Patent Publication Number: US-11029029-B2

Title: Fuel injector heat exchanger assembly

Description:
FIELD 
     The present subject matter relates generally to fuel injector assemblies for heat engines. The present subject matter relates specifically to heat exchanger systems at fuel injector assemblies. 
     BACKGROUND 
     Heat engines, such as gas turbine engines, generally include fuel nozzles that generally suffer from thermal distress due to high operating temperatures in combustion chambers. Downstream portions of fuel nozzles may require cooling fluid to mitigate distress and damage due to high temperatures at the combustion chamber. Although impingement holes and cooling circuits may be provided at downstream portions of fuel nozzles, the extent of mitigation of thermal distress may be limited by the temperature of the cooling fluid. For example, fuel nozzles are often compromised by the temperature of compressed air used as cooling fluid from the compressors as well as limitations on heat transfer to fuel in the fuel nozzle, such as to avoid fuel coking. 
     As such, there is a need for combustion sections and fuel nozzles that provide improved cooling structures. 
     BRIEF DESCRIPTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     A fuel injector heat exchanger assembly is provided, in which the fuel injector assembly includes a body defining an outer surface and an inner surface. The body includes a plurality of walls in concentric arrangement. The plurality of walls defines a plurality of passages including a first passage surrounded by a second passage, and a third passage surrounding the second passage. Each passage is fluidly segregated from one another by the plurality of walls. A first conduit wall is defined through the body from the outer surface. The first conduit wall defines a first conduit in fluid communication with the second passage. The first conduit wall fluidly segregates the first conduit from the third passage. The first conduit is configured to admit a flow of fluid from outside the fuel injector into the second passage. 
     In one embodiment, the fuel injector assembly includes a flange configured to couple to an outer casing. The fuel injector defines a first end proximate to the flange and a second end distal to the first end along the body. The first conduit wall is defined through the body at the first end. 
     In various embodiments, the body further includes a second conduit wall defined through the body from the outer surface. The second conduit wall defines a second conduit in fluid communication with the second passage. The second conduit wall fluidly segregates the first conduit from the third passage. The second conduit is configured to egress a flow of fluid from the second passage to outside the fuel injector. In one embodiment, the fuel injector assembly includes a flange configured to couple to an outer casing. The fuel injector defines a first end proximate to the flange and a second end distal to the first end along the body. The second conduit wall is defined through the body at the first end. The first conduit wall is defined through the body at the second end distal to the first conduit wall at the first end. 
     In one embodiment, the fuel injector assembly further includes a head extended from the body. The head defines one or more fuel outlets through which a flow of fuel egresses the first passage and the third passage. The head defines a working fluid outlet through which a flow of working fluid egresses the second passage. 
     In various embodiments, the fuel injector assembly further includes a fin structure comprising a plurality of fins extended from one or more of the plurality of walls into one or more of the plurality of passages, in which the plurality of fins are in adjacent circumferential arrangement relative to a reference centerline axis. In one embodiment, the plurality of fins of the fin structure is in adjacent radial arrangement relative to the reference centerline axis extended through the body. In another embodiment, the plurality of fins is arranged along the circumferential direction and the radial direction to provide a helical arrangement through one or more of the plurality of passages. In yet another embodiment, the fin structure is extended into the first passage, the third passage, or both. The first passage and the third passage are each configured provide a flow of fuel therethrough. The second passage is configured to provide a flow of working fluid defining compressed air therethrough. 
     Another aspect of the present disclosure is directed to a heat engine, the heat engine including an outer casing defining an exterior surface and an interior surface. The outer casing defines a diffuser cavity therewithin receiving a flow of compressed air. The fuel injector assembly is coupled to the exterior surface of the outer casing. 
     In one embodiment, the first conduit wall is defined through the body at the first end. 
     In another embodiment, the body of the fuel injector further includes a second conduit wall defined through the body from the outer surface. The second conduit wall defines a second conduit in fluid communication with the second passage. The second conduit wall fluidly segregates the first conduit from the third passage. The second conduit is configured to egress a flow of fluid from the second passage to outside the fuel injector. 
