Support device for at least one stator blade of an aircraft turbomachine and method of using same

Abstract

A support device (1) for at least one stator blade (22) of an aircraft turbomachine, the aircraft turbomachine extending along a longitudinal axis (X) oriented from upstream to downstream and comprising an external wall (21) from which the stator blade (22) extends in projection along a radial axis (Y), the support device (1) comprising: - at least one housing (2) configured to radially receive a mounting foot (23) of the stator blade (22) and; - an upstream support foot (5) and a downstream support foot (6) connected respectively to an upstream end (3) and to a downstream end (4) of the housing (2) and configured to be mounted on the external wall (21) of the aircraft turbomachine, the downstream support foot (6) comprising at least one return member (7) adapted to be stressed under the effect of an impact exerted on the stator blade (22). Abstract figure: Figure 2

Description

Title of the invention: Support device for at least one stator blade of an aircraft turbomachine and method of using it Technical field

[0001] The present invention relates to an aircraft turbomachine and more specifically relates to a device for supporting at least one stator blade as well as its method of use.

[0002] Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change. Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0003] This sustained research and development work relates in particular to new generations of aircraft turbomachines known as "unducted" in that they are free of a nacelle surrounding the aircraft turbomachine. An unducted turbomachine conventionally comprises, upstream, a fan configured to guide an air flow in an air stream defined from upstream to downstream by one or more compressors, a combustion chamber and one or more turbines. No fairing surrounds the fan, which makes it possible to provide a fan with a very large diameter greater than 3.5 m. The mass of the aircraft turbomachine is advantageously reduced and the thrust improved, making it possible to reduce fuel consumption by 20% compared to the latest generations of aircraft turbomachines.

[0004] In practice, a rectifier is mounted externally on the aircraft turbomachine, downstream of the fan, in order to straighten the air flow not admitted into the air stream and promote thrust. Like the fan, no fairing surrounds the rectifier. Such a rectifier comprises a plurality of stator blades comprising a radial blade and a mounting foot connected by a platform. The mounting foot of each stator blade is mounted in a housing which is fixed to the outer casing of the compressor(s). In the case of variable-pitch stator blades, the mounting foot is mounted to pivot radially in the housing in order to adapt the angle of attack of the stator blades during flight.

[0005] Because it is unducted, such a rectifier is more exposed to a risk of impact by a solid body, such as a bird, which in the long term could damage the parts of the aircraft turbomachine, in particular by deformation. To limit the risk, one solution would be to reinforce the housing and the compressor casing, which would however have an undesirable impact on the mass of the aircraft turbomachine. Another solution would be to reinforce only the housing, but this would transmit the forces undesirably to the external compressor casing.

[0006] The invention thus aims to protect an aircraft turbomachine in the event of impact of a solid body, such as a bird, on the stator blades of an unducted rectifier. PRESENTATION OF THE INVENTION

[0007] The invention relates to a support device for at least one stator blade of an aircraft turbomachine, the aircraft turbomachine extending along a longitudinal axis oriented from upstream to downstream and comprising an external wall from which the stator blade extends projecting along a radial axis, the support device comprising: • At least one housing configured to radially receive a mounting foot of the stator blade, • An upstream support foot and a downstream support foot connected respectively to an upstream end and to a downstream end of the housing and configured to be mounted on the external wall of the aircraft turbomachine.

[0008] The invention is remarkable in that the downstream support foot comprises at least one return member adapted to be stressed under the effect of an impact exerted on the stator blade.

[0009] The support device according to the invention advantageously makes it possible to absorb the forces experienced during an impact exerted from upstream to downstream by a solid body, such as a bird, on the stator blade, in particular at the blade. The return member integrated in the downstream support foot is advantageously adapted to be constrained under the effect of the impact, which integrally tilts the housing and the stator blade downstream. This has the effect of limiting the forces experienced by the stator blade, but also those transmitted to the external wall of the aircraft turbomachine. The return member thus makes it possible to avoid deformation or even damage to the aircraft turbomachine, without impacting the mass and complexity thereof.

[0010] According to one aspect of the invention, the return member is configured to be radially constrained relative to the longitudinal axis. This advantageously makes it possible to reversibly tilt the blades downstream so as to absorb the forces experienced during the impact.

[0011] According to one aspect of the invention, the return member is in the form of a compression spring, namely a passive organ that is easy to integrate and inexpensive.

