REINFORCED SOUND TREATMENT PLATE FOR AN AIRCRAFT ENGINE UNIT

Description

Technical Field

[0001] The invention relates to an acoustic treatment panel for absorbing sound waves, and more particularly to a panel also constituting a working element of a structure. Prior art

[0002] Conventionally, the reduction of noise from a turbojet engine, and more precisely that radiated by the interaction between the rotors and their environments, is achieved using absorbent panels placed on the wetted surfaces of the ducts in which the sound waves propagate. Wetted surfaces are surfaces in contact with a fluid flow. These panels are sandwich-type composite materials formed of a perforated (or acoustically porous) skin facing the noise-generating zone, a rear skin, and a honeycomb-type alveolar structure trapped between the rear skin and the perforated skin and whose absorbent properties are partly obtained thanks to the principle of Helmholtz resonators formed by the cells of the honeycomb forming acoustic absorption cells.These cells can have substantially prismatic shapes perpendicular to the skins, one or more additional perforated skins can also be added.

[0003] In general, the structural resistance of the panel in bending is provided by the skins, the honeycomb (NIDA) essentially playing the role of transmitting the shear between the skins, similar to the web of a beam. These panels can also be stressed in tension, with a tensile force exerted on one side by the inner skin and on the other side by the outer skin. This last case is very common on an air intake where it is necessary to connect the aerodynamic skin, the perforated one, to the monolithic lip of the air intake, but where the connection of the panel to the engine flange passes through a flange necessarily connected to the rear skin of the acoustic panel. This configuration then results in a shear induced by the thrust forces of the lip and their necessarily misaligned flange reaction.

[0004] In both the case of tension and bending, a major structural design problem arises relating to the concentration of shear stresses located on the edges of these acoustic panels, and in particular in the areas where the panel is connected to the rest of the structure.

[0005] Some acoustic panel architectures allow for an orthogonal cross-section of the two skins without providing a specific connection between the skins. In this architectural configuration, the honeycomb is much more sensitive to shear forces. Therefore, acoustic panels with this architecture are rather intended to be placed in locations where they will be subject to little shear stress or in locations that are highly optimized in terms of force introduction. This architecture nevertheless remains exceptional.

[0006] Indeed, in most cases, the edges, or contours, of acoustic panels correspond to structural connection zones, often with the introduction of a significant shear force. This generates a shear that most honeycombs cannot tolerate, even with sound absorption cells whose cavities have been filled with a structural component (strong foam or resin) called "potting" in English.

[0007] The most common solution illustrated on the figure 1 , which represents an acoustic panel 100 of the state of the art, is then to join the front skin 101, the perforated skin, and the rear skin 102 and to bind them together over the entire perimeter 103 of the acoustic panel 100. This is what is called the edging of the panel Pa.

[0008] In general, to achieve an edging as illustrated in the figure 1, the shape of the front skin 101 intended to be in contact with a fluid flow F is retained, while that of the rear skin 102 is modified as a chamfer 104 so that the rear skin 102 joins the front skin 101, the front skin 101 forming a so-called docking angle with the rear skin 102. We then have an inclined edging, which is by far the most applied.

[0009] Despite this design trick, this area often remains very critical in terms of shear. And the more obtuse the angle of docking of the two skins, the higher the shear peak, especially when this angle exceeds 60°. However, acoustic treatment is only effective if the honeycomb has a certain height tuned to the frequency of the noise to be attenuated. A low docking angle has the effect of having a large border with cells not having their full height, which therefore induces a significant loss of effective surface area around the perimeter of the panel, especially since these areas generally remain filled with reinforcing resin 105 (potting), which then completely cancels out the acoustic attenuation effect.

[0010] With a traditional design, the good structural behavior of the edging unfortunately harms the acoustic behavior of the sandwich panel, at least in its peripheral areas.

[0011] It is possible to considerably reinforce the rear skin to make it take up the shear in the case where the edging angle is large or even equal to 90°, but this is to the detriment of the mass and often keeping a portion of the honeycomb structure filled with potting. This design favors acoustics but penalizes the mass and / or the structural behavior of the panel.

[0012] Furthermore, when an acoustic treatment panel is placed on a wall of a turbomachine air inlet downstream of a lip delimiting the air inlet, this panel is generally connected to the surrounding structure in an awkward manner, in particular via a Z-shaped angle iron or an inclined edge, subject to tensile forces. Most of these problems arise from the fact that the honeycomb of the acoustic panel must be bypassed to connect the wall forming the lip to the rear skin of the panel, while the wall forming the lip is at the same level as the front skin. This leads to either a reduction in acoustic reduction (inclined edge), or a poorly arranged structure (with an impact on mass in the end).

