STATIC TURBINE ASSEMBLY

Abstract

A stator assembly for an aircraft turbomachine extending around an axis (A1) and comprising: – a sealing ring (41) including an abradable element (26) intended to cooperate with sealing blades (25) carried by a rotor, – a plurality of bladed ring sectors (30), – sliding means allowing relative movement between the sealing ring (41) and each of the ring sectors (30), the sliding means comprising two external annular flanges (45, 46), respectively upstream and downstream, of the sealing ring (41), and an internal flange of each of the ring sectors (30) which is axially interposed between the two external flanges, characterized in that each of the ring sectors (30) comprises a deflector (86) which is carried by the internal flange (40) of this sector and which extends around the upstream annular flange (45) of the sealing ring. (41). Figure for the abstract: Figure 11

Description

Title of the invention: TURBINE STATIC ASSEMBLY Technical field of the invention

[0001] The present invention relates to the field of aircraft turbomachinery and in particular to a turbine stator assembly for an aircraft turbomachine. Technical background

[0002] A conventional turbomachine turbine comprises one or more axial stages arranged in series which convert combustion energy into motive energy, in particular to drive a compressor rotor(s) and a blower shaft.

[0003] To achieve this, each stage of the turbine comprises a distributor forming a stator and a moving wheel forming a rotor. The distributor comprises fixed blades configured to accelerate and deflect a flow of combustion gases towards moving blades carried by a disc of the moving wheel.

[0004] It is known to arrange a radially positioned sealing gasket inside the distributor in order to reduce the circulation of gases outside the primary annular channel in which the fixed and moving vanes extend. Such a gasket comprises an abradable element integral with the distributor and one or more annular flaps integral with the rotor.

[0005] During turbomachine operation, the distributor is exposed to higher temperatures than the rotating wheel disc, and the distributor's thermal inertia is generally lower than that of the disc, resulting in a variation in the clearance between the abradable element and the vanes. Rotating the rotor also causes it to deform, leading to mechanical variations in rotor / stator clearance that vary according to engine speed (closer clearance during acceleration, opening clearance during deceleration).

[0006] This results in an increase in the leakage rate through the sealing joint when the aforementioned clearance increases and an acceleration of the wear of the abradable element when this clearance decreases.

[0007] Document FR-A1-3 027 343 Al discloses a mounting solution allowing radial movement between the abradable element and the distributor. To allow this type of movement, a certain mounting clearance is provided between the abradable element and the distributor.

[0008] During operation, some of the hot gases from the vein, intended to flow to the sealing joint, enter this mounting gap. Hot gases therefore flow from upstream to downstream through the mounting gap between the abradable element and The distributor is heated before being reinjected into the bore. These hot gases tend to increase the temperature of the abradable element and the distributor, which can impair the seal's operation and thus impact the turbine's performance, as well as affect the lifespan of these parts. In practice, an increase in the temperature of the abradable element (and the sealing ring that supports it) leads to an undesirable opening of the gap due to thermal expansion.

[0009] The invention aims to provide a solution to this heating problem while retaining the sealing defect between the abradable element and the distributor, which is inherent in the presence of the mounting clearance between these parts. Summary of the invention

[0010] The invention relates to a stator assembly for an aircraft turbomachine extending around an axis and comprising:

[0011] - a sealing ring extending around the axis and comprising an element abradable material designed to cooperate with sealing strips carried by a rotor mounted around the shaft

[0012] - a plurality of crown sectors arranged circumferentially end to end around the axis so as to form together a crown, each sector of the crown being winged,

[0013] - sliding means allowing a relative radial displacement vis- with respect to the axis between the sealing ring and each of the crown sectors, the sliding means comprising two external annular flanges, respectively upstream and downstream, of the sealing ring, and an internal flange of each of the crown sectors which is axially interposed between the two external flanges,

[0014] characterized in that each of the crown sectors includes a deflector which is carried by the internal flange of this sector and which extends around the upstream annular flange of the sealing ring.

[0015] In this application, the term "deflector" means a gas guiding device. When a gas flow encounters a deflector, the flow bypasses the deflector, which therefore alters its flow path.

