SECTOR OF A RING FOR A TURBINE OF AN AIRCRAFT TURBOMACHINE

Abstract

A sector (16) of a ring (15) for a turbine (1) of an aircraft turbomachine (2), the sector (16) being circular about a longitudinal axis (X), the sector (16) comprising a body (17) having an inner face (18) on which an abradable layer (19) is applied, the abradable layer (19) being intended to be opposite at least one crest (11) of a blade (9) of a rotating wheel (5), characterized in that the body (17) comprises an upstream rim (20) projecting radially towards the axis (X) and extending beyond the abradable layer (19), the rim (20) being intended to radially cover the crest (11) of the blade (9), the sector (16) further comprising a first internal air circuit (21) which includes at least one duct (22a-22d) opening onto the upstream rim (20) and / or on the abradable layer (19), the duct (22a-22d) being oriented so that the air jet (J1) from the duct (22a-22d) is projected onto the apex (11) of the blade (9). Figure for the abbreviation: 2

Description

Title of the invention: SECTOR OF A RING FOR A TURBINE OF AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to a sector of a ring for a turbine of an aircraft turbomachine, as well as to a ring formed by such sectors, but also to a turbine comprising such a ring, and finally to a turbomachine comprising such a turbine. Technical background

[0002] Classically, an axial turbine of a turbomachine comprises one or more axial stages arranged one behind the other, each stage comprising a bladed distributor (stator) and a bladed moving wheel (rotor).

[0003] A movable wheel comprises a disc carrying an annular row of blades.

[0004] In the remainder of this application, we will focus on blades described as "without a heel". A blade described as "without a heel" comprises a blade with a summit at its free outer end. Conversely, a blade described as "with a heel" comprises a blade with an outer end attached to a heel, this heel generally being equipped with one or more blade tips.

[0005] In order to optimize the efficiency of a turbine, it is necessary to maximize the amount of exhaust gas acting on the different blades.

[0006] For this purpose, it is known to implant a sectorized ring around the moving wheel, this ring being fixed to a turbine housing. The ring has an abradable layer (for example a metallic or ceramic layer with a honeycomb structure) which is positioned opposite the tips of the blades and which is intended to cooperate with these tips to form a dynamic labyrinth-type seal.

[0007] Based on experience, engine manufacturers have observed premature wear of the blade tip, which is largely explained by a locally higher temperature of the tip, this temperature being able to reach 1200°C.

[0008] This locally higher temperature is the cause of various harmful phenomena for the summit, namely corrosion, oxidation, burns and cracks.

[0009] Engine manufacturers are thus mobilized to find solutions to lower the temperature of the top of the blade, and consequently to maximize the lifespan of the blade.

[0010] The objective of the present invention is therefore to provide a simple, effective solution and economical, enabling a solution to the aforementioned problem. Summary of the invention

[0011] The invention thus proposes a sector of a ring for a turbine of an aircraft turbine machine, the sector being circular around a longitudinal axis X, the sector comprising a body having an inner face on which an abradable layer is applied, the abradable layer being intended to be opposite at least one crest of a blade of a moving wheel, characterized in that the body comprises an upstream rim which projects radially towards the axis X and which exceeds the abradable layer, the rim being intended to radially cover the crest of the blade, the sector further comprising a first internal air circuit which includes at least one conduit opening onto the upstream rim and / or onto the abradable layer, the conduit being oriented so that the air jet from the conduit is projected onto the crest of the blade.

[0012] The upstream rim and the air jet from the duct (first air circuit) make it possible to significantly lower the temperature of the top of the blade, and consequently to maximize the lifespan of the blade.

[0013] Indeed, the upstream rim forms a protection or a deflector which diverts the exhaust gases heading towards the peaks, so as to prevent the exhaust gases from coming into direct contact with the peaks.

[0014] Furthermore, the air jet from the duct (first air circuit) directly impacts the The tips of the blades are designed to maximize their cooling. Furthermore, the air jet from the duct forms a layer of cold air (or a cold air curtain) between the tips and the ring, which not only contributes to cooling the tips of the blades, but also forms a barrier (or obstacle) preventing the hot exhaust gases from rising.

