Improved sealing assembly for gas turbine

Abstract

Improved Gas Turbine Sealing Assembly. The sealing assembly (100) comprises two successive ring sectors (12) and a sealing plate (18) positioned in a housing formed by opposing grooves (19) in the sealing portion (13) of the ring sectors. On its downstream axial face (23), each sealing portion has an entry slot (22) that communicates with a groove (19). This entry slot (22) has an upper radial face (24) delimited downwards by an inclined ramp (25) and a lower radial face (26) delimited by a rim (27) provided on the downstream axial face of each sealing portion. The rim (27) of each entry slot has a tab (28) forming a projecting return directed upstream inside the groove (19) and positioned in the upper part of the housing.The upper face (30) of the housing is located radially at a lower height than the inner face (32) of each leg (28). Figure to be published with the abbreviation: Figure 6.

Description

Title of the invention: Improved sealing assembly for gas turbine TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of turbomachinery, in particular that of low pressure gas turbine modules of a turbomachine.

[0002] The present invention relates to a sealing assembly for ensuring the sealing of a low-pressure turbine of a turbomachine, and in particular a sealing assembly comprising a sealing plate positioned between two sealing sectors inside a groove formed in a lateral face opposite each of these two sealing sectors. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] In a turbojet or turboprop, the gas turbines recover part of the kinetic energy of the gases exiting the combustion chamber in order to ensure the operation of the fan, the compressor and the accessories, or to drive the propeller transmission shaft, the compressor and various accessories in a turboprop.

[0004] The gas turbine module 1 shown in longitudinal section on [Fig.1], with longitudinal axis XX', comprises four stages A, B, C, D: each stage comprising a stage of stators 2A, 2B, 2C, 2D, followed by a stage of rotors 3A, 3B, 3C, 3D.

[0005] More specifically, each stator stage 2A, 2B, 2C, 2D is formed by an annular row of distributors 4A, 4B, 4C, 4D. The stator stages 2A, 2B, 2C, 2D are mounted between an outer casing 7 and an internal structure 8. At their apex, the distributors 4A, 4B, 4C, 4D have an external platform 5A, 5B, 5C, 5D. These external platforms 5A, 5B, 5C, 5D are joined end-to-end circumferentially around the longitudinal axis XX' so as to form a ring. Furthermore, each rotor 3A, 3B, 3C, 3D is formed by an annular row of movable blades 6A, 6B, 6C, 6D which are fixed on discs 9A, 9B, 9C, 9D bolted together.

[0006] As can be seen more clearly on [Fig.2], the turbine 1 further comprises rings 10A, 10B, 10C, 10D arranged concentrically around the rotors 3A, 3B, 3C, 3D of each stage to contain the gas flow passing through the different stages in the channel 11 of the turbine 1.

[0007] Each ring 10A, 10B, 10C, 10D is made up of ring sectors 12A, 12B, 12C, 12D.

[0008] As can be seen in the following figures, each ring sector 12A, 12B, 12C, 12D includes a part designated as a retaining part 14A, 14B, 14C, 14D which is provided in the vicinity of the distributors 4A, 4B, 4C, 4D, and a part designated as a sealing part 13A, 13B, 13C, 13D which forms a sealing means with the tops of the moving blades 6A, 6B, 6C, 6D of the rotors 3A, 3B, 3C, 3D. The ring sectors 12A, 12B, 12C, 12D are each wedged inside the outer casing 7 between an axial hook 15 integral with the outer casing 7 and a hook 16 integral with the external platform 5A, 5B, 5C, 5D of each distributor 4A, 4B, 4C, 4D of stator stage 2A, 2B, 2C, 2D.

[0009] As can be seen in [Fig.3] to [Fig.9], in order to improve the sealing in the In turbine 1, a sealing plate 18 is positioned between two successive ring sectors within the same ring 10A, 10B, 10C, 10D, in the sealing area of ​​said ring sectors. Adding a sealing plate 18 to this sealing area prevents gas leaks between two adjacent ring sectors, which could reduce the turbomachine's performance. Indeed, two adjacent ring sectors may have a slight gap E that must be sealed.

