Turbine rotor assembly for turbomachine

Abstract

Turbine rotor assembly comprising an upstream disc (30) comprising a first radial annular flange (33); a downstream disc (40) spaced from the upstream disc (30) in the longitudinal direction (X1) and comprising a second radial annular flange (43); a sealing ring (20) interposed between the upstream disc (30) and the downstream disc (40) and comprising a third radial annular flange (22) which comprises an upstream face applied longitudinally against a downstream face of the first radial annular flange (33), and a downstream face applied longitudinally against an upstream face of the second radial annular flange (43); an upstream sealing means (50) interposed in the longitudinal direction between the downstream face of the first radial annular flange (33) and the upstream face of the third radial annular flange (22). Abstract figure: Figure 3

Description

Title of the invention: Turbine rotor assembly for a turbomachine Technical field

[0001] The present description relates to a turbine rotor assembly of a turbomachine, to a turbine comprising such a rotor assembly and to a method of assembling such a rotor assembly. Prior art

[0002] Conventionally, a turbomachine of the double-flow turbojet type comprises, from upstream to downstream in the direction of circulation of the gases inside the turbomachine, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and an exhaust nozzle. The low-pressure compressor, the high-pressure compressor, the combustion chamber, the high-pressure turbine, the low-pressure turbine and the exhaust nozzle are arranged radially inside a casing which delimits, radially outwards, an annular primary vein 4 of the turbomachine in which the gases flow from upstream to downstream.

[0003] The high-pressure compressor and the low-pressure compressor are respectively connected to the high-pressure turbine and the low-pressure turbine by a respective shaft extending along the longitudinal axis X of rotation of the shafts of the turbomachine.

[0004] In the present disclosure, the longitudinal direction XI corresponds to the direction of the longitudinal axis X. The longitudinal axis X coincides with an axis of rotation of the rotor parts of the turbomachine. Orientation qualifiers, such as “longitudinal”, “radial” or “circumferential” are defined, unless otherwise specified, by reference to the longitudinal axis X. A radial direction RI is a direction perpendicular to the direction of the longitudinal axis X. A circumferential direction, at a point distant from the longitudinal axis X, corresponds to a direction perpendicular to the longitudinal and radial directions. Furthermore, unless otherwise specified, the adjectives “inner”, “inner”, “outer” and “outer” are used with reference to a radial direction RI so that the inner / inner part (i.e. radially inner / inner) of an element is closer to the longitudinal axis X than the outer / outer part (i.e.radially external / external) of the same element. Finally, the relative qualifiers “upstream” and “downstream” are defined in relation to the normal flow direction of the fluid (from upstream to downstream) in the turbomachine.

[0005] As shown in [Fig.l], each turbine 1 conventionally comprises several stages, each consisting of a row of fixed blades 3, also called a distributor, followed by a row of moving blades 2.

[0006] The low-pressure turbine 1 thus comprises a rotor or rotor assembly comprising the elements mobile in rotation around the longitudinal axis X, and in particular the row of mobile blades 2 of each stage. The rotor of the low-pressure turbine further comprises a plurality of discs 10 each comprising a hub 11 provided with a peripheral rim on which one of the rows of mobile blades is mounted. Each disc 11 further comprises an upstream shell 12am and a downstream shell 12av more particularly visible in [Fig. 2]. The upstream shell 12av and the downstream shell 12am of each disc 10 extend longitudinally from the hub of the disc respectively upstream and downstream. The upstream shell 12am and the downstream shell 12av of each disc 10 are intended for fixing the disc with respectively the disc 10 longitudinally adjacent to the upstream and the disc longitudinally adjacent to the downstream.For this purpose, the upstream ferrule 12am and the downstream ferrule 12av each include a radial annular flange 13av, 13am.

[0007] The rotor generally comprises a sealing ring 20 arranged longitudinally between each pair of consecutive discs 10 and comprising an annular platform 21 arranged radially opposite one of the rows of fixed blades 3. The sealing ring 21 comprises a plurality of wipers 23 projecting radially outwards from the annular platform to cooperate in sealing with the row of fixed blades. The sealing ring 20 is fixed to the rotor by means of a radial annular flange 22 extending radially inwards from the annular platform 21 and interposed longitudinally between the downstream shell 12av of the disc 10 longitudinally adjacent to the upstream and the upstream shell 12am of the disc longitudinally adjacent to the downstream, more precisely between the radial annular flange 13av of the downstream shell 12av and the radial annular flange 13am of the upstream shell 12am.The connection between the radial annular flanges of the discs and the sealing ring is generally carried out by means of 14 bolts.

