Air intake lip of a turbofan engine nacelle including an acoustic device and method for manufacturing such lip

Abstract

An air intake lip (2a) of a nacelle of an aircraft turbojet engine, the nacelle extending along an axis X, with the air flow flowing from upstream to downstream in the nacelle, the lip (2a) extending circumferentially around the axis X and including an inner wall (21) facing the axis X and an outer wall (22) opposite to the inner wall (21), the inner wall (21) and the outer wall (22) being connected by an upstream wall (23) to define an annular cavity (20), the lip (2a) including an annular acoustic device (50) mounted in the annular cavity (20), the lip (2a) being provided with a first module (M1) and a second module (M2), the first module (M1) including the outer wall (22), the upstream wall (23) and a front wall (24) forming the upstream part of the inner wall (21), the second module (M2) including the acoustic device (50) and a front housing (51) forming the downstream part of the inner wall (21), the first module (M1) and the second module (M2) being fixedly connected to each other so that the front wall (24) and the front housing (51) together form the inner wall (21) of the lip (2a).

Description

Field of the Invention

[0001] The present invention relates to the field of aircraft turbojet engines, and more particularly to the inlet lip of the nacelle of an aircraft turbojet engine. Background Art

[0002] It is known that an aircraft includes one or more turbojet engines in order to achieve aircraft propulsion by accelerating the airflow flowing from upstream to downstream in the turbojet engine.

[0003] Reference Figure 1 shows a turbojet engine 100 extending along axis X. The turbojet engine 100 includes a fan 110 that is rotatably mounted about axis X in a nacelle including an inner casing 112 in order to accelerate the airflow F from upstream to downstream. The terms "upstream" and "downstream" are defined in the flow direction of the airflow F. The turbojet engine 100 includes an inlet duct 102 at its upstream end. The inlet duct is used to separate the incoming airflow F into an internal airflow FINT that is accelerated by the fan 110 and an external airflow FEXT that is guided outside the nacelle.

[0004] Reference Figure 1 shows that the inlet duct 200 includes an upstream portion and a downstream portion that are referred to as a lip by those skilled in the art. In this embodiment, the lip 102a is separated from the downstream portion 102b by an inner partition wall 125.

[0005] The lip 102a includes an inner wall 121 facing the axis X and an outer wall 122 opposite to the inner wall 121. The inner wall 121 and the outer wall 122 are connected by an upstream wall 123 to form an annular cavity 120. Thus, the lip 102a enables the incoming airflow F to be separated into an internal airflow FINT guided by the inner wall 121 and an external airflow FEXT guided by the outer wall 122. Hereinafter, the terms "inner" and "outer" are defined in the radial direction of the axis X of the turbine 100.

[0006] The airflow flowing on the inner wall 121 of the lip 102a generates noise, and an annular acoustic device needs to be assembled on the lip 102a to reduce the noise.

[0007] Reference Figure 2 shows a lip 102a equipped with an acoustic device 104 disclosed in the patent application W01216 / 005711. The acoustic device 104 includes a rear housing 142, and an acoustic material, specifically a honeycomb material 140, is connected to the housing 142. In practice, the rear housing 142 is welded to the acoustic material 140. The acoustic device 104 is installed in the annular cavity 120, and the annular cavity 120 is located on the inner surface of the inner wall 121 of the lip 102a.

[0008] In order to integrate such an acoustic device 104, the rear housing 142 must be connected to the inner surface of the inner wall 121, and a plurality of holes (not shown) are formed in the inner wall 121 so that the internal air flow FINT can flow through the acoustic device 104, thereby reducing noise.

[0009] In practice, the rear housing 142 of the acoustic device 104 is welded to the inner surface of the inner wall 121 of the flange 102a using a 6061-type alloy compatible with the inner wall 121, and the 6061-type alloy is generally made of aluminum that can withstand de-icing temperatures.

