GONDOLA AIR INTAKE AND GONDOLA WITH SUCH AN AIR INTAKE

Description

[0001] The present invention relates to an aircraft propulsion assembly comprising a nacelle and an engine such as a turbojet, and relates in particular to an air intake of such a nacelle.

[0002] An aircraft is powered by one or more turbojet engines, each housed in at least one nacelle. The nacelle generally has a tubular structure comprising an air intake section upstream of the turbojet engine, a middle section intended to surround a fan of the turbojet engine, and a downstream section housing the thrust reverser means.

[0003] The downstream section of the nacelle surrounds the turbojet engine's gas generator which terminates in an exhaust nozzle located downstream of the turbojet engine.

[0004] The air inlet section of the nacelle includes in particular a generally annular front lip which intercepts the nacelle inlet air flow which is directed towards a fan.

[0005] To do this, the remainder of the air intake structure has a substantially annular structure comprising an external panel or wall ensuring the external aerodynamic continuity of the nacelle and an internal panel or wall ensuring the internal aerodynamic continuity of the nacelle, in particular with the fan casing at the level of the middle section. The air intake lip ensures the junction between these two walls by forming a leading edge of the nacelle and can in particular be integrated into the external and / or internal panel, thus forming a main wall of the air intake.

[0006] Generally, the front lip consists of a single annular-shaped part which is directly fixed to support partitions inside the nacelle. Also noted is the use of an upstream partition which forms an annular volume behind the front lip in the shape of a "D".

[0007] More specifically, the nacelle inlet section generally includes: an internal wall, preferably provided with a substantially cylindrical internal acoustic part having an upstream edge and a downstream edge, this part forming at least part of an acoustic shroud of the air inlet being called an "inner barrel" in English jargon; a substantially cylindrical external wall; a front lip connecting the internal and external walls by forming a leading edge; a downstream mounting flange configured for mounting the inlet section to a front flange of a wall of the turbojet; and a rear partition having a downstream end for securing the external part of the external wall to the downstream mounting flange.

[0008] An air inlet for an aircraft engine nacelle is known from document FR 2 856 379 A1. Other air inlets are known from documents FR 2 998 548 A1, FR 2 966 126 A1, FR 3 016 159 A1 and US 2008 / 0016844 A1.

[0009] Furthermore, the air intake generally includes a de-icing system. A known type of de-icing or anti-icing system, presented in particular by documents EP 0 913 326 B1 or US 2002 / 0179773 A1, comprises a circular tube going around the nacelle, which supplies hot air taken from the turbojet engine to the interior volume of the front lip of this nacelle in order to heat its walls.

[0010] The lengthening of the nacelle's front lip is sought in particular for aerodynamic reasons, in order to extend the laminar airflow zone downstream. However, its lengthening is not without repercussions on the design of the rest of the nacelle. In particular, the nacelle must have mechanical rigidity performance in order to reduce its deformations during operating stresses.

[0011] As a result, the part that forms the front lip that limits the entry of fresh air into the nacelle has a complex and large cross-sectional shape.

[0012] To solve these problems, the concept of a so-called "extended" lip was developed, comprising an external wall extending well downstream from the internal wall and covering part of the fan casing externally, the external wall and the lip forming an integral part, i.e. a single piece.

[0013] Such an arrangement described in the prior art allows for savings in material mass and part complexity compared to the older prior art in which the outer casing and the front lip of the nacelle inlet section are made of separate parts.

[0014] However, for these arrangements to be advantageous, they require the addition of annular reinforcements, arranged inside the external envelope. The single part thus formed, moreover, is of a large dimension and a significant volume. Its production requires a complex and expensive tool.

[0015] However, the solution of an integral lip with the external wall of the nacelle inlet section also faces problems of adaptation to other requirements.

[0016] Among these, we will notably mention the problem of maintenance. Indeed, in order to inspect the various systems such as defrosting or to inspect the condition of the structure, it is necessary to provide the possibility of accessing the space between the front (or upstream) and rear (or downstream) bulkheads, which is then inaccessible if the part forming the lip and the external wall are in one piece.