     In various embodiments, the second conduit wall is defined through the body at the first end. The first conduit wall is defined through the body at the second end distal to the first conduit wall at the first end. In one embodiment, the second conduit wall is defined through the body at the first end radially outward of the interior surface of the outer casing. In another embodiment, the second conduit wall is defined through the body at the first end radially outward of the exterior surface of the outer casing. 
     In one embodiment, the plurality of walls of the fuel injector assembly includes a first wall extended inward of and spaced apart from the inner surface of the body, wherein the first passage is defined within the first wall and a second wall extended inward of the inner surface of the body and outward of the first wall. The second wall is spaced apart from each of the inner surface of the body and the first wall. The second passage is defined between the first wall and the second wall. The third passage is defined between the second wall and the inner surface of the body. The first conduit wall is extended through the body from the outer surface and coupled to the second wall. 
     In one embodiment, the heat engine further includes a fuel system configured to provide one or more flows of de-oxygenated fuel to the first passage and the third passage of the fuel injector assembly. The second passage is configured to receive the flow of compressed air from the diffuser cavity via the first conduit. The fuel injector assembly is configured to egress the flow of compressed air via the second conduit. The one or more flows of fuel and the compressed air are in thermal communication within the body of the fuel injector assembly. 
     In various embodiments, the heat engine further includes a fin structure comprising a plurality of fins extended from one or more of the plurality of walls into one or more of the plurality of passages. The plurality of fins is in adjacent circumferential arrangement relative to a reference centerline axis. In one embodiment, the plurality of fins of the fin structure is in adjacent radial arrangement relative to the reference centerline axis extended through the body. In another embodiment, the plurality of fins is arranged along the circumferential direction and the radial direction to provide a helical arrangement through one or more of the plurality of passages. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  is a schematic cross sectional view of an exemplary heat engine including a combustion section and fuel injector assembly according to aspects of the present disclosure; 
         FIG. 2  is a cross sectional view of an exemplary combustion section and fuel injector assembly of the heat engine of  FIG. 1  according to an aspect of the present disclosure; 
         FIG. 3  is a cutaway cross sectional view of an exemplary embodiment of the fuel injector assembly of the combustion section of  FIG. 2 ; 
         FIG. 4  is an exemplary cross sectional view of the fuel injector assembly of  FIG. 3  at plane  4 - 4 ; 
         FIG. 5  is a cutaway cross sectional view of another exemplary embodiment of the fuel injector assembly of the combustion section of  FIG. 2 ; 
         FIG. 6  is an exemplary cross sectional view of the fuel injector assembly of  FIG. 5  at plane  6 - 6 ; 
         FIG. 7  is another exemplary cross sectional view of the fuel injector assembly of  FIG. 5  at plane  6 - 6 ; 
         FIG. 8  is a cutaway cross sectional view of another exemplary embodiment of the fuel injector assembly of the combustion section of  FIG. 2 ; 
         FIG. 9  is an exemplary cross sectional view of the fuel injector assembly of  FIG. 8  at plane  9 - 9 ; 
         FIG. 10  is an exemplary cross sectional view of the fuel injector assembly of  FIG. 8  at plane  10 - 10 ; and 
         FIG. 11  is a cutaway cross sectional view of another exemplary embodiment of the fuel injector assembly of the combustion section of  FIG. 2 ; 
     
    
    
     Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention. 
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. 
     Approximations recited herein may include margins based on one more measurement devices as used in the art, such as, but not limited to, a percentage of a full scale measurement range of a measurement device or sensor. Alternatively, approximations recited herein may include margins of 10% of an upper limit value greater than the upper limit value or 10% of a lower limit value less than the lower limit value. 
     Embodiments of a fuel injector heat exchanger assembly and combustion section are provided that may provide improved cooling to the fuel injector assembly and the combustion section. The embodiments provided herein generally include a body defining an outer surface and an inner surface and including a plurality of walls in concentric arrangement defining a plurality of passages. The plurality of passages provides thermal communication (e.g., heat transfer) between a working fluid, such as compressed air from a compressor section, to a pair or more of fuels surrounding the passage through which the working fluid flows. As the compressed air is generally a significantly higher temperature from the compressor section versus the flows of fuel entering the fuel injector assembly, the fuel removes thermal energy from the working fluid. The working fluid may be provided to a head portion of the fuel injector assembly, or other portions of the combustion section or engine. The cooled working fluid may be provided to a downstream portion, such as an aft heat shield, thermally proximate to combustion gases at the combustion chamber, thereby improving fuel injector assembly durability by reducing a thermal gradient at the fuel injector assembly. In various embodiments, the fuel entering the fuel injector assembly is de-oxygenated at the fuel system such as to mitigate risks of damage at the fuel injector assembly that may be associated with the increased thermal energy received from the working fluid (e.g., coking). 
