Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
2000-05-25
2001-06-19
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
Reexamination Certificate
active
06247317
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to gas turbine engines, and more particularly, to a fuel injector for such engines.
2. Description of the Prior Art
The combustion chamber of certain gas turbine engines may be an annular tube with a plurality of fuel injectors or nozzles that are spaced apart circumferentially. Each fuel injector in such an arrangement must be efficient and provide a proper distribution of an atomized fuel and air mixture in the zone surrounding the particular injector. Preferably this mixture is distributed as a conical spray. It is also important that the fuel be atomized in order to promote efficient burning of the fuel in the combustion chamber. The control of the spray cone can be effected by providing a swirl to the mixture as it leaves the injector. The swirl can be provided by deflectors or directing air jets to provide a vortex. However, such devices are often spaced apart from the actual fuel nozzles forming part of the fuel injector.
U. S. Pat. 5,579,645, issued Dec. 3, 1996 to the applicant, describes a fuel nozzle having first and second annular air passages and an annular fuel passage between the first and second air passages. The result is a conical air-fuel-air sandwich which greatly enhances the formation of atomized fuel droplets in order to improve the efficient burning of the fuel. It has been found that in some cases the spray cone formed by the nozzle is too wide and results in wall impingement. Therefore, there is a need to control the angle and pattern of the spray cone.
SUMMARY OF THE INVENTION
It is, therefore, an aim of the present invention to provide an improved fuel injector that answers some of the needs that have been identified but is not presently being addressed by existing fuel injector technology.
It is also advantageous to provide a higher air-to-fuel ratio; yet given the constraints with present fuel injector designs, it is difficult to increase this ratio.
It is a further aim of the present invention to design a fuel injector for a gas turbine that has a compact arrangement of nozzles and passages for supplying both air and fuel to form a diverging spray of a mixture of atomized fuel and air with an increased air-to-fuel ratio.
It is a further aim of the present invention to provide a more controlled spray shape.
In a construction in accordance with the present invention, there is a fuel injector for a combustor in a gas turbine engine, wherein the fuel injector includes a fuel tip protruding inwardly of the combustor along a tip axis and defining a primary fuel nozzle along the tip axis, a valve for metering the fuel through the primary fuel nozzle of the fuel injector, the valve comprising a spiral vane disposed within a fuel chamber in the tip to provide a spiral fuel flow path through a portion of the fuel chamber to the primary fuel nozzle, wherein the primary fuel nozzle is used for ignition purposes.
In another aspect of the present invention, there is a fuel injector for a combustor in a gas turbine engine, wherein the combustor includes a combustor wall defining a combustion chamber tube surrounded by pressurized air, the injector comprising an injection tip assembly adapted to protrude, in use, through the combustor wall into the chamber, the injector tip including a first air passage forming an annular array communicating the pressurized air from outside the wall into the combustion chamber, a second air passage made up of an annular array of individual air passages spaced radially from the first air passage for communicating pressurized air from outside the wall into the combustion chamber, a first fuel gallery extending through the fuel injector tip and defining an annular fuel nozzle between the first air passage and the second air passages whereby the second air passage is arranged to atomize the fuel emanating from the first fuel nozzle, and a set of third air passages arranged in annular array in the injector tip spaced radially outwardly from the second air passages whereby air from the third passages is arranged to shape the spray of the mixture of atomized fuel and air and to add supplemental air to the mixture.
In a more specific embodiment of the present invention, there is provided a fuel tip with a second fuel gallery communicating with an axial fuel nozzle concentric and central to the first air passage, wherein the second fuel gallery is effective to supply primary fuel for ignition purposes.
REFERENCES:
patent: 1875457 (1932-09-01), Hemmingsen
patent: 3076607 (1963-02-01), Cordier
patent: 3129891 (1964-04-01), Vdoviak
patent: 4491272 (1985-01-01), Bradley et al.
patent: 5127346 (1992-07-01), Kepplinger et al.
patent: 6141968 (2000-11-01), Gates
patent: 493434 (1938-11-01), None
Astle Jeffrey W.
Gartenberg Ehud
Pratt & Whitney Canada Corp.
Thorpe Timothy S.
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