[0017] The present invention provides a remedy to these drawbacks and in particular proposes a solution presenting the advantages in terms of aerodynamics of a so-called extended lip while ensuring improved maintenance.

[0018] To this end, the present invention relates to an air intake for an aircraft engine nacelle, the air intake comprising a front lip connecting a substantially cylindrical inner wall and a substantially cylindrical outer wall, a front mounting flange configured to cooperate with a rear flange of a wall of the turbojet, the air intake having a support structure extending from a lower end configured to be secured to a fan casing, at the rear flange, to an upper end in contact at least with a downstream portion of the outer wall of the air intake, said support structure comprising access windows configured to be traversed by maintenance tools during maintenance operations of the air intake.

[0019] By such a combination of features, the force path is improved between the air inlet and the nacelle, in particular with the rear flange of the turbojet wall of the fan casing at which the support structure is configured to be secured.

[0020] With reference to the support structure, the expression "secured" will be understood to mean that the support structure is configured to be secured to the wall of the turbojet engine forming the fan casing so that a force-recovery path, in the assembled position, passes from the external wall to the fan casing, without passing through the internal wall.

[0021] Preferably, the support structure is directly attached to the rear flange of the turbojet wall forming the fan casing.

[0022] Furthermore, accessibility to the air intake mountings on the fan casing is maintained thanks to the access windows which facilitate maintenance, particularly after removal and opening of the external fan covers.

[0023] According to a particular technical characteristic, the air inlet lip can be integrated into the internal and / or external wall.

[0024] More preferably, the air inlet lip may be integrated into the inner and / or outer wall so as to form a single wall together.

[0025] In other words, the air inlet lip, the inner wall and the outer wall are formed from a single piece.

[0026] According to the invention, the lower end of the support structure is configured to be secured to a rear face of the rear flange. This further contributes to improving the force path and reinforcing the structure.

[0027] Preferably, the lower end of the support structure is directly attached to the rear face of the rear flange.

[0028] Advantageously, the front mounting flange and the rear flange are secured together by fastening means, the support structure being secured to the rear flange with all or part of these same fastening means.

[0029] Such a feature makes it possible to avoid the multiplication of fixing means and therefore to gain in mass and simplicity of design.

[0030] Alternatively, these means of attachment may be separate, at least in part or even entirely.

[0031] According to a particular technical characteristic, the support structure is arranged substantially continuously around the wall of the turbojet engine of the fan casing, and comprises, for example, a partition.

[0032] Alternatively or in addition, the support structure is arranged discontinuously around the wall of the turbojet engine of the fan casing, and comprises for example a set of support rods. In this case, a space between two rods can delimit an access window for maintenance.

[0033] Advantageously, the portion of the outer wall of the air inlet which is at least in contact with the upper end of the support structure, preferably at a support surface of said support structure, comprises a downstream end of the outer wall.

[0034] According to another feature, in addition to being in contact with a support surface of the support structure, the external wall is supported against it and fixed to it by fixing means. This ensures better holding of the parts taking into account the stresses undergone by the air inlet.

[0035] Preferably, the downstream end of the outer wall is configured to support a front end of the outer fan cowl, in the assembled position, this support preferably being completed by fixing means.

[0036] In such a configuration, the junction of the downstream end of the external wall with the support structure is located under the support zone of the external fan cowl on the external wall of the air inlet.

[0037] In this case, the downstream end of the external wall has a step dimensioned according to the radial thickness of said external fan cowl so that the two walls successively forming the external aerodynamic line of the nacelle are continuous and flush.

[0038] Because the junction is located under the support area of ​​the outer fan cowl, this means that the quality of the lines and the cosmetic appearance (paint) are not affected by visible fixings. As a result, the possible fixing means can be larger and fewer in number.

[0039] According to another aspect, the invention relates to a nacelle comprising an air inlet comprising all or part of the aforementioned characteristics.

