EP0984138B1 - Turbomachine with shaft cooling - Google Patents

Description

Technical area

The invention relates to a turbomachine, in particular a compressor of a Gas turbine, according to the preamble of claim 1.

State of the art

In turbomachinery with high thermal load, especially at compressor stages modern gas turbines, the rotor shaft is particularly endangered To look at component. Due to the extreme temperature loads, the life decreases drastically reduced, so that additional Measures must be taken to solve this problem.

A first approach is to provide so-called heat shields, the prevent direct contact of the heated flow medium with the rotor shaft and thus their warming within the limits considered admissible to hold. The disadvantage here is the increase in manufacturing costs and Complexity of the turbomachine due to the additional components.

Another approach is to use the rotor shaft of a material with to produce improved high-temperature behavior. Although such materials are available in practical use in addition to increased material costs Problems due to a different temperature-expansion behavior in the Comparison to the materials of neighboring components. In particular transient processes, such as starting the machine, prepare by the different ones Time-dependent temperature expansion behavior enormous difficulties.

Finally, it is also known rotor shafts made of conventional materials To cool a central coolant hole, which passes through the rotor shaft. A However, such a solution is extremely cost-intensive and, moreover, less effective.

EP 0 790 390 discloses a cooling device with which the rotor shaft at most indirectly and could be cooled effectively.

Presentation of the invention

The invention seeks to avoid the disadvantages described. She is the one The object of the invention is to specify a turbomachine of the type mentioned at the outset, which allows to cool the rotor shaft locally with high efficiency, so that the life expectancy of the rotor shaft even at extremely high thermal Burden is not appreciably affected.

According to the invention this is achieved in that individual or all vanes are formed as cooling vanes, which from a cooling air supply are fed. The cooling vanes are configured to be in substantially Radial direction of air ducts are interspersed and in the area the blade tips have blower openings aligned with the rotor shaft are.

The advantages of the invention are various in nature and both relate to technical-constructive simplifications as well as aero-thermodynamic aspects.

One of the main advantages of the invention is the fact that by the direct Actuation of the rotor shaft with cooling air optimizes the achievable cooling effect can be. Even a comparatively small amount of cooling air is sufficient to keep the rotor shaft locally at a low temperature level. The latter effect can be used in various ways.

On the one hand, it is possible to produce conventional, low-cost materials for production to use the rotor shaft, even if a higher pressure ratio than before is realized.

Even in thermally heavily loaded high-pressure compressor stages can on heat shields be completely dispensed with, since the rotor shaft are selectively cooled locally can.

Due to the high cooling efficiency, it may be sufficient, only individual Form vanes of a vane ring as cooling vanes. As a general rule However, all blades of a blade ring cooled because in this way an optimally uniformed loading of the rotor shaft with Cooling air can be achieved.

On the other hand, the life of the blading increases due to the cooling air caused lower temperature levels. This does not just affect the Cooling blades, which are flowed through by cooling air, but also the downstream, not cooled blade rings.

Overall, the compressor outlet temperature is lowered, so that the improved aero-thermodynamic efficiency of the compressor.

Also, the exiting at the blade tips cooling air causes an improvement the fluidic properties. So on the one hand, the boundary layer Kinetic energy is supplied locally by the cooling air flow and influences it positive by that. On the other hand prevents the exiting cooling air flow at appropriate Design or arrangement of the exhaust openings a flow around the vanes in the gap between the blade tips and the rotor shaft. Leakage losses in this area are thus almost completely avoided.

By improving these aero-thermodynamic conditions shows the Compressors also improved performance, which also translates into a significant Raising the surge limit precipitates.

By varying Auslagungsparametem the air ducts, such as Number, dimension or location of attachment, can be the vibration behavior the blades vary within wide limits. This makes it possible to tune the natural frequency and flutter characteristics within limits so that critical vibration states no longer occur.

The attachment of the air ducts on the vanes designed in the Generally conceivable simply and cost-effective, since cooling blades are specially in the thermal highly loaded rear stages of compressors are provided and these Guide vanes are usually not or only slightly twisted. The air ducts can therefore usually be performed as simple holes that the each guide vane radially fully enforce or as in the axial direction tilted inclined from a central air duct.

The cooling device according to the invention has the additional advantage that it can be controlled very easily and precisely. The cooling air can be immediate upstream or downstream compressor stages are removed needs however, still a conditioning to the effect that they with higher pressure and lower temperature is fed than the local state variables the main flow corresponds. As far as cooling air, a cooling air flow from a higher Compressor is removed, it must be cooled. If, on the contrary a cooling air flow is taken from a lower compressor stage, this must first be further compressed externally and then cooled.