[0012] According to one aspect of the invention, the return member is prestressed by a stop member so as to limit the inclination of the housing towards the upstream. Advantageously, the return member is thus insensitive to the aerodynamic forces exerted on the stator blades during flight, such as those of lift and drag. This prevents untimely inclinations of the stator blade.

[0013] According to one aspect of the invention, the stop member extends radially outwardly relative to the downstream support foot and is configured to be fixed to the external wall of the aircraft turbomachine. Such a stop member is a passive member that is simple to integrate and inexpensive.

[0014] According to one aspect of the invention, the upstream support foot comprises a second return member adapted to be constrained to allow an inclination of the housing upstream. Preferably, the second return member is in the form of a compression spring. The second return member advantageously makes it possible to dampen the elastic return force after the impact exerted by the first return member.

[0015] Preferably, the second return member is prestressed by a second stop member, so as to limit the inclination of the housing downstream. Advantageously, the return member is thus insensitive to the aerodynamic forces exerted on the stator blades during flight, such as those of lift and drag. This prevents untimely inclinations of the stator blade.

[0016] According to one aspect of the invention, the support device defines a cavity delimited upstream by the upstream support foot and downstream by the downstream support foot, the cavity being adapted to house a device for controlling the pivot angle along the radial axis of the stator blade in the housing. The variable setting device is thus integrated in a simple and practical manner into the support device.

[0017] The invention also relates to an assembly of a support device as described above and an unducted rectifier of an aircraft turbomachine comprising at least one stator blade, the aircraft turbomachine extending along a longitudinal axis oriented from upstream to downstream and comprising an external wall from which the stator blade is configured to extend projecting along a radial axis, the stator blade comprising a mounting foot mounted radially in the housing of the support device, preferably pivoting along the radial axis in the housing.

[0018] The invention also relates to an aircraft turbomachine extending along a longitudinal axis oriented from upstream to downstream and comprising: • An external wall, preferably in the form of an outer compressor casing, • An unshrouded rectifier comprising at least one stator vane extending projecting from the external wall along a radial axis, • At least one support device as described above, in which the upstream support foot and the downstream support foot are mounted on the external wall, the stator blade comprising a mounting foot mounted radially in the housing of the support device.

[0019] Preferably, the aircraft turbomachine is of the unducted type. The stator vanes of the rectifier are not protected by a fairing and are more exposed to the risk of bird strikes.

[0020] The invention also relates to a method of using an assembly as described above, in which the return member is constrained under the effect of an impact exerted on the stator blade of the aircraft turbomachine. Such a method is implemented passively, that is to say that it advantageously does not require any manual or electronic control. Such a method is furthermore advantageously repeatable. PRESENTATION OF FIGURES

[0021] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0022] [Fig.l] is a schematic perspective representation of an aircraft turbomachine according to one embodiment of the invention.

[0023] [Fig. 2] is a schematic representation in longitudinal half-section of the support device according to a first embodiment of the invention.

[0024] [Fig. 3] is a schematic representation in longitudinal half-section of the support device according to a second embodiment of the invention.

[0025] [Fig.4] is a schematic representation in longitudinal half-section of the support device according to a third embodiment of the invention.

[0026] [Fig. 5] is a schematic representation of the stress exerted on the return member of the support device during an impact of a solid body on the stator blade according to one embodiment of the invention.

[0027] [Fig. 6] is a schematic representation of the elastic return force of the return member of the support device after an impact of a solid body on the stator blade according to one embodiment of the invention.

[0028] It should be noted that the figures set out the invention in detail for implementing the invention, said figures of course being able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0029] With reference to [Fig. 1], the invention relates to an aircraft turbomachine 20 extending along a longitudinal axis X oriented from upstream to downstream. The aircraft turbomachine 20 conventionally comprises, upstream, a fan 27 configured to guide an air flow in an air stream 28 defined from upstream to downstream by one or more compressors, a combustion chamber and one or more turbines. The fan 27 is of the unducted type and preferably has a diameter greater than 3.5 m. The aircraft turbomachine 20 is preferably in the form of a turboprop in which the fan 27 is driven by the turbine(s) via a speed reducer.

[0030] With reference to Figures 1 and 2, the aircraft turbomachine 20 also comprises a non-ducted rectifier 29 extending radially outwardly relative to the air stream 28, downstream of the fan 27. The non-ducted rectifier 29 makes it possible to straighten the air flow not admitted into the air stream 28 and promote thrust. The rectifier 29 comprises a plurality of stator blades 22 extending outwardly from an external wall 21 of the aircraft turbomachine 20, preferably along a radial axis Y. Each stator blade 22 comprises a radial blade 25 and a mounting foot 23 connected by a platform 24.

