Turbomachine rotor with blade axial retention device

Abstract

One aspect of the invention relates to a turbomachine rotor (20), wherein each blade (40) comprises: - an airfoil (50) extending radially with respect to the axis (X); - a root (80) extending radially from the airfoil (50) and configured to be mounted in a respective recess (31) of the disk (30), wherein the rotor (20) comprises upstream and downstream axial retention means configured to axially retain the roots (80) of the blades (40) in the recesses (31) of the disk (30), the downstream axial retention means comprising tabs (100) and a plurality of hooks (34) belonging to the disk (30), each hook (34) being configured to provide radially outer retention of the tab (100).

Description

DESCRIPTION TITLE: Aircraft Turbomachine Blade Axial Stop Device TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of aircraft turbomachinery.

[0002] The present invention relates to a turbomachine rotor comprising a blade and a disk and an axial stopping means for the blade and in particular an axial stopping means bearing on the blade and on the disk. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Aircraft turbomachinery typically comprises several modules, such as a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine followed by a low-pressure turbine, which drives the corresponding low-pressure or high-pressure compressor, and a gas ejection system. Each turbine consists of one or more stages, each stage comprising successively a fixed blade wheel, called a distributor, and a rotating blade wheel, called a rotor.

[0004] In this application, the terms "external" and "internal," "upper" and "lower," "outer" and "inner" refer to the position of a part or surface relative to the longitudinal axis of the turbomachine. Furthermore, the terms "radial" and "axial" refer respectively to an axial direction, parallel to the longitudinal axis of the turbomachine, and a radial direction, i.e., perpendicular to the longitudinal axis of the turbomachine. Additionally, the terms "upstream" and "downstream" refer to the direction of airflow within the turbomachine, from left to right in the figures of this application, as illustrated in Figure 2 by an arrow.

[0005] Figure 1 is an axial cross-sectional view of part of a prior art turbine rotor, taken at one of the blade roots mounted circumferentially around a rotor disk.

[0006] With reference to Figure 1, the fixed vanes 11 of the distributor are joined together at their radially internal ends by annular sectors placed circumferentially end to end so as to form an internal ferrule 12 and are mounted at their radially external ends on a housing (not shown) of the turbine.

[0007] Furthermore, the rotor comprises a disc 3 having, at its outer periphery, teeth defining recesses in which the movable blades 4 are engaged by their respective feet 8. Each movable blade 4 comprises a blade 5 equipped with a platform 6 connected to a strut 7 which is extended radially by a foot 8. The feet 8 of the movable blades 4 are retained radially in the recesses of the disc 3 by their bulbous, dovetail-shaped cross-section and axially by an annular ring 14 bearing axially against the upstream face of the feet 8 of the movable blades 4. The annular ring 14 is held radially in upstream grooves 6c formed at the level of the inner faces of the platforms 6 and axially by an upstream annular flange 15 fixed to the disc 3.

[0008] To improve the turbomachine's performance and prevent the disc 3 from overheating due to the flow of hot gases from the upstream combustion chamber flowing through the turbine's flow channel 9, it is important to minimize the radial flow of these gases from the outside to the inside, i.e., from the channel 9 to the area 10 located between the platforms 6 of the moving blades 4 and the disc 3. Indeed, the portion of the gases from channel 9 flowing radially under the platforms 6 does not contribute to the rotation of the moving blades 40 and directly heats the teeth of the disc 3. Furthermore, the cooling of the disc 3 and the feet 8 of the moving blades 4 is ensured by orifices (not shown) in the upstream flange 15, which direct a flow of cold air to the bottom of the disc 3's recesses. Therefore, it is also necessary to limit the flow path of cold air radially from the inside to the outside.

[0009] To limit the circulation of gases between the vein 9 and the zone 10 located between the platforms 6 of the moving blades 4 and the disk 3, it is known to equip the platform 6 of each moving blade 4 with an upstream spoiler 6a and a downstream spoiler 6b which define a sealing baffle, respectively, with a downstream spoiler 13b and an upstream spoiler 13a formed in axial projection on the annular sectors of the internal ferrules 12 located, respectively, upstream and downstream of the rotor.

