Turbine for turbomachine

Abstract

Turbine comprising: - an external annular casing (100) including a radial annular wall (102), - a radial flange (110) fixed to the external annular casing (100), - a ring (120) including an upstream annular flange (123) and a downstream annular flange (124), - upstream sealing means (140) interposed longitudinally between the upstream annular flange (123) of the ring (120) and the flange (110), and having a coefficient of thermal expansion between that of the flange (110) and that of the upstream annular flange (123), and / or - downstream sealing means (150) interposed longitudinally between the downstream annular flange (124) of the ring (120) and the radial annular wall (102) of the external casing, the downstream sealing means (150) having a coefficient of expansion thermal difference between that of the radial annular wall (102) of the external annular housing (100) and that of the downstream annular flange (124). Figure 3

Description

Title of the invention: Turbine for turbomachine technical field

[0001] This description relates to a turbine for a turbomachine. This description also relates to a turbomachine comprising such a turbine. Prior art

[0002] A turbomachine 10, as shown in [Fig. 1], conventionally has a longitudinal axis XI which corresponds to the axis of rotation of the rotating parts. In what follows, the terms axial and radial are defined with respect to the longitudinal axis XL. The turbomachine 10 comprises, from upstream AM to downstream AV in the direction of gas flow, a fan 11, a low-pressure compressor 12, a high-pressure compressor 13, a combustion chamber 14, a high-pressure turbine 15, and a low-pressure turbine 16. The air from the fan 11 is divided into a primary flow in a primary annular stream and a secondary flow in a secondary annular stream surrounding the primary annular stream. The low-pressure compressor 12, the high-pressure compressor 13, the combustion chamber 14, the high-pressure turbine 15 and the low-pressure turbine 16 are provided in the primary vein.

[0003] The rotor of the high-pressure turbine 15 and the rotor of the high-pressure compressor 13 are rotationally coupled via a first shaft 17 to form a high-pressure unit. The rotor of the low-pressure turbine 16 and the rotor of the low-pressure compressor 12 are rotationally coupled via a second shaft 18 to form a low-pressure unit, the blower 11 being able to be connected directly to the rotor of the low-pressure compressor or, for example, via an epicyclic gear train.

[0004] Conventionally, the rotor of the low-pressure turbine 16 or the high-pressure turbine 15 comprises a plurality of blade wheels surrounded by a turbine ring 30 externally delimiting the gas flow path.

[0005] As shown in [Fig.2], the ring 30 includes an annular platform 31, an internal radial surface of which may have an abradable coating intended to limit the circulation of parasitic air between the external radial end of the blades and the ring 30. The coating also provides a thermal barrier function.

[0006] The ring 30 comprises an upstream annular flange 32 and a downstream annular flange 33, located axially upstream and downstream respectively, and by which it is fixed to an annular external housing 20 of the turbine. The upstream annular flange 32 and the downstream annular flange 33 each extend radially outwards from the platform 31 annular. In addition, each ring 30 is constrained between, upstream, a radial annular flange 23 and, downstream, a radial annular wall 22 of the outer casing 20. To do this, the upstream annular flange 32 and the downstream annular flange 33 of the ring 30 are respectively arranged in support, in the longitudinal direction X, against the radial annular flange 23 and the radial annular wall 22 of the outer casing 20.

[0007] Furthermore, to facilitate its manufacture, the ring 30 is generally formed by a plurality of ring sectors 30 arranged circumferentially end-to-end around the longitudinal axis XI. Each ring sector 30 comprises a sector of the annular platform 31, a sector of the upstream annular flange 32 and a sector of the downstream annular flange 33.

[0008] Each ring 30 is made of a ceramic matrix composite, or CMC, while the flange and outer casing are generally made of metallic material. CMC materials are known for their mechanical properties, enabling them to maintain their mechanical integrity at high temperatures. Furthermore, CMC materials have a lower density than traditionally used metallic alloys.