[0010] This welding step deteriorates the mechanical properties of the inner wall 121. The thickness of the inner wall must be increased to obtain good mechanical strength, thus increasing the weight of the flange 102a. In fact, errors in the manufacturing process of the acoustic device 104 and the flange 102a make the assembly more complex. In addition, during the cooling period after welding, the inner wall 121 is prone to deformation. Moreover, during welding, the flange 102a should be placed in a welding furnace, and the outer wall 122 may crack during the heating process. Additionally, specific and complex tools are required to fix the acoustic device 104 and the flange 102a to each other during welding. Finally, since it is necessary to accurately align with the honeycomb cells in the acoustic material 140 to ensure optimal acoustic treatment, it is complex to process acoustic holes in the inner wall 121.

[0011] One of the objects of the present invention is to assist in the manufacture of an intake pipe flange including an annular acoustic device while reducing the manufacturing cost.

[0012] Refer again to Figure 2 , as is known, an anti-icing device is assembled for the flange 102a to avoid ice accumulation on the inner wall 121. For this purpose, a hot air flow injector 103 is provided in the annular cavity 120, and injection ports 130 are formed in the inner wall 121, preferably upstream of the acoustic device 104, to heat the inner wall 121. Processing such injection ports 130 takes a long time and is complex to implement.

[0013] Another object of the present invention is to assist in the manufacture of an intake pipe flange including such injection ports.

[0014] Incidentally, in the patent application FR2924409, an aircraft nacelle includes an intake pipe and a downstream body. The intake pipe includes an acoustic device, and the downstream body includes another acoustic device. The patent application FR2924409 only solves the assembly problem of the downstream body of the nacelle, but does not propose any solution for manufacturing the intake pipe.

[0015] US2012048389A1 and US2012241249A1 provide an air intake duct that includes a noise attenuation member disposed downstream of the air intake duct lip, i.e., outside the annular cavity. US2002139899A1 provides an air intake duct lip without a jet orifice. Summary of the Invention

[0016] The present invention relates to an air intake duct lip of an aircraft turbofan engine nacelle, the nacelle extending along an axis X, wherein the air flow flows from upstream to downstream, the lip extending circumferentially around the axis X and including an inner wall facing the axis X and an outer wall opposite to the inner wall, the inner wall and the outer wall being connected by an upstream wall, and the lip including an annular acoustic device installed in the annular cavity.

[0017] The remarkable feature of the present invention is that the lip includes:

[0018] A first module, which includes an outer wall, an upstream wall, and a front wall constituting the upstream portion of the inner wall; and

[0019] A second module, which includes the acoustic device and a front housing constituting the downstream portion of the inner wall, the first module and the second module being fixedly connected to each other such that the front wall and the front housing together form the inner wall of the lip.

[0020] According to the present invention, the lip includes two inserted modules assembled together. Due to the small overall size and the fact that it can be manufactured by simpler and cheaper equipment, this modular design makes it easier to process and shape the modules. In addition, since the inspection can be carried out on both sides of the module, the module inspection is easier, so there are fewer defects. The modular assembly can use various assembly schemes without affecting the modules. In addition, the mechanical properties of the inner wall are not affected and it is no longer easily deformed. The outer wall is also not affected. Finally, when the second module fails, only the second acoustic module needs to be replaced.

[0021] Preferably, the front housing includes acoustic holes. Advantageously, this allows the internal air flow to pass through the acoustic device.

[0022] Preferably, the second module includes a rear housing, and the acoustic device is installed between the front housing and the rear housing. The acoustic device is thus clamped in the middle in the radial direction.

[0023] Preferably, the front wall of the first module is radially located inside the front housing of the second module at the junction between the front wall and the front housing. This advantageously allows a radial connection at the overlap.

[0024] According to one aspect, the lip includes at least one ejection orifice formed in the inner wall of the lip. Such an ejection orifice makes it possible to de-ice the inner wall of the lip.

[0025] Preferably, the ejection orifice is located upstream of the acoustic device so as to be able to de-ice the front housing during the flow of the internal air flow.

[0026] Preferably, the lip includes an ejection orifice formed at the junction between the front wall of the first module and the front housing of the second module. Such an ejection orifice advantageously avoids machining of the front wall, thereby improving the mechanical strength. During assembly, the ejection orifice is formed at the junction.

