Patent ID: 8156746

Claim:
A method of injecting fuel into a gas turbine comprising the steps of: a) providing an inboard pilot combustion zone, wherein the pilot combustion zone is produced by fuel issuing from a pilot fuel swirler and air issuing from inner and outer pilot air swirlers; b) providing a main combustion zone outboard of the pilot combustion zone, wherein the main combustion zone is produced by fuel issuing from a main fuel swirler and air issuing from inner and outer main air swirlers; c) mechanically separating the main combustion zone from the pilot combustion zone by confining air flowing from the main inner air swirler within a conical air passage defined about a conically extending wall in such a manner so as to delay mixing of hot combustion products from the pilot combustion zone into the main combustion zone; and d) flowing cooling air along a radially inner surface of the conically extending wall, wherein the cooling air is provided by an intermediate air swirler located between the main inner air swirler and the pilot outer air swirler.