Turbine sealing ring that is removable upstream

Abstract

The invention relates to a turbine for a turbine engine comprising an annular casing (1), upstream (3) and downstream (4) ring supports and a sealing ring (2) that is configured to extend around and radially face a blading (6) of a rotor of the turbine, the supports being mounted against a radially inner surface of the casing (1), the sealing ring (2) being configured to be disposed radially between the blading (6) and the casing (1), and being mounted against the upstream support and the downstream support, the sealing ring (2) having a maximum radius with respect to the main axis (X) of the turbine, and the casing (1) being dimensioned such that the maximum radius of the sealing ring (2) is strictly less than the radius of the upstream end of the casing (1) so as to allow mounting by axial insertion, of the sealing ring (2) and of the upstream ring support (3), against the downstream ring support (4).

Description

Description Title of the invention: Sealing ring for turbine removable from upstream Technical Field

[0001] This disclosure relates to a sealing ring for a turbomachine turbine, in particular a sealing ring for a turbine that can be removed from upstream. Prior art

[0002] We know the maintenance constraints of turbomachine turbines, requiring access to parts internal to the turbines.

[0003] For example, low-pressure turbine blades are generally difficult to access for maintenance operations.

[0004] To facilitate maintenance and thus reduce operating costs, turbomachines have been designed with a sealing ring that can be removed from upstream.

[0005] However, the possibility of disassembly from upstream of the sealing ring is generally at the expense of the sealing capacity of the sealing ring, and thus of increased fuel consumption. Statement of the invention

[0006] This paper aims to propose a turbine to solve the above problems.

[0007] For this purpose, the present disclosure relates to a turbine for a turbomachine, the turbine having a main axis and comprising a casing, typically annular, an upstream ring support, a downstream ring support, a sealing ring, the sealing ring being configured to extend around and come radially opposite a blading of a rotor of the turbine, in which: the upstream ring support and the downstream ring support are mounted against a radially internal surface of the casing, the upstream ring support and the downstream ring support having an upstream end and a downstream end, the sealing ring being configured to be arranged radially between the blade and the casing, and being mounted against the upstream ring support and the downstream ring support, the sealing ring having a maximum radius with respect to the main axis, and the casing being dimensioned so that the maximum radius of the sealing ring is strictly less than the radius of the upstream end of the casing so as to allow mounting by axial insertion, of the sealing ring and the upstream ring support, against the downstream ring support.

[0008] In this disclosure, the terms “axial”, “radial”, “circumferential”, “inner”, “outer” and their derivatives are defined relative to the main axis of the turbomachine; finally, the terms “upstream”, “downstream”, “front” and “rear” are defined relative to the main axis, according to the general direction of circulation of the fluid within the turbomachine. By “extends axially, radially or circumferentially” is meant “extends in a direction having a non-zero component in an axial, radial or circumferential direction”, respectively. A circumferential direction is perpendicular to the axial direction and to a radial direction. The main axis of the turbomachine corresponds to the axis of rotation of the turbomachine.

[0009] In some embodiments, the upstream ring support is circumferential, preferably 360°. Preferably, the upstream ring support is continuously mounted to bear against a radially inner surface of the housing, along a circumference.

[0010] In some embodiments, the downstream ring support is circumferential, preferably 360°. Preferably, the downstream ring support is sectored.

[0011] Upstream ring support and downstream ring support mean an upstream support and a downstream support respectively.

[0012] Such a dimensioning of the sealing ring and the casing allows, after dismantling the upstream ring support, to dismantle the sealing ring by translation along the main axis towards the upstream without the casing being an obstacle.

[0013] In particular, front mounting can be carried out without tilting, allowing for more precise, faster mounting with reduced risk of part damage.

[0014] Naturally, unless otherwise stated, any characteristic described relating to a disassembly operation is also applicable to an assembly operation carried out in the reverse order, and vice versa.

[0015] Dismantling the sealing ring upstream thus reduces maintenance time and costs compared to a turbine whose sealing ring can only be dismantled downstream.

[0016] The support of the sealing ring on the supports ensures the centering of the sealing ring, thus reducing the relative wear of the parts while being compatible with the upstream disassembly of the sealing ring.

[0017] According to one example, the support of the sealing ring on the upstream ring support is a radial support. According to one example, the support of the sealing ring on the downstream ring support is a radial support.

[0018] Radial support means support on a surface whose normal has a non-zero radial component.

[0019] In one example, the radial support has a positive or zero component along the main axis towards the upstream, further facilitating disassembly from the upstream.

