EP2326555A1

EP2326555A1 - Nacelle with a variable nozzle section

Info

Publication number: EP2326555A1
Application number: EP09784266A
Authority: EP
Inventors: Guy Bernard Vauchel
Original assignee: Aircelle SA
Current assignee: Safran Nacelles SAS
Priority date: 2008-09-24
Filing date: 2009-07-10
Publication date: 2011-06-01
Also published as: BRPI0917696A2; US20110174899A1; FR2936222B1; CA2734417A1; RU2011115146A; US8919667B2; CN102131705A; WO2010034893A1; FR2936222A1; CN102131705B; CO6361863A2; RU2532682C2

Abstract

The invention relates to a nacelle that comprises a fixed structure (20), a nozzle with a variable section, and a cowling (30) mounted on said fixed structure (20) so as to be capable of sliding particularly along a travel so as to modify the section of said nozzle, characterised in that the nacelle further comprises an aerodynamic continuity assembly (40) provided between the fixed structure (20) and the mobile cowling (30), said assembly (40) including an elastic means that can be compressed between the fixed structure and said mobile cowling when the cowling is in the upstream portion of the travel thereof and that can expand when the cowling is in the downstream portion of the travel thereof so as to ensure the aerodynamic continuity of the lines between said fixed structure (20) and said mobile cowling (30).

Description

Nacelle with variable nozzle section

The present invention relates to a turbojet engine nacelle comprising a variable nozzle section. A nacelle generally has a tubular structure comprising an air inlet upstream of the turbojet engine, a median section intended to surround a fan of the turbojet engine, a downstream section housing a thrust reverser means and intended to surround the combustion chamber of the turbojet engine. , and is generally terminated by an ejection nozzle whose output is located downstream of the turbojet engine.

Modern nacelles are intended to house a turbofan engine capable of generating through the blades of the rotating fan a flow of hot air (also called primary flow) from the combustion chamber of the turbojet engine, and a flow of cold air (secondary flow) flowing outside the turbojet engine through a vein formed between a fairing of the turbojet and an inner wall of the nacelle. The two air flows are ejected from the turbojet engine from the rear of the nacelle.

The role of a thrust reverser is, during the landing of an aircraft, to improve the braking capacity thereof by redirecting forward at least a portion of the thrust generated by the turbojet engine. In this phase, the inverter obstructs the cold flow vein and directs the latter towards the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft.

The means implemented to achieve this reorientation of the cold flow vary according to the type of inverter.

Thus, the grid inverters, as illustrated in FIGS. 1 to 3, are known in which the reorientation of the air flow is carried out by deflection grids 1 associated with a sliding cover 2 intended to reveal or cover these grids. 1, the translation of the hood 2 being effected along a longitudinal axis substantially parallel to the axis of the nacelle.

This sliding cowl 2 is thus able to pass alternately from a closed position illustrated in FIG. 1 in which it ensures the aerodynamic continuity of the nacelle and covers the deflection grids 1 at an open position in which it opens a passage in the nacelle for the deviated flow and discovers the deflection grids 1. Moreover, in addition to its thrust reversal function, the sliding cowl belongs to the rear section and has a downstream side forming the ejection nozzle 3 for channeling the ejection of the air flows.

This nozzle 3 comprises at least one panel 4 rotatably mounted, said panel 4 being adapted to pivot between a normal position illustrated in FIG. 1 in which it ensures the aerodynamic continuity of the nacelle, a thrust reversal position in which it obstructs the cold flow vein 5 and a position shown in Figure 2 causing a variation of the nozzle section 3. It is possible to adjust the degree of pivoting of the movable panel 4 and allow to either vary the nozzle section of ejection 3 is to cause the reversal of the cold air flow in the vein 5 in reverse jet according to the degree of displacement of the movable cover 2.

Thus, as illustrated in FIG. 2, to reduce the section of the ejection nozzle 3 by driving the panel 4 towards the inside of the vein 5, the movable cover 2 must be advanced upstream in the direction of the structure fixed upstream 6 of the nacelle.

In order to be able to ensure this simple movement of translation of the mobile hood 2 upstream and, consequently, the free movement between the mobile hood 2 and the upstream fixed structure 6 of the nacelle, a cavity 7 is created at the interface between these two elements.

However, as illustrated in detail in FIG. 3, the presence of this cavity 7 generates a discontinuity of the aerodynamic lines of the surface of the nacelle, resulting in a degradation of the performance of the propulsion unit of the latter and an increase in consumption. of the aircraft.

An object of the present invention is to overcome the aforementioned drawbacks.

