WO2019234371A1

WO2019234371A1 - Propulsion assembly for a vertikal take-off and landing aircraft

Info

Publication number: WO2019234371A1
Application number: PCT/FR2019/051384
Authority: WO
Inventors: Jérôme Didier MORA
Original assignee: Safran
Priority date: 2018-06-07
Filing date: 2019-06-07
Publication date: 2019-12-12
Also published as: FR3082186A1; FR3082186B1

Abstract

The invention relates to a propulsion assembly (1) for a vertical take-off and landing aircraft, comprising a propeller (2) capable of being driven in rotation about an axis (X) by a motor (3), and a fairing (5, 9) surrounding said propeller (2), characterized in that said assembly (1) comprises at least one mobile part (9) capable of modifying the axial distance (d) between the propeller (2) and the downstream end of the fairing (5, 9).

Description

PROPULSION ASSEMBLY FOR A TAKE-OFF AIRCRAFT AND

VERTICAL LANDING

FIELD

[001] The present invention relates to a propulsion assembly for a vertical takeoff and landing aircraft.

CONTEXT

[002] The vertical takeoff and landing aircraft, whose acronym is VTOL (for Vertical Take Off and Landing), can be classified into several categories, depending on the propulsive means used for the vertical displacement phases, such as take-off or landing, and horizontal advance phases.

[003] A first category concerns aircraft comprising only so-called vertical propulsion units, generally identical, used for both the vertical phases and the advance phases. A vertical propulsion assembly conventionally comprises a propeller whose axis of rotation is oriented vertically. Such an architecture has a low complexity but limits the speed of advance of the vehicle. EP 2 234 883 discloses an aircraft belonging to this category.

[004] A second category concerns aircraft comprising one or more vertical propulsion units used for the vertical phases and one or more additional fixed propulsion units used for the advance phases. Such an architecture is a compromise that meets both the needs of low complexity and significant advance speed. EP 0 539 464 discloses an aircraft belonging to this category.

[005] A third category concerns aircraft comprising only mobile propulsion units. Sets of Mobile propulsion can be oriented vertically or horizontally depending on the flight phase. Such an architecture makes it possible to obtain a high speed of advance at the cost of a great complexity. EP 3 296 202 discloses an aircraft belonging to this category.

[006] A fourth category concerns aircraft comprising one or more vertical propulsion units, used for the vertical phases, and one or more additional mobile propulsion units, the orientation of which may be modified as a function of the flight phases (phase vertical or advance phase). Mobile assemblies then provide additional lift during vertical phases, and provide propulsion during horizontal advance phases. The document FR 2 997 924 discloses an aircraft belonging to this category.

[007] For aircraft belonging to the second and fourth categories, it is interesting to streamline the rotors of the vertical propulsion units in order to increase their efficiency.

[008] The efficiency is all the more important that the height of the fairing, that is to say its dimension along the axis of rotation of the rotor, is important. However, a large height of the fairing generates a high aerodynamic resistance during the advance phases, which is detrimental to performance.

[009] There is currently a need to be able to benefit from increased efficiency in the vertical phases while limiting the aerodynamic resistance of the propulsion assembly during the advance phases.

SUMMARY OF THE INVENTION [010] The invention aims to meet this need in a simple, reliable and inexpensive way.

[011] For this purpose, the invention relates to a propulsion assembly for a vertical take-off and landing aircraft, comprising a propeller adapted to be rotated about an axis by an engine, and a fairing. surrounding said propeller, characterized in that said assembly comprises at least one movable part able to modify the axial distance between the propeller and the downstream end of the shroud.

[012] In this way, it is possible to deploy the propulsion assembly, that is to say to increase its axial dimension, in a case of operation corresponding for example to a vertical takeoff or landing of the aircraft, so as to maximize the efficiency of the propeller due to the presence of a fairing of large axial dimension. Furthermore, it is possible to retract the propulsion assembly, that is to say to reduce its axial dimension, in a case of operation corresponding for example to a displacement or horizontal flight of the aircraft, so as to reduce the aerodynamic resistance generated by the propulsion unit.

