DE19944923A1 - Turbine blade for rotor of gas turbine; has blade crown with cap having bars and hollow spaces inside bars connected to cooling channels to supply cooling air to inside of bars - Google Patents

Abstract

The turbine blade has a blade crown (8) at its free end with a cap (5). The cap has bars (6,7) projecting radially outwards. The inside of the bars has hollow spaces (9) through which cooling air flows to cool the blade crown. At least one cooling channel for cooling air is provided under the cap and is connected to the hollow spaces to supply cooling air by a number of cooling air bores (10).

Description

TECHNICAL AREA

The present invention relates to the field of gas turbines. It affects a turbine blade for the rotor of a gas turbine according to the preamble of claim 1.

Such a turbine blade is e.g. B. from the document EP-A1-0 684 364 be knows.

STATE OF THE ART

In the turbine blades for the rotor of a gas turbine, i. that is, in the run blades of a gas turbine, blades can be placed with and without a shroud divorce. In the case of moving blades without a shroud, to which the present inventor relates  the blade tip area or the blade crown is due to the exposed position at the gap between the shovel and the opposite tub formation (heat accumulation segment) of a high temperature load from the hot gas exposed. As a result, oxidation and LCF problems (LCF = low cycle fatigue = low-cycle fatigue). Due to the oxidative attacks Gap enlarged to the heat accumulation segment, which worsens efficiency tion of the turbine. Cracks caused by LCF can also and very strong oxidation the cooling channel arranged inside the blade expose so that the cooling of the entire blade breaks down, which ei result in total loss of the bucket.

Furthermore, it is difficult or not at all at high blade crown temperatures possible a so-called "rubbing" system consisting of an abrasive ("Abra sive ") on the crown and an abradable material on the heat to realize the exhibition segment. The reason for this is that if the crowns are too high temperatures the matrix material on the crown into which the abrasives are incorporated beds, react with the abrasives. This leads to deterioration of the matrix-abrasive compound, which in turn causes the abrasive to fall out medium when brushing.

One reason for the high metal temperatures It is very easy to declare reference to FIG. 1. The blade crown shown in Fig. 1 in longitudinal section 8 of a turbine blade 1, which has with respect to the hot-gas flow side a suction side 2 and a pressure 3, the top by a Cap 5 is closed, which is surrounded on the edge by radially outwardly projecting rails 6 and 7 (see also FIG. 7). The turbine blade 1 is cooled from the inside by means of a cooling duct 4 through which cooling air flows. The hot gas put out (outer) crown surface (dashed line in Fig. 1) is now compared to the wetted with cooling air (inner) crown surface (dash-dotted line in Fig. 1) he recognizable much smaller, so that the blade crown 8 for this reason alone cannot be cooled sufficiently. Another (possible) reason is too large a gap for the hot gas.

In order to lower the metal temperatures, pressure is usually applied side of the rotor blade blown out cooling air. Another variant is in EP-A1-0 684 364. Here is also in the crown area nearby the rail on the suction side and blown out at the rear edge. In all cases the cooling air mixes with the hot gas and lowers the hot gas temperature. There the lowering of the temperature by mixing in cold air is not very effective a lot of cooling air must be added. The resulting mixing losses and the increased cooling air consumption adversely affect the effectiveness degree of the turbine.

PRESENTATION OF THE INVENTION

It is therefore an object of the invention to provide a cooled turbine blade which avoids the disadvantages of previously known solutions, and in particular due to an effective cooling of the blade crown at the same time as low Characterized cooling air consumption.

The object is achieved by the entirety of the features of claim 1. Around to lower the crown temperature, according to the invention in the order running rails of the crown additional cavities through which cooling air flows brought in. This improves the ratio of wetted with cooling air Crown area to the hot gas exposed crown area essential. Through the the additional surface that is exposed to cooling air can do the heat better are dissipated and the material temperature of the crown is significantly reduced be decorated. The hollow, which is preferably designed as a circumferential cooling slot rooms can pass through one or more cooling air holes from the cooling channels of the Shovel can be fed with cooling air. The cooling air flows through the rotating Cooling slots and is preferably made in the area of the rear edge of the blade blown.  