For this purpose, the invention proposes a nacelle comprising a fixed structure, a nozzle of variable section and a cover slidably mounted on said fixed structure in particular in a race for varying the section deladite nozzle characterized in that it comprises, in in addition, a set of aerodynamic continuity arranged between the fixed structure and the movable cowl, said assembly comprising elastic means able to be compressed between the fixed structure and said movable cowl when the cowl is in the upstream portion of its travel and to relax when the hood gets located in a downstream part of its race so as to ensure the aerodynamic continuity of the lines between said fixed structure and said movable cowl.

The present invention offers the advantage of eliminating the aerodynamic line defect in a direct jet between the upstream fixed structure and the movable cowl while allowing the free movement between these two elements, in particular so as to move the movable cowl 30 upstream of the the nacelle to vary the section of the nozzle.

According to particular embodiments of the invention, the device may comprise one or more of the following features, taken in isolation or in combination technically possible:

the aerodynamic continuity assembly comprises a flexible profile of elastomer type;

the aerodynamic continuity assembly comprises a rigid section able to be deformed elastically; - The profile is pin spring type, leaf spring or bellows;

the aerodynamic continuity assembly comprises a non-deformable rigid profile associated with elastic return means;

the profile is formed of a single piece or of several sectors of parts to be assembled together; the aerodynamic continuity assembly is capable of ensuring the aerodynamic continuity of the external lines between the upstream fixed structure and the movable hood;

the aerodynamic continuity assembly is capable of ensuring the aerodynamic continuity of the internal lines between the fixed structure and the movable hood;

a heel can be attached to the upstream end of the movable cowl;

the aerodynamic continuity element is integral with the fixed structure;

the aerodynamic continuity element is integral with the movable cowl;

the nacelle comprises a downstream section equipped with a thrust reverser device.

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows, according to embodiments given as non-limiting examples, and with reference to the appended drawings in which:

Figures 1 and 2 are schematic longitudinal sectional representations of a thrust reverser device of the prior art having movable panels respectively in normal nozzle position and closed nozzle position; Figure 3 is a detail view of Figure 1 on the interface between a movable cover and the upstream fixed structure of the thrust reverser device; FIG. 4 is a diagrammatic representation in longitudinal section of a thrust reverser device comprising a set of aerodynamic continuity according to a first embodiment of the present invention; Figures 5 to 8 are detail views of Figure 4 on the interface between a movable cowl and the fixed upstream structure of the thrust reverser device respectively before and after moving the movable cowl upstream; FIG. 9 is a diagrammatic representation in longitudinal section of a thrust reverser device comprising a set of aerodynamic continuity according to a second embodiment of the present invention; FIGS. 10 to 13 are detailed views of FIG. 9 on the interface between a movable cowl and the upstream fixed structure of the thrust reverser device respectively before and after movement of the upstream moving cowl;

Figures 14 and 15 are diagrammatic representations in longitudinal section of a thrust reverser device comprising a set of aerodynamic continuity according to a third embodiment of the present invention respectively before and after displacement of the movable cowl upstream;

FIGS. 16 and 17 are diagrammatic representations in longitudinal section of a thrust reverser device comprising a set of aerodynamic continuity according to a fourth embodiment of the present invention respectively before and after movement of the upstream moving cowl.

A nacelle generally has a structure comprising an upstream section forming an air inlet, a central section surrounding the turbojet fan and a downstream section surrounding the turbojet engine.

Referring to FIG. 4, this downstream section comprises an external structure 10 comprising a thrust reverser device and an internal motor fairing structure (not shown) defining with the external structure 10 a vein (not shown) intended to to the circulation of a cold flow in the case of the turbojet engine nacelle as presented here.

The downstream section further comprises an upstream fixed structure 20 comprising a front frame 21, said upstream fixed structure 20 being extended by a movable thrust reverser cover 30 and an ejection nozzle section (not shown).

The movable thrust reverser cover 30 is intended to be actuated in a substantially longitudinal direction of the nacelle between a closed position in which it covers grids 31 of airflow deflection and an open position in which it is spaced from the frame before 21 opening, then a passage in the nacelle by discovering the airflow deflection grids.

Furthermore, the ejection nozzle section in the extension of the movable cover 30 comprises a series of movable panels rotatably mounted at a downstream end of the movable cover and distributed over the periphery of the ejection nozzle section.

Each movable panel is adapted to pivot between several positions, namely a normal position in which it ensures the aerodynamic continuity of the nacelle, a reverse thrust position in which it obstructs the flow of cold flow and return this air to the grids deflection 31 which ensure the reorientation of the flow thus allowing the inverted jet and positions where they allow to vary the section of the nozzle.

