Improved sealing assembly for turbomachine turbine

Abstract

Improved sealing assembly for a turbomachine turbine. Sealing assembly for a turbomachine turbine (6), comprising a turbine distributor (20) centered on a central axis (X), comprising at least one fixed blade (24), an external blade platform (26) comprising an external upstream spoiler (264) for hooking onto an internal hook (12), and an internal upstream spoiler (261) forming with the external upstream spoiler (264) an annular groove (29), a sealing ring (30) comprising a plurality of ring sectors (32) mounted end-to-end around the central axis (X), two adjacent ring sectors (32) comprising respectively a first and a second slot (34) arranged opposite each other, a sealing plate (36) being disposed in the first and second slots,the distributor (20) comprising an axial protrusion (25) extending axially into the annular groove (29) so as to reduce the axial distance between the sealing ring (30) and the distributor (20), and being arranged axially opposite the sealing plate (36). Figure for the abbreviation: Fig. 4.

Description

Title of the invention: Improved sealing assembly for turbomachine turbine technical field

[0001] This presentation relates to the field of aeronautical turbomachinery, in particular the distributors and sealing rings of such turbomachinery. More specifically, this presentation relates to a sealing assembly for a turbomachine turbine, and to a turbine comprising this sealing assembly. Previous technique

[0002] A turbomachine turbine, for example a low-pressure turbine, conventionally comprises several rotor and stator stages. A stator stage comprises a distributor downstream of the rotor stage and includes a plurality of fixed blades, or stators. A rotor stage comprises a rotating wheel with a plurality of rotating blades about a central axis.

[0003] In order to limit air leakage in the hot air flow stream and to ensure the system is sealed, the rotor blade heads are generally equipped with scuffs designed to cut a track of abradable material against a sealing ring surrounding the rotor. The radial spacing with minimal clearance between the scuffs and the abradable track during rotor rotation allows for high-efficiency operation.

[0004] Such a sealing ring is typically formed from a plurality of ring sectors assembled end to end around the central axis to form the ring. Also with the aim of ensuring the thermal sealing of the system, the sealing ring is typically equipped with a plurality of sealing plates, or strips. These sealing plates, typically made of metal, are inserted into slots made inside each ring sector, so as to extend between two circumferentially adjacent ring sectors, improving the seal between them.

[0005] Although these sealing plates do indeed improve the sealing of the junction between two ring sectors, and therefore of the turbine module, they nevertheless have drawbacks. In particular, loss of sealing plates is regularly observed, especially when the turbine module is inverted or placed vertically during handling phases, for example, as the plates fall off due to gravity, or during engine testing, as mounting defects can lead to their expulsion by the outgoing airflow. engine.

[0006] If one or more sealing plates are lost, the module must be completely disassembled to replace the plate(s), resulting in additional costs. Furthermore, sealing plates may also become dislodged from their housings during engine operation. Dislodgement or loss of plates during engine operation degrades the seal between the ring sectors, which reduces the lifespan of surrounding parts, particularly the hooks on the fixed housing that support the turbine stator. A dislodged sealing plate also constitutes a foreign body within the turbine that can damage it.

[0007] There is therefore a real need for a device for a turbomachine turbine which is free, at least in part, from the aforementioned disadvantages, and which in particular allows for improved retention of the sealing plates. Description of the invention

[0008] The present description relates to a sealing assembly for a turbomachine turbine extending around a central axis, the turbine comprising a fixed casing having at least one internal hook extending radially in projection from the casing towards the central axis, the sealing assembly comprising: - a turbine distributor centered on the central axis and comprising at least one fixed blade extending between a radially internal platform and a radially external platform, the radially external platform comprising an external upstream spoiler adapted to hook onto the internal hook, and an internal upstream spoiler forming with the external upstream spoiler an annular groove, the external upstream spoiler being located radially outside relative to the internal upstream spoiler, - a sealing ring suitable for attachment to the casing and intended to surround a turbine rotor stage, and comprising a plurality of ring sectors mounted circumferentially end to end around the central axis, a first and a second circumferentially adjacent ring sectors comprising respectively a first and a second slot, the first and second slots being arranged circumferentially opposite each other, and a sealing plate comprising a first circumferential end disposed in the first slot and a second circumferential end disposed in the second slot, the distributor comprising an axial protrusion which extends axially in projection from the annular groove so as to reduce an axial distance between the sealing ring and the distributor, and being disposed axially opposite the sealing plate.

