Abstract:
A liquid fuel injection spoke for a gas turbine engine. The liquid fuel injection spoke may include an inlet end and an outlet end. The liquid fuel injection spoke may further include a head located at the inlet end and a stem extending along a longitudinal axis from the head to the outlet end. The stem may define a fluid passageway therein. The head may include a cavity with an inner wall. The inner wall may include an annular protrusion.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to a fuel injector, and more particularly, to a joint for a fuel injector spoke. 
       BACKGROUND 
       [0002]    Gas turbine engines (GTEs) produce power by extracting energy from a flow of hot gas produced by combustion of fuel in a stream of compressed air. In general, GTEs have an upstream air compressor coupled to a downstream turbine with a combustion chamber (combustor) in between. Energy is produced when a mixture of compressed air and fuel is burned in the combustor, and the resulting hot gases are used to spin blades of a turbine. In typical GTEs, multiple fuel injectors direct the fuel to the combustor for combustion. 
         [0003]    The GTE may commonly include a swirler vane adapted to impart a swirl to compressed air passing through the GTE. The swirler may include a liquid fuel injection spoke. The liquid fuel injection spoke may be joined to, and in fluid communication with, a liquid fuel manifold. As such, the liquid fuel injection spoke may be configured to inject liquid fuel into the compressed air stream flowing past the swirler. 
         [0004]    U.S. Pat. No. 5,613,363 to Joshi et al. (&#39;363 patent) discloses an air fuel mixer having a mixing duct, a set of swirlers, and a means for injecting fuel into the mixing duct. As shown in FIG.  8 , a plurality of spokes may be in communication with a fuel manifold such that the spokes may inject fuel into the mixing duct. Relevant to this disclosure, the &#39;363 patent fails to disclose a means of engagement between the plurality of spokes and the fuel manifold. 
       SUMMARY 
       [0005]    Embodiments of the present disclosure may be directed to a liquid fuel injection spoke for a gas turbine engine. The liquid fuel injection spoke may include an inlet end and an outlet end. The liquid fuel injection spoke may further include a head located at the inlet end and a stem extending along a longitudinal axis from the head to the outlet end. The stem may include a fluid passageway therein. The head may include a cavity with an inner wall. The cavity may form an inlet to the fluid passageway. The inner wall may include an annular protrusion. 
         [0006]    Further embodiments of the present disclosure may be directed to a fuel injector system. The fuel injector system may include a liquid fuel injection spoke defining a fluid passageway therethrough. The liquid fuel injection spoke may include an inlet end, an outlet end, and a stem extending to the outlet end. The liquid injection spoke may further include a head located at the inlet end. 
         [0007]    Still further embodiments of the present disclosure may be directed to a method of forming a joint in a turbine engine. The method may include inserting a liquid fuel injection spoke into an engine having a manifold. The method may further include applying a first deformation member to the liquid fuel injection spoke to deform the liquid fuel injection spoke. Additionally, the method may include materially bonding the liquid fuel injection spoke to the manifold via molecular diffusion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional illustration of an exemplary liquid fuel injection spoke in an exemplary liquid manifold of a fuel injector system; 
           [0009]      FIG. 2  is a cross-sectional view of the liquid fuel injection spoke of  FIG. 2 ; 
           [0010]      FIGS. 3A-3C  are cross-sectional views of the liquid fuel injection spoke and a swager; and 
           [0011]      FIG. 4  is a flow diagram of an exemplary method of forming a joint between the liquid fuel injection spoke and liquid manifold. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]      FIG. 1  illustrates an exemplary liquid fuel injection spoke  24  in an exemplary liquid manifold  26  of a fuel injector system  10  of a GTE. Fuel injector  10  may be configured to deliver fuel to the GTE. GTE may include a first portion (not shown) configured to receive compressed air from a compressor section of the GTE and a second portion (not shown) configured to deliver premixed compressed air and fuel to a combustor of the GTE. 
         [0013]    As shown in  FIG. 1 , a swirler  22  may be disposed within GTE between the first portion and the second portion. Swirler  22  may be configured to impart a swirl to compressed air delivered from the compressor of the GTE through first portion. Swirler  22  may include one or more liquid fuel injection spokes  24  fluidly connected to a liquid fuel manifold  26 . Liquid fuel injection spoke(s)  24  may be formed of any suitable material configured to withstand high temperatures. Manifold  26  may be made of any suitable manifold material such as. Liquid fuel injection spoke  24  may be configured to spray a stream of liquid fuel from manifold  26  into the swirled compressed air stream flowing past swirler  22 . 
