EP1840331B1 - Turbomachine nozzle - Google Patents

Description

The invention relates to a set of a blade and a cooling jacket of the blade, in a distributor of a turbomachine.

A turbomachine comprises rotor stages - compressor and / or turbine - separated by distributors. The latter comprise a plurality of vanes, intended to guide the flow of gas. The vanes extend in the gas vein between an outer shell and an inner shell. Due to the temperature of the gases flowing through them, in particular in the distributors separating the turbine stages, the vanes are subjected to very severe operating conditions; it is therefore necessary to cool them, usually by forced convection or by air impact, inside the blades.

For air-impact cooling, multi-perforated longitudinal liners can be used. These jackets are generally made of a hot-resistant alloy, for example based on Chromium (Cr), Cobalt (Co) and Nickel (Ni). Such a shirt is slid longitudinally into the cavity of a blade. It is supplied with cooling air at the outer shell. Due to the pressure difference between the inner cavity of the liner and the cavity between the liner and the blade, a portion of the air is projected, via the perforations of the liner, against the inner wall of the liner. dawn, thus ensuring its cooling. This air is then evacuated along the trailing edge of the blade by calibrated perforations in the gas vein. The remainder of the air is discharged through the inner shroud to other parts of the engine to be cooled, such as the turbine disk or bearings.

The dawn cavity provides two openings in the inner and outer platforms. The liner is generally attached externally to the wall of the outer opening by soldering or welding, for example. This gives a kind of brazed slide connection. The liner is further guided, at its other end portion, in the inner opening, whose wall slid form for this purpose and which makes it possible to compensate for the differential expansions between the liner and the blade.

According to an advantageous configuration, the jacket comprises, on its external side, a flange, brazed on the dispenser. A collared shirt is known from the document US 2002/0028133 . Compared to the shirts whose outer portion is brazed at a slide, a collarless shirt presents various advantages: it allows a simple mounting of the liner in the blade, with a determined radial positioning, and the brazing of the collar on the distributor is easy to implement and can be visually controlled.

It is essential to ensure a good tightness of the shirt on the dawn, at the level of the collar. Indeed, if this is not the case, leaks occur in one direction or the other and are detrimental in both cases. Thus, if the pressure on the outer side of the outer shell of the distributor is greater than the pressure in the cavity between the jacket and the blade, air will enter the latter cavity; This results in an increase in the pressure outside the jacket, the air being less likely to be projected from the inside of the shirt against the blade and the cooling of the latter is therefore less well ensured. Conversely, if the pressure is greater in the cavity between the jacket and the blade than on the outer side of the outer ring of the dispenser, the air, which was used to cool the dawn and therefore warmed , escapes from the latter cavity and deteriorates the cooling, provided elsewhere, the outer side of the dispenser. Some of the above problems could be overcome by increasing the volume of the cooling flow at this level; however, increasing the volume in one place means decreasing it to another.

None of these situations is satisfactory and it is necessary to have a satisfactory sealing connection at the flange.

Such a connection can be obtained by brazing. However, even if such brazing can be visually controlled on the flange, there is a risk of incomplete or failed brazing, leaving room for a possible air leak.

The documents EP-A-1626162 , BE 685,320 and FR-A-2 094 033 describe different turbomachine distributors.

The present invention aims to provide an assembly of a blade and a cooling collar jacket of the blade in which the sealing of the fastener at the collar is provided.

Thus, the invention relates to an assembly of a blade and a cooling jacket of the blade, here in a distributor of one according to claim 1, the blade comprising a central cavity, with at least one first opening, in which the liner extends, the liner having a flange fixed to the rim of the opening, characterized in that it comprises, at
proximity of the flange, a peripheral interposition element between the wall of the jacket and the wall of the opening.

Such an interposition element creates a pressure drop. By loss of load is meant not only a conventional pressure loss created by a narrowing of the passage section of a flow or a baffle, but also an pressure drop - infinite - created by a seal.

