Turbine ring assembly with improved radial flange

Abstract

Turbine ring assembly with improved radial flange The invention relates to a turbine ring assembly (2) having a CMC sectorized turbine ring (4) and a ring support structure (6), each sector (10) comprising a base (12) from which extend radially outwards an upstream attachment lug (16) and a downstream attachment lug (14) axially spaced, the support structure (6) comprising an upstream radial flange (62) and a downstream radial flange (64) between which the attachment lugs (14, 16) are held.Opposite each inter-sector junction (100) between two adjacent ring sectors (10) in the circumferential direction (DC), the downstream radial flange (64) includes a fitting portion (70) machined from the thickness of the downstream radial flange (64), extending 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 along the axial direction (DA), and the fitting portion (70) of the downstream radial flange (64) being axially distant from the inter-sector junction (100) opposite which it is positioned. Figure for the abbreviation: Fig. 1.

Description

Title of the invention: Turbine ring assembly with improved radial flange technical field

[0001] The invention relates to a turbine ring assembly for a turbomachine in which the assembly comprises a plurality of angular ring sectors made of ceramic matrix composite material placed circumferentially end to end to form a turbine ring.

[0002] The field of application of the invention is notably that of aeronautical gas turbine engines. The invention is however applicable to other turbomachinery, for example industrial turbines. Previous technique

[0003] 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 flow. This cooling has a significant impact on engine performance since the cooling flow used is drawn from the engine's primary flow. Furthermore, the use of a metallic material for the turbine ring limits the possibilities of increasing the turbine temperature due to the inherent mechanical limitations of this type of material, which would nevertheless allow for improved performance of aircraft engines.

[0004] In an attempt to solve these problems, it was envisaged to make the turbine ring with a ceramic matrix composite (CMC) material in order to avoid the use of a metallic material.

[0005] CMC materials exhibit good mechanical properties, making them suitable for use in structural components, and advantageously retain these properties at elevated temperatures. The use of CMC materials has advantageously reduced the cooling flow required during operation, thereby increasing the performance of turbomachinery. Furthermore, the use of CMC materials advantageously reduces the mass of turbomachinery and minimizes the thermal expansion effect encountered with metallic parts.

[0006] We also know of documents FR 2 540 939, and FR 2 955 898 which disclose turbine ring assemblies.

[0007] The ring comprises an annular base whose inner face defines the inner face of the turbine ring and an outer face from which two lugs extend radially, the ends of which are held between the two flanges of a metallic ring support structure.

[0008] The integration of a ring in CMC includes radial retention of the part, partly ensured by one or more axial pins. In the known document FR 3 086 327, there are four pins for retention, two upstream and two downstream.

[0009] The use of a CMC material for the ring thus makes it possible to significantly reduce the ventilation required to cool the turbine ring, and therefore to increase efficiency. They also allow for a weight reduction because they are lighter than the metal alloys traditionally used.

[0010] However, since CMC has a different mechanical behavior than a metallic material, its integration and positioning within the turbine had to be redesigned. Indeed, CMC can be damaged by shrink-fitted mountings (usually used for metal rings) and its thermal expansion is lower than that of a metallic material.

[0011] There is a need to improve existing turbine ring assemblies and their mounting, and in particular existing turbine ring assemblies implementing a CMC material in order to reduce the intensity of the mechanical stresses to which the CMC ring is subjected during the operation of the turbine.

[0012] 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 in this high-pressure turbine component. This would result in excessive clearance at the tip of the moving blade (in the opposite runner) and thus a significantly degraded performance through a loss of turbine efficiency.

[0013] The consequence of this sectorization of the turbine ring is the creation of gaps at the inter-sectors (between 0.1mm and 1mm).

[0014] To limit leaks in these areas, sealing strips (also called sheets) are generally integrated between the ring sectors.

[0015] In the prior art, downstream contact along the axial direction is made via an annular radial flange (a 360° component) of a ring support coupled to the turbine housing. For sealing reasons, this annular radial flange must remain intact over its entire circumference due to the interfacing components. It therefore cannot be segmented or semi-segmented.