[0027] Even more preferably, the front wall of the first module and the front housing of the second module are radially spaced apart to form at least one ejection orifice therebetween. The ejection orifice is advantageously provided with a flow guide channel for precisely guiding the hot de-icing air flow.

[0028] Preferably, the lip includes a filler installed between the front wall of the first module and the front housing of the second module, that is, in the flow guide channel of the ejection orifice.

[0029] Preferably, the front wall of the first module and the front housing of the second module are radially spaced apart by at least one spacer post. Such a spacer post is used to define the radial thickness of the ejection orifice. Preferably, the spacer post has an aerodynamic shape to direct the air flow to the ejection orifice.

[0030] Preferably, the spacer post includes an opening for guiding a mechanical connecting member configured to fix the front wall of the first module and the front housing of the second module. Preferably, the spacer post has an aerodynamic profile so as to guide the de-icing air flow in an optimal manner. In particular, it prevents the occurrence of turbulence caused by the mechanical connecting member.

[0031] According to one aspect, the lip includes at least one inner partition wall installed in the annular cavity and located between the first module and the second module, preferably installed between the inner surface of the outer wall of the first module and the inner surface of the rear housing of the second module. The installation of the inner partition wall is relatively convenient.

[0032] According to one aspect, the annular cavity includes at least one hot air flow ejector so as to be able to de-ice by delivering hot air flow through the ejection orifice.

[0033] The present invention also relates to an aircraft air intake pipe including the lip as described above. Preferably, the air intake pipe includes an upstream portion formed by the lip and a downstream portion for installing the lip.

[0034] The invention also relates to an aircraft turbojet engine including a nacelle, said nacelle including an air intake pipe as described above.

[0035] The invention also relates to a method for manufacturing a lip of an air intake pipe as described above, the method comprising: manufacturing the first module and the second module independently, and fixing the first module and the second module together so that the front wall and the front housing jointly form the inner wall of the lip. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for the description of the embodiments. By reading the following description given only as an example and referring to the drawings given as non-limiting examples, the present invention will be better understood. In the drawings, the same reference numerals are used to indicate similar objects, wherein:

[0037] Figure 1 is a longitudinal sectional view of a prior art turbojet engine including a nacelle air intake pipe;

[0038] Figure 2 is a longitudinal sectional view of a prior art air intake pipe including an acoustic device;

[0039] Figure 3 is a longitudinal sectional view of the steps of manufacturing a prior art air intake pipe;

[0040] Figure 4 is a longitudinal sectional view of a lip of the present invention including a first main module and a second acoustic module assembled together;

[0041] Figure 5 is a schematic view of the second acoustic module of the lip of the present invention;

[0042] Figure 6 is a perspective view of a lip of the present invention having an inner partition wall;

[0043] Figure 7A and 7B are respectively a longitudinal sectional view and a partial perspective view of a first embodiment of a lip assembly of the present invention including a jet orifice;

[0044] Figure 8A and 8B are respectively a longitudinal perspective view and a partial perspective view of a second embodiment of a lip assembly of the present invention including a jet orifice;

[0045] Figure 8C is a longitudinal sectional view of the downstream end of the first main module of an embodiment of the present invention;

[0046] Figure 9 is a longitudinal sectional view of a third embodiment of a lip assembly of the present invention including a jet orifice;

[0047] Figure 10 is a perspective view of the lip assembly of the present invention including a jet nozzle and a filler;

[0048] Figure 11A and 11B are partial perspective views of the lip assembly of the present invention including a jet nozzle and a corrugated spacer post, respectively.

[0049] It should be noted that these drawings illustrate the present invention in detail for implementing the present invention, and of course the drawings can clearly define the present invention better when appropriate. Detailed Description of the Invention

[0050] Referring to Figure 4 , which shows the intake duct 2 of the nacelle of an aircraft turbojet engine according to an embodiment of the present invention, and particularly shows the nacelle of the turbojet engine. The turbojet engine extends along the axis X and enables the air flow to flow from upstream to downstream during propulsion. Hereinafter, the axis X extends from upstream to downstream. Referring to Figure 6 , the intake duct 2 includes an upstream portion 2a, referred to by those skilled in the art as the lip 2a, and a downstream portion 2b. In this embodiment, the lip 2a is separated from the downstream portion 2b by an inner partition wall 25.

