EP1134360B1 - Device for adjusting the diameter of the stator of a gas turbine engine - Google Patents

Description

The field of this invention is a diameter adjustment arrangement of a stator of gas turbine.

Some gas turbines include our days of adjustment devices of the internal diameter of the stator in order to bring back the existing clearance between the stator and rotor blade tips at a value as weak as possible; a current layout to ensure this diameter adjustment is to sample a portion of the cooler gases originating from compressors and route it through the stator for that it is blown on pilot's rings from stator which extend in front of the rotor blades. We realizes what is called a stator ventilation, whose diameter is changed according to the temperature and flow rate of ventilation gases. Generally, the gas sampling is double: so-called hot source with fixed flow allows the expansion of the crank when necessary, another cold source variable and controlled flow makes it possible to contract casing.

The path of the ventilation gases of the hot source borrows a volume internal to the stator, between the rings to ventilate and a casing that surrounded. Spacers joining the rings to the housing include in particular transverse bulkheads that separate the volume of the journey into rooms and to through which it is necessary to communications to allow the flow of gases from ventilation. This is illustrated in particular by the US 4,573,866 where the passage of gases through the spacers are made by drilling holes partitions of these. Many other examples of these communications have been proposed in the prior art, but it is observed that a good ventilation is not easy to ensure because it must be well distributed not only between the rings successive, but on the surface of each of the rings, otherwise we see ripples of the rings produced by differences in intensity of ventilation and thermal expansion around their circumferences, and therefore areas where leaks gas at the end of the rotor blades will remain. Moreover, the openings made through the spacers have to weaken them, with consequences dangerous parts of the machine subjected to strong mechanical stresses, since stress concentrations usually appear around these openings.

The object of the invention is therefore to propose a gas turbine stator arrangement, of which the interior is compartmentalized but provided with openings allowing ventilation gas to be blown on stator rings subject to adjustment, where the openings are designed to produce great regularity of ventilation around the rings without unduly weaken the structural elements to through which they are pierced.

The invention thus relates, in its form the most general, a diameter adjustment arrangement of a gas turbine stator, the stator comprising a carter, rings bordering a flow vein gas and located in front of respective stages of blades movable rotor, the rings being surrounded by the housing and hung on the housing by spacers circular, each comprising a partition cross section extending from the housing to one of the rings and separating two chambers, the partition comprising an edge outside curved hook spacer and engaged between a main portion of the housing and an appendix respective crooked hook crank associated audit spacer hook, passing communications a pressure gas flow existing between rooms, characterized in that at least one of the communications is achieved by means of recesses operated through a junction of hooks consisting of a spacer hook and crankcase hook which is associated.

Like the spacer hooks and crankcase are appendages or ends of these structures, they are subject to moderate constraints, so opening creation through them does not produces only acceptable levels of stress. Of preferably, the communication between rooms proposes here includes longitudinal notches dug through each of the spacer hooks, a Circular gap located under the crankcase hook respective and outside the spacer hook, and radial notches operated on the hook of spacer between the longitudinal notches and opening on one of said chambers.

We can propose two designs main features of this embodiment: either the radial notches extend to a depth sufficient to protrude from the crankcase hook, they include collecting portions followed by holes; this last arrangement lends itself willingly to a calibration of the ventilation rate (from the inlet section of the radial notches or piercing) and to a tranquilization of the gas in the downstream chamber of the flow (after passing through the constricted part of the holes).

• la figure 1 illustre une entretoise équipée de l'invention et ses parages ;
• la figure 2 illustre la présence d'un second circuit de ventilation, facultatif, avec la même réalisation d'entretoise de ventilation ;
• la figure 3 illustre les crochets d'entretoise ;
• et les figures 4, 5, 6, 7, 8 et 9 représentent certaines possibilités pour créer des perçages complétant ou facilitant la ventilation.

Other characters of the invention will be described with reference to the appended figures, which illustrate certain concrete embodiments of the invention:

• Figure 1 illustrates a spacer equipped with the invention and its surroundings;
• FIG. 2 illustrates the presence of a second optional ventilation circuit, with the same embodiment of a ventilation spacer;
• Figure 3 illustrates the spacer hooks;
• and Figures 4, 5, 6, 7, 8 and 9 show some possibilities for creating holes to complete or facilitate ventilation.

