EP2356319A1 - Guide blade arrangement for an axial turbo-machine - Google Patents

Abstract

The invention relates to a guide blade arrangement (12) for an axial turbo-machine, which guide blade arrangement (12) comprises at least one annular guide blade carrier (14) and an inner ring (22) arranged concentrically with respect to the guide blade carrier (14), between which guide blade carrier (14) and inner ring (22) a number of guide blades (20) are arranged in a radiating pattern. To obtain a low-wear and particularly durable fastening of the guide blade (20), which is supported by the guide blade carrier (14), to the inner ring (22), it is proposed that the guide blades (20) are fastened resiliently to the inner ring (22). Here, the fastening is provided by means of a spring element (52). By means of the spring element (52), it is possible to ensure a uniform contact pressure of the guide blade head (30) against the inner ring (22) or if appropriate against a further spring element (52), such that occurring stresses and wear can be reduced.

Description

description

Guide vane assembly for an axial turbomachine

The invention relates to a stator vane assembly for an axial turbomachine comprising an annular vane carrier and an inner ring disposed concentrically with the vane carrier, between which a plurality of vanes with a blade airfoil are arranged, each vane being attached to the vane carrier.

An initially mentioned vane arrangement is sufficiently known from the prior art. For example, this is known in compressors of stationary gas turbines, in which guide vanes of the compressor to a

Guide vane or attached to a compressor housing. For this purpose, known guide blade carrier, which are designed in particular in particular tubular, at its inner circumferential surfaces extending in the circumferential direction

Retaining with undercuts in which guide vanes or outer rings are inserted and secured. On the one hand, the guide vanes may be formed as free-standing vanes, so that their airfoil tips lie opposite one another with the gap forming an inner boundary wall of the flow path of the compressor. Also, for example, it is known from US 20007/0177973 A1 that the inner boundary wall of the flow path is part of the vanes or can be held by the vanes themselves. In this case, the known guide vanes either have cover bands arranged on the top side, which then form parts of the boundary wall, or the guide vanes carry an inner ring on the top side, the outer surface of which then represents the inner boundary for the flow path. The attachment of the inner ring to the guide vanes of the vane assembly can thereby via a suitable Screwing, done by welding or by caulking.

In the known types of mounting of the inner ring on the vanes of the vane assembly, it may come during operation of the compressor to wear or crack initiation at the connection of inner ring and vane. The signs of wear occur due to the rotation of the inner ring by the aerodynamic load on the blade and / or due to thermally induced strains, which occurs due to the heat generated in the compression in the compressor. Periodic changes in the load on the blades or vibrations can also lead to signs of wear.

Furthermore, from the documents GB 2 400 415 A and US 2,914,300 a radially internally sprung mounting of the blades is known.

The object of the invention is therefore to provide an aforementioned vane arrangement for an axial turbomachine, which allows a particularly simple, strain-tolerant, low-wear and reliable attachment of vanes to an inner ring.

The object underlying the invention is achieved by a vane arrangement according to the features of claim 1.

According to the invention, in the guide vane arrangement mentioned at the beginning, the vane comprises a vane head projecting into a peripheral groove of the inner ring with a web and a head part extending transversely thereto, and the groove is closed by a cover in the section between two adjacent vanes adjacent covers to form the web receiving recesses spaced from each other and that the Leitschaufelkopf at least one of the vanes by means of at least one in one of the respective web facing side surface of the recess arranged spring element is resiliently mounted on the inner ring.

The invention is based on the finding that a rigid connection of guide vanes on the inner ring is disadvantageous. Accordingly, it proposes a type of connection which permits relative movements of guide vanes to inner ring without wear to a small extent, without damaging the connection. Consequently, the invention turns away from the previous approaches, in which a rigid, firm connection between vanes and inner ring was provided.

In the course of the invention, a simple spring element is now to be used for fixing the guide vane on the inner ring. By using a resilient mounting of vanes on the inner ring a uniform contact pressure of the relevant vane on the inner ring can be done, which effectively minimizes occurring stresses caused by thermal expansion and / or static and / or dynamic stresses. At the same time can be easily compensated by the resilient attachment required for easy installation mounting games.

By reducing wear and avoiding cracks, overall system uptime can be increased since previously required controls and rework of worn components are eliminated using the invention. Furthermore, repair costs can be saved and may be waived on intermediate inspections. In addition, the described measure can easily be combined with some of the solutions known from the prior art, which represents an improved repair possibility of existing turbomachines.

