Sound insulation panel with inclined cavity

Abstract

The present invention relates to a sound insulation panel (20), comprising a first set of cavities (31) oriented toward the front end of the panel (20) and a second set of cavities (31B) oriented toward the rear end of the panel (20).

Description

Technical Field

[0001] This invention relates to the field of sound insulation panels for the aviation industry. Background Technology

[0002] Traditional aircraft propulsion components include sound-absorbing panels, often referred to as "sandwich panels," which consist of two outer layers and a microporous structure sandwiched between them. The microporous structure is typically a honeycomb structure that forms sound-absorbing cavities or Helmholtz chambers, allowing for the attenuation of noise generated by the propulsion component. For this purpose, the outer layer, oriented towards the noise source, is made breathable, often using openings through it to guide air into the cavity and thus absorb sound energy.

[0003] Generally, the thickness of the plate determines the length of the cavity, which in turn determines its attenuation capability. In particular, longer cavities allow for the attenuation of longer waves, thus attenuating lower frequencies.

[0004] To reduce the footprint of the plate while attenuating the low frequencies generated by the propulsion components, it is known to tilt the cavity in the manner described in documents US3821999 and WO92 / 12854.

[0005] The solutions proposed in these documents present challenges in the manufacture of contemporary thermosetting composite panels, which typically include beveled edges, also known as chamfers. Such chamfers allow the two surfaces of the panel to be joined to form an integral return section for closing the panel.

[0006] Figure 1 A plate A1 is shown, which includes a perforated surface layer A2, a solid surface layer A3, and a microporous structure A4 forming inclined cavities A5. Plate A1 includes a front edge A6 and an inclined rear edge A7. In this example, the cavities A5 are oriented toward the front edge A6 of plate A1 such that their axes A8 form a relatively large angle A9 with the front edge A6 and a relatively small angle A10 with the rear edge A7.

[0007] Given such an angle A10, there is a risk that plate A1 may collapse at its rear edge A7 under the pressure applied during its curing process. Summary of the Invention

[0008] The purpose of this invention is to provide a sound insulation panel that can attenuate low frequencies while reducing the footprint.

[0009] The present invention also aims to overcome the aforementioned manufacturing difficulties.

[0010] Another object of the present invention is to provide a lightweight plate.

[0011] Another objective of this invention is to reduce the cost of manufacturing such a board.

[0012] Therefore, the present invention relates to a soundproof panel for an aircraft propulsion assembly, comprising a first surface layer, a second surface layer, and a microporous structure forming sound-absorbing cavities, each sound-absorbing cavity extending along an inclined axis relative to the first surface layer. According to the invention, the cavities are distributed into several groups comprising a first group and a second group, wherein the cavities in the first group are oriented toward the front end of the panel, and the cavities in the second group are oriented toward the rear end of the panel.

[0013] On the one hand, the tilt of the cavities allows them to have an acoustic length greater than the distance between the first and second surfaces. Therefore, this invention allows for a reduction in plate size while maintaining good acoustic performance, particularly attenuation at frequencies with a given footprint compared to conventional plates.

[0014] On the other hand, distributing the cavities into two sets of different orientations allows for a reduction in the risk of collapse during manufacturing, while also enabling the production of plates with beveled edges. Therefore, the plates do not require components for supporting or joining the surface layers at the front and rear ends, nor do they require stabilizing components, which allows for reduced plate weight and cost.

[0015] Therefore, the present invention allows for the provision of a soundproof plate compatible with the geometry of the ramp edge and a new generation of propulsion components, which differs from conventional propulsion components in that it has a larger overall diameter, a lower fan speed, and therefore a lower attenuation frequency.

[0016] In one embodiment, the microporous structure includes a front block forming a first set of cavities and a rear block forming a second set of cavities.

[0017] Producing the microporous structure in two parts makes the fabrication and assembly of the board much easier.

[0018] Of course, a microporous structure may include more than two blocks. For example, a microporous structure may include the aforementioned front block and rear block, as well as one or more intermediate blocks extending between the front block and the rear block. As another example, a microporous structure may include the aforementioned front block and rear block forming a first layer or level of the microporous structure, and one or more other blocks forming a second layer or level of the microporous structure.

[0019] In one embodiment, the microporous structure includes a front edge and a rear edge, each of which is oblique.

[0020] Preferably, the front edge is formed by the front block and the rear edge is formed by the rear block.

