Abstract:
A fuel nozzle assembly for delivering fuel to a combustor of a gas turbine engine. The assembly includes a fuel nozzle including a body having a fuel inlet, an air inlet, an outlet for discharging fuel to the combustor, and a mounting flange for mounting the nozzle in the engine. A portion of the body corresponding to the fuel inlet and/or the air inlet includes a recess for receiving a supply fitting having an annular sealing surface and a rotatable nut. The recess includes an annular seat sized and shaped for sealingly engaging the sealing surface of the supply tube fitting and female threads positioned adjacent the seat for threadably receiving the rotatable nut of the supply.

Description:
[0001] This invention was made with government support under a grant from the U.S. Army (DAAE07-00-C-N086). The U.S. government has certain rights in this invention. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to gas turbine engine fuel nozzles, and more particularly to a fitting for connecting a nozzle to a supply line.  
           [0003]    Gas turbine engines generally have a compressor section for compressing flowpath air traveling through the engine, a combustor downstream from the compressor section for heating the compressed flowpath air, and a turbine section downstream from the combustor for removing energy from the heated flowpath air to drive the compressor section. The combustor includes fuel nozzles for delivering fuel to the combustor. The fuel nozzles have a fuel inlet that connects to a fuel supply line and an outlet that delivers the fuel to the combustor. Conventionally, the fuel nozzle inlet is formed as a protrusion having a rounded sealing surface and external threads. The fuel supply line has an annular conical seat that mates with the rounded sealing surface. An internally threaded nut is used to connect the fuel supply line to the inlet and hold the annular seat in sealing engagement with the rounded sealing surface.  
           [0004]    In some applications, a frame surrounds the combustor immediately outside the fuel nozzles, and the fuel nozzles are cooled with cooling air. A separate cooling air supply line is provided for delivering the cooling air to passages extending through the nozzle. A protruding inlet similar to that used for the fuel supply line cannot be used to connect the cooling air supply line to the fuel nozzle because such an inlet configuration does not provide sufficient radial clearance between the fuel nozzles and the surrounding frame during assembly. Thus, there is a need for a fuel nozzle having a low profile cooling air inlet.  
         SUMMARY OF THE INVENTION  
         [0005]    Briefly, the present invention includes a fuel nozzle assembly for delivering fuel to a combustor of a gas turbine engine. The assembly comprises a fuel nozzle including a body having a fuel inlet for receiving fuel from a fuel supply, an air inlet for receiving air from an air supply, an outlet for discharging fuel to the combustor of the gas turbine engine, and a mounting flange for mounting the nozzle in the engine so the fuel inlet and air inlet are positioned outside the combustor and the nozzle outlet is positioned inside the combustor. A portion of the body corresponding to at least one of the fuel inlet and the air inlet includes a recess for receiving a supply fitting having an annular sealing surface and a rotatable nut. The recess includes an annular seat sized and shaped for sealingly engaging the sealing surface of the supply tube fitting and female threads positioned adjacent the seat for threadably receiving the rotatable nut of the supply fitting to releasably fasten the supply tube to the fuel nozzle and hold the sealing surface of the supply tube in sealing engagement with the seat of the fuel nozzle.  
           [0006]    Other features of the present invention will be in part apparent and in part pointed out hereinafter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a partial cross section of a gas turbine engine having a fuel nozzle assembly of the present invention; and  
         [0008]    [0008]FIG. 2 is a detail of FIG. 1 showing the fuel nozzle assembly of the present invention.  
         [0009]    Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0010]    Referring now to the drawings and in particular to FIG. 1, a fuel nozzle assembly of the present invention is designated in its entirety by the reference numeral  20 . The assembly  20  delivers fuel to a combustor, generally designated by  22 , of a gas turbine engine, generally designated by  24  (partially shown). The fuel is ignited in the combustor  22  to heat flowpath air passing through the combustor. The combustor  22  is operatively positioned between a compressor  26  positioned upstream from the combustor for compressing the flowpath air before it enters the combustor and a turbine (not shown) positioned downstream from the combustor for driving the compressor. A frame, generally designated by  28 , is mounted between the compressor  26  and the combustor  22 . The frame  28  includes a forward flange  30  and an aft flange  32  spaced by a truss  34  allowing for movement between the compressor  26  and the combustor  22  as the engine heats up and cools down. The forward flange  30  and aft flange  32  are connected to the compressor  26  and the combustor, respectively, using conventional threaded fasteners (not shown).  
         [0011]    The fuel nozzle assembly  20  comprises a fuel nozzle  40 , a fuel supply line  42  for delivering fuel to the nozzle from a fuel supply  44 , a cooling air supply line  46  for delivering cooling air to the nozzle from an air supply  48 , and connectors  50 ,  52  for releasably connecting the fuel supply line and the cooling air supply line, respectively, to the nozzle. As illustrated n FIG. 2, the nozzle  40  includes a body  60  having a fuel inlet  62  for receiving fuel from the fuel supply line  42 , a cooling air inlet  64  non-concentrically positioned with respect to the fuel inlet for receiving cooling air from the cooling air supply line  46 , an outlet  66  for discharging fuel to the combustor  22  of the gas turbine engine  24 , and a mounting flange  68  for mounting the nozzle on the combustor.  