[0020] According to one example, in addition to or as a replacement, the sealing ring has axial support on the upstream ring support. According to one example, the sealing ring has axial support on the downstream ring support.

[0021] Axial support means support on a surface whose normal has a non-zero axial component.

[0022] The axial support ensures axial support on the upstream ring support.

[0023] In some embodiments, the turbine includes at least one seal disposed between the downstream ring support and the radially protruding portion.

[0024] The seal between the downstream ring support and the radially projecting portion ensures sealing despite differential thermal expansion within the turbine resulting in relative movements, in particular between the sealing ring and the downstream ring support, which can be compensated by deformation of the seal. Differential thermal expansion results from temperature differences between the ring and the downstream ring support as well as from materials with different coefficients of thermal expansion.

[0025] According to one example, the seal is an axial seal, i.e. extending axially between two contact surfaces.

[0026] The use of an axial seal is compatible with centering by the sealing ring and the downstream ring support, and the relative axial displacements between the sealing ring and the downstream ring support are thus limited, which reduces the shear forces applied to the seal and improves its service life. A fortiori, the use of an axial seal at a radial support between the downstream ring support and the sealing ring provides increased sealing and the shear forces applied to the seal are reduced as the direction of support between the downstream ring support and the sealing ring and the direction in which the seal extends form an angle close to 90°.

[0027] In some embodiments, the seal is in direct contact with the downstream ring support and the radially protruding portion.

[0028] According to one example, the seal is sectorized. In the case where at least one part among the sealing ring and the downstream ring support is sectorized, the seal is sectorized similarly to said part, that is to say comprising sectors at circumferential positions common to the sectors of said part.

[0029] Each sector of a sectored seal can move and deform more independently than a non-sectored seal, ensuring better sealing performance.

[0030] In one example, the joint is an omega joint. An omega joint is a joint whose cross-section has a shape similar to the omega symbol (Q). A cross-section of an omega joint may have an open contour or a closed contour. An omega joint may also denote an accordion-shaped joint, i.e. formed from a succession of folds in successively alternating directions, which corresponds to the junction of a plurality of omega joints with open contours.

[0031] An omega seal, and even more so an accordion-shaped seal, makes it possible to maintain sealing over a wide range of deformation while ensuring a satisfactory level of sealing.

[0032] In some embodiments, the housing is a low pressure turbine housing.

[0033] The possibility of upstream disassembly is particularly desirable for a low-pressure turbine casing, in order to facilitate maintenance operations.

[0034] In some embodiments, the blade comprises a ceramic matrix composite (CMC) material. A CMC material generally comprises fiber reinforcement within an at least partially ceramic matrix.

[0035] The use of ceramic matrix composite material allows the blading to withstand higher temperatures than blading made of metallic material, thus reducing the air flow rate taken from the high-pressure compressor required to cool the blading, which improves the specific consumption of the turbomachine, and allows the turbomachine to operate at higher temperatures, resulting in better turbomachine efficiency. In addition, ceramic matrix composite materials have a lower density than metallic materials, which allows a weight saving reducing the consumption of the turbomachine.

[0036] Compared to blades made of metallic material, blades made of CMC materials can be sensitive to FOD (Foreign Object Damage) or DOD (Domestic Object Damage), in this case internal to the turbomachine. Easier maintenance due to upstream assembly is therefore particularly desirable when using CMC blades.

[0037] In some embodiments, the sealing ring is sectored.

[0038] In some embodiments, at least one of the upstream ring support and the downstream ring support is sectored.

[0039] By sectorized we mean formed of sectors connected to each other. In this case, by sectorized we mean sectorized in a circumferential direction around the main axis, that is to say formed of sectors extending along a circumference and connected to each other.

[0040] The sectored sealing ring is less susceptible to thermal expansion than a non-sectored sealing ring, thus minimizing relative displacements between the sealing ring and other internal parts of the turbine during the life of the turbine, thus facilitating the control of the tip clearance of the blade with respect to the sealing ring and ensuring good thermal performance and maintenance of the sealing of the turbomachine.

[0041] When combined with a support(s) that are also sectored, the support(s) is (are) also less susceptible to thermal expansion, further improving control of the blade tip clearance. The reduction in displacements associated with reduced thermal expansion also allows for a reduction in the amplitude of deformations applied to intermediate parts, for example a seal, thereby reducing its fatigue damage.