[0021] In one embodiment, several cavities of the first group open on the front edge of the microporous structure, and several cavities of the second group open on the rear edge of the microporous structure.

[0022] The second surface layer preferably includes the front portion of the front edge covering the microporous structure.

[0023] Preferably, the second surface layer includes a rear portion covering the rear edge of the microporous structure.

[0024] The second surface layer also preferably includes a middle portion that connects the front and rear portions of the second surface layer to each other and covers the surface of the microporous structure.

[0025] In one embodiment, the front and rear portions of the second surface layer extend obliquely relative to the middle portion of the second surface layer to engage the first surface layer.

[0026] Preferably, the front and rear edges of the microporous structure each form an angle between 30 and 60 degrees with the first surface layer, more preferably between 40 and 50 degrees, for example, equal to or close to 45 degrees.

[0027] Of course, if the first surface is not flat, this angle can be formed with an imaginary plane tangent to the first surface.

[0028] Furthermore, the front edge and / or rear edge may be curved. In this case, the aforementioned angle can be formed by an imaginary plane tangent to the front edge and / or the corresponding rear edge.

[0029] In one embodiment, the axis of each cavity forms an angle of inclination between 30 and 50 degrees relative to the first surface layer, more preferably between 35 and 45 degrees, for example equal to or close to 45 degrees.

[0030] Of course, if the first surface is not flat, the axis can be tilted relative to an imaginary plane tangent to the first surface.

[0031] In one embodiment, the first surface layer and / or the second surface layer comprises an organic matrix composite material.

[0032] More preferably, the aforementioned material is a thermosetting composite material, that is, its matrix includes a thermosetting polymer.

[0033] In one embodiment, the microporous structure comprises a metallic material.

[0034] In one embodiment, the plate forms a cylindrical structure or a portion thereof.

[0035] In one embodiment, the plate forms at least one flat surface.

[0036] In one embodiment, the microporous structure comprises several levels.

[0037] Preferably, each stage of the microporous structure may include a first group of cavities and a second group of cavities.

[0038] The present invention also relates to a propulsion assembly for an aircraft, comprising at least one plate as defined above.

[0039] In one embodiment, the plate forms the housing of a turbine engine for a propulsion assembly, or is fixed to such a housing.

[0040] The aforementioned housing can be a fan housing.

[0041] In one embodiment, the plate forms part of the nacelle of the propulsion assembly.

[0042] According to another aspect, the present invention also relates to a method for manufacturing a plate as defined above.

[0043] In one embodiment, the method includes the step of assembling the board, followed by the step of curing the board.

[0044] In one embodiment, the assembly step includes placing a microporous structure on a first surface layer and placing a second surface layer on the microporous structure.

[0045] In one embodiment, the step of placing the microporous structure on the first surface layer includes placing the front block of the microporous structure on the front portion of the first surface layer and placing the rear block of the microporous structure on the rear portion of the first surface layer, such that the front block and the rear block of the microporous structure are adjacent to each other.

[0046] Other advantages and features of the invention will become apparent from the following detailed, non-limiting description. Attached Figure Description

[0047] The following detailed description refers to the accompanying drawings, in which:

[0048] The already described [ Figure 1 [This is a schematic cross-sectional view of a plate including its sloping front and rear edges and its inclined Helmholtz cavity;]

[0049] [ Figure 2 [This is a schematic longitudinal section of an aircraft propulsion assembly equipped with sound insulation panels;]

[0050] [ Figure 3 [I] is a schematic cross-sectional view of a plate according to a first embodiment of the present invention, the plate comprising two block-shaped microporous structures sandwiched between two surface layers, each block comprising a sound-absorbing cavity oriented in a corresponding direction;

[0051] [ Figure 4 ]yes Figure 3 A schematic cross-sectional view of one of the blocks of the plate;

[0052] [ Figure 5 [Image 1] is a schematic cross-sectional view of a plate according to a second embodiment of the present invention, the plate comprising a microporous structure in the form of three blocks sandwiched between two surface layers.

[0053] [ Figure 6 [Illustrated cross-sectional view of a plate according to a third embodiment of the present invention, the plate comprising a two-level microporous structure sandwiched between two surface layers.] Detailed Implementation

[0054] Figure 2 The subsequent figures include reference frames D1, D2, and D3, which define the longitudinal / axial, circumferential / tangential, and radial directions that are orthogonal to each other.