[0016] In the present invention, the deflector modifies the flow of the gas stream originating from the duct and flowing radially inward upstream of the crown sectors, to reach the sealing joint, of which the sealing ring is a part. This gas stream flows radially inward along the inner flange of each crown sector and encounters the deflector along its path. The gas stream is then guided upstream by the deflector, allowing it to mix with the rotor cooling air. This mixing results in a decrease The temperature of the air circulating in the aforementioned mounting gap between the sealing ring and the crown sectors is significant. The temperature of the sealing ring is reduced, which allows the rotor / stator gap to close (through thermal expansion) and thus improves turbine performance.

[0017] The stator assembly according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0018] - the deflector is fixed on an upstream radial face of the internal annular flange of each of the crown sectors,

[0019] - the deflector is fixed to the internal flange of each of the crown sectors by welding, brazing or riveting,

[0020] - the deflector has in axial section a general L-shaped form, of which a first branch is oriented radially and extends parallel to the internal flange of each of the crown sectors, and a second branch of which is oriented axially upstream and extends around the upstream annular flange of the sealing ring and at least an upstream part of this sealing ring,

[0021] - said second branch includes an upstream free end which is located upstream of the sealing ring,

[0022] - the deflector is a first sheet metal,

[0023] - the assembly includes a second sheet metal which forms another deflector and which is supported by the upstream external flange of the sealing ring, and / or a third sheet metal which forms another deflector and which is supported by the downstream external flange of the sealing ring,

[0024] - the sliding means further comprise pins carried by the flanges external upstream and downstream of the sealing ring and passing through oblong openings formed in the flange of each of the crown sectors,

[0025] - the internal flange of each of the crown sectors has a radial dimension su greater than a maximum radial dimension of the sealing ring,

[0026] The present invention further relates to a turbine for an aircraft turbomachine, the turbine comprising a casing and a stator assembly as described above carried by the casing.

[0027] The stator turbine according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0028] - the turbine further comprises a rotor provided with configured annular blades to cooperate with the abradable element of the stator assembly, this rotor comprises a movable wheel located upstream of the crown sectors and comprising a disc carrying blades,

[0029] - the vanes of the moving wheel include downstream spoilers which extend at least partly around said deflector,

[0030] - the rotor includes a first ventilation air passage which has an orientation axial and which is defined by clearances between the feet of the blades and the disc, and a second ventilation air passage which has a radial orientation and which is defined by radial orifices formed upstream of said blades. Brief description of the figures

[0031] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0032] [fig. 1] [fig. 1] is a schematic axial cross-sectional view of an aircraft propulsion assembly,

[0033] [fig.2] Fig.2 is a partial schematic half-view in axial cross-section of a turbine low pressure turbomachine

[0034] [fig.3] Fig.3 is a schematic perspective view of a distributor sector of the turbine of [fig.2],

[0035] [fig-4] [fig.4] is a schematic perspective view of a ring segment forming a support for an abradable element of a turbine seal of the [fig.2],

[0036] [fig.5] [fig.5] is a schematic perspective view of a section of element annular abradable of said turbine seal of the [fig.2],

[0037] [fig.6] [fig.6] is a schematic perspective view of part of the ring of [Fig. 4], showing receiving holes for a peg,

[0038] [fig-7] [fig.7] is a schematic perspective view of a pawn intended to ensure cooperation between the crown sector of [fig.3] and the ring of [fig.4],

[0039] [fig.8] Fig.8 is a schematic perspective view of part of the turbine of the [fig.2], and in particular means of radial movement between the ring and a distributor sector,

[0040] [fig.9] Fig.9 is a partial schematic half-view in axial section of a turbine low pressure and illustrates the circulation of several gas flows,

[0041] [fig.10] Fig.10 is a schematic perspective view of a disk and a blade of a turbine wheel,

[0042] [fig.1 1] the [fig. 11] is a partial schematic half-view in axial section of a low pressure turbine and illustrates the circulation of several gas flows by means of the invention. Detailed description of the invention

[0043] The figures include a reference frame L, R and C defining respectively di- axial (or longitudinal), radial and circumferential directions orthogonal to each other.