[0010] In addition, the sealing between the platforms 6 is ensured by sealing plates 18, also called "candies", which are mounted between the movable blades 4, in lateral cavities 19 provided in the struts 7 of the movable blades 4. In particular, each sealing plate 19 is mounted between two circumferentially adjacent movable blades 4 and comprises a circumferential end portion housed in the lateral cavity 19 of one movable blade 4 and an opposite circumferential end portion housed in the lateral cavity 19 of the circumferentially adjacent movable blade 4. These sealing plates 18 conform with small gaps to the internal shape of the lateral cavities 19. In operation, these sealing plates 18 are subjected to centrifugal forces and are pressed radially against the internal faces of the main walls of the platforms 6, thus preventing the radial passage of hot gases from the vein to the zone 10 located radially under the platforms.

[0011] Furthermore, each movable blade 4 has an upstream wall 16a and a downstream wall 16b extending radially between the foot 8 and the platform 6 of each movable blade 4 which encompass and limit the bypass of the gas flow in the channel 9. In addition, the upstream walls 16a and downstream walls 16b limit gas leaks from the channel 9 which would bypass the movable blade 4 by passing through the foot 6 of the movable blade 4.

[0012] Furthermore, in addition to ensuring sealing within the turbine, reducing the mass of the turbomachine's constituent elements is a constant concern that has led to the development of blades made of ceramic matrix composite material, known as CMC.

[0013] While the use of CMC material reduces blade weight and increases resistance to high temperatures, it also necessitates a redesign of the moving blade geometry due to the constraints of the CMC manufacturing process. Indeed, producing a moving blade with a platform exhibiting a structure similar to the one described previously proves complex, as such a structure generates problems with fiber twisting during manufacturing. Of course, this issue of simplifying platform structures can also arise with other types of blades.

[0014] To overcome this problem, it was proposed in patent application FR3108941A1 "TURBINE ROTOR FOR TURBOMACHINE, METHOD OF ASSEMBLING SAID ROTOR" to use slats 103 and 104 distributed circumferentially around the disk and axially blocking each blade foot mounted in a cavity of the disk, the slat being held axially, at one radial end, by a downstream radial hook 33 of the disk and at the other radial end, by the platform 60 of the blade 40 in a radial groove 62-2 of a downstream rim 62 of the platform 60.

[0015] One problem with this solution is that the blades bear against the vanes in the radial direction, thus mechanically reloading the vanes. When the vanes are made of CMC (carbon fiber composite), finding a solution to this problem is even more critical because the blades, held radially by the vanes, impose stresses on the vanes that are unsuitable for this material.

[0016] Therefore, there is a need to propose a means of radial retention of slats that does not mechanically recharge the blades. SUMMARY OF THE INVENTION

[0017] The invention offers a solution to the problems mentioned above, by allowing the blades to be mechanically unloaded compared to the prior art by means of hooks.

[0018] One aspect of the invention relates to a turbomachine rotor extending around an axis and comprising: a disk centered on the axis and having alveoli and teeth formed on an outer periphery of the disk, the alveoli being distributed circumferentially around the disk and the teeth each being circumferentially delimited by two circumferentially adjacent alveoli, a plurality of blades, each blade comprising: a blade that extends radially with respect to the axis, a foot that extends in the radial line of the blade and is configured to be mounted in a respective recess of the disc, a platform situated radially between the blade and the base of the blade and comprising at least one inner face including a radial groove at its downstream end, in which the rotor includes upstream and downstream axial retention means configured to axially retain the blade roots in the disk recesses, characterized in that the downstream axial retention means comprise at least a plurality of slats circumferentially distributed around the axis of the disk and a plurality of hooks belonging to the disk, each slat of the plurality of slats comprising a radially external end disposed in the radial groove of the inner face of the platform, each hook of the plurality of hooks being configured to: receive a radially internal end of a slat of the plurality of slats so that the slat is opposite at least one cavity of the disk so as to axially block the foot of a blade mounted in said cavity of the disk and to achieve external radial retention of the lamella, radially outside the lamella.