[0040] Other characteristics and advantages of the invention will emerge from reading the following description, given solely by way of example, with reference to the appended figures. There figure 1 is a partial schematic section of one embodiment of a nacelle. The figure 2 is a schematic sectional view of an air inlet according to one embodiment. The figures 3, 4 And 5 are sectional views of an air inlet according to one embodiment. The figures 6A et 6B are seen in section of an air inlet according to two other embodiments. The figure 7 is a view of an access window crossed by a maintenance tool during an air inlet maintenance operation according to one embodiment. figures 8 , 9 , 10 , 11 are perspective views of a support structure according to different fixing variants with the external wall of the air inlet and the external fan cowl.

[0041] Throughout these figures, identical or similar references designate identical or similar organs or sets of organs.

[0042] The terms "upstream" and "front" will be used interchangeably to designate the upstream of the air inlet and the terms "downstream" and "rear" will be used interchangeably to designate the downstream of the air inlet.

[0043] As shown in the figure 1 , a nacelle 1 according to the invention has a substantially tubular shape along a longitudinal axis Δ (direction parallel to X).

[0044] The nacelle 1 comprises an upstream section 2 with an air inlet lip 3, a middle section 4 surrounding a fan 5 of an engine 6 such as a dual-flow turbojet and a downstream section 7 housing a thrust reversal system (not visible), the nacelle serving to channel the air flows generated by the engine 6.

[0045] The air inlet 3 is divided into two parts, namely on the one hand, an inlet lip 31 adapted to allow optimal capture towards the turbojet of the air necessary to supply the fan and the internal compressors of the turbojet, and on the other hand, a downstream structure 32, 33 on which the lip is attached and intended to properly channel the air towards the blades of the fan. The assembly is attached upstream of a casing of the fan belonging to the middle section 4 of the nacelle 1.

[0046] The downstream section 7 comprises an internal structure 8 (also called “inner fixed structure” or “IFS”) surrounding the upstream part of the turbojet 6, an external structure (also called “outer fan structure” or “OFS”) 9 forming the cold flow channel and fixed relative to the engine, and a movable cowl comprising thrust reversal means.

[0047] The IFS 8 and the OFS 9 delimit a vein 10 allowing the passage of an air flow 12 penetrating the nacelle 1 at the level of the air inlet lip 3.

[0048] The nacelle 1 comprises a top 14 intended to receive an attachment engine mast making it possible to fix said nacelle 1 to a wing of the aircraft. To do this, said top 14 comprises means for fixing said engine mast.

[0049] The turbojet nacelle is in particular suspended from the engine mast, by means of a beam at the level of this summit 14.

[0050] Nacelle 1 ends with an ejection nozzle 21.

[0051] As more specifically represented on the figures 2 à 4 , the air inlet 3 comprises a front lip 31 forming a leading edge of the nacelle, said lip 31 connecting a substantially cylindrical internal wall 32 and a substantially cylindrical external wall 33.

[0052] In other words, the air inlet 3 has a substantially annular structure comprising the external wall 33 ensuring the external aerodynamic continuity of the nacelle, and the internal wall 32 ensuring the internal aerodynamic continuity of the nacelle, in particular with the fan casing at the level of the middle section 4.

[0053] The nacelle comprises an outer casing and an inner casing, said outer casing comprising fan cowls flush with the outer wall 33 ensuring external aerodynamic continuity and said inner casing comprising a fan casing flush with the inner wall 32 ensuring internal aerodynamic continuity of the nacelle 1.

[0054] The air inlet lip 31 provides the junction between these two walls 32, 33 and can in particular be integrated into the internal and / or external wall, thus forming a main wall of the air inlet 3 formed from a single piece.

[0055] The inner envelope of the nacelle 1 comprises an upstream part (on the side of the air inlet section 3 of the nacelle 1) having in particular an acoustic shroud and a downstream part (on the side of the thrust reverser) comprising the casing 42 of the fan 5. The two upstream and downstream parts are connected by attachment flanges.

