Gas turbine and fuel injector for the same

Abstract

A fuel injector for a gas turbine engine includes an injector housing having a central cavity configured to fluidly couple with a combustor of the gas turbine engine. The fuel injector may include a fuel nozzle at the upstream end of the central cavity. The fuel nozzle may be configured to direct a first fuel into the central cavity. The fuel injector may also include an annular air inlet disposed circumferentially about the fuel nozzle at the upstream end of the central cavity, and an annular air discharge outlet circumferentially disposed about the exit opening of the central cavity. The fuel injector may further include an annular fuel discharge outlet circumferentially disposed about the air discharge outlet. The fuel discharge outlet may be configured to discharge a second fuel into the combustor circumferentially around the air discharge outlet.

What is claimed is: 
     
         1 . A fuel injector for a gas turbine engine comprising:
 an injector housing including a central cavity extending along a longitudinal axis from an upstream end to a downstream end, the downstream end of the central cavity including an exit opening configured to fluidly couple the central cavity to a combustor of the gas turbine engine;   a fuel nozzle at the upstream end of the central cavity, the fuel nozzle being configured to direct a first fuel into the central cavity;   an annular air inlet of the central cavity disposed circumferentially about the fuel nozzle at the upstream end of the central cavity;   an annular air discharge outlet circumferentially disposed about the exit opening of the central cavity; and   an annular fuel discharge outlet circumferentially disposed about the air discharge outlet, the fuel discharge outlet being configured to discharge a second fuel into the combustor circumferentially around the air discharge outlet.   
     
     
         2 . The fuel injector of  claim 1 , further including an annular inner passageway extending from an inlet opening at the upstream end to the annular air discharge outlet at the downstream end, the inner passageway being disposed radially outwards of and symmetrically about the central cavity. 
     
     
         3 . The fuel injector of  claim 2 , wherein at least a portion of the inner passageway forms a convergent passageway. 
     
     
         4 . The fuel injector of  claim 2 , further including an annular outer passageway extending from the upstream end to the fuel discharge outlet at the downstream end, the outer passageway being disposed symmetrically about the central cavity and radially outwards the inner passageway. 
     
     
         5 . The fuel injector of  claim 4 , wherein at least a portion of the outer passageway forms a convergent passageway. 
     
     
         6 . The fuel injector of  claim 4 , further including an annular chamber extending around the upstream end of the injector housing, wherein the outer passageway is fluidly coupled to the annular chamber at the upstream end. 
     
     
         7 . The fuel injector of  claim 6 , further including a plurality of inlet ports coupled to the annular chamber, wherein a first inlet port of the plurality of inlet ports is configured to direct the second fuel into the outer passageway. 
     
     
         8 . The fuel injector of  claim 7 , wherein the second fuel is a liquid fuel and the plurality of inlet ports includes a second inlet port configured to direct a gaseous fuel into the outer passageway. 
     
     
         9 . The fuel injector of  claim 8 , wherein the plurality of inlet ports includes a third inlet port configured to direct steam into the outer passageway. 
     
     
         10 . The fuel injector of  claim 1 , wherein at least a portion of the central cavity is a convergent passageway. 
     
     
         11 . A method of operating a gas turbine engine comprising:
 directing a premixed fuel-air mixture into a combustor of the gas turbine engine through a central cavity of a fuel injector, the premixed fuel-air mixture being a mixture of a first fuel and a first quantity of compressed air, the central cavity extending from an upstream end to a downstream end fluidly coupled to the combustor;   directing a second quantity of compressed air into the combustor circumferentially around the premixed fuel-air mixture; and   directing a second fuel into the combustor circumferentially around the second quantity of compressed air, wherein directing the second fuel includes increasing an angular velocity of the second fuel in the fuel injector.   
     
     
         14 . The method of claim  13 , wherein directing the premixed fuel-air mixture includes directing the first fuel into the upstream end of the central cavity, and directing the first quantity of compressed air into the central cavity circumferentially around the first fuel. 
     
     
         15 . The method of claim  13 , further including increasing an angular velocity and a linear velocity of the second quantity of compressed air in the fuel injector prior to directing the second quantity of compressed air into the combustor. 
     
     
         16 . The method of claim  13 , further including directing steam into the combustor circumferentially around the second quantity of compressed air. 
     
     
         17 . A gas turbine engine, comprising:
 a combustion system including a combustor; and   a fuel injector extending from an upstream end to a downstream end along a longitudinal axis, the fuel injector being coupled to the combustor at the downstream end, the fuel injector including:
 a central cavity extending from the upstream end to a central opening at the downstream end, the central cavity being configured to direct a fuel into the combustor through the central opening; 
 an annular air discharge outlet circumferentially disposed about the central opening, the annular air discharge outlet being configured to direct compressed air into the combustor circumferentially around the fuel entering the combustor from the central cavity; and 
 an outer passageway circumferentially disposed about the central cavity, the outer passageway being configured to selectively direct a gaseous fuel and a liquid fuel into the combustor circumferentially around the compressed air from the air discharge outlet. 
   
     
     
         18 . The gas turbine of  claim 17 , wherein the outer passageway is fluidly coupled to an annular chamber that extends around the fuel injector at the upstream end, the annular chamber including a plurality of inlet ports coupled thereto, the plurality of inlet ports including a first inlet port configured to direct the gaseous fuel into the outer passageway, a second inlet port configured to direct the liquid fuel into the outer passageway, and a third inlet port configured to direct steam into the outer passageway. 
     
     
         19 . The gas turbine of  claim 17 , wherein at least a portion of the central cavity is a convergent passageway. 
     
     
         20 . The gas turbine engine of  claim 17 , wherein at least a portion of the outer passageway is a convergent passageway.