Cooled turbine blade, in particular for a gas turbine engine

Abstract

The invention relates to a turbine blade (1), in particular for a gas turbine engine, with a blade (12) having a pressure-side wall section (10) and a suction-side wall section (11), extending radially and axially from an upstream flank (15) to an outstream flank (16) with respect to an installation state, in which a cooling channel arrangement (4) is formed with at least one cooling channel, which has an upstream channel section (40) extending at least predominantly radially near the upstream flank, an outstream channel section (42) extending at least predominantly radially near the outstream flank and an inner channel section (45) located between these, which is directed at least predominantly radially, as well as a first and second deflection section (41, 43) connecting these channel sections.Efficient cooling is achieved by arranging the inner channel section (44) downstream of the upstream channel section (40) and the downstream channel section (42).

Description

[0001] The invention relates to a turbine blade, in particular for a gas turbine engine, with a blade having a pressure-side wall section and a suction-side wall section, extending radially and axially from an upstream flank to an downstream flank with respect to an installation state, in which a cooling channel arrangement is formed with at least one cooling channel, which has an upstream channel section extending at least predominantly radially near the upstream flank, an downstream channel section extending at least predominantly radially near the downstream flank and an inner channel section located between these, which is directed at least predominantly radially, as well as a first and second deflection section connecting these channel sections.wherein, with respect to a cooling fluid guided through the cooling channel arrangement during cooling operation, the upstream channel section or the downstream channel section forms the inlet channel section. Furthermore, the invention relates to a method for manufacturing such a turbine blade and a high-pressure turbine equipped therewith.

[0002] A turbine blade of this type is described in DE 691 05 837 T2. In this known turbine blade, a blade body or airfoil extends essentially radially between a central blade root and an outer blade ring section and has a cooling channel arrangement inside the airfoil with a cooling channel that comprises a first channel section on the upstream side with respect to an installation condition in a turbine and a second channel section deflected thereto by about 180° via a bending section, wherein the channel sections thus lying side by side are separated from each other by means of a generally flat wall that is locally thickened in the area of ​​the bend.

[0003] The DE 600 28 529 T features ceramic turbine blades with a cooled trailing edge.

[0004] Various other designs of turbine blades with different configurations of cooling channels within the blade are shown in US 7600973 B2, US 7967563 B1, US 9518468 B2, KR 101513474 B1, and US 7967563 B1. In these designs, channel sections also transition into one another via deflections of essentially 180°, with various deflection sections and parallel channel sections being present.

[0005] The cooling channel arrangement thus formed in the turbine blade includes, for example, a serpentine cooling channel which can be designed for the flow of a cooling fluid from the downstream flank to the upstream flank in a forward direction or vice versa in a reverse direction. The channel arrangement designed for reverse flow generally results in particularly good cooling in the leading and middle sections of the blade, but less effective cooling at the end of the internal cooling passages, i.e., in the rear radially outer region of the blade, specifically in its trailing edge and radially outer regions.

[0006] A precision casting process is used to manufacture the turbine blade with its complex internal cooling channels. The mold consists of a ceramic shell (for the outer blade shape) and a conical core, which defines the internal channel shape. Complexly designed core extensions are required to securely fix the mold core. This is because, with a conventional serpentine cooling channel design, two core extensions are necessary on the outer surface. These extensions can interfere with each other in the outer area, especially when they have to be positioned close together at U-shaped bends. This limits the overall channel design.

[0007] The present invention is based on the objective of creating a turbine blade characterized by the most efficient and balanced blade cooling possible, while also achieving an economical manufacturing method, and also providing a high-pressure turbine, in particular a high-pressure turbine for a gas turbine engine, with improved cooling efficiency.

[0008] This problem is solved according to the invention in the case of a turbine blade with the features of claim 1, a method with the features of claim 7 and a high-pressure turbine with the features of claim 8.

[0009] In the case of the turbine blade, in connection with the features of the general term, it is further provided that the inner channel section is arranged downstream of the upstream channel section and the downstream channel section in the direction of flow of the cooling fluid.

[0010] In the production of the turbine blade, an investment casting process with a mold core is used, which is then used to form the cooling channel arrangement. The mold core is fixed in the radially outer region of the cooling channel arrangement by means of a radially outwardly directed core extension. According to the invention, the core extension is formed in the radially outer region of the first deflection section connecting the upstream and downstream channel sections by means of only one core extension. This simplified manufacturing process compared to conventional methods is made possible by the fact that the core extension completely fixes the core on the outside of the first deflection section, whereas in conventional designs, two extension arms must be held in place during the casting process for the core that generates the cooling channels.