[0044] Figure 1 shows a propulsion unit 1 of an aircraft comprising a turbomachine 2 enclosed by a nacelle 3. In this example, the turbomachine 2 is a turbomachine of the twin-body, twin-flow turbojet type.

[0045] Subsequently, the terms "upstream" and "downstream" are defined with respect to a DI direction of gas flow through the propulsion assembly 1 when it is propelled.

[0046] The turbomachine 2 has a central longitudinal axis Al around which its various components extend, in this case, from upstream to downstream, a blower 4, a low pressure compressor 5, a high pressure compressor 6, a combustion chamber 7, a high pressure turbine 8 and a low pressure turbine 9. The compressors 5 and 6, the combustion chamber 7 and the turbines 8 and 9 form a gas generator.

[0047] During the operation of the turbomachine 2, an air flow 10 enters the propulsion assembly 1 through an air inlet upstream of the nacelle 3, passes through the fan 4 and then divides into a central primary flow 10A and a secondary flow 10B.

[0048] The primary flow 10A flows in a main gas circulation channel 1IA through the gas generator. The secondary flow 10B flows in a secondary channel 1IB surrounding the gas generator and radially delimited outwards by the nacelle 3.

[0049] The low-pressure turbine 9, partially shown in [fig.2], is configured to recover part of the combustion energy in order to drive in rotation around the axis Al movable wheels forming the rotor of the turbine 9. Between each pair of adjacent movable wheels, the turbine 9 includes a bladed stator ring forming a distributor.

[0050] Fig. 2 shows part of two movable wheels 15 and 16, of a distributor 17 and of a sealing joint 18 of the turbine 9.

[0051] The distributor 17 extends axially between the movable wheel 15, which forms an upstream wheel, and the movable wheel 16, which forms a downstream wheel.

[0052] In a manner known per se, each of the movable wheels 15 and 16 comprises a disc 20 and blades 21 carried by the disc 20.

[0053] In this example, the disc 20 of the upstream wheel 15 includes a ferrule 22 extending axially towards the downstream wheel 16, radially inside the distributor 17. A downstream end of the ferrule 22 is connected to the disc 20 of the downstream wheel 16 so as to lock the wheels 15 and 16 together in rotation about the axis AL

[0054] The sealing joint 18 is formed on the one hand by annular lugs 25 carried by the ferrule 22 and, on the other hand, by an abradable element 26, or wear part, connected to the distributor 17.

[0055] During the operation of the turbomachine 2, the movable wheels 15 and 16 are driven in rotation around the axis Al, and the blades 25 thus rotate in relation to the abradable element 26. The seal 18 thus ensures a seal which reduces the circulation of gas outside the main stream 11 A, in this case radially between the distributor 17 and the ferrule 22.

[0056] The distributor 17 in this example comprises several sectors 30 arranged circumferentially end to end so as to form together a bladed crown.

[0057] Fig. 3 shows one of these crown sectors 30. In this example, all the crown sectors 30 of the distributor 17 are identical so that the following description, which relates to the crown sector 30 of Fig. 3, applies to each of the other crown sectors.

[0058] With reference to figures 2 and 3, the crown sector 30 comprises an inner platform 31, an outer platform 32 and blades 33.

[0059] The blades 33 are each connected on one side to the internal platform 31 and on the other side to the external platform 32 so as to extend radially through the main vein 1 IA, which is radially delimited by these platforms 31 and 32.

[0060] The blades 33 of the crown sector 30 are circumferentially spaced from each other. The external platform 32 is configured to be fixed on a housing 35 of the turbomachine 2.

[0061] The crown sector 30 includes a flange 40 connected to the internal platform 31 so as to extend radially inwards from the internal platform 31, in the direction of the ferrule 22.

[0062] The flange 40 is configured to cooperate with a sealing ring 4L

[0063] Fig. 4 shows a circumferential section of ring 41, it being understood that this forms an annular crown.

[0064] In this example, the ring 41 is a part carrying the abradable element 26, which also forms an annular ring.

