Air and steam cooled platform of a turbine blade or vane

Abstract

A turbine blade or vane includes a platform that is cooled by way of air and steam. The air cooling may form an open circuit, where the steam cooling may form a closed circuit.

Description

[0001] The present application hereby claims priority under 35 U.S.C. §119 on German patent application number 10217388.5, filed Apr. 18, 2002, the entire contents of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention generally relates to a cooled platform of a turbine blade or vane.

BACKGROUND OF THE INVENTION

[0003] EP 1 126 134 A1 discloses an air and steam cooled main blade or vane part of a turbine blade or vane.

[0004] U.S. Pat. No. 5,829,245 discloses a platform of a turbine blade or vane which is either steam or air cooled.

[0005] The complete cooling or a turbine blade or vane including main blade or vane region and platform and/or the root region by means of steam cooling requires a high design outlay, entailing cost problems. Although complete air cooling is possible, it leads to a higher loss of compressed air as a result of the compressed air which is removed in order to provide the cooling air.

SUMMARY OF THE INVENTION

[0006] It is an object of the present invention to provide a platform for a turbine blade or vane which is cooled and can be produced at low cost.

[0007] The present invention is based on the discovery that the steam cooling can be used for regions which are simple to cool, whereas the air cooling can be used for regions which are more difficult to cool and, furthermore, can lead to convective cooling of the bores and to film cooling.

[0008] In this context, it is advantageous if the steam cooling has a closed circuit.

[0009] Since the more critical region to be cooled is in the outer region of the platform, the outer region is advantageously air cooled, whereas the inner region is steam cooled. Therefore, the platform according to the invention is simultaneously air cooled and steam cooled. The steam cooling saves on compressed air for cooling.

[0010] The cooling action can be intensified in both the outer region and the inner region and with air and steam cooling by carrying out impingement cooling, in particular using impingement-cooling inserts.

[0011] If a single piece impingement-cooling insert is used, the number of parts which have to be fitted is reduced.

[0012] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

[0014] FIG. 1 diagrammatically depicts a longitudinal section through a platform of a turbine blade or vane; and

[0015] FIG. 2 illustrates a planned view of a platform of the turbine blade or vane.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0016] FIG. 1 shows part of a turbine blade or vane 1, in particular a gas turbine blade or vane 1, with, for example, a rectangular platform 4 (FIG. 2) in longitudinal section (section perpendicular to the plane of the drawing in FIG. 2).

[0017] The turbine blade or vane 1 has a main blade or vane region 7 with a main blade or vane cavity 10 in which, by way of example, air cooling and steam cooling of the main blade or vane region 7 takes place.

[0018] A plurality of turbine blades or vanes 1 are arranged in a turbine and are connected to one another, for example, by a connecting/sealing element 22 in the region of platform 4.

[0019] The platform 4 has an outer region 28 (FIG. 2, indicated by dashed lines), which is formed along an outer periphery 29 of the platform 4. The outer region 28 of the platform 4 surrounds an inner region 25 of the platform 4. The outer region 28 is, for example, air cooled. The air is taken, for example, from the turbine compressed air.

[0020] In the outer region 28 there is, for example, at least one impingement-cooling insert 13a in order to intensify the cooling action. The impingement-cooling insert 13a engages, for example, in a recess in the platform 4, i.e. in an air cooling cavity 16, the air cooling cavity 16 being arranged on that side of the platform 4 which is remote from the main blade or vane region 7, i.e. the underside 5.

[0021] In the impingement-cooling insert 13a there is at least one impingement air passage 31, through which air flows into the air cooling cavity 16. The direction of flow is indicated by arrows 37, the cooling air flowing from the underside 5 of the platform 4 toward an outer side 6 which is located in an outer region 40.

[0022] The impingement-cooling insert 13a produces impingement cooling of the platform 4 in the outer region 28 in a region of the outer side 6 which is subject to thermal loads.