[0009] However, CMC materials have a lower coefficient of thermal expansion than metallic materials. Consequently, during the operation of the turbomachine, a relative displacement was observed in the circumferential and radial directions between the sectors of the ring 30 and, on the one hand, the flange 23 upstream and the radial annular wall 22 downstream. These displacements cause wear on the upstream annular flanges 32 and downstream annular flanges 33 of the ring 30, the flange 23, and the radial annular wall 22 of the outer casing 30, which forms radial passages upstream between the flange and the upstream annular flange and downstream between the downstream annular flange and the radial annular wall of the outer casing.These passages allow radial outward leakage of gases circulating in the flow, resulting in a loss of turbomachine performance and a risk of damage to the external casing 20 subjected to high gas temperatures. Summary

[0010] A turbine for a longitudinally oriented turbomachine is proposed, the turbine comprising: - an external annular housing comprising a radial annular wall, - a radial flange fixed to the external annular housing, - a ring comprising: — an annular platform, — an upstream annular flange extending radially outwards from the annular platform, the upstream annular flange having an upstream face which is opposite, in the longitudinal direction, the flange, — a downstream annular flange extending radially outwards from the annular platform, the downstream annular flange having a downstream face which is opposite, in the longitudinal direction, the radial annular wall of the external casing, remarkable in that it comprises: - upstream sealing means interposed longitudinally between the upstream face of the upstream annular flange of the ring and the flange, the upstream sealing means having a coefficient of thermal expansion intermediate between a coefficient of thermal expansion of the flange and a coefficient of thermal expansion of the upstream annular flange, and / or - downstream sealing means interposed longitudinally between the downstream face of the downstream annular flange of the ring and the radial annular wall of the external casing, the downstream sealing means having a coefficient of thermal expansion intermediate between a coefficient of thermal expansion of the radial annular wall of the external annular casing and a coefficient of thermal expansion of the downstream annular flange.

[0011] By "intermediate coefficient of thermal expansion between," it is appropriate to understand a coefficient that can take any value within an interval delimited by and including the bounds formed by the coefficients of thermal expansion of the two opposing parts, respectively upstream or downstream. Thus, the coefficient of thermal expansion of the upstream sealing means can be equal to the coefficient of thermal expansion of the flange; and / or the coefficient of thermal expansion of the downstream sealing means can be equal to the coefficient of thermal expansion of the radial annular wall of the external casing.

[0012] The coefficient of thermal expansion of the upstream sealing means and / or the downstream sealing means can be between 6.106 C 1 and 15.106 C1.

[0013] The upstream sealing means and / or the downstream sealing means may be made of a ceramic matrix oxide / oxide composite material or of a monolithic ceramic matrix oxide composite material, or alternatively of a metallic material. The metallic material may be a titanium alloy.

[0014] The coefficient of thermal expansion of the ring can be between 1.5 x 10⁶ C₁ and 6 x 10⁶ C₁. Preferably, the coefficient of thermal expansion of the ring can be between 3.5 x 10⁶ C₁ and 5 x 10⁶ C₁. The coefficient of thermal expansion of the flange and / or the external annular housing can be between 12 x 10⁶ C₁ and 15 x 10⁶ C₁.

[0015] The ring can be made of a silicon carbide-based ceramic matrix composite material. The flange and / or the outer annular housing can be made of a metallic material.

[0016] The upstream sealing means may include an upstream annular disc which has an upstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on a downstream face of the flange and a downstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on an upstream face of the upstream annular flange of the ring, the upstream disc preferably also having, in whole or in part, a trapezoidal shape in a cutting plane comprising the longitudinal axis, a long side of the trapezoid coinciding with a downstream face of the upstream disc and a short side of the trapezoid coinciding with an upstream face of the upstream disc.

[0017] In this disclosure, the term "disc" is to be understood in its broadest sense, namely a substantially axisymmetric element (possibly sectorized, the sectors together forming a substantially axisymmetric entity), of small thickness (along the longitudinal axis X) compared to its diameter. This definition includes, in particular, discs with openings in their center, such as rings, open discs, flanges, cups, etc.

[0018] Upstream sealing means may include: - an internal upstream rim extending longitudinally upstream from the upstream disc and bearing, preferably in a watertight manner, radially outwards on a radially internal face of the flange; and / or - an external upstream rim extending radially upstream from the upstream disc and bearing, preferably in a sealed manner, radially inwards on a radially external face of the flange.

[0019] The downstream sealing means may include an annular downstream disc which has an upstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on a downstream face of the downstream annular flange of the ring and a downstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on an upstream face of the radial annular wall of the external annular housing, the downstream disc preferably also having, in whole or in part, a trapezoidal shape in a cutting plane comprising the longitudinal axis, a long side of the trapezoid coinciding with an upstream face of the downstream disc and a short side of the trapezoid coinciding with a downstream face of the downstream disc.