It is the degree of displacement of the movable hood upstream and downstream which makes it possible to regulate the degree of pivoting of the movable panels and, thus, either to vary the direct jet ejection nozzle section or to drive the nozzle. inversion of the cold air flow in the reverse jet vein. In order to allow movement of the movable cover 30 upstream towards the front frame 21 to vary the section of the nozzle, a plurality of recesses 50, 51 may be provided between the front frame 21 and the movable cover 30 on the outer surface. of the nacelle and the inner surface of the front frame 21.

According to the invention, a set of aerodynamic continuity 40 is arranged at the interface of the front frame 21 and the movable cover 30 and housed in the recess or recesses 50, 51.

This aerodynamic continuity assembly 40 comprises elastic means capable of being compressed between the front frame 21 and the movable hood 30 when the hood is in the upstream portion of its stroke to vary the nozzle section and able to relax when the hood is in a downstream portion of its stroke so as to ensure the aerodynamic continuity of the lines between the front frame 21 and the movable hood 30.

More precisely, this set of aerodynamic continuity 40 fits into the aerodynamic profile of the nacelle taking several positions, namely:

- A relaxed position when the cover 30 is in a position in which the nozzle section does not vary, position in which it is intended to fill the space between the downstream end of the front frame 21 and the upstream end of the hood 30 movable to ensure aerodynamic continuity of the lines of the downstream section that is to say that the aerodynamic lines of the front frame 21 and the movable cover 30 are without breaking slope and,

- A compressed position in which it is adapted to allow movement of the movable cover 30 upstream to vary the section of the nozzle being covered by the latter during its advance upstream.

Advantageously, the presence of the aerodynamic continuity element 40 makes it possible to overcome the aerodynamic line defect in a direct jet while allowing displacement of the movable cover 30 upstream of the nacelle to vary the section of the nozzle.

Therefore, the performance degradation of the nacelle in direct jet is avoided. Preferably, the aerodynamic continuity element 40 can be placed at the interface between the front frame 21 and the movable cover 30 on the outer side the nacelle and / or the side of the cold flow vein thus ensuring the continuity of external aerodynamic lines and / or internal aerodynamic lines between these two elements as will be seen later with reference to the various figures.

In a first embodiment illustrated in Figures 4 to 6, there is an aerodynamic continuity member 40 in the form of a flexible section 41 adapted to ensure the continuity of the outer aerodynamic lines of the nacelle. This section 41 thus has a shape and dimensions adapted to fill the space existing between the downstream end of the front frame 21 and the upstream free end of the movable cover 30 when the cover 30 is in a position in which the nozzle section does not vary.

This profile 41 may have a downstream end having a form of overlap with the upstream end of the movable cover 30, in order to maintain the lowest aerodynamic line break possible even when moving upstream of the movable cover 30 to vary the section. of nozzle.

Advantageously, the aerodynamic continuity element 40 is sufficiently flexible to deform in contact with the upstream end of the movable cover 30 when the latter moves in a translation movement upstream towards the front frame 21 to rotate the movable panels of the nozzle and then to resume its neutral position and its shape after retreating the hood 30 downstream. In a non-limiting example, the profile 41 has a general shape in L.

It comprises, on the one hand, an upstream end configured to be fixed to the front frame 21 and having a shape complementary to the downstream end of the front frame 21 and, on the other hand, a downstream end having a shape complementary to the upstream end of the mobile cover 30.

The cover 30 having at its free end upstream a protrusion 32 extending along the longitudinal axis of the nacelle, the upstream end of the profile defined by the cavity of the L is the space necessary to receive the protrusion of the cover 30 mobile. The aerodynamic external lines of the nacelle are thus smoothed by the presence of the profile 41 between the front frame 21 and the hood 30. During a displacement of the hood 30 mobile upstream, the cover 30 tends to come into contact with the front frame 21 deforming the passage of the profile 41 which is housed under the hood 30.

In an alternative embodiment, the composition of the profile 41 may be reinforced with fibers. It can also be provided to introduce rigid elements in certain areas of the profile 41 desired indeformable.

In another variant embodiment, it is proposed to add an additional elastic element to the profile 41, in order to ensure that it properly covers its initial shape after retreating the hood 30 downstream of the nacelle. In a last variant embodiment, a heel 33 of suitable shape can be attached to the upstream end of the movable cover 30, in order to improve the contact interface with the aerodynamic continuity element 40 and thus to offer a controlled contact zone.

With reference to FIGS. 7 and 8, a flexible aerodynamic continuity element 40 is observed capable of ensuring the continuity of the internal aerodynamic lines of the nacelle on the side of the cold flow vein.