[0015] The cold air layer also makes it possible to relax certain dimensional requirements that were associated with obtaining the functional clearance (particularly precise) between the vertices and the abradable layer of the ring.

[0016] The layer of cold air finally forms an additional seal between the peaks and the ring, regardless of the operating regime of the turbine, to the benefit of its efficiency.

[0017] The sector according to the invention may comprise one or more of the following features, taken individually or in combination with each other: - the sector includes a second internal air circuit which is independent of the first internal air circuit, the second air circuit having at least one passage opening onto the abradable layer, the passage being oriented so that the jet of air from the passage is projected onto the top of the blade; - the duct and the passage are each defined by an air inlet and an air outlet, the duct and the passage each extending from upstream to downstream from their air inlet to their air outlet; - the passage is fed by a recess which is formed in the body of the sector and which is open to the outside, the sector also comprising a perforated sheet metal which covers the recess; - the rim has an upstream end which has in cross section a face inclined with respect to the X axis, the radial dimension of the inclined face decreasing from upstream to downstream, so as to deflect the exhaust gases in the direction of the X axis; - the first air circuit comprises several ducts which each open onto the upstream rim and / or onto the abradable layer, each duct being oriented so that the corresponding jet of air is projected onto the top of the blade, the ducts being supplied by a common chamber which is formed in the body; - the sector includes several first air circuits distributed around the X axis, the first air circuits preferably being distributed regularly.

[0018] The present invention also relates to a ring for a turbine of an aircraft turbomachine, the ring comprising a plurality of sectors as described above, the sectors being arranged end to end around the X axis.

[0019] The present invention further relates to a turbine of an aircraft turbomachine comprising a ring as described above and a movable wheel disposed inside the ring, the movable wheel comprising a disk carrying an annular row of blades, each blade comprising a blade which has a vertex at its free external end, the abradable layers of the different sectors of the ring being opposite the vertices of the blades.

[0020] The present invention finally relates to an aircraft turbomachine comprising a turbine as described above. Brief description of the figures

[0021] The invention will be better understood and other details, features and advantages of the invention will become more apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

[0022] [Fig-1] [Fig.1] is a schematic and partial view in a longitudinal half-section of a turbine of an aircraft turbomachine according to the invention;

[0023] [Fig.2] [Fig.2] is a detail view of [Fig.1];

[0024] [Fig.3] [Fig.3] corresponds to [Fig.2] on which the path of cooling air through a sector of a turbine ring;

[0025] [Fig.4] [Fig.4] is a perspective view of a sector of the turbine ring. Detailed description of the invention

[0026] Figures 1 and 2 show a portion of a high-pressure turbine 1 (hereinafter referred to as the "turbine") of a turbomachine 2. The turbine 1 is part of a gas generator which also includes a compressor and a combustion chamber. More specifically, the turbine 1 is positioned directly downstream of the combustion chamber, and is thus particularly exposed to high temperatures.

[0027] The turbine 1 comprises at least one stage including a bladed distributor 3 which is integral with a housing 4 of the turbine 1 and a bladed wheel 5 which is free to rotate about a longitudinal axis X of the turbine 1 (common with the longitudinal axis of the turbomachine). The bladed wheel 5 is located downstream of the bladed distributor 3.

[0028] The bladed distributor 3 comprises an annular row of rectifier blades 6. The rectifier blades 6 are arranged between external and internal platforms 7, 47 which define the turbine channel 8 into which the exhaust gases G from the combustion chamber flow. The bladed distributor 3 is preferably sectored, each sector comprising, for example, two or three rectifier blades 6.

[0029] The movable wheel 5 includes a disc 48 carrying an annular row of blades 9. A blade 9 includes a foot 49 mounted in a recess 50 of the disc 48 and a blade 10 which has a summit 11 at its free outer end.

[0030] More specifically, the blade 10 of the blade 9 extends along a stacking axis Z which is substantially perpendicular to the axis X. The blade 10 has an intrados face 12 and an extrados face connected to each other by a leading edge 13 and a trailing edge 14. The exhaust gases G flow around the blade 10 from the leading edge 13 towards the trailing edge 14, the leading edge 13 being thus positioned upstream of the trailing edge 14 in the direction of flow of the exhaust gases G.