[0055] exist Figure 2 The image shows a simplified propulsion assembly 1 for an aircraft, which includes a turbine engine 3 and a nacelle 4 extending around a central longitudinal axis 2. In this example, the turbine engine 3 is a turbofan engine.

[0056] Subsequently, the terms "front" and "rear" are considered along the main direction S1 of the airflow in the propulsion assembly 1, parallel to the axis 2 of direction D1.

[0057] In a manner known per se, the propulsion assembly 1 includes, from front to back, an air inlet 5, a fan 6, a secondary flow path 7 defined radially inward by an internal cowl 8 and radially outward by elements of the nacelle 4, and a duct 10 for ejecting the main stream of gas from the gas generator 9, wherein the internal cowl 8 surrounds the gas generator 9 formed by the turbojet engine 3. The duct 10 includes an injection cone 11 and an injection nozzle 12.

[0058] More specifically, the present invention relates to a soundproof plate 20 intended for equipping such a propulsion assembly 1.

[0059] In this non-limiting example, the propulsion assembly 1 includes a plurality of sound-insulating panels 20 as described below. Figure 2 These plates 20 are shown in thick lines. The plates 20 include a plate 20A forming the inner wall of the air inlet 5, a plate 20B forming part of the internal shroud 8, a plate 20C defining the secondary flow path 7, a plate 20D forming the outer wall of the injection cone 11, and a plate 20E forming the inner wall of the injection nozzle 12.

[0060] In this example, each of plates 20A to 20E extends circumferentially around axis 2, forming an annular portion. Therefore, specifically, each plate 20A extends along its corresponding circumferential portion to together form a cylindrical structure with axis 2. The description just given regarding plate 20A applies by analogy to plates 20B to 20E.

[0061] exist Figure 3 The cross-section shown in the middle illustrates a plate 20 according to a first embodiment of the present invention, with sections parallel to directions D1 and D3.

[0062] The plate 20 includes a first surface layer 21, a second surface layer 22, and a microporous structure 23, which in this example includes a front block 24 and a rear block 25.

[0063] refer to Figure 4 The front block 24 has an inner surface 26, an outer surface 27, a front surface 28 forming the front edge of the microporous structure 23, and a rear surface 29, thereby giving the front block 24 a quadrilateral cross-section.

[0064] In this example, surfaces 26 to 29 of the front block 24 are... Figure 4 The cross-section is shown as flat. Specifically, in this cross-section, surfaces 26 and 27 are shown parallel to the axial direction D1, and the rear surface 29 is shown parallel to the radial direction D3. Of course, one or more of these surfaces 26 to 29 can be... Figure 4 The cross-section has a curved geometry and / or other cross-sections.

[0065] In this example, the front block 24 extends along the circumferential direction D2 to form a part of a cylindrical structure.

[0066] The front block 24 includes a spacer 30 defining a cavity 31, which extends radially and axially.

[0067] In this example, some of these cavities 31 have an opening on the inner surface 26 on one side and an opening on the front surface 28 on the other side, some of these cavities 31 have an opening on the inner surface 26 on one side and an opening on the outer surface 27 on the other side, and other cavities 31 have an opening on the rear surface 29 on one side and an opening on the outer surface 27 on the other side.

[0068] Each cavity 31 extends along an inclined axis 32 relative to the inner surface 26 and the outer surface 27.

[0069] In this example, the axis 32 of each cavity 31 forms an angle 33 of approximately 45 degrees with surfaces 26 and 27.

[0070] The front surface 28 then forms an angle 34 of approximately 45 degrees relative to the inner surface 26 of the front block 24, making the front edge of the microporous structure 23 oblique.

[0071] As a result, in this particular example, the axis 32 of the cavity 31 that opens on the front surface 28 of the front block 24 forms an angle of approximately 90 degrees with the front surface 28, which allows for a reduction in the risk of the plate 20 collapsing at the front edge during curing.

[0072] Regarding the geometry of the cavities 31, in this example, the spacer 30 is configured such that each cavity 31 has a hexagonal cross-section in a plane perpendicular to axis 32. Alternatively, one or more cavities 31 may include a triangular cross-section, a square cross-section, and so on. The cavities 31 may have any other shape that specifically allows for the avoidance of bleed-through.

[0073] In a manner known per se, the spacer 30 includes a drainage recess (not shown) at the outer surface 27. In this example, such a recess is also formed at the front surface 28 of the block 24 in order to maximize the acoustic surface.

