Variable volume combustor with pre-nozzle fuel injection system

A method of operating a combustor in a gas turbine engine, the combustor comprising a liner, a cap assembly, and a seal in between the liner and the cap assembly, the method comprising:

• supporting a plurality of fuel nozzles about a plurality of support struts, the plurality of fuel nozzles positioned within the cap assembly;
• flowing a flow of fuel through the plurality of support struts to the plurality of fuel nozzles;
• actuating the plurality of fuel nozzles from a first position to a second position, such that a head end volume of the combustor is increased as a combustion zone volume of the combustor is decreased;
• diverting a pre-nozzle flow of fuel from the plurality of support struts;
• flowing a flow of air through the plurality of support struts;
• and
• mixing the flow of air and the pre-nozzle flow of fuel upstream of the plurality of fuel nozzles.

A combustor for use with a gas turbine engine, comprising:

• a liner;
• a cap assembly;
• a seal in between the liner and the cap assembly;
• a head end with a head end volume;
• a combustion zone with a combustion zone volume;
• a plurality of micro-mixer fuel nozzles positioned within the cap assembly;
• a plurality of support struts supporting the plurality of micro-mixer fuel nozzles;
• the plurality of support struts comprising a plurality of fuel injections holes thereon;
• and
• a linear actuator to maneuver the plurality of micro-mixer fuel nozzles and the plurality of support struts, such that the head end volume is increased as the combustion zone volume is decreased.