Thanks to the combination of a flange fixed to the rim and an interposition element near this collar, the air does not leak - at least any leaks are not significant - and a possible solder gap n is not problematic. Indeed, the flange being fixed, any air leakage could be done only by a small clearance between the flange and the flange. However, such leakage by a small gap is not possible because of the interposing element creating a pressure drop, neither in one direction nor in the other.

In solving a specific problem, the applicant has also discovered that it was possible to greatly simplify the assembly of the assembly. Indeed, the presence of an interposing element near the collar has a very effective effect on air leakage, so it is no longer necessary to perfectly braze the flange on the distributor. It is therefore possible to simply fix, by spot welding between the flange and the flange, the jacket on the blade, the leaks being avoided thanks to the interposing element. The time and cost savings are considerable in comparison with soldering over the entire periphery of the collar.

The interposer may serve a baffle and / or seal function.

Preferably, the central cavity providing a second opening, the liner has an end portion, opposite the flange, which is guided in the second opening, the wall forming a slide for this purpose.

Advantageously in this case, a clearance is provided between the jacket and the wall of the first opening.

According to a first particular embodiment, the interposing element comprises a peripheral ring forming a baffle.

According to a second particular embodiment, the interposing element comprises an elastic lamella.

According to a third particular embodiment, the interposing element comprises a peripheral spring.

• on insère la chemise dans la cavité de l'aube, par la première ouverture, de manière à placer un élément d'interposition périphérique entre la paroi de la chemise et la paroi de la première ouverture et
• on soude par points la collerette sur le rebord.

The invention also relates to a turbomachine distributor, comprising a plurality of assemblies as presented above, and a turbomachine comprising such a distributor. A simplified method, which has been presented above, for mounting a a cooling jacket in a hollow turbomachine distributor blade, to form the assembly of the invention, the blade having a central cavity, with at least a first opening, and the jacket comprising a collar, wherein:

• inserting the liner into the blade cavity, through the first opening, so as to place a peripheral interposing element between the liner wall and the wall of the first opening and
• the collar is dotted by points on the rim.

• on arase la collerette de la chemise, jusqu'au rebord, sans araser l'élément d'interposition,
• on enlève la chemise du corps central de l'aube, par l'ouverture,
• on rapporte une nouvelle collerette sur la chemise,
• on insère la chemise, avec la nouvelle collerette, dans la cavité de l'aube, par la première ouverture, de manière à placer l'élément d'interposition périphérique entre la paroi de la chemise et la paroi de la première ouverture et
• on fixe la collerette sur le rebord.

Thanks to the use of the interposing element of the invention, the use of a flanged jacket can be implemented industrially, by controlling the risk of air leakage. It is thus possible, in case of repair of a distributor and thus of the whole of the invention, to dismantle and reassemble the jacket of the blade, to implement a method in which:

• the collar of the shirt is cut to the brim, without striking the interposition element,
• we remove the shirt from the central body of the dawn, through the opening,
• there is a new collar on the shirt,
• the jacket, with the new flange, is inserted into the cavity of the blade, through the first opening, so as to place the peripheral interposing element between the wall of the jacket and the wall of the first opening and
• we fix the collar on the rim.

Such a method has the advantage of its simplicity of implementation.

It is noted that the invention is particularly applicable to an assembly whose jacket is open on both sides, the end portion opposite the flange being guided in an opening whose wall form slider, but it goes without saying that the The invention also applies to an assembly whose jacket is open only on the side of the collar, without necessarily being guided in a slide at its other end.

• la figure 1 représente une vue en perspective schématique d'une portion du distributeur de l'invention ;
• la figure 2 représente une vue en coupe schématique de l'ensemble de l'invention ;
• la figure 3 représente une vue en coupe schématique de l'élément d'interposition selon une première forme de réalisation de l'ensemble de l'invention ;
• la figure 4 représente une vue en coupe schématique de l'élément d'interposition selon une deuxième forme de réalisation de l'ensemble de l'invention et
• la figure 5 représente une vue en coupe schématique de l'élément d'interposition selon une troisième forme de réalisation de l'ensemble de l'invention.