[0019] Thanks to the invention, the hooks, radially external protrusions located on the disc, retain the blades axially at their radially internal portion. This allows for at least partial mechanical unloading of the blades against which the blades bear via their radially external end. Thus, even when using ceramic matrix blades, the mechanical load associated with the blades is not problematic for the blade structure, because the blades are also retained in the external radial direction by the disc's hooks.

[0020] In addition to the characteristics mentioned in the preceding paragraph, the turbomachine rotor according to one aspect of the invention may have one or more additional characteristics from among the following, considered individually or in all technically possible combinations: The external radial retention of each lamella is achieved by a hook which has a portion that projects upstream so as to form an axial groove of the hook open upstream, the radially internal end of each lamella comprising a portion that projects downstream and is configured to be received in the axial groove of the hook. Each hook projects radially outwards from a downstream face of the disc. Each hook extends radially outwards from a tooth of the disc. Each hook extends radially outwards from a part of the disc located radially further inwards relative to the teeth of the disc. the plurality of hooks forms a first plurality of hooks and further comprising a second plurality of hooks, each hook of the second plurality of hooks extending radially outwards from a tooth of the disc and achieving only axial retention of at least one lamella. Each slat comprises a radially external part and a radially internal part, the radially external part being configured to bear on two circumferentially adjacent hooks of the second plurality of hooks, the radially internal part being configured to bear on two circumferentially adjacent hooks of the first plurality of hooks. Each lamella in the plurality of lamellae has a beak that extends axially downstream. The blades and the vanes are made of different materials. The blades are made from a ceramic matrix material and the vanes are made from a metallic material. The upstream axial retention means include an upstream flange mounted against the rotor disc, the upstream flange being configured to axially retain the blade feet in the disc recesses. The upstream flange is mounted against one upstream face of the disc. The upstream flange is fixed to the disc by a locking ring housed in an annular groove of the disc, the annular groove of the disc being open downstream.

[0021] Another aspect of the invention relates to an aircraft comprising a turbomachine, the turbomachine comprising the rotor according to the invention.

[0022] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0023] The figures are presented for illustrative purposes only and are in no way limiting to the invention. Figure 1 shows a schematic representation of an axial cross-sectional view of a portion of a rotor, according to the prior art, Figure 2 shows a schematic representation of an axial cross-sectional view of a portion of a rotor, according to the prior art, taken at the level of a blade root mounted in a recess of the rotor disk, Figure 3 shows a schematic representation of an axial cross-sectional view of a portion of a rotor according to a first embodiment of the invention, Figure 4 shows a schematic representation of a magnified axial cross-sectional view of a portion of a rotor according to a first embodiment of the invention, Figure 5 shows a schematic representation of an axial cross-sectional view of a portion of a rotor according to a second embodiment of the invention, Figure 6 shows a schematic representation of a perspective view, from downstream of the turbomachine, of a portion of a rotor according to a second embodiment of the invention, Figure 7 shows a schematic representation of an axial cross-sectional view of a portion of a rotor according to a third embodiment of the invention, Figures 8 and 9 show schematic representations of a perspective view, from downstream of the turbomachine, of a downstream flange of a rotor according to the invention. DETAILED DESCRIPTION

[0024] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0025] The invention is a 20-rotor turbomachine, preferably an aircraft turbomachine.

[0026] It is recalled that a turbomachine generally comprises, from upstream to downstream in the direction of the gas flow, a blower, one or more stages of compressors, for example a low pressure compressor and a high pressure compressor, a combustion chamber, one or more stages of turbines, for example a high pressure turbine and a low pressure turbine, and a gas exhaust nozzle.

