Abstract:
A method for fabricating a dome assembly for a gas turbine engine combustor includes forming an annular dome plate including a plurality of substantially circular eyelets circumferentially spaced thereon, coupling a seal plate to the dome plate at each eyelet such that an opening defined in each seal plate is aligned substantially concentrically with respect to a respective eyelet, coupling a baffle to each seal plate such that an opening defined in each baffle is aligned substantially concentrically with respect to a respective eyelet, and coupling a swirler assembly having an integrally formed swirler and flare cone to each seal plate such that the flare cone extends at least partially through the baffle opening, and such that cooling air may be directed towards the flare cone through openings formed in the assembly.

Description:
BACKGROUND OF THE INVENTION 
   This application relates generally to gas turbine engines and, more particularly, to combustors for gas turbine engine. 
   At least some known gas turbine engines include a compressor that provides compressed air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. The gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as to power an aircraft in flight. 
   At least some known combustors used in gas turbine engines typically include inner and outer combustion liners joined at their upstream ends by a dome assembly. The dome assembly includes an annular spectacle plate or dome plate and a plurality of circumferentially spaced swirler assemblies or cups. Fuel is supplied to the dome where it is mixed with air discharged from the swirler assemblies to create a fuel/air mixture that is channeled to the combustor. Known combustors include a baffle that is exposed to high temperatures generated during the combustion process, and cooling air passages that channel cooling air to the baffle. Known cooling air channels do not regulate a precise air flow to the baffle, but rather, the cooling air is forced through gaps defined between the edges of the dome plate and the baffle. 
   In at least one known combustor, the dome assembly is manufactured by a brazing process, wherein the swirler assemblies and baffles are brazed to the dome plate. The brazing process may be a time consuming and labor-intensive procedure that may require the use of multiple fixtures and many expensive materials. Typically, at least some of the braze joints may be difficult to inspect, and may require considerable rework. Moreover, in at least one known combustor dome assembly, repairs are difficult or impossible, in that the repair of a brazed component requires that the dome assembly go through a braze oven which may undesireably cause damage to joints that previously did not require repair. 
   BRIEF SUMMARY OF THE INVENTION 
   In one aspect, a method for fabricating a dome assembly for a gas turbine engine combustor is provided. The method includes forming an annular dome plate including a plurality of substantially circular eyelets circumferentially spaced thereon, coupling a seal plate to the dome plate at each eyelet such that an opening defined in each seal plate is aligned substantially concentrically with respect to a respective eyelet, coupling a baffle to each seal plate such that an opening defined in each baffle is aligned substantially concentrically with respect to a respective eyelet, and coupling a swirler assembly having an integrally formed swirler and flare cone to each seal plate such that the flare cone extends at least partially through the baffle opening, and such that cooling air may be directed towards the flare cone through openings formed in the assembly. 
   In another aspect, a dome assembly for a gas turbine engine combustor is provided that includes at least one swirler assembly that includes a primary swirler and a secondary swirler. The secondary swirler is formed integrally with a flare cone, and the secondary swirler includes a cooling circuit formed therein channeling cooling air towards the flare cone. 
   In a further aspect, a gas turbine engine is provided. The gas turbine engine includes a combustor that includes at least one dome assembly. The at least one dome assembly includes at least one swirler assembly including a primary swirler and a secondary swirler. The secondary swirler is formed integrally with a flare cone. The secondary swirler includes a cooling circuit defined therein for channeling cooling air towards the flare cone. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic illustration of a gas turbine engine; 
       FIG. 2  is a schematic cross-sectional view of a combustor that may be used with the gas turbine engine shown in  FIG. 1 ; 
       FIG. 3  is a perspective view of a dome plate; and 
       FIG. 4  is an enlarged cross-sectional view of the dome assembly shown in  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a schematic illustration of a gas turbine engine  10  including a low pressure compressor  12 , a high pressure compressor  14 , and a combustor  16 . Engine  10  also includes a high pressure turbine  18 , and a low pressure turbine  20  arranged in a serial, axial flow relationship. Compressor  12  and turbine  20  are coupled by a first shaft  24 , and compressor  14  and turbine  18  are coupled by a second shaft  26 . In one embodiment, gas turbine engine  10  is a CF34-3 engine commercially available from General Electric Company, Cincinnati, Ohio. 