[0056] More precisely, the air inlet 3 comprises at its internal wall 32 a front mounting flange 34 configured to cooperate with a rear flange 44 secured to a wall of the turbojet at its upstream end, in particular the casing 42 of the fan 5 also called the engine casing and at its upstream end.

[0057] This assembly of the flanges 34 and 44 ensures the fixing of the air inlet 3 with the middle section 4. This assembly is completed and secured by fixing means 45, for example of the screw-nut type.

[0058] The external wall 33 has a downstream end 33' configured to be positioned in a junction zone flush with a front end 43' of the external fan cowl 43 so as to ensure the external aerodynamic continuity of the nacelle.

[0059] To maintain a certain rigidity in the structure, this external wall 33 comes to bear against a support surface 51 of a support structure 50. Preferably, this support is completed by fixing means 35 for fixing the support structure 50 to said external wall of the air inlet 3. These fixing means 35 may be, for example, screw-nut assemblies.

[0060] This support structure 50 extends substantially radially in the thickness of the nacelle 1 and is configured to be secured to the fan casing 42, and more particularly secured to the rear flange 44, on a rear face thereof, that is to say opposite a front face configured to cooperate and / or be joined with a rear face of the front mounting flange 34. This contributes to improving the force path.

[0061] In other words, the support structure 50 extends from a lower end configured to be integral with the middle section 4, and more particularly with the fan casing 42, at the level of the rear flange 44, to an upper end in contact at least with a downstream part of the external wall 33 of the air inlet 3.

[0062] The support structure 50 is attached to the rear flange 44 with all or part of the same attachment means 45 of the front mounting flange 34 and the rear flange 44,

[0063] The support structure 50 being integral with the rear flange 44, on a rear face thereof, the fixing means 45 such as screw-nut assemblies pass successively from upstream to downstream, respectively: the front mounting flange 34, the rear flange 44 then the lower end of the support structure 50.

[0064] According to the invention, the support structure 50 comprises access windows 70 configured to be passed through by maintenance tools 80 during maintenance operations on the air inlet 3.

[0065] As illustrated on the figure 4 , in this embodiment, the support structure 50 is formed by a plurality of support rods or uprights 52. The space formed between each of the support rods forms an access window 70. In this case the access windows are delimited laterally by the two adjacent uprights 52 on the one hand and radially by the rear flange 44 and the external wall 33.

[0066] The support rods 52 are distributed over the entire circumference of the nacelle 1 in a relatively homogeneous manner, in particular around the rear flange 44, and are spaced apart from each other by a predetermined distance sufficient to guarantee the structural integrity of the air inlet of the nacelle 1.

[0067] In this embodiment (see the figures 3 à 5 ), the downstream end 33' of the external wall 33 is located longitudinally upstream of the front mounting flange 34. Due to this configuration, the support structure 52 has an inclination such that its orientation generally deviates forward from the longitudinal axis of the nacelle at the same time as it moves away from the longitudinal axis.

[0068] In particular the figures 3 And 5 also represent air inlets 3 according to embodiments illustrated here without the partition 50 to illustrate the offset of the downstream end 33' of the external wall 33 longitudinally upstream of the front mounting flange 34.

[0069] On the figure 3 further illustrated are equipment of the air inlet 3 such as a power supply for a defrosting system of the air inlet secured to the front partition 50' and an engine probe passing through the acoustic attenuation structure 60 equipping the internal wall 32.

[0070] According to other embodiments, the downstream end 33' of the external wall 33 may be located longitudinally substantially at the level of the front mounting flange 34 (see figure 6A ), or be located longitudinally substantially downstream of the front mounting flange 34 (see the figure 6B ).

[0071] The term "downstream of the front mounting flange" means downstream of the upstream end of the flange, i.e. downstream of a joining plane between the two flanges in the assembled position.

[0072] In order to reduce the noise pollution generated by the turbojet, at least the internal wall 32 of the air intake 3 is equipped with an acoustic attenuation structure 60, which is located in the space delimited by the main wall, namely the internal wall 32, the external wall 33 and the front lip 31.

