Sealing assembly with thermal sheet for gas turbine

Abstract

Sealing assembly with thermal sheet for gas turbine The sealing assembly comprises two successive ring sectors (12) each equipped with a thermal sheet sector (21) on their axial insertion face (28) and a sealing plate (16) positioned in a housing formed by grooves (17) facing each other formed in the radial face (18) of the ring sectors (12). On its axial insertion face (28) each ring sector (12) has an insertion opening (29). In its part fixed to a ring sector (12), each thermal sheet sector (21) has an insertion slot (30). The insertion opening and the insertion slot communicate with the housing for the insertion of a sealing plate. The upper face (32) of each insertion opening has an inclined ramp (33). The lower face (34) of each insertion slot (30) has a rim (36) which partially closes the insertion opening (29).The lower face (31) of the introduction opening is located in continuity with the lower face (24) of the groove. Figure to be published with the abstract: Figure 5.

Description

Title of the invention: Sealing assembly with thermal sheet for gas turbine TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of turbomachines, 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.

[0003] The present invention relates more specifically to a sealing assembly provided for the first stage of a low pressure turbine, this first stage being equipped with a thermal sheet. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0004] In a turbojet or a turboprop, the gas turbines recover part of the kinetic energy of the gases leaving the combustion chamber in order to ensure the operation of the fan, the compressor and the accessories, or to drive the propeller drive shaft, the compressor as well as various accessories in a turboprop.

[0005] The gas turbine module 1 shown in longitudinal section in [Fig.l], with longitudinal axis XX', comprises four stages A, B, C, D: each stage comprising a stator stage 2, followed by a rotor stage 3.

[0006] More particularly, each stator stage 2 is formed by an annular row of distributors 4. The stator stages 2 are mounted between an outer casing 7 and an internal structure 8. At their top, the distributors 4 have an external platform 5. These external platforms 5 are joined end to end circumferentially around the longitudinal axis XX' so as to form a ring. Furthermore, each rotor 3 is formed by an annular row of moving blades 6 which are fixed on disks 9 bolted together.

[0007] The gas turbine 1 further comprises rings 10 arranged concentrically around the rotors 3 of each stage to contain the flow of gas passing through the different stages in the vein 11 of the gas turbine 1.

[0008] Each ring 10 is made up of ring sectors 12, which are positioned end to end circumferentially around the longitudinal axis XX' of the gas turbine 1.

[0009] The ring sectors 12 are each usually wedged between an outer hook 13 and an inner hook 14, these hooks 13, 14 being able to be secured to the outer casing 7 or to the external platform 15 of each distributor 4.

[0010] As can be seen in [Fig.2] to [Fig.8], in order to improve the sealing in the vein 11 of the gas turbine 1, it is known to position one or more sealing plates 16 in particular between two successive ring sectors 12 and 12' within the same ring 10. The addition of a sealing plate 16 makes it possible to avoid gas leaks between two adjacent ring sectors which are likely to reduce the performance of the turbomachine. Indeed, two adjacent ring sectors are likely to have a slight gap E which should be closed.

[0011] As is known in particular from French applications Nos. 2957969 and 3065986, a sealing plate 16 is positioned in a first groove 17 formed in the radial face 18 of a first ring sector 12 and in a second groove 17' formed in the radial face 18' of a second ring sector 12'. It is noted that the radial face 18 of the first ring sector 12 and the radial face 18' of the second ring sector 12' are adjacent and their respective grooves 17, 17' are opposite each other so as to form a housing 19 for a sealing plate 16.

[0012] However, the sealing plates 16 sometimes disengage from the grooves 17, 17'. Indeed, the vibration phenomena combined with the high temperatures in the vein 11 during operation of the turbomachine cause the sealing plates 16 to move and vibrate at the bottom of the grooves 17, 17' by the force of the gases, which sometimes causes them to come out of the grooves 17, 17'.

[0013] Following studies carried out by the applicant, it has been found that the sealing plates 16 are also likely to disengage when the gas turbine module 1 is turned over or placed vertically, in particular during handling phases. In this case, the sealing plates 16 may fall from the gas turbine 1 by gravity. When a gas turbine engine is undergoing testing, sealing plates 16 may also be expelled by the air flow exiting the gas turbine engine, in particular when they are incorrectly mounted in the grooves 17, 17' or when they are already partially disengaged therefrom.

