Abstract: A combustor for a gas turbine engine includes divergent mixing cones disposed substantially within the combustion chamber proper to provide a flow restriction which separates the combustion chamber into primary and secondary combustion zones. Placement of the mixing cones within the chamber enhances vaporization of the fuel and permits combustion to take place in the primary zone at flame temperatures below the stoichiometric temperature thereby reducing formation of nitrous oxides. The mixing cones have external cooling shrouds to prevent autoignition, and the mixing cones for the primary zone provide tangential swirl of the vaporized fuel/air charge in a direction opposite that of the secondary mixing cones. The mixing cones together with an associate fuel nozzle sub-assembly form an integrated unit separable from the combustor for calibration and setting of the fuel/air ratio.