[0020] Downstream sealing means may include: - an internal downstream rim extending longitudinally downstream from the downstream disc and bearing, preferably in a sealed manner, radially outwards on a radially internal face of the radial annular wall of the external annular housing; and / or - an external downstream rim extending radially downstream from the downstream disc and bearing, preferably in a sealed manner, radially inwards on a radially external face of the radial annular wall of the external annular housing.

[0021] According to another aspect, a turbomachine is proposed comprising a turbine as described above. Brief description of the drawings

[0022] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0023] [Fig-1] is a schematic cross-sectional view that represents a turbomachine according to the state of the art;

[0024] [Fig.2] is a schematic cross-sectional view representing a turbine housing and a turbine ring of the turbomachine of the [Fig.l];

[0025] [Fig.3] is a schematic cross-sectional view representing a turbine housing, a turbine ring for turbomachine and upstream and downstream sealing means according to a first configuration of the present description;

[0026] [Fig.4] is a schematic front view of the turbine ring and means downstream sealing of the figure;

[0027] [Fig. 5] is a schematic cross-sectional view representing a turbine housing, a turbine ring for turbomachine and upstream and downstream sealing means according to a second configuration of this description;

[0028] [Fig.6] is a schematic perspective view which represents the means upstream and downstream sealing according to the second configuration;

[0029] [Fig.7] is a schematic perspective view which represents means upstream and downstream sealing according to a third configuration. Description of the implementation methods

[0030] Reference is now made first to figures 3 and 4 which partially represent a turbine for a turbomachine with longitudinal axis XI.

[0031] In the present description, the longitudinal direction XI corresponds to the direction of the longitudinal axis XI. The longitudinal axis XI coincides with an axis of rotation of the rotor parts of the turbomachine. Orientation qualifiers, such as "longitudinal," "radial," or "circumferential," are defined, unless otherwise specified, with reference to the longitudinal axis XL. A radial direction is a direction perpendicular to the direction of the longitudinal axis XL. A circumferential direction, at a point far from the longitudinal axis XI, corresponds to a direction perpendicular to both the longitudinal XI and radial directions. Furthermore, unless otherwise specified, the adjectives "inner," "internal," "outer," and "external" are used with reference to a radial direction, such that the inner part / The internal, i.e., radially internal, part of an element is closer to the longitudinal axis XI than the external, i.e., radially external, part of the same element. Finally, the relative terms "upstream" and "downstream" are defined with respect to the normal direction of fluid flow from upstream to downstream in the turbomachine.

[0032] In particular, the turbine includes an external annular housing 100. The external annular housing includes a radial annular wall 102. The housing may include a cylindrical wall 101 with longitudinal axis XL. The radial annular wall 102 of the external annular housing 100 may extend radially inwards from the cylindrical wall 101, in particular from a downstream end portion of the cylindrical wall 101.

[0033] The turbine includes a radial flange 110 fixed to the external annular housing 100. The flange 110 can be connected, preferably fixedly, to the external annular housing 100.

[0034] The turbine further comprises a ring 120. The ring 120 may be designed to surround an annular row of moving turbine blades. The ring 120 may radially delimit on the outside a primary annular gas flow channel V within the turbine. The ring 120 comprises an annular platform 121. The annular platform 121 may have a radially internal face adapted to support an abradable material 122 of the turbine. The abradable material 122 may be suitable for sealing with the moving blades, in particular with the blade tips of the moving blades. The radially internal face of the annular platform 121 may radially delimit on the outside the primary annular flow channel V. The ring 120 may comprise a plurality of ring 120 sectors. The sectoring of the ring 120 further facilitates the manufacturing of the ring 120 and its integration into the turbine.Each sector of ring 120 can extend between a first end and a second end in the circumferential direction.

[0035] The ring 120 further comprises an upstream annular flange 123 extending radially outwards from the annular platform 121, the upstream annular flange 123 having an upstream face that is opposite, in the longitudinal direction XI, the flange 110 of the outer housing. Similarly, the ring 120 comprises a downstream annular flange 124 extending radially outwards from the annular platform 121, the downstream annular flange 124 having a downstream face that is opposite, in the longitudinal direction XI, a radial annular wall 102 of the outer housing.

