Turbine assembly for a turbomachine
The turbine assembly addresses wear issues by using a metal alloy interface element between CMC ring sectors and metal support flanges, ensuring thermal expansion compensation and maintaining sealing integrity for improved turbomachine performance.
Patent Information
- Application Number
- FR2022012305
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-11-24
- Publication Date
- 2025-01-10
- Estimated Expiration
- 2042-11-24
AI Technical Summary
Wear occurs at the contact surfaces between the ceramic matrix composite (CMC) ring and the metal support in a turbomachine's high pressure turbine due to differential thermal expansion, leading to sealing loss and reduced performance.
A turbine assembly with a ceramic matrix composite ring sectors and a metal support, featuring an interface element made of high-temperature metal alloy interposed between the flanges, allowing for differential expansion compensation and reducing wear.
The solution minimizes wear and maintains sealing integrity, enhancing turbomachine performance and reducing maintenance costs by allowing easy replacement of worn interface elements.
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Abstract
Description
Title of the invention: Turbine assembly for a turbomachine Technical field of the invention
[0001] The invention relates to a turbine assembly for a turbomachine, intended to equip in particular a high pressure turbine. State of the prior art
[0002] Figures 1 to 3 illustrate a turbomachine and a turbine assembly of the prior art, known from document FR 3 108 671 in the name of the Applicant.
[0003] In particular, [Fig.l] illustrates a propulsion unit 1 intended for an aircraft and comprising a turbomachine 2 shrouded by a nacelle 3. In the example shown, the turbomachine 2 is a twin-spool, twin-flow turbojet.
[0004] This [Fig.l] includes a reference frame DA, DR and DC which respectively defines the longitudinal (axial), radial and circumferential directions of the turbomachine, these directions being orthogonal to each other.
[0005] In the remainder of this description, the terms “upstream” and “downstream” are defined relative to the flow direction of the gas flow F through the turbomachine 2, i.e. from left to right in [Fig.l].
[0006] The turbojet 2 extends around a longitudinal axis X and comprises, from upstream to downstream, a fan 4, a low-pressure compressor 5, a high-pressure compressor 6, a combustion chamber 7, a high-pressure turbine 8 and a low-pressure turbine 9.
[0007] During operation of the turbojet 2, an air flow F enters the propulsion unit 1 from upstream of the nacelle 3, then passes through the fan 4 and is then divided into a central primary flow F1 and a peripheral secondary flow F2. The primary flow F1 flows in a main gas circulation vein 10 successively passing through the compressors 5 and 6, the combustion chamber 7 and the turbines 8 and 9. The secondary flow F2 flows in a peripheral secondary vein 11, delimited radially on the outside by the nacelle 3.
[0008] In order to ensure good performance of the high-pressure turbine 8 when subjected to hot gases from the combustion chamber, the high-pressure turbine 8 comprises an external stator comprising a ring 12 made of ceramic matrix composite (CMC) material. The integration of this ring 12 in CMC, the temperature resistance of which is high, makes it possible to reduce the flow of cooling air taken upstream of the high-pressure turbine 8, and thus makes it possible to improve the performance and / or the fuel consumption of the turbomachine 2.
[0009] Figures 2 to 4 are detailed views, in axial section, illustrating the assembly of a such turbine ring 12.
[0010] Said ring 12 surrounds a turbine rotor comprising blades 13, said ring 12 being formed from a plurality of ring sectors 14 (only one of which is visible in FIGS. 3 and 4).
[0011] Each ring sector 14 has an axially extending portion 15 or annular base as well as an upstream flange 16 and a downstream flange 17, axially offset from each other and extending radially outwards from the base 15.
[0012] Each CMC ring sector 14 is mounted on a metal annular support 18 of a fixed casing of the turbine, surrounding said ring 12. The annular support 18 comprises an axially extending annular part 19, also called a shell, as well as an upstream flange 20 and a downstream flange 21, hereinafter called complementary flanges, extending radially inwards from the shell 19.
[0013] The upstream flange 16 of each sector 14 bears in the axial direction DA on the complementary upstream flange 20 of the support 18. Similarly, the downstream flange 17 of each sector 14 bears in the axial direction on the complementary downstream flange 21 of the support 18.