[0027] Figure 3 shows a schematic representation of an axial cross-sectional view of part of a high or low pressure turbine rotor of the turbomachine, according to a first embodiment of the invention.

[0028] In the rest of the description, the term "blade" will be used to refer to a moving rotor blade.

[0029] With reference to Figure 3, each blade 40 comprises a blade 50 connected by a platform 60 to a median portion or stilt 70 which is extended radially by a foot 80. Thus, the platform 60 is located radially between the blade 50 and the foot 80 of the blade 40.

[0030] The feet 80 of the blades 40 are engaged in recesses 31 formed in the outer periphery of a disc 30. The recesses 31 are regularly distributed around the axis X of rotation of the rotor 20 and delimit between them teeth 32.

[0031] The feet 80 of the blades 40 are held radially in the recesses 31 by their bulbous, dovetail-shaped cross-section. Furthermore, the feet 80 of the blades 40 are held axially in the recesses 31 of the disc 30 by axial retention means.

[0032] The axial retention means of the blade 40 in the disc 30 include upstream axial retention means and downstream axial retention means.

[0033] The invention relates to downstream axial retention means. The invention can therefore be implemented with any upstream axial retention means. For example, and as shown in all embodiments, but without limitation, the upstream axial retention means are formed by an upstream flange 97.

[0034] The upstream flange 97 is fixed to the disc 30 of the rotor 20 and is in the form of a part of revolution, whose axis of revolution coincides with the axis of rotation X of the rotor 20. The upstream flange 97 is for example fixed to the disc 30 by a plurality of screws (as shown in Figures 8 and 9), by a ring housed in an internal annular groove 36 of the disc 30, or by any other means of fixing.

[0035] The downstream axial retention means comprise downstream lamellae 100 arranged downstream of the disc 30 and radially external and internal retention means enabling the said downstream lamellae 100 to be held radially and axially in relation to the alveoli 31 of the disc 30.

[0036] In one embodiment of the invention, the blades 100 have an annular downstream spoiler 105 that defines a sealing baffle with an upstream spoiler formed as an axial projection on the annular sectors of the inner ferrules located downstream of the rotor 20. The overlap of the downstream spoiler 105 formed in the blades 100 and the upstream spoiler formed in the inner ferrule limits the passage of hot gases radially from the outside to the inside, i.e., from the annular flow channel of the hot gas stream towards the area located between the platform 60 of the blades 40 and the disc 30, and conversely, a flow of cold air radially from the inside to the outside. Such blades 100 with a spoiler 105 are schematically represented in Figures 5 and 6.

[0037] The invention relates in particular to radially external retaining means for the slats 100. These radially external retaining means exert an inward radial force on the slats 100 to ensure that the slats 100 are held in position and prevent displacement of the slats 100 in the radially outward direction. In a first embodiment, these radially external retaining means are schematically shown in detail in Figure 4. External radially restraining means include a combination of two means.

[0038] A first radially external retaining means is formed by hooks 34 belonging to the disc 30. The hooks 34 are outgrowths extending at least in one radially external direction. The hooks 34 further include an upstream-facing notch 341, that is to say, an axially projecting portion 341 facing upstream, the axially projecting portion 341 forming an axial groove 342 of the hook 34 open towards the upstream side. The axial groove 342 allows, in combination with the radially internal end of the lamellae 100, a radially external retention of the lamellae 100. For this, the lamellae 100 include a step towards the downstream, i.e. an axially projecting portion 102 over at least part of their width, the axially projecting portion 102 being configured to be received by the axial groove 342 of the hook 34 open towards the upstream.The hooks 34 are included in the disc 30, and preferentially each individually form part of a tooth 32 of the disc 30, that is to say raised parts delimiting the alveoli 31.