[0008] The rotor of the turbine (in particular the disks) is subjected to a very hot thermal environment. This is why a specific cooling system is provided which comprises an internal cavity 61 delimited radially on the outside by the upstream and downstream shells of the plurality of disks 10 and which is supplied by a flow of “cold” cooling air DI taken upstream of the turbine, generally at one of the compressors, in particular at the high-pressure compressor or a thermodynamic plane of the high-pressure compressor. A radially internal portion of the hub 11 of each disk extends inside the internal cavity, allowing cooling of the disks 10. This cooling air is then reinjected into the annular primary stream upstream of the rotor at a controlled flow rate D2, in particular at the level of an upstream duct formed longitudinally between the disk upstream (i.e. the first rotor disc in the direction from upstream to downstream of the longitudinal direction XI) and a downstream distributor of the high-pressure turbine. Also, it is provided that the cooling air has sufficient pressure in the internal cavity 61 to limit a flow of gases flowing in the annular primary vein 4 radially inwards in the upstream duct.

[0009] Due to manufacturing tolerances, a clearance j may be formed in the longitudinal direction XI between the radial annular flange 22 of one of the sealing rings 20 and one of the radial annular flanges 13am, 13av of the corresponding upstream and downstream ferrules 12am, 12av. Also, due to the high pressure of the cooling air in the internal cavity 61, the cooling air can flow radially outwards through the clearance (represented by the arrow F) which causes a reduction in the pressure of the cooling air in the internal cavity 61. However, if the pressure of the cooling air is not sufficient (in particular if it is lower than the pressure of the gases circulating in the annular primary vein), this results in an introduction of the hot gases from the annular primary vein 4 into the internal cavity 61 via the upstream duct and a heating of the discs which can affect their integrity and their service life.

[0010] A known solution is to check, during assembly of the low-pressure turbine, the effective longitudinal plating between the radial annular flange 21 of each ring 20 and the radial annular flanges 13am, 13av of the upstream and downstream shells 12am, 12av of the adjacent discs 10 manually by means of a glitter shim. However, this solution proves to be time-consuming. Summary

[0011] A turbine rotor assembly for a longitudinal axis turbomachine is provided, the assembly comprising: - an upstream disc comprising a downstream shell which has a first radial annular flange, - a downstream disc spaced from the upstream disc in the longitudinal direction and comprising an upstream shell which has a second radial annular flange, - a sealing ring interposed, in whole or in part, between the upstream disc and the downstream disc and comprising a third radial annular flange, the third radial annular flange comprising an upstream face applied longitudinally against a downstream face of the first radial annular flange, and a downstream face applied longitudinally against an upstream face of the second radial annular flange, the assembly further comprising at least one of an upstream sealing means interposed in the longitudinal direction between the downstream face of the first radial annular flange and the upstream face of the third radial annular flange and a downstream sealing means interposed in the longitudinal direction between the downstream face of the third radial annular flange and the upstream face of the second annular flange radial.

[0012] This makes it possible to limit, or even eliminate, a radially outward leak of cooling air contained in an internal cavity arranged radially inside the downstream shell and the upstream shell towards an external cavity arranged radially outside the downstream shell and the upstream shell, or even towards an annular primary vein arranged radially outside the rotor assembly and in which gases from the turbomachine flow.

[0013] In addition, sealing is ensured even if a clearance is formed longitudinally between the downstream face of the first radial annular flange and the upstream face of the third downstream annular flange, or between the upstream face of the second radial annular flange and the downstream face of the third radial annular flange. Thus, the arrangement of the sealing means (upstream and / or downstream) makes it possible to avoid checking the longitudinal clearances between the downstream face of the first radial annular flange and the upstream face of the third downstream annular flange, and / or between the upstream face of the second radial annular flange and the downstream face of the third radial annular flange. The assembly of such an assembly is thus faster. The clearance thus taken up can be formed annularly around the longitudinal axis or locally around the longitudinal axis.

[0014] At least one of the downstream face of the first radial annular flange and the upstream face of the third radial annular flange comprises an upstream longitudinal annular groove in which the upstream sealing means is engaged, the upstream sealing means bearing in the longitudinal direction on the other of the downstream face of the first radial annular flange and the upstream face of the third radial annular flange. At least one of the downstream face of the third radial annular flange and the upstream face of the second radial annular flange may comprise a downstream longitudinal annular groove in which the downstream sealing means is engaged, the downstream sealing means bearing in the longitudinal direction on the other of the downstream face of the third radial annular flange and the upstream face of the second radial annular flange.

[0015] The upstream sealing means and upstream sealing means are thus maintained in the radial direction.

[0016] The upstream longitudinal annular groove and / or the downstream longitudinal annular groove may comprise an outlet which longitudinally delimits said longitudinal annular groove and at least one radially external annular face, the radially external annular face of said longitudinal annular groove being at least delimited on one side in the longitudinal direction by the outlet of said longitudinal annular groove, the radially external face of said longitudinal annular groove widening in the longitudinal direction in a direction oriented towards the outlet.