     Referring now to the drawings,  FIG. 1  is a schematic partially cross-sectioned side view of an exemplary heat engine  10  herein referred to as “engine  10 ” as may incorporate various embodiments of the present disclosure. Although further described below with reference to a turbofan engine, the present disclosure is also applicable to heat engines, propulsion systems, and turbomachinery in general, including turbofan, turbojet, turboprop, turboshaft, and propfan gas turbine engines, marine and industrial turbine engines, and auxiliary power units. As shown in  FIG. 1 , the engine  10  has a longitudinal or axial centerline axis  12  that extends there through for reference purposes and generally along an axial direction A. A reference radial direction R is further provided extended from the axial centerline axis  12 . The engine  10  further defines an upstream end  99  and a downstream  98  generally opposite of the upstream end  99  along the axial direction A. In general, the engine  10  may include a fan assembly  14  and a core engine  16  disposed downstream from the fan assembly  14 . 
     The core engine  16  may generally include a substantially tubular outer casing  18  that defines an annular inlet  20 . The outer casing  18  encases or at least partially forms, in serial flow relationship, a compressor section having a booster or low pressure (LP) compressor  22 , a high pressure (HP) compressor  24 , a combustion section  26 , a turbine section including a high pressure (HP) turbine  28 , a low pressure (LP) turbine  30  and a jet exhaust nozzle section  32 . A high pressure (HP) rotor shaft  34  drivingly connects the HP turbine  28  to the HP compressor  24 . A low pressure (LP) rotor shaft  36  drivingly connects the LP turbine  30  to the LP compressor  22 . The LP rotor shaft  36  may also be connected to a fan shaft  38  of the fan assembly  14 . In particular embodiments, as shown in  FIG. 1 , the LP rotor shaft  36  may be connected to the fan shaft  38  by way of a reduction gear  40  such as in an indirect-drive or geared-drive configuration. In other embodiments, the engine  10  may further include an intermediate pressure (IP) compressor and turbine rotatable with an intermediate pressure shaft. 
     As shown in  FIG. 1 , the fan assembly  14  includes a plurality of fan blades  42  that are coupled to and that extend radially outwardly from the fan shaft  38 . An annular fan casing or nacelle  44  circumferentially surrounds the fan assembly  14  and/or at least a portion of the core engine  16 . In one embodiment, the nacelle  44  may be supported relative to the core engine  16  by a plurality of circumferentially-spaced outlet guide vanes or struts  46 . Moreover, at least a portion of the nacelle  44  may extend over an outer portion of the core engine  16  so as to define a bypass airflow passage  48  therebetween. 
       FIG. 2  is a cross sectional side view of an exemplary combustion section  26  of the core engine  16  as shown in  FIG. 1 . As shown in  FIG. 2 , the combustion section  26  may generally include an annular type combustor  50  having an annular inner liner  52 , an annular outer liner  54  and a dome wall  56  that extends radially between upstream ends  58 ,  60  of the inner liner  52  and the outer liner  54  respectfully. In other embodiments of the combustion section  26 , the combustion assembly  50  may be a multi-annular combustor, such as a can or can-annular type. As shown in  FIG. 2 , the inner liner  52  is radially spaced from the outer liner  54  with respect to axial centerline  12  ( FIG. 1 ) and defines a generally annular combustion chamber  62  therebetween. However, it should be appreciated that the liners  52 ,  54 , swirlers (not shown), or other components may be disposed from the axial centerline  12  such as to define a multi-annular combustor configuration. 