[0031] Advantageously, each blade 9 includes an internal cooling circuit. The internal cooling circuit may, for example, include one or more inlets located at the base 49 of the blade 9 and outlets located along the trailing edge 14 of the blade 10.

[0032] The movable wheel 5 is arranged inside a sectorized ring 15 which is integral with the housing 4. The ring 15 thus comprises a plurality of sectors 16 arranged end to end around the axis X.

[0033] Advantageously, sealing means (for example, strips and / or plates) are arranged between sectors 16 to minimize inter-sector leakage.

[0034] Each sector 16 of the ring 15 is circular around the longitudinal axis X. Each sector 16 comprises a body 17 having an inner face 18 on which an abradable layer 19 is applied. The abradable layer 19 is opposite the vertices 11 of the blades 9 surrounded by the sector 16.

[0035] According to the invention, the body 17 of each sector 16 includes an upstream rim 20 which projects radially towards the X axis and which extends beyond the abradable layer 19, the rim 20 radially covering the apexes 11 of the blades 9 surrounded by the sector 16. Each sector 16 further includes a first internal air circuit 21 which includes at least one conduit 22a-22d opening onto the upstream rim 20 and / or onto the abradable layer 19, the conduit 22a-22d being oriented so that the air jet J1 from the conduit 22a-22d is projected onto the apexes 11 of the blades 9.

[0036] The upstream rim and the air jet from the duct (first air circuit) make it possible to significantly lower the temperature of the top of the blade, and consequently to maximize the lifespan of the blade.

[0037] Indeed, the upstream rim forms a protection or a deflector which diverts the exhaust gases heading towards the peaks, so as to prevent the exhaust gases from coming into direct contact with the peaks.

[0038] Furthermore, the air jet from the duct (first air circuit) directly impacts the tips of the blades to maximize their cooling. Moreover, the air jet from the duct forms a layer of cold air (or a cold air curtain) between the tips and the ring, which not only contributes to cooling the tips of the blades but also forms a barrier (or obstacle) preventing the upward flow of hot exhaust gases.

[0039] The cold air layer also makes it possible to relax certain dimensional requirements that were associated with obtaining the functional clearance (particularly precise) between the vertices and the abradable layer of the ring.

[0040] The layer of cold air finally forms an additional seal between the peaks and the ring, regardless of the operating regime of the turbine, to the benefit of its efficiency.

[0041] In the same way as the turbine 1 or the turbomachine 2, a sector 16 of the ring 15 is defined with respect to the longitudinal axis X.

[0042] In the present application, the terms "internal" and "external" are defined with respect to the longitudinal axis X.

[0043] In the present application, the term "interior" associated with an element of sector 16 indicates that this element is located inside sector 16. Conversely, the term "exterior" associated with an element of sector 16 indicates that this element is located outside sector 16.

[0044] Furthermore, in the present application, the terms "upstream" and "downstream" are defined with respect to the direction of exhaust gas flow G.

[0045] The abradable layers of the different sectors 16 of the ring 15 are opposite the abradable layers of the various sectors 16 of the ring 15. The abradable layers are intended to cooperate with the abradable layers of the abradable layers of the type 1- byrinth.

[0046] The abradable layer 19 of a sector 16 may have a constant or variable thickness. The abradable layer 19 may also be stepped.

[0047] The abradable layer 19 can, for example, be a metallic or ceramic layer with a honeycomb structure.

[0048] The rim 20 extends beyond the abradable layer 19, and in other words the rim 20 extends radially beyond the abradable layer 19, so as to radially cover the apexes 11 of the blades 9 surrounded by the sector 16.

[0049] The rim 20 may have an upstream end which has in cross section a face inclined 23 with respect to the axis X, the radial dimension of the inclined face 23 decreasing from upstream to downstream, so as to deflect the exhaust gases G in the direction of the axis X. Such an inclination of the upstream end makes it possible to limit the disturbances.

[0050] Advantageously, the inclined face 23 of the upstream end is in line with the external platform 7 of the distributor 3, to ensure aerodynamic continuity, and thus minimize disturbances.

[0051] The first internal air circuit 21 (hereinafter referred to as "first circuit") of each sector 16 can obviously include several conduits 22a-22d which each open onto the upstream rim 20 and / or onto the abradable layer 19. Each conduit 22a-22d is oriented so that the corresponding air jet J1 is projected onto the tips 11 of the blades 9.

