ARRANGEMENT FOR TURBINE AND GAS TURBINE DRIVE WITH SUCH ARRANGEMENT

Description

DOMAINE DE L'INVENTION

[0001] A turbine assembly is provided, comprising a plurality of ceramic matrix composite (or CMC) ring sectors assembled to form a turbine ring, and a ring support structure.

[0002] The field of application of the invention is in particular that of aeronautical gas turbine or turbomachine engines. The invention is however applicable to other turbomachines, for example industrial turbines. ETAT DE LA TECHNIQUE

[0003] In gas turbine aircraft engines, improving efficiency and reducing certain pollutant emissions is leading to the search for operation at ever higher temperatures. According to the state of the art, an all-metal turbine ring assembly is already known. However, it is necessary to cool all the elements of this assembly and in particular the turbine ring, because the latter is subjected to very hot flows, the temperature of which is higher than that which can be tolerated by metallic materials.

[0004] However, this cooling has a significant impact on engine performance, as 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.

[0005] In an attempt to resolve the above problem, it was considered to produce a turbine ring sector in ceramic matrix composite (CMC) material, in order to avoid the use of a metallic material.

[0006] Ceramic matrix composite materials are known to retain their mechanical properties at significantly higher temperatures than metals, making them suitable for use in hot structural elements. The use of this type of material reduces the cooling flow rate of the parts and therefore increases the performance of the turbomachine. In addition, CMC materials have the advantage of having a lower density than the metals usually used to make a turbine ring. This makes it possible to envisage a significant weight saving for the entire turbomachine.

[0007] The production of turbine ring sectors in a single piece of CMC material is described in particular in document US 2012 / 0027572. The ring sectors comprise an annular base whose internal face defines the internal face of the turbine ring and an external face, from which two legs extend radially, the ends of which are held between the two flanges of a metal ring support structure.

[0008] The use of CMC ring sectors thus makes it possible to significantly reduce the ventilation required to cool the turbine ring. However, since CMC has a different mechanical behavior than a metallic material, its integration and the way of positioning it within the turbine had to be rethought. Indeed, CMC does not support shrink-fit assemblies (usually used for metallic rings) and its thermal expansion is lower than that of a metallic material.

[0009] We already know from document WO 2015 / 191 169, a turbine assembly comprising a plurality of turbine ring sectors made of ceramic composite material, a support structure held by an external casing, (this structure comprising an annular shell and annular spacer sectors), and an air deflector which diffuses air.

[0010] Also known from WO 2015 / 108 658 is a turbine assembly which comprises a ring support structure and a plurality of turbine ring sectors which together form a turbine ring. This assembly also comprises a deflector provided with a passage allowing the introduction of cooling air onto the radially inner face of the turbine ring sector.

[0011] Finally, document EP 3 118 417 discloses a turbine assembly which comprises a plurality of turbine ring sectors made of CMC ceramic materials and a ring support structure. A deflector may be arranged radially between the support and the ring sector.

[0012] However, none of these documents describes or suggests the mounting of the air diffuser by fitting onto one of said spacer sectors, nor the structure of the air diffuser according to the invention. EXPOSE DE L'INVENTION

[0013] An aim of the invention is to propose a turbine ring assembly which does not have the aforementioned drawbacks and in particular which is less heavy than the turbine ring assemblies known from the state of the art, with, in particular, the elimination of all the bolted connections, usually present in this type of integration.

[0014] To this end, the invention relates to a turbine assembly extending around a longitudinal axis, this assembly comprising: a plurality of turbine ring sectors made of ceramic matrix composite material, assembled circumferentially end-to-end to form a turbine ring, each turbine ring sector comprising a base with a radially inner face and a radially outer face from which an upstream leg and a downstream leg extend radially outwardly, axially spaced from one another, a ring support structure, held by an annular outer turbine casing, said ring support structure comprising an annular shroud, and a plurality of angular spacer sectors together forming an annular spacer, said annular spacer being fixed to said annular shroud, and each turbine ring sector being fixed, by said legs, to said annular spacer, at least one air diffuser,configured to diffuse cooling air onto said radially outer face of at least one of said turbine ring sectors.

