Aircraft turbomachine blade axial stopping device

Abstract

One aspect of the invention relates to a turbomachine rotor (20) in which each blade (40) comprises: a blade (50) extending radially about the axis (X), a foot (80) extending radially from the blade (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 feet (80) of the blades (40) in the recesses (31) of the disk (30), the downstream axial retention means comprising slats (100) and a plurality of hooks (34) belonging to an added component fixed to the disk (30), each hook (34) being configured to provide external radial retention of the slat (100). Figure to be published with the abstract: Figure 3

Description

Title of the invention: Aircraft turbomachine blade axial stopping 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 supported 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 drive the corresponding low-pressure or high-pressure compressor, and a gas ejection system. Each turbine is formed of one or more stages, each stage successively comprising 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" are used with reference to the position of a part or surface relative to the longitudinal axis of the turbomachine. Furthermore, the terms "radial" and "axial" correspond 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. In addition, the terms "upstream" and "downstream" are used with reference to the direction of airflow within the turbomachine, from left to right in the figures of this application, as illustrated in [Fig. 2] by an arrow.

[0005] Figure 1 is an axial cross-sectional view of a portion of a turbine rotor according to art anterior, taken at the level of one of the blade feet mounted circumferentially around a rotor disc.

[0006] With reference to [Fig. 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 stilt 7 which is extended radially by a foot 8. The feet 8 of the movable blades 4 are retained radially in the alveoli of the disk 3, by their bulbous section, known as dovetail and axially, by an annular ring 14 in axial buttress 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 internal faces of the platforms 6 and axially by an upstream annular flange 15 fixed to the disk 3.

[0008] In order to improve the performance of the turbomachine and to prevent the disk 3 from heating up 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 disk 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 disk 3. Furthermore, the cooling of the disk 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 disk 3's recesses. Therefore, it is also necessary to limit the passage of cold air flow 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] Furthermore, the seal 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 formed 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 clearances to the internal shape of the lateral cavities 19.In operation, these sealing plates 18 are subjected to centrifugal forces and are radially pressed against the inner 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 below the platforms.

[0011] In addition, 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 flowing in the channel 9. Furthermore, 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 the weight of the blades and increases their resistance to high temperatures, it also necessitates a revision of the geometry of the moving blades 4 due to the constraints of the manufacturing process for parts in CMC. Indeed, it proves complicated to produce a moving blade with a platform that has a structure similar to that described above because such a structure generates, in particular, problems with fiber twisting during its manufacture. Of course, this problem of simplifying the platform structure can also arise with other types of blades.

[0014] To overcome this problem, it was proposed in patent application FR3108941Al "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 slats bear against the blades in the radial direction and therefore mechanically load the blades. When the blades are made of CMC, it is even more important to find a solution to this problem because the slats held radially by the blades impose stresses on the blades that are unsuitable for this material.

[0016] There is therefore 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 disc centered on the axis and comprising alveoli and teeth formed on an external periphery of the disc, the alveoli being distributed circumferentially around the disc and the teeth each being circumferentially delimited by two circumferentially adjacent alveoli, • a plurality of dawns, each dawn 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, • wherein the rotor comprises 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 disc and a retaining assembly which has a hook shape, the retaining assembly preferably comprising a hook, and in that the retaining assembly belongs to an added part fixed to the disc, each slat of the plurality of slats comprising a radially external end disposed in the radial groove of the inner face of the platform, the retaining assembly being configured to: • receive a radially internal end of at least one slat from the plurality of slats so that each slat is opposite at least one cavity of the disc so as to axially block the foot of a blade mounted in said cavity of the disc and • achieve external radial retention of the lamella, radially outwards with respect to the lamella.

[0019] Thanks to the invention, the hooks, protrusions extending in a radially outward direction, retain the blades axially at their radially inner portion, which allows for at least partial mechanical unloading of the blades on which the blades rest via their radially outer 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 radially outward direction by the hooks. The implementation of the invention is simple and requires little modification of the disk. The turbomachine, the hooks belonging to an added part fixed to the disc. Thus, the assembly is easier than in the prior art.

