EP1455055A1 - Turbomachine with cooled shroud segments - Google Patents

Abstract

The turbomachine has cooled ring sectors (108) interposed between a turbine casing (102) and a rotor (4). Each sector has a main cooling cavity (162) and is mounted on the casing by a fixing unit (132). The fixing unit has a clamping screw (134) positioned radially and ensuring pressing of the sector against the casing. The screw is traversed by a cooling air passage (174) communicating with the cavity.

Description

TECHNICAL AREA

The present invention relates so general to a ring sector turbomachine cooled.

More specifically, the invention relates to a turbomachine comprising a casing, a rotor and that a plurality of cooled ring sectors interposed between the casing and the rotor, each of these ring sectors being provided with at least one cavity of cooling.

Ring areas can indifferently to be turbine ring sectors, preferably a high pressure turbine, or compressor ring areas. As such, it is clarified that the invention finds an application not exclusive but more specific when relates to a turbine of the turbomachine, in the since the significant thermal stresses surrounding require the presence of such areas ring cooled.

STATE OF THE PRIOR ART

Referring to Figure 1, it is partially shown a portion of high turbine pressure of a turbomachine 1 of the prior art, such than that described in document FR-A-2 800 797.

As can be seen in this figure, the high pressure turbine comprises a turbine casing 2, as well as a rotor 4, of which only one end of the blades 6 is shown.

Furthermore, the turbine is provided with a plurality of cooled ring sectors 8 mounted on the turbine casing 2, and forming a ring around the blades 6 of the rotor 4.

In order to assemble the sectors ring 8 on the casing 2, the latter comprises all first, on the upstream side, a hook 10 intended to cooperate with a hook 12 belonging to the sector ring 8. So, once hooks 10 and 12 are nested, they allow the pivoting of the sector ring 8 until it comes up against downstream against the turbine casing 2, by bringing the ledges 14 and 16.

Tightening in axial direction of the sector ring 8 on the casing 2 is then provided by a tenon 18 secured to a downstream part of this sector, the tenon 18 being located upstream relative to the flange 14 of the ring sector 8, and being located on the side of a inner chamber 20 partially delimited by the turbine housing 2.

Still with reference to FIG. 1, the tenon 18 is retained by a mortise 22, formed by through the edge 16 of the casing, as well as by an elastic tab 24 which once allows mounting performed, to remove the axial play of the lug 18.

In addition, maintaining direction tangential of each ring sector 8 with respect to to the turbine casing 2 is carried out using a staple 26, the branches of which serve to grip the edges 14 and 16, these being respectively provided with notches opposite 28 and 30 between which can be slid the core of clip 26, pushing it upstream.

Therefore, the mounting system of the ring sectors on the housing is very design complex, and therefore generates relatively low costs important.

In addition, the tenon / mortise assembly used work between the casing and each ring sector does not allow to obtain a perfect seal, so that leaks can be observed between these two elements, naturally at the expense of cooling ring areas and thermal protection of the turbine housing.

In addition, the inner chamber 20 is supplied with cooling air via one or more cooling orifices 27 practiced through in the casing 2, this cooling air being for example taken from the level of one of the compressors (not shown) of the turbomachine 1. After the introduction of air from cooling in the inner chamber 20, this one passes through a perforated wall 23 of the ring sector 8 in order to enter a cooling cavity 25 provided in the latter.

Thus, it is clear from the above that the means required to ensure the delivery of air to the cooling cavity, such as the cooling orifices provided in the casing, further complicate the design of the turbomachine.

STATEMENT OF THE INVENTION

The invention therefore aims to provide a turbomachine comprising a casing, a rotor and that a plurality of cooled ring sectors interposed between the casing and the rotor, the turbomachine at least partially remedying the disadvantages mentioned above relating to the achievements of art prior.

To do this, the invention relates to a turbomachine comprising a casing, a rotor and that a plurality of cooled ring sectors interposed between the housing and the rotor, each sector ring including a cooling cavity main and being mounted on the turbine housing by by means of fixing means. according to the invention, the fixing means comprise a screw clamping position substantially radially and ensuring the plating of the ring sector against the casing, this clamping screw being traversed by a cooling air passage communicating with the main cooling cavity of the sector ring.