[0042] In some embodiments, the turbine includes at least one locking member configured to hold together a downstream end of the sealing ring and the downstream ring support. In one example, the locking member is C-shaped and configured to hold together in contact, within the C, a downstream end of the sealing ring and the downstream ring support.

[0043] In some embodiments, the turbine includes at least one locking member configured to hold together an upstream end of the sealing ring and the upstream ring support. In one example, the locking member is C-shaped and configured to hold together in contact, within the C, an upstream end of the sealing ring and the upstream ring support.

[0044] The locking member ensures the downstream and / or upstream centering of the sealing ring, thus maintaining it in position within the turbine.

[0045] In some embodiments, the locking member is a clip.

[0046] Such a locking member is compatible with stable locking and easy removal prior to a maintenance operation on the blade.

[0047] In some embodiments, the sealing ring includes a radially projecting portion, the maximum radius of the sealing ring being equal to the maximum radius of the radially projecting portion from the main axis, i.e., the distance from the main axis of the position of the radially projecting portion furthest from the main axis.

[0048] In other words, the sealing ring includes a radially projecting portion, the maximum radius of the sealing ring being measured on the radially projecting portion.

[0049] In some embodiments, at least one sealing sheet is provided between the seal and the downstream ring support and / or between the seal and the radially projecting portion.

[0050] The sheet metal ensures good contact with the gasket, thus ensuring sealing performance.

[0051] In one example, the sheet metal is a circumferential sheet metal. A circumferential sheet metal provides the seal with a larger bearing surface, improving its efficiency and reducing its wear.

[0052] In one example, the sheet metal is a non-sectored circumferential sheet metal. For example, sheet metal is invariant under rotation around the principal axis.

[0053] In the case of a sectored sealing ring and a non-sectored sheet, the thermomechanical performance of the sectored sealing ring is preserved without degrading the sealing provided by the seal.

[0054] According to one example, the sheet metal is detachably mounted on the radially projecting portion, for example the sheet metal is clipped onto the radially projecting portion.

[0055] In one example, the sheet metal is in direct contact with the seal and one of the downstream ring support and the radially projecting portion.

[0056] By extension, the measurement of the maximum section of the sealing ring (therefore also of the radially projecting portion) includes the sheet metal mounted on the sealing ring.

[0057] In some embodiments, the turbine includes a sheet metal mounted between the seal and the downstream ring support.

[0058] The sheet metal between the seal and the front ring support ensures downstream centering by the downstream ring support.

[0059] In some embodiments, at least one of a downstream end of the sealing ring and a downstream end of the downstream ring support is received in a housing of an outer platform of a downstream distributor. By downstream distributor, for example, is meant a distributor downstream of the sealing ring.

[0060] In some embodiments, the housing is a groove into which the at least one end is axially inserted.

[0061] This disclosure also relates to a turbomachine comprising the turbine according to this disclosure. Brief description of the drawings

[0062] Other characteristics and advantages of the subject of the present disclosure will emerge from the following description of embodiments, given as non-limiting examples, with reference to the appended figures.

[0063] [Fig. 1] Figure 1 is a half-sectional view of a turbomachine.

[0064] [Fig. 2] Figure 2 is a schematic representation in a cross-sectional view including the main axis of a low pressure turbine according to a first embodiment.

[0065] [Fig. 3] Figure 3 is a schematic representation in a cross-sectional view including the main axis of a low pressure turbine according to a second embodiment.

[0066] [Fig.4] Figure 4 is a schematic representation in a cross-sectional view including the main axis of a low pressure turbine according to a third embodiment.

[0067] [Fig. 5] Figure 5 is a schematic representation in a cross-sectional view including the main axis of a low pressure turbine according to a fourth embodiment. Description of the embodiments

[0068] FIG 1 represents a turbomachine 101 in longitudinal half-section along a plane passing through its main axis A1 -A1. The turbomachine 101 is a double-spool, double-flow turbomachine, but other turbomachines can accommodate a turbine according to one embodiment.

[0069] The turbomachine 101 comprises, from upstream to downstream depending on the circulation of the air flow, a fan 102, a low-pressure compressor 103 (also called a “booster” in English), a high-pressure compressor 104, a combustion chamber 105, a high-pressure turbine 106, and a low-pressure turbine 107. These different elements are installed inside a nacelle 120, so as to obtain a propulsion assembly comprising the nacelle 120 and the turbomachine 101.

[0070] Downstream of the blower 102, the air flow is divided into a first part of the air flow (also called the primary flow) F1 passing through the low pressure compressor 103, and a second part of the air flow (also called the secondary flow) F2 flowing in bypass around the low pressure compressor 103.