   In operation, air flows through low pressure compressor  12  from an upstream side  28  of engine  10 . Compressed air is supplied from low pressure compressor  12  to high pressure compressor  14 . Highly compressed air is then delivered to combustor assembly  16  where it is mixed with fuel and ignited. Combustion gases are channeled from combustor  16  to drive turbines  18  and  20 . 
     FIG. 2  is a cross-sectional view of a combustor, such as combustor  16 , that may be used with gas turbine engine  10 . Combustor  16  includes an inner liner  30  and an outer liner  32 . Inner and outer liners  30  and  32  are joined at an upstream end  36  by a dome assembly  40 . The cross section shown in  FIG. 2  is taken through one of a plurality of swirler assemblies  42  that are mounted on dome assembly  40 . A fuel line  44  delivers fuel to a fuel injector (not shown) that supplies fuel to an inlet  46  of swirler assembly  42 . Fuel is mixed with air in swirler assembly  42  and the fuel/air mixture is introduced into combustor  16  from an outlet  48  of swirler assembly  42 . 
     FIG. 3  is a perspective view of a dome plate  52  that forms a part of dome assembly  40 . Dome plate  52  is an annular member having a substantially circular profile. Dome plate  52  includes a plurality of openings or eyelets  54  circumferentially spaced between an inner radius R 1  and an outer radius R 2  of dome plate  52 . Dome plate  52  has a forward or upstream facing side  56  and an aft or downstream facing side  58 . A bushing or seal plate  60  is mounted on dome plate  52  at each eyelet  54 . Dome plate  52  also includes an inner circumferential flange  62  and an outer circumferential flange  64  that are used to couple dome assembly  40  to combustor  16 . In the exemplary embodiment, dome plate  52  is formed by a stamping operation and seal plate  60  is brazed to dome plate  52 . The braze is applied to aft side  58  of dome plate  52  and flows to forward side  56 . The braze joint can be visually inspected from forward side  56  to confirm that the braze joint is complete. Brazing provides structural strength between dome plate  52  and seal plate  60 . 
     FIG. 4  is an enlarged cross-sectional view of dome assembly  40  shown in  FIG. 2 . Dome assembly  40  includes dome plate  52  with seal plate  60 , swirler assembly  42 , and a baffle  68 . Dome plate  52 , seal plate  60 , and baffle  68  are aligned coaxially with an axial centerline  70  of swirler assembly  42 . Swirler assembly  42  includes a primary swirler  74  and a secondary swirler  76 . 
   Primary swirler  74  includes a body  78  that is generally cylindrical in shape and includes fuel inlet  46  at a forward end  80 . Fuel inlet  46  opens into a fuel inlet channel  82  in body  78 . Body  78  includes a base  84  and a generally circular flange  86  that extends radially outward from base  84 . Flange  86  abuts secondary swirler  76 . A plurality of passageways  88  are formed in base  84 . Passageways  88  admit air into primary swirler  74  that mixes with fuel and imparts a swirling action to the fuel/air mixture. 
   Secondary swirler  76  includes a venturi section  90  from which a substantially circular flange  92  radially extends. A retainer ring (not shown) coupled to secondary swirler  76  holds primary swirler  74  in sliding engagement with secondary swirler  76 . Some movement is allowed between primary swirler  74  and secondary swirler  76  to facilitate installation of a fuel injector on primary swirler  74 . A flare cone section  96  is formed integrally with secondary swirler  76 . Flare cone section  96  includes an exit cone  98 , a substantially circular mid section  100 , and a substantially circular flange  102 . A plurality of swirler vanes  104  extend between flange  92  and flange  102 . Flanges  92  and  102  define a swirler vane channel  106  that circumscribes venturi  90 . Swirler vanes  104  are circumferentially spaced around venturi section  90  and are oriented so as to impart a swirling motion to air flowing through swirler vane channel  106 . Flare cone section  96  includes a cooling air circuit that directs cooling air against an underside  110  of exit cone  98 . 