     As shown in  FIG. 2 , the inner liner  52  and the outer liner  54  may be encased within an outer casing  64 . An outer flow passage  66  may be defined around the inner liner  52 , the outer liner  54 , or both. The inner liner  52  and the outer liner  54  may extend from the dome wall  56  towards a turbine nozzle or inlet  68  to the HP turbine  28  ( FIG. 1 ), thus at least partially defining a hot gas path between the combustor assembly  50  and the HP turbine  28 . 
     A fuel system  300  provides one or more flows of fuel  171 ,  172  to one or more fuel injector assemblies  70  coupled to an exterior surface  69  of the outer casing  64  and extended therethrough. The fuel system  300  may generally define a de-oxygenating fuel system providing flows of substantially or completely de-oxygenated fuel  171 ,  172  to each fuel injector assembly  70 . The fuel may include liquid and/or gaseous flows of fuel. In various embodiments, the flows of fuel  171 ,  172  are independently metered or controlled such as to provide flow rates, pressures, temperatures, or fuel types different from one another, or different to one or more of the fuel injector assemblies  70 . 
     The fuel injector assembly  70  may extend at least partially through the dome wall  56  and provide a fuel-air mixture to the combustion chamber  62 . The fuel injector assembly  70  includes a body  110  extended from the outer casing  64  and radially inward into the combustion section  26 . The fuel injector assembly  70  may further include a head  113  that extends at least partially through the dome wall  56  to the combustion chamber  62 . 
     A first end  101  of the fuel injector assembly  70  is defined at or proximate to a flange  150  of the fuel injector assembly  70  that couples to the outer casing  64 . The flange  150  is generally extended from an outer wall  125  of a portion of the body  110  of the fuel injector assembly  70 . In various embodiments, the outer wall  125  may define a heat shield generally protecting a fuel delivering body  110  of the fuel injector assembly  70  from thermal exposure. The fuel injector assembly  70  further defines a second end  102  distal to the first end  101  along a body  110  or head  113  of the fuel injector assembly  70 . The second end  102  may generally correspond to a portion of the fuel injector assembly  70  further downstream from the outer casing  64  relative to flows of fuel  171 ,  172  provided therethrough to the fuel injector assembly  70 . For example, the second end  102  may correspond to a radially inward portion of the body  110  from which the head  113  is extended toward the combustion chamber  62 . As another example, the second end  102  may correspond to one or more fuel outlets  114  of the fuel injector assembly  70  through which flows of fuel  171 ,  172  are provided to the combustion chamber  62 . 
     During operation of the engine  10 , as shown in  FIGS. 1 and 2  collectively, a volume of air as indicated schematically by arrows  74  enters the engine  10  through an associated inlet  76  of the nacelle  44  and/or fan assembly  14 . As the air  74  passes across the fan blades  42  a portion of the air as indicated schematically by arrows  78  is directed or routed into the bypass airflow passage  48  while another portion of the air as indicated schematically by arrow  80  is directed or routed into the LP compressor  22 . Air  80  is progressively compressed as it flows through the LP and HP compressors  22 ,  24  towards the combustion section  26 . As shown in  FIG. 2 , the now compressed air as indicated schematically by arrows  82  flows across a compressor exit guide vane (CEGV)  67  and through a prediffuser  65  into a diffuser cavity or head end portion  84  of the combustion section  26 . 
     The prediffuser  65  and CEGV  67  condition the flow of compressed air  82  to the fuel injector assembly  70 . The compressed air  82  pressurizes the diffuser cavity  84 . The compressed air  82  enters the fuel injector assembly  70  to mix with a liquid and/or gaseous fuel. 
     Referring still to  FIGS. 1 and 2  collectively, the combustion gases  86  generated in the combustion chamber  62  flow from the combustor assembly  50  into the HP turbine  28 , thus causing the HP rotor shaft  34  to rotate, thereby supporting operation of the HP compressor  24 . As shown in  FIG. 1 , the combustion gases  86  are then routed through the LP turbine  30 , thus causing the LP rotor shaft  36  to rotate, thereby supporting operation of the LP compressor  22  and/or rotation of the fan shaft  38 . The combustion gases  86  are then exhausted through the jet exhaust nozzle section  32  of the core engine  16  to provide propulsive thrust. 