[0071] The blower 102 and the low pressure compressor 103 are driven by the low pressure turbine 107 via a low pressure main shaft SL, while the high pressure compressor 104 is driven by the turbine high pressure 106 via a high pressure main shaft SH. The low pressure main shaft SL typically extends inside the high pressure main shaft SH.

[0072] The structure of the low pressure turbine 107 will be described in more detail with respect to Figure 2, the embodiments of Figures 3 to 5 will be described as variants of Figure 2.

[0073] In Figures 2 to 5, the upstream direction is symbolized by the AM mark, and the downstream direction is symbolized by the AV mark.

[0074] As shown in Figure 2, the low pressure turbine 107 comprises a casing 1, an upstream ring support 3 (or upstream support 3), a downstream ring support 4 (or downstream support 4), a sealing ring 2 and a blading 6.

[0075] The casing 1 is an annular casing having an internal surface.

[0076] The upstream support 3 and the downstream support 4 are mounted to bear against the internal surface of the annular casing 1, thus delimiting a casing segment.

[0077] The upstream support 3 and the downstream support 4 are in contact along a radial normal surface, thus facilitating the assembly and disassembly of the parts relative to each other.

[0078] The upstream support 3 may have a radial projection abutting an upstream face of the casing 1, in order to facilitate the correct relative positioning of the different parts of the casing 1 during assembly.

[0079] A blade 6 of a rotor of the turbine 107 is provided inside the casing 1, to take mechanical power from the combustion gases coming from the combustion chamber by the high pressure turbine.

[0080] The blade 6 is provided in a CMC material.

[0081] The sealing ring 2 is provided radially between the blade 6 and the casing 1.

[0082] An abradable element 11 may be provided between the sealing ring 2 and the blading 6, making it possible to ensure better control of the tolerances relative to the blading 6 and thus limit the flow rate of leaks bypassing the blading 6.

[0083] The sealing ring 2 is mounted between the upstream support 3 and the downstream support 4, bearing against the upstream support 3 and the downstream support 4.

[0084] The sealing ring 2 has a radially outermost end, at a distance R1 from the main axis.

[0085] For example, the sealing ring 2 comprises a radially projecting portion 2A, one end of which is at a radially outermost position of the sealing ring 2, at a distance R1 from the main axis.

[0086] In other words, the sealing ring 2 is included in a virtual cylinder of revolution centered on the main axis, extending axially according to positions common with the sealing ring 2 and of radius equal to the distance R1, the cylinder of revolution being tangent to the sealing ring 2 (and to the radially projecting portion 2A, if any) at the radially outermost position.

[0087] The casing 1 can thus be virtually split into an upstream half of casing 1 and a downstream half of casing 1, where the upstream half of casing 1 corresponds to a half of the casing 1 positioned upstream of the radially outermost end of the sealing ring 2, and the downstream half of casing 1 corresponds to a half of the casing 1 positioned downstream of the radially outermost end of the sealing ring 2.

[0088] A radially innermost position of the upstream half of the casing 1 is located at a distance R2 from the main axis.

[0089] In other words, a virtual cylinder of revolution centered on the main axis and of radius equal to the distance R2, extending axially according to positions common with the upstream half of the casing 1 and of radius equal to the distance R2, is included in the upstream half of the casing 1, the cylinder of revolution being tangent to the upstream half of the casing 1 at the radially innermost position of the upstream half of the casing 1.

[0090] The distances R1 and R2 are planned such that R1 <R2 (« R1 strictement inférieur à R2 »).

[0091] Thus, the turbine is dimensioned so that the maximum section of the sealing ring 2 is strictly included in any section of the casing 1 along the main axis upstream of the main axis.

[0092] In other words, it is possible to construct a virtual infinite half-cylinder containing the sealing ring 2 and extending infinitely upstream without intersecting or tangent to the upstream half of the casing 1.

[0093] In other words, the turbine is dimensioned so that the maximum radius R1 of the sealing ring 2 is strictly less than the radius R2 of the upstream end of the casing 1, the upstream end corresponding to the upstream half of the casing 1.

[0094] In this way, it is possible to move the sealing ring 2 by translation upstream without the sealing ring 2 coming into contact with the upstream part of the casing 1.

[0095] This also ensures the axial insertion mounting of the sealing ring 2 and the upstream ring support 3 against the downstream ring support 4.

