Turbine ring assembly, turbine and turbomachine

Abstract

The invention relates to a turbine ring assembly provided with a sectorized CMC turbine ring and with a ring support structure (6), each sector (10) comprising a base (12) from which an upstream attachment tab (16) and a downstream attachment tab (14), which are axially spaced apart, extend radially outwards, the support structure (6) comprising an upstream radial flange (62) and a downstream radial flange (64) between which the attachment tabs (14, 16) are held. Opposite each inter-sector junction (100) between two adjacent ring sectors (10) in the circumferential direction (De), the downstream radial flange (64) comprises a fit-adjustment portion (70) machined in the thickness of the downstream radial flange (64), from an upstream face (642) of the downstream radial flange (64), and extending radially from the inner radial end (643) of the downstream radial flange (64), the thickness of the downstream radial flange (64) being measured in the axial direction (DA), and the fit-adjustment portion (70) of the downstream radial flange (64) being axially distant from the inter-sector junction (100) opposite which it is positioned.

Description

[0001] Description

[0002] TURBINE RING ASSEMBLY, TURBINE AND TURBOMACHINE

[0003] Technical Field

[0004] A turbine ring assembly for a turbomachine is provided wherein the assembly comprises a plurality of angular ring sectors of ceramic matrix composite material placed circumferentially end to end to form a turbine ring.

[0005] The field of application of the invention is in particular that of gas turbine aeronautical engines. The invention is however applicable to other turbomachines, for example industrial turbines.

[0006] Prior art

[0007] In the case of all-metal turbine ring assemblies, it is necessary to cool all the elements of the assembly and in particular the turbine ring which is subjected to the hottest flows. This cooling has a significant impact on the engine performance since the cooling flow used is taken from the primary flow of the engine. In addition, the use of a metallic material for the turbine ring limits the possibilities of increasing the temperature at the turbine level due to the mechanical limitations specific to this type of material, which would nevertheless improve the performance of aeronautical engines.

[0008] In an attempt to resolve these problems, it was considered to make the turbine ring with a ceramic matrix composite (CMC) material in order to avoid the use of a metallic material.

[0009] CMC materials have good mechanical properties making them suitable for forming structural elements and advantageously retain these properties at high temperatures. The use of CMC materials has advantageously made it possible to reduce the cooling flow required during operation and therefore to increase the performance of turbomachines. In addition, the use of CMC materials advantageously makes it possible to reduce the mass of turbomachines and to reduce the effect of hot expansion encountered with metal parts. Documents FR 2 540 939 and FR 2 955 898 are also known, which disclose turbine ring assemblies.

[0010] The ring comprises an annular base whose inner face defines the inner face of the turbine ring and an outer face from which two legs extend radially, the ends of which are held between the two flanges of a metal ring support structure.

[0011] The integration of a CMC ring includes a radial hold of the part partly ensured by one or more axial pins. In the known document FR 3 086 327, there are four pins for the hold, two upstream and two downstream.

[0012] Using a CMC material for the ring significantly reduces the ventilation required to cool the turbine ring, thus increasing efficiency. They also allow for weight savings because they are lighter than the metal alloys traditionally used.

[0013] However, since CMC has a different mechanical behavior from a metallic material, its integration and the way of positioning it within the turbine had to be rethought. Indeed, CMC can be damaged by shrink-fit assemblies (usually used for metallic rings) and its thermal expansion is lower than that of a metallic material.

[0014] There is a need to improve existing turbine ring assemblies and their mounting, and in particular existing turbine ring assemblies using CMC material in order to reduce the intensity of mechanical stresses to which the CMC ring is subjected during turbine operation.

[0015] CMC turbine rings are generally divided into several ring sectors. This integration choice is due to the fact that a single-piece ring would deform under the effect of high temperatures for this high-pressure turbine part. This would result in a clearance at the tip of the moving blade (in the opposite vein) that is locally too large and thus significantly degraded performance via a loss of turbine efficiency.

[0016] The consequence of this sectorization of the turbine ring is the creation of inter-sector clearances (between 0.1 mm and 1 mm). To limit leaks in these areas, sealing strips (also called sheets) are generally integrated between the ring sectors.

