Turbine components with adaptive cooling paths using two materials

Abstract

Turbine component (100) for use in a hot gas path (56) of a gas turbine (10), comprising: an outer surface (180); an internal cooling circuit (160); an adaptive cooling path (200) connected to the internal cooling circuit (160) and extending through the outer surface (180); and a cooling plug (270) positioned within the adaptive cooling path (200); wherein the cooling plug (270) comprises at least a first material (230) and a second material (240), the first material (230) having a lower melting temperature than the second material (240), and the first material (230) and the second material (240) being wound together in a swirled configuration (280).

Description

TECHNICAL AREA The present application and the resulting patent relate generally to gas turbines and in particular to gas turbines with adaptive cooling paths provided with two materials, which are filled with two or more materials with different melting points, such that at least one material can open above a predetermined temperature to provide a supplementary cooling flow through it. BACKGROUND TO THE INVENTION In general terms, a gas turbine contains a number of stages with rotor blades extending outwards from a supporting rotor disk. Each rotor blade contains an airfoil over which hot combustion gases flow. The airfoil must be cooled to withstand the high temperatures generated by the combustion gases. Insufficient cooling can result in excessive stress and oxidation of the airfoil, leading to fatigue and / or damage. The airfoil is generally hollow, with one or more internal cooling circuits leading to a number of cooling holes and the like. Cooling air is discharged through the cooling holes to create a film cooling effect on the outer surface of the airfoil. Other types of hot gas path components and other turbine components can be cooled in a similar manner. Although many models and simulations can be performed before a given component is commissioned in the field, the exact temperatures that a component or a region of it can reach can vary considerably due to component-specific hot and cold spots. In particular, the component may have temperature-dependent properties that can be adversely affected by overheating. Consequently, many turbine components may be supercooled to compensate for localized hot spots that can develop on the components. However, such excessive supercooling can negatively impact the overall power output and efficiency of the gas turbine. DE 102 50 779 A1 discloses a turbine component and a method for cooling it, wherein the turbine component has a plug positioned in an emergency cooling port and configured to melt at a specific temperature to open the emergency cooling port. The plug comprises a plug body surrounded by a protective layer. The material of the protective layer can be either platinum / platinum alloy or aluminum / aluminum alloy and therefore have a higher or lower melting point than the Ni-HF alloy material of the plug body. GB 1 381 277 A discloses a sealing device for a gas turbine engine with a bimetallic motor assembly, which in one embodiment comprises two metal rings and a number of spiral elements arranged in the space between the metal rings and connected at each end to one of the metal rings. The spiral elements and each of the metal rings are made of materials with different coefficients of thermal expansion to allow relative rotation of one of the metal rings relative to the other metal ring when heated or cooled. EP 1 584 789 A1 discloses a turbine blade with a cooling channel that is provided with a throttling point dependent on the temperature of a cooling medium. For this purpose, the throttling point has two layers surrounding the cooling wall, which are formed from different temperature-dependent materials in the manner of a bimetallic strip. DE 102 25 264 A1 discloses a bimetallic valve for opening and closing a cooling port located in the tip cover of a turbine blade. The bimetallic valve deforms due to elevated temperature without melting. In one embodiment, a plug made of a fusible material is used instead of the bimetallic valve. This plug opens the cooling port when a certain high temperature is reached. The plug consists of a single material. There is therefore a desire for improved designs for turbine blades and other types of hot gas path components. Such improved designs can manage localized hot spots with a minimized amount of additional cooling air. Furthermore, these improved designs can promote extended component lifetime without compromising the overall efficiency and power output of the gas turbine. BRIEF DESCRIPTION OF THE INVENTION To meet this requirement, a turbine component for use in a hot gas path of a gas turbine is provided according to a first aspect of the invention. The turbine component comprises an outer surface, an internal cooling circuit, an adaptive cooling path