Lean-rich axial stage combustion in a can-annular gas turbine engine

A gas turbine engine comprising:

• a can-annular combustor;
• a transition in fluid communication between the combustor and a turbine;
• a combustor extender in fluid communication between the combustor and the transition;
• a plurality of wall openings formed through the combustor extender;
• and
• a fuel manifold extending along an outer surface of the combustor extender, said fuel manifold comprising a plurality of fuel nozzles aligned to deliver fuel through the respective plurality of wall openings.

A method for axial stage combustion in a gas turbine engine comprising:

• igniting a lean air-fuel mixture at a first stage of combustion of the gas turbine engine to create hot combustion gas having a temperature below a predetermined NOx production threshold limit;
• mixing a rich air-fuel mixture with an equivalence ratio greater than or equal to three;
• injecting the rich air-fuel mixture into the hot combustion gas at a second stage of combustion downstream from the first stage;
• and
• utilizing heat of the hot combustion gas and free radicals therein to ignite the rich air-fuel mixture such that the rich air-fuel mixture is combusted within a predetermined hydrocarbon emissions limit and the temperature of the hot combustion gas is increased by a threshold amount to a temperature still below the NOx production threshold limit.