FR3088307A1 - NACELLE FOR FIREPROOF AIRCRAFT TURBOREACTOR - Google Patents

Abstract

The present invention relates to a nacelle for an aircraft turbojet engine, comprising a wall (21) comprising a support element (35) of a device (37) annexed to the nacelle, said support element comprising: - a face (39) facing a fire zone of the nacelle (3), and - a gap (41) opening at the level of said face (39) facing the fire zone. According to the invention, the nacelle is remarkable in that the support element (35) comprises a device for closing the gap (41), non-flammable, mounted in said gap (41) and comprising one or more of the elements of the following group: metal tongue, metal tube, vulcanized seal. The invention also relates to a method for closing a gap (41) of a support element (35) of a device (37) annexed to a nacelle (3) for an aircraft turbojet engine.

Description

The present invention relates to a nacelle for an aircraft turbojet engine provided with a device intended to close interstices present at the level of joints between support elements for devices annexed to said nacelle. The invention also relates to a method for closing this gap.

An aircraft is powered by several propulsion units each comprising a turbojet engine housed in a nacelle also housing a set of ancillary devices linked to its operation, such as power transmission boxes or turbines, and ensuring various functions, when the turbojet engine is in running or stopped.

As illustrated in FIG. 1, a propulsion unit 1 comprises a nacelle 3, generally having a tubular structure along a longitudinal axis, and a turbojet engine 5. The nacelle 3 comprises a fixed upstream section 7 constituted by an air inlet upstream of the turbojet engine, a fixed middle section 9 intended to surround a fan of the turbojet engine, and a downstream section 11 which can house a thrust reverser device 13 and intended to surround the combustion chamber of the turbojet engine, upstream and downstream of the nacelle being defined by reference to the direction of flow of the air flow in the nacelle in direct jet operation, the upstream of the nacelle corresponding to a part of the nacelle through which the air flow enters, and the corresponding downstream to an ejection zone of said air flow. The propulsion unit 1 is also connected to a wing (not shown) of the aircraft by means of a pylon 15 or suspension mast.

Modern nacelles are often intended to house a double-flow turbojet engine capable of generating, via the blades of the rotating fan and a compressor, a flow of hot air, called primary, from the combustion chamber of the high pressure / low pressure turbines arranged downstream of the compression chamber. The compressor, combustion chamber and turbine assembly constitutes the gas generator of the turbojet engine, also called the core of the turbojet engine (or core).

A nacelle generally comprises an external structure comprising the air intake, the middle section and the rear section, and a concentric internal structure of the rear section, called the Inner Fixed Structure (IFS) surrounding the core of the turbojet engine behind the blower. . These external and internal structures define an annular flow channel, also called a secondary vein, aimed at channeling a flow of cold air, known as secondary, which circulates outside the turbojet engine.

The internal structure of the nacelle thus constitutes a cowling around the heart of the turbojet engine and can be designated under different names, in particular rear heart cover (Aft Core Cowl, ACC).

Auxiliary devices, such as power transmissions or turbines, can cause fires. They are housed in volumes of the nacelle then called "fire zones". Thus, the walls of these fire zones must resist a fire and be waterproof. These walls can be made of several joined elements 17, 19 visible in FIGS. 2 and 3 respectively illustrating in front view and in top view an assembly comprising a wall 21 of the nacelle 3, on which the so-called elements 17,19 are mounted. support, supporting for example a fitting 23 and having a face 25 facing a fire zone 27 of the nacelle.

Interstices 29 are generally present at the joints between the elements 17, 19. They allow to provide the clearance necessary for mounting fittings for the assembly of ancillary devices in the nacelle, such as fittings.

It is necessary to fill these gaps, after assembly, in order to achieve a fire barrier.

Usually, these interstices are closed by application of fire-resistant sealant 31, which can also extend along the face 25 of the elements 17, 19, facing the fire zone 27 of the nacelle.

Putty is a plastic paste obtained by mixing different synthetic or natural substances, so as to give it the desired mechanical properties. The sealant generally used to make a fire barrier at the joints between elements of a nacelle is composed of several polymers which vulcanize in the presence of humid air.

This paste is applied at the joints, then it polymerizes so as to close the interstices and create a tight barrier to fluids and flames.

Although the putty is not flammable on contact with fire, it expands and liquefies on contact with heat, and migrates outside the fire zone. Gas produced by the degradation of the putty is then emitted outside the fire zone where it can ignite on contact with air and the walls heated by the flames.

In addition, the use of certain sealants is prohibited by the aircraft manufacturer.

In addition, the installation time of these sealants is long because the installation requires meticulousness.

Also, the presence of these sealants affects the aesthetics of the nacelle.

