HIGH-PRESSURE GAS TURBINE FOR A TURBOMACHINE AND TURBOMACHINE

Description

Technical field

[0001] The present invention relates to a high-pressure gas turbine for a turbomachine. It also relates to a turbomachine comprising such a gas turbine. Prior art

[0002] Classically, as represented in the Figure 1, a turbomachine 10 of the double-flow turbojet type comprises, from upstream to downstream in the direction of circulation of the gases inside the turbomachine 10, a fan 14, a low-pressure compressor 16, a high-pressure compressor 18, a combustion chamber 20, a high-pressure turbine 22, a low-pressure turbine 24 and an exhaust nozzle 26. The low-pressure compressor 16, the high-pressure compressor 18, the combustion chamber 20, the high-pressure turbine 22, the low-pressure turbine 24 and the exhaust nozzle 26 are arranged radially inside a casing 12 which delimits, radially outwards, an annular vein 11 of the turbomachine 10 in which the gases flow from upstream to downstream.

[0003] The high-pressure compressor 14 and the low-pressure compressor 18 are respectively connected to a high-pressure turbine 22 and a low-pressure turbine 24 by a respective shaft 15, 17 extending along the longitudinal axis X of rotation of the shafts of the turbomachine 10. In the following, the orientation qualifiers, such as “longitudinal”, “radial” and “circumferential” are defined with reference to the longitudinal axis. Furthermore, the terms upstream and downstream are defined with respect to the direction of circulation of the gases within the turbomachine.

[0004] The high-pressure turbine 22 comprises a plurality of stages, one of which is partially shown in FIG. Figure 2 , each comprising a distributor 30 and a mobile wheel 40 mounted downstream of the distributor 30.

[0005] The distributor 30 comprises an internal annular platform 34 and an annular row of fixed blades 32. Each fixed blade 32 extends radially in the annular vein 11 and is connected, radially inside, to the internal annular platform 34. The distributor 30 generally comprises an annular radial flange 36 for attachment to the casing 5.

[0006] The moving wheel 40 comprises an annular row of moving blades 42 carried by a disc 41 comprising a plurality of cells on its external periphery, each receiving a root 46 of a blade 42. Each moving blade 42 further comprises a sector of an internal annular platform 44 of the moving wheel 40 from which a blade 42' extends radially outwards through the annular vein 11. The internal annular platform 44 thus comprises a plurality of sectors arranged circumferentially end to end around the longitudinal axis X.

[0007] The internal annular platform 34 of the distributor 30 and the internal annular platform 44 of the moving wheel 40 each delimit, radially inwards, the annular vein 11.

[0008] In operation, the gases flowing in the annular vein 11 are introduced into a space formed longitudinally between the internal annular platform 34 of the distributor 30 and the internal annular platform 44 of the moving wheel 40, which reduces the performance of the turbomachine 10. To limit this phenomenon, it is known to arrange, radially inside the internal annular platform 34 of the distributor 30, an upstream annular spoiler 47 of the internal annular platform 44 and a downstream annular spoiler 54 of an annular part 50 for sealing the casing 5. Thus, a baffle is formed in the longitudinal space between the internal annular platform 34 of the distributor 30 and the internal annular platform 44 of the moving wheel 44, limiting the leakage, radially inwards, of the gases flowing in the annular vein 11.

[0009] The annular part 50 comprises a cavity 51 in which an elastic member 51' is housed.

[0010] Furthermore, a purge air flow, taken from the low-pressure compressor 14 and / or the high-pressure compressor 16, is directed through an annular purge cavity 62 towards the space formed longitudinally between the internal annular platform 34 of the distributor 30 and the internal annular platform 44 of the mobile wheel 4. This purge air flow thus makes it possible to redirect the gases that have entered the purge cavity 62 towards the annular vein 11.

[0011] However, this solution is not entirely satisfactory in that the air sampling taken at the level of the low-pressure compressor 14 and / or the high-pressure compressor 16 reduces the efficiency of the turbomachine 10. Furthermore, the reintroduction, into the annular vein 11, of the purge air and the gases having entered the purge cavity 62 disturbs the flow in the annular vein 11, which also reduces the performance of the turbomachine 10.