Figure 1 illustrates a fragment of a gas turbine stator 1 which is found with surrounding elements in Figure 2. The stator 1 includes a casing 2 on the outside, and which surrounds rings 3 coming in front of stages of moving blades 5 of a rotor 6 within a vein 7 of flow of gas, and rings 3 alternate with other rings 8 vanes 9 along the vein 7. Gas turbines include several rings 3 and 8 successive, but only one of each species is shown on the fragment of FIGS. 1 and 2, the invention being here applied only to a ring 3.

Spacers 10 join the rings 3 1. Junctions composed generally of the assembly of a pair of hooks and which will be described in detail unite the spacer 10 to the stator 1 to the front and back, and the spacer 10 to the ring 3 front and back; they carry respectively references 11, 12, 13 and 14. We seek to reduce the clearance between the ring 3 and the blades 5 during the operation of the gas turbine. More gases charges originating from a compressor upstream of the gas turbine are racked out to be blown to the outside of the ring 3, on the opposite side to 5 As the spacer 10 comprises a transverse partition at the front 15, between the junctions 11 and 13, a transverse partition at the rear 16, between junctions 12 and 14, and a partition intermediate transverse 17 connecting the two preceding and arranged obliquely and substantially between the junctions 13 and 12, the ventilation gases passing through the case 2 but around the rings 3 and 8 first pass through a first chamber 18 to the front of the partition before 15, then by a room intermediate 19 between the bulkhead before 15 and the intermediate partition 17, and finally by a downstream chamber 20 between the intermediate partition 17 and the ring 3. This downstream chamber 20 is still delimited by the rear partition 16, and it is divided by a lid with holes, or more generally a box 21 composed of several of these lids, already proposed in the art to help equalize the ventilation (for example in the US patent 5,273,396). The rear partition 16 is a partition external ventilation chambers 18, 19 and 20, since the ventilation flow stops there and that another atmosphere extends beyond.

Communications to make pass the compressor gases through chambers 18, 19 then comprise, in accordance with the invention, openings arranged mainly through the junctions 11 and 12 to the casing 2. The part of description that will benefit from being read in also referring to Figure 3.

Junction 11 is composed of an edge of the front wall 15, curved downstream (or back) to form a spacer hook 26, and a associated appendix of the casing 2, the end curved upstream (or forward) to give a crank hook 27. Similarly, the partitions back and intermediate 16 and 17 end up on one edge common directed backwards, forming another hook spacer 28, whereas an associated appendix of the casing 2 is also bent forward for give another crank hook 29. Hooks 26 and 28 are inserted between the casing 2 to the outside and, respectively, the crankcase hooks 27 and 29 inside.

The spacer hook 26 located at the front is not a continuous or intact structure, but it is dug longitudinal notches 30 regularly distributed on its circumference and parallel between they, who cut him from side to side on his face outside and therefore extend from the upstream chamber 18 to the annular gap 31 between the end of the spacer hook 26 and the bottom of the crankcase hook 27; the spacer hook 26 is also notched radial notches 32, also parallel between they are regularly distributed around the circumference spacer hook 26, halfway between the cuts 30, and these radial notches 32 have a sufficient depth to go beyond the end of the hook 27: the intervals 31 and 34 formed between the ends of the spacer hooks 26 and 28 and the bottom of crankcase hooks 27 and 29 gain to see their meridian sections augmented by practicing rabbets 50 (shown in Figure 3) on the faces external spacing hooks 26 and 28, on the crankcase hooks 27 and 29 and extending the longitudinal notches 30 and 33. The advantages of 50 rebates are multiple: reduction of the surface contact spacer-carter and therefore the warm-up casing by conduction; better control of the circulating air passage section circumferential because the manufacturing dispersions are smaller for the rabbets 50 than for the throat bottoms of crankcase hooks; and so better control of circumferential speed of air flow and exchange coefficients convective; larger convective exchange surface on the casing 1 and therefore better control of the flow of heat and its homogeneity.

