Aircraft turbomachine fan and method of using same

Abstract

An aircraft turbomachine fan (1) (30) comprising blades (3) carried by a rotating hub along a longitudinal axis (X), an outer shroud (4) integral with the rotating hub and a fan compartment defined radially between the rotating hub and the outer shroud (4), the outer shroud (4) comprising: - at least one frame (7) delimiting an inspection opening (8) for accessing the fan compartment, and - at least one panel (9) removably mounted on the frame (7) to close the inspection opening (8), the panel (9) comprising at least a first end and a second opposite end extending in abutment against an internal face of the frame (7) facing the longitudinal axis (X). Abstract figure: Figure 1

Description

Title of the invention: Aircraft turbomachine fan and method of using same Technical field

[0001] The present invention relates to the field of aircraft turbomachine fans.

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various States. In particular, an ambitious standard applies both to new types of aircraft and those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0003] 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.

[0004] This sustained research and development work relates in particular to new generations of so-called "unducted" aircraft turbomachines in that no nacelle surrounds the turbomachine, which makes it possible to reduce the mass. Such an unducted aircraft turbomachine conventionally comprises, upstream, an unducted fan making it possible to guide an air flow in a vein comprising, from upstream to downstream, 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 of very large diameter, in particular greater than 3.5 m, to improve the thrust.

[0005] In practice, the fan comprises a set of blades carried by a rotating hub connected in rotation to a shaft of the aircraft turbomachine via a reduction gear. Each blade comprises a root mounted in a housing of the rotating hub, a blade extending radially outwardly and a platform connecting the root and the blade. To protect the rotating hub and ensure aerodynamics, the unducted fan comprises an outer shroud extending radially around the rotating hub and integral with it. Mounting openings are formed in the outer shroud for the blades of the vanes. A fan compartment is defined radially between the rotating hub and the outer shroud and houses the blade platforms as well as one or more aircraft turbomachinery equipment, such as a telemetry box.

[0006] To reduce the downtime of the aircraft during maintenance or inspection operations of the fan, it is known to provide inspection openings in the outer shell downstream of the mounting openings. Such inspection openings are closed by removable panels screwed externally onto the outer shell. During maintenance, the operator removes the panel by loosening the screws, which allows him to access the fan compartment in a simple and practical manner without having to disassemble the blades and the outer shell.

[0007] In practice, one or more panel fasteners are likely to loosen under the effect of centrifugal forces generated by the rotation of the fan. This can ultimately disrupt aerodynamics, generate vibrations and in some cases lead to the loss of a panel during the flight of the aircraft. To avoid this, one solution is to implement regular verification procedures for the holding of the panels, which is restrictive and costly. Another solution would be to use stronger and more numerous fasteners, which would undesirably complicate access to the inspection openings.

[0008] The invention thus aims to eliminate one or more of the aforementioned drawbacks in aircraft turbomachine fans, in particular unducted ones. PRESENTATION OF THE INVENTION

[0009] The invention relates to an aircraft turbomachine fan comprising a hub rotating along a longitudinal axis and a plurality of blades carried by the rotating hub, the fan comprising an outer shroud secured to the rotating hub and a fan compartment defined radially between the rotating hub and the outer shroud, the outer shroud comprising: • at least one frame delimiting an inspection opening to access the blower compartment, • at least one panel removably mounted on the frame to close the inspection opening.

[0010] The invention is remarkable in that the panel of the external shroud of the fan comprises at least a first end and a second end, opposite the first end, which extend in abutment against an internal face of the frame facing the longitudinal axis.

[0011] The external face of the panel reconstitutes the aerodynamic surface of the external shell at the inspection opening. The first end and the second end of the panel have an external face resting on the internal face of the inspection opening. The first end and the second end are said to be opposite in that they form two portions of the perimeter which are not adjacent and extend substantially opposite each other so as to hold the entire panel against the frame.