Finally, the aging of these sealants is relatively poor depending on the environment. The effectiveness of these sealants is affected over time.

The present invention aims to provide a device making it possible to protect the interstice while overcoming the drawbacks listed above, and to do this relates to a nacelle for an aircraft turbojet engine, comprising a wall comprising a support element for an annex device of the nacelle, said support element comprising:

a face opposite a fire zone of the nacelle, and a gap opening at the level of said face opposite the fire zone, said nacelle being remarkable in that the support element comprises a device for closing the interstice, non-flammable, mounted in said interstice and comprising one or more of the elements of the following group: metal tongue, metal tube, vulcanized seal.

Thus, by planning to mount in the interstice a device for closing this interstice, non-flammable and selected from a group comprising a metal tongue, a metal tube, a vulcanized seal, this eliminates the need for use. putty at the gap, while ensuring a seal against fluids and flames.

According to optional characteristics of the nacelle according to the invention: the support element comprises an opening opening into the gap, said opening receiving the device for closing the gap;

according to one embodiment, the opening takes the form of an ovoid; the opening is made throughout the thickness of the support element;

in one embodiment, the support element comprises two support sub-elements separated by the gap, and the opening is made at the walls of said support sub-elements in contact with the gap;

the opening extends along a substantially vertical axis with respect to an axis representative of the longitudinal direction of the gap;

the metal tab of the interstice closure device defines a curved surface facing the fire zone of the nacelle;

the gap closure device is compressed inside the opening.

The present invention also relates to a method for closing a gap in a support element of an annex device of a nacelle for an aircraft turbojet engine, said gap opening at a face of said support element facing of a fire zone of the nacelle, remarkable in that it comprises the following stages aimed at:

practicing, by trimming, an opening leading into said interstice, mounting in said opening a device for closing the interstice, said device for closing the interstice being non-flammable and comprising one or more of the elements of the following group: tongue metal, metal tube, vulcanized gasket.

According to an alternative embodiment of the method according to the invention, the device for closing the gap is mounted in the opening in a compressed state.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

Figure 1 is a schematic view of a propulsion unit of aircraft of the prior art;

Figure 2 illustrates in front view an embodiment of the prior art of a fire barrier in a nacelle;

Figure 3 is a top view of the assembly shown in Figure 2;

FIG. 4 illustrates in front view the production of a fire barrier according to the invention;

Figure 5 is a simplified top view of a fire barrier obtained according to a first embodiment of the invention;

Figure 6 is a simplified top view of a fire barrier obtained according to a second embodiment of the invention;

Figure 7 is a simplified top view of a fire barrier obtained according to a third embodiment of the invention.

In the description and in the claims, the terms “upstream” and “downstream” must be understood with respect to the circulation of the air flow inside the propulsion assembly formed by the nacelle and the turbojet engine, it i.e. from left to right with reference to Figure 1.

In addition, in all of the figures, identical or analogous references represent identical or analogous members or sets of members.

Referring to Figure 4 in which is shown in front view a wall 21 of the nacelle 3, having on its upper face 33 a support member 35 of a device 37 annex to the nacelle.

The support element 35 is for example of generally parallelepiped shape. The support element 35 has a face 39 which faces the fire zone of the nacelle.

The support element 35 has a gap 41 which opens at the level of the face 39 opposite the fire zone of the nacelle.

The gap 41 is typically made over the entire depth of the support element 35, thus defining two support sub-elements 35a, 35b separated by the gap 41.

According to the invention, the support element 35 receives a closure device 43 of the gap 41, which is non-flammable. A first embodiment of the device for closing the gap is given in FIG. 5 to which reference is now made.

According to this first embodiment, the device for closing the gap is produced by a metal tongue 45. The fact of making this tongue from a metallic material makes it possible to provide a device for closing the fire-resistant gap, even in the event of expansion due to heat from the fire area of the nacelle.

The metal tongue 45 has a planar shape, for example parallelepipedic, in the rest state. The metal tongue may for example consist of a spring leaf.

According to one embodiment of the invention, the metal tongue 45 is held in the gap 41 by virtue of the presence of an opening 47, which opens into the gap 41. The opening 47 can, according to one embodiment, be obtained by trimming. The opening 47 adopts for example the shape of an ovoid, this in order to allow a clearance between the opening and the device for closing the gap, obtained in this embodiment by the metal tongue 45, which clearance allowing expansion of the shutter device that may occur due to heat from the fire area of the nacelle.

When it is mounted in the opening 47, the metal tongue 45 is curved and is then introduced into the opening 47 in compressed form. The positioning of the metal tab in the opening can, for example, be carried out using pliers.

