COOLING DEVICE FOR COOLING PLATFORMS OF A GUIDE VANE RING OF A GAS TURBINE

Abstract

A cooling device for cooling platforms of a guide vane ring of a gas turbine is arranged downstream inside a main flow channel of a combustion chamber. Cooling air passages are arranged in a wall of the platforms or of an intermediate piece that is connected therewith to guide cooling air for film cooling the surfaces of the platforms. At least in certain areas, the wall is configured with at least two layers having—as viewed from the main flow channel—an outer wall and a spaced apart inner wall forming a hollow space, wherein the hollow space can be impinged by cooling air through at least one cooling air blow-in opening inside the outer wall, and at least one cooling air blow-out opening is arranged inside the inner wall extending in the downstream direction to the surfaces of the platforms.

Claims

1. A cooling device for cooling platforms of a guide vane ring of a gas turbine that is arranged downstream inside a main flow channel of a combustion chamber, wherein in a wall of the platforms or of an intermediate piece that is connected therewith and that is arranged at the side of the combustion chamber of the platforms cooling air passage holes are provided, through which cooling air for film cooling is guided to the surfaces of the platforms, characterized in that, at least in certain areas, the wall is configured with at least two layers, having—as viewed from the main flow channel—an outer wall and an inner wall that is spaced apart from the same by a hollow space, wherein the hollow space can be impinged by cooling air through at least one cooling air blow-in opening inside the outer wall, and in that at least one cooling air blow-out opening is arranged inside the inner wall, extending in the downstream direction to the surfaces of the platforms.

2. The cooling device according to claim 1, wherein the hollow space is configured so as to be integral with at least one of the platforms or the intermediate piece.

3. The cooling device according to claim 1, wherein the hollow space is formed by the outer wall and the inner wall of the intermediate piece as well as an axial upstream-side wall of at least one of the platforms.

4. The cooling device according to claim 1, wherein the inner wall is formed by a separate, sheet metal type structural component.

5. The cooling device according to claim 4, wherein the sheet metal type structural component is attached at the outer wall by means of at least one attachment device.

6. The cooling device according to claim 4, wherein the sheet metal type structural component is attached by means of at least one attachment device at an upstream-side end of the wall in the area of a seal opposite a combustion chamber wall.

7. The cooling device according to claim 6, wherein the attachment device is formed by a retaining bolt for attachment of the seal at the wall.

8. The cooling device according to claim 4, wherein the sheet metal type structural component is fixated with its downstream-side end at least one of the platforms in a form-fit manner, in particular by means of a recess that engages under an undercut at the respective platform.

9. The cooling device according to claim 4, wherein the sheet metal type structural component rests at the inner side of the outer wall with its downstream-side end due to a defined pre-stress, wherein preferably a superimposition element that corresponds to the radial depth of the hollow space is provided at the sheet metal type structural component.

10. The cooling device according to claim 1, wherein the inner contour of the inner wall is formed so as to at least approximately align with an inner contour of an adjoining structural component, in particular a combustion chamber wall.

11. The cooling device according to claim 1, wherein the sheet metal type structural component is configured as a heat shield made of a high-temperature alloy and, if necessary, is configured with an additional heat-resistant coating.

12. The cooling device according to claim 1, wherein the sheet metal type structural component is configured as a circumferential ring or in a segment-shaped manner.

13. The cooling device according to claim 1, wherein at least one recess, in particular a bore or a slit, with a central axis is configured as the cooling air blow-in opening in the outer wall, extending inward with respect to the main flow channel in the upstream-side direction, and in that at least one recess, in particular a bore or a slit, with a central axis is configured as a cooling air blow-out opening in the inner wall, extending inward with respect to the main flow channel in the downstream-side direction in such a manner that it is angled in such a way that the cooling air that is discharged from the cooling air blow-out opening forms a cooling film on the surfaces of the platforms in an area directly in front of vane aerofoils of the guide vane ring.

14. The cooling device according to claim 4, wherein the outer wall in particular has an S-shaped cross-sectional curvature inwards against the main flow channel in the area of the downstream-side end of the hollow space and in an upstream-side area directly in front of vane aerofoils of the guide vane ring, namely in such a manner that the inner side of the outer wall forms the surface of the platforms in the area directly in front of the vane aerofoils.

15. The cooling device according to claim 4, wherein a distance between the sheet metal type structural component and the surfaces of the platforms forms a cooling air blow-out opening in an upstream-side area directly in front of the vane aerofoils of the guide vane ring.

Description

[0035] FIG. 1 to FIG. 5 respectively show a section of a gas turbine 1 that is configured as an aircraft turbine, in the present case with a combustion chamber 2 and a guide vane ring 4 that is arranged downstream of a discharge opening 3 of the combustion chamber 2 inside a main flow channel 40 and that is constructed in a segment-shaped manner with a plurality of guide vanes 5 in the circumferential direction, with the guide vanes 5 respectively having a vane aerofoil 6 between a radially inner platform 7 and a radially outer platform 8 between which they are supported in the known manner.

