FR2982242A1 - Turbojet nacelle for aircraft propelling unit, has flaps pivotally mounted between retracted and deployed positions, and thrust reversing device whose offset unit provides kinematics offset between flaps adjacent to duct periphery - Google Patents

Abstract

The nacelle (10) has a thrust reversing device (20) including a sliding cap (30) that is movable in translation according to a direction parallel to a longitudinal axis of the nacelle. Upstream inversion flaps (34) are pivotally mounted between a retracted position in which the flaps ensure aerodynamic continuity with a blower casing of the nacelle, and a deployed position in which the flaps are blocked in a thrust reversing state. The thrust reversing device includes a kinematics offset unit providing a kinematics offset between the flaps adjacent to a periphery of a duct (14).

Description

The present invention relates to an aircraft propulsion unit comprising a turbojet engine nacelle equipped with a thrust reverser device with deflection grids. An aircraft is driven by several turbojets each housed in a nacelle also housing a set of ancillary actuators related to its operation and providing various functions when the turbojet engine is in operation or stopped. These auxiliary actuating devices include, in particular, a mechanical thrust reversal device. The propulsion unit of the aircraft formed of the nacelle and the turbojet engine 10 is intended to be suspended from a fixed structure of the aircraft, for example under a wing or on the fuselage, by means of a suspension pylon. . The 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 the thrust reverser means and intended to surround a combustion chamber and turbojet turbines, and is generally terminated by an ejection nozzle whose output is located downstream of the turbojet engine. This nacelle can be intended to house a turbojet engine, namely a turbojet capable of generating a hot air flow (also called primary stream) from the combustion chamber of the turbojet, and through the blades of the rotating fan and a cold air flow (secondary flow) flowing outside the turbojet through a flow vein of the cold air flow. An external structure called OFS (Outer Fan Structure in Anglo-Saxon terms), housing the means of thrust reversal, and an internal structure, called IFS 25 (Inner Fan Structure in Anglo-Saxon terms), intended to cover a downstream section. turbojet, both belonging to the downstream section of the nacelle, define the flow vein of the cold air flow and thus a passage section of the cold air flow. With regard to the thrust reverser device, it is adapted, during landing of the aircraft, to improve the braking capacity of the latter by redirecting forwards at least a portion of the thrust generated by the aircraft. turbojet. In this phase, it obstructs the flow vein of the cold air flow 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. .

In the case of a so-called grid inverter illustrated in FIGS. 1a to 1c, the reorientation of the cold air flow is carried out by deflection grids in association with a cover 1 having a sliding function designed to uncover or cover these grids.

Complementary upstream locking doors 2, also called upstream shutters, activated by the sliding of the hood 1, allow a closure in the upstream part of the flow vein 3 of the cold air flow, downstream of the grids so as to allow the reorientation of the cold air flow towards the deflection grilles. These upstream flaps 2 are pivotally mounted on the cover 1 sliding between a retracted position in which they provide, with said movable cover 1, the aerodynamic continuity of the radially outer wall of the annular duct 3 and an extended position in which, in situ thrust reverser, they at least partially close the vein 3 to deflect the flow of cold air to the deflection grids discovered by the sliding of the hood 1. The pivoting of each upstream flap 2 is guided by connecting rods 4 attached, on the one hand, to the shutter 2, and on the other hand, to a fixed point of the internal structure 5 of the nacelle defining the flow vein 3 of the cold air flow. These flaps 2 upstream are associated with intervolets 6, designated as island fairings in Anglo-Saxon terms whose role is to fill the space left free 20 by the flaps 2, in the retracted position, in order to ensure the aerodynamic continuity of the line of the radially outer wall of the annular vein. These intervolets 6 are fixed structural elements, which do not move during the different phases of flight of the aircraft and, in particular, during a reverse thrust. Each junction 6 is mounted on the outer panel of the thrust reverser cover 1 via lateral mounting profiles 7 and suitable fastening means such as blocking wedges and fasteners. Such an installation of upstream shutters 2 involves delicate management of the vein 3 ejection of the cold air flow. Indeed, the thrust reverser must effectively ensure the required inversion performance and, during operation in direct thrust, minimize aerodynamic drag not to damage the aerodynamic performance of the engine.

