EP1456508B1 - Hot gas path subassembly of a gas turbine - Google Patents

Description

Technical application

The present invention relates to a hot gas path assembly for a turbomachine, in particular for a gas turbine, according to the preamble of claim 1.
It further relates to a turbomachine in which an assembly according to the invention is used.

State of the art

The efficiency of an axially flowed through Gas turbine is among other things by leakage currents of the compressed gas affects between rotating and non-rotating components of the Turbine occur. The one between the tips of the Blades and the blades surrounding the blades Housing wall occurring gap plays this one essential role. One is therefore anxious to have the column keep as small as possible. In case of deviations from Design point can be easily used for scratching the moved to come to the static components. Out For this reason are often grazing and / or abrasion-tolerant components, such as Honeycombs, "honeycombs", or even porous Ceramic or metal structures or felts used, as the mating surfaces of the sealing tips of Serving blades, and partially during one Break-in phase of these are cut. The Use of such touch-tolerant sealing elements diminished at minor grazing incidents serious machine accidents as the rubbing due to the soft structure of the mating surface without Damage to the blades is recorded.

Both the tips of the blades or vanes as well as the used honeycomb seals are in Hot gas operation of the gas turbine at very high temperatures exposed.

It is therefore known, for example, from US Pat. No. 3,365,172, to apply cooling air to the sealing tips of the rotor blades through honeycomb seals. For this purpose, the support for the honeycomb seals with small cooling air holes is penetrated, which are supplied via a rotating annular chamber with cooling air.
JP 61149506 shows a similar configuration in which the honeycomb seals are carried by a layer of porous metal adjacent to a supply chamber for cooling air. Also in this embodiment, the cooling air is brought through the honeycomb seals to the blade tips.

From US 6,171,052 is also the leadership of Cooling air through porous Dichtungslemente through known. This will be the porous sealing elements when flowing through with the cooling air transpirationsgekühlt. US 4,013,376 discloses a Configuration in which the mating surface of the Shovels both chilled and cooled Transpirationsgekühlt is executed. EP 1162346 discloses a configuration in which the Cooling side of a gas-impermeable element is cooled by impact. US 3,728,039 also discloses transpiration cooled porous rings as mating surfaces of blades. It is the Feed of the ring segmented with cooling air. Of the Ring itself is made in one piece.

A problem with a variety of configurations is that when it comes to one by rubbing Damage to the gas-permeable elements comes or even an area is completely torn out, the Coolant pressure collapses, and it becomes one Overheating and finally failure of the whole Seal arrangement comes. Likewise, if in one Range of porosity due to grazing deformation or is clogged by dirt, the coolant flows around this area of the sealing element. Whose Cooling is no longer guaranteed, and it comes to local overheating. Due to overheating, the burning out affected area. By the way resulting large hole now flows the cooling air out, and the previously unaffected areas become no longer cooled. As a result, the Bautiel fails as a whole, on the entire circumference.

Another question is one possible efficient use of the available Cooling air, as by a cooling air saving considerable Performance and efficiency potentials can be tapped are.

Presentation of the invention

The object of the present invention is now in it, a hot gas path assembly of the above specify the type mentioned, which the disadvantages of Prior art avoids. In particular, should a Hot gas path assembly be designed such that the Cooling air is used as efficiently as possible, and that in a damaged area of the Sealing element, the cooling of not immediately affected areas are essentially unimpaired remains. In other words, a potential possible damage to the location of the primary be limited to a damage-causing event.

The task is with the hot gas path assembly solved according to claim 1.

The core of the invention is therefore on the one hand, in a cooling air path to two cooling points in series too switch, such that the flowing cooling air successively to fulfill two cooling tasks is used. In one embodiment of the Invention is with the same cooling air flow of the stator a gas turbine once in the area Leitschaufelreihe, as well as in the area of a Cooled bucket row, and at the same time are the Bucket tips or the bucket cover with the same cooling air applied. This way will achieves the maximum permissible cooling air heating and the Cooling potential of the cooling air is maximally utilized. On the other hand, the partition wall is such stated that the cooling air flow paths of individual in the circumferential direction of the machine next to each other arranged segments downstream of a baffle cooling element hermetically separated. One Impact cooling element is comparatively with a variety provided small openings over which a Cooling air flow at high speed on the Cooling side of the component to be cooled is directed. Frequently, baffle plates are used. by virtue of this function cause the baffle elements a comparatively high pressure drop, and are the essential throttle in the respective Coolant path, which also essentially the Metering of the flowing coolant causes. at a corresponding distribution of pressure drops, wherein the pressure loss coefficient of the impingement cooling element greater is, preferably at least a factor of 2, than the Pressure loss coefficient arranged downstream thereof Flow cross sections, the total flow is in first approximation only by the impingement cooling element certainly. For the configuration according to the invention does that mean that when in a segment a Damage to the gas-permeable element, in particular a sealing element, enters, the Flow conditions of the coolant are not dramatic be changed, and not primarily by the Damage event affected segments still sufficient be supplied with cooling air.

