EP0984138A2 - Turbomachine with shaft cooling - Google Patents

Abstract

Turbomachine, in particular compressor of a gas turbine, with moving blades (11) and guide blades (12), in which some or all of the guide blades (12) are designed as cooling blades. The cooling blades (12) have air guide channels (13) which open into blow-out openings (14) in the region of the blade tips (15). Cooling air (K) is expelled through the blow-out openings (14) and strikes a rotor shaft (18) at high speed. The cooling effect that can be achieved in this way is optimal and also leads to an increase in the compressor efficiency and the surge limit.

Description

Technical field

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

State of the art

For turbo machines with high thermal loads, especially with compressor stages modern gas turbines, the rotor shaft is particularly vulnerable Component to consider. As a result of the extreme temperature loads, the service life is reduced conventionally used materials drastically, so that additional Measures need to be taken to solve this problem.

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

Another solution is to use a rotor shaft made of one material to produce improved high-temperature behavior. Although such materials are available, result 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. Especially transient processes, such as starting the machine, prepare by the different time-dependent temperature expansion behavior enormous difficulties.

Finally, it is also known to use rotor shafts made from conventional materials to cool a central coolant hole that passes through the rotor shaft. A however, such a solution is extremely expensive and, moreover, not very effective.

Presentation of the invention

The invention tries to avoid the disadvantages described. You are the Based on the task of specifying a turbomachine of the type mentioned at the outset, which allows the rotor shaft to be cooled locally with high efficiency, so that the life expectancy of the rotor shaft even at extremely high thermal Load is not significantly affected.

According to the invention, this is achieved in that individual or all guide vanes are designed as cooling blades, which are from a cooling air supply are fed. The cooling blades are designed such that they essentially are penetrated in the radial direction by air guide channels and in the area of the blade tips have blow-out openings that are aligned with the rotor shaft are.

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

One of the main advantages of the invention can be seen in that the direct Applying cooling air to the rotor shaft optimally designs the achievable cooling effect can be. 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 different ways.

On the one hand, it is possible to manufacture conventional, inexpensive materials to use the rotor shaft, even if a higher pressure ratio than before is realized.

Even in high-pressure compressor stages with high thermal loads, heat shields can be used can be completely dispensed with because the rotor shaft is locally cooled in a targeted manner can.

Due to the high cooling effectiveness, it may be sufficient, just a few To form guide vanes of a guide vane ring as cooling blades. As a general rule However, all the blades of a blade ring are cooled because in this way an optimally even application of the rotor shaft Can achieve cooling air.

On the other hand, the lifespan of the blading increases as a result of the cooling air caused lower temperature levels. This does not only concern that Cooling blades through which cooling air flows, but also the downstream, not refrigerated shovel rings.

Overall, the compressor outlet temperature also drops, so that the Aero-thermodynamic efficiency of the compressor improved.

The cooling air emerging at the blade tips also brings about an improvement the fluid mechanical properties. So on the one hand the boundary layer kinetic energy is locally supplied and influenced by the cooling air flow thereby positive. On the other hand, the emerging cooling air flow prevents the corresponding Design or arrangement of the blow-out openings a flow the guide vanes in the gap between the blade tips and the rotor shaft. Leakage losses in this area can therefore be avoided almost completely.

By improving these aero-thermodynamic conditions, the Compressors also have improved operating behavior, which can also be seen in a clear Raising the surge limit is reflected.

By varying the design parameters of the air duct, such as Number, dimensioning or location of attachment, the vibration behavior can be of the blades vary within wide limits. So it is possible to coordinate the natural frequency and flutter characteristics within limits so that critical vibration states no longer occur.

The attachment of the air duct to the guide vanes is in the Usually very easy and inexpensive, because cooling blades are especially thermal highly loaded rear stages of compressors and these Guide vanes are usually not or only slightly twisted. The air ducts can therefore usually be carried out as simple holes that the Push through the respective guide vane completely radially or as in the axial direction branch at an angle from a central air duct.

The cooling device according to the invention also has the advantage that it can be controlled very easily and precisely. The cooling air can do this immediately upstream or downstream compressor stages are required However, another preparation in such a way that it with higher pressure and is fed in at a lower temperature than the local state variables corresponds to the main flow. If a cooling air flow from a higher one than cooling air Compressor stage is removed, it must be cooled. If on the other hand a cooling air flow is taken from a lower compressor stage, it must first be further compressed externally and then cooled.

The cooling concept according to the invention can also be particularly advantageous for idlers can be applied with a cover tape. The cover tape enables one even more uniform formation of the cooling film in the circumferential direction, because the emerging cooling air partial flows are not directly captured by the main flow and get 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 guide vane tips and to use the rotor shaft. For this purpose, the cooling blades are radial Direction slidably and are against the action of return springs shifted from their starting position by the pressure of the cooling air. This makes it possible to improve the compressor efficiency and in particular the Pumping limit raised significantly. This effect is with modern high pressure compressor stages clearly pronounced, because here for security reasons because of the slow response large gap widths must be provided to reliably prevent the blade tips from entering the rotor shaft.

