Compact turbomachine combustor

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.

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.