[0010] As is known in particular from French applications No. 2957969 and No. 3065986, a sealing plate 18 is positioned in a first groove 19 formed in the radial face 20 of a first sealing part 13A, 13B, 13C, 13D and in a second groove 19' formed in the radial face 20' of a second sealing part 13'A, 13'B, 13'C, 13'D. It is noted that the radial face 20 of the first sealing part 13A, 13B, 13C, 13D and the radial face 20' of the second sealing part 13'A, 13'B, 13'C, 13'D are adjacent and that their respective grooves 19, 19' are opposite each other so as to form a housing 21 for a sealing plate 18.

[0011] For the insertion of a sealing plate 18 into a groove 19, 19' formed in the radial face 20, 20' of a sealing part 13A, 13B, 13C, 13D, each sealing part has an insertion slot 22 provided on one of its axial faces, generally on its downstream axial face 23, each insertion slot 22 communicating with the groove 19, 19'. The insertion slot 22 of a sealing part 13A, 13B, 13C, 13D communicates with the insertion slot of the neighboring sealing part 13'A, 13'B, 13'C, 13'D in order to form an insertion slot wide enough for the passage of a sealing plate 18.

[0012] However, the sealing plates 18 sometimes disengage from the grooves 19, 19'. Indeed, the vibrational phenomena combined with the high temperatures in the duct 11 during the operation of the turbomachine cause the sealing plates 18 to move and vibrate at the bottom of the grooves 19, 19' by the force of the gases, which sometimes leads to them coming out at the level of the inlet slots 22.

[0013] Following studies carried out by the applicant, it was also found that the sealing plates 18 are also susceptible to disengagement when the gas turbine module 1 is inverted or placed vertically, particularly during handling. In this case, the sealing plates 18 can fall from the gas turbine 1 by gravity. When a gas turbine engine is being tested, sealing plates 18 can also be expelled by the airflow exiting the gas turbine engine, particularly when they are incorrectly mounted in the grooves 19, 19' or when they are already partially disengaged from them.

[0014] In the absence of a sealing plate 18, the increase in gas leakage through the gap E present between two ring sectors can, depending on the location of the leaks, lead to a decrease in the cooling of the parts of the turbine 1, which can cause more or less significant burns, and generate losses in service life and performance.

[0015] Furthermore, the presence of a sealing plate 18 in the gas turbine 1 constitutes a foreign body which may cause significant damage to said gas turbine 1.

[0016] In addition, when a lack of sealing plate 18 is found, the module must be completely disassembled to replace the sealing plate 18, which generates significant additional costs.

[0017] There is therefore a need to improve the gas turbine sealing assembly between two ring sectors. Indeed, studies carried out by the applicant have notably determined that the current sealing assembly does not provide sufficient axial and radial locking for the sealing plates.

[0018] The improvement of this sealing assembly must not only prevent a sealing plate from disengaging from its housing defined between two grooves, but must also ensure that a sealing plate is properly engaged in its housing. Summary of the invention

[0019] The invention offers a solution to the problems mentioned above, by equipping the groove where a sealing plate is housed with a tab extending axially, this tab forming a stop which blocks any radial movement of a sealing plate introduced into the housing defined between two grooves.

[0020] One aspect of the invention relates to a sealing assembly for a gas turbine ring formed of several ring sectors, comprising: • a first ring sector having a sealing portion and a second ring sector having a sealing portion positioned end to end circumferentially around a longitudinal axis of the gas turbine, the sealing portion of the first ring sector having a first face radial adjacent to a second radial face of the sealing portion of the second ring sector, a first groove being formed in the first radial face opposite a second groove formed in the second radial face, each sealing portion having a downstream axial face with an insertion slot for a sealing plate, the two insertion slots communicating with a defined housing between the first groove and the second groove, each insertion slot having an upper radial face delimited by an inclined ramp and a lower radial face delimited by a rim, and • a sealing plate positioned in the housing; the assembly being characterized in that: • the rim of the lower radial face of each inlet slot has a tab forming a projecting return which extends axially upstream inside the groove and which is positioned in the upper part of the rim.

[0021] According to one aspect of the invention, at least one leg extends over the entire radial length of each inlet slot.

[0022] According to another aspect of the invention, the housing has a top face defining a first upper bearing surface for the sealing plate, each tab has an inner face defining a second upper bearing surface, and the first upper bearing surface is located radially at a height h lower than the height H of the second upper bearing surface defined by the inner face of each tab.