[0065] With reference to figures 4 and 5, which respectively show a circumferential section of the ring 41 and a corresponding circumferential section of the abradable element 26, the ring 41 includes for this purpose a platform 42 defining an internal surface 43 on which the abradable element 26 is fixed according to the configuration of [fig.2],

[0066] The ring 41 further comprises an upstream annular flange 45 and a downstream annular flange 46 extending radially outwards from the platform 42.

[0067] With reference to figures 2, 4, 6 and 8, the flanges 45 and 46 are substantially parallel and axially spaced from each other so as to form a U-shaped section defining a space into which the flange 40 of each of the crown sectors 30 can be inserted.

[0068] The axial distance between flanges 45 and 46 is chosen to allow for proper axial positioning and axial retention of the crown sectors 30, while also permitting its movement by radial sliding of the flange 40 between flanges 45 and 46 (see below). In particular, an axial clearance J1, J2 is left during assembly between flanges 40, 45, and 46 to allow this radial movement (see [Fig. 8]). The clearance J1 extends between flanges 45 and 40, and the clearance J2 extends between flanges 40 and 46.

[0069] Furthermore, the flange 40 is mounted with a radial clearance J3 relative to the bottom of the space defined by the flanges 45, 46.

[0070] Figure 6 shows two orifices 51 and 52 made respectively in the upstream flange 45 and the downstream flange 46 of the ring 4L

[0071] The ports 51 and 52 have a common axis A2 and are designed to receive a pin 60 such as that shown in [fig.7]. The pin 60 is a cylindrical part with axis A2 having two shoulders which define an upstream part 61, an intermediate part 62 and a downstream part 63.

[0072] The intermediate part 62 has a diameter smaller than the diameter of the upstream part 61 and the downstream part 63. The diameter of the upstream part 61 is also smaller than that of the downstream part 63.

[0073] The orifice 51 of the upstream flange 45 of the ring 41 is sized to receive the upstream portion 61 of the pin 60 so as to form a tight fit. Similarly, the orifice 52 of the downstream flange 46 of the ring 41 is sized to receive the downstream portion 63 of the pin 60 so as to form a tight fit.

[0074] After assembly, the pin 60 is thus carried by the ring 41, forming a complete connection with it.

[0075] The pin 60 is configured to cooperate with the distributor 17, in particular with the flange 40 of the crown sector 30.

[0076] With reference to figures 3 and 8, the flange 40 of each of the crown sectors 30 includes for this purpose an opening 70 which has an oblong shape of the radially extending groove type.

[0077] In this example, the opening 70 opens radially towards the interior of the crown sector 30.

[0078] The opening 70 has a width, or circumferential dimension, allowing it to be crossed by the intermediate part 62 of the pin 60, that is to say a width greater than the diameter of the intermediate part 62 of the pin 60.

[0079] The width of the opening 70 is also less than the diameter of the upstream part 61 and the downstream part 63 of the pin 60. Thus, in the event of a break in the connection between the pin 60 and the ring 41, the flange 40 of the crown sector 30 forms an axial stop to retain the pin 60.

[0080] By contrast with the rotor of the turbine 9, the parts of which are rotating around the axis Al, the assembly formed by the ring 41, the abradable element 26, the crown sector 30 and the pin 60 belong to the stator of the turbine 9.

[0081] The assembly of this stator element includes a pre-insertion of the pin 60 into the ring 41 by passing the upstream part 61 of the pin 60 through the orifice 52 of the downstream flange 46.

[0082] The pin 60 is then fixed to the ring 41 by forcibly inserting its upstream part 61 into the orifice 51 of the upstream flange 45 and, simultaneously, its downstream part 63 into the orifice 52 of the downstream flange 46.

[0083] The crown sector 30 is then moved radially inwards so as to introduce the flange 40 axially between the flanges 45 and 46 of the ring 41 and to insert the intermediate part 62 of the pin 60 into the opening 70 of the flange 40.

[0084] These assembly steps lead to the configuration illustrated in figures 2 and 8.

