Radial turbine rotor with additive layer manufactured components

Abstract

A multi-piece radial turbine rotor includes a hub and a bladed crown manufactured via additive layer manufacturing. A bond is formed between the hub and the bladed crown to fix the components together for rotation.

Description

FIELD OF THE DISCLOSURE

[0001] The present disclosure relates generally to radial turbines, and more specifically to radial turbine rotors.BACKGROUND

[0002] Radial turbine rotors are characterized by rotating in response to a flow of working fluid radially inwardly toward the axis of rotation. In many applications, radial turbine rotors can be more efficient than axial turbine rotors that rotate in response to a flow of working fluid primarily parallel to the axis of rotation.

[0003] To increase efficiency of radial turbine rotors, it can be beneficial to increase the temperature of the working fluid that interacts with the rotors. However, manufacturing radial turbine rotors from high temperature materials and / or incorporating an active supply of cooling air into radial turbines presents challenges.SUMMARY

[0004] The present disclosure may comprise one or more of the following features and combinations thereof in an effort to address challenges in radial turbine rotor design and manufacture.

[0005] A radial turbine rotor may comprise a hub and a crown with blades coupled to the hub. The hub may be arranged around a central axis and may define a radially innermost surface of the rotor. The crown may be formed of metallic layers deposited additively to provide monolithic, single piece with a flowpath ring that extends annularly around the hub and turbine blades that extend radially outwardly from the flowpath ring.

[0006] In some embodiments, the crown is coupled to the hub via a metallurgical bond process that fixes the crown to the hub for rotation therewith. The bond layer may be a diffusion bond joint, transient liquid phase bond joint, or a braze assist diffusion bond joint. It is also contemplated to couple the crown to the hub via mechanical or simple brazing as may be suitable for certain applications.

[0007] In some embodiments, at least one of the plurality of turbine blades is formed to include a cooling air passageway therein. Complex cooling features including pins and fins may be formed within the cooling air passageway.

[0008] In some embodiments, the flowpath ring is formed to include at least one cooling air feed channel that opens radially inwardly to face the central axis. The cooling air feed channel may be in fluid communication with the cooling air passageway formed in at least one of the plurality of turbine blades. An axial end of the at least one cooling air feed channel may be open to receive cooling air at a location radially inward of the plurality of turbine blades.

[0009] In some embodiments, the crown comprises nickel superalloy materials. The hub can also comprise nickel superalloy materials. Other suitable materials can also be used. In some other embodiments, other high temperature material systems such as refractory alloys like C103 Niobium alloy could be used.

[0010] According to another aspect of the present disclosure, a method of making a radial turbine rotor is disclosed. The method may comprise forging a hub arranged around a central axis, forming a crown with a flowpath ring that extends annularly around the hub and a plurality of turbine blades that extend radially outwardly from the flowpath ring via additive layer manufacturing so as to provide a monolithic, single piece component, and coupling the crown to the hub by forming a joint radially between a radially inwardly facing surface of the crown and a radially outwardly facing surface of the hub.

[0011] In some embodiments, the joint is a diffusion bond layer. The hub and the crown may be shrink fit together by sufficiently heating the crown and cooling the hub. Thermal expansion of the crown can enable insertion of the hub into the crown. After the hub is inserted into the crown, the assembly is heated in a vacuum furnace to a sufficient temperature to complete diffusion bonding. In certain embodiments, to join the crown to the hub, a transient liquid phase bonding process may be used. In this case a melting point suppressant is applied to one (or both) surfaces to be joined. The bond process is “self fixtured” meaning it doesn't require the use of separate delta alpha tooling to apply a load across the bond joint. This is accomplished by shrink fitting the hub and crown together after application of the melting point suppressant and then heating this assembly in a vacuum furnace up to a temperature to accomplish the transient liquid phase bond.

[0012] In some embodiments, the crown comprises nickel superalloy materials. The hub can also comprise nickel superalloy materials. Other suitable materials can also be used. In some other embodiments, other high temperature material systems such as refractory alloys like C103 Niobium alloy could be used.

[0013] These and other features of the present disclosure will become more apparent from the following description of the illustrative embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a perspective view of a radial turbine rotor including a forged hub and a bladed crown formed via additive layer manufacturing (ALM), the crown bonded to the hub;

[0015] FIG. 2 is a detail view of a portion of FIG. 1 with a portion of a blade broken away to show complex internal geometry produced via additive layer manufacturing within the blade to enable optimized active cooling during use; and

[0016] FIG. 3 is an exploded perspective view of the radial turbine rotor with the forged hub outside the crown prior to bonding of the hub to the crown.DETAILED DESCRIPTION OF THE DRAWINGS

[0017] For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments illustrated in the drawings and specific language will be used to describe the same.