The invention will be better understood with the aid of the following description of the preferred embodiments of the invention, with reference to the attached plates, in which:

• the figure 1 is a schematic perspective view of a portion of the dispenser of the invention;
• the figure 2 is a schematic sectional view of the assembly of the invention;
• the figure 3 is a schematic sectional view of the interposing element according to a first embodiment of the whole of the invention;
• the figure 4 is a schematic sectional view of the interposing element according to a second embodiment of the whole of the invention and
• the figure 5 is a schematic sectional view of the interposer according to a third embodiment of the whole of the invention.

With reference to Figures 1 and 2 , a distributor 1 comprises a plurality of stationary vanes 2, forming a grid that straighten the flow of air passing through the gas stream of the engine. The arrow of the figure 2 represents the flow direction of the gas, from upstream to downstream. This vein is delimited by an outer shell 3 and an inner shell 4, supporting the blades 2.

Each blade 2 is hollow and comprises a central cavity 5 within which is inserted a cooling jacket 6. On the figure 1 , the leftmost cooling jacket 6 has been shown partially out of the cavity 5 of its receiving blade 2, to help understanding the shape of the various elements. We will describe later a particular set of a dawn 2 and a jacket 6, it being understood that all the sets 2, 6 of the distributor 1 are similar in their structure.

The cavity 5 of the blade 2 has an external opening 7 and an internal opening 8, respectively in the outer and inner ring 3 4 of the distributor. To be mounted in the blade 2, the jacket 6 is inserted through the external opening 7.

The jacket 6 comprises a hollow body 9 pierced, here on the upstream side, with a plurality of orifices 10 through which is projected, against the inner wall of the blade 2, air fed into the body 9 of the jacket 6 at a supply pipe 11 located near the outer opening 7 of the blade 2. In this case, the inner wall of the blade 2 comprises, facing these orifices 10, a plurality of disruptive fins 11, for better cooling of the blade 2, in known manner. The liner 6 further includes, on its outer surface, a plurality of bosses 12 - also shown schematically on the figure 2 , although the latter is in section - whose function is to allow the positioning of the liner 2 in the cavity 5 of the blade 2.

The liner 6 comprises, on the external side, a flange 13. This flange 13 is here obtained by forming the sheet forming the liner 6. It could also be reported on the latter. The flange 13 is arranged to bear on the flange 14 formed by the distributor around the outer opening 7 formed by the cavity 5 of the blade 2. The flange 13 is fixed to this rim 14, by soldering or welding, as will be detailed below.

On its internal side, the liner 6 comprises an end portion 15, in the extension of its body 6, inserted into the internal opening 8 formed by the blade 2, whose wall 8 'slider form to guide this portion of end 15, in known manner. Due to this freedom of movement, the differences in thermal expansion between the blade 2 and the liner 6 can be absorbed.

The assembly of the blade 2 and the liner 6 further includes, near the collar 13, an interposing element 16. The function of the interposing element 16 is to create a pressure drop in the vicinity collar 13, to avoid or at least limit air leakage, in one direction or the other. This interposing element 16 is peripheral around the jacket 6. It can be secured to either the jacket 6 or the distributor 1. It is located at close to the flange 13, that is to say that it is in an area in which its effects can be combined with those of the collar 13. In other words, the pressure losses generated by the interposition element 16 must be sufficient to prevent air leakage through the possible gaps between the flange 13 and the flange 14. In this case, the interposing element 16 is located, under the flange 13, at the wall 7 'of the external opening 7, which is extended by the flange 14 where the flange 13 is fixed.

Three particular embodiments of the interposition element will now be described, in relation to the Figures 3 to 5 . In these three embodiments, the interposing element 16 is shown integral with the jacket 6, but it goes without saying that the skilled person will transpose without difficulty to an interposing element 16 integral with the wall 7 'of the outer opening 7 formed by the blade 2. In the three figures, the interposition element is designated by the same reference 16.