[0016] Sectorization would lead to leaks opening downstream along the axial direction at the inter-sector junctions. These leaks would depressurize the ring cavity and thus induce potential reintroductions of air from the vein.

[0017] The current trend in aviation is towards an increase in the temperature of the exhaust gases exiting the combustion chamber, leading to a rise in the temperature of the turbine components. The need to cool these parts is therefore increasingly important. The air that enables this cooling is drawn from the compressor outlet. high pressure. This means that air bypasses the combustion chamber without participating in combustion, thus reducing the overall efficiency of the turbine.

[0018] In current designs, inverted pi-shaped CMC rings are used. These inverted pi rings exhibit dimensional variability along the axial direction, in other words, variability in their axial width. This manufacturing variability results in a sizing case known as "short ring / long ring," consisting of a ring at its maximum dimension next to a ring at its minimum dimension. This can lead to stresses, particularly at the inter-sector junctions, due to the clamping of the ring by adjacent metal parts. Indeed, the non-sectorized annular downstream radial flange has a stiffness that does not allow it to conform to dimensional variations. Description of the invention

[0019] The main objective of the present invention is therefore to propose a turbine ring assembly which does not have the aforementioned disadvantages and which reduces the stress on the rings at the inter-sector junctions without degrading the pressurization of the ring cavity.

[0020] This goal 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 along the circumferential direction, the turbine ring assembly further comprising a ring support structure, each ring sector comprising a base from which extend radially outwards an upstream attachment lug and a downstream attachment lug axially spaced from each other, 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.

[0021] In other words, the ring sectors are arranged in the circumferential direction by being placed end to end. This arrangement thus defines intersector junctions, each intersector junction corresponding to the interval between two adjacent ring sectors in the circumferential direction.

[0022] The turbine ring assembly according to the invention is notable 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 into the thickness of the downstream radial flange, from an upstream face of the downstream radial flange, and extending radially from the radial end. external of the downstream radial flange, the thickness of the downstream radial flange being measured along the axial direction, and the adjustment portion of the downstream radial flange being axially distant from the inter-sector junction opposite which it is positioned.

[0023] 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 conform better according to the constraints, in particular thermal, during the 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, by redirecting in particular the flow of force towards a less sensitive area of ​​the turbine ring.

[0024] Reducing the thickness of the downstream radial flange creates a cut-out, i.e., a shortening of the axial thickness. This cut-out allows the adjustment portions of the downstream radial flange to no longer be in direct contact with the turbine ring.

[0025] According to a first aspect of the turbine ring assembly, each adjustment portion of the downstream radial flange may include a housing cut into the thickness of the downstream radial flange.

[0026] Preferably, the housing has an overall rectangular shape, with the corners of the rectangle being rounded or not.

[0027] According to a second aspect of the turbine ring assembly, each adjustment portion of the downstream radial flange may further include a folded sheet metal inserted into said housing to maintain a seal between the downstream radial flange and the turbine ring.

[0028] The folded sheet metal inserted into the housings closes the axial gap between the adjustment portion of the downstream radial flange and the ring, thus forming a seal to prevent radial leakage between the vein sector and the non-vein sector. The folded sheet metal prevents any depressurization of the ring cavity and thus prevents the reintroduction of vein air.

[0029] According to a third aspect of the turbine ring assembly, the housing may comprise an internal radial shoulder, an external radial shoulder, a wall extending between the external radial shoulder and the internal radial shoulder and closing the housing upstream in the axial direction, the housing opening axially downstream, in other words, being axially open downstream, and the folded sheet metal may comprise an external radial portion bearing against the external radial shoulder of the housing, an internal radial portion bearing against the internal radial shoulder of the housing, and a central portion extending between the external radial portion and the internal radial portion and disposed in support against said housing wall, 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.