[0017] During operation of the turbomachine, the sealing means (upstream or downstream) is applied radially outwards by the centrifugal effect on the radially external face of the corresponding longitudinal annular groove in which it is engaged. The radially external face of the longitudinal annular groove then forms a ramp (or a guide) which makes it possible to maintain the sealing means applied in the longitudinal direction on the downstream face of the first radial annular flange or the upstream face of the third radial annular flange in the case of the upstream sealing means, or on the downstream face of the third radial annular flange or the upstream face of the second radial annular flange in the case of the downstream sealing means. This makes it possible to maintain the seal despite the radial displacement of the sealing means under the centrifugal effect.

[0018] The radially outer annular face of the upstream longitudinal annular groove widens longitudinally downstream when the upstream longitudinal annular groove is formed in the downstream face of the first radial annular flange and upstream when the upstream longitudinal annular groove is formed in the upstream face of the third radial annular flange.

[0019] The radially external annular face of the downstream longitudinal annular groove widens longitudinally downstream when the downstream longitudinal annular groove is formed in the downstream face of the third radial annular flange and upstream when the downstream longitudinal annular groove is formed in the upstream face of the second radial annular flange.

[0020] The radially external face of the longitudinal annular groove may be frustoconical of revolution around the longitudinal axis with a section increasing towards the outlet.

[0021] In other words, the profile of the radially external face in a section plane comprising the longitudinal axis is substantially a straight line segment forming an angle with the longitudinal axis, also called a half-angle at the apex of the frustoconical shape.

[0022] The truncated cone shape of the radially external face of the longitudinal annular groove may have a half-angle at the apex greater than or equal to 45°.

[0023] The longitudinal annular groove may comprise an annular bottom face. The annular radially outer face may be delimited in the longitudinal direction by the bottom face. The annular radially outer face may extend longitudinally from the bottom face to the outlet.

[0024] The longitudinal annular groove may comprise at least one annular radially inner face. The annular radially inner face may extend longitudinally from the bottom face to the outlet. The annular radially inner face may have a cylindrical shape with a circular section around the longitudinal axis.

[0025] The upstream sealing means and / or the downstream sealing means may be a seal annular capable of being elastically deformed.

[0026] The seal may be split. The seal may be made of a material suitable for withstanding high temperatures. The seal may be O-ring, for example with a diameter between 2 mm and 3 mm.

[0027] Each disc may include a hub. The downstream shell of the upstream disc may extend longitudinally downstream from the hub of the upstream disc. The downstream shell may include a first longitudinal connecting wall having an upstream end at which the downstream shell is connected to the hub of the upstream disc and a downstream end from which the first radial annular flange extends radially inward. The upstream longitudinal annular groove may be formed adjacent the junction between the first connecting wall and the first radial annular flange. Similarly, the upstream shell of the downstream disc may extend longitudinally upstream from the hub of the downstream disc.The upstream ferrule may comprise a second longitudinal connecting wall having a downstream end at which the upstream ferrule is connected to the hub of the downstream disc and an upstream end from which the second radial annular flange extends radially inward. The downstream longitudinal annular groove may be formed in the vicinity of the junction between the second connecting wall and the second radial annular flange.

[0028] Each hub may comprise a peripheral rim in which an annular row of longitudinally oriented cells or grooves is formed and in each of which a turbomachine blade may be fitted by complementary shape. Longitudinally at the level of each disc, the rim of the disc in question may radially delimit the primary annular gas flow vein on the inside.

[0029] The upstream disc, the downstream disc and the sealing ring are integral with each other. The first radial annular flange, the second radial annular flange and the third radial annular flange may be connected to each other, for example by bolting. For this purpose, the assembly may comprise at least one bolt which passes through each of the radial annular flanges. Each radial annular flange may comprise a radial annular wall from which a plurality of festoons extend radially inwards. The bolted connections may be located at the festoons of each flange. The longitudinal annular groove may be formed at the radial wall of the corresponding radial annular flange.

[0030] The designation of the radial annular flanges by a numeral adjective (“first”, “second”, “third”) results from a semantic choice. Alternatively, the first radial annular flange can be designated by “radial annular flange of the downstream shell of the upstream disc” or by “downstream radial annular flange of the upstream disc”. Similarly, the second radial annular flange may be referred to as the "radial annular flange of the upstream shell of the downstream disc" or as the "upstream radial annular flange of the downstream disc". The second radial annular flange may constitute the sole flange of the upstream shell of the disc. Finally, the third radial annular flange may be referred to as the "radial annular flange of the sealing ring". The third radial annular flange may constitute the sole flange of the sealing ring.