In a preferred embodiment of the invention are in the circumferential direction several gas-permeable Elements arranged side by side. By the multi-piece, lateral, in particular in the circumferential direction, segmented design of the sealing ring will continue Ensures that a local damage event too mechanically on the directly affected segment remains limited. This is even more true when the individual sealing ring segments arranged and fixed are that as mutual as possible mechanical decoupling is achieved. Preferred is in each segment at least a single gas permeable Arranged element. As already stated, offers the assembly according to the invention is very special then on, when the gas-permeable element a Part of a non-contact seal of a Turbomachine, in particular between a vane and the rotor and especially between one Blade and the stator is.

In one embodiment of the invention that is gas impermeable element in the direction of Hot gas flow upstream of the gas permeable Element arranged. It is advantageous if the gas impermeable element has another, redundant, Has coolant opening on the hot gas side the module opens. Preferably, the flows Coolant opening upstream of the gas permeable Elementes, as close to the gas-permeable Element. The coolant opening is as possible executed that there emerging coolant as possible parallel to the hot gas side surface of the gas-permeable element flows, such that there a cooling film is created. This has the following big Advantages: When the flow cross sections of the gas-permeable element of the respective segment due to contamination or deformation unrestricted flow will continue to allow more on the one hand, a coolant flow through the Impact cooling holes or impingement cooling nozzles of Ensures impingement cooling element, and the cooling of the gas impermeable element is ensured. At the same time, it settles out of the coolant opening outgoing air as a cooling film on the gas permeable Element, thus ensuring a minimum cooling of this element, though due to the diminished Flow through the transpiration cooling effect of the Element passing air reduced or completely has failed. It is advantageous if the Flow cross-sections of the gas-permeable element and the coolant openings in design terms so are measured that the pressure loss of the Coolant opening is greater than that of the gas-permeable element, such that preferably less than 50%, and in particular less than 30% of the total coolant through the coolant hole, and the rest as Transpiration coolant through the gas permeable Element is passed. If its pressure loss due to the effects described above, the coolant moves into the coolant opening, and the proportion of film cooling increases. As above set out, while the entire remains Coolant mass flow to a first approximation constant, if the pressure loss over the impingement cooling bores predominates.

The inventive assembly is suitable as already indicated, very special for use in Turbomachinery, the gas-permeable elements a circumferential ring for non-contact sealing form with an opposite blade ring. preferably also form the gas-impermeable elements a circumferential ring; This ring is preferred in Direction of Heisssgasdurchströmung the Turbomachine upstream of the ring of arranged gas permeable elements. In a preferred embodiment are the gas impermeable Elements of impact-cooled heat discharge segments. in a Another preferred embodiment of the wear impact-cooled gas-impermeable elements Turbine blades, in particular vanes. In particular, then the assembly according to the invention arranged in the stator of the turbomachine.

It is, especially if the assembly is part a turbomachine is a preferred Embodiment that the dividers or Partition walls for subdividing the segments parallel to the chords of in the flow channel, and in particular on the gas impermeable elements, arranged blades run.

The assembly consists in one embodiment a number of lateral, in particular in the circumferential direction, juxtaposed subassemblies, which so are constructed that each subassembly one gas impermeable element and a gas permeable Element comprises. In essence, then on the Cooling side of the subassembly opposite the gas impermeable element an impingement cooling element spaced apart, and opposite of the gas permeable element a cover element. Between the cover element and the impingement cooling element on the one hand and the gas-permeable and gas-impermeable element on the other hand, a ring segment-shaped space or a essentially annular segment-shaped gap for the Coolant formed. According to the invention comprises a Such subassembly at least one Subdivision wall for fluid-separating subdivision and / or delineation of the annular gap in lateral direction, in particular in the circumferential direction. in an embodiment carries the subassembly at least one turbine blade; the subdivision wall then runs preferably parallel to the chord this Shovel.