[0051] The lip 2a extends circumferentially around the axis X and includes an inner wall 21 facing the axis X and an outer wall 22 opposite to the inner wall 21. The inner wall 21 and the outer wall 22 are connected by an upstream wall 23 to define an annular cavity 20. Thus, the lip 2a enables the incoming air flow to be separated into an internal air flow guided by the inner wall 21 and an external air flow guided by the outer wall 22. Hereinafter, the terms "internal" and "external" are defined radially with respect to the axis X of the turbojet engine. The lip 2a includes an annular acoustic device 50 installed in the annular cavity 20.

[0052] According to the present invention, the lip 2a includes a first module M1, which includes the outer wall 22, the upstream wall 23, and a front wall 24 constituting the upstream portion of the inner wall 21. The lip 2a further includes a second module M2, which includes the acoustic device 50 and a front housing 51 constituting the downstream portion of the inner wall 21. The first module M1 and the second module M2 are fixedly connected to each other so that the front wall 24 and the front housing 51 together form the inner wall 21 of the lip 2a. Preferably, the inner wall 21 has an aerodynamic shape to optimally guide the air flow in the secondary flow of the turbojet engine.

[0053] In other words, contrary to manufacturing the inner wall 21 integrally in the prior art, the present invention describes a modularly assembled inner wall 21, which includes a front wall 24 forming an upstream portion and a front housing 51 forming a downstream portion, and the front wall 24 and the front housing 51 are fixed during the assembly process. As will be elaborated later, this modular design enables the second acoustic module M2 to be manufactured independently, thereby facilitating its manufacturing and reducing damage during the assembly process.

[0054] As Figure 4 shown, the first module M1, also referred to as the main module M1, has a structure similar to that in the prior art, except that the first module M1 does not have a long inner wall, but only has a shortened inner wall called the front wall 24. Preferably, the main module M1 is made of a metal material, preferably a heat-resistant metal material such as aluminum. Several embodiments of the main module M1 will be elaborated below. The first module M1 is preferably integrally formed.

[0055] In this embodiment, the first module M1 is manufactured by forming (explosively or otherwise) or by spin forming.

[0056] As Figure 4 shown, the second module M2, also referred to as the acoustic module M2, has an acoustic device 50, which has a honeycomb structure in this embodiment. The acoustic device 50 includes a plurality of acoustic units, preferably metal honeycomb units. However, it goes without saying that the acoustic device 50 can take other forms.

[0057] Referring Figure 4 and Figure 5 , the second module M2 includes a front housing 51 and a rear housing 52, and the acoustic device 50 is installed between the front housing 51 and the rear housing 52. The front housing 51 of the second acoustic module M2 is configured to form an extension of the front wall 24 of the first module M1. The front housing 51 is preferably made of a metal material, especially aluminum.

[0058] The front housing 51 is provided with a plurality of holes to enable the acoustic device 50 to communicate with the air flow flowing within the lip 2a. These holes can be manufactured before or after assembling the second module M2. Similarly, these holes can be manufactured before or after assembling the first module M1 and the second module M2.

[0059] The rear housing 52 defines a recess for accommodating the acoustic device 50. The rear housing 52 is preferably made of a metal material, especially aluminum. The acoustic device 50 is preferably fixed to the rear housing 52 by welding.

[0060] As Figure 5As shown, in the longitudinal cross-sectional view, the rear housing 52 includes a central recess 52b and two end portions 52a fixed to the front housing 51. Since it is installed independently of the first module M1, this fixing method is easy to implement. Preferably, the rear housing 52 is fixedly connected to the front housing 51 by welding, soldering, etc. or by mechanical assembly, etc. Advantageously, the overall size of the second module M2 is reduced, which helps with its welding and assembly in the oven. In addition, when manufacturing the second module M2, the mechanical properties of the first module M1 are advantageously not affected.