[0052] Advantageously, the conduits 22a-22d are supplied by a common chamber 24 which is formed in the body 17 of the sector 16. The conduits 22a-22d are connected directly or indirectly to the chamber 24.

[0053] Advantageously, the first circuit 21 includes at least one conduit 22c, 22d which opens onto the upstream rim 20.

[0054] Each duct 22a-22d is defined by an air inlet 25, an air outlet 26 and an elongation axis.

[0055] By way of example, a conduit 22a-22d can be of circular, rectangular, etc. cross-section.

[0056] A conduit 22a-22d may have a constant or variable cross-section along its axis of elongation.

[0057] Advantageously, when a conduit 22a-22d has a variable cross-section, its section converges from its air inlet 25 to its air outlet 26, so as to increase the speed of the corresponding air jet J1, and thus increase the cooling of the peaks 11.

[0058] A conduit 22a-22d can extend parallel to the X axis (its axis (elongation being then parallel to the X-axis) or inclined with respect to the axis X (its elongation axis being then inclined with respect to the X axis).

[0059] Advantageously, each conduit 22a-22d extends from upstream to downstream, with reference to the direction of exhaust gas flow G, from its air inlet 25 to its air outlet 26. Such an orientation of the duct(s) 22a-22d allows air jets J1 to be directed along the direction of exhaust gas flow G, so as to minimize disturbances.

[0060] Each sector 16 can include several first circuits 21 distributed around the X axis.

[0061] Advantageously, the first circuits 21 are distributed in a regular manner.

[0062] The first circuits 21 can be arranged in the form of a row around the X axis.

[0063] Advantageously, the first circuit(s) 21 are supplied with compressed air from, for example, the compressor of the gas generator.

[0064] Each sector 16 may include a second internal air circuit 27 (hereinafter referred to as "second circuit") which is independent of the first circuit 21.

[0065] The second circuit 27 may include one or more passages 28 each opening onto the abradable layer 19. Each passage 28 is oriented so that the corresponding air jet J2 is projected onto the apexes 11 of the blades 9.

[0066] The passage(s) 28 of a sector 16 can be supplied by a recess 29 which is formed in the body 17 of the sector 16 and which is open to the outside.

[0067] Each sector 16 may further include a perforated sheet 30 which covers the recess 29, in particular to regulate the temperature of the body 17.

[0068] In the same way as a duct 22a-22d, each passage 28 is defined by an air inlet 25, an air outlet 26 and an axis of extension.

[0069] By way of example, a passage 28 may have a circular, rectangular, etc. cross-section.

[0070] A passage 28 may have a constant or variable cross-section along its elongation axis.

[0071] Advantageously, when a passage 28 has a variable section, its section converges from its air inlet 25 to its air outlet 26, so as to increase the speed of the corresponding air jet J2, and thus increase the cooling of the peaks 11.

[0072] Advantageously, each passage 28 extends from upstream to downstream, with reference to the direction of exhaust gas flow G, from its air inlet 25 to its air outlet 26. Such an orientation of the passage(s) 28 allows air jets J2 to be directed along the direction of exhaust gas flow G, so as to minimize disturbances.

[0073] Advantageously, the second circuit 27 is supplied with compressed air from, for example, the compressor of the gas generator.

[0074] According to the embodiment illustrated in figures 1 to 4, each sector 16 is in the form of an arc of a circle around the X axis.

[0075] As illustrated in figures 1 to 3, each sector 16 includes an upstream groove 31 in which is housed an upstream hook 32 of the housing 4 and a downstream tab 33 which is secured to a downstream hook 34 of the housing 4 via a retaining element 35. The retaining element 35 has a U-shaped cross-section.

[0076] As illustrated in Figures 1 to 3, the rim 20 of each sector 16 is arranged upstream of the abradable layer 19. The rim 20 thus radially covers the apexes 11 of the blades 9 surrounded by the sector 16.

[0077] The rim 20 is defined in particular by an upstream edge 36, a first face 23, a second face 37 and a downstream edge 38.

[0078] More specifically, the upstream edge 36 is in straight and radial cross-section.

