Combustor and gas turbine

A combustor, comprising:

• a combustor basket which is configured to receive air from the an outside of the combustor;
• a plurality of first nozzles that are provided along an inner periphery of the combustor basket and that extend in an axial direction of the combustor basket;
• a second nozzle that is arranged at a center of the combustor basket and that extends in an axial direction of the combustor basket;
• and
• a transition piece that is connected to the combustor basket and that is configured to allow high-temperature combustion gas to flow inside of the transition piece, wherein
• each of the first nozzles has fuel discharge holes and is surrounded by a first nozzle pipe which is configured to mix the air and fuel discharged from the fuel discharge holes forming a premixed gas,
• the second nozzle has fuel discharge holes and is surrounded by a second nozzle pipe, a gap is provided between the first nozzle pipe and the second nozzle pipe, which is configured to provide cooling air into combustion zone,
• cooling air is configured to flow around the first nozzles, the second nozzle, combustor basket and the transition piece,
• an area located near the outlet of the first nozzles, which is positioned inside the combustor basket, includes a first area near a radially outer periphery of the first nozzles receiving the cooling air and a second area near a radially inner periphery of the first nozzles located radially inward with respect to the first area, and which receives the cooling air from the gap, radially being defined relative to a combustor axis, and
• wherein a flow amount of the cooling air in the second area is larger than a flow amount of the cooling air in the first area, the first nozzles are configured such that, in the first nozzle pipes at their outlets, a fuel concentration of the premixed gas in the second area is relatively higher than that in the first area, and mixing of the cooling air with the premixed gas in the first area and second area promoting relatively uniform flame temperature.