EP3428402A1 - Vane segment with curved relief slot - Google Patents

Abstract

The invention relates to a stator blade segment (10) for a gas turbine, in particular an aircraft gas turbine, comprising at least one radially outer shroud (14) and a radially inner shroud, which extend along a respective arc and together form a ring section, wherein in the radial direction (RR) between the outer shroud (14) and the inner shroud a plurality of guide vanes (12) in the circumferential direction (UR) are arranged side by side, with the inner shroud and the outer shroud (14), preferably materially, in particular in one piece, are connected, wherein the outer Covering tape (14) relative to an axial longitudinal direction (AR) comprises an axially front sealing wall element (16) and an axially rear sealing wall element (18), such that the outer shroud (14) and the two sealing walls (16, 18) in longitudinal section forming a trough-like profile, wherein at the axially front and / or rear sealing wall element (16, 18) at least one discharge link e (24) is provided with a main portion (26) extending from a radial outer edge of the respective front and / or rear rear sealing wall element (16, 18) along the sealing wall element extends substantially radially inward. According to the invention, it is proposed that the relief joint (24) has at least one additional section (34) adjoining the main section (26) radially inward, wherein the additional section (34) is formed by at least one curved section (30, 32, 42).

Description

The present invention relates to a stator segment for a gas turbine, in particular an aircraft gas turbine, comprising at least one radially outer shroud and a radially inner shroud, which extend along a respective arc and together form a ring portion, wherein in the radial direction between the outer shroud and the inner shroud a plurality of guide vanes are arranged side by side in the circumferential direction, which are connected to the inner shroud and the outer shroud, preferably material fit, in particular in one piece, wherein the outer shroud comprises an axially forward sealing wall member and an axially rear sealing wall member, such that the outer shroud and the two sealing walls in longitudinal section form a trough-like profile, wherein at the axially front and / or rear sealing wall element at least one relief gap with an example substantially linearly extending Hau Is provided ptabschnitt, which extends from a radial outer edge of the respective front and / or rear sealing wall element along the sealing wall element substantially radially inward.

Directional information such as "axial" or "axial", "radial" or "radial" and "circumferential" are basically based on the machine axis of the gas turbine to understand, unless the context explicitly or implicitly otherwise results.

Relief joints in guide blade segments of gas turbines are used in particular to reduce the resulting thermal expansion in the component. As a result, other areas can be protected in which cracks would lead to a vibration fatigue of the entire component, in particular an entire vane ring, which is formed by a plurality of vane segments.

In such relief joints, the main linear section of which has a radially inner bottom or joint bottom, it has been found that high tensile stresses arise in the area of the bottom during operation of the gas turbines, which can lead to cracks at the joint in question. Cracking at such relief joints reduces the life of a vane segment or vane ring formed of multiple vane segments.

The object of the invention is to provide a vane segment in which cracking is reduced.

To achieve this object, it is proposed that, in the case of a guide blade segment, the relief gap has at least one additional section which adjoins the main section radially inward, wherein the additional section is formed by at least one curved section.

The provision of an additional section with at least one curved section leads to an improved stress distribution in the region of the relief section having the main section and at least one curved section. In particular, by providing the additional portion, a base or joint bottom directly adjoining the linear main portion can be avoided, which counteracts the high stresses in the region of the base or joint floor.

The relief gap may extend in its radially innermost region in the circumferential direction and / or terminate in one or more end regions, which are located radially farther outward than a radially innermost region of the relief joint.

It is further proposed that the additional portion has at least one curved first section and at least one curved second section, which are interconnected. In this case, the first section may be curved with a first radius, and the second section may be curved with a second radius, wherein the first radius may be greater than the second radius. The two sections may be connected to a third radius.

By providing differently curved sections, in particular a first section with a first curvature and a second section with a second curve, which is different from the first curve, the relief gap may have an optimized design with respect to the stress distribution. In this case, concentrating forces can be absorbed distributed along the differently curved sections so far in the ground or joint floor.

The first subsection may be arranged so as to have a tangent in the region of the connection to the main section which is substantially orthogonal to the main section runs. In other words, the tangent to the main portion may also be a tangent to an arcuate circumferential direction imagined in the region of the terminal. In this case, the first section may be formed convex so that it extends radially outward starting from the region of the connection to the main section. Based on the arrangement of a guide blade segment in a gas turbine, the first section of the additional section of the relief joint thus has a radially inwardly convex curvature and extends substantially in the circumferential direction. In other words, it can also be said that the first section forms an arc section whose chord extends substantially in the circumferential direction or substantially orthogonal to the radial direction.