Preferably, an annular assembly in Circumferential direction in at least four from each other Independently with cooling medium acted upon segments be divided. By training a larger number of segments, the reliability of cooling is added Damage to individual sections of the increased gas permeable elements.

As gas-permeable and in particular touch-tolerant elements come alongside Honeycomb structures, "honeycombs", including porous, for example, produced by foaming Structures of metal or ceramic materials in Question, or felts or fabrics of metallic or ceramic fibers, in question.

In an advantageous embodiment of the present device are further means for independent of each other at least some of the segments provided with coolant. This can be realized by a device that the Supply of cooling medium to the individual segments via the respective supply channels independently controls. In this way, an inhomogeneous Temperature distribution during operation of the Turbomachine over the circumference of the flow channel be compensated by individual segments. With supplied accordingly adjusted amounts of cooling medium become. This is still suitable for the realization a gap width control.

Even if in the following Embodiments of an annular or Ring segment-shaped design of the assembly, especially in a turbomachine, and quite especially in a gas turbine, is assumed, so the skilled artisan readily recognizes that the invention for example, is applicable to planar geometries, the segments then not in the circumferential direction but are arranged laterally side by side.

Brief description of the drawings

Figur 1 ein Beispiel für die Realisierung der Erfindung in einer Gasturbine;

Figur 2 ein Beispiel für die Realisierung der Erfindung mit einem prallgekühlten Leitschaufelfuss;

Figur 3 einen vereinfachten teilweisen Querschnitt einer erfindungsgemässen Baugruppe;

Figur 4 eine Unterbaugruppe zum Aufbau einer erfindungsgemässen Baugruppe in einer Strömungsmaschine, insbesondere einer Gasturbogruppe; und

Figur 5 eine vereinfachte Draufsicht auf die Unterbaugruppe.

The present cooling and sealing arrangement will be explained below with reference to embodiments in conjunction with the figures. In detail show:

Figure 1 shows an example of the realization of the invention in a gas turbine;

Figure 2 shows an example of the realization of the invention with a fully cooled vane foot;

FIG. 3 shows a simplified partial cross section of an assembly according to the invention;

FIG. 4 shows a subassembly for constructing an assembly according to the invention in a turbomachine, in particular a gas turbine group; and

Figure 5 is a simplified plan view of the subassembly.

Not necessary for the understanding of the invention Elements have been omitted. The Embodiments are instructive to understand, and should better understand, but not the Restriction of the marked in the claims Serve invention.

Ways to carry out the invention

Figure 1 shows a section of a Flow channel of a turbomachine, for example a turbine of a gas turbine group. The flow channel is from right to left of a hot gas flow 12 flows through. In the stator 13 is not shown and not relevant to the invention, but to the person skilled in the art Common way a vane foot 16 with one Guide vane 10 is arranged. Downstream of the vane 10 is a blade 11 with a shroud 7 and Shroud tips 7a arranged. The shroud tips minimize in conjunction with opposite arranged suitable stator 2, the leakage gap and thus the hot gas leakage flow 12a. Around the leakage gap being able to keep small under nominal conditions is the opposite element 2 in the normal case comparatively soft touch-tolerant element. This is present as transpiration cooled gas-permeable honeycomb element executed. The Outflow of a flowing coolant in the Leakage gap is in crossflow to the leakage current quite suitable, the leakage flow continues to Reduce. The element 2 is in a carrier 1 held. The inventive, fixed in the stator, Assembly further includes an upstream of the gas permeable element 2 arranged gas-impermeable, impact-cooled element 8, here a Heat shield. Coolant, in particular cooling air or steam, via a feed 14 in the housing 13th introduced. The coolant 4 is initially high Speed through openings or nozzles of a Impact cooling element 17 out, and hits with high Impulse on the cooling side of the element 8, this being is cooled by impingement cooling. The coolant 4 continues to flow through after completion of the impingement cooling gas-permeable element 2 as transpiration coolant in the hot gas flow, wherein in the present Configuration continues the bucket cover 7 and the Seal tip 7a to be cooled. From this Coolant guide results in the best possible Utilization of the coolant 4. As can be seen, is between the gas-permeable element 2, the gas impermeable element 8, an upstream Wall 22, a downstream wall 23, the Impact cooling element 17, and a cover element 21 a in principle annular or ring segment-shaped space or gap 5, 9 is formed. According to the invention this in the circumferential direction of the turbomachine divided as below in particular in connection with Figure 3 is explained in more detail.

