METHOD OF MAKING SURFACE COOLING CHANNELS ON A COMPONENT USING LITHOGRAPHIC MOLDING TECHNIQUES
Methods of casting a component including one or more surface cooling channels. The method including casting a ceramic core into a flexible mold of a core section and casting a ceramic shell in at least two sections into respective flexible molds of a first shell section and a second shell section. A ceramic casting vessel is subsequently formed by assembling the ceramic core within the ceramic shell sections. A metal substrate material is cast into the ceramic casting vessel. Removal of the ceramic casting vessel reveals a substrate of the component having defined therein the interior passageway, the one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages.
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The subject matter disclosed herein relates generally to turbine systems, such as gas turbine systems, and more particularly to micro-channel cooling therein.
In gas turbine engines, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases. Energy is extracted from the gases in a high pressure turbine (HPT), which powers the compressor, and in a low pressure turbine (LPT), which powers a fan in a turbofan aircraft engine application, or powers an external shaft for marine and industrial applications.
During operation of gas turbine engines, the temperatures of combustion gases may exceed 3,000° F., considerably higher than the melting temperatures of the metal parts of the engine which are in contact with these gases. Operation of these engines at gas temperatures that are above the metal part melting temperatures is a well-established art, and depends in part on supplying a cooling air to the outer surfaces of the metal parts through various methods. The metal parts of these engines that are particularly subject to high temperatures, and thus require particular attention with respect to cooling, are the metal parts forming combustors and parts located aft of the combustor.
Engine efficiency increases with temperature of combustion gases. However, the combustion gases heat the various components along their flow path, which in turn requires cooling thereof to achieve a long engine lifetime. Typically, the hot gas path components are cooled by bleeding air from the compressor. This cooling process reduces engine efficiency, as the bled air is not used in the combustion process.
Gas turbine engine cooling art is mature and includes numerous patents for various aspects of cooling circuits and features in the various hot gas path components. For example, the combustor includes radially outer and inner liners, which require cooling during operation. Turbine nozzles include hollow vanes supported between outer and inner bands, which also require cooling. Turbine rotor blades are hollow and typically include cooling circuits therein, with the blades being surrounded by turbine shrouds, which also require cooling. The hot combustion gases are discharged through an exhaust which may also be lined, and suitably cooled.
In all of these exemplary gas turbine engines components, thin metal walls of high strength superalloy metals are typically used for enhanced durability while minimizing the need for cooling thereof. Various cooling circuits and features are tailored for these individual components in their corresponding environments in the engine. For example, a series of internal cooling passages, or serpentines, may be formed in a hot gas path component. A cooling fluid may be provided to the serpentines from a plenum, and the cooling fluid may flow through the passages, cooling the hot gas path component substrate and coatings. However, this cooling strategy typically results in comparatively low heat transfer rates and non-uniform component temperature profiles.
Employing micro-channel cooling techniques has the potential to significantly reduce cooling requirements. Micro-channel cooling places the cooling as close as possible to the heat zone, thus reducing the temperature difference between the hot side and cold side of the load bearing substrate material for a given heat transfer rate. However, current techniques for forming micro-channels typically require the use of post-casting machining to form the micro-channels and coolant feed holes. Post-casting machining involves potentially damaging processes and typically requires long times.
It would therefore be desirable to provide a method for forming cooling channels in hot gas path components that eliminates the need for the post-casting machining
BRIEF DESCRIPTIONIn one embodiment, a method of casting a component including one or more surface cooling channels is disclosed. The method includes casting a ceramic core from a flexible mold of one or more core sections and casting a ceramic shell in at least two sections into respective flexible molds of a first shell section and a second shell section. Next, a ceramic casting vessel is formed by assembling the ceramic core within the ceramic shell sections. A metal substrate material is cast into the ceramic casting vessel. Subsequently, the ceramic casting vessel is removed. Removal of the ceramic casting vessel reveals a substrate of the component having defined therein an interior passageway, one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages.
In another embodiment, a method of casting a component including one or more surface cooling channels is disclosed. The method includes providing a model of a desired ceramic casting vessel defining a geometry of the component and including an interior passageway, one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages. The model is digitally divided into a plurality of sections and each of the plurality of sections is translated into a master tool wherein the plurality of sections include a one or more precision metal inserts to define the geometry of the component including the interior passageway, the one or more cooling passages and the one or more surface grooves and one or more alignment features. A flexible mold is next cast from each master tool. A ceramic core is cast from a respective flexible mold. A ceramic shell is cast in at least two sections from a respective flexible mold. A ceramic casting vessel is formed by assembling the ceramic core within the ceramic shell sections. Next, a metal is cast into the ceramic casting vessel. The ceramic casting vessel is subsequently removed to reveal a substrate of the component having the interior passageway, the one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages.
