EP3428402B1 - Vane segment with curved relief slot - Google Patents

Description

The present invention relates to a guide vane segment for a gas turbine according to claim 1.

Directional indications such as “axial” or “axial”, “radial” or “radial” and “circumferential” are to be understood as referring to the machine axis of the gas turbine, unless the context explicitly or implicitly indicates otherwise.

Relief joints in guide vane segments of gas turbines serve in particular to reduce the constraints in the component that arise due to thermal expansion. In this way, other areas can be protected in which cracks would lead to vibration fatigue of the entire component, in particular of an entire guide vane ring which is formed by several guide vane segments.

In such relief joints, the linear main section of which has a radially inner base or joint bottom, it has been shown that high tensile stresses arise in the area of the base during operation of the gas turbine, which can lead to cracks at the joint in question. The service life of a guide vane segment or a guide vane ring, which is formed from several guide vane segments, is reduced by the formation of cracks at such relief joints.

Examples of relief joints are from the documents FR 2 929 983 A1 , US 2015/300192 A1 and U.S. 3,781,125 A known.

The object of the invention is to provide a guide vane segment in which crack formation is reduced.

To solve this problem, a guide vane segment according to claim 1 is proposed.

The provision of the additional section leads to an improved stress distribution in the area of the relief joint having the main section and at least one curved subsection. In particular, by providing the additional section, a base or joint base directly adjoining the linear main section can be avoided, as a result of which the high stresses in the area of the base or joint base are counteracted.

The relief joint runs in its radially innermost area in the circumferential direction and can end in an end area which is located radially further out than a radially innermost area of the relief joint.

In a further development, it is proposed that the additional section has at least one curved first section and at least one curved second section, which are connected to one another. The first section can be curved with a first radius and the second section can be curved with a second radius, wherein the first radius can be larger than the second radius. The two subsections can be connected with a third radius.

By providing differently curved subsections, in particular a first subsection with a first curvature and a second subsection with a second curvature that is different from the first curvature, the relief joint can have an optimized configuration with regard to stress distribution. Forces previously concentrated in the base or joint base can be absorbed in a distributed manner along the differently curved subsections.

The second partial section can be arranged such that it has a tangent which runs parallel to the main section
On the first subsection, on opposite sides of the main section in the circumferential direction, a respective second subsection, which is connected to the first subsection, can be arranged.

The main section is connected to a second subsection by means of a third subsection, in particular connected to a radially outer end of the second subsection. The first subsection can adjoin the second subsection connected to the main section. The third section and the adjoining second section are S-shaped. In particular, the third subsection and the second subsection flow into one another. In other words, the third sub-section is arranged between the main section and the one second sub-section. In the second variant, a kind of hook shape or loop shape of the relief joint is formed by the sequence of third section, second section, first section and further second section.

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

In one or more of the aforementioned embodiments, the relief joint can have the shape of a question mark without a point. In this and other embodiments, the main section can be arranged in a circumferentially central region of the relief joint, e.g. within a range of 20% to 80%, or 35% to 65% of the circumferential extension. The relief joint is unbranched and can only have a single end within the relevant front or rear sealing wall element.

So that the force distribution or stress distribution occurs optimally, a respective transition between the first section and the second section can be formed by a transition section, the transition section preferably having a transition radius that is smaller than the first radius and smaller than the second radius. The radii transitions can take place essentially tangentially, that is to say at a point at which there is a tangent to both adjacent but differently curved sections can be formed. Such tangential radius transitions can ensure that there are no jumps in the curvature along the differently curved subsections.

An end section can be assigned to at least one second partial section. The end section can be curved with the same radius (second radius) as the second partial section. However, it is also conceivable that the end section has a radius that is smaller than the second radius. The end section is designed in such a way that a tangent runs inclined to the main section, in particular would intersect the main section.

The invention also relates to a gas turbine, in particular an aircraft gas turbine, with at least one compressor arrangement, a combustion chamber and at least one turbine arrangement, the compressor arrangement and / or the turbine arrangement having at least one guide vane arrangement, which is formed by a plurality of guide vane segments arranged next to one another in the circumferential direction according to one of the preceding claims is formed.