A first preferred embodiment of the turbine blade according to the invention is characterized in that inside the turbine blade below the Cap at least one cooling channel acted upon with cooling air is provided that the cavities in the rails for supplying cooling air with the least a cooling channel are connected to connect the cavities with a plurality distributed over the at least one cooling channel over the blade crown of cooling holes are provided. This allows the Ver care of the cavities can be ensured. They are particularly easy Realize cooling air holes if according to a preferred training this embodiment, the cooling holes as of the at least one cooling channel through the cavities to the outside through holes are formed, which ver outwards by a closure are closed. Instead of the cooling air holes, it is also conceivable that for Connection of the cavities to the at least one cooling channel, the cavities pass directly into the at least one cooling channel at predetermined points.

A second preferred embodiment of the turbines according to the invention The blade is characterized by the fact that the cooling air is removed from the hollow clear the cavities from the cavities at predetermined points in the blade crown Blow-out openings leading outside are provided.

These discharge openings can either be arranged laterally, namely ent neither on the pressure side of the turbine blade, nor on the suction side of the turbine blade or at the rear edge. But it could also go radially outwards outgoing exhaust openings may be provided.

The crown cooling is particularly effective, if according to another way leadership form of the invention, the cavities as circumferential around the blade crown Cooling slots are formed. There can be a single continuous cooling slot be provided. But there can also be several separate cooling slots in The circumferential direction of the blade crown can be arranged one behind the other and through separate discharge openings are connected to the outside space.  

Localized cooling at particularly critical points on the blade crown leaves can be achieved if, according to another embodiment, the cavities as individual pockets connected to one another by connecting channels det.

The cooling effect of the cooling air flowing through the cavities can be continued increase if according to another preferred embodiment of the inven in the cavities or cooling slots or pockets means for improvement tion of the heat transfer between cooling air and rails are provided. These agents can in particular in the cavities or cooling slots or Pocketed turbulators or pins that contain the turbulence in increase the cooling air flow. In this context, the following are also conceivable rods or rip arranged in the cavities or cooling slots or pockets pen. But it is also conceivable that the means changes in the flow cross cut, especially in the form of a sequence of narrowing and expansion gene, in the cavities or cooling slots or pockets.

The cavities in the blade crown are preferably completely cast educated. Alternatively, however, the hollow can be used to simplify production spaces are formed as recesses in the blade crown, which through a cover plate, an attachment or a closure can be closed.

Further embodiments result from the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

In the following, the invention is to be described using exemplary embodiments together Menhang be explained in more detail with the drawing.

Show it:  

FIG. 1 shows in longitudinal section a blade crown of the prior art without any special cooling measures for the blade crown;

Fig. 2 in a representation equivalent to Figure 1, a first preferred embodiment of a turbine blade with targeted cooling ter crown according to the invention.

Fig. 3 is a perspective side view with a longitudinally cut crown of a blade crown with cooling according to Figure 2, wherein the cooling air of the crown is blown sen on the pressure side of the blade.

FIG. 4 shows a solution according to the invention that is comparable to FIG. 3, the cooling air being blown out at the rear edge of the blade;

FIG. 5 shows a solution according to the invention that is comparable to FIG. 3, the cooling air being blown out on the suction side of the blade and the inner region of the crown being connected to the cooling slot of the crown via a connecting channel;

FIG. 6 shows a solution according to the invention comparable to FIG. 3, wherein a plurality of cooling slots arranged one behind the other with separate blow-out openings are provided;

Fig. 7 is a blade crown according to the invention are in uncut by spectral TiVi shear side view, being provided on the upper surface radially outwardly reaching exhaust openings for the cooling air;

