EP3596314A1

EP3596314A1 - Turbine ring assembly

Info

Publication number: EP3596314A1
Application number: EP18714566.9A
Authority: EP
Inventors: Nicolas Paul TABLEAU; Sébastien Serge Francis CONGRATEL; Clément Jean Pierre DUFFAU; Fabrice Marcel Noël GARIN; Lucien Henri Jacques QUENNEHEN
Original assignee: Safran Aircraft Engines SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 2017-03-16
Filing date: 2018-03-13
Publication date: 2020-01-22
Anticipated expiration: 2038-03-13
Also published as: US11021988B2; WO2018172653A1; CN110506149A; US20210054757A1; EP3596314B1; FR3064022B1; FR3064022A1; CN110506149B

Abstract

A turbine ring assembly comprising ring sections (10) forming a turbine ring (1) and a ring support structure (3), each ring section (10) having, along a section plane defined by an axial direction (DA) and a radial direction (DR) of the ring (1), a part forming an annular base (12) with, in the radial direction (DR), an inner face (12a) and an outer face (12b), from which a first and a second fastening lug (14, 16) project, said structure (3) comprising a central shroud (31), from which a first and a second radial clamp (32, 36) project, between which the fastening lugs (14, 16) of each ring section (10) are maintained. It comprises a first and a second annular flange (33, 34) detachably fixed to the first radial clamp (32), the second annular flange (34) comprising a support shroud (346) projecting upstream in the axial direction (DA) and having a radial support (348) in contact with the central shroud (31).

Description

TURBINE RING ASSEMBLY

Background of the invention

The invention relates to a turbine ring assembly comprising a plurality of ceramic matrix composite ring sectors and a ring support structure.

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

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 main flow of the engine. In addition, the use of metal for the turbine ring limits the possibilities of increasing the temperature at the turbine, which would however improve the performance of aircraft engines.

In an attempt to solve these problems, it has been envisaged to produce turbine ring sectors made of ceramic matrix composite material (CMC) in order to overcome the implementation of a metallic material.

CMC materials have good mechanical properties making them suitable for constituting 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 to be imposed during operation and thus to increase the performance of the turbomachines. In addition, the use of CMC materials advantageously makes it possible to reduce the weight of the turbomachines and to reduce the effect of hot expansion encountered with the metal parts.

However, the existing solutions proposed can implement an assembly of a CMC ring sector with metal hooking portions of a ring support structure, these hooking portions being subjected to the hot flow. As a result, these metal hooking parts undergo hot expansion, which can lead to mechanical stressing of the ring sectors in CMC and embrittlement thereof.

Documents FR 2 540 939, GB 2 480 766, EP 1 350 927, US 2014/0271145, US 2012/082540 and FR 2 955 898 which disclose turbine ring assemblies are also known.

There is a need to improve existing turbine ring assemblies and their assembly, including existing turbine ring assemblies employing a CMC material to reduce the intensity of the mechanical stresses at which the ring sectors in use. CMC are subjected during the operation of the turbine.

Obiet and summary of the invention

The invention aims to provide a turbine ring assembly for maintaining each ring sector in a deterministic manner, that is to say so as to control its position and prevent it from vibrating. on the one hand, while allowing the ring sector, and by extension the ring, to deform under the effects of temperature rise and pressure variations, and in particular independently of the metal parts interfaced, and on the other hand, while improving the seal between the off-vein sector and the vein sector and simplifying the manipulations and reducing their number for mounting the ring assembly.

An object of the invention provides a turbine ring assembly comprising a plurality of ring sectors forming a turbine ring and a ring support structure, each ring sector having, according to a sectional plane defined by an axial direction and a radial direction of the turbine ring, an annular base portion with, in the radial direction of the turbine ring, an inner face defining the inner face of the turbine ring and an outer face to from which protrude a first and a second attachment lugs, the ring support structure having a central ferrule from which project a first and a second radial flange between which are maintained the first and second latches of each ring sector.

According to a general characteristic of the object, the turbine ring assembly comprises a first annular flange and a second annular flange disposed upstream of the first annular flange relative to the direction of an air flow for passing through the turbine ring assembly, the first and second annular flanges respectively having a first free end and a second end opposite to the first end, the first end of the first flange being in abutment against the first attachment lug, the first end of the second annular flange being distant from the first end of the first annular flange in the axial direction, and the second end of the second flange ring comprising an upstream bearing shell extending projecting upstream in the axial direction, the upstream bearing shell having a radial bearing in contact with the central shell of the ring support structure.

In a particular embodiment, the ring sectors may be made of ceramic matrix composite material (CMC).

The second annular flange separated from the first annular flange at its free end can provide the turbine ring assembly an upstream flange dedicated to the recovery of the force of the high pressure distributor (DHP). The second annular flange upstream of the turbine ring and free from any contact with the ring is configured to pass the maximum axial force induced by the DHP directly into the ring support structure without passing through the ring. ring which, when it is in CMC, has a low mechanical permissible.

