Shim for turbomachine moving blade

Abstract

The invention relates to a shim (30) for a moving blade (10) comprising a root (11) and configured to be mounted in a peripheral cell (21) of a disk (20) of a turbomachine (1) with a longitudinal axis (X). The shim (30) comprises a flexible body (33), a first (41) and a second (42) support and is configured to be mounted in a space (E) between the root (11) and the bottom (211) in a mounting position such that the first support (41) bears against the blade root (11) and the second support (42) bears against the cell bottom (211), the flexible body (33) being shaped so that, through its supports, it can deform elastically while having a wavy profile, the shim (30) extending along a main axis A between a first and a second opposite end. Figure 2

Description

Title of the invention: Wedge for a moving blade of a turbomachine

[0001] In a turbomachine, for example a double-spool double-flow turbomachine which extends along a longitudinal axis, a compressor located upstream compresses the air which has entered the turbomachine from upstream. This air is admitted into the combustion chamber of the turbomachine located downstream where it is mixed with fuel before being burned there. The hot gases resulting from this combustion are then expanded in a turbine located downstream and cause this turbine to turn. The rotation of this turbine drives the rotor of this turbomachine on which these turbines are mounted. The rotor in turn drives the rotation of the compressor and the blades of the fan located upstream of the turbomachine. The rotation of the fan blades contributes, with the high-speed ejection of the gases at the outlet of the combustion chamber, to the propulsion of the turbomachine.

[0002] The turbine and the compressor comprise a set of coaxial discs which are arranged one after the other along the longitudinal axis of the turbomachine. Each disc carries on its outer periphery a plurality of moving blades regularly distributed on this outer periphery. The moving blades have a platform which extends circumferentially and which is extended radially internally by a blade root and extended radially externally by a blade. The root of each blade is housed in a cell of the disc, each cell opening onto the outer peripheral surface of the disc. A cell has a shape which substantially matches the shape of a root. The root has a shape which allows it to be held in its cell despite the centrifugal force which is exerted on it during the rotation of the disc during operation of the turbomachine. For example, the root has a dovetail or fir tree shape.

[0003] A blade root is inserted into a cell of a disk by translation along an axis substantially parallel to the longitudinal axis of the turbomachine or inclined relative to this longitudinal axis. In order to facilitate this mounting of the blades on the rotor disks, it is necessary to provide sufficient clearance to allow easy sliding of the blade roots in the cells. There therefore remains a relatively large clearance once the blade root has been mounted in the cell, which can be detrimental to the proper operation of the turbomachine. Indeed, and in particular when stopped, the moving blades can move in radial translation in the direction of the longitudinal axis of the turbomachine.The same applies when the turbomachine is operating but at reduced speed, that is to say when the rotor is rotating at reduced speed, insufficient for the centrifugal force to move the blade roots away from the radially internal base of the disk cells and press the lateral faces of the blade root (called the bearing surfaces of the . foot) against the lateral faces of the disc alveolus (called alveolus surfaces).

[0004] It is therefore sought to prevent the blade roots from falling towards the longitudinal axis of the turbomachine when the latter is stopped or operating at reduced speed. One solution consists of providing the blades with stilts which connect the roots to the platforms of the blades, as described in documents FR 2994211 and FR 3072122. [Fig. 11] illustrates these stilts 200 for a blade 100 which comprises a platform 120, a root 110, a blade 130. These stilts 200 comprise walls 210 which abut against the teeth formed between two successive cells, thus allowing radial maintenance of the position of the blades 100 and limiting the radial displacement towards the longitudinal axis of the turbomachine of the roots 110 in the cells.

[0005] However, a disadvantage of such stilts is that they have shapes that are relatively complex to produce, which has a significant impact in terms of cost and time to produce the blades. Furthermore, the production of such stilts is even more complex when the blades are partially or entirely made of a ceramic matrix composite material. Description of the invention

[0006] The present invention aims to remedy these drawbacks.

[0007] The invention aims to propose a device which makes it possible, in an economical manner, to secure the radial positioning of the moving blades on the discs, and in particular to limit, during operation of the turbomachine, the radial displacement towards the longitudinal axis of the turbomachine of the roots of the blades in the cells of the discs as well as the tilting of the blades relative to their radial direction.