[0079] The first face 23 (hereinafter referred to as the "inclined face") has an inclined cross-section with respect to the X axis. The radial dimension of the inclined face 23 decreases from upstream to downstream, so as to deflect the exhaust gases G in the direction of the X axis.

[0080] The inclined face 23 is located here in the extension of the external platform 7 of the distributor 3, to minimize disturbances.

[0081] The second face 37 is in right and axial cross section (i.e. along the X axis).

[0082] The downstream edge 38 has a straight and radial cross-section. The downstream edge 38 is located opposite the leading edge 13 of the blade 10 at its apex 11.

[0083] As illustrated in the figures, the abradable layer 19 of each sector 16 here has a constant thickness.

[0084] As illustrated in [Fig. 4], each sector 16 comprises a row of first circuits 21 distributed regularly around the X-axis. Each sector 16 also comprises a single second circuit 27.

[0085] The first and second circuits 21, 27 are supplied with compressed air (cooling air or cold air) which is conveyed to a chamber 39 defined radially between the casing 4 and the ring 15. The compressed air here comes from a compressor of the turbomachine 2.

[0086] As illustrated in [Fig. 4], the second circuit 27 comprises three rows of four passages 28. The passages 28 in each row are distributed regularly around the X-axis. Each passage 28 opens onto the abradable layer 19, and more precisely onto the internal surface 40 of the abradable layer 19.

[0087] As illustrated in [Fig. 3], the passages 28 are oriented so that the air jets J2 corresponding are projected onto the vertices 11 of the blades 9.

[0088] As illustrated in Figures 1 to 3, the passages 28 each extend in a way inclined with respect to the X axis.

[0089] The passages 28 each extend from upstream to downstream, with reference to the direction of flow of the exhaust gases G, from their air inlet 25 to their air outlet 26.

[0090] The passages 28 each extend radially from the outside to the inside from their air inlet 25 to their air outlet 26.

[0091] The passages 28 are fed by a central recess 29 formed in the body 17 of the sector 16 and open to the outside. The recess 29 is defined in particular by a bottom wall 41 and an upstream side wall 42 of the body 17. The passages 28 are partly formed in the bottom wall 41 of the body 17 and partly in the abradable layer 19.

[0092] A perforated sheet metal 30 covers the recess 29. The sheet metal 30 includes a plurality of holes 46 to allow cooling air to pass from the enclosure 39 to a housing 43 defined between the sheet metal 30 and the bottom wall 41 of the body 17.

[0093] As illustrated in Figures 1 to 3, each first circuit 21 comprises four superimposed conduits 22a-22d, namely a first conduit 22a, a second conduit 22b, a third conduit 22c and a fourth conduit 22d. The conduits 22a-22d are referenced from the outside in.

[0094] The first and second conduits 22a, 22b open onto the abradable layer 19, and more precisely onto the internal surface 40 of the abradable layer 19.

[0095] The third and fourth conduits 22c, 22d open onto the rim 20, and more precisely onto the downstream edge 38 of the rim 20.

[0096] As illustrated in [Fig.3], the conduits 22a-22d are oriented so that the corresponding air jets J1 are projected onto the apexes 11 of the blades 9.

[0097] More specifically, the first, second and third conduits 22a-22c each extend at an angle to the X axis. The fourth conduit 22d extends parallel to the X axis.

[0098] The conduits 22a-22d each extend from upstream to downstream, with reference to the direction of flow of the exhaust gases G, from their air inlet 25 to their air outlet 26.

[0099] In addition, the first, second and third ducts 22a-22c each extend radially from the outside to the inside from their air inlet 25 to their air outlet 26.

[0100] The conduits 22a-22d are supplied by a common chamber 24 which is formed in the body 17. The chamber 24 includes an inlet port 44 which communicates directly with the enclosure 39. The chamber 24 is partly formed in the upstream side wall 42 and partly in the rim 20 of the body 17.

[0101] The first, second and third conduits 22a-22c are directly connected with the chamber 24. The fourth conduit 22d is indirectly connected to chamber 24 via a fitting 45.