Indeed, leaving a space between the first ends of the first and second annular flanges can deflect the force received by the second flange, upstream of the first annular flange which is in contact with the turbine ring, and to do passing directly to the central ferrule of the ring support structure via the second end of the second annular flange, without impacting the first annular flange and therefore without impacting the turbine ring. The first end of the first flange not under stress, the turbine ring is thus preserved from this axial force.

The transit of the DHP force via the second annular flange can induce its tilting. This tilting can cause an uncontrolled contact between the lower parts, that is to say the first ends, of the second annular flange and the first annular flange in contact with the turbine ring, which would have the effect of directly transmitting the DHP effort to the ring.

The upstream support ferrule provides higher resistance to DHP-induced tilting. The bearing shell takes the significant tangential stresses caused by the DHP effort and thus limits the tilting of the second annular flange.

In addition, the removable nature of the annular flanges makes it possible to have axial access to the cavity of the turbine ring. This makes it possible to assemble the ring sectors together outside the ring support structure and then to axially slide the assembly thus assembled into the cavity of the ring support structure until it comes into contact. bearing against the second radial flange, before fixing the annular flanges on the central ferrule of the ring support structure.

During the operation of fixing the turbine ring on the support structure of the ring, it is possible to use a tool comprising a cylinder or a ring on which the ring sectors are supported or sucked during their crown assembly.

The fact of having two annular flanges each in one piece, that is to say describing the entirety of a ring over 360 °, allows, compared to sectored annular flanges, to limit the flow of the flow of air between the off-vein sector and the vein sector, since all inter-sector leaks are eliminated, and thus to control the tightness.

The solution defined above for the ring assembly thus makes it possible to maintain each ring sector in a deterministic manner, that is to say to control its position and to prevent it from starting to vibrate. by improving the seal between the off-vein sector and the vein sector, by simplifying the manipulations and reducing their number for the assembly of the ring assembly, and by allowing the ring to deform under the effect of temperature and pressure especially independently metal parts interface.

According to a first aspect of the turbine ring assembly, the second annular flange may include a contact abutment extending in the axial direction of the turbine ring and separating the second end of the second annular flange from the second end. of the first annular flange. The contact abutment provided between the second ends of the first and second annular flange further reduces the contact between the lower portion of the second annular flange, disposed upstream of the first flange, and that of the first annular flange, further at this changeover. The direct transit of DHP effort to the ring is avoided.

According to a second aspect of the turbine ring assembly, the assembly may further comprise an omega seal mounted between the first end of the second annular flange and the first end of the first flange, the second annular flange being fixed to the structure. ring support on a portion upstream of the radial support.

The omega seal makes it possible to seal between the vein cavity and the off-vein cavity upstream of the ring.

According to a third aspect of the turbine ring assembly, the ring sector may have a Greek letter section pi (π) inverted according to the section plane defined by the axial direction and the radial direction, and the whole may comprise, for each ring sector, at least three pins for radially holding the ring sector in position, the first and second attachment tabs of each ring sector each comprising a first end integral with the outer face of the ring sector; the annular base, a second free end, at least three receiving lugs of the at least three pegs, at least two lugs projecting from the second end of one of the first or second latching lugs in the radial direction of the turbine ring and at least one lug projecting from the second end of the other hooking lug in the radial direction of the turbine ring, each receiving lug comprising an orifice for receiving one of the pieces.

According to a fourth aspect of the turbine ring assembly, the ring sector may have a section having an elongated K-shape according to the section plane defined by the axial direction and the radial direction, the first and a second legs with a shape of S.

According to a fifth aspect of the turbine ring assembly, the ring sector may have, at at least one radial range of the ring sector, a section at 0 according to the section plane defined by the axial direction and the radial direction, the first and the second latching lugs each having a first end secured to the outer face and a second free end, and each ring sector comprising a third and a fourth latching tabs; each extending, in the axial direction of the turbine ring, between a second end of the first latching lug and a second end of the second latching lug, each ring sector being fixed to the support structure of ring by a fixing screw comprising a screw head bearing against the ring support structure and a thread cooperating with a tapping made in a fixing plate, the fixing plate cooperating with the third and fourth attachment tabs .

Another object of the invention provides a turbomachine comprising a turbine ring assembly as defined above.

Brief description of the drawings.

The invention will be better understood on reading the following, by way of indication but without limitation, with reference to the accompanying drawings in which:

- Figure 1 is a schematic perspective view of a first embodiment of a turbine ring assembly according to the invention;

FIG. 2 is a diagrammatic exploded perspective view of the turbine ring assembly of FIG. 1;

FIG. 3 is a schematic sectional view of the turbine ring assembly of FIG. 1;

FIG. 4 is a diagrammatic sectional view of a second embodiment of the turbine ring assembly;

FIG. 5 is a diagrammatic sectional view of a third embodiment of the turbine ring assembly;

- Figure 6 is a schematic sectional view of a fourth embodiment of the turbine ring assembly.

