Patent ID: 7694521

Claim:
A combustor comprising: a pilot nozzle located at a center portion of a main body of the combustor; a plurality of main nozzles located at a surrounding area of the pilot nozzle, each respective main nozzle of the plurality of main nozzles being spaced apart at a regular interval; a pilot cone covering a downstream-side tip portion of the pilot nozzle; and main burners covering downstream-side tip portions of the plurality of main nozzles, wherein, the pilot cone comprises: a cone having a tapered portion located at an inner circumference thereof, such that the tapered portion of the cone forms a tapered shape stretching outwardly in a radial pattern toward a downstream side of the combustor; a cylinder installed therein, such that a space is formed between the cylinder and an outer wall of the tapered portion of the inner circumference of the cone; and a collar portion located at an external periphery of a downstream-side tip of the tapered portion of the inner circumference the cone, such that the collar portion is located on a downstream side of downstream-side tips of the main burners and such that the collar portion provides a surface extending approximately vertical to an axial direction of the pilot nozzle, wherein, an angle measured from a line extending in the axial direction to a line that connects an external periphery of a downstream-side tip of the pilot nozzle with an external periphery of the downstream-side tips of the main burners is specified as “αx,” and wherein an opening angle, measured at the tapered portion of the inner circumference of the cone is specified as “θ” wherein “0<θ<2αx.”.