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 with respect to the axis (X), a foot (80) formed in the radial extension of the blade (50), configured to be mounted in a respective recess (31) of the disk (30), in which 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) including a radial step (108), a shoulder (71) configured to achieve radial retention of the slat (100) and a plurality of hooks (34), each hook (34) being configured to achieve axial retention of the slat (100). Figure to be published with the abbreviation: Figure 4

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 mounted against 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 brackets belonging to the disk, • a plurality of lamellae circumferentially distributed around the axis of the disc, • the rotor further comprising at least one radial retention shoulder, • 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 radial retention shoulder being configured to achieve external radial retention of the slat, radially outward from the slat, 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 each slat is mounted opposite at least one hole of the disc so as to axially lock the foot of a blade mounted in a hole of the disc.

[0019] Thanks to the invention, the hooks, protrusions extending in an outward radial direction, retain the blades axially at their radially internal portion, and a combination of a shoulder and a notch on each blade retains the blades in the outward radial direction, which allows at least partial mechanical unloading of the vanes on which the blades bear via their radially external end. Thus, even when using ceramic matrix vanes, the mechanical load on the blades is not problematic for the blade structure, because the blades are also held in the external radial direction by the combination of a shoulder and a notch of each blade, distributing the mechanical load better than in the previous 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: • Each lamella of the plurality of lamellae comprises a radially internal portion and a radially external portion, the radially internal portion being axially offset from the radially external portion and the external radial retention of the lamella is achieved by the radial retention shoulder which serves as a radial stop for the radially internal portion. • The radial retention shoulder is made by a groove cut into the disc radially below the alveoli and in which the radially internal portion extends upstream and is inserted into the groove of the disc. • the radial retention shoulder is formed in at least one blade foot. • 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 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 a downstream 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 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 a magnified axial cross-sectional view of a portion of a rotor according to a first embodiment of the invention. • Fig. 5 shows a schematic representation of a perspective view, 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 has 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 turbine rotor, high or low pressure, 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 movable rotor blade.

[0029] 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.

[0030] The feet 80 of the blades 40 are engaged in recesses 31 provided in the outer periphery of the 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 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.

[0032] The axial retention means of the blade 40 in the disk 30 comprise 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 mounted against 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.

[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 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 spoiler 105 are schematically represented in Figures 5 and 6.

[0037] The invention relates in particular to the radially external holding means and the axial holding means for the slats 100. The radially external holding means exert an inward radial force on the slats 100 to maintain the slats 100 in position and prevent displacement of the slats 100 in the radially outward direction. The downstream axial holding means exert an axial force on the slats 100 to maintain the slats 100 in position and prevent downstream displacement of the slats 100. The holding means are schematically shown in detail in a first embodiment in Figures 3 and 4 and in a second embodiment in [Fig. 5]. The radially external holding means comprise a combination of two means.

[0038] A first means of radially external retention of the lamellae 100 is formed by a combination of a shoulder and a notch of the lamellae 100.

[0039] The shoulder, interacting with the radial notch of the lamellae 100, provides radial external support for the lamellae 100. To achieve this, the lamellae 100 have a shape designed to conform to the shoulder; that is, the lamellae 100 comprise a radial notch designed to bear against the shoulder in the radially outward direction.

[0040] In a first embodiment, schematically represented in [Fig.4], the shoulder is included in Péchasse 70 of the blade 40. The shoulder 71 is a modification of the thickness of Péchasse 70, Péchasse 70 then comprising a first radially internal part 72 of thickness along the axis of rotation X of the rotor 20 less than the thickness of a second radially external part 73 of Péchasse 70, the two parts 72 and 73 of different thickness then being separated by the shoulder 71.

[0041] In this first embodiment, each slat 100 comprises a first radially internal portion 101 offset along the axis of rotation X of the rotor 20 relative to a second radially external portion 102 of the slat 100. This offset along the axis of rotation X of the rotor 20 is a radial offset, such that the first radially internal portion 101 is upstream of the second radially external portion 102. This allows each slat 100, when mounted to provide axial support for the Péchasse 70, to follow the shape of the downstream face 74 of the Péchasse 70, which includes a shoulder 71. The shoulder 71 then performs a radially external support function for the slat 100 by the support of the offset 103 of the slat 100 on the shoulder 71 of the Péchasse 70. The retention shoulder radial 71 then serves as a radial stop for the internal portion 101 of the slat 100.