[0036] As has already been explained above, the surfaces 9 of the platforms 7, 8 that are facing towards the discharge opening 3 of the combustion chamber 2 have to be cooled because of the hot gas flow of the main flow channel 40 that is discharged through the discharge opening 3 of the combustion chamber 2. For this purpose, cooling air 13 is guided via a cooling device 10 from a secondary air area 15, which surrounds the combustion chamber 2 or a combustion chamber wall 14 and a wall 11, 12 of the platforms 7, 8, to the surfaces 9 of the platforms 7, 8 in an area directly upstream in front of an inflow side of the vane aerofoils 6 with a higher pressure than in the main flow channel 40 in order to achieve a film cooling at the surfaces 9 and a shielding of the platforms 7, 8 against the hot gas flow that is discharged from the combustion chamber 2. Since both the functional principle of the proposed cooling and the principal structure are analogous in the embodiments of FIG. 1 to FIG. 5, in the following the same reference signs are used for structural components having the same functionality in the different embodiments.

[0037] For the purpose of guiding cooling air 13 to the surfaces 9 of the platforms 7, 8, the cooling device 10 is designed in such a manner that, at least in certain areas, the wall 11, 12 of the platforms 7, 8 is configured with two layers having—as viewed from the main flow channel 40—an outer wall 16 or 17 and an inner wall 19 or 20 that is separated from the same by a hollow space 18. At least one cooling air blow-in opening 21 leads from the secondary air area 15 through the outer wall 16 or 17 into the hollow space 18. In turn, at least one cooling air blow-out opening 22 leads from the hollow space 18 in the downstream direction to the surfaces 9 of the platforms 7, 8 through the inner wall 19 or 20 the wall 11, 12 of the platforms 7, 8.

[0038] In the Figures, the number and the shape of the cooling air blow-in openings 21 and cooling air blow-out openings 22 is shown only in a symbolic manner, so that a divergent number of cooling air passage holes 21, 22 in different shapes, for example in the form of slits or round bores, and in the most different arrangements, which may be regular or irregular, grouped or isolated depending on the platform geometry, is also conceivable for achieving the desired film cooling.

[0039] In the embodiments of the cooling device 10 that is shown in FIG. 1 to FIG. 3, an inner wall 19 or 20 of the wall 11, 12 of the platforms 7, 8 that is facing towards the hot gas is respectively formed by a separate, sheet metal type structural component 23 which is attached by means of at least one attachment device 24, 25, 26 at the outer wall 16 or 17 of the wall 11 or 12 of the platforms 7, 8. In every shown embodiment, the sheet metal type structural component 23 is configured as a heat shield made of a high-temperature alloy and has a surface curvature that is adjusted to the surface contour of the platforms 7, 8, wherein in the present case an inner contour 27 of the inner wall 19, 20 of the platforms 7, 8 or of the sheet metal type structural component 23 corresponds to an inner contour 28 of the combustion chamber wall 14 that is adjoining in the upstream direction. Here, the inner contour 28 of the combustion chamber wall can also be configured with a cooled heat shield in a manner analogous to the sheet metal type structural component 23 of the cooling device 10.

[0040] FIG. 1 shows an embodiment of the sheet metal type structural component 23, in which it has a retaining bolt 24 as the attachment device for fixation at the outer wall 16 or 17, with the retaining bolt 24 passing through the outer wall 16 or 17 and being configured so as to be hollow there, and also has passage openings 29 in the area of the hollow space 18, so that the retaining bolt 24 forms a cooling air blow-in opening 21 at the same time, via which the hollow space 18 can be impinged by cooling air from the secondary air area 15.

[0041] Of course, also further cooling air blow-in openings that are inserted by means of a bore through the outer wall 16 or 17 can be provided apart from the cooling air blow-in opening that is formed by the retaining bolt 24.

[0042] In the embodiment according to FIG. 1, the sheet metal type structural component abuts the outer wall 16 or 17 with its upstream-side end in the area of an interface 30 formed by a distance between the discharge opening 3 of the combustion chamber 2 and the guide vane ring 4, while the sheet metal type structural component 23 forms at least one cooling air blow-out opening at its downstream-side end through a distance 31 with respect to the surface 9 of the platforms 7, 8 which is positioned directly in front of the inflow side of the vane aerofoils 6 and in the area of which the sheet metal type structural component 23 is made to rest at the inner side of the outer wall 16 or 17 by means of a spacing or superimposition element 32 that corresponds to the radial depth of the hollow space 18.