[0031] The sealing ring may comprise an annular platform from which the third radial annular flange extends radially inward. The sealing ring may further comprise a plurality of wipers projecting radially outward from the annular platform and intended to cooperate in a sealing manner with an annular row of fixed blades of the turbine. Longitudinally between the upstream disc and the downstream disc, the annular platform of the sealing ring may delimit radially on the inside the primary annular gas flow vein.

[0032] The rotor assembly may include a cooling system. The cooling system may include an internal cavity (also called a purge cavity). The internal cavity may be delimited radially on the outside by the downstream shell of the upstream disc and the upstream shell of the downstream disc. A radially internal end portion of the hub of each disc may extend inside the internal cavity. The internal cavity may contain cooling air (or purge air) intended for cooling the discs and the sealing ring. The rotor assembly may include an external cavity. The external cavity may be delimited radially on the inside by the downstream shell of the upstream disc and the upstream shell of the downstream disc. The external cavity may be delimited radially on the outside by the annular platform of the sealing ring.The external cavity may be delimited longitudinally upstream by the downstream shell of the upstream disc and / or an upstream end portion of the annular platform of the sealing ring, and downstream by the upstream shell of the downstream disc and / or a downstream end portion of the annular platform of the sealing ring. The external cavity may comprise a first portion and a second portion separated longitudinally from each other by the third radial annular flange.

[0033] The cooling system may comprise a first series of grooves formed in an upstream face of the third radial annular flange and adapted to place the internal cavity and the external cavity, in particular the first part of the external cavity, in fluid communication. Each groove of the first series of grooves may be formed at the radial wall of the third annular flange, and preferably circumferentially between two scallops. The cooling system may comprise a second series of grooves formed in a downstream face of the third radial annular flange and adapted to put the internal cavity and the external cavity, in particular the second part of the external cavity, into fluid communication. Each groove of the second series of grooves may be formed at the radial wall of the third annular flange, and preferably circumferentially between two scallops. Each groove of the first series of grooves and / or the second series of grooves allows the circulation of cooling air between the internal cavity and the external cavity at a chosen flow rate (i.e. determined in advance) and controlled for cooling the sealing ring. The flow rate is chosen to maintain sufficient cooling air pressure in the internal cavity and not to impair the performance of the turbomachine.The grooves of the first series of grooves and / or the second series of grooves may be distributed annularly around the longitudinal axis, preferably in a regular manner.

[0034] The cooling system may comprise a series of holes formed through the annular platform of the sealing ring and adapted to put the external cavity and the annular primary flow stream into fluid communication. Each hole allows the circulation of cooling air between the external cavity and the annular primary flow stream at a chosen (i.e. determined in advance) and controlled flow rate for the evacuation of the cooling air. The flow rate is chosen to maintain sufficient cooling air pressure in the internal cavity and not to harm the performance of the turbomachine. The holes may be distributed annularly around the longitudinal axis, preferably in a regular manner.

[0035] According to another aspect, a turbine for a turbomachine is described, the turbine comprising at least one rotor assembly as described above. It may be a low pressure turbine.

[0036] According to another aspect, there is provided a method of assembling a turbine rotor assembly for a turbomachine as described above, the method comprising the steps: A Position the upstream disc so that the longitudinal axis coincides with the gravity field and the downstream face of the first radial annular flange is facing upwards; B Position the sealing ring on the upstream disc so that the upstream face of the third radial annular flange is applied longitudinally to the downstream face of the first radial annular flange; and C Position the downstream disc on the sealing ring so that the upstream face of the second radial annular flange is applied longitudinally to the downstream face of the third radial annular flange.

[0037] The method further comprises a step i carried out between steps A and B which comprises the positioning of the first sealing means on the downstream face of the first radial annular flange and / or a step ii carried out between steps B and C which comprises the positioning of the second sealing means on the downstream face of the third radial annular flange.

[0038] In the case where the upstream longitudinal annular groove is formed in the downstream face of the first radial annular flange, step i may comprise the engagement of the first sealing means in the upstream longitudinal annular groove.

[0039] The method may comprise a subsequent step which comprises the securing of the first radial annular flange, the second radial annular flange and the third radial annular flange, in particular by bolting. Brief description of the drawings

[0040] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0041] [Fig.l], already described previously, is a partial schematic sectional view of a low-pressure turbine of a turbomachine of the prior art;

[0042] [Fig.2], already described previously, is a partial schematic sectional view on a larger scale of an assembly of the turbine of [Fig.l];

[0043] [Fig.3] is a schematic view similar to that of [Fig.2] and illustrating a turbine assembly for a turbomachine according to an embodiment of the present description.

