EP2173972B1 - Rotor for an axial flow turbomachine - Google Patents

Description

The invention relates to a rotor for an axially flow-through turbomachine, with a plurality of stacked rotor disks, which are clamped together axially by means of at least one tie rod and each having an outer diameter.

Generic rotors have long been known from the general state of the art. The rotor disks used in the rotor are known to carry on their outer sides in a ring arranged blades, by means of which a working medium compressible or by means of which the energy contained in a working medium can be converted into the rotational movement of the rotor. The adjacent stacked rotor discs are braced together by at least one tie rod. For this purpose, the tie rod extends through the rotor discs and is biased by nuts screwed end. The tie rod ensures the firm juxtaposition of the rotor discs.

Furthermore, from the DE 199 14 227 B4 It is known that a welded-together rotor can have an outer drum-shaped heat-insulating jacket for protecting the inner region of the rotor.

Besides that is from the patent DE 898 100 a cooled gas turbine engine known. Its outer periphery is formed by annular blade carriers, which are provided to the axis to opposite recesses. In each of these recesses engages in each case a projecting edge of a rotor disk, so that the respective blade carrier is positively clamped between two rotor disks.

In addition, a composite of several parts drum rotor for gas turbines from the patent CH 238 207 known. The drum runner includes one out a plurality of rings axially assembled drum, which are welded together at the outer drum circumference at the joints. In this case, the edge of a rotor disk is frictionally bordered in the region of the joints between two adjacent rings.

From the patent DE 972 310 is a modular rotor for a turbomachine disk-type known. The blades carried by the rotor are fastened in detail to rings. The rings are held on their front sides by positive locking of rotor disks arranged on both sides.

In general efforts to increase the efficiency and performance of gas turbines used to generate energy, relatively large compressor mass flows are required with high compressor pressure ratios. Larger compressor mass flows occur, for example, in compressors of gas turbines whose rated power is greater than 50 MW. The compressor pressure ratio is greater than 1:16. Due to the comparatively high pressure ratio, the temperature of the compressed air rises to several hundred degrees Celsius. The high air temperature heats the adjacent elements of the compressor, especially in the area of the rear compressor stages, so that nowadays due to the increased pressure conditions, the materials used so far can no longer sufficiently withstand the temperatures which now occur. When using more temperature-resistant materials for rotor disks, however, due to the size of compressors with large mass flows further disadvantages in the strength and workability, so that they are only partially suitable and only limited use. In addition, the more temperature-resistant materials are also more expensive.

The object of the invention is therefore to provide a rotor for an axially flow-through turbomachine, preferably for a high-pressure compressor with a pressure ratio of greater than 1:16 and a comparatively large compressor mass flow, in which, while maintaining the concept with stacked contiguous rotor discs a cost-effective design can be specified. At the same time, the rotor should have a particularly long life. Furthermore, the efficiency of the compressor should be further improved.

The above objects are achieved by a rotor of the type mentioned, in which at least two of the rotor discs of the rotor have a smaller outer diameter than one of the adjacent rotor discs and the existing difference in diameter is compensated by a rotor disc with a smaller outer diameter annularly encompassing drum, which Drum the respective rotor discs engages with small diameter in its entire axial extent and having an endless surface on its inner surface web which is axially braced between the encompassed rotor discs with a smaller diameter.

According to the invention, a multi-part rotor, as seen in its radial direction, is thus proposed, in which the inner rotor disks can be made of a different material than the drum provided on the outside. The most suitable materials can thus be selected for the different loads of drum and rotor disks. Thus, both the drum and the encompassed rotor disks with a smaller diameter can each be made of a material with which a particularly long service life of the component can be achieved. At the same time, a device is specified, by means of which the drum can be connected in a rotationally fixed manner to the rotor disks of smaller diameter. A slip-laden relative movement between the outside arranged drum and radially further inwardly arranged rotor disks is thus not possible, whereby a total of the torque to be transmitted between the components involved and forces can be passed lossless. In addition, the drum allows the sealing of gaps between the two rotor disks, so that at this point in the prior art possibly existing leakage flow can be suppressed here. This increases the efficiency of the compressor.

In addition, due to their reduced diameter, the rotor disks can also be better examined for possibly existing material inclusions, imperfections and / or cracks by means of the known ultrasonic methods than the rotor disks with a larger diameter known from the prior art.

Advantageous embodiments are specified in the subclaims.

According to a first advantageous embodiment, the rotor disk is arranged with the larger outer diameter immediately adjacent to the rotor disk with the smaller outer diameter. As such, the blades are hooked directly to the larger diameter rotor disk, whereas in the axial portion of the rotor, where the smaller diameter rotor disk is disposed, the blades are directly hooked to the drum. As it were, the rotor comprises a first section with a disk rotor and a second section with a drum rotor with internal rotor disks.

