic The outer skin of the acoustic panel, called “acoustic”, is perforated and is permeable to air; it is intended to be exposed to the flow of air passing through the interior of the nacelle and generating the noise to be attenuated.
• full The inner skin of the acoustic panel, called “full”, is not perforated and is impervious to air; it is not in contact with the flow of air passing through the interior of the nacelle.
• external is used when an organ is exposed to the airflow to be acoustically attenuated.
• internal means an organ that is not in contact with said air flow passing through the nacelle.
• Such panels can "trap” the noise and thus reduce noise emissions to the outside of the nacelle.
• a honeycomb core structure can be realized by assembling a plurality of cellular units in the form of rectangular plates interconnected by nodal joints.
• Each alveolar unit has a plurality of alveolar cells.
• the joining surface constituted by the contact surface between the nodal joints of a first cellular unit and the nodal joints of a second cellular unit is called the joining edge of cellular units.
• the acoustical properties of the acoustic panel ie its rate of noise absorption as a function of the frequency and sound level of the noise, depend in part on the junction with the septum of the cellular units, which form the structure. with alveolar core.
• the junction at the level of Joining edge of cellular units is commonly performed using a foaming glue, such as FM 410® glue.
• the septum When assembling and firing an acoustic panel, the septum, due to the difference in materials undergoes a thermal expansion of amplitude different from that of other surrounding materials. This induces offsets and delamination between the junction edges of the rectangular septum plates and the junction edges of the cellular units.
• a known solution is, during assembly, to avoid matching a junction edge of a septum plate with a joining edge of cellular units.
• An object of the present invention is to solve these disadvantages by proposing a septum intended to be associated with at least one cellular core structure, the assembly forming a resonator, and requiring substantially no repair after the baking phase of such a device. resonator.
• Another object of the invention is also to provide an acoustic panel incorporating a resonator comprising a septum according to the invention.
• the invention proposes such a septum made from at least two adjacent plates placed in edge-to-edge contact at the level of at least one joining edge of a septum plate. at least one angle between a joining edge of a septum plate and one of its adjacent sides is less than 90 °.
• one of the junction edges of the septum plates is bevelled so as to have an angle with one of their adjacent edges of less than 90 °.
• this feature of the invention allows to cause an angular offset between a joining edge of cellular units and a joining edge of a septum plate.
• An advantage of this angular offset is, during the cooking phase of such a septum integral with at least one honeycomb core structure, of to allow a better dispersion of the thermal deformations and to avoid a concentration and an accumulation of such deformations in only one direction and thus to avoid the detachment and the offset between a joining edge of a septum plate with a joining edge of alveolar units.
• At least one angle between a joining edge of a septum plate and one of its adjacent sides is substantially equal to 45 °.
• the adjustment of the septum plates is easier and the forces are better distributed on each cellular unit cell.
• At least one of the plates that make up the septum according to the invention is made of glass, in particular pierced.
• the invention also relates to a simple acoustic resonator remarkable in that it comprises a honeycomb core structure on the inner face of which is fixed by connecting means, in particular by bonding, at least one septum according to the invention. 'invention.
• the invention also relates to a double acoustic resonator comprising a first honeycomb core structure and a second honeycomb core structure, said structures being separated by a septum according to the invention, with the septum being attached to at least one of the core structures alveolar by connecting means, in particular by gluing.
• the invention also relates to an acoustic panel for nacelle of an aircraft comprising an acoustic resonator according to the invention on an outer face of which is fixed at least one permeable acoustic skin.
• an acoustic panel according to the invention comprises at least one impermeable solid skin fixed on an internal face of the acoustic resonator according to the invention.
• the invention relates to a nacelle for rboreactor comprising an acoustic panel according to the invention.
• FIG. 1 is a schematic cross sectional view of a double resonator panel
• FIG. 2 illustrates a deseptum plate constituting a septum according to the invention, positioned above the honeycomb;
• FIG. 3 illustrates septum plates according to the invention, positioned on a honeycomb core structure, specifying the offset between the joining edge of alveolar units and the joining edge of the septum plates.
• the present invention is not limited thereto and may relate to any acoustic panel structure implementing a septum.
• an acoustic panel 1 is composed of a sandwich structure comprising successively in the direction of thickness: an outer skin 3 multiperforated (acoustic skin), a double acoustic resonator 4 and an internal skin 6 (full skin).
• the outer skin 3 of the acoustic panel 1 is perforated and permeable to air. It forms the outer layer of the acoustic panel 1.
• the inner skin 6 of the acoustic panel 1 is not perforated and is impervious to air. It forms the inner layer of the acoustic panel 1.
• the outer skin 3 is perforated with a multitude of holes 5 of small diameter, in particular between 1, 2 and 1, 9 mm, typically equal to about 1, 5mm.
• the perforation of the skin is done by any suitable means known to those skilled in the art, such as a laser, a water jet or a conventional multi-spindle perforator.
• the holes 5 are spaced so that the ratio of the perforated surface to the total area including the holes allows the absorption of the desired noise frequency (s).
