Patent Grant
7131273
1. Field of the Invention
This invention relates to carburetors for gas turbine engine combustors and, more particularly, to such carburetors having primary and secondary air swirlers and designed for mounting in combustor domes.
2. Description of Related Art
Gas turbine engine combustors include carburetors for mixing fuel with compressed air to form an air/fuel mixture for combustion in a combustion zone of the combustor. One type of conventional gas turbine engine combustor includes radially spaced outer and inner combustor liners surrounding the combustion zone and joined at an upstream end thereof by a combustor dome. The combustor dome is typically made of sheet metal and is part of a combustor dome assembly that includes a plurality of circumferentially spaced carburetors therein, with each carburetor including a fuel injector for providing fuel and an air swirler for providing swirled air for mixing with the fuel for creating a fuel/air mixture discharged into the combustion zone between the two liners.
The mixture is burned for generating combustion gases which flow downstream or aftwardly through the combustor to a turbine nozzle suitably joined to the aft end of the combustor. Immediately downstream of the turbine nozzle is a high-pressure turbine which extracts energy from the combustion gases for powering a compressor disposed upstream of the combustor which provides compressed air to the engine.
Each of the carburetors includes forward and aft air swirlers respectively, also referred to as primary and secondary swirlers, respectively, having a longitudinal carburetor axis. The aft swirler includes a septum which defines a primary venturi of the carburetor. The aft swirler includes a plurality of circumferentially spaced aft swirl vanes and an annular exit cone, all formed together in an integral casting. The forward swirler includes a ferrule for slidably supporting a fuel injector. The forward swirler includes a plurality of circumferentially spaced forward swirl vanes and a flat annular radial flange attached thereto.
The radial flange of the forward swirler is slidably retained against a forward facing surface of the septum of the aft swirler by a retainer attached to the septum. The retainer has a wide aperture in the middle allowing it to slide over the forward swirl vanes and engage an outer edge of the flat annular radial flange which is wider than the aperture. A ridge along a periphery of the retainer extends aftwardly from an aft face of the retainer. A small notch machined into the ridge receives a narrow anti-rotation tab extending radially outwardly from a periphery of the radial flange of the forward swirler.
The ridge of the retainer is brazed, welded, or otherwise bonded or attached to the forward facing surface of the septum. This secures the forward swirler to the aft swirler while allowing for differential thermal growth between the fuel injector and the combustor dome while preventing relative rotation between the forward and aft swirlers. This helps set, control, and maintain desirable Pattern Factors.
The retainer is formed from a retainer casting and its final shape including the ridge and notch features are machined into the retainer casting. The primary swirler typically has a narrow anti-rotation tab that engages the notch to prevent relative rotation between the primary and secondary swirlers. The narrow tab is subject to fretting from engine cycles and, thus, prone to failure. The primary and secondary swirlers and the retainer are delicate and prone to damage during fabrication and from handling during assembly and maintenance and from engine operating loads. The primary and secondary swirlers and retainer plate are extensively machined at their mating surfaces which is costly. It is, thus, desirable to provide a carburetor and its parts that are not as delicate and prone to damage during fabrication and from handling and during engine operation from vibratory engine operating loads.
A gas turbine engine combustor carburetor includes forward and aft air swirlers. The aft swirler has a septum defining a primary venturi and a plurality of circumferentially spaced aft swirl vanes. The forward swirler has a plurality of circumferentially spaced forward swirl vanes extending forwardly from a flat annular radial flange of the forward swirler. The aft swirler includes an annular wall extending forwardly from a forward face of the septum and radially bounding an annular recess on the forward face. The radial flange of the forward swirler is slidably retained within the annular recess and against the septum by a flat retainer attached to the annular wall of the septum. The flat retainer may be produced by stamping.
An exemplary embodiment of the carburetor includes an anti-rotation tab on the radial flange of the forward swirler that extends radially through a corresponding notch in the annular wall. More particular embodiments of the anti-rotation tab are rectangular in shape and have a width at least 33% of a forward swirler flange diameter of the forward swirler or at least 20% of the forward swirler flange diameter or in a range of between 20%–33% of the forward swirler flange diameter. Yet, more particular embodiments of the anti-rotation tab have a width of at least 0.2 inches.
The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawings where:
Illustrated in
At its upstream end, the combustor 10 includes the dome assembly 20 having an annular combustor dome 21 with an annular dome plate 22 at its upstream end and disposed coaxially about the centerline 16 which is conventionally fixedly connected to upstream ends of the liners 12 and 14. The annular dome plate 22 is a forward substantially conical portion of the annular combustor dome 21. The combustor dome assembly 20 includes a plurality of circumferentially spaced carburetors 24 which are additionally shown in
Illustrated in
The forward swirler 25 centrally supports a ferrule 66 for slidably supporting a fuel injector 30 (see
Illustrated in greater detail in
The wide anti-rotation tab 86 has a tab width W in a preferential range of about 20% to 33% of a forward swirler flange diameter D1 of the forward swirler 25. Wider anti-rotation tab 86 also allows more economical gang grinding operation to be used in the manufacturing process. A wide anti-rotation tab 86 having the tab width W in excess of 33% of the forward swirler flange diameter D1 provides manufacturing benefits, but durability is probably not significantly enhanced over one with a tab width of 20% of the forward swirler flange diameter D1. It is also recommended that the tab width W not be less than 0.2 inches. Narrow tabs in past designs have been in a range of 7% to 17%.
Referring back to
The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. While there have been described herein, what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein and, it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention.
Accordingly, what is desired to be secured by Letters Patent of the U.S. is the invention as defined and differentiated in the following claims.
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| Number | Date | Country | |
|---|---|---|---|
| 20060130483 A1 | Jun 2006 | US |