FIG. 8 a crown comparable to FIG. 2 with additional lateral blow-out of cooling air to the outside on the hot gas side of the blade;

Fig. 9 is a comparable to Figure 8 side blowout into the interior of the crown;

Fig. 10 in a representation comparable to Figure 2 cooled crowns according to the invention with different outer contour (Teilfigu ren A and B) and additional means in the cooling slots to improve cooling (sub-figures C and D);

Fig. 11 different, differing from the rectangle shapes of the cross-sectional profile of the cooling slots or cavities in a crown cooling according to the invention;

12 shows in side view an embodiment of the invention with cooling cavities in the form of interconnected bags.

Fig. 13 shows the example of Figure 12 in plan view from above.

Fig. 14 is different in various subfigures AD measures to improve the heat transfer into the cooling slots of a blade according to the invention the cooled crown;

Fig. 15 is another embodiment of the invention, in which a direct connection between the cooling slots and the cooling duct is produced by suitable shaping, in cross-section (partial figure A) and in longitudinal section (figure part B);

FIG. 16 is an embodiment of the invention, wherein the cooling slots by welding, soldering, or otherwise applying generated by cover plates to the crown;

FIG. 17 shows an exemplary embodiment comparable to FIG. 16, in which a cover plate is inserted, and

Fig. 18-21 further embodiments of the invention, in which the cooling slots in the crown using cover plates, Aufsät zen or closures are realized.

WAYS OF CARRYING OUT THE INVENTION

A first preferred embodiment of the invention is shown in FIGS. 2 and 3. In order to lower the crown temperature, 8 additional cooling slots 9 are introduced into the circumferential rails ("rails") 6 and 7 of the blade crown. As can be easily seen from FIG. 2, the ratio of the crown surface wetted with cooling air to the crown surface exposed to the hot gas improves significantly because the inner walls of the cooling slots 9 are added to the wetted surfaces. Due to the additional cooling air surface, the heat can be dissipated better and the material temperature of the crown can be significantly reduced. The circumferential cooling slots 9 are fed through one or more cooling air holes 10 from the cooling channels 4 of the turbine blade 1 . The cooling air bores 10 are formed in this example for the sake of producibility because of the passage from the cooling channel 4 through the cooling slots 9 to the outside through bores, which are each closed to the outside by a closure ( 11 ). The cooling air flows through the circumferential cooling slot 9 and is preferably blown out in the region of the rear edge of the turbine blade 1 through a suitable blow-out opening ( 14 in FIG. 3).

In Fig. 3, the Hinterkantenausblasung is realized on the pressure side 3 of the turbine blade 1. The trailing edge blow-out can also take place directly through a blow-out opening 15 arranged in the rear edge 16 ( FIG. 4), or through a blow-out opening 17 on the suction side 2 of the blade ( FIG. 5). If it is advantageous, then - as shown in Fig. 6 - the cooling air through successively arranged separate cooling slots 9 , 9 'and 9 "and through several Ausblasöff openings 14 , 19 and 20 at one or more other locations of the crown This can be done - as shown in Fig. 6 - towards the hot gas side (outwards) or, if this is advantageous, into the crown itself (inwards). For each separate cooling slot or Cooling slot segment 9 , 9 ', 9 "requires one or more cooling air holes 10 for supplying cooling air.

However, it is also possible here that the air is blown out in a defined cross section, which is exposed to severe overheating. This then helps to reduce the effective flow cross-section over the crown. This makes it possible to locally cool the blade crown 8 . FIG. 7 in connection with FIG. 2 shows such an example. In Fig. 7 ( Fig. 2) the local blowout is shown radially outwards sen, ie, perpendicular to the top surface of the crown, by means of corresponding blowout openings 12 , 13 . FIGS. 8 and 9 show a lateral blow-out . In FIG. 8, cooling air is blown radially outward from the cooling channel 4 through blow-out openings 21 running obliquely upwards on the hot gas side. In Fig. 9 cooling air is blown through cooling air holes 23 , the cooling slot 9 and Ausblasöff openings 22 in the interior of the crown.