Heat exchanges are produced in intervals 31 and 34. They are regulated by: the surface wetted by the gas of the casing 1; speed air flow in the circumferential direction; the number of longitudinal cuts 30 and 33, and therefore the length of the circumferential paths.

Communication between rooms 18 and 19 is so established, the vent gases passing by the longitudinal notches 30, then by the interval 31 where they disperse and finally by the radial notches 32.

The notches 30 and 32, generators of concentrations of stress and weakening the structure, are only established on the brackets of the junction 11, that is to say portions of edge, little likely to give high concentrations of constraints. The dispersion movement of the flow through the interval 31 helps to standardize the flow of gas on the circumference of the machine, and therefore the effect ventilation; changes of direction to which the flow is subjected produce losses welcome to the efficiency of the ventilation ; finally, the gases exit in the direction centripetal, towards the ring 3.

It will have been noticed that the notches are not dug only through the spacer hook 26 but suitable results would be very likely obtained if the radial notches had been operated in the crankcase hook 27.

A similar provision allows for communicate rooms 19 and 20. The hook spacer 28 located at the back is first dug longitudinal slots 33, similar to those 30 of the hook 26, and an interval 34 analogous to the interval 31 exists between the end of spacer hook 28 and the bottom of the hook of the housing 29; the gases of ventilation are dispersed in this interval 34 to radial notches 35 operated between the notches 33. However, they do not communicate directly to the downstream chamber 20 but in bores 36, in variable number per radial notch. holes 36 extend to the chamber 20 in traversing the material of the spacer 10 at the junction partitions 16 and 17. This arrangement offers the same features and benefits that that of assembly previous 11, and the holes 36 are directed obliquely with a strong centripetal component that directs the ventilation gas to the ring 3. the notches 33 can still open on rabbets 50 which extend them to the interval 34. The gases ventilate ring 3 with even greater regularity by the box 21 before dispersing around him by leakage of the structure and through the emission channels 51 formed in the skin of ring 3 and giving in vein 7. The existence of intervals 31 and 34 is guaranteed by the stop established by the end of the hook of housing 29 located back against the rear wall 16, and ring 8 located immediately upstream maintain this support by weighing on the bulkhead before 15 to the place of the junction 13 outside front. The sealing downstream of the junction 12 is guaranteed by a seal 37 housed in a groove of the hook 29 and compressed between him and the rear partition 16; it's about a joint whose section is composed of three lobes in extension and so called omega joint.

The seal of this seal 37 adjacent to the hook 29 is doubled by the plane support 52 of the hook of the casing on the rear wall 16, which forms a uninterrupted sealing line. The radial notches 35, the holes 36, 42 and 43 are designed in such a way that not break that sealing line by doing communicate the interval 34 to the chamber of the joint 37. The arrangements of FIGS. 8 and 9 are thus possible to achieve the same result: in Figure 8, the radial notches 53 (instead of 35) extend in countersink on a portion 54 of the rear wall 16 for clear access to holes 36 while reducing the width of the support plane 52, but without interrupting it; at 9, the notches 55 (instead of 35 or 53) do not extend only in the inner face of the hook spacer 28, in front of the crankcase hook 29, thus lengthening the path of the gases in the cavities 34. Other arrangements are also possible. The part 54 recess of the rear partition 16 facilitates the entry of the air in the holes.

The box 21 can be a simple sheet impact and multiperforated. It can be fixed either on the ring, either on the spacer. The box 21 is attached to edges 38 and 39 of ring 3, usual manner in the art, in Figure 1; The direction favorable ventilation gases would allow for bring the box 21 closer to the gas inlet in the room 20, having it supported by ledges 40 and 41 of the spacer 10 that would be located on the partitions 15 and 16, as shown in FIG.

The holes 36 represented were constant section. They could be replaced by divergent holes whose section would increase to the downstream chamber 20, such as the stepped bore 42, or with a sudden variation in diameter, of the piercing 43, or progressive variation of diameter, of Figure 6; these holes 42 and 43 would be located like piercing 36 but the the proportions that could be given to Inlet and outflow diameters would help to faith about the calibration of the gas flow of allowed ventilation (thanks to the smaller diameter at entry) and the tranquilization effect obtained at the entrance to room 20 (thanks to the largest diameter at the exit), which is accompanied by a better supply of the box 21.