connected to the internal cooling circuit and extending through the outer surface, and a cooling plug with two or more materials positioned within the adaptive cooling path. The cooling plug has at least a first material and a second material, the first material having a lower melting point than the second material, and the first and second materials being wound together in a swirled configuration. The cooling plug can open to deliver a cooling medium through it when a locally predetermined temperature is reached. In the aforementioned turbine component, the first material of the cooling plug can at least partially surround the second material and also extend within the second material. In a preferred embodiment, the first material has a melting temperature of about 900 to about 1900 degrees Fahrenheit (about 482 to about 1038 degrees Celsius). Additionally or alternatively, the second material can have a melting temperature of approximately 1901 to approximately 2400 degrees Fahrenheit (approximately 1038 to approximately 1316 degrees Celsius). The turbine component of any of the aforementioned types may preferably have a blade. In the turbine component of any of the aforementioned types, the adaptive cooling path may have multiple adaptive cooling paths, and the cooling plug may have multiple cooling plugs. Additionally or alternatively, the turbine component may also have several cooling holes that are connected to the internal cooling circuit and extend through the outer surface. The turbine component of any of the aforementioned types may further include a cooling medium that flows through the internal cooling circuit. In one embodiment, the turbine component further comprises a supplementary volume of the cooling medium, and the supplementary volume of the cooling medium flows through the adaptive cooling path when the cooling plug is open. According to a further aspect of the invention, a method for cooling a turbine component operating in a hot gas path is also provided. The method comprises the steps of positioning an adaptive cooling path in an outer surface of the turbine component and in flow connection with an internal cooling circuit of the turbine component; positioning a cooling plug in the adaptive cooling path, wherein the cooling plug comprises at least a first material and a second material, the first material having a lower melting point than the second material, the first material and the second material being wound together in a swirled configuration; opening the cooling plug if the melting point of the first material of the cooling plug is reached or exceeded; and allowing a cooling medium to flow through the adaptive cooling path to cool at least a locally limited section of the outer surface. According to a further aspect of the invention, a hot gas path component for use in a hot gas path of a gas turbine is also provided. The hot gas path component comprises an outer surface, an internal cooling circuit, a cooling path connected to the internal cooling circuit and extending through the outer surface, an adaptive cooling path connected to the internal cooling circuit and extending through the outer surface, and a cooling plug comprising two materials arranged within the adaptive cooling path. The cooling plug comprises a first material and a second material, the first material having a lower melting point than the second material. The first and second materials are wound together in a swirled configuration.The two-material cooling plug can open to deliver a cooling medium through it when a locally limited predetermined temperature is reached. The melting point of the first material can be about 900 to about 1900 degrees Fahrenheit (about 482 to about 1038 degrees Celsius), and the melting point of the second material can be about 1901 to about 2400 degrees Fahrenheit (about 1038 to about 1316 degrees Celsius). The first material can open once its melting temperature is reached or exceeded. In the hot gas path component of any of the aforementioned types, the first material can at least partially surround the second material and also extend within the second material. These and other features and improvements of the present application and the resulting patent will be obvious to a person skilled in the art upon review of the following detailed description in conjunction with the various drawings and the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a schematic representation of a gas turbine illustrating a compressor, a combustion chamber, and a turbine. Fig. 2 shows a perspective view of an example of a known turbine component, such as a turbine blade. Fig. 3 shows a perspective view of a section of a turbine component as described herein. Fig. 4 shows a cross-sectional side view of a section of the turbine component from Fig. 3 with a two-material cooling plug within an adaptive cooling path as described herein, but not part of the claimed invention. Fig. 5 