[0009] In the present description, the terms "axial", "radial", "circumferential", "Interior", "exterior" and their derivatives are defined in relation to the central axis of the turbomachine, in other words the axis of rotation of the turbine. Furthermore, the terms "upstream" and "downstream" are defined in relation to the normal direction of airflow in the turbomachine.

[0010] The external upstream spoiler is typically a portion of the platform extending upstream and outward from a main surface of the platform, so as to form a hook cooperating with an external face of the internal hook of the fixed housing and thus enabling the radial retention of the distributor. The internal upstream spoiler of the platform may be located in line with its main surface, forming, with the external upstream spoiler, a clamp typically encompassing a portion of the sealing ring, and thus defining an annular groove. This annular groove forms a cavity open to the upstream side.

[0011] The sealing ring can also be fixed to the internal hook of the fixed housing, and is typically interposed between the external upstream spoiler and the internal upstream spoiler of the platform, axially opposite the annular groove.

[0012] It is therefore understood that having an axial protrusion in the annular groove, axially opposite the sealing plate, allows the cavity formed by said annular groove to be at least partially filled, thus limiting the possible axial displacement of the sealing plate. In other words, if the sealing plate moves within its housing during engine operation or during disassembly of the turbine module, its movement in the direction of the central axis is limited by the presence of the protrusion, the latter acting in particular as a stop preventing the plate from moving further out of its housing.

[0013] Thus, unlike prior art devices in which the sealing plates can come out of their housing via the annular groove, the sealing plates of the sealing assembly of the present presentation, during their axial movement downstream if necessary, come into contact with the distributor, in particular with the axial protrusion, but do not have room to come out of their housing.

[0014] It is thus possible to improve the sealing of the turbine module while limiting the risk of loss of sealing plates during engine operation, thereby reducing leakage during operation or disassembly, which facilitates maintenance operations and reduces costs. The reduced risk of loss of sealing plates also limits the risk of damage to turbine components, and therefore improves the turbine's lifespan.

[0015] In some embodiments, the axial protrusion extends axially from a bottom of the groove towards the sealing ring, the sealing ring being arranged upstream of the axial protrusion.

[0016] It is understood that the axial protrusion extends from the bottom of the annular groove upstream, that is to say towards the portion of the sealing ring comprising the sealing plate. This makes it possible to reduce the axial distance between said sealing plate and the distributor, and therefore to reduce the possible axial stroke of the sealing plate.

[0017] In some embodiments, the axial protrusion extends circumferentially over a distance greater than the width of the sealing plate.

[0018] It is understood that the sealing plate has a plate shape having a first dimension, i.e., a length, in the axial direction, and a second dimension, i.e., a width, in the direction perpendicular to the axial direction. It is thus understood that the protrusion extends along the annular groove, at the bottom thereof, over a distance greater than the said width of the sealing plate.

[0019] This improves the sealing plate's locking effect by maximizing the contact area between the plate's edge and the axial protrusion in the event of axial movement of the plate. This also promotes planar contact and thus limits wear related to such contact.

[0020] In some embodiments, the axial protrusion includes a flat upstream end face, at least a portion of which is disposed in the same radial position as the sealing plate.

[0021] Positioning the upstream end face in the same radial orientation as the sealing plate ensures that the sealing plate comes into contact with said upstream end face in the event of axial movement. Furthermore, the fact that the upstream end face is flat further promotes planar contact between the sealing plate and the distributor, thereby further limiting wear related to this contact.

[0022] In some embodiments, the axial protuberance includes a recessed upstream face arranged further downstream than the upstream end face.