The second subsection may be arranged to have a tangent parallel to the main section. In this case, the second subsection may be convexly formed in the circumferential direction away from the main section. Based on the arrangement of a guide vane segment in a gas turbine, the second subsection of the additional section of the relief joint thus has a convex curvature in a direction pointing away from the main section in the circumferential direction. Such a second subsection extends substantially in the radial direction. In other words, it can also be said that the second section forms an arc section whose chord extends substantially in the radial direction or substantially parallel to the main section or substantially orthogonal to the circumferential direction.

It follows from the above descriptions and features that the first section and the second section may preferably be concavely curved in the direction of the main section.

According to a first variant, the main portion may be connected to the first portion, in particular, the main portion may be connected to a central region of the first portion. In this case, on the first subsection on circumferentially opposite sides of the main section, a respective second subsection is arranged, which is connected to the first subsection. The first section and the two adjoining second sections thereby form two hook-shaped sections connected to the main section. In other words, it can also be said that the discharge gap with main section and the additional section, which has the first section and two second section, form a kind of anchor shape of the relief joint.

According to a second variant, the main section can be connected by means of a third section to a second section, in particular connected to a radially outer end of the second section. In this case, the first subsection can adjoin the second subsection connected to the main section. Furthermore, in this second variant, a further second subsection can adjoin the first subsection. Finally, in this case the third section and the subsequent second section can be S-shaped. In particular, the third section and the second section flow into each other. In other words, the third section is arranged between the main section and the one second section. In the second variant, a type of hook shape or loop shape of the relief joint is formed by the sequence of third subsection, second subsection, first subsection and further second subsection.

"S-shaped" may mean in particular that the respective sections together form an S-shape and / or are curved in opposite directions.

In one or more of the aforementioned embodiments, the relief gap may be in the form of a question mark without a dot. The main portion may, in this and other embodiments, be arranged in a circumferentially central region of the relief gap, e.g. within a range of 20% to 80%, or even 35% to 65% of the circumferential extent. Alternatively or additionally, the relief gap can also be unbranched and / or have only a single end within the relevant front or rear sealing wall element.

So that the force distribution or stress distribution takes place optimally, a respective transition between the first section and the second section may be formed by a transition section, wherein preferably the transition section has a transition radius which is smaller than the first radius and smaller than the second radius. In this case, the radii transitions can take place substantially tangentially, that is to say at a point at which a tangent to both adjacent but differently curved sections can be formed. By such tangential radii transitions can be ensured that there are no cracks in the curvature along the differently curved sections.

At least one second section can be assigned an end section. In this case, the end portion with the same radius (second radius) may be curved as the second portion. But it is also conceivable that the end portion has a radius which is smaller than the second radius. In this case, the end portion is formed so that a tangent inclined to the main portion, in particular the main portion would cut.

The invention further relates to a gas turbine, in particular an aircraft gas turbine, with at least one compressor assembly, a combustion chamber and at least one turbine assembly, wherein the compressor assembly and / or the turbine assembly comprises at least one vane assembly by a plurality of circumferentially juxtaposed vane segments according to any one of the preceding claims is formed.

It should be noted that the present invention also includes such embodiments in which, alternatively or additionally, a corresponding relief gap is provided in the inner shroud. The inner shroud may also (i.e., like the outer shroud) comprise an axial forward seal wall member and an axially rearward seal wall member such that the inner shroud and these two seal walls form a (reverse) trough-like profile in longitudinal section. In this embodiment, in these embodiments, this alternative or additional radially inner relief joint may be provided on the axially front and / or rear sealing wall element (also) with a main section which extends essentially from a radial inner edge of the respective front and / or rear sealing wall element along the sealing wall element extends radially outward. This additional or alternative radial relief joint may have at least one additional section which adjoins the main section radially on the outside and which may also be formed by at least one curved section.

This radially inner relief gap may be formed corresponding to or analogous to the previously defined and described in more detail below with reference to the figures (outer) relief joint, ie it may correspond to a mirrored outer relief joint according to one or more of the preceding and / or following embodiments or substantially correspond.