However, in the inverters of the type of those of Figures 1a to 1c, given the manufacturing tolerances and outcrops necessary for the proper operation of the flaps 2 inversion, there is on both sides of each flap 2 inversion a game with the intervolet 6 adjacent when the flaps 2 are in the retracted position. Over time, the interface between each component 2 and the adjacent intervolet 6 evolves and tends to increase the aerodynamic drag due to the evolution of games. Aerodynamic accidents in the full vein 3 multiply. Therefore, in this type of inverter, the problem of reducing aerodynamic drag so as not to degrade the aerodynamic performance of the engine remains. Furthermore, in this type of inverter, the effective acoustic surface is reduced by the assembly of intervolets 6 and the shape of the flaps 2 with which they cooperate. Such a thrust reverser device has, moreover, a complex structure because of the multiplicity of parts that constitute it and the need to ensure correct manufacturing tolerances and outcrops between fixed and moving surfaces to ensure the proper functioning of the components. inversion flaps. The reliability of such a device is affected, the maintenance difficulties are multiplied as the mass of the device. This mass is also affected by the attachment systems intervolets 6, often reinforced because of the risk of detachment of intervolets 6 during operation of the aircraft. An object of the present invention is to provide a nacelle for an aircraft with a thrust reverser device in which the losses related to the aerodynamic drag are reduced. It is also desirable to provide a thrust reverser device in which it promotes a gain in direct jet consumption. Another object of the present invention is to provide a nacelle whose mass of the thrust reverser device is reduced and the costs of assembly and maintenance are reduced. Another object of the present invention is to provide a thrust reverser device whose effective acoustic surface is increased and optimal.

For this purpose, the invention proposes a turbojet engine nacelle comprising: an external structure provided with a thrust reverser device; and an internal structure intended to cover a downstream section of the turbojet engine, the external structure and the internal structure. defining a flow vein of an air flow of the turbojet engine, the thrust reverser device comprising: at least one cowl movable in translation in a direction parallel to a longitudinal axis of the nacelle, the cowl being suitable to pass alternately from a closed position in which it ensures the aerodynamic continuity of the nacelle to an open position in which it opens a passage in the nacelle for the deflected air flow, 15 - upstream inversion flaps pivoted between a retracted position in which they provide aerodynamic continuity with a fan casing of the nacelle and an extended position in which, in situat thrust reversal ion, they come obstruct, in part upstream, the flow stream of the air flow to deflect the flow of air to the passage formed by the sliding of the hood, 20 all of said shutters inversion on the periphery of the vein being centered radially on the same axis. Said nacelle is remarkable in that the thrust reverser device further comprises means ensuring a kinematic shifted between said adjoining inversion flaps adjacent to the periphery of the vein. Thanks to the present invention, it is found that a source of increase in drag attributable to the upstream inversion flaps is eliminated. One can remove any intervolet and piece of attachment of these with the corresponding shutters. On the other hand, the outcropping sets are reduced, which favors a gain in direct jet consumption and the reduction of aerodynamic drag. In addition, it is possible to increase the effective acoustic surface of corresponding dimensions substantially to those of the removed intervolets.

