This invention relates generally to combustors for gas turbine engines and more particularly to a method of repairing an annular dome of a combustor.
In gas turbine engines, compressed air is mixed with fuel and burned within a combustor to produce high-temperature working gases, which are directed to one or more downstream turbines for work extraction. A known type of combustor includes an annular dome attached to annular inner and outer liners which define a combustion chamber therebetween. Fuel injection devices are attached to the combustor in flow communication with the dome and supply fuel to the combustion chamber. The dome includes a structural dome plate carrying a plurality of swirler assemblies. Each swirler assembly includes an air swirler, and a divergent deflector assembly which extends aft from the swirler to prevent hot combustion gases from impinging upon the dome plate. The deflector assembly is comprised of a cylindrical sleeve and a deflector plate, attached at a cylindrical interface.
In some engines, the combustor dome experiences heavy “burning” (i.e. localized overheating) and oxidation of the sleeve and deflector plate. Prior art repair methods require either complete replacement of the dome with a newly manufactured dome, or repair of the dome by removal and replacement of the sleeve and deflector plate. Unfortunately, removal of the sleeve and deflector plate while preserving the geometric features of the swirler requires expensive and complex machining processes, such as wire electrodischarge machining (EDM).
Accordingly, there is a need for a method of replacing a combustor deflector plate and or sleeve using simple machining processes.
The above-mentioned need is met by the present invention, which according to one aspect provides a method of repairing a swirler assembly having a first deflector component attached to a swirler having a first joint configuration, including: removing the first deflector component; machining a second joint configuration different from the first joint configuration in the swirler; providing a replacement deflector component having a sleeve with a shape complementary to the second joint configuration; and securing the replacement deflector component to the swirler.
According to another aspect of the invention, a method of repairing a combustor dome for a gas turbine engine includes: providing a combustor having: a swirler defining a first joint configuration for receiving a deflector component; and a first deflector component having: a sleeve with generally conical aft section; and a generally cylindrical forward section complementary to the first joint configuration, wherein the forward section is secured to the swirler; removing the first deflector component; machining a second joint configuration different from the first joint configuration into the swirler; providing a replacement deflector component having a shape complementary to the second joint configuration; and securing the replacement deflector component to the swirler.
The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:
Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,
The deflector assembly 23 is comprised of the sleeve 27 and deflector plate 29. In some instances these may be a single integral part. The sleeve 27 of the deflector assembly 23 has a generally conical aft section 44 and a generally cylindrical forward section 46. The forward cylindrical end 46 of the sleeve 27 is formed into an axially-extending tang 48 of reduced thickness which is received in the swirler groove 42. In the illustrated example, the axial length of the tang 48 is selected so that an attachment slot 50 is present between the tang 48 and the base of the swirler groove 42. This provides space to put alloy material for the purpose of bonding the two parts. During initial manufacture, the dome 18 including the swirler assemblies 22 and deflector assemblies 23 are put through a high temperature furnace cycle sufficient to cause the alloy material to melt and flow. As a result the swirler assemblies 22 and deflector assembly 23 are thus securely bonded together. By the original process, when replacement of the deflector assembly 23 or subfeatures are required, it may not be cost effective or desirable to machine and disassemble the deflector assemblies from the entire dome 18. In the prior art, this leads to the replacement of the deflector assemblies 23 by using a process such as EDM to machine them away while maintaining the integrity of the swirler groove 42.
The dome 18 may be repaired in accordance with the present invention as follows. First, the dome 18 is separated from the rest of the combustor 10 to expose the dome plate 20, individual swirler assemblies 22 and deflector assemblies 23. Next, the original deflector assembly 23 is removed from the swirler assembly 22. In contrast to prior art repair methods, there is no need to preserve the swirler groove 42. This allows the use of simple machining methods. For example, the original deflector 23 may be cut away with an ordinary end-mill. Alternatively, the deflector assembly 23 could be removed in two steps by first separating the swirler 22 from the sleeve 27 with a mill or a fly-cutter, for example along line “L” in
Once the original deflector assembly 23 is removed, a lap joint geometry is machined into the aft end of the aft section 36 of the secondary swirler 26. As shown in
As with the original deflector assembly 23, the replacement deflector sleeve 127 and deflector plate similar to deflector plate 29 (not shown) may be cast or otherwise formed from a suitable high-temperature alloy such as a Mar-M-509 cobalt-based alloy. Alternatively, the replacement deflector sleeve 127 or deflector plate may be constructed from different materials, preferably an alloy having enhanced oxidation resistant material properties. It is often the case that during the service life of a gas turbine engine component, improved alloys suitable for use with such components are developed. Traditionally, engine operators would have to replace existing dome assemblies with a new dome containing components fabricated from the improved alloy to realize the enhanced material properties. However, by fabricating the replacement deflector assembly 123 or sleeve 127 or deflector plate from the improved alloy, the repaired combustor 10 may obtain, in part, the enhanced material properties and resultant extended service life.
A suitable braze alloy, is placed on the radiused surface R2. The replacement deflector sleeve 127 or deflector plate is then assembled and placed in the secondary swirler 26 so that it engages the swirler groove 42, forming a lap joint 54, as shown in
It has been found that the above-described repair method will be much more cost-effective than either complete replacement of the dome assembly 18 or prior art methods of deflector assembly replacement. Analysis has also shown that an acceptable joint in terms of strength and operational durability is created while requiring significantly less machining effort than the original joint.
The foregoing has described a method for repairing a combustor dome. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation, the invention being defined by the claims.