[0012] US 2015 / 354391 A1, FR 2 930 593 A1, FR 2 940 351 A1, FR 3 001 492 A1 and particularly US 9 605 552 B2 disclose the state of the prior art. Summary

[0013] The present invention improves the situation.

[0014] The present invention consists of a high-pressure gas turbine for a turbomachine extending about a longitudinal axis, the turbine comprising: a distributor comprising an internal annular platform and an annular row of fixed blades, each fixed blade being connected, radially inwards, to the internal annular platform, an annular row of moving blades mounted downstream of the distributor, comprising a disc from which blades extend radially outwards, an upstream sealing part applied to a downstream face of the distributor and a downstream sealing part applied to an upstream face of the disc of the annular row of moving blades, the upstream sealing part comprising an annular part from which a downstream annular spoiler extends longitudinally downstream, said annular part having a radially external part comprising an upstream annular cavity, said upstream cavity being open at a radially external annular clearance, delimited between the downstream face of the distributor and the upstream sealing part,the downstream sealing part comprising a first upstream spoiler arranged, at least in part, radially inside the internal annular platform of the distributor and radially outside the downstream spoiler of the upstream sealing part, said downstream sealing part further comprising a second upstream spoiler arranged, at least in part, radially inside the downstream spoiler, the downstream spoiler extending, at least in part, radially opposite the first and second upstream spoilers, the first and second upstream spoilers and the downstream spoiler defining a double baffle.

[0015] The double baffle generates a pressure drop that limits the gas leakage flow rate from the vein radially inwards, between the distributor and the annular row of moving blades, also limiting the necessary air purge flow rate. Furthermore, the upstream annular cavity also limits such a leakage flow rate, by creating an additional pressure drop.

[0016] Furthermore, the bleed air flow rate required to redirect the hot gases that have entered between the distributor and the annular row of moving blades towards the annular flow path is reduced. Thus, the elements of the annular row of moving blades are better protected. Also, the quantity of bleed air taken from the high-pressure compressor and / or the low-pressure compressor is reduced, which improves the overall efficiency of the turbomachine and therefore reduces the specific consumption.

[0017] In the present disclosure, a so-called annular part may comprise a plurality of sectors arranged circumferentially end to end around an axis, in particular at 360° around said axis. Of course, a so-called annular part may also be a single piece, i.e. formed from a single piece and not from sectors.

[0018] The first upstream spoiler, the second upstream spoiler and / or the downstream spoiler may be, at least in part, cylindrical.

[0019] The first upstream spoiler may have a radially external face which is of truncated cone shape with a section decreasing towards the upstream extending over at least a first longitudinal portion.

[0020] Such a shape facilitates the evacuation of purge air and gases from the cavity between the distributor and the annular row of moving blades into the annular vein. Furthermore, such a feature allows the direction in which the gases mixed in the annular vein are reintroduced into the annular vein to be adapted to minimize disturbances to the gases flowing in the annular vein.

[0021] The annular space extending between the first and second upstream spoilers is delimited by a radially inner surface of the first upstream spoiler, a radially outer surface of the second upstream spoiler and a concave upstream surface of the downstream sealing part.

[0022] The radially internal surface of the second upstream spoiler can be connected to an upstream face of the downstream sealing part by a concave rounded portion.

[0023] The upstream annular cavity of the upstream sealing part may be delimited longitudinally by a downstream radial face of the distributor and by a downstream radial wall of the upstream sealing part extending radially outward from the annular portion of the upstream sealing part portion, and delimited radially by an annular end surface located at the radially outer end of said annular portion and by a longitudinal wall extending longitudinally upstream from the radially outer end of the downstream radial wall, said external annular clearance being formed longitudinally between the downstream radial face of the distributor and the upstream end of said longitudinal wall.

[0024] Said annular end surface may comprise a frustoconical zone widening downstream.

[0025] The radially inner annular face of the inner annular platform of the distributor may have at least one concave-shaped area.

