TURBINE RING ARRANGEMENT FOR DIFFERENTIAL THERMAL EXPANSION

Description

Background of the invention

[0001] A turbine ring assembly includes a plurality of ring sectors made of ceramic matrix composite material and a ring support structure.

[0002] In the case of all-metal turbine ring assemblies, it is necessary to cool all the elements of the assembly, particularly the turbine ring, which is subject to the hottest flows. This cooling has a significant impact on engine performance since the cooling flow used is taken from the main engine flow. In addition, the use of metal for the turbine ring limits the possibilities of increasing the temperature at the turbine level, which would otherwise improve the performance of aeronautical engines.

[0003] In an attempt to resolve these problems, consideration was given to making turbine ring sectors from ceramic matrix composite (CMC) material in order to avoid the need to use a metallic material.

[0004] CMC materials have good mechanical properties making them suitable for use in 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.

[0005] However, the existing solutions proposed may implement an assembly of a CMC ring sector with metal attachment parts of a ring support structure, these attachment parts being subjected to the hot flow. Consequently, these metal attachment parts undergo hot expansion, which may lead to mechanical stressing of the CMC ring sectors and their embrittlement.

[0006] We also know the documents GB 2 480 766, EP 1 350 927 and US 2014 / 0271145 which disclose turbine ring assemblies.

[0007] There is a need to improve existing turbine ring assemblies implementing CMC material in order to reduce the intensity of mechanical stresses to which the CMC ring sectors are subjected during operation. Subject matter and summary of the invention

[0008] To this end, the invention proposes, according to a first aspect, a turbine ring assembly comprising a plurality of ring sectors made of ceramic matrix composite material forming a turbine ring and a ring support structure, each ring sector having a portion forming an annular base with an inner face defining the inner face of the turbine ring and an outer face from which extends a portion for attaching the ring sector to the ring support structure, the ring support structure comprising two annular flanges between which the attachment portion of each ring sector is held, the annular flanges of the ring support structure each having at least one inclined portion bearing on the attachment portions of the ring sectors, said inclined portion forming, when observed in meridian section, a non-zero angle relative to the radial direction and to the axial direction,characterized in that the attachment parts of the ring sectors are held to the ring support structure at axial portions each extending parallel to the axial direction, these axial portions being formed by a plurality of added elements engaged without play when cold through the annular flanges.,

[0009] The radial direction corresponds to the direction along a radius of the turbine ring (straight line connecting the center of the turbine ring to its periphery). The axial direction corresponds to the direction along the axis of revolution of the turbine ring as well as the direction of flow of the gas flow in the vein.

[0010] The implementation of such inclined portions at the annular flanges of the ring support structure advantageously makes it possible to compensate for the differences in expansion between the annular flanges and the attachment parts of the ring sectors and therefore to reduce the mechanical stresses to which the ring sectors are subjected during operation.

[0011] Preferably, at least one of the flanges of the ring support structure is elastically deformable. This advantageously makes it possible to compensate even better for differential expansions between the attachment portions of the CMC ring sectors and the flanges of the metal ring support structure without significantly increasing the stress exerted "when cold" by the flanges on the attachment portions of the ring sectors. In particular, both flanges of the ring support structure are elastically deformable or only one of the two flanges of the ring support structure is elastically deformable.

[0012] The patent further describes the case where each of the annular flanges of the ring support structure may have a first and a second inclined portion bearing on the attachment parts of the ring sectors, said first and second inclined portions each forming, when observed in meridian section, a non-zero angle relative to the radial direction and to the axial direction. The patent further describes the case where the first inclined portion may bear on the upper half of the attachment parts of the ring sectors and the second inclined portion may bear on the lower half of the attachment parts of the ring sectors.

[0013] The upper half of a hooking portion of a ring sector corresponds to the portion of said hooking portion extending radially between the mid-length zone of the hooking portion and the end of the hooking portion located on the side of the ring support structure. The lower half of a hooking portion of a ring sector corresponds to the portion of the hooking portion extending radially between the mid-length zone of the hooking portion and the end of the hooking portion located on the side of the annular base.