[0036] Remarkably, the turbine includes upstream sealing means 140 interposed longitudinally between the upstream face of the upstream annular flange 123 of the ring 120 and the flange 110, the upstream sealing means 140 having a coefficient of thermal expansion intermediate between a coefficient of expansion thermal coefficient of the flange 110 and a coefficient of thermal expansion of the upstream annular flange 123. The term "intermediate" is to be understood as including the limits delimiting the interval, or including at least the limit dictated by the housing: the coefficient of thermal expansion of the upstream sealing means is included in an interval bounded by and including the coefficients of thermal expansion of the flange 110 and the upstream annular flange 123. In particular, the coefficient of thermal expansion of the upstream sealing means may be equal to the coefficient of thermal expansion of the flange.

[0037] Alternatively or in addition, the turbine includes downstream sealing means 150 interposed longitudinally between the downstream face of the downstream annular flange 124 of the ring 120 and the radial annular wall 102 of the outer casing, the downstream sealing means 150 having a coefficient of thermal expansion intermediate between a coefficient of thermal expansion of the radial annular wall 102 of the outer annular casing 100 and a coefficient of thermal expansion of the downstream annular flange 124. Here too, the term "intermediate" is to be understood as including the limits delimiting the interval, or including at least the limit dictated by the casing: the coefficient of thermal expansion of the downstream sealing means is included in an interval bounded by and including the coefficients of thermal expansion of the downstream annular flange 124 and the radial annular wall 102.In particular, the coefficient of thermal expansion of the downstream sealing means can be equal to the coefficient of thermal expansion of the radial annular wall of the external casing.

[0038] The upstream sealing means 140 thus form an intermediate interface between the flange 110 and the upstream annular flange 123. The displacements induced by the differences in thermal coefficient are thus reduced on the one hand between the flange 110 and the upstream sealing means 140, and on the other hand between the upstream sealing means 140 and the upstream annular flange 123. Consequently, reduced wear of the flange 110 and the upstream annular flange 123 was observed, thus reducing the formation of a passage between the radial flange 110 and the upstream annular flange 123 and therefore the risks of radial gas leakage to the outside towards the external annular casing 100.In the case where, for example, the coefficient of thermal expansion of the upstream sealing means 140 is equal to that of the flange, then, although there are no longer two differences in thermal expansion but only one, there is nevertheless a larger contact area between the sealing means 140 and the upstream annular flange 123, which also reduces leakage. The absence of leakage is thus confirmed over the entire interval, inclusive, formed between the values ​​of the coefficients of thermal expansion of the upstream annular flange 123 and the flange 110.

[0039] Similarly, the downstream sealing means 150 form an intermediate interface between the radial annular wall 102 of the external annular housing 100 and the annular flange downstream 124. The displacements induced by the differences in thermal coefficient are thus reduced on the one hand between the downstream annular flange 124 and the downstream sealing means 150, and on the other hand between the downstream sealing means 150 and the radial annular wall 102 of the external annular housing 100. Consequently, reduced wear was observed on the downstream annular flange 124 and the radial annular wall 102 of the external annular housing 100, thus reducing the formation of passage between the downstream annular flange 124 and the radial annular wall 102 of the external annular housing 100, and therefore reducing the risks of gas leakage radially outwards towards the external annular housing 100.In the case where, for example, the coefficient of thermal expansion of the downstream sealing means 150 is equal to that of the radial annular wall 102, then, although there are no longer two differences in thermal expansion but only one, there is nevertheless a larger contact area between the sealing means 150 and the downstream annular flange 124, which also reduces leakage. The absence of leakage is thus confirmed over the entire interval, inclusive, formed between the values ​​of the coefficients of thermal expansion of the downstream annular flange 124 and the radial annular wall 102.

[0040] According to another formulation, the upstream sealing means 140 can be clamped longitudinally between the upstream face of the upstream annular flange 123 of the ring 120 and the flange 110. Similarly, the downstream sealing means 150 can be positioned longitudinally between the downstream face of the downstream annular flange 124 of the ring 120 and the radial annular wall 102 of the outer casing. The ring 120 is thus held in the longitudinal direction XI by being interposed between the flange 110 and the radial annular wall 102 of the outer annular casing 100, here by means of the upstream and downstream sealing means 140.