[0014] In the absence of a sealing plate 16, the increase in gas leaks through the gap E present between two ring sectors can cause, depending on the location of the leaks, a reduction in the cooling of the parts of the gas turbine 1, which can cause more or less significant burns, and cause losses in service life and performance.

[0015] Furthermore, the presence of a sealing plate 16 in the gas turbine 1 constitutes a foreign body which can cause significant damage to said gas turbine 1.

[0016] Furthermore, when a lack of sealing plate 16 is noted, the module must be completely dismantled to replace the sealing plate 16, which generates significant additional costs.

[0017] There is therefore a need to improve the sealing assembly for a gas turbine provided with two ring sectors so as to be able to replace a sealing plate which has come out of its housing, without having to dismantle the gas turbine module concerned.

[0018] In some cases, each ring sector may also be equipped with thermal protection, referred to as a "thermal sheet". Usually, the thermal sheet 20 is in the form of an annular part, also divided into thermal sheet sectors 21, 21' assembled end to end, which protects each ring sector. Thus, as shown in [Fig.2] for the first stage A of a gas turbine, each ring sector may have a thermal sheet sector 21, 21' fixed on its downstream axial face 22. Depending on the configuration of the gas turbine module 1, this thermal sheet sector 21, 21' could also be fixed on the upstream axial face 23.

[0019] Thus, the improvement of the sealing assembly must also take into account the presence of this thermal sheet 20.

[0020] This improved sealing assembly must further provide satisfactory locking in all directions for the sealing pads. Summary of the invention

[0021] The invention offers a solution to the problems mentioned above, by providing an introduction orifice through the thermal sheet and the sealing part of each ring sector allowing a sealing plate to be directly introduced into its housing via the downstream or upstream axial face of said ring sector.

[0022] One aspect of the invention relates to a sealing assembly for a gas turbine ring formed from several ring sectors and equipped with a thermal sheet formed from several thermal sheet sectors, comprising:

[0023] a first ring sector and a second ring sector positioned end to end circumferentially around a longitudinal axis XX' of the gas turbine, the first ring sector having a first radial face adjacent to a second radial face 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 ring sector having a downstream axial face and an upstream axial face; • a sealing plate positioned in a housing defined between the first groove and the second groove; • a first sector of thermal sheet having a collar fixed on one of the downstream or upstream axial faces of the first ring sector, this axial face being designated as the first axial introduction face; • a second thermal sheet sector having a collar fixed on one of the downstream or upstream axial faces of the second ring sector, this axial face being designated as the second axial introduction face; • the two collars both being fixed on the same face among the downstream and upstream axial faces of the first ring sector and of the second ring sector; sealing assembly in which: • each ring sector has an introduction opening on its axial introduction face; • each collar has an insertion slot; and • the insertion opening of each ring sector and the insertion slot of each thermal sheet sector communicate with the housing.

[0024] According to one aspect of the invention, each opening for introducing the ring sectors has a lower face and an upper face, the upper face having an inclined ramp.

[0025] According to another aspect of the invention, each slot for introducing the thermal sheet sectors has a lower face and an upper face, the lower face having a rim which partially closes the introduction opening.

[0026] According to a further aspect of the invention, the introduction opening of a ring sector communicates with the introduction opening of the neighboring ring sector and the sum of the widths Lo of the introduction openings is greater than the width Lp of a sealing plate.

[0027] According to one aspect of the invention, the insertion slot of the collar of a thermal sheet sector communicates with the insertion slot of the collar of the neighboring thermal sheet sector and the sum of the widths Lf of the insertion slots is greater than the width Lp of a sealing plate.

[0028] According to another aspect of the invention, each introduction opening of the ring sectors has a lower face, each groove has a lower face, and the lower face of the introduction opening is aligned with the lower face of the groove.

[0029] Another aspect of the invention relates to a first stage of a gas turbine comprising at least one sealing assembly according to the invention as described previously.

[0030] An additional aspect of the invention relates to a gas turbine characterized in that it comprises at least one sealing assembly according to the invention as described previously.

[0031] A sealing plate can be positioned in its housing without having to dismantle the gas turbine module concerned, even if the ring in which a sealing plate is to be fitted is equipped with a thermal sheet.