[0013] Furthermore, in this configuration, and especially if part of the lip is provided with an acoustic treatment when using pneumatic defrosting, the front partition is heated strongly. As a result, the extended integrated acoustic panel is exposed to high temperatures and must be made of more expensive heat-resistant materials. In addition, in the state of the art, the attachment of this panel to the rest of the internal panel of the air intake is carried out substantially at the junction between the front partition and the internal panel. As a result, this partition requires either a non-acoustic zone located between the "hot" lip acoustic panel and the internal panel, or it connects to the internal panel, which induces a heat flow that is often unacceptable for the latter.This results in either a loss of acoustic efficiency or a loss of structural efficiency, which can be compensated for by adding reinforcement of the rear skin to the front of the internal panel in the form of thermal insulation inserts, which are very delicate and expensive to manufacture and which generate an increase in mass.

[0014] Document US 4,265,955 discloses an acoustic treatment panel according to the preamble of claim 1. Statement of the invention

[0015] The invention aims to provide an acoustic treatment panel for a turbomachine making it possible to solve the problems of force transfer and edge shear mentioned above without significantly compromising the acoustic behavior of the edges of the acoustic panel. In other words, the invention aims to provide an acoustic treatment panel having a structural reinforcement making it possible to have better resistance to the shear stresses that it may undergo when the turbomachine is in operation while using the entire surface of the panel for the acoustic treatment.

[0016] An object of the invention provides an acoustic treatment panel intended to be arranged on at least one wall of a propulsion assembly of an aircraft in contact with a fluid flow, the panel comprising a first acoustically reflective skin, a second acoustically porous skin intended to be in contact with a fluid flow, a honeycomb structure extending between the first skin and the second skin and comprising a plurality of cavities, and the acoustic treatment panel comprises at least one acoustically transparent reinforcing wall passing through a plurality of cavities of the honeycomb structure and extending from the second skin to the first skin forming a non-orthogonal angle with the first and second skins.

[0017] Said at least one reinforcing wall is formed in one piece with the first acoustically reflective wall. An acoustically porous wall is understood to mean a wall which comprises orifices allowing a portion of the acoustic waves to pass through without significantly altering them in terms of intensity or frequency. An acoustically opaque or acoustically reflective wall is understood to mean a wall which does not allow any acoustic waves to pass through without altering them at least in part, in particular in intensity. An acoustically opaque wall will reflect the majority of the incident acoustic waves.

[0018] The propulsion system of an aircraft is understood to mean, in particular, the system comprising a turbojet engine and a nacelle.

[0019] The connection between the first skin and the second skin provided by the reinforcing wall thus improves the resistance of the acoustic treatment panel to the shear forces it may be subjected to. And, thanks to the acoustic transparency of the reinforcing wall, this structural reinforcement is given to the acoustic treatment panel without degrading the surface of the panel, allowing acoustic absorption to be achieved, i.e. without degrading the effectiveness of the acoustic treatment of the panel.

[0020] According to a first aspect of the acoustic treatment panel, said acoustically transparent reinforcing wall preferably has a perforation rate greater than or equal to 18%.

[0021] A minimum perforation rate of 18% of the reinforcement wall ensures acoustic transparency of the reinforcement wall. The perforation rate corresponds to the ratio between the total perforated surface area of ​​the reinforcement wall and the total surface area of ​​the reinforcement wall, perforated or not.

[0022] Preferably the perforation rate is less than 80% to ensure acoustic transparency of the reinforcement wall while maintaining good force transfer capacity.

[0023] According to a second aspect of the acoustic treatment panel, the honeycomb structure may extend, in a plane parallel to the second skin, inside an outer perimeter, and said at least one reinforcing wall may extend inside the honeycomb structure from the second skin to the first skin over an edge portion of the honeycomb structure extending, in the plane parallel to the second skin, from said outer perimeter to the inside of the honeycomb structure.

[0024] The reinforcing wall(s) is / are therefore only located on the edge(s) of the acoustic treatment panel.

[0025] According to a third aspect of the acoustic treatment panel, the panel may further comprise at least one panel portion extending, in a direction orthogonal to the first skin, between a reinforcing wall and a portion of the first skin, said at least one panel portion being attached and fixed to the rest of the panel by co-firing during the manufacture of the panel. In another subject of the invention, an aircraft propulsion assembly is proposed intended to be mounted on an aircraft, the propulsion assembly comprising at least one acoustic treatment panel as defined above.