Advantageously, the fixing means have a design greatly simplified compared to that means presented previously, insofar as they no longer require hooks or staples extremely precise dimensions, but on the contrary are essentially consisting of a simple clamping screw.

In addition, the clamping screw arranged radially provides axial positioning and very precise tangential of the ring sector compared to the turbine housing, thus considerably limiting cooling air leaks between these elements. In this way, the turbine housing is better protected thermally, and the ring sectors can be completely satisfactorily cooled.

Also, the fixing means used in the invention provide simplicity of assembly as well as a reduced cost compared to those of art described above and shown on the figure 1.

Furthermore, the fact of providing one or multiple air passages through the screw allows advantageously to combine the fixing means of each ring sector with the means necessary to the supply of cooling air to the cooling cavity of the ring concerned. In effect, with such an arrangement, the cooling air collected at the desired location, such as for example at level of a turbomachine compressor, penetrates in an outer radial end of the air passage, then crosses it until it is ejected by a internal radial end, to then integrate the main cooling cavity and thereby ensure the cooling of the ring sector.

Preferably, for each sector ring, the clamping screw is crossed longitudinally by a single air passage of cooling, which therefore leads in particular to the level of the screw head.

Preferably, for each sector ring, the fixing means comprise a spacer mounted on the housing and crossed by the screw tightening, the spacer ensuring positioning axial and tangential of the ring sector with respect to the casing, as well as the desired pretension. For this do, we can predict that for each sector ring, the spacer has an inside diameter substantially equal to an outside diameter of at least a portion of the clamping screw lying opposite of the spacer, and / or that the spacer has a lower end inserted in a bore provided on the ring area, this lower end having an outer diameter substantially equal to an internal diameter of the bore.

Preferably, for each sector ring, the spacer constitutes a stop for this ring sector, so as to ensure the radial positioning of the latter relative to the casing. So with such a configuration, a simple judiciously arranged spacer on the housing allows to achieve a very precise positioning of the sector ring relative to this housing, as well axially, tangentially than radially.

Preferably, each sector ring has a threaded portion cooperating with the clamping screw, the head of this clamping screw being abutted against an upper end of the spacer. In this regard, note that another solution ensuring the plating of the ring sector against the housing could be to provide that each ring sector has a footprint the interior of which is housed in abutment the head of the clamping screw, the latter cooperating with a nut in abutment against an upper end of the spacer passing through the casing.

On the other hand, each ring sector can have an upstream end as well as an end downstream, the upstream end being in contact with a upstream circular flange belonging to the casing, and the downstream end being in contact with a flange downstream circular belonging to this same casing.

Finally, we can also provide that each ring sector further comprises a cavity of separate secondary cooling of the cavity main cooling by a wall, these cavities main and secondary being superimposed radially.

Other advantages and characteristics of the invention will appear in the detailed description nonlimiting below.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1, déjà décrite, représente partiellement une turbine haute pression de turbomachine selon une réalisation de l'art antérieur,
• la figure 2 représente une vue partielle en coupe longitudinale d'une turbomachine, selon un premier mode de réalisation préféré de la présente invention,
• la figure 3 représente une vue partielle en coupe prise le long de la ligne III-III de la figure 2,
• la figure 4 représente une vue agrandie d'une partie d'une turbomachine similaire à celle représentée sur la figure 2, constituant une alternative au premier mode de réalisation préféré de la présente invention,
• la figure 5 représente une vue partielle et agrandie d'une turbomachine similaire à celle représentée sur la figure 2, constituant une autre alternative au premier mode de réalisation préféré de la présente invention, et
• la figure 6 représente une vue partielle en coupe longitudinale d'une turbomachine, selon un second mode de réalisation préféré de la présente invention.