[0039] In a second embodiment of the first radially external retaining means, schematically represented in Figure 7, the hooks 34 are included within the disc 30, but are not part of a tooth 32 of the disc 30. Rather, the hooks 34 are located on a radially internal portion of the disc 30, that is, closer to the axis of rotation X of the rotor 20 than when they are placed on a tooth 32 of the disc 30. The hooks 34 are then positioned in radial alignment with the radially internal grooves 63 of the platforms 60 so that the slats 100 are vertical when mounted in the rotor 20. In this second embodiment, the disc 30 may include a second hook 35.This hook 35, as shown in Figure 7, may include an axial groove identical or similar to that of the hooks 34, or may extend only in a radially external direction, i.e., without a downstream projection and therefore without an upstream open axial groove like the hooks 34 (not shown). In all cases, the lamella 100 includes only a projecting portion 102, in order to avoid hyperstatic cases. The hooks 34, being radially more internal than the hooks 35, then provide radially internal retention of the lamellae 100, in combination with the projecting portion 102 cooperating with the internal groove of the hooks 34. In this embodiment, the lamellae 100 may have a substantially different shape. rectangular with a center of narrowed width, that is to say, a head, or radially external portion 106, configured to rest on two adjacent central radial hooks 35, and feet, or radially internal portion 107 configured to rest on two circumferentially adjacent hooks 34, the head and feet being separated by a radially central portion of narrowed width corresponding to the width separating two central radial hooks 35.

[0040] A second radially external retaining means in the invention is formed by internal radial grooves 63 provided in the internal faces of the downstream ends (or edges) 62 of the platforms 60. Thus, when the platforms 60 are arranged circumferentially end to end, the radial grooves 63 placed end to end form an annular radial groove.

[0041] The combination of the first and second means of radially external support makes it possible to reduce the mechanical force imposed on the blade 40 by the support of the slats 100 on the platform 60 in the annular radial groove 62, because part of this mechanical force is transmitted to the projecting portion 341 upstream of the hooks 34 via the projecting portion downstream 102 of the radially internal end of the slats 100.

[0042] The hooks 34 also form radially internal retaining means. Indeed, the radially internal end of each lamella 100 is held, at the level of its radially external end, by the base of the hook, the protruding portion 102 downstream of the lamella 100 being received in the axial groove 342 and resting on the base of the hook 34.

[0043] Furthermore, the slats 100 are arranged opposite the alveoli 31 of the disc 30 so as to axially lock the feet 80 of the blades 40 in said alveoli 31.

[0044] In an advantageous embodiment of the invention, the slats 100 have the general shape of a T. The head, or radially external portion, of the slats 100 is configured to face the downstream face of at least two circumferentially adjacent stilts 70. Each head of the slats 100 is thus radially supported against two adjacent hooks 34 of the disc 30.

[0045] Furthermore, the foot of the blades 100 is positioned between two circumferentially adjacent hooks 34, opposite a foot 80 of the blade 40. Thus, the foot of Each of said slats 100 forms a lug which is circumferentially butted against a hook 34 so as to block said slat 100 from rotation.

[0046] Advantageously, the upstream flange 97 and / or the downstream flange 98 when it exists and / or the slats 100 have orifices (not illustrated) which ensure the delivery of a flow of cold air to the bottom of the alveoli 31 of the disc 30 so as to ensure the cooling of the disc 30 and the feet 80 of the movable blades 40.

[0047] Advantageously, the blades 40 and the vanes 100 are made of different materials. For example, the blades 40 are made of a ceramic matrix composite (CMC), while the vanes 100 are made of a metallic material. In an alternative embodiment, the blades 40 and the vanes 100 are made of the same material, for example, a ceramic matrix composite.