[0085] In this configuration, the pin 60 forms, on the one hand, a circumferential stop for the crown sector 30, preventing the ring 41 and the crown sector 30 from moving relative to each other during rotation about the axis Al, and allowing the ring 41 to be centered with respect to this axis AL

[0086] On the other hand, taking into account the respective dimensions of the intermediate part 62 of the pin 60 and the oblong opening 70, the assembly allows a radial displacement of the ring 41 relative to the crown sector 30.

[0087] The stator assembly may include other pins similar to pin 60, each cooperating with the flange 40 of one of the respective other crown sectors 30 according to the principles described above.

[0088] Of course, these principles can be generalized. For example, each of the crown sectors 30 of the distributor 17 can cooperate with several pawns similar to pawn 60.

[0089] In general, the invention makes it possible to connect the sealing ring 41 and the distributor 17 to each other according to a connection defining a radial degree of freedom capable of compensating for differential thermal expansions within the turbine 9.

[0090] The radial clearance between the blades 25 and the abradable element 26 can thus be kept substantially constant during the operation of the turbojet 2, which improves the sealing provided by the sealing gasket 18.

[0091] The forced mounting of the pins 60 in the orifices 51 and 52 of the ring 41 contributes to the reduction of gas leaks outside the main vein 11 A.

[0092] Fig. 9 is a larger scale view of a sealing ring 41 in its mounting environment.

[0093] The crown sector 30 shown in this [fig.9] includes grooves 90 formed in the flange 40 and in the platform 31. These grooves 90 are configured To receive a first set of sealing plates, a second set of these plates is housed in similar grooves 90 made in an adjacent ring sector 30, so that the sealing plates extend circumferentially between these ring sectors 30 and close the circumferential space they define between them. Such sealing plates can be arranged according to this principle so as to extend circumferentially between each pair of adjacent ring sectors and thus improve the sealing of the assembly.

[0094] Fig. 9 also allows visualization of the gas flow circuits.

[0095] A first circuit Cl represents a portion of the gases from the vein 1 IA which passes radially inwards, between the upstream wheel 15 and the platform 31 of each of the ring sectors 30. These gases are intended to flow radially inwards, between the upstream wheel 15 and the sealing ring 41, up to the scrapers 25. For this purpose, a deflector 80 formed by a sheet can be fixed on the sealing ring 41 and in particular on its upstream flange, to guide these gases so that they bypass the abradable element 26.

[0096] However, in practice, due to the presence of the mounting clearance J1, J2, some of these gases (Cl') pass through the flanges 40, 45, 46 and arrive directly downstream of the distributor sectors, without passing through the seal. These gases are then reinjected directly into the vein 11 A.

[0097] A second circuit C2 represents ventilation air that passes through mounting gaps provided between the feet 21a of the blades 21 and the recesses 20a of the disc 20 of the upstream wheel 15 (see [Fig. 10]). Each blade comprises a foot 21a which is connected to the blade 21b by a platform 21c. This platform 21c extends upstream of the platform 31 of the distributor sector 30 located downstream and includes a downstream spoiler 21d. The downstream spoiler 21d extends axially downstream and its downstream end is radially interposed between the upstream end of the platform of each of the distributor sectors 30 and the upstream end of the deflector 80.

[0098] The disc 20 of the wheel 15 comprises on its outer periphery a series of recesses 20a, each of which receives the foot 21a of a blade 21. The feet 21a of the blades 21 are fitted into the recesses 20a by male-female engagement, and clearances remain between the feet 21a and the walls of the recesses 20a, in particular between the radially inner end of each foot and the bottom of the corresponding recess. These clearances allow the passage of ventilation air, axially from upstream to downstream of the wheel, to form the circuit C2.

[0099] A third circuit C3 represents ventilation air which passes through radial through orifices 82 provided in the ferrule 22, upstream of the nozzles 25.

[0100] The various gases from circuits Cl, C2, C3 join upstream of the nozzles and are intended to supply the seal formed by the nozzles 25 and the element abradable 26. These gases pass axially through this joint and are found downstream of the sealing ring (C4 circuit).