[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 the hook which has a portion which extends upstream so as to form an axial groove of the hook open upstream, the radially internal end of each lamella comprising a portion which extends downstream and which is received in the axial groove of the hook. • the hook extends radially outwards at a radially external end of the added part. • the hook extends radially outwards at a radially external end of a downstream annular flange mounted against the disc, on the downstream side of the disc. • the downstream annular flange includes a radially internal portion mounted against a downstream face of a disc rim. • the downstream annular flange is fixed to the disc, radially under the alveoli, by a plurality of fixing means. • 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 The slats are made from a metallic material. • the upstream axial retention means include an upstream annular flange mounted against an upstream face of the rotor disc, the upstream annular flange being configured to axially retain the blade feet in the disc recesses. • the upstream annular flange is fixed to the disc, radially under the alveoli, by a plurality of fixing means. • The disc includes an annular groove open downstream and the upstream annular flange is mounted against the upstream face of the disc by a locking ring which is mounted in the annular groove of the disc.

[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 not in any way limiting to the invention. • Fig. 1 shows a schematic representation of an axial cross-sectional view of a portion of a rotor, according to the prior art, • Figure [Fig. 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 an axial cross-sectional view of a portion of a rotor according to a second embodiment of the invention, • Figures 5 and 6 show schematic representations of perspective views, from upstream of the turbomachine, of part of a rotor according to a second embodiment of the invention. DETAILED DESCRIPTION

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

[0025] The invention is a turbomachine rotor 20, 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] Fig. 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] Fig. 4 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 second embodiment of the invention.

[0029] In the rest of the description, the term "blade" will be used to refer to a movable rotor blade.

[0030] With reference to [Fig.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.

[0031] The feet 80 of blades 40 are engaged in recesses 31 provided 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.

[0032] The feet 80 of the blades 40 are retained radially in the recesses 31 by their bulbous, dovetail-shaped cross-section. Furthermore, the feet 80 of the blades 40 are retained axially in the recesses 31 of the disc 30 by axial retention means.

[0033] The axial retention means of the blade 40 in the disc 30 comprise upstream axial retention means and downstream axial retention means.

[0034] 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.

[0035] The upstream flange 97 is fixed to the disc 30 of the rotor 20 and is in the form of a part of revolution, the axis of revolution of which coincides with the axis of rotation X of the rotor 20. The upstream flange 97 can be fixed to the disc 30 by any known means, for example by a circlip housed in an annular groove of the disc 30, as shown with the circlip 971 and the annular groove 972 in [Fig.3], or by screws, or by axial bolts and / or by dog ​​clutching.

[0036] 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.

[0037] 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 makes it possible to limit 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, of a flow of cold air radially from the inside to the outside. Such blades 100 with a downstream spoiler 105 are schematically represented in Figures 4 to 6.

[0038] The invention relates in particular to the radially external retaining means for the slats 100. The radially external retaining means exert an inward radial force on the slats 100 to ensure that the slats 100 are held in position and to prevent displacement of the slats 100 in the radially outward direction. These radially external retaining means, in a first mode of The implementations are schematically represented in detail in [Fig.4]. The radially external retaining means comprise a combination of two means.

[0039] A first radially external retaining means is formed by at least one hook 34. Each lamella 100 is retained radially by a single hook 34. The hook 34 is an outgrowth extending in a radially external direction. The hook 34 further comprises an upstream-facing notch 341, i.e., 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 down, 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.

[0040] In the invention, the hook 34 is included in an add-on fixed to the disk 30. That is to say, each add-on comprises at least one hook 34. Preferably, each add-on comprises a single hook 34. Even more preferably, the rotor comprises a single add-on, although, in another embodiment, the rotor may comprise several add-ons. The add-on is fixed to the disk 30 of the rotor 20. The hook 34 is a projection extending in a radially outward direction from the downstream face of the add-on, as shown in Figures 3 and 4. The add-on may, for example, be in the form of a part of revolution, the axis of revolution of which coincides with the axis of rotation X of the rotor 20. For example, and as schematically shown in Figures 3 to 6, the add-on fixed to the disk 30 is a flange 98.A flange is an annular part of revolution, used in particular to hold parts of the turbomachine. As shown in Figures 4 to 6, the flange 98 preferably comprises a radially internal part 981 mounted against a downstream face of a rim 301 of the disk 30. The hook 34 extends preferably from a radially external end of the flange 98, as shown in Figures 3 to 6.