[0012] Mounting the panel against the internal face of the frame allows the ends of the panel to be pressed against the frame under the effect of centrifugal force, which avoids any risk of losing a panel during the flight of the aircraft. Thus, even if the mounting of the panel on the frame is subject to play or even weakened, the frame radially retains the panel by overlapping its ends. Such internal mounting also reduces the stress on the mounting elements, which reduces the risk of play or weakening occurring. The procedures for checking the mounting of the panel by an operator can thus be spaced out. Furthermore, access to the inspection opening remains simple and practical. The internal mounting of the panel allows the use of inexpensive and few mounting elements to ensure sufficient strength.

[0013] According to a preferred aspect, the blower is of the unducted type. This allows simple and easy access to the blower compartment.

[0014] According to a preferred aspect, the first end and the second end are opposite in the circumferential direction relative to the longitudinal axis for better resistance under the effect of centrifugal force.

[0015] According to one aspect of the invention, the first end of the panel extends over the entire length or width of the panel. Preferably, the second end of the panel extends over the entire length or width of the panel. This ensures good pressing of the panel on the internal face of the frame when driving the rotating hub.

[0016] According to one aspect of the invention, the panel comprises a periphery comprising the first end and the second end, the entire periphery of the panel bearing against the internal face of the frame. This ensures optimal pressing of the panel against the internal face of the frame when driving the rotary hub.

[0017] According to a preferred aspect of the invention, the longitudinal axis of the rotating hub of the fan is oriented from upstream to downstream in the direction of circulation of an air flow during a thrust phase of the aircraft turbomachine, the inspection opening of the outer shroud extending downstream of the blades. This promotes the aerodynamics of the outer shroud of the fan. Alternatively or additionally, one or more inspection openings extend upstream of the blades.

[0018] According to one aspect of the invention, the frame has two sides extending in an oblique direction forming an angle relative to a longitudinal direction parallel to the longitudinal axis. This reduces the drag generated by the boundary layer of air flow around the outer shell circulating at the connection between the frame and the panel.

[0019] According to one aspect of the invention, the external ferrule comprises at least one fixing element mounted in a through manner in the frame and in the first end of the panel, the fixing element being removable from an external face of the frame opposite the internal face. Preferably, at least one fixing element removable from the external face of the frame is mounted in a through manner in the frame and in the second end of the panel. Preferably, the fixing element is in the form of a screw. This makes it possible to secure the panel to the frame in a reversible, simple and practical manner.

[0020] According to another aspect of the invention, the outer ferrule comprises at least one locking element movable from an outer face of the frame opposite the inner face, the first end of the panel being sandwiched between the locking element and the frame. Preferably, the second end of the panel is sandwiched between the frame and a locking element movable from the outer face of the frame. Preferably, the locking element is in the form of a cleat. This makes it possible to keep the panel pressed against the frame in a reversible, simple and practical manner.

[0021] According to one aspect of the invention, the panel comprises a first part and a second part, the first part comprising the first end, the second part comprising the second end, the first part comprising a third end, opposite the first end, cooperating with a fourth end of the second part, opposite the second end. This makes it possible to extract the panel more simply from the inspection opening.

[0022] According to a preferred aspect of the invention, the external ferrule comprises: • a plurality of frames distributed around the circumference of the external shell and each delimiting an inspection opening for accessing the fan compartment, • at least one panel removably mounted on each frame to close the inspection opening, each panel comprising at least a first end and a second end, opposite the first end, which extend in abutment against an internal face of the frame facing the longitudinal axis.

[0023] This provides simple and convenient access to the entire blower compartment.

[0024] The invention also relates to an aircraft turbomachine comprising a fan as described above and a gas generator driving the fan in rotation.

[0025] The invention also relates to a method of using a blower as described above, in which the rotational drive of the rotating hub presses the first end and the second end of the panel against the internal face of the frame by centrifugal effect. This prevents any risk of losing the panel, even if the panel mounting has play.

[0026] The invention also relates to a method for maintaining a blower as described above, consisting of dismantling the panel from the frame and extracting the panel from the blower via the inspection opening. Advantageously, dismantling the frame is simple, practical and quick for an operator. PRESENTATION OF FIGURES

[0027] 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.

[0028] [Fig.l] is a schematic perspective representation of an unducted aircraft turbomachine comprising an unducted fan according to one embodiment of the invention.