[0101] A deflector 84 formed by a sheet metal can be fixed on the sealing ring 41 and in particular on its downstream flange 46, to guide these gases so that they join the vein 11 A.

[0102] As is the case with the upstream wheel 15, the blades 21 of the downstream wheel 16 each comprise a foot 21a which is connected to the blade 21b of the blade by a platform 21c. This platform 21c extends downstream of the platform 31 of the upstream distributor sector 30 and comprises an upstream spoiler 21e. The upstream spoiler 21e extends axially upstream and its upstream end is radially interposed between the downstream end of the platform 31 of each of the distributor sectors 30 and the downstream end of the deflector 84.

[0103] The present invention proposes a solution to prevent the mounting clearance Jl, J2 from being detrimental to the circulation of gases in this environment and negatively impacting the operation of the seal and the performance of the turbomachine.

[0104] Fig. 11 illustrates a preferred embodiment of the invention.

[0105] According to the invention, each of the crown sectors 30 comprises a deflector 86 which is carried by the internal flange 40 of this sector and extends around the upstream flange 45 of the sealing ring 4L

[0106] In the example shown, the deflector 86 is fixed to an upstream radial face 40a of the internal flange 40 of each of the crown sectors 30. The deflector 86 can be fixed there by welding, brazing or mechanical connection (by screws or rivets for example).

[0107] As is the case with the crown sectors 30, the deflectors 86 carried by the crown sectors together have a general annular shape. Taken individually, they have a general curved or arc-shaped shape whose axis of revolution can be considered to coincide with the axis Al of the turbine.

[0108] As can be seen in the drawing, each deflector 86 has in axial section a general L-shape of which a first branch 86a is oriented radially and extends parallel to the internal flange 40 of each of the crown sectors 30, and of which a second branch 86b is oriented axially upstream and extends around the upstream flange 45 of the sealing ring 41 and at least an upstream part of this sealing ring 4L. Due to the curved shape of the deflector 86, this second branch 86b has a general cylindrical or part-of-a-cylinder shape.

[0109] This second branch 86b preferably comprises a free upstream end 86ba which is located:

[0110] - upstream of the sealing ring 41, and / or

[0111] - upstream of the downstream end of the spoiler 21d, and / or

[0112] - substantially opposite the upstream end of platform 31 in the sector of 30 crown corresponding.

[0113] As with the other two deflectors 80 and 84 described above, the deflector 86 can be formed from a sheet of metal. The deflectors 80 and 86 and their sheets can be similar or identical and, in particular, oriented in the same way, with their radial arms extending upwards. The deflector 84 can be oriented in a different position, with its radial arm directed inwards. The radial arms 80a and 84a of the deflectors 80 and 84 are fixed respectively to an upstream face of the upstream flange 45 and to a downstream face of the downstream flange 46.

[0114] The axial branch 80b of the deflector 80 preferably comprises an upstream free end 80ba which is located:

[0115] - upstream of the sealing ring 41, and / or

[0116] - upstream of the downstream end of the spoiler 21d, and / or

[0117] - substantially opposite the upstream end of platform 31 in the sector of corresponding 30 crown, and / or

[0118] - upstream or opposite the end 86ba of the deflector 86.

[0119] The axial branch 84b of the deflector 84 preferably comprises a downstream free end 84ba which is located:

[0120] - downstream of the sealing ring 41, and / or

[0121] - downstream of the upstream end of the 21st spur, and / or

[0122] - downstream of the downstream end of platform 31 of crown sector 30 cor respondent.

[0123] By comparing figures 9 and 11, it can be seen that the internal flange 40 of each of the crown sectors 30 of [fig.11] has a relatively large radial dimension RI and greater than a maximum radial dimension R2 of the sealing ring 41 (which is not the case in [fig.9]).

[0124] As can be seen in [fig.l 1], the gases of the first circuit Cl are deflected by the deflector 86 and are found upstream of the sealing ring 4L. Due to the presence of this additional deflector 86 and especially its position, the temperature of the air passing through the circuit Cl' is reduced by a mixing effect with the cooling air of the circuit C2.