Each relevant vane comprises on the inner ring side a countersunk in the inner ring, ie in a designated groove projecting vane head, by means of which the vane is resiliently mounted on the inner ring. Thus, the relevant vane on the inner ring is resiliently fastened, it comprises at least one structural element, namely the vane head, which is connectable to the inner ring and adapted to carry this.

According to a simple embodiment, the guide vane head of each relevant vane comprises a web which is arranged in each case in an outwardly open, arranged on the inner ring recess and in which in at least one of the respective web facing side surface of the recess, a spring element is arranged, which on the inner ring and biased against the web of the relevant vane. Thus, for the resilient attachment of the guide vane on the inner ring another construction component, the spring element, provided, which is supported on the one hand on the inner ring and on the other hand at the web of the relevant vane. In this case, the vane arrangement is designed so that the spring element is preferably biased and thus the web of the relevant vane either indirectly or directly to the inner ring, in detail to one of the two side surfaces of the recess pressed.

The vane head is hammer-shaped by means of the web and a head portion extending transversely thereto, wherein the web connects the head portion with an aerodynamically curved airfoil of the respective vane and wherein the inner ring has a circumferential groove corresponding to the vane head for receiving the vane heads, which groove respectively in the section between two adjacent vanes of a cover, so the blade towards, is closed. By the positive connection of the guide vane with the inner ring by means of arranged on the vane hammer-shaped vane head or Leitschaufelhakens and provided on the inner ring groove, which correspond to the shape is formed of the vane head, a guide vane arrangement can be specified, in which the inner ring is supported by the guide vanes particularly reliable. This embodiment is particularly advantageous when the vane assembly itself, the inner ring and / or the annular vane support is not formed integrally, but are formed by at least two arcuate ring segments, which in each case separate from the other ring segments during assembly and / or disassembly be handled. The cover prevents on the one hand a displacement of the inner ring relative to the guide vanes along the circumference, since the cover is arranged in each case between two guide vanes and thus blocks the displacement path along the groove. On the other hand, the cover also provides for a stepless boundary surface of the flow channel. Overall, the components of the arrangement and the arrangement itself can then easily manufacture.

Advantageous embodiments are specified in the subclaims.

According to an advantageous embodiment, two spring elements are provided for each respective vane, which are arranged on opposite side surfaces of the recess. As a result, each such mounted vane is indirectly, so arranged biased on the inner ring via the spring elements. Conveniently, the spring force of each spring element is directed in the circumferential direction of the inner ring. If a clamping sleeve is used as the spring element, only a line contact is present between the web of each respective vane and the clamping sleeve, whereby the static load on the vane at the connection point is less than in a flat fixed guide vane. Since the static load is mainly due to an occurring displacement of the inner ring in the circumferential direction caused by an aerodynamic blade load, a displacement-tolerant attachment is in shape a resilient circumferential storage in order to prevent wear and cracking and crack growth.

For a simple manufacture of the vane arrangement, it may be advantageous if the inner ring comprises two partial rings, which can be mounted after their assembly into a one-piece inner ring.

If the vane arrangement is used in particular in stationary turbomachines, it is advantageous if the vane arrangement itself comprises two or more ring segments, that is, that the inner ring and / or the annular vane carrier are formed as arcuate ring segments. Since the vane assembly and its components to the non-rotatable components of a

Turbomachine, which, if used in the stationary area, have a dividing plane, whereby the rotationally fixed components are divided for an upper and a lower half, is suitable in two, each 180 ° large ring segments divided guide vane assembly, especially for stationary turbomachinery. Then, a simple assembly of the individual components to an overall annular vane arrangement is possible. Preferably, the guide vane assembly is used in a turbomachine, which may be designed in particular as an axial compressor or axial turbine. In addition, the guide blade carrier can be arranged within a separate housing or even be designed as a housing itself.

The invention will be explained with reference to a drawing. Further advantages and further features emerge from the description of the figures.

Show it:

1 shows a segment 10 of a guide vane assembly 12 of an axial turbomachine in a perspective view; 2 shows an exploded view of FIG. 1;

3 shows a longitudinal section through a connection according to the invention of vane and inner ring;

4 shows a section of the inner ring without a vane;

5 shows a side view according to the section V-V and

6, 7 show schematically the torsion of the vane by load and bearing reaction for a fixed according to the prior art vane and for a fixed according to the invention vane.