         [0014]    As shown in  FIG. 1 , liquid fuel injection spoke  24  may include an enlarged head  30  and a stem  32  defining a fluid passageway  34  therethrough. Head  30  may be positioned within manifold  26  and configured to receive liquid fuel from manifold  26 . As shown, manifold  26  may include a manifold recess  26   a  configured to aid bonding between manifold  26  and head  30  as will be described in more detail below. Stem  32 , as shown in  FIG. 1 , may extend radially inwardly into swirler  22 . Swirler  22  may include a plurality of swirler vanes  22   a  extending radially inwardly. Stem  32  may be disposed in between any two of the plurality of swirler vanes  22   a.    
         [0015]      FIG. 2  illustrates an exemplary liquid fuel injection spoke  24  according to embodiments of the disclosure. Liquid fuel injection spoke  24 , including fluid passageway  34 , may extend along a central longitudinally extending axis A. Head  30  may include a fluid receiving cavity  36  configured to receive liquid fuel from manifold  26 . Cavity  36  is in direct fluid communication with fluid passageway  34  extending along axis A through stem  32 . As such, liquid fuel may be communicated from manifold  26 , through cavity  36  of head  30 , into fluid passageway  34  along stem  32 , and into swirler  22  of the GTE. 
         [0016]    Head  30  may be deformable from a pre-installation configuration, as shown in  FIG. 2 , to a post-installation configuration as shown in  FIGS. 1 and 3   c  as explained below. While in the pre-installation configuration, head  30  may include an outer circumferential wall  38  and an inner circumferential wall  40 . A distance between outer circumferential wall  38  and inner circumferential wall may define a nominal thickness of head  30 . Additionally, head  30  may include an inner end wall  42  and an upper end  44 . Cavity  36  may be defined in part by inner circumferential wall  40 , inner end wall  42 , and upper end  44 . 
         [0017]    Inner circumferential wall  40  may further include a protrusion  46 . Protrusion  46  may extend radially inwardly on inner circumferential wall  40  towards axis A. As shown in  FIG. 2 , the thickness of head  30  is increased in the area adjacent protrusion  46 . Protrusion  46  may be located along inner circumferential wall  44  between inner end wall  42  and upper end  44 . Further, protrusion  44  may include a swager contacting surface  46   a . As shown in  FIG. 2 , for example, surface  46   a  may be inclined so as to cooperate with first and second swagers  50  and  52  (shown in  FIGS. 3   a - 3   c ) to deform head  30  from the pre-installation configuration to the post-installation configuration. Alternatively, surface  46   a  may include any shape configured to contact and cooperate with first and second swagers  50  and  52 . 
         [0018]    As shown in  FIG. 2 , head  30  is of varying thickness. That is, head  30  may have a first thickness adjacent upper end  44 . As shown, inner circumferential wall  40  includes a first taper portion adjacent upper end  44 . Moving along inner circumferential wall  40  towards inner end wall  42 , surface  46   a  is angled, i.e., tapered radially inward toward axis A. That is, the thickness of head  30  increases at surface  46   a . Following surface  46   a , a plateau or flat section  46   b  of protrusion  46  extends thereby maintaining a constant thickness of head  30  in the area of protrusion  46 . The protrusion further includes a second angled, i.e., tapered surface  46   c  mirroring surface  46   a . As shown in  FIG. 2 , the second surface  46   c  tapers radially outwardly away from axis A. That is, head  30  includes a reduced thickness in the area of the second surface  46   c . Outer circumferential wall  38  includes a recess  47  therein. Recess  47  reduces the thickness of head  30  in the vicinity thereof. Recess  47  may be configured to receive a seal and/or gasket therein. 
