Patent Application
20080053102
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.
Outer and inner liners 140 and 142 extend downstream from dome 144 to a turbine nozzle 156. In the exemplary embodiment, outer and inner liners 140 and 142, respectively, each include a plurality of panels 158 and 160, respectively, and each also includes a series of steps 162, each of which forms a distinct portion of combustor liners 140 and 142. Mixer assemblies 146 and 148 are coupled in flow communication with turbine nozzle 156 via combustion chamber 150.
Combustor 106 includes an outer cowl 164 and an inner cowl 166. Outer cowl 164 and inner cowl 166 are each coupled to portions of panels 158 and 160, respectively. More specifically, outer and inner liner panels 158 and 160, respectively, are coupled serially to, and extend downstream from, cowls 164 and 166, respectively. Outer cowl 164 extends annularly in combustor 106 about mixer 146 and inner cowl 166 extends annularly in combustor 106 about mixer 148. Combustor 106 also includes an annular center cowl 168 that includes an outer cowl portion 170, an inner cowl portion 172, and a center portion 174. Portions 170 and 172 are coupled to portion 174 and all three portions 170, 172, and 174 define an annular cavity 175 therebetween. Cowl 164 and center cowl portion 170 at least partially define an outer mixer cavity 176 and an annular entrance 178. Similarly, cowl 166 and cowl portion 172 at least partially define an inner mixer cavity 180 and entrance 182. Compressor 104 is coupled in flow communication with mixer 146 via entrance 178 and cavity 176. Similarly, compressor 104 is coupled in flow communication with mixer 148 via entrance 182 and cavity 180.
Combustor 106 also includes a dome plate 184 that extends annularly about engine centerline 122 upstream of combustion chamber 150. Dome plate 184 is coupled to liners 140 and 142 and provides structural support to mixers 146 and 148. A plurality of openings (not shown in
Mixer 146 includes a cone assembly 190 having a deflector portion 192 and a flare cone portion 194. Similarly, mixer 148 includes a cone assembly 200 that further includes a deflector portion 202 and a flare-cone portion 204. In the exemplary embodiment, mixers 146 and 148 are substantially identical.
Mixer assembly 146 is supplied fuel via a fuel injector 205 that is supplied fuel via fuel supply line 206. Line 206 is connected to a fuel source (not shown in
Combustor 106 also includes a substantially annular flow center shield 211 positioned between mixers 146 and 148. Center shield 211 includes a plurality of walls 212 that defines an annular chamber 213 therein and that includes a plurality of air jets 214. Center shield 211 is coupled to dome plate 184 and cowl center portion 174 via walls 212. Cavity 175, cowl center portion 174, a portion of walls 212, center shield chamber 213, and air jets 214 are coupled in flow communication and define a passage for channeling air from high-pressure compressor 104 to combustion chamber 150. Air jets 214 split flames from mixer 146 and mixer 148 such that interaction between the two flames is mitigated. Moreover, air flow from compressor 104 to combustion chamber 150 via center shield 211 facilitates removing heat from cowl 168 and dome plate 184.
During operation, air discharged from high-pressure compressor 104 is channeled to combustor 106. Specifically, air is channeled into mixer cavity 176 via entrance 178 and into mixer cavity 180 via entrance 182. Fuel is channeled from a fuel source (not shown in
Cone assembly 190 is coupled to air swirler 215. Specifically, flare cone portion 192 couples to exit cone 216 and extends downstream from exit cone 216. More specifically, flare cone portion 192 includes a radially inner flow surface 230 and a radially outer surface 232. When flare cone portion 192 is coupled to exit cone 216, radially inner flow surface 230 is positioned substantially co-planar with exit cone flow surface 218. Specifically, flare cone inner flow surface 230 is divergent such that flare cone inner flow surface 230 extends radially outwardly from an elbow 234 of flare cone body 235 to a trailing end 236 of flare cone portion 192. More specifically, flare cone outer surface 232 is substantially parallel to inner surface 230 between trailing edge 236 and elbow 234.