Detailed description of embodiments

FIG. 1 shows a high pressure turbine ring assembly comprising a turbine ring 1 made of composite material with ceramic matrix (CMC) and a metal ring support structure 3. The turbine ring 1 surrounds a set of rotating blades (not shown). The turbine ring 1 is formed of a plurality of ring sectors 10, FIG. 1 being a view in radial section. The arrow D _A indicates the axial direction of the turbine ring 1 while the arrow D _R indicates the radial direction of the turbine ring 1. For reasons of simplification of presentation, Figure 1 is a partial view of the turbine ring 1. turbine ring 1 which is actually a complete ring.

As illustrated in FIGS. 2 and 3, which respectively have an exploded schematic perspective view and a sectional view of the turbine ring assembly of FIG. 1, the sectional view being in a sectional plane comprising the radial direction DR and the axial direction D _{A /} each ring sector 10 has, in a plane defined by the axial directions D _A and radial DR, a substantially shaped section of the Greek letter inverted π. The section comprises in fact an annular base 12 and upstream and downstream radial attachment tabs, respectively 14 and 16. The terms "upstream" and "downstream" are used here with reference to the flow direction of the gas flow in the turbine represented by the arrow F in Figure 1. The legs of the ring sector 10 could have another shape, the section of the ring sector having a shape other than π, such as a K-shape or O.

The annular base 12 comprises, in the radial direction D _R of the ring 1, an inner face 12a and an outer face 12b opposite to each other. The inner face 12a of the annular base 12 is coated with a layer 13 of abradable material forming a thermal and environmental barrier and defines a stream of flow of gas in the turbine. The terms "internal" and "external" are used herein with reference to the radial direction D _R in the turbine.

The upstream and downstream radial hooking tabs 14 and 16 project in the direction D _R from the outer face 12b of the annular base 12 away from the upstream and downstream ends 121 and 122 of the annular base. 12. The upstream and downstream radial fastening tabs 14 and 16 extend over the entire width of the ring sector 10, that is to say over the entire arc described by the ring sector 10. , or over the entire circumferential length of the ring sector 10. As illustrated in FIGS. 1 to 3, the ring support structure 3 which is integral with a turbine casing comprises a central ring 31, extending in the axial direction D _A , and having an axis of revolution. coincide with the axis of revolution of the turbine ring 1 when they are fixed together, and a first annular radial flange 32 and a second annular radial flange 36, the first annular radial flange 32 being positioned upstream of the second radial annular flange 36 which is therefore downstream of the first annular radial flange 32.

The second annular radial flange 36 extends in the circumferential direction of the ring 1 and, in the radial direction D _R , from the central shell 31 towards the center of the ring 1. It comprises a first end 361 free and a second end 362 integral with the central ferrule 31. The second annular radial flange 36 comprises a first portion 363, a second portion 364, and a third portion 365 between the first portion 363 and the second portion 364. The first portion 363 is s extends between the first end 361 and the third portion 365, and the second portion 364 extends between the third portion 365 and the second end 362. The first portion 363 of the second annular radial flange 36 is in contact with the radial flange d The second portion 364 is thinned with respect to the first portion 363 and the third portion 365 so as to give some flexibility to the second flange. annular ring 36 and thus not too much constrain the turbine ring 1 CMC.

The first annular radial flange 32 extends in the circumferential direction of the ring 1 and, in the radial direction D _R , from the central shell 31 towards the center of the ring 1. It comprises a first free end 321 and a second end 322 secured to the central ferrule 31.

As illustrated in Figures 1 to 3, the turbine ring assembly 1 includes a first annular flange 33 and a second annular flange 34, the two annular flanges 33 and 34 being removably attached to the first radial flange. The first and second annular flanges 33 and 34 are arranged upstream of the turbine ring 1 with respect to the flow direction F of the gas flow in the turbine. The first annular flange 33 is disposed downstream of the second annular flange 34. The first annular flange 33 has a first end 331 free and a second end 332 removably attached to the ring support structure 3, and more particularly to the first annular radial flange 32.

In addition, the first annular flange 33 has a first portion 333 extending from the first end 331 and a second portion 334 extending between the first portion 333 and the second end 332. When the ring assembly 1 is mounted the first portion 333 of the first annular flange 33 is in abutment against the upstream radial clawing tab 14 of each of the ring sectors 10 making up the turbine ring 1, and the second portion 334 of the first annular flange 34 is rests against at least a portion of the first annular radial flange 32.

The radial retention of the ring 1 is ensured by the first annular flange 33 which is pressed onto the first annular radial flange 32 of the ring support structure 3 and on the upstream radial snap tab 14. The first annular flange 33 seals between the vein cavity and the off-vein cavity of the ring.