[0014] The ring 12 and the support 18 extend around the axis X of the turbomachine 2.
[0015] Other means, such as annular flanges, pins 22 and screw / nuts (not shown) make it possible to immobilize the ring sectors 14, both in the axial and radial direction, as is known in particular from document EP 3 857 030 in the name of the Applicant.
[0016] In particular, pins 22 secured to the flanges 20, 21 of the support 18 are engaged in oblong holes in the flanges 16, 17 of the ring 12, as illustrated in [Fig.2].
[0017] Downstream of the shell 19 and more precisely downstream of the complementary downstream flange 21, the structure is generally extended axially by a set of annular partitions 23, 24, some of which serve in particular to hold a radially external platform 25 of a distributor 26 of the low-pressure turbine 9. Blades 27 extend radially inwards from the external platform 25. The distributor 26 is mounted, via a hook 28, at a mounting zone in a groove 29 of the support 18. In particular, the groove 29 is delimited radially between the partitions 23, 24 and opens downstream, the hook 28 comprising an axial part engaged at least partially in the groove 29.
[0018] In operation, it has been observed that wear occurs at the contact surfaces 30 between the flanges 16, 17, 20, 21 of the ring 12 and the support 18, due to the forces passing through these zones as well as to the differences in thermal expansion between the CMC ring 12 and the metal support 18. In fact, the CMC ring 12 expands four times less than the metal ring 18. Such wear can cause a loss of sealing of the support zones concerned and thus make it possible to introduce of air from the primary stream to the metal casing, leading to its heating and a reduction in its service life. Such a loss of sealing can also lead to a loss of performance of the turbomachine. Presentation of the invention
[0019] This document aims to remedy this drawback, in a simple, reliable and inexpensive manner.
[0020] To this end, the invention relates to a turbine assembly for a turbomachine, extending around an axis and comprising
[0021] - a plurality of ring sectors forming a turbine ring, each sector ring comprising an axial portion and at least one flange extending radially outward from said axial portion of the sector,
[0022] - a support surrounding said ring, each ring sector being mounted on said support, said support comprising an axial portion and at least one complementary flange extending radially inwards from said axial portion of the support,
[0023] the flange of each sector being made at least partially of ceramic matrix material and bearing axially on the complementary flange of the support, made at least partially of metallic material,
[0024] characterized in that it comprises at least one interface element made of metallic material integral with the sector flange and interposed between the ceramic material part of the sector flange and the metallic part of the complementary flange of the support, the sector flange bearing on the complementary flange of the support via the interface element.
[0025] In this way, it is possible to use a ring made at least partly of CMC so as to benefit from the advantages of such a material (resistance to high temperatures, low mass) while benefiting from contact surfaces of the same nature, through the metal interface element and the complementary metal flange of the support. This limits or avoids the phenomena of differential expansion causing wear, as mentioned above. The interface element can be removably mounted on the sector flange.
[0026] It is thus possible to easily change the interface element in the event of wear thereof. Thus, during a maintenance operation, only the interface elements showing wear can be changed. This presents an economic advantage compared to the complete change or reconditioning of the flange.
[0027] Each sector may comprise two flanges axially offset from each other and each extending radially outwards from the axial portion of the sector, and in which the support comprises two complementary flanges axially offset from each other and each extending radially inwards from the axial portion axial of the support, at least one metallic interface element being interposed between at least one of the flanges of the sector and the corresponding complementary flange of the support.
[0028] For each ring sector, the axial part and the flange of said sector can be made in a single piece from ceramic matrix composite material.
[0029] The axial part and the complementary flange of the support can be made in a single piece from metallic material.
[0030] The interface element can be made of a high-temperature metal alloy, based on nickel or cobalt for example (Inconel, Waspaloy, etc.).
[0031] The metal part of the complementary flange of the support can be made of high temperature metal alloy, based on nickel or cobalt for example (Inconel, Waspaloy, etc.).
