Nacelle for aircraft and aircraft comprising such nacelle

Abstract

The invention relates to a nacelle for an aircraft and an aircraft comprising such a nacelle. The nacelle comprises an engine compartment, an air intake compartment and a connection device connecting the engine compartment and the air intake compartment of the aircraft, the connection device comprising a first flange and a second flange disposed against the first flange, at least one of the first and second flanges being a joining flange, the connecting device comprises a connecting element locked in the at least one channel hole, the engine compartment and the air inlet compartment are fixed to each other through the connecting device, and the connecting flange is provided with a first supporting leg, called a base, and a second supporting leg, called a connecting supporting leg, inclined relative to the base. The first leg is shaped to be placed on an outer surface, referred to as a mounting surface, of one of the engine compartment and the air intake compartment, the second leg comprises at least one passage aperture for passage of a connecting element connecting the connecting flange with the other flange, the connecting flange comprises at least one groove cut into the connecting leg, and the passage aperture is configured to receive the connecting element. To create a local constriction of the cross-section.

Description

TECHNICAL FIELD

[0001] The present invention relates to a nacelle for an aircraft and to an aircraft comprising such a nacelle, in which a joining flange is provided to join the engine compartment to the intake compartment of the nacelle of the aircraft. BACKGROUND

[0002] An aircraft nacelle generally comprises an intake compartment and an engine compartment fixed to each other by a connecting device. This connecting device comprises as such at least two joining flanges mounted against each other and connected by a set of bolts.

[0003] In the event of engine damage, including in the event of blade loss ("fan blade out" or FBO), the connecting device must ensure the integrity of the nacelle structure. Blade loss is an event in which a fan blade of a jet engine detaches from its shaft, which causes damage to the propulsion assembly. Certification requirements require that the intake cannot detach from the engine and fall to the ground in any case. The connecting device is therefore designed for the purpose of meeting this constraint.

[0004] More particularly, if one of the blades of the fan detaches, a large amount of energy is released. The engine does not immediately stop its rotation and exerts a significant imbalance on the structure of the nacelle. This is a phase called "speed reduction": the rotation speed of the fan decreases, but the imbalance causes the structure to deform. The energy released is initially very large, then decreases, and this causes a wave on the structure that rotates at the rotation rate of the engine. The wave of energy caused by the imbalance generates a varying deformation at the connecting device. The joining flanges must then withstand in order to keep the intake fixed to the jet engine.

[0005] The known solutions consist in adding additional elements to the joining flanges and the set of bolts, such as an angle bar interposed between the flanges, to absorb the deformation and limit its propagation.

[0006] However, this solution is tricky to implement and makes the manufacture of the nacelle more complex.

[0007] The aim of the present invention is to remedy at least partially to these drawbacks. SUMMARY

[0008] To this end, a joining flange for joining an engine compartment of an aircraft with an air intake compartment is proposed, the joining flange having a first leg, called base, shaped to be placed on an outer surface of one of the engine compartment and the air intake compartment, called mounting surface, and a second leg, called joining leg, inclined with respect to the base and comprising at least one passage orifice for the passage of a connecting element for connecting said flange with another flange, the joining flange comprising at least one groove cut into the joining leg so as to create a local narrowing of the section.

[0009] With the joining flange according to the invention, it is possible to absorb the deformation wave in the event of a blade loss, the local narrowing of the section due to the groove creating a deformation zone of the flange. It is therefore the flange itself, by its deformation, which makes it possible to prevent the propagation of the deformation in the event of an FBO, without the need to add any other piece to the connection between the engine compartment and the air intake compartment.

[0010] According to another aspect, the groove extends parallel to the longitudinal edge of the joining leg.

[0011] According to another aspect, the groove extends over the entire length of the longitudinal edge of the joining leg.

[0012] According to another aspect, the groove extends over only a part of the length of the longitudinal edge of the joining leg.

[0013] According to another aspect, the groove extends in the lower half of the joining leg in terms of height, when the flange is mounted on the mounting surface.

[0014] According to another aspect, the joining leg comprises a sector around said at least one passage orifice for the passage of the connecting element.