The second annular flange 34 has a first free end 341 and a second end 342 removably attached to the ring support structure 3.

The second annular flange 34 is dedicated to the recovery of the force of the high pressure distributor (DHP) on the ring assembly 1, on the one hand, by deforming, and, on the other hand, by passing through this force towards the casing line which is more mechanically robust, that is to say toward the line of the ring support structure 3 as illustrated by the effort arrow E shown in FIG.

In the first embodiment illustrated in Figures 1 to 3, the first annular flange 33 and the second annular flange 34 are in contact at their second end respectively 332 and 342. The second end 342 of the second annular flange 34 comprises a contact abutment 340 projecting in the axial direction D _A between the second annular flange 34 and the first annular flange 33. The contact abutment 340 makes it possible to maintain a distance between the first end 331 of the first annular flange 33 and the first end 341 of the second annular flange 34 during the tilting of the second annular flange 34 induced by the effort DHP. The second end 342 of the second annular flange 34 is fixed to the first annular radial flange 32 via the abutment and the first annular flange 33.

In addition, the second end 342 of the second annular flange

34 comprises a support ring 346 projecting upstream in the axial direction D _A.

In other words, the second annular flange 34 has an upstream face 34a receiving the gas flow F and a downstream face 34b facing the first annular flange 33, and the second end 342 of the second annular flange 34 comprises a contact abutment 340 extending in the axial direction D _A from the downstream face 34b downstream, that is to say towards the first annular flange 33, and a supporting ferrule 346 extending in the axial direction D _A from the upstream face 34a of the second annular flange 34.

The support ring 346 has an inner face 346a and an outer face 346b, a first free end 3461, and a second end 3462 integral with the upstream face 34a of the second annular flange 34, the first end 3461 being upstream of the second end 3462 when the turbine ring assembly is mounted. The support ring 346 comprises, on its first end 3461, a radial support 348 projecting from the external face 346b of the support ring 346. The radial support 348 is in contact with the central shell 31 of the support structure. ring support 3.

The support ferrule 346 provides a higher resistance to DHP stress-induced tilting. The support ring 346 takes up the important tangential stresses caused by the DHP force and thus limits the tilting of the second annular flange 34.

The second annular flange 34 provides the connection between the downstream part of the DHP, the ring support structure 3, or casing, by radial surface contact, and the first annular flange 33 by axial surface contact.

The first and second annular flanges 33 and 34 are fretted to the ring support structure 3.

The second annular flange 34 is fretted on the central ferrule

31 of the ring support structure 3, the hooping being realized, of a part, between the central ferrule 31 and a portion 345 projecting from the contact abutment 340, in the radial direction D _R away from the axis of revolution of the ring, that is to say going towards the central ferrule 31, and, secondly, between the central ferrule 31 and the radial support 348.

The first annular flange 33 is shrunk onto the first annular radial flange 32 of the ring support structure 3. More precisely, the hooping is produced between a radial surface 335 approximately in the middle, in the radial direction D _R , of the first annular flange

33 and a radial surface 325 at half height of the first annular radial flange 32, the two radial surfaces 335 and 325 being opposite and in contact with each other in the radial direction D _R. The radial surface 335 of the first annular flange 33 extends over the entire circumference of the first annular flange 33, and on the face of the first annular flange 33 facing the first annular flange 32 and the first radial fixing lug 14. More specifically, the radial surface 335 of the first annular flange 33 may be formed anywhere on the portion of the first annular flange 33 intended to be in contact with the first annular radial flange 32, the radial surface 325 of the first annular radial flange 32 being formed at a corresponding height on the face of the first annular radial flange 32 facing the first annular flange 33.

The ring support structure 3 further comprises screws 38 which make it possible to press the ring in the low radial position, that is to say towards the vein, in a deterministic manner. There is indeed a clearance between the axial pins and the bores on the ring to compensate for the differential expansion between the metal and the CMC elements that operates hot.

In Figure 4 is shown a schematic sectional view of a second embodiment of the turbine ring assembly.

The second embodiment of the invention illustrated in FIG. 4 differs from the first embodiment illustrated in FIGS. 1 to 3 mainly in that the second annular flange 34 is not in direct contact with the first annular flange 33.

The first annular flange 33 and the second annular flange

34 are connected by an omega seal 40 for sealing between the vein cavity and the off-vein cavity upstream of the ring 1. In the second embodiment, the second annular flange 34 does not comprise a contact abutment 340 unlike the first embodiment illustrated in FIGS. 1 to 3.

The support ring 346 of the second annular flange 34 also comprises a radial support 348 projecting from the external face 346b of the support ring 346. In FIG. 4, the radial support 348 is disposed on an upstream portion of the bearing ferrule 346 without being directly on the first end 3461, the radial support 348 may be disposed along the entire length of the outer face 34b in the axial direction D _A , the most upstream position allowing a greater resistance.

