Patent Application
20100242484
This application relates generally to gas turbine engines and, more particularly, to combustors for gas turbine engines.
At least some known combustors include at least one mixer assembly coupled to a combustor liner that defines a combustion zone. Fuel injectors are coupled to the combustor in flow communication with the mixer assembly for supplying fuel to the combustion zone. Specifically, in such designs, fuel enters the combustor through the mixer assembly. The mixer assembly is coupled to the combustor liner by a dome plate or a spectacle plate.
At least some known mixer assemblies include a flare cone. Generally, the flare cone is divergent and extends radially outward from a centerline axis of the combustor to facilitate mixing the air and fuel, and to facilitate spreading the mixture radially outwardly into the combustion zone. A divergent deflector extends circumferentially around and radially outward from the flare cone. The deflector, sometimes referred to as a splash plate, facilitates preventing hot combustion gases produced within the combustion zone from impinging upon the dome plate.
During operation, fuel discharged to the combustion zone may form a fuel-air mixture along the flare cone and the deflector. This fuel-air mixture may combust resulting in high gas temperatures. Prolonged exposure to the increased temperatures may increase a rate of oxidation formation on the flare cone, and may result in deformation of the flare cone and the deflector.
To facilitate reducing operating temperatures of the flare cone and the deflector, at least some known combustor mixer assemblies supply convective cooling air via air injectors defined within the flare cone. Specifically, in such combustors, the cooling air is supplied into a gap extending circumferentially around the combustor centerline axis between the flare cone and the deflector.
Such cooled deflector assemblies are formed of separate flare cones and deflectors, which are subsequently coupled together, for example, by brazing to form a unitary assembly having the flare cone integral with the deflector. However, forming the deflector and flare cone separately increases the combustor part count and coupling the deflector and flare cone together is labor intensive and prone to possible manufacturing tolerance errors.
In one embodiment, a deflector-flare cone for a combustor includes a single annular body including an engagement end configured to support the deflector-flare cone, an annular divergent portion extending downstream from the engagement end. The annular divergent portion includes a radially outer annular deflector portion and a radially inner annular flare cone portion that are separated by an annular gap extending between the deflector portion and the flare cone portion. The deflector-flare cone includes a plurality of cooling passages extending through the single annular body of the deflector-flare cone. The plurality of cooling passages are spaced circumferentially about the centerline axis and are configured to be coupled in flow communication with a cooling fluid source.
In another embodiment, a method of forming a deflector-flare cone includes forming a deflector-flare cone blank from a single piece of material, forming a circumferential groove in a downstream end of said deflector-flare cone blank forming a radially outer divergent deflector portion and a radially inner divergent flare cone portion separated by said gap, and forming a plurality of cooling passages spaced circumferentially about said deflector-flare cone from an upstream end to said gap.
In yet another embodiment, a gas turbine engine includes a compressor configured to transmit compressed air, and a combustor coupled in flow communication with the compressor. The combustor includes a single-piece deflector-flare cone wherein the deflector-flare cone includes a deflector portion and a flare cone portion separated from the deflector portion by a groove machined into a downstream end of the deflector-flare cone. The deflector-flare cone comprises a plurality of cooling passages extending through the deflector-flare cone from an upstream end supplied with compressed air by the compressor to the groove. The plurality of cooling passages are spaced circumferentially about a centerline axis of the deflector-flare cone.
This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
In operation, air enters engine 100 through intake 118 and is channeled through fan assembly 102 into booster 103. Compressed air is discharged from booster 103 into high-pressure compressor 104. Highly compressed air is channeled from compressor 104 to combustor 106 where fuel is mixed with air and the mixture is combusted within combustor 106. High temperature combustion gases generated are channeled to turbines 108 and 110. Turbine 108 drives compressor 104, and turbine 110 drives fan assembly 102 and booster 103. Combustion gases are subsequently discharged from engine 100 via exhaust 120.
Combustion chamber 208 is generally annular in shape and is disposed between liners 202 and 204. Outer and inner liners 202 and 204 extend to a turbine nozzle 210 disposed downstream from combustor domed end 206.
In the exemplary embodiment, combustor domed end 206 includes an annular dome assembly 212 arranged in a single annular configuration. In another embodiment, combustor domed end 206 includes a dome assembly 212 arranged in a double annular configuration. In a further embodiment, combustor domed end 206 includes a dome assembly 212 arranged in a triple annular configuration. Combustor dome assembly includes a dome plate or spectacle plate 216 and a deflector-flare cone 218. Deflector-flare cone 218 is a single one-piece member that is machined to include a radially divergent deflector portion 220 and a radially divergent flare cone portion 222. In the exemplary embodiment, deflector-flare cone 218 is fabricated in a single piece using a casting process and then machined to form the features of deflector portion 220 and flare cone portion 222. In an alternative embodiment, deflector-flare cone 218 is fabricated in a single piece using a forging process and then machined to form the features of deflector portion 220 and flare cone portion 222. In another alternative embodiment, deflector-flare cone 218 is fabricated in a single piece using another process that provides a one-piece blank that includes extra material outside final dimensional tolerances and then machined to form the features of deflector portion 220 and flare cone portion 222.