[0017] In the state of the art, the downstream contact in the axial direction is made by an annular radial flange (a 360° part) of a ring support coupled to the turbine casing. For sealing reasons, this annular radial flange must remain intact over its entire circumference due to the interfacing parts. It cannot therefore be sectorized, or semi-sectorized.

[0018] Sectorization would lead to leaks opening downstream in the axial direction at the inter-sector junctions. These leaks would depressurize the ring cavity and thus induce potential reintroductions of vein air.

[0019] The current trend in aviation is towards an increase in the temperature of the gases leaving the combustion chamber, leading to an increase in the temperature of the turbine components. The need to cool these parts is therefore increasingly important. The air that allows this cooling is taken from the outlet of the high-pressure compressor. This air will therefore bypass the combustion chamber without participating in combustion, thus leading to a decrease in the overall efficiency of the turbomachine.

[0020] In the current state of designs, inverted pi-shaped CMC rings are used. These inverted pi-shaped rings have a variability in size depending on the axial direction, in other words a variability in their axial width. This manufacturing variability leads to a sizing case called "short ring / long ring", consisting of a ring at the maximum dimension next to a ring at the minimum of this dimension, this can lead to stresses, particularly at the inter-sector junctions due to the tightening of the ring by the adjacent metal parts. Indeed, the non-sectorized annular downstream radial flange has a stiffness that does not allow it to conform to dimensional variations.

[0021] Statement of the invention

[0022] The main aim of the present invention is therefore to propose a turbine ring assembly which does not have the aforementioned drawbacks and which makes it possible to reduce the stress on the rings at the inter-sector junctions without, however, degrading the pressurization of the ring cavity.This aim is achieved by means of a turbine ring assembly comprising a plurality of ring sectors made of ceramic matrix composite material forming a turbine ring, defining an axial direction, a radial direction and a circumferential direction, as well as a plurality of inter-sector junctions in the circumferential direction, the turbine ring assembly further comprising a ring support structure, each ring sector comprising a base from which an upstream attachment lug and a downstream attachment lug axially spaced from one another extend radially outwards, and the ring support structure comprising an upstream radial flange and a downstream radial flange between which the upstream attachment lug and the downstream attachment lug of each ring sector are held.

[0023] In other words, the ring sectors are arranged in the circumferential direction by being placed end to end. This arrangement thus defines inter-sector junctions, each inter-sector junction corresponding to the interval between two adjacent ring sectors in the circumferential direction.

[0024] The turbine ring assembly according to the invention is remarkable in particular in that, opposite each inter-sector junction between two adjacent ring sectors in the circumferential direction, the downstream radial flange comprises a fitting portion machined hollow in the thickness of the downstream radial flange, from an upstream face of the downstream radial flange, and extending radially from the inner radial end of the downstream radial flange, the thickness of the downstream radial flange being measured in the axial direction, and the fitting portion of the downstream radial flange being axially distant from the inter-sector junction opposite which it is arranged.

[0025] Machining the downstream radial flange to reduce its axial thickness at each of the inter-sector junctions to form a fitting portion allows the downstream radial flange of the ring support to better conform to the stresses, in particular thermal, during operation of the turbomachine in which the ring assembly is mounted, and thus to limit the shear observed at the inter-sector junctions of the CMC turbine ring, in particular by redirecting the force flow to a less sensitive area of ​​the turbine ring. Reducing the thickness of the downstream radial flange forms a relief, i.e. a shortening of the axial thickness. This relief allows the fitting portions of the downstream radial flange to no longer be in direct contact with the turbine ring.

[0026] According to a first aspect of the turbine ring assembly, each adjustment portion of the downstream radial flange may comprise a housing hollowed out in the thickness of the downstream radial flange.

[0027] Preferably, the housing has an overall rectangular shape, with the corners of the rectangle being rounded or not.

[0028] According to a second aspect of the turbine ring assembly, each adjustment portion of the downstream radial flange may further comprise a folded sheet inserted into said housing to maintain a seal between the downstream radial flange and the turbine ring.

[0029] The folded sheets inserted into the housings make it possible to close the space in the axial direction between the adjustment portion of the downstream radial flange and the ring, and thus to form a seal to prevent leaks in the radial direction between the vein sector and the non-vein sector. The folded sheets make it possible to avoid any depressurization of the ring cavity and thus to avoid reintroduction of vein air.