[0042] In a second embodiment schematically represented in [Fig. 5], the shoulder 36 is included within the disc 30. The shoulder 36 is a modification of the thickness of the disc 30, the disc 30 then comprising a first radially internal portion whose thickness along the axis of rotation X of the rotor 20 is less than the thickness of a second radially external portion of the disc 30, the two portions of different thicknesses being separated by the shoulder 36. The second radially external portion of the disc 30, in [Fig. 5], is the part of the disc 30 comprising the recesses 31 intended to receive the blade feet 80. Thus, the shoulder 36 is formed below the recesses 31. The shoulder 36 is then, for example, formed by a groove cut into the disc 30, radially below the recesses 31. In this second embodiment, each blade 100 includes an upstream radial step. Such an upstream radial step is a projecting portion 108.The shoulder 36 then performs a radially external retaining function of the blade 100 by the support of the projecting portion 108 of the blade 100 on the shoulder 36 of the disc 30 in a radially external direction. Each blade 100 is configured to engage its projecting portion 108 in the shoulder 36 of the disc 30 and to cover a cavity 31 following the shape of the downstream face 37 of the disc 30, thus achieving axial retaining of the blade root 80.

[0043] A second radially external retaining means, in all embodiments of the invention, is formed by radial grooves 63 provided in the internal 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.

[0044] 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 stilts 70 via their shoulder 71 or to the disc 30 via its shoulder 36, by the notch 108 of the slats 100.

[0045] The invention also includes a means for axially retaining the pads. The axially retaining means for the pads is formed by hooks 34. As shown in Figures 3 to 5, the hooks 34 are contained within the disc 30, and are individually part of a tooth 32 of the disc 30, i.e., raised portions delimiting the sockets 31. The hooks 34 are outgrowths extending in an outward radial direction, each hook belonging to a tooth 32 of the disc 30.

[0046] In the first embodiment of the first radial retaining means, shown in [Fig. 4], the slats 100 may 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 struts 70. Each head of the slats 100 is thus radially supported against two adjacent hooks 34. Furthermore, the foot, or radially internal portion, of the slats 100 is positioned between two circumferentially adjacent hooks 34, opposite a foot 80 of a blade 40. Thus, the foot of each of said slats 100 forms a lug which is circumferentially abutted against a hook 34 so as to lock said slat 100 against rotation.

[0047] In the second embodiment of the first radial retaining means, comprising a shoulder in the disc 30 under the alveoli 31 shown in [Fig.5], the lamellae 100 may have a substantially rectangular shape with a center of narrowed width, i.e., a head, or radially external portion, configured to bear on two adjacent hooks 34, and feet, or radially internal portion, comprising the upstream projecting portion 108 configured to bear 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 hooks 34.

[0048] The hooks 34 also form radially internal retaining means. Indeed, the radially internal end of each slat 100 is retained, at its radially external end, by the base of the hook 34, coming to rest on the base of the hook 34.

[0049] Thus, each lamella 100 is held axially by two hooks 34, and is held radially by the interaction of the shoulder 36 with the projection 108, as well as by the radial groove 63 and by the base of the hook(s) 34.

[0050] 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.

[0051] 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 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.

[0052] 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 dawns (40), each dawn (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 brackets (34) belonging to the disk (30), • a plurality of lamellae (100) circumferentially distributed around the axis (X) of the disc (30), - the rotor further comprising at least one shoulder (36.71) of radial retention, - each slat (100) of the plurality of slats comprising a radially external end disposed in the radial groove (63) of the internal face (62) of the platform (60), the radial retention shoulder (36,71) being configured to achieve external radial retention of the slat (100), radially outward from the slat (100), each hook (34) of the plurality of hooks being configured to receive a radially internal end (102) of a slat (100) of the plurality of slats so that each slat (100) is mounted opposite at least one alveolus (31) of the disk (30) so as to axially block the foot (80) of a blade (40) mounted in an alveolus (31) of the disk (30).

2. Rotor (20) of turbomachine (1) according to claim 1 wherein each blade (100) of the plurality of blades comprises a radially internal portion (101) and a radially external portion (102), the radially internal portion (101) being axially offset with respect to the radially external portion (102) and the external radial retention of the blade (100) is achieved by the radial retention shoulder (36,71) which serves as a radial stop for the radially internal portion (101).

3. Rotor (20) of turbomachine (1) according to claim 2 in which the radial retention shoulder (36,71) is made by a groove cut in the disc (30) radially under the alveoli (31) and in which the radially internal portion (101) extends upstream and is inserted into the groove of the disc (30).

4. Rotor (20) of turbomachine (1) according to claim 2 in which the radial retaining shoulder (36,71) is formed in at least one foot (80) of blade (40).

5. 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.

6. 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.

7. 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.

8. Rotor (20) of turbomachine (1) according to any one of the preceding claims wherein the retention means axial upstream include an upstream flange (97) mounted against the rotor (20) disc (30), the upstream flange (97) being configured to axially retain the feet (80) of the blades (40) in the recesses (31) of the disc (30).

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

10. Rotor (20) of turbomachine (1) according to claim 8 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.

Images