In yet another embodiment, a method of casting a component including one or more surface cooling channels is disclosed. The method includes providing a model of a desired ceramic casting vessel defining a geometry of the component and including an interior passageway, one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages and digitally dividing the model into a plurality of sections. The plurality of sections defines one or more core sections and at least two shell sections. Each of the plurality of sections is next translated into a master tool. One or more precision metal inserts is disposed into one or more of the plurality of sections to define the geometry of the component including the interior passageway, the one or more cooling passages, the one or more surface grooves and one or more alignment features. Next, a flexible mold if cast from each master tool. The respective flexible molds are assembled to define a cavity therebetween. A ceramic core is cast from a respective flexible mold and a ceramic shell in at least two sections is casts from a respective flexible mold. A ceramic casting vessel is formed by assembling the ceramic core within the ceramic shell sections utilizing the one or more alignment features. A metal is then cast into the ceramic casting vessel. Subsequent removal of the ceramic casting vessel reveals a substrate of the component having the interior passageway, the one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages. Finally, a coating is disposed over at least a portion of a surface of the substrate, wherein the one or more surface grooves and the coating define the one or more surface cooling channels for cooling the component.
These and additional features provided by the embodiments discussed herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the embodiments defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present disclosure, the components “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
Disclosed is a method of manufacturing surface cooling channels in a high-performance product, such an airfoil, made from metals, ceramics, polymers and/or composite material systems. The method enables the manufacture of an airfoil design with improved cooling characteristics that eliminates the need for the post-casting machining of the surface cooling channels. In an embodiment, coolant exit features may be placed in the applied coating after deposition of the coating, or the surface cooling channels may be oriented to exit off the edges of the part.
The method of manufacture utilizes a novel molding or casting process based on the use of lithography and lithographic machining techniques to create a three-dimensional model of the finished airfoil. The method will be described in more detail herein.
The gas turbine system 10 may include a number of hot gas path components. A hot gas path component is any component of the system 10 that is at least partially exposed to a high temperature flow of gas through the system 10. For example, bucket assemblies (also known as blades or blade assemblies), nozzle assemblies (also known as vanes or vane assemblies), shroud assemblies, transition pieces, retaining rings, and compressor exhaust components are all hot gas path components. However, it should be understood that the hot gas path component of the present disclosure is not limited to the above examples, but may be any component that is at least partially exposed to a high temperature flow of gas. Further, it should be understood that the hot gas path component of the present disclosure is not limited to components in gas turbine systems 10, but may be any piece of machinery or component thereof that may be exposed to high temperature flows.
When a hot gas path component is exposed to a hot gas flow, the hot gas path component is heated by the hot gas flow and may reach a temperature at which the hot gas path component fails. Thus, in order to allow system 10 to operate with hot gas flow at a high temperature, increasing the efficiency and performance of the system 10, a cooling system for the hot gas path component is required.
In general, the cooling system of the present disclosure includes a series of small cooling channels, or microchannels, formed in the surface of the hot gas path component. The hot gas path component may include one or more grooves and a coating to bridge there over the grooves, and form the micro-channels. A cooling fluid may be provided to the micro-channels from a plenum, and the cooling fluid may flow through the micro-channels, cooling the coating and the substrate.
Referring now to
As described below, the method disclosed herein includes lithography and lithographic machining techniques to create a three-dimensional model of the finished component, and more particularly the airfoil, including a plurality of surface cooling channels. Initially, a digital model of a component, such as an airfoil, is formed using a computerized design system, the use of which is well known in the art. The digital model is thereafter divided into a plurality of parts for castings. The plurality of castings are ultimately assembled into a casting vessel into which an alloy is cast. Ultimate removal of the casting vessel reveals a coolable structure having an interior passageway and one or more cooling passages in fluidic communication with the interior passageway and one or more open surface cooling channels. The method results in a component that requires no post casting machining to form the open surface cooling channels.
As previously indicated, an exemplary embodiment fabricated according to the method disclosed herein is the fabrication of a gas turbine airfoil, including an interior hollow passageway in fluidic communication with a plurality of surface cooling channels.