• Fig. 1 zeigt in einer vereinfachten und schematischen Perspektivdarstellung ein Leitschaufelsegment mit herkömmlichen Entlastungsfugen.
• Fig. 2 zeigt in einer vereinfachten und schematischen Draufsicht eine Entlastungsfuge gemäß einer ersten Ausführungsform.
• Fig. 3 zeigt in einer vereinfachten und schematischen Draufsicht eine Entlastungfuge gemäß einer zweiten Ausführungsform.
• Fig. 4 zeigt eine Abwandlung der Ausführungsform gemäß Fig. 2.
• Fig. 5 zeigt das Leitschaufelsegment der Fig. 1 beispielhaft mit Entlastungfugen gemäß der beiden Ausführungsformen der Fig. 2 und 3.
• Fig. 6 zeigt vereinfacht und qualitativ Spannungsverläufe für eine herkömmliche Entlastungsfuge und für eine Entlastungsfuge gemäß der ersten Ausführungsform. □

The invention will be described below by way of example and not limitation with reference to the attached figures.

• Fig. 1 shows in a simplified and schematic perspective view of a vane segment with conventional relief joints.
• Fig. 2 shows in a simplified and schematic plan view of a relief joint according to a first embodiment.
• Fig. 3 shows in a simplified and schematic plan view of a discharge gap according to a second embodiment.
• Fig. 4 shows a modification of the embodiment according to Fig. 2 ,
• Fig. 5 shows the vane segment of Fig. 1 by way of example with discharge gaps according to the two embodiments of FIG FIGS. 2 and 3 ,
• Fig. 6 shows simplified and qualitative voltage curves for a conventional relief joint and for a relief joint according to the first embodiment. □

Fig. 1 shows in a simplified and schematic perspective view a section of a vane segment 10. The vane segment comprises a plurality of circumferentially UR arranged side by side vanes 12. In Fig. 1 is shown in the radial direction RR outer and upper shroud 14 of the vane segment 10. with respect to an axial direction AR, an axially forward sealing wall element 18 and an axially rearward sealing wall element 20 are arranged on the shroud 14. The outer shroud 14 and the two sealing walls 16, 18 form a trough-like profile in longitudinal section. In an axially front region and in an axially rear region, the sides 20, 22 of the sealing walls 16, 18 which are respectively remote from the formed trough form receptacles for connecting the vane segment 10 to further structural components, not shown, of a gas turbine.

In the rear sealing wall element 18 a plurality of relief joints 24 are arranged along the circumferential direction. The in the Fig. 1 Relief joints 24 shown extend substantially linearly in the radial direction RR and along the inclined sealing wall element 18th

The relief joints 24, according to this known embodiment, only a main portion 26 which has a radially inner bottom 28 or bottom joint.
As already explained in the introduction, the linearly extending relief joints 24 are disadvantageous in that high stresses or tensile forces occur at the base 28, which is particularly the case in FIG Fig. 5 in the upper voltage curve diagram and is marked with a white arrow. Related investigations have shown values of over 1000MPa for a linear relief joint.

Fig. 2 shows in a simplified and schematic representation, which can also be designated as a plan view of the sealing wall element 18, a relief joint 24 according to a first embodiment. The relief gap 24 comprises a main portion 26. Furthermore, the relief gap 24 comprises a first portion 30 and in the example shown, two second portions 32, which adjoin the first portion in the circumferential direction left and right. The first section 30 and the two second sections 32 together form an additional section 34 which, together with the main section 26, forms the entire relief gap 24. The main section 26 merges into the first section 30, in particular the main section 26 is connected to the central section of the first section 30 in a central region of the first section 30 relative to the circumferential direction UR.

To illustrate a possible delineation of the subsections 30, 32 dotted lines 36 are drawn in, which illustrate a possible transition from one to the other subsection. It should be noted, however, that the purely schematically drawn lines 36 indicate only where a transition between subsections can be qualitatively arranged approximately.

The first section 30 has a radially inwardly convex curvature. It is thus concavely curved toward the main section 26. The curvature is formed by a first radius R1, which in the Fig. 2 illustratively drawn as a dashed line. Considering the two lines 36, which indicate the extent of the first section 30 in the circumferential direction UR, it can also be said that the first section 30 extends substantially in the circumferential direction UR. At the least, it may be said that the first section 30 is curved so as to have a tangent T1 orthogonal to the radial direction RR.

The second section 32 has a convex curvature away from the main section 26 in the circumferential direction. The curvature is formed by a second radius R2, which in the Fig. 2 illustratively drawn as a dashed line. The second section 32 extends substantially in the radial direction RR. At least it runs in sections across the circumferential direction UR. In other words, it can also be said that the second subsection 32 is arranged to have a tangent T2 that is parallel to the radial direction or parallel to the main section 26.