Another embodiment of the invention is in Figure 2 shown. Essential elements are explained In the light of the explanation of Figure 1 by itself. In This embodiment serves the gas-impermeable Crash-cooled element 8 at the same time as a blade root 16 of the vane 10. Analogous to Figure 1 is between the gas-permeable element 2, the gas-impermeable Element 8, the impingement cooling element 17, a cover element 21, and an upstream wall 22 and a downstream wall 23, a space 9 is formed, which in the circumferential direction not recognizable here is divided. Coolant passes through the Impact cooling element 17 in the space 9 a. Under undisturbed nominal conditions, the coolant 4 flows at least predominantly by the gas permeable Element 2 off. Furthermore, the gas impermeable Element 8 another, redundant coolant port 18th on, via the coolant 4 flow out of the room 9 can. This coolant opening opens on the Heisgasseite the assembly that exiting there Coolant as a cooling film on the hot gas side of the gas-permeable element flows. In particular, flows the redundant coolant port 18 substantially tangential to the hot gas side surface of the gas-permeable element 2. The redundant Coolant opening is preferably dimensioned such that under undisturbed nominal conditions less than that Half, in particular less than 30%, of the Coolant mass flow 4 through the redundant Coolant openings 18 flow. If it does, though for example due to pollution or a Grazing event to a significant increase in the Flow resistance of the gas-permeable element. 2 comes, shifts the flow of coolant in the redundant coolant openings 18. This is on the one hand, the flow for cooling the gas-impermeable element 8 maintained, and On the other hand, due to decreasing Flow through insufficient transpiration cooling successively by film cooling through the openings 18th replaced.

FIG. 3 shows a schematic view of a inventive assembly in one Cross-sectional view. Essentially radial and axially extending webs or partition walls 24 divide the space 9 in the circumferential direction into segments 26. Each segment 26 is also its own redundant Coolant opening 18 is arranged; at least theirs Mouth is slot-shaped, in case of need a the largest possible distribution of film coolant to achieve. This is the entire coolant path at least downstream of the impingement cooling elements 17 through the Partition walls 24 in completely from each other divided into independent segments. Still is ever Segment 26 a single gas-permeable element. 2 arranged. Is it now a strong Scratching a not shown here Blade tip 7a, see FIG. 1 or 2 in this regard, in a segment, only that becomes immediate affected gas-permeable element from the assembly torn out. Due to the mechanical decoupling the gas-permeable elements 2 of the different Segments 26, the mechanical damage event remains on the immediately affected segments are limited. Of course breaks in the room 9 of the affected Segmentes the refrigerant pressure together. But since the Segments are separated from each other, and the significant pressure loss in the impingement cooling elements 17 occurs, the coolant pressure remains in the other Segments are constant, at least to a good approximation, and the damage event is completely local to the or the affected segments are limited. Also the Impact cooling of the gas impermeable element in affected segment essentially remains fully functional.

In a real running turbomachine is the inventive assembly advantageously from a Plural arranged side by side in the circumferential direction Subassemblies built, which is the handling of Invention significantly simplified. Such Subassembly is exemplified in Figure 4 in a shown in perspective view. It is about to a subassembly of the assembly of Figure 2, and comprises a circumferential segment with a vane 10, together with their impact-cooled blade foot 16. Die Subassembly also includes a gas permeable Element 2, an impingement cooling element 17, a cover element 21, and an upstream wall 22 and a downstream wall 23. Through the illustrated Arrangement is a ring segment-shaped gap. 9 formed, which in the radial and axial directions closed and on the peripheral sides of the subassembly in itself open. According to the invention, the Subassembly a partition wall 24, which en a peripheral side of the subassembly or on a other circumferential position can be arranged. The Subdivision wall is designed so that they, as in In connection with FIG. 3, a fluid separation is explained between the two peripheral sides manufactures.