[0011] As a result of the arrangement of the cooling channel sections specified in claim 1, a more balanced cooling of the blade body is achieved compared to previous designs, across the pressure and suction sides, particularly also in the region of the upstream and downstream flanks and in the radially outer blade region, thereby achieving improved cooling efficiency. The arrangement of the channel sections offers combined advantages such as those provided by channel arrangements with forward and reverse cooling fluid flow.

[0012] This results in a turbine blade with particularly advantageous design and cooling function by connecting the inner or middle channel section at its downstream end, via a flow-through opening, to a region of equal or lower cooling fluid pressure generated in the first deflection section connecting the upstream and downstream channel sections. This connection of the inner channel section at its downstream end in the junction between the upstream and downstream channel sections, within the region of lower cooling fluid pressure, ensures a continuous flow of cooling fluid within the turbine blade.During manufacturing, a simple, stable core fixation is achieved by attaching the core process in this area using a single core process, which also results in significant advantages of the manufacturing process.

[0013] For the cooling function and guidance of the cooling channel, it is advantageous that the first and second deflection sections are U-shaped with two U-legs merging into the respective channel sections and a curved U-rib encompassing a concave curvature area, and that the connection area is located upstream, centrally, or downstream within the concave curvature area of ​​the U-rib of the first deflection section. The alternative arrangements of the connection area on the U-rib, in conjunction with the cooling channel design and the respective blade, offer optimized adaptation possibilities with regard to the cooling function.

[0014] For efficient cooling of the turbine blade inside, the cooling fluid must flow through the cooling channels to exert a cooling effect. To ensure the best possible cooling effect, the cooling fluid can be blown out through film cooling holes on the pressure side and / or suction side.

[0015] Cooling efficiency for balanced cooling of the turbine blade can also be favorably influenced by equipping at least a section of the cooling channel with an obstacle structure or turbulators to generate vortices in the flow of the cooling fluid. These turbulences of the cooling fluid result in more uniform heat transfer and distribution across the blade.

[0016] Further advantageous measures for efficient and balanced cooling of the turbine blade result from the fact that the flow cross-sections are designed in terms of cross-sectional area and / or contour with regard to a desired temperature distribution over the pressure-side blade surface and suction-side blade surface.

[0017] The invention is explained in more detail below with reference to exemplary embodiments and the drawings. The drawings show: Fig. 1 shows a cross-section of a turbine blade with an upstream channel section, inner channel section and downstream channel section arranged therein, and Fig. 2 shows a longitudinal section (in the manner of a meridional section) along a substantially radially directed cross-sectional surface of a turbine blade with a blade extending radially between a central platform and a radially outer retaining part.

[0018] The Fig. 1 Figure 1 shows an exemplary cross-section of an airfoil 12 of a turbine blade 1, for example in the central region with respect to its radial extent. The airfoil 12 has a pressure-side wall section 10 and a suction-side wall section 11, which extend from an upstream flank 15 (also referred to as leading edge LE) to a downstream flank 16 (also referred to as trailing edge TE) and merge into one another in these flank regions. The pressure-side wall section 10 and the suction-side wall section 11 surround a cooling channel arrangement 4 formed inside the airfoil 12, comprising an upstream channel section 40, a downstream channel section 42, and an inner channel section 44 arranged between them, separated by partition wall sections 13 and 14 (except in Figure 1). Fig. 2 (shown deflection sections) are separated from each other.

[0019] Fig. 2 shows a longitudinal section of the blade 12 of a turbine blade 1, which is arranged on a central platform 2 and extends essentially radially outwards.

[0020] The cooling channel arrangement 4 formed in the blade 12 of the turbine blade 1 comprises (with respect to an operating state of a gas turbine having such turbine blades 1) the upstream channel section 40, located in the region of an upstream flank 15 and directed substantially radially outwards, the downstream channel section 42, located in the region of the downstream flank 16 and connected to it via a U-shaped first deflection section 41 and directed substantially radially inwards, and the inner, spatially central channel section 44, located in the central region of the turbine blade 1 and thus between the upstream channel section 40 and the downstream channel section 42.Between the inlet slope 15 and the outlet slope 16, the blade 12 has the pressure-side wall section 10 and the suction-side wall section 11, which delimit the channel sections 40, 42, 44 on their pressure-side and suction-side sides, respectively. Inside the blade 12, the channel sections 40, 42, 44 are laterally delimited (except for the deflection sections 41, 43) by the substantially radially extending partition wall sections 13, 14 of the partition wall arrangement 5, which extend between the pressure-side wall section 10 and the suction-side wall section 11 of the blade 12, as shown in the figure. Fig. 1 evident.

