阅读说明：本技术 包括导流叶片的涡轮喷射引擎短舱的进气管 (Air intake duct of a turbojet engine nacelle comprising guide vanes ) 是由 安东尼·宾德 丹尼尔-西普里安·明库 于 2020-04-08 设计创作，主要内容包括：本发明公开了一种使用飞行器涡轮喷射引擎(1)的方法,飞行器涡轮喷射引擎包括进气管(2),进气管(2)包括多个导流叶片(3),每个导流叶片(3)以适于在缩回位置和伸出位置之间运动的方式安装,在缩回位置推力增大,在伸出位置(B),导流叶片(3)从内壁(21)径向向内伸出,以便引导内壁(21)上的反向气流(F-INV)以增大反推力；该方法包括,在涡轮喷射引擎(1)的推力阶段,使至少一个导流叶片(3)处于所述缩回位置,在涡轮喷射引擎(1)的反推力阶段,驱动导流叶片(3)运动至伸出位置。(The invention discloses a method of using an aircraft turbo jet engine (1) comprising an air inlet duct (2), the air inlet duct (2) comprising a plurality of guide vanes (3), each guide vane (3) being mounted in a manner adapted to move between a retracted position in which thrust is increased and an extended position (B) in which the guide vane (3) projects radially inwardly from an inner wall (21) so as to direct a reverse airflow (F-INV) over the inner wall (21) to increase reverse thrust; the method comprises, during a thrust phase of the turbojet engine (1), bringing at least one guide vane (3) in said retracted position and, during a thrust reversal phase of the turbojet engine (1), driving the guide vane (3) to move to the extended position.)

1. A method of using an aircraft turbojet engine (1) extending along an axis (X) oriented from upstream to downstream, an internal airflow (F-INT) in the aircraft turbojet engine flowing from upstream to downstream in a thrust phase and a reverse airflow (F-INV) in the aircraft turbojet engine flowing from downstream to upstream in a reverse thrust phase, the turbojet engine (1) comprising a fan (11) and a nacelle, the fan being configured to provide reverse thrust, the nacelle comprising an air inlet duct (2) extending circumferentially around the axis (X) and comprising an inner wall (21) facing the axis (X) and configured to guide the internal airflow (F-INT) and the reverse airflow (F-INV) and an outer wall (22) opposite the inner wall (21) and configured to guide the external airflow (F-EXT), -the inner wall (21) and the outer wall (22) are connected to each other by an inlet duct lip (23) so as to form an annular chamber (20), characterized in that the inlet duct (2) comprises a plurality of guide vanes (3) located upstream of the fan (11), each guide vane (3) moving between a retracted position (a) and an extended position (B):

-in the retracted position (a), the thrust is increased;

-in the extended position (B), the guide vanes (3) extend radially inwards from the inner wall (21) to direct a reverse airflow (F-INV) on the inner wall (21) to increase the reverse thrust;

-the method comprises, during a thrust phase of the turbojet engine (1), bringing at least one guide vane (3) in the retracted position (a); -driving the guide vanes (3) to move to the extended position (B) during a thrust reversal phase of the turbojet engine (1).

2. A method according to claim 1, characterized in that the guide vanes (3) of the inlet pipe (2) of the turbojet engine (1) are distributed circumferentially on the inlet pipe (2) about the axis (X).

3. The method according to claim 1 or 2, characterized in that the air intake (2) of the turbojet engine (1) comprises at least one driver (9) configured to drive the guide vanes (3) from the retracted position (a) to the extended position (B).

4. A method according to any one of claims 1-3, characterised in that the guide vanes (3) of the inlet pipe (2) of the turbojet engine (1) are movably and/or rotatably mounted in the inlet pipe (2).

5. The method according to any of claims 1-4, characterized in that the guide vanes (3) of the inlet pipe (2) of the turbojet engine (1) have an aerodynamic profile.