According to a further advantageous development, the web of the drum extends radially further inward than the rotor disk with a smaller outer diameter and has an axial width such that the web extends at least partially into a hub opening of the rotor disk with a smaller diameter. This embodiment leads to a mechanically as well as thermally particularly resilient drum.

Preferably, the two - seen in the axial direction of the rotor - the outer of the rotor disks encompassed by the drum are hooked to it for receiving centrifugal forces. The drum thus encompasses at least two rotor disks, wherein each of the two outer rotor disks, viewed in the axial direction, each provide an entanglement at their outer peripheries which can be brought into engagement with a corresponding hook or groove provided on the inside of the drum. The direction of the entanglement is chosen so that the forces acting on the drum centrifugal loads from the rotor disks at least partially can be included. As a result, the centrifugal force occurring in this section of the rotor can be evenly distributed from the drum to the rotor discs arranged radially further inside. Due to the required mountability of the stackable construction with radially inwardly arranged rotor disks and radially outwardly arranged drum, it is necessary that at least the two outer rotor disks are hooked to the drum. In an arrangement in which the drum engages around only two rotor disks, thus both rotor disks are hooked to the drum.

According to a particularly advantageous embodiment of the invention, the drum is formed of a heat-resistant material than the rotor disks. In particular, this is a particularly inexpensive rotor can be specified because the heat-resistant and cost-intensive material is only to use for the drum. The construction according to the invention is preferably used in the rear stages of an axial compressor, in which particularly high temperatures in the range of greater than 400 ° C occur during the compression process. With a more heat resistant drum, the life of the rotor can at least be maintained, if not extended even further. Since a lower temperature prevails in the interior of the rotor due to the temperature gradients in the drum material than in the air to be compressed, it may be sufficient that the rotor disks are made of a material which meets lower requirements in terms of temperature resistance. Accordingly, the material of the rotor discs can be a cheaper than the material of the drum. For example, the drum may be made of a nickel-based alloy and the rotor disks encompassed by it may be made of a heat-resistant steel or alloy.

In order to specify a particularly firm and reliable connection between the drum and the rotor disks, the web has two opposite flange-like end faces on, abut the flange-like end faces of adjacent rotor discs. Preferably, the end face of the rotor discs is positively against the end face of the web. For example, the positive connection can be produced by means of a Hirth toothing. According to a further embodiment it can be provided that the drum has at least one groove for receiving at least one blade. Preferably, the groove is formed as a circumferential groove, so that in the circumferential groove all blades of a blade ring can be used. The use of circumferential grooves allows a particularly large number of blades per ring. In addition, the circumferential grooves are cheaper to manufacture than axially extending slots for blades.

In a particularly preferred variant of the invention, the number of circumferential grooves can be greater than the number of rotor disks encompassed by the drum. So far, it was in the prior art so that each rotor blade stage a rotor disk was provided with a circumferential groove. This caused a comparatively large axial space for mounting the blades on the rotor. Despite the use of the modular rotor concept with rotor disks, the solution proposed can achieve a comparatively short axial installation space for the rotor and for the housing since, for example when using two rotor disks, it is possible to provide three peripheral grooves on the outer circumference of the drum. can be used in the respective blades of different blade rings. Thus, axial space can be saved, which reduces in particular the housing material costs. In addition, the mass of the rotor can be reduced. Overall, therefore, the outside of the drum for receiving arranged in wreath blades is formed, wherein the number of mountable blade rings can be greater than the number of rotor discs encompassed by the drum.

The invention is particularly useful when the rotor is used in a compressor with a pressure ratio greater than 1:16, the compressor preferably being the compressor of a stationary gas turbine used for power generation. Preferably, the rated power of the gas turbine is greater than 50 MW. The invention can be used in principle in each section of a compressor. Since the problems mentioned in the prior art occur especially with large rotor disks with an outer diameter of 1200 mm and larger, it is particularly advantageous if in particular such large rotor disks are replaced by the construction according to the invention with compressor disks smaller outer diameter and with a surrounding drum , Thus, the drum according to the invention preferably has an outer diameter of 1200 mm and larger. Of course, the invention can also be used in the sections of the compressor, where - if only compressor discs without a drum would be used - this would have a smaller outer diameter than 1200 mm. Thus, drum outer diameter smaller than 1200 mm are possible.

FIG 1

einen Ausschnitt durch den Längsschnitt durch einen erfindungsgemäßen Rotor,

FIG 2

den gleichen Ausschnitt wie FIG 1 mit einer modifizierten Trommel und.

FIG 3

eine Trommel gemäß einer weiteren Ausgestaltung mit einem radial nach innen ragenden Nabenbereich.

The invention will be explained in more detail with reference to a drawing. Other features and other advantages will be apparent from the description of the figures. It shows:

FIG. 1

a detail through the longitudinal section through a rotor according to the invention,

FIG. 2

the same section as FIG. 1 with a modified drum and.