Referring more particularly to
As indicated, the method provides for forming (as best illustrated in
Referring now to
Referring now to
As best illustrated in
Referring now to
In addition to fabrication of the ceramic core 52, the ceramic casting vessel 56 further includes the ceramic shell 54. Accordingly, the ceramic shell 54 is next cast in at least two sections 62 and 64 which are then joined together and in combination with the ceramic core 52 enable fabrication of the component 30 including one or more surface grooves 44. As previously detailed, in a preferred embodiment of fabrication an airfoil, such as airfoil 30 of
Referring now to
A flexible mold is next fabricated for each master tool 90 and 92. More specifically, as illustrated in
Next, as best illustrated in
Referring now to
The ceramic casting vessel 56 subsequently receives a molten metal 110 into the ceramic casting vessel 56, and more particularly into the cavities 112 defined therein, using well known processes known in the art, to form the cast gas turbine blade 30 including a plurality of surface grooves 44. In a preferred embodiment, the molten metal 110, as discussed in U.S. Pat. No. 5,626,462, Melvin R. Jackson et al., “Double-wall airfoil,” which is incorporated herein in its entirety, may include any suitable metal material. Depending on the intended application for component 30, this could include Ni-base, Co-base and Fe-base superalloys. The Ni-base superalloys may be those containing both γ and γ′ phases, particularly those Ni-base superalloys containing both γ and γ′ phases wherein the γ′ phase occupies at least 40% by volume of the superalloy. Such alloys are known to be advantageous because of a combination of desirable properties including high temperature strength and high temperature creep resistance. The metal material 110 may also comprise a NiAl intermetallic alloy, as these alloys are also known to possess a combination of superior properties including high-temperature strength and high temperature creep resistance that are advantageous for use in turbine engine applications used for aircraft. In the case of Nb-base alloys, coated Nb-base alloys having superior oxidation resistance will be preferred, particularly those alloys comprising Nb-(27-40)Ti-(4.5-10.5)Al-(4.5-7.9)Cr-(1.5-5.5)Hf-(0-6)V, where the composition ranges are in atom percent. The metal material may also comprise a Nb-base alloy that contains at least one secondary phase, such as a Nb-containing intermetallic compound comprising a silicide, carbide or boride. Such alloys are composites of a ductile phase (i.e., the Nb-base alloy) and a strengthening phase (i.e., a Nb-containing intermetallic compound). For other arrangements, the metal material comprises a molybdenum based alloy, such as alloys based on molybdenum (solid solution) with Mo5SiB2 and/or Mo3Si second phases. For other configurations, the metal material comprises a ceramic matrix composite (CMC), such as a silicon carbide (SiC) matrix reinforced with SiC fibers. For other configurations the metal material comprises a TiAl-based intermetallic compound.
The ceramic casting vessel 56 is next removed to reveal the component 30 having the interior passageway 38, the one or more cooling passages 41 in fluidic communication with the interior passageway 38 and one or more surface grooves 44 in fluidic communication with the one or more cooling passages 41, a portion of which is illustrated in
Beneficially, by forming re-entrant grooves 44, it is not necessary to use a sacrificial filler (not shown) to apply coating 42 to the substrate 32. This eliminates the need for a filling process and for the more difficult removal process. By forming reentrant shaped grooves with narrow openings 48 (tops), for example with openings 48 in the range of about 10-12 mils wide, the openings 48 can be bridged by the coating 42 without the use of a sacrificial filler, thereby eliminating additional processing steps (filling and leaching) beyond the eliminated post-machining step previously described, for conventional channel forming techniques. For the example configuration illustrated in
Referring now to
While the disclosed method has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosed method is not limited to such disclosed embodiments. Rather, the method can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the method have been described, it is to be understood that aspects of the method may include only some of the described embodiments. Accordingly, the disclosed method is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Claims
1. A method of casting a component including one or more surface cooling channels, the method comprising:
- casting a ceramic core from a flexible mold of one or more core sections;
- casting a ceramic shell in at least two sections into respective flexible molds of at least two shell sections;
- forming a ceramic casting vessel by assembling the ceramic core within the ceramic shell sections;
- casting a metal substrate material into the ceramic casting vessel; and
- removing the ceramic casting vessel to reveal a substrate of the component having defined therein an interior passageway, one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages.