[0044] [Fig.4] is a partial schematic perspective view of a disc of the assembly of [Fig.3];

[0045] [Fig.5] is another partial schematic perspective view of the disc of [Fig.4]

[0046] [Fig.6] is a partial schematic perspective view of a sealing ring of the whole of [Fig.3];

[0047] [Fig.7] is a partial schematic sectional view of the assembly of [Fig.3] in a configuration in which the turbine is in operation. Description of the embodiments

[0048] Reference is now made to [Fig. 3] which represents a turbine rotor assembly for a turbomachine with a longitudinal axis X comprising an upstream disc 30, a downstream disc and a sealing ring 20. In this case, and in a non-limiting manner, this is a low-pressure turbine. The upstream disc 30 is visible in isolation and in more detail in Figures 4 and 5. The sealing ring 20 is visible in isolation and in more detail in [Fig. 6].

[0049] The upstream disc 30 and the downstream disc are spaced apart from each other in the longitudinal direction XL. Each disc comprises a hub 31, 4L. Each hub 31, 41 comprises a peripheral rim in which an annular row is formed. of longitudinally oriented cells or grooves, and in each of which a turbomachine blade is fitted by complementary shape. Longitudinally at the level of each disc, the rim of the disc in question can delimit radially inside an annular primary vein 4 arranged radially outside the rotor assembly and in which gases from the turbomachine flow.

[0050] The upstream disc 30 comprises a downstream ferrule 32 which extends longitudinally downstream from the hub 31 of the upstream disc 30. The downstream disc comprises an upstream ferrule 42 which extends longitudinally upstream from the hub 41 of the downstream disc. As described below, the downstream ferrule 32 of the upstream disc 30 and the upstream ferrule 42 of the downstream disc are intended for fixing the discs together. The downstream ferrule 32 comprises a first connecting wall 34 and a first radial annular flange 33. The first connecting wall 34 comprises an upstream end at which the downstream ferrule 32 is connected (here in a single piece) to the hub 31 of the upstream disc 30 and a downstream end from which the first radial annular flange 33 extends radially inwards. The first radial annular flange 33 has an external end by which it is connected (here in one piece) to the first connecting wall 34 and a free internal end.Similarly, the upstream ferrule 42 comprises a second connecting wall 44 and a second radial annular flange 43. The second connecting wall 44 has a downstream end at which the upstream ferrule 42 is connected (here in a single piece) to the hub 41 of the downstream disc and an upstream end from which the second radial annular flange 43 extends radially inwards. The second radial annular flange 43 has an external end by which it is connected (here in a single piece) to the second connecting wall 44 and a free internal end.

[0051] The sealing ring 20 is interposed, here in part, between the upstream disc 30 and the downstream disc. The sealing ring 20 comprises a third radial annular flange 22 and an annular platform 21. The third radial annular flange 22 extends radially inward from the annular platform 21. The third radial annular flange 22 comprises an upstream face applied longitudinally against a downstream face of the first radial annular flange 33, and a downstream face applied longitudinally against an upstream face of the second radial annular flange 43.

[0052] The upstream disc 30, the downstream disc and the sealing ring 20 are integral with each other. The first radial annular flange 33, the second radial annular flange 43 and the third radial annular flange 22 are here connected to each other by bolting. For this purpose, the assembly may comprise at least one bolt which passes through each of the radial annular flanges. The assembly may comprise an annular row of bolted connections. For this purpose, each radial annular flange comprises a radial annular wall from which extends radially inwards a annular row of festoons 22a, 32a. The bolted connections are here located at the festoons 32a, 22a of each flange.

[0053] The sealing ring 20 comprises a plurality of wipers 23 projecting radially outwards from the annular platform 21 and intended to cooperate in a sealing manner with an annular row of fixed blades of the turbine. Longitudinally between the upstream disc 30 and the downstream disc, the annular platform 21 of the sealing ring 20 radially delimits on the inside the primary annular gas flow vein.

[0054] Remarkably, the assembly further comprises an upstream sealing means 50 interposed in the longitudinal direction XI between the downstream face of the first radial annular flange 33 and the upstream face of the third radial annular flange 22. This makes it possible to limit, or even eliminate, a radially outward leak of cooling air contained in an internal cavity 61 arranged radially inside the downstream shell 32 and the upstream shell 42 towards an external cavity 62 arranged radially outside the downstream shell 32 and the upstream shell 42, or even towards the primary annular flow path 4. In addition, sealing is ensured even if a clearance is formed longitudinally between the downstream face of the first radial annular flange 33 and the upstream face of the third downstream annular flange, or between the upstream face of the second radial annular flange 43 and the downstream face of the third radial annular flange. 22.Thus, the arrangement of the sealing means makes it possible to avoid checking the longitudinal clearances between the downstream face of the first radial annular flange 33 and the upstream face of the third downstream annular flange, and / or between the upstream face of the second radial annular flange 43 and the downstream face of the third radial annular flange 22. The assembly of such an assembly thus proves to be faster. The clearance thus taken up can be formed annularly around the longitudinal axis X or locally around the longitudinal axis X.