[0041] The added part can be attached to the disc 30 by any known means, for example by a circlip housed in an annular groove of the disc 30 (as shown with circlip 971 and annular groove 972 for flange 97 in [Fig. 3]), or by screws, or by axial bolts and / or by locking. The means of attaching flange 98 in Figures 3 to 6 is not shown.

[0042] A second radially external retaining means, in all embodiments of the invention, is formed by radial grooves 63 provided in the inner faces of the downstream 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.

[0043] The combination of the first and second radially external retaining means 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 projection 341 upstream of the hooks 34 via the projection downstream 102 of the radially internal end of the slats 100.

[0044] The hooks 34 also form radially internal retaining means. Indeed, each lamella 100 is held, at 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.

[0045] Furthermore, the slats 100 are arranged opposite the alveoli 31 of the disc 30 so as to axially block the feet 80 of the blades 40 in said alveoli 31.

[0046] In embodiments of Figures 3 to 6, advantageously, 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.

[0047] In addition, the foot of the slats 100 is positioned between two circumferentially adjacent hooks 34, opposite a foot 80 of blade 40. Thus, the foot of each of said slats 100 forms a lug which is circumferentially against a hook 34 so as to block said slat 100 from rotation.

[0048] Advantageously, the upstream flange 97 and / or the added part comprising the hooks 34 (for example the downstream flange 98) and / or the slats 100 have orifices (not illustrated) which ensure the conveyance of a flow of cold air towards 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.

[0049] 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 material (“CMC”) while the vanes 100 are made of a metallic material. In another embodiment, the blades 40 and the vanes 100 are made of the same material, for example, a ceramic matrix composite.

Claims

1. Demands Rotor (20) of a turbomachine (1) extending around 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 blades (40), each blade (40) comprising: • a blade (50) which extends radially with respect to the axis (X), • 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), • 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 slats (100) circumferentially distributed around the axis (X) of the disc (30) and a retaining assembly having a hook shape (34), the retaining assembly preferably comprising a hook, and in that the retaining assembly belongs to an added part (98) fixed to the disc (30), each slat (100) of the plurality of slats comprising a radially external end disposed in the radial groove (63) of the inner face (62) of the platform (60), the retaining assembly being configured to: • receive a radially internal end (102) of at least one slat (100) of the plurality of slats so that each slat (100) is opposite at least one alveolus (31) of the disc (30) so as to axially block the foot (80) of a blade (40) mounted in said alveolus (31) of the disc (30) and • achieve an external radial retention of the slat (100), radially outside vis-à-vis the slat (100).

2. Rotor (20) of turbomachine (1) according to claim 1 in which the external radial retention of each slat (100) is achieved by the hook (34) which has a portion which extends in projection (341) upstream 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 extends in projection downstream and which is received in the axial groove (342) of the hook (34).

3. Rotor (20) of turbomachine (1) according to any one of the preceding claims wherein the hook (34) extends radially outward at a radially external end of the added part (98).

4. Turbomachine rotor (20) according to any one of claims 1 or 2 wherein the hook (34) extends radially outwards at a radially external end of a downstream annular flange (98) mounted against the disk (30), on the downstream side of the disk (30).

5. Rotor (20) of turbomachine (1) according to claim 4 in which the downstream annular flange (98) comprises a radially internal portion (981) mounted against a downstream face of a rim (301) of the disc (30).

6. Rotor (20) of turbomachine (1) according to any one of claims 4 or 5 wherein the downstream annular flange (98) is fixed to the disc (30), radially under the pits, by a plurality of fastening means.

7. Turbine rotor (20) of (1) according to any one of the preceding claims wherein each blade (100) of the plurality of blades has a spoiler (105) which extends axially downstream.

8. Turbine rotor (20) (1) according to any one of the preceding claims wherein the blades (40) and the vanes (100) are made of different materials.

9. Turbine rotor (20) of (1) according to the preceding claim wherein the blades (40) are made from a ceramic matrix material and the vanes (100) are made from a metallic material.

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

11. Rotor (20) of turbomachine (1) according to claim 10 in which the upstream annular flange (97) is fixed to the disc (30), radially under the pits, by a plurality of fixing means.

12. Rotor (20) of turbomachine (1) according to claim 10 in which the disc (30) comprises an annular groove (972) open downstream and the upstream annular flange (98) is mounted against the upstream face of the disc (30) by a locking ring (971) which is mounted in the annular groove (972) of the disc (30).

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