[0014] The ring support structure has axial portions bearing on the attachment parts of the ring sectors, the axial portions each extending parallel to the axial direction, these axial portions being formed by a plurality of added elements engaged without play when cold through the annular flanges. The attachment parts of the ring sectors are held to the ring support structure at such axial portions.

[0015] In one exemplary embodiment, the annular flanges of the ring support structure may grip the hooking portions of the ring sectors over at least half the length of said hooking portions.

[0016] In an exemplary embodiment, the annular flanges of the ring support structure may grip the attachment portions of the ring sectors at least at the outer radial ends of said attachment portions. The outer radial end of a attachment portion corresponds to the end of this attachment portion located on the side opposite the flow path of the gas flow. In particular, the annular flanges of the ring support structure may grip the attachment portions of the ring sectors only at the upper half of said attachment portions.

[0017] In an exemplary embodiment, the attachment portion of each ring sector may be in the form of radially extending tabs. In particular, the outer radial ends of the tabs of the ring sectors may not be in contact and the tabs of the ring sectors may define between them an interior ventilation volume for each of the ring sectors.

[0018] In an exemplary embodiment, the attachment portion of each of the ring sectors is in the form of a bulb.

[0019] In an exemplary embodiment, the ring sectors have a substantially Ω-shaped or substantially π-shaped section.

[0020] The present invention also relates to a turbomachine comprising a turbine ring assembly as described above.

[0021] The turbine ring assembly may be part of a gas turbine of an aero engine or may, alternatively, be part of an industrial turbine. Brief description of the drawings

[0022] Other characteristics and advantages of the invention will emerge from the following description of particular embodiments of the invention, given as non-limiting examples, with reference to the appended drawings, in which: there figure 1 is a meridian sectional view showing a turbine ring assembly outside the invention, the figure 2 represents a detail of the figure 1 , THE Figures 3 and 4 are meridian sectional views showing turbine ring assemblies outside the invention, the Figures 5 and 6 are meridian sectional views showing alternative embodiments of turbine ring assemblies according to the invention, the figure 7 represents the flange implemented in the embodiment of the figure 6 , THE figures 8 to 10illustrate the assembly of the ring sectors in the case of the example of realization of the Figure 5 , and the figures 11 to 15 illustrate the assembly of the ring sectors in the case of the example of realization of the figure 6 . Detailed description of embodiments

[0023] In the following, the terms "upstream" and "downstream" are used here in reference to the direction of flow of the gas stream in the turbine (see arrow F in figure 1 , For example).

[0024] There figure 1 , which is outside the invention, shows a turbine ring sector 1 and a casing 2 made of metallic material constituting a ring support structure. The ring support structure 2 is made of a metallic material such as the Waspaloy ®< alloy or the Inconel ®< 718 alloy.

[0025] The set of ring sectors 1 is mounted on the casing 2 so as to form a turbine ring which surrounds a set of rotating blades 3. The arrow F represents the direction of flow of the gas flow in the turbine. The ring sectors 1 are in a single piece and made of CMC. The use of a CMC material to produce the ring sectors 1 is advantageous in order to reduce the ventilation requirements of the ring. The ring sectors 1 have, in the example illustrated, a substantially Ω-shaped section with an annular base 5 whose radially inner face 6 coated with a layer 7 of abradable material defines the flow path of the gas flow in the turbine. The annular base 5 also has a radially outer face 8 from which a hooking portion 9 extends.In the example illustrated, the attachment portion 9 is in the form of a solid bulb; it does not depart from the scope of the invention when the attachment portion is in the form of a hollow bulb or when the latter is in another form as detailed below. The inter-sector seal is ensured by sealing tabs (not shown) housed in grooves facing each other in the edges opposite two neighboring ring sectors.