[0023] Starting from the air cooling cavity 16 there is, for example, at least one air passage 34, in particular a film cooling opening 34, in the platform 4, through which the cooling air flows out of the air cooling cavity 16 into the outer region 40 surrounding the blade or vane 1. In this case, by way of example, the air passage 34 is designed as a film cooling bore, resulting in film cooling of the platform 4. The air cooling therefore forms, for example, an open system, since the air is not returned to the compressed air.

[0024] The outer region 28 is separated from the inner region 25 by a separating rib 57 which, by way of example, runs all the way around the underside 5 in the platform 4.

[0025] The steam cooling takes place in the inner region 25 of the platform 4 below the main blade or vane cavity 10 of the turbine blade or vane 1. In the inner region 25 there is, for example, an impingement-cooling insert 13d which engages in a corresponding recess 19, a steam cooling cavity 19, in the platform 4. Steam flows out of a steam circuit of the turbine into a steam reservoir 43 through a steam inlet opening 46, in order to flow into the steam cooling cavity 19 through at least one impingement steam passage 49 which is present. This produces impingement cooling of the platform 4 in the inner region 25.

[0026] The steam flows out of the steam cooling cavity 19 through a steam passage 52 in the platform 4, for example into the main blade or vane cavity 10 before flowing back into the steam circuit through a steam return passage 55, so that the steam cooling forms a closed circuit.

[0027] Other connections between steam cooling cavity 19 and steam return passage 55 without connection to the main blade or vane cavity 10 are also conceivable.

[0028] A cover 59 forms the steam reservoir 43, for example together with the impingement-cooling insert 13d.

[0029] The impingement-cooling insert 13d of the inner region 25 and the impingement-cooling insert 13a of the outer region 28 may also be formed integrally.

[0030] The impingement-cooling inserts 13a, 13d, by way of example, rest on the separating rib 57 and are secured to it, for example by welding.

[0031] Exemplary embodiments being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A turbine blade or vane, comprising:

a platform being both air and steam cooled.

2. The turbine blade or vane as claimed in claim 1, wherein the air cooling forms an open circuit.

3. The turbine blade or vane as claimed in claim 1, wherein the steam cooling forms a closed circuit.

4. The turbine blade or vane as claimed in claim 1, wherein the platform is air cooled in an outer region.

5. The turbine blade or vane as claimed in claim 1, wherein an inner region of the platform is steam cooled.

6. The turbine blade or vane as claimed in claim 4, wherein the cooling in the outer region is affected by impingement cooling.

7. The turbine blade or vane as claimed in claim 5, wherein the cooling in the inner region is affected by impingement cooling.

8. The turbine blade or vane as claimed in claim 6, wherein the platform includes at least one impingement cooling insert.

9. The turbine blade or vane as claimed in claim 6, wherein the outer region has at least one impingement cooling insert.

10. The turbine blade or vane as claimed in claim 7, wherein the inner region has at least one impingement cooling insert.

11. The turbine blade or vane as claimed in claim 1, wherein film cooling of the platform is affected by the air cooling by way of at least one film cooling bore.

12. The turbine blade or vane as claimed in claim 9, wherein the impingement-cooling insert of the inner region and the impingement-cooling insert of the outer region are formed integrally.

13. The turbine blade or vane as claimed in claim 2, wherein the platform is air cooled in an outer region.

14. The turbine blade or vane as claimed in claim 2, wherein an inner region of the platform is steam cooled.

15. The turbine blade or vane as claimed in claim 3, wherein an inner region of the platform is steam cooled.

16. The turbine blade or vane as claimed in claim 7, wherein the platform includes at least one impingement cooling insert.

17. The turbine blade or vane as claimed in claim 10, wherein the impingement-cooling insert of the inner region and the impingement-cooling insert of the outer region are formed integrally.

18. The turbine blade or vane as claimed in claim 2, wherein the steam cooling forms a closed circuit.

19. The turbine blade or vane as claimed in claim 4, wherein an inner region of the platform is steam cooled.

20. The turbine blade or vane as claimed in claim 18, wherein the platform is air cooled in an outer region and wherein an inner region of the platform is steam cooled.