The first radius R1 is greater than the second radius R2. In a region of the respective lines 36 or the transitions between two subsections 30, 32, a transition section 38 may be provided. Such a transition section may be curved with a third radius which is smaller than the first radius R1 and the second radius R2.

The purely schematically and simplified illustrated curvature of the additional portion 34 with different radii of the sections 30, 32 is preferably carried out in reality so that no cracks or steps arise along the changing curvatures. The radii transitions between two adjacent partial or transition sections 30, 32, 38 are tangential.

The free ends 39 of the second sections 32 may also be provided by outlet sections 40, which are not shown in detail here. Such outlet portions 40 have a fourth radius of curvature which is smaller than the second radius R2. The second sections 32 or their free ends 39 can be aligned with the main section 26. In the Fig. 2 illustrated relief gap 24 has a kind of double hook shape or anchor shape.

Fig. 3 shows a second embodiment of a relief joint 24 with the main portion 26, a first portion 30 and two second portions 32nd Unlike in the embodiment of Fig. 2 the main section 26 is connected by means of a third section 42 with the right in the circumferential direction UR second section 32. The third section 42 forms a counterbending to the adjoining second section 32. These two sections 32, 42 form a kind of S-shaped connection between the main section 26 and the first section 30. With respect to the radii with which the first section 30 and the second sections 32 are curved, essentially the same applies as above Embodiment of Fig. 2 described. It is clear that a transition section can also be provided at the transition between the third subsection 42 and the adjoining second subsection 32 in the region of the line 36. The same applies, of course, to the other transitions 38 between the second subsections 32 and the first subsection 30 at the lines 36, as stated above with reference to Fig. 2 has already been described.

The relief joint 24 according to Fig. 3 has a single free end 39 on the left second section. Also, this end 39 may be formed by a spout portion 40, as described above with reference to the Fig. 2 has already been described. Overall, results for the relief gap 24 according to Fig. 3 a kind of hook shape or loop shape.

Fig. 4 shows a modification of the relief joint 24 according to Fig. 2 , It has been shown that the relief gap does not necessarily have to have two second sections 32. Rather, a second section 32 may be provided on the first section 30 only on one side. Whether the second portion 32 in such a configuration with respect to the circumferential direction UR left or, as in the Fig. 4 is shown, right on the first section 30 is arranged, is arbitrary. With regard to the dimensions of the radii of curvature, essentially the same applies as for the embodiment according to FIG Fig. 2 , as well as for transition areas between the sections 30, 32nd

Fig. 5 shows purely illustratively the vane segment 10 of Fig. 1 , wherein simplified and purely illustrative relief joints 24 according to Fig. 2 and Fig. 3 are drawn. This illustration serves only to show the arrangement of such relief joints with curved sections 30, 32. The specific number of relief joints 24 on a vane segment 10 is arbitrary. Usually, a plurality of similar or only similar relief joints 24 are provided for a vane segment 10. A mix of relief joints, as in Fig. 5 Thus, as a rule, this does not correspond to a real embodiment, but merely serves the purpose of illustration here.

Finally it will open Fig. 6 whose upper voltage pattern has already been mentioned above in the introductory part of the description of the figures. The lower picture shows a typical voltage curve for a relief joint 24 according to an embodiment as shown in FIG Fig. 2 has been shown and explained there. It has been found that in the region of the transition from the main section 26 to the first section 30, a significantly reduced tension occurs due to the configuration of the relief joint with the curved sections Subsections 30, 32. It has been found, in particular, that the stresses in the region of interest at the radially inner end of the main section 26 are less than 500 MPa.

Comparing the stresses of a conventional relief joint (upper diagram) with those of a relief joint according to the present invention, the Applicant was able to establish in experiments that the stresses in the region of interest (white arrow) could be reduced by about fourfold. Furthermore, it has also been shown that at the free ends 39 of the second sections 32 no tensions occur in which there would be a high risk of cracking.

Finally, it should be noted that the relief joints 24 according to the examples shown here ( Fig. 2-4 ) pass slightly more fluid or gas due to their overall larger overall length or overall extent, as the conventional linear relief joints. This effect can be counteracted by narrower execution of the curved relief joints. As a result, the freely flowable surface is reduced again.

Overall, the presented here embodiment of relief joints with curved sections the opportunity to provide guide blade segments that have an improved or extended life, but without significant loss of the sealing effect must be taken into account.

In a gas turbine, not shown here, in particular an aircraft gas turbine, a vane ring may be formed by a plurality of vane segments 10 described above, which are arranged side by side in the circumferential direction. Such a vane ring can be assigned to a compressor side or a turbine side of the gas turbine.