It is pointed out that the present invention also includes those embodiments in which, as an alternative or in addition, a corresponding relief joint is provided in the inner shroud. The inner shroud can also (i.e. like the outer shroud), in relation to the axial longitudinal direction, comprise an axially front sealing wall element and an axially rear sealing wall element, in such a way that the inner shroud and these two sealing walls form a (inverted) trough-like profile in longitudinal section. In these embodiments, this alternative or additional radially inner relief joint on the axially front and / and rear sealing wall element (likewise) can be provided with a main section which, starting from a radial inner edge of the relevant front and / and rear sealing wall element, essentially extends along the sealing wall element extends radially outward. This additional or alternative radial relief joint can have at least one additional section adjoining the main section radially on the outside, which (likewise) can be formed by at least one curved subsection.

This radially inner relief joint can be designed correspondingly or analogously to the previously defined and the (outer) relief joint described in more detail below with reference to the figures, ie it can be a mirrored outer relief joint according to an or correspond to or substantially correspond to several of the preceding and / or subsequent embodiments.

• 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 nicht beanspruchten Ausführungsform.
• Fig. 3 zeigt in einer vereinfachten und schematischen Draufsicht eine Entlastungfuge gemäß einer zweiten erfindungsgemäßen Ausführungsform.
• Fig. 4 zeigt eine nicht beanspruchte Abwandlung der nicht beanspruchten 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 is described below by way of example and not in a restrictive manner with reference to the accompanying figures.

• Fig. 1 shows in a simplified and schematic perspective illustration a guide vane segment with conventional relief joints.
• Fig. 2 shows in a simplified and schematic plan view a relief joint according to a first embodiment not claimed.
• Fig. 3 shows a simplified and schematic plan view of a relief joint according to a second embodiment of the invention.
• Fig. 4 FIG. 13 shows a non-claimed modification of the non-claimed embodiment according to FIG Fig. 2 .
• Fig. 5 shows the guide vane segment of Fig. 1 for example with relief joints according to the two embodiments of FIG Figs. 2 and 3 .
• Fig. 6 shows simplified and qualitative stress curves for a conventional relief joint and for a relief joint according to the first embodiment.

Fig. 1 shows a simplified and schematic perspective illustration of a section of a guide vane segment 10. The guide vane segment comprises a plurality of guide vanes 12 arranged next to one another in the circumferential direction UR Fig. 1 an outer or upper shroud 14 of the guide vane segment 10 is shown in the radial direction RR. In relation to an axial direction AR, an axially front sealing wall element 18 and an axially rear 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 area and in an axially rear area, the sides 20, 22 of the sealing walls 16, 18 facing away from the tub formed form receptacles for connecting the guide vane segment 10 to further structural components of a gas turbine, not shown.

Several relief joints 24 are arranged in the rear sealing wall element 18 along the circumferential direction. The ones in the Fig. 1 The relief joints 24 shown run essentially linearly in the radial direction RR and along the inclined sealing wall element 18. According to this known embodiment, the relief joints 24 have only one main section 26 which has a base 28 or joint base radially on the inside.
As already explained in the introduction, the linearly running relief joints 24 are disadvantageous in that high stresses or tensile forces occur at the base 28, which is particularly evident from the Fig. 5 can be seen in the voltage curve diagram above and is marked with a white arrow. Investigations in this regard have shown values of over 1000MPa for a linear relief joint.

Fig. 2 shows in a simplified and schematic representation, which can also be referred to as a plan view of the sealing wall element 18, a relief joint 24 according to a first embodiment not claimed. The relief joint 24 comprises a main section 26. Furthermore, the relief joint 24 comprises a first subsection 30 and, in the example shown, two second subsections 32, which adjoin the first subsection on the left and right in the circumferential direction. The first subsection 30 and the two second subsections 32 together form an additional section 34 which, together with the main section 26, forms the entire relief joint 24. The main section 26 merges into the first sub-section 30; in particular, the main section 26 is connected to the first sub-section 30 in a central region of the first sub-section 30 in relation to the circumferential direction UR.

To clarify a possible delimitation of the subsections 30, 32, dotted lines 36 are drawn in, which illustrate a possible transition from one to the other subsection. It is pointed out, however, that the lines 36 drawn in purely schematically here only indicate where a transition between subsections can be qualitatively arranged.