[0008] This object is achieved by the fact that this device is a shim for a mobile turbomachine blade comprising a root, the shim being configured to be mounted on a turbomachine disk of longitudinal axis X, the disk having at its external periphery a plurality of open cells, the cells being circumferentially adjacent and separated by teeth, each of the cells being configured to receive one of the blade roots and having a bottom, the shim being configured to be mounted radially in a space E between the bottom and the root in a mounting position and comprising a flexible body, a first support and a second support, in the mounting position the first support bears against the blade root and the second support bears against the cell bottom, the flexible body being shaped so that, through its supports, it can deform elastically while having a wavy profile,the wedge extending along a main axis A between a first and a second opposite end.

[0009] Thanks to these arrangements, a moving blade can be positioned radially outwards in the cell in which it is housed, regardless of its shape. Thus, the bearing surfaces of the blade root bear against the bearing surfaces of the cell. In In particular, it is not necessary to conform this blade with stilts to obtain this positioning. This prevents the blade root from moving radially inwards when the turbomachine is stopped or operating at low speed. In addition, the axial shape of the shim allows its easy insertion into the cell between the bottom of the cell and the blade root.

[0010] For example, the flexible body is a flat blade having a first face and a second face opposite the first face, the flexible body having a first end and a second end, such that the first support is located on the first face and consists of an end protrusion located at the first end and another end protrusion located at the second end, in which the second support consists of a central protrusion located in the middle of the second face.

[0011] For example, the flexible body is a flat blade having a first face and a second face opposite the first face, the flexible body having a first end and a second end, such that the first support consists of a central protrusion located in the middle of the first face, and such that the second support is located on the second face and consists of an end protrusion located at the first end and another end protrusion located at the second end.

[0012] For example, each of the central protrusions and the end protrusions is a stud.

[0013] For example, each of the pads tapers from its base toward its distal end.

[0014] For example, the flexible body has a first end and a second end and the wedge has a stop which is located at the second end and which is capable of coming to bear against the disc to prevent movement of the wedge in one direction outside the space E.

[0015] For example, the stop comprises a first branch which is capable of bearing on a first of its teeth located circumferentially on one side of the alveolus, and a second branch which is capable of bearing on a second of its teeth located circumferentially on the other side of the alveolus.

[0016] The invention also relates to an assembly for a turbomachine with a longitudinal axis X comprising a disc having a plurality of open cells, the cells being circumferentially adjacent on the external periphery of the disc and each having a bottom, and a plurality of mobile blades each comprising a root mounted in one of the cells, the assembly comprising at least one shim according to the invention.

[0017] For example, this assembly further comprises a retaining member which is capable of cooperating with the wedge when it is mounted in the space E to prevent removal of the wedge from the space E.

[0018] For example, the retaining member is a flange which is fixed to the disc.

[0019] The invention also relates to a turbomachine comprising an assembly according to the invention.

[0020] The invention will be better understood and its advantages will appear better, on reading the detailed description which follows, of embodiments shown as non-limiting examples. The description refers to the appended drawings in which:

[0021] [Fig.l] [Fig.l] is a longitudinal sectional view of a turbomachine comprising blades with shims according to the invention.

[0022] [Fig.2] [Fig.2] is a view in a transverse plane of a portion of a disc and of a blade with a wedge according to the invention.

[0023] [Fig.3] [Fig.3] is a perspective view of a wedge according to the invention.

[0024] [Fig.4] [Fig.4] is a sectional view in a longitudinal plane of a portion of a disc and a blade with a wedge according to the invention.

[0025] [Fig.5] [Fig.5] is a sectional view in a longitudinal plane of a portion of a disc and a blade with a variant of a wedge according to the invention.

[0026] [Fig.6] [Fig.6] is a perspective view of a wedge according to a variant of sheave lization of the invention.

[0027] [Fig.7] [Fig.7] is a sectional view in a longitudinal plane of a wedge according to a another embodiment of the invention.

[0028] [Fig.8] [Fig.8] is a perspective view of a wedge according to yet another mode of carrying out the invention.