[0015] According to the invention, said at least one air diffuser is mounted by fitting onto one of said angular spacer sectors, in a fitted position, - the air diffuser has an internal cavity and a radially internal face pierced with a plurality of air ejection orifices opening into this cavity, each angular spacer sector has a radially internal face and has on its radially internal face, a rectilinear fitting groove, which has over part of its length, a fitting zone of T-shaped cross section, in that each air diffuser is provided, at its radially external part, with a hooking member also in the form of a T, configured to be able to be received and fitted into said fitting zone,the attachment member of the air diffuser is pierced with an air intake hole opening into said internal cavity and each angular spacer sector comprises at least one air supply duct, opening on the one hand onto one of its upstream faces and on the other hand into the bottom of the T-shaped fitting zone of the groove, opposite the mouth of the air intake hole of the attachment member of the diffuser, when this diffuser is in its fitted position, so that this air supply duct is in fluid communication with said air ejection orifices.,

[0016] Thanks to these characteristics of the invention, and in particular to the fitting of the air diffuser onto one of the angular spacer sectors, the assembly of the diffuser is simplified, it is no longer necessary to use bushings or pins for its fixing and the overall mass of the turbine ring assembly is lower.

[0017] Furthermore, this assembly allows the use of a ceramic matrix composite material ring and the associated advantages to be retained.

[0018] According to other advantageous and non-limiting characteristics of the invention, taken alone or in combination: said hooking member comprises at least one stop cooperating with the T-shaped interlocking zone of said interlocking groove, so as to block the axial movement of the air diffuser, once the latter is in the interlocked position; each angular spacer sector comprises an upstream hook oriented axially downstream and a downstream finger, the annular ferrule comprises two annular grooves opening upstream, and in that these grooves are intended to receive respectively said upstream hook and said downstream finger; each spacer sector is provided with an upstream flange, and a distributor of the turbine, forming a crown arranged upstream of said turbine ring assembly, presses axially against this upstream flange, in order to maintain said upstream hook and said downstream finger respectively in the corresponding grooves of the annular ferrule;said annular shell comprises a downstream flange, this downstream flange having, in the axial direction of the turbine ring, a thickness generally less than the thickness of the downstream lug of the ring sector, the downstream flange exerting a stress on the downstream lug of the ring sector; said upstream lug of a ring sector is fixed to the upstream flange of the spacer sector using fixing pins, each spacer sector comprises several downstream ears and said downstream lug of a ring sector is fixed to at least one downstream ear of this same spacer sector using fixing pins, the pins extending mainly axially;each angular spacer sector has at its two circumferential ends, sealing grooves for receiving sealing tabs, these sealing tabs being arranged in said sealing grooves between two angular spacer sectors arranged circumferentially end to end.;

[0019] The invention also relates to a turbomachine comprising a turbine assembly, as mentioned above. DESCRIPTION DES FIGURES

[0020] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which: there figure 1 represents a longitudinal sectional view of a turbine assembly according to the invention, mounted in a turbomachine. figure 2 is an enlarged longitudinal sectional view of a turbine assembly according to the invention. figure 3 is an elevation view of one end of an angular spacer sector. figure 4 is a perspective view of an air diffuser according to the invention. figure 5 is a perspective and transparent view of an angular spacer sector, on which two diffusers are mounted. figure 6 is a bottom view of an angular spacer sector on which a diffuser is mounted. figure 7 is a view similar to the figure 6 but without the diffuser. DESCRIPTION DETAILLEE DE L'INVENTION

[0021] A turbine assembly 1 according to the invention will now be described in connection with the figures 1 And 2 . This set 1 extends around a longitudinal axis X-X'.