The return springs are a safety measure in the event that the Cooling air supply should be interrupted. The cooling blades sweep immediately back to their starting position and in this way enlarge the gap between the blade tips and the rotor, so that this also in the case of a then thermal radial expansion not in contact with the Blade tips can come.

According to a constructively particularly simple implementation of this concept the blade root of the cooling blades is provided with a piston-shaped section, the in a correspondingly shaped cylindrical housing section is sealed to form a work space. The workspace is there in connection with the cooling air supply, so that when exposed to Cooling air is pushed out like a pneumatic cylinder, the cooling blades can.

The air ducts of the cooling air blades are preferably communicating Connection to the respective work area, which makes the airflow special simply designed. The airflow fed by the cooling air supply first gets into the work area and causes the radial displacement the shovel. The cooling air flow now enters directly from the work area the air guide channels and leaves the blade in the area of the blade tip through the blow-out openings. The coordination of the geometry of the air duct Channel sections and the pressure conditions in the compressed air supply is such that the air jets emerging from the exhaust openings have a high speed own and at high speed on the opposite Impact arranged rotor shaft. The impact cooling achieved in this way is guaranteed 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 slidably supported. This simplifies further the constructive structure of the bearing without the cooling effect disadvantageous to influence.

The air duct channels are preferred as bores, in particular as radial Through holes carried out, which minimizes the manufacturing effort can hold.

The cooling blades preferably each have several, in particular parallel to one another running air duct on, so that each of the cooling blades can form several partial cooling air jets. This allows cooling one Axial section of the rotor shaft corresponding to the axial width of the respective Diffuser.

A similar effect can also be achieved if there are several radial ends Blow-out openings are provided on a common air duct access. Such a solution is used, for example Cooling blades applied, which are slidable by means of a piston-shaped section are equipped on the blade root and therefore none for space reasons Allow multiple arrangement of through holes.

Brief description of the drawing

Exemplary embodiments of the invention are shown in the drawing.

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 variant, partial longitudinal section;

Fig. 4

second embodiment, partial view in axial section;

Fig. 5

third variant, partial view in axial section;

Fig. 6

fourth variant in partial longitudinal section with adjustable gap width;

Fig. 7

View from the left acc. Fig. 6;

Fig. 8

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

Only the elements essential for understanding the invention are shown some of which only use abstract symbols to clarify the function were.

Way of carrying out the invention

The concept of rotor cooling on which the invention is based is particularly evident 1 and 2. It is a typical compressor stage of a high pressure compressor with an impeller and a stator, symbolized by a blade 11 and vane 12 shown. The blades 11 are in themselves known manner attached to a rotor shaft 18 which rotates in the direction of rotation D. is drivable.

The blades 11 are followed by the guide blades 12, which are known Way attached to a housing section 17 - and thus fixed are.

The guide blades 12 are designed as cooling blades. You point to this Purpose air guide channels 13 which are continuous in the radial direction within the cooling blade 12 and extend in the area of the blade tip 15 as Blow-out openings 14 open out. The blow-out openings 14 are on the rotor shaft 18 aligned.

The air duct 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 strike the immediately adjacent rotor shaft 18. The cooling effect achieved in this way is enormous, since the heat transfer coefficient - and thus the transferable cooling energy - is very high.

As can be seen, for example, from FIG. 2, the cooling air channels 13 do not have to necessarily have a circular cross section. For example the cross-sectional shape optimally matches the profile cross-sectional shape of the guide vane 12 be adjusted so that a high and optimally distributed air flow can be realized 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. So reduced the thermal stress on the guide vane 12 with the thus associated advantages of an extended service life or the possibility of allow a higher process temperature already at the time of design.

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

A rotor shaft 38 has a circumferential groove in the axial section to be cooled 39, into which a cooling blade 32 protrudes radially with its blade tip 35. Blow-out openings 34 are again provided, through which cooling air jets K emerge.

This configuration may have a. the advantage that the emerging cooling air K is not immediate is caught by the main flow H and carried away. This is the local cooling effect is more pronounced than, for example, that described above Configuration.

The embodiment shown in FIG. 4 has cooling blades 42 which are connected to a Shroud 46 are connected to one another in the area of the blade tips 45. Blow-out openings 44 are again arranged in the area of the blade tips 45, emerge through the cooling air jets K. These hit directly opposite on a rotor shaft 48 and cool it locally. Between the Shroud 46 and the rotor 48 is a continuous annular gap in the circumferential direction 49 available, so that a certain retention effect for the emerging cooling air jets K is given.

5, there are cooling blades 52, which Have blade tips 55 that extend radially in the direction of a rotor shaft 58 expand funnel-shaped. In turn, in the area of the blade tips 55 Blow-out openings 54 are provided, through which cooling air jets K are expelled become. The funnel shape of the blade tips 55 enables the application of the rotor shaft 58 along a larger circumferential section than is the case with radial straight-ended blades would be possible.

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

In the embodiment variants according to FIGS. 6 to 8, a further increase in the Pumping limit and a further increase in compressor efficiency possible that the radial gap of the stator is adjusted during operation, d. H. can be reduced.