[0023] Thus, while the upstream end face allows one to get as close as possible to the portion of the sealing ring comprising the sealing plate, the recessed upstream face allows space to be freed up, thus facilitating the integration of the distributor into the turbine, and limiting the quantity of material and therefore the mass of the assembly.

[0024] In some embodiments, the upstream end face of the axial protuberance is radial with respect to the central axis.

[0025] In other words, the upstream end face of the axial protrusion is perpendicular to a plane comprising the sealing plate. It is understood that the sealing plate has a plate shape forming a plane parallel to the central axis, and the upstream end face lies in a radial plane perpendicular to the central axis. The fact that the plane comprising the upstream end face and the plane comprising the sealing plate are perpendicular to each other prevents vibrations from twisting the sealing plate in the event of contact between the sealing plate and the upstream end face. Indeed, when the planes are perpendicular, the edge of the plate in contact with the axial protrusion slides on the upstream end face during vibration, whereas the plate would tend to bend if the upstream end face formed a non-right angle with it.

[0026] In some embodiments, an axial clearance between an upstream end of the axial protrusion and the sealing ring is less than 2 mm, preferably between 0.07 mm and 1.3 mm.

[0027] Preferably, the upstream end of the axial protrusion is the plane formed by the upstream end face. Providing an axial clearance of approximately 1 mm between the axial protrusion, in particular the upstream end face, and the portion of the sealing ring comprising the sealing plate, makes it possible to minimize the axial distance between the sealing ring and the distributor to obtain the aforementioned effects, while taking into account tolerances, expansions or possible movements of the parts relative to each other.

[0028] In certain embodiments, the assembly comprises a plurality of axial protrusions distributed circumferentially around the central axis, and in which each pair of circumferentially adjacent ring sectors comprises respectively a first and a second slot arranged circumferentially opposite each other and in which is housed a sealing plate comprising a first circumferential end disposed in the first slot and a second circumferential end disposed in the second slot, each axial protrusion being arranged axially opposite a sealing plate.

[0029] Preferably, the assembly comprises as many axial protrusions as sealing plates. This limits the displacement of each sealing plate, while minimizing the amount of material required to form the axial protrusions, and therefore minimizing the mass of the assembly.

[0030] In some embodiments, the assembly comprises a single axial protrusion extending axially from a bottom of the annular groove towards the sealing ring over the entire circumference of the distributor.

[0031] This configuration makes it possible to fill a large volume of the cavity formed by the annular groove, and therefore to further limit the risks of loss or disengagement of a sealing plate.

[0032] The present exposition also relates to a turbine comprising a sealing assembly according to any one of the preceding embodiments, the turbine being a low pressure turbine.

[0033] The present description also relates to a turbomachine comprising such a turbine. Brief description of the drawings

[0034] The invention and its advantages will be better understood upon reading the following detailed description of various embodiments of the invention, given by way of non-limiting examples. This description refers to the accompanying figure pages, on which:

[0035] [Fig-1] Fig. 1 represents a schematic longitudinal cross-sectional view of a tower bomachine;

[0036] [Fig. 2A-2B] Image A of Figures 2A-2B schematically represents a view in an axial plane of a sealing assembly at the level of an inter-sector according to the prior art, and image B schematically represents a view in a radial section plane BB of image A;

[0037] [Fig.3] The [Fig.3] represents a longitudinal cross-sectional view of a portion of a turbine according to the prior art, including a rotor stage and a stator stage;

[0038] [Fig.4] Fig.4 represents a longitudinal cross-sectional view of a portion of a turbine according to the invention, including a rotor stage and a stator stage;

[0039] [Fig.5] The [Fig.5] represents a detailed view of part V of the turbine portion of the [Fig.4];

[0040] [Fig.6] Fig.6 represents a perspective view of a turbine distributor sector according to the invention. Description of the implementation methods

[0041] In the following description, the terms "upstream" and "downstream" are subsequently defined with respect to the direction of gas flow through a turbomachine, indicated by arrow F on [Fig.1], representing the flow of hot gases in the combustion chamber 4. Furthermore, the terms "internal" and "external" are considered in a radial direction perpendicular to the central axis X.