     Referring now to  FIG. 3 , a cutaway view of an exemplary embodiment of the fuel injector assembly  70  according to an aspect of the present disclosure is provided. Referring additionally to  FIG. 4 , a cross sectional view at plane  4 - 4  in  FIG. 3  of the fuel injector assembly  70  is further provided. Referring to  FIGS. 3-4 , the body  110  of the fuel injector assembly  70  defines an outer enclosure  124 . In various embodiments, the outer enclosure  124  of the body  110  is inward of the outer wall  125  defining a heat shield. An inner wall  123  is extended through the body  110  substantially co-directional to the outer enclosure  124 . A first reference centerline axis  13  is defined through the fuel injector assembly  70 . The first reference centerline axis  13  generally corresponds to the radial direction R of the engine  10 . A plurality of walls  120  is extended through the body  110 . In various embodiments, the plurality of walls  120  are each in generally concentric arrangement relative to the first reference centerline axis  13 . The plurality of walls  120  defines a plurality of fluidly separated passages between the walls  120  and the inner wall  123  of the body  110 . 
     The plurality of walls  120  includes a first wall  121  extended inward of and spaced apart from the inner wall  123  of the body  110  relative to the first centerline axis  13 . A first passage  126  is defined within the first wall  121 . A second wall  122  is extended inward of the inner wall  123  of the body  110  and outward of the first wall  121  relative to the first centerline axis  13 . The second wall  122  is spaced apart from the inner wall  123  of the body  110  and the first wall  121 . A second passage  127  is defined between the first wall  121  and the second wall  122 . A third passage  128  is defined between the second wall  122  and the inner wall  123  of the body  110 . Each passage  126 ,  127 ,  128  is fluidly segregated from one another via each of the plurality of walls  120  therebetween (e.g., the first wall  121  and the second wall  122 ). 
     In various embodiments, a fourth passage  129  is defined between the inner wall  123  and the outer enclosure  124 . The fourth passage  129  generally defines a volume at which a gas, such as air, or oxidizer generally, or an inert gas, surrounds the passages  126 ,  127 ,  128  within the body  110 . In still another embodiment, a fifth passage  130  is defined between the outer enclosure  124  and the outer wall  125 , such as to define another volume at which a gas, such as air or an oxidizer generally, surrounds the passages  126 ,  127 ,  128  within the body  110  and the fourth passage  129  surrounding the body  100 . 
     The fuel injector assembly  70  further includes a first conduit wall  131  defined through the body  110  from the outer wall  125 , the outer enclosure  124 , or both, and coupled to the second wall  122 . The first conduit wall  131  defines a first conduit  136  therewithin in fluid communication with the second passage  127 . 
     During operation of the engine  10 , a first flow of fuel, depicted schematically via arrows  171 , is provided to the first passage  126  of the fuel injector assembly  70 . A second flow of fuel, depicted schematically via arrows  172 , is provided to the third passage  128  of the fuel injector assembly  70 . The first flow of fuel  171  and the second flow of fuel  172  may each define one or more of a different pressure, flow rate, temperature, or fuel type (e.g., a liquid or gaseous fuel, or combinations thereof). It should be appreciated that the first passage  126  and the third passage  128  may each define different geometries (e.g., different cross sectional areas or volumes) such as to enable different pressures, flow rates, temperatures, etc. of the first flow of fuel  171  relative to the second flow of fuel  172 . 
     A flow of a working fluid, depicted schematically via arrows  182 , is provided to the second passage  127  via the first conduit  136  extended from a first opening  138  through the outer wall  125  of the body  110 . In various embodiments, the working fluid is a portion of the compressed air  82  from the compressors  22 ,  24  ( FIG. 1 ). The working fluid  182  provided to the second passage  127  is in thermal communication between first passage  126  and the third passage  128  such as to define the plurality of passages  126 ,  127 ,  128  within the body  110  as a heat exchanger. 