The first section 30 has a radially inwardly convex curvature. It is thus curved concavely towards the main section 26. The curvature is formed by a first radius R1, which is in the Fig. 2 is shown illustratively as a dashed line. Looking at 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 essentially in the circumferential direction UR. At least it runs across the Radial direction RR or to the main section 26. In other words, it can also be said that the first subsection 30 is arranged or curved in such a way that it has a tangent T1 which is oriented orthogonally to the radial direction RR.

The second sub-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 is in the Fig. 2 is shown illustratively as a dashed line. The second subsection 32 extends essentially in the radial direction RR. At least it runs in sections transversely to the circumferential direction UR. In other words, it can also be said that the second partial section 32 is arranged such that it has a tangent T2 which is oriented parallel to the radial direction or parallel to the main section 26.

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

The course of the curvature of the additional section 34, shown in a purely schematic and simplified manner, with different radii of the subsections 30, 32 is in reality preferably designed in such a way that no jumps or steps occur along the changing curvatures. The radius transitions between two adjacent partial or transition sections 30, 32, 38 take place tangentially.

The free ends 39 of the second partial sections 32 can also be provided by outlet sections 40, which are not shown in greater detail here. Such run-out sections 40 have a fourth radius of curvature which is smaller than the second radius R2. The second partial sections 32 or their free ends 39 can be oriented towards the main section 26. In the Fig. 2 The relief joint 24 shown has a type of double hook shape or anchor shape.

Fig. 3 shows a second embodiment of a relief joint 24 with the main section 26, a first section 30 and two second sections 32. Unlike in the embodiment of FIG Fig. 2 the main section 26 is connected by means of a third subsection 42 to the second subsection 32 on the right in the circumferential direction UR. The third Sub-section 42 forms a counter-curve to the adjoining second sub-section 32. These two subsections 32, 42 form a kind of S-shaped connection between the main section 26 and the first subsection 30. With regard to the radii with which the first subsection 30 and the second subsections 32 are curved, essentially the same applies as above for Embodiment of the 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 area of the line 36.The same naturally also applies to the other transitions 38 between the second subsections 32 and the first subsection 30 at lines 36, as referred to above with reference to FIG Fig. 2 has already been described.

The relief joint 24 according to Fig. 3 has a single free end 39 on the left second partial section. This end 39 can also be formed by an outlet section 40, as described above with reference to FIG Fig. 2 has already been described. Overall, the relief joint 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 Fig. 2 . It has been shown that the relief joint does not necessarily have to have two second partial sections 32. Rather, a second subsection 32 can also be provided on only one side of the first subsection 30. Whether the second subsection 32 in such a configuration is on the left or, as in FIG Fig. 4 shown, is arranged on the right of the first section 30 is freely selectable. With regard to the dimensions of the radii of curvature, essentially the same applies as for the configuration according to FIG Fig. 2 , also for transition areas between the subsections 30, 32.

Fig. 5 shows the guide vane segment 10 of FIG Fig. 1 , wherein, in a simplified and purely illustrative manner, relief joints 24 according to FIG FIGS. 2 and 3 are shown. This illustration only serves to show the arrangement of such relief joints with curved subsections 30, 32. The specific number of relief joints 24 on a guide vane segment 10 can be freely selected. Usually, several similar or only similar relief joints 24 are provided for a guide vane segment 10. A mixture of relief joints like those in Fig. 5 are shown therefore generally does not correspond to a real embodiment, but is only used here for the purpose of illustration.

Finally it will still be on Fig. 6 referenced, whose upper tension picture has already been mentioned above in the introductory part of the description of the figures. The lower picture shows a typical stress 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 shown that in the area of the transition from the main section 26 to the first section 30, a significantly reduced stress occurs due to the design of the relief joint with the curved sections 30, 32. It has been shown in particular that the stresses in the area of interest on the radially inner End of the main section 26 are below 500MPa.

Comparing the stresses occurring in a conventional relief joint (top diagram) with those of a relief joint according to the present invention, the applicant was able to determine in tests that the stresses in the area of interest (white arrow) could be reduced by about four times. Furthermore, it has also been shown that no stresses occur at the free ends 39 of the second subsections 32 which would result in a high risk of crack formation.