[0026] According to a first aspect of the propulsion assembly, the latter may comprise at least one air inlet provided with a front lip, an external wall and an internal wall, and connected to one of said acoustic treatment panels forming at least part of the internal wall.

[0027] According to a second aspect of the propulsion assembly, said reinforcing wall of said acoustic treatment panel may extend outside said panel and be connected to the front lip of the air inlet.

[0028] In another object of the invention, an aircraft is proposed comprising at least one propulsion unit as defined above.

[0029] In another subject of the invention, there is proposed a method of manufacturing an acoustic treatment panel intended to be arranged on at least one wall of an aircraft propulsion unit in contact with a fluid flow, the method of manufacturing the panel comprising a step of stacking a first acoustically reflective skin, a honeycomb structure and a second acoustically porous skin intended to be in contact with a fluid flow, the honeycomb structure extending between the first skin and the second skin and comprising a plurality of cavities.

[0030] The method further comprises a step of laying at least one acoustically transparent reinforcing wall passing through a plurality of cavities of the honeycomb structure and extending from the second skin to the first skin at a non-orthogonal angle with the first and second skins. Said at least one reinforcing wall is formed in one piece with the first acoustically reflective skin.

[0031] According to one aspect of the method according to the invention, the method may further comprise a step of producing at least one portion of panel intended to extend, in a direction orthogonal to the first skin, between a reinforcing wall and a portion of first skin, and a step of connecting by co-firing said at least one portion of panel to the rest of the panel. Brief description of the drawings

[0032] The invention will be better understood from the reading below, for informational but non-limiting purposes, with reference to the appended drawings in which: [ Fig. 1 ] There figure 1 , already presented, illustrates a sectional view of an acoustic treatment panel according to the state of the art. Fig. 2 ] There figure 2 shows a sectional view of a propulsion unit of an aircraft according to an embodiment of the invention, in a longitudinal plane of the propulsion unit of an aircraft. Fig. 3 ] There figure 3 illustrates a partial perspective view of an acoustic treatment panel according to one embodiment of the invention. Fig. 4 ] There figure 4 schematically presents a sectional view of the acoustic treatment panel of the figure 3 . [ Fig. 5 ] There Figure 5 shows a zoom of part of the acoustic treatment panel of the figure 4 with a triangular portion separated from the rest of the panel. Fig. 6 ] There figure 6 schematically shows a sectional view of a portion of the nacelle of the propulsion unit of the figure 2 at the air inlet channel according to a first embodiment. Fig. 7 ] There figure 7 schematically represents a sectional view of a portion of the nacelle of the propulsion unit of the figure 2 at the air inlet channel according to a second embodiment. Description of the embodiments

[0033] On the figure 2 a sectional view of a propulsion unit 1 of an aircraft according to a non-limiting embodiment of the invention is shown, in a longitudinal plane of the propulsion unit 1.

[0034] The propulsion assembly 1 comprises a nacelle 2, an intermediate casing 3 and an inner casing 4. The nacelle 2 and the two casings 3 and 4 are coaxial. The nacelle 2 defines at a first end an inlet channel 5 for a fluid flow and at a second end, opposite the first end, an exhaust channel 6 for a fluid flow. The nacelle 2 and the intermediate casing 3 delimit between them a primary fluid flow vein 7. The intermediate casing 3 and the inner casing 4 delimit between them a secondary fluid flow vein 8. The primary vein 7 and the secondary vein 8 are arranged in an axial direction of the propulsion assembly between the inlet channel 5 and the exhaust channel 6.

[0035] The propulsion assembly 1 further comprises a fan 9 configured to deliver an air flow F as fluid flow, the air flow F being divided at the outlet of the fan into a primary flow FP circulating in the primary vein 7 and into a secondary flow FS circulating in the secondary vein 8.

[0036] The propulsion assembly 1 further comprises at least one acoustic treatment panel 10 configured to attenuate the acoustic waves emitted by the propulsion assembly 1 before these waves escape radially to the outside of the nacelle 2 of the propulsion assembly 1.

[0037] In the case of an unducted turbomachine, the acoustic treatment would be configured to attenuate or limit the refractions of acoustic waves radiated by the propellers.