2. The method of claim 1, further comprising:
- providing a model of a desired ceramic casting vessel defining a geometry of the component and including the interior passageway, the one or more cooling passages in fluidic communication with the interior passageway and the one or more surface grooves in fluidic communication with the one or more cooling passages;
- digitally dividing the model into a plurality of sections defining the core section, the first shell section and the second shell section;
- translating each of the plurality of sections into a master tool wherein the plurality of sections include a one or more precision metal inserts to define the geometry of the component including the interior passageway, the one or more cooling passages and the one or more surface grooves; and
- casting the flexible molds from each master tool.
3. The method of claim 1, further including disposing a coating over at least a portion of a surface of the substrate, wherein the one or more cooling passages, the one or more surface grooves and the coating define the one or more surface cooling channels for cooling the component.
4. The method of claim 1, further including defining at least one coolant exit through the coating.
5. The method of claim 1, wherein the one or more surface grooves are re-entrant shaped grooves.
6. A method of casting a component including one or more surface cooling channels, the method comprising:
- providing a model of a desired ceramic casting vessel defining a geometry of the component and including an interior passageway, one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages;
- digitally dividing the model into a plurality of sections;
- translating each of the plurality of sections into a master tool wherein the plurality of sections include a one or more precision metal inserts to define the geometry of the component including the interior passageway, the one or more cooling passages, the one or more surface grooves and one or more alignment features;
- casting a flexible mold from each master tool;
- casting a ceramic core from a respective flexible mold;
- casting a ceramic shell in at least two sections from a respective flexible mold;
- forming the ceramic casting vessel by assembling the ceramic core within the ceramic shell sections;
- casting a metal into the ceramic casting vessel; and
- removing the ceramic casting vessel to reveal a substrate of the component having the interior passageway, the one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages.
7. The method of claim 6, further including disposing a coating over at least a portion of a surface of the substrate, wherein the one or more surface grooves and the coating define the one or more surface cooling channels for cooling the component.
8. The method of claim 7, wherein the coating completely bridges the respective one or more surface grooves such that the coating seals the respective one or more surface cooling channels.
9. The method of claim 6, wherein the one or more surface grooves are re-entrant shaped grooves.
10. The method of claim 6, wherein each of the master tools is formed of a metal material.
11. The method of claim 10, wherein the metal material is aluminum.
12. The method of claim 6, wherein the plurality of sections define one or more core sections and at least two shell sections.
13. The method of claim 6, wherein the precision inserts are formed of a metal material.
14. The method of claim 13, wherein the metal material is etched copper.
15. The method of claim 6, wherein the one or more precision metal inserts further define one or more alignment features and wherein forming the ceramic casting vessel by assembling the ceramic core within the ceramic shell sections further includes utilizing the one or more alignment features.
16. A method of casting a component including one or more surface cooling channels, the method comprising:
- providing a model of a desired ceramic casting vessel defining a geometry of the component and including an interior passageway, one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages;
- digitally dividing the model into a plurality of sections, wherein the plurality of sections define one or more core sections and at least two shell sections;
- translating each of the plurality of sections into a master tool and disposing one or more precision metal inserts into one or more of the plurality of sections to define the geometry of the component including the interior passageway, the one or more cooling passages, the one or more surface grooves and one or more alignment features;
- casting a flexible mold from each master tool;
- assembling the respective flexible molds to define a cavity therebetween;
- casting a ceramic core from a respective flexible mold;
- casting a ceramic shell in at least two sections from a respective flexible mold;
- forming the ceramic casting vessel by assembling the ceramic core within the ceramic shell sections utilizing the one or more alignment features;
- casting a metal into the ceramic casting vessel;
- removing the ceramic casting vessel to reveal a substrate of the component having the interior passageway, the one or more cooling passages in fluidic communication with the interior passageway and one or more surface grooves in fluidic communication with the one or more cooling passages; and
- disposing a coating over at least a portion of a surface of the substrate, wherein the one or more surface grooves and the coating define the one or more surface cooling channels for cooling the component.
17. The method of claim 16, wherein the coating completely bridges the respective one or more surface grooves such that the coating seals the respective one or more surface cooling channels.
18. The method of claim 16, wherein the one or more surface grooves are re-entrant shaped grooves.
19. The method of claim 16, wherein each of the master tools is formed of aluminum.
20. The method of claim 16, wherein the precision inserts are formed of an etched copper.
Type: Application
Filed: Oct 12, 2012
Publication Date: Jul 23, 2015
Applicant: GENERAL ELECTRIC COMPANY (Schenectady, NY)
Inventor: GENERAL ELECTRIC COMPANY
Application Number: 13/650,320