[0043] In contrast to the embodiment according to FIG. 1, in the embodiment that is shown in FIG. 2, the sheet metal type structural component 23 is attached at the outer wall 16 in a different manner and is designed differently with respect to the cooling air blow-in openings 21 and the cooling air blow-out openings 22. The embodiment according to FIG. 2 shows a fixation of the sheet metal type structural component 23 at its upstream-side end by means of a retaining bolt 25 of a flap seal 33, which is provided in a per se known manner for creating a seal between the discharge opening 3 of the combustion chamber 2 and the platforms 7, 8 of the guide vane ring 4, and which can be tilted into a sealing position through the different pressure in the secondary air area 15 and the main flow channel 40. Through the dual use of the retaining bolt 25 of the flap seal 33, an additional retaining bolt can be saved as compared to the embodiment according to FIG. 1, and a more free arrangement of the cooling air blow-in openings 21 in the hollow space 18 can be facilitated.

[0044] In the embodiment according to FIG. 2, the sheet metal type structural component 23 is fixated at its downstream-side end to the platforms 7 or their surface 9 in a form-fit manner, wherein, just like in all generally advantageous designs that are shown in FIG. 1 to FIG. 3, the surface 9 of the platforms 7 transitions into the inner side of the outer wall 16 or 17 of the wall 11 or 12 of the platforms 7, 8 particularly due to an S-shaped cross-sectional curvature 34 in the direction facing away from the main flow channel 40, whereby an installation space for the creation of the hollow space 18 and the arrangement of the sheet metal type structural component 23 as the inner wall 19 or 20 is created.

[0045] The form-fit fixation of the sheet metal type structural component 23 in the embodiment shown in FIG. 2 is designed as a kind of clip connection, in which a recess 36 is clipped in the radial direction under an undercut 35 at the platforms 7 at the downstream-side end of the sheet metal type structural component 23.

[0046] Here, the cooling air blow-out openings 22 are inserted into the sheet metal type structural component in any number and in the present case so as to be beveled downstream, wherein here a central axis of the cooling air blow-out openings 22 that are embodied as bores or slits extends radially in the direction of the main flow channel 40 in the downstream-side direction so as to be angled in such a manner that the cooling air that exits from the respective cooling air blow-out opening 22 forms a cooling film in an area directly in front of the vane aerofoils 6 on the surfaces 9 of the platforms 7, 8. Here, too, the cooling air blow-in openings 21 are configured so as to extend in the upstream-side direction radially in the direction of the main flow channels 40 for reasons of easier manufacturability, so that the cooling air is also deflected inside the hollow space 18.

[0047] FIG. 3 shows two minor variations on the cooling device 10, in which the sheet metal type structural components 23 in the radially inner platforms 7 and in the radially outer platforms 8 again respectively use the retaining bolt 25 of the flap seal 33 as an attachment device. In the embodiment according to FIG. 3, the sheet metal type support elements 23 are embodied with such a high residual stress that they rest with their downstream-side end at the inner side of the outer wall 19 or 20 without any further attachment, and that they are spaced apart from it only through the superimposition element 32, with the hollow space 18 being formed.

[0048] As can be seen from FIG. 4, the hollow space 18 can also be configured integrally or in one piece with the platforms 7, 8, wherein it can be manufactured in the course of the casting process together with the platforms 7, 8. Just like in the other embodiments, the arrangement and configuration of the cooling air blow-in openings 21 and the cooling air blow-out openings 22 can be realized in any manner, for example by means of machining.

[0049] As shown in FIG. 5, the hollow space 18 can also be configured at an intermediate piece 37, which for example supports the flap seal 33 that is not shown here, and which forms a kind of axial extension of the platforms 7, 8 in the direction of the discharge opening 3 of the combustion chamber 2. If the surface 9 of the platforms 7, 8 has a correspondingly short axial extension in the area directly upstream in front of the vane aerofoils 6, an efficient film cooling can be achieved at the surface 9 of the platforms 7, 8 also in such an embodiment with an intermediate piece 37, in which the cooling air passage holes 21, 22 are much easier to insert into the platforms 7, 8 themselves from the manufacturing-technical perspective, as usual in a separate structural component.

REFERENCE SIGNS

[0050] 1 gas turbine [0051] 2 combustion chamber [0052] 3 discharge opening of the combustion chamber [0053] 4 guide vane ring [0054] 5 guide vane [0055] 6 vane aerofoil [0056] 7 radially inner platform [0057] 8 radially outer platform [0058] 9 surface of the platform [0059] 10 cooling device [0060] 11 wall [0061] 12 wall [0062] 13 cooling air [0063] 14 combustion chamber wall [0064] 15 secondary air area [0065] 16 outer wall [0066] 17 outer wall [0067] 18 hollow space [0068] 19 inner wall [0069] 20 inner wall [0070] 21 cooling air blow-in opening [0071] 22 cooling air blow-out opening [0072] 23 sheet metal type structural component [0073] 24 attachment device, retaining bolt [0074] 25 attachment device, retaining bolt flap seal [0075] 26 attachment device [0076] 27 inner contour of the platform [0077] 28 inner contour of the combustion chamber [0078] 29 passage opening [0079] 30 interface [0080] 31 distance [0081] 32 superimposition element [0082] 33 flap seal [0083] 34 S-shaped cross-sectional curvature [0084] 35 undercut [0085] 36 recess [0086] 37 intermediate piece [0087] 40 main flow channel