[0074] refer to Figure 3 In this example, the rear block 25 is symmetrical to the front block 24 with respect to a transverse plane parallel to directions D2 and D3.

[0075] Therefore, the rear block 25 has an inner surface 26B, an outer surface 27B, a rear surface 28B forming a rear edge of the microporous structure 23, a front surface 29B, and a cavity 31B, which also extends radially and axially, but in the opposite direction to the cavity 31 of the front block 24.

[0076] In other words, the cavities 31B of the rear block 25 each extend along an axis 32B that is inclined relative to the axis 32 of the cavity 31 of the front block 24.

[0077] The description of the preceding block 24 also applies to the following block 25.

[0078] In this example, blocks 24 and 25 are arranged axially adjacent such that the rear surface 29 of the front block 24 faces the front surface 29B of the rear block 25.

[0079] The first surface layer 21, also known as the inner surface layer, is radially disposed on one side of the microporous structure 23 to cover the inner surface 26 of the front block 24 and the inner surface 26B of the rear block 25.

[0080] The inner surface layer 21 matches the inner surfaces 26 and 26B of the microporous structure 23, and the aforementioned angles 33 and 34 are also formed between the axis 32 of the cavity 31 and the inner surface layer 21, and between the front edge 28 of the microporous structure 23, respectively. This also applies to the corresponding angles associated with the rear block 25 of the microporous structure 23.

[0081] Still referencing Figure 3 The second surface layer 22, also known as the outer surface layer, is radially disposed on the other side of the microporous structure 23 so as to cover the front part of the inner surface layer 21, the front edge 28 of the microporous structure 23, the outer surface 27 of the front block 24, the outer surface 27B of the rear block 25, the rear edge 28B of the microporous structure 23, and the rear part of the inner surface layer 21 from front to back, respectively.

[0082] Therefore, plate 20 has a sloping front edge defined by the front surface 28 of the front block 24 of the microporous structure 23, and a sloping rear edge defined by the rear surface 28B of the rear block 25 of the microporous structure 23.

[0083] In this example, the outer layer 22 is solid, while the inner layer 21 includes openings (not shown) on at least a portion of its surface designed to guide air into cavities 31 and 31B for absorbing acoustic energy.

[0084] Therefore, the cavity 31 formed by the front block 24 of the microporous structure 23 is oriented toward the front end of the plate 20, while the cavity 31B formed by the rear block 25 of the microporous structure 23 is oriented toward the rear end of the plate 20.

[0085] exist Figure 3 In the example, plate 20 has a thickness 50 or radial dimension between 20 mm and 40 mm, and surfaces 21 and 22 each have a thickness between 0.2 mm and 2 mm, for example, 1 mm.

[0086] In this example, surfaces 21 and 22 are made of a composite material with a thermosetting matrix, such as carbon fiber with epoxy resin, and the microporous structure 23 is formed of aluminum foil. In an alternative embodiment, the microporous structure 23 is made of an organic material, such as [material name missing]. The known materials. In another alternative embodiment, the microporous structure 23 is made of an organic matrix composite material.

[0087] Figure 5 A plate 20 according to a second embodiment of the present invention is shown, which is... Figure 3 The difference between this plate and the previous one lies in the fact that the microporous structure 23 includes a third block 40, also known as the intermediate block. This is solely based on its relationship with... Figure 3 To describe the difference between the boards Figure 5 The above description of the first embodiment is applied by analogy to the second embodiment.

[0088] refer to Figure 5 The middle block 40 extends axially between the front block 24 and the rear block 25.

[0089] The intermediate block 40 also includes cavities 31C, each extending along an axis 32C that is inclined relative to the inner surface 26C and the outer surface 27C of the block 40.

[0090] In this example, the cavity 31C of the intermediate block 40 is oriented in the same axial direction as the cavity 31B of the rear block 25, that is, it is oriented toward the rear of the plate 20, but the angle 33C formed is different from the corresponding angle 33B formed by the cavity 31B of the rear block 25.

[0091] In an alternative embodiment not shown, the cavity 31C of the intermediate block 40 is oriented in the same axial direction as the cavity 31 of the front block 24.

[0092] Board 20 may of course include and Figure 5 Block 40 is similar to several intermediate blocks.

[0093] The microporous structure 23, including one or more intermediate blocks 40, particularly allows for an increase in the axial dimension of the plate 20.