[0061] Preferably, the end portion 51a of the front housing 51 is longer than the end portion of the rear housing 52 so that, as will be described below, it can be fixed to the first module M1.

[0062] After assembly, the second module M2 can be stored, processed, and used independently of the first module M1, which significantly simplifies the transportation and assembly of the flange 2a.

[0063] Advantageously, the first module M1 and the second module M2 can be prepared by different methods.

[0064] Advantageously, the first module M1 and the second module M2 are manufactured independently and then assembled together. Their assembly is preferably performed by mechanical means such as welding (laser, friction, electron beam, etc.).

[0065] Reference Figure 6 , according to one aspect of the present invention, the intake pipe 2 includes an inner partition wall 25 so as to form a closed annular cavity 20 dedicated to the flow of the de-icing air stream therein. In this embodiment, the inner partition wall 25 is installed between the outer wall 22 of the first module M1 and the rear housing 52 of the second module M2. Arranged in this way, on the one hand, the size of the acoustic device 50 can be maximized, and on the other hand, the inner partition wall 25 can be pre-installed on the first module M1 or the second module M2 to facilitate the installation of the inner partition wall 25, so this design is advantageous. However, it goes without saying that the acoustic device 50 can be independent of the inner partition wall 25 and spaced apart from the inner partition wall 25. Specifically, the inner partition wall 25 can be provided downstream of the acoustic device 50.

[0066] In this embodiment, the assembly of the inner partition wall 25 in the intake pipe 2 is described. Such an inner partition wall 25 is not necessary and can be omitted according to the structure of the intake pipe 2. In the following, for the sake of clarity and conciseness, the inner partition wall 25 will not be shown, but it is obvious that it can be provided.

[0067] As described above, the intake pipe 2 includes an upstream portion 2a and a downstream portion 2b. After being manufactured, the flange 2a can be mounted to the downstream portion 2b to form the intake pipe 2. Preferably, the downstream portion 2b includes an acoustic device. According to one aspect of the present invention, the acoustic device of the downstream portion 2b is an acoustic device 50 independent of the flange 2a. According to another aspect of the present invention, the acoustic device continuously extends between the downstream portion 2b and the flange 2a to provide optimal noise attenuation. The inner partition wall 25 located between the flange 2a and the downstream portion 2b of the intake pipe 2 is described above, but this is not necessary.

[0068] According to one aspect of the present invention, the annular cavity 20 includes at least one hot air flow ejector, particularly for de-icing the flange 2a. According to one aspect of the present invention, the flange 2a includes at least one ejection opening in the inner wall 21, preferably a plurality of ejection openings, to lead the hot air flow out of the annular cavity 20 for de-icing the inner wall 21.

[0069] Now reference will be made to Figures 7A to 11B describe several embodiments of the ejection opening.

[0070] As Figure 7A and 7B , according to the first embodiment, the first module M1 and the second module M2 are fixedly connected to each other at the junction thereof, wherein one end 51a of the front housing 51 of the second module M2 is fixedly connected to the front wall 24 of the first module M1. Preferably, at the junction, the front housing 51 is located radially inside the front wall 24 of the first module M1 so as to be fixedly connected in the radial direction by means such as welding or mechanical connection. In this embodiment, three connecting members L are shown in Figure 7B .

[0071] In order to form the flange 2a of the inner wall 21 having an aerodynamic curvature, the front housing 51 of the second module M2 is curved to form an end portion 51a and a central portion 51b. The end portion 51a is superimposed on the front wall 24 of the first module M1 to achieve fixation, and the central portion 51b serves as an extension of the front wall 24 of the first module M1, as shown in Figure 7A .

[0072] Preferably, as shown in Figure 7A , the downstream end 24a of the front wall 24 is a bevel surface to match the shape of the front housing 51 of the second module M2, and its radially outer surface is radially inclined inward from the upstream to the downstream direction. Such a bevel surface is simple to manufacture and avoids severe deformation of the front housing 51, thereby maintaining the aerodynamic profile. Thus, the bevel surface faces the bending direction of the front housing 51 to obtain a continuous inner wall 21.