[0055] Here the upstream sealing means 50 is an annular seal capable of being elastically deformed. The seal may be split to allow easier deformation, in particular under the centrifugal effect as described below. The seal may be made of a material suitable for withstanding high temperatures reached when the turbine is in operation. The seal here is an O-ring, having for example a diameter of between 2 mm and 3 mm.

[0056] The downstream face of the first radial annular flange 33 further comprises an upstream longitudinal annular groove 35 in which the upstream sealing means 50 is partly received. The upstream sealing means 50 also bears in the longitudinal direction XI on the upstream face of the third radial annular flange 22. The sealing means is thus held radially when the turbine is operating (i.e. when the rotor assembly is rotated around the axis Ion- gitudinal X).

[0057] The upstream longitudinal annular groove 35 comprises an outlet located longitudinally opposite the upstream face of the third radial annular flange 22. The outlet longitudinally delimits said upstream longitudinal annular groove 35. The upstream longitudinal annular groove 35 also comprises at least one annular radially external face 35a. The annular radially external face 35a of the upstream longitudinal annular groove 35 is delimited, here downstream in the longitudinal direction XI, by the outlet of the upstream longitudinal annular groove 35. The upstream longitudinal annular groove 35 also comprises an annular bottom face. The annular radially external face 35a is delimited, here upstream in the longitudinal direction XI, by the bottom face. The annular radially external face 35a therefore extends longitudinally from the bottom face to the outlet. The longitudinal annular groove finally comprises at least one radially internal annular face.The annular radially inner face extends longitudinally from the bottom face to the outlet. The annular radially inner face has a cylindrical shape with a circular section around the longitudinal axis X.

[0058] Remarkably, the radially external face 35a of the upstream longitudinal annular groove 35 widens in the longitudinal direction XI in a direction oriented towards the outlet (i.e. downstream). During operation of the turbomachine, as shown in [Fig.7], the upstream sealing means 50 is applied radially outwards by the centrifugal force C on the radially external face 35a of the upstream longitudinal annular groove 35 in which it is engaged. The radially external face 35a of the upstream longitudinal annular groove 35 then forms a ramp (or a guide) which makes it possible to keep the upstream sealing means 50 applied in the longitudinal direction XI on the upstream face of the third radial annular flange 22. This makes it possible to maintain the seal despite the radial displacement and / or the radial deformation of the upstream sealing means 50 under the centrifugal effect.

[0059] In particular, the radially external face 35a of the upstream longitudinal annular groove 35 is frustoconical of revolution around the longitudinal axis X with a section increasing towards the outlet. In other words, the profile of the radially external face 35a in a section plane comprising the longitudinal axis X is substantially a straight line segment forming an angle with the longitudinal axis X, also called a half-angle at the apex of the frustoconical shape. The frustoconical shape of the radially external face 35a of the upstream longitudinal annular groove 35 may have a half-angle at the apex greater than or equal to 45°.

[0060] Also, the upstream longitudinal annular groove 35 is located radially closer to the outer end of the first radial annular flange 33 than to the inner end of the first radial annular flange 33. The longitudinal annular groove upstream 35 is therefore located in the vicinity of the junction between the first connecting wall 34 and the first radial annular flange 33. The longitudinal annular groove is in this case formed at the level of the radial wall of the corresponding radial annular flange. Such an arrangement of the upstream longitudinal annular groove 35 makes it possible to keep a sufficient portion of the first radial annular flange 33 for the passage of the bolted connections.

[0061] The rotor assembly further comprises a cooling system. The cooling system comprises the internal cavity 61 (also called the purge cavity) mentioned above. The internal cavity 61 is delimited radially on the outside by the downstream shell 32 of the upstream disc 30 and the upstream shell 42 of the downstream disc. A radially internal end portion of the hub 31, 41 of each disc 30, 40 extends inside the internal cavity 61. The internal cavity 61 contains cooling air (or purge air) intended for cooling the discs and the sealing ring 20. The rotor assembly also comprises the external cavity 62 mentioned above. The external cavity 62 is delimited radially on the inside by the downstream shell 32 of the upstream disc 30 and the upstream shell 42 of the downstream disc. The external cavity 62 is delimited radially on the outside by the annular platform 21 of the sealing ring 20.The external cavity 62 may be delimited longitudinally upstream by the downstream shell 32 of the upstream disc 30 and / or an upstream end portion of the annular platform 21 of the sealing ring 20, and downstream by the upstream shell 42 of the downstream disc and / or a downstream end portion of the annular platform 21 of the sealing ring 20. The external cavity 62 may comprise a first portion and a second portion separated longitudinally from each other by the third radial annular flange 22.