According to other optional features of the nacelle according to the invention, taken alone or in combination: the means ensuring an offset kinematics between said adjacent upstream inversion flaps are adapted to implement an offset pivoting between two adjacent flaps; the means providing an offset kinematics between said adjacent upstream inversion flaps are adapted to deploy a flap upstream or downstream of the two adjacent flaps; the means providing an offset kinematics between said adjacent upstream inversion flaps comprise at least one drive rod for each of the flaps, each rod being rotatably mounted around anchor points respectively on the upstream inversion flap and on the internal structure, the anchoring points of the legs and / or connecting rod heads of two adjacent upstream inversion flaps being offset; - the anchoring points of the legs and / or rod ends of two adjacent upstream inversion flaps are offset along a central axis of the nacelle and / or radially relative to a central axis of the nacelle; the means providing an offset kinematics between said adjacent upstream inversion flaps comprise at least one pivot about which each upstream inversion flap is rotatably mounted, the pivots of two adjacent upstream inversion flaps being offset; the pivots of two adjacent flaps are offset along the central axis of the nacelle and / or radially relative to the central axis of the nacelle; the means ensure an offset kinematics between said adjacent upstream inversion flaps over the entire periphery of the vein. Other features and advantages of the present invention will emerge in the light of the following description, and on examining the appended figures, in which: FIG. 1a is a perspective view of a set downstream aircraft nacelle equipped with a thrust reverser device according to the prior art; FIG. 1b is an enlarged view of zone A of FIG. 1a; Figure 1c is a perspective view of an assembly of intervolets on a hood of the thrust reverser device of the prior art, illustrated in Figures 1a and 1b; FIG. 2 is a perspective view of a downstream assembly of aircraft nacelle equipped with a thrust reverser device according to one embodiment of the present invention; - Figures 3a and 3b are axial views of a thrust reversal device of a nacelle downstream assembly of Figure 2, respectively upstream and downstream of the device. In all of these figures, identical or similar numbers denote identical or similar members or sets of members. It should be noted that care has been taken to define in the description a three-axis marker X, YZ, these three axes being representative of: the longitudinal direction of the turbojet engine and of the nacelle for the X axis; direction from the longitudinal axis of the turbojet engine to the longitudinal axis of a suspension pylon of the aircraft propulsion system for the Z direction and, of the direction orthogonal to X and Z for the Y axis. In the case of a propulsion unit mounted under the wing of an aircraft, the Z axis is generally vertical. In the following description, the vertical axis will be assimilated to the Z axis, even if the aircraft propulsion unit is mounted in another configuration, such as for example in a rear fuselage, for simplification purposes. . It will also be noted that the upstream and downstream terms refer to the direction of the flow of air in the turbojet engine in normal direct jet operation. With reference to FIG. 2, part of the nacelle 10 of a propulsion unit of an aircraft is observed. In general, this aircraft propulsion unit is formed, in particular, by this nacelle 10 and a turbojet engine (not shown).

A pylon (not shown) makes it possible to suspend the propulsion unit to a fixed structure of the aircraft, for example under a wing or on the fuselage. The nacelle 10 is intended to form a tubular housing for the turbojet engine and serves to channel the air flows it generates through the blades of a fan (not shown), namely a flow of air hot through a combustion chamber of the turbojet, and a cold air flow flowing outside the turbojet engine. The nacelle 10 generally has a structure comprising an upstream section forming an air inlet, a median section surrounding the fan of the turbojet engine, and a downstream section 11 surrounding the turbojet engine and comprising a thrust reverser device 20. Referring more particularly to FIGS. 2 to 4, the downstream section 11 of the nacelle 10 comprises an outer structure 12 called OFS comprising the thrust reverser device 20 and an internal structure 13 called IFS for refitting the turbojet engine defining with the external structure 12, a vein 14 for the circulation and the exhaust of the cold air flow. The thrust reverser device 20, illustrated in these figures, is an inverter with deflection gates of the cold flow. Thus, this device 20 comprises a mobile cover 30 mounted in translation, in a direction substantially parallel to the central axis X of the nacelle 10, with respect to a fixed structure of the nacelle 10 comprising at least one front frame. This cover 30 is also extended by at least one ejection nozzle section 40 for channeling the ejection of the cold air flow, mounted at a downstream end of said cover 30. More precisely, the cover 30 comprises a outer ferrule 31 and an inner ferrule 32 which is in continuity with the front frame and is intended to delimit, in a direct jet position of the turbojet engine an outer wall of the vein 14 in which the flow of cold air flows. The cover 30 is able to pass alternately from a closed position 30 in which it ensures the aerodynamic continuity of the lines of the fixed structure of the nacelle 10 and covers deflection grids 50, at an open position, downstream of the nacelle 10, in which it is spaced from the front frame, thus revealing a passage in the nacelle and discovering deflection grids 50.