The cooling slot 9 need not be seen on both sides (in both rails 6 , 7 ). It is also possible that it is only present on one side or only at one or more specific locations on the crown (depending on the requirements of the construction). Depending on what offers the greater advantage for the construction, the interior of the crown can be connected to the rear edge by a connecting channel 18 (see FIGS. 5 and 6) or without connection (see FIGS. 3 and 4).

Fig. 10A-D and Fig. 11A-C show further possible variants of the rail geometry in cross section. The cross section does not have to be rectangular, but can have any shape on the inside (see, for example, FIGS. 11A-C), and on the outside on the edge contours 24 , 25 ( FIGS. 10A, B), depending on the requirements of the con structure.

The cooling slot 9 can also be provided with fluidic means who make it possible to adjust the heat transfer locally according to the requirements of the construction. Possible examples of this are turbulators 26 ( FIG. 10C) or rods 27 ( FIG. 10D) arranged in the cooling slot. Another example are the cross-sectional profiles of a cooling slot 9 (section in the longitudinal direction of the rails) in FIGS. 14A-D.

The circumferential cooling slot 9 or the cooling slot segments 9 , 9 ', 9 "can already be incorporated into the turbine blade during casting. They can be closed or open at the top. In the event that they are open at the top, they are welded be to close wide-gap brazing or other suitable method. in Fig. 17 a closure variant with soldered or welded-in cover plate 39 is shown. the cooling air holes or holes for cooling air supply in the cooling slot 9 or the cooling slot segments 9, 9 ', 9 "can be poured or subsequently drilled. Drilling with laser, EDM, water jet or any other method are conceivable. In the case of the bore ( 10 ), it may be necessary to close the hole or the holes from the hot gas side (see closure 11 in FIGS. 2 and 3) in order to keep enough cooling air in the slot and not too much to the surface to lose.

However, the circumferential cooling slot 9 or the cooling slot segments 9 , 9 ', 9 "can also be worked in later. Processing with laser, EDM, water jet or any other method are conceivable. The open cooling slot 9 or the open cooling slot segments 9 , 9 ', 9 "must then be closed by welding, wide-gap soldering or another suitable method. The cooling air bores 10 for supplying cooling air into the cooling slot 9 or the cooling slot segments 9 , 9 ', 9 "can be drilled subsequently or already cast in. Drilling with laser, EDM, water jet or any other method are conceivable. Both for the drilled and For the cast-in cooling air holes or holes, it may also be necessary to close the hole or holes from the hot gas side (see Fig. 3 and 4) in order to keep enough cooling air in the slot and not too much to the surface to lose.

FIGS. 12 and 13 show a further embodiment of the invention. Here are in the crown area (the rails 6 , 7 ) small pockets 28 poured (or made differently), which are connected to each other by Ver connection channels 30 in the example shown. This makes it possible to cool the crown area very efficiently, precisely where the local temperatures are too high. The supply of the cooling air to the pockets 28 takes place through cooling air bores 29 , the removal by blowing out through blowout openings 31st Any number of pockets 28 can be connected to one another. The pockets 28 - as indicated in FIGS . 12 and 13 - do not necessarily have to be connected to one another. The blow-out openings 31 can also be designed like the blow-out openings 14 , 15 , 17 , 19 and 20 in FIGS. 3 to 6.

Fig. 14A-D show - as already mentioned - various variable profiles of the cooling slot cross section in a longitudinal section parallel to the direction of rotation of the rails. The cooling effect can be influenced in a targeted manner by appropriate arrangement of constrictions 32 and extensions 33 ( FIG. 14A) or of ribs 34 , 35 ( FIG. 14B, D). The same applies to a meandering course of the cooling slot according to FIG. 14C.