[013] In general, in the deployed position, the invention allows in particular to increase the axial distance between the propeller and the downstream end of the fairing. The terms upstream and downstream are defined with respect to the direction of flow of the air flow through the assembly, and in particular the propeller.

[014] The increase in the aforementioned axial distance can be obtained by increasing the axial dimension of the fairing downstream of the propeller and / or moving the propeller to the upstream end of the fairing.

[015] The at least one movable portion may comprise part of the fairing.

[016] Said mobile part of the fairing can be movable relative to a fixed part of the fairing.

[017] Said mobile part of the fairing may comprise noise attenuation means comprising, for example, a multi-perforated skin and a core with a cellular or porous structure.

[018] The movable portion of the fairing may comprise a frustoconical portion movable between a retracted position and an extended position wherein said frustoconical portion is adapted to form a divergent diffuser at the downstream end of the fairing. [019] The movable portion of the fairing may comprise a cylindrical portion movable between a retracted position and an extended position in which said cylindrical portion extends the downstream end of the fairing.

[020] The at least one movable portion may comprise a movable support on which are mounted the motor and the propeller, said support being able to be moved relative to at least one fixed part of the fairing.

[021] The fairing may comprise an air inlet at the upstream end of the shroud, the support having a closing portion adapted to close the air inlet in a retracted position of the support, said shutter portion being spaced from the air inlet in an extended position of the support.

[022] The fairing may comprise an air inlet at the upstream end of the fairing, the assembly comprising a movable shutter member adapted to close the air inlet in a retracted position of the shutter member , the shutter member being spaced from the air inlet in an extended position of said member.

[023] The movable support or the shutter member may comprise at least one baffle adapted to redirect an incoming air flow oriented perpendicularly to the axis of the helix in a flow of air oriented along the axis of the propeller.

[024] The movable part or the movable support may be able to be moved along the axis of the helix.

[025] The movable part and the closure member may be able to be moved simultaneously, for example along the axis of the helix.

[026] In such a case, the same actuator can ensure their simultaneous movement.

[027] The invention also relates to an aircraft, characterized in that it comprises at least one set of the aforementioned type, the axis of the propeller being oriented vertically.

[028] The invention will be better understood and other details, features and advantages of the invention will become apparent on reading the following description given by way of non-limiting example with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE FIGURES FIGS. 1 and 2 are views in axial section of a propulsion assembly according to a first embodiment, respectively in the retracted position and in the deployed position of the mobile part and the closure member;

Figures 3 and 4 are views in axial section of a propulsion assembly according to a second embodiment, respectively in the retracted position and in the deployed position of the support on which are mounted the motor and the propeller;

- Figures 5 and 6 are views in axial section of a propulsion assembly according to a third embodiment, respectively in the retracted position and in the deployed position of a movable part of the fairing forming a diffuser.

DETAILED DESCRIPTION

[029] Figures 1 and 2 show a set of propulsion 1 for a vertical takeoff and landing aircraft, according to a first embodiment of the invention.

[030] The propulsion unit 1 comprises a propeller 2 adapted to be rotated about an axis X by a motor 3. The motor 3 comprises a stator 4 fixed on a support (not shown), itself secured. a fixed part 5 of a fairing. The motor 3 further comprises a rotor integral in rotation with the propeller 2.

[031] The fixed portion 5 of the fairing has upstream ends 6 and downstream 7 open. The terms upstream and downstream are defined relative to the direction of flow of the air flow within the propulsion assembly 1, oriented along the X axis from top to bottom in the figures. The propeller 2 may extend generally in a radial plane situated axially upstream of the engine 3, as illustrated in FIGS. 1 and 2. As a variant, the helix 2 may extend generally in a radial plane situated axially downstream of the engine 3.