[0030] More particularly, the folded sheet metal may include an external radially tab bearing against the external radial shoulder of the housing, an internal radially tab at least a portion of which is bearing against the internal radial shoulder of the housing, and a central portion extending between the external radially tab and the internal radially tab and disposed to bear against said wall of the housing, the internal radially tab being axially longer than the internal radial shoulder and comprising a portion extending axially between the internal radial shoulder of the housing and the turbine ring.

[0031] The shape of the housing and that of the folded sheet metal make it possible to guarantee radial and axial retention of the folded sheet metal in its housing.

[0032] According to a fourth aspect of the turbine ring assembly, the housing may include a first circumferential shoulder and a second circumferential shoulder opposite the first circumferential shoulder in the circumferential direction, the folded sheet metal being housed, in the circumferential direction, between the first circumferential shoulder and the second circumferential shoulder, which makes it possible to ensure the retention of the folded sheet metal in the circumferential direction (tangential retention).

[0033] According to a fifth aspect of the turbine ring assembly, each adjustment portion of the downstream radial flange may further include 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 disposed opposite an inter-sector junction.

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

[0035] According to a sixth aspect of the turbine ring assembly, for each adjustment portion, the folded sheet metal 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 include, 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 along the circumferential direction greater than the depth of the groove measured along 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. Brief description of the drawings

[0040] [Fig-1] Fig. 1 is a schematic cross-sectional view along a plane comprising the axial direction and radial direction of a turbine ring assembly according to the invention.

[0041] [Fig.2] The [Fig.2] represents an exploded perspective view of a portion of the ring support of the turbine ring assembly of the [Fig.1].

[0042] [Fig.3] The [Fig.3] represents an assembled perspective view of a portion of the ring support of the turbine ring assembly of the [Fig.1].

[0043] [Fig.4] Fig.4 represents a schematic view of an aircraft.

[0044] [Fig. 5] Fig. 5 schematically represents a cross-sectional view of one half of perimeter of a turbomachine of the aircraft according to the invention. Description of the implementation methods

[0045] Figure 1 schematically represents a turbine ring assembly 2 according to a first embodiment of the invention. Figure 1 is a cross-sectional view along a plane comprising the radial direction DR and the axial direction DA and orthogonal to the circumferential direction Dc.

[0046] The turbine ring assembly 2 shown in Figures 1 and 2 includes, in particular, a turbine ring 4 made of ceramic matrix composite (CMC) material centered on a longitudinal axis XX, and a metal ring support structure 6 attached to a turbine housing (not shown for clarity). The turbine ring 4 surrounds a set of turbine blades (not shown).

[0047] The circumferential direction Dc being a circular direction centered on the longitudinal axis XX.

[0048] Thereafter, throughout the text, the terms "upstream" and "downstream" are used in reference to the direction of flow of the gas flow F through the blades indicated by an arrow.

[0049] Furthermore, the turbine ring 4 is formed from a plurality of angular sectors of ring 10 which are placed end to end in the circumferential direction to form a ring. In [Fig. 1], arrow DA indicates the axial direction of the turbine ring while arrow DR indicates the radial direction of the turbine ring.

[0050] Each angular sector of ring 10 has a substantially shaped section Pi (or ji) inverted with a base 12 having an inner face 12a which defines an angular portion of the inner face of the turbine ring 4 and which is typically provided with an abradable coating layer 13 which also acts as a thermal and environmental barrier.

[0051] Two axially spaced attachment lugs, a downstream attachment lug 14 and an upstream attachment lug 16, extend radially from the external face 12b of the base 12 opposite the internal face 12a. These attachment lugs 14 and 16 extend over the entire width of each ring sector 10 (in the circumferential direction).

[0052] The ring support structure 6 comprises a ferrule 60 extending around the axis XX, and an upstream radial flange 62 and a downstream radial flange 64 extending radially inward from the ferrule 60. The downstream radial flange 64 comprises a mounting portion 640 projecting radially from the ferrule 60, and the upstream radial flange 62 comprises a mounting portion 620 projecting radially from the ferrule 60, as well as an upstream flange 20 attached to the radially projecting mounting portion 620 of the upstream radial flange 62 by means of bolts and nuts (not shown). The bolts pass axially through the first upstream flange 20 and the mounting portion 620 of the upstream radial flange 62.

