System and method for reducing combustion dynamics in a combustor

A system for reducing combustion dynamics in a combustor, comprising:

• a. an end cap that extends radially across at least a portion of the combustor wherein the end cap comprises an upstream surface axially separated from a downstream surface;
• b. a plurality of tube bundles that extends from the upstream surface through the downstream surface of the end cap, wherein each tube bundle provides fluid communication through the end cap;
• c. a first diluent passage, that extends circumferentially around a first tube bundle, wherein the first diluent passage is defined between an inner shroud and an outer shroud that extends axially within the end cap and at least partially through the downstream surface, wherein the first diluent passage extends axially through the downstream surface;
• d. a diluent supply in fluid communication with the first diluent passage, wherein the diluent supply provides diluent flow to the diluent passage;
• and
• e. a second diluent passage that is radially outward of the first diluent passage and extends axially through the downstream surface, wherein the second diluent passage separates the tube bundles into a plurality of sectors.

A method for reducing combustion dynamics in a combustor, comprising:

• a. flowing a fuel through a plurality of tube bundles that extend axially through an end cap that extends radially across at least a portion of the combustor;
• b. flowing a diluent through a first diluent passage of a first tube bundle into a combustion chamber downstream from the end cap, wherein the first diluent passage extends circumferentially around a first tube bundle, wherein the first diluent passage is defined between an inner shroud and an outer shroud that extend axially within the end cap and at least partially through a downstream surface of the end cap, wherein the first diluent passage extends axially through at least a portion of the end cap;
• c. forming a diluent barrier in the combustion chamber between the first tube bundle and at least one other adjacent tube bundle;
• and
• d. flowing diluent through a second diluent passage, wherein the second diluent passage is radially outward of the first diluent passage and separates the plurality of tube bundles into a plurality of sectors.