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

The blade root 67 is provided with sealing rings 73, so that in this way the working space 77 is sealed off from the cylindrical housing section 78 is. As soon as cooling air is applied to the working space 77, there is a shift the cooling blade 62 towards the rotor shaft 68. Cooling air also occurs from the work space 77 into air guide channels 63 and leaves them through Blow-out openings 64. The sliding movement of the cooling blade 62 takes place against the action of return springs 74 which between the blade root 67 and the housing section 78 act in the region of the working space 77. The return springs 74 have the effect on the one hand that they the cooling blade 62 when switched off Withdraw cooling air supply and in this way a gap 70 between the blade tips 65 and the rotor shaft 68 is set to be as wide is dimensioned such that the blade tip 65 runs securely into the rotor shaft 68 is prevented. On the other hand, when the cooling air supply is switched on, the Gap 70 is reduced to such an extent that a cooling air stream K discharges Air cushion is formed in the gap 70, which not only cools the rotor shaft 68, but also a reliable flow around the cooling blade 62 in the area of the gap 70 prevented. The compressor efficiency and the surge limit can be thereby increase optimally.

The width of the gap 70 can be appropriately controlled for the cooling air supply can be designed to be variably adjustable. A particularly simple constructive Solution can also be achieved by not having a closer look here Shown stop is provided, the displacement of the cooling blade 62 limits and thus specifies the minimum width of the gap 70.

The variant shown in FIGS. 6 and 7 is further characterized by that each of the cooling blades 62 of a guide vane ring is individually displaceable is stored. This configuration includes an additional security aspect in the event that there is a local fault with a single cooling blade 62 - for example if the air duct 63 is blocked - the person concerned Cooling blade 62 returns to its original position. One in a row due to the lack of internal cooling of the cooling blade 62 caused thermal expansion in radial Direction does not lead to the blade tip 65 entering the rotor shaft 68.

The variant shown in FIG. 8 shows a tandem arrangement of two cooling blades 82 on a common blade carrier 87. In the area of blade tips 85, a shroud 86 is provided. In turn, cooling air jets K ejected from the cooling blades 82 via blow-out openings 84 and impact on a rotor shaft 88.

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

Reference list

11

Blade

12th

Cooling vane, guide vane

13

Air duct

14

Blow-out opening

15

Blade tip

17th

Housing section

18th

Rotor shaft

32

Cooling blade

34

Blow-out opening

35

Blade tip

38

Rotor shaft

39

Groove

42

Cooling blade

44

Blow-out opening

45

Blade tip

46

Shroud

48

Rotor shaft

49

Annular gap

52

Cooling blade

54

Blow-out opening

55

Blade tip

58

Rotor shaft

62

Cooling blade

63

Air duct

64

Blow-out opening

65

Blade tip

67

Blade root

68

Rotor shaft

70

gap

73

Sealing ring

74

Return spring

76

Supply channel

77

working space

78

Housing section

82

Cooling blade

84

Blow-out opening

85

Blade tip

86

Shroud

87

Shovel 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)

Turbomachine, in particular compressor with a gas turbine Blades and guide vanes that lead to at least one impeller and a stator are arranged, and with at least one rotor shaft, which is cooled by means of a cooling device, characterized in that that individual or all guide vanes (12, 32, 42, 52, 62, 82) as Cooling blades supplied from a cooling air supply are designed in this way are that they are penetrated by air duct (13, 63) and Blow-out openings in the area of the blade tips (15, 35, 45, 55, 65, 85) (14, 34, 44, 54, 64, 84), which on the rotor shaft (18, 38, 48, 68, 88) are aligned. Fluid machine according to claim 1, characterized in that individual or all guide vanes of a guide wheel as cooling blades (12, 32, 42, 52, 62, 82) are formed. Fluid machine according to claim 2, characterized in that the stator has a shroud (46, 86). Fluid machine according to claim 2, characterized in that the cooling blades (12, 32, 42, 52, 62, 82) by the pressure of the cooling air (K) from a starting position against the action of return springs (74, 94) are slidably mounted. Turbomachine according to claim 4, characterized in that the blade root (67) of the cooling blades (62) has a piston-shaped section has, which in a corresponding cylindrical housing portion (78) sealed to form a work space (77) is guided, with the working space (77) in communicating fluid connection with the cooling air supply. Fluid machine according to claim 5, characterized in that the air duct (63) in communicating fluid communication with the respective work area (77). Fluid machine according to one of claims 4 to 6, characterized in that that two adjacent cooling blades (82) with each other are firmly connected and positively coupled can be moved. Fluid machine according to one of the preceding claims, characterized characterized in that the air duct (13, 63) as bores, or are designed as through holes. Fluid machine according to one of the preceding claims, characterized characterized in that the cooling blades (12, 32, 52, 62, 82) each several, or parallel to each other air duct (13). Fluid machine according to one of the preceding claims, characterized characterized in that the cooling blades (12, 32, 42, 52, 62, 82) several each, or at the tip of the blade (15, 35, 45, 55, 65, 85) have outlet openings (14, 34, 44, 54, 64, 84).

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