1 shows a segment 10 of a vane assembly 12 of an axial turbomachine in a perspective view. The segment 10 is arcuate and spans an arc of 180 °. Two of the segments 10 shown in FIG

Guiding assembly 12 are assembled, which is then annular. On an inner surface 16 of the vane support 14 extending in the axial direction of grooves 18 for receiving vanes 20 are provided. In FIG. 2, the guide vanes 20 to be inserted into the grooves 18 are shown offset from the guide blade carrier 14 due to the explosive manner of representation. The radially outer part of the guide blade 20 is referred to as a guide blade root and the radially inner part of the guide blade 20 as a Leitschaufelkopf. Between the vane root and the vane head, the vane 20 has an aerodynamically curved airfoil. On the head side, an inner ring 22 is arranged on the guide vanes 20, of which only a 180 ° segment is shown in FIG. Of the

Inner ring 22 or its segments are made up of two partial rings 36, 38 or partial ring segments together. The vane assembly 12 composed of two segments 10 thus includes a ring of vanes 20 which is also known as a vane ring and may be part of a compressor stage or turbine stage.

The vane support 14 is attached to a non-illustrated housing of the axial turbomachine, such as a compressor, or even formed as a housing. The vane support 14 carries the guide vanes 20 which are fastened to it on the inside and in turn carry the inner ring 22 on the inside of the head. The outer circumferential surface of the inner ring 22 and the inner surface 16 of the vane support 14 form the radial inner and outer boundary for a medium flowing through the axial turbomachine. If the axial turbomachine is designed as a compressor, the medium is compressed or compressed air.

3 shows a longitudinal section (in the sense of the axial turbomachine) by means of a connection according to the invention of the guide blade 20 with the inner ring 22. The blade blade 28 belonging to the guide blade 20 is only partially shown. At the airfoil 28, at the head end of the vane 20, a vane head 30 is provided, which has a web 32 and a transversely extending head portion 34. By means of the web 32 and the head part 34, the guide blade head 30 viewed in cross-section on a total of a hammer shape.

The inner ring 22 is provided with an outwardly open groove 44, whose longitudinal section contour is formed corresponding to the guide vane head 30. The inner ring 22 comprises the two partial rings 36, 38, which are in turn also formed as shown in FIG 2 as a 180 ° arcuate segments. The partial rings 36, 38 or their segments are fixedly connected to one another via a welded connection 40. The partial rings 36, 38 each have mutually directed projections 42, 43, in each case for forming a Undercut, through which the hammer-shaped vane head 30 can be radially fixed.

4 shows a perspective view of a portion of the inner ring 22, in which the partial rings 36, 38 are shown for reasons of clarity not in their final construction position, but at a distance. In their final construction position, the two projections 42, 43 - as far as possible - without gaps to each other. In the projection 43 of the partial ring 36 is for each

Guide vane 20 is provided a recess 46, two of which are shown in FIG 4. The recesses 46 serve to receive the ridge 32 of the vane head 30 of the vane 20. The projection 43 thus forms between the recesses a cover 47 which closes the groove 44 between two vanes 20 to provide a non-offset flow path. Between two adjacent covers 47, a recess 46 is thus provided in each case, in which the web 32 is accommodated (FIG. 3). For reasons of clarity, the guide vane 20 shown in FIG. 3 is not shown in FIG. Each recess 46 has two opposing side surfaces 48. In at least one of the two side surfaces 48 of each recess 46, a further pocket 50 is provided, in which a designed as a clamping ring spring element 52 is provided for resilient attachment of the guide vane 20 on the inner ring 22. In FIG. 4, a spring element 52 is shown schematically only in the recess 46 shown there on the left. A side view on the in FIG 4 further right portion of the partial ring 36 is shown in FIG 5. This recess 46 is bounded by two side surfaces 48, in each of which a pocket 50 is provided. The pocket 50 is formed substantially circular segment-shaped and extends over the entire axial length of the recess 46. The bag 50 may, for example, before the introduction of the

Recess 46 may have been made by drilling or eroding. The pocket 50 is arranged so that the diameter lying in the radial plane of the axial turbomachine Bag 50 is arranged in the projection 43 and in the cover 47, so that only a comparatively small portion of the drilling circle is detected by the recess 46. The clamping sleeve then has a diameter which is only slightly smaller than the diameter of the pocket 50. Due to the selected position of the pocket 50, the clamping element formed as a spring element 52 may still protrude into the recess 46 so far that the web arranged there, which is not shown in FIG 5, resiliently fixed over the spring element 52 on the inner ring 22. Due to the selected arrangement of the recess 46, the pockets 50 and the spring elements 52, the force direction of the latter acts in the circumferential direction.