     Referring to  FIGS. 1-3 , in one embodiment, the working fluid  182 , defining a portion of the compressed air  82  exiting the compressors  22 ,  24  into the combustion section  26  may be approximately 480 degrees Celsius or greater as it enters the second passage  127  through the first conduit  136 . However, it should be appreciated that the working fluid  182  may define greater or lesser temperatures based at least on the compressors  22 ,  24  and an operating condition of the engine  10  (e.g., part load or full load condition, rotor speed, ambient air pressure or temperature, etc.). Generally, the working fluid  182  may define a temperature greater than the flows of fuel  171 ,  172  entering the fuel injector assembly  70 . 
     Referring to  FIG. 3 , in one embodiment, the fuel injector assembly  70  includes the first conduit wall  131  and the first conduit  136  defined at the first end  101  of the fuel injector assembly  70 . The working fluid  182  enters the second passage  127  and flows substantially co-directional to the first flow of fuel  171  and second flow of fuel  172  through the first passage  126  and third passage  128 , respectively. The flows of fuel  171 ,  172  each egress through one or more fuel outlets  114  at the head  113  of the fuel injector assembly  70 . 
     In various embodiments, a working fluid outlet  115  is defined through the fuel injector assembly  70  through which the flow of working fluid  182  egresses from the fuel injector assembly  70 . In one embodiment, such as depicted in regard to  FIG. 3 , the working fluid outlet  115  is proximate to the fuel outlet  114 . In an exemplary embodiment, the working fluid outlet  115  is proximate to the fuel outlet  114  such as to enable the working fluid  182  to flow through the body  110 , or additionally, the head  113 , in thermal communication with the flows of fuel  171 ,  172 . The thermal communication between the working fluid  182  and the flows of fuel  171 ,  172  provide for heat transfer from the working fluid  182  to one or more of the flows of fuel  171 ,  172 . The arrangement of the first conduit wall  131  at the first end  101  of the fuel injector assembly  70  and the working fluid outlet  115  at a distal second end  102  of the fuel injector assembly  70  (e.g., at the head  113 ) provides the working fluid  182  as a cooling fluid to the head  113 . 
     In one particular embodiment, the working fluid outlet  115  is disposed at a portion of the head  113  disposed at the combustion chamber  62  ( FIG. 2 ) or most proximate to heat release from the combustion gases  86  ( FIG. 2 ). The working fluid  182 , cooled by the flows of fuel  171 ,  172  surrounding the working fluid  182  within the fuel injector assembly  70 , provides thermal attenuation to the head  113 , or more particularly, the second end  102  at the head  113 . Such thermal attenuation improves durability of the fuel injector assembly  70 , such as by reducing a thermal gradient at the fuel injector assembly  70  associated with heat release at the combustion chamber  62  ( FIG. 2 ). 
     It should be appreciated that in various embodiments, the working fluid outlet  115  may further define a fuel-air mixing outlet, such as to provide fluid communication between the working fluid  182  and one or more of the flows of fuel  171 ,  172  at the head  113 . It should further be appreciated that fuel-air mixing may be improved via the transfer of thermal energy from the working fluid  182  to one or more of the flows of fuel  171 ,  172  within the fuel injector assembly  70 . Such increase in thermal energy at the flows of fuel  171 ,  172  may improve atomization of the fuel  171 ,  172  as it egresses from the one or more fuel outlets  114  for ignition at the combustion chamber  62 . Improved atomization may further improve emissions output or desirably alter heat release characteristics during combustion. 
     Referring now to  FIGS. 5-7 , exemplary embodiments of the fuel injector assembly  70  according to aspects of the present disclosure are further provided. The embodiments provided in regard to  FIGS. 5-7  are configured substantially similarly as described in regard to  FIGS. 2-4 .  FIG. 5  provides a cutaway cross sectional view of an exemplary embodiment of the fuel injector assembly  70 .  FIG. 6  provides a cross sectional view at plane  6 - 6  of  FIG. 5 . In the embodiments provided in regard to  FIGS. 5-6 , the fuel injector assembly  70  may further include a fin structure  140  extended from one or more of the walls  121 ,  122 ,  123  extended within the body  110 . The fin structure  140  includes a plurality of fins  141  disposed in circumferential arrangement relative to the reference centerline axis  13  extended through the body  110 . In the embodiment depicted, the plurality of fins  141  is extended into fourth passage  129  from the inner wall  123  of the body  110 . In other embodiments, the plurality of fins  141  is extended into one or more passages  126 ,  127 ,  128  defined between the walls  121 ,  122 ,  123 ,  124  of the body  110 . 