This description will be made with reference to the accompanying drawings, among which;

• FIG. 1, already described, partially represents a high pressure turbine of a turbomachine according to an embodiment of the prior art,
• FIG. 2 represents a partial view in longitudinal section of a turbomachine, according to a first preferred embodiment of the present invention,
• FIG. 3 represents a partial sectional view taken along line III-III of FIG. 2,
• FIG. 4 represents an enlarged view of part of a turbomachine similar to that represented in FIG. 2, constituting an alternative to the first preferred embodiment of the present invention,
• FIG. 5 represents a partial and enlarged view of a turbomachine similar to that shown in FIG. 2, constituting another alternative to the first preferred embodiment of the present invention, and
• FIG. 6 represents a partial view in longitudinal section of a turbomachine, according to a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to Figures 2 and 3, a turbomachine is partially shown 100, according to a first preferred embodiment of the present invention.

The turbomachine 100 comprises a casing 102 as well as a rotor 4 provided with blades 6. As such, the invention finding a very particular application when applied to a turbine of the turbomachine 100, we will consider in the following the description that the part shown in Figures 2 and 3 corresponds to a high pressure turbine of this turbomachine, and that consequently, the casings 102 and rotor 4 correspond respectively to a housing of turbine 102 and to a turbine rotor 4 provided with blades 6. It is noted that this choice of application of the invention to a turbine, preferably to the turbine high pressure subject to heavy loads will be adopted for all modes of preferred embodiments shown in FIGS. 2 to 6, and described below.

Of course, as indicated previously, the invention could also apply to a compressor of the turbomachine, without depart from the scope of the invention.

Thus, still with reference to Figures 2 and 3, we can see that the turbine includes a plurality of cooled ring sectors 108 mounted on the turbine casing 102 by means fixing 132, the ring sectors 108 forming a ring around the blades 6 of the turbine rotor 4.

In addition, the fixing means 132 have a clamping screw 134 positioned substantially radially with respect to the housing turbine 102. In other words, the clamping screw 134 is arranged so that its longitudinal axis (not shown) is substantially parallel to a radial direction of the turbomachine 100.

To do this, the fixing means 132 include a spacer 136, integrally mounted or with a calibrated clearance on the casing 102 which it crosses, this spacer 136 also called "sleeve of guide ”being traversed by the clamping screw 134 and therefore also having a longitudinal axis positioned substantially radially.

In this first embodiment preferred, the clamping screw 134 has a portion 138, located under the head 140 and opposite the spacer 136, the outside diameter of which is substantially equal to the inside diameter of this same spacer 136. Thus, the clearance between the screw 134 and the spacer 136 being almost zero, the clamping screw 134 is then positioned axially and tangentially very precisely with respect to the turbine casing 102, insofar as it is joined together to the spacer 136, for example by welding, or even mounted with almost zero play.

As such, note that the ring sector 108 has a threaded portion 141 cooperating with the threaded portion 142 of the fixing screw 134. From this way when the ring sector 108 cooperates with the fixing screw 134, it is also positioned axially and tangentially very precisely relative to the turbine casing 102.

Note with reference to Figure 4 that a alternative could also be to provide that to obtain the axial and tangential positioning of the ring sector 108 relative to the casing 102, the spacer 136 has a lower end 136a inserted inside a bore 144 provided on the ring sector 108, the outside diameter of the lower end 136a being substantially equal to the internal diameter of bore 144. With such a layout, it is no longer necessary to plan the identity between the inner diameter of the spacer 136 and the outside diameter of the portion 138 of the clamping screw 134.

Referring again to Figures 2 and 3, it is noted that the head 140 of the screw 134 located radially outwardly relative to the portion threaded 142, abuts against one end upper 136b of the spacer 136. An anti-rotation plate 146 can optionally be inserted between this upper end 136b and the head 140 of the screw 134, so that it can no longer loosen once assembled.

In this regard, it is specified that the operation tightening the clamping screw 134 inside the ring sector 108 causes a radial movement towards outside of the latter, until it comes into contact with the turbine casing 102. As can be see in figure 2, contact is made at level an upstream boss 148 and a downstream boss 150, provided on an upper part of the ring sector 108. So, once the plating is established, the ring sector 108 and the casing 102 form an interior chamber closed 120, the leaks of which are considerably limited compared to those encountered in achievements of the prior art.

