EP1593814A1 - Feather seal configuration for a gas turbine shroud - Google Patents

Abstract

The assembly has multiple ring and spacer segments. Axial and radial sealing tongues (42, 44) are respectively housed in an axial slot (36) and a radial slot (38) placed oppositely in adjacent side faces of the segments. The axial slot of each segment has depth higher than depth of the radial slot. The axial tongue has width greater than the width of the radial tongue.

Description

Background of the invention

The present invention relates to the general field of fixed ring assemblies of a gas turbine. It aims more particularly fixed ring assemblies of a high pressure turbine turbomachines consisting of a plurality of joined segments end to end with interposition of sealing tabs.

In a gas turbine, for example a high-pressure turbine turbomachine, the rotor blades are surrounded by a fixed ring assembly forming an envelope. The fixed ring set so defines one of the walls of the hot gas flow vein from the combustion chamber of the turbomachine and through the turbine.

The fixed ring assembly consists of a turbine ring attached to the turbine housing by means of a spacer. Generally, the ring and the spacer of such a fixed ring assembly are sectorised, ie they each consist of a plurality of segments joined end to end.

The fixed ring assembly thus defined being directly in contact with the hot gases from the combustion chamber, it is necessary to cool the different segments that compose it. In this indeed, air taken from the chamber bottom circulates in a circuit of cooling arranged in each segment of the ring assembly fixed and is evacuated in the vein of gas flow upstream of the vanes movable turbine.

It is also necessary to ensure a seal between adjacent segments of the fixed ring assembly to prevent leakage particularly damaging to the proper cooling of these segments. For this purpose, it is known to interpose tabs sealing between neighboring segments. Such tongues are generally housed in axial and radial slots opposite each other in the adjacent side faces of the segments. They allow thus to obstruct the existing game between two adjacent segments in order to limit air leakage irrespective of the thermal expansion experienced by segments.

The radial and axial slots in which are housed the sealing tabs are usually machined so that they are joined, ie they communicate with each other. This arrangement is made necessary by the fact that the tabs must cover a maximum surface of the lateral faces segments for optimum sealing.

In practice, however, it is noted that such an arrangement slots generate significant air leaks at the junction between the axial and radial slots. These leaks are illustrated in Figure 5. In this figure, two segments 100, 100 'are partially represented. of the fixed ring assembly each provided with an axial slot 102, 102 'and a radial slot 104, 104 '. Sealing tabs 106, 108 are housed respectively in the axial and radial slots. The game 110 existing between the tabs and the slots is due to the fact that, as segments are exposed to hot gases from the chamber of combustion, they undergo thermal expansions and contractions which reverberate at the level of the game 112 existing between the two segments adjacent.

Due to the pressure distribution in the circuit of cooling the segments 100, 100 ', air leaks appear at level of the junction of the axial slots 102, 102 'and radial 104, 104' (These leaks are represented in hatched lines in the figure). Such leaks are particularly penalizing for the cooling of segments and for the efficiency of the turbine.

Object and summary of the invention

The present invention therefore aims to overcome such drawbacks by proposing a fixed-ring gas turbine ring assembly whose segments that constitute it have a particular geometry of the slots and sealing tabs to reduce leakage between two adjacent segments.

For this purpose, there is provided a fixed ring assembly forming rotor casing of a gas turbine, fixed ring assembly having a plurality of segments including adjacent side faces are placed end to end with the interposition of sealing means, the sealing means comprising at least one sealing tongue axial and at least one radial sealing tongue housed respectively in at least one axial slot and at least one slot radially opposite the adjacent side faces of the segments, the radial slot opening at least at one of its ends in the axial slot, characterized in that the axial slot of the faces sides of each segment has a depth greater than that of the radial slot and in that the axial sealing tongue presents a width greater than that of the radial tongue.

The axial sealing tongue housed in a slot more depth allows to cover the leakage sections observed in the art prior. In this way, it is possible to reduce air leakage between two adjacent segments which improves their cooling. AT identical cooling, it is also possible to reduce the flow of air required for cooling, and therefore to increase the efficiency of the turbine.

Another advantage of the invention lies in the fact that this removal of these air leaks without additional parts (angled type) damaging the mass of the whole, does not require no significant changes to the slots and sealing tabs and does not involve maintenance issues.

The fixed ring assembly may constitute a turbine ring high pressure of a turbomachine. In this case, each segment of ring may comprise, at its side faces, two slots axially disposed on the inner and outer wall side and in which axial tabs are housed, and two radial slots arranged side of upstream and downstream walls and in which are housed tabs radials.

The fixed ring assembly may also constitute a spacer on which is fixed the high-pressure turbine ring of the turbine engine. In this case, each spacer segment may comprise, at its lateral faces, an axial slot in which is housed an axial tongue, and at least three radial slots, two of which are housed on the side of its upstream and downstream walls and in which are housed radial tongues.