6. The method according to any one of claims 1 to 5, characterized in that the air intake duct (2) of the turbojet engine (1) comprises a cover (4) moving between a closed position (C1) and an open position (C2), in which closed position (C1) the cover (4) covers the guide vanes (3) in the retracted position (A) to ensure an aerodynamic profile of the thrust phase; in the open position (C2), the cover (4) is biased from a closed position (C1) to allow the guide vane (3) to move to the extended position (a).

7. Method according to any of claims 1-6, characterized in that the guide vanes (3) of the inlet pipe (2) of the turbojet engine (1) extend in the annular chamber (20) of the inlet pipe (2) in the retracted position (A).

8. A method according to any one of claims 1-7, wherein the turbojet engine (1) comprises fan blades (11), and the guide vanes (3) have a length less than 1/3 of the length of the fan blades (11).

Technical Field

The present invention relates to the field of aircraft turbo-jet engines, and more particularly to air intake ducts of aircraft turbo-jet engine nacelles.

Background

As is known, an aircraft comprises one or more turbojet engines, so as to enable its propulsion to be achieved by accelerating the airflow flowing from upstream to downstream in the turbojet engine.

Referring to fig. 1, a turbojet engine 100 is shown, which extends along an axis X and comprises a fan 101 rotatably mounted in a casing 102 about the axis X so as to accelerate an air flow flowing from upstream to downstream in the turbojet engine 100, i.e. an internal air flow F-INT, during a thrust phase of the turbojet engine 100. Hereinafter, the terms "upstream" and "downstream" are defined with respect to the flow direction of the internal gas flow F-INT.

As known, the turbojet engine 100 comprises a nacelle comprising, at its upstream end, an air intake duct 200 comprising an inner wall 201 facing the axis X and an outer wall 202 opposite the inner wall 201. The inner wall 201 and the outer wall 202 are connected by an inlet pipe lip 203 comprising a leading edge, thereby forming an annular cavity 220. The inlet duct 200 has an aerodynamic profile for dividing the upstream air flow F into an inner air flow F-INT guided by an inner wall 201 and an outer air flow F-EXT guided by an outer wall 202. Hereinafter, the terms "inner" and "outer" are defined with respect to the radial direction of the axis X of the turbojet engine 100.

In order to reduce the braking distance of an aircraft, in particular during landing, it is known to integrate a counterthrust system in the nacelle to change the direction of the airflow at the exhaust duct in order to generate the counterthrust. As is known, the thrust reversal is produced by opening flaps and/or grilles in the secondary flow downstream of the straightener, in order to direct the flow radially outwards or upstream.

For large bypass ratio turbojet engines, the nacelle has a large diameter and it is not desirable to install a conventional thrust reversal system in an integrated manner, since this would have a significant adverse effect on the weight, overall size and drag of the turbojet engine.

In order to generate the thrust reversal, another solution provides a variable pitch fan, or VPF, to reverse the flow of the air flowing in the secondary flow of the turbojet engine, so as to generate the thrust reversal to achieve the deceleration of the aircraft during landing or any other manoeuvre.

Referring to FIG. 2, during a reverse thrust phase, the reverse airflow F-INV flows downstream and upstream in the turbojet engine 100, i.e., in the opposite direction to the internal airflow F-INT in FIG. 1. More precisely, the reverse airflow F-INV flows between the head of the fan blade 101 and the housing 102. The reverse airflow F-INV is directed axially upstream by the inner wall 201 generally along the axis X. This reverse airflow F-INV is now opposite to the upstream airflow F, thereby achieving reverse thrust.

In fact, as shown in fig. 2, in the thrust reversal phase, the reverse air flow F-INV is twisted azimuthally under the action of the rotation of the fan 101. Therefore, the reverse airflow F-INV does not flow in the same direction as the upstream airflow F, which reduces the performance of the reverse thrust phase. Furthermore, part of the reverse airflow F-INV may bypass the aerodynamic profile of the air inlet tube 200 in a substantially radial direction, which may result in a local depression P near the air inlet tube lip 203. This local depression P generates an upstream suction force, i.e. a force opposite to the thrust reversal. In fact, this phenomenon very significantly affects the performance of the thrust reversal phase.

The invention therefore aims to reduce this phenomenon in order to improve the performance of the turbojet engine in the reverse thrust phase, without affecting the performance of the aircraft in the thrust phase.

In the prior art, it is known from patent application US3736750a1 that, in order to reduce noise, the air intake duct comprises a ring that is movable between cruise, take-off and landing conditions. This annulus does not increase the thrust reversal, especially for high bypass ratio jet engines, whose flap thrust reversal system is heavy and large in overall size.

Disclosure of Invention

The invention relates to an air inlet duct for an aircraft turbojet engine nacelle extending along an axis X oriented from upstream to downstream, the internal airflow in the aircraft turbojet engine nacelle flowing from upstream to downstream during a thrust phase and a reverse airflow flowing from downstream to upstream during a reverse thrust phase, the air inlet duct extending circumferentially around the axis X and comprising an inner wall facing the axis X and configured to direct the internal airflow and the reverse airflow, and an outer wall opposite the inner wall and configured to direct an external airflow, the inner wall and the outer wall being connected to one another by an air inlet duct lip.

The invention is remarkable in that the intake duct comprises a plurality of guide vanes, each guide vane moving between a retracted position and an extended position:

-retracted position, thrust increase;

in the extended position, the guide vanes extend radially inwardly from the inner wall so as to direct a reverse flow of air on the inner wall, thereby increasing the reverse thrust.

By means of the invention, the guide vanes are extended in order to guide the counter-current flow in the vicinity of the inner wall. Thus, the turning of the partial counter-flow is reduced or even eliminated, directly opposed to the axial flow, to obtain an optimal counter-thrust. Thus, with OGV-type blades located downstream of the fan and used during the thrust phase, the inlet duct guide blades upstream of the fan can be optimally directed during the reverse thrust phase to direct the reverse airflow from the fan.

Further, since the directed air flow is axially extending, this promotes separation of the air flow at the inlet duct lip and thus improves thrust by eliminating vacuum as compared to the prior art.

The term "guide vane" refers to an aerodynamic profile as well as any other profile such as a straight or inclined plate of constant thickness.

According to one aspect of the invention, the guide vanes are circumferentially distributed on the inlet duct, uniformly or non-uniformly about the axis X, in order to adjust the guiding according to the circumferential environment of the inlet duct and, more generally, of the nacelle. Thus, the reverse air flow can be advantageously directed as desired and limited.

According to one aspect of the invention, the air inlet duct comprises at least one driver configured to drive the guide vanes from the retracted position to the extended position.

According to one aspect, the drive is active. The drive member is in the form of a controllable actuator.

According to another aspect, the drive member is passive and preferably in the form of a pneumatic conduit formed in the annular chamber and leading to the guide vanes for moving the guide vanes between the retracted and extended positions by suction or blowing air.

According to another aspect, the guide vanes are movably and/or rotatably mounted in the inlet duct. The guide vanes are configured to rotate about an axis substantially parallel to the axis X (transverse rotation) or an axis substantially perpendicular to the axis X (longitudinal rotation).

According to one aspect of the invention, the guide vane has an aerodynamic profile. The guide vane comprises, in radial cross section, a downstream leading edge and an upstream trailing edge. Thus, the guide vanes are adapted to direct the airflow only during the reverse thrust phase. Preferably, the guide vane comprises a front side, in particular a curved surface, and a back side, in particular a curved surface.

According to one aspect of the invention, the air intake duct comprises a cover that moves between a closed position, in which it covers the guide vanes in the retracted position, and an open position, so as to ensure the aerodynamic profile of the thrust phase; in the open position, the cover is biased away from its closed position such that the guide vanes are in the extended position. This cover allows the aerodynamic profile of the air inlet tube to be optimised in the retracted position.

According to one aspect, the guide vanes extend in the annular cavity of the inlet pipe in the retracted position. According to one aspect, the guide vane extends into the azimuth cavity.

The invention also relates to an aircraft turbojet engine extending along an axis X oriented from upstream to downstream, the internal airflow in the aircraft turbojet engine flowing from upstream to downstream in the thrust phase and the reverse airflow in the aircraft turbojet engine flowing from downstream to upstream in the reverse thrust phase, the turbojet engine comprising a fan configured to provide reverse thrust and a nacelle comprising an air intake duct, as previously set forth, in order to increase the reverse thrust, the fan blades being located upstream of the fan.

According to a preferred aspect of the present invention, the turbine jet engine includes fan blades, and the guide vanes have a length less than 1/3 of the fan blades' length.

The invention also relates to a method of using an air intake as described above, comprising, during a thrust phase of the turbojet engine, bringing at least one guide vane into the retracted position; in a thrust reversal phase of the turbojet engine, the guide vanes are driven to move to the extended position, so that the guide vanes extend radially inward from the inner wall to guide the reverse airflow of the inner wall, thereby increasing thrust reversal.

Drawings

In order to more clearly illustrate the technical solution of the embodiments of the present invention, the drawings used in the description of the embodiments are briefly introduced below, wherein like reference numerals denote similar objects:

FIG. 1 is a longitudinal cross-sectional schematic view of a prior art turbojet engine nacelle during the thrust phase;

FIG. 2 is a schematic longitudinal cross-sectional view of a prior art turbojet engine nacelle during the reverse thrust phase;

FIG. 3 is a longitudinal cross-sectional schematic view of a turbojet engine nacelle of the present invention during the thrust phase;

FIG. 4 is a schematic longitudinal cross-sectional view of a turbojet engine nacelle of the present invention during the thrust reversal phase;

FIG. 5 is a schematic cross-sectional view of the air inlet tube of the present invention with a row of guide vanes on the lip of the air inlet tube in a retracted position;

FIG. 6 is a schematic cross-sectional view of an air inlet tube of the present invention with a row of guide vanes on the lip of the inlet tube in an extended position;

FIGS. 7A and 7B are schematic longitudinal cross-sectional views of an air inlet tube with guide vanes on a lip of the air inlet tube of the present invention in a first retracted position and in a second extended position, respectively;

FIG. 7C is a schematic longitudinal cross-sectional view of an air inlet tube including guide vanes fixedly attached to a cover member according to the present invention;

FIG. 8 is a partial schematic view of the air inlet duct in the plane of rotation with the guide vanes of the present invention in the extended position;

FIG. 9A, FIG. 9B, FIG. 9C and FIG. 9D are schematic diagrams of the movement of the rotating guide vanes of the present invention;

FIG. 10A, FIG. 10B, FIG. 10C and FIG. 10D are schematic views of the translational guide vane of the present invention moving in a direction relatively inclined to the radial direction;

fig. 11A and 11B are schematic views of an intake duct including a passive driver.

It should be noted that the accompanying drawings illustrate the invention in detail for the purpose of practicing the invention, and of course, may be used to further define the invention where appropriate.

Detailed Description

With reference to fig. 3 and 4, a turbojet engine 1 of the invention is shown, extending along an axis X oriented from upstream to downstream and comprising a fan 11 rotatably mounted about the axis X in a casing 12 defining an air flow. As known, the fan 11 is configured to accelerate, in a thrust phase, the air flow flowing from upstream to downstream in the turbojet engine 1, i.e. the internal air flow F-INT (fig. 3), and, in a thrust reversal phase, the air flow flowing from downstream to upstream in the turbojet engine 1, i.e. the reverse air flow F-INV (fig. 4). In effect, the reverse airflow F-INV flows downstream and upstream radially outward of the airflow, particularly at 1/3 beyond the radius of the airflow. The internal flow F-INT always flows from upstream to downstream radially inside the flow, particularly at 2/3, which exceeds the radius of the flow. The flow rate of the internal air flow F-INT is sufficiently fast to avoid any pumping phenomena of the turbojet engine.

As shown in fig. 3, the turbojet engine 1 comprises a nacelle comprising, at its upstream end, an air inlet duct 2 extending circumferentially about the axis X, the air inlet duct comprising an inner wall 21 facing the axis X and configured to direct an inner air flow F-INT and a reverse air flow F-INV, and an outer wall 22 opposite the inner wall 21 and configured to direct an outer air flow F-EXT. The inner wall 21 and the outer wall 22 are connected by an inlet tube lip 23 comprising a leading edge to form the annular cavity 20.

In the present embodiment, the turbojet engine 1 comprises thrust reversers, in particular variable pitch fans 11 or VPF, to reverse the flow of air flowing in the turbojet engine 1 and thus generate thrust reversals to achieve deceleration of the aircraft during landing.

According to the invention, with reference to fig. 3 and 4, the intake pipe 2 comprises a plurality of guide vanes 3, each guide vane 3 moving between a retracted position a and an extended position B:

in the retracted position a, the thrust is increased;

in the extended position B, the guide vanes 3 extend radially inwards from the inner wall 21 so as to direct the reverse air flow F-INV from the inner wall 21 to increase the thrust reversal.

The intake pipe 2 thus performs two different functions in the thrust phase and the thrust reversal phase. In the retracted position a, the guide vanes 3 do not influence the aerodynamic performance of the aerodynamically profiled leading edge 23. The thrust is therefore optimal.

As the guide vanes 3 move to the extended position B, each guide vane 3 may direct the F-INV airflow that has been previously twisted by the fan 11 during a thrust reversal phase. The directed reverse air flow F-INVR thus flows on the inner wall 21 of the inlet pipe 21, which is optimally opposite to the upstream air flow F. The performance of the thrust reversal phase is optimal.

According to the invention, during the thrust reversal phase, the guide vanes 3 function similarly to the vanes located in the secondary flow and are known to the person skilled in the art by the abbreviation "outlet guide vanes".

With reference to fig. 5, an intake pipe 2 is shown, comprising a plurality of guide vanes 3 distributed circumferentially on the intake pipe 2 about an axis X in such a way as to improve the performance in the thrust reversal phase. Preferably, the number of guide vanes 3 is sufficiently large to allow flow guidance over the entire circumference of the inlet pipe 2, while also being sufficiently small to reduce weight and drag. Preferably, when the turbojet engine 1 comprises OGV-type blades, the number of guide vanes 3 for the thrust reversal phase is substantially equal to the number of OGV-type blades.

Preferably, the guide vanes 3 may be different or may be moved to different extended positions in order to guide the reverse air flow unevenly at the circumference of the inlet duct. This advantageously takes into account the surroundings of the inlet pipe, in particular to reduce noise by guiding the reverse air flow.

Preferably, the guide vanes 3 are arranged in rows, each row of guide vanes comprising a plurality of guide vanes 3 at equal radial distances from the axis X. Alternatively, the guide vanes 3 may be located at different radial distances to achieve different degrees of guiding of the reverse air flow at the circumference of the inlet pipe. For example, one row of guide vanes is shown in fig. 5, but it is obvious that the number of rows may be larger.

The axial position of the guide vanes 3, i.e. the distance from the fan 11, may vary depending on the application. In fact, the closer the guide vanes 3 are to the fan 11, the better the guiding effect. Conversely, the farther the guide vane 3 is from the fan 11, the less noise is generated.

Referring to fig. 7A and 7B, an intake pipe 2 is shown, which includes guide vanes 3 moving in a radial direction. It goes without saying, however, that the direction of movement of the guide vanes 3 may comprise a longitudinal or azimuthal component, it being important that the direction of movement thereof comprises at least a radial component. Preferably, however, the direction of movement is radial, as it enables the guide vanes 3 to perform a similar function to radially extending OGV vanes. The inner wall 21 comprises an inlet 210 to the annular chamber 20 in which the guide vanes 3 move to the extended position B. The inlet 210 is dimensioned such that its clearance with the guide vanes 3 in the extended position B is minimal. This reduces the flow of the reverse air flow F-INV in the annular cavity 20 in the extended position B.

In the present embodiment, the air inlet duct 2 comprises a drive 9 to drive the guide vanes 3 in translation from the retracted position a to the extended position B. This drive 9 is, for example, an active drive 9, for example in the form of a pneumatic, hydraulic, electric or other actuator, which receives commands from the controller and drives the guide vanes 3. Preferably, the driver 9 may also drive the guide vanes 3 in translation from the extended position B to the retracted position a. The air inlet conduit 2 may comprise one or more drivers 9.

As shown in fig. 8, the guide vane 3 includes, in a radial cross section, a downstream leading edge BA and an upstream trailing edge BF. Preferably, the guide vanes have an aerodynamic profile so as to guide the reverse airflow F-INV at the front and back of the guide vane 3 and obtain an axially flowing guided reverse airflow F-INVR.

Still referring to fig. 7A and 7B, the driving member 9 may drive the guide vanes 3 to move radially inward so that the guide vanes 3 are extended and positioned in the reverse airflow F-INV twisted by the fan 11.

Alternatively, with reference to fig. 7A and 7B, the air inlet duct 2 comprises a cover 4 moving between a closed position C1 and an open position C2, in which said cover 4 covers the guide vanes 3 in the retracted position a, so as to ensure the aerodynamic profile of the thrust phase (fig. 7A); in the open position, the cover 4 is offset from the closed position C1 to allow the guide vanes 3 to move to the extended position B (fig. 7B). In the retracted position a, the covering member 4 covers the entrance 210, and in the extended position B, the covering member 4 does not cover the entrance.

Preferably, the cover 4 is made of the same material as the inner wall 21 and is shaped as an extension of the inner wall 21, so that the aerodynamic profile of the air inlet tube 2 remains unchanged during the thrust phase.

In the example of fig. 7A-7B, the cover 4 translates upstream along the inner wall 21 moving from the closed position C1 to the open position C2. It goes without saying, however, that the covering 4 may have other shapes and move in different ways, in particular in the circumferential direction. Further, the covering member 4 may include one or more components. Furthermore, the movement of the covering 4 can be driven by a drive 9 on the guide vane 3 or any other drive.

In the extended position B, as shown in fig. 7B and 8, the guide vanes 3 act on the reverse airflow F-INV so as to oppose the upstream airflow F axially and achieve optimal thrust reversal. The fan 11 can thus function in the thrust reversal phase.

Alternatively, referring to fig. 7C, the covering member 4 is integrally connected to the inner end of the guide vane 3 and moves together with the guide vane 3 in the reverse air flow F-INV. This embodiment only requires moving the guide vanes 3, which is advantageous.

Still referring to fig. 7C, the guide vane 3 comprises at its outer end a closure member 6 configured to at least partially block the inlet 210 of the inner wall 21, the guide vane 3 being moved relative to the inner wall 21 to the extended position B. This closure 6 advantageously makes it possible to reduce the flow of the reverse air flow F-INV in the annular cavity 20 of the intake pipe 2, in particular through the gap formed between the guide vanes 3 and the inlet 210. Of course, this closure 6 is also suitable for other embodiments. The closing element 6 is preferably formed integrally with the guide vane 3.

In fig. 7A to 7C, the guide vanes 3 have been shown moving substantially in the radial direction. However, the moving direction of the guide vane 3 may be other directions.

Referring to fig. 9A to 9B, a first rotational movement is shown in which the guide vanes 3 are pivoted about the upstream rotational axis 30. In the retracted position a (fig. 9A), the guide vanes 3 are longitudinally aligned downstream and then rotated upstream to deploy substantially radially in the extended position B (fig. 9B). In the extended position B, the guide vanes 3 do not have to be radially spread out, but may be inclined downstream or upstream.