Fig. 15 shows a variant in which at various points along the circumference the cooling slot extends deeper or has a recess 36 (production by casting, eroding or any other manufacturing method) in order to supply cooling air from the cooling channel 4 into the cooling slot or slots 9 or 9 , 9 'and 9 "to realize. The production is less expensive, since there are no holes or bores on the hot gas side, which must be closed again.

Fig. 16 shows a variant with a built cooling slot 9 in the blade crown. 8 The cooling slot 9 is formed from the cast blade crown 8 and a built-in cover plate 37 in a suitable shape. The cover plate 37 is attached by welding, soldering or another suitable method. The cooling air is supplied via cooling air bores 38 from the cooling duct 4 .

Fig. 18 to 21 show further variants built cooling slots 9. In Fig. 18, the eroded, drilled, cast or by another suitable method he created open channel by a soldered, welded or attached in another suitable connection technique attachment 40 is closed. FIGS. 20 and 21 show forms of the cap 43 or 44 with an enlarged contact area, which may be for certain bonding techniques advantageous. In order to prevent such by centrifugal force and rubbing loaded seams, according to Fig. 19 also eroded laterally and are closed by closures 41st Closures 41 introduced laterally can be provided with pins 42 , ribs or other turbulators. These turbulators can then serve as spacers when joining the components and to increase the cooling effectiveness. Lateral manufacturing solutions can be made from the hot gas or crown inside.

Overall, the invention results in a cooled rotor blade which is characterized by economical and highly effective cooling in the area of the blade crown draws, and flexible to different manufacturing methods and use lets you customize your surroundings.

REFERENCE SIGN LIST

1

Turbine blade

2nd

Suction side

3rd

Printed page

4th

Cooling channel

5

cap

6

,

7

rail

8th

Bucket crown

9

,

9

',

9

"Cooling slot

10th

Cooling air hole

11

Clasp

12th

,

13

Discharge opening

14

,

15

,

17th

Discharge opening

16

Trailing edge

18th

Connecting channel

19th

,

20th

Discharge opening

21

,

22

Discharge opening

23

Cooling air hole

24th

,

25th

Edge contour

26

Turbulator

27

Rod

28

bag

29

Cooling air hole

30th

Connecting channel

31

Discharge opening

32

Narrowing

33

extension

34

,

35

rib

36

deepening

37

Cover plate

38

Cooling air hole

39

Cover plate

40

,

43

,

44

Essay

41

Clasp

42

Pin code

Claims (22)