[0031] The aircraft turbomachine 20 is preferably of the unducted type, that is to say that it is free of a nacelle surrounding the aircraft turbomachine 20.

[0032] With reference to [Fig.2], the invention relates to a support device 1 for one or more stator blades 22 of the unducted rectifier 29 of the aircraft turbomachine 20, comprising: • One or more housings 2 each configured to radially receive a mounting foot 23 of a stator blade 22, • An upstream support foot 5 and a downstream support foot 6 connected respectively to an upstream end 3 and to a downstream end 4 of the housing(s) 2 and configured to be mounted on the external wall 21 of the aircraft turbomachine 20, the downstream support foot 6 comprising a return member 7 adapted to be stressed under the effect of an impact A (see [Fig.5]) exerted on the stator blade 22.

[0033] Thanks to the return member 7, the support device 1 according to the invention advantageously makes it possible to absorb the forces transmitted to the aircraft turbomachine 20 during an impact of a solid body, such as a bird, exerted on one or more stator blades 22 of the rectifier 29. Indeed, the return member 7 advantageously allows the stator blades 22 to tilt downstream, which allows the impact to be damped. The risk of deformation or even breakage is reduced both for the stator blades 22 and for the external wall 21 of the aircraft turbomachine 20. The return member 7 also does not penalize the mass of the aircraft turbomachine 20.

[0034] According to a preferred aspect, the support device 1 is in the form of a peripheral part of longitudinal axis X comprising a housing 2 for each stator vane 22 of the rectifier 29. According to another preferred aspect, the support device 1 is in the form of one or more angular sectors each comprising one or more housings 2 and extending in a partially peripheral or peripheral manner around the longitudinal axis X.

[0035] According to a preferred aspect, the external wall 21 on which the support device 1 is fixed is in the form of the external wall of the air stream 28, and preferably of the external casing of one or more compressors mounted in the air stream 28. In this example, the upstream support foot 5 is fixed to the external casing 21A of an upstream compressor and the downstream support foot 6 is fixed to the external casing 21B of a downstream compressor of the aircraft turbomachine 20. One or more fixing elements ensure the fixing of the support feet 5, 6 to the external wall 21, such as screws or bolts.

[0036] According to a preferred aspect illustrated in [Fig. 2], the mounting foot 23 of the stator blade 22 is pivotally mounted along the radial axis Y in the housing 2. In other words, the stator blades 22 of the rectifier 29 are of the variable pitch type, which makes it possible to modify their angle of attack depending on the flight conditions. It is specified that the stator blades 22, as opposed to rotor blades, are not mounted so as to be able to rotate along the longitudinal axis X. The only degree of freedom of the rotor blade 22 is rotation along the radial axis Y. Alternatively, the mounting foot 23 of the stator blade 22 is fixedly mounted in the housing 2.

[0037] As illustrated in [Fig. 2], the support device 1 preferably defines a cavity C delimited upstream by the upstream support foot 5 and downstream by the downstream support foot 6. The cavity C extends radially between the external wall 21 and the housing 2 and makes it possible to house a device (not shown) for controlling the pitch angle of one or more stator blades 22, namely their pivot angle along the radial axis Y in the housing 2.

[0038] As illustrated in [Fig. 2], the return member 7 integrated in the downstream support foot 6 is preferably in the form of a compression spring, simple to integrate and inexpensive. The return member 7 is dimensioned to be stressed under the effect of an impact of a solid body, such as a bird, exerted on the stator blade 22 without being unintentionally stressed by aerodynamic disturbances during flight. Preferably, the return member 7 is dimensioned to be stressed in the presence of a force exerted on the stator blade 22 greater than the aerodynamic forces in cases of normal operation.

[0039] According to a preferred aspect illustrated in [Fig.2], the return member 7 extends radially between the housing 2 and the external wall 21 so as to be stressed ra- dially during an impact. In this example, the return member 7 extends along the radial axis Y but could alternatively extend in a direction with a radial component. This makes it possible to ensure an inclination of the stator blade 22 downstream and to absorb the transmitted forces. According to a preferred aspect illustrated in [Fig. 2], the downstream support foot 6 comprises a support portion 11 extending between the housing 2 and the return member 7. The support portion 11 is made of a rigid material, such as titanium or an alloy comprising iron, nickel and chromium, and makes it possible to transmit the forces to the return member 7. The support portion 11 preferably extends longitudinally along the longitudinal axis X.