[0015] According to another aspect, the flange comprises two grooves, each groove flush with an opposite face of the joining leg.

[0016] It should be noted that each groove is flush with one face of the joining leg and does not reach the opposite face of the joining leg.

[0017] Another subject of the invention is a connecting device for connecting an engine compartment of an aircraft with an air intake compartment, the connecting device comprising a first flange and a second flange arranged against the first flange, at least one of said first flange and said second flange being a joining flange as described above, the connecting device comprising a connecting element locked in said at least one passage orifice.

[0018] According to another aspect, each of the first flange and the second flange is a joining flange as described above.

[0019] Another subject of the application is a nacelle for an aircraft, the nacelle comprising an engine compartment, an air intake compartment and a connecting device as described above, the engine compartment and the air intake compartment being secured to each other by the connecting device.

[0020] Another subject of the application is an aircraft comprising a nacelle as described above. BRIEF DESCRIPTION OF DRAWINGS

[0021] Further features, details and advantages will become apparent from the following detailed description, and from the appended drawings, of which: Figure 1

[0022] [ Figure 1 ] is a schematic cross-section in a radial plane of a portion of the front of an aircraft comprising a connecting device according to the application. Figure 2

[0023] [ Figure 2 ] is a schematic cross-section in a radial plane of the connecting device in Figure 1 . Figure 3

[0024] [ Figure 3 ] is a schematic perspective view of a detail of the connecting device in Figure 1 , comprising the joining flange and the motor-side flange, the latter being partially shown. Figure 4

[0025] [ Figure 4 ] is a schematic perspective view of a detail of the connecting device in Figure 1 according to a variant embodiment. Figure 5

[0026] [ Figure 5 ] is a schematic perspective view of a detail of the connecting device in Figure 1 according to another embodiment. DETAILED DESCRIPTION

[0027] The examples and related conditions detailed herein are primarily intended to help the reader understand the principles of the application and should not be taken as limiting the scope of the application to these particular examples and conditions. It will be understood by those skilled in the art that various arrangements can be conceived that, although not explicitly described or depicted herein, embody the principles of the application and are included therein and within the spirit and scope of the application.

[0028] Furthermore, the following description can describe relatively simplified embodiments of the application for the sake of understanding. Other embodiments of the application can be more complex, as will be appreciated by those skilled in the art.

[0029] In some cases, modified examples of the application can also be presented. This is only to help the understanding and is likewise not intended to limit the scope or establish the limitations of the application. These modifications are not an exhaustive list and other modifications can be made by those skilled in the art, while still remaining within the scope of the application.

[0030] Furthermore, all statements herein relative to the principles, aspects and embodiments of the application, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. These equivalents are both currently known or later developed.

[0031] As apparent from the figures, one subject of the application is a joining flange 1 of a connecting device 2 of a nacelle 3 of an aircraft A. The application also relates to a connecting device 2 comprising a flange 1.

[0032] In Figure 1 The nacelle 3 comprises an intake compartment 4 and an engine compartment 5 (also called motor) in extension of the intake 4. The intake 4 is provided at the front of the nacelle 3 and makes it possible to direct an airflow in the direction of the motor 5. The intake 4 comprises a lip 6, the surface of which in contact with the aerodynamic flow extends inside the nacelle by an internal duct 7 and outside the nacelle by an external wall 8. The intake 4 is connected to the motor 5 by a connecting device 2.

[0033] As will be described in detail hereafter, the connecting device 2 comprises a flange 1 provided on one side of the intake 4 and a flange 9 provided on one side of the motor 5, the flanges 1, 9 being fixed to each other by bolts 10.

[0034] Reference will now be made to Figures 2 to 5 The joining flange 1 will be described in detail.

[0035] As apparent from these figures, the flange 1 comprises a first leg 11 called base and a second leg 12 called joining leg, which is inclined with respect to the base 11. The base 11 is shaped to be placed on an outer surface S of one of the engine compartment 5 and the intake compartment 4, this outer surface being called mounting surface S.