In its open position, the cover 30 allows the cold air flow of the turbojet to escape at least partially, this portion of flow being redirected upstream of the nacelle 10, in particular by the deflection grids 50 discovered , thereby generating a counter-thrust capable of aiding braking of the aircraft. In one embodiment of the thrust reverser device 20, in order to increase the portion of cold air flow passing through the deflection grids 50, the inner shroud 32 of the cover 30 may comprise a plurality of upstream inversion flaps. 34, distributed on its circumference.

Each inversion flap 34 is pivotally mounted at one end about a hinge axis or pivot, on the sliding cover 30, between at least one retracted position (illustrated in Figure 2), corresponding to a direct thrust operation of the turbojet engine, wherein the flap 34 obstructs the gate opening 50 and ensures the aerodynamic continuity of the inner vein 14 with the front frame, that is to say in the upstream portion of the vein 14, and a deployed position (illustrated in FIGS. 3a, 3b) in which, in a thrust reversal situation, it obstructs the vein 14 in its upstream part, with a view to deflecting the flow of cold air towards the grids 50. During operation of the turbojet engine in direct pushing, the sliding cowl 30 forms all or part of a downstream part of the nacelle, the flaps 34 being then retracted into the sliding cowl 30. In order to reverse the thrust of the turbojet engine 2, the sliding cowl 30 is displaced in position downstream ion and the flaps 34 pivot in the deployed position to deflect the flow of cold air to the grids 50 forming an inverted air flow guided by the grids 50. More specifically, more particularly reference to Figure 2, the nacelle 10 is formed of two half-covers 30, only one of which is visible in the figure, adapted to be connected to upper and / or lower beams (not shown) integral with the suspension pylon of the aircraft propulsion unit. These upper and lower girder girders are located vertically at the so-called 6 o'clock and 12 o'clock positions. The exhaust vein of the cold air flow 14 is of revolution about the longitudinal axis X. More specifically, the cross section, in the YZ plane, of the vein 14 is constant on the periphery of the vein 14.

As a result, as shown in FIG. 2, the deflection flaps 34 are centered radially on the central axis X of the nacelle or longitudinal axis. According to the invention, the thrust reverser device 20 comprises, in addition, means 100 providing a kinematic offset between the upstream inversion flaps 34 adjacent to the periphery of the vein 14 and, preferably, on the the whole periphery of the vein 14. More specifically, each flap 34 of inversion on the periphery of the vein 14 is supported by pivot points 120 integral with the inner ferrule 31 of the hood 30 and is pivotally driven by at least a driving rod 110 passing through the vein 14. Each driving rod 110 is rotatably mounted around anchoring points 111, 112 respectively on the corresponding flap 34 (illustrated in FIG. 2) and on the IFS internal structure. 13 of the nacelle 10 (shown in Figure 3a). Thus, during a movement of the hood 30 upstream or downstream of the nacelle 10 driven by a suitable actuator, each rod 110 ensures the pivoting of the flap 34 corresponding in the vein 14. It should be noted that , in the embodiment illustrated in Figures 2 to 4, the pivoting of the flap 34 around its pivot 120 is provided at its upstream end. It is of course possible to perform a hinge of the flap 34 downstream in the vein 16, by its downstream end. In addition, each pivot 120 may be transverse to the longitudinal axis X or not. Furthermore, the drive rods 110 can be mounted obliquely such that an end 111 of a connecting rod 110 connected to the flap 34 is upstream of an end 112 connected to the IFS 13. According to a second variant of FIG. realization, each rod 110 is mounted obliquely such that an end 111 of said rod 110 connected to the flap 34 is downstream of an end connected to the IFS 13. Advantageously, the means 100 ensuring kinematic shifted between the flaps upstream inversion 34 adjacent to the periphery of the vein 14 comprise drive means adapted to implement an offset pivoting of the flaps 34 on the periphery of the vein 16.