[0125] Almost all of the gases from circuit Cl are therefore found upstream of the nozzles with the ventilation air from circuits C2 and C3. These gases pass axially through the seal, are found downstream of the sealing ring (circuit C4), then are reinjected into the vein 11 A.

[0126] As is the case with the upstream wheel 15, the blades 21 of the downstream wheel 16 each comprise a foot 21a which is connected to the blade 21b of the blade by a platform 21c. This platform 21c extends downstream of the platform 31 of the distributor sector 30 located upstream and comprises an upstream spoiler 21e. The upstream spoiler 21e extends axially upstream and its upstream end is radially interposed between the downstream end of platform 31 of each of the distributor sectors 30 and the downstream end of the deflector 84.

Claims

Claims

1. Stator assembly for an aircraft turbomachine extending around an axis (Al) and comprising: - a sealing ring (41) extending around the axis (Al) and comprising an abradable element (26) intended to cooperate with sealing lips (25) carried by a rotor mounted around the axis (Al), - a plurality of crown sectors (30) arranged circumferentially end to end around the axis (Al) so as to form together a crown, each crown sector (30) being bladed, - sliding means allowing relative displacement radially with respect to the axis (Al) between the sealing ring (41) and each of the crown sectors (30), the sliding means comprising two external annular flanges (45, 46), respectively upstream and downstream, of the sealing ring (41), and an internal flange of each of the crown sectors (30) which is axially interposed between the two external flanges,characterized in that each of the crown sectors (30) comprises a deflector (86) which is carried by the internal flange (40) of this sector and which extends around the upstream annular flange (45) of the sealing ring (41).,

2. Assembly according to claim 1, in which the deflector (86) is fixed on an upstream radial face (40a) of the internal annular flange (40) of each of the crown sectors (30).

3. An assembly according to claim 1 or 2, wherein the deflector (86) is fixed to the internal flange (40) of each of the crown sectors (30) by welding, brazing or riveting.

4. Assembly according to one of the preceding claims, in which the deflector (86) has a general L-shape in axial section, a first branch (86a) of which is oriented radially and extends parallel to the internal flange (40) of each of the crown sectors (30), and a second branch (86b) of which is oriented axially upstream and extends around the upstream annular flange (45) of the sealing ring (41) and at least one upstream portion of this sealing ring (41).

5. Assembly according to the preceding claim, in which said second branch (80b) comprises an upstream free end (86ba) which is located upstream of the sealing ring (41).

6. Assembly according to one of the preceding claims, in which the deflector (86) is a first sheet metal.

7. Assembly according to the preceding claim, in which it comprises a second sheet which forms another deflector (80) and which is carried by the upstream external flange (45) of the sealing ring (41), and / or a third sheet which forms another deflector (84) and which is carried by the downstream external flange (46) of the sealing ring (41).

8. Assembly according to the preceding claim, in which the sliding means further comprise pins (60) carried by the upstream and downstream external flanges (45, 46) of the sealing ring (41) and passing through oblong openings (70) formed in the flange of each of the crown sectors (30).

9. Assembly according to one of the preceding claims, in which the internal flange (40) of each of the crown sectors (30) has a radial dimension (RI) greater than a maximum radial dimension (R2) of the sealing ring (41).

10. Turbine (9) for an aircraft turbomachine, this turbine comprising a casing (35) and a stator assembly according to any one of the preceding claims carried by the casing.

11. Turbine (9) according to the preceding claim, further comprising a rotor provided with annular wipers (25) configured to cooperate with the abradable element (26) of the stator assembly, this rotor comprising a mobile wheel (15) located upstream of the crown sectors (30) and comprising a disc (20) carrying blades (21).

12. Turbine (9) according to the preceding claim, in which the blades (21) of the moving wheel (15) comprise downstream spoilers (21d) which extend at least partly around said deflector (86).

13. Turbine (9) according to the preceding claim, in which the rotor comprises a first ventilation air passage which has an axial orientation and which is defined by clearances between roots (21a) of the blades (21) and the disc (20), and a second ventilation air passage which has a radial orientation and which is defined by radial orifices (82) formed upstream of said wipers (25).

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