Annular premixed pilot in fuel nozzle

Abstract

A combustor for a gas turbine engine has a head end portion that carries at least one fuel / air nozzle. Each fuel / air nozzle includes a premixed pilot nozzle having premix conduits where each premix conduit has an upstream end defining an opening and having a central axis and downstream end defining an outlet and having a central axis where the central axis of the downstream end is non-parallel with a central axis of a center body of the fuel / air nozzle. The premixed pilot nozzle can include an annular channel disposed radially outwardly from the premix conduits and may include air jets that direct air radially outwardly from the premix conduits.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application is a continuation application of U.S. application having Ser. No. 13 / 405,550 filed on Feb. 27, 2012, which is incorporated herein in its entirety by reference thereto for all purposes. Any disclaimer that may have occurred during prosecution of the above-referenced application(s) is hereby expressly rescinded.FIELD OF THE INVENTION[0002]The present invention generally involves a gas turbine engine that combusts a hydrocarbon fuel mixed with air to generate a high temperature gas stream that drives turbine blades to rotate a shaft attached to the blades and more particularly to the engine's fuel nozzle having a pilot nozzle that premixes fuel and air while achieving lower nitrogen oxides.BACKGROUND OF THE INVENTION[0003]Gas turbine engines are widely used to generate power for numerous applications. A conventional gas turbine engine includes a compressor, a combustor, and a turbine. In a typical gas turbine engine, ...

AI Technical Summary

Benefits of technology

[0008]In theory, the closer one comes to having at every point in the combustion chamber, a stoichiometric relationship between the fuel and air that undergoes combustion at a given temperature of combustion, the closer one comes to minimizing the generation of nitrogen oxides as byproducts of the combustion. With a fuel nozzle configured as described below, it becomes possible to achieve a more uniform equivalence ratio across the plane of the center body tip of the outer nozzle and thus more closely approximate achieving in the combustion chamber of the gas turbine engine such theoretical conditions of the desired stoichiometric relationship between the fuel and air that undergoes combustion at a given temperature of combustion. Moreover, to overcome one of the drawbacks of a diffusion flame type of pilot, a premix pilot also can be used as a pilot to stabilize the pilot flame, even in low fuel to air ratio to prevent an increase in NOx.

Problems solved by technology

However, there is a trade-off in performance of the gas turbine engine.

For as the ratio of fuel to air that is combusted is lowered, there is an increased tendency of the flame of the fuel nozzle to blow out and thus render unstable the operation of the gas turbine engine.

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