The present invention also aims at a segment for gas turbine fixed ring assembly as previously defined.

Brief description of the drawings

• la figure 1 est une vue en coupe longitudinale d'un ensemble à anneau fixe de turbine haute-pression de turbomachine selon l'invention ;
• la figure 2 représente en perspective un segment d'entretoise de l'ensemble à anneau fixe de la figure 1 ;
• la figure 3 illustre en perspective et partiellement en écorché deux segments d'entretoise de la figure 2 réunis bout à bout ;
• la figure 4 est une vue en coupe selon IV-IV de la figure 3 ; et
• la figure 5, décrite précédemment, illustre les problèmes de fuites rencontrés dans un ensemble à anneau fixe de l'art antérieur.

Other features and advantages of the present invention will emerge from the description given below, with reference to the accompanying drawings which illustrate an embodiment having no limiting character. In the figures:

• Figure 1 is a longitudinal sectional view of a stationary ring assembly of turbomachine high-pressure turbine according to the invention;
• Figure 2 is a perspective view of a spacer segment of the fixed ring assembly of Figure 1;
• Figure 3 illustrates in perspective and partially severed two spacer segments of Figure 2 joined end to end;
• Figure 4 is a sectional view along line IV-IV of Figure 3; and
• Figure 5, previously described, illustrates the leakage problems encountered in a fixed ring assembly of the prior art.

Detailed description of an embodiment

In connection with FIG. 1, a high-pressure turbine of turbomachine 2, of longitudinal axis X-X, consists in particular of a a plurality of rotor blades 4 arranged in the vein ring 6 of hot gas flow from the chamber of combustion (not shown). A plurality of fixed blades 8 forming high pressure dispenser are also arranged in the vein 6, upstream of the blades 4 with respect to the direction flow of gases.

The blades 4 are surrounded by a ring assembly fixed 12 forming envelope. This fixed ring set consists of a turbine ring attached to a casing 14 of the turbine via of a plurality of spacer segments 18. More particularly, the turbine ring is composed of a plurality of ring segments 16 gathered end to end. For example, there can be two segments ring 16 mounted on a single spacer segment 18.

The fixed ring assembly 12 thus defined comprises a circuit of air circulation for cooling the ring segments 16 and of spacer 18 which are exposed to the hot gases from the chamber of combustion.

To do this, the fixed ring assembly 12 is provided with a circuit cooling. A hole 20 is drilled in the upstream radial wall 22a of each spacer segment 18 and opens into a cavity 24 formed between the housing 14 and the spacer segment 18. The distributed air in this cavity 24 comes from a sample taken in the bottom of chamber and then feeds a cooling circuit of the segment spacer 18 and ring segment (s) 16 mounted thereon. The air is finally discharged into the flow line 6 of the hot gases, upstream of the blades 4 of the turbine.

Moreover, like the ring and the spacer of the set 12 fixed ring are sectorized, it is necessary to limit air leaks between two segments 16, 18 adjacent.

For this purpose, sealing barriers are interposed between two adjacent segments of ring 16 and spacer 18. These barriers consist of sealing tabs housed in axial slots and radially opposite each other in the adjacent lateral faces of the segments 16, 18.

By axial slots, it is meant that these slots extend substantially axially, ie along the longitudinal axis X-X of the high-pressure turbine 2. Similarly, by radial slots, it is understood that these slots extend substantially radially, that is to say according to a direction perpendicular to the longitudinal axis X-X.

Thus, each ring segment 16 is provided with at least one axial slot 26 and at least one radial slot 28 made on its faces lateral 30.

In FIG. 1, the lateral faces 30 of the ring segment each comprise two axial slots 26 and two radial slots 28. The axial slots 26 are for example arranged on the side of the inner walls 32a and outer 32b of the ring segment 16. As for the radial slots 28, they are for example positioned on the side of the upstream axial walls 34a and downstream 34b of segment 16.

Such a distribution of the axial 26 and radial slots 28 allows thus to the sealing tabs to cover a large area of side faces 30 of the ring segment 16 to ensure a seal optimal between two adjacent ring segments.

Moreover, it follows from this optimal distribution that the two radial slots 28 open at both ends into the slots 26. One can also imagine that the radial slots 28 open into the axial slots only at one end.

Similarly, each spacer segment 18 is provided with at least an axial slot 36 and at least one radial slot 38 made on its side faces 40.

In FIGS. 1 and 2, each lateral face 40 of the segment spacer 18 comprises for example an axial slot 36 and three slots radial 38, two of which are arranged on the side of its upstream axial walls 22a and downstream 22b.

Because of the need to achieve an optimal distribution of axial and radial slots 38 over the entire surface of the lateral faces 40 of the spacer segment 18, two of the radial slots 38 open at one of their ends in the axial slot 36.

In the axial slots 26, 36 and radial 28, 38 segments of ring 16 and spacer 18 are fitted with sealing tabs that partially obstruct the existing game between two adjacent segments to limit air leakage.