[0030] According to a third aspect of the turbine ring assembly, the housing may comprise a radially internal shoulder, a radially external shoulder, a wall extending between the radially external shoulder and the radially internal shoulder and closing the housing upstream in the axial direction, the housing opening axially downstream, in other words being open axially downstream, and the folded sheet may comprise a radially external portion bearing against the radially external shoulder of the housing, a radially internal portion bearing against the radially internal shoulder of the housing, and a central portion extending between the radially external portion and the radially internal portion and arranged bearing against said wall of the housing, the radially internal portion being axially longer than the radially internal shoulder and extending axially between the radially internal shoulder of the housing and the turbine ring.More particularly, the folded sheet metal may comprise a radially external tongue bearing against the radially external shoulder of the housing, a radially internal tongue of which at least a portion bears against the radially internal shoulder of the housing, and a central portion extending between the radially external tongue and the radially internal tongue and arranged to bear against said wall of the housing, the radially internal tongue being axially longer than the radially internal shoulder and comprising a portion extending axially between the radially internal shoulder of the housing and the turbine ring.

[0031] The conformation of the housing and that of the folded sheet metal ensure radial and axial support of the folded sheet metal in its housing.

[0032] According to a fourth aspect of the turbine ring assembly, the housing may comprise a first circumferential shoulder and a second circumferential shoulder opposite the first circumferential shoulder in the circumferential direction, the folded sheet being housed, in the circumferential direction, between the first circumferential shoulder and the second circumferential shoulder, thereby ensuring that the folded sheet is held in the circumferential direction (tangential hold).

[0033] According to a fifth aspect of the turbine ring assembly, each adjustment portion of the downstream radial flange may further comprise a radial slot open on an inner radial end of the downstream radial flange and extending over a radial portion of the downstream radial flange, the radial slot being arranged opposite an inter-sector junction.

[0034] The open radial slot on an inner radial end of the downstream radial flange provided in each housing allows for semi-sectorization of the downstream radial flange and thus allows it to better conform to the constraints and thus further limit shear.

[0035] According to a sixth aspect of the turbine ring assembly, for each adjustment portion, the folded sheet inserted into said housing preferably covers said radial slot to maximize sealing.

[0036] According to a seventh aspect of the turbine ring assembly, each ring sector may comprise, at each of its circumferential ends, at least one groove extending axially and / or radially and at least one inter-sector sealing pad inserted in a groove, the inter-sector sealing pad having a width in the circumferential direction greater than the depth of the groove measured in the circumferential direction.

[0037] The invention also relates to a turbine comprising a casing and a ring assembly as defined above.

[0038] The invention also relates to a turbomachine comprising a turbine as defined above.

[0039] The invention can be applied to any turbine stage comprising a ring made of ceramic matrix composite material.

[0040] Brief description of the drawings

[0041] [Fig. 1] Figure 1 is a schematic sectional view along a plane including the axial direction and the radial direction of a turbine ring assembly according to the invention.

[0042] [Fig. 2] Figure 2 shows an exploded perspective view of a portion of the ring support of the turbine ring assembly of Figure 1.

[0043] [Fig. 3] Figure 3 shows an assembled perspective view of a portion of the ring support of the turbine ring assembly of Figure 1.

[0044] [Fig. 4] Figure 4 represents a schematic view of an aircraft.

[0045] [Fig. 5] Figure 5 schematically represents a sectional view of an upper half of a turbomachine of the aircraft according to the invention.

[0046] Description of the embodiments

[0047] Figure 1 schematically represents a turbine ring assembly according to a first embodiment of the invention. Figure 1 is a sectional view along a plane comprising the radial direction D R and the axial direction D and orthogonal to the circumferential direction D c .

[0048] The turbine ring assembly shown in Figures 1 and 2 includes in particular a turbine ring made of ceramic matrix composite (CMC) material centered on a longitudinal axis XX, a metallic ring support structure 6 fixed to a turbine casing not shown for clarity. The turbine ring surrounds a set of turbine blades not shown.

[0049] The circumferential direction D c being a circular direction centered on the longitudinal axis XX.

[0050] Subsequently, throughout the text, the terms "upstream" and "downstream" are used in reference to the direction of flow of the gas stream F through the blades indicated by an arrow.

