Patent Publication Number: US-11378275-B2

Title: High shear swirler with recessed fuel filmer for a gas turbine engine

Description:
BACKGROUND OF THE DISCLOSURE 
     1. Technical Field 
     This disclosure relates generally to a fuel injector assembly and, more particularly, to a fuel injector assembly with a high shear swirler. 
     2. Background Information 
     Various types and configurations of fuel injector assemblies are known in the art. Some of these known fuel injector assemblies include a high shear swirler mated with a fuel injector nozzle. While these known fuel injector assemblies have various advantages, there is still room in the art for improvement. In particular, there is still room in the art for fuel injector assemblies capable of improving fuel-air mixing, reducing combustor dynamics and/or reducing undesirable combustor tones. 
     SUMMARY OF THE DISCLOSURE 
     According to an aspect of the present disclosure, an assembly is provided for a turbine engine. This turbine engine assembly includes a swirler and a fuel nozzle. The swirler is configured with an outer wall, an inner wall, an outer passage and an inner passage. The outer wall circumscribes the inner wall and extends axially along an axis to a distal outer wall end. The inner wall extends axially along the axis to a distal inner wall end that is axially recessed within the swirler from the distal outer wall end. The outer passage is formed by and radially between the inner wall and the outer wall. The inner passage is formed by and radially within the inner wall. The fuel nozzle projects into the inner passage. The fuel nozzle is configured with a plurality of orifices axially aligned with the inner wall and arranged circumferentially about the axis. 
     According to another aspect of the present disclosure, a fuel injector assembly with an axis is provided. This fuel injector assembly includes a swirler and a fuel nozzle. The swirler is configured with an outer wall, an inner wall, an outer passage and an inner passage. The outer wall extends axially along the axis to a distal outer wall end. The inner wall is radially within the outer wall and extends axially along the axis to a distal inner wall end. The distal inner wall end is axially offset from the distal outer wall end along the axis. The outer passage is radially between the inner wall and the outer wall. The inner passage is radially within the inner wall. The fuel nozzle projects into the inner passage. The fuel nozzle is configured to direct a plurality of jets of fuel against the inner wall. 
     According to still another aspect of the present disclosure, another fuel injector assembly with an axis is provided. This fuel injector assembly includes a swirler and a fuel nozzle. The swirler is configured with an outer wall, an inner wall, an outer passage and an inner passage. The outer wall extends circumferentially about the inner wall and extends axially along the axis to a distal outer wall end. The inner wall extends axially along the axis to a distal inner wall end. The outer passage is radially between the inner wall and the outer wall. The inner passage is radially within the inner wall. The fuel nozzle projects into the inner passage. The distal outer wall end is disposed a first distance along the axis from a tip of the fuel nozzle. The distal outer wall end is disposed a second distance along the axis from the distal inner wall end. The outer passage has a diameter at the distal outer wall end. A quotient of (the first distance minus the second distance) divided by the diameter is less than one. 
     The plurality of orifices may include a first orifice that is configured to direct a jet of fuel to impinge against the inner wall. 
     The fuel nozzle may be further configured with a second orifice that is coaxial with the axis. 
     The distal outer wall end may be disposed a first distance along the axis from a tip of the fuel nozzle. The distal outer wall end may be disposed a second distance along the axis from the distal inner wall end. The outer passage may have a diameter at the distal outer wall end. A quotient of (the first distance minus the second distance) divided by the diameter may be less than one. 
     The quotient may be less than or equal to 0.8. 
     The quotient may be greater than or equal to 0.25. 
     The quotient may be between 0.35 and 0.68; e.g., 0.35≤quotient≤0.68. 
     The distal outer wall end may be disposed a distance along the axis from a tip of the fuel nozzle. The outer passage may have a diameter at the distal outer wall end. A quotient of the distance divided by the diameter may be less than one. 
     The quotient may be between 0.5 and 0.75; e.g., 0.5≤quotient≤0.75. 
     The distal outer wall end may be disposed a first distance along the axis from a tip of the fuel nozzle. The distal outer wall end may be disposed a second distance along the axis from the distal inner wall end. The outer passage may have a diameter at the distal outer wall end. A quotient of the second distance divided by the diameter may be between 0.07 and 0.15; e.g., 0.07≤quotient≤0.15. 
     The swirler may include a first set of vanes and a second set of vanes. The first set of vanes may be arranged with the outer passage. The second set of vanes may be arranged with the inner passage. 
     The swirler may further include a third set of vanes arranged with the inner passage. The third set of vanes may be axially offset from the second set of vanes. 
     A nozzle guide plate may be included that mounts the fuel nozzle to the swirler. 
     The distal inner wall end may be located axially between the distal outer wall end and a tip of the fuel nozzle along the axis. 
     The fuel nozzle may be configured with a plurality of orifices that are axially overlapped by the inner wall and arranged circumferentially about the axis. 
     The present disclosure may include any one or more of the individual features disclosed above and/or below alone or in any combination thereof. 
     The foregoing features and the operation of the invention will become more apparent in light of the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cutaway illustration of a geared turbine engine. 
         FIG. 2  is a partial side sectional illustration of a combustor section. 
         FIG. 3  is a side sectional illustration of a swirler. 
         FIG. 4A  is an end view illustration of an upstream swirler segment of the swirler with vanes arranged in a first circumferential direction. 
         FIG. 4B  is an end view illustration of the upstream swirler segment with the vanes arranged in a second circumferential direction. 
         FIG. 5A  is an end view illustration of an intermediate swirler segment of the swirler with vanes arranged in the first circumferential direction. 
         FIG. 5B  is an end view illustration of the intermediate swirler segment with the vanes arranged in the second circumferential direction. 
         FIG. 6A  is an end view illustration of a downstream swirