Air vehicle bypass turbojet engine nacelle outflow duct including a guide for a reverse thrust phase

Abstract

The exhaust pipe (4) of the nacelle (2) of the aircraft bypass turbojet engine (T) includes a downstream inner wall (41) and a downstream outer wall (42) connected by a trailing edge (43). At least one radial through-hole (44) located at the corner of the exhaust pipe (4) includes an inner opening surface (45) and an outer opening surface (46). The guide device (1) for each radial through-hole (44) includes an inner moving part (10) and an outer moving part (11). The outer movable part (11) moves between the closed position (F) and the open position (O). In the closed position (F), the inner movable part (10) and the outer movable part (11) close the inner opening surface (45) and the outer opening surface (46) respectively, and the through hole (44) defines a closed cavity. In the open position (O), the inner movable part (10) and the outer movable part (11) are used to allow the external airflow (F-EXT) to flow in the through hole (44) to facilitate the reverse thrust stage (P2).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft bypass turbojet engines, and more specifically to an outflow duct for a nacelle of an aircraft turbojet engine. BACKGROUND

[0002] As known, an aircraft comprises one or more turbojet engines configured to enable, in a thrust phase, the propulsion of the aircraft by accelerating an airflow flowing from upstream to downstream in each turbojet engine, called internal airflow. Hereinafter, the terms "upstream" and "downstream" are defined with respect to the direction of flow of the internal airflow in the thrust phase.

[0003] As known, with reference to Figure 1 illustrates an aircraft bypass turbojet engine TAA extending along a longitudinal axis X and comprising a fan 500 rotating about the longitudinal axis X and configured to accelerate, in a thrust phase PI of the turbojet engine TAA, an internal airflow F-INT. The turbojet engine TAA is further provided with a radially inner primary flowpath 600 and a radially outer secondary flowpath 700 downstream of the fan 500, separated by a casing 800. The casing 800 is configured to channel, in the primary flowpath 600, a first portion of the internal airflow F-INT, called primary airflow Fl, for burning fuel, and to channel, in the secondary flowpath 700, a second portion of the internal airflow F-INT, called secondary airflow F2, to generate the thrust of the turbojet engine TAA. Hereinafter, the terms "inner" and "outer" are defined in a radial direction with respect to the longitudinal axis X.

[0004] As known, still with reference to Figure 1 illustrates an aircraft propulsion assembly EAA comprising the turbojet engine TAA and a nacelle 200 extending circumferentially around the longitudinal axis X of the turbojet engine TAA radially outward of the fan 500 and delimiting the secondary flowpath 700. The nacelle 200 is provided, at its upstream end, with an inlet duct 300 and, at its downstream end, with an outflow duct 400. The inlet duct 300 comprises an upstream inner wall 310 facing the longitudinal axis X and an upstream outer wall 320 opposite the upstream inner wall 310, the upstream inner wall 310 and the upstream outer wall 320 being connected together upstream by an inlet duct lip 330 comprising a leading edge. The inlet duct 300 has a circular profile in accordance with aerodynamics, so as to enable the separation of an upstream airflow F into an internal airflow F-INT channeled by the upstream inner wall 310 and an external airflow F-EXT channeled by the upstream outer wall 320.

[0005] As known and similarly to the inlet duct 300, still with reference to Figure 1, the outlet pipe 400 of the nacelle 200 comprises a downstream inner wall 410 facing the longitudinal axis X and a downstream outer wall 420 opposite the downstream inner wall 410, the downstream inner wall 410, the downstream outer wall 420 being connected together downstream through the trailing edge 430. The outlet pipe 400 comprises a profile tapering downstream, thus enabling the secondary flow F2 to be directed from the secondary channel 700 to the outside of the turbojet engine TAA.

[0006] To reduce the braking distance of the aircraft, in particular during landing, it is known to integrate a thrust reversal system in the nacelle 200, to enable the direction of the secondary flow F2 at the exhaust to be changed, thus enabling a reverse thrust to be implemented. It is known that the reverse thrust phase can be implemented by at least partially blocking the secondary channel 700 downstream of the fan 500, in order to redirect the secondary flow upstream of the turbojet engine TAA, such as shown in patent application FR2120172A1 Figure 1 -7, in particular by means of a grid provided in the nacelle 200. However, for a turbojet engine TAA having a particularly high bypass ratio, i.e. a ratio of the mass of the secondary flow F2 to the mass of the primary flow F1 greater than 16, the nacelle 200 has a large diameter, and the integration of such a thrust reversal system thereon is not ideal, since it would significantly impact the mass, volume and drag of the turbojet engine TAA.

[0007] Another solution to reduce the braking distance of the aircraft consists in providing a variable-pitch fan (VPF) 500. The fan 500 comprises blades whose pitch angle is set to be able to reverse the flow direction of the secondary flow F2 in the secondary channel 700, thus enabling the aircraft to be decelerated, in particular during landing.

[0008] With reference to Figure 2A , in the reverse thrust phase P2, the reverse flow F-INV drawn from the external flow F-EXT enters the secondary channel 700 at the trailing edge 430 of the outlet pipe 400 of the nacelle 200 and flows in the secondary channel 700 from downstream to upstream, i.e. opposite to the secondary flow F2 in Figure 1 . The reverse flow F-INV from the secondary channel 700 then crosses the fan 500 and is directed upstream by the upstream inner wall 310 of the inlet pipe 300, then the reverse flow F-INV is opposite to the upstream flow F, in particular radially outside the nacelle 200, thus enabling braking to be implemented. In the same way as for the thrust phase P1, the internal flow F-INT from the upstream flow F flows from upstream to downstream at the base of the fan 500, i.e. radially inside in the opposite direction to the reverse flow F-INV, to provide the primary flow F1. The primary flow F1 can also be provided by a portion of the reverse flow F-INV that bypasses the casing 800.

[0009] In practice, as Figure 2A andFigure 2B As shown, the blades of the fan 500 drive the counter-flow F-INV at the inlet duct 300 according to a torsional motion V along the longitudinal axis X. This torsional motion V can be transmitted to the external flow F-EXT guided by the upstream outer wall 320 of the inlet duct 300 and flowing along the nacelle 200 from upstream to downstream. The external flow F-EXT is next extracted at the outlet duct 400 of the nacelle 200 to form the counter-flow F-INV. The counter-flow F-INV entering the secondary flow channel 700 thus also comprises a torsional motion portion V' transmitted by the external flow F-EXT, which solution is not optimal as it reduces the reverse thrust performance.

[0010] Moreover, still referring to Figure 2A and Figure 2B , the conical profile of the outlet duct 400, which is aerodynamic during the thrust phase PI, generates a recirculation zone R in the secondary flow channel 700 at the outlet duct 400 during the reverse thrust phase P2. More precisely, the external flow F-EXT from upstream detaches from the downstream outer wall 420 and bypasses the trailing edge 430 to enter the outlet duct 400 and form the counter-flow F-INV. Such recirculation zone R reduces the amount of counter-flow F-INV that can enter the outlet duct 400, thereby reducing the reverse thrust performance.

[0011] In another field, i.e. airships, it is known from patent US5516061 to provide a plurality of propellers mounted in a mast stay. Each propeller receives a torque from an engine mounted in the airship body. Such airship thus does not comprise turbojet engines, let alone bypass turbojet engines. To increase the amount of counter-flow in the propeller housing, it is known from figure 3 an outlet duct comprising radially distributed holes opened and angled along a cross section of the outlet duct located upstream of the trailing edge. In each hole, a shutter pivots between a closed position, in which it completely fills said hole, and an open position, in which it projects inwardly to open said hole. The open position enables the counter-flow to enter via the hole in addition to the trailing edge to improve the performance during the reverse thrust phase, while the closed position enables the performance during the thrust phase to be maintained. However, such shutters have a large volume and a heavy on-board mass.

[0012] In an alternative way, it is known from figure 5 of the same patent to add a secondary radial hole inside and upstream of the radial hole as previously described. A flap is pivotably mounted at the outer opening face of each secondary radial hole. This alternative solution has the same drawbacks as the previously described embodiment.

[0013] From figure 6 of the same patent Figure 7 and Figure 8It is also known to replace the flap with two cooperating half flaps rotatably mounted at the outer and inner opening faces of the hole. The outer half flap is mounted along the longitudinal axis, while the inner half flap is mounted along the tangential axis. However, such cooperating half flaps can have a poor sealing in the closed position and are more cumbersome and more difficult to handle than a simple flap.

[0014] In another field, in the field of aircraft propulsion assemblies with low bypass ratio, there are no vanes for guiding the secondary flow, and the primary and secondary flow channels are separated late. It is known from patent application GB 1360238 A to form a circumferential hole in the nacelle wall. Radially offset outer and inner doors close the circumferential hole in a complex and cumbersome manner. It is also known from patent application FR 2162257 A1 to form a through opening in the nacelle wall upstream of the secondary flow channel. This makes it possible to increase the flow of air flowing in the primary flow channel without affecting the performance of the reverse thrust phase.

[0015] The present invention therefore relates to an air outlet duct of a nacelle of an aircraft bypass turbojet engine, making it possible to increase the performance of the turbojet engine in the reverse thrust phase, without reducing the thrust performance. SUMMARY

[0016] The present invention relates to an air outlet duct of a nacelle of an aircraft bypass turbojet engine, the turbojet engine extending along a longitudinal axis and being provided with a radially inner primary flow channel and a radially outer secondary flow channel, in the thrust phase a secondary flow flowing from upstream to downstream in the radially outer secondary flow channel, in the reverse thrust phase a reverse flow flowing from downstream to upstream in the radially outer secondary flow channel, the nacelle extending circumferentially around the longitudinal axis of the turbojet engine and being provided with the air outlet duct at a downstream end thereof, the air outlet duct comprising a downstream inner wall and a downstream outer wall, the downstream inner wall facing the longitudinal axis and being configured to delimit an exterior of the secondary flow channel and to guide the secondary flow and the reverse flow, the downstream outer wall being opposite the downstream inner wall and being configured to guide an exterior flow flowing from upstream to downstream, the downstream inner wall and the downstream outer wall being connected together downstream through an aft edge.

[0017] The present invention is remarkable in that the air outlet duct comprises:

[0018] at least one radial through hole, the radial through hole being opened in a corner of the air outlet duct along a cross section upstream of the aft edge, the radial through hole being provided with an inner opening face formed in the downstream inner wall and an outer opening face formed in the downstream outer wall; and

[0019] a guide device corresponding to each radial through hole, each guide device comprising an inner mobile element and an outer mobile element mounted respectively at the inner opening face and at the outer opening face, the inner mobile element and the outer mobile element being movable between a closed position and an open position:

[0020] In the closed position, the inner mobile element closes the inner opening face in the extension of the downstream inner wall and the outer mobile element closes the outer opening face in the extension of the downstream outer wall, the radial through hole defining a closed cavity between the inner mobile element and the outer mobile element to maintain the performance of the thrust phase;

[0021] In the open position, the inner mobile element and the outer mobile element are both configured to allow the external flow to enter the radial through hole from the outer opening face and to flow towards the inner opening face to increase the reverse flow into the secondary flow channel to improve the performance of the reverse thrust phase.

[0022] The present invention, in the reverse thrust phase, the reverse flow enters the secondary flow channel at the trailing edge and at each radial through hole. The reverse flow into the secondary flow channel is thus increased, which is advantageous to improve the performance of the reverse thrust phase. In addition, each radial through hole generates a phenomenon of suction of the external flow at the outer opening face, i.e. a local overpressure, and a local underpressure at the inner opening face at the source of the resistance. In combination with the effect of the guide means, it is advantageous to press the external flow against the downstream outer wall, which increases the reverse flow into the secondary flow channel. In fact, the reverse flow entering not only at the trailing edge but also at each radial through hole has a significantly reduced backflow and twisting motion compared to the prior art. Each guide means and each radial through hole thus reduce the twisting motion of the external flow generated upstream by the variable-pitch fan.

[0023] Each guide means also has the advantage of being small in volume and light in weight on board compared to the prior art, each guide means comprising only one inner mobile element and one outer mobile element configured to, in the closed position, not fill the radial through hole but to close it respectively at the inner opening face and at the outer opening face so as to form a closed cavity. In addition, in the closed position, the inner mobile element and the outer mobile element extend respectively into the extension of the downstream inner wall and of the downstream outer wall, which makes it possible to maintain the profile of the outlet duct without changing it, thus maintaining the performance of the thrust phase.

[0024] According to one aspect of the invention, the outlet duct comprises a plurality of radial through holes distributed circumferentially on the outlet duct. Preferably, each radial through hole is located on the same cross section upstream of the trailing edge. Further preferably, each radial through hole is distributed circumferentially uniformly on the outlet duct. Advantageously, the distribution, the number and the size of the radial through holes are directly related to the desired effect of the reverse thrust phase and to its uniformity or, on the contrary, to its non-uniformity, more highlighted on certain defined corners.

[0025] According to a preferred aspect, the exhaust pipe includes at least ten guide devices, preferably at least thirty guide devices, and more preferably up to fifty guide devices, to allow sufficient reverse airflow to enter the secondary flow channel and efficiently correct the flow of the external airflow. In other words, the exhaust pipe includes at least ten radial through holes, preferably at least thirty, and more preferably up to fifty.

[0026] Preferably, each radial through-hole is axially located between the guide vane (known to those skilled in the art as an OGV) of the secondary flow passage of the turbojet engine and the trailing edge of the exhaust pipe of the nacelle. Preferably, the axial length of the through-hole is at most 90% of the axial length between the guide vane of the secondary flow passage and the trailing edge of the exhaust pipe. This allows sufficient reverse airflow to enter the secondary flow passage and efficiently corrects the flow of the external airflow.

[0027] According to one aspect of the invention, at least two radial through holes are spaced far apart from each other, preferably all radial through holes are spaced far apart from each other, and more preferably are spaced far apart uniformly. Advantageously, such an exhaust pipe has great mechanical strength in environments of vibration and turbulence. Furthermore, in the closed position, a closed cavity is formed between the inner moving member and the outer moving member, which ensures performance during the thrust phase.

[0028] According to a preferred aspect of the invention, the at least two radial through holes are adjacent, preferably all of the radial through holes are adjacent, and preferably the radial through holes together form an annular through hole. Advantageously, this structure optimizes the amount of reverse airflow entering and effectively reduces backflow at the trailing edge and reduces the torsional motion of the incoming reverse airflow, thus achieving optimal reverse thrust in the exhaust pipe.

[0029] According to a preferred aspect, at least the inner moving part and the outer moving part of the same guiding device have substantially the same shape and preferably substantially the same size, that is, the shape and size of the inner moving part differ from the shape and size of the outer moving part by at most 10%. Advantageously, the inner moving part and the outer moving part can be controlled in the same manner and thus in a simple and practical way. Preferably, the outer opening surface and the inner opening surface have adjacent portions.

[0030] Preferably, at least one inner moving member is flat and preferably in the form of a flap. Equally preferably, at least one outer moving member is flat and preferably in the form of a flap. Preferably, the radial thickness of the flap is less than one-third of the local radial thickness of the exhaust pipe, and more preferably less than one-quarter of the local radial thickness of the exhaust pipe. Advantageously, such inner and outer moving members have relatively small mass and volume.

[0031] According to the first aspect, the inner movable member slides on the downstream inner wall of the air outlet pipe. Preferably, the outer movable member slides on the downstream outer wall of the air outlet pipe. This sliding arrangement advantageously has a very small volume and does not interfere with the external airflow when in the open position.

[0032] Preferably, in the open position, the inner movable member of at least one guide device extends upstream of the inner opening surface, preferably extending to the outside of the downstream inner wall. Also preferably, in the open position, the outer movable member extends upstream of the outer opening surface, preferably extending to the inside of the downstream outer wall. Advantageously, this minimizes the volume. Considering that the actuating device is preferably located upstream of the vent pipe, it is advantageous for the movable member to be located upstream in the open position.

[0033] According to another aspect, the inner movable member of the at least one guide device is rotatably mounted about a rotation axis tangent to the air outlet pipe. Preferably, the outer movable member is rotatably mounted about a rotation axis tangent to the air outlet pipe. Advantageously, the inner and outer movable members allow the external airflow to be guided to the secondary flow channel while efficiently reducing the torsional motion of the external airflow.

[0034] According to one aspect, in the open position, the inner movable member protrudes inward relative to the longitudinal axis, and preferably, the axis of rotation is located downstream of the inner opening surface. Preferably, in the open position, the inner movable member protrudes relative to the closed position along an unfolding angle between 0° and 180°.

[0035] According to one aspect, the deployment angle is between 30° and 60° to optimally guide the external airflow in the secondary flow channel. Advantageously, the inner moving member allows the external airflow from the through-hole to be directed upstream, which improves reverse thrust performance. According to another aspect, the deployment angle is greater than 150° to minimize the volume in the secondary flow channel. The inner moving member protrudes only slightly into the secondary flow channel.

[0036] According to a preferred aspect, the outer movable member protrudes outward relative to the longitudinal axis, and preferably, the axis of rotation is located downstream of the outer opening surface. Preferably, in the open position, the outer movable member protrudes relative to the closed position along an unfolding angle between 0° and 180°.

[0037] According to one aspect, the spread angle is between 30° and 60° to optimally guide the external airflow in the radial through-hole. In practice, this arrangement of the outer moving member advantageously allows for a reduction in the external airflow in the through-hole, thereby increasing the flow rate within the through-hole. Therefore, the outer moving member allows the external airflow to be drawn into the radial through-hole. According to another aspect, the spread angle is greater than 150° to optimally press the external airflow against the downstream outer wall.

[0038] According to another aspect, in the open position, the inner movable member extends outward relative to the longitudinal axis into the radial through-hole, and is preferably mounted about a rotation axis located upstream of the inner opening surface. According to another preferred aspect, in the open position, the outer movable member extends inward relative to the longitudinal axis into the radial through-hole, and is preferably mounted about a rotation axis located upstream of the outer opening surface. The volume is therefore minimized, and the inner and outer movable members are located in the radial layer of the outlet pipe. Therefore, this rotation allows the flow of the external airflow at the downstream outer wall to be undisturbed. In the open position, the external airflow flows in the through-hole while passing around the inner and outer movable members.

[0039] Preferably, in the open position, the inner movable member is engaged with the outer movable member, preferably through the downstream ends of the inner and outer movable members, to form an aerodynamic upstream wall for guiding the external airflow within the radial through-hole. In the open position, the inner and outer movable members together form a guide for directing the airflow.

[0040] According to one aspect, at least the inner and outer moving parts of the same guide device are symmetrical about an axis of symmetry passing through the trailing edge and the center of the radial through-hole corresponding to the guide device, the center of which is defined relative to the radial axis of the longitudinal axis. Therefore, if the inner moving part is displaced by sliding, the outer moving part will also be displaced, and this cycle repeats. Similarly, if the inner moving part is rotated, the outer moving part will also move, and this cycle repeats. Furthermore, if the inner moving part moves inward, the outer moving part moves outward, and this cycle repeats. Finally, if the inner moving part moves upstream, the outer moving part also moves upstream, and this cycle repeats. This guide device can advantageously be controlled in a simple and practical manner, and allows similar aerodynamic behavior to be obtained on either side of the through-hole, which improves the flow of air.

[0041] According to another aspect, at least one guiding device includes at least one perforated member located in the radial through-hole corresponding to the guiding device. Preferably, the perforated member is in the form of a grille comprising multiple blades or alternatively in the form of a fin. Advantageously, such a perforated member helps to reduce the torsional motion of the reverse airflow and guide the reverse airflow during its entry into the secondary flow channel.

[0042] Preferably, the perforated member is located at the outer opening surface and / or the inner opening surface and / or the center of the radial through hole, so as to reduce the volume while effectively reducing the torsional motion of the incoming reverse airflow.

[0043] The present invention also relates to a nacelle for a bypass turbojet engine of an aircraft, the turbojet engine extending along a longitudinal axis and having a radially inner main flow channel and a radially outer secondary flow channel. During the thrust phase, the secondary airflow flows from upstream to downstream in the radially outer secondary flow channel, and during the reverse thrust phase, the reverse airflow flows from downstream to upstream in the radially outer secondary flow channel. The nacelle extends circumferentially around the longitudinal axis of the turbojet engine and has an exhaust pipe, as described above, at its downstream end.

[0044] The present invention also relates to an aircraft propulsion assembly including an aircraft bypass turbojet engine, the aircraft bypass turbojet engine having a radially inner main flow channel and a radially outer secondary flow channel. During the thrust phase, the secondary airflow flows from upstream to downstream in the radially outer secondary flow channel, and during the reverse thrust phase, the reverse airflow flows from downstream to upstream in the radially outer secondary flow channel. The propulsion assembly includes a nacelle mounted on the turbojet engine as described above. Preferably, the turbojet engine includes a variable-pitch fan. Also preferably, the turbojet engine has a bypass ratio greater than 16.

[0045] Advantageously, the exhaust manifold, as described above, can increase the reverse airflow entering the secondary flow channel and press the external airflow against the downstream outer wall to improve its entry, even for large-diameter exhaust manifolds. In the case of large-diameter exhaust manifolds, thrust reversal is advantageously achieved through a variable-pitch fan, which does not compromise the quality of the turbojet engine.

[0046] The present invention also relates to a method of using an aircraft propulsion assembly as described above, wherein the inner and outer moving parts of at least one guide device of the exhaust pipe are in a closed position during the thrust phase of the turbojet engine, the method comprising driving the inner and outer moving parts from the closed position to an open position during the reverse thrust phase of the turbojet engine.

[0047] The present invention also relates to a method of using an aircraft propulsion assembly as described above, wherein the inner and outer moving parts of at least one guide device of the exhaust pipe are in an open position during the reverse thrust phase of the turbojet engine, the method comprising driving the inner and outer moving parts from the open position to a closed position during the thrust phase of the turbojet engine.

[0048] Advantageously, this method allows for a simple, practical, and rapid adjustment of the exhaust pipe to achieve an aerodynamic profile during both the thrust and reverse thrust phases.

[0049] Preferably, the guiding device includes at least one driving member for driving the inner moving member to move and at least one driving member for driving the outer moving member to move from the closed position to the open position and preferably from the open position to the closed position.

[0050] Preferably, the same drive member is configured to move the inner and outer moving parts of the same guide device. More preferably, the same drive member is configured to move the inner and outer moving parts of each guide device, so as to control each guide device while reducing volume and weight. Attached Figure Description

[0051] The invention can be better understood by reading the following description given by way of example only, and by referring to the accompanying drawings given by way of non-limiting example, wherein the same reference numerals in the drawings are used to refer to similar objects, wherein:

[0052] Figure 1 This is a longitudinal schematic diagram of the propulsion components of an aircraft in the thrust phase using existing technology;

[0053] Figure 2A It is during the reverse thrust phase. Figure 1 A longitudinal schematic diagram of the propulsion components of a medium-sized aircraft;

[0054] Figure 2B It is during the reverse thrust phase. Figure 1 A schematic diagram of the longitudinal half-section of the nacelle of the propulsion assembly of a medium-sized aircraft;

[0055] Figure 3A This is a longitudinal schematic diagram of the aircraft propulsion assembly during the thrust phase according to an embodiment of the present invention;

[0056] Figure 3B yes Figure 3A A longitudinal half-section diagram of the exhaust pipe of the propulsion assembly of a medium-sized aircraft when the moving parts are in the closed position during the thrust phase.

[0057] Figure 4AThis is a longitudinal schematic diagram of the aircraft propulsion assembly in the reverse thrust phase according to the first embodiment of the present invention;

[0058] Figure 4B yes Figure 4A A longitudinal half-section view of the exhaust pipe of the propulsion assembly of a medium-sized aircraft when the moving parts are in the open position during the reverse thrust phase.

[0059] Figure 5A , Figure 5B and Figure 5C They are Figure 3A Schematic diagram of three alternative embodiments of the propulsion nacelle of a medium-sized aircraft during the thrust phase;

[0060] Figure 6 , Figure 7 and Figure 8 These are schematic diagrams of the longitudinal half-section of the exhaust pipe when the movable part is in the open position during the reverse thrust phase, representing the second, third, and fourth embodiments of the present invention, respectively.

[0061] Figure 9A and Figure 9B These are longitudinal half-section views of the air outlet pipe of the guide device including the perforated member in two alternative embodiments of the present invention during the reverse thrust phase.

[0062] It should be noted that the accompanying drawings illustrate the invention in detail for the purpose of implementing the invention, and the drawings can obviously better define the invention if necessary. Detailed Implementation

[0063] refer to Figure 3AAs previously described, it illustrates an aircraft propulsion assembly E comprising an aircraft bypass turbojet engine T extending along a longitudinal axis X and configured to propel the aircraft during the thrust phase P1 by accelerating an airflow (referred to as internal airflow F-INT) flowing from upstream to downstream in each turbojet engine T. Hereinafter, the terms "upstream" and "downstream" are defined relative to the flow direction of the internal airflow F-INT during the thrust phase P1. The turbojet engine T includes a fan 5 that rotates about the longitudinal axis X and is configured to accelerate the internal airflow F-INT during the thrust phase P1 of the turbojet engine. The turbojet engine T also has a radially inner main flow channel 6 and a radially outer secondary flow channel 7 located downstream of the fan 5, separated by a housing 8. The casing 8 is configured to guide a first portion (referred to as the main airflow F1) of the internal airflow F-INT in the main flow channel 6 for fuel combustion, and a second portion (referred to as the secondary airflow F2) of the internal airflow F-INT in the secondary flow channel 7 to generate thrust for the turbojet engine T. In the following text, the terms "inner" and "outer" are defined radially relative to the longitudinal axis X.

[0064] The turbojet engine T, as described below, is considered to have a high bypass ratio, meaning the ratio of the mass of the secondary airflow F2 to the mass of the primary airflow F1 is greater than 16, and fan 5 is a variable-pitch fan, abbreviated as VPF. For example... Figure 4A As shown, this fan 5 is configured to decelerate the aircraft during the reverse thrust phase P2, particularly during landing. For this purpose, the fan 5 includes blades with adjustable pitch angles, allowing the flow direction of the secondary airflow F2 in the secondary channel 7 to be reversed. During the reverse thrust phase P2, the reverse airflow F-INV therefore flows from downstream to upstream in the secondary channel 7, i.e., with... Figure 3A The secondary airflow F2 flows in the opposite direction. The reverse airflow F-INV then traverses the fan and is opposite to the upstream airflow F, especially radially outward, which allows for braking. In the same manner as thrust phase P1, the internal airflow F-INT from the upstream airflow F flows from upstream to downstream at the base of fan 5, i.e., radially inward, and opposite to the reverse airflow F-INV, to provide the main airflow F1. The main airflow F1 can also be provided by a portion of the reverse airflow F-INV that bypasses the housing 8.

[0065] refer to Figure 3A and Figure 4A The aircraft propulsion assembly E also includes a nacelle 2, which is mounted on the turbojet engine T and extends circumferentially around the longitudinal axis X of the turbojet engine T from the radially outer side of the fan 5, defining a secondary flow channel 7. Figure 3AAs shown, the turbojet engine T also includes guide vanes 20, referred to by those skilled in the art as exit guide vanes (OGVs), which extend radially into the secondary flow passage 7 of the casing 8 of the turbojet engine T. The nacelle 2 has an intake pipe 3 at its upstream end and an exhaust pipe 4 at its downstream end. The intake pipe 3 includes an upstream inner wall 31 facing the longitudinal axis X and an upstream outer wall 32 opposite to the upstream inner wall 31, the upstream inner wall 31 and the upstream outer wall 32 being connected upstream by an intake pipe 33 including a leading edge.

[0066] like Figure 3A As shown, in the thrust phase P1, the intake duct 3 has a circular aerodynamic profile, which allows the upstream airflow F to be separated into an internal airflow F-INT guided by the upstream inner wall 31 and an external airflow F-EXT guided by the upstream outer wall 32. In the reverse thrust phase P2, as... Figure 4A As shown, the upstream inner wall 31 of the intake duct 3 is configured to guide the reverse airflow F-INV, which successively crosses the secondary flow channel 7 and the fan 5, upstream, so that the reverse airflow F-INV is opposite to the upstream airflow F, thereby achieving braking. At the intake duct 3, the reverse airflow F-INV guided by the upstream inner wall 31 has a torsional motion V along the longitudinal axis X generated by the blades of the fan 5. This torsional motion V can be transmitted to the external airflow F-EXT, which is guided by the upstream outer wall 32 of the intake duct 3 and flows from upstream to downstream along the nacelle 2.

[0067] The present invention relates more specifically to the exhaust pipe 4 of the nacelle 2, in a manner similar to the intake pipe 3 and referenced to Figure 3B and Figure 4B The vent pipe 4 includes a downstream inner wall 41 facing the longitudinal axis X and a downstream outer wall 42 opposite to the downstream inner wall 41. The downstream inner wall 41 and the downstream outer wall 42 are connected together downstream by a trailing edge 43.

[0068] According to the present invention, still referencing Figure 3B and Figure 4B The exhaust pipe 4 also includes:

[0069] One or more radial through holes 44 are formed at the corner of the exhaust pipe 4 along a cross section located upstream of the trailing edge 43. Each radial through hole 44 has an inner opening surface 45 formed in the downstream inner wall 41 and an outer opening surface 46 formed in the downstream outer wall 42; and

[0070] Guide devices 1 are provided corresponding to each radial through hole 44. Each guide device 1 includes an inner movable member 10 and an outer movable member 11 respectively installed at the inner opening surface 45 and the outer opening surface 46. Both the inner and outer movable members can be... Figure 3B The closed position F shown is Figure 4B , Figure 6 ,Figure 7 and Figure 8 The movement is between the open position O shown, where the closed position F is suitable for the thrust phase P1 of the turbojet engine T, and the open position O is suitable for the reverse thrust phase P2.

[0071] refer to Figure 3B In the closed position F, the inner movable member 10 closes the inner opening surface 45 in the extension of the downstream inner wall 41, and the outer movable member 11 closes the outer opening surface 46 in the extension of the downstream outer wall 42. A radial through-hole 44 corresponding to the guide device 1 defines a closed cavity 47 located between the inner movable member 10 and the outer movable member. Furthermore, in the closed position F, the inner movable member 10 and the outer movable member 11 of the guide device 1 are radially aligned relative to the longitudinal axis X.

[0072] If in Figure 4B , Figure 6 , Figure 7 and Figure 8 In the next embodiment, in the open position O, both the inner movable member 10 and the outer movable member 11 are configured to allow external airflow F-EXT to enter the radial through-hole 44 from the outer opening face 46 and flow to the inner opening face 45 to re-enter the secondary flow channel 7. The radial direction of the through-hole 44 facilitates the entry of external airflow F-EXT.

[0073] In practice, each guide device 1 also includes a drive element (not shown) for moving the inner movable member 10 and the outer movable member 11 from the closed position F to the open position O or from the open position O to the closed position F. Preferably, the same drive element controls the inner movable member 10 and the outer movable member 11 of the same guide device 1. Preferably, all guide devices 1 are controlled by the same drive element to achieve simple and practical control. Preferably, the drive element is located upstream of the through hole, thus resulting in a smaller size and more free movement.

[0074] The exhaust pipe 4, including one or more radial through holes 44 with guide device 1, has an aerodynamic profile and is suitable for the thrust phase P1 and reverse thrust phase P2 of the turbojet engine T.

[0075] In fact, during the thrust phase P1, the inner moving part 10 and the outer moving part 11, in the closed position F, extend into the downstream inner wall 41 and the downstream outer wall 42 of the exhaust pipe 4, respectively. The exhaust pipe 4 thus retains the same aerodynamic profile as the prior art, allowing the downstream outer wall 42 to guide the external airflow F-EXT and the downstream inner wall 41 to guide the secondary airflow F2 from upstream to downstream in the secondary flow channel 7. The exhaust pipe 4 also retains substantially the same airborne mass as the prior art because each radial through-hole 44 is closed to form a closed cavity 47 and is not filled. In the closed position F, the inner moving part 10 and the outer moving part 11 do not extend into the through-holes 44. Therefore, the performance of the thrust phase P1 is advantageously preserved.

[0076] During the reverse thrust phase P2, the inner moving part 10 and the outer moving part 11, in the open position O, allow the reverse airflow F-INV to enter the secondary flow channel 7 both at the trailing edge 43 and at each radial through-hole 44. Therefore, the amount of reverse airflow F-INV entering the secondary flow channel 7 increases, thereby improving performance in the reverse thrust phase P2. The reverse airflow F-INV then flows from downstream to upstream to the fan 5, which imparts a torsional motion V to the reverse airflow F-INV. The reverse airflow F-INV then bypasses the intake pipe 3 to rejoin the external airflow F-EXT, while simultaneously transmitting its torsional motion V to the external airflow F-EXT. Advantageously, this torsional motion V is significantly reduced when transmitted to the reverse airflow F-INV entering at the trailing edge 43 and each radial through-hole 44. In effect, each radial through-hole 44 cooperates with each guide device 1 to guide the external airflow F-EXT, on the one hand by pressing it against the downstream outer wall 42, and on the other hand by reducing backflow in the secondary flow channel 7. Compared to existing technologies, this improves performance in the reverse thrust phase P2 by allowing a larger number of reverse airflows F-INV to enter in a generally longitudinal flow direction without backflow.

[0077] The structure and functional characteristics of the radial through-hole 44 of the vent pipe 4 will be described more precisely below.

[0078] refer to Figure 5A , Figure 5B and Figure 5C As previously mentioned, the exhaust pipe 4 includes one or more radial through holes 44A, 44B, and 44C, each of which is formed at the corner α of the exhaust pipe 4 along a cross-section located upstream of the trailing edge 43. In practice, the number, distribution, and size of the radial through holes 44A, 44B, and 44C depend on the effect of the reverse thrust phase P2 and the desired uniformity or non-uniformity characteristics. The following will describe three embodiments of the invention as non-limiting examples suitable for three different types of reverse thrust phases P2.

[0079] according to Figure 5AThe first embodiment of the invention shown includes an exhaust pipe 4 comprising ten radial through-holes 44A, 44B, and 44C located along the same cross-section and circumferentially and evenly spaced. This exhaust pipe 4 advantageously allows the reverse airflow F-INV to enter and be guided uniformly over the entire circumference of the exhaust pipe 4. The radial through-holes 44A, 44B, and 44C are also spaced apart from each other to increase the mechanical strength of the exhaust pipe 4 in vibration and turbulent environments.

[0080] according to Figure 5B In the second embodiment of the invention shown, the exhaust pipe 4 includes twelve radial through holes 44A, 44B, 44C that are adjacent to each other and together form a whole annular through hole 48 extending about the longitudinal axis X. This annular through hole 48 advantageously has optimal performance and is suitable for a uniform reverse thrust phase P2, especially for turbojet engines T with a bypass ratio greater than 16.

[0081] according to Figure 5C In the third embodiment of the invention shown, the exhaust pipe 4 includes only two adjacent radial through holes 44A and 44B located on the circumferential setting portion of the exhaust pipe. By locally improving the performance at the setting portion of the exhaust pipe 4 with radial through holes 44A and 44B, this type of exhaust pipe 4 is suitable for the non-uniform reverse thrust phase P2.

[0082] It should be noted that, needless to say, the number of radial through holes 44A, 44B, and 44C can be the same as... Figure 5A , Figure 5B and Figure 5C The number of radial through holes varies. In an example of an aircraft bypass turbojet engine T with a bypass ratio greater than 16, the exhaust pipe 4 preferably includes at least ten radial through holes 44A, 44B, 44C, more preferably at least thirty, and at most fifty radial through holes 44A, 44B, 44C, in order to efficiently increase the amount of incoming reverse airflow F-INV and efficiently straighten it in a generally longitudinal direction.

[0083] Similarly, in the example of an aircraft bypass turbojet engine T with a bypass ratio greater than 16, radial through-holes 44A, 44B, and 44C are axially located between the guide vane 20 and the trailing edge 43 of the exhaust pipe 4. Preferably, the radial through-holes 44A, 44B, and 44C are located between the guide vanes 20, preferably in a plane transverse to the longitudinal axis X. Preferably, the axial length of the radial through-holes 44A, 44B, and 44C is at most 90% of the axial length between the axial position of the guide vane 20 and the axial position of the trailing edge 43. Furthermore, the radial through-holes 44A, 44B, and 44C preferably have a downstream end, which is longitudinally away from the trailing edge 43, and the distance between the downstream end and the trailing edge 43 is at least 10% of the longitudinal length between the axial position of the guide vane 20 and the axial position of the edge 43.

[0084] Preferably, the radial through holes 44A, 44B, and 44C have a longitudinal length L that is approximately equal to the longitudinal length of the guide vane 20, that is, the longitudinal length L of the radial through holes 44A, 44B, and 44C differs from the longitudinal length of the guide vane 20 by at most 10%.

[0085] In summary, the exhaust pipe 4 includes one or more radial through-holes 44A, 44B, and 44C, which on the one hand improves the performance during the reverse thrust phase P2 and allows the reverse airflow F-INV to enter the secondary flow channel 7 as a supplement to the trailing edge 43; on the other hand, it helps to press the external airflow F-EXT against the downstream outer wall 42 to reduce backflow. When a uniform and comprehensive improvement in performance is required during the reverse thrust phase P2, the radial through-holes 44A, 44B, and 44C are evenly distributed circumferentially in the exhaust pipe 4. In particular, the radial through-holes 44A, 44B, and 44C are spaced far apart from each other to obtain better mechanical strength. Figure 5A ) or together form an annular through-hole 48 to achieve optimal performance ( Figure 5B For the localized and non-uniform improvement of the reverse thrust phase P2, radial through-holes 44A and 44B are located, conversely, in one or more designated portions of the outlet pipe 4 circumferentially ( Figure 5C ).

[0086] Still referencing Figure 5A , Figure 5B and Figure 5CAs previously mentioned, each radial through-hole 44A, 44B, 44C is respectively provided with guide devices 1A, 1B, 1C. These guide devices 1A, 1B, 1C are configured to close the inner opening surface 45 and outer opening surface 46 of the radial through-holes 44A, 44B, 44C during the thrust phase P1, and guide the external airflow E-EXT during the reverse thrust phase P2, specifically causing the external airflow E-EXT to flow within the radial through-holes 44A, 44B, 44C and press against the downstream outer wall 42. In other words, the exhaust pipe 4 includes the same number, size, and distribution of guide devices 1A, 1B, 1C as the radial through-holes 44A, 44B, 44C. Each radial through-hole 44A, 44B, 44C cooperates with each guide device 1A, 1B, 1C to improve the performance of the reverse thrust phase P2.

[0087] It should be noted, in particular, that each guide device 1A, 1B, 1C is located at a specific corner α, which corresponds to each radial through hole 44A, 44B, 44C. Figure 5A In the example, guide devices 1A, 1B, and 1C are far apart from each other, while Figure 5B In the example, guide devices 1A, 1B, and 1C are adjacent to each other.

[0088] The following section will consider a single radial through-hole 44 and will describe more precisely the structural and functional characteristics of the associated guiding device.

[0089] refer to Figure 3B and Figure 4B As previously described, the guide device 1 includes a single inner movable member 10 and a single outer movable member 11, which move to closed positions F at the inner opening surface 45 and the outer opening surface 46 of the radial through hole 44, respectively. Figure 3B The inner movable member 10 and the outer movable member 11 are mounted on the radial through hole 44. Therefore, only one inner movable member 10 and one outer movable member 11 are mounted on the corner α, where the radial through hole 44 is opened.

[0090] like Figure 3B and Figure 4BAs shown, the inner movable member 10 and the outer movable member 11 are preferably each in the form of a single flap, with a thickness similar to that of the downstream inner wall 41 and the downstream outer wall 42. This flap has the advantages of small size and light onboard weight, allowing it to close the inner opening 45 and the outer opening 46 without filling the radial through-hole 44. This flap also ensures a seal in the closed position F. It goes without saying that the inner movable member 10 and the outer movable member 11 can have another shape, which must close and not fill the radial through-hole 44, and be in the form of a single component to reduce volume and weight. In particular, preferably, the radial thickness of the inner movable member 10 and the outer movable member 11 is less than one-third of the local radial thickness of the exhaust pipe 4, and preferably less than one-quarter of the local radial thickness of the exhaust pipe 4. Furthermore, preferably, the inner movable member 10 and the outer movable member 11 have the same shape and / or size for ease of control, i.e., the shape and size of the inner movable member 10 and the outer movable member 11 differ by at most 10%.

[0091] refer to Figure 4B , Figure 6 , Figure 7 and Figure 8 The inner movable member 10 and the outer movable member 11 are respectively movably mounted at the inner opening surface 45 and the outer opening surface 46, especially by rotation (as will be described below). Figure 4B , Figure 6 and Figure 7 ) or by sliding ( Figure 8 )Install.

[0092] In illustrating the first embodiment of the present invention Figure 4B In the middle, the inner moving part 10 and the outer moving part 11 are in Figure 3B The device rotates between the closed position F and the open position O. More specifically, the inner movable member 10 and the outer movable member 11 are located downstream of the inner opening surface 45 and the outer opening surface 46, respectively, and rotate about a rotation axis Y tangent to the vent pipe 4. The inner movable member 10 is configured to rotate inward, and the outer movable member 11 is configured to rotate outward in a manner symmetrical with respect to the inner movable member 10 along an axis of symmetry X1 passing through the rear edge 43 and the center of the radial through-hole 44. In other words, in the open position O, as shown... Figure 4B As shown, the inner movable member 10 extends into the secondary flow channel 7, while the outer movable member 11 extends relative to the longitudinal axis X to the outside of the outlet pipe 4. Figure 4BIn the example, in the open position, the inner movable member 10 and the outer movable member 11 protrude relative to the closed position F along expansion angles γ10 and γ11, respectively, between 30° and 60°. As detailed here and below, the expansion angle γ10 is defined as the angle separating the inner opening surface 45 from the inner movable member 10, and the expansion angle γ11 is the angle separating the outer opening surface 46 from the outer movable member 11. These expansion angles γ10 and γ11 enable the guide device 1 to efficiently guide the external airflow F-EXT in the radial through-hole 44 and then in the secondary flow channel 7. Therefore, the reverse airflow F-INV enters in a generally longitudinal direction, eliminating backflow in the secondary flow channel 7.

[0093] The outer moving part 11 advantageously achieves the suction function by drawing out a portion of the external airflow L-EXT and injecting it into the radial through-hole 44. In itself, the inner moving part 10 enables the airflow flowing in the radial through-hole 44 to be directed upstream of the secondary flow channel 7, which achieves efficient reverse thrust.

[0094] In illustrating the second embodiment of the present invention Figure 6 In the example, in the open position O, the expansion angles γ10' and γ11' of the inner movable member 10 and the outer movable member 11 along their extensions are greater than 150°. Preferably, the expansion angles γ10' and γ11' are close to 180°, such that in the open position, the inner movable member 10 and the outer movable member 11 abut against the downstream inner wall 41 and the downstream outer wall 42, respectively. These expansion angles γ10' and γ11' have the advantage of efficiently pressing the external airflow L-EXT against the downstream outer wall 42, so that the external airflow F-EXT does not have to bypass the outer movable member 11.

[0095] It should be noted that, Figure 4B and Figure 6 In the two embodiments shown, the unfolding angles γ10, γ11, γ10', and γ11' of the inner moving parts 10 reduce the diameter of the resulting trachea 4. In practice, to ensure that all inner moving parts 10 can move in the open position O without interfering with each other, the radial through holes 44 are preferably spaced apart from each other, such as... Figure 5A As shown in the example. In a complementary or alternative manner, the inner opening surface 45 of the radial through hole 44 and the inner moving member 10 have suitable shapes, for example, opened at the downstream end of the reduced corner α.

[0096] It should also be noted that, Figure 4B and Figure 6In the two embodiments shown, the deployment angles γ10 and γ10' of the inner movable member 10 may differ from the deployment angles γ11 and γ11' of the outer movable member 11. As an example, the deployment angles γ11 and γ11' of the outer movable member 11 may be greater than the deployment angles γ10 and γ10' of the inner movable member 10 to achieve maximum capture of the external airflow F-EXT at the radial through-hole 44 without significantly reducing the capture of the external airflow at the trailing edge 43.

[0097] In illustrating the third embodiment of the present invention Figure 7 In this configuration, the rotation axis Y' of the inner movable member 10 and the rotation axis Y' of the outer movable member 11 are located upstream of the inner opening surface α and the outer opening surface 46, respectively, and the rotation axis Y' remains tangent to the vent pipe 4. The inner movable member 10 is configured to rotate outward, while the outer movable member 11 is configured to rotate inward in a manner symmetrical with respect to the inner movable member 10 along a symmetry axis X1 passing through the rear edge 43 and the center of the radial through hole 44. In other words, in the open position O, as... Figure 7 As shown, both the inner movable member 10 and the outer movable member 11 extend within the radial through hole 44. Preferably, as Figure 7 As shown, in the open position O, the inner moving member 10 is engaged with the outer moving member 11, particularly at their downstream ends. Advantageously, the guide device 1 has a minimal volume in the open position O. Therefore, the external airflow F-EXT can flow in the radial through-hole 44, simultaneously guided by the inner moving member 10 and the outer moving member 11, reversing the flow direction of the external airflow F-EXT so that it is guided upstream in the secondary flow channel 7, achieving efficient thrust reversal. Advantageously, the reverse airflow F-INV does not need to bypass the outer moving member 11 during the reverse thrust phase.

[0098] The fourth embodiment of the present invention is shown Figure 8 In the example, the inner movable member 10 and the outer movable member 11 are respectively mounted on the downstream inner wall 41 and the downstream outer wall 42, and slide between the closed position F and the open position O. Preferably, as shown... Figure 8 As shown, the inner movable member 10 is slidably mounted inside the downstream outer wall 41, while the outer movable member 11 is slidably mounted outside the downstream inner wall 42 in a manner symmetrical about the axis of symmetry X1. Also preferably, as... Figure 8 As shown, the inner movable member 10 and the outer movable member 11 are slidably mounted upstream. Furthermore, in Figure 8 In the example, in the open position O, the inner and outer moving parts 11 extend to two housings 49, which are formed at the downstream inner wall 41 and the downstream outer wall 42, respectively. Advantageously, the guide device 1 has a minimal volume in the open position O. This also allows for efficient pressing of the external airflow F-EXT against the downstream outer wall 42. Advantageously, the reverse airflow F-INV does not need to bypass the outer moving part 11 during the reverse thrust phase.

[0099] In the four embodiments of the invention described above, the inner moving parts 10 and the outer moving parts 11 are symmetrically mounted about the axis of symmetry X1 for ease of control, and in practice, controlled by a single drive (not shown). Preferably, all the inner moving parts 10 and all the outer moving parts 11 of the exhaust pipe 4 are mounted in the same manner for ease of control, and in practice, controlled by the same drive.

[0100] However, it goes without saying that the inner movable member 10 and the outer movable member of the same guide device 1 can be installed in different ways, especially to integrate the advantages of the two installation methods. As an example, the inner movable member 10 is rotatably mounted relative to the longitudinal axis X and protrudes inward to efficiently guide the reverse airflow F-INV in the secondary flow channel 7, while the outer movable member 11 is slidably mounted to reduce volume and facilitate pressing the external airflow F-EXT against the downstream outer wall 42. Generally, the inner movable member 10 and the outer movable member 11 can each be installed according to any embodiment described in the present invention.

[0101] It should be noted that the embodiments of the present invention described above are given by way of example only and are not restrictive. In particular, the deployment angles γ10, γ11, γ10', and γ11' can be selected differently depending on the desired amount of the incoming reverse airflow F-INV. This sliding can also occur downstream, especially when the guide device 1 is integrated into the outlet pipe 4.

[0102] according to Figure 9A and Figure 9B In the alternative embodiment of the invention shown, in addition to the inner moving member 10 and the outer moving member 11, the guide device 1 further includes one or more perforated members 12. Each perforated member 12 is located within the radial through-hole 44 to allow the external airflow F-EXT to traverse during the reverse thrust phase P2, and is configured to reduce the torsional motion V in the external airflow F-EXT entering the secondary flow channel 7. Figure 4B The perforated member 12 can also guide the reverse airflow F-INV to flow in a generally longitudinal direction within the secondary channel 7. Preferably, the perforated member 12 is in the form of a grille or fin, which advantageously allows the reverse airflow F-INV to be guided in a generally longitudinal direction within the secondary channel 7. Figure 9A In the example, the guide device 1 includes a single perforated member 12 extending longitudinally to the center of the radial through-hole 44. Figure 9B In the example, the guide device 1 includes two perforated members 12 extending longitudinally at the inner opening face 45 and the outer opening face 46.

[0103] In practice, the selection of the number and location of the perforated members 12 depends on the installation of the inner movable member 10 and the outer movable member 11, as this installation will create integration limitations. The perforated members 12 are already arranged according to...Figure 4B The first embodiment is described in the example of a rotatably mounted inner movable member 10 and outer movable member 11. In this example, one or more perforated members 12 can be mounted in the radial through hole 44 without integration restrictions. If considered... Figure 7 The third embodiment of the present invention shown, such as Figure 9A In the example, the perforated member 12 positioned therein cannot effectively move the inner movable member 10 and the outer movable member 11. Therefore, such as Figure 9B As shown, the perforated member 12 is preferably positioned at the inner opening face 45 and / or the outer opening face 46. Still in this example, preferably, the inner movable member 10 and the outer movable member 11 include perforated member imprints so that they can be nested with the perforated member 12 in the closed position F.

[0104] In summary, the inner movable member 10 and the outer movable member 11 are movably mounted by rotating or sliding according to the desired performance in the reverse thrust phase P2 and the integrated constraints in the exhaust pipe 4. Preferably, the inner movable member 10 and the outer movable member 11 are symmetrically mounted about the axis of symmetry X1 to facilitate the control of the drive component. One or more perforated members are located within the radial through-hole 44 to enhance the guiding effect of the guide device 1 on the external airflow F-EXT.

[0105] The following describes a method of using the aircraft propulsion assembly E as described above, wherein the exhaust pipe 4 of the aircraft propulsion assembly includes a radial through-hole 44 and a guide device 1 corresponding to the radial through-hole. By default, the turbojet engine T is initially in the thrust phase P1, and the inner moving part 10 and the outer moving part 11 of the guide device 1 are in the closed position F.

[0106] During the reverse thrust phase P2 of the turbojet engine T, the blade spacing angle of the fan 5 is modified so that the direction of the secondary airflow F2 flowing in the secondary channel 7 is reversed in the reverse airflow F-INV, thereby facilitating aircraft deceleration. According to the invention, in parallel with modifying the blade spacing angle of the fan 5, the inner movable member 10 and outer movable member 11 of each guide device 1 are rotated or slidably moved to the open position O by means of one or more drive members.

[0107] Preferably, the inner moving part 10 and the outer moving part 11 are identical and move symmetrically relative to the axis of symmetry X1, thereby enabling simple and practical movement via a single drive. Preferably, all the inner moving parts 10 and the outer moving parts 11 of the exhaust pipe 4 are identical and driven by a single drive to reduce the volume of the guide device 1. In the case of rotation, the drive can be in the form of a seesaw or wheels, advantageously allowing for simple, rapid, and synchronous rotation of all the inner moving parts 10 and all the outer moving parts 11 along the same unfolding angles γ10, γ11, γ10', γ11'. In the case of sliding, the drive can be in the form of one or more actuators, such as hydraulic or pneumatic jacks connected together with the same advantages.

[0108] Alternatively, depending on the upstream airflow F and the desired thrust reversal, only certain inner moving parts 10 and outer moving parts 11 of the guide device 1 can move in the open position O, especially in Figure 5A and Figure 5B In the example of the illustrated embodiment, the inner movable member 10 and the outer movable member 11 of the guide device 1 can be driven to move at different deployment angles γ10, γ10', γ11, and γ11' by a drive member for driving the inner movable member 10 and a drive member for driving the outer movable member 11. According to a preferred aspect, the inner movable member 10 and the outer movable member 11 of the guide device 1 are actuated independently so that they can move along different deployment angles, thereby achieving greater degrees of freedom.

[0109] In the new thrust phase P1 of the turbojet engine T, the blade spacing angle of the fan 5 is modified again to re-establish the secondary airflow F2 flowing from upstream to downstream. According to the invention, in parallel with modifying the blade spacing angle of the fan 5, the inner moving member 10 and the outer moving member 11 move from the open position O to the closed position F in opposite directions. Advantageously, the exhaust pipe 4 thus has an aerodynamic profile in both the thrust phase P1 and the reverse thrust phase P2. Furthermore, the process of moving the inner moving member 10 and the outer moving member 11 from the closed position F to the open position O and from the open position O to the closed position F is simple and quick to implement and can be repeated as needed.

Claims

1. An aircraft propulsion assembly (E) comprising an aircraft bypass turbojet engine (T), the turbojet engine (T) having a radially inner main flow channel (6) and a radially outer secondary flow channel (7), wherein during the thrust phase (P1), a secondary airflow (E2) flows from upstream to downstream in the radially outer secondary flow channel (7), and during the reverse thrust phase (P2), a reverse airflow (F-INV) flows from downstream to upstream in the radially outer secondary flow channel (7), the propulsion assembly (E) comprising a nacelle (2) mounted on the turbojet engine (T) and extending circumferentially about the longitudinal axis (X) of the turbojet engine (T), the turbojet engine (T) comprising a plurality of radially extending... Guide vanes (20) in the secondary flow channel (7), the nacelle (2) having an exhaust pipe (4) at its downstream end, the exhaust pipe (4) including a downstream inner wall (41) and a downstream outer wall (42), the downstream inner wall (41) facing the longitudinal axis (X) and configured to define the outside of the secondary flow channel (7) and guide the secondary airflow (F2) and the reverse airflow (F-INV), the downstream outer wall (42) opposite to the downstream inner wall (41) and configured to guide the external airflow (F-EXT) flowing from upstream to downstream, the downstream inner wall (41) and the downstream outer wall (42) being connected together downstream by a trailing edge (43), characterized in that, The turbojet engine (T) includes a variable-pitch fan (5); the exhaust pipe (4) includes: Multiple radial through holes (44, 44A, 44B, 44C) are distributed circumferentially on the exhaust pipe (4). Each radial through hole (44, 44A, 44B, 44C) is opened at the corner (α) of the exhaust pipe (4) along a cross section located upstream of the trailing edge (43). Each radial through hole (44, 44A, 44B, 44C) has an inner opening surface (45) formed in the downstream inner wall (41) and an outer opening surface (46) formed in the downstream outer wall (42). Each radial through hole (44, 44A, 44B, 44C) is axially located between the guide vane (20) and the trailing edge (43). Guide devices (1, 1A, 1B, 1C) are provided one-to-one with each radial through hole (44, 44A, 44B, 44C). Each guide device (1, 1A, 1B, 1C) includes an inner movable member (10, 10A, 10B, 10C) and an outer movable member (11, 11A, 11B, 11C) respectively installed at the inner opening surface (45) and the outer opening surface (46). The inner movable member (10, 10A, 10B, 10C) and the outer movable member (11, 11A, 11B, 11C) both move between the closed position (F) and the open position (O). In the closed position (F), the inner moving parts (10, 10A, 10B, 10C) close the inner opening surface (45) in the extension of the downstream inner wall (41), the outer moving parts (11, 11A, 11B, 11C) close the outer opening surface (46) in the extension of the downstream outer wall (42), and the radial through holes (44, 44A, 44B, 44C) define a closed cavity (47) between the inner moving parts (10, 10A, 10B, 10C) and the outer moving parts (11, 11A, 11B, 11C) to maintain the performance of the thrust phase (P1); In the open position (O), both the inner movable members (10, 10A, 10B, 10C) and the outer movable members (11, 11A, 11B, 11C) are configured to allow the external airflow (F-EXT) to enter the radial through-holes (44, 44A, 44B, 44C) from the outer opening face (46) and flow to the inner opening face (45) to increase the reverse airflow (F-INV) entering the secondary flow channel (7) to improve the performance of the reverse thrust stage (P2); The inner movable part (10, 10A, 10B, 10C) of at least one guide device (1, 1A, 1B, 1C) is rotatably mounted about a rotation axis (Y, Y') tangential to the vent pipe (4); in the open position (O), the inner movable part (10, 10A, 10B, 10C) extends outward relative to the longitudinal axis (X) into the radial through hole (44, 44A, 44B, 44C).

2. The aircraft propulsion assembly (E) as claimed in claim 1, characterized in that, Each radial through hole (44, 44A, 44B, 44C) is located on the same cross section upstream of the trailing edge (43) and is distributed circumferentially on the vent pipe (4).

3. The aircraft propulsion assembly (E) as claimed in claim 1, characterized in that, At least the inner moving parts (10, 10A, 10B, 10C) and the outer moving parts (11, 11A, 11B, 11C) of the same guide device (1, 1A, 1B, 1C) are symmetrical about an axis of symmetry (X1), which passes through the rear edge (43) and the center of the radial through hole (44, 44A, 44B, 44C) corresponding to the guide device (1, 1A, 1B, 1C).

4. The aircraft propulsion assembly (E) as claimed in claim 1, characterized in that, The guide device (1, 1A, 1B, 1C) includes at least one perforated member (12) located in the radial through hole (44, 44A, 44B, 44C) corresponding to the guide device (1, 1A, 1B, 1C).

5. The aircraft propulsion assembly (E) as claimed in claim 1, characterized in that, At least one guide device (1, 1A, 1B, 1C) further includes a drive for moving the inner movable member ((10, 10A, 10B, 10C)) and the outer movable member (11, 11A, 11B, 11C) between a closed position (F) and an open position (O), the drive being located upstream of the radial through hole (44, 44A, 44B, 44C).

6. A method of using an aircraft propulsion assembly (E) as claimed in any one of claims 1-5, characterized in that, The inner moving part (10, 10A, 10B, 10C) and the outer moving part (11, 11A, 11B, 11C) of at least one guide device (1, 1A, 1B, 1C) of the exhaust pipe (4) are in the closed position (F) during the thrust phase (P1) of the turbojet engine (T), the method comprising driving the inner moving part (10, 10A, 10B, 10C) and the outer moving part (11, 11A, 11B, 11C) from the closed position to the open position (O) during the reverse thrust phase (P2) of the turbojet engine (T).

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