[0053] The upstream radial flange 62 and the downstream radial flange 64 thus form two attachment flanges for the ring 4, the downstream attachment lug 14 and the upstream attachment lug 16 of the ring sectors 10 being arranged axially between the upstream radial flange 62 and the downstream radial flange 64.

[0054] The turbine ring assembly 2 further comprises upstream pins 40 and downstream pins not shown to simplify reading the figures. The upstream pins 40 pass through the upstream flange 20 of the upstream radial flange 62 and the upstream tab 16 of a ring sector 10. The downstream pins pass at least partially through the downstream radial flange 64, and more particularly through the radially projecting attachment portion 640, as well as the downstream attachment tab 14.

[0055] As illustrated in [Fig. 1], the ring assembly 2 further comprises at each inter-sector junction 100 between two adjacent ring sectors 10 along the circumferential direction Dc, at least one sealing gasket not shown cooperating with grooves 120. The sealing gasket is disposed between the bases 12 of the two adjacent ring sectors 10, and extends mainly along the axial direction DA, i.e. the base of the cylindrical shape extends in a plane orthogonal to the axial direction DA and the generatrices of the cylindrical shape extend parallel to the axial direction DA.

[0056] Opposite each inter-sector junction 100 between two adjacent ring sectors 10 in the circumferential direction, the downstream radial flange 64 further comprises an adjustment portion 70 machined into the thickness of the downstream radial flange 64, the thickness of the downstream radial flange 64 being measured along the axial direction DA.

[0057] The adjustment portion 70 includes 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 plate 72 which is inserted into the housing 71 to maintain a radial seal between the downstream radial flange 64 and the turbine ring 4.

[0058] Figures 2 and 3 respectively show an exploded perspective view and an assembled perspective view of a portion of the ring support of the turbine ring assembly of [Fig.1].

[0059] As illustrated in Figures 1 to 3, the downstream radial flange 64 comprises, along 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 integral with the central ferrule 60 of the ring support 6. The adjustment portion 70 extends along the radial direction DR from the radial inner end 643 of the downstream radial flange 64, and over a portion of the attachment portion 640 of the downstream radial flange 64.

[0060] 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 opposite the radially internal shoulder 711 along the radial direction DR, a first circumferential shoulder 713 and a second circumferential shoulder 714 opposite the first circumferential shoulder 713 along the circumferential direction D c. The housing 71 is machined in a hollow only on part of the axial thickness of the downstream radial flange 64. It thus includes a bottom 710, formed by a wall extending along the radial direction DR between the radially internal shoulder 711 and the radially external shoulder 712, and extending along the circumferential direction Dc between the first circumferential shoulder 713 and the second circumferential shoulder 714.

[0061] The housing 71 is machined in a hollow so that, according to the axial direction DA, the internal radial shoulder 711 is recessed relative to the upstream surface 642 of the downstream radial flange 64. In other words, the internal radial shoulder 713 has axial dimensions enabling it to start axially downstream of the upstream face 642 of the downstream radial flange 64.

[0062] Thus, according to the axial direction DA, the radially internal shoulder 713 is axially distant from the inter-sector junction 100 opposite which it is disposed.

[0063] As illustrated in Figures 1 and 2, the sealing sheet 72 has a C-shaped cross-section along a cutting plane parallel to the axial direction DA and the radial direction DR, in other words in a cutting plane orthogonal to the circumferential direction Dc.

[0064] As illustrated in [Fig.2], the sealing sheet 72 thus comprises a radially external tab 721 located at a radially external end of the sealing sheet 72, a radially internal tab 722 located at a radially external end of the sealing sheet 72, and a central panel 723 extending between the radially external tab 721 and the radially internal tab 723.