Furthermore, it is specified that the lower end 136a of the spacer 136 can also be a stop for the ring sector 108, so as to ensure a very radial positioning precise of the latter with respect to the turbine casing 102, or even a controlled prestress. Well heard, in such a case, the spacer 136 is sized so that when the ring sector 108 abuts against its lower end 136a, the bosses 148 and 150 from this same sector come simultaneously abut against the casing 102.

On the other hand, to further decrease further leakage from the inner chamber 120, the turbine is designed so that the ring sector 108 has an upstream end or upstream edge in contact with an upstream circular flange 152 belonging to the turbine casing 102, as well as a downstream end or downstream edge in contact with a circular flange downstream 154 belonging to this same casing. Note as example, as shown in Figure 2, that the contacts established by the flanges 152 and 154 with sector 108 are preferably plan contacts, belonging to plans substantially perpendicular to a main longitudinal axis (not shown) of the turbomachine 100.

In addition, relatively conventionally, it is noted that the ring sectors 108 are connected to each other through tabs seal 156, limiting gas flow in the axial and radial directions.

In this preferred embodiment of the present invention, each ring sector 108 has an upper wall 158 and a lower wall 160 radially superimposed and defining a cavity main cooling 162, these two walls being indifferently carried out separately then assembled together, or made in one piece.

It is specified that in this first mode of preferred embodiment shown in FIGS. 2 to 4, each ring sector 108 includes no other cooling cavity than the main cavity 162.

To supply air to cooling of the cavity 162, the clamping screw 134 is provided with one or more air through passages cooling 174, preferably only one, which is practiced so as to communicate with this same main cavity 162. Indeed, air from cooling can be taken for example at the level of a turbomachine compressor 100 and then be routed to an outer radial end (not referenced) from passage 174, this outer end being located radially outwardly relative to the turbine casing 102. In addition, insofar as the threaded portion 141 opens directly into the cavity cooling 162 so it's clear that a internal radial end (not referenced) of the passage 174 is in communication with this same cavity 162, from so the air ejected from this radial end internal can then penetrate inside the cavity main cooling 162, and ensures the ring sector 108 cooling. illustrative, the cooling air path described above is shown schematically on the Figure 3, by arrow 175.

Preferably, the passage of air from cooling 174 is centered on the axis of the screw clamping 134, and has a cylindrical shape of circular section. Furthermore, it is noted that for obtain the desired air flow, it is possible to directly calibrate passage 174, or place calibrated washers (or pads) at the interior of these passages 174. Naturally, the interest of this last solution lies in the fact that when you want to change the air flow of cooling passing through the passages 174 it it is only necessary to change the washers (not shown). On the other hand, this platelet solution also provides different air flows depending on the floors of the turbine, while using the same drilled screws dimensions.

With more specific reference to the Figure 2, the upper wall 158 participates in delimiting the interior chamber 120, inside which air can also be introduced cooling. So the cooling air penetrating inside the chamber 120 can also join the cooling cavity 162 in using through orifices (not shown) made in the upper wall 158, so as to allow ring sectors 108 to cool by direct impact on the cavity wall. In such case, it is to be understood that the cavity of cooling 162 is then supplied with air by two flows, taken for example respectively from the high pressure compressor and at compressor level low pressure of the turbomachine 100.

However, other solutions are also possible to cool the sectors ring 108 of the high pressure turbine.

By way of example and with reference to the Figure 5, the ring sector 108 has a wall upper 164 defining a cavity of main cooling 166 with a wall intermediate 168, also called “impact sheet”. In addition, sector 108 has a lower wall 170 defining a cooling cavity secondary 172 using the intermediate wall 168. Thus, the two cavities 166 and 172 are superimposed radially, the main cavity 166 being for example smaller than the secondary cavity 172.

In this way, the cooling air ejected from the internal radial end of passage 174 enters the main cavity 166 in a way identical to that shown above and then is likely to join the secondary cavity 172 in using through orifices (not shown) made in the intermediate wall 168. From this way, it is possible to achieve cooling ring sectors 108 by impact or convection.

