Fan rotor for turbomachine

Abstract

Fan rotor (4, 5) for a turbomachine comprising: a hub (6); a blade (7) rotatable relative to the hub (6) about an axis (Y) to vary a pitch of the blade (7), the blade (7) comprising a single-piece part (8) made of a woven composite material, the single-piece part (8) comprising a root (12) and an aerodynamic part (10) having an extrados and a intrados; a ball bearing (30) extending about the axis (Y) between the hub (6) and the root (12); and a metal ring (18) extending about the axis (Y), between the bearing and the root 12. Figure for the abstract: Fig. 4

Description

Title of the invention: Fan rotor for a turbomachine FIELD OF THE INVENTION

[0001] The present invention relates to a fan rotor for a turbomachine. STATE OF THE ART

[0002] Fans for a turbomachine comprising a hub and variable-pitch blades are known from the state of the art, the blades each comprising two separate parts: an aerodynamic part made of a composite material, having a lower surface and an upper surface, and a metal blade root used to mount the blade on the hub in a rotatable manner. The assembly of the aerodynamic part with the blade root is achieved by a bonded interface.

[0003] This assembly solution has several drawbacks, including in particular excessive mass, and potential fragility / criticality of the interface due to the transmission of forces between the metal foot and the aerodynamic part, when its setting angle is varied. Statement of the invention

[0004] An aim of the invention is to overcome the aforementioned drawbacks, that is to say to lighten a turbomachine fan while preventing a fan blade from breaking when its pitch angle varies.

[0005] This object is achieved by a fan rotor for a turbomachine, the fan rotor comprising: a hub; a blade rotatable relative to the hub about an axis to vary a pitch of the blade, the blade comprising a single-piece part made from a woven composite material, the single-piece part comprising a root and an aerodynamic part having an extrados and a intrados; a ball bearing extending around the axis between the hub and the root; and a metal ring extending around the axis, between the bearing and the root.

[0006] In the proposed fan rotor, the aerodynamic part and the root are made of a single piece. Consequently, the blade is not subject to the fragilities that would be caused by a bonding interface between these two parts. Furthermore, the fact that the root is made of a composite material in the same way as the aerodynamic part makes it possible to reduce the mass of the blade, and therefore more generally that of the fan.

[0007] The proposed fan rotor may also include the following optional features taken alone or in combination whenever it makes technical sense.

[0008] Optionally, the metal ring has an internal surface defining a space into which the foot extends, the internal surface being oriented to prevent a exit of the foot out of space in a centrifugal direction, when the hub is rotated.

[0009] Optionally, the metal ring is made of titanium or made of an alloy comprising nickel.

[0010] Optionally, the composite material is woven in 3D.

[0011] Optionally, the metal ring comprises two shells respectively delimiting two complementary portions of the internal surface, and the fan rotor further comprises a hoop extending around the metal ring to keep the two shells in contact with each other.

[0012] Optionally, the ball bearing is in contact with the hoop.

[0013] Optionally, the fret is metallic.

[0014] Also provided is a turbomachine engine comprising one or more fan rotors according to the preceding description.

[0015] Further provided is a method of manufacturing the aforementioned fan rotor, the manufacturing method comprising cooling the metal ring, then positioning the hoop around the metal ring, such that subsequent heating of the metal ring expands the two shells so that the two shells are clamped by the hoop. DESCRIPTION OF FIGURES

[0016] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0017] [Fig.l] is a perspective view of a turbomachine according to one embodiment.

[0018] [Fig.2] is a side view of a blade according to one embodiment.

[0019] [Fig. 3] is a partial longitudinal sectional view of a fan portion according to one embodiment.

[0020] [Fig.4] is a partial cross-sectional view of a fan portion according to the embodiment of [Fig.3].

[0021] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0022] With reference to [Fig.l], a turbomachine comprises an engine 1 of the “open rotor” type. The engine 1 comprises a casing 2 and a fan 3.

[0023] The casing is a nacelle 2 intended to be fixed to a fuselage of an aircraft.

[0024] The blower 3 is not ducted.

[0025] The fan 3 comprises two counter-rotating fan rotors 4 and 5. In other words, when the engine 1 is in operation, the rotors 4 and 5 are driven in rotation relative to the nacelle 2 around the same axis of rotation X (which coincides with a main axis of the engine).

[0026] The engine 1 as shown in [Fig.l] is in a configuration commonly referred to as a “pusher” (i.e. the fan 3 is placed at the rear of a power generator with an air inlet located upstream, on the right in [Fig.l]). However, the engine 1 can alternatively be in a “puller” configuration (i.e. the fan is placed upstream of the power generator with an air inlet located before, between or just behind the two fan rotors). The engine 1 can also have a still different architecture, such as an architecture comprising a fan rotor comprising moving blades and a fan stator comprising fixed blades (USF configuration), or a single fan rotor (TP configuration). The invention can also be applied to a turbomachine with a ducted fan but also with variable pitch.