[032] The fixed part 5 of the fairing is cylindrical and surrounds the propeller 2 with minimum operating clearance. The fixed part 5 of the fairing may comprise radial fastening flanges 8, or areas of fairing continuity, at its upstream and downstream ends.

[033] The fairing further comprises a movable portion 9, located at the downstream end 7 of the fixed portion 5. In the embodiment shown here, the movable portion 9 is located radially outside the portion fixed 5. The movable part 9 and / or the fixed part 5 may comprise an acoustic treatment. In particular, the mobile part 9 and / or the fixed part 5 may comprise a multi-perforated skin 10 and a core 11 with a cellular or porous structure (FIG. 2).

[034] The movable part 9 can be moved by an actuator, such as for example a motor or a jack (not shown). The mobile part 9 can be displaced in translation along the X axis, between a retracted or retracted position, illustrated in FIG. 1, and an extended position, illustrated in FIG. 2. In its retracted position, the downstream end 12 of the movable portion 9 is located axially facing the downstream end 7 of the fixed part 5 of the fairing. In its deployed position, the downstream end 12 of the movable part 9 is situated axially downstream of the downstream end 7 of the fixed part 5 of the fairing, so as to increase the length of the fairing, in particular the axial distance between the 2 and the downstream end of the movable part 9.

[035] The propulsion unit 1 further comprises a closure member 13 movable axially in translation between a retracted position or closed or closed position, illustrated in Figure 1, and an extended position or open position, illustrated in FIG. Figure 2.

[036] The closure member 13 comprises, radially outer periphery, a cylindrical partition 14 having openings 15 regularly distributed over the circumference, and a closure wall 16 extending radially from the upstream end of the cylindrical partition . [037] The closure member 13 may further comprise a rounded central deflector 17 and a peripheral baffle 18, also of rounded shape. The deflectors 17, 18 are oriented and positioned so that, when air F penetrates radially from the outside towards the inside through the openings 15 of the cylindrical partition 14, this air F is directed or oriented axially downstream. The shutter member 13 can be moved by an actuator, such as for example a motor or a jack (not shown).

[038] The shutter member 13 and the movable portion 9 can be moved or used independently of one another, or simultaneously. If the movement is simultaneous, the same actuator can ensure their simultaneous movement.

The operation of such a propulsion unit 1 will now be described with reference to FIGS. 1 and 2.

[040] In the case of a flight phase corresponding to a horizontal advance phase, the closure member 13 and the movable portion 9 of the fairing are held in the retracted position, as shown in Figure 1. The wall closure 16 then closes the upstream opening of the fixed part 5 of the fairing and the airflow F, radially directed as illustrated by the arrows in FIG. 1, can not penetrate into the propulsion unit 1. The engine 3 can be stopped.

[041] Furthermore, the closure member 13 and the movable portion 9 being in the retracted position, the height or axial dimension of the propulsion assembly 1 is relatively small, which limits the aerodynamic resistance of the propulsion set 1.

[042] In a flight phase corresponding to a phase of vertical displacement of the aircraft, such as for example a take-off or landing phase, the shutter member 13 and the movable part 9 of the fairing are displaced. to their deployed positions, as shown in Figure 2. The engine 3 is also started, so as to rotate the propeller 2.

[043] The air F can then enter the fairing through the openings

15 of the closure member 13, the air F being directed axially by the deflectors 17, 18 and passing through the helix 2 being contained by the fixed portion 5 and the movable portion 9 of the shroud. In such a case, the height of the propulsion unit 1 is important. In particular, the displacement of the movable part 9 of the fairing towards its deployed position maximizes the axial distance d between the propeller 2 and the downstream end 12 of the movable part 9 of the fairing, which has the effect of improving the efficiency of the helix 2.

[044] The acoustic attenuation means 10, 11 also make it possible to limit the noise in such a case of operation.

[045] Figures 3 and 4 show a propulsion unit 1 for a vertical take-off and landing aircraft, according to a second embodiment of the invention.