[0096] The sealing ring 2 can then be dismantled from upstream and removed from inside the casing 1 by axial translation towards upstream, the various means of attachment with the other parts of the turbine, which will be described below, being previously unhooked and / or disassembled.

[0097] The upstream support 3 extends radially, and an inner surface of the upstream support 3 is in contact with an outer surface of the sealing ring 2.

[0098] The contact surface between the inner surface of the upstream support 3 and the outer surface of the sealing ring 2 may be provided between two respective ends of the upstream support 3 and the sealing ring 2. The contact surface may be a radial contact surface.

[0099] A radial surface is a surface whose normal has a non-zero radial component.

[0100] These two ends can be held against each other by a locking member 8.

[0101] The locking member 8 may for example be a C-shaped clip, that is to say a clip configured to surround the two respective ends of the sealing ring 2 and the upstream support 3 in order to keep them in contact with each other.

[0102] The contact between the inner surface of the upstream support 3 and the outer surface of the sealing ring 2 can be made by means of a sealing gasket 9.

[0103] The downstream support 4 extends radially, and an inner surface of the casing 1 is in contact with an outer surface of the downstream support 4.

[0104] The contact surface between the inner surface of the casing 1 and the outer surface of the downstream support 4 may be provided between two respective ends of the casing 1 and the downstream support 4. The contact surface may be a radial contact surface.

[0105] These two ends can be held against each other by a locking member 8, for example a C-shaped clip.

[0106] The contact between the inner surface of the casing 1 and the outer surface of the downstream support 4 can be made by means of a seal 9.

[0107] Contact between a locking member 8 and one surface of the two ends held against each other by the locking member 8 may be made by means of a sealing tab 12.

[0108] A downstream end of the sealing ring 2 is in contact with one end of the downstream support 4. The downstream end of the sealing ring 2 has a radial bearing surface on the end of the downstream support 4.

[0109] The radial surface between the sealing ring 2 and the downstream support 4 may be purely radial, i.e. radially normal, or have an inclination such that the surface moves away from the main axis in the upstream direction. In this way, the contact against the radial surface does not hinder the disassembly from the upstream side of the sealing ring 2.

[0110] As shown in Figure 2, the turbine comprises a distributor 7 which may have a first end inserted into an opening provided in the casing 1, and a second C-shaped end provided so as to enclose the downstream end of the sealing ring 2 and the end of the downstream support 4 in contact with each other.

[0111] The second end of the distributor 7 may comprise only one branch in contact with an internal surface of the downstream end of the sealing ring 2 alone, as shown in the embodiments of FIGS. 4 and 5, or in contact with an internal surface of the end of the downstream support 4 alone.

[0112] The second end of the distributor 7 may comprise only one branch in contact with a radially inner surface, for example a radially inner surface of the end of the downstream support 4 as shown in the embodiment of FIG. 3, or a radially inner surface of the end of the sealing ring 2.

[0113] The end of the downstream support 4 can grip the sealing ring 2, as shown in Figure 3. According to one example, the end of the downstream support 4 grips the sealing ring 2 so as not to hinder disassembly from the upstream side.

[0114] A seal 5 is provided between the downstream support 4 and the radially projecting portion 2A.

[0115] According to one example, the seal 5 is provided between an axial surface of the downstream support 4 and an axial surface of the radially projecting portion 2A.

[0116] An axial surface means a surface whose normal has a non-zero axial component.

[0117] According to one example, in addition or as a replacement, the seal 5 is provided between a radial surface of the downstream support 4 and a radial surface of the radially projecting portion 2A. Such additional contact allows better holding in position.

[0118] The seal 5 may for example be an omega seal, in particular an accordion-shaped seal.

[0119] The seal 5 may be in direct contact with the respective axial surfaces of the radially projecting portion 2A and the downstream support 4.

[0120] The sealing gasket 5 may also be in contact with these surfaces via sheets.

[0121] The seal 5 may be in contact with at least one of the radial surfaces among the radial surface of the downstream support 4 and the radial surface of the radially projecting portion 2A, in direct contact or via sheets.

[0122] A sheet 10 may be provided against the radially projecting portion 2A. The sheet 10 of the radially projecting portion 2A may, for example, surround the radially projecting portion 2A like a C-clip, in order to be held in position against the radially projecting portion 2A.

[0123] In addition or as a replacement, a sheet 10 may be provided against the downstream support 4. The sheet 10 of the downstream support 4 may, for example, surround a portion of the downstream support 4 like a C-clip, in order to be held in position against the downstream support 4.