[0041] The upstream sealing means 140 can be configured to limit, or even prevent, longitudinal gas leakage between the upstream face of the upstream annular flange 123 of the ring 120 and the flange 110. Similarly, the downstream sealing means 150 can be configured to limit, or even prevent, longitudinal gas leakage between the downstream face of the downstream annular flange 124 of the ring 120 and the radial annular wall 102 of the outer casing.

[0042] The coefficient of thermal expansion of the ring 120 can be between 1.5 x 10⁶ C₁ and 6 x 10⁶ C₁, preferably between 3.5 x 10⁶ C₁ and 5.0 x 10⁶ C₁. The ring 120 can be made of a silicon carbide-based ceramic matrix composite material. Ceramic matrix composite materials (CMCs) withstand temperatures up to 1400°C. Due to their superior resistance to high temperatures, CMCs require less cooling. This cooling is traditionally obtained by drawing heat from the compressor, which impacts the In terms of turbomachine efficiency, CMC materials therefore improve engine efficiency, which reduces fuel consumption.

[0043] Furthermore, the use of ceramic matrix composite materials helps to optimize the performance of turbomachines, in particular by reducing the overall mass of the turbomachine, which further contributes to a decrease in fuel consumption and therefore to a significant reduction in pollutant emissions.

[0044] The coefficient of thermal expansion of the flange 110 and / or the external annular housing 100 can be between 12.106 C 1 and 15.106 C1. The flange 110 and / or the external annular housing 100 can be made of a metallic material.

[0045] The coefficient of thermal expansion of the upstream sealing means 140 and / or the downstream sealing means 150 can be between 6 x 10⁶ C₁ and 15 x 10⁶ C₁. In a first embodiment, the upstream sealing means 140 and / or the downstream sealing means 150 can be made of a material with a coefficient of thermal expansion less than or equal to 6 x 10⁶ C₁: a ceramic matrix oxide / oxide composite material or a monolithic ceramic matrix oxide composite material. In a second embodiment, one or both of the sealing means (upstream and / or downstream) can be made of a material with a coefficient of thermal expansion between 6 x 10⁶ C₁ and 15 x 10⁶ C₁: for example, a metallic material, e.g., a titanium alloy.

[0046] The upstream sealing means 140 may include an annular upstream disc 141. The upstream disc 141 can be interposed longitudinally between the upstream face of the upstream annular flange 123 of the ring 120 and the flange 110. In other words, the upstream disc 141 can be clamped longitudinally between the upstream face of the upstream annular flange 123 of the ring 120 and the flange 110. The upstream disc 141 may include an upstream face that is, in whole or in part, supported, preferably in a sealing manner, longitudinally on a downstream face of the flange 110. The upstream disc 141 may include a downstream face that is, in whole or in part, supported, preferably in a sealing manner, longitudinally on an upstream face of the upstream annular flange 123 of the ring 120. Equivalently, the upstream disc 141 may correspond to an annular radial wall of the upstream sealing means 140.

[0047] The upstream sealing means 140 may include one or more upstream scallops 144 projecting radially outward from the upstream disc 141. The term "scallop" is understood to mean a relief projecting radially outward from a radially external end of the upstream disc 141. Each upstream scallop 144 may include a base by which it is connected to the upstream disc 141. Each upstream scallop 144 may include a free edge. Each upstream scallop 144 may have a trapezoidal cross-section in a cutting plane perpendicular to the longitudinal axis XL. Alternatively, each upstream scallop 144 may have a section having a rounded shape in a cutting plane perpendicular to the longitudinal axis XI. Each upstream festoon 144 includes a hole passing through along the longitudinal direction XI.

[0048] The flange 110 may include one or more holes. The upstream annular flange 123 may include one or more holes. The turbine may include one or more upstream pins 131. Each upstream pin 131 may extend longitudinally through, from upstream to downstream along the longitudinal direction XI, one or more of said holes through the flange 110, the hole through one or more of said upstream scallops 144 of the upstream sealing means 140, and one or more of said holes through the upstream annular flange 123. This allows the radial retention of the ring 120 relative to the flange 110 and also the radial retention of the upstream sealing means 140 relative to the flange 110 and the ring 120.