Falling out of the spring element 52 from the pocket 50 into the recess 46 can be avoided due to the position of the pocket 50. This facilitates assembly of the vane assembly 12.

Of course, the spring element 52 could also be mounted in pockets, which are arranged on the web 32, and not on the side surfaces 48 of the recess 46.

FIG. 6 and FIG. 7 show diagrammatically the twisting of the vane 20 by load and bearing reaction for a prior art vane (FIG. 6) and for a vane attached according to the invention (FIG. 7).

Since a head-side fixed according to the prior art guide vane 20 is particularly strong, could at their weakest point, especially on the vane head 32, or on the inner ring particularly high loads and wear occur, which can lead to cracking and crack growth depending on the load. With the invention, a resilient and thus designated as a floating bearing attachment of the guide vane head 30 is proposed, which leads to a much lower torsion of the vane 20 by load and bearing reaction. As a result, the load on the vane head 32 can be reduced, which is the The occurrence of cracks and wear is delayed or prevented. In particular, the displacement of the inner ring in the circumferential direction, which occurs due to aerodynamic blade loading, causes a static load on the blade, which can be better compensated by the connection according to the invention than guide vanes fastened according to the prior art.

In general, the invention relates to a vane assembly 12 for an axial turbomachine comprising at least one annular vane support 14 and an inner ring 22 concentric with the vane support 14, between which a plurality of vanes 20 are radially disposed. In order to specify a low-wear and particularly durable attachment of the guide vane 20 carried by the vane carrier 14 on the inner ring 22, it is proposed that the vane 20 are resiliently secured to the inner ring 22. The attachment takes place by means of a spring element 52. By the spring element 52 can be a uniform contact pressure of the vane head 30 to the

Inner ring 22 or possibly to a further spring element 52 are ensured, so that occurring stresses and wear can be reduced.

Claims

claims A vane assembly (12) for an axial turbomachine comprising an annular vane support (14) and an inner ring (22) concentric with the vane support (14), between which a plurality of vanes (20) having a vane blade (28) are radially disposed, wherein each vane (20) is fixed to the vane support (14), characterized in that the vane (20) comprises a vane head (30) projecting into a circumferential groove (44) of the inner ring (22) and having a web (32) extending transversely extending head portion (34) and the groove (44) each in the portion between two adjacent vanes (20) by a cover (47) is closed, that adjacent covers (47) to form the webs (32) receiving recesses (46) are spaced apart from each other and that the Leitschaufelkopf at least one of the guide vanes (20) by means of at least one in the respective web (32) facing S Side surface (48) of the recess (46) arranged spring element (52) on the inner ring (22) is resiliently mounted. Second vane assembly (12) according to claim 1, wherein the spring element (52) on the inner ring (22) and on the web (32) of the respective vane (20) biased rests. 3. vane assembly (12) according to claim 1 or 2, wherein for each respective vane (20) comprises two spring elements (52) which are arranged on opposite side surfaces (48) of the recess (46). 4. vane assembly (12) according to claim 1, 2 or 3, wherein the spring element (52) is designed as a clamping sleeve 5. vane assembly (12) according to one of claims 1 to 4, wherein in the side surfaces (48) has a pocket (50) for receiving the spring element (52) is provided, from which the spring element (52) protrudes partially. 6. vane assembly (12) according to any one of claims 1 to 5, wherein the spring force in the circumferential direction of the inner ring (22) is directed. 7. vane assembly (12) according to any one of claims 1 to 6, wherein the inner ring (22) comprises two partial rings (36, 38). 8. vane assembly (12) according to one of claims 1 to 7, wherein the inner ring (22) and / or the annular Guide vane (14) comprise at least two ring segments. 9. vane assembly (12) according to any one of claims 1 to 8, wherein the guide vane carrier (14) is formed as a housing. 10. Turbomachine with a vane arrangement (12) according to one of claims 1 to 9. 11. Turbomachine according to claim 10, designed as an axial compressor or axial turbine.