[0051] Furthermore, the turbine ring is formed from a plurality of angular ring sectors 10 which are placed end to end in the circumferential direction to form a ring. In Figure 1, the arrow D indicates the axial direction of the turbine ring while the arrow DR indicates the radial direction of the turbine ring.

[0052] Each angular ring sector 10 has a section substantially in the shape of an inverted Pi (or ii) with a base 12 provided with an internal face 12a which defines an angular portion of the internal face of the turbine ring and which is typically provided with a layer of abradable coating 13 also acting as a thermal and environmental barrier.

[0053] Two axially spaced hooking lugs, a downstream hooking lug 14 and an upstream hooking lug 16, extend radially from the outer face 12b of the base 12 opposite the inner face 12a. These downstream and upstream hooking lugs 14 and 16 extend over the entire width of each angular ring sector 10 (in the circumferential direction).

[0054] The ring support structure 6 comprises a ferrule 60 extending about the axis XX, as well as an upstream radial flange 62 and a downstream radial flange 64 extending radially inward from the ferrule 60. The downstream radial flange 64 comprises an attachment portion 640 projecting radially from the ferrule 60, and the upstream radial flange 62 comprises an attachment portion 620 projecting radially from the ferrule 60, as well as an upstream flange 20 fixed to the attachment portion 620 projecting radially from the upstream radial flange 62 using bolts and nuts not shown. The bolts pass axially through the upstream flange 20 and the attachment portion 620 of the upstream radial flange 62. The upstream radial flange 62 and the downstream radial flange 64 thus form two ring attachment flanges, the downstream attachment lug 14 and the upstream attachment lug 16 of the angular ring sectors 10 being arranged axially between the upstream radial flange 62 and the downstream radial flange 64.

[0055] The turbine ring assembly further comprises upstream pins 40 and downstream pins not shown to simplify reading of the figures. The upstream pins 40 pass through the upstream flange 20 of the upstream radial flange 62 as well as the upstream attachment lug 16 of an angular ring sector 10. The downstream pins pass at least partially through the downstream radial flange 64, and more particularly the radially projecting attachment portion 640, as well as the downstream attachment lug 14.

[0056] As illustrated in Figure 1, the ring assembly further comprises at each inter-sector junction 100 between two adjacent angular ring sectors 10 along the circumferential direction D c , at least one seal not shown cooperating with grooves 120. The seal is arranged between the bases 12 of the two adjacent angular ring sectors 10, and extends mainly in the axial direction D A, that is, the base of the cylindrical shape extends in a plane orthogonal to the axial direction D A and the generatrices of the cylindrical shape extend parallel to the axial direction D A .

[0057] Opposite each inter-sector junction 100 between two angular ring sectors 10 adjacent in the circumferential direction, the downstream radial flange 64 further comprises an adjustment portion 70 machined in the thickness of the downstream radial flange 64, the thickness of the downstream radial flange 64 being measured in the axial direction D A .

[0058] The adjustment portion 70 comprises a housing 71 machined in the thickness of the downstream radial flange 64 from an upstream face 642 of the downstream radial flange 64, and a folded sealing sheet 72 which is inserted into the housing 71 to maintain a radial seal between the downstream radial flange 64 and the turbine ring.

[0059] In Figures 2 and 3 are shown respectively an exploded perspective view and an assembled perspective view of a portion of the ring support of the turbine ring assembly of Figure 1.

[0060] As illustrated in Figures 1 to 3, the downstream radial flange 64 comprises, in the radial direction DR, a radially inner end 643 and a radially outer end 644. The radially outer end 623 is free while the radially outer end is secured to the central ferrule 60 of the ring support 6. The adjustment portion 70 extends in the radial direction DR from the radially inner end 643 of the downstream radial flange 64, and over a part of the attachment portion 640 of the downstream radial flange 64.

[0061] The housing 71 is formed by machining a portion of the downstream radial flange 64. For each housing 71, the upstream face 642 of the downstream radial flange 64 is machined to form a radially internal shoulder 711, a radially external shoulder 712 facing the radially internal shoulder 711 in the radial direction DR, a first circumferential shoulder 713 and a second circumferential shoulder 714 facing the first circumferential shoulder 713 in the circumferential direction D. c The housing 71 is machined hollow only over a portion of the axial thickness of the downstream radial flange 64. It thus comprises a bottom 710, formed by a wall extending in the radial direction D R between the radially internal shoulder 711 and the radially external shoulder 712, and extending in the circumferential direction D c between the first circumferential shoulder 713 and the second circumferential shoulder 714.