[0124] The sheets 10 may be circumferential, for example non-sectored circumferential, and thus improve the sealing between the downstream support 4 and the sealing ring 2 by improving the sealing between the seal 5 and the radially projecting portion 2A and / or by improving the sealing between the seal 5 and the downstream support 4.

[0125] In the case where a sheet 10 surrounds the radially projecting portion 2A, instead of the previous definition of the distance R1 relative to the sealing ring 2 alone, the distance R1 can be defined relative to the assembly of the sealing ring 2 and the sheet mounted on the sealing ring 2.

[0126] In other words, the distance R1 can be defined at the radially outermost position of the assembly formed by the sealing ring 2 and the sheet metal 10 mounted on the sealing ring.

[0127] In this way, disassembly from the upstream side of the assembly of the sealing ring 2 and the sheet metal 10 is possible.

[0128] It is understood that the turbine 107 may be devoid of one or both of the sheets 10 between the downstream support 4 and the sealing ring 2 and between the sealing gasket 5 and the radially projecting portion 2A.

[0129] For example, in the embodiment of FIG. 3, the turbine 107 is devoid of sheet metal between the seal 5 and the radially projecting portion 2A.

[0130] In the embodiment of figures 4 and 5, the turbines 107 are devoid of sheets between the downstream support 4 and the sealing ring 2 and between the sealing gasket 5 and the radially projecting portion 2A.

[0131] The turbine 107 may also be without a seal between the sealing ring 2 and the downstream support 3.

[0132] In order to ensure sealing between the sealing ring 2 and the downstream support 4 in the absence of a seal 5, the radially projecting portion 2A may for example have a first radial contact surface with a radially inner portion of the downstream support 4, and a second radial contact surface with a radially outer portion of the downstream support 4.

[0133] In this way, the radially projecting portion 2A can grip the downstream support 4, so as to exert a force on the downstream support 4 making it possible to ensure sealing between the downstream support 4 and the sealing ring 2.

[0134] The downstream support 4 and / or the sealing ring 2 may be sectorized. Where appropriate, the number of sectors forming the downstream support 4 is strictly less than the number of sectors forming the sealing ring 2.

[0135] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Claims

1. Turbine for a turbomachine, the turbine having a main axis (X) and comprising an annular casing (1), an upstream ring support (3), a downstream ring support (4) and a sealing ring (2), the sealing ring (2) being configured to extend around and radially face a blading (6) of a rotor of the turbine, wherein the upstream ring support (3) and the downstream ring support (4) are mounted against a radially internal surface of the casing (1), the upstream ring support (3) and the downstream ring support (4) having an upstream end and a downstream end, the sealing ring (2) being configured to be arranged radially between the blading (6) and the casing (1), and being mounted against the upstream ring support (3) and the downstream ring support (4), the sealing ring (2) having a maximum radius opposite the main axis (X),and the casing (1) being dimensioned so that the maximum radius of the sealing ring (2) is strictly less than the radius of the upstream end of the casing (1) so as to allow mounting by axial insertion, of the sealing ring (2) and the upstream ring support (3), against the downstream ring support (4), the turbine comprising at least one C-shaped locking member (8) configured to hold together in contact, inside the C, an upstream end of the sealing ring (2) and the upstream ring support (3) and / or at least one C-shaped locking member (8) configured to hold together in contact, inside the C, a downstream end of the sealing ring (2) and the downstream ring support (4).,

2. Turbine for a turbomachine according to claim 1, in which the sealing ring (2) comprises a radially projecting portion (2A), the maximum radius of the sealing ring (2) being equal to the maximum radius of the radially projecting portion (2A).

3. Turbine for a turbomachine according to claim 2, comprising at least one seal (5) arranged between the downstream ring support (4) and the radially projecting portion (2A).

4. Turbine for a turbomachine according to claim 3, in which the at least one seal (5) extends axially.

5. Turbine for a turbomachine according to claim 3 or 4, comprising at least one sealing sheet (10) arranged between the seal (5) and the downstream ring support (4) and / or between the seal (5) and the radially projecting portion (2A).

6. Turbine for a turbomachine according to any one of claims 1 to 5 in which the casing (1) is a low pressure turbine casing (1).

7. A turbine according to any one of claims 1 to 6, wherein at least one of a downstream end of the sealing ring (2) and a downstream end of the downstream ring support (4) is received in a housing of an outer platform of a downstream distributor.

8. A turbine according to claim 7, wherein the housing is a groove into which the at least one end is axially inserted.

9. A turbomachine comprising the turbine according to any one of the preceding claims.

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