[0021] According to the cooling channel arrangement 4 described above, the U-shaped first deflection section 41, with its curved U-shaped web and the adjoining legs transitioning into the respective channel sections 40 and 42, is wider than the centrally located second U-shaped deflection section 43, which also has a U-shaped web extending in an arc and adjoining U-shaped legs transitioning into the respective channel sections 42 and 44. The inner or middle channel section 44 is fluidly connected at its downstream end region to the concave inner surface of the first deflection section 41 via a connecting area 45 (through the opening formed). In this connecting area of ​​the first deflection section 41, the flow channel is shaped accordingly.The flow cross-section in this area (with respect to an operating condition) creates a zone of similar, preferably lower, fluid pressure than in the downstream end region of the inner channel section 44. Consequently, a preferably continuous flow of the cooling fluid in the cooling channel is achieved between the inner channel section 44 and the first deflection area 41, and thus the subsequent area of ​​the cooling channel in the flow direction. These measures contribute significantly to efficient, largely balanced cooling of the turbine blade 1.

[0022] To support balanced cooling of the turbine blade 1, the cooling channel is provided with a turbulator-like obstacle structure 7 along its inner wall surface. This structure creates turbulence in the cooling fluid flow, thus homogenizing heat transfer in the relevant zones. Furthermore, for effective cooling, particularly of the pressure-side wall section 10 and the suction-side wall section 11, film cooling holes 6 are provided at least partially between these wall sections and the cooling channel assembly 4. These holes support the cooling of the respective outer wall sections or the outer surface of the blade 12. In addition to the cooling channel described, the cooling channel assembly 4 may include further cooling channels.

[0023] The design of the turbine blade 1 with the cooling channel arrangement 4 thus arranged in the blade 12, which has the connection area 45 between the end area of ​​the inner channel section 44 and the first deflection section 41, results not only in the aforementioned functional advantages in cooling but also in a simplification in manufacturing by means of the investment casting process, since only a core extension 3 can be used to stabilize the mold core in the connection area 45 between the end area of ​​the inner channel section 44 and the first deflection section 41, thus eliminating the need for a complex design of a core extension arrangement for stabilization.

Claims

1. Turbine blade (1), in particular for a gas turbine engine, with a blade (12) having a pressure-side wall section (10) and a suction-side wall section (11), extending radially and axially from an upstream flank (15) to an outstream flank (16) with respect to an installation state, in which a cooling channel arrangement (4) is formed with at least one cooling channel, which has an upstream channel section (40) extending at least predominantly radially near the upstream flank, an outstream channel section (42) extending at least predominantly radially near the suction flank and an inner channel section (44) located between these, which is directed at least predominantly radially, as well as a first and second deflection section (41, 43) connecting these channel sections,wherein, with respect to a cooling fluid carried through the cooling channel arrangement (4) in cooling operation, the upstream channel section (40) or the downstream channel section (42) forms the inlet channel section, characterized by the fact that the inner channel section (44) is arranged in the direction of flow of the cooling fluid downstream of the upstream channel section (40) and the downstream channel section (42).

2. Turbine blade according to claim 1, characterized by the fact that the inner channel section (44) is connected at its downstream end in a connection area (45) via a passage opening to a region of equal or lower cooling fluid pressure, which is generated in the first deflection section (41) connecting the upstream channel section (40) and the downstream channel section (42).

3. Turbine blade according to claim 2, characterized by thatthe first and second deflection sections (41, 43) are U-shaped with two U-legs transitioning into the respective two channel sections (40, 42, 44) and a curved U-bridge encompassing a concave curvature area and that the connection area (45) is located upstream, centrally or downstream in the concave curvature area of ​​the U-bridge of the first deflection section (41).

4. Turbine blade according to one of the preceding claims, characterized by that the pressure-side and / or suction-side wall section (10) is provided with film cooling holes (6).

5. Turbine blade according to one of the preceding claims, characterized by that at least one section of the cooling channel is provided with an obstacle structure (7) to create vortices in the flow of the cooling fluid.

6. Turbine blade according to one of the preceding claims, characterized by thatthe flow cross-sections in cross-sectional area and / or contour are designed with regard to a uniform temperature distribution over the pressure-side wall section (10) and suction-side wall section (11).

7. Method for manufacturing a turbine blade (1) according to one of the preceding claims, in which an investment casting process is used with a mold core forming the cooling channel arrangement (4) in the further manufacturing process, which is fixed in the radially outer area of ​​the cooling channel arrangement (4) by means of a radially outwardly directed core extension arrangement (3), characterized by that the core extension arrangement (3) in the radially outer area of ​​the first deflection section (41) connecting the upstream and downstream channel sections (40, 42) is formed by means of only one core extension (3).

8. High-pressure turbine for a jet engine, comprising turbine blades (1) of the structure according to any one of claims 1 to 6.

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