[0029] [Fig.2] is a schematic perspective representation of the outer shroud of the unducted fan of [Fig.l].

[0030] [Fig. 3] is a schematic cross-sectional representation of the panels closing the inspection openings of the external shell of the unducted fan of [Fig. 2],

[0031] [Fig.4] is a schematic representation of the disassembly of a panel to access an inspection opening in the external shell of the ducted fan of [Fig.2],

[0032] [Fig.5] is a schematic perspective representation from the inside of a panel closing an inspection opening in the external shell of the ducted fan of [Fig.2].

[0033] [Fig. 6] is a schematic cross-sectional representation of the panels closing the inspection openings of the external shell of the unducted fan according to another embodiment of the invention.

[0034] [Fig.7] is a schematic perspective representation from the inside of a panel closing an inspection opening of the external shell of the ducted fan according to another embodiment.

[0035] [Fig. 8] is a schematic cross-sectional representation of the panels closing the inspection openings of the external shell of the unducted fan according to another embodiment of the invention.

[0036] [Fig.9] is a schematic perspective representation of the outer shell with oblique panels according to another embodiment of the invention.

[0037] It should be noted that the figures set out the invention in detail to illustrate implements the invention, said figures being able of course to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0038] With reference to [Fig.l], the invention is presented in the context of a fan 1 of the unducted type of aircraft turbomachine 30, that is to say that no fairing surrounds the fan 1. Such an unducted fan 1 usually has a large diameter greater than 3.5 m and a reduced mass which allows it to generate significant thrust. The invention also applies to ducted fans of aircraft turbomachine 30 for which access to the fan compartment is desired.

[0039] As illustrated in [Fig.l], the aircraft turbomachine 30 conventionally comprises an air stream 31 extending along a longitudinal axis X and in which an air flow circulates from upstream to downstream in a gas generator during a thrust phase of the aircraft turbomachine 30. The gas generator conventionally comprises from upstream to downstream one or more compressors, a combustion chamber and one or more turbines. The fan 1 conventionally extends upstream of the gas generator and makes it possible to guide the air flow in the air stream 31. The aircraft turbomachine 30 is in this example in the form of a turboprop in which the fan 1 is driven in rotation by the turbine(s) via a speed reducer.

[0040] In the example of [Fig.l], the aircraft turbomachine 30 is of the unducted type, that is to say that no nacelle surrounds the aircraft turbomachine 30. Still in this example, the compressor of the aircraft turbomachine 30 comprises upstream an unducted rectifier 32 whose stator blades extend radially projecting outwardly from the air stream 31 to promote thrust.

[0041] With reference to Figures 1 and 2, the fan 1 comprises a rotating hub 2 along the longitudinal axis X carrying a set of blades 3. Each blade 3 typically comprises a root (not shown) mounted in a housing of the rotating hub 2, a blade 18 extending radially outwardly and a platform 19 connecting the root and the blade 18. To protect the rotating hub and ensure aerodynamics, the fan 1 comprises an outer shroud 4 extending radially around the rotating hub 2 and secured to it. The outer shroud 4, in one piece or comprising several portions assembled together, comprises mounting openings 6 through which the blades 3 pass to allow the blades 18 to extend outwardly. A fan compartment 5 is defined radially between the rotating hub 2 and the outer shroud 4 and houses the platforms 19 of the blades 3 as well as one or more aircraft turbomachine equipment 30, such as a telemetry box.The blower compartment 5 corresponds to the inside of the outer shell 4. .

[0042] According to the invention and as illustrated in Figures 1 to 4, the outer shell 4 comprises at least one frame 7 delimiting an inspection opening 8 (see [Fig.4]) for accessing the fan compartment 5. Still according to the invention, the outer shell 4 comprises at least one panel 9 removably mounted on the frame 7 to close the inspection opening 8 (see [Fig.3]). Still according to the invention, the panel 9 comprises at least a first end 10 and a second end 11, opposite the first end 10, which extend in abutment against an internal face 14 of the frame 7 facing the longitudinal axis X.