[0036] In the figures, the mounting surface S is the upper surface of the internal duct 7 of the intake 4.

[0037] In the illustrated embodiment, the joining leg 12 is provided orthogonally to the base 11.

[0038] Each of the two legs (base 11 and joining leg 12) advantageously has the overall shape of a portion of a circular ring C.

[0039] The joining leg 12 is delimited by two opposite longitudinal edges, marked 13 and 14, and by two opposite transverse edges, only one of which is visible in the figures, marked 15. The longitudinal edge 13 forms a junction with the base 11 and rests on the mounting surface 12, while the longitudinal edge 14 is free. The height H of the ring C is the distance between the longitudinal edge 13 and the longitudinal edge 14. The thickness E of the ring C is the thickness of the transverse edges and delimits an external face Fe of the joining leg 12 and an internal face Fi of the joining leg 12. The internal face Fi is provided on one side of the base 11, i.e. towards the intake mouth 4. As will be described in detail below, the external face Fe is provided towards the compartment 5 and is shaped to come into contact with the joining leg 12' of the flange 9.

[0040] As is evident from Figures 2 to 5 , the joining flange 1 comprises at least one recess 17, which is cut into the joining leg 12 so as to create a local narrowing of the section. In other words, the recess 17 reduces the thickness E of the joining leg 12.

[0041] The recess 17 is produced, for example, by orbital machining.

[0042] As can be seen in the figures, the recess can have any suitable shape, advantageously having a curved section, for example a semicircular section.

[0043] By locally narrowing the section, i.e. by reducing the material, a flexible zone is created, which allows elastic and programmed deformation of the flange 1. Thus, in the event of engine damage, and in particular in the event of blade loss, the flange deforms through its flexible zone, which allows absorption of at least part of the structural deformation.

[0044] The number, their dimensions and position of the recesses 17 are chosen so as to remain within the plastic limit of the flange 1 and not to reach the breaking point even in the case of FBO.

[0045] In Figure 2 and Figure 3 , the flange 1 comprises a single recess 17 which extends parallel to the longitudinal edges 13, 14 on the entire circumference of the joining leg 12. The recess 17 is closer to the longitudinal edge 13 than to the longitudinal edge 14, although, as mentioned above, the present invention is not limited to this position. In Figure 2 and Figure 3 , the recess 17 is flush with the external face Fe of the joining leg 12.

[0046] According to the variant in Figure 4 , in addition to the recess 17, the flange 1 also comprises a recess 17' which is flush with the internal face Fi of the joining leg 12. The recess 17 and the recess 17' are placed face to face. In other words, the recess 17 and the recess 17' are cut at the same height h on both sides of the thickness E of the joining leg 12.

[0047] The invention is not limited to this variant, and the two grooves 17, 17' can not be provided at the same height h.

[0048] In each of the embodiments illustrated, the joining leg 12 comprises a through aperture 18 for the passage of a shank 19 of a connecting element. As can be seen in Figures 1 to 3 the connecting element is for example a bolt 10, the shank 19 being a screw. Preferably, the apertures 18 are regularly spaced.

[0049] According to Figures 2 to 4 the first embodiment illustrated, the free longitudinal edge 14 is flat and the height H of the joining leg 12 is constant. According to Figure 5 the second embodiment illustrated, the free longitudinal edge 14 comprises a cut-out or sector 21 around the aperture 18. In other words, the height H of the joining leg 12 varies longitudinally.

[0050] For each aperture 18, D denotes a straight line passing through the aperture 18 and perpendicular to the longitudinal edge 13. The height H is greater when it is aligned with each aperture 18 (height Hmax), decreasing symmetrically with respect to the straight line D between the plateau P at the height Hmax and the plateau p at the height Hmin. The height Hmin substantially corresponds to the level of positioning of the aperture 18.

[0051] This embodiment has the advantage of protecting the area around the bolt, this being achieved by making the flange more flexible overall by means of the sectors 21, while increasing the flexibility of the flange 1, and this enhances the absorption of deformations by the flange 1.

[0052] The connecting device 2 will now be described.