In the second embodiment illustrated in FIG. 4, the first annular flange 33 is fixed to the first annular flange 32 of the ring support structure 3 by means of screws 60 and fixing nuts 61. screw 60 passing through the second portion 334 of the first annular flange 33 and the upstream annular radial flange 32.

The radial support 348, projecting in the radial direction DR in a direction away from the axis of revolution of the ring 1, comprises a first face 348a extending in the radial direction D _R and receiving the flow F and a second face 348b extending in the radial direction DR and opposite to the first face 348a, the second face 348b forming an axial shoulder bearing on a radial rib 314 of the central shell 31. The radial rib 314 extends protruding in the radial direction D _R from the central shell 31 in a direction towards the axis of revolution of the ring 1. The radial rib 314 comprises a first face 314a extending in the radial direction D _R opposite the flow F and in contact with the second face 348b of the radial support 348, and a second face 314b extending in the radial direction DR and opposite the first face 314a.

The axial shoulder formed by the second face 348b of the radial support 348 of the second annular flange 34 is pressed against the radial rib 314 of the central shell 31 of the ring support structure 3. A DHP casing, not shown on FIG. FIG. 4, located upstream of the second annular flange 34 provides a locking in the axial direction D _A of the second annular flange 34 on the other side of the radial rib 314. The second annular flange 34 is thus held axially in position between the radial rib 314 and the DBH casing upstream of the second annular flange 34.

At the radial level, there is a functional clearance between the radial support 348 of the second annular flange 34 and the central ferrule 31 of the ring support structure 3. This clearance has no influence on the behavior of the assembly , especially in dynamics since the second annular flange 34 remains static during operation of the engine. In addition, its radial positioning has no influence on the radial positioning of the other parts.

In Figure 5 is shown a schematic sectional view of a third embodiment of the turbine ring assembly.

The third embodiment illustrated in FIG. 5 differs from the first embodiment illustrated in FIGS. 1 to 3 in that the ring sector 10 has, in the plane defined by the axial directions D _A and radial direction DR, a section in FIG. K shape instead of an inverted section.

Figure 6 is a sectional view of a fourth embodiment of the turbine ring assembly.

The fourth embodiment illustrated in FIG. 6 differs from the first embodiment illustrated in FIGS. 1 to 3 in that the ring sector 10 has in the plane defined by the axial directions D _A and radial D _R , on a part of the ring sector 10, an O-shaped section instead of an inverted π-shaped section, the ring section 10 being fixed to the ring support structure 3 by means of a screw 19 and a fastener 20, the screws 38 being removed.

In each of the embodiments of the invention illustrated in Figures 1 to 6, in the axial direction D _A , the second annular radial flange 36 of the ring support structure 3 is separated from the first annular flange 33 of a distance corresponding to the spacing of the upstream and downstream radial hooking tabs 14 and 16 so as to maintain the latter between the first annular flange 33 and the second annular radial flange 36.

In the first and second embodiments illustrated in FIGS. 1 to 4, in order to keep the ring sectors 10, and thus the turbine ring 1, in position with the ring support structure 3, the ring assembly comprises two first pins 119 cooperating with the upstream latching lug 14 and the first annular flange 33, and two second pins 120 cooperating with the downstream latching lug 16 and the second annular radial flange 36.

In these two embodiments illustrated respectively in FIGS. 1 to 3 and in FIG. 4, for each corresponding ring sector 10, the second portion 334 of the first annular flange 33 comprises two orifices 3340 for receiving the first two pins 119, and the third portion 365 of the annular radial flange 36 comprises two orifices 3650 configured to receive the two second pins 120.

For each ring sector 10, each of the upstream and downstream radial attachment tabs 14 and 16 comprises a first end, 141 and 161, integral with the outer face 12b of the annular base 12 and a second end, 142 and 162, free. The second end 142 of the upstream radial fastening tab 14 comprises two first lugs 17 each having an orifice 170 configured to receive a first pin 119. Similarly, the second end 162 of the downstream radial fastening tab 16 comprises two second ears 18 each having an orifice 180 configured to receive a second pin 120. The first and second ears 17 and 18 project in the radial direction D _R of the turbine ring 1 respectively of the second end 142 of the radial attachment tab 14 upstream and the second end 162 of the downstream radial attachment tab 16.