However, air leaks appear at the junction between some of these axial and radial slots. In particular, leaks occur develop for the ring segments 16, at the junctions A and A '(FIG. 1) between the two radial slots 28 and the axial slot 26 arranged on the side of the outer wall 32b. Similarly, leaks are observed for the spacer segments 18, at the junctions B and B '(FIG. 1) between two of the radial slots 38 and the axial slot 36.

To limit such leaks, it is intended, in accordance with the invention, that the axial slot (s) 26, 36 of the lateral faces 30, 40 of each ring segment 16 and spacer 18 has a depth greater than that of the radial slot (s) 28, 38 and that the sealing tab housed in each axial slot presents a width greater than that of the sealing tongue housed in each radial slot.

By slot depth, we mean the machining depth of the slot in the material of the segment concerned. By tongue width, we hear the distance of the tongue between its two edges side by which the tongue is positioned in the slots.

This characteristic is illustrated in particular in FIG. 2, which represents a spacer segment 18. In this figure, it should be noted that at the junction B, the axial slot 36 has a depth P1 greater than the depth P2 of the slot radial 38 which opens into the axial slot 36. Of course, this characteristic also applies to the junction B 'of the spacer segment 18, as well as the junctions A and A' of the ring segment 16 (Figure 1) .

In FIG. 3, two adjacent spacer segments 18, 18 ' end-to-end are represented, as well as the B-junction between slots axial 36 and radial 38. An axial sealing tab 42 is housed in the axial slot 36 and a radial sealing tongue 44 is housed in the radial slot 38.

In FIGS. 3 and 4, it will be noted that the axial sealing tongue 42 has a width L1 greater than the width L2 of the radial sealing tongue 44. Of course, although not illustrated, this characteristic relating to the width sealing tabs also apply to the junction B 'of the spacer segment 18, as well as to the junctions A and A' of the ring segment 16 (FIG. 1).

Thus, the air leaks at the junctions between axial slots 26, 36 and radial 28, 38 ring segments 16 and spacer 18 can be avoided. In particular, concerning spacer segments 18, it will be noted that the pressure of the air feeding their circuit of cooling is greater on the side of cavities 24 (Figure 1) than on the side of the flow vein 6. Air flowing between two segments 18, 18 'adjacent (Figure 3) will then tend to stick the tongue axial seal 42 against the bearing surfaces of the axial slot 36 on which it rests, thus preventing air from escaping through the radial slots 38 at their junction with the axial slot. In this way, any risk leakage is avoided.

Of course, this feature also applies to ring segments 16 for which the air pressure feeding their cooling circuit is more important on the side of their wall external 32b that the side of their inner wall 32a (Figure 1).

Referring to Figure 4, it will also be noted that a clearance J exists between the tabs 42, 44 and the axial slots 36 and radial 38 in which they are housed. This clearance J is necessary to take into account the thermal expansion and contraction experienced by the adjacent spacer segments 18, 18 '(and, by analogy, the ring segments).

The fixed ring assembly as described constitutes an element a turbomachine high-pressure turbine. Of course, this invention applies to any other type of segmented ring of which it is necessary to ensure a seal between adjacent segments, as for example a high-pressure turbomachine distributor.

Claims (6)

A fixed ring assembly forming a rotor envelope of a gas turbine, the fixed ring assembly having a plurality of segments (16, 18) whose adjacent side faces (30, 40) are butt-fitted with interposing means sealing means comprising at least one axial sealing tongue (42) and at least one radial sealing tongue (44) housed respectively in at least one axial slot (26, 36) and at least one radial slot (28, 38) formed opposite the adjacent side faces of the segments, the radial slot (28, 38) opening at at least one of its ends in the axial slot (26, 36), characterized in that the axial slot (26, 36) of each segment (16, 18) has a depth ( P1 ) greater than that ( P2 ) of the radial slot (28, 38) and that the axial tongue of sealing (42) has a width ( L1 ) greater than that ( L2 ) of the radial tongue (44). Assembly according to Claim 1, characterized in that it constitutes a high-pressure turbine ring of a turbomachine. Assembly according to claim 2, characterized in that each ring segment (16) comprises, at its lateral faces (30), two axial slots (26) arranged on the inner (32a) and outer (32b) side walls. and in which are accommodated axial tongues, and two radial slots (28) disposed on the upstream wall side (34a) and downstream (34b) and in which are accommodated radial tongues. Assembly according to Claim 1, characterized in that it constitutes a high-pressure turbine spacer of a turbomachine. Assembly according to claim 4, characterized in that each spacer segment (18) comprises, at its lateral faces (40), an axial slot (36) in which is housed an axial tongue (42), and at least three radial slots (38), two of which are housed on the side of its upstream (22a) and downstream (22b) walls and in which radial tabs (44) are housed. Segment (16, 18) for fixed ring assembly (12) of a gas turbine according to any one of claims 1 to 5.

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