Claims

DEMANDS

1. Rotor (20) of a turbomachine (1) extending about an axis (X) and comprising: - a disk (30) centered on the axis (X) and comprising alveoli (31) and teeth (32) formed on an external periphery of the disk (30), the alveoli (31) being distributed circumferentially around the disk (30) and the teeth (32) each being circumferentially delimited by two circumferentially adjacent alveoli (31), - a plurality of dawns (40), each dawn (40) comprising: o a blade (50) which extends radially with respect to the axis (X), o a foot (80) which extends in the radial continuation of the blade (50) and which is configured to be mounted in a respective recess (31) of the disk (30), o a platform (60) located radially between the blade (50) and the foot (80) of the blade (40) and comprising at least one inner face (62) including a radial groove (63) at its downstream end, - in which the rotor (20) includes upstream and downstream axial retention means configured to axially retain the feet (80) of the blades (40) in the recesses (31) of the disk (30), - characterized in that the downstream axial retention means comprise at least a plurality of lamellae (100) circumferentially distributed around the axis (X) of the disk (30) and a plurality of hooks (34) belonging to the disk (30), each lamella (100) of the plurality of lamellae comprising a radially external end disposed in the radial groove (63) of the inner face (62) of the platform (60), each hook (34) of the plurality of hooks (34) being configured to: to receive a radially internal end (102) of a slat (100) of the plurality of slats so that the slat (100) is opposite at least one cavity (31) of the disc (30) so as to axially block the foot (80) of a blade (40) mounted in said cavity (31) of the disc (30) and to achieve external radial retention of the lamella (100), radially outside the lamella (100).

2. Rotor (20) of turbomachine (1) according to claim 1 wherein the external radial retention of each slat (100) is achieved by a hook (34) which has a portion which projects upstream (341) so as to form an axial groove (342) of the hook (34) open upstream, the radially internal end (102) of each slat (100) comprising a portion which projects downstream and which is configured to be received in the axial groove (342) of the hook (34). [Claims] Turbomachine rotor (20) according to any one of the preceding claims wherein each hook (34) projects radially outwards from a downstream face of the disk (30).

4. Rotor (20) of turbomachine (1) according to claim 3 in which each hook (34) extends radially outwards from a tooth (32) of the disc (30). [Claims] Rotor (20) of turbomachine (1) according to claim 3 in which each hook (34) extends radially outwards from a portion of the disk (30) located radially further inwards with respect to the teeth (32) of the disk (30). [Claims] Rotor (20) of turbomachine (1) according to claim 5 wherein the plurality of hooks (34) forms a first plurality of hooks (34) and further comprising a second plurality of hooks (35), each hook (35) of the second plurality of hooks (35) extending radially outwards from a tooth (32) of the disc (30) and achieving only axial retention of at least one lamella (100).

7. Rotor (20) of turbomachine (1) according to claim 6 in which each blade (100) comprises a radially external part (106) and a radially internal part (107), the radially external part (106) being configured to bear on two circumferentially adjacent hooks (35) of the second plurality of hooks (35), the radially internal part (107) being configured to bear on two circumferentially adjacent hooks (34) of the first plurality of hooks (34). [Claims] Rotor (20) of turbomachine (1) according to any one of the preceding claims wherein each slat (100) of the plurality of slats has a spoiler (105) which extends axially downstream. [Claims] Rotor (20) of turbomachine (1) according to any one of the preceding claims wherein the blades (40) and the vanes (100) are made of different materials.

10. Rotor (20) of turbomachine (1) according to claim 6 wherein the blades (40) are made from a ceramic matrix material and the vanes (100) are made from a metallic material.

11. Turbomachine rotor (20) according to any one of the preceding claims wherein the upstream axial retention means comprise an upstream flange (97) mounted against the rotor disc (30) (20), the upstream flange (97) being configured to axially retain the feet (80) of the blades (40) in the recesses (31) of the disc (30).

12. Rotor (20) of turbomachine (1) according to claim 8 in which the upstream flange (97) is mounted against an upstream face of the disk (30).

13. Rotor (20) of turbomachine (1) according to claim 8 or 9 wherein the upstream flange (97) is fixed to the disc (30) by a locking ring housed in an annular groove (36) of the disc (30), the annular groove (36) of the disc (30) being open downstream.

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