Also, here again, the air of cooling located in the interior chamber 120 is able to penetrate inside the cavity 166 through through holes (not shown) made in the upper wall 164. As can be seen in this figure 5, the wall upper 164 has the threaded portion 141 necessary for fixing the ring sector 108 on the clamping screw 134, this threaded portion 141 opening into the main cavity 166.

So these are two air flows from passage 174 and room respectively interior 120 that are likely to enter the main cavity 166 and then to mix in this same main cavity before joining the secondary cavity 172 via the orifices aforementioned through holes in the wall intermediate 168.

Referring to Figure 6, it is partially shown a turbomachine, according to a second preferred embodiment of this invention.

In this figure 6, the elements bearing the same reference numbers as those attached the elements shown in FIGS. 1 to 5, correspond to identical or similar elements.

In this way, we can see that the turbomachine 200 according to the second embodiment preferred of the present invention is widely similar to the turbomachine 100 according to the first mode preferred embodiment.

The main difference is in the fixing means 232 of the cooled ring sectors 208 on the turbine casing 102. Indeed, if the spacer 136 is similar to that presented in the first preferred embodiment, it is not the same for the clamping screw 234. This screw tightening 234 actually includes a head 240 capable of be precisely stuck in a cavity 276 belonging to an upper sector ring 208, this borrows 276 defining a space 280 with an upper wall 258 of the ring sector 208, located radially inside with respect to borrows 276.

So the cooperation between the spacer 136 and a portion 238 of the screw 234 located opposite of this spacer, associated with the cooperation between the head 240 of the tightening screw 234 and the cavity 276 of the ring sector 208, allows axial positioning and precise tangential of the latter relative to the casing turbine 102.

In addition, the clamping screw 234 has a threaded portion 242 projecting from spacer 136 outward, and cooperating with a nut 278 positioned in abutment against the upper end 136b of the spacer 136, the nut 278 therefore being located radially outwardly relative to the casing 102. Therefore, tightening the nut 278 causes a outward radial movement of the ring sector 208, until it comes into contact with the housing turbine 102. As can be seen in FIG. 6, the contact takes place at the level of the upstream boss 148 and downstream boss 150 provided on the upper part of the ring sector 208. Furthermore, as indicated previously, the movement in the radial direction of the ring sector 208 could be stopped simultaneously by the latter coming into contact with the end lower 136a of the spacer 136.

On the other hand, here again, each sector ring 208 has the upper wall 258 and a lower wall 260 being radially superimposed, these walls 258 and 260 defining therebetween a main cooling cavity 262, and being indifferently carried out separately then assembled together, or made in one piece.

To supply air to cooling of the cavity 262, the tightening screw 234 is provided with one or more air through passages cooling 274, preferably only one, which is practiced so as to communicate with this same main cavity 262. Indeed, air from cooling can be taken for example at the level of a turbomachine compressor 200 and then be routed to an outer radial end (not referenced) from passage 274, this outer end being located radially outwardly relative to the turbine casing 102. In addition, insofar as the screw head 240 is placed inside the space 280, so it's clear that an internal radial end (not referenced) from passage 274 is in communication with this same space 280, which is itself in communication with the cavity 262 via one or more through holes 282 made in the upper wall 258. With such a configuration, the cooling air passage 274 is in communication with the main cavity 262, from so that air ejected from the inner radial end can then penetrate inside this cavity 262, and cool the ring sector 208. As illustrative, the cooling air path described above is shown schematically on the Figure 6, by arrow 275.

Preferably, the passage of air from cooling 274 is centered on the axis of the screw tightening 234, and also has a cylindrical shape of circular section. Here again, it is noted that for obtain the desired air flow, it is possible to directly calibrate passage 274, or place calibrated washers (or pads) at inside these passages 274.

Of course, the proposed alternatives for the turbomachine 100 according to the first mode of preferred embodiment of the present invention and shown in Figures 4 and 5, are also applicable to the turbomachine 200 according to this second mode preferred embodiment.

To mount the sectors ring 208, it is carried out as follows.