[0073] This acoustic attenuation structure 60 is in the form of a panel with a honeycomb core forming a honeycomb structure whose cells delimit acoustic cells, the acoustic structure further comprising a solid internal skin ensuring in particular the mechanical strength of the panel.

[0074] This acoustic structure 60 is preferably formed from composite materials. Where the temperatures involved allow, other materials may be used. These materials may also depend on the manufacturing process used, for example by thermoplastic molding, by additive manufacturing in aluminum, etc.

[0075] The middle section also includes such an acoustic structure equipping in particular at least in part the casing 42 of the fan 5.

[0076] The mounting flanges 34 and rear 44 are integral with these respective acoustic structures 60.

[0077] There figure 7 illustrates a detailed view of a support structure 50 according to one embodiment during a maintenance operation of the air inlet 3.

[0078] In the operation of removing or replacing the air inlet 3 of the fan casing 42, two solutions are possible depending on the configurations of the rear support of the external wall 33.

[0079] In the case where the support of the air inlet 3 by the support structure 50 is discontinuous around the wall of the turbojet engine of the fan casing (as illustrated in particular on the figure 4 ), during a maintenance operation, it is sufficient to detach the external wall 33 from the support structure 50, for example by first removing the fan cowls (if they are fixed) or opening them (if they are mobile and / or articulated), then said external wall 33 is detached from the support structure 50. The support structure 50 remains fixed to the fan casing during the removal of the air intake. Said support structure 50 is arranged to form, by its material configuration, access windows 70 configured to be sufficiently small to guarantee the structural integrity of the nacelle and sufficiently large to be passed through by maintenance tools 80 during maintenance operations on the air intake 3. It is then easy to access both the front mounting flange 34 and the rear flange 44.

[0080] Such a support structure 50 supporting the external wall 33 of the air inlet 3 and configured discontinuously around the wall of the turbojet engine of the fan casing is generally dedicated to a non-fire environment, that is to say that there is no need for this type of nacelle to locally protect this geography of the nacelle from a risk of fire.

[0081] In the case of the embodiment illustrated in the figure 7 , the support structure 50 comprises a partition which, generally, is continuous around the wall of the turbojet engine of the fan casing. In particular, it makes it possible to guarantee a thermal seal compatible with fire protection in order to guarantee the protection of any equipment which would be housed in this space. In other words, when the support structure 50 comprises a partition, said partition can be segmented, but is preferably solid, that is to say continuous, when it provides a fire-carrying function.

[0082] In the same way, during a maintenance operation, it is sufficient to separate the external wall 33 from the support structure 50 and to keep this support structure 50 fixed on the fan casing 42 when removing the air inlet 3.

[0083] Said support structure 50 being continuous, it is configured to have access windows 70 configured to be large enough to be passed through by maintenance tools 80 during maintenance operations of the air inlet 3. In this embodiment, an access window 70 is delimited by edges of the partition 50 on the one hand and by the rear flange 44 on the other hand.

[0084] A closing partition or hatch 54 is also provided to close the access windows 70 during use of the nacelle in order to guarantee the continuity of thermal protection, if this is necessary.

[0085] It is then easy to access both the front mounting flange 34 and the rear mounting flange 44, as illustrated in this figure 7 to allow their dismantling.

[0086] When the support structure 50 comprises a partition, said partition may be segmented. It is preferably solid when it provides a fire-carrying function.

[0087] Such a support structure 50 of the downstream edge 33' of the external wall 33 of the air inlet directly connected to the fan casing 42, and not to the internal wall 32 is particularly advantageous in terms of force absorption. This concept also allows easy access for maintainability needs to the flanges 34, 44 and the equipment present in the air inlet such as for example the defrosting tube.

[0088] THE figures 8 , 9 , 10 And 11 illustrate perspective views of a support structure 50 according to different attachment variants with the external wall 33 of the air inlet 3 and the external fan cowl 43.

[0089] It is visible on the figure 8 , the downstream end 33' of the outer wall 33 is configured to support the front end 43' of the outer fan cowl 43 and be fixed thereto, in the assembled position.