[0073] As Figure 7A and 7BAs shown, the front wall 24 of the first module M1 includes a plurality of injection ports 31 formed at the downstream end away from the front wall 24. In this embodiment, the injection ports 31 extend radially on the front wall 24 approximately. For those skilled in the art, such independent injection ports 31 are the so-called "separation grooves". Refer to Figure 7B , in this embodiment, each injection port 31 adopts an azimuthally oriented groove. Of course, the shape and direction can be different.

[0074] The injection ports 31 are formed in the first module M1 independently of the second module M2. Refer to Figure 7A , the injection ports 31 are formed in the wall of the thicker part of the front wall 24, however, such a thick wall is not necessary.

[0075] According to the second embodiment, as Figure 8A and 8B shown, the first module M1 and the second module M2 are fixedly connected to each other at their junction, and at this junction, the end 51a of the front housing 51 of the second module M2 is fixedly connected to the front wall 24 of the first module M1. Preferably, at the junction, the front housing 51 is located radially inside the front wall 24 of the first module M1 so as to enable fixed connection along the radial direction.

[0076] In this second embodiment, the front wall 24 and the front housing 51 are radially spaced apart by a plurality of spacer posts 6 or wedges installed between the front wall 24 and the front housing 51. Preferably, at least one spacer post 6 includes a radial channel opening for guiding a mechanical connecting member L, such as a rivet. Thus, when the first module M1 and the second module M2 are assembled together, the front wall 24 is spaced apart from the front housing 51 so as to form an air injection port 32 including a preferably annular diversion channel therebetween. Preferably, the radial thickness of the spacer post 6 is between 1 mm and 8 mm to form a diversion channel with a set thickness. Preferably, this radial thickness depends on the required de-icing conditions (temperature, pressure, etc.).

[0077] Advantageously, different from the first embodiment, it is not necessary to open holes in the front wall 24 of the first module M1. In this embodiment, the injection port 32 is formed at the junction during the assembly process. Thus, the mechanical stress in the front wall 24 of the first module M1 is reduced. Such a biased injection port 32 is the so-called "step groove" for those skilled in the art. In this embodiment, the injection port 32 is circumferential.

[0078] Refer to Figure 8A , due to the gap between the front wall 24 and the front housing 51, the inner wall 21 of the lip 2a is discontinuous radially. Optionally, refer to Figure 8C, the downstream end 24a of the front wall 24 is an inclined surface, and its radially inner surface is inclined radially outward in the direction from upstream to downstream. Such an inclined surface is simple to manufacture and significantly reduces the aerodynamic discontinuity at the junction between the front wall 24 and the front housing 51. As Figure 8C shown, when the inclined angle θ is less than 15°, good performance can be achieved. Preferably, the radially inner surface is a curved surface to form an aerodynamic profile.

[0079] According to the third embodiment, as Figure 9 shown, the front housing 51 of the second module M2 is curved to form an end portion 51a and a central portion 51b. The end portion 51a faces the front wall 24 of the first module M1 for fixation, and the central portion 51b serves as an extension of the front wall 24 of the first module M1.

[0080] In this embodiment, the front wall 24 and the front housing 51 have substantially the same shape as in the first embodiment and are radially spaced apart in a manner similar to the second embodiment, specifically by spacer posts 6 ( Figure 9 not shown in the figure) and in the form of an annular groove.

[0081] Advantageously, during the assembly process, the ejection orifice 33 is formed at the junction. The ejection orifice 33 includes a flow guiding channel that extends longitudinally between the front wall 24 and the front housing 51 to guide the hot air flow. The ejection orifice 33 opens at the junction of the front wall 24 and the front housing 51 that are aligned with each other. Such an embedded ejection orifice 33 is what is called a "buried groove" for those skilled in the art. In this embodiment, the ejection orifice 33 is circumferential.

[0082] According to an alternative of the present invention, referring to Figure 10 , when the ejection orifices 32, 33 include flow guiding channels formed between the front wall 24 and the front housing 51, a filling member 7 can be advantageously provided in the flow guiding channel so that the hot air flow acts on the hot air flow before being discharged.