[0018] A radial turbine rotor 10 for use in a gas turbine engine includes a hub 12 and a crown 14 as shown in FIG. 1. The radial turbine rotor 10 extracts energy from a working fluid, such as hot, high pressure combustion products, flowing through a gas path 18. The radial turbine rotor 10 rotates about a central axis 11 to extract mechanical work from the flow of working fluid to drive other components of the gas turbine engine. The flow of working fluid in the radial turbine rotor 10 may be radial to the central axis 11.

[0019] Temperatures of the working fluid at an inlet of radial turbines may be relatively high. To allow for relatively high temperatures of the working fluid, cooling of radial turbines, like rotor 10, may be useful so that the materials of the radial turbine can withstand the relatively high temperatures. Conventional manufacturing methods for integrally-cooled turbines incorporate integrally cast turbine blades and hub. However, these conventional manufacturing methods may not be cost effective for radial turbines. For example, if one turbine blade of the integrally cast radial turbine has a defect, the entire radial turbine may be unusable. A low casting yield in production due to potential defects may lead to increased costs.

[0020] The radial turbine rotor 10 provides passages for cooling with internal cooling features via additive layer manufacturing (ALM) as suggested in FIGS. 1-3. The hub 12 and the crown 14 are separate components that are assembled to form the radial turbine rotor 10 as suggested in FIG. 1. The multi-piece radial turbine rotor 10 allows for inspection of each component prior to assembly of the radial turbine rotor 10 so that the entire radial turbine rotor 10 may not be deemed unusable due to a defect in one component.

[0021] The hub 12 is arranged around the central axis 11 as shown in FIG. 1. As assembled, the hub 12 defines a radially-innermost surface of the radial turbine rotor 10. In the illustrative embodiment, the hub 12 includes a cylindrical portion 20 and a conical / frustoconical portion 22. The conical portion 22 of the hub 12 extends between a first end 24 and a second end 26. The first end 24 has a first diameter, and the second end 26 has a second diameter. The first diameter is smaller than the second diameter. The first end 24 of the conical portion 22 is coupled with the cylindrical portion 20 of the hub 12.

[0022] In some embodiments, the hub 12 comprises nickel superalloy, such as, but not limited to, Udimet 720. In some embodiments, the hub 12 comprises nickel powder alloy, such as, but not limited to, RR1000. In some embodiments, the hub 12 comprises polycrystalline nickel-based superalloy, such as, but not limited to, Mar-M-247. In the illustrative embodiment, the hub 12 is integrally formed as a single component via forging. Of course other suitable manufacturing techniques to form the hub 12 are also contemplated including, but not limited to, casting, machining, additive layer manufacturing, etc.

[0023] The crown 14 is manufactured via additive layer manufacturing (ALM) to enable complex geometry without some of the challenges of complex geometry metallic casting. The crown 14 includes a plurality of blades 15 that extend out from an annular flowpath ring 16 as shown in FIG. 1. The plurality of turbine blades 15 are circumferentially spaced apart from one another about the central axis 11. Notably, the blades may curve around a portion of the axis such that they overlap over certain circumferential locations while remaining spaced apart from one another at any particular location along the axis 11.

[0024] The turbine blades 15 are each formed to include a cooling air passageway 36 extending therethrough, as shown in FIG. 2. The cooling air passageway 36 is provided to cool and / or shield the turbine blade 15 that is exposed to the hot working fluid flowing through the gas path 18. Complex cooling features such as pins 38 and fins 40 are formed within the cooling air passageway. Other shapes for cooling features may also be used as desired.

[0025] A radially inwardly facing surface 28 of the flowpath ring 16 is formed to include at least one cooling air feed channel 30 as shown in FIG. 3. In the illustrative embodiment, the flowpath ring 16 is formed to include a plurality of cooling air feed channels 30 spaced apart circumferentially around the axis 11. The cooling air feed channels 30 extend radially into the flowpath ring 16.

[0026] The cooling air feed channels 30 are in fluid communication with the cooling air passageways 36 formed in the plurality of turbine blades 15 and feed cooling air to the passageways 36. Axial ends of the cooling air feed channel 30 are open to receive cooling air at a location radially inward of the plurality of turbine blades 15. In other embodiments, it is contemplated that the cooling air feed channels may be formed in a radially outer surface of the conical portion 22 of the hub 12.