[0062] The housing 71 is hollow machined so that, in the axial direction D A , the radially internal shoulder 711 is set back relative to the upstream face 642 of the downstream radial flange 64. In other words, the radially internal shoulder 711 has axial dimensions allowing it to start axially downstream of the upstream face 642 of the downstream radial flange 64.

[0063] Thus, according to the axial direction D A , the radially internal shoulder 711 is axially distant from the inter-sector junction 100 opposite which it is arranged.

[0064] As illustrated in Figures 1 and 2, the sealing sheet 72 has a C-shaped section along a cutting plane parallel to the axial direction D A and to the radial direction DR, in other words in a cutting plane orthogonal to the circumferential direction D c .

[0065] As illustrated in FIG. 2, the sealing sheet 72 thus comprises a radially external tongue 721 located at a radially external end of the sealing sheet 72, a radially internal tongue 722 located at a radially external end of the sealing sheet 72, and a central portion 723 extending between the radially external tongue 721 and the radially internal tongue 722.

[0066] The radially inner tab 722 comprises a first portion 724 extending parallel to the radially outer tab 721 and with an axial length corresponding to the axial length of the radially inner shoulder 711, and a second portion 725 extending in the axial direction D between the first portion 724 and the turbine ring.

[0067] As illustrated in Figures 1 and 3, the radially external tab 721 bears against the radially external shoulder 712 of the housing, the first portion 724 of the radially internal tab 722 bears against the radially internal shoulder 711 of the housing, and the central portion 723 is arranged to bear against the bottom 710 of the housing 71.

[0068] The sealing sheet 72 has dimensions in the circumferential direction D c adjusted to the bottom 710 and thus allowing it to be held in the circumferential direction D c between the first circumferential shoulder 713 and the second circumferential shoulder 714.

[0069] Each adjustment portion 70 of the downstream radial flange 64 further comprises a radial slot 75 open on the radially inner end 643 of the downstream radial flange 64 and extending over a radial portion of the downstream radial flange 64, the radial slot 75 being arranged opposite an inter-sector junction 100.

[0070] The open radial slot 75 provided in each housing 71 makes it possible to achieve a semi-sectorization of the downstream radial flange 64 and thus to allow it to conform better according to the constraints and thus to limit the shear even more.

[0071] The sealing sheet 72 is disposed in the housing to cover the radial slot 75 to maximize sealing.

[0072] In Figure 4 is shown a schematic view of an aircraft 1 comprising a nose 2, a tail 3, a main axis Y extending between the nose 2 and the tail 3 of the aircraft 1, two wings 4 each extending on one side of the main axis Y, and two turbomachines 5 arranged symmetrically with respect to the main axis Y, each turbomachine 5 being mounted on a separate wing 4. In Figure 5, is shown schematically a sectional view of an upper half of a turbomachine 5 of the aircraft 1.

[0073] In the example illustrated in Figure 4, each turbomachine 5 of the aircraft 1 is a twin-spool, twin-flow turbomachine. The turbomachine 5 comprises, from upstream to downstream along an axis X (parallel to the main axis Y) of the turbomachine 5 in the direction of gas flow, an air inlet 50, a fan 51, a low-pressure (or LP) compressor 52, a high-pressure (or HP) compressor 53, a combustion chamber 54, a high-pressure turbine 55, and a low-pressure turbine 56.

[0074] The turbomachine 5 further comprises a primary vein 57 and a secondary vein 58 separated by an intermediate casing 59. The primary vein 57 extends downstream of the fan 51 and is delimited radially by the intermediate casing 59. The primary vein 57 comprises the low-pressure compressor 52, the high-pressure compressor 53, the combustion chamber 54 and the high- and low-pressure turbines 55 and 56. The secondary vein 58 extends around the primary vein 57, also downstream of the fan 51. The secondary vein 58 extends radially between the intermediate casing 59 and an external casing extending around the intermediate casing 59.