In a non-limiting example of the invention, this aerodynamic continuity element 40 may take the form of a tongue 42 intended to fill the recess 51 provided in the inner surface of the front frame 21 and, more precisely on the guide structure. of the air flow in the inversion phase.

This tongue 42 elongate comprises two opposite ends bearing on the inner face of the inner surface of the front frame 21 and a central portion facing the upstream end of the hood 30. The central portion of the tongue 42 has a curved section which the curvature is defined so as to ensure the continuity of the internal aerodynamic line of the inner surface of the front frame 21.

When moving the movable cover 30 upstream towards the front frame 21 to vary the section of the nozzle, the upstream end of the movable cover 30 enters the central portion of the tongue 42 and deforms.

After recoil of the hood 30 downstream of the nacelle, the tongue 42 resumes its original shape.

In an alternative embodiment, a heel 34 of suitable shape may be attached to the upstream end of the movable cover 30, as in FIGS. 4 to 6. In a second embodiment, the central portion of the tongue may be formed of a double wall to reinforce the aerodynamic continuity element 40. The central portion illustrated in Figures 7 and 8 is thus attached to an inner wall. T shape whose T bar forms the second wall of the double wall.

In a second embodiment illustrated in FIGS. 9 to 13, 16 and 17, the aerodynamic continuity unit 40 comprises a rigid section 43 able to be deformed elastically and intended to ensure the continuity of the aerodynamic external or internal lines of the nacelle. .

As illustrated in FIGS. 10 to 11, the profile 43 may take the form of a pin-like spring.

In a non-limiting example of the invention, the profile 43 has a general shape in J whose concavity is directed towards the front frame 21. More specifically, it has a first downstream end folded and fixed to the front frame 21, said end being extended by a transition portion intended to allow the inflection of the section 43, it itself extended by a rectilinear upstream end being fixed to the outer surface of the front frame 21 without breaking the slope with the latter. When the cover 30 is in a position where the section of the nozzle does not vary, the upstream end of the cover 30 is housed against the transition portion so that the front frame 21, the aerodynamic continuity member 40 and the movable hood then have no slope break on the outer surface of the nacelle. During a movement of the movable cover 30 upstream in the direction of the front frame 21, the upstream end of the cover 30 abuts and bears against the transition portion of the profile 43 causing the flexion of the latter, thus releasing a passage for advancing the upstream end of the cover 30 to the front frame 21. The bending point may advantageously be positioned downstream of its structure as shown in FIGS. 9 to 11. It may also be inverted but requires this a larger exhaust travel.

The section 43 may be made of metallic material or of composite material having elastic characteristics permitting the bending of part of its structure. Moreover, insofar as the upward displacement of the movable cover 30 causes the reduction of the outer diameter of the profile 43, it is necessary to provide slots which extend from the upstream end of the profile to the zone bending of the latter to allow its deformation. In addition, in order not to reduce the aerodynamic performance of the nacelle by the presence of these slots, they can be filled with flexible material like elastomer.

As illustrated in Figures 12 and 13, the section 44 may take the form of a leaf type spring adapted to ensure continuity of the aerodynamic internal lines of the nacelle on the side of the cold flow vein.

This profile 44 has a shape similar to that already described with reference to Figures 7 and 8.

However, in this embodiment, the section 44 is rigid and able to be elastically deformed. Thus, as illustrated in Figure 13, when moving the hood

Movable upstream towards the front frame 21 to vary the section of the nozzle, the upstream end of the movable cover 30 bears against the section 44 which bends inwardly of the front frame 21 so as not to create aerodynamic disturbances. Specifically, a free end of the section 44 not fixed on the inner face of the inner surface of the front frame 21 tilts inside the front frame to allow this bending.

The fixed portion of connection with the frame of the section 44 can be positioned at the bottom or the top relative to the recess 51. After retreating the cover 30 downstream of the nacelle, the section 44 resumes its initial position.

As in the other embodiments envisaged, a bead 34 can be attached to the upstream end of the movable cover.

Furthermore, with reference to Figures 16 and 17, there is another embodiment of the profile adapted to ensure the continuity of the outer and inner aerodynamic lines of the nacelle respectively in the form of bellows 45 and 46.

These bellows 45, 46 have shapes and dimensions adapted, as in the other embodiments, to ensure the aerodynamic continuity between the front frame 21 and the cover 30 when the cover is not in the nozzle section variation position . When the cover 30 is moved upstream in the direction of the front frame 21 as illustrated in FIG. 17, the upstream end of the cover 30 bears on the bellows 45, 46 which compresses, releasing a passage for the advance further upstream of the hood towards the front frame 21. After retreat of the movable cover 30, each bellows 45,46 returns to its original shape.