The cooling concept according to the invention can also be used to particular advantage with guide wheels be applied with a shroud. The shroud allows a even more even education of the cooling film in the circumferential direction, since the exiting cooling air partial flows are not detected directly from the main flow and be carried away.

Further preferred embodiments of the invention are directed to the Cooling air at the same time to influence the gap width between the vane tips and to use the rotor shaft. For this purpose, the cooling blades are in radial Directed displaced and are against the action of return springs moved out of its initial position by the pressure of the cooling air. This makes it possible to control the compressor efficiency and in particular the Considerably increase the pumping limit. This effect is in modern high pressure compressor stages clearly pronounced, because here for safety reasons because of sluggish response large slit widths must be provided to to reliably prevent a run-in of the blade tips in the rotor shaft.

The return springs are a safety measure in the event that the Cooling air supply should be interrupted. The cooling blades return immediately back to their original position and thus increase the gap between the blade tips and the rotor, so this in the case of a then thermally induced strong radial expansion not in contact with the Shovel tips can come.

According to a structurally particularly simple implementation of this concept is the blade root of the cooling blades is provided with a piston-shaped section, in a correspondingly shaped cylindrical housing section is performed sealed to form a working space. The workroom is standing in connection with the cooling air supply, so that when exposed to Cooling air in the manner of a pneumatic cylinder, the cooling blades are pushed out can.

Preferably, the air ducts of the cooling air blades are in communicating Connection with the respective working space, whereby the air flow is particularly simply designed. The air flow fed by the cooling air supply first enters the working space and causes the radial displacement the shovel. From the working space of the cooling air flow now occurs directly in the air ducts and leaves the blade in the blade tip through the bubble openings. The tuning of the geometry of the air-conveying Channel sections and the pressure conditions in the compressed air supply is such that the air jets emerging from the blow-out openings is at high speed own and at high speed on the opposite impinge arranged rotor shaft. The resulting impact cooling ensures an optimal heat transfer and thus an optimal cooling effect for the rotor shaft.

Advantageously, two adjacent cooling blades are fixed to each other connected and positively coupled slidably mounted. Simplified further the structural design of the storage, without the cooling effect disadvantageous to influence.

The air ducts are preferred as bores, in particular as radial Through holes performed, resulting in minimal production costs to let hold.

Preferably, the cooling blades each have a plurality, in particular parallel to each other extending air ducts on, so that at each of the cooling blades can form several partial cooling air jets. This allows the cooling of a Axial section of the rotor shaft corresponding to the axial width of the respective Stator.

A similar effect can be achieved even if in each case several radialmündende Purging openings are provided, which are on a common air duct access. Such a solution is for example in such Used cooling vanes, which are displaceable by means of a piston-shaped portion are equipped on the blade foot and therefore for reasons of space no Allow multiple arrangement of through holes.

Short description of the drawing

In the drawings, embodiments of the invention are shown.

Fig. 1

Verdichterstufe im Teillängsschnitt;

Fig. 2

Schnitt A-A gem. Fig. 1 in vergrößerter Darstellung;

Fig. 3

erste Ausführungsvariante, Teillängsschnitt;

Fig. 4

zweite Ausführungsvariante, Teilansicht im Axialschnitt;

Fig. 5

dritte Ausführungsvariante, Teilansicht im Axialschnitt;

Fig. 6

vierte Ausführungsvariante im Teillängsschnitt mit einstellbarer Spaltbreite;

Fig. 7

Ansicht von links gem. Fig. 6;

Fig. 8

weitere Ausführungsvariante mit einstellbarer Spaltbreite, Teilansicht im Axialschnitt.

Show it:

Fig. 1

Compressor stage in partial longitudinal section;

Fig. 2

Section AA acc. Fig. 1 in an enlarged view;

Fig. 3

first embodiment, partial longitudinal section;

Fig. 4

second embodiment, partial view in axial section;

Fig. 5

third embodiment, partial view in axial section;

Fig. 6

fourth embodiment in partial longitudinal section with adjustable gap width;

Fig. 7

View from the left acc. Fig. 6;

Fig. 8

further variant with adjustable gap width, partial view in axial section.

Only the essential elements for the understanding of the invention are shown, partially using only the function clarifying, abstract symbols were.

Way to carry out the invention

The concept of rotor cooling on which the invention is based results in particular from Figs. 1 and 2. It is a typical compressor stage of a high pressure compressor with a rotor and a stator, symbolized by a bucket 11 and vane 12 shown. The blades 11 are in itself known manner to a rotor shaft 18 which rotates in the direction of rotation D. is drivable.