[0032] Alternatively, the interface element and / or the complementary part of the support flange may be made of monolithic oxide (e.g.: A12O3 alumina), for example by providing a circumferential degree of freedom. Such materials have an intermediate coefficient of thermal expansion (8.0E-6°Cl), located between the coefficient of thermal expansion of a carbide-based CMC type material (4.5E-6°C-1) and the coefficient of thermal expansion of the metal (15E-6°C-1). The monolithic oxide has the advantage of distributing the differential expansion and expanding in an intermediate manner, while being relatively hard. Wear is then less present.
[0033] The interface element may be mounted, at least in part, in a recessed area of the sector flange.
[0034] Said hollow zone may be offset radially relative to the radially outer end of the corresponding flange of the sector. In other words, said hollow zone does not open radially outwards, at the free end (i.e. the radially outer end) of the corresponding flange.
[0035] The sector flange and the interface element may each extend circumferentially in an arc of a circle.
[0036] The interface element may have a flat surface extending radially, bearing axially on the complementary flange of the support.
[0037] Alternatively, the interface element may have a convex curved surface, axially supported on the complementary flange of the support. Such a curved surface makes it possible to promote continuous support during possible deformation of the flanges under thermal and mechanical loading.
[0038] The complementary flange of the support may have a flat surface extending radially, bearing on the interface element.
[0039] The sector may comprise at least one sealing slot intended to house one or more sealing sheets. Preferably, the interface element is located radially outside of said slot.
[0040] The present document also relates to a turbine for a turbomachine comprising an assembly of the aforementioned type.
[0041] The present document further relates to a turbomachine comprising a turbine of the aforementioned type. Brief description of the figures
[0042] [Fig-1] is an axial sectional view of a propulsion assembly of the prior art,
[0043] [Fig.2] is a detailed and axial sectional view illustrating the assembly of a part of the high pressure turbine, according to the prior art,
[0044] [Fig.3] is a detailed and axial sectional view of a part of the high pressure turbine and a distributor located downstream, according to the prior art,
[0045] [Fig.4] is a detailed and axial sectional view of a part of the high pressure turbine and a distributor located downstream, according to the prior art,
[0046] [Fig.5] is a schematic axial sectional view illustrating the support of a flange of a segment of the ring on a complementary flange of the support, through an interface element, in accordance with an embodiment of the present document,
[0047] [Fig.6] is a view corresponding to [Fig.5], of another embodiment of the present document. Detailed description of the invention
[0048] [Fig. 5] illustrates a part of a CMC ring 12 similar to that described previously, formed of several CMC sectors 14 and each comprising a part 15 extending axially or annular base as well as an upstream flange 16 and a downstream flange 17, axially offset from each other and extending radially outwards from the base 15.
[0049] Each CMC ring sector is mounted on a metal annular support 18 of a fixed casing of the turbine, surrounding said ring 12. The annular support 18 comprises an axially extending annular part 19, also called a shell, as well as an upstream complementary flange 20 and a downstream complementary flange 21, extending radially inwards from the shell 19.
[0050] The upstream flange 16 of each sector 14 bears in the axial direction DA on the complementary upstream flange 20 of the support 18, by means of an upstream interface element 31. Similarly, as illustrated in [Fig.5], the downstream flange 17 of each sector 14 bears in the axial direction DA on the complementary downstream flange 21 of the support 18, by means of a downstream interface element 31.
[0051] Other means, such as annular flanges, pins 22 and screw / nut assemblies make it possible to immobilize the ring sectors 14, both in the axial direction DA and the radial direction DR. In particular, pins 22 secured to the flanges 20, 21 of the support 18 are engaged in oblong holes of the flanges 16, 17 of the ring 12.
[0052] Each interface element 31 is removably mounted in a recessed area 32 or groove of the corresponding flange 16, 17 of the sector 14. In particular, each interface element 31 and each recessed area 32 have an arcuate shape and extend in the circumferential direction. Each interface element 31 comprises a mounting portion 33 engaged in the corresponding groove 32 and a bearing portion 34 defining a radial bearing surface 30, extending circumferentially in an arc of a circle. The corresponding complementary flange 20, 21 of the support 18 also comprises a complementary radial flat bearing surface 30a, bearing on the corresponding bearing surface 30.
[0053] Alternatively, the surface 30 may be a convex curved surface.