[0038] Each acoustic treatment panel 10 is configured to attenuate acoustic waves whose frequency belongs to a predetermined frequency range. In the embodiment illustrated in the figure 1 , the acoustic treatment panels 10 are integrated into the nacelle 2, the intermediate casing 3 and the internal casing 4. On the internal casing 4, the acoustic treatment panels 10 are integrated, on the one hand, on the upstream portion of the intermediate casing 3 in the axial direction and in particular on the portion carrying the fan 9, and, on the other hand, on a downstream portion of the intermediate casing 3.

[0039] On the figure 3 a partial perspective view of an acoustic treatment panel 10 according to one embodiment of the invention is shown.

[0040] In reference to the figure 3, the acoustic treatment panel 10 comprises a core 12, a reflective layer or wall 14 and an inlet layer or wall 16 intended to be in contact with a fluid flow F, FP or FS.

[0041] The core 12 has a honeycomb structure. More specifically, the core 12 comprises a plurality of acoustic cells 18, or alveoli, delimited by walls 180 and arranged according to a known honeycomb structure.

[0042] Each cell 18 opens onto a first face 121 of the core 12 and onto a second face 122 of the core 12 located opposite the first face 121.

[0043] The first face 121 of the core 12 is intended to be oriented towards the primary air flow duct 7 or secondary air flow duct 8 depending on the location of the acoustic treatment panel 10. The second face 122 of the core 12 is intended to be oriented opposite the air flow duct.

[0044] Depending on the embodiment, the core 12 may be made of metal, or of a composite material, such as a composite material formed of carbon fibers embedded in a hardened resin matrix.

[0045] The reflective layer 14 is adapted to reflect acoustic waves having a frequency belonging to the predetermined frequency range.

[0046] The reflective layer 14 extends opposite the second face 122 of the core 12, being in contact with the second face 122. More precisely, the reflective layer 14 is integral with the second face 122 of the core 12, for example glued to the second face 122 of the core 12.

[0047] Depending on the embodiment, the reflective layer 14 may be made of metal or a composite material, such as a composite material formed of carbon fibers embedded in a hardened resin matrix. In a variant, the layer forming the bottom of the cells 18 may be non-reflective.

[0048] The input layer 16 extends opposite the first face 121 of the core 12, being in contact with the first face 121. More precisely, the input layer 16 is integral with the first face 121 of the core 12, for example glued to the first face 121 of the core 12.

[0049] The inlet layer 16 is a perforated single-piece skin comprising a plurality of orifices 20 passing through the inlet layer 16 from the first face 161 to the second face 162 of the inlet layer 16. Each orifice 20 opens onto a cell 18 of the core 12, several orifices 20 being able to open onto the same cell 18. The inlet layer 16 thus has a porosity of approximately 10% to 15%.

[0050] The panels 10 may be so-called single degree of freedom panels, or SDOF in English for “single degree of freedom”, that is to say with a single layer of acoustic cells 18, or so-called two degree of freedom panels, or DDOF in English for “double degree of freedom”, that is to say with two layers of acoustic cells 18 superimposed on each other and separated by a septum, that is to say by an acoustically porous skin.

[0051] On the figure 4is schematically illustrated a sectional view of the acoustic treatment panel 10 of the figure 3 .

[0052] As illustrated in the Figures 3 and 4 , the acoustic treatment panel 10 has a general shape of a rectangular parallelepiped which has, in section, a general rectangular shape which can be curved to follow the walls of the nacelle on which it is mounted.

[0053] In section, as shown in the figure 4 , the acoustic treatment panel 10 therefore comprises a rectangular shape, with a width of the rectangle extending orthogonally between the input layer 16 and the reflective layer 14, and a length between a first longitudinal end 24 and a second longitudinal end 26, the first and second longitudinal ends 24 and 26 defining the edges of the panel 10.

[0054] At each end of the rectangle in the direction of its length, the panel 10 comprises a reinforcing wall 22 extending, inside the panel 10, in an oblique direction between the input layer 16 and the reflective layer 14. Each reinforcing wall 22 thus passes through a plurality of cavities 18 of the core 12. Each reinforcing wall 22 forms an angle α with the reflective layer 14 on the one hand and with the input layer 16 on the other hand.

[0055] Each reinforcing wall 22 is acoustically transparent, that is to say that it comprises orifices allowing part of the acoustic waves to pass through without significantly altering them in terms of intensity or frequency. In the example illustrated in the figure 4, the reinforcing walls 22 have a porosity rate greater than 18% and preferably between 18% and 80% to ensure acoustic transparency of the reinforcing wall 22 while retaining good force transfer capacity.

