Turbine blade comprising a cooling structure and associated production method

Abstract

A turbine blade has a blade tip, a cooling structure with cooling channels which are designed to have cooling fluid passed through them in order to cool the turbine blade during operation, an end section at a lower level than that of the blade tip, and an outer wall section extending up to the blade tip. The cooling structure is formed between the end section and the blade tip. A method produces a cooling structure of this type.

Claims

1. A turbine blade, comprising: a blade tip, a cooling structure comprising a multiplicity of cooling ducts which are configured to have a cooling fluid flowing through them during operation in order to cool the turbine blade, wherein the cooling structure comprises a lattice structure which forms the multiplicity of cooling ducts, an end portion that is recessed with respect to the blade tip, and an outer wall portion which: projects from the end portion; and terminates at and defines the blade tip, wherein the end portion and the outer wall portion bound a region that is recessed in the blade tip, and wherein the cooling structure fills an entirety of the region.

2. The turbine blade as claimed in claim 1, wherein diameters of cooling ducts of the multiplicity of cooling ducts are between 0.1 mm and 1 mm.

3. The turbine blade as claimed in claim 1, wherein cooling ducts of the multiplicity of cooling ducts that are fluidically separated from one another.

4. The turbine blade as claimed in claim 1, wherein the end portion comprises cooling-air bores.

5. The turbine blade as claimed in claim 1, wherein the cooling structure is formed at least partially in the outer wall portion, and wherein an outlet of cooling ducts of the multiplicity of cooling ducts leads into the blade tip.

6. The turbine blade as claimed in claim 1, wherein the outer wall portion is a closed wall portion, and wherein the cooling structure is at least partially enclosed by the outer wall portion.

7. The turbine blade as claimed in claim 1, further comprising: between the blade tip and the end portion, a plurality of inner walls, which extend through the cooling structure.

8. The turbine blade as claimed in claim 1, wherein the blade tip comprises a thermal barrier layer and/or an oxidation-resistant layer.

9. The turbine blade as claimed in claim 1, wherein the blade tip and/or the cooling structure are configured to form a rubbing edge during operation of the turbine blade.

10. The turbine blade as claimed in claim 1, wherein the cooling structure and/or the outer wall portion are produced or producible by additive manufacturing or by selective laser melting.

11. A method for producing a cooling structure for a turbine blade as claimed in claim 1, comprising: additively building of the cooling structure on the end portion of the turbine blade, wherein the cooling structure is additively built up on the end portion such that the multiplicity of cooling ducts are formed, wherein the multiplicity of cooling ducts are configured to have the cooling fluid flowing through them during operation in order to cool the turbine blade.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details of the invention are described in the following text with reference to the drawing. Identical or corresponding drawing elements are each provided with identical reference signs in the individual figures.

(2) FIG. 1 schematically shows a cross section through a part of a turbine blade of the prior art.

(3) FIG. 2 schematically shows a cross section through a part of a turbine blade (blade tip) of the present invention.

(4) FIG. 3 schematically shows a plan view of a rubbing edge of a turbine blade of the present invention.

(5) FIG. 4 schematically shows a cross section through a part of a turbine blade of the present invention in a further configuration.

(6) FIG. 5 schematically shows a plan view of a rubbing edge of a turbine blade of the present invention according to the configuration in FIG. 4.

(7) FIG. 6 schematically shows a cross section through a part of a turbine blade of the present invention in a further configuration.

(8) FIG. 7 schematically shows a plan view of a rubbing edge of a turbine blade of the present invention according to the configuration in FIG. 6.

(9) FIG. 8 schematically shows a cross section of a part of a turbine blade of the present invention in a further configuration.

(10) FIG. 9 schematically shows a cross section of a part of a turbine blade from an alternative perspective to FIG. 8.

DETAILED DESCRIPTION OF INVENTION

(11) FIG. 1 shows a perspective view of a portion of a turbine blade of the prior art. Specifically, an H-shaped profile of a tip-side portion of the turbine blade is indicated, which is identified in the following text by the reference sign 100, synonymously with the turbine blade.

(12) Furthermore, the turbine blade has a blade tip identified by the reference sign 20. Synonymously with the blade tip 20, a rubbing edge or a corresponding rubbing face can be identified. The lower part of the turbine blade 100 is not shown in the present figures, in particular in the cross-sectional depictions.

(13) The turbine blade 100 has an end portion 1. The end portion 1 is advantageously recessed with respect to the blade tip 20. The end portion 1 denotes a vertical portion of the profile shown in FIG. 1. Furthermore, the turbine blade has an outer wall portion 2, which encloses the end portion 1. The outer wall portion 2 can also be subdivided into a plurality of outer wall portions 2. The cross-sectional illustration illustrates two parts/regions of the outer wall portion. The outer wall portion extends expediently between the end portion 1 and the blade tip 20.