[0049] According to a variant shown in Figures 5 and 6, the upstream sealing means 140 may include an internal upstream rim 142 extending longitudinally upstream from the upstream disc 141 and bearing, preferably in a watertight manner, radially outwards on a radially internal face of the flange 110. The upstream sealing means 140 may include an external upstream rim 143 extending radially upstream from the upstream disc 141 and bearing, preferably in a watertight manner, radially inwards on a radially external face of the flange 110. This ensures better upstream longitudinal sealing between the upstream sealing means 140 and the flange 110.Indeed, an upstream labyrinth is formed longitudinally between, on the one hand, the flange 110 and, on the other hand, the internal upstream rim 142, the disc and the external upstream rim 143, thus further limiting a radial outward longitudinal gas leak between the flange 110 and the upstream annular flange 123. The internal upstream rim 142 and / or the external upstream rim 143 also improve the radial retention of the upstream sealing means 140 relative to the flange 110.

[0050] The inner upstream rim 142 and / or the outer upstream rim 143 may be annular.

[0051] The external upstream rim 143 can be connected to a radially external end portion of the upstream disk 141. The internal upstream rim 142 can be connected to a radially internal end portion of the upstream disk 141. The external upstream rim 143 can be arranged radially outside with respect to the internal upstream rim 142.

[0052] The upstream disc 141 can be made of material, i.e. monobloc, with the internal upstream rim 142 and / or the external upstream rim 143.

[0053] According to another variant shown in [Fig. 7] and not exclusive of the variant in Figures 5 and 6, the upstream disc 141 may have, in whole or in part, a trapezoidal shape in a cross-sectional plane comprising the longitudinal axis XI, a long side of the trapezoid coinciding with a downstream face of the upstream disc 141 and a short side of the trapezoid coinciding with an upstream face of the upstream disc 141. Such a shape of the upstream disc 141 allows better diffusion of the clamping forces along the longitudinal axis XI in the upstream annular flange 123, thus reducing mechanical stresses.

[0054] In general, the upstream disc 141 can have a dimension along the longitudinal direction XI of between 0.05 mm and 0.3 mm.

[0055] The upstream sealing means 140 may include a plurality of sectors arranged circumferentially end to end around the longitudinal axis XL. Each sector of upstream sealing means 140 may in particular include an upstream disc sector 141, and preferably an internal upstream rim sector 142 and / or an external upstream rim sector 143. Each sector of upstream sealing means 140 may further include one or more of said one or more festoons.

[0056] Each sector of the upstream sealing means 140 can be associated with at least one, preferably only one, of the ring sectors 120. In particular, each upstream disc sector 141, and where applicable each internal upstream rim sector 142 and / or external upstream rim sector 143, can extend circumferentially between a first end and a second end which are longitudinally aligned with the first end and the second end of one of the ring sectors 120. In other words, each sector of the upstream sealing means 140 can extend circumferentially over the entire circumferential length of one of the ring sectors 120.

[0057] The downstream sealing means 150 may include an annular downstream disc 151. The downstream disc 151 can be interposed longitudinally between the downstream face of the downstream annular flange 124 of the ring 120 and the radial annular wall 102 of the external annular housing 100. In other words, the downstream disc 151 can be clamped longitudinally between the downstream face of the downstream annular flange 124 of the ring 120 and the radial annular wall 102 of the external annular housing 100. The downstream disc 151 may include an upstream face that is, in whole or in part, supported, preferably in a sealed manner, longitudinally on a downstream face of the downstream annular flange 124 of the ring 120. The downstream disc 151 may include a downstream face that is, in whole or in part, supported, preferably in a sealed manner, longitudinally on an upstream face of the radial annular wall 102 of the external annular housing 100.Equivalently, the downstream disc 151 can correspond to an annular radial wall of the downstream sealing means 150.

[0058] The downstream sealing means 150 may include one or more downstream scallops 154 projecting radially outward from the downstream disc 151. The term "scallop" is understood to mean a relief projecting radially outward from a radially external end of the downstream disc 151. Each downstream scallop 154 ​​may include a base by which it is connected to the downstream disc 151. Each downstream scallop 154 ​​may Each downstream scallop 154 ​​includes a free edge. Each downstream scallop 154 ​​may have a trapezoidal cross-section in a cutting plane perpendicular to the longitudinal axis XI. Alternatively, each downstream scallop 154 ​​may have a rounded cross-section in a cutting plane perpendicular to the longitudinal axis XI. Each downstream scallop 154 ​​includes a through hole along the longitudinal direction XI.