[0042] Fig. 1 illustrates a double-flow turbomachine 100 comprising, in a known manner, from upstream to downstream successively, at least one blower S, a gas turbine engine part 1 comprising successively at least one stage of low-pressure compressor 2, high-pressure compressor 3, a combustion chamber 4, at least one stage of high-pressure turbine 5 and low-pressure turbine 6. The rotors of the compressors 2, 3, the turbines 5, 6 and the blower S rotate around the central axis X of the turbomachine 100, and can be coupled together by different transmission and gear systems.

[0043] In the following description, reference is made to the low-pressure turbine 6. It should be noted, however, that the invention can be applied to both the low-pressure turbine 6 and to The high-pressure turbine 5. This low-pressure turbine 6 comprises a plurality of rotor and stator stages arranged successively from upstream to downstream. For the sake of simplicity, only one rotor stage and one stator stage are shown in the following description.

[0044] In this regard, image 2A of figures 2A-2B schematically represents a section in an axial plane of a sealing ring 30 described below surrounding the rotor, or rotor stage 40, and image 2B schematically represents a section in a radial plane of the ring sector 30 and the rotor 40 of image 2A along the cutting plane BB, allowing visualization of the junction between two ring sectors.

[0045] Each rotor stage 40 comprises a plurality of movable rotor blades 42, each comprising a blade, a foot mounted on a disk (not shown) coupled to a shaft of the turbomachine. The rotor stage 40 rotates about the central axis X of rotation, inside the sealing ring 30 (hereinafter referred to as "ring 30") of the stator, comprising a plurality of curved ring sectors 32 joined end to end circumferentially, to form the ring 30 enveloping the rotor 40.

[0046] The circumferential ends of each ring sector 32 have a slot 34 configured to partially receive a sealing strip, or plate 36 (hereinafter "plate" 36). Each plate 36 is thus housed in the slots 34 of the circumferentially adjacent ring sectors 32, said slots 34 being circumferentially opposite each other. It is thus understood that a plate 36 is arranged so as to extend circumferentially between each pair of circumferentially adjacent ring sectors 32. In other words, the ring 30 comprises as many plates 36 as there are junctions between the ring sectors 32.

[0047] An abradable track 38 is carried by a radially inner face of each ring sector 32. In this example, the head of a movable blade 42 is equipped with two scourers 44a, 44b configured to notch the track of abradable material 38 carried by the ring sector 32.

[0048] These slats 44a, 44b improve the sealing of the junction between the The moving part, i.e., the rotor 40, and the fixed part, including the ring 30, limit the bypassing of the blades 42 by non-working air. Similarly, the plates 36, typically made of metal, improve thermal sealing at the junction between two sectors of the ring 32, limiting leakage of non-working air at this point.

[0049] Figure 3 represents, in an axial cross-sectional plane, a portion of a stator stage according to the prior art, in particular a sealing assembly comprising a sealing ring 30 and a distributor 20.

[0050] In [Fig. 3], only one ring sector 32 (carrying an abradable track 38) is visible, and only a portion of dispenser 20 is also visible. Dispenser 20 and the ring 30 are both fixed to a fixed external casing 10, in the manner described below.

[0051] The distributor 20 typically comprises a plurality of fixed vanes 24 (or rectifiers) distributed circumferentially around the central axis X, and extending between an inner and an outer ferrule. The distributor 20 may be formed as a single unit, or comprise a plurality of sectors 22 assembled end-to-end circumferentially around the central axis X so as to form the distributor 20.

[0052] Each sector 22 comprises one or more fixed blades 24 extending between an inner platform 28 (not visible in [Fig. 3]) and an outer platform 26, the assembly of the inner and outer platforms forming the inner and outer shells. The outer platform 26 extends axially between an inner upstream spoiler 261 and an inner downstream spoiler 262.