         [0019]    Deformation of head  30  from the pre-installation configuration to the post-installation configuration will be described in more detail with reference to  FIGS. 3A-3C . As shown in  FIG. 3A , liquid fuel injection spoke  24  may be positioned such that head  30  is disposed within manifold  26  with protrusion  46  adjacent to manifold recess  26   a . Further, stem  32  may be positioned so as to extend into swirler  22 . In order to couple liquid fuel injection spoke  24  within manifold  26 , a series of first and second swagers  50  and  52  may be introduced into cavity  36  through the application of a pressing machine (not shown). For example, as shown in  FIG. 3A , first swager  50  may be introduced into cavity  36 . First swager  50  may include a longitudinally extending support  54 . Swager die  56  may be disposed on an end of support  54 . Swager die  56  may have any shape configured to interact with surface  46   a  so as to cause deformation of head  30 . For example, swager die  56  may include a semi-spherical shape having an outer diameter D 1 . Upon insertion of swager  50  into cavity  36 , an engagement portion  58 , i.e. an outer side wall of swager die  56  may be brought into contact with surface  46   a  of protrusion  46 . 
         [0020]    Upon application of sufficient force urging first swager  50  into cavity  36 , engagement portion  58  may cooperate with surface  46   a  so as to deform head  30 . As shown in  FIG. 3B , for example, engagement portion  58  may interact with surface  46   a  so as to progressively deform or displace material of protrusion  46  as semi-spherical swager die  56  is advanced. Indeed, as die  56  is advanced, a diameter of semi-spherical swager die  56  in contact with surface  46   a  is increased until it reaches outer diameter D 1 . As the diameter of die  56  is increased, increased force is applied to surface  46   a  so as to increase an amount of deformation or material displacement. 
         [0021]    After a first degree of deformation or material displacement has been achieved through the use of first swager  50 , second swager  52  may be inserted to cavity  36 . Second swager  52  may be similar to swager  50 , except a die  57  of swager  52  may include an outer diameter D 2 , larger than diameter D 1  of die  56 . That is, second swager  52 , similarly to first swager  50 , may include a longitudinally extending support  55  and a swager die  57  disposed on an end of support  55 . Swager die  57  may have any shape configured to interact with surface  46   a  so as to cause deformation of head  30 . For example, swager die  57  may include a semi-spherical shape having outer diameter D 2 . Upon insertion of second swager  52  into cavity  36 , an engagement portion  59 , i.e. an outer side wall of swager die  56  may be brought into contact with surface  46   a.    
         [0022]    Upon application of sufficient force urging second swager  52  into cavity  36 , engagement portion  59  may cooperate with surface  46   a  so as to deform head  30 . As shown in  FIG. 3C , for example, engagement portion  59  may interact with surface  46   a  so as to progressively deform or displace the material of protrusion  46  as semi-spherical swager die  57  is advanced. Indeed, as die  57  is advanced, a diameter of semi-spherical swager die  57  in contact with surface  46   a  is increased until it reaches outer diameter D 2 . As the diameter of die  57  is increased, increased force is applied to surface  46   a  so as to increase an amount of deformation. As shown in  FIG. 3C , second swager  52  may urge displaced material of protrusion  46  into recess  26   a  of manifold  26 . That is, due to the interaction of first and second swagers  50  and  52  with head  30 , material of protrusion  46  may be displaced from the pre-installation configuration in which protrusion  46  extends radially inwardly from inner circumferential wall  40  to the post-installation configuration in which displaced material of protrusion  46  may be urged outwardly of outer circumferential wall  38  and into recess  26   a  of manifold  26 . As such, liquid fuel injection spoke  24  may be securely retained in manifold  26 . 
         [0023]    Engagement of liquid fuel injection spoke  24  with manifold  26  via first and second swagers  50  and  52  may form an improved joint therebetween. For example, displacement of material of protrusion  44  into recess  26   a  may provide an improved structural seal between liquid fuel injection spoke  24  and manifold  26 . As such, leakage between manifold  26  and liquid fuel injection spoke  24  may be avoided. In addition, deformation of head  30  via first and second swagers  50  and  52  may ensure sealing without over stressing. That is, deformation of head  30  may be achieved sufficiently gradually so as to avoid stress cracking. 
         [0024]    Further, as material of protrusion  46  is displaced, molecular diffusion between liquid fuel injection spoke  24  and manifold  26  may form an improved joint. Molecular diffusion is a solid-state welding technique which firmly joins two components. During molecular diffusion, contacting surfaces coalesce upon the application of heat and pressure. That is, owing to a gradient difference between two different materials, molecules of a region of higher concentration will migrate towards one of lower concentration. As such, a strong bond between manifold  26  and liquid fuel injection spoke  24  may be formed. Additionally, as to opposed to alternative prior art joining methods, molecular diffusion does not require application of a separate material and does not result in welding material interfering with fluid passageway  34 . 
