Compact turbomachine combustor
Combustors, gas turbines, and associated methods of operation are provided. A method for operating a combustor includes firing a bundled tube fuel nozzle assembly within a combustion liner of the combustor to generate combustion gases at a first temperature within a first combustion zone length. The method further includes firing a fuel injector downstream from the bundled tube fuel nozzle assembly within the combustion liner of the combustor to generate combustion gases at a second temperature within a second combustion zone length. The first combustion zone length is less than the second combustion zone length. The combustion gases travel through the first combustion zone length in a first time period and through the second combustion zone length in a second time period. The second time period is less than the first time period.
1 . A combustor comprising:
an end cover defining a forward end of the combustor;
a combustion liner having an upstream end and a downstream end;
a bundled tube fuel nozzle assembly comprising a plurality of bundled tube fuel nozzles fluidly coupled to the end cover at the upstream end of the combustion liner and extending to a plurality of outlets in a cap plate, the cap plate defining a diameter of the bundled tube fuel nozzle assembly;
a plurality of fuel injectors coupled to the combustion liner and disposed downstream from the plurality of bundled fuel nozzles and upstream from an aft frame, the aft frame coupled to the downstream end of the combustion liner;
wherein the combustion liner defines a combustion zone between the plurality of outlets and the aft frame through which combustion gases travel over a total time period, the combustion zone comprising:
a first combustion zone defined between the plurality of outlets and a forward end of the plurality of fuel injectors through which the combustion gases from the plurality of bundled tube fuel nozzles flow over a first portion of the total time period, the first combustion zone defining a first combustion zone length between the plurality of outlets and the forward end of the plurality of fuel injectors;
a second combustion zone defined between the plurality of fuel injectors and the aft frame through which the combustion gases from the plurality of bundled tube fuel nozzles and the plurality of fuel injectors flow over a second portion of the total time period, the second combustion zone defining a second combustion zone length between the forward end of the plurality of fuel injectors and the aft frame; and
wherein the first combustion zone length is between about 45% and about 80% of the diameter of the bundled tube fuel nozzle assembly, and wherein the second combustion zone length is between about 120% and about 180% of the diameter of the bundled tube fuel nozzle assembly, and wherein the second portion of the total time period is between about 35% and about 45% of the total time period.
2 . The combustor as in claim 1 , further comprising an outer sleeve surrounding at least a portion of the combustion liner; wherein the combustion liner defines a first radial opening downstream from the plurality of bundled tube fuel nozzles; wherein the outer sleeve defines a second radial opening; wherein the second radial opening is aligned with the first radial opening; and wherein a fuel injector of the plurality of fuel injectors extends through the first radial opening and the second radial opening.
3 . The combustor as in claim 2 , wherein the first radial opening of the combustion liner and the second radial opening of the outer sleeve are shaped as a geometric stadium having a major axis and a minor axis, wherein the major axis is parallel with an axial centerline of the combustor.
4 . The combustor as in claim 1 , wherein each bundled tube fuel nozzle of the plurality of bundled tube fuel nozzles comprises a fuel plenum body comprising a forward wall, an aft wall, and an outer band; a fuel plenum defined within the fuel plenum body; and a plurality of tubes extending through the forward wall, the fuel plenum, and the aft wall.
5 . A gas turbine comprising:
a compressor;
a turbine; and
a combustor disposed downstream from the compressor and upstream from the turbine, the combustor comprising:
an end cover defining a forward end of the combustor;
a combustion liner having an upstream end and a downstream end;
a bundled tube fuel nozzle assembly comprising a plurality of bundled tube fuel nozzles fluidly coupled to the end cover at the upstream end of the combustion liner and extending to a plurality of outlets in a cap plate, the cap plate defining a diameter of the bundled tube fuel nozzle assembly;
a plurality of fuel injectors coupled to the combustion liner and disposed downstream from the plurality of bundled fuel nozzles and upstream from an aft frame, the aft frame coupled to the downstream end of the combustion liner;
wherein the combustion liner defines a combustion zone between the plurality of outlets and the aft frame through which combustion gases travel over a total time period, the combustion zone comprising:
a first combustion zone defined between the plurality of outlets and a forward end of the plurality of fuel injectors through which the combustion gases from the plurality of bundled tube fuel nozzles flow over a first portion of the total time period, the first combustion zone defining a first combustion zone length between the plurality of outlets and the forward end of the plurality of fuel injectors;
a second combustion zone defined between the plurality of fuel injectors and the aft frame through which the combustion gases from the plurality of bundled tube fuel nozzles and the plurality of fuel injectors flow over a second portion of the total time period, the second combustion zone defining a second combustion zone length between the forward end of the plurality of fuel injectors and the aft frame; and
wherein the first combustion zone length is between about 45% and about 80% of the diameter of the bundled tube fuel nozzle assembly, and wherein the second combustion zone length is between about 120% and about 180% of the diameter of the bundled tube fuel nozzle assembly, and wherein the second portion of the total time period is between about 35% and about 45% of the total time period.
6 . The gas turbine as in claim 5 , further comprising an outer sleeve surrounding at least a portion of the combustion liner; wherein the combustion liner defines a first radial opening downstream from the plurality of bundled tube fuel nozzles; wherein the outer sleeve defines a second radial opening; wherein the second radial opening is aligned with the first radial opening; and wherein a fuel injector of the plurality of fuel injectors extends through the first radial opening and the second radial opening.
7 . The gas turbine as in claim 6 , wherein the first radial opening of the combustion liner and the second radial opening of the outer sleeve are shaped as a geometric stadium having a major axis and a minor axis, wherein the major axis is parallel with an axial centerline of the combustor.
8 . A method of operating a combustor, comprising:
firing a bundled tube fuel nozzle assembly within a combustion liner of the combustor, whereby combustion gases at a first temperature are generated within a first combustion zone length;
firing a fuel injector downstream from the bundled tube fuel nozzle assembly within the combustion liner of the combustor, whereby additional combustion gases are generated within a second combustion zone length, the additional combustion gases having a second temperature, wherein the first combustion zone length is defined between a plurality of outlets of the bundled tube fuel nozzle and a forward end of the fuel injector, wherein the second combustion zone length is defined between the forward end the fuel injector and an aft frame of the combustor, wherein the first combustion zone length is between about 45% and about 80% of a diameter of the bundled tube fuel nozzle assembly, and wherein the second combustion zone length is between about 120% and about 180% of the diameter of the bundled tube fuel nozzle assembly; and
providing the additional combustion gases at the second temperature to a turbine downstream of the combustor, wherein the combustion gases and the additional combustion gases travel from the combustor to the turbine over a total time period, wherein the total time period comprises a first portion of the total time period in the first combustion zone length and a second portion of the total time period in the second combustion zone length, and wherein the second portion of the total time period is about 35% to about 45% of the total time period.
9 . The method as in claim 8 , wherein the bundled tube fuel nozzle assembly includes a cap plate that defines the diameter of the bundled tube fuel nozzle assembly.
10 . The method as in claim 9 , wherein the combustion liner defines a radial opening through which the fuel injector is disposed, wherein the radial opening is shaped as a geometric stadium having a major axis and a minor axis, and wherein the major axis is parallel with an axial centerline of the combustor.