[0026] The distributor may further comprise a radial annular flange extending radially inwardly from the inner annular platform, the upstream sealing part being attached and fixed to the radial annular flange.

[0027] The present invention also relates to a turbomachine comprising a high-pressure gas turbine of the aforementioned type. Brief description of the drawings

[0028] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: [ Fig. 1 ], already described previously, is a partial schematic sectional view of a turbomachine of the prior art; [ Fig. 2], already described previously, is a partial schematic sectional view of a high-pressure turbine of the turbomachine of the Figure 1 ; [ Fig. 3 ] is a partial schematic perspective and sectional view of a high-pressure turbine according to an embodiment of the present document; [ Fig. 4 ] is a partial schematic sectional view of the turbine of the Figure 3 ; Description of the embodiments

[0029] Reference is now made to the Figures 3 and 4 which represent, according to a first embodiment, partially a high-pressure turbine of a turbomachine with longitudinal axis X. The high-pressure turbine comprises a plurality of stages each comprising a distributor 30 and a mobile wheel 40 mounted downstream of the distributor 30.

[0030] The distributor 30 comprises an annular row of fixed blades 32. Each fixed blade 32 is connected, radially inward, to an inner annular platform 34 of the distributor 30. Each fixed blade 32 extends radially outward from the inner annular platform 34. Each fixed blade 32 is connected, radially outward, to an outer platform 34' connected to an outer casing of the high-pressure turbine. A radially outer annular face of the inner annular platform 34 and a radially inner annular face of the outer platform 34' delimit, radially, respectively inwardly and outwardly, an annular vein 11 of the turbomachine 10 at the distributor 30 of the high-pressure turbine. Thus, each fixed blade 32 extends radially inside the annular vein 11.

[0031] The distributor 30 further comprises a radial annular flange 36 extending radially inward from the internal annular platform 34. The distributor 30 can be connected to an internal turbomachine casing via the radial annular flange 36.

[0032] The movable wheel 40 comprises an annular row of movable blades 42 carried by a disc 41. The movable wheel 40 comprises an internal annular platform 44. Each movable blade 42 of the movable wheel 40 comprises a sector of the internal annular platform 44, the sectors being arranged circumferentially end to end around the longitudinal axis X. A radially external annular face 44a of the internal annular platform 44 delimits, radially inwards, the annular vein 11 at the movable wheel 40 of the turbine. Each movable blade 42 comprises a blade 42' extending, radially outwards, into the annular vein 11 from the respective sector of the internal annular platform 44.

[0033] The movable wheel 40 also comprises a downstream sealing part 43 attached and fixed to an upstream radial surface of the disc 41 and of the zone comprising the platform 44. According to a variant not forming part of the claimed invention, the downstream sealing part 43 may be made of the same material as the disc 41. The downstream sealing part 43 comprises a first upstream annular spoiler 47 which is annular and which extends longitudinally upstream at the level of the radially external end of the downstream sealing part 43. The first upstream annular spoiler 47 is arranged, here in part, radially inside the internal annular platform 34 of the distributor 30. In other words, the first upstream annular spoiler 47 is arranged radially inside the internal annular platform 34 of the distributor 30 and, in part, radially opposite the internal annular platform 34 of the distributor 30.The upstream end of the first upstream spoiler 47 is located longitudinally further upstream than the downstream end of the internal platform 34.

[0034] The first upstream annular spoiler 47 has a radially external annular face 47a which is of truncated cone shape with a section decreasing towards the upstream and which extends over a first longitudinal portion of the first upstream annular spoiler 47. The first portion of the upstream annular spoiler 47 is, here in part, radially opposite the internal annular platform 34 of the distributor 30. The radially external annular face 47a of the first portion of the upstream annular spoiler 47 is here connected to the radially external annular face 44a of the internal annular platform 44 of the mobile wheel 40, in particular by a rounding.

[0035] Furthermore, the downstream sealing part 43 comprises a second upstream annular spoiler 48, extending longitudinally downstream and located radially inside the first upstream spoiler 47.