[0026] Each ring sector 1 described above is made of CMC by forming a fiber preform having a shape similar to that of the ring sector and densifying the ring sector with a ceramic matrix. To make the fiber preform, ceramic fiber yarns may be used, for example SiC fiber yarns such as those marketed by the Japanese company Nippon Carbon under the name "Nicalon", or carbon fiber yarns. The fiber preform is advantageously made by three-dimensional weaving, or multi-layer weaving. The weaving may be of the interlock type. Other three-dimensional or multi-layer weaving weaves may be used, such as multi-plain or multi-satin weaves. For this purpose, reference may be made to document WO 2006 / 136755.After weaving, the blank can be shaped to obtain a ring sector preform which is then consolidated and densified by a ceramic matrix, the densification being able to be carried out in particular by chemical gas infiltration (CVI) which is well known per se. A detailed example of manufacturing ring sectors in CMC is notably described in document US 2012 / 0027572.

[0027] The casing 2 comprises two annular radial flanges 11a and 11b made of metallic material extending radially towards a flow vein of the gas flow. The annular flanges 11a and 11b of the casing 2 axially enclose the attachment parts 9 of the ring sectors 1. Thus, as illustrated in figure 1, the hooking parts 9 of the ring sectors 1 are held between the annular flanges 11a and 11b, the hooking parts 9 being housed between the annular flanges 11a and 11b. Furthermore, in a conventional manner, ventilation holes 34 formed in the flange 11a make it possible to bring cooling air to the outer side of the turbine ring 1.

[0028] The annular flanges 11a and 11b each have two inclined portions resting on the attachment parts 9 of the ring sectors 1 and ensuring their retention. The inclined portions of the annular flanges 11a and 11b are in contact with the attachment parts 9 of the ring sectors 1. The upstream annular flange 11a has a first inclined portion 12a and a second inclined portion 13a. The flange 11a also has a third portion 15a extending in the radial direction R and located between the first 12a and the second 13a inclined portion. The downstream annular flange 11b also has a first inclined portion 12b and a second inclined portion 13b. The flange 11b also has a third portion 15b extending in the radial direction R and located between the first 12b and the second 13b inclined portion. When observed in meridian section and as illustrated in Figures 1 and 2, the first inclined portion 12a of the upstream annular flange 11a forms a non-zero angle α 1 with the radial direction R and forms a non-zero angle α 2 with the axial direction A. Similarly, when observed in meridian section, the second inclined portion 13a of the upstream annular flange 11a forms a non-zero angle α 3 with the radial direction R and forms a non-zero angle α 4 with the axial direction A. The same is true for the first and second inclined portions 12b and 13b of the downstream annular flange 11b. The first and second inclined portions 12a and 13a extend in non-parallel directions (they form a non-zero angle between them). The same is true for the first and second inclined portions 12b and 13b. As shown, the inclined portions of the annular flanges 11a and 11b extend at a non-zero angle with the radial direction R and a non-zero angle with the axial direction A.In the illustrated example, the inclined portions of the annular flanges 11a and 11b each extend in a straight line. In the illustrated example, the inclined portions 12a, 12b, 13a and 13b each have an elongated shape. When observed in meridian section, all or part of the inclined portions of the annular flanges 11a and 11b may form an angle of between 30° and 60° with the radial direction. For each of the annular flanges 11a and 11b, the angle formed between its first inclined portion and the radial direction may or may not be equal to the angle formed between its second inclined portion and the radial direction, when the first and second inclined portions are observed in meridian section.

[0029] In the example illustrated, the annular flanges 11a and 11b enclose the attachment parts 9 of the ring sectors over more than half of the length l of said attachment parts 9, in particular over at least 75% of this length. The length l is measured in the radial direction R.