The orifices 170 and 180 may be circular or oblong. Preferably, all the orifices 170 and 180 comprise a portion of circular orifices and a portion of oblong orifices. The circular orifices make it possible to tangentially index the rings and to prevent them from moving tangentially (especially in case of touch by the blade). The oblong holes accommodate differential expansions between the CMC and the metal. CMC has a coefficient of expansion much lower than that of metal. Hot, the lengths in the tangential direction of the ring sector and the housing portion vis-à-vis vis-à-vis will be different. If there were only circular orifices, the metal casing would impose its displacements to the CMC ring, which would be a source of very high mechanical stresses in the ring sector. Have oblong holes in the set ring allows the pin to slide in this hole and avoid the phenomenon of over-stress mentioned above. Therefore, two drilling patterns can be imagined: a first drilling pattern, for a case with three ears, would comprise a radial circular orifice on a radial attachment flange and two tangential oblong holes on the other radial attachment flange , and a second drilling pattern, for a case with at least four lugs, would comprise a circular orifice and an oblong orifice by radial attachment flange vis-à-vis each time. Other related cases may be considered as well.

For each ring sector 10, the first two lugs 17 are positioned at two different angular positions relative to the axis of revolution of the turbine ring 1. Likewise, for each ring sector 10, the two seconds ears 18 are positioned at two different angular positions with respect to the axis of revolution of the turbine ring 1.

As illustrated in FIG. 5, in the third embodiment, each ring sector 10 has, in a plane defined by the axial directions D _A and radial D _R , a substantially K-shaped section comprising an annular base 12 with , in the radial direction DR of the ring, an inner face 12a coated with a layer 13 of abradable material forming a thermal and environmental barrier and which defines the flow of gaseous flow stream in the turbine. S-shaped upstream and downstream hooking tabs 140, 160 that are substantially S-shaped extend, in the radial direction D _R , from the outer face 12b of the annular base 12 over the entire width thereof and above the upstream and downstream circumferential end portions 121 and 122 of the annular base 12.

The radial latching tabs 140 and 160 have a first end, respectively referenced 1410 and 1610, integral with the annular base 12 and a second free end, referenced respectively 1420 and 1620. The free ends 1420 and 1620 of the radial fastening tabs upstream and downstream 140 and 160 extend either parallel to the plane in which the annular base 12 extends, that is to say in a circular plane, or rectilinearly while the latching lugs 140 and 160 extend annularly. In this second configuration where the ends are rectilinear and annular claws, in the event of a possible rocking of the ring during operation, the surface supports then become linear bearings which provides a greater seal than in the case of punctual support. The second end 1620 of the downstream radial gripping tab 160 is held between a portion 3610 of the second annular radial flange 36 projecting in the axial direction D _A from the first end 361 of the second annular radial flange 36 in the opposite direction to the flow direction F and the free end of the screw 38 associated, that is to say the screw opposite to the screw head. The second end 1410 of the upstream radial fastening tab 140 is held between a portion 3310 of the first annular flange 33 projecting in the axial direction D _A from the first end 331 of the first annular flange 33 in the flow direction. F and the free end of the associated screw 38.

In the fourth embodiment illustrated in FIG. 6, the ring sector 10 comprises an axial hook tab 17 'extending between the upstream and downstream radial attachment tabs 14 and 16. The axial hooking tab 17 'extends more precisely, in the axial direction D _A , between the second end 142 of the upstream radial fastening tab 14 and the second end 162 of the downstream radial fastening tab 16.

The axial hooking tab 17 'comprises an upstream end 171' and a downstream end 172 'separated by a central portion 170'. The upstream and downstream ends 171 'and 172' of the axial latching lug 17 'protrude, in the radial direction D _R , from the second end 142, 162 of the radial latching lug 14, 16 to which they are coupled, so as to have a central portion 170 'of axial hooking lug 17' raised relative to the second ends 142 and 162 of the upstream and downstream radial hooking tabs 14 and 16.

For each ring sector 10, the turbine ring assembly comprises a screw 19 and a fastener 20. The fastener 20 is fixed on the axial fastening tab 17 '.

The fastener 20 further comprises an orifice 21 having a tapping cooperating with a thread of the screw 19 to fasten the fastener 20 to the screw 19. The screw 19 comprises a screw head 190 whose diameter is greater than the diameter of an orifice 39 made in the central shell 31 of the support structure of the ring 3 through which the screw 19 is inserted before being screwed to the fastener 20.

The radial joining of the ring sector 10 with the ring support structure 3 is carried out using the screw 19, the head 190 of which bears against the central ring 31 of the support structure of the ring. 3, and the fastener 20 screwed to the screw 19 and fixed to the axial attachment tab 17 'of the ring sector 10, the screw head 190 and the fastener 20 exerting forces in opposite directions for hold together the ring 1 and the ring support structure 3.

In a variant, the radial retention of the ring downwards can be ensured by means of four radial pins plated on the axial hooking lug 17 ', and the radial retention upwards of the ring can be ensured. by a pickaxe head, integral with the screw 19, placed under the ring in the cavity between the axial hooking tab 17 'and the outer face 12b of the annular base.