[0027] In the illustrative embodiment, the crown 14 including both the turbine blades 15 and the flowpath ring 16 is made through additive layer manufacturing (ALM). The crown 14 may comprise high temperature metallic alloys, for example, Nickel-containing super alloys.

[0028] The flowpath ring 16 extends circumferentially about the central axis 11 to define a radially-inner boundary of the flowpath 18 as shown in FIG. 1. The flowpath ring 16 is located radially between the hub 12 and the plurality of turbine blades 15.

[0029] The hub 12 is fixed to the crown 14 by a bond joint or layer 54. The hub joint 54 is formed between the radially-outwardly facing surface 29 of the conical portion 22 of the hub 12 and the radially-inwardly facing surface 28 of the flowpath ring 16 included in the crown 14. In the illustrative embodiment, the hub joint 54 is a diffusion bond joint. In some embodiments, the hub joint 54 may be any other joint that fixes the hub 12 with the crown 14.

[0030] In some embodiments, shrink fitting may be used as part of the process of forming the joint 54. A material containing a suitable melting point suppressant may be applied to the radially-outwardly facing surface 29 of the hub 12 and / or the radially-inwardly facing surface 28 of the flowpath ring 16. The hub 12 and the crown 14 may be shrink fit together by sufficiently heating the crown 14 and cooling the hub 12, resulting in thermal expansion of the crown 14. After the crown 14 has expanded, the hub 12 may be inserted into it. After the hub is inserted into the crown, the assembly is heated in a vacuum furnace to a sufficient temperature to complete diffusion bonding. In certain embodiments, to join the crown 14 to the hub 12, a transient liquid phase bonding process may be used. In this case a melting point suppressant is applied to one (or both) surfaces to be joined. The bond process is “self fixtured” meaning it doesn't require the use of separate delta alpha tooling to apply a load across the bond joint. This is accomplished by shrink fitting the hub 12 and crown 14 together after application of the melting point suppressant and then heating this assembly in a vacuum furnace up to a temperature to accomplish the transient liquid phase bond.

[0031] While the disclosure has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

Claims

1. A radial turbine rotor, the rotor comprising:a hub arranged around a central axis that defines a radially-innermost surface of the rotor, anda crown having metallic layers deposited additively to provide a monolithic, single piece with a flowpath ring that extends annularly around the hub and a plurality of turbine blades that extend radially outwardly from the flowpath ring.

2. The rotor of claim 1, wherein the crown is coupled to the hub via a metalurgical bond that fixes the crown to the hub for rotation therewith.

3. The rotor of claim 2, wherein the metalurgical bond layer is a diffusion bond joint.

4. The rotor of claim 1, wherein at least one of the plurality of turbine blades is formed to include a cooling air passageway therein.

5. The rotor of claim 4, wherein complex cooling features including pins and fins are formed within the cooling air passageway.

6. The rotor of claim 4, wherein the flowpath ring is formed to include at least one cooling air feed channel that opens radially inwardly to face the central axis.

7. The rotor of claim 6, wherein the at least one cooling air feed channel is in fluid communication with the cooling air passageway formed in at least one of the plurality of turbine blades.

8. The rotor of claim 7, wherein an axial end of the at least one cooling air feed channel is open to receive cooling air at a location radially inward of the plurality of turbine blades.

9. The rotor of claim 1, wherein the crown comprises nickel superalloy materials.

10. The rotor of claim 9, wherein the hub comprises nickel superalloy materials.

11. A method of making a radial turbine rotor, the method comprising:forging a hub arranged around a central axis,forming a crown with a flowpath ring that extends annularly around the hub and a plurality of turbine blades that extend radially outwardly from the flowpath ring via additive layer manufacturing so as to provide a monolithic, single piece component, andcoupling the crown to the hub by forming a joint radially between a radially inwardly facing surface of the crown and a radially outwardly facing surface of the hub.

12. The method of claim 11, wherein the joint is a diffusion bond layer.

13. The method of claim 12, wherein the hub and the crown are shrink fit together by sufficiently heating the crown and cooling the hub, resulting in thermal expansion of the crown to enable insertion of the hub into the crown.

14. The method of claim 13, wherein after the hub is inserted into the crown, the assembly is heated in a vacuum furnace to a sufficient temperature to complete diffusion bonding.

15. The method of claim 11, wherein the crown comprises nickel superalloy materials.

16. The method of claim 15, wherein the hub comprises nickel superalloy materials.

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