         [0012]    In one embodiment, the fuel inlet  62  includes a protrusion having a rounded sealing surface  70  and external threads  72  forming a fuel supply fitting. The fuel supply line  42  includes an annular conical seat  74  that sealingly engages the rounded sealing surface  70  of the body  60 . As will be appreciated by those skilled in the art, the shapes of the sealing surface  70  and seat  74  may be modified without departing from the scope of the present invention. For example, the sealing surface  70  may have a conical shape corresponding to that of the seat  70 . Although the annular seat  74  may have other included cone angles without departing from the scope of the present invention, in one embodiment the surface has an included cone angle or apex angle of about 74 degrees. In one embodiment, the fuel supply connector  50  is a nut having internal threads  76  for releasably connecting the fuel supply line  42  to the nozzle  40  so the rounded sealing surface  70  and the annular seat  74  are in sealing engagement. The connector  50  includes an elongate body  78  having a hexagonal wrenching surface  80  opposite the threads for turning the connector about a turning axis  82  to tighten and loosen the connector during assembly and disassembly. As will be appreciated by those skilled in the art, the wrenching surface  80  is sufficiently spaced from the threads  76  of the connector  50  so that the wrenching surface is positioned outside the truss  34  of the frame  28  when the connector is fully tightened. Thus, the elongate body  78  provides clearance for using a wrench to connect the fuel supply line  42  to the nozzle  40 . The connector  50  and fuel supply line  42  have inter-engaging shoulders  84 ,  86 , respectively, so the connector clamps the annular seat  74  of the fuel supply line  42  against the rounded sealing surface  70  of the body  60  as the connector is tightened. As will be appreciated by those skilled in the art, the resulting line contact between the annular seat  74  and the rounded sealing surface  70  provides a repeatable, fluid-tight seal at the interface.  
         [0013]    Further, the cooling air inlet  64  includes a recess having an annular conical seat  90  and internal threads  92  forming a cooling air supply fitting. The cooling air supply line  46  includes a rounded sealing surface  94  that sealingly engages the annular seat  90  of the body  60 . As will be appreciated by those skilled in the art, the shapes of the seat  90  and the sealing surface  94  may be modified without departing from the scope of the present invention. For example, the sealing surface  94  may have a conical shape corresponding to that of the seat  90 . Although the annular seat  90  may have other included cone angles without departing from the scope of the present invention, in one embodiment the seat has an included cone angle or apex angle of about 74 degrees. In one embodiment, the cooling air supply connector  52  is a nut having external threads  96  for releasably connecting the cooling air supply line  46  to the nozzle  40  so the annular seat  90  and rounded sealing surface  94  are in sealing engagement. The connector  52  includes an elongate body  98  having a hexagonal wrenching surface  100  opposite the threads for turning the connector about a turning axis  102  to tighten and loosen the connector during assembly and disassembly. As will be appreciated by those skilled in the art, the wrenching surface  100  is sufficiently spaced from the threads  96  of the connector  52  so the wrenching surface is positioned outside the truss  34  of the frame  28  when the connector is fully tightened. Thus, the elongate body  98  provides clearance for using a wrench to connect the cooling air supply line  46  to the nozzle  40 . The cooling air supply line  46  has a shoulder  104  that the connector  52  engages so the connector clamps the rounded sealing surface  94  of cooling air fuel supply line  46  against the annular seat  90  of the body  60  as the connector is tightened. As will be appreciated by those skilled in the art, the resulting line contact between the annular seat  90  and the rounded sealing surface  94  provides a repeatable, fluid-tight seal at the interface.  
         [0014]    As will be apparent to those skilled in the art, the recessed configuration of the cooling air inlet  64  provides a lower profile than the protruding configuration of the fuel inlet  62 . Thus, the fuel nozzle bodies  60  may be mounted on the combustor  22  before the combustor and frame  28  are assembled. Although the body may be mounted on the combustor  22  in other ways with departing from the scope of the present invention, in one embodiment, the mounting flange  68  is fastened to the combustor with a screw fastener  106 . A seal  108  is provided between the flange  68  and the combustor  22  to seal the interface between the flange and the combustor. The nozzle body  60  extends through a hole  110  in the combustor  22  so that the nozzle outlet  66  is positioned inside the combustor and the fuel inlet  62  and cooling air inlet  64  are positioned outside the combustor when the flange is fastened to the combustor.  
         [0015]    The shorter profile of the cooling air inlet  64  permits the mounted nozzle bodies  60  to slide inside the frame  28  during assembly without interfering with the frame. Once the combustor  22  and frame  28  are assembled. The fuel supply line  42  and cooling air supply line  46  may be connected to the fuel inlet  62  and cooling air inlet  64 , respectively, and the connectors  50 ,  52  may be tightened to seal the respective sealing surfaces.  
         [0016]    When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.  
         [0017]    As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.