The blades 11, the vanes 12 are connected downstream, which in known Way on a housing portion 17 - and thus fixed - attached are.

The vanes 12 are formed as cooling vanes. They point to this Purpose air ducts 13, which are continuous in the radial direction within extend the cooling blade 12 and in the region of the blade tip 15 as Outlet openings 14 open. The blow-out openings 14 are on the rotor shaft 18 aligned.

The air ducts 13 are in a manner not shown with a Cooling air supply connected, which supplies cooling air. The pressure is like this chosen that cooling air jets K at high speed from the exhaust openings 14 emerge and impinge on the immediately adjacent rotor shaft 18. The cooling effect achieved by this is enormous, since the heat transfer coefficient - And thus the transferable cooling energy - is very high.

As can be seen for example in FIG. 2, the cooling air ducts 13 do not have to inevitably have a circular cross-section. So, for example the cross-sectional shape optimally to the profile cross-sectional shape of the guide vane 12th be adapted so that realize a high and optimally distributed air flow leaves. On the other hand, further advantages result from the fact that the guide vane 12 or the surface around which it flows, is cooled from the inside. With it reduced also the thermal stress of the vane 12 with the so associated benefits of prolonged life or the ability to already allow a higher process temperature at the time of design.

FIGS. 3 to 5 show different application variants in the concrete implementation the cooling concept of the invention.

A rotor shaft 38 has a circumferential groove in the axial section to be cooled 39, in which a cooling blade 32 projects radially with its blade tip 35. Again, blow-out openings 34 are provided by the cooling air jets K escape.

This configuration may have u. a. the advantage that the exiting cooling air K is not immediate is detected by the main flow H and entrained. This is the result local cooling effect more pronounced than, for example, in the above-described Configuration.

The embodiment shown in Fig. 4 has cooling blades 42, which with a Shroud 46 in the region of the blade tips 45 are interconnected. Again, blower openings 44 are arranged in the area of the blade tips 45, exit through the cooling air jets K. These meet directly opposite each other on a rotor shaft 48 and cool them locally. Between the Shroud 46 and the rotor 48 is a circumferentially continuous annular gap 49 exists, so that in this case, a certain retention effect for the exiting cooling air jets K is given.

In the embodiment of FIG. 5 cooling vanes 52 are present, which Blade tips 55 which extend radially in the direction of a rotor shaft 58 in a funnel shape. In the area of the blade tips 55 are in turn Blow-out openings 54 are provided, ejected by the cooling air jets K. become. The funnel shape of the blade tips 55 allows the admission the rotor shaft 58 along a larger peripheral portion than at radial straight ended blades would be possible.

Allen above embodiments is common that by the exiting Cooling air jets K a flow around the blade tips 15, 35, 45, 55th By partial flows of the main flow H largely or even completely prevented becomes. The surge limit of such cooled compressor stages are thus significantly higher than comparable compressors without cooling device from the State of the art.

In the embodiments of FIG. 6 to 8 is a further increase in Pumping limit and a further increase in the compressor efficiency thereby possible that the radial gap of the stator set during operation, d. H. can be downsized.

According to the embodiment variant shown in FIGS. 6 and 7, cooling vanes have 62 a blade root 67 in the manner of a piston-shaped radial section on, in a correspondingly shaped cylindrical housing portion 78 is slidably mounted. It creates a working space 77, in a supply channel 76 opens. Through the supply channel 76 is off the cooling air supply cooling air, not shown here, the working space 77th fed.

The blade root 67 is provided with sealing rings 73, so that in this way the working space 77 sealed relative to the cylindrical housing portion 78 is. As soon as the working space 77 is charged with cooling air, a displacement takes place the cooling blade 62 on the rotor shaft 68 back. Furthermore, cooling air occurs from the working space 77 in air ducts 63 and exits through Blow-out openings 64. The displacement movement of the cooling blade 62 takes place against the effect of return springs 74, the between the blade root 67 and the housing portion 78 act in the region of the working space 77. The return springs 74 on the one hand have the effect that they the cooling blade 62 when turned off Pull back cooling air supply and in this way a gap 70 between the blade tips 65 and the rotor shaft 68 is set so broad is dimensioned that a running-in of the blade tip 65 in the rotor shaft 68 safely is prevented. On the other hand, when the cooling air supply is switched on Gap 70 reduced so far, so that by the ejected cooling air flows K a Air cushion is formed in the gap 70, which not only cools the rotor shaft 68, but also a flow around the cooling blade 62 in the region of the gap 70 reliably prevented. The compressor efficiency and the surge limit can be thereby optimally increase.