[0032] The modifications made by the sealing assembly according to the invention do not alter the locking of the sealing plates in all directions because they remain confined in their housing. Indeed, the edge of the insertion slot blocks the axial movement of the sealing plates while the different faces of each housing block the other movements of the sealing plates. Thus, the sealing plates do not risk accidentally coming out of their housing through the openings and the insertion slots.

[0033] Furthermore, the presence of an inclined ramp in the upper face of each opening for introducing the ring sectors makes it possible to facilitate and guide the introduction of the sealing plates into their respective housing.

[0034] Finally, when the lower face of the insertion opening is aligned with the lower face of the groove and in continuity with the latter, the presence of the insertion opening in the axial face of insertion of a sealing part extends the axial length of the grooves, which makes it possible to use longer sealing plates. The use of longer sealing plates advantageously improves the sealing between two successive ring sectors.

[0035] 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

[0036] The figures are presented for information purposes only and in no way limit the invention.

[0037] [Fig. 1] represents a gas turbine module of a turbomachine.

[0038] [Fig.2] represents an enlarged portion of the circled portion in [Fig. 1].

[0039] [Fig.3] represents an enlarged part in perspective of the part circled on [Fig.2] for a module according to the prior art where only a sealing sector, a sealing plate and a thermal sheet sector are represented.

[0040] [Fig.4] represents an enlarged part in perspective from above of the circled part on [Fig.2] for a module according to the invention where only a sealing sector, a sealing plate and a thermal sheet sector are represented.

[0041] [Fig.5] represents an enlarged part in perspective from below of the circled part on [Fig.2] for a module according to the invention where only a sealing sector, a sealing plate and a thermal sheet sector are represented.

[0042] [Fig.6] represents an enlarged part of the circled part in [Fig.2] for a module according to the invention illustrating the installation of a sealing plate in its housing and where only a sealing sector, a sealing plate and a thermal sheet sector are represented.

[0043] [Fig.7] is a view similar to [Fig.6], in which a sealing plate is placed in its housing.

[0044] [Fig.8] is a radial sectional view of the sealing part of two successive ring sectors within the same ring, the section being made according to the section plane VIII-VIII shown in [Fig.7]. DETAILED DESCRIPTION

[0045] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0046] By convention, in the present application, the terms "upstream" and "downstream" are defined relative to the direction of air flow 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" means a direction perpendicular to the longitudinal axis XX'. Furthermore, in the present application, the terms "inner" and "outer", "lower" and "upper", and "inner" and "outer" are defined radially relative to the longitudinal axis XX' of the turbomachine.Thus, a cylindrical part extending along the longitudinal axis XX' comprises 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 the present application, the terms "top" and "bottom" respectively mean "lower" and "upper" when referring to a direction. Thus, the part of a part projecting upwards is a part which projects from the upper face of said part and away from the longitudinal axis XX', in the direction of the outer casing.

[0047] The invention can be used within any type of gas turbine engine, for example a turbojet, a turboprop or a turboshaft engine.

[0048] 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 leaks from the vein 11 of the gas turbine 1 visible in [Fig.l].

[0049] It is recalled that a gas turbine 1, with a longitudinal axis XX', comprises one or more stages A, B, C, D allowing the expansion of the gases at the outlet of the combustion chamber, each stage comprising a stator stage 2 followed by a rotor stage 3. Each stator stage 2 comprises an annular row of distributors 4 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 3 comprises a row annular of mobile blades 6 around said longitudinal axis XX', the rotors 3 being fixed on discs 9 bolted together

[0050] The gas turbine 1 may be a high pressure turbine or a low pressure turbine.

[0051] As can be seen in [Fig.2], the gas turbine 1 comprises rings 10 arranged concentrically around the rotors 3 of each stage to contain the gas flow passing through the different stages in the vein 11 of the gas turbine 1. Each ring 10 is made up of ring sectors 12 which are assembled end-to-end in an annular manner.

[0052] As can be seen in [Fig.4] to [Fig.8], a sealing plate 16 is introduced between two successive ring sectors within the same ring 10.

[0053] Thus, for example, the same ring 10 made up of five to ten ring sectors 12 is equipped with five to ten sealing plates 16.