With reference to the figure 3 , the interposing element 16 comprises, according to a first embodiment, a peripheral ring 16, or peripheral strip, fixed around the jacket 6, under the collar 13. This ring 16, metal, is arranged to extend radially on a distance less than that separating the wall of the liner 16 from the wall 7 'of the external opening 7 at this point, preferably flush with the latter. By radially, is meant radially with respect to the overall axis of the liner, that is to say with respect to its longitudinal direction between the flange 13 and the end portion 15. The pressure loss thus created is sufficient to avoid or limit satisfactorily leaks between the flange 13 and the flange 14. In this embodiment, the interposing element forms a baffle, for the air flows, over the entire periphery of the jacket 6.

With reference to the figure 4 , the interposing element 16 comprises, according to a second embodiment, a strip 16 peripheral, having a certain elasticity. This lamella 16, metal, has a radial dimension which may possibly be greater than the average distance between the wall of the liner 6 of the wall 7 'of the outer opening 7 at this location. When inserting the liner 6 in the opening 7, it is not detrimental that the liner 6 is not perfectly centered with respect to the opening 7. The sipe 16 bears on the wall portions 7 ' of opening 7 whose shirt 6 is closer and elastically bends outwards during the introduction of the liner 6, thus compensating for the play. It may also be provided that the dimension of the sipe 16 is such that the sipe comes into contact with the wall 7 'of the opening 7 over the entire periphery of the liner 6, thereby forming a seal.

With this embodiment, it is possible to provide a clearance between the liner 6 and the wall 7 'of the outer opening 7. Such a game allows a simpler mounting of the liner 6. When introduced into the blade 2, the liner 6 is guided, at its end portion 15, in the slide 8 located on the inner side of the blade 2. This guidance is done freely because it is not hindered by a defect of alignment of the inner opening 8 and the outer opening 7, due to the presence of a game at the latter. Such a game is not detrimental to the assembly because it is compensated by the elasticity of the blade 16. Thus, the blade 16 can pass through the opening 7 and fulfill its function of limiting leaks. With the blade 16, the presence of a game does not involve leaks; the game and the advantages that it implies are therefore authorized by the presence of the slat 16.

In this embodiment, the interposing element 16 can either perform the function of a baffle, or perform the function of a seal, or both, depending on whether it touches the wall 7 'of external opening 7 (seal function) or not touching it (baffle function). In all cases, it induces a loss of load at its level. When it performs both functions, the sealing element 16 fills on certain portions - where the strip 16 is not in contact with the wall 7 'of the opening 7 - a baffle function and on others portions - where the blade 16 is in contact with the wall 7 'of the opening 7 - a seal function.

With reference to the figure 5 , the interposing element 16 comprises, according to a third embodiment, a peripheral spring 16. This spring 16, metal, comprises a blade, whose edges are fixed to the surface of the jacket 6, the blade having a section U-shaped flared between the two fixed edges. As above, such a spring member 16 compensates for a possible play at the outer opening 7 and may, depending on the areas of the jacket 6, perform a seal function and / or baffle, depending on whether the spring 16 is in contact or not with the wall 7 'of the opening 7.

The interposing element has been presented according to three preferred embodiments, but it goes without saying that it is possible to envisage other structures, insofar as they extend between the wall of the jacket 6 and that of the opening 7 to create a pressure drop. We could also combine several elements of interposition and create a kind of labyrinth seal.

• on insère la chemise 6 dans la cavité 5 de l'aube 2, par l'ouverture externe 7 et
• on soude par points la collerette 13 sur le rebord 14.

Thanks to the interposition element 16, the air leaks at the flange 13 are, if not completely avoided, at least largely limited. The flange 13 can be fixed to the flange 14 by soldering. In such a case, a possible gap in solder material is not unacceptable because the interposing element prohibits or limits leaks. The use of an interposing element also makes it possible to implement a particular method of mounting the jacket 6 in the blade 2, in which:

• the jacket 6 is inserted into the cavity 5 of the blade 2, through the external opening 7 and
• the flange 13 is welded in points on the flange 14.

Such a mounting method is very fast and inexpensive. Indeed, instead of being soldered over its entire circumference, the collar 13 is simply welded in a plurality of points (usually referred to as "pointing"). The assembly is viable in operation because the weld points are sufficient to ensure the holding of the liner 6 on the blade 2, while the interposing element 16 seals or at least the limitation of leaks at the It should be noted that the point-welding fastening between the liner 6 and the flange 14 is sufficiently strong because the mechanical stresses at the level of a distributor liner are not too great.

