Burner and combustor

A burner of double tube structure comprising:

• an outer tube;
• and
• an inner tube, wherein the inner tube includes:
• a tip-side support portion fixed on the outer tube,
• a base-side support portion fixed on the outer tube,
• a main body portion supported by the tip-side support portion,
• bellows interposed between the main body portion and the base-side support portion,
• a bulkhead member attached at a position between the tip-side support portion and the base-side support portion,
• a first gap defined between an outermost peripheral surface of the bellows and an inner peripheral surface of the outer tube, and
• a second gap defined between an outer peripheral surface of the bulkhead member and the inner peripheral surface of the outer tube, the second gap being smaller than the first gap,
• wherein the outer tube includes:
• a main body formed in a circular cylindrical shape,
• a flange protruding outwardly in a radial direction from an outer peripheral surface of the main body, and
• a fuel port extending outwardly in the radial direction from an outer peripheral surface of the flange,
• wherein the burner further comprises:
• a fuel header formed between the outer tube and the inner tube,
• a plurality of main fuel nozzles connected to the fuel header,
• a pilot fuel nozzle extending inside the inner tube, and
• a radial fuel flow path formed inside the fuel port and extending in the radial direction, the radial fuel flow path leading to the fuel header from the radially outer side,
• wherein an outlet of the radial fuel flow path opens to the fuel header, and the bulkhead member is interposed between the outlet of the radial fuel flow path and the bellows,
• the bulkhead member is interposed between the bellows and the plurality of main fuel nozzles, and
• the bulkhead member separates a volume in which the bellows are positioned from a volume defined by the outlet of the radial fuel flow path and the fuel header.