(14) Furthermore, the end portion 1 has one or more cooling-air bores 3. Through the cooling-air bores 3, it is advantageously possible for a cooling fluid to flow, in order to cool that tip-side portion of the blade that is highly loaded by the operating temperatures during operation of the turbine blade. Advantageously, the outer wall portion 2 represents an extension of side walls of the turbine blade, in particular an extension of the pressure side and the suction side of the turbine blade.

(15) FIG. 2 shows a schematic sectional view of a tip-side portion or end portion of a turbine blade 100 according to the present invention. The tip-side portion can advantageously denote at least one portion of the turbine blade 100 between the end portion 1 and the blade tip 20. The turbine blade 100 or the abovementioned portion comprises, in addition to the features shown in FIG. 1, a cooling structure 10. The cooling structure 10 is formed in particular between the end portion 1 and the blade tip 20. Advantageously, the cooling structure 10 extends along the entire length between the end portion 1 and the blade tip 20. In FIG. 2, the actual blade tip 20, or the rubbing edge or the rubbing region, extends over the entire cross section (horizontal direction) of the turbine blade 100 as a result of the configuration of the cooling structure 10.

(16) In FIG. 1, the cooling structure 10 fills the entire region between the end portion 1 and the outer wall portion 2. In this sense, the cooling structure 10 advantageously likewise extends substantially over the entire width of the cross-sectional illustration in FIG. 1, i.e. over the entire width of the turbine blade between the outer wall portions 2 shown.

(17) The cooling structure 10 comprises a plurality of cooling ducts 5, which are configured to have a cooling fluid (not explicitly indicated) flowing through them during operation of the turbine blade in order to cool the turbine blade 100 and/or the entire portion identified. The cooling fluid is expediently a process gas at a temperature lower than a hot-gas or operating temperature of the corresponding turbine.

(18) In FIG. 2, the cooling ducts are formed by a lattice structure, i.e. it is a question of open ducts or ducts that are fluidically connected together at least partially. The abovementioned lattice can likewise consist only of struts or a corresponding grid, such that a large duct volume can serve for cooling the turbine blade 100.

(19) The individual cooling ducts can have a diameter or a dimension of between 0.1 mm and 1 mm, for example as a result of the grid sizes of the lattice.

(20) According to the invention, the outer wall portions 2 are advantageously closed wall portions. However, it is possible, in the scope of the present invention, for the cooling structure 10 to be formed at least partially within the outer wall portions 2 (cf. FIGS. 8 to 10 below). In FIG. 2, the outer wall portions are advantageously continuous wall portions through which the cooling structure 10 does not pass.

(21) According to the invention—in contrast to the illustration in FIG. 1—a plurality of cooling-air bores 3 can be provided and formed in the end portion 1 of the turbine blade 100, in order, during operation of the turbine blade 100, to have a cooling fluid flowing through them from (radially) inside to (radially) outside (in other words from bottom to top in FIG. 2). As a result, in particular impingement cooling is realized for cooling the end portion 1.

(22) During operation of the turbine blade 100, the cooling fluid is advantageously guided through the cooling-air bores 3 from the inside, wherein it subsequently flows through the cooling structure 10 and effectively cools the region of the turbine blade between the end portion 1 and blade tip 20 and thus protects the blade from mechanical, oxidative and/or corrosive wear. This cooling is in particular effective because the cooling structure forms a large cooling surface area and at the same time the cooling fluid experiences less resistance as a result of advantageously large diameters of the cooling ducts.

(23) The cooling structure 10 is produced advantageously by an additive or generative manufacturing method, advantageously following the building up of the rest of or the basic structure for the turbine blade. Particularly advantageously, the cooling structure 10 is producible and/or produced by selective laser melting.

(24) Particularly advantageously, the cooling structure 10 is built up on the end portion of conventional turbine blades in a maintenance or repair step (“refurbishment”). The cooling structure is additively built up on the end portion advantageously such that the cooling ducts are formed. According to the described method, the cooling structure is built up advantageously in a radial direction with an oversize, such that the expedient length of the entire turbine blade can be set (automatically) by abrasion. Abrasive sealing off of the radial gaps of turbine blades in general is already known from the prior art.

(25) This method also advantageously allows the processing of the materials required for turbine blades, for example nickel- or cobalt-based superalloys.

(26) FIG. 3 shows a schematic plan view of the blade tip 20 of the turbine blade 100 illustrated in FIG. 2. FIG. 3 illustrates in particular a cross section (along a longitudinal axis of the turbine blade 100) or a plan view of the turbine blade 100, wherein the profile of the turbine blade is discernible. The outer wall portion 2 or an outer wall of the turbine blade is illustrated approximately circumferentially, wherein it can be interrupted only on a trailing edge (not explicitly illustrated) of the turbine blade 100.

(27) FIG. 4 shows a schematic sectional view of a tip-side portion of a turbine blade 100 according to a further configuration of the present invention. In addition to the illustration in FIG. 2, two inner walls 4 are illustrated by way of example, which can act as an additional rubbing edge at the blade tip 20. As seen in the cross section of the turbine blade 100, the inner walls are expediently arranged within the outer wall portion 2.