The number of corrugations of each bellows is determined so as not to exceed the elastic limit of the latter.

In a third embodiment illustrated in the figures

14 and 15, the aerodynamic continuity assembly 40 intended to ensure continuity the outer and inner lines of the nacelle comprises a non-deformable rigid section 47,48 associated with elastic return means.

More specifically, it comprises a section 47,48 fixed at one end of a spring-type element itself fixed at the opposite end to a bearing structure 49.

The carrier structure 49 may be either integrated with the front frame 21 as illustrated for the outer surface of the nacelle is independent of the front frame 21 but fixed on the latter as illustrated for the inner surface of the front frame 21.

Similarly to the other embodiments, the section 47,48 has a shape and dimensions adapted to fill the recesses 50,51 between the front frame 21 and the cover 30 and ensure the continuity of the aerodynamic lines between these elements. Moreover, during a displacement of the hood 30 upstream in the direction of the front frame 21 as illustrated in FIG. 15, the upstream end of the hood 30 bears on the profile 47, 48 which is compressed by means of the spring releasing a passage for the advance of the hood 30 to the front frame 21.

The direction of movement of the profile is defined by the direction of the contact forces at the interface between the section 47,48 and the upstream end of the movable cover.

In all of the embodiments described, the profile considered may consist of a single piece or an assembly of parts sectors. Those skilled in the art will appreciate, compared to nacelles of the prior art, a nacelle proposing a variable nozzle in takeoff and landing by moving the movable cowl beyond its closed position upstream of the fixed structure of the nacelle while not having any aerodynamic line defect direct jet flight phase.

Of course, the invention is not limited to the embodiments of this nacelle described above as examples but it embraces all the possible variants.

Thus, the invention can be applied to a nacelle not comprising a thrust reverser device.

The invention can also be applied to a nacelle comprising a thrust reverser device comprising, upstream, thrust reversing flaps under the deflection grilles and an associated movable cowl, downstream of the nacelle, to panels movable to ensure the sectional variation of the ejection nozzle.

Furthermore, in an alternative embodiment of the present invention, it can be provided that the aerodynamic continuity assembly is secured to the movable hood and compressed by the front frame during a movement of the movable cowl upstream of the nacelle.

Claims

1. Nacelle comprising a fixed structure (20), a hood (30) movable extended at its downstream end by a nozzle of variable section, said hood (30) being slidably mounted on said fixed structure (20) including a race for to vary the nozzle deladite section characterized in that it further comprises a set of aerodynamic continuity (40) arranged between the fixed structure (20) and the cover (30) movable, said assembly (40) comprising elastic means capable of being compressed between the fixed structure and said movable cowl when the cowl is in the upstream portion of its travel and to relax when the cowl is in a downstream part of its travel so as to ensure the aerodynamic continuity of the lines between said fixed structure (20) and said movable hood (30).

2. Nacelle according to claim 1 characterized in that the aerodynamic continuity assembly (40) comprises a section (41, 42) flexible elastomeric type.

3. Nacelle according to claim 1 characterized in that the aerodynamic continuity assembly (40) comprises a section (43,44,47,48) rigid capable of being deformed elastically.

4. Nacelle according to claim 3 characterized in that this profile is of pin spring type, leaf spring or bellows.

5. Nacelle according to claim 1 characterized in that the aerodynamic continuity assembly (40) comprises a rigid section (47,48) non-deformable associated with elastic return means.

6. Nacelle according to one of claims 2 to 5 characterized in that the section (41, 42,43,44,45,46,47,48) is formed of a single piece or several areas of parts to assemble together.

7. Nacelle according to claim 1 characterized in that the aerodynamic continuity assembly (40) is adapted to ensure the aerodynamic continuity of the external lines between the upstream fixed structure (20) and the cover (30) movable.

8. Nacelle according to claim 1 characterized in that the aerodynamic continuity assembly (40) is adapted to ensure the aerodynamic continuity of the internal lines between the fixed structure (20) and the hood

(30) mobile.

9. Nacelle according to one of the preceding claims characterized in that a heel (33,34) can be attached to the upstream end of the cover (30) movable.

10. Nacelle according to one of the preceding claims characterized in that the aerodynamic continuity element (40) is integral with the fixed structure (20).

11. Nacelle according to one of claims 1 to 9 characterized in that the aerodynamic continuity element (40) is integral with the movable hood

(30).

12. Nacelle according to one of the preceding claims characterized in that it comprises a downstream section equipped with a thrust reverser device.