Combustor 106 is supplied fuel via a fuel injector 224 connected to a fuel source (not shown) and extending through combustor domed end 206. More specifically, fuel injector 224 extends through dome assembly 212 and discharges fuel in a direction (not shown) that is substantially concentric with respect to a combustor center longitudinal axis of symmetry 226. Combustor 106 also includes a fuel igniter 228 that extends into combustor 106 downstream from fuel injector 224.
Combustor 106 also includes an annular air swirler 230 having an annular exit 232 that extends substantially symmetrically about combustor center longitudinal axis of symmetry 226. Exit 232 includes mating surface 234 configured to engage a complementary engagement end 236 of deflector-flare cone 218. Deflector-flare cone 218 couples to exit 232 using mating surface 234 and extends downstream from exit 232. Flare cone portion 222 includes a radially inner flow surface 238 and a radially outer surface 240. An inner surface 242 of deflector-flare cone 218 extends downstream from engagement end 236 to an elbow 244, before extending divergently outward from elbow 244 to a trailing end 246 of flare cone portion 222.
Deflector portion 220 includes a radially inner flow surface 248 and a radially outer surface 250. Deflector portion 220 extends downstream from engagement end 236 and divergently outward to a trailing end 252 of deflector portion 220.
A gap 254 is formed between deflector portion 220 and flare cone portion 222 using a machining process during fabrication of deflector-flare cone 218. Gap 254 provides an annular space having a width D1 for directing cooling fluid about outer surface 240 and radially inner flow surface 248.
A plurality of circumferentially spaced cooling passages 256 are formed through deflector-flare cone 218. Specifically, cooling passages 256 extend substantially axially through deflector-flare cone 218 in a direction that is substantially parallel to a combustor center longitudinal axis of symmetry 226. In an alternative embodiment, cooling passages 256 are oriented non-parallel with respect to combustor center longitudinal axis of symmetry 226. Additionally, in various embodiments, cooling passages 256 are spaced non-uniformly around combustor center longitudinal axis of symmetry 226 to provide a variable amount of cooling to various areas of deflector portion 220 and/or flare cone portion 222. Cooling passages 256 discharge cooling air therethrough at a reduced pressure for cooling of deflector-flare cone 218. In one embodiment, the cooling air is compressor air. In the exemplary embodiment, cooling passages 256 are formed using an electro-discharge machining (EDM) process.
During operation, cooling air is supplied to deflector-flare cone 218 through cooling passages 256. Cooling passages 256 facilitate providing a continuous flow of cooling air to be discharged at a reduced air pressure for impingement cooling of flare cone portion 222. The reduced air pressure facilitates improved cooling and backflow margin for the impingement cooling of flare cone portion 222. Furthermore, the cooling air enhances convective heat transfer and facilitates reducing an operating temperature of flare cone portion 222, which facilitates extending a useful life of flare cone portion 222, while reducing a rate of oxidation formation of flare cone portion 222.
Furthermore, as cooling air is discharged through cooling passages 256, deflector divergent portion 220 is film cooled. More specifically, cooling passages 256 supply deflector divergent portion inner surface 248 with film cooling. Because cooling passages 256 are spaced circumferentially through deflector-flare cone 218, film cooling is directed along deflector inner surface 248 substantially circumferentially around flare cone portion 222. In addition, because cooling passages 256 facilitate substantially uniform cooling flow, deflector-flare cone 218 facilitates optimizing film cooling while reducing mixing of the cooling air with combustion air, which thereby facilitates reducing an adverse effect of flare cooling on combustor emissions.
During operation, cooling air is supplied to deflector-flare cone 218 through cooling passages 256. Cooling passages 256 facilitate providing a continuous flow of cooling air to be discharged at a reduced air pressure for impingement cooling of flare cone portion 222. Furthermore, the cooling air enhances convective heat transfer and facilitates reducing an operating temperature of flare cone portion 222, which facilitates extending a useful life of flare cone portion 222, while reducing a rate of oxidation formation of flare cone portion 222.
The methods and apparatuses for a combustor described herein facilitate operation of a gas turbine. More specifically, the single-piece combustor deflector-flare cone as described above facilitates an efficient and effective combustor cooling mechanism. In addition, the robust single-piece combustor deflector-flare cone facilitates an extended operational life expectancy over prior art separate combustor deflectors and flare cones. Such combustor deflector-flare cones also facilitate gas turbine fabrication time and cost, and reduced maintenance costs and gas turbine outages.
Exemplary embodiments of single-piece cast and machined combustor deflector-flare cones as associated with gas turbines are described above in detail. The methods, apparatus, and systems are not limited to the specific embodiments described herein or to the specific illustrated gas turbines.
The above-described embodiments of an apparatus and method for fabricating a deflector-flare cone provides a cost-effective and reliable means for improved manufacturing of gas turbine engine components. More specifically, the apparatus and method described herein facilitate reducing a part count and fabrication steps. As a result, the apparatus and method described herein facilitate manufacturing gas turbine engine components in a cost-effective and reliable manner.
This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