LIST OF REFERENCE NUMBERS

10

vane segment

12

vane

14

radially outer shroud

16

axially front sealing wall element

18

axially rear sealing wall element

20

axial front side of the front sealing wall element

22

axial rear side of the rear sealing wall element

24

Entlastungsfuge

26

main section

28

reason

30

first section

32

second subsection

34

additional section

36

parting line

38

Transition section

39

free end

40

exit section

42

third section

AR

axially

RR

radial direction

UR

circumferentially

R1

first radius

R2

second radius

T1

tangent

T2

tangent

Claims (15)

Guide vane segment (10) for a gas turbine, in particular aircraft gas turbine, comprising at least one radially outer shroud (14) and a radially inner shroud extending along a respective arc and together form a ring portion, wherein in the radial direction (RR) between the outer shroud (14) and the inner shroud a plurality of guide vanes (12) in the circumferential direction (UR) are arranged side by side, which are connected to the inner shroud and the outer shroud (14), preferably materially, in particular in one piece, wherein the outer shroud (14) relative to an axial longitudinal direction (AR) comprises an axially forward sealing wall element (16) and an axially rear sealing wall element (18), such that the outer shroud (14) and the two sealing walls (16, 18) form a trough-like profile in longitudinal section, wherein at the axially front and / or rear sealing wall element (16, 18) at least one relief gap (24) having a Hauptabsch nitt (26) is provided, which extends starting from a radial outer edge of the respective front and / or rear sealing wall element (16, 18) along the sealing wall element according to substantially radially inwardly, characterized in that the relief gap (24) at least one radially inside the main portion (26) adjoining additional portion (34), wherein the additional portion (34) by at least one curved portion (30, 32, 42) is formed. Guide vane segment according to claim 1, characterized in that the relief gap (24) extends in its radially innermost region in the circumferential direction (UR) and / or ends in one or more end regions (39), which lie radially further outward read a radially innermost Relief joint area (24). Guide vane segment according to claim 2, characterized in that the additional portion (34) at least one curved first portion (30) and at least one curved second portion (32) which are interconnected, and / or that the first portion (30) with a first radius (R1) is curved, and that the second portion (32) is curved with a second radius (R2), wherein the first radius (R1) is greater than the second radius (R2). Guide vane segment according to claim 2 or 3, characterized in that the first section (30) is arranged so that in the region of the connection to the main portion (26) has a tangent (T1) which is substantially orthogonal to the main portion (26) , Guide vane segment according to one of claims 2 to 4, characterized in that the first section (30) is formed convex so that it extends radially outward from the region of the terminal to the main portion. Guide vane segment according to one of claims 2 to 5, characterized in that the second subsection (32) is arranged so that it has a tangent (T2) which is parallel to the main portion (26). Guide vane segment according to one of claims 2 to 6, characterized in that the second portion (32) in the circumferential direction (UR) away from the main portion (26) is convex. Guide vane segment according to one of claims 2 to 7, characterized in that the main portion (26) is connected to the first portion (30), in particular that the main portion (26) is connected to a central region of the first portion (30). Guide vane segment according to claim 8, characterized in that on the first part section (30) in the circumferential direction (UR) opposite sides of the main portion (26), a respective second portion (32) is arranged, which is connected to the first portion (30). Guide vane segment according to one of claims 2 to 7, characterized in that the main portion (26) by means of a third portion (42) with a second portion (32) is connected, in particular with a radially outer end of the second portion (32) is connected. Guide vane segment according to claim 10, characterized in that the first section (30) adjoins the second section (32) connected to the main section (26). Guide vane segment according to claim 11, characterized in that adjoining the first subsection (30) is a further second subsection (32). Guide vane segment according to one of claims 10 to 12, characterized in that the third section (42) and the adjoining second section (32) are S-shaped and / or the discharge gap (24) has the shape of a question mark without a dot and / or the main portion (26) is arranged in a circumferentially central region of the relief joint (24). Guide vane segment according to one of claims 2 to 13, characterized in that a respective transition (36) between the first portion (30) and the second portion (32) by a transition portion (38) is formed, wherein preferably the transition portion (38) a Transition radius which is smaller than the first radius (R1) and smaller than the second radius (R2). A gas turbine having at least one compressor assembly, a combustor, and at least one turbine assembly, the compressor assembly and / or the turbine assembly having at least one vane assembly formed by a plurality of circumferentially juxtaposed vane segments (10) of any one of the preceding claims.

Images