[0029] [Fig.9] [Fig.9] is an axial sectional view of the shim of [Fig.8] when it is housed in the cell and with a blocking element, and inserting a perspective view of this blocking element alone.

[0030] [Fig. 10] [Fig. 10] is a top view of a wedge according to yet another mode of realization of the invention.

[0031] [Fig. 11] [Fig. 11] is a perspective view of a blade according to the prior art. Detailed description of the invention

[0032] We consider a turbomachine 1 with a longitudinal axis X which is its axis of rotation. In the description below, the terms “internal” and “inner” designate an element oriented towards the longitudinal axis X or arranged closer to this axis. The terms “external” and “outer” designate an element oriented in the opposite direction from the longitudinal axis X or arranged further from this axis. The terms “upstream” and “downstream” are relative to the direction of circulation of the air and gases during operation of the turbomachine, i.e. from left to right in the figures. The term “radial” designates a position or a direction in a transverse plane perpendicular to the longitudinal axis X.

[0033] By way of example, the invention is first described in the case where the turbomachine 1 is a dual-flow double-spool turbomachine. [Fig. 1] illustrates such a turbomachine 1, in a longitudinal view. This turbomachine 1 comprises a nacelle 2 with a fan 3 comprising blades. The turbomachine 1 comprises a hub 8a, a rotor element of which carries the ring of blades forming the propeller of the fan 3. The hub 8a is made up of rotor elements and stator elements alternating along the longitudinal axis X. The hub 8a is carried by a rotor 8 which extends along the longitudinal axis X and which is rotated by a high-pressure turbine 6 and a low-pressure turbine 7, discussed below. Radially outside the hub 8a and downstream of the propeller of the fan 3 is an internal casing 8b which is coaxial with the hub 8a.

[0034] In normal operation of the turbomachine 1, an air flow (called secondary flow F2) circulates in an annular vein, called second vein V2, which extends between the inner casing 8b and the nacelle 2. Another annular vein, called first vein VI, extends between the hub 8a and the inner casing 8b. The first vein VI comprises, downstream of the fan 3, a compressor 4 and a combustion chamber 5. This compressor 4 comprises, upstream, a low-pressure compressor 4a and downstream, a high-pressure compressor 4b. The air compressed by the compressor 4 is admitted downstream into the combustion chamber 5 and mixed with fuel before being burned there. The hot gases resulting from this combustion are then expanded in a turbine in the first vein V1 and turn this turbine. This turbine comprises a high pressure turbine 6 which is located downstream of the combustion chamber 5 then a low pressure turbine 7 located downstream of the high pressure turbine 6.The high-pressure turbine 6 comprises at least one stage E and the low-pressure turbine 7 comprises several stages E, each stage E consisting of a ring of fixed turbine blades, also called a nozzle, followed by a ring of mobile turbine blades spaced circumferentially all around the longitudinal axis X. The stages E are located in the turbine vein, which is a first vein VL The turbomachine 1 also comprises a rotor 8 whose axis of rotation is the longitudinal axis X. The mobile turbine blades of the high-pressure turbine 6 and of the low-pressure turbine 7 are integral with the rotor 8. Indeed, a row of blades is mounted over the entire external circumference of a disk which is itself mounted on the rotor 8, such that each blade extends radially outwardly relative to the disk.Thus, the rotation of these moving turbine blades turns the rotor 8 which in turn drives the low pressure compressor 4a, the high pressure compressor 4b and the blades of the fan 3 into rotation. The rotation of the blades of the fan 3 contributes, with the high speed ejection of the gases at the outlet of the combustion chamber 5, to the propulsion of the turbomachine 1. The mounting of blades on the external circumference of . discs described above for the turbines are found at the compressors.