[0036] The annular space extending between the first and second upstream spoilers 47, 48 is delimited by a radially internal surface 47b of the first upstream spoiler 47, a radially external surface 48a of the second upstream spoiler 48 and a concave upstream surface 43a of the downstream sealing part 43.

[0037] Furthermore, the second upstream spoiler 48 comprises a radially internal surface 48b which is connected to an upstream face of the downstream sealing part 43 by a concave rounded portion 49.

[0038] The high-pressure turbine further comprises an upstream sealing part 50, which is here annular, applied against a downstream face 36a of the distributor 30. The upstream sealing part 50 is here attached and fixed to the radial annular flange 36. To do this, the upstream sealing part 50 comprises an annular part 52 applied against a downstream face 36a of the radial annular flange 36 of the distributor 30. The annular part 52 of the upstream sealing part 50 can be fixed, for example by bolting, to the radial annular flange 36 of the distributor 30. The upstream sealing part can be an integral part of the casing of the high-pressure turbine or of the flange 36.

[0039] The upstream sealing part 50 comprises a cavity 51 in which an elastic member 51' is housed.

[0040] The upstream sealing part 50 comprises a downstream spoiler 54 which is annular. The first downstream annular spoiler 54 is arranged, here in part, radially inside the first upstream annular spoiler 47 and radially outside the second upstream spoiler 48 of the downstream sealing part 43. Furthermore, the downstream end of the downstream spoiler 54 is located longitudinally further downstream than the upstream ends of the first and second upstream spoilers 47, 48. The spoilers 54, 47, 48 form a double baffle, and create pressure losses limiting the flow rate of gas capable of flowing radially through said double baffle.

[0041] The upstream sealing part 50 further comprises an upstream annular cavity 56, said upstream cavity 56 being open at the level of a radially external annular clearance 58, delimited between the downstream face 36a of the distributor 30 and the upstream sealing part 50.

[0042] The upstream annular cavity 56 of the upstream sealing part 50 may be delimited longitudinally by the downstream radial face 36a of the distributor 30 and by a downstream radial wall 60 of the upstream sealing part 50 extending radially outward from the annular portion 52 of the upstream sealing part portion 50, and delimited radially by an annular end surface 52a located at the radially outer end of said annular portion 52 and by a longitudinal wall 62 extending longitudinally upstream from the radially outer end of the downstream radial wall 60. The external annular clearance 58 is formed longitudinally between the downstream radial face 36a of the distributor 30 and the upstream end of said longitudinal wall 62.

[0043] Said annular end surface 52a may comprise a frustoconical zone 52b widening downstream.

[0044] According to a variant not forming part of the claimed invention and not shown, the upstream annular sealing part 50 may be made in one piece with the radial annular flange 36 of the distributor 30.

[0045] According to a variant not shown, the annular sealing part 50 may comprise a plurality of sectors arranged circumferentially end to end around the longitudinal axis X.

[0046] The radially internal annular face 34a of the internal annular platform 34 of the distributor 30 may have a concave-shaped zone 34b which is arranged radially opposite the upstream annular spoiler 47 and / or the longitudinal wall 62.

[0047] The turbine further comprises an annular purge cavity 62 located longitudinally between the upstream sealing part 50 and the downstream sealing part 43, or more generally between the distributor 30 and the moving wheel 40, and radially inside the second upstream spoiler 48.

[0048] A free space 64 is formed, longitudinally, between the internal annular platform 34 of the distributor 30 and the internal annular platform 44 of the moving wheel 40. The internal annular platform 34 of the distributor 30 and the upstream annular spoiler 47 of the moving wheel 40 together define a clearance or flow conduit between the annular vein 11 and the double baffle 47, 48, 54.

[0049] In operation, hot gases from the vein 11 enter the space 64 formed between the platform 34 and the platform 44, this flow of hot gases being countered by a flow of purge air, taken from the low-pressure compressor 14 and / or the high-pressure compressor 16, and directed through the annular purge cavity 62 and the double baffle 47, 48, 54, towards the vein 11.

[0050] The double baffle 47, 48, 54 and the upstream cavity 56 make it possible to generate pressure losses limiting the progression of the flow of hot gases from the vein 11 radially inwards, towards the annular purge cavity 62, also limiting the purge air flow necessary to avoid damage to the turbine.