[0053] Furthermore, the external platform 26 includes an external upstream spoiler 264 extending upstream and outward from a main surface 263 of the external platform 26, and an external downstream spoiler 265 extending downstream and outward from said main surface 263. The external upstream spoiler 264 is formed such that it engages with an internal hook 12 disposed on an internal face of the fixed external housing 10, by cooperating with an external face of said internal hook 12. The internal hook 12 and the external upstream spoiler 264 are oriented in opposition to each other so as to allow such engagement. A similar engagement system is provided at the downstream end of the external platform 26, via the external downstream spoiler 265.

[0054] Furthermore, each ring sector 32 is also fixed to the internal hook 12, on an internal face thereof, and is also held by the distributor 20. Indeed, the internal upstream beak 261 and the external upstream beak 264 together form a clamp gripping a portion of the ring sector 32. Given this arrangement, an annular groove 29 is formed between the internal upstream beak 261 and the external upstream beak 264, the latter thus delimiting a cavity C open upstream.

[0055] The plates 36 arranged between each circumferentially adjacent ring sector 32 are thus axially opposite this annular groove 29. In the event of disengagement, the plates 36 are therefore likely to escape from the space left by this annular groove 29, in particular into cavity C.

[0056] A sealing assembly according to the present exposition is shown in [Fig. 4]. More specifically, [Fig. 4] shows, in an axial cross-sectional plane, a portion of a stator stage according to the invention, in particular a sealing assembly comprising a sealing ring 30 and a distributor 20. Furthermore, [Fig. 5] shows a detailed view of a portion V of the turbine portion of [Fig. 4].

[0057] The sealing ring 30 according to the invention is identical to the sealing ring 30 according to the prior art described above, and will therefore not be described again. Similarly, the characteristics of the distributor 20 according to the invention, identical to those of the distributor 20 according to the prior art described above, in particular the shape of the external platform 26 and the spoilers 264, 265, will not be described again.

[0058] Figure 6 also shows a perspective view of a sector 22 of the distributor 20 according to the invention. In this example, the sector 22 comprises six fixed vanes 24 extending between the inner platform 28 and the outer platform 26.

[0059] The distributor 20 of the sealing assembly according to the invention differs from that of the prior art, in that the sector 22 comprises an axial protrusion 25 disposed in the annular groove 29. The axial protrusion 25 extends axially upstream from a bottom 292 of the annular groove 29, and over a width L along the annular groove 29.

[0060] At its upstream end, the axial protuberance 25 comprises an upstream end face 252, which is flat and inscribed in a radial plane R perpendicular to the central axis X, and a recessed upstream face 254 which is disposed in recess relative to the upstream end face 252. In other words, the upstream end face 252 is disposed further upstream along the central axis X than the recessed upstream face 254.

[0061] The shape and dimensions of the axial protrusion 25 are such that, when the elements of the sealing assembly are assembled, a portion of the upstream end face 252 is positioned axially opposite a portion of the ring sector 32 comprising the plate 36 (Figures 4 and 5). In other words, the plate 36 extends in a plane P substantially parallel to the central axis X, the plane P intersecting the radial plane R comprising the upstream end face 252, preferably perpendicular to the latter.

[0062] Thus, a portion of the upstream end face 252 is disposed in the same radial position as the portion of the ring sector 32 comprising the plate 36, and is axially separated from a downstream end 322 of said portion of the ring sector 32 by an axial clearance J. In other words, the axial protrusion 25 allows the distributor 20 to be brought axially closer to said downstream end 322 of the ring sector 32, at the location of the plate 36. The downstream end 322 is therefore no longer axially separated from the distributor 20 by its distance from the bottom 292 of the annular groove 29, but by the axial clearance J.

[0063] The axial clearance J between the upstream end, more precisely the upstream end face 252 of the axial protrusion 25, and the downstream end 322 of the sealing ring 32, is between 0.07 mm and 1.3 mm, preferably equal to 1 mm, so as to take into account the differential expansions between the different parts.