• a dual acoustic resonator 4 according to the invention comprises, in the direction of thickness, a first honeycomb core structure 9a and a second honeycomb core structure 9b (commonly called “honeycomb” structures) separated by a septum 11 according to the invention, said septum being fixed either on the inner face 1 3 of the honeycomb core structure 9a, or on the outer face 15 of the honeycomb core structure 9b, both on the inner face 13 of the honeycomb core structure 9a and on the outer face 15 of the honeycomb core structure 9b.
• such a honeycomb core structure 9a, 9b can be made of a light alloy, such as aluminum, or a material such as Nomex® which corresponds to a paper based on polyamide fibers and phenolic resin.
• each honeycomb core structure 9a, 9b is composed of a plurality of cellular units 10a, 10b.
• At least two cellular units 10a are interconnected by nodal joints in a direction substantially parallel to the longitudinal axis of the nacelle, said longitudinal axis of the nacelle being substantially perpendicular to the ribbon direction of the first honeycomb core structure 9a (respectively of the second honeycomb core structure 9b).
• Each cellular unit 10a, 10b has substantially the shape of a rectangular plate consisting of a plurality of cellular cells 12.
• the joining surface constituted by the contact surface between the nodal joints of a first cellular unit and the nodal joints of a second cellular unit is called the joining edge 14 of cellular units.
• the acoustic resonator 4 is said to be "double" and comprises two cellular core structures 9a and 9b enveloping a septum 11 according to the invention.
• the first honeycomb core structure 9a and the second honeycomb core structure 9b are each bonded to the septum 11 by an adhesive 17, or by any other means known to those skilled in the art.
• An acoustic skin 3 is fixed on the outer face 16 of the first honeycomb core structure 9a using an adhesive 8 for example.
• a solid skin 6 is also fixed on the inner face 20 of the second honeycomb core structure 9b by an adhesive 18.
• a simple acoustic resonator comprises a honeycomb core structure on the inner face of which is fixed by any means known to those skilled in the art, for example by gluing, a septum according to the invention.
• the septum according to the invention can occupy all or part of the surface formed by the inner face of the honeycomb core structure.
• An acoustic skin is attached to the outer face of the honeycomb core structure, for example by gluing or using an adhesive.
• a full skin may also be fixed directly on the septum according to the invention, said septum then constituting an inner face of the simple acoustic resonator.
• Said solid skin is fixed by any means known to those skilled in the art, in particular by gluing or with the aid of an adhesive.
• the acoustic panel thus formed is said acoustic panel single resonator and is intended to be arranged in particular in a turbojet engine nacelle to dampen the sound waves and mitigate the noise pollution thus generated.
• the septum 11 consists of several plates 19. At least two plates 19 are necessary to obtain a septum according to the invention.
• the septum plates 19 are used to make the septum advantageously advantageously in glass mechanically pierced by a method well known to those skilled in the art.
• the septum according to the invention comprises a plurality of adjacent plates placed in edge-to-edge contact at a junction edge 21 of the septum plates 19.
• the septum plates 19 constituting the septum 11 according to the invention are disposed on a first honeycomb core structure 9a, an edge 23 a septum plate 19 being arranged in a ribbon-like manner in a cellular unit 10a, 10b.
• the septum plates 19 are attached to the first honeycomb core structure 9a by any means known to those skilled in the art as previously described.
• the second honeycomb core structure 9b is then fixed on the septum 11 by any means known to those skilled in the art as described above.
• the resulting assembly thus forms the double acoustic resonator 4.
• a septum plate 19 has a junction edge 21 bevelled so as to have an angle ⁇ with one of its adjacent sides less than 90 °.
• This advantageous disposition makes it possible to be sure that the joining edge 21 of a septum plate 19 will not be colearary at a joining edge 14 of cellular units 10a, 10b during the assembly of the septum plates 19 on a honeycomb core structure 9a, 9b.
• this characteristic of the invention makes it possible to cause an angular offset ⁇ between a joining edge 14 of cellular units 10a, 10b and a joining edge 21 of a septum plate 19.
• an advantage of this angular offset ⁇ is, during the cooking phase of such a septum 1 1 integral with at least one honeycomb core structure 10a, 10b to allow a better dispersion of the thermal deformations and to avoid a concentrating and accumulating such deformations in a single direction to avoid delamination and misalignment between a joining edge 21 of a septum plate 19 with a joining edge 14 of cellular units 10a, 10b.
• the angle ⁇ between a joining edge 21 of a septum plate 19 and one of its adjacent sides 25 is substantially equal to 45 °.
• the adjustment of the septum plates 19 is easier and the forces are better distributed on each cell 12 of cellular unit 10a, 10b.
• the detachment effect between the septum and the honeycomb core structure is removed.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Mechanical Engineering (AREA)
• Aviation & Aerospace Engineering (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Securing Of Glass Panes Or The Like (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=46968292

Family Applications (1)

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Family Cites Families (14)

• 2011
  • 2011-09-21 FR FR1158388A patent/FR2980297B1/fr not_active Expired - Fee Related
• 2012
  • 2012-09-11 EP EP12767063.6A patent/EP2758955A1/de not_active Withdrawn
  • 2012-09-11 WO PCT/FR2012/052026 patent/WO2013041795A1/fr active Application Filing
  • 2012-09-11 CA CA2847668A patent/CA2847668A1/fr not_active Abandoned
  • 2012-09-11 BR BR112014006235A patent/BR112014006235A2/pt not_active IP Right Cessation
  • 2012-09-11 CN CN201280046112.XA patent/CN103827958A/zh active Pending
  • 2012-09-11 RU RU2014114646/28A patent/RU2014114646A/ru not_active Application Discontinuation
• 2014
  • 2014-03-20 US US14/220,671 patent/US9073622B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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