The invention can also be combined with more classic communications between rooms, such as holes 44 in FIG. room 18 to room 20 through the material of the spacer 10 arranged at the junction of the partitions transverse 15 and 17; the invention would then have for consequence of attenuating the weakening effect mechanical produced by the holes 44, reducing their required number.

Finishing in Figure 2, we see that the stator may be provided with external ribs 45 in front of or between which are arranged the chambers of distribution 46 of another ventilation gas network forming a cold source, these distribution chambers 46 being connected to supply pipes 47 used for the circulation of gases. The rooms of distribution 46 are pierced with blow holes in front of the ribs 45 for the gas to reach them. Often in practice, the second gas flow of ventilation will be withdrawn from a portion of the compressor located further upstream than the withdrawal portion of the first flow, so that the gas from this second flow will be cooler. Setting the diameter of the ring 3 will then consist of a combined adjustment of the two flows of ventilation, which will give a precision excellent.

Claims (12)

1. Gas turbine stator (1) comprising a casing (2), rings (3), circular groups of spacers (10), a diameter adjustment arrangement, the rings (3) being surrounded by the casing (2) and attached to the casing by the circular groups of spacers (10), each one comprising at least one partition (15, 17) extending from the casing to one of the rings and separating two chambers (18, 19: 19, 20), the partition comprising an outer edge curved as a spacer hook (26, 28) and engaged between a main portion of casing (2) and a respective appendage of the casing curved as a hook (27, 29) coupled with the said spacer hook, the diameter adjustment arrangement comprising connections for the passage of a flow of pressurized gas formed between the chambers, characterized in that at least one of the connections comprises longitudinal notches (30) formed through one of the spacer hooks, a circular gap (31) situated under the respective casing hook and in front of the spacer hook, and radial notches (32) formed on the spacer hook or on the casing hook between the longitudinal notches (30) and opening into one of the said chambers.
2. Gas turbine stator according to Claim 1, characterized in that the radial notches (32) are formed on the spacer hook and extend to a depth sufficient to extend beyond the casing hook.
3. Gas turbine stator according to Claim 1, characterized in that the radial notches are formed on the spacer hook and comprise collector portions (35) followed by passages (36, 42, 43).
4. Gas turbine stator according to Claim 3, characterized in that a plurality of the passages (36, 42, 43) open into each one of the collector portions.
5. Gas turbine stator according to either one of Claims 3 and 4, characterized in that the passages (42, 43) have a divergent cross-section starting from the collector portions.
6. Gas turbine stator according to any one of Claims 1 to 5, characterized in that covers (21) covering the stator rings, situated in the chambers and pierced in order to distribute the flow of pressurized gas more evenly, are fixed to the spacers.
7. Gas turbine stator according to any one of Claims 1 to 6, characterized in that it also comprises a device (46, 47, 48) for blowing a second gas flow over an external rib (45) of the casing, the gas flows being at different temperatures.
8. Gas turbine stator according to any one of Claims 1 to 6, characterized in that it also comprises a direct feed of one of the chambers (20), situated downstream, through passages (44) traversing one of the partitions (15) whilst avoiding the notches formed through the hooks.
9. Gas turbine stator according to Claim 1, characterized in that grooves (50) are formed through one of the spacer hooks and extending the longitudinal notches (30).
10. Gas turbine stator according to any one of Claims 1 to 9, characterized in that one of the hooks of the casing (29) is adjacent to a fluid-tightness seal (37) of the chambers and forms a continuous line of fluid-tightness (52) with one of the partitions (16) of the spacers, the said partition (16) being an external partition of the chambers.
11. Gas turbine stator according to either one of Claims 1 or 3, characterized in that the radial notches (53, 55) are formed on the spacer hook and extend over a portion (54) of one of the partitions (16).
12. Gas turbine provided with a stator comprising a diameter adjustment arrangement according to any one of the preceding claims.

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