[0035] The invention is described below in the case of a turbine blade and disk but is valid for any moving blade mounted on a disk. [Fig. 2] is a view in a transverse plane (i.e. perpendicular to the longitudinal axis X) of a moving turbine blade 10 and a turbine disk 20 on which it is mounted, also visible in [Fig. 1]. The moving blade 10 comprises a platform 12, a root 11 which extends radially inward from this platform 12 and a blade 13 which extends radially outward from this platform 12. The disk 20 has a plurality of cells 21 located on the outer circumferential periphery of the disk 20 and the opening of which is located on this periphery. Any two adjacent cells 21 are circumferentially separated by a tooth 22. Each of the cells 21 is oriented radially outwards and has a bottom wall 211, also called bottom 211.The blade 10 is mounted on the disc 20 by insertion and translation of its root 11 along an insertion axis which is substantially parallel to the longitudinal axis X or inclined relative to this longitudinal axis X.

[0036] A shim 30 comprises a flexible body 33, a first support 41 and a second support 42. Before mounting the blade 10 in the cell 21 in its mounting position, the shim 30 is at rest (i.e. it is not deformed by external forces) and extends essentially in a main plane P. By “essentially”, it is meant that the majority (for example at least 50%, for example at least 70%, for example at least 90%) of the shim 30 extends in the same plane. Thus, the two largest dimensions of the shim 30 are in this plane, the thickness (smaller dimension) being perpendicular to this plane. This flat geometry of the shim 30 allows it to be easily mounted in its mounting position. The wedge 30 has at rest an elongated and rectilinear shape along a main axis A which is contained in the main plane P, as illustrated in [Fig.3] which is a perspective view of the wedge.The flexible body 33 has a first end 301 and a second end 302 along this main axis A, these two ends (301, 302) therefore being opposite. By “flexible”, we mean that the wedge is visibly deformable in the mounting position (see below).

[0037] In its mounting position, the shim 30 is inserted into a space E between the blade root 11 and the bottom 211 of the cell 21. The shim 30 extends along its main axis A over the entire thickness of the disc 20, that is to say over the entire length of the cell 21. To insert the shim 30 into the space E, the shim 30 is elastically deformed from its rest position. The flexible body 33 is elastically deformed in flexion in this mounting position so that the shim 30 exerts a force on the root 11 which tends to radially move the blade root 11 away from the cell bottom 211. Thus the shim 30 has a radially undulating profile. In this mounting position, the root 11 blade and the bottom 211 exert pressure on the wedge 30 while seeking to move closer to each other. An elastic deformation is, by definition, a reversible deformation when no force is exerted on the wedge 30. Thus, in the mounting position of the wedge 30, the first support 41 of the wedge 30 bears against the blade root 11 and the second support 42 of the wedge 30 bears against the bottom 211 of the cell 21. In this mounting position, the main plane P in which the wedge 30 essentially extends is perpendicular to a radial direction relative to the longitudinal axis X. [Fig. 4] is a longitudinal sectional view in the radial plane IV-IV of [Fig. 2], the radial plane IV-IV containing the longitudinal axis X.

[0038] For example, as illustrated in the figures, the flexible body 33 is a flat blade which has in the main plane P a first face 331 and a second face 332 which is opposite the first face 331. For example, this blade is rectangular and its length extends along the main axis A.

[0039] In a first variant, the first support 41 (which is in contact with the foot 11) is located on the first face 331 and is made up of an end protrusion 411 located at the first end 301 and an end protrusion 412 located at the second end 302. The second support 42 (which is in contact with the bottom 211 of the cell 21) is made up of a central protrusion 423 located in the middle of the second face 332. This shim 30 is illustrated in [Fig. 3]. The shim 30 is also visible in [Fig. 4] and in [Fig. 2]. In its mounting position, the shim 30 is deformed in three-point bending by the forces on these protrusions.

[0040] Alternatively, in a second variant, the first support 41 is constituted by a central protrusion 413 located in the middle of the first face 331, and the second support 42 is located on the second face 332 and is constituted by an end protrusion 421 located at the first end 301 and an end protrusion 422 located at the second end 302. This wedge 30 is illustrated in [Fig.5].