[0094] Figure 6 A plate 20 according to a third embodiment of the present invention is shown, which is... Figure 3 The difference between this plate and the previous one lies in the fact that the microporous structure 23 includes a second level. This is solely based on its relationship with... Figure 3 To describe the difference between the boards Figure 5 The above description of the first embodiment is applied by analogy to the third embodiment.

[0095] refer to Figure 6 The front block 24 and the rear block 25 form the first level, while the second level also includes the front block 41 and the rear block 42 placed on the outer surfaces of the blocks 24 and 25 of the first level.

[0096] In this example, the second-stage front block 41 includes a cavity 31D oriented parallel to the cavity 31 of the first-stage front block 24, while the second-stage rear block 42 includes a cavity 31E oriented parallel to the cavity 31B of the first-stage rear block 24.

[0097] Of course, the orientation of cavity 31D can be different from that of cavity 31. Similarly, the orientation of cavity 31E can be different from that of cavity 31B.

[0098] exist Figure 6 In the example, the rear surface 29 of the first-stage front block 24 is axially offset relative to the rear surface 29C of the second-stage front block 41, and correspondingly, the front surface 29B of the first-stage rear block 25 is axially offset relative to the front surface 29D of the second-stage rear block 42. This offset allows for improved mechanical strength of the microporous structure 23.

[0099] In a manner known per se, the spacer (not shown) is preferably inserted between the two stages of the microporous structure 23. The spacer may comprise a composite material, such as glass fiber impregnated with microporous epoxy resin, or a metal fabric (e.g., made of aluminum), or an organic material of the polyetheretherketone type.

[0100] The above embodiments can be combined. For example, Figure 6 The microporous structure 23 may include one or more intermediate blocks that are axially positioned between the first-stage blocks 24 and 25 and / or between the second-stage blocks 41 and 42.

[0101] The invention is not limited to the embodiments just described. For example, in an embodiment not shown, the inner surface layer 21 is solid and the outer surface layer 22 is provided with openings.

[0102] In addition, plate 20 can have the same Figures 3 to 6 The geometry shown in the figure is different from the geometry. For example, the front block 24 and the rear block 25 may be asymmetrical and / or form cavities 31 and / or 31B with angles different from those given above as examples.

Claims

1. A soundproof panel (20) for an aircraft propulsion assembly (1), comprising a first surface layer (21), a second surface layer (22), and a microporous structure (23) forming sound-absorbing cavities (31, 31B), each sound-absorbing cavity extending along an inclined axis (32, 32B) relative to the first surface layer (21), characterized in that The cavities (31, 31B) are distributed into several groups, including a first group and a second group. In the first group, the cavities (31) are oriented towards the front end of the plate (20) along the axial direction of the aircraft propulsion assembly, and in the second group, the cavities (31B) are oriented towards the rear end of the plate (20) along the axial direction of the aircraft propulsion assembly. The tilt of the cavities allows them to have an acoustic length greater than the distance between the first and second surfaces. The microporous structure (23) includes a front block (24) forming the first group of cavities (31) and a rear block (25) forming the second group of cavities (31B).

2. The plate (20) according to claim 1, wherein the microporous structure (23) includes a front edge (28) and a rear edge (28B), the front edge (28) and the rear edge (28B) being oblique.

3. The plate (20) according to claim 2, wherein a plurality of the cavities (31) of the first group open on the front edge (28) of the microporous structure (23), and a plurality of the cavities (31B) of the second group open on the rear edge (28B) of the microporous structure (23).

4. The plate (20) according to claim 2, wherein the second surface layer (22) includes a front portion of the front edge (28) covering the microporous structure (23) and a rear portion of the rear edge (28B) covering the microporous structure (23).

5. The plate (20) according to claim 2, wherein the front edge (28) and rear edge (28B) of the microporous structure (23) each form an angle (34) with the first surface layer (21) between 30 degrees and 60 degrees.

6. The plate (20) according to claim 1, wherein the axis (32, 32B) of each cavity (31, 31B) forms an angle (33) between 30 degrees and 50 degrees with respect to the first surface layer (21).

7. The plate (20) according to claim 1, wherein the first surface layer (21) and / or the second surface layer (22) comprises an organic matrix composite material, and the microporous structure (23) comprises a metallic material.

8. The plate (20) according to claim 1, wherein the microporous structure (23) comprises several levels, each level comprising a first group of cavities and a second group of cavities.

9. A propulsion assembly (1) for an aircraft, comprising at least one plate according to claim 1.

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