FIG. 3

a drum according to another embodiment with a radially inwardly projecting hub region.

The FIG. 1 shows a section through the longitudinal section of a plurality of rotor disks 10 comprehensive rotor 12 of a gas turbine, not shown. The section of the rotor 12 is chosen so that this in the high pressure region of the Axial compressor of the gas turbine is located. The pumping direction of the axial compressor is from the left side of the drawing to the right side of the drawing.

The rotor discs 14, 16 are manufactured in a known configuration and have at their outer peripheries 18 each have a circumferential groove extending in the circumferential direction 20, which are provided for receiving blades of the compressor. The rotor disks 14, 16 are flange-like against each other at a contact surface 22, wherein in this contact surface 22 a serration is provided for the positive connection.

Immediately downstream of the rotor disk 16, ie in FIG. 2 further shown on the right, two further rotor discs 24, 26 are provided, which compared to the upstream rotor discs 14, 16 have a substantially smaller outer diameter. The terms "downstream" and "upstream" refer to the direction of the compressed air flowing in the axial compressor.

The two rotor discs 24, 26 are encompassed by a longitudinally sectionally T-shaped, circular in cross-section drum 28. The drum 28 has on its inner side 30 a radially inwardly directed endless circumferential ridge 32, which is provided with two opposite end surfaces 34. The end faces 34 rest on the one hand on the rotor disk 24 and on the other hand on the rotor disk 26 on contact surfaces 36, 38 at. The contact surfaces 36, 38 are structured such that in each case a positive connection in the form of a serration is provided.

Each of the rotor disks 24, 26 has in its outer region an axially extending circumferential hooks 40, 42. The annular hooks 40, 42 each engage in an open towards the end face of the drum 28, arranged in this endless circumferential groove 44, 46 a. The grooves 44, 46 thus each form a receptacle for the hooks 40, 42 arranged on the rotor disks 24, 26.

The drum 28 has on its outer side also in the circumferential direction extending blade holding grooves 48, 50, 52, in each of which blades of a blade ring can be used. The blades have for this purpose to the blade holding grooves 48, 50, 52 corresponding formed blade roots. The blades which can be inserted in the grooves 48, 50, 52 belong to the blade stages which carry out the last pressure increases in the medium to be compressed. Accordingly, the blade holding grooves 48, 50, 52 are arranged the last three compressor blade rings of the compressor. Due to the high temperatures occurring in the area of the drum 28 during the compression of the medium (air), it is made of a heat-resistant material than the rotor disks 24, 26 encompassed by the drum 28 and thus located radially further inward. The rotor disks 24, 26 can thus are made of a less temperature-resistant material, since in their region lower temperatures than in the region of the drum 28. In addition, the axial distance between the grooves 48 and 50 and between the grooves 50 and 52 in comparison is less than the distance in the use of three individual rotor discs instead of the drum 28, so that axial space can be saved in the compressor. The saving of axial space overall allows the construction of a cheaper gas turbine or the construction of a cheaper compressor.

Although the drum 28 is integrally formed and accordingly centered by the rotor disks 24, 26 provided therein, it has been found to be advantageous that each of the rotor disks 24, 26 is hooked to the inner side 30 of the drum 28. Even a slight placement of the two axially opposite ends 54, 56 of the drum 28 can thus be avoided. At the same time, the mechanical centrifugal force loads originating from the blades can be transferred from the drum 28 to the rotor disks 24, Be at least partially forwarded so that the mechanical stresses on the edge of the drum 28 remain within the allowable limits of the drum material.

Instead of a centrally extending through hub openings 57 of the rotor disks 10 tie rod 58 may of course also be provided a number of several, decentralized around the machine axis 60 concentrically arranged tie rods to press the rotor disks firmly together.

FIG. 2 shows the same section of the gas turbine as FIG. 1 , wherein like components are labeled with identical reference numerals.

In contrast to FIG. 1 has the in FIG. 2 illustrated drum 28 on a modified web 32. The web 32 according to the in FIG. 2 illustrated second embodiment of the drum 28 extends inwardly not only to those end faces 34 which abut against the contact surfaces 22 of the adjacent rotor disks 24, 26, but beyond this range. Thus, the web 32 may also comprise a further hub region 62, the radial end of which lies substantially further inward than the contact surfaces 22 of the rotor disks 24, 26. In this way, a greater load capacity of the drum 28 can be achieved.

In FIG. 3 a further alternative embodiment of the invention is shown, wherein identical features are provided with identical reference numerals. Identical features also have the same function, so that the previous description for in FIG. 3 identical design features apply here as well. Subsequently, only the structural differences become FIG. 2 explained in more detail.