[0059] The radial annular wall 102 of the external annular housing 100 may include one or more holes. The downstream annular flange 124 may include one or more holes. The turbine may include one or more downstream pins 132. Each downstream pin 132 may extend longitudinally by passing through, from upstream to downstream along the longitudinal direction XI, one or more holes through the downstream annular flange 124 of the ring 120, the hole through one or more downstream scallops 154 of the downstream sealing means 150, and one or more holes through the radial annular wall 102 of the outer annular housing 100. This allows the radial retention of the ring 120 relative to the outer annular housing 100 and also the radial retention of the downstream sealing means 150 relative to the outer annular housing 100 and to the ring 120.

[0060] According to an embodiment shown in Figures 5 and 6, the downstream sealing means 150 may include an internal downstream rim 152 extending longitudinally downstream from the downstream disc 151 and bearing, preferably in a sealed manner, radially outwards on a radially internal face of the radial annular wall 102 of the external annular housing 100. The downstream sealing means 150 may also include an external downstream rim 153 extending radially downstream from the downstream disc 151 and bearing, preferably in a sealed manner, radially inwards on a radially external face of the radial annular wall 102 of the external annular housing 100. This ensures a better longitudinal downstream seal between the downstream sealing means 150 and the radial annular wall 102 of the external annular housing 100.Indeed, a downstream labyrinth is formed longitudinally between, on the one hand, the radial annular wall 102 of the external annular housing 100 and, on the other hand, the internal downstream rim 152, the disc and the external downstream rim 153, thus further limiting a radial outward longitudinal gas leak between the external annular housing 100 and the downstream annular flange 124. The internal downstream rim 152 and / or the external downstream rim 153 also improve the radial retention of the downstream sealing means 150 relative to the flange 110.

[0061] The internal downstream rim 152 and / or the external downstream rim 153 may be annular.

[0062] The external downstream rim 153 can be connected radially to an end portion external of the downstream disc 151. The internal downstream rim 152 can be connected to a radially internal end portion of the downstream disc 151. The external downstream rim 153 can be arranged radially outside with respect to the internal downstream rim 152.

[0063] The downstream disc 151 can be made of material, i.e. monobloc, with the internal downstream rim 152 and / or the external downstream rim 153.

[0064] According to another variant shown in [Fig.7] and not exclusive of the variant of Figures 5 and 6, the downstream disc 151 may have, in whole or in part, a trapezoidal shape in a cutting plane comprising the longitudinal axis XI, a long side of the trapezoid coinciding with an upstream face of the downstream disc 151 and a short side of the trapezoid coinciding with a downstream face of the downstream disc 151. Such a shape of the downstream disc 151 allows the clamping forces to be better distributed along the longitudinal axis XI in the downstream annular flange 124, thus reducing the mechanical stresses.

[0065] In general, the downstream disc 151 can have a dimension along the longitudinal direction XI of between 0.05 mm and 0.3 mm.

[0066] The downstream sealing means 150 may include a plurality of sectors arranged circumferentially end to end around the longitudinal axis XL. Each sector of the downstream sealing means 150 may in particular include a downstream disc sector 151, and preferably an internal downstream rim sector 152 and / or an external downstream rim sector 153. Each sector of the downstream sealing means 150 may further include one or more of said one or more downstream festoons 154.

[0067] Each sector of the downstream sealing means 150 can be associated with at least one, preferably only one, of the ring sectors 120. In particular, each downstream disc sector 151, and where applicable each internal downstream rim sector 152 and / or external downstream rim sector 153, can extend circumferentially between a first end and a second end which are longitudinally aligned with the first end and the second end of one of the ring sectors 120. In other words, each sector of the downstream sealing means 150 can extend circumferentially over the entire circumferential length of one of the ring sectors 120.