[046] As previously, the propulsion unit 1 comprises a propeller 2 adapted to be rotated about an axis X by a motor 3. The stator 4 of the motor 3 is fixed on a mobile support 19.

[047] The propeller 2 is surrounded by a fixed fairing 5 of cylindrical shape, having upstream ends 6 and downstream 7 open. The propeller 2 extends here in a radial plane located axially downstream of the engine 3. The fairing 5 comprises radial fastening flanges 8, or zones of fairing continuity, at its upstream and downstream ends 6, 7.

[048] The movable support 19 comprises, at the radially outer periphery, a cylindrical partition 14 having regularly spaced openings 15 around the circumference, and a closure wall 16 extending radially from the upstream end of the cylindrical partition 15. mobile support 19 may further comprise a rounded central deflector 17 and a peripheral baffle 18, also of rounded shape. The deflectors 1, 18 are oriented and positioned so that, when air penetrates radially from the outside to the inside through the openings 15 of the cylindrical partition 14, this air is directed or oriented axially towards the wall. 'downstream. The stator 4 of the motor 3 can be fixed at the downstream end of the central deflector 17.

[049] The movable support 19 can be moved by an actuator, such as for example a motor or a jack (not shown). The mobile support 19 can be moved in translation along the X axis, between a retracted position or closed or closed position, illustrated in Figure 3, and an extended position or open position, illustrated in Figure 4.

[050] The operation of such a propulsion unit 1 will now be described with reference to FIGS. 3 and 4.

[051] In the case of a flight phase corresponding to a horizontal advance phase, the mobile support 19 is held in the retracted position, as illustrated in FIG. 3. The closing wall 16 then closes the upstream opening of the fairing 5 and the flow of air, radially directed, can not enter the propulsion assembly 1. The engine 3 can be stopped.

[052] Moreover, the movable support 19 being in the retracted position, the height or axial dimension of the propulsion assembly 1 is relatively low, which limits the aerodynamic resistance of the propulsion assembly 1.

[053] In a flight phase corresponding to a phase of vertical displacement of the aircraft, such as for example a take-off or landing phase, the mobile support 19 is moved to its deployed position, as illustrated in FIG. 4. The engine 3 is also started, so as to turn the propeller 2.

[054] The air can then enter the fairing 5 through the openings

15 of the mobile support 19, the air being directed axially by the baffles 17, 18 and passing through the propeller 2 being contained by the fairing. In such a case, the height of the propulsion unit 1 is greater. In particular, the displacement of the mobile support 19 towards its deployed position maximizes the axial distance d between the propeller 2 and the downstream end 7 of the fairing, which has the effect of improving the efficiency of the propeller 2.

[055] Figures 5 and 6 show a propulsion unit 1 according to a third embodiment of the invention.

[056] As before, the propulsion unit 1 comprises a propeller 2 adapted to be rotated about an axis X by a motor 3. The motor 3 comprises a stator 4 fixed on a support (not shown), - even integral with a fixed part 5 of a fairing. The motor 3 further comprises a rotor integral in rotation with the propeller 2.

[057] The fixed portion 5 of the fairing has upstream ends 6 and downstream 7 open. The propeller 2 here extends generally in a radial plane located axially downstream of the engine 3. In a variant, the propeller 2 may extend generally in a radial plane situated axially upstream of the engine 3.

[058] The fixed part 5 of the fairing comprises a cylindrical upstream zone 5a surrounding the propeller 2 with minimum operating clearance. The fixed portion 5 of the fairing further comprises a frustoconical downstream zone 5b flaring downstream.

[059] The fixed portion 5 of the fairing further comprises a radial attachment flange 8, or a fairing continuity zone, at its upstream end 6.

[060] The fairing further comprises a movable portion 9, located at the downstream end of the fixed portion 5. The movable portion 9 is frustoconical and flares downstream. In the embodiment shown here, the movable portion 9 is located radially outside the fixed portion 5.