Compared to FIG. 2 has the drum 28 according to FIG. 3 a still further radially inwardly projecting hub portion 63. This hub portion 63 is also still in its axial Extent so wide that it lies radially within the hub areas 64 of the rotor disks 24, 26. In other words, the boss portion 63 of the land 32 has an axial extent such that it extends partially into the hub opening 57 of the rotor disks 24, 26 of smaller diameter. By means of such a hub region 63, the mechanical stresses in the drum can be kept comparatively small 24, as a result of which it can withstand the thermal loads in an improved manner.

Overall, the invention thus relates to a rotor 12 for an axially flow-through turbomachine with a plurality of stacked rotor disks 10, 14, 16, 24, 26, which are braced by means of at least one tie rod 58 and each having an outer diameter. To provide a particularly inexpensive rotor 12 in a compact design, which is designed in particular for particularly high pressure conditions at comparatively large compressor mass flows, it is proposed that at least two rotor disks 24, 26 of the rotor 12 have a smaller outer diameter than one of the adjacent rotor disks 16 and the existing difference in diameter is compensated by a rotor disks 24, 26 with a smaller outer diameter annularly encompassing drum 28. The drum 28 surrounds the rotor disks 24, 26 with a smaller diameter in its entire axial extent and has a continuous on its inner surface 30 to running step 32 which is axially braced between the gripped rotor disks 24, 26 with a smaller diameter. In this case, only the drum 28 may be made of a more heat-resistant material. The encompassed by her rotor discs 24, 26, however, can be made of a cheaper material, resulting in cost savings. Furthermore, the drum 28 can carry at least one blade ring more than rotor disks 24, 26, which are encompassed by it.

Claims (15)

1. Rotor (12) for a turbomachine which is exposable to axial throughflow, with a plurality of rotor disks (10, 14, 16, 24, 26) which are arranged in a stacked manner, are clamped to each other by means of at least one tie rod (58), and have an outside diameter in each case, characterized in that at least two rotor disks (24, 26) of the rotor (12) have a smaller outside diameter than one of the adjacent rotor disks (16) and the existing diameter difference is compensated by means of a drum (28) which annularly encompasses the rotor disk (24, 26) with smaller outside diameter, which drum (28) encompasses the rotor disks (24, 26) with smaller diameter over its entire axial extent and on its inner surface (30) has an endlessly encompassing web (32) which is axially clamped between the encompassed rotor disks (24, 26) with smaller diameter.
2. Rotor (12) according to Claim 1, in which the rotor disk (14, 16) with the larger outside diameter is arranged directly next to the rotor disk (24, 26) with the smaller outside diameter.
3. Rotor (12) according to one of Claims 1 or 2, in which the web of the drum (28) extends radially further inwards than the rotor disk (24, 26) with smaller outside diameter and in this case has such an axial width that the web (32) at least partially extends into a hub opening (57) of the rotor disk (24, 26) with smaller outside diameter.
4. Rotor according to one of Claims 1 to 3, in which the two outer of the rotor disks (24, 26), as seen in the axial direction of the rotor (12), which are encompassed by the drum (28) are hooked into the drum for absorbing centrifugal force loads.
5. Rotor (12) according to Claim 4, in which the two rotor disks (24, 26), on their circumferential side, have an annular hook (40, 42) which extends in the axial direction and engages in each case in a slot (44, 46) which is provided on the drum (28).
6. Rotor (12) according to one of the preceding claims, in which the drum (28) is formed from a more heat-resistant material than the rotor disk (24, 26) with smaller diameter.
7. Rotor (12) according to one of the preceding claims, in which the web (32) has two oppositely disposed, flange-like end faces (34) which abut against flange-like end faces (36, 38) of the adjacent rotor disks (24, 26).
8. Rotor (12) according to Claim 7, in which the end faces (36, 38) of the rotor disks (24, 26) and the end faces (34) of the web (32) abut against each other in a form-fitting manner.
9. Rotor (12) according to Claim 8, in which the form fit is formed by means of a Hirth toothing.
10. Rotor (12) according to one of Claims 1 to 9, in which the drum (28) has at least one slot (48, 50, 52) for accommodating at least one rotor blade.
11. Rotor (12) according to Claim 10, in which the slot (48, 50, 52) is formed as a circumferential slot.
12. Rotor (12) according to Claim 11, in which provision is made for a number of circumferential slots (48, 50, 52) which is greater than the number of rotor disks (24, 26) which are encompassed by the drum (28).
13. Rotor (12) according to Claim 12, in which the outer side of the drum (28) is formed for accommodating rotor blades which are arranged in rings, wherein the number of blade rings which can be installed is greater than the number of rotor disks (24, 26) which are encompassed by the drum (28).
14. Compressor with a rotor (12) according to one of the preceding claims.
15. Gas turbine with a compressor according to Claim 14.

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