[0054] The sealing plates 16 are usually made of metal.

[0055] Usually, two successive ring sectors 12 and 12' have similar shapes. They each have a groove 17, 17' formed in a radial face 18, 18', these two grooves 17, 17' being provided to receive a sealing plate 16 between their lower face 24, 24' and their upper face 25, 25'.

[0056] Indeed, as can be seen in [Fig.8], a sealing plate 16 is positioned in a first groove 17 formed in the radial face 18 of a first ring sector 12 and in a second groove 17' formed in the radial face 18' of a second ring sector 12'.

[0057] For the purpose of illustration, in [Fig.8], the spacing E likely to exist between two adjacent ring sectors has been considerably exaggerated.

[0058] The sealing assembly 100 according to the invention thus comprises two successive ring sectors 12 and 12' and a sealing plate 16 positioned in a housing 19 formed by facing grooves 17, 17' formed in the successive ring sectors.

[0059] The radial face 18 of the first ring sector 12 and the radial face 18' of the second ring sector 12' are adjacent and their respective grooves 17, 17' are opposite each other so as to form a housing 19 for a sealing plate 16.

[0060] The sealing assembly 100 according to the invention is more particularly concerned with a ring 10 equipped with an annular thermal sheet 20 on the downstream axial face 22 or on the upstream axial face 23 of its ring sectors 12, 12'.

[0061] Like the rings 10, the annular thermal sheet is formed of thermal sheet sectors 21, 21'. Thus, each ring sector 12 and 12' is preferably equipped with a thermal sheet 21, 21' in the form of a sector.

[0062] Although the invention can be used for any turbine ring 10 gas turbine 1 equipped with a thermal sheet 20 on its downstream axial face 22 or on its upstream axial face 23, the figures illustrate the most common case in which it is the ring 10A of the first stage A of a low pressure gas turbine 1 which is equipped with an annular thermal sheet 20 on its downstream axial face 22.

[0063] In section, the section of each thermal sheet sector 21, 21' usually has an S or Z profile rotated 90 degrees.

[0064] The thermal sheet 20 comprises a collar 26, thus each thermal sheet sector 21, 21' comprises a collar sector 27. A collar sector 27 of the thermal sheet 21, 21' is fixed, for example by brazing or welding, on the downstream axial face 22 or on the upstream axial face 23 of a ring sector 12, 12'.

[0065] For reasons of simplification, the downstream axial face 22 or the upstream axial face 23 of a ring sector 12 on which the collar sector 27 of each thermal sheet sector 21, 21' is fixed will be designated hereinafter as the "axial introduction face 28", because it is from the side where this axial introduction face 28 is located that a sealing plate 16 can be introduced to be put or replaced in its housing 19.

[0066] Indeed, for the introduction of a sealing plate 16 into its housing 19 defined between two grooves 17, 17', an introduction opening 29 is provided in the axial introduction face 28 of each ring sector 12, 12', each introduction opening 29 communicating with the groove 17, 17' of the ring sector concerned.

[0067] For the introduction of a sealing plate 16 into its housing 19, an insertion slot 30 is also provided in the collar sector 27 of each thermal sheet sector 21, 21'. This insertion slot 30 is located in the part of the collar sector 27 which is fixed to the ring sector.

[0068] The insertion opening 29 and the insertion slot 30 communicate with each other and with the housing 19 defined between two grooves 17, 17' to allow the insertion of a sealing plate 16 into said housing 19.

[0069] The introduction opening 29 of a ring sector 12 communicates with the introduction opening of the neighboring ring sector 12' in order to form an introduction opening sufficiently wide for the passage of a sealing plate 16.

[0070] Thus, for two neighboring ring sectors, the sum of the widths Lo of the introduction openings 29 is greater than the width Lp of a sealing plate 16. The width Lo of an introduction opening 29 is shown in [Fig.5].

[0071] Similarly, the insertion slot 30 of the collar of a thermal sheet sector 21, 21' communicates with the insertion slot of the collar of the neighboring thermal sheet sector 21, 21' in order to form an insertion slot 30 sufficiently wide for the passage of a sealing plate 16.

[0072] Thus, for two neighboring ring sectors, the sum of the widths Lf of the slots insertion slot 30 is greater than the width Lp of a sealing plate 16. The width Lf of an insertion slot 30 is shown in [Fig.5].

