Micromixer for combustor, combustor including same and method of mixing tube repair

A method comprising:

• for a micromixer including at least one damaged mixing tube amongst a plurality of mixing tubes includes a first material, having a cylindrical inner diameter and extending from a first end at least one of an air plenum and a fuel plenum to a second end at a combustion chamber of a combustor:
• removing a damaged portion from the second end of the at least one damaged mixing tube, leaving a body portion of the at least one damaged mixing tube with a circular end surface;
• cladding a cladded tip portion onto the circular end surface of the body portion of the at least one damaged mixing tube, the cladded tip portion including a second material different than the first material and a combustion end opposite the circular end surface of the body portion;
• identifying a centerline of the body portion of the at least one damaged mixing tube;
• forming a vibration dampening material around a portion of the plurality of mixing tubes;
• based on the centerline of the body portion of the at least one damaged mixing tube, forming a tapered inner surface extending from the combustion end of the cladded tip portion to a location on the body portion of the at least one damaged mixing tube;
• and
• removing the vibration dampening material.

A micromixer for combusting a fuel-air mixture in a combustion chamber of a combustor, the micromixer comprising:

• a fuel plenum;
• an air plenum;
• a plurality of mixing tubes in fluid communication with the fuel plenum and the air plenum and extending to the combustion chamber, wherein the plurality of mixing tubes include at least one first mixing tube including:
• a body portion made of a first material and including a first end and a second end, the first end in fluid communication with the fuel plenum and the air plenum;
• and
• a cladded tip portion made of a second material different than the first material and coupled to the second end of the body portion, the cladded tip portion including a combustion end configured to direct the fuel-air mixture into the combustion chamber, and
• wherein the body portion has a cylindrical inner diameter and the cladded tip portion has an inner diameter at the combustion end thereof larger than the cylindrical inner diameter of the body portion.