     The fin structure  140  may promote and improve heat transfer from the working fluid  182  to one or more of the fuels  171 ,  172  flowing through the body  110 . In one embodiment, such as depicted in regard to  FIG. 6 , the fin structure  140  is extended from the inner wall  123  into the fourth passage  129  such as to promote heat transfer from the working fluid  182  in the second passage  127  to the fuel in the third passage  128 . In another embodiment, the fin structure  140  is extended from the second wall  122  into the second passage  127 . In yet another embodiment, such as depicted in regard to the exemplary cross sectional view provided in  FIG. 7 , the fin structure  140  may be extended from the first wall  121  into the first passage  126  such as described in regard to  FIG. 6 . 
     Referring back to  FIG. 5 , in various embodiments, the plurality of fins  141  of the fin structure  140  may further be disposed in adjacent radial arrangement along the radial direction R. For example, the fin structure  140  may be disposed along a flowpath length of the passages  126 ,  127 ,  128 ,  129  through the body  110  from the first end  101  to the head  113 . In one embodiment, the plurality of fines  141  is further arranged along the circumferential direction and the radial direction to provide a helical arrangement through one or more of the passages  126 ,  127 ,  128 ,  129 . The helical arrangement may provide a substantially helical flowpath of the fuel  171 ,  172  and/or the working fluid  182 . The helical flowpath may increase a residence time of the fluids  171 ,  172 ,  182  within the body  110  of the fuel injector assembly  70  such as to increase heat transfer between the fluids  171 ,  172 ,  182 . The increased heat transfer may further cool the working fluid  182  to further provide one or more benefits described herein. 
     Referring now to  FIGS. 8-10 , exemplary embodiments of the fuel injector assembly  70  according to aspects of the present disclosure are further provided. The embodiments provided in regard to  FIGS. 8-10  are configured substantially similarly to embodiments shown and described in regard to  FIGS. 2-7 . Regarding  FIG. 8 , the first conduit wall  131  defining the first conduit  136  in fluid communication with the second passage  127  may be defined at the second end  102  distal to a second conduit wall  132  defining a second conduit  137  at the first end  101 . Various embodiments of the second conduit wall  132  are configured similarly as described in regard to the first conduit wall  131 . For example, the second conduit wall  132  defines the second conduit  137  in fluid communication with the second passage  127 . Additionally, the first conduit wall  131  and the second conduit wall  132  each provide fluid communication between an exterior or outside of the fuel injector assembly  70  to the second passage  127  via the respective first conduit  136  and second conduit  137 . Furthermore, the first conduit wall  131  and the second conduit wall  132  each fluidly segregate the working fluid  182  from the third passage  128  disposed between the exterior of the fuel injector assembly  70  and the second passage  127 . 
     Referring now to  FIG. 11 , another exemplary embodiment of the fuel injector assembly  70  is provided. The exemplary embodiment provided in regard to  FIG. 11  is configured substantially similarly as shown and described in regard to  FIGS. 8-10 . In  FIG. 11 , the fuel injector assembly particularly defines the second conduit wall  132  and the second conduit  137  radially outward of an interior surface  69  of the outer casing  64 , such as shown schematically by reference plane  69  and further shown in  FIG. 2 . In various embodiments, the fuel injector assembly  70  may provide a portion of a heat exchanger circuit of the engine  10  in which the working fluid  182 , such as a portion of compressed air  82  from the compressors  22 ,  24 , is provided from the diffuser cavity  84  through the fuel injector assembly  70  defining a heat exchanger with the fuels  171 ,  172  through the fuel injector assembly  70 . The working fluid  182  may enter the fuel injector assembly  70  through the first opening  138  to the first conduit  136 , flow through the second passage  127  in thermal communication with the fuels  171 ,  172  in the first passage  126  and third passage  128 , and egress from the fuel injector assembly  70  via a second opening  139  at the outer wall  125  of the body  110  at the second conduit  137 . 