Claims

Demands

1. Turbine for a turbomachine with a longitudinal axis (XI), the turbine comprising: - an outer annular casing (100) including a radial annular wall (102), - a radial flange (110) fixed to the outer annular casing (100), - a ring (120) comprising: — an annular platform (121), — an upstream annular flange (123) extending radially outwards from the annular platform (121), the upstream annular flange (123) having an upstream face which is opposite, in the longitudinal direction (XI), the flange (110) — a downstream annular flange (124) extending radially outwards from the annular platform (121), the downstream annular flange (124) having a downstream face which is opposite, in the longitudinal direction (XI), the radial annular wall (102) of the external casing,characterized in that it comprises: - upstream sealing means (140) interposed longitudinally between the upstream face of the upstream annular flange (123) of the ring (120) and the flange (110), the upstream sealing means (140) having a coefficient of thermal expansion intermediate between a coefficient of thermal expansion of the flange (110) and a coefficient of thermal expansion of the upstream annular flange (123), and / or - downstream sealing means (150) interposed longitudinally between the downstream face of the downstream annular flange (124) of the ring (120) and the radial annular wall (102) of the outer casing, the downstream sealing means (150) having a coefficient of thermal expansion intermediate between a coefficient of thermal expansion of the radial annular wall (102) of the outer annular casing (100) and a coefficient of thermal expansion of the downstream annular flange (124).

2. Turbine according to the preceding claim, wherein the coefficient of thermal expansion of the upstream sealing means (140) and / or the downstream sealing means (150) is between 6.106 C* and 15.106 C1.

3. Turbine according to any one of the preceding claims, wherein the upstream sealing means (140) and / or the downstream sealing means (150) are made of a ceramic matrix oxide / oxide composite material or of a monolithic ceramic matrix oxide composite material, or alternatively of a metallic material.

4. Turbine according to any one of the preceding claims, wherein the coefficient of thermal expansion of the ring (120) is between 1.5.106 C 1 and 6.106 C 1 and / or wherein the coefficient of thermal expansion of the flange (110) and / or of the external annular casing (100) is between 12.106 C 1 and 15.106 C1.

5. Turbine according to any one of the preceding claims, wherein the ring (120) is made of a silicon carbide-based ceramic matrix composite material and / or wherein the flange (110) and / or the external annular housing (100) are made of a metallic material.

6. Turbine according to any one of the preceding claims, wherein the upstream sealing means (140) comprise an annular upstream disc (141) which has an upstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on a downstream face of the flange (110) and a downstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on an upstream face of the upstream annular flange (123) of the ring (120), the upstream disc (141) preferably further having, in whole or in part, a trapezoidal shape in a cutting plane comprising the longitudinal axis (XI), a long side of the trapezoid coinciding with a downstream face of the upstream disc (141) and a short side of the trapezoid coinciding with an upstream face of the upstream disc (141).

7. Turbine according to the preceding claim, wherein the upstream sealing means (140) comprise: - an internal upstream rim (142) extending longitudinally upstream from the upstream disc (141) and bearing, preferably in a sealing manner, radially outwards on a radially internal face of the flange (110); and / or - an external upstream rim (143) extending radially upstream from the upstream disc (141) and bearing, preferably in a sealing manner, radially outwards on a radially internal face of the flange (110); and / or sealed, radially inwards on a radially external face of the flange (110).

8. Turbine according to any one of the preceding claims, wherein the downstream sealing means (150) comprise an annular downstream disc (151) which has an upstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on a downstream face of the downstream annular flange (124) of the ring (120) and a downstream face which is, in whole or in part, supported, preferably in a sealing manner, longitudinally on an upstream face of the radial annular wall (102) of the external annular casing (100), the downstream disc (151) preferably further having, in whole or in part, a trapezoidal shape in a cutting plane comprising the longitudinal axis (XI), a long side of the trapezoid coinciding with an upstream face of the downstream disc (151) and a short side of the trapezoid coinciding with a downstream face of the downstream disc (151).

9. Turbine according to the preceding claim, wherein the downstream sealing means (150) comprise: - an internal downstream rim (152) extending longitudinally downstream from the downstream disc (151) and bearing, preferably in a sealed manner, radially outwards on a radially internal face of the radial annular wall (102) of the external annular housing (100); and / or - an external downstream rim (153) extending radially downstream from the downstream disc (151) and bearing, preferably in a sealed manner, radially inwards on a radially external face of the radial annular wall (102) of the external annular housing (100).

10. Turbomachine comprising a turbine according to any one of the preceding claims.

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