[0043] Mounting the panel 9 in abutment against the internal face 14 of the frame 7 advantageously eliminates the risk of losing a panel 9 during the flight of the aircraft. Indeed, the rotational drive of the fan 1, and in particular of the external shroud 4, makes it possible to press the ends 10, 11 of the panel 9 against the frame 7 under the effect of centrifugal force. Thus, even if the mounting of the panel 9 on the frame 7 is subject to play or even weakened, the frame 7 overlaps the panel 9 at the ends 10, 11, which radially retains the panel 9 and prevents it from passing through the inspection opening 8. Such an internal mounting also makes it possible to reduce the stress on the mounting elements, which reduces the risk of play or weakening occurring. The procedures for checking the mounting of the panel 9 by an operator can thus be spaced out.

[0044] Furthermore, access to the inspection opening 8 remains simple and practical. The internal mounting of the panel 9 makes it possible to use inexpensive and few mounting elements to ensure sufficient hold. As will be explained later, the panel 9 is adapted, when removed from the frame 7, to be extracted from the blower 1 via the inspection opening 8. As illustrated in [Fig. 4], the panel 9 having a surface area greater than that of the inspection opening 8, its extraction is implemented by tilting the panel 9 taking advantage of the free volume present in the blower compartment 5.

[0045] According to a preferred aspect illustrated in Figures 1 and 2, the outer shroud 4 comprises several frames 7 distributed over the circumference of the outer shroud 4 and each delimiting an inspection opening 8. A panel 9 is removably mounted on the internal face 14 of each frame 7 to close the associated inspection opening 8. This makes it possible to provide several accesses to the fan compartment 5 to facilitate inspection or maintenance. In this example, the frames 7 are aligned transversely with respect to the longitudinal axis X to limit the space requirement. Preferably and as illustrated in [Fig. 1], the frame(s) 7 are mounted downstream of the mounting openings 6 to promote the aerodynamics of the unducted fan 1. Alternatively or additionally, one or more frames 7 are mounted upstream of the mounting openings 6. A single frame 7 and a single frame 7 are described below. panel 9, this description being valid for each.

[0046] As illustrated in Figures 3 and 4, the panel 9 covers the entire surface of the inspection opening 8 to close it. The external face of the panel 9 preferably extends in the extension of the frame 7 to promote the aerodynamics of the external shell 4. The external face of the panel 9 is exposed to the external air flow. The first end 10 and the second end 11 of the panel 9 protrude on either side of the inspection opening 8, radially inwards, so that their external face bears against the internal face 14 of the frame 7. The first end 10 and the second end 11 are said to be opposite in that they form two portions of the periphery 12 which are not adjacent and extend substantially opposite each other so as to retain the entire panel 9 against the frame 7. Preferably, the first end 10 and the second end 11 are opposite in a circumferential direction relative to the longitudinal axis.

[0047] Preferably, the first end 10 and the second end 11 of the panel 9 extend over the entire width or over the entire length of the panel 9, in other words form two opposite sides of the panel 9, namely the short sides or the long sides. This allows good support of the panel 9 on the frame 7 and thus promotes plating when the blower 1 is rotated. Preferably and as illustrated in [Fig.5], the entire periphery of the panel 9, formed by the four sides of the panel 9, is in abutment against the internal face 14 of the frame 7 to maximize support and plating.

[0048] According to a first embodiment of the invention illustrated in Figures 3 to 5, the panel 9 is removably mounted on the internal face 14 of the frame 7 by means of fixing elements 16, such as screws, passing through the frame 7 and the first end 10 of the panel 9. One or more other fixing elements 16 pass through the frame 7 and the second end 11 of the panel 9. The fixing elements 16 are driven in from the external face 15 of the frame 7 so as to be able to be easily loosened during maintenance by an operator. Nuts 17, preferably integral with the panel 9, make it possible to tighten the screws 16.

[0049] As illustrated in [Fig. 5], the fixing elements 16 are preferably distributed over the entire periphery 12 of the panel 9 for good mechanical strength. According to a preferred aspect illustrated in [Fig. 5], the periphery 12 of the panel 9 comprises fixing lugs 24 extending in projection and configured to receive the fixing elements 16. This makes it possible to limit the mass of the panel 9 and limit the width, which can facilitate assembly and disassembly.