Deflector portion 194 facilitates preventing hot combustion gases from impinging upon combustor dome plate 184. Deflector portion 194 also includes a radially outer surface 240 and a radially inner surface 242. Radially outer surface 240 and radially inner surface 242 extend from deflector leading edge 244 across deflector 194 to deflector trailing edge 246. Deflector radially inner surface 242 includes two radially-narrow regions 241 and two radially-wide regions 243. A substantially annular gap 247 is defined between radially outer surface 232 and at least a portion of deflector inner surface 242.
Flare cone body 235 includes a forward surface 248 and an aft surface 250. A plurality of cooling injectors 300 are defined within and extend axially through, flare cone body 235. More specifically, injectors 300 extend from an entrance 302 defined within flare cone body forward surface 248 to an exit 304 defined within flare cone body aft surface 250. Entrance 302 is upstream from exit 304 such that injectors 300 discharge cooling fluid therethrough at a reduced pressure. In one embodiment, the cooling fluid is compressed air channeled from compressor 104. Alternatively, the cooling fluid may be from any source that facilitates cooling as described herein.
Injectors 300 extend radially outward with respect to axis 207 and from forward entrance 302 to aft exit 304. In the exemplary embodiment, injectors 300 include a plurality of injectors having different discharge diameters. Specifically, in the exemplary embodiment, there are two groups of injectors 300, i.e., a small-diameter group 306 and a large-diameter group 308. More specifically, in the exemplary embodiment, the diameter associated with group 306 is approximately 0.889 millimeters (mm) (0.0350 inches (in) and the diameter associated with group 308 is approximately 1.433 mm (0.0564 in). Moreover, in the exemplary embodiment, injectors 300 are arranged such that two circumferentially opposite groups 306 are positioned to inject cooling fluid towards radially narrow regions 241 of deflector inner surface 242 and there are two circumferentially opposite groups 308 to inject cooling fluid towards radially widest regions 243 of deflector inner surface 242. The differing diameters associated with injector groups 306 and 308 facilitate biasing cooling fluid flow over deflector 194. Specifically, the differing diameters facilitate injecting differing cooling fluid mass flow rates across differing regions 241 and 243 of deflector surface 242. More specifically, injector groups 308 inject cooling fluid at a greater predetermined mass flow rate across regions 243 than injector groups 306 inject across regions 241. Alternatively, any diameters arranged in any configuration that attain predetermined operating parameters may be used.
In the exemplary embodiment, flare cone 192 and deflector 194 are fabricated independently. The methods of fabrication include, but are not limited to, casting. Subsequently, injectors 300 are formed using methods that include, but are not limited to, known electrical discharge machining (EDM) method. Alternatively, injectors 300 may be formed within flare cone 192 during casting. Also, alternatively, flare cone 192 and deflector 194 may be formed as an integral, unity flare cone-deflector assembly 190 via methods that include, but are not limited to, casting.
During operation, forward swirler vanes 226 swirl air in a first rotational direction and aft swirler vanes 227 swirl air in a second rotational direction that is opposite to the first rotational direction. Fuel discharged from fuel injector 205 (shown in
Cooling fluid is supplied to cone assembly 190 through cooling injector groups 306 and 308. Groups 306 and 308 facilitate channeling a continuous flow of cooling fluid to be discharged at a reduced pressure for impingement cooling of flare cone 192. The reduced pressure facilitates improved cooling and backflow margin for the impingement cooling of flare cone 192 via cooling fluid impingement on radially outer surface 232. Furthermore, the cooling fluid enhances convective heat transfer and facilitates reducing an operating temperature of flare cone 192. The reduced operating temperature facilitates extending a useful life of flare cone 192 via mechanisms that include, but are not limited to, mitigating a potential for heat-induced distortion and deleterious oxidation of flare cone 192.