The width of the gap 70 can, with appropriate control of the cooling air supply be made variably adjustable. A particularly simple constructive But solution can also be achieved in that one is not closer illustrated stop is provided, the displacement of the cooling blade 62 limited and thus dictates the minimum width of the gap 70.

The variant shown in FIGS. 6 and 7 is further characterized by each of the vanes 62 of a vane ring is individually slidable is stored. This configuration includes an additional safety aspect in that in the case of a local disturbance with a single cooling blade 62 - for example, with obstruction of the air duct 63 - the affected Cooling blade 62 returns to its original position. One in consequence of the missing internal cooling of the cooling pad 62 caused thermal expansion in radial Direction does not lead to a run-in of the blade tip 65 in the rotor shaft 68th

The variant shown in Fig. 8 shows a tandem arrangement of two cooling blades 82 on a common blade carrier 87. In the range of blade tips 85, a shroud 86 is provided. Again, cooling air jets K ejected from the cooling vanes 82 via discharge openings 84 and bounce on a rotor shaft 88.

In contrast to the embodiment described above, both are here Cooling vanes 82 configured jointly radially displaceable. A return spring 94 acts directly on the blade carrier 87 a. This is a housing section 98 as a rear stop for the blade carrier 87. The cooling air K each of the two cooling blades 82 is supplied separately, wherein as a length compensation a respective bellows 95 between a supply channel 96 and the blade carrier 87 is arranged.

LIST OF REFERENCE NUMBERS

11

blade

12

Cooling blade, vane

13

Air duct

14

blowoff

15

blade tip

17

housing section

18

rotor shaft

32

cooling scoop

34

blowoff

35

blade tip

38

rotor shaft

39

groove

42

cooling scoop

44

blowoff

45

blade tip

46

shroud

48

rotor shaft

49

annular gap

52

cooling scoop

54

blowoff

55

blade tip

58

rotor shaft

62

cooling scoop

63

Air duct

64

blowoff

65

blade tip

67

blade

68

rotor shaft

70

gap

73

sealing ring

74

Return spring

76

supply channel

77

working space

78

housing section

82

cooling scoop

84

blowoff

85

blade tip

86

shroud

87

blade carrier

88

rotor shaft

94

Return spring

95

bellows

96

supply channel

98

housing section

H

mainstream

K

cooling air

D

direction of rotation

Claims (10)

1. Turbomachine, in particular a compressor of a gas turbine with rotor blades and guide vanes which are associated with at least one rotor row and one guide vane row, and having at least one rotor shaft which is cooled by means of a cooling device, wherein individual or all guide vanes (12, 32, 42, 52, 62, 82) are configured as cooled vanes fed by a cooling air supply in such a way that they have air guidance ducts (13, 63) passing through them, characterized in that they have outlet openings (14, 34, 44, 54, 64, 84), which are directed toward the rotor shaft (18, 38, 48, 68, 88), in the region of the vane tips (15, 35, 45, 55, 65, 85) in such a way that the rotor shaft is directly subjected to cooling air.
2. Turbomachine according to Claim 1, characterized in that individual or all guide vanes of a guide vane row are configured as cooled vanes (12, 32, 42, 52, 62, 82).
3. Turbomachine according to Claim 2, characterized in that the guide vane row has a shroud (46, 86).
4. Turbomachine according to Claim 2, characterized in that the cooled vanes (12, 32, 42, 52, 62, 82) are supported so that they can be displaced from an initial position, against the action of return springs (74, 94), by the pressure of the cooling air (K) .
5. Turbomachine according to Claim 4, characterized in that the vane root (67) of the cooled vanes (62) has a piston-shaped section which is guided, in a sealed manner, in a corresponding cylindrical casing section (78), thus forming a working space (77), the working space (77) being in communicating fluid connection with the cooling air supply.
6. Turbomachine according to Claim 5, characterized in that the air guidance duct (63) is in communicating fluid connection to the respective working space (77).
7. Turbomachine according to one of Claims 4 to 6, characterized in that each two adjacent cooled vanes (82) are firmly connected together and can be displaced while positively coupled together.
8. Turbomachine according to one of the preceding claims, characterized in that the air guidance ducts (13, 63) are configured as holes or as through-holes.
9. Turbomachine according to one of the preceding claims, characterized in that the cooled vanes (12, 32, 52, 62, 82) each have a plurality of air guidance ducts (13) respectively extending parallel to one another.
10. Turbomachine according to one of the preceding claims, characterized in that the cooled vanes (12, 32, 42, 52, 62, 82) each have a plurality of outlet openings (14, 34, 44, 54, 64, 84) respectively emerging at the vane tip (15, 35, 45, 55, 65, 85).

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