[0041] In these two variants, the central (413, 423) and end (411, 412, 421, 422) protrusions extend from the surface of the flexible body 33, for example perpendicularly. These protrusions therefore project relative to the flexible body 33. These protrusions can have any geometry. For example, each of the central (413, 423) and end (411, 412, 421, 422) protrusions is a stud. For example, each of these pads is rectangular and extends over substantially the width of the flexible body 33, as illustrated in figures 2 to 5. This width is in a direction perpendicular to the main axis A, in the main plane P. For example, each of these pads narrows from its base (at the level of the first face 331 or the second face 332) towards its distal end (top), that is to say that its cross-section decreases.For example, the lateral surfaces of each stud, which connect its base to its distal end, are concave. This wedge 30 is illustrated in . [Fig.6]. Alternatively, the growths are bulges on the flexible body 33 or local deformations of the flexible body 33.

[0042] In the above description, the flexible body 33 has, apart from the central (413, 423) and end (411, 412, 421, 422) protrusions, a constant thickness. Alternatively, the flexible body 33 has, apart from the central (413, 423) and end (411, 412, 421, 422) protrusions, an excess thickness at the locations where the bending stresses are greatest.

[0043] According to another embodiment, illustrated in [Fig.7], the shim 30 illustrated in [Fig.4] is modified to add on the second face 332, under the end protrusion 411 a small stud 51 and under the end protrusion 412 a small stud 52. The small studs (51, 52) are smaller (less high) than the central protrusion 423 so that the shim 30 deforms in bending in the mounting position. However, the small studs (51, 52) prevent a bending deformation of the flexible body 33 beyond the elastic limit of the material constituting the flexible body 33.

[0044] In another embodiment, the shim 30 has a stop 35 which is located at the second end 302. This stop is capable of coming to bear against the disc 20 to prevent a movement of the shim 30 out of the space E in one direction along the main axis A.

[0045] For example, as illustrated in [Fig.8], the stop 35 is made up of a first branch 351 which is able to bear on a first of the teeth 22 situated circumferentially on one side of the cell 21, and of a second branch 352 which is able to bear on a second of the teeth 22 situated circumferentially on the other side of the cell 21. Thus, the impossible direction of withdrawal of the wedge 30 is towards the left, and a withdrawal of the wedge 30 can only be carried out in the direction of the arrow F, that is to say towards the right. For example, these branches (351, 352) extend in the main plane P perpendicular to the main axis A.

[0046] The invention also relates to an assembly for a turbomachine 1 with a longitudinal axis X comprising a disc 20 having a plurality of cells 21 open circumferentially on the radially external periphery of the disc 20 and having a bottom 211, and a plurality of mobile blades 10 comprising a root 11 mounted in one of the cells 21, the assembly comprising at least one shim 30 according to the invention.

[0047] For example, this assembly further comprises for each wedge 30 a retaining member (or blocking member) 40 which is capable of cooperating with the wedge 30 when it is mounted in the space E to prevent the wedge 30 from being removed from the space E.

[0048] For example, the assembly comprises as many shims 30 as blades 10, each shim 30 being intended to be inserted into a cell 21 which receives a blade 10.

[0049] Various configurations of the retaining member 40 are possible. For example, the retaining member 40 is a flange that attaches to the disc 20. For example, a part of the retaining member 40 is crossed by the main axis A. The flange 40 is sufficiently close to one end of the wedge 30 so that the withdrawal of the wedge 30 in the direction of the flange 40 is prevented. Thus the distance between the flange 40 and the edge of the disc 20 is less than the length of the wedge 30 along the main axis A.

[0050] In the case where the shim 30 has a stop 35, the flange 40 is located on the same side as the stop 35, such that the stop 35 is sandwiched between the disc 30 and the flange 40. Thus, a translation of the shim 30 in both directions along the main axis A is impossible. This situation is illustrated in [Fig. 9], which is a section of a portion of the disc 20 in a plane radially above the main plane P and parallel to the main plane P. The shim 30 is in the mounting position, and the root 11 of the blade 10 is not shown. [Fig. 9] also illustrates the flange 40 in perspective, which is shaped in an L.

[0051] In the case where the shim 30 does not have a stop 35, the retaining member 40 is shaped to prevent a translation of the shim 30 out of the space E in both directions along the main axis A. For example, the retaining member 40 is connected to the disc 20 by a first mechanical connection and is connected to the shim 30 by a second mechanical connection to prevent a translation of the shim 30 in both directions along the main axis A. For example, the shim 30 has a hole at one end and the retaining member 40 is fixed to the disc 20 and comprises a rod which is inserted into this hole.