1. turbine blade ( 1 ) for the rotor of a gas turbine, which turbine blade ( 1 ) has at its free end a blade crown ( 8 ) with a cap ( 5 ), which cap ( 5 ) on the edge of radially outwardly projecting rails ( 6 , 7 ) is characterized in that for better cooling of the blade crown ( 8 ) inside the rails ( 6 , 7 ) through which cooling air flows hollow spaces ( 9 , 9 ', 9 "; 28 ) are accommodated. 2. Turbine blade according to claim 1, characterized in that in the interior of the turbine blade ( 1 ) below the cap ( 5 ) at least one cooling channel be opened with cooling air ( 4 ) is provided, and that the cavities ( 9 , 9 ', 9 '; 28 ) in the rails ( 6 , 7 ) for supplying cooling air with the at least one cooling duct ( 4 ). 3. Turbine blade according to claim 2, characterized in that for connecting the cavities ( 9 , 9 ', 9 "; 28 ) with the at least one cooling channel ( 4 ) over the blade crown ( 8 ) distributed a plurality of cooling bores ( 10 ) see easily are. 4. Turbine blade according to claim 3, characterized in that the cooling bores ( 10 ) as from the at least one cooling channel ( 4 ) through the cavities ( 9 , 9 ', 9 "; 28 ) to the outside continuous through bores are formed, which according to on the outside are each closed by a closure ( 11 ). 5. Turbine blade according to claim 2, characterized in that for connecting the cavities ( 9 , 9 ', 9 "; 28 ) with the at least one cooling channel ( 4 ), the cavities ( 9 , 9 ', 9 '; 28 ) at predetermined locations ( 36 ) go directly into the least one cooling channel ( 4 ). 6. Turbine blade according to one of claims 2 to 5, characterized in that for removing the cooling air from the cavities ( 9 , 9 ', 9 "; 28 ) at given points of the blade crown ( 8 ) from the cavities ( 9 , 9 ', 9 "; 28 ) discharge openings ( 12 ,..., 15 , 17 , 19 , 20 , 31 ) leading into the outside space are provided. 7. Turbine blade according to claim 6, characterized in that the blow-out openings ( 14 , 15 , 17 , 19 , 20 ) are arranged laterally. 8. Turbine blade according to claim 7, characterized in that the blow-out openings ( 14 , 20 ) on the pressure side ( 3 ) of the turbine blade ( 1 ) are arranged. 9. Turbine blade according to claim 7, characterized in that the blow-out openings ( 17 , 19 ) on the suction side ( 2 ) of the turbine blade ( 1 ) are arranged. 10. Turbine blade according to claim 7, characterized in that the blow-out openings ( 15 ) on the rear edge ( 16 ) of the turbine blade ( 1 ) are net angeord. 11. Turbine blade according to claim 6, characterized in that ra dial outward outlet openings ( 12 , 13 , 31 ) are provided. 12. Turbine blade according to one of claims 1 to 11, characterized in that the cavities are formed as cooling slots ( 9 , 9 ', 9 ") surrounding the blade crown ( 8 ). 13. Turbine blade according to claim 12, characterized in that a single continuous cooling slot ( 9 ) is provided. 14. Turbine blade according to claim 12, characterized in that a plurality of separate cooling slots ( 9 , 9 ', 9 ") are arranged one behind the other in the circumferential direction of the blade crown ( 8 ) and are connected to the outside space by separate blow-out openings ( 14 , 19 , 20 ) . 15. Turbine blade according to one of claims 1 to 11, characterized in that the cavities are designed as individual pockets ( 28 ) connected to one another by connecting channels ( 30 ). 16. Turbine blade according to one of claims 1 to 15, characterized in that in the cavities or cooling slots or pockets ( 9 , 9 ', 9 ", 28 ) means for improving the heat transfer between cooling air and rails ( 6 , 7 ) are provided. 17. Turbine blade according to claim 16, characterized in that the means in the cavities or cooling slots or pockets ( 9 , 9 ', 9 ", 28 ) comprise arranged turbulators ( 26 ) or pins ( 42 ). 18. Turbine blade according to claim 16, characterized in that the means in the cavities or cooling slots or pockets ( 9 , 9 ', 9 ", 28 ) comprise arranged rods ( 27 ). 19. Turbine blade according to claim 16, characterized in that the means in the cavities or cooling slots or pockets ( 9 , 9 ', 9 ", 28 ) comprise arranged ribs ( 34 , 35 ). 20. Turbine blade according to claim 16, characterized in that the means changes in the flow cross-section, in particular in the form of a sequence of constrictions ( 32 ) and extensions ( 33 ), in the cavities or cooling slots or pockets ( 9 , 9 ', 9 ", 28 ). 21. Turbine blade according to one of claims 1 to 20, characterized in that the cavities ( 9 , 9 ', 9 ", 28 ) in the blade crown ( 8 ) are completely formed by casting. 22. Turbine blade according to one of claims 1 to 20, characterized in that the cavities ( 9 , 9 ', 9 ", 28 ) are formed as recesses in the blade crown ( 8 ), which by a cover plate ( 37 , 39 ) , an attachment ( 40 , 43 , 44 ) or a closure ( 41 ) can be closed.