[0054] Each interface element 31 is made of metal, for example a high-temperature metal alloy, based on nickel or cobalt for example (Inconel, Waspaloy, etc.). Furthermore, each complementary flange 20, 21 is made of a high-temperature metal alloy, based on nickel or cobalt for example (Inconel, Waspaloy, etc.).
[0055] As illustrated in [Fig. 5], the flange 17 and possibly the axial part 15 of the sector 14 may comprise at least one sealing slot 35 intended to house one or more sealing sheets. Preferably, the interface element 31, in particular the mounting part 33, is located radially outside the slot 35.
[0056] The radial dimension a of the mounting portion 33 may be between 2.5 and 6 mm. The axial dimension b of the mounting portion 33 may be between 0.5 and 2 mm.
[0057] The axial dimension c of the bearing portion 34 may be between 0.5 and 3 mm. The radial dimension d of the bearing zone between the surfaces 30 and 30a may be between 1.5 and 5 mm, for example of the order of 2 mm.
[0058] [Fig. 6] illustrates an alternative embodiment in which the hollow zone 32 is offset radially inwards relative to [Fig. 5]. The radial position of this hollow zone 32 can thus vary depending on the applications. Preferably, this hollow zone 32 is offset radially relative to the radially outer end 17a of the corresponding flange 17 of the sector 14. In other words, said hollow zone 32 does not open radially outwards, at the free end 17a (i.e. the radially outer end 17a) of the corresponding flange 17.
Claims
1.
2.
3. Claims Turbine assembly for a turbomachine (2), extending around an axis and comprising - a plurality of ring sectors (14) forming a turbine ring (12), each ring sector (14) comprising an axial portion (15) and at least one flange (16, 17) extending radially outwards from said axial portion (15) of the sector (14), - a support (18) surrounding said ring (12), each ring sector (14) being mounted on said support (18), said support (18) comprising an axial part (19) and at least one complementary flange (20, 21) extending radially inwards from said axial part (19) of the support (18), the flange (16, 17) of each sector (14) being made at least partially of ceramic matrix material and coming into axial support on the complementary flange (20, 21) of the support (18), made at least partially of metallic material, characterized in that it comprises at least one interface element (31) made of metallic material integral with the flange (16, 17) of the sector (14) and interposed between the part made of ceramic material of the flange (16, 17) of the sector (14) and the metallic part of the complementary flange (20, 21) of the support (18), the flange (16, 17) of the sector (14) coming to bear on the complementary flange (20, 21) of the support (18) via the interface element (31), the interface element having a flat surface or a convex curved surface, axially supported on the complementary flange of the support. Turbine assembly according to the preceding claim, in which the interface element (31) is removably mounted on the flange (16, 17) of the sector (14). Turbine assembly according to one of the preceding claims, in which each sector (14) comprises two flanges (16, 17) axially offset from each other and each extending radially outwards from the axial part (15) of the sector (14), and in which the support (18) comprises two complementary flanges (20, 21) axially offset from each other and each extending radially outwards the interior from the axial part (19) of the support (18), at least one metallic interface element (31) being interposed between at least one of the flanges (16, 17) of the sector (14) and the corresponding complementary flange (20, 21) of the support (18).
4. Turbine assembly according to one of the preceding claims, in which, for each ring sector (14), the axial part (15) and the flange (16, 17) of said sector (14) are made in a single piece from ceramic matrix composite material.
5. Turbine assembly according to one of the preceding claims, in which the axial part (19) and the complementary flange (20, 21) of the support (18) are made in a single piece of metallic material.
6. Turbine assembly according to one of the preceding claims, in which the interface element (31) is made of a nickel or cobalt-based metal alloy.
7. Turbine assembly according to one of the preceding claims, in which the metal part of the complementary flange (20, 21) of the support (18) is made of a nickel or cobalt-based metal alloy.
8. Turbine assembly according to one of the preceding claims, wherein the interface element (31) is mounted, at least in part, in a hollow zone (32) of the flange (16, 17) of the sector (14).
9. Turbine assembly according to one of the preceding claims, in which the flange (16, 17) of the sector (14) and the interface element (31) each extend circumferentially in an arc of a circle.
10. Turbine for a turbomachine (2) comprising an assembly according to one of the preceding claims.