Such drive means deploy each upstream inversion flap 34 upstream or downstream of its flaps 34 adjacent, depending on the selected kinematics. In a first variant embodiment of such drive means, there is provided for an upstream inversion flap 34, a driving rod 110 whose anchoring points of the head and / or the small end 110 are relatively offset. at the anchoring points of the corresponding head and / or small end of the flaps 34 adjacent. Conventionally in the prior art, the flaps had the same movement during the recoil of the hood in its open position, the positions of the foot / rod head being placed each on their respective plane. More specifically, the anchoring points of the heads and / or the legs of connecting rods 110 of the upstream inversion flaps 34 can be shifted in two ways. They can be shifted along the X axis and placed downstream or upstream of the anchoring points of the heads and / or the connecting rod legs 110 of the inverting flaps 34 adjacent. They can also be offset radially with respect to the longitudinal axis X relative to the anchoring points of the heads and / or the connecting rod legs 110 of the inverting flaps 34 adjacent. The rods 110 for driving each of the flaps 34 for inversion over the entire periphery of the vein 16 may have, moreover, an identical length, which reduces maintenance errors and logistics costs. Of course, the number of drive rods 110 depends on loadings and balancing experienced by the upstream inversion flaps 34 and 25 will be adapted to the needs of the thrust reverser. In another alternative embodiment of such drive means, there is provided for an upstream inversion flap 34 a pivot 120 offset relative to the corresponding pivots flaps 34 adjacent. It can be shifted along the X axis and placed downstream or upstream of the pivots 120 of the inverting flaps 34 adjacent. It can also be shifted radially relative to the longitudinal axis X relative to the pivots 120 of the inverting flaps 34 adjacent. It should be noted that the different variants proposed are not exclusive of each other.

Associating several variants makes it possible, in particular, to offer more comfortable games for the kinematics of the thrust reverser flaps 34. Moreover, the offsets will be chosen as a function of the geometry of the flaps 34 and that of the vein 14, by appropriate tests or studies, in the optics, for example, to reduce the flaps of thrust reverser flaps 34. Thus, in operation, during a reverse thrust phase of the turbojet, the sliding cover 30 is moved downstream of the nacelle 10 causing, in its sliding, the pivoting of the inversion flaps 34 in the vein 14. At the end of their deployment, each flap 34 upstream inversion can be deployed, in part upstream of the vein 14, downstream or upstream of its two neighbors on the periphery of the vein 14. Advantageously, it has been found that modifying the kinematics of the upstream thrust reversal flaps 34 offers the possibility of controlling the aerodynamic drag. odynamic in vein 14 and reduce it. It should be noted that this is not the case for the thrust reversing flaps which are formed by the downstream panels of the nozzle 40 whose kinematics 20 can be shifted or not. In this type of thrust reverser, aerodynamics are degraded and aerodynamic drag is important, whatever the kinematics chosen for these panels. Indeed, such panels have aerodynamic disturbances 25 internal to the vein and external with risks of leaks and / or pressure losses between the pressure of the vein and the external. As illustrated in FIGS. 2,3a and 3b, the invention offers the advantage of eliminating the upstream intervolets of the prior art in the vein. These intervolets removed, the sets of outcrops between upstream inversion flaps 34 are less compared to the outcropping sets that existed between intervolets and inversion flaps of the prior art, which promotes the reduction of leaks and the reduction of the associated trnine.

In a nonlimiting example, the outcropping sets can be halved between the games of the prior art and the clearance between two upstream inversion flaps 34 adjacent according to the invention. Furthermore, since the surface of the upstream inversion flaps 34 has increased, the effective acoustic area of the upstream inversion flaps 34 can be increased and thus the acoustic properties of the thrust reverser device 20 can be improved. for example, to be increased by a surface substantially equal to that of the removed intervolets. In addition, the mounting of the thrust reverser device 20 is considerably simplified without the presence of the intervolets and blocking wedges or other associated fasteners, which promotes the reduction of the weight of the thrust reverser device 20 and simplifies assembly and maintenance procedures for these.