[0075] At least one of the high pressure 55 or low pressure 56 turbines comprises a ring assembly 2 of figures 1 to 3. The present invention thus proposes a turbine ring assembly making it possible to reduce the stress on the rings at the inter-sector junctions without degrading the pressurization of the ring cavity.

Claims

Claims

1. Turbine ring assembly comprising a plurality of ring sectors (10) of ceramic matrix composite material forming a turbine ring, defining an axial direction (D A ), a radial direction (D R ), a circumferential direction (D c ), as well as a plurality of inter-sector junctions (100) in the circumferential direction (D c), the turbine ring assembly further comprising a ring support structure (6), each ring sector (10) comprising a base (12) from which an upstream hooking lug (16) and a downstream hooking lug (14) axially spaced from each other extend radially outwards, and the ring support structure (6) comprising an upstream radial flange (62) and a downstream radial flange (64) between which the upstream hooking lug (16) and the downstream hooking lug (14) of each ring sector (10) are held, characterized in that, opposite each inter-sector junction (100) between two ring sectors (10) adjacent in the circumferential direction (D c), the downstream radial flange (64) comprises an adjustment portion (70) machined hollow in the thickness of the downstream radial flange (64), from an upstream face (642) of the downstream radial flange (64), and extending radially from the radially inner end (643) of the downstream radial flange (64), the thickness of the downstream radial flange (64) being measured in the axial direction (D A ), and the adjustment portion (70) of the downstream radial flange (64) being axially distant from the inter-sector junction opposite which it is arranged.

2. A turbine ring assembly according to claim 1, wherein each fitting portion (70) of the downstream radial flange (64) comprises a housing (71) hollowed out in the thickness of the downstream radial flange (64).

3. A turbine ring assembly according to claim 2, wherein the housing (71) has an overall rectangular shape, the corners of the rectangle being rounded or not.

4. Turbine ring assembly (2) according to one of claims 2 or 3, each adjustment portion (70) of the downstream radial flange (64) further comprises a folded sheet metal (72) inserted into said housing (71) to maintain a seal between the downstream radial flange (64) and the turbine ring.

5. Turbine ring assembly according to one of claims 2 to 4, in which the housing (71) comprises a radially internal shoulder (711), a radially external shoulder (712), a wall (710) extending between the radially external shoulder (712) and the radially internal shoulder (711) and closing the housing (71) upstream in the axial direction (D A), the housing (71) opening axially downstream, and the folded sheet (72) comprises a radially external portion (721) bearing against the radially external shoulder (712) of the housing (71), a radially internal portion (722) bearing against the radially internal shoulder (711) of the housing (71), and a central portion (723) extending between the radially external portion (721) and the radially internal portion (722) and arranged bearing against said wall (710) of the housing (71), the radially internal portion (722) being axially longer than the radially internal shoulder (711) and extending axially between the radially internal shoulder (711) of the housing (71) and the turbine ring.

6. A turbine ring assembly according to one of claims 2 to 5, wherein the housing (71) comprises a first circumferential shoulder (713) and a second circumferential shoulder (714) opposite the first circumferential shoulder (713) in the circumferential direction (D c ), the folded sheet (72) being housed, in the circumferential direction (De) between the first circumferential shoulder (713) and the second circumferential shoulder (714).

7. Turbine ring assembly according to one of claims 1 to 6, wherein each adjustment portion (70) of the downstream radial flange (64) further comprises a radial slot (75) which opens onto the radially inner end (643) of the downstream radial flange (64) and extending over a radial portion of the downstream radial flange (64), the radial slot (75) being arranged opposite an inter-sector junction (100).

8. A turbine ring assembly according to claim 7 in combination with one of claims 2 to 6, wherein, for each fitting portion (70), the folded sheet metal (72) inserted into said housing (71) covers said radial slot (75).

9. A turbine ring assembly according to one of claims 1 to 8, wherein each ring sector (10) comprises, at each of its circumferential ends, at least one groove extending axially and / or radially and at least one inter-sector sealing plate inserted in a groove, the inter-sector sealing plate having a width in the circumferential direction (D c ) greater than the depth of the groove measured in the circumferential direction (D c ).

10. A turbine comprising a casing and a turbine ring assembly according to one of claims 1 to 9.

11. A turbomachine comprising a turbine according to claim 10.

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