Finally, FIG. 5 shows a schematic Top view of the subassembly from the radial outside, with "split" walls 22, 23, 24. It can be seen that in this preferred embodiment the in the Figure 5 is not explicitly marked, but for the One skilled in the light of the foregoing recognizable, space 9 in the circumferential direction of one Dividing wall 14 divided in the circumferential direction that is parallel to the dot-dash line drawn chord of the blade 10 extends. The partition wall 24 is directly at one Peripheral side of the subassembly arranged; she could but without further ado another Be arranged circumferential position.

The designs made here for annular or ring segment-shaped geometries can interested expert without further ado on level Transfer geometries, taking place then Circumferential segments lateral segments next to each other are arranged.

LIST OF REFERENCE NUMBERS

1

support element

2

gas-permeable element

4

coolant

5

Space, gap

7

Blade shroud

7a

sealing tip

8th

gas impermeable element

9

Coolant channel, gap

10

vane

11

blade

12

Hot gas flow

12a

leakage flow

13

Housing wall, stator

14

Feeder for coolant

16

blade root

17

Impact cooling element, impingement cooling plate, impact cooling insert

18

redundant coolant opening

21

cover element

22

upstream boundary, wall

23

downstream boundary, wall

24

Subdivision wall, circumferential or lateral Partition wall

26

segment

Claims (14)

1. Hot gas path subassembly for a turbomachine, in particular a gas turbine, which hot gas path subassembly has substantially an annular cross section or the cross section from a ring segment with a circumferential direction and which subassembly has a cooling side and a hot gas side over which hot gas (12) flows during operation, which hot gas path subassembly furthermore comprises at least one gas-permeable element (2) designed for transpiration cooling and at least one gas-impermeable element (8), the gas-permeable element and the gas-impermeable element being arranged in different positions in the hot gas flow direction, and the gas-impermeable element being designed to be impact-cooled, with an impact-cooling element (17) arranged, spaced apart from the gas-impermeable element on the cooling side, and, on the cooling side of the subassembly, a coolant path (9, 5) being formed, which leads from the impact-cooling insert (17) to the cooling side of the gas-permeable element (2), characterized in that the subassembly has at least one subdividing wall (24) which subdivides the coolant path in the circumferential direction into fluidically separated segments (26).
2. Subassembly according to Claim 1, characterized in that a plurality of individual gas-permeable elements are arranged next to one another, in particular in the circumferential direction.
3. Subassembly according to Claim 2, characterized in that at least one individual gas-permeable element is arranged in each segment (26).
4. Subassembly according to one of the preceding claims, characterized in that the gas-permeable element is a sealing element of an arrangement for contactless sealing.
5. Subassembly according to one of the preceding claims, characterized in that a vane blade (10) is arranged on the gas-impermeable element (8).
6. Subassembly according to one of the preceding claims, characterized in that the gas-impermeable element (8) is arranged upstream of the gas-permeable element (2) in the hot gas flow direction (12).
7. Subassembly according to Claim 5, characterized in that the subdividing walls (24) run essentially parallel to the profile chords of the vane blades (10) arranged on the subassembly.
8. Subassembly according to one of the preceding claims, characterized in that a coolant orifice is arranged in the gas-impermeable element and issues on the hot gas side upstream of the gas-permeable element.
9. Subassembly according to one of the preceding claims, characterized in that the subassembly consists of a number of subordinate subassemblies arranged next to one another in the circumferential direction.
10. Turbomachine, in particular gas turbine, comprising at least one subassembly according to one of the preceding claims, characterized in that the gas-permeable elements (2) form a peripheral ring for contactless sealing relative to a blade ring (11, 7, 7a) arranged opposite.
11. Turbomachine according to Claim 10, characterized in that the gas-impermeable elements (8) form a peripheral ring which is arranged upstream of the gas-permeable elements (2) in the flow direction of a hot gas flow (12).
12. Turbomachine according to either one of Claims 10 and 11, characterized in that the gas-impermeable elements (8) are impact-cooled heat accumulation segments.
13. Turbomachine according to one of Claims 10 to 12, characterized in that the gas-impermeable elements (8) carry vane blades (10).
14. Turbomachine according to one of Claims 10 to 13, characterized in that the subassembly is arranged in the stator (13) of the turbomachine.

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