First, the clamping screws 234, the different sectors of 208 rings and tabs 156 are installed before assembly spacers 136 on the casing 102, so that that the ring sectors 208 each have a degree of tangential freedom for mounting tabs 156.

Then the spacers 136 are mounted on the turbine casing 102 so as to be crossed by the clamping screws 234. Thus, the ring sectors 208 having been set up so offset from their final position can then be rotated until the heads 240 enter the respective imprints 276.

To complete the assembly and have a fixed ring surrounding the blades 6 of the turbine rotor 4, it is then necessary to tighten all of the nuts 278 on the threaded portions 242 of the tightening 234.

Of course, various modifications can be made by those skilled in the art to turbomachines 100 and 200 which have just been described, only by way of nonlimiting examples.

Claims (12)

Turbomachine (100, 200) comprising a casing (102), a rotor (4) and a plurality of cooled ring sectors (108, 208) interposed between said casing (102) and said rotor (4), each sector ring (108, 208) comprising a main cooling cavity (162, 166, 262) and being mounted on the turbine housing (102) by means of fixing means (132, 232), characterized in that the fixing means (132, 232) comprise a clamping screw (134, 234) positioned substantially radially and ensuring the plating of the ring sector (108, 208) against said casing (102), and in that said screw clamping (134, 234) is traversed by a cooling air passage (174, 274) communicating with said main cooling cavity (162, 166, 262) of the ring sector (108, 208). Turbomachine (100, 200) according to claim 1, characterized in that for each ring sector (108, 208), said clamping screw (134, 234) is traversed longitudinally by a single passage of cooling air (174 , 274). Turbomachine (100, 200) according to claim 1 or claim 2, characterized in that for each ring sector (108, 208), the fixing means (132, 232) comprise a spacer (136) mounted on the casing (102) and traversed by the clamping screw (134, 234), said spacer (136) ensuring the axial and tangential positioning of the ring sector (108,208) relative to said casing (102). Turbomachine (100, 200) according to claim 3, characterized in that for each ring sector (108, 208), said spacer (136) has an internal diameter substantially equal to an external diameter of at least a portion (138, 238) of said clamping screw located opposite the spacer (136). Turbomachine (100, 200) according to claim 3 or claim 4, characterized in that for each ring sector (108, 208), said spacer (136) has a lower end (136a) inserted in a bore (144) provided on said ring sector (108, 208), this lower end (136a) having an outside diameter substantially equal to an inside diameter of said bore (144). Turbomachine (100, 200) according to any one of claims 3 to 5, characterized in that for each ring sector (108, 208), said spacer (136) constitutes a stop for said ring sector (108, 208), so as to ensure the radial positioning of the latter relative to said casing (102). Turbomachine (100) according to any one of claims 3 to 6, characterized in that each ring sector (108) comprises a threaded portion (141) cooperating with said clamping screw (134), the head (140) of this clamping screw (134) being in abutment against an upper end (136b) of the spacer (136). Turbomachine (200) according to any one of claims 3 to 6, characterized in that each ring sector (208) has an imprint (276) inside which is housed in abutment the head (240) of said clamping screw (234), the latter cooperating with a nut (278) abutting against an upper end (136b) of the spacer (136). Turbomachine (100, 200) according to any one of the preceding claims, characterized in that each ring sector (108, 208) has an upstream end as well as a downstream end, said upstream end being in contact with a circular flange upstream (152) belonging to the casing (102), and said downstream end being in contact with a downstream circular flange (154) belonging to this same casing (102). Turbomachine (100, 200) according to any one of the preceding claims, characterized in that each ring sector (108, 208) further comprises a secondary cooling cavity (172) separate from said main cooling cavity (166) by a wall (168), said main and secondary cavities (166, 172) being superposed radially. Turbomachine (100, 200) according to any one of the preceding claims, characterized in that the ring sectors (108, 208) are connected to each other by means of sealing tongues (156). Turbomachine (100, 200) according to any one of the preceding claims, characterized in that said casing (102) is a turbine casing, and in that said rotor (4) is a turbine rotor.

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