       INDUSTRIAL APPLICABILITY 
       [0025]    Current liquid fuel injection spokes are expensive to manufacture and often produce unreliable results. For example, current spokes often allow leakage of fuel between the liquid fuel manifold and the liquid fuel injection spoke. Leakage may result in uneven fuel burning thereby resulting in uneven temperature distributions during combustion. Often, liquid fuel injection spokes are press-fit into engagement with the liquid fuel manifold. A press-fit engagement, however, requires precise manufacturing tolerances which increase manufacturing costs. Also, since there is no material bond, a press-fit engagement fails to prevent fuel leakage between the liquid fuel injection spoke and the liquid fuel manifold. Alternative engagements between the liquid fuel manifold and liquid fuel injection spoke may be obtained through brazing. Brazing, however, may result in particles of brazing material becoming lodged within a fuel passage of the liquid fuel injection spoke. This brazing material may reduce the cross-sectional area of the fuel passage and therefore, affect the amount and/or speed of liquid fuel injected through the liquid fuel injection spoke. Additionally, brazing is difficult to control and may result in uneven engagement between the liquid fuel injection spoke and liquid manifold. 
         [0026]    Further engagements between the liquid fuel injection spoke and the liquid manifold may be accomplished via electron beam welding or laser welding in which materials are heated until they are melted and joined together. Each of these engagements, however, may produce stress cracking and is difficult to control with sufficient precision on elements having dimensions similar to common liquid fuel injection spokes. Additionally, welding may be ineffective to join the liquid fuel injection spoke and liquid manifold since each are commonly formed of a different material having different melting points. 
         [0027]    The presently disclosed liquid fuel injection spoke  24  may be utilized to form an improved joint between liquid fuel injection spoke  24  and manifold  26 . For example, as shown in  FIG. 4 , a method of forming an improved joint between liquid fuel injection spoke  24  and manifold  26  is disclosed. As shown at step  100 , liquid fuel injection spoke  24  may be positioned within manifold  26  to extend into swirler  22 . At step  110 , first swager  50  may be inserted into cavity  36 . First swager  50  may be urged into cavity  36  such that engagement portion  58 , i.e. an outer side wall of first swager  50  interacts with surface  46   a  of protrusion  46  so as to progressively deform or displace material of protrusion  46  as semi-spherical swager die  56  is advanced. Due to the applied pressure, a first amount of molecular diffusion may be induced between liquid fuel injection spoke  24  and manifold  26  after which first swager  50  may be removed from cavity  36 . 
         [0028]    At step  120 , second swager  52 , having a larger diameter than first swager  50 , may be inserted into cavity  36 . Similar to first swager  50  applied in step  110 , second swager  52  may be urged into cavity  36  such that engagement portion  59 , i.e. outer side wall of second swager  52  interacts with surface  46   a  of protrusion  46  so as to progressively deform or displace material of protrusion  46  as semi-spherical swager die  57  is advanced. Indeed, material displaced from protrusion  46  may be urged into recess  26   a  of manifold. Due to the applied pressure, a second amount of molecular diffusion may be induced between liquid fuel injection spoke  24  and manifold  26  after which second swager  52  may be removed from cavity  36 . Optionally, heat may be applied to liquid fuel injection spoke  24  and/or manifold  26  at step  130  so as to enhance molecular diffusion therebetween. For example, heat may be applied in any conventional manner, such as, by increasing a temperature of the liquid fuel injection spoke  24  and/or manifold via applied radiation in a vacuum furnace. 
         [0029]    As such, an improved joint between liquid fuel injection spoke  24  and manifold  26  may be formed. The improved joint may prevent fuel leakage between liquid fuel injection spoke  24  and manifold  26  and reduce stress cracking. Molecular diffusion between liquid fuel injection spoke  24  and manifold  26  form a strong bond therebetween and the system and method prevent interference with fluid passageway  36 . 
         [0030]    It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed liquid fuel injection spoke joint. For example, liquid fuel injection spoke  24  can be securely coupled to the manifold  26  using just a single swager  50 , rather than two swagers  50 ,  52  disclosed above. Further, liquid fuel injection spoke  24  may be secured to manifold  26  without the application of heat. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed liquid fuel injection spoke joint. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.