[0062] The cooling system comprises a first series of grooves formed in an upstream face of the third radial annular flange 22 and adapted to put the internal cavity 61 and the external cavity 62, in particular the first part of the external cavity 62, into fluid communication. Each groove of the first series of grooves is formed at the radial wall of the third annular flange, and preferably circumferentially between two festoons. The cooling system comprises a second series of grooves 24 formed in a downstream face of the third radial annular flange 22 and adapted to put the internal cavity 61 and the external cavity 62, in particular the second part of the external cavity 62, into fluid communication. Each groove of the second series of grooves 24 is formed at the radial wall of the third annular flange, and preferably circumferentially between two festoons.Unlike a leak which would be due to unwanted and uncontrolled play, each groove of the first series of grooves and / or the second series of grooves 24 allows the circulation of cooling air between the . internal cavity 61 and the external cavity 62 according to a flow rate chosen (i.e. determined in advance) and controlled for the cooling of the sealing ring 20. The flow rate is chosen to maintain sufficient cooling air pressure in the internal cavity 61 and not to harm the performance of the turbomachine. The grooves of the first series of grooves and / or of the second series of grooves 24 may be distributed annularly around the longitudinal axis X, preferably in a regular manner.

[0063] The cooling system also comprises a series of holes 25 formed through the annular platform 21 of the sealing ring 20 and adapted to put the external cavity 62 and the annular primary flow path 4 into fluid communication. As for the grooves, each hole 25 allows the circulation of cooling air between the external cavity 62 and the annular primary flow path 4 according to a flow rate chosen (i.e. determined in advance) and controlled for the evacuation of the cooling air. The flow rate is chosen to maintain sufficient cooling air pressure in the internal cavity 61 and not to harm the performance of the turbomachine. The holes 25 can be distributed annularly around the longitudinal axis X, preferably in a regular manner.

[0064] With reference to [Fig.8], a method 100 for assembling a turbine rotor assembly for a turbomachine as described above is now described.

[0065] The method 100 comprises a first step 101 which comprises the positioning of the upstream disc 30 so that the longitudinal axis X coincides with the gravity field and the downstream face of the first radial annular flange 33 is oriented upwards.

[0066] The method 100 comprises a second step 102 which comprises the engagement of the first sealing means in the upstream longitudinal annular groove 35.

[0067] The method 100 comprises a third step 103 which comprises the positioning of the sealing ring 20 on the upstream disc 30 so that the upstream face of the third radial annular flange 22 is applied longitudinally to the downstream face of the first radial annular flange 33.

[0068] The method 100 comprises a fourth step 104 which comprises the positioning of the downstream disc on the sealing ring 20 so that the upstream face of the second radial annular flange 43 is applied longitudinally to the downstream face of the third radial annular flange 22.

[0069] The method 100 comprises a fifth step 105 which comprises fixing the first radial annular flange 33, the second radial annular flange 43 and the third radial annular flange 22 together, here by bolting.

[0070] The invention is not limited to the examples described above and is susceptible to numerous variants.

[0071] According to a first variant not shown, the upstream longitudinal annular groove can be formed in the upstream face of the third radial annular flange. In this variant, the upstream sealing means can be received partly in the upstream longitudinal annular groove and can bear in the longitudinal direction XI on the downstream face of the first radial annular flange. In this variant, the radially external face of the upstream longitudinal annular groove can widen longitudinally towards the upstream.

[0072] According to a second variant not shown, which can be considered independently or in combination with the example described above or the first variant, the assembly can comprise a downstream sealing means interposed in the longitudinal direction XI between the downstream face of the third radial annular flange and the upstream face of the second radial annular flange. Structurally, the downstream sealing means can be identical to the upstream sealing means.

[0073] According to a first alternative of the second variant, the upstream face of the second radial annular flange may comprise a downstream longitudinal annular groove in which the downstream sealing means is, in whole or in part, received. The downstream sealing means may, on the other hand, bear on the downstream face of the third radial annular flange. The downstream longitudinal annular groove may have the same characteristics as the upstream longitudinal annular groove. In particular, a radially external face of the downstream longitudinal annular groove may widen longitudinally towards the upstream. Similarly, the downstream longitudinal annular groove may be formed in the vicinity of the junction between the second connecting wall and the second radial annular flange, i.e. radially closer to the external end of the second radial annular flange than the internal end of the second radial annular flange.