Thus, the method of attachment can freely be adapted according to mechanical constraints on the one hand, time constraints and mounting cost on the other hand. This freedom of adaptation is conferred by the presence of an interposing element between the wall of the liner 6 and the wall 7 'of the opening 7, which makes it possible to choose between brazing and spot welding.

• on arase la collerette 13 de la chemise 6, jusqu'au rebord 14, sans araser l'élément d'interposition 16,
• on enlève la chemise 6 du corps central 5 de l'aube 2, par l'ouverture 7,
• on rapporte une nouvelle collerette sur la chemise 6,
• on insère la chemise 6, avec la nouvelle collerette, dans la cavité 5 de l'aube 2, par l'ouverture externe 7, de manière à placer l'élément d'interposition 16 périphérique entre la paroi de la chemise 6 et la paroi 7' de l'ouverture 7 et
• on fixe la collerette 13 sur le rebord 14.

In case of repair of the distributor 1, it is possible, for each set of a blade 2 and a jacket 6, to implement a repair method in which:

• the flange 13 of the jacket 6 is flared to the flange 14, without striking the interposition element 16,
• the liner 6 of the central body 5 of the blade 2 is removed through the opening 7,
• we report a new collar on the shirt 6,
• the liner 6, with the new flange, is inserted into the cavity 5 of the blade 2, through the external opening 7, so as to place the peripheral element 16 between the wall of the liner 6 and the wall 7 'of opening 7 and
• the flange 13 is fixed on the flange 14.

The step of leveling the flange 13 may be implemented by machining, or preferably by ripping by an EDM machine (this type of routing is well known to those skilled in the art under its English acronym EDM, meaning "Electro-Discharge Machine"). The routing to be operated is very quickly implemented, because it suffices to break down the flange 13, which does not have, in general, a very large thickness. It is simple then, once the liner 6 removed from the central cavity 5 of the blade 2, to report a flange on the body 9 of the liner 6, for example by welding, to reform a new liner. The latter can then be inserted again in the central cavity 5 of the blade 2.

Claims (9)

1. Turbine engine nozzle (1) comprising a plurality of assemblies of a vane (2) and a cooling jacket (6) for the vane (2), in each assembly the vane (2) being supported by an outer shroud (3) and an inner shroud (4), the vane (2) comprising a central cavity (5) providing, in the outer shroud (3), an outer opening (7) in which the jacket (6) runs, the jacket (6) being of longitudinal axis and comprising a flange (13) fastened to a shoulder (14) formed by the nozzle (1) around the outer opening (7), the shoulder (14) comprising a longitudinal wall (7'), the nozzle (1) being characterised in that it comprises in each assembly, close to and away from the flange (13), an interposition element (16) running along the entire periphery of the jacket (6) between the wall of the jacket (6) and the longitudinal wall (7') of the shoulder (14).
2. Nozzle (1), according to claim 1, in which the interposition element (16) is a baffle or seal.
3. Nozzle (1), according to either of claims 1 or 2, in which, the central cavity (5) providing an inner opening (8), the jacket (6) comprises an end portion (15), opposite the flange (13), which is guided in the inner opening (8), the wall (8') of which forms a slide for this purpose.
4. Nozzle (1), according to claim 3, in which a clearance is provided between the jacket (6) and the longitudinal wall (7') of the shoulder (14).
5. Nozzle (1), according to any one of claims 1 to 4, in which the interposition element comprises a peripheral ring (16) forming a baffle.
6. Nozzle (1), according to any one of claims 1 to 4, in which the interposition element comprises an elastic strip (16).
7. Nozzle (1), according to any one of claims 1 to 4, in which the interposition element comprises a peripheral spring (16).
8. Nozzle (1), according to any one of claims 1 to 7, in which the flange (13) is fastened to the shoulder (14) by spot welding.
9. Turbine engine comprising a nozzle (1) according to any one of claims 1 to 8.

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