   Venturi section  90  includes an outer wall  112  and an inner wall  114  that defines an axial flow path  116  that extends through venturi section  90  along axial centerline  70  of swirler assembly  42 . Venturi section  90  includes a throat  118  and a venturi exit  120 . Throat  118  has a converging-diverging cross sectional profile that extends from a forward facing surface  122  of flange  92  flange to venturi exit  120 . Venturi throat  118  has a minimum diameter D 1 . Venturi exit  120  extends into a throat  130  of flare cone section  96 . Venturi exit  120  has a an outer diameter D 2  that is less than an inner diameter D 3  of throat  130  of flare cone section  96  such that a space  132  circumscribes venturi exit  120 . Space  132  is in flow communication with swirler vane channel  106 . 
   Exit cone  98  of flare cone  96  includes an inner wall  134  that defines a flare cone flow path  136  that extends along axial centerline  70  of swirler assembly  42 . Flow path  136  culminates at swirler exit  48 . Exit cone  98  is exposed to a combustion zone (not shown) within combustor  16 . Flare cone section  96  is provided with a cooling circuit to cool exit cone  98 . Flange  102  includes air holes  140  circumferentially spaced around a perimeter  142  of flange  102 . Internal channels  144  cast into flange  102  and mid section  100  route cooling air to delivery holes  146  that direct cooling air to underside  110  of exit cone  98  to cool exit cone  98  and baffle  68 . In an alternative embodiment, internal channels  144  are machined into flange  102  and mid section  100 . 
   Baffle  68  is generally cylindrical in shape and includes a heat deflecting portion  150  that extends radially outward from an axial portion  152  that is coupled to seal plate  60 . In the exemplary embodiment, baffle  68  is welded to seal plate  60 . The welded attachment of baffle  68  to seal plate  60  facilitates repair and replacement of baffle  68 . 
   Dome assembly  40  is fabricated by first stamping a dome plate  52  that includes a plurality of substantially circular openings or eyelets  54 . A seal plate  60  is then brazed to dome plate  52  at each eyelet  54 . In the braze operation, braze is applied to an aft side  58  of dome plate  52 . Inspection of the braze joint is achieved visually by confirming the presence of braze filler from the forward side  56  of dome plate  52  after the braze heat cycle. In the exemplary embodiment, the seal plate-to-dome plate joint is the only brazed joint in dome assembly  40 , which facilitates service and repair and also reduces rework. After seal plate  60  is installed, a baffle  68  is coupled to seal plate  60 . In the exemplary embodiment, baffle  68  is welded to seal plate  60 . Seal plate  60  and baffle  68  are assembled such openings in seal plate  60  and baffle  68  are concentric with eyelets  54  in dome plate  52 . 
   Dome assembly  40  is completed by coupling a swirler assembly  42  having an integrally formed flare cone assembly  96  to each seal plate  60 . In coupling swirler assembly  42  to seal plate  60 , exit cone  98  of flair cone assembly  96  is passed through openings in eyelet  54 , seal plate  60 , and baffle  68 . In the exemplary embodiment, swirler assembly  42  is welded to seal plate  60 . 
   During operation, fuel is delivered to inlet  46  of primary swirler  74 . The fuel is mixed with air and the fuel/air mixture is channeled downstream through venturi section  90  of secondary swirler  76 . Fuel/air mixture exits venturi section  90  and is mixed with swirling air from swirler vane channel  106 . Flare cone section  96  receives swirled air from swirler vane channel  106  and a fuel/air mix from venturi section  90  that is discharged into throat  130  of flare cone section  96 . The fuel/air mixture is spread radially outward as it exits swirler assembly  42  through exit cone  98  and enters a burning zone within combustor  16 . Cooling air is channeled through flange  102  and delivered between baffle  68  and underside  110  of exit cone  98 . More specifically, cooling air is routed through channels  144  in flange  102  and directed towards underside  110  of exit cone  98 . 
   The above-described dome assembly for a gas turbine engine combustor is cost-effective and reliable. The dome assembly is fabricated with only one braze joint which facilitates service and repair and reduces rework during initial assembly. The integrity of the braze joint can be visually inspected after a braze oven heat cycle. The dome assembly includes a swirler assembly that has an integral flare cone that includes a cooling circuit to cool the flare cone and baffle. As a result, the fabrication costs of the dome assembly are reduced while serviceability and reliability are improved. 
   Exemplary embodiments of combustor dome assemblies are described above in detail. The assemblies are not limited to the specific embodiments described herein, but rather, components of each assembly may be utilized independently and separately from other components described herein. Each dome assembly component can also be used in combination with other dome assembly components. 
   While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.