In each of the embodiments of the invention illustrated in FIGS. 1 to 6, each ring sector 10 further comprises rectilinear support surfaces 110 mounted on the faces of the upstream and downstream radial attachment tabs 14 and 16. in contact respectively with the first annular flange 33 and the second annular radial flange 36, that is to say on the upstream face 14a of the upstream radial fastening tab 14 and on the downstream face 16b of the radial flange of FIG. In a variant, the rectilinear supports could be mounted on the first annular flange 33 and on the second downstream annular radial flange 36.

The rectilinear supports 110 allow to have controlled sealing zones. Indeed, the bearing surfaces 110 between the upstream radial fastening flap 14 and the first annular flange 33, on the one hand, and between the downstream radial fastening tab 16 and the second annular radial flange 36 are included in FIG. the same rectilinear plane.

More precisely, having bearings on radial planes makes it possible to overcome the effects of unclamping in the turbine ring 1.

A method for producing a turbine ring assembly corresponding to that shown in FIG. 1, that is to say according to the first embodiment illustrated in FIGS. 1 to 3, is now described. Each ring sector 10 described above is made of ceramic matrix composite material (CMC) by forming a fibrous preform having a shape close to that of the ring sector and densification of the ring sector by a ceramic matrix .

For the production of the fiber preform, it is possible to use ceramic fiber yarns, for example SiC fiber yarns, such as those marketed by the Japanese company Nippon Carbon under the name "Hi-NicalonS", or carbon fiber yarns. .

The fibrous preform is advantageously made by three-dimensional weaving, or multilayer weaving with the provision of debonding zones enabling the parts of preforms corresponding to the hooking tabs 14 and 16 of the sectors 10 to be spaced apart.

The weave can be interlock type, as illustrated. Other weaves of three-dimensional weave or multilayer can be used as for example multi-web or multi-satin weaves. Reference can be made to WO 2006/136755.

After weaving, the blank can be shaped to obtain a ring sector preform which is consolidated and densified by a ceramic matrix, the densification can be achieved in particular by chemical vapor infiltration (CVI) which is well known in itself. Alternatively, the textile preform can be a little hardened by CVI so that it is rigid enough to be manipulated, before raising liquid silicon by capillarity in the textile for densification ("Melt Infiltration").

A detailed example of manufacturing ring sectors in

CMC is described in particular in document US 2012/0027572.

The ring support structure 3 is made of a metallic material such as a Waspaloy® alloy or inconel 718® or C263®.

The realization of the turbine ring assembly is continued by mounting the ring sectors 10 on the ring support structure 3.

For this, the ring sectors 10 are assembled together on an annular tool of the "spider" type comprising, for example, suckers configured to each maintain a ring sector 10. Then the two second pins 120 are inserted into the two orifices 3650 provided in the third portion 365 of the second annular radial flange 36 of the support structure: ring 3.

The ring 1 is then mounted on the ring support structure 3 by inserting each second pin 120 in each of the orifices 180 of the second lugs 18 of the downstream radial fastening flanges 16 of each ring sector 10 constituting the ring. 1.

Then all the first pins 119 are placed in its orifices 170 provided in the first lugs 17 of the radiafe hooking tab 14 of the ring 1.

Then the first annular flange 33 and the second annular flange 34 are attached to the ring support structure 3 and to the ring 1. The first and second annular flasks 33 and 34 are fixed by frettage to the support structure of the ring flange. 3. The DHP force exerted in the direction of the flow F reinforces this fixation during operation of the engine.

It should be noted that in the case of a method for producing a turbine ring assembly corresponding to that shown in FIG. 4, the assembly is carried out by fixing the first flange 33 to the ring support structure. 3 by bolted connection, - then putting the omega seal 40 in place in the groove provided for this purpose in the first flask 33 before coming to assemble the second flange 34 to the ring support structure 3.

To maintain the ring 1 in radlafernent position, the first annular flange 33 is fixed to the ring by inserting each first pin 119 in each of the orifices 170 of the first ears 17 of the upstream radial fastening tabs 14 of each ring sector 10 component ring 1.

The ring 1 is thus maintained in position axially with the aid of the first annular flange 33 and the second annular radial flange 36 bearing respectively upstream and downstream on the straight bearing surfaces 110 of the radial claws respectively upstream 14 and downstream 16, during the installation of the first annular flange 33 _/ axial prestressing may be applied to the first annular flange 33 and the upstream radial flange 14 to overcome the differential expansion effect between the material CMC of the ring 1 and the metal of the ring support structure 3, the first ring flange 33 is maintained in axial stress by mechanical elements placed upstream as shown in dashed lines in FIG.

The ring 1 is held in position radially with the aid of the first and second pins 119 and 120 cooperating with the first and second lugs 17 and 18 and the orifices 3340 and 3650 of the first annular flange 33 and the annular radial flange 36.