[0053] As has been indicated, the connecting device 2 comprises the flange 1 and also comprises a flange 9. The flange 9 is a flange of the prior art without grooves 17, or is a flange according to the invention, in which case the flange has at least one groove 17. The flange 9 is not described in more detail and will be referred to the foregoing description, which then also applies to the flange 9.

[0054] The flanges 1 and 9 are fastened to one another by means of the bolts 10, the shanks 19 of the screws being inserted into the through apertures 18 and the nuts of the clamping screws. The bolts 10 form the elements for connecting the flange 1 to the flange 9.

[0055] As is apparent from the foregoing description, the flange 1 makes it possible to absorb deformations in the event of blade loss.

[0056] Advantageously, the dimensions (length, diameter) of the grooves 17 are chosen so that the deformations absorbed by the flange 1 correspond to the amount of energy released during the FBO.

[0057] The flange 1 is particularly suitable for new engine architectures of the UHBR ("Ultra High Bypass Ratio") type, in which the fan is enlarged and the amount of energy released during blade loss is even greater. In the case of these engine architectures, the bolts are even more highly loaded in the case of FBO, and the flange 1 allows them to be effectively protected by means of the flexible zone. The flange 1 can deform in a local and controlled manner, and thus protect the bolts and therefore the junction between the air intake 4 and the engine 5.

[0058] Furthermore, the reduction in material in the flexible zone makes it possible to reduce the mass of the flange, and this contributes to reducing the weight of the aircraft.

[0059] It should be noted that the recesses are understood to mean any non-through recess. The recesses do not pass directly through the material of the junction leg 12 from the face Fe until the face Fi, and vice versa. On the contrary, the recesses leave material between them and the faces that are not flush with the recesses.

[0060] Modifications and improvements to the above-described embodiments of the application can be made by persons skilled in the art without departing from the scope of the application. In particular, the described examples and variants can be combined, provided they are not incompatible. The above description is illustrative and not restrictive. The scope of the application is therefore only limited by the scope of the following claims.

Claims

1. A nacelle for an aircraft, the nacelle comprising an engine compartment, an air intake compartment, and a connecting device for connecting the engine compartment (5) and the air intake compartment (4) of an aircraft (A), the connecting device comprising a first flange (1) and a second flange (9) disposed abutting against the first flange (1), at least one of the first flange and the second flange being a connecting flange, the connecting device (2) comprising a connecting element locked in at least one channel opening (18), the engine compartment and the air intake compartment being secured to each other by the connecting device, the connecting flange having a first portion referred to as a base (11). The first leg is shaped to rest on the outer surface (S) of one of the engine compartment (5) and the intake compartment (4), the outer surface being referred to as the mounting surface. The second leg includes the at least one channel opening (18) for passage of a connecting element (10) for connecting the connecting flange to another flange. The second leg is inclined relative to the base (11). The connecting flange includes at least one groove (17) cut into the connecting leg (12) to create a local narrowing of the cross section.

2. The nacelle according to claim 1, wherein, The groove (17) extends parallel to the longitudinal edges (13, 14) of the connecting leg (12).

3. The nacelle according to claim 2, wherein, The groove (17) extends along the entire length of the longitudinal edges (13, 14) of the connecting leg (12).

4. The nacelle according to claim 2, wherein, The groove extends only along a portion of the length of the longitudinal edges (13, 14) of the connecting leg (12).

5. The nacelle according to any one of the preceding claims, wherein, The groove (17) extends in the lower half of the connecting leg (12) in terms of height.

6. The nacelle according to any one of the preceding claims, wherein, The connecting leg (12) includes a sector (21) surrounding the at least one channel opening (18) through which the connecting element (10) passes.

7. The nacelle according to any one of the preceding claims, wherein, The connecting flange includes two grooves (17, 17'), each groove being flush with the opposite side (Fe, Fi) of the connecting leg (12).

8. The nacelle according to any one of the preceding claims, wherein, Each of the first flange and the second flange is a connecting flange.

9. An aircraft comprising a nacelle according to any one of the preceding claims.

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