[0030] In the example shown in figure 1, the first inclined portions 12a and 12b are, when observed in meridian section, each resting on the upper half M 1 of the hooking parts 9 and the second inclined portions 13a and 13b are, when observed in meridian section, each resting on the lower half M 2 of the hooking parts 9. The upper half M 1 corresponds to the portion of the hooking part 9 extending radially between the zone Z at mid-length of the hooking part 9 and the end E 1 of the hooking part located on the side of the ring support structure 2 (external radial end). The lower half M 2 corresponds to the portion of the attachment part 9 extending radially between the zone Z at mid-length of the attachment part 9 and the end E 2 of the attachment part located on the side of the annular base 5 (internal radial end).The inclined portions of the annular flanges 11a and 11b define two hooks between which the attachment portions 9 of the ring sectors 1 are axially clamped. Each of these hooks has, in the example illustrated, substantially a C shape.

[0031] As mentioned above, the implementation of the inclined portions advantageously makes it possible to compensate for the differences in expansion between the annular flanges 11a and 11b, on the one hand, and the ring sectors 1, on the other hand, and thus to reduce the mechanical stresses to which the ring sectors 1 are subjected during operation.

[0032] In the figures 1 to 5 , at least one of the annular flanges (flange 11b at the figure 1 ) is, as illustrated, provided on its external face with a hook 25 whose function will be detailed later.

[0033] In the example shown in figure 1, the ring sectors 1 are held on the ring support structure 2 solely by the annular flanges 11a and 11b (no presence of an added element such as a pin through the attachment part 9 of the ring sectors). As will be detailed below, the exemplary embodiments of the invention use such added elements in order to participate in holding the ring sectors on the ring support structure.

[0034] We represented at the figure 3a turbine ring assembly outside the invention. In this example, the attachment part of the ring sectors 1a is in the form of lugs 9a and 9b extending radially from the external face 8 of the annular base 5. In this example, the external radial ends 10a and 10b of the lugs 9a and 9b of the ring sectors 1a are not in contact. The external radial end of a lug of a ring sector corresponds to the end of said lug located on the side opposite the flow path of the gas flow. The external radial ends 10a and 10b are, in the example illustrated in figure 3, spaced along the axial direction A. The legs 9a and 9b of the ring sectors define between them an interior ventilation volume V for each of the ring sectors 1a. It is thus possible to ventilate the ring sectors 1a by sending cooling air towards their annular base 5 through the ventilation orifice 14 defined between the legs 9a and 9b.

[0035] The 1a ring sectors of the figure 3 substantially have an open Ω shape at its end located on the side of the ring support structure 2.

[0036] The fiber preform intended to form the ring sector 1a of the type illustrated in figure 3can be produced by three-dimensional weaving, or multi-layer weaving with the provision of separation zones making it possible to separate the parts of preforms corresponding to the legs 9a and 9b from the part of preform corresponding to the base 5. Alternatively, the parts of preforms corresponding to the legs can be produced by weaving layers of threads passing through the part of preform corresponding to the base 5.

[0037] We represented at the figure 4an alternative embodiment according to the invention in which the ring sectors 1b are held to the ring support structure 2 by means of annular flanges 21a and 21b each having, as illustrated, an axial portion 16a or 16b extending parallel to the axial direction A. In addition, each of the annular flanges 21a and 21b has a single inclined portion 13a or 13b bearing on the lugs 19a or 19b of the ring sectors 1b and forming a non-zero angle relative to the radial direction R and to the axial direction A. The axial portions 16a and 16b bear on the lugs 19a and 19b of the ring sectors. The tabs 19a and 19b forming the attachment portion of the ring sectors 1b are held to the ring support structure 2 at the axial portions 16a and 16b. The axial portions 16a and 16b formed by the annular flanges block the movement of the ring sectors 1b outwards in the radial direction R.The annular flanges 21a and 21b axially grip the legs 19a and 19b of the ring sectors 1b at their external radial end 20a and 20b. In the example illustrated, the inclined portion and the axial portion form for each of the annular flanges 21a and 21b a hook bearing on the legs 19a and 19b of the ring sectors 1b. The legs 19a and 19b of the ring sectors 1b are axially gripped between these two hooks formed by the annular flanges 21a and 21b. In the example illustrated in . figure 4 , the ring sectors 1b have a section substantially in the shape of a π.