(28) As a result of this configuration, the rubbing edge of the turbine blade as a whole can be preserved particularly expediently from mechanical influences and consequently from wear. Although not explicitly illustrated, it is possible for further inner walls to be provided, in order to afford additional inventive advantages. Expediently, the inner walls 4 are arranged on the end portion 1 such that the cooling-air bores are not covered. The inner wall 4 extends—as illustrated—from the end portion in a radial direction expediently as far as the blade tip 20.

(29) Furthermore, FIG. 4 shows that the turbine blade, in particular at least the outer wall portion 2, the blade tip 20, and the cooling structure 10 are provided with a coating 7. The coating 7 is advantageously a thermal barrier coating and/or oxidation-resistant coating. It can furthermore be a multiple coating, for example with a first, inner layer as oxidation protection, in particular with materials comprising MAX phases and/or MCrAlY alloys, and a second, outer layer for thermal insulation.

(30) FIG. 5 shows a schematic plan view of the blade tip 20 of the turbine blade 100 illustrated in FIG. 4. In accordance with the illustration in FIG. 4, two inner walls 4 arranged between the pressure side and suction side of the turbine blade (bottom and top) are identified.

(31) FIG. 6 shows a schematic sectional view of a blade-side portion of a turbine blade 100 according to a further configuration of the present invention. According to this illustration, the cooling structure 10 is formed by an irregularly shaped, in particular bionically or biomimetically optimized or designed geometry. The latter can be for example a result of a simulation process or an optimization process, for example comprising genetic algorithms and/or comparable trial-and-error optimization steps. In particular, it is possible for parameters, such as the fluid resistance, the mechanical stability of the cooling structure and/or of the rubbing edge, or the thermal, mechanical, thermomechanical, oxidative or corrosive load during operation of the turbine blade 100, to be optimized for the design of the geometry. Furthermore, FIG. 6 reveals that the outer wall portions 2 are furthermore illustrated in a continuously closed manner, such that no cooling duct of the cooling structure 10 ends in or leads into the outer wall portions 2. As an alternative to this configuration, it is also possible for the cooling ducts 5 to lead into or end in the outer wall portions 2, however.

(32) FIG. 7 shows a schematic plan view of the blade tip 20 of the turbine blade 100 illustrated in FIG. 6. FIG. 7 reveals in particular that the irregular, bionic geometry of the cooling structure 10 according to this configuration is likewise distributed over the entire cross section of the turbine blade 100 or extends thereover.

(33) FIG. 8 shows a schematic sectional view of a tip-side portion of a turbine blade 100 according to a further configuration of the present invention. As an alternative to the above-described figures, the cooling structure 10 according to this configuration is formed for example at least partially in the outer wall portions. As a further difference, the cooling structure is formed only in the region of the wall portions 2 and in the form of closed cooling ducts 5 or cooling ducts 5 that are fluidically separated from one another at least partially. However, the cooling structure 10 or the cooling ducts 5 are configured such that outlets or exit openings 6 of the cooling ducts 5—just as in the above-described examples—lead into or end in the rubbing edge and/or the blade tip 20.

(34) It is furthermore apparent that the cooling-air bores 3 lead, on each side of the cross section shown, in each case into a duct structure (not explicitly indicated), i.e. into one or more cooling ducts that are each fluidically separated from one another at least partially. As a result of this configuration, the “cooling geometry” can be adapted specifically to particular “hot-spots” that arise during operation of the turbine blade 100.

(35) The individual cooling ducts can, according to this configuration, each have for example diameters or dimensions of between 0.1 mm and 1 mm.

(36) FIG. 9 schematically shows a cross section of a part of a turbine blade from an alternative perspective compared with FIG. 8, for example in section along a different axis. The illustration in FIG. 9 should be understood in particular such that in each case one cooling duct 5 (as described above) adjoins in each case one cooling-air bore 3 (cf. FIG. 8) and this cooling duct 5 then extends within one of the outer wall portions 2, wherein only the outlet 6 is arranged at the surface of the blade tip 20 or the rubbing edge, such that the cooling fluid can pass out of the cooling structure 10 in each case also only through the outlet 6. It is furthermore apparent that the cooling ducts 5 extend advantageously substantially over the entire cross section and/or the entire provided area of the blade tip 20 or of a rubbing region.

(37) Features or configurations of the different exemplary embodiments can be combined with one another in the present case to achieve the object of the invention. Thus, it is possible for example for a turbine blade to be provided, in which, in addition to the “duct cooling structure” illustrated in FIGS. 8 and 9, a “lattice cooling structure”, as described in FIGS. 2 to 7, is present, without departing from the concept of the invention.

(38) The invention is not limited to the exemplary embodiments by the description thereof, but rather encompasses every new feature and every combination of features. This includes in particular every combination of features in the claims, even when this feature or this combination itself is not explicitly specified in the claims or exemplary embodiments.