[0023] According to a further aspect of the invention, each leg has an upper face and this upper face has a chamfered part which extends axially upstream inside the groove.

[0024] According to one aspect of the invention, the chamfered part of each leg is parallel to the inclined ramp.

[0025] Another aspect of the invention relates to a gas turbine comprising at least one sealing assembly as described above.

[0026] Thanks to the invention, the sealing plate is better held in its housing and is not at risk of accidentally coming out. Indeed, the tab provided at each insertion slot forms a radial locking stop for the sealing plate in an area where said plate could have come out. This tab is provided at the level of a rim which already forms an axial locking stop; thus, by the combination of radial and axial locking, the sealing plate is perfectly retained at the insertion slot. Being further retained without possibility of exit at the upstream part of its housing, located opposite the insertion slot, the sealing plate is perfectly enclosed within its accommodation without risk of accidental exit.

[0027] The tab provided at the level of each insertion slot also ensures that the sealing plate cannot be oriented upwards in the extraction position by pivoting at the upstream part of the upper ramp of the insertion slot.

[0028] The tab provided at each insertion slot also allows for visual verification that the sealing plate is fully inserted into its housing and is not partially dislodged. A simple and quick check involves visually verifying that the downstream portion of the sealing plate is positioned under the tab provided at each insertion slot. If it is not, this indicates that the sealing plate is not properly inserted into its housing and may come loose.

[0029] The fact that the upper face of the housing is lower than the inner face of each tab advantageously ensures that, when a sealing plate is in contact with the upper part of its housing, it is not in contact with a tab. Thus, the sealing plate in the upper position cannot be in contact with the upper part of the feed slot, whether with the inclined ramp or any part of the tab, to avoid any risk of the sealing plate potentially disengaging if it moves downstream.

[0030] Finally, the fact that the chamfered part of each leg is parallel to the inclined ramp makes it easier to introduce a sealing plate into its housing, without affecting the OK of the latter in its housing.

[0031] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0032] The figures are presented by way of illustration and in no way limit the invention.

[0033] [Fig. 1] represents a turbomachine gas turbine module.

[0034] [Fig.2] represents an enlarged part of the framed part on [Fig. 1].

[0035] [Fig.3] represents an enlarged part of the circled part in [Fig.2] for a module according to prior art.

[0036] [Fig.4] represents an enlarged part of the circled part on [Fig.2] for a module according to the invention.

[0037] [Fig.5] is a perspective view of [Fig.4], in which a sealing plate is being inserted into its housing.

[0038] [Fig.6] 6 is a view similar to [Fig.4], in which a sealing plate is present in her accommodation.

[0039] [Fig.7] is a side view of [Fig.5].

[0040] [Fig.8] is a side view of [Fig.6].

[0041] [Fig.9] is a radial cross-sectional view of the sealing portion of two sectors of successive rings within the same ring. DETAILED DESCRIPTION

[0042] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0043] By convention, in this application, the terms "upstream" and "downstream" are defined with respect to the direction of airflow in the turbomachine. Thus, upstream is located on the air inlet side, while downstream is located on the air outlet side. Similarly, the term "longitudinal" or "axial" corresponds to a direction parallel to the longitudinal axis XX' along which the turbomachine extends, while the term "radial" is understood to mean a direction perpendicular to the longitudinal axis XX'. Furthermore, in this application, the terms "inside" and "outside," "lower" and "upper," and "internal" and "external" are defined radially with respect to the longitudinal axis XX' of the turbomachine.Thus, a cylindrical part extending along the longitudinal axis XX' has an inner radial face facing the longitudinal axis XX' of the turbomachine and an outer radial face, opposite its inner face and facing the outer casing of the turbomachine. Finally, in this application, the terms "top" and "bottom" mean "lower" and "upper," respectively, when referring to a direction. Therefore, the part of a part projecting upwards is a part that projects from the upper face of said part away from the longitudinal axis XX', in the direction of the casing.

[0044] The invention can be used within any type of gas turbine engine, for example a turbojet, a turboprop or a turboshaft engine.

[0045] The invention relates to a sealing assembly 100 for ensuring sealing in a gas turbine 1 of a turbomachine. In particular, the sealing assembly 100 according to the invention makes it possible to limit gas leakage from the stream 11 of the gas turbine 1 visible in [Fig. 1].

