Combustors with improved dynamics

A combustor comprising:

• an outer combustor casing defining a plurality of circumferentially adjoining combustion chambers, each combustion chamber comprising a dome at an upstream end and an outlet at a downstream end;
• a plurality of pre-mixers joined to said combustor dome of each respective combustion chamber, said pre-mixers comprising a duct having an inlet at one end for receiving compressed air, an outlet at an opposite end disposed in flow communication with said combustion chamber and a swirler disposed in said duct adjacent said duct inlet for swirling air channeled therethrough;
• and
• a fuel injector for injecting fuel into said pre-mixer ducts and for mixing with said air in said ducts for flow into said combustion chamber to generate a combustion flame at said duct outlets;
• and
• a plurality of flameholders positioned axially downstream from said dome and proximate a pressure node so as to minimize Rayleigh's criteria.

An industrial gas turbine including a combustor comprising:

• an outer combustor casing defining a plurality of circumferentially adjoining combustion chambers, each combustion chamber comprising a dome at an upstream end and an outlet at a downstream end;
• a plurality of pre-mixers joined to said combustor dome of each respective combustion chamber, said pre-mixers comprising a duct having an inlet at one end for receiving compressed air, an outlet at an opposite end disposed in flow communication with said combustion chamber and a swirler disposed in said duct adjacent said duct inlet for swirling air channeled therethrough;
• and
• a fuel injector for injecting fuel into said pre-mixer ducts and for mixing with said air in said ducts for flow into said combustion chamber to generate a combustion flame at said duct outlets;
• wherein a portion of said pre-mixers comprise an altered flameholding capability so as to distribute said resulting combustion flames from said respective portion of said pre-mixers axially downstream with respect to said non-altered pre-mixers to reduce the dynamic pressure amplitude of said combustion flames.

An industrial gas turbine having a combustor comprising:

• an outer combustor casing defining a plurality of circumferentially adjoining combustion chambers, each combustion chamber comprising a dome at an upstream end and an outlet at a downstream end;
• a plurality of pre-mixers joined to said combustor dome of each respective combustion chamber, said pre-mixers comprising a duct having an inlet at one end for receiving compressed air, an outlet at an opposite end disposed in flow communication with said combustion chamber and a swirler disposed in said duct adjacent said duct inlet for swirling air channeled therethrough;
• and
• a fuel injector for injecting fuel into said pre-mixer ducts and for mixing with said air in said ducts for flow into said combustion chamber to generate a combustion flame at said duct outlets;
• and
• a plurality of flameholders positioned axially downstream from said dome and proximate a pressure node so as to minimize Rayleigh's criteria.