Similarly, referring to fig. 9C to 9D, a second rotational movement is shown in which the guide vanes 3 are pivoted downstream about the rotary shaft 30. In the retracted position a (fig. 9C), the guide vanes 3 are longitudinally aligned upstream and then rotated downstream to be deployed substantially radially in the extended position B (fig. 9D). In the extended position B, the guide vanes 3 do not have to be radially spread out, but may be inclined downstream or upstream.

The guide vanes have been described as rotating about an axis of rotation (longitudinal rotation) substantially perpendicular to the axis X, but it is understood that the axis of rotation may be substantially parallel to the axis X (transverse rotation). According to this alternative, the guide vanes 3 are preferably located in the azimuth cavity in the retracted position a, in particular pressed against the inner wall 21.

The rotation is advantageous because it reduces the overall radial dimension of the guide vanes 3 in the retracted position a. It goes without saying that the guide vanes 3 can also be moved by a combination of rotation and translation.

According to a preferred aspect of the invention, the guide vane 3 constitutes a part of the inner wall 21 in the extended position. In other words, the guide vanes 3 are not located in the annular cavity 20 formed between the inner wall 21 and the outer wall 22.

Fig. 7A to 7C show the guide vane 3 extending substantially in the radial direction. Of course, it is also conceivable to extend in a direction inclined toward the downstream (fig. 10A to 10B) or inclined toward the upstream (fig. 10A to 10B).

According to one aspect of the invention, the movement of the guide vanes 3 can be achieved by driving a passive drive.

With reference to fig. 11A to 11B, the passive drive is in the form of a pneumatic conduit 9' formed in the annular chamber 20 and directed towards the guide vanes 3 in order to move the guide vanes 3 between the retracted and extended positions by means of suction or blowing air.

Preferably, the pneumatic conduit 9 'is connected to an overpressure source 90', which overpressure source 90 'can move the guide vanes 3 by suction due to the pressure difference between the air flow and the pneumatic conduit 9'. The pressure in the air flow is low because the fan 11 accelerates the reverse air flow F-INV. In this embodiment, the guide vanes 3 may be fully extended or partially extended due to the aerodynamic forces in the airflow. The passive drive is adapted to both translational and rotational motion.

According to one aspect of the invention, the pneumatic conduit 9' is fed by a reverse flow of air. Preferably, during the thrust phase, there is no longer a reverse flow, and the guide vanes 3 will automatically move to the retracted position a.

A method of using the intake pipe 2 of the present invention as described above is described below. For the sake of clarity, only the movement of a single guide vane 3 is illustrated, but it goes without saying that a plurality of guide vanes 3 may be moved simultaneously or successively.

During the thrust phase, the fan 11 accelerates the internal air flow F-INT flowing from upstream to downstream, which is guided by the air intake duct 2 with an aerodynamic profile to increase the thrust. During the thrust phase of the turbojet engine 1, the guide vanes 3 are in the retracted position, so that the air intake pipe 2 has an aerodynamic profile in order to guide the air flow. The use of the cover 4 ensures an optimal aerodynamic profile for the thrust phase.

During the reverse thrust phase of the turbojet engine 1, in particular after pitch changes of the fan blades 11, the one or more actuators 9 drive the guide vanes 3 to move to the extended position B, in which the guide vanes 3 project radially inwards from the inner wall 21 in order to direct the reverse airflow F-INV on the inner wall 21, thereby increasing the reverse thrust.

Advantageously, this method of use provides good performance of the aircraft both in the thrust phase, in which the internal airflow F-INT remains unchanged, and in the thrust phase, in which the guide vanes 230 allow the reverse airflow F-INV to be untwisted. Referring to fig. 8, the directed reverse airflow F-INVR flows opposite the upstream airflow F, providing effective thrust reversal.

According to one aspect of the invention, only part of the guide vanes 3 is moved during movement to adapt to different operating conditions, such as when braking.

By means of the invention, the turbojet engine 1 has a significant improvement in performance during the reverse thrust phase, while maintaining the existing performance during the thrust phase.