The invention thus provides a turbine ring assembly for maintaining each ring sector in a deterministic manner while allowing, on the one hand, the ring sector, and by extension to the ring, to deform under the effects of temperature rises and pressure variations, and in particular independently of the metal parts interface, and, on the other hand, while improving the seal between the non-vein sector and the vein sector and simplifying manipulations and reducing their number for mounting the ring assembly.

In addition, the invention provides a turbine ring assembly comprising an upstream annular flange dedicated to the recovery of the DHP force and thus to induce low levels of forces in the CMC ring, a contact abutment between the annular flange dedicated to the recovery of DHP effort and the annular flange used to maintain the ring, the stop to ensure the non-contact of the lower parts of the two flanges when tilting the upstream flange. The turbine ring assembly according to the invention also makes it possible to control the rigidity at the upstream and downstream axial contacts between the CMC ring and the metal casing. As a result, the seal is ensured in all circumstances without inducing excessive axial forces on the ring.

Claims

A turbine ring assembly comprising a plurality of ring sectors (10) forming a turbine ring (1) and a ring support structure (3), each ring sector (10) having, according to a cutting plane defined by an axial direction (DA) and a radial direction (D _R ) of the turbine ring (1), an annular base portion (12) with, in the radial direction (D _R ) of the turbine ring (1), an inner face (12a) defining the inner face of the turbine ring (1) and an outer face (12b) from which project a first and a second lugs hooking (14, 16), the ring support structure (3) having a central shell (31) from which project first and second radial flanges (32, 36) between which are held the first and second latching lugs (14, 16) of each ring sector (10),

characterized in that it comprises a first annular flange (33) and a second annular flange (34) disposed upstream of the first annular flange (33) with respect to the direction of a flow of air (F) intended to pass through the annular flange (33) turbine ring assembly (1), the first and second annular flanges (33, 34) respectively having a first free end (331, 341) and a second end (332, 342) opposite the first end, the first end (331) of the first flange (33) bearing against the first latching lug (14), the first end (341) of the second annular flange (34) being distant from the first end (331) of the first annular flange ( 33) in the axial direction (D _A ), and the second end (342) of the second annular flange (34) comprising an upstream bearing ferrule (346) projecting upstream in the axial direction (D). _A ), the upstream bearing shell (346) having a radial bearing (348) in contact with the c the central shell (31) of the ring support structure (3).

An assembly according to claim 1, wherein the second annular flange (34) comprises a contact abutment (340) extending in the axial direction (D _A ) of the turbine ring (1) and separating the second end (342) second annular flange (34) of the second end (332) of the first annular flange (33).

3. The assembly of claim 1, further comprising an omega seal (40) mounted between the first end (341) of the second annular flange (34) and the first end (331) of the first flange (33), the second annular flange. (34) being attached to the ring support structure (3) on a portion upstream of the radial support (348).

4. An assembly according to one of claims 1 to 3, wherein the ring sector (10) has a Greek letter section pi (π) inverted along the plane of section defined by the axial direction (D _A ) and the radial direction (DR), and the assembly comprises, for each ring sector (10), at least three pins (119, 120) for radially holding the ring sector (10) in position, the first and second legs latching (14, 16) each ring sector (10) each comprising a first end (141, 161) integral with the outer face (12b) of the annular base (12), a second end (142, 162 ) free, at least three lugs (17, 18) for receiving said at least three pins (119, 120), at least two lugs (17) projecting from the second end (142, 162) of one of the first or second latching lugs (14, 16) in the radial direction (DR) of the turbine ring (1) and at least one lug (18) projecting from the second end (162, 142) of the other hooking lug (16, 14) in the radial direction (D _R ) of the turbine ring (1), each receiving lug (17, 18) having an orifice ( 170, 180) for receiving one of the pins (119, 120).

5. An assembly according to one of claims 1 to 3, wherein the ring sector (10) has a section having an elongate K shape according to the section plane defined by the axial direction (D _A ) and the radial direction (DR), the first and second hook tabs (14, 16) having an S-shape.

6. An assembly according to one of claims 1 to 3, wherein the ring sector (10) has, on at least one radial range of the ring sector, a section in O along the section plane defined by the direction. axial (D _A ) and the radial direction (DR), the first and second attachment lugs (14, 16) each having a first end (141, 161) secured to the outer face (12b) and a second free end (142, 162), and each ring sector (10) comprising a third and a fourth latching lug (17 each extending, in the axial direction (D _A ) of the turbine ring (1), between a second end (142) of the first latching lug (14) and a second end (162) of the second latching lug ( 16), each ring sector (10) being attached to the ring support structure (3) by a fixing screw (19) having a screw head (190) bearing against the ring support structure (3) and a thread cooperating with a thread formed in a fastening plate (20), the fastening plate (20) cooperating with the third and fourth fastening tabs (17 ').

7. A turbomachine comprising a turbine ring assembly (1) according to any one of claims 1 to 6.