[0038] The embodiments which will be described are illustrated in Figures 5 and 6 concern the case where an attached element is present across the attachment part of the ring sectors in order to maintain the latter. We have shown in the Figure 5an alternative embodiment in which the ring sectors 1c are held by locking pins 35 and 37. More precisely and as illustrated in the Figure 5, pins 35 are engaged both in the annular upstream radial flange 31a of the ring support structure 2 and in the upstream tabs 29a of the ring sectors 1c. For this purpose, the pins 35 each pass through a hole provided in the annular upstream radial flange 31a and a hole provided in each upstream tab 29a, the holes in the flange 31a and the tabs 29a being aligned when the ring sectors 1c are mounted on the ring support structure 2. Similarly, pins 37 are engaged both in the annular downstream radial flange 31b of the ring support structure 2 and in the downstream tabs 29b of the ring sectors 1c. For this purpose, the pins 37 each pass through an orifice provided in the annular downstream radial flange 31b and an orifice provided in each downstream tab 29b, the orifices of the flange 31b and the tabs 29b being aligned during the mounting of the ring sectors 1c on the ring support structure 2.The pins 35 and 37 are engaged without play when cold through the flanges 31a and 31b and the lugs 29a and 29b. The pins 35 and 37 make it possible to lock the ring sectors 1c in rotation. The pins 35 and 37 block the movement of the ring sectors 1c inward and outward in the radial direction R. The annular flanges 31a and 31b each further have a single inclined portion 13a or 13b making it possible to reduce the stress applied to the ring sectors 1c during the expansion of the annular flanges 31a and 31b during operation.

[0039] We represented at the figure 6an alternative embodiment in which each ring sector 1c has a substantially π-shaped section with an annular base 5 whose internal face coated with a layer 7 of abradable material defines the gas flow stream in the turbine. Upstream and downstream legs 29a and 29b extend from the external face of the annular base 5 in the radial direction R.

[0040] The ring support structure 2 is, in this embodiment, formed of two parts, namely a first part corresponding to an annular upstream radial flange 31a which is preferably formed integrally with a turbine casing and a second part corresponding to an annular retention flange 50 mounted on the turbine casing. The annular upstream radial flange 31a comprises an inclined portion 13a as described above bearing on the upstream tabs 29a of the ring sectors 1c. On the downstream side, the flange 50 comprises an annular web 57 which forms an annular downstream radial flange 54 comprising an inclined portion 13b as described above bearing on the downstream tabs 29b of the ring sectors 1c.The flange 50 comprises an annular body 51 extending axially and comprising, on the upstream side, the annular web 57 and, on the downstream side, a first series of teeth 52 distributed circumferentially on the flange 50 and spaced from each other by first engagement passages 53 (. figure 7 ). The turbine casing has on the downstream side a second series of teeth 60 extending radially from the inner surface 38a of the shell 38 of the turbine casing. The teeth 60 are distributed circumferentially on the inner surface 38a of the shell 38 and spaced from each other by second engagement passages 61 ( figure 13 ). Teeth 52 and 60 cooperate with each other to form a circumferential dog clutch.

[0041] The legs 29a and 29b of each ring sector 1c are mounted in prestress between the annular flanges 31a and 54 so that the flanges exert, at least when “cold”, that is to say at an ambient temperature of approximately 25°C, a stress on the legs 29a and 29b. Furthermore, as in the embodiment of the Figure 5 , ring sectors 1c are further held by blocking pins 35 and 37.

[0042] At least one of the flanges of the ring support structure is elastically deformable, which makes it possible to further compensate for differential expansions between the legs of the CMC ring sectors and the flanges of the metal ring support structure without significantly increasing the stress exerted "when cold" by the flanges on the legs of the ring sectors.

[0043] Furthermore, the seal between the upstream and downstream of the turbine ring assembly is ensured by an annular boss 70 extending radially from the internal surface 38a of the shell 38 of the turbine casing and the free end of which is in contact with the surface of the body 51 of the flange 50.