shows a cross-sectional view of the two-material cooling plug from Fig. 4. Fig. 6 shows a cross-sectional side view of a section of the turbine component from Fig. 3 with the higher-temperature-rated inner material of the open two-material cooling plug from Fig. 4.Figure 7 shows a cross-sectional side view of an embodiment of a cooling hole plug made of two materials as described herein. Figure 8 shows a cross-sectional side view of an embodiment of a cooling hole plug made of two materials as described herein, but not belonging to the claimed invention. DETAILED DESCRIPTION Referring to the drawings, in which the same reference numerals denote the same elements throughout the different views, Fig. 1 shows a schematic view of a gas turbine 10 as it may be used herein. The gas turbine 10 may include a compressor 15. The compressor 15 compresses an incoming airflow 20. The compressor 15 delivers the compressed airflow 20 to a combustion chamber 25. The combustion chamber 25 mixes the compressed airflow 20 with a pressurized fuel flow 30 and ignites the mixture to produce a flow of combustion gases 35. Although only a single combustion chamber 25 is illustrated, the gas turbine 10 may contain any number of combustion chambers 25. The flow of combustion gases 35 is in turn delivered to a turbine 40. The combustion gas flow 35 drives the turbine 40 to perform mechanical work.The mechanical work performed in the turbine 40 drives the compressor 15 via a shaft 45 and an external load 50, such as an electric generator and the like. The Gas Turbine 10 can use natural gas, liquid fuels, various types of synthesis gas, and / or other types of fuels or mixtures thereof. The Gas Turbine 10 can be any single one of a number of different gas turbines offered by the General Electric Company of Schenectady, New York, and the like. The Gas Turbine 10 can have various configurations and can use other types of components. Other types of gas turbines can also be used here. Multiple gas turbines, other turbine types, or other types of power generation equipment can also be used together here. Fig. 2 shows an example of a turbine rotor blade 55 that can be used in a hot gas path 56 of a turbine 40 and the like. Generally speaking, the turbine rotor blade 55 can include a blade 60, a shaft section 65, and a platform 70 located between the blade 60 and the shaft section 65. The blade 60 generally extends radially outward from the platform 70 and includes a leading edge 72 and a trailing edge 74. The blade 60 can further include a concave surface defining a pressure side and an opposing convex surface defining a suction side 78. The platform 70 can be substantially horizontal and planar. The shaft section 65 can extend radially inward from the platform 70 such that the platform 70 essentially defines a junction between the blade 60 and the shaft section 65.The shaft section 65 may contain a shaft cavity 80. The shaft section 65 may further include one or more angel-wing seals 82 and a root structure 84, such as a dovetail or the like. The root structure 84 may be configured to secure the turbine rotor blade 55 to the shaft 45. Any number of turbine rotor blades 55 may be arranged circumferentially around the shaft 45. Other components and configurations may also be used herein. The turbine blade 55 can include one or more cooling circuits 86 extending through it to allow a cooling medium 88, such as air, to flow from the compressor 15 or another source. Steam and other types of cooling media 88 can also be used herein. The cooling circuits 86 and the cooling medium 88 can circulate through at least sections of the blade 60, the shaft section 65, and the platform 70 in any order, direction, or distance. Many different types of cooling circuits and cooling media in any orientation can be used herein. The cooling circuits 86 can lead to a number of cooling holes 90 or other types of cooling paths for film cooling on the blade 60 or elsewhere. Other types of cooling methods can be used herein. Other components and other configurations can also be used herein. Fig. 3 shows an example of a section of a turbine component 100 as it may be described herein. In this example, the turbine component 100 may be an airfoil 110, and in particular a sidewall thereof. The airfoil 110 may be part of a rotor blade or a guide vane, and the like. The turbine component 100 may furthermore be any type of air-cooled component, including a shaft, a platform, or any type of hot gas path component. Other types of components and other configurations may be used herein. Similar to the above description, the airfoil 110 can have a leading edge 120 and a trailing edge 130. Likewise, the airfoil 110 can have a pressure side 140 and a suction side 150. The airfoil 110 can further include one or more internal cooling circuits 160. The cooling circuits 160 can lead to a number of cooling paths 170, such as a number of cooling holes 175. The cooling holes 