[0022] On the figure 1 , the arrow DA indicates the axial direction of the turbine assembly 1, while the arrow DR indicates its radial direction. For reasons of simplification of the representation, the figures 1 And 2are partial views of this set, which is in reality annular.

[0023] This assembly 1 includes in particular a turbine ring 2 made of ceramic matrix composite (CMC) material, centered on the longitudinal axis XX' and a ring support structure 3, held by an annular external turbine casing 4, the latter being visible only on the figure 1 .

[0024] Turbine ring 2 surrounds a set of turbine blades 5.

[0025] In the remainder of the description, the turbine described is a high-pressure turbine. However, the invention also applies to a low-pressure turbine.

[0026] The turbine ring 2 is formed from a plurality of angular ring sectors 20, which are placed end to end circumferentially to form a ring.

[0027] Each angular ring sector 20 has a section substantially in the shape of an inverted Greek letter Pi (or Π), with a base 21, having a radially internal face 211, which defines an angular portion of the internal face of the turbine ring 2 and a radially external face 212, which defines an angular portion of the external face of the turbine ring and from which an upstream leg 22 and a downstream leg 23 extend radially outwards.

[0028] The terms "upstream" and "downstream" are used here in reference to the direction of flow of the gas stream, inside the turbine ring, represented by the arrow F on the figures 1 And 2 The two legs 22 and 23 extend over the entire width of the ring sector, in the circumferential direction. They are axially spaced from each other.

[0029] The upstream tab 22 is pierced with a plurality of axial orifices 220 and the downstream tab 23 is pierced with a plurality of axial orifices 230.

[0030] Conventionally, the seal between two neighboring angular sectors 20 is ensured by sealing tabs (not visible in the figures), housed in sealing grooves 24 provided at the two ends of each ring sector 20, the grooves 24 facing each other when two sectors 20 are assembled end to end.

[0031] The ring support structure 3 comprises several separate parts, assembled together, namely an annular ferrule 6, and in accordance with the invention, an annular spacer 7.

[0032] The annular ferrule 6 can be formed by a piece of revolution, that is to say extending over 360° or be produced by an assembly of a plurality of angular sectors placed end to end.

[0033] As it appears better on the figure 2 , the annular ferrule 6 has an upstream annular groove 61, which opens upstream, a middle annular groove 62, which also opens upstream and finally a downstream annular groove 63, which opens downstream. These different annular grooves are centered on the longitudinal axis XX' and they extend axially.

[0034] The downstream annular groove 63 is intended to receive the end of a blade of a distributor A (here for example a low pressure distributor) of the low pressure turbine, arranged downstream of the high pressure turbine and visible only on the figure 1 .

[0035] Furthermore, the annular ferrule 6 comprises an annular downstream flange 64, which extends radially inwards and the end 640 of which is curved upstream so as to extend axially. The thickness of this flange 64 in its radial part is sufficiently small so that it retains an elastic, flexible character.

[0036] Finally, the annular ferrule 6 has on its radially external face, a projection 65, intended to come into radial abutment against the external casing 4. The ferrule 6 is fixed on this casing 4 by fixing means not visible in the figures (shrinking). According to another variant embodiment not shown in the figures, the ferrule can be made in one piece with the external casing 4.

[0037] The annular spacer 7 is made up of a plurality of angular spacer sectors 70, assembled circumferentially end-to-end.

[0038] One of these 70 spacer sectors appears better on the figure 5 . Each sector 70 comprises a curved body 71 which has a radially external face 711 and a radially internal face 712. The curved downstream edge of this body 71 defines an axially oriented downstream finger 713. This downstream finger 713 is intended to be inserted into the middle annular groove 62 of the ferrule 6. As this appears better on the figure 2 , the assembly of the spacer 7 and the ferrule 6 is made so that the radially external face of the downstream finger 713 is pressed against the radially internal face of the middle annular groove 62, and this, so as to ensure sealing between the two parts.