     Referring to  FIGS. 2 and 11 , in one embodiment, the second conduit  137  may be disposed radially outward of the interior surface  69  and radially inward of the exterior surface  71  ( FIG. 2 ) of the outer casing  64 . For example, the outer casing  64  may define between the exterior and interior surfaces  69 ,  71  one or more passages, conduits, or manifolds further defining portions of a heat exchanger circuit of the engine  10 . The second conduit  137  is disposed through the body  110  of the fuel injector assembly  70  corresponding to a portion between the exterior and interior surfaces  69 ,  71  of the outer casing  64  when the fuel injector assembly  70  is installed thereto. The second conduit  137  is further in fluid communication with such passages, conduits, or manifolds between the surfaces  69 ,  71  of the outer casing  64 . 
     In another embodiment, the second conduit  137  may be disposed radially outward of the interior surface  69  and the exterior surface  71  ( FIG. 2 ) of the outer casing  64  when the fuel injector assembly  70  is installed thereto. The second conduit  137  may be provided in fluid communication with passages, conduits, or manifolds disposed radially outward or outside of the outer casing  64  such as to further provide the cooled working fluid  182  to the heat exchanger circuit. Additionally, or alternatively, the working fluid  182  may be further cooled by another fluid after egressing from the fuel injector assembly  70 . 
     Although not further depicted herein, the fuel injector assembly  70  and the combustion section  26  may include one or more seals, such as between the fuel injector assembly  70  and the outer casing  64 . Additionally, in various embodiments, a heat shield  200  ( FIG. 5 ) may be disposed between the first end  101  of the fuel injector assembly  70  and the second passage  127 , such as to prevent thermal communication between the working fluid  182  at the second passage  127  and a fuel valve  210  disposed radially outward of the heat shield  200  at the fuel injector assembly  70 . 
     Additionally, or alternatively, the fuel injector assembly  70  may further include additional walls to define additional fluid flow passages therebetween. For example, the first passage  126  may provide a pilot fuel source, such as for promoting ignition or low- or mid-power conditions, such as idle, cruise, or other part-load conditions, or for promoting or advantageously affecting heat release characteristics at the combustion chamber  62  (e.g., pressure oscillations, acoustics, etc.). The third passage  128  may provide a main fuel source such as to provide high-power conditions at the combustion chamber  62 , such as take-off or full load conditions. The plurality of walls  120  may further include a third wall or more to provide an additional pilot fuel source, thereby providing a primary and secondary pilot circuit. Embodiments of the fuel injector assembly  70  provided herein may generally provide the second passage  127  surrounded by the first and third passages  126 ,  128  and in thermal communication therewith. The working fluid  182 , such as a portion of compressed air  82  from the compressors  22 ,  24 , is conditioned as a cooling fluid to the head  113  of the fuel injector assembly  70 , or more particularly more thermally distressed downstream portions thereof inward into the combustion chamber  62 . 
     The fuel injector assembly  70 , the combustion section  26 , and the combustor assembly  50  depicted in regard to  FIGS. 1-11  and described herein may be constructed as an assembly of various components that are mechanically joined or arranged such as to produce the fuel injector assembly  70  shown and described herein. The fuel injector assembly  70 , or portions thereof, may alternatively be constructed as a single, unitary component and manufactured from any number of processes commonly known by one skilled in the art. These manufacturing processes include, but are not limited to, those referred to as “additive manufacturing” or “3D printing”. Additionally, any number of casting, machining, welding, brazing, or sintering processes, or mechanical fasteners, or any combination thereof, may be utilized to construct the fuel injector assembly  70  or the combustion section  26 . Furthermore, the fuel injector assembly  70  may be constructed of any suitable material for turbine engine combustor sections, including but not limited to, nickel- and cobalt-based alloys. Still further, flowpath surfaces and passages may include surface finishing or other manufacturing methods to beneficially affect drag or otherwise promote heat transfer or advantageously affect fluid flow. Such manufacturing methods or surface finishing may include methods to promote fluid flow, such as, but not limited to, tumble finishing, barreling, rifling, polishing, or coating. Other methods may include those to promote heat transfer or increase residence time of one or more fluids within the fuel injector assembly  70 , such as, but not limited to, protuberances, promoting roughness, or other surface features to affect fluid flow rate or heat transfer. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.