175 can extend through an outer surface 180 of the airfoil 110 or otherwise. The cooling circuits 160 and the cooling holes 175 serve to cool the airfoil 110 and its components with a cooling medium contained therein. Any type of cooling medium, such as air, steam, and the like, from any source can be used. The cooling holes 175 can have any size, shape, or configuration.Any number of cooling holes (175) can be used here. Other types of cooling paths (170) can be used here. Other components and configurations can be used here. As illustrated in Fig. 4, which as such does not show an embodiment of the invention, the blade 110 can further include a number of adaptive cooling paths 200. In this example, the adaptive cooling path 200 can be in the form of a number of adaptive cooling holes 210. The adaptive cooling holes 210 can extend through the outer surface 180 in a similar manner to the cooling holes 175. The adaptive cooling holes 210 can also be connected to one or more of the cooling circuits 160. The adaptive cooling holes 210 can be filled with a two-material cooling plug 220. As illustrated in Figs. 4 and 5, the two-material cooling plug 220 can contain two or more materials with different melting points to fill and plug the cooling holes 210.Although the cooling plug 220 can use two different materials, any two different materials can be used. Furthermore, the two or more materials retain their respective properties; that is, no alloy or the like is created. Rather, an alloy can form one or more of the two or more materials used. In particular, the cooling plug 220 may contain two materials: an outer material 230 for lower temperature and an inner material 240 for higher temperature. The terms "lower" and "higher" are used herein in their relative sense. Materials with any melting or opening / dissolving temperatures may be used herein. The outer material 230 for lower temperature may be a low-temperature brazing material and the like. As an example, at a lower predetermined temperature 250, the outer material 230 for lower temperature may soften and melt, turn to ash, or otherwise oxidize and / or change volumetrically in a manner similar to glass. In this example, the lower predetermined temperature may be about 900 to about 1900 degrees Fahrenheit (about 482 to about 1038 degrees Celsius). Other predetermined temperatures may be used herein.Examples of the outer material 230 for lower temperatures include AMS 4764 and other types of copper-based brazing alloys. Such a material can have a solidus-liquidus temperature of approximately 1600 to 1700 degrees Fahrenheit (approximately 871 to 927 degrees Celsius). Other types of materials may be used here. The higher-temperature inner material 240 may contain a high predetermined temperature 260. In this example, the high predetermined temperature may be approximately 1901 to approximately 2400 degrees Fahrenheit (approximately 1038 to approximately 1316 degrees Celsius). Other high predetermined temperatures 260 may be used herein. The higher-temperature inner material 240 may be a high-temperature brazing material and the like. Examples of the higher-temperature inner material 240 may include AMS 4779 and other types of nickel alloy-based brazing alloys. Such a material may have a solidus liquidus temperature of approximately 1800 to approximately 1900 degrees Fahrenheit (approximately 982 to approximately 1038 degrees Celsius) (although melting may occur above these temperatures). Other types of materials may be used herein. In operation, the cooling holes 170, 210 can be drilled into the turbine component 100 or inserted in some other way. The turbine component 100 can be coated with a conventional thermal insulation coating or the like. The adaptive cooling holes 210 can be filled with cooling plugs 220 containing two materials. In particular, the outer material 230 of the cooling plug 220, intended for lower temperatures, can be connected to the cooling hole 210, with the inner material 240, intended for higher temperatures, located within it. If the surface temperature of any region of the turbine component 100 reaches or exceeds the design temperature of, for example, a hot spot, the lower-temperature outer material 230 of the bi-material cooling plug 220 may melt, burn, or otherwise rupture (disintegrate) once the lower predetermined temperature 250 is reached or exceeded. Once the integrity of the lower-temperature outer material 230 is compromised, higher pressures within the turbine component 100 may displace the remaining higher-temperature inner material 240 from the cooling hole 210. The removal of the bi-material cooling plug 220 thus opens the adaptive cooling hole 210 and provides a cooling device in a region requiring such cooling flow. Fig. 6 shows the adaptive cooling hole 210 from Fig. 4 once the bi-material cooling plug 220 has ruptured or opened.Only a thin layer of the outer material 230 can remain for lower