[0056] Each reinforcing wall 22 extends inside the core 12 from the corner formed by an edge 24 or 26 of the panel 10 and the input layer 16. The reinforcing wall 22 extends rectilinearly inside the core 12 until it reaches the reflective layer 14.

[0057] The angle α formed by a reinforcing wall with the input layer 16 is preferably between 15° and 70°.

[0058] The reinforcing wall 22 is made in a single piece with the portion 140 of the reflective layer 14 located between the reinforcing walls 22, the reinforcing wall 22 being perforated while the portion 140 of the reflective layer 14 between the reinforcing walls 22 is acoustically opaque. The portions 142 of the reflective layer 14 extending opposite a reinforcing wall 22, that is to say between an edge 24 or 26 and the portion 140 of the reflective layer 14 located between the reinforcing walls 22, being added over the reinforcing walls 22 during the manufacture of the panel 10 and secured to the rest of the panel 10 by aligning the walls 180 of the cells 18 of the core 12 to ensure the effectiveness of the acoustic treatment. The walls 180 of the cells 18 may not be perfectly aligned without the effectiveness of the acoustic treatment being too affected. Indeed, the walls 180 guide the acoustic wave into the cells 18.If the walls 180 have parallel foils, this guidance is carried out correctly even if the walls 180 are not aligned on either side of the reinforcing wall 22 as long as the latter is acoustically transparent. The term foil designates, for a honeycomb, the walls defining the cells.

[0059] The triangular portion, illustrated in particular on the figures 4 And 5 , there Figure 5 showing a zoom of the Figure 5 with the triangular portion separated on the rest of the panel, separated from the rest of the panel by a reinforcing wall 22 can be added and co-fired during manufacture.

[0060] On the figure 6 is schematically illustrated a sectional view of a portion of the nacelle 2 of the propulsion unit 1 of the figure 2 according to one embodiment of the invention.

[0061] On the figure 6the inlet channel 5 receiving the fluid flow F and the portion of the nacelle 2 which radially delimits the inlet channel 5 on the outside are illustrated. The nacelle 2 comprises at this location a rounded front lip 51 extending on one side by a radially external wall 52 of the nacelle 2 and, on the other side, by a radially internal wall 53 of the nacelle 2.

[0062] To reinforce the structure of the nacelle 2 on this portion, the nacelle comprises a reinforcing partition 54. The reinforcing partition 54 comprises an external portion 541 fixed to the radially external wall 52, an internal portion 542 fixed to the radially internal wall 51, and a central portion 543 extending between the internal portion 542 and the external portion 541 in a rectilinear direction, at a distance from the front lip 51.

[0063] The nacelle 2 comprises an acoustic treatment panel 10 as described above. The panel 10 is mounted on the radially inner wall 53 of the nacelle 2 so that its inlet layer 16 is in contact with the fluid flow F. The panel 10 comprises on its edge 24 visible on the figure 6 , a fixing edge 30 which comes in the extension of the input layer 16, outside the area covered by the core 12 of the panel 10.

[0064] In one embodiment, the fixing edge 30 can be fixed on the radially internal wall 53 of the nacelle, upstream of the internal portion 542 of the reinforcing partition 54 or on the internal portion 542 of the reinforcing partition 54.

[0065] In another embodiment, the reinforcing partition 54 and the fixing edge 30 on the side of the edge 24 of the panel 10 can be made in a single piece.

[0066] On the figure 7an alternative embodiment of the inlet channel of the figure 6 In this variant, the nacelle comprises two acoustic treatment panels: a first conventional acoustic panel 100 without a reinforcing wall, and a second acoustic treatment panel 10 comprising a reinforcing wall 22, the first panel 100 being adjacent to the second panel 10. The second acoustic treatment panel 10 is crossed over its entire length by the reinforcing wall 22. Upstream, the reinforcing wall 22 extends outside the panel 10 in the extension of the second skin 16 and is fixed to the internal portion 542 of the reinforcing partition 54. And downstream, the reinforcing wall 22 extends outside the panel 10 in the extension of the first skin 14 and is fixed to the first acoustic treatment panel 100.

[0067] In other words, the fixing edge 30 which extends in the extension of the entry layer 16, can be formed by the portion of reinforcing wall 22 extending outside the panel 10 in the extension of the second skin 16.

[0068] Thus, the two fixing edges 30, the two reinforcing walls 22 and the portion 140 of reflective layer 14 located between the reinforcing walls 22 can be formed from the same material, or even in a single piece.