[0065] The radially internal tongue 722 comprises a first portion 724 extending parallel to the radially external tongue 721 and with an axial length corresponding to the axial length of the radially internal shoulder 711, and a second portion 725 extending in the axial direction DA between the first portion 724 and the turbine ring 4.

[0066] As illustrated in Figures 1 and 3, the radially external tongue 721 is supported against the radially external shoulder 712 of the housing, the first portion 724 of the radially internal tongue 722 is supported against the radially internal shoulder 711 of the housing, and the central portion 723 is disposed to support against the bottom 710 of the housing 71.

[0067] The sealing plate 72 has dimensions in the circumferential direction Dc fitted to the bottom 710 and thus allowing it to be held in the circumferential direction Dc between the first circumferential shoulder 713 and the second circumferential shoulder 714.

[0068] Each adjustment portion 70 of the downstream radial flange 64 further includes a radial slot 75 open on the inner radial 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 disposed opposite an inter-sector junction 100.

[0069] The open radial slot 75 provided in each housing 71 allows for a semi-sectorization of the downstream radial flange 64 and thus allows it to conform better to the constraints and thus further limit the shear.

[0070] The sealing plate 72 is arranged in the housing to cover the radial slot 75 to maximize sealing.

[0071] Figure 4 shows 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 from 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.

[0072] Figure 5 schematically represents a cross-sectional view of the upper half of a turbomachine 5 of aircraft 1.

[0073] In the example illustrated in [Fig. 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 X-axis (parallel to the main Y-axis), the turbomachine 1 in the direction gas flow, an air inlet 50, a blower 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 flow 57 and a secondary flow 58 separated by an intermediate casing 59. The primary flow 57 extends downstream of the fan 51 and is radially delimited by the intermediate casing 59. The primary flow 57 includes 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 flow 58 extends around the primary flow 57, also downstream of the fan 51. The secondary flow 58 extends radially between the intermediate casing 59 and an external casing 500 extending around the intermediate casing 59.

[0075] At least one of the high pressure 55 or low pressure turbines comprises a turbine 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

Demands

1. Turbine ring assembly (2) comprising a plurality of ring sectors (10) made of ceramic matrix composite material forming a turbine ring (4), defining an axial direction (DA), a radial direction (DR), a circumferential direction (Dc), and a plurality of inter-sector junctions (100) along the circumferential direction (Dc), the turbine ring assembly (2) further comprising a ring support structure (6), each ring sector (10) comprising a base (12) from which extend radially outward an upstream attachment lug (16) and a downstream attachment lug (14) axially spaced from each other, and the ring support structure (6) comprising an upstream radial flange (62) and a downstream radial flange (64) between which the upstream attachment lug (16) and the downstream attachment lug are held (14) of each ring sector (10), characterized in that,opposite each inter-sector junction (100) between two adjacent ring sectors (10) in the circumferential direction (Dc), the downstream radial flange (64) comprises a fitting portion (70) machined into 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 along the axial direction (DA), and the fitting portion (70) of the downstream radial flange (64) being axially distant from the inter-sector junction opposite which it is disposed.

2. Turbine ring assembly (2) according to claim 1, wherein each fitting portion (70) of the downstream radial flange (64) comprises a housing (71) cut into the thickness of the downstream radial flange (64).

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

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

5. Assembly (2) of turbine ring according to any one of claims 2 to 4, in which the housing (71) has 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 (DA), 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 disposed in 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 (4).

6. Turbine ring assembly (2) according to any 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 (Dc), the folded sheet metal (72) being housed, in the circumferential direction (Dc) between the first circumferential shoulder (713) and the second circumferential shoulder (714).

7. Turbine ring assembly (2) according to any one of claims 1 to 6, wherein each fitting 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 extends over a radial portion of the downstream radial flange (64), the radial slot (75) being disposed opposite an inter-sector junction (100).

8. Turbine ring assembly according to claim 7 in combination with any 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. Turbine ring assembly according to any 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 along the circumferential direction (Dc) greater than the groove depth measured along the circumferential direction (Dc)

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

11. Turbomachine comprising a turbine according to claim 10.

Images