Finally, it should be noted that the relief joints 24 according to the examples shown here ( Fig. 2-4 ) allow slightly more fluid or gas to pass than the conventional linear relief joints due to their overall greater overall length or overall expansion. However, this effect can be counteracted by making the curved relief joints narrower. This reduces the area that can be freely flowed through again.

Overall, the design of relief joints with curved subsections presented here makes it possible to provide guide vane segments which have an improved or extended service life without having to accept significant losses in terms of the sealing effect.

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

List of reference symbols

10

Guide vane segment

12

vane

14th

radially outer shroud

16

axially front sealing wall element

18th

axially rear sealing wall element

20th

axial front of the front sealing wall element

22nd

axial rear of the rear sealing wall element

24

Relief joint

26th

Main section

28

reason

30th

first section

32

second section

34

Additional section

36

parting line

38

Transition section

39

free end

40

Outlet section

42

third section

AR

Axial direction

RR

Radial direction

UR

Circumferential direction

R1

first radius

R2

second radius

T1

tangent

T2

tangent

Claims (11)

1. Guide vane 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 relevant circular arc and together form an annular portion, a plurality of guide vanes (12) being arranged next to one another in the circumferential direction (UR), in the radial direction (RR) between the outer shroud (14) and the inner shroud, which guide vanes are preferably integrally joined, in particular in one piece, to the inner shroud and the outer shroud (14), the outer shroud (14) comprising, with respect to an axial longitudinal direction (AR), 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) form a trough-like profile in longitudinal section, at least one unbranched relief joint (24) having a main portion (26) being provided on the axially front and/or rear sealing wall element (16, 18), which main portion, starting from a radial outer edge of the relevant front and/or rear sealing wall element (16, 18), extends substantially radially inward along the sealing wall element, the relief joint (24) having at least one additional portion (34) which adjoins the main portion (26) radially on the inside, the additional portion (34) being formed by at least one curved first sub-portion (30), a curved second sub-portion (32) and a third sub-portion (42), and the relief joint (24) extending in its radially innermost region in the circumferential direction (UR), the main portion (26) being connected to the second sub-portion (32) by means of the third sub-portion (42), characterized in that the third sub-portion (42) and the adjoining second sub-portion (32) are S-shaped.
2. Guide vane segment according to claim 1, characterized in that the relief joint (24) ends in an end region (39) which is radially further outward than a radially innermost region of the relief joint (24).
3. Guide vane segment according to either claim 1 or claim 2, characterized in that the first sub-portion is connected to the second sub-portion, and/or in that the first sub-portion (30) is curved with a first radius (R1) and in that the second sub-portion (32) is curved with a second radius (R2), the first radius (R1) being greater than the second radius (R2).
4. Guide vane segment according to any of claims 1 to 3, characterized in that the second sub-portion (32) is arranged such that it has a tangent (T2) which extends in parallel with the main portion (26).
5. Guide vane segment according to any of claims 1 to 4, characterized in that a relevant second sub-portion (32) which is connected to the first sub-portion (30) is arranged on the first sub-portion (30) on faces of the main portion (26) which are opposite one another in the circumferential direction (UR).
6. Guide vane segment according to any of claims 1 to 5, characterized in that the main portion (26) is connected to a radially outer end of the second sub-portion (32) by means of the third sub-portion (42).
7. Guide vane segment according to any of claims 1 to 6, characterized in that the first sub-portion (30) adjoins the second sub-portion (32) connected to the main portion (26).
8. Guide vane segment according to claim 7, characterized in that a further second sub-portion (32) adjoins the first sub-portion (30).
9. Guide vane segment according to any of claims 1 to 8, characterized in that the relief joint (24) is in the shape of a question mark without a dot, and/or the main portion (26) is arranged in a region of the relief joint (24) that is central in the circumferential direction.
10. Guide vane segment according to any of claims 3 to 9, characterized in that a relevant transition (36) between the first sub-portion (30) and the second sub-portion (32) is formed by a transition portion (38), the transition portion (38) preferably having a transition radius which is smaller than the first radius (R1) and smaller than the second radius (R2).
11. Gas turbine having at least one compressor arrangement, a combustion chamber and at least one turbine arrangement, wherein the compressor arrangement and/or the turbine arrangement has at least one guide vane arrangement which is formed by a plurality of guide vane segments (10) according to any of the preceding claims which are arranged next to one another in the circumferential direction.

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