[0102] As illustrated in [Fig.3], the air jets J1, J2 from the conduits 22a-22d and the passages 28 form the layer of cold air C (represented in dotted lines) between the vertices 11 and the ring 15 which not only participates in the cooling of the vertices 11, but which also forms a barrier (or obstacle) preventing the upward movement of the exhaust gases G.

[0103] The body 17 of the sector 16 can be metallic, ceramic or made of composite material (for example a ceramic matrix composite material which has the advantage of being able to withstand very high temperatures).

[0104] The body 17 of the sector 16 is for example produced via a process comprising firstly obtaining a raw body (in particular without the first and second circuits 21, 27) via for example a molding process, and secondly various machining operations carried out on the raw body (in particular the first and second circuits 21, 27), in order to obtain the finished body 17.

[0105] The body 17 of sector 16 could also be obtained by additive manufacturing.

[0106] The illustrated example is in no way limiting; sector 16 (or ring) according to the invention could obviously be mounted in a low-pressure turbine of the tur-bomachine.

Claims

Claims

1. Sector (16) of a ring (15) for a turbine (1) of an aircraft turbomachine (2), the sector (16) being circular about a longitudinal axis (X), the sector (16) comprising a body (17) having an internal face (18) on which an abradable layer (19) is attached, the abradable layer (19) being intended to be opposite at least one tip (11) of a blade (9) of a mobile wheel (5), characterized in that the body (17) comprises an upstream rim (20) which projects radially towards the axis (X) and which exceeds the abradable layer (19), the rim (20) being intended to radially cover the tip (11) of the blade (9), the sector (16) further comprising a first internal air circuit (21) which comprises at least one duct (22a-22d) opening onto the upstream edge (20) and / or onto the abradable layer (19), the duct (22a-22d) being oriented so that the air jet (J 1 ) coming from the duct (22a-22d) is projected onto the top (11) of the blade (9).

2. Sector (16) according to claim 1, characterized in that the sector (16) comprises a second internal air circuit (27) which is independent of the first internal air circuit (21), the second air circuit (27) comprising at least one passage (28) opening onto the abradable layer (19), the passage (28) being oriented so that the air jet (J2) coming from the passage (28) is projected onto the tip (11) of the blade (9).

3. Sector (16) according to claim 2, characterized in that the duct (22a-22d) and the passage (28) are each defined by an air inlet (25) and an air outlet (26), the duct (22a-22d) and the passage (28) each extending from upstream to downstream from their air inlet (25) to their air outlet (26).

4. Sector (16) according to claim 2 or 3 when dependent on claim 2, characterized in that the passage (28) is supplied by a recess (29) which is formed in the body (17) of the sector (16) and which is open to the outside, the sector (16) further comprising a pierced sheet metal (30) which covers the recess (29).

5. Sector (16) according to one of the preceding claims, characterized in that the rim (20) has an upstream end which has in cross section an inclined face (23) relative to the axis (X), the radial dimension of the inclined face (23) decreasing from upstream to downstream, so as to deflect the exhaust gases (G) in the direction of the axis (X).

6. Sector (16) according to one of the preceding claims, characterized in that the first air circuit (21) comprises several ducts (22a-22d) which each open onto the upstream edge (20) and / or onto the abradable layer (19), each duct (22a-22d) being oriented so that the corresponding air jet (J 1 ) is projected onto the top (11) of the blade (9), the ducts (22a-22d) being supplied by a common chamber (24) which is formed in the body (17).

7. Sector (16) according to one of the preceding claims, characterized in that the sector (16) comprises several first air circuits (21) distributed around the axis (X), the first air circuits (21) preferably being distributed regularly.

8. Ring (15) for a turbine (1) of an aircraft turbomachine (2), the ring (15) comprising a plurality of sectors (16) according to one of the preceding claims, the sectors (16) being arranged end to end around the axis (X).

9. Turbine (1) of an aircraft turbomachine (2) comprising a ring (15) according to the preceding claim and a movable wheel (5) arranged inside the ring (15), the movable wheel (5) comprising a disc (48) carrying an annular row of blades (9), each blade (9) comprising a blade (10) which has a tip (11) at its free external end, the abradable layers of the different sectors (16) of the ring (15) being opposite the tips (11) of the blades (9).

10. Aircraft turbomachine (2) comprising a turbine (1) according to the preceding claim.

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