Furthermore, as cooling fluid is discharged through injector groups 306 and 308, deflector 194 is film cooled. More specifically, injector groups 306 and 308 supply inner surface 242 with film cooling. Because groups 306 and 308 are disposed circumferentially about flare cone 192 and the cooling fluid impinges on radially outer surface 232, film cooling is directed along inner surface 242 circumferentially around flare cone 192. In addition, because groups 306 and 308 facilitate directed cooling flow as described above, cone assembly 190 facilitates optimizing film cooling across deflector regions 241 and 243. Specifically, the differing diameters associated with injector groups 306 and 308 facilitate biasing cooling fluid flow over deflector 194. More specifically, the differing diameters facilitate injecting differing cooling fluid mass flow rates across differing regions 241 and 243 of deflector surface 242. Even more specifically, injector groups 308 inject cooling fluid at a greater predetermined mass flow rate across regions 243 than injector groups 306 inject across regions 241. Therefore, preferential cooling of regions 241 and 243 is facilitated and temperature differentials between regions 241 and 243 are mitigated. Moreover, a reduction in temperature differentials between regions 241 and 243 mitigates inducing heat stresses between regions 241 and 243 that subsequently mitigates a potential for distortion of deflector 194. Furthermore, optimizing cooling fluid flow as described herein facilitates mitigating a potential for nitrogen oxides (NOx) formation when the cooling fluid is air.
In the exemplary embodiment, radially outer surface 232 is positioned substantially parallel to a portion of inner surface 242. Therefore, in the exemplary embodiment, the distance between surface 242 and trailing edge 236 is substantially circumferentially constant and the cooling fluid mass flow rate is substantially biased by injector groups 306 and 308 sizing and positioning. Alternatively, flare cone 192 has a varying distance (not shown) between surface 242 and trailing edge 236 such that cooling fluid mass flow rates are further biased to facilitate a greater predetermined mass flow rate across regions 243 than across regions 241. Specifically, the distance of gap 247 between surface 242 and trailing edge 236 associated with regions 243 is greater than the distance of gap 247 associated with regions 241. Fabricating an integral, unitized cone assembly 190 as discussed above facilitates this alternative embodiment.
A method for operating gas turbine engine 100 includes channeling cooling fluid, i.e., air from a cooling fluid source, i.e., compressor 104, to combustors 106 that include at least one deflector 194 and at least one flare cone 192. Deflector 194 and flare cone 192 are coupled together and are configured to define cooling fluid channel 247, i.e., gap 247, therebetween. Flare cone 192 has a plurality of cooling injectors 300 extending through a portion of flare cone 192. Plurality of cooling injectors 300 are spaced circumferentially about centerline axis 207 of flare cone 192 and are coupled in flow communication with the cooling fluid source, i.e., compressor 104. Plurality of cooling injectors 300 includes plurality of first cooling injectors 308 and plurality of second cooling injectors 306. The method also includes directing a portion of the cooling fluid, i.e., compressed air, through plurality of first cooling injectors 308. The method further includes directing a portion of the compressed air through plurality of second cooling injectors 306, wherein first plurality of cooling injectors 308 facilitates cooling a portion of deflector 194 more than second plurality of cooling injectors 306.
The methods and apparatuses for a combustor described herein facilitate operation of a gas turbine. More specifically, the combustor cone assembly as described above facilitates an efficient and effective combustor cooling mechanism. Also, the robust combustor cone assembly facilitates an extended operational life expectancy of combustor deflectors and flare cones. Such combustor deflector-flare cone assemblies also facilitate gas turbine reliability, and reduced maintenance costs and gas turbine outages.
Exemplary embodiments of combustor deflector-flare cone assemblies as associated with gas turbines are described above in detail. The methods, apparatus and systems are not limited to the specific embodiments described herein nor to the specific illustrated gas turbines.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