[0040] In the example of [Fig. 2], in the absence of impact on the stator blade 22, the return member 7 extends at rest in an unstressed state and the support device 1 holds the stator blade 22 along the radial axis Y. Still in the example of [Fig. 2], the upstream support foot 5 is free of a return member and is preferably made of a rigid material such as titanium or an alloy comprising iron, nickel and chromium.

[0041] The embodiment of [Fig. 3] differs from that of [Fig. 2] in that the support device 1 further comprises a stop member 8 keeping the return member 7 prestressed. In this example, the stop member 8 is mounted on the external wall 21 and extends radially outwardly relative to the downstream support foot 6. The downstream support foot 6 extends in radially outward bearing against the stop member 8 thanks to a prestressing force F0 exerted by the return member 7 against the stop member 8.

[0042] The stop member 8 advantageously makes it possible to avoid untimely inclinations of the stator blade 22 under the effect of the aerodynamic forces exerted on the stator blade 22 during flight. The prestressing force F0 is chosen so as to be greater than the aerodynamic forces in normal operation and less than the forces exerted by an impact of a solid element, such as a bird, whose mass at impact can reach 15t. Thus, in the presence of aerodynamic forces, the return member 7 maintains the stator blade 22 along the radial axis Y.

[0043] The embodiment of [Fig. 4] differs from those of figures 2 and 3 in that the upstream support foot 5 comprises a second return member 9 held prestressed by a second stop member 10. The return member 7 of the downstream support foot 6 and the associated stop member 8 are renamed respectively “first return member 7” and “first stop member 8” for the sake of clarity.

[0044] With reference to [Fig. 4], the second return member 9 is preferably in the form of a compression spring with a stiffness constant preferably equal to that of the first return member 7. Preferably, the second return member 9 extends radially between the housing 2 and the external wall 21 so as to be radially constrained. Also preferably, the upstream support foot 5 comprises a support portion 12, in this example longitudinal and made of a rigid material such as titanium or an alloy comprising iron, nickel and chromium, which extends between the housing 2 and the return member 7.

[0045] The second return member 9 advantageously makes it possible to reduce the forces exerted at the upstream support foot 5 during an impact of a solid body on the stator blade 22. The second return member 9 also makes it possible to dampen the elastic return forces exerted by the first return member 7 after the impact to return to the neutral position, namely at rest in the example of [Fig.2] and prestressed in that of [Fig.3].

[0046] Still with reference to [Fig. 4], the second stop member 10 is preferably mounted on the external wall 21 and extends radially outwardly relative to the upstream support foot 5. The upstream support foot 5 extends in radially outward bearing against the second stop member 10 thanks to a prestressing force F0' exerted by the second return member 9 which is equal to that F0 of the first return member 7. The second stop member 10 contributes to avoiding untimely inclinations of the stator blade 22 under the effect of aerodynamic forces exerted on the stator blade 22 during flight.

[0047] Alternatively, the support device 1 is free of a second stop member 10 and, in the absence of impact on the stator blade 22, the return member 7 extends at rest in an unstressed state.

[0048] Figures 2, 3 and 4 illustrate the support device 1 when the return member 7 (or the first and second return members 7, 9) is (are) in the neutral position, namely in the absence of impact of a solid body on the stator blade 22. In the example of [Fig. 2] without abutment member 8, the return member 7 is at rest. In the example of [Fig. 3] with abutment member 8, the return member 7 is prestressed and exerts a prestressing force F0 against the abutment member 8. The same applies to the second return member 9 in the example of [Fig. 4]. In the neutral position illustrated in Figures 2, 3 and 4, the support device 1 holds the stator blade 22 along the radial axis Y.

[0049] Still with reference to figures 2, 3 and 4, the stiffness constant of the return member(s) 7, 9 as well as the stop member(s) 8, 10 make it possible to maintain the neutral position in the presence of aerodynamic forces exerted on the stator blade 22, for example meteorological disturbances.