[0050] According to a second embodiment of the invention illustrated in Figures 6 and 7, the panel 9 is removably mounted on the internal face 14 of the frame 7 by means of movable locking elements 13, such as pivoting cleats. The locking elements 13 make it possible to sandwich the panel 9 at the ends 10, 11 between the locking elements 13 and the frame 7. The locking elements 13 are preferably mounted on the inner face 14 of the frame 7, in this example by screws passing through the frame 7 which allows the locking elements 13 to be pivoted from the outside. A small number of locking elements 13 is required, which can be distributed on two sides of the frame 7 only, and the ends 10, 11 can advantageously be narrower.

[0051] Preferably and as illustrated in [Fig.6], the ends 10, 11 of the panel 9, and preferably all or part(s) of the perimeter 12, are hooked in the shape of a U open towards the outside to cooperate with the frame 7 which is hooked curved towards the inside. This facilitates the positioning of the panel 9 and can allow better fixing as well as sealing, both with the blocking elements 13 and the fixing elements 16.

[0052] According to a preferred aspect illustrated in [Fig.9], the frame 7 (and consequently the panel 9) is oblique, that is to say that it comprises: • two first opposite sides 25, in this example the short sides, extending in an oblique direction Y1 forming an angle a, preferably non-zero, preferably between 5° and 30° relative to a longitudinal direction XI parallel to the longitudinal axis X, and • two second opposite sides 26, in this example the long sides, extending transversely relative to the longitudinal axis X.

[0053] Such an oblique frame 7 and such an oblique panel 9 make it possible to reduce the drag of the air flow at the connections between the frame 7 and the panel 9. Alternatively, as illustrated in [Fig.2], the first opposite sides 25 extend longitudinally.

[0054] According to a preferred aspect illustrated in [Fig.8], the panel 9 comprises a first part 20 on which the first end 10 is formed and a second part 21 on which the second end 11 is formed. The first part 20 and the second part 21 are juxtaposed and their external face extend in the extension of one another to promote the aerodynamics of the external shell 4. The first part 20 comprises a third end 22 opposite the first end 10 and cooperating with a fourth end 23 of the second part 21, opposite the second end 11, in this example by complementarity of shapes. In this example, all or part of the third end 22 is preferably hooked curved inwards and all or part of the fourth end 23 is hooked in the shape of a U open towards the outside.

[0055] Advantageously, during rotation of the blower 1, this makes it possible to press the first part 20 and the second part 21 of the panel 9 together under the effect of centrifugal force without using fixing or blocking elements between the first part 20 and the second part 21 of the panel 9. The parts 20, 21 of the panel 9 are, as previously, removably mounted on the frame 7. In addition, during maintenance, it is sufficient to separate the first part 20 and the second part 21 from the frame 7 to separate the first part 20 from the second part 21. Each part 20, 21 is then extracted from the inspection opening 8, in a simplified manner because they have a smaller dimension than that of an entire panel 9. Advantageously, this solution makes it possible to have a large inspection opening 8. Assembly and disassembly are facilitated.

[0056] The invention has been described for inspection openings 8 and panels 9 of quadrilateral shape, in particular with rounded tops. The invention also applies to inspection openings 8 and panels 9 of different shape, for example oval or elliptical. The first end 10 and the second end 11 may be of different lengths and are said to be substantially opposite in that together they allow the panel 9 to be held on either side against the frame 7. In order to be able to install or extract the panel 9, its greatest width must be less than the greatest length of one of the inspection openings 8 and the internal space available in the fan compartment must allow the panel 9 to be moved and pivoted to make it come out and come in by arranging the greatest width of the panel 9 in the direction of a sufficient length of the inspection opening 8.

[0057] The invention has been presented for inspection openings 8 and panels 9 located downstream of the blades 3 but also applies to inspection openings 8 and panels 9 located upstream of the fan 1. As described previously, the invention also applies to a ducted fan 1 comprising a rotating shroud in which at least one inspection opening 8 is provided.