[0090] This external wall 33 comes to bear against the support surface 51 of the support structure 50. This support is also completed by fixing means for fixing the support structure 50 to said external wall 33 of the air inlet 3. These fixing means 35 can be, for example, screw-nut assemblies.

[0091] Furthermore, the downstream end 33' of the external wall 33 has a step dimensioned according to the radial thickness of said external fan cowl 43 so that the two walls 33, 43 successively forming the external aerodynamic line of the nacelle are continuous and flush.

[0092] In such a configuration, the junction of the downstream end 33' of the external wall 33 with the support structure 50 is located under the support zone of the outer fan cowl 43 on the external wall 33 of the air inlet 3. This makes it possible not to impact the quality of the lines and the cosmetic appearance by visible fixings. As a result, the possible fixing means can be larger and fewer in number.

[0093] In the configuration illustrated on the figure 9 , the front end 43' of the outer fan cowl 43 is in direct contact and fixed together with the downstream end 33' of the outer wall 33.

[0094] According to another variant, the respective ends 33', 43' of the external walls 33 and of the outer fan cowl 43 can be abutted and supported directly on the support surface 51 of the support structure 50 (see for example the figures 10 And 11 ).

[0095] In this case, the fixing means 35 allow the fixing of the downstream end 33' of the external wall 33 with the support structure 50 and the front end 43' of the external fan cowl 43 can simply be supported (see figure 10 ) or similarly secured with the support structure 50 ( figure 11 ).

[0096] It will be noted that the respective ends 33', 43' of the external walls 33 and of the external fan cowl 43 can also rest on an intermediate piece or are fixed by means of this intermediate piece which rests on the support surface 51 of the support structure 50.

[0097] The invention is described in the foregoing by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention without departing from the scope of the invention.

Claims

1. An air intake (3) for a nacelle (1) of an aircraft engine (6), the air intake (3) including a front lip (31) connecting a substantially cylindrical inner wall (32) and a substantially cylindrical outer wall (33), a front mounting flange (34) configured to cooperate with a rear flange (44) of a wall of the turbojet engine forming a fan casing (42), the air intake having a support structure (50) extending from a lower end configured to be secured to the fan casing (42), by the rear flange (44), up to an upper end in contact at least with a downstream portion of the outer wall (33) of the air intake (3), said support structure (50) including or forming access apertures (70) configured to be crossed by maintenance tools during the operations of maintenance of the air intake (3), characterized in that the lower end of the support structure (50) is configured to be secured to a rear face (441) of the rear flange (44).

2. The air intake (3) according to claim 1, characterized in that the air intake lip (31) may be integrated to the inner (32) and / or outer (33) wall so as to form a wall in one-piece.

3. The air intake (3) according to claim 1 or 2, characterized in that the support structure (50) is disposed continuously around the wall of the turbojet engine forming the fan casing, and comprises for example a partition, and / or discontinuously around the wall of the turbojet engine of the fan casing, and comprises for example a set of support rods (52).

4. The air intake (3) according to any one of the preceding claims, characterized in that the front mounting flange (34) and the rear flange (44) are fastened together by fastening means (45), the support structure (50) being fastened to the rear flange (44) with all or part of these same fastening means (45).

5. The air intake (3) according to any one of the preceding claims, characterized in that the portion of the outer wall (33) configured to come at least into contact with the upper end of the support structure (50), preferably at the level of a support surface (51) of said support structure (50), comprises a downstream end (33') of the outer wall (33).

6. The air intake (3) according to any one of the preceding claims, characterized in that, besides being in contact against a support surface (51) of the support structure (50), the outer wall (33) is bearing against it and fastened thereto by fastening means (35).

7. The air intake (3) according to any one of the preceding claims, characterized in that the downstream end (33') of the outer wall (33) is configured to support a front end (43') of the fan external cowl (43), in the assembled position, this support being preferably completed by fastening means.

8. A nacelle (1) for an aircraft engine characterized in that it includes an air intake (3) according to any one of the preceding claims.