[0074] According to a second alternative of the second variant, the downstream longitudinal annular groove may be formed in the downstream face of the third radial annular flange. In this alternative, the downstream sealing means may be received partly in the downstream longitudinal annular groove and bear in the longitudinal direction XI on the upstream face of the second radial annular flange. In this alternative, the radially external face of the downstream longitudinal annular groove may widen longitudinally towards the downstream.

Claims

Claims

1. Turbine rotor assembly for a turbomachine with a longitudinal axis, the assembly comprising: - an upstream disc (30) comprising a downstream shroud (32) which comprises a first radial annular flange (33), - a downstream disc (40) spaced from the upstream disc (30) in the longitudinal direction (XI) and comprising an upstream shroud (42) which comprises a second radial annular flange (43), - a sealing ring (20) interposed, in whole or in part, between the upstream disc (30) and the downstream disc (40) and comprising a third radial annular flange (22), the third radial annular flange (22) comprising an upstream face applied longitudinally against a downstream face of the first radial annular flange (33), and a downstream face applied longitudinally against an upstream face of the second radial annular flange (43),the assembly further comprising at least one of an upstream sealing means (50) interposed in the longitudinal direction between the downstream face of the first radial annular flange (33) and the upstream face of the third radial annular flange (22), and a downstream sealing means interposed in the longitudinal direction between the downstream face of the third radial annular flange (22) and the upstream face of the second radial annular flange (43).,

2. Rotor assembly according to the preceding claim, in which at least one of the downstream face of the first radial annular flange (33) and the upstream face of the third radial annular flange (22) comprises an upstream longitudinal annular groove (35) in which the upstream sealing means (50) is engaged, the upstream sealing means (50) bearing in the longitudinal direction (XI) on the other of the downstream face of the first radial annular flange (33) and the upstream face of the third radial annular flange (22), and / or in which at least one of the downstream face of the third radial annular flange (22) and the upstream face of the second radial annular flange (43) comprises a downstream longitudinal annular groove in which the downstream sealing means is engaged,the downstream sealing means being supported in the longitudinal direction (XI) on the other of the downstream face of the third radial annular flange (22) and the upstream face of the second radial annular flange (43).,

3. Rotor assembly according to the preceding claim, in which the upstream longitudinal annular groove (35) and / or the downstream longitudinal annular groove comprises an outlet which longitudinally delimits said longitudinal annular groove (35) and at least one radially external annular face (35a), the radially external annular face (35a) of said longitudinal annular groove (35) being at least delimited on one side in the longitudinal direction by the outlet of said longitudinal annular groove (35), the radially external annular face (35a) of said longitudinal annular groove (35) widening in the longitudinal direction (XI) in a direction oriented towards the outlet.

4. Rotor assembly according to the preceding claim, in which the annular radially external face (35a) of the longitudinal annular groove (35) is frustoconical of revolution around the longitudinal axis (X) with a section increasing towards the outlet.

5. Rotor assembly according to the preceding claim, in which the frustoconical shape of the radially external annular face (35a) of the longitudinal annular groove (35) has a half-angle at the apex greater than or equal to 45° relative to the longitudinal direction (XI).

6. Rotor assembly according to any one of the preceding claims, in which the upstream sealing means (50) and / or the downstream sealing means comprises an annular seal capable of being elastically deformed.

7. Turbine for a turbomachine, the turbine comprising at least one rotor assembly according to any one of the preceding claims.

8. A method of assembling a turbine rotor assembly for a turbomachine according to any one of claims 1 to 6, the method comprising the steps: A Positioning the upstream disc (30) so that the longitudinal axis coincides with the gravity field and the downstream face of the first radial annular flange (33) is oriented upwards; B Positioning the sealing ring (20) on the upstream disc (30) so that the upstream face of the third radial annular flange (22) is applied longitudinally to the downstream face of the first radial annular flange (33); and C Positioning the downstream disc (40) on the sealing ring (20) so that the upstream face of the second radial annular flange (43) is

9.

10. applied longitudinally on the downstream face of the third radial annular flange (22); the method further comprising a step i carried out between steps A and B which comprises the positioning of the first sealing means (50) on the downstream face of the first radial annular flange (33) and / or a step ii carried out between steps B and C which comprises the positioning of the second sealing means on the downstream face of the third radial annular flange (22). Method according to the preceding claim, claim 2 applying with the upstream longitudinal annular groove (35) is formed in the downstream face of the first radial annular flange, in which step i comprises the engagement of the first sealing means (50) in the upstream longitudinal annular groove (35). Assembly method according to the preceding claim, the method comprising a subsequent step which comprises the securing of the first radial annular flange (33), the second radial annular flange (43) and the third radial annular flange (22), in particular by bolting.

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