[0044] Two mounting methods that can be used to mount the ring sectors to the ring support structure will now be described.

[0045] THE figures 8 to 10 which will be described illustrate the assembly of the ring sectors in the case of the example of realization of the Figure 5 . As illustrated on the figure 8, the spacing E between the annular upstream radial flange 31a and the annular downstream radial flange 31b at “rest”, that is to say when no ring sector is mounted between the flanges, is less than the distance D present between the external faces 29c and 29d of the upstream and downstream legs 29a and 29b of the ring sectors. The spacing E is measured between the ends of the inclined portions 13a and 13b of the annular flanges 31a and 31b.

[0046] The ring support structure comprises at least one annular flange which is elastically deformable in the axial direction A of the ring. In the present example, the annular downstream radial flange 31b is elastically deformable. When mounting a ring sector 1c, the annular downstream radial flange 31b is pulled in the axial direction A as shown in the figures 9 And 10in order to increase the spacing between the flanges 31a and 31b and allow the insertion of the tabs 29a and 29b between the flanges 31a and 31b without risk of damage. Once the tabs 29a and 29b of a ring sector 1c are inserted between the flanges 31a and 31b and positioned so as to align the orifices 35a and 35b, on the one hand, and 37a and 37b on the other hand, the flange 31b is released in order to hold the ring sector. In order to facilitate the separation by traction of the annular downstream radial flange 31b, the latter comprises a plurality of hooks 25 distributed on its face 31c, face which is opposite the face 31d of the flange 31b opposite the downstream tabs 29b of the ring sectors 1c. The traction in the axial direction A of the ring exerted on the elastically deformable flange 31b is here carried out by means of a tool 250 comprising at least one arm 251 whose end comprises a hook 252 which is engaged in the hook 25 present on the external face 31c of the flange 31b.

[0047] The number of hooks 25 distributed on the face 31c of the flange 31b is defined as a function of the number of traction points that one wishes to have on the flange 31b. This number depends mainly on the elastic character of the flange. Other shapes and arrangements of means making it possible to exert traction in the axial direction A on one of the flanges of the ring support structure can of course be envisaged.

[0048] Once the ring sector 1c is inserted and positioned between the flanges 31a and 31b, pins 35 are engaged in the aligned orifices 35b and 35a provided respectively in the annular upstream radial flange 31a and in the upstream tab 29a, and pins 37 are engaged in the aligned orifices 37b and 37a provided respectively in the annular downstream radial flange 31b and in the downstream tab 29b. Each tab 29a or 29b of the ring sector may comprise one or more orifices for the passage of a locking pin.

[0049] A similar method can be used to achieve the assembly of the ring sectors in the context of the examples illustrated in figures 1 , 3 and 4 except that no blocking pawn is used in this case.

[0050] We will now describe the assembly of the ring sectors 1c in the case of the example of realization of the figure 6 . As illustrated on the figure 11 , the ring sectors 1c are first fixed by their upstream tab 29a to the annular upstream radial flange 31a of the ring support structure 2 by pins 35 which are engaged in the aligned orifices 35b and 35a provided respectively in the annular upstream radial flange 31a and in the upstream tab 29a.

[0051] Once all the ring sectors 1c are thus fixed to the annular upstream radial flange 31a, the annular retention flange 50 is assembled by dog-engaging between the turbine casing and the downstream tabs of the ring sectors 29b. In accordance with the embodiment described here, the spacing E' between the annular downstream radial flange 54 formed by the annular web 57 of the flange 50 and the external surface 52a of the teeth 52 of said flange is greater than the distance D' present between the external face 29d of the downstream tabs 29b of the ring sectors and the internal face 60a of the teeth 60 present on the turbine casing.By defining a spacing E' between the annular downstream radial flange and the external surface of the teeth of the flange greater than the distance D' between the external face of the downstream tabs of the ring sectors and the internal face of the teeth present on the turbine casing, it is possible to mount the ring sectors in prestress between the flanges of the ring support structure.