Once mounted in the gap 41, the metal tongue has a curved surface 49, for example facing the fire zone 27 of the nacelle according to the embodiment shown in the figure.

According to one embodiment, the opening 47 extends along an axis 51 which is substantially vertical with respect to an axis 53 representative of the longitudinal direction of the gap 41, with reference to the direct trihedron L, V, T indicated to the figures. According to one arrangement, the opening 47 is made throughout the entire thickness of the support element 35.

The opening 47 is made at the side walls 55, 57 of the sub-elements 35a, 35b which are opposite one another and in contact with the gap 41.

As a variant, provision may be made to maintain the metal tongue 45 in the gap by any other means, in particular a mechanical fixing means, eliminating the presence of such an opening in the gap.

Referring now to Figure 6 showing a second embodiment of the invention.

This second embodiment differs from the first in that the device for closing the gap 41 is obtained by a metal tube 59.

The metal tube 59 has a substantially circular, oval, rectangular cross section, by way of nonlimiting examples. The metal tube can be continuous or discontinuous around its circumference.

As in the first embodiment, the metal tube 59 is held in the gap 41 through the opening 47.

The metal tube 59 is mounted in a slightly compressed state in the opening 47.

As a variant, provision may be made to maintain the metal tube 59 in the interstice by any other means, in particular a mechanical fixing means, eliminating the presence of such an opening in the interstice.

Reference is made to FIG. 7 representing a third embodiment of the invention.

This third embodiment differs from the previous ones in that the device for closing the gap 41 is obtained by a vulcanized seal.

61. The vulcanized seal is made of elastomeric material on which a vulcanizing agent has been incorporated.

As in the previous embodiments, the vulcanized seal 61 is held in the gap 41 through the opening 47.

The vulcanized seal 61 is mounted in a slightly compressed state in the opening 47.

As a variant, provision may be made to keep the vulcanized seal 61 in the interstice everywhere else, in particular a mechanical fixing means, eliminating the presence of such an opening in the interstice.

According to a common arrangement of the invention, it is envisaged to use the shutter devices from the embodiments which have just been described alone or in combination with each other.

It goes without saying that the present invention is not limited to the sole embodiments of this nacelle and of this method of closing a gap, described above only by way of illustrative examples, but on the contrary embraces all variants involving the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

Claims (10)

1. Nacelle (3) for an aircraft turbojet engine, comprising a wall (21) comprising a support element (35) of a device (37) annexed to the nacelle (3), said support element (35) comprising: a face (39) facing a fire zone (27) of the nacelle (3), and a gap (41) opening at the level of said face (39) facing the fire zone (27), said nacelle ( 3) being characterized in that the support element (35) comprises a device for closing the gap (41), non-flammable, mounted in said gap (41) and comprising one or more of the elements of the following group: metal tongue (45), metal tube (59), vulcanized seal (61). 2. Nacelle (3) according to claim 1, characterized in that the support element (35) has an opening (47) opening into the gap (41), said opening (47) receiving the shutter device the gap (41). 3. Nacelle (3) according to claim 2, characterized in that the opening (47) takes the form of an ovoid. 4. Nacelle (3) according to one of claims 2 or 3, characterized in that the opening (47) is formed throughout the thickness of the support element (35). 5. Nacelle (3) according to any one of claims 2 to 4, in which the support element (35) comprises two support sub-elements (35a, 35b) separated by the gap (41), characterized in that the opening (47) is made at the walls (55, 57) of said support sub-elements (35a, 35b) in contact with the gap (41). 6. Nacelle (3) according to any one of claims 2 to 5, characterized in that the opening (47) extends along an axis (51) substantially vertical with respect to an axis (53) representative from the longitudinal direction of the gap (41). 7. Nacelle (3) according to any one of claims 1 to 6, characterized in that the metal tongue (45) of the device for closing the gap (41) defines a curved surface (49) facing the fire zone (27) of the nacelle (3). 8. Nacelle (3) according to any one of claims 2 to 7, characterized in that the device for closing the gap (41) is compressed inside the opening (47). 5 9. Method for closing a gap (41) of a support element (35) of a device (37) annexed to a nacelle (3) for an aircraft turbojet engine, said gap (41) opening out at level of a face (39) of said support element (35) opposite a fire zone (27) of the nacelle (3), characterized in that it comprises the following steps aimed at: 10 - practice, by trimming, an opening (47) opening into said interstice (41), mounting in said opening (47) a device for closing the interstice (41), said device for closing the interstice ( 41) being non-flammable and comprising one or more of the elements of the following group: metal tongue (45), metal tube (59), vulcanized seal (61). 10. Method according to claim 9, characterized in that the device for closing the gap (41) is mounted in the opening (47) in a compressed state.