[0051] The invention is not limited to the examples described above and is susceptible of numerous variations, but is defined by the statement of the claims. In particular, the embodiments are capable of being combined, within the framework of the statement of the claims.

Claims

1. High-pressure gas turbine for a turbomachine (10) extending around a longitudinal axis (X), the turbine comprising: - a nozzle guide vane assembly (30) comprising an internal annular platform (34) and an annular array of fixed vanes (32), each fixed vane (32) being connected, radially inwards, to the internal annular platform (34), - an annular array of movable blades (40) mounted downstream of the nozzle guide vane assembly (30), comprising a disc (41) from which blades (42) extend radially outwards, - an upstream sealing element (50) applied against a downstream face of the nozzle guide vane assembly (30), and a downstream sealing element (43) applied against an upstream face of the disc (41) of the annular array of movable blades (40), - the upstream sealing element (50) comprising an annular portion (52) from which a downstream annular deflector (54) extends longitudinally downstream, said annular portion (52) having a radially outer portion comprising a upstream annular cavity (56), said upstream cavity (56) being open at a radially outer annular clearance (58) delimited between the downstream face of the nozzle guide vane assembly (30) and the upstream sealing element (50), - the downstream sealing element (43) comprising a first upstream deflector (47) arranged, at least in part, radially internally to the internal annular platform (34) of the nozzle guide vane assembly (30) and radially externally to the downstream deflector (54) of the upstream sealing element (50), said downstream sealing element (43) further comprising a second upstream deflector (48) arranged, at least in part, radially internally to the downstream deflector (54), the downstream deflector (54) extending, at least in part, radially facing the first and second upstream deflectors (47, 48), the first and second upstream deflectors (47, 48) and the downstream deflector (54) defining a double baffle.

2. Turbine according to any one of the preceding claims, wherein the first upstream deflector (47), the second upstream deflector (48), and / or the downstream deflector (54) are cylindrical, at least in part.

3. Turbine according to any one of the preceding claims, wherein the first upstream deflector (47) has a radially external face (47a) which is of a frustoconical shape with a decreasing cross-section in the upstream direction and extending over at least a first longitudinal portion.

4. Turbine according to any one of the preceding claims, wherein the annular space extending between the first and second upstream deflectors (47, 48) is delimited by a radially internal surface (47b) of the first upstream deflector (47), a radially outer surface (48a) of the second upstream deflector (48), and a concave upstream surface of the downstream sealing element (43).

5. Turbine according to any one of the preceding claims, wherein the radially internal surface of the second upstream deflector (48) is connected to an upstream face of the downstream sealing element (43) by a concave rounded portion (49).

6. Turbine according to any one of the preceding claims, wherein the upstream annular cavity (56) of the upstream sealing element (50) is delimited longitudinally by a downstream radial face (36a) of the nozzle guide vane assembly (30) and by a downstream radial wall (60) of the upstream sealing element (50) extending radially outwards from the annular portion (52) of the upstream sealing element (50), and delimited radially by an annular end surface (52a) located at the radially outer end of said annular portion (52) and by a longitudinal wall (62) extending longitudinally upstream from the radially outer end of the downstream radial wall (60), said external annular clearance (58) being formed longitudinally between the downstream radial face (36a) of the nozzle guide vane assembly (30) and the upstream end of said longitudinal wall (62).

7. Turbine according to the preceding claim, wherein said annular end surface (52a) comprises a frustoconical region (52b) which widens in the downstream direction.

8. Turbine according to any one of the preceding claims, wherein the radially internal annular face (34a) of the internal annular platform (34) of the nozzle guide vane assembly (30) has at least one region (34b) of concave shape.

9. Turbine according to any one of the preceding claims, wherein the nozzle guide vane assembly (30) further comprises a radial annular flange (36) extending radially inwards from the internal annular platform (34), the upstream sealing element (50) being attached and fixed to the radial annular flange (36).

10. Turbomachine comprising a high-pressure gas turbine according to any one of the preceding claims.