[0039] An upstream hook 714 in the form of a ring sector, oriented axially downstream, projects outwards from the upstream end of the radially external face 711. This upstream hook 714 is intended to be inserted into the upstream annular groove 61 of the annular ferrule 6. As can be seen in the figure 2 , the assembly of the spacer 7 and the ferrule 6 is made so that the radially external face of the upstream annular groove 61 is pressed against the radially internal face of the upstream hook 714, and this, so as to ensure the seal between the two parts.

[0040] On the figure 2 , we can also see that the contact of the downstream finger 713 upwards and of the upstream hook downwards guarantees the radial positioning of each spacer sector 70 relative to the annular ferrule 6 (tilting effect).

[0041] Furthermore, the body 71 comprises an upstream flange 72 and a plurality of downstream ears 73. On the figure 5 , we can see that these ears 73 are for example two in number per sector 70. Each ear 73 is pierced with an axial orifice 730. Furthermore, the flange 72 has several blind, axial cavities 720 opening downstream.

[0042] The upstream flange 72 and the downstream ears 73 extend radially or substantially radially in the direction of the interior of the ring assembly 1, i.e. in the direction of the axis X-X'.

[0043] The turbine ring assembly 1 further comprises upstream axial pins 24 and downstream axial pins 25. The upstream axial pins 24 are inserted into the blind cavities 720 and through the orifices 220, so as to ensure the fixing of the upstream tab 22 of the ring sector 20 on the upstream flange 72. The downstream axial pins 25 are inserted through the axial orifices 730 of the spacer 7 and 230 of the ring sector 20, so as to ensure the fixing of the downstream tab 23 of the ring sector 20 on the ears 73. The different axial pins are distributed regularly around the longitudinal axis XX' of the ring.

[0044] When the assembly is carried out, the ears 73 are arranged upstream of the downstream tab 23 of the ring 2 and the upstream flange 72 is upstream of the upstream tab 22.

[0045] Furthermore, the upstream 22 and downstream 23 legs of each ring sector 20 are held respectively between the upstream flange 72 and the flange 64, which each exert an axial stress on these legs, the end 640 of the flange 64 pressing against the downstream face of the downstream leg 23, these axial stresses being opposite.

[0046] The upstream flange 72 is generally thicker in the axial direction (with the exception of the areas provided with the casings 720) than the radial part of the flange 64. The upstream flange 72 is therefore more rigid and the flange 64 more flexible and deformable.

[0047] Finally, as we can see on the figure 1 , the turbine ring assembly 1 is arranged between two distributor stages, here between distributor A for example low pressure and distributor B, for example here high pressure of the high pressure turbine. This distributor B, arranged upstream of the turbine ring assembly 1 presses axially against the upstream flange 72. Thus, in operation, the absorption of the forces of the distributor B is ensured by the spacer 7 by limiting the transmission of these forces to the ring 2 in CMC, due to the significant stiffness of the upstream flange 72. The transmission of the forces to the ring 2 is also limited by the flexible nature of the downstream flange 64.

[0048] Finally, once the assembly is carried out, the annular ferrule 6 surrounds the annular spacer 7, which itself surrounds the ring 2, so that these three elements are concentric and coaxial with longitudinal axis X-X'.

[0049] Advantageously, and as it appears better on the figure 5 , each angular spacer sector 70 has at its two ends, sealing grooves 721 for receiving sealing tabs. These tabs, not shown in the figures, are arranged between two angular spacer sectors 70, arranged circumferentially end-to-end. This makes it possible to ensure sealing between two neighboring sectors 70.

[0050] Preferably, these sealing grooves 721 are provided at both ends of the upstream flange 72, as well as at both ends of the hook 714.

[0051] The turbine assembly 1 also comprises an air diffuser 8, intended to diffuse cooling air onto the radially external face 212 of the base 21. This air diffuser 8 comprises walls which delimit an internal cavity 80 (see figure 2 ). In the embodiment shown in the figures, the walls of this air diffuser have the shape of a truncated pyramid.