[0046] It is recalled that a gas turbine 1, with longitudinal axis XX', comprises one or more stages A, B, C, D allowing the expansion of the gases exiting the combustion chamber, each stage comprising a stator stage 2A, 2B, 2C, 2D followed by a rotor stage 3A, 3B, 3C, 3D. Each stator stage 2A, 2B, 2C, 2D comprises an annular row of distributors 4A, 4B, 4C, 4D mounted circumferentially around the longitudinal axis XX' of the gas turbine 1 between an outer casing 7 and an internal structure 8, and each rotor 3A, 3B, 3C, 3D comprises an annular row of movable blades 6A, 6B, 6C, 6D around said longitudinal axis XX', the rotors 3A, 3B, 3C, 3D being fixed on discs 9A, 9B, 9C, 9D bolted together

[0047] The gas turbine 1 can be a high-pressure turbine or a low-pressure turbine.

[0048] As can be seen in [Fig.2], the turbine 1 comprises rings 10A, 10B, 10C, 10D arranged concentrically around the rotors 3A, 3B, 3C, 3D of each stage to contain the gas flow passing through the different stages in the channel 11 of the turbine 1. Each ring 10A, 10B, 10C, 10D is made up of ring sectors 12A, 12B, 12C, 12D, and each ring sector 12A, 12B, 12C, 12D includes a retaining part 14A, 14B, 14C, 14D and a sealing part 13A, 13B, 13C, 13D.

[0049] The ring sectors 12A, 12B, 12C, 12D are usually wedged between an axial hook 15 integral with the outer casing 7 and a hook 16 integral with the external platform 5A, 5B, 5C, 5D of each distributor 4A, 4B, 4C, 4D of stator stage 2A, 2B, 2C, 2D.

[0050] As can be seen in [Fig.4] to [Fig.9], a sealing plate 18 is introduced between two successive ring sectors within the same ring 10A, 10B, 10C, 10D in the sealing part 13A, 13B, 13C, 13D and 13'A, 13'B, 13'C, 13'D of said ring sectors.

[0051] Thus, for example, the same ring 10A, 10B, 10C, 10D made up of five to ten ring sectors 12A, 12B, 12C, 12D will be equipped with five to ten sealing plates 18.

[0052] The sealing plates 18 are usually made of metal.

[0053] Typically, two successive ring sectors 12A, 12B, 12C, 12D and 12'A, 12'B, 12'C, 12'D have similar shapes. Each has a groove 19, 19' formed in a radial face 20, 20' of a sealing portion, these two grooves 19, 19' being intended to receive a sealing plate 18.

[0054] Indeed, as can be seen on [Fig.9], a sealing plate 18 is positioned in a first groove 19 formed in the radial face 20 of a first sealing part 13A, 13B, 13C, 13D and in a second groove 19' formed in the radial face 20' of a second sealing part 13'A, 13'B, 13'C, 13'D.

[0055] For illustrative purposes, in [Fig.9], the spacing E that may exist between two adjacent ring sectors has been considerably exaggerated.

[0056] The sealing assembly 100 according to the invention thus comprises two successive ring sectors 12A, 12B, 12C, 12D and 12'A, 12'B, 12'C, 12'D and a sealing plate 18 positioned in a housing 21 formed by opposite grooves 19, 19' formed in the successive ring sectors 12A, 12B, 12C, 12D and 12'A, 12'B, 12'C, 12'D.

[0057] The radial face 20 of the first sealing part 13A, 13B, 13C, 13D and the face radial 20' of the second sealing part 13'A, 13'B, 13'C, 13'D are adjacent and their respective grooves 19, 19' are opposite each other so as to form a housing 21 for a sealing plate 18.

[0058] On its downstream axial face 23, each sealing part 13A, 13B, 13C, 13D and 13'A, 13'B, 13'C, 13'D has an insertion slot 22 which communicates with the groove 19, 19'. This insertion slot 22 is provided to allow the insertion of a sealing plate 18 into the housing 21. Such an insertion operation is shown in [Fig.6] and [Fig.8].

[0059] Each feed slot 22 has an upper radial face 24 delimited downwards by an inclined ramp 25. This inclined ramp 25 thus widens the opening of the feed slot 22 downstream. Its purpose is, in particular, to guide a sealing plate 18 during its insertion into a housing 21.