[0058] The invention also relates to a method of using the blower 1, in which the panel 9 is mounted on the frame 7, as illustrated in Figures 2 and 3 as well as Figures 5 to 9. The rotational drive of the rotary hub 2 has the effect of pressing in an outwardly oriented radial direction the ends 10, 11 of the panel 9 against the internal face 14 of the frame 7. This avoids any risk of losing the panel 9, even if the fixing elements 16 or the locking elements 13 have play.

[0059] The invention also relates to a method for maintaining the blower 1 consisting of removing the panel 9 from the frame 7, by loosening the fixing elements 16 in the example of [Fig. 4] or by pivoting the locking elements 13 in the example of Figures 6 and 7. As illustrated in [Fig. 4], the panel 9 is then extracted from the blower 1 via the inspection opening 8, typically by pivoting it along the diagonal of the frame 7 and taking advantage of the free volume offered by the blower compartment 5. This allows an operator to access the blower compartment 5.

[0060] Once the maintenance or inspection is completed, the panel 9 is inserted into the inspection opening 8, typically by pivoting it diagonally of the frame 7 and taking advantage of the free volume offered by the blower compartment 5. The panel 9 is then remounted on the frame 7, for example by tightening the fixing elements 16 or pivoting the locking elements 13.

Claims

Claims

1. Fan (1) of an aircraft turbomachine (30) comprising a rotating hub (2) along a longitudinal axis (X) and a plurality of blades (3) carried by the rotating hub (2), the fan (1) comprising an outer shroud (4) secured to the rotating hub (2) and a fan compartment (5) defined radially between the rotating hub (2) and the outer shroud (4), the outer shroud (4) comprising: • at least one frame (7) delimiting an inspection opening (8) for accessing the fan compartment (5), • at least one panel (9) removably mounted on the frame (7) to close the inspection opening (8), the fan (1) being characterized in that the panel (9) comprises at least a first end (10) and a second end (11), opposite the first end (10), which extend in abutment against an internal face (14) of the frame (7) turned towards the longitudinal axis (X).

2. A blower (1) according to claim 1, wherein the first end (10) extends over the entire length or width of the panel (9).

3. Blower (1) according to one of claims 1 and 2, in which the panel (9) comprises a periphery (12) comprising the first end (10) and the second end (11), the entire periphery (12) of the panel (9) bearing against the internal face (14) of the frame (7).

4. Blower (1) according to one of claims 1 to 3, in which the frame (7) comprises two sides (25) extending in an oblique direction (Yl) forming an angle (a) relative to a longitudinal direction (XI) parallel to the longitudinal axis (X).

5. Blower (1) according to one of claims 1 to 4, in which the external shell (4) comprises at least one fixing element (16) mounted in a through manner in the frame (7) and in the first end (10) of the panel (9), the fixing element (16) being removable from an external face (15) of the frame (7) opposite the internal face (14).

6. Blower (1) according to one of claims 1 to 4, in which the external shroud (4) comprises at least one locking element (13) movable from an external face (15) of the frame (7) opposite the face internal (14), the first end (10) of the panel (9) being sandwiched between the locking element (13) and the frame (7).

7. Blower (1) according to one of claims 1 to 6, wherein the panel (9) comprises a first part (20) and a second part (21), the first part (20) comprising the first end (10), the second part (21) comprising the second end (11), the first part (20) comprising a third end (22), opposite the first end (10), cooperating with a fourth end (23) of the second part (21), opposite the second end (11).

8. Aircraft turbomachine (30) comprising a fan (1) according to one of claims 1 to 7 and a gas generator driving the fan (1) in rotation.

9. Method for maintaining a blower (1) according to one of claims 1 to 7, consisting of removing the panel (9) from the frame (7) and extracting the panel (9) from the blower (1) via the inspection opening (8).

10. A method of using a blower (1) according to one of claims 1 to 7, wherein the rotational drive of the rotating hub (2) presses the first end (10) and the second end (11) of the panel (9) against the internal face (14) of the frame (7) by centrifugal effect.

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