[0052] This air diffuser 8 has a radially internal wall 81, preferably flat, pierced with a plurality of air ejection orifices 810.

[0053] According to the invention, each air diffuser 8 is mounted by fitting onto one of the angular spacer sectors 70. In the example shown in the figure 5 , two air diffusers 8 are mounted on an angular spacer sector 70. They are in a so-called “nested” position.

[0054] For this purpose, each angular spacer sector 70 has on one of its radially internal faces, here its face 712, a rectilinear fitting groove 74 (see figures 5 à 7 ). This groove is rectilinear, that is to say it is not curved, whereas it is formed in the body 71 which is curved.

[0055] Advantageously, the spacer sectors 70 are manufactured by additive manufacturing.

[0056] Furthermore, this groove 74 has over a part of its length, preferably its central part, a T-shaped cross-section, forming a nesting zone 742. This T-shaped cross-section appears better on the section of the figure 3 At this location, the groove 74 is punctually provided with two tongues 740 facing each other and spaced apart from each other, so as to delimit the two branches of the T.

[0057] Moreover, as it appears better on the figure 4 , the air diffuser 8 has at its radially external part, here at the top of the truncated pyramid, a hooking member 82, also T-shaped, configured to be able to be received and fitted by sliding in the groove 74. The latter being rectilinear, sliding is facilitated.

[0058] Advantageously, this hooking member 82 has at one of its ends, two stops 821, arranged on either side of the T. The horizontal branch 822 of the T-shaped hooking member is configured to be received in the groove 74 between the bottom thereof and the two tabs 740, while the vertical branch 823 of the T is received between the two tabs 740. The radially external face 824 of the member 82 is flat.

[0059] Complementary interlocking shapes of the hooking member 82 and the groove 74, other than a T-shape, could also be envisaged.

[0060] The air diffuser 8 can thus be inserted by axial sliding into the groove 74, from one of the ends of the sector 70 (insertion arrow G on the figure 6 ), the tabs 740 retaining the horizontal branch 822 of the T, until the two stops 821 come into contact with the two respective tabs 740. These stops 821 thus block the axial sliding of the air diffuser 8 inside the groove 740. The diffuser 8 cannot move further towards the center of the spacer sector 70. Additional shims, not shown in the figures, can be added to prevent the diffuser 8 from moving in the direction opposite to that of its insertion.

[0061] Furthermore, the attachment member 82 is pierced with at least one air intake hole 825 which opens both onto the external face 824 of the attachment member 82 and inside the cavity 80.

[0062] Each angular spacer sector 70 further comprises at least one air supply duct 75, (in the embodiment shown in the figure 5 two conduits 75). Each conduit 75 opens on the one hand onto the upstream face 76 of the angular sector 70 and on the other hand, into the bottom of the groove 74, opposite the portion of groove 74 having a T-shaped section (nesting zone 742). As can be seen on the figure 5 , the duct 75 is configured so that when the air diffuser 8 is positioned in abutment inside the groove 74, against the tabs 740, (nested position), this duct 75 opens at the mouth of the air intake hole 825 of the attachment member 82 of the diffuser 8.

[0063] Thus, the cooling air, taken from a stage of the turbomachine compressor, enters the duct 75 then into the diffuser 8 where it is ejected via the air ejection orifices 810, towards the internal face 212 of the base 21 of the ring sector, thus leading to the cooling of the latter.

[0064] Advantageously, the ferrule 6, the spacer 7 and the diffuser 8 are made of metal.