temperatures. Once the cooling plug 220 containing the two materials has dissolved or been opened, the additional volume of the cooling medium can be used to cool component 100. Such an additional volume of cooling medium can mitigate localized problems such as fragmentation and oxidation, or other harmful high-temperature effects. The two-material cooling plug 220 thus enables additional cooling if the localized surface temperature of the turbine component 100 exceeds the design temperature, for example, where a hot spot occurs. Likewise, the two-material cooling plug 220 can serve as a failsafe for the overall design. The two-material cooling plug 220 achieves additional cooling precisely where it is needed, unlike approaches based on predictive models or simulations. Rather, this cooling strategy adapts to the actual operating conditions of the gas turbine 10 and the specific turbine component 100. Consequently, testing of the entire machine can be reduced.Because the dual-material cooling plugs 220 can only open when the local temperature reaches the point where cooling air is required, the dual-material cooling plug 220 provides a passively adaptive or "self-healing" thermal design. If predicted hot spots are indeed hot, the dual-material cooling plugs 220 can open. If not, the dual-material cooling plugs 220 can remain closed. Given this, lower cooling flows can be provided at higher ignition temperatures with reduced component risk and / or fewer failures. The overall amount of cooling flow can therefore be reduced. Furthermore, the dual-material cooling plug 220 can offer advantages over single-material plugs in that single-material plugs tend to develop pinhead-sized leaks in their center, thus preventing the desired amount of cooling flow from passing through them. Fig. 7 shows an alternative embodiment of a cooling plug 270 with two materials, as described herein. In this example, instead of the outer lower-temperature material 230 merely surrounding the inner higher-temperature material 240, the respective materials 230 and 240 are wound into a swirled configuration 280. The outer (first) lower-temperature material 230 can, in turn, be connected to the cooling hole 210 and can melt, dissolve, or open when the low predetermined temperature 250 is reached or exceeded. The outer (first) lower-temperature material 230 also extends within the inner (second) higher-temperature material 240 to assist in the elimination of the inner higher-temperature material 240 with respect to high internal pressures. Other components and configurations may be used herein. The adaptive cooling paths 200 also enable minimized use of the cooling medium. Specifically, the adaptive cooling paths 200 can be opened for the additional volume 195 of cooling medium only when the turbine component 100, or a portion thereof, reaches the predetermined low temperature. In itself, the adaptive cooling paths 200 can lead to a reduction in design time and a decrease in field variation. The overall service life of the turbine component 100 should also be increased. In particular, the number of operating cycles for the component 100 can be extended. Likewise, the amount of cooling medium 190 can be reduced, as the required adaptive cooling paths 200 can be opened for the additional volume 195 of cooling medium 190. Furthermore, given the absence of overheating concerns, new cooling strategies can be implemented. Fig. 8 shows another embodiment of a two-material cooling plug 290, not belonging to the claimed invention, as may be described herein. In this example, instead of the outer material 230 for the lower temperature surrounding the inner material 240 for the higher temperature, the position of the respective materials 230 and 240 can be reversed. Accordingly, the two-material cooling plug 290 can have an outer material 300 for the higher temperature surrounding an inner material 310 for the lower temperature. The inner material 310 for the lower temperature can melt or otherwise dissolve or open when the lower predetermined temperature 250 is reached or exceeded. A loss of the inner material 310 for the lower temperature can thus create a cooling hole with a variable diameter based on the local temperature and other parameters.The diameter of the cooling holes can vary. The dual-material cooling plug 290 thus provides increased durability in place (i.e., cold melting inside) and the complete elimination of the plug (i.e., cold melting outside). Other components and configurations can be used here. It should be obvious that the foregoing relates only to certain embodiments of the present application and the resulting patent. Numerous changes and modifications can be made therein by a person skilled in the art without departing from the general scope of the invention as defined by the following claims. The present application thus provides a turbine component for use in a hot gas path of a gas turbine. The turbine component