[0050] [Fig. 5] illustrates an impact A of a solid body oriented from upstream to downstream on the stator blade 22, typically a bird, having the effect of forcing the return member 7 into a compressed state FL. The stator blade 22 and the housing 2 are then inclined downstream to an impact axis Y1 in a solid manner, which allows to dampen the forces transmitted to the aircraft turbomachine. The impact A also has the effect of constraining the second return member 9 into a stretched state Fl'. In the example of [Fig.5], the second stop member 10 and the stiffness constant of the return members 7, 9 make it possible to control the inclination of the stator blade 22. Preferably, the downstream inclination angle a between the radial axis Y and the impact axis Y1 is between 1° and 5°.

[0051] As illustrated in [Fig.6], following the impact A, the return member 7 exerts an elastic return force F2 which has the effect of tilting the housing 2 and the stator blade 22 upstream to an impact return axis Y2. In this example, this also has the effect of constraining the second return member 9 into a compressed state F2'. Preferably, the stop member 8 and the stiffness constant of the return members 7, 9 make it possible to control the upstream angle of inclination y between the radial axis Y and the impact return axis Y2, less than the downstream angle of inclination a. The return member(s) 7, 9 thus advantageously return to the neutral position by oscillation from upstream to downstream.

[0052] Advantageously, the support device 1 thus makes it possible to protect the stator blades 22 of an unducted rectifier 29 and the external wall 21 of the aircraft turbomachine 20 from deformation or even damage. The method is advantageously implemented passively, without any manual or electronic control, under the action of the forces generated by the impact A. The method is also advantageously repeatable.

Claims

Claims

1. Support device (1) for at least one stator blade (22) of an aircraft turbomachine (20), the aircraft turbomachine (20) extending along a longitudinal axis (X) oriented from upstream to downstream and comprising an external wall (21) from which the stator blade (22) projects along a radial axis (Y), the support device (1) comprising: • At least one housing (2) configured to radially receive a mounting foot (23) of the stator blade (22), • An upstream support foot (5) and a downstream support foot (6) connected respectively to an upstream end (3) and to a downstream end (4) of the housing (2) and configured to be mounted on the external wall (21) of the aircraft turbomachine (20), • The support device (1) being characterized in that the downstream support foot (6) comprises at least one member of reminder (7) adapted to be constrained under the effect of an impact (A) exerted on the stator blade (22).

2. Support device (1) according to claim 1, wherein the return member (7) is configured to be radially constrained relative to the longitudinal axis (X).

3. Support device (1) according to one of claims 1 and 2, in which the return member (7) is in the form of a compression spring.

4. Support device (1) according to one of claims 1 to 3, in which the return member (7) is prestressed by a stop member (8) so as to limit the inclination of the housing (2) upstream.

5. Support device (1) according to claim 4, wherein the stop member (8) extends radially outwardly relative to the downstream support foot (6) and is configured to be fixed to the external wall (21) of the aircraft turbomachine (20).

6. Support device (1) according to one of claims 1 to 5, in which the upstream support foot (5) comprises a second return member (9) adapted to be constrained, to allow an inclination of the housing (2) towards the upstream.

7. Support device (1) according to one of claims 1 to 6, de- ending a cavity (C) delimited upstream by the upstream support foot (5) and downstream by the downstream support foot (6), the cavity (C) being adapted to house a device for controlling the pivot angle along the radial axis (Y) of the stator blade (22) in the housing (2).

8. Assembly of a support device (1) according to one of claims 1 to 7 and at least one unducted rectifier (29) of an aircraft turbomachine (20) comprising at least one stator blade (22), the aircraft turbomachine (20) extending along a longitudinal axis (X) oriented from upstream to downstream and comprising an external wall (21) from which the stator blade (22) is configured to extend projecting along a radial axis (Y), the stator blade (22) comprising a mounting foot (23) mounted radially in the housing (2) of the support device (1), preferably pivoting along the radial axis (Y) in the housing (2).

9. Aircraft turbomachine (20) extending along a longitudinal axis (X) oriented from upstream to downstream and comprising: • An external wall (21), preferably in the form of an external compressor casing, • An unducted rectifier (29) comprising at least one stator blade (22) extending projecting from the external wall (21) along a radial axis (Y), • At least one support device (1) according to one of claims 1 to 7, in which the upstream support foot (5) and the downstream support foot (6) are mounted on the external wall (21), the stator blade (22) comprising a mounting foot (23) mounted radially in the housing (2) of the support device (1).

10. Method of using an assembly according to claim 8, in which the return member (7) is constrained under the effect of an impact (A) exerted on the stator blade (22) of the aircraft turbomachine (20).

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