[0064] Furthermore, the width L of the axial protrusion 25 is greater than the width d (image 2B) of the plate 36 in the circumferential direction. It is understood that the distributor 20 includes an axial protrusion 25 opposite axially each plate 36, and therefore includes as many axial protrusions 25 as there are plates 36.

[0065] Alternatively, the distributor 20 may include a single axial protrusion 25 extending over the entire length of the annular groove 29, i.e. over the entire circumference of the distributor 20. Consequently, the upstream end face 252 is axially separated from the downstream end 322 of the ring sectors 32 over the entire circumference of the distributor 20 and the ring 30.

[0066] It should be noted that the invention is not limited to the upstream end of the external platform 26, but could also be applied to configurations in which the axial protrusion 25 is disposed at the downstream end of the external platform 26, or at the level of the internal platform 28.

[0067] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

Claims

Demands

1. A sealing assembly for a turbomachine turbine (6) extending about a central axis (X), the turbine (6) comprising a fixed housing (10) having at least one internal hook (12) extending radially projecting from the housing (10) towards the central axis (X), the sealing assembly comprising: - a turbine distributor (20) centered on the central axis (X) and comprising at least one fixed blade (24) extending between a radially internal platform (28) and a radially external platform (26), the radially external platform (26) comprising an external upstream spoiler (264) adapted to engage with the internal hook (12), and an internal upstream spoiler (261) forming with the external upstream spoiler (264) an annular groove (29), the external upstream spoiler (264) being located radially outside the spoiler upstream internal (261), - a sealing ring (30) suitable for being fixed to the casing (10) and intended to surround a rotor stage (40) of the turbine,and comprising a plurality of ring sectors (32) mounted circumferentially end to end around the central axis (X), a first and a second circumferentially adjacent ring sectors (32) comprising respectively a first and a second slot (34), the first and second slots being arranged circumferentially opposite each other, and a sealing plate (36) comprising a first circumferential end disposed in the first slot and a second circumferential end disposed in the second slot, the distributor (20) comprising an axial protrusion (25) which extends axially in projection from the annular groove (29) so as to reduce an axial distance between the sealing ring (30) and the distributor (20), and being disposed axially opposite the sealing plate (36).

2. Assembly according to claim 1, wherein the axial protrusion (25) extends axially from a bottom (292) of the annular groove (29) towards the sealing ring (30), the sealing ring (30) being arranged upstream of the axial protrusion (25).

3. Assembly according to claim 1 or 2, wherein the axial protrusion (25) extends circumferentially over a distance (L) greater than a width (d) of the sealing plate (36).

4. Assembly according to any one of claims 1 to 3, in which the axial protuberance (25) includes a flat upstream end face (252) at least a portion of which is disposed in the same radial position as the sealing plate (36).

5. Assembly according to claim 4, wherein the axial protrusion (36) comprises a recessed upstream face (254) arranged further downstream than the upstream end face (252).

6. Assembly according to claim 4 or 5, wherein the upstream end face (252) of the axial protrusion (25) is radial with respect to the central axis (X).

7. Assembly according to any one of claims 1 to 6, wherein an axial clearance (J) between an upstream end of the axial protrusion (36) and the sealing ring (30) is less than 2 mm, preferably between 0.07 mm and 1.3 mm.

8. Assembly according to any one of claims 1 to 7, comprising a plurality of axial protrusions (25) distributed circumferentially around the central axis (X), and in which each pair of circumferentially adjacent ring sectors (32) comprises respectively a first and a second slot (34) arranged circumferentially opposite each other and in which is housed a sealing plate (36) comprising a first circumferential end disposed in the first slot (34) and a second circumferential end disposed in the second slot (34), each axial protrusion (25) being arranged axially opposite a sealing plate (36).

9. Assembly according to any one of claims 1 to 7, comprising a single axial protrusion (25) extending axially from a bottom (292) of the annular groove (29) to the sealing ring (30) over the entire circumference of the distributor (20).

10. Turbine (6) comprising a sealing assembly according to any one of the preceding claims, the turbine (6) being a low pressure turbine.

11. Turbomachine (100) comprising a turbine (6) according to claim 10.

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