[0052] In [Fig. 2], the blade 10 is mounted on the disk 20 by insertion and translation of its root 11 along an insertion axis which is substantially parallel to the longitudinal axis X. Thus, the wedge 30 is also mounted in the space E along this insertion axis, and consequently the main axis A of the wedge 30 is parallel to the longitudinal axis X in the mounting position of the wedge 30. Alternatively, as illustrated in [Fig. 10], this insertion axis is inclined relative to this longitudinal axis X. Thus, the main axis A of the wedge 30 is inclined in the main plane P relative to the longitudinal axis X in the mounting position of the wedge 30.

[0053] The invention also relates to a turbomachine 1 comprising an assembly according to the invention.

Claims

Claims

1. Wedge (30) for a moving blade (10) of a turbomachine (1) comprising a root (11), said wedge (30) being configured to be mounted on a disk (20) of a turbomachine (1) with a longitudinal axis (X), said disk (20) having at its outer periphery a plurality of open cells (21), the cells (21) being circumferentially adjacent and separated by teeth (22), each of said cells (21) being configured to receive one of said blade roots (11) and having a bottom (211), said wedge (30) being configured to be mounted radially in a space (E) between said bottom (211) and said root (11) in a mounting position and being characterized in that it comprises a flexible body (33), a first support (41) and a second support (42), and in that in said mounting position mounting said first support (41) is supported against said blade root (11) and said second support (42) is supported against said cell bottom (211),said flexible body (33) being shaped so as, through its supports (41, 42), to be able to deform elastically while presenting a wavy profile, said wedge (30) extending along a main axis (A) between a first and a second opposite end.,

2. Wedge (30) according to claim 1 wherein said flexible body (33) is a flat blade having a first face (331) and a second face (332) opposite said first face (331), said flexible body (33) having a first end (301) and a second end (302), such that said first support (41) is located on said first face (331) and consists of an end protrusion (411) located at said first end (301) and another end protrusion (412) located at said second end (302), and wherein said second support (42) consists of a central protrusion (423) located in the middle of said second face (332).

3. Wedge (30) according to claim 1 wherein said flexible body (33) is a flat blade having a first face (331) and a second face (332) opposite said first face (331), said flexible body (33) having a first end (301) and a second end (302), such that said first support (41) consists of a central protrusion (413) located in the middle of said first face (331), and such that said second support (42) is located on said second face (332) and consists of an end protrusion (421) located at said first end (301) and another end protrusion (422) located at said second end (302).

4. A wedge (30) according to claim 2 or 3 wherein each of said central protrusions (413, 423) and said end protrusions (411, 412, 421, 423) is a stud.

5. A wedge (30) according to claim 4 wherein each of said studs tapers from its base towards its distal end.

6. Wedge (30) according to any one of claims 1 to 5 wherein said flexible body (33) has a first end (301) and a second end (302) and said wedge (30) has a stop (35) which is located at said second end (302) and which is capable of coming to bear against said disc (20) to prevent movement of said wedge (30) out of said space (E).

7. Wedge (30) according to claim 6 wherein said stop (35) comprises a first branch (351) which is able to bear on a first of said teeth (22) situated circumferentially on one side of said cell (21), and a second branch (352) which is able to bear on a second of said teeth (22) situated circumferentially on the other side of said cell (21).

8. Assembly for a turbomachine (1) with a longitudinal axis (X) comprising a disc (20) having a plurality of open cells (21), the cells (21) being circumferentially adjacent on the external periphery of said disc (20) and each having a bottom (211), and a plurality of mobile blades (10) each comprising a root (11) mounted in one of said cells (21), said assembly comprising at least one shim (30) according to any one of claims 1 to 7.

9. An assembly according to claim 8 further comprising a retaining member (40) which is adapted to cooperate with said wedge (30) when mounted in said space (E) to prevent removal of said wedge (30) from said space (E).

10. An assembly according to claim 9 wherein the retaining member (40) is a flange which attaches to the disc (20).

11. Turbomachine (1) comprising an assembly according to any one of claims 1 to 10.

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