can comprise an outer surface, an internal cooling circuit, an adaptive cooling path connected to the internal cooling circuit and extending through the outer surface, and a cooling plug with two or more materials positioned within the adaptive cooling path. Parts list: 10 Gas turbine 15 Compressor 20 Air 25 Combustion chamber 30 Fuel 35 Combustion gases 40 Turbine 45 Shaft 50 Load 55 Rotor blade 56 Hot gas path 60 Blade 65 Stem 70 Platform 72 Leading edge 74 Trailing edge 76 Pressure side 78 Suction side 80 Stem cavity 82 Angel blade seals 84 Root structure 86 Cooling circuits 88 Cooling medium 90 Cooling holes 100 Turbine component 110 Blade 120 Leading edge 130 Trailing edge 140 Pressure side 150 Suction side 160 Cooling circuits 170 Cooling holes 175 Cooling paths 180 Outer surface 200 Adaptive cooling paths 210 Passive cooling holes 220 Dual-material cooling plugs 230 Outer / first material for low temperature 240 Inner / second material for higher temperature 250 Low predetermined temperature 260 High predetermined temperature 270 Dual-material cooling plug 280 Swirled configuration 290 Dual-material cooling plug 300 Outer material for higher temperature 310 Inner material for lower temperature

Claims

Turbine component (100) for use in a hot gas path (56) of a gas turbine (10), comprising: an outer surface (180); an internal cooling circuit (160); an adaptive cooling path (200) connected to the internal cooling circuit (160) and extending through the outer surface (180); and a cooling plug (270) positioned within the adaptive cooling path (200); wherein the cooling plug (270) comprises at least a first material (230) and a second material (240), the first material (230) having a lower melting temperature than the second material (240), and the first material (230) and the second material (240) being wound together in a swirled configuration (280). Turbine component (100) according to claim 1, wherein the first material (230) at least partially surrounds the second material (240) and also extends within the second material (240). Turbine component (100) according to claim 2, wherein the first material (230) has a melting temperature of about 482 to about 1038 degrees Celsius and the second material (240) has a melting temperature of about 1038 to about 1316 degrees Celsius. Turbine component (100) according to any one of the preceding claims, wherein the adaptive cooling path (200) has multiple adaptive cooling paths (200) and wherein the cooling plug (270) has multiple cooling plugs (270). Turbine component (100) according to any one of the preceding claims, further comprising several cooling holes (210) which are connected to the internal cooling circuit (160) and extend through the outer surface (180). Turbine component (100) according to any one of the preceding claims, further comprising a cooling medium flowing through the internal cooling circuit (160). Turbine component (100) according to any one of the preceding claims, further comprising a supplementary volume of the cooling medium, wherein the supplementary volume of the cooling medium flows through the adaptive cooling path (200) as soon as the cooling plug (270) is opened. A method for cooling a turbine component (100) operating in a hot gas path (56) comprising: positioning an adaptive cooling path (200) in an outer surface (180) of the turbine component (100) and in flow connection with an internal cooling circuit (160) of the turbine component (100); positioning a cooling plug (270) in the adaptive cooling path (200), wherein the cooling plug (270) comprises at least a first material (230) and a second material (240), the first material (230) having a lower melting point than the second material (240), and the first material (230) and the second material (240) being wound together in a swirled configuration (280); opening the cooling plug (270) when the melting point of the first material (230) of the cooling plug (270) is reached or exceeded; and flowing a cooling medium through the adaptive cooling path (200) to cool a locally limited section of the outer surface (180). Hot gas path component for use in a hot gas path (56) of a gas turbine (10), comprising: an outer surface (180); an internal cooling circuit (160); a cooling path (175) connected to the internal cooling circuit (160) and extending through the outer surface (180); an adaptive cooling path (200) connected to the internal cooling circuit (160) and extending through the outer surface (180); and a cooling plug (270) with two materials, which is positioned inside the adaptive cooling pad (200); wherein the cooling plug (270) with two materials has a first material (230) and a second material (240), wherein the first material (230) has a lower melting temperature than the second material (240), wherein the first material (230) and the second material (240) are wound together in a swirled configuration (280).

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