Claims

1. A turbine assembly (1) extending about a longitudinal axis (X-X'), said assembly (1) comprising: - a plurality of turbine ring sectors (20) made of ceramic matrix composite material, circumferentially assembled end-to-end to form a turbine ring (2), each turbine ring sector (20) comprising a base (21) with a radially inner face (211) and a radially outer face (212) from which an upstream lug (22) and a downstream lug (23), axially spaced apart from each other extend radially outwardly, - a ring support structure (3), held by an outer annular turbine casing (4), said ring support structure (3) comprising an annular shroud (6), and a plurality of angular spacer sectors (70) together forming an annular spacer (7), said annular spacer (7) being secured to said annular shroud (6), and each turbine ring sector (20) being secured by said lugs (22, 23) to said annular spacer (7), - at least one air diffuser (8), configured to diffuse cooling air onto said radially outer face (212) of at least one of said turbine ring sectors (20), - at least one air diffuser (8) is mounted by nesting on one of said angular spacer sectors (70), in a nested position, in that the air diffuser (8) has an internal cavity (80) and a radially inner face (81) pierced by a plurality of air ejection orifices (810) opening out into this cavity (80), in that each angular spacer sector (70) has a radially inner face (712) and has, on its radially inner face (712), a rectilinear engagement groove (74), which has, over part of its length, a nesting zone (742) of T-shaped cross-section, in that each air diffuser (8) is provided, at its radially outer part, with an attachment member (82) also T-shaped, configured to be received and nested in said nesting zone (742), in that the hooking member (82) of the air diffuser (8) is pierced by an air inlet hole (825) opening out into said internal cavity (80) and in that each angular spacer sector (70) comprises at least one air supply duct (75), opening out on the one hand, onto one of its upstream faces (76) and, on the other hand, into the bottom of the T-shaped nesting zone (742) of the groove (74), opposite the mouth of the air intake hole (825) of the diffuser attachment member (82), when this diffuser (8) is in its nested position, so that this air supply duct (75) is in fluid communication with said air ejection orifices (810).

2. The turbine assembly (1) according to claim 1, characterized in that said attachment member (82) comprises at least one abutment (821) cooperating with the T-shaped nesting zone (742) of said engagement groove (74), so as to block the axial displacement of the air diffuser (8), once the latter is in the nested position.

3. The turbine assembly (1) according to claim 1 or 2, characterized in that each angular spacer sector (70) comprises an upstream hook (714) oriented axially downstream and a downstream finger (713), in that the annular shroud (6) comprises two annular grooves (61, 62) opening upstream, and in that these grooves (61, 62) are intended to receive said upstream hook (714) and said downstream finger (713) respectively.

4. The turbine assembly (1) according to claim 3, characterized in that each spacer sector (70) is provided with an upstream flange (72), and in that a turbine nozzle (B), forming a ring disposed upstream of said turbine ring assembly (1), presses axially against this upstream flange (72), in order to hold said upstream hook (714) and said downstream finger (713) respectively in the corresponding grooves (61, 62) of the annular shroud (6).

5. The turbine assembly (1) according to any one of the preceding claims, characterized in that said annular shroud (6) comprises a downstream flange (64), this downstream flange (64) having, in the axial direction of the turbine ring (2), a thickness which is generally less than the thickness of the downstream lug (23) of the ring sector (20), the downstream flange (64) exerting a stress on the downstream lug (23) of the ring sector (20).

6. The turbine assembly (1) according to claim 5, characterized in that said upstream lug (22) of a ring sector (20) is fixed to the upstream flange (72) of the spacer sector (70) by means of fixing pins (24), in that each spacer sector (70) comprises a plurality of downstream ears (73) and in that said downstream lug (23) of a ring sector (20) is secured to at least one downstream ear (73) of this same spacer sector (70) by means of fixing pins (25), the pins (24, 25) extending mainly axially.

7. The turbine assembly (1) according to any one of the preceding claims, characterized in that each angular spacer sector (70) has, at its two circumferential ends, sealing grooves (721) for receiving sealing tabs, these sealing tabs being disposed in said sealing grooves (721) between two angular spacer sectors (70) disposed circumferentially end to end.

8. A turbomachine comprising a turbine assembly (1) according to any one of the preceding claims.