[0027] In [Fig.l], each fan rotor 4, 5 comprises a hub 6 mounted to rotate on the casing 2 around the axis X, and further comprises a plurality of blades 7. The blades 7 extend substantially radially relative to the axis of rotation X of the hub 6.

[0028] The blades 7 are mounted on the hub 6 not in a fixed manner, but in a mobile manner, so as to be able to vary their pitch (this is then referred to as a variable pitch blade).

[0029] In the following, the characteristics of a blade 7 will be detailed, knowing that this description is applicable to all the other blades of the fan 3.

[0030] With reference to [Fig.2], the blade 7 comprises a single-piece part 8, this single-piece part 8 comprising an aerodynamic part 10 and a root 12 (shown in gray).

[0031] The single-piece part 8 comprising the aerodynamic part 10 and the foot 12 is made of a woven composite material. Such a material has the advantage of being lighter than a metal while offering interesting mechanical performance. Preferably, it is a 3D woven material, because a 3D weave gives the part better resistance to delamination than a 2D woven material.

[0032] As the part 8 is a single piece, the root 12 and the aerodynamic part 10 are not assembled into each other as can be seen in certain blades known from the state of the art. There is therefore no bonding interface between the root 12 and the aerodynamic part 10. In reality, the single piece 8 is manufactured from a single woven preform, made from a composite material.

[0033] The aerodynamic part 10 is intended to be immersed in an air flow when the turbomachine is in operation, in order to generate thrust. The aerodynamic part 10 comprises a mutually opposite extrados and intrados. The part aerodynamic 10 further comprises a leading edge 14 and a trailing edge 16 opposite the leading edge 14, these two edges 14, 16 each connecting the intrados to the extrados.

[0034] The foot 12 is a part of the part used for mounting the blade in the hub 6. For this purpose, it is located inside a cavity formed in the hub 6.

[0035] With reference to figures 3 and 4, the blade 7 extends radially along a setting axis Y perpendicular to the rotation axis X. The blade 7 is movable in rotation relative to the hub 6 around the setting axis Y (it is therefore by rotation around this setting axis Y that the setting angle of the blade 7 can be varied).

[0036] The foot 12 constitutes an end portion of the blade 7 which is closest to the hub 6 (and therefore closest to the axis of rotation X).

[0037] The foot 12 has a bulb-shaped profile, which flares in a centripetal direction (therefore along the alignment axis Y, towards the rotation axis X). This flare is observed in a section plane of the foot parallel to the plane (X, Y) (see [Fig. 3]) and in a section plane perpendicular to the rotation axis X (see [Fig. 4]). Thus, the foot 12 has two opposite sides which move away from each other in the centripetal direction.

[0038] The blower 3 also comprises a metal ring 18.

[0039] The metal ring 18 extends around the setting axis Y, between the foot 12 and the hub 6.

[0040] The metal ring 18 has an internal surface 20 and an external surface 22 opposite the internal surface 20.

[0041] The internal surface 20 of the metal ring 18 delimits a space in which the foot 12 of the blade is received.

[0042] The internal surface 20 comprises inclined faces relative to the wedging axis Y so as to prevent the foot 12 from exiting the space in a centrifugal direction, when the hub 6 is rotated relative to the casing 2. The two inclined faces are arranged to be mutually opposite.

[0043] The two inclined sides end with ends which delimit an upper passage crossed by the blade 7.

[0044] The blower 3 has a profile in a section plane containing the setting axis Y in which the two inclined sides of the internal surface 20 approach each other in a centrifugal direction (therefore along the setting axis Y and moving away from the rotation axis X). In the embodiment illustrated in the figures, this section plane is a transverse section plane perpendicular to the rotation axis X (see [Fig.4]). In this transverse section plane, the two inclined sides are rectilinear. In the transverse section plane, the upper passage has a width which is less than a maximum width of the bulb of the foot 12.

[0045] The two inclined sides can be complementary on the two opposite sides of the foot. 12 which flare in the centripetal direction (along the setting axis X, towards the rotation axis Y). In this way, a non-point contact can be ensured in the section plane considered between the two inclined sides of the internal surface 40 and the opposite flared sides of the root 12. When the fan is rotating, the opposite sides of the root 12 respectively bear on the inclined sides of the surface 20 under the effect of centrifugal force, but the blade 7 cannot exit through the upper passage since these sides approach each other in the centrifugal direction.

[0046] In the longitudinal sectional plane of [Fig. 3], that is to say a sectional plane parallel to the plane (X, Y), the two inclined sides have end portions which move away from each other in the centrifugal direction (therefore along the setting axis Y and away from the rotation axis X). These end portions by the aforementioned ends which delimit the upper passage crossed by the blade 7.

[0047] Thus, the surface 20 of the embodiment illustrated in FIGS. 3 and 4 is not of revolution around the alignment axis Y, since the mutual approximation of the inclined sides is observed in the transverse section plane but not in the longitudinal section plane.