[061] The movable part 9 can be moved by an actuator, such as for example a motor or a jack (not shown). The mobile part 9 can be displaced in translation along the X axis, between a retracted or retracted position, illustrated in FIG. 1, and an extended position, illustrated in FIG. 2. In its retracted position, the downstream end 12 of the movable portion 9 is located axially facing the downstream end 7 of the fixed part 5 of the fairing. In its deployed position, the upstream end 20 of the movable part 9 is located axially opposite and in the extension of the flared downstream end 7 of the fixed part 5, so as to form a diffuser and to increase the length fairing, in particular the axial distance d between the helix 2 and the downstream end 12 of the movable part 9.

[062] In the case of a flight phase corresponding to a horizontal advance phase, the movable portion 9 of the fairing is held in the retracted position, as illustrated in FIG. 5. In this way, the height or axial dimension of the propulsion assembly 1 is relatively small, which limits the aerodynamic resistance of the propulsion assembly 1.

[063] In a flight phase corresponding to a phase of vertical displacement of the aircraft, such as for example a take-off or landing phase, the movable portion 9 of the fairing is moved to its deployed position, as shown in FIG. Figure 6. The engine 3 is also started, so as to rotate the propeller 2.

[064] The air entering the upstream opening of the fairing passes through the propeller 2 being contained by the shroud, before escaping through the diffuser. In such a case, the height of the propulsion unit 1 is important. In particular, the displacement of the movable portion 9 of the fairing towards its deployed position maximizes the axial distance d between the propeller 2 and the downstream end of the movable part 9 of the fairing, which has the effect of improving the propeller efficiency 2.

Claims

1. Propulsion unit (1) for a vertical take-off and landing aircraft, comprising a propeller (2) adapted to be rotated about an axis (X) by a motor (3), and a fairing (5, 9) surrounding said propeller (2), characterized in that said assembly (1) comprises at least one movable part (9, 19) able to modify the axial distance (d) between the propeller (2) and the downstream end of the fairing (5, 9).

2. Assembly (1) according to claim 1, characterized in that the at least one movable portion comprises a portion (9) of the fairing.

3. Assembly (1) according to claim 2, characterized in that the movable portion (9) of the fairing comprises a frustoconical portion movable between a retracted position and an extended position wherein said frustoconical portion is adapted to form a divergent diffuser to the downstream end of the fairing (5, 9).

4. The assembly (1) according to claim 2, characterized in that the movable portion (9) of the fairing comprises a cylindrical portion movable between a retracted position and an extended position in which said cylindrical portion extends the downstream end of the fairing (5). , 9).

5. Assembly (1) according to one of claims 1 to 4, characterized in that the at least one movable part comprises a movable support (19) on which are mounted the motor (3) and the propeller (2) , said movable support (19) being able to be displaced with respect to at least one fixed part (5) of the fairing.

6. Assembly (1) according to claim 5, characterized in that the fairing comprises an air inlet at the upstream end (6) of the fairing, the movable support (19) having a shutter portion (16) fit closing the air inlet in a retracted position of the movable support (19), said closing portion (16) being spaced from the air inlet in an extended position of the movable support (19).

7. Assembly (1) according to one of claims 1 to 6, characterized in that the fairing comprises an air inlet at the upstream end (6) of the fairing, the assembly comprising a movable closing member (13) adapted to close the air inlet in a retracted position of the closure member (13), the closure member (13) being discarded the air inlet in an extended position of said member (13).

8. Assembly (1) according to claim 6 or 7, characterized in that the movable support (19) or the closure member (13) comprises at least one deflector (17, 18) adapted to redirect a flow of incoming air (F) oriented perpendicular to the axis (X) of the propeller (2) in an air flow oriented along the axis (X) of the propeller (2).

9. Assembly (1) according to one of claims 1 to 7, characterized in that the movable part (9) and the closure member (13) are able to be moved simultaneously).

10. Aircraft, characterized in that it comprises at least one assembly (1) according to one of claims 1 to 9, the axis (X) of the propeller (2) being oriented vertically.