[0069] The second skin 16 of the second acoustic treatment panel 10 is not integral with the radially internal wall 53 of the nacelle 2.

[0070] Furthermore, in this embodiment, the height of the two panels 10 and 100 may be different.

[0071] The invention thus makes it possible to provide an acoustic treatment panel for a turbomachine having a structural reinforcement allowing better resistance to the shear stresses that it may undergo when the turbomachine is in operation while using the entire surface of the panel for acoustic treatment.

Claims

1. An acoustic treatment panel (10) intended to be disposed on at least one wall of an aircraft propulsion unit (1) in contact with a fluid flow, the panel (10) comprising a first acoustically reflective skin (14), a second acoustically porous skin (16) intended to be in contact with a fluid flow (F, FP, FS), a honeycomb structure (12) extending between the first skin (14) and the second skin (16) and comprising a plurality of cavities (18), and at least one acoustically transparent reinforcing wall (22) passing through a plurality of cavities (18) of the honeycomb structure and extending from the second skin (16) to the first skin (14) forming a non-orthogonal angle with the first and second skins (14 and 16), characterised in that said at least one reinforcing wall (22) is formed in one piece with the first acoustically reflective wall (14).

2. The acoustic treatment panel (10) according to claim 1, wherein said at least one acoustically transparent reinforcing wall (22) has a perforation rate greater than or equal to 18%.

3. The acoustic treatment panel (10) according to one of claims 1 or 2, wherein the honeycomb structure (12) extends, in a plane parallel to the second skin (16), inside an outer perimeter, and said at least one reinforcing wall (22) extends inside the honeycomb structure (12) from the second skin (16) to the first skin (14) on a border portion (24, 26) of the honeycomb structure (12) extending, in the plane parallel to the second skin (16), from said outer perimeter to the interior of the honeycomb structure (12).

4. The panel (10) according to one of claims 1 to 3, wherein the reinforcing wall (22) comprises a fastening portion extending to the outside of the panel (10) in the elongation of the second skin (16), the fastening portion being intended to be coupled to a wall of the propulsion unit (1).

5. The panel (10) according to one of claims 1 to 4, wherein the reinforcing wall (22) comprises a fixing portion extending to the outside of the panel (10) in the elongation of the first skin (14), the fixing portion being intended to be coupled to a wall of the propulsion unit (1).

6. The panel (10) according to one of claims 1 to 4, comprising at least one portion of panel (10) extending, in a direction orthogonal to the first skin (14), between a reinforcing wall (22) and a portion of (142) the first skin (14), said at least one portion of panel being attached and fixed to the remainder of the panel by co-firing during the manufacture of the panel.

7. A propulsion unit (1) intended to be mounted on an aircraft, the propulsion unit (1) comprising at least one acoustic treatment panel (10) according to one of claims 1 to 6.

8. The propulsion unit (1) according to claim 7, comprising at least one air inlet (5) provided with a front lip (51), an outer wall (52) and an inner wall (53), and connected to one of said acoustic treatment panels (10) forming at least one part of the inner wall (53).

9. The propulsion unit (1) according to claim 8, wherein said reinforcing wall (22) of said acoustic treatment panel (10) continues outside of said panel (10) and is connected to the front lip (51) of the air inlet (5).

10. An aircraft comprising at least one propulsion unit (1) according to one of claims 6 to 9.

11. A method for manufacturing an acoustic treatment panel (10) intended to be disposed on at least one wall of an aircraft propulsion unit (1) in contact with a fluid flow, the method for manufacturing the panel (10) comprising a step of stacking a first acoustically reflective skin (14), a honeycomb structure (12) and a second acoustically porous skin (16) intended to be in contact with a fluid flow (F, FP, FS), the honeycomb structure (12) extending between the first skin (14) and the second skin (16) and comprising a plurality of cavities (18), and a step of installing at least one acoustically transparent reinforcing wall (22) passing through a plurality of cavities (18) of the honeycomb structure and extending from the second skin (16) to the first skin (14) forming a non-orthogonal angle with the first and second skins (14 and 16), characterised in that said at least one reinforcing wall (22) is formed in one piece with the first acoustically reflective wall (14).

12. The method according to claim 11, comprising a step of producing at least one portion of panel intended to extend, in a direction orthogonal to the first skin (14), between a reinforcing wall (22) and a portion (142) of the first skin (14), and a step of connecting, by co-firing, said at least one portion of panel to the remainder of the panel.