Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
2000-05-25
2001-09-18
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
Reexamination Certificate
active
06289677
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. No. 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.
A construction in accordance with the present invention comprises 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, along a tip axis through the combustor wall into the chamber, the injector tip including a first air passage forming an annular array of individual air passages spaced radially from the tip axis for communicating pressurized air from outside the wall into the combustion chamber, a fuel gallery extending through the fuel injector tip and defining an annular fuel nozzle radially inwardly from the first air passage whereby the first air passage is arranged to atomize the fuel emanating from the fuel nozzle, and a set of second air passages arranged in annular array in the injector tip spaced radially outwardly from the first air passages whereby air from the second 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, each passage in the first and second air passages is formed with an axial component and an inwardly directed component which is the result of an inwardly directed angle offset and parallel to a plane extending through the axis of the injector tip in order to provide a swirl to the mixture.
REFERENCES:
patent: 3067582 (1962-12-01), Schirmer
patent: 4689961 (1987-09-01), Stratton
patent: 5351489 (1994-10-01), Okamoto et al.
patent: 5579645 (1996-12-01), Prociw et al.
patent: 6082113 (2000-07-01), Prociw et al.
Prociw Lev Alexander
Sampath Parthasarathy
Astle Jeffrey W.
Gartenberg Ehud
Pratt & Whitney Canada Corp.
Thorpe Timothy S.
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