[0052] The ring support structure comprises at least one annular flange which is elastically deformable in the axial direction A of the ring. In the example described here, it is the annular downstream radial flange 54 present on the flange 50 which is elastically deformable. Indeed, the annular web 57 forming the annular downstream radial flange 54 of the ring support structure 2 has a reduced thickness compared to the annular upstream radial flange 31a, which gives it a certain elasticity.

[0053] As illustrated on the figures 14 and 15, the flange 50 is mounted on the turbine casing by placing the teeth 52 present on the flange 50 opposite the engagement passages 61 provided on the turbine casing, the teeth 60 present on said turbine casing also being placed opposite the engagement passages 53 provided between the teeth 52 on the flange 50. The spacing E' being greater than the distance D', it is necessary to apply an axial force on the flange 50 in the direction indicated on the figure 14 in order to engage the teeth 52 beyond the teeth 60 and allow a rotation R' of the flange according to an angle corresponding substantially to the width of the teeth 60 and 52. After this rotation, the flange 50 is released, the latter then being maintained in axial constraint between the downstream tabs 29b of the ring sectors and the internal surface 60a of the teeth 60 of the turbine casing.

[0054] Once the flange is thus put in place, pins 37 are engaged in the aligned orifices 56 and 37a provided respectively in the annular downstream radial flange 54 and in the downstream lug 29b. Each ring sector lug 29a or 29b may comprise one or more orifices for the passage of a locking pin.

[0055] The expression "between ... and ..." or "ranging from ... to ..." must be understood as including the limits.

Claims

1. A turbine ring assembly comprising a plurality of ring sectors (1b; 1c) made of ceramic matrix composite material forming a turbine ring, and also a ring support structure (2), each ring sector (1b; 1c) having a portion forming an annular base (5) with an inner face (6) defining the inside space of the turbine ring and an outer face (8) from which an attachment portion (19a; 19b; 29a; 29b) of the ring sector to the ring support structure extends, the ring support structure (2) comprising two annular flanges (21a; 21b; 31a; 31b; 50) between which the attachment portion of each ring sector is held, each of the annular flanges of the ring support structure presenting at least one sloping portion(12a; 12b; 13a; 13b) bearing against the attachment portions of the ring sectors, said sloping portion, when observed in meridian section, forming a non-zero angle relative to the radial direction (R) and relative to the axial direction (A), characterized in that the attachment portions (19a; 19b; 29a; 29b) of the ring sectors (1b; 1c) are held to the ring support structure (2) by axial portions (16a; 16b) each extending parallel to the axial direction, these axial portions being formed by a plurality of fitted elements engaged without clearance when cold through the annular flanges.

2. An assembly according to claim 1, wherein the annular flanges (11a; 11b) of the ring support structure (2) grip the attachment portions (9) of the ring sectors (1) over at least half of the length ℓ of said attachment portions (9).

3. An assembly according to claim 1 or 2, wherein the annular flanges (21a; 21b) of the ring support structure (2) grip the attachment portions (19a; 19b) of the ring sectors (1b) at least at the radially outer ends (20a; 20b) of said attachment portions (19a; 19b).

4. An assembly according to any one of claims 1 to 3, wherein the attachment portion of each ring sector is in the form of tabs (9a; 9b; 19a; 19b; 29a; 29b) extending radially.

5. An assembly according to claim 4, wherein the radially outer ends (10a; 10b; 20a; 20b) of the ring sector tabs do not come into contact and wherein the tabs of the ring sectors define between them an internal ventilation volume (V) for each of the ring sectors.

6. An assembly according to any one of claims 1 to 3, wherein the attachment portion of each of the ring sectors is in the from of a bulb (9).

7. An assembly according to any one of claims 1 to 6, wherein the ring sectors are of a section that is substantially Ω-shaped or substantially π-shaped.

8. A turbine engine including a turbine ring assembly according to any one of claims 1 to 7.