Although the invention has been described with particular exemplary embodiments, it is quite obvious that it is in no way limited thereto and that it comprises all the technical equivalents of the means described as well as their combinations if these enter in the context of the invention. For example, it would be possible to envisage applying the invention to a thrust reverser in which the thrust reverser cover is formed in one piece over the entire periphery of the reverser (inverter the so-called "0-duct" thrust) or in half C-type ducts, as illustrated. Furthermore, the thrust reverser device 20 comprises, in FIG. 2, five thrust reversing flaps 34 pivoting on each of the half-covers 25. Obviously, the number of flaps 34 depends on the geometry and the size of the turbojet and is not limited to those illustrated. In order to balance all the efforts, it is recommended to use an odd number of shutters to find a symmetry 12h / 6h. A number of 5 or 7 appears from appropriate experience.

Claims (8)

REVENDICATIONS1. A turbojet engine nacelle (10) comprising: - an external structure (12) provided with a thrust reverser device (20) and, - an internal structure (13) intended to cover a downstream section of the turbojet engine, the external structure and the internal structure defining a flow vein (14) for an air flow of the turbojet engine (2), the thrust reverser device (20) comprising: - at least one movable hood (30, 31, 32) in translation in a direction parallel to a longitudinal axis of the nacelle, the hood (30,31,32) being able to pass alternately from a closed position in which it ensures the aerodynamic continuity of the nacelle to an open position in which it opens a passage in the nacelle for the flow of deflected air, - flaps (34) of upstream reversal pivotally mounted between a retracted position in which they provide aerodynamic continuity with a fan casing of the nacelle (10 ) and a deployed position of in which, in reverse thrust situation, they obstruct, in the upstream part, the flow vein (14) of the air flow in order to deflect the flow of air towards the passage formed by the sliding of the hood (30), the set of flaps (34) of upstream inversion on the periphery of the vein (14) being centered radially on the same axis, the nacelle being characterized in that the thrust reverser device (20) further comprises means (100) providing kinematic offset between said adjacent upstream inversion flaps (34) on the periphery of the vein. 2. Nacelle according to claim 1 characterized in that the means (100) providing a kinematic offset between said flaps (34) of adjacent upstream inversion are adapted to implement pivoting offset between two adjacent flaps (34). 3. Nacelle according to claim 2 characterized in that the means ensuring a kinematic offset between said adjacent upstream inversion flaps are adapted to deploy a flap (34) upstream or downstream of the two adjacent flaps. 4. Nacelle according to one of claims 2 to 3 characterized in that the means (100) providing a kinematic offset between said flaps (34) adjacent upstream inversion comprise at least one connecting rod (110) for each drive flaps (120), each connecting rod (110) being rotatably mounted around anchor points respectively on the upstream inversion flap (34) and on the internal structure (13), the anchoring points of the feet and / or connecting rod ends of two upstream inversion flaps (34) being offset. 5. Nacelle according to claim 4 characterized in that the anchoring points of the feet and / or heads of rods (110) of two flaps (34) adjacent upstream inversion are offset along a central axis (X) of the nacelle (10) and / or radially with respect to a central axis (X) of the nacelle (10). 6. Nacelle according to one of claims 2 to 5 characterized in that the means (100) providing a kinematics offset between said inverting flaps (34) adjacent upstream comprise at least one pivot (120) around which each flap of Upstream inversion is rotatably mounted, the pivots of two adjacent upstream inversion flaps being staggered. 7. Nacelle according to claim 6 characterized in that the pivots (120) of two adjacent inversion flaps (34) upstream are offset along a central axis (X) of the nacelle and / or radially relative to the central axis (X) of the nacelle. 8. Nacelle according to one of claims 2 to 7 characterized in that the means (100) provide a kinematic offset between said adjacent upstream inversion flaps (34) over the entire periphery of the vein (14).