Gas turbine combustor with staged combustion

An annular combustor for a gas turbine engine, comprising:

• an inboard liner extending circumferentially and extending longitudinally fore to aft;
• an outboard liner extending circumferentially and extending longitudinally fore to aft and circumscribing the inboard liner;
• a bulkhead extending between a forward end of the inboard liner and a forward end of the outboard liner and in cooperation with the inboard liner and the outboard liner defining an annular combustion chamber;
• and
• the outboard liner including a forward section defining a radially outward projecting substantially rectangular stabilization chamber extending aftward from the bulkhead and circumferentially about and in open relationship to the annular combustion chamber;
• the inboard liner including a forward section defining a radially inward projecting substantially rectangular stabilization chamber extending aftward from the bulkhead in open relationship to the annular combustion chamber;
• a plurality of primary fuel injectors opening through the bulkhead admitting fuel directly into a central primary combustion zone of the annular combustion chamber, the plurality of the primary fuel injectors disposed at circumferentially spaced intervals in a ring radially intermediate the inboard liner and the outboard liner;
• a plurality of secondary fuel injectors opening through the bulkhead admitting fuel directly into a secondary combustion zone substantially located in the stabilization chamber of the outboard liner, the plurality of secondary fuel injectors being independently controllable relative to the plurality of primary fuel injectors, disposed at circumferentially spaced intervals in a ring coaxially radially outboard of the plurality of primary fuel injectors and arranged in circumferential alignment with the plurality of primary fuel injectors;
• a first plurality of tertiary fuel injectors opening through the bulkhead admitting fuel directly into a first tertiary combustion zone, the first plurality of tertiary fuel injectors being independently controllable relative to the plurality of primary fuel injectors and plurality of secondary fuel injectors, disposed at circumferentially spaced intervals in a ring coaxially radially outboard of the plurality of primary fuel injectors and coaxially radially inboard of the plurality of the secondary fuel injectors, and arranged in an alternating relationship with the plurality of primary fuel injectors and plurality of secondary fuel injectors, the first tertiary combustion zone located coaxially radially outboard of the central primary combustion zone and coaxially radially inboard of the secondary combustion zone;
• and
• a second plurality of tertiary fuel injectors opening through the bulkhead admitting fuel into a second tertiary combustion zone of the annular combustion chamber, the second plurality of tertiary fuel injectors being independently controllable relative to the plurality of primary fuel injectors, plurality of secondary fuel injectors and the first plurality of tertiary fuel injectors, disposed at circumferentially spaced intervals in a ring coaxially radially inboard of the primary fuel injectors and arranged in an alternating relationship with the plurality of primary fuel injectors and plurality of secondary fuel injectors, the second tertiary combustion zone located radially inward of the central primary combustion zone.

A method for operating a gas turbine engine over a power demand range having a low power demand, an intermediate power demand and a high power demand, the gas turbine engine having a combustor, the combustor having an inboard liner, an outboard liner circumscribing the inboard liner, and a bulkhead extending between a forward end of the inboard liner and a forward end of the outboard liner and in cooperation with the inboard liner and the outboard liner defining an annular combustion chamber, the outboard liner including a forward section defining a radially outward projecting substantially rectangular stabilization chamber extending aftward from the bulkhead and circumferentially about and in open relationship to the annular combustion chamber, the inboard liner including a forward section and an aft section, the forward section converges towards the outboard liner from fore to aft and the aft section converges towards the outboard liner from fore to aft more gradually than the forward section, the combustor further including a plurality of primary fuel injectors opening through the bulkhead admitting fuel directly into a central primary combustion zone of the annular combustion chamber, the plurality of the primary fuel injectors disposed at circumferentially spaced intervals in a ring radially intermediate the inboard liner and the outboard liner, the combustor further including a plurality of secondary fuel injectors opening through the bulkhead admitting fuel directly into a secondary combustion zone substantially located in the stabilization chamber of the outboard liner, the plurality of secondary fuel injectors being independently controllable relative to the plurality of primary fuel injectors, disposed at circumferentially spaced intervals in a ring coaxially radially outboard of the plurality of primary fuel injectors and arranged in circumferential alignment with the plurality of primary fuel injectors, and the combustor further including a first plurality of tertiary fuel injectors opening through the bulkhead admitting fuel directly into a first tertiary combustion zone, the first plurality of tertiary fuel injectors being independently controllable relative to the plurality of primary fuel injectors and plurality of secondary fuel injectors, disposed at circumferentially spaced intervals in a ring coaxially radially outboard of the plurality of primary fuel injectors and coaxially radially inboard of the plurality of secondary fuel injectors, and arranged in an alternating relationship with the plurality of primary fuel injectors and plurality of secondary fuel injectors, the first tertiary combustion zone located coaxially radially outboard of the central primary combustion zone and coaxially radially inboard of the secondary combustion zone, the method comprising the steps of:

• injecting a primary fuel supply into the primary combustion zone during all power demands, the primary combustion zone intermediate the inboard liner and the outboard liner;
• injecting a secondary fuel supply into a secondary combustion zone during all power demands, the secondary combustion zone substantially in the first stabilization chamber, the secondary fuel supply being independently controllable relative to the primary fuel supply;
• and
• injecting a first tertiary fuel supply into the first tertiary combustion zone during intermediate and high power demand, the first tertiary combustion zone coaxially radially outboard of the primary combustion zone and coaxially radially inboard of the secondary combustion zone, the first tertiary fuel supply independently controllable relative to the primary fuel supply and the secondary fuel supply;
• and
• injecting a second tertiary fuel supply into a second tertiary combustion zone during high power demand, the second tertiary zone radially inboard of the primary combustion zone, the second tertiary fuel supply independently controllable relative to the primary fuel supply, the secondary fuel supply and the first tertiary fuel supply.