[0048] The metal ring 18 comprises two shells 18a, 18b delimiting two complementary portions of the internal surface 20. The two shells 18a, 18b extend over two complementary angular sectors around the setting axis Y. For example, the two shells 18a, 18b are half-shells, each extending 180° degrees around the setting axis Y.

[0049] The metal ring 18 is made of titanium or an alloy comprising nickel, such as inconel.

[0050] The fan 3 further comprises a hoop 24 surrounding the metal ring 18. The hoop 24 extends around the setting axis Y. The hoop 24 holds the two shells 18a, 18b against each other in a position where the internal surface 20 of the closed ring 18 is closed on itself around the setting axis Y.

[0051] The two shells 18a, 18b can be co-molded, added-glued or simply held by the hoop 24.

[0052] The hoop 24 has an internal surface 26 and an external surface 28 opposite the internal surface. The internal surface 26 is pressed against the external surface 22 of the ring 18, on each of the two shells 18a, 18b.

[0053] The hoop 24 is made of metal. The hoop 24 is for example made of the same material as the metal ring 18.

[0054] The blower 3 further comprises a ball bearing 30. The ball bearing 30 extends around the setting axis Y, between the hub 6 and the foot 12. More precisely, the ball bearing 30 is located between the hub 6 and the metal ring 18. Even more precisely, the bearing is located between the hub 6 and the hoop 24.

[0055] Conventionally, the ball bearing comprises an outer ring, an inner ring, and balls between the inner ring and the outer ring. The outer ring of the bearing is fixed to the hub 6. The inner ring is fixed to the hoop 24. In this way, the ball bearing 30 allows rotation of the assembly "hoop 24 + metal ring 18 + blade 7" around the setting axis Y relative to the hub 6, thus causing a variation in the setting angle of the blade 7, and this with limited friction.

[0056] The fan 3 may comprise several ball bearings, arranged in different positions along the setting axis Y of the blade 7 as shown in FIGS. 3 to 4, but a single ball bearing 30 may suffice.

[0057] In the embodiment shown in Figures 3 and 4, two parts are arranged between the bearing and the blade root 12: the metal ring 18 and the hoop 24. In another embodiment, only the metal ring is arranged between the bearing and the blade root 12.

[0058] The metal ring 18, the hoop 24, the or each ball bearing 30 described above may be part of the fan rotor 4 or of the fan rotor 5. In particular, the two fan rotors 4 and 5 may comprise these characteristics.

[0059] In the preceding description, the non-limiting example of an unducted fan 3 has been taken, comprising two rotors 4, 5. In other embodiments, the fan 3 comprises a single fan rotor and / or is ducted.

Claims

Claims

1. Fan rotor (4, 5) for a turbomachine, the fan rotor (4, 5) comprising: • a hub (6), • a blade (7) rotatable relative to the hub (6) about an axis (Y) to vary a pitch of the blade (7), the blade (7) comprising a single-piece part (8) made of a woven composite material, the single-piece part (8) comprising a root (12) and an aerodynamic part (10) having an extrados and a intrados, • a ball bearing (30) extending about the axis (Y) between the hub (6) and the root (12), • a metal ring (18) extending about the axis (Y), between the bearing and the root (12).

2. Fan rotor (4, 5) for a turbomachine according to the preceding claim, in which the metal ring (18) has an internal surface (20) delimiting a space (19) in which the foot (12) extends, the internal surface (20) being oriented to prevent the foot (12) from exiting the space (19) in a centrifugal direction, when the hub (6) is rotated.

3. Fan rotor (4, 5) for a turbomachine according to any one of the preceding claims, in which the metal ring (18) is made of titanium or made of an alloy comprising nickel.

4. Fan rotor (4, 5) for a turbomachine according to any one of the preceding claims, in which the composite material is woven in 3D.

5. Fan rotor (4, 5) for a turbomachine according to any one of the preceding claims, in which the metal ring (18) comprises two shells (18a 18b) respectively delimiting two complementary portions of the internal surface (20), the fan rotor (4, 5) further comprising a hoop (24) extending around the metal ring (18) to keep the two shells (18a, 18b) in contact with each other.

6. Fan rotor (4, 5) for a turbomachine according to the preceding claim, in which the ball bearing (30) is in contact with the fret (24).

7. Fan rotor (4, 5) for a turbomachine according to any one of claims 5 and 6, in which the hoop (24) is metallic.

8. Turbomachine engine (1) comprising a fan rotor (4, 5) according to any one of the preceding claims.

9. A method of manufacturing a fan rotor (4) for a turbomachine according to any one of claims 5 to 7, the manufacturing method comprising cooling the metal ring (18), then positioning the hoop (24) around the metal ring (18), so that subsequent heating of the metal ring (18) expands the two shells so that the two shells are clamped by the hoop (24).

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