Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
2000-01-13
2001-11-13
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
Reexamination Certificate
active
06314739
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to gas turbine engine combustors and, more specifically, to a combustor dome assembly.
2. Description of Related Art
A conventional gas turbine engine combustor includes radially spaced outer and inner combustor liners 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 combustor 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.
A significant consideration in the design of the gas turbine engine combustor is serviceability of the life-limiting parts therein. For example, a typical dome assembly includes a baffle extending from the air swirler and spaced from the combustor dome for providing a channel therebetween for channeling compressor air for cooling at least the baffle itself. The baffle is subject to intense heating from combustion and, thus, is one life-limiting part which is replaced at periodic intervals.
The baffle is typically welded and/or brazed to the dome and, typically, requires replacement of the entire dome assembly therewith or substantial disassembly work at the periodic service intervals. Such baffle replacement. service is relatively expensive and requires a significant amount of time. U.S. Pat. No. 5,117,637 entitled “Combustor Dome Assembly” discloses a gas turbine engine combustor dome assembly mounting ring fixedly joined to the dome around a dome eyelet in a combustor dome. A baffle and a carburetor are fixedly joined to the mounting ring. The carburetor is joined to the mounting ring by its air swirler. The mounting ring is designed for assembly with reduced stackup clearances and easy disassembly for servicing. Each mounting ring is fixedly joined to a respective dome eyelet by welding or brazing. U.S. Pat. No. 5,117,637 is incorporated herein by reference.
The mounting ring also provides sealing and air leakage control between the air swirler of the carburetor and dome which results in good combustor performance and a good Pattern Factor. Leakage control is expensive to provide. Other designs have a lower cost dome assembly which has more leakage and produces a higher less desirable Pattern Factor. It is highly desirable to provide a low cost dome assembly which has been demonstrated to provide good leakage control. It is also desirable to provide a low cost dome assembly which eliminates brazed joints.
SUMMARY OF THE INVENTION
An exemplary embodiment of the invention is a dome assembly for a gas turbine engine combustor having an annular dome with a substantially conical front portion herein after referred to as a dome plate and at least one circular opening in the dome plate. The dome assembly further includes a seal plate having a central ring circumscribed about a centerline axis. A seal plate flange is disposed about a forward end of the central ring. The central ring is disposed through the circular opening and includes a central bore coaxially aligned with the circular opening.
A baffle with a cylindrical tubular mounting portion extending upstream through the central bore is fixedly joined to the seal plate and a flare portion of the baffle extends aft from the seal plate. A carburetor including an air swirler having an annular exit cone is joined to the baffle with the exit cone disposed within the cylindrical tubular mounting portion of the baffle. The exit cone includes an annular radially outwardly extending annular cone flange, an annular barrel extending aftwardly from the cone flange, and a radially inwardly facing annular inner cone surface for channeling air thereover and downstream over the baffle flare portion.
An aft end of the central ring is joined to the dome plate by a swage joint. The swage joint is preferably formed by bending the aft end of the central ring with swaging so that it is inclined radially outwardly against the chamfer along a circumference of the circular opening in the dome plate. The seal plate flange preferably includes a flat forward facing surface and has a rounded comer triangular shape with three wings having radially outer arcuate edges with respect to the centerline axis. The seal plate is joined to the dome plate by second tack welds between the seal plate flange and the dome plate at three locations wherein each of the locations is between each of the three wings. Legs extend axially aftwardly from an aft facing surface of the seal plate flange to contact the dome plate wherein each of the legs is located about midway between each two of the three wings and the second tack welds are between the legs and the dome plate.
The seal plate flange triangular shape is preferably formed from a circle truncated along three straight lines forming three straight edges of the seal plate flange and each of the legs is located along a respective one of the straight edges. First tack welds between a flange edge of an annular flange of the exit cone and the wings of the seal plate flange fixedly join the carburetor to the seal plate. The cylindrical tubular mounting portion of the baffle is fixedly joined to the seal plate by third tack welds along the forward end of the central ring.
Dome cooling holes disposed through the dome plate are circumferentially spaced and located radially inwardly, with respect to the centerline axis, of the radially outer arcuate edges of the wings of the seal plate. An undercut is formed in each of the aft facing surfaces along radially outer portions of the wings of the seal plate flange and is axially disposed in front of at least some of the dome cooling holes which are axially inline with the wings. An undercut groove is formed in the aft facing surface along a circular intersection between the seal plate flange and the central ring.
One advantage of the seal plate and dome assembly of the present invention is that they provide inexpensive and good sealing and air leakage control between the air swirler of the carburetor and dome which results in good combustor performance and a good Pattern Factor. The present invention is also advantageous because it uses a swage operation instead of braze operation to attach the seal plate to the dome. The seal plate also provides easy removal of the swirler and baffle, while minimizing leakage and providing dimensional control.
REFERENCES:
patent: 4974416 (1990-12-01), Taylor
patent: 5117637 (1992-06-01), Howell et al.
patent: 5623827 (1997-04-01), Montry
patent: 5916142 (1999-06-01), Snyder et al.
patent: 6035645 (2000-03-01), Bensaadi et al.
Carita Robert G.
Howell Stephen J.
Waslo Jennifer
Freay Charles G.
General Electric Company
Hess Andrew C.
Rodriguez William H
Young Rodney M.
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