[0060] Each introduction slot 22 also has a lower radial face 26 delimited by a rim 27. This rim 27 is provided on the downstream axial face 23 of each sealing part.

[0061] The rim 27 of each inlet slot 22 has a tab 28 forming a projecting return directed towards the inside of the groove 19, 19'. This tab 28 is positioned in the upper part of the housing 21 and is directed upstream.

[0062] According to a preferred embodiment of the invention shown in the figures, each leg 28 extends over the entire radial length of each inlet slot 22. However, it may extend only over a portion of the radial length of each inlet slot 22.

[0063] Preferably, as shown in the figures, each leg 28 extends axially towards the inside of the groove 19, 19'. It can however extend at an angle, outwards, or more preferably inwards.

[0064] Preferably, as shown in the figures, the first upper bearing surface 29 defined by the upper face 30 of the housing 21 is located at a radial height h which is less than the radial height H of the second upper bearing surface 31 defined by the inner face 32 of each tab 28. In other words, each tab 28 is higher than the housing 21. Thus, when a sealing plate 18 comes against the upper face 30 of the housing 21, it does not come into contact with the inner face 32 of each tab 28.

[0065] According to a preferred embodiment of the invention shown in the figures, the upper face 33 of each leg 28 has a chamfered part 34 at its upstream end 35. This chamfered part 34 is preferably parallel to the inclined ramp 25.

[0066] The invention also relates to a gas turbine 1 comprising at least one sealing assembly 100 as described above. Such a gas turbine 1 may include a sealing assembly 100 for each of the ring sectors of the same ring 10A, 10B, 10C, 10D, and for all the rings 10A, 10B, 10C, 10D of the same gas turbine 1.

Claims

Claims

1. Sealing assembly (100) for a ring (10A, 10B, 10C, 10D) of a gas turbine (1) formed of several ring sectors, comprising: - a first ring sector (12A, 12B, 12C, 12D) having a sealing portion (13A, 13B, 13C, 13D) and a second ring sector (12'A, 12'B, 12'C, 12'D) having a sealing portion (13'A, 13'B, 13'C, 13'D) positioned end to end circumferentially around a longitudinal axis (XX') of the gas turbine (1), the sealing portion (13A, 13B, 13C, 13D) of the first ring sector (12A, 12B, 12C, 12D) being arranged in a radial direction relative to the ... 12C, 12D) having a first radial face (20) adjacent to a second radial face (20') of the sealing portion (13'A, 13'B, 13'C, 13'D) of the second ring sector (12'A, 12'B, 12'C, 12'D), a first groove (19) being provided in the first radial face (20) opposite a second groove (19') provided in the second radial face (20'), each sealing portion (13A, 13B, 13C, 13D, 13'A, 13'B, 13'C,13'D) having a downstream axial face (23) having an insertion slot (22) for a sealing plate (18), the two insertion slots (22) communicating with a housing (21) defined between the first groove (19) and the second groove (19'), each insertion slot (22) having an upper radial face (24) delimited by an inclined ramp (25) and a lower radial face (26) delimited by a rim (27), and - a sealing plate (18) positioned in the housing (21); the sealing assembly (100) being characterized in that: - the rim (27) of the lower radial face (26) of each insertion slot (22) has a tab (28) forming a projecting return which extends axially upstream inside the groove (19, 19') and which is positioned in the upper part of the rim (27).,

2. Sealing assembly (100) according to claim 1, characterized in that at least one tab (28) extends over the entire radial length of each insertion slot (22).

3. Sealing assembly (100) according to claim 1 or claim 2, characterized in that the housing (21) has an upper face (30) defining a first upper bearing surface (29) for the sealing plate (18), in that each tab (28) has an internal face (32) defining a second upper bearing surface (31), and in that the first upper bearing surface (29) is located radially at a height h less than the height H of the second upper bearing surface (31) defined by the internal face (32) of each tab (28).

4. Sealing assembly (100) according to any one of the preceding claims, characterized in that each tab (28) has an upper face (33) and in that this upper face (33) has a chamfered part (34) which extends axially upstream inside the groove (19, 19').

5. Sealing assembly (100) according to the preceding claim, characterized in that the chamfered part (34) of each tab (28) is parallel to the inclined ramp (25).

6. Gas turbine (1) characterized in that it comprises at least one sealing assembly (100) according to any one of the preceding claims.