[0083] Preferably, the filling member 7 can include main channels to separate the hot air flow into multiple main air flows to facilitate the guiding of the air flow and achieve optimal de-icing. As an example, the filling member 7 includes a corrugated plate sandwiched between two circumferential plates. Further preferably, the filling member 7 is made of a metallic material.

[0084] According to an alternative of the present invention, referring to Figure 11A and Figure 11B shown, the lip 2a includes spacer posts 6' having an aerodynamic profile to define a leading edge facing upstream and a trailing edge facing downstream. Preferably, as Figure 11A and 11B shown, the spacer posts 6' are in a water droplet shape, and its cross-section first increases and then decreases from upstream to downstream. However, it goes without saying that each spacer post can have a different shape.

[0085] Spacer columns 6, 6' (with or without an aerodynamic profile) can be installed in the form of inserts between the front wall 24 and the front housing 51, but can also be made of the material of the front wall 24 or the front housing 51. Preferably, the spacer columns 6, 6' are made of the material of the front wall 24 and are formed during the manufacture of the first module M1.

[0086] With the present invention, due to the limited overall dimensions, the modular design enables easier fixing and machining of the first module M1 and the second module M2, and can be achieved by simpler and cheaper equipment. In addition, since the first module M1 and the second module M2 are inspectable on each face, there are fewer defects and it helps with their maintenance. Moreover, the modular assembly can be carried out in various schemes without affecting the performance of the first module M1 and the second module M2.

[0087] Specifically, with the present invention, the mechanical properties of the inner wall 21 are maintained and it is no longer easily deformed. Since it is no longer necessary to introduce it into a welding furnace, the outer wall 22 is also maintained. Finally, in case of damage, only the second acoustic module M2 needs to be simply replaced.

Claims

1. The lip (2a) of an air intake duct (2) of an aircraft turbofan nacelle, the nacelle extending along an axis X, the air flow flowing in the nacelle from upstream to downstream, the lip (2a) extending circumferentially around the axis X and comprising an inner wall (21) facing the axis X and an outer wall (22) opposite the inner wall (21), the inner wall (21) and the outer wall (22) being connected by an upstream wall (23) to define an annular cavity (20), the lip (2a) comprising an annular acoustic device (50) mounted in the annular cavity (20), characterized in that, The lip edge (2a) includes: - A first module (M1) that includes the outer wall (22), the upstream wall (23), and a front wall (24) that forms the upstream portion of the inner wall (21); and - A second module (M2) that includes the acoustic device (50) and a front housing (51) that forms the downstream portion of the inner wall (21). The first module (M1) and the second module (M2) are fixedly connected to each other such that the front wall (24) and the front housing (51) together form the inner wall (21) of the lip edge (2a). The front wall (24) of the first module (M1) and the front housing (51) of the second module (M2) are radially spaced apart by at least one spacer post (6, 6') to form at least one injection port (32, 33) between the front wall and the front housing; the front wall (24) and the front housing (51) face each other, and the spacer posts (6, 6') are located in the region where the front wall (24) and the front housing (51) face each other; The front wall (24) of the first module (M1) is radially located inside the front housing (51) of the second module (M2) at the junction of the front wall (24) and the front housing (51); The spacer posts (6, 6’) are provided with openings for guiding a mechanical connecting member (L), and the mechanical connecting member (L) is configured to fixedly connect the front wall (24) of the first module (M1) and the front housing (51) of the second module (M2); The second module (M2) includes a rear housing (52), and the acoustic device (50) is installed between the front housing (51) and the rear housing (52).

2. The lip (2a) of the intake pipe (2) according to claim 1, characterized in that The spacer post (6’) has an aerodynamic shape to guide the air flow to the injection port (33).

3. A method for manufacturing a lip (2a) of an intake pipe (2) as claimed in any one of claims 1 to 2, characterized in that, Including: Independently manufacturing the first module (M1) and the second module (M2), and fixedly connecting the first module (M1) and the second module (M2) such that the front wall (24) and the front housing (51) together form the inner wall (21) of the lip edge (2a).

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