[0073] The width Lp of a sealing plate 16 is shown in [Fig.8].

[0074] The introduction opening 29 has a lower face 31 and an upper face 32, its upper face 32 being delimited in the direction of the axis XX' (downwards in the figures) by an inclined ramp 33. This inclined ramp 33 thus widens the introduction opening 29 in the direction of the axial introduction face 28, that is to say downstream in the drawings. This inclined ramp 33 has the particular purpose of guiding a sealing plate 16 during its introduction into a housing 19.

[0075] The insertion slot 30 has a lower face 34 and an upper face 35, its lower face 34 being delimited by a rim 36. This rim 36 partially closes the insertion opening 29, in the lower part thereof, which makes it possible to axially block a sealing plate 16 introduced into its housing 19.

[0076] According to a preferred embodiment of the invention, the lower face 31 of the insertion opening 29 is aligned with the lower face 24, 24' of the groove 17, 17' and situated in continuity with the latter, that is to say that the lower face 31 of the insertion opening 29 is situated in the same plane as the lower face 24, 24' of the groove 17, 17' in order to extend the latter.

Claims

Claims

1. Sealing assembly (100) for ring (10) of gas turbine (1) formed of several ring sectors (12, 12') and equipped with a thermal sheet (20) formed of several thermal sheet sectors (21, 21'), comprising: a first ring sector (12) and a second ring sector (12') positioned end to end circumferentially around a longitudinal axis (XX') of the gas turbine (1), the first ring sector (12) having a first radial face (18) adjacent to a second radial face (18') of the second ring sector (12'), a first groove (17) being provided in the first radial face (18) opposite a second groove (17') provided in the second radial face (18'), each ring sector (12, 12') having a downstream axial face (22) and an upstream axial face (23); a sealing plate (16) positioned in a housing (19) defined between the first groove (17) and the second groove (17'); a first thermal sheet sector (21) having a collar (27) fixed on one of the downstream or upstream axial faces (22, 23) of the first ring sector (12), this axial face being designated as the first axial introduction face (28); a second thermal sheet sector (21') having a collar fixed on one of the downstream or upstream axial faces of the second ring sector (12'), this axial face being designated as the second axial introduction face; the two collars both being fixed on the same face among the downstream and upstream axial faces of the first ring sector (12) and of the second ring sector (12'); the sealing assembly (100) being characterized in that: each ring sector (12, 12') has an introduction opening (29) on its axial introduction face (28) such that the introduction opening (29) of a ring sector (12) communicates with the introduction opening of a neighboring ring sector (12') and the sum of the widths Lo of the introduction openings (29) is greater than the width Lp of a sealing plate (16); in that - each collar (27) has an insertion slot (30) such that the insertion slot (30) of the collar sector (27) of a thermal sheet sector (21) communicates with the insertion slot of a collar sector (27') of a neighboring thermal sheet sector (21') and in that the sum of the widths Lf of the insertion slots is greater than the width Lp of a sealing plate (16); and in that - the insertion opening (29) of each ring sector (12, 12') and the insertion slot of each thermal sheet sector (21, 21') communicate with each other and with the housing (19) to allow the insertion of a sealing plate (16) into said housing (19);and in that - each insertion slot (30) of the thermal sheet sectors (21, 21') has a lower face (34) and an upper face (35), the lower face (34) having a rim (36) which partially closes the insertion opening (29).;

2. Sealing assembly (100) according to claim 1, characterized in that each introduction opening (29) of the ring sectors (12, 12') has a lower face (31) and an upper face (32), the upper face (32) having an inclined ramp (33).

3. Sealing assembly (100) according to any one of the preceding claims, characterized in that each introduction opening (29) of the ring sectors (12, 12') has a lower face (31), in that each groove (17, 17') has a lower face (24, 24'), and in that the lower face (31) of the introduction opening (29) is aligned with the lower face (24, 24') of the groove (17, 17').

4. First stage of a gas turbine (1) characterized in that it comprises at least one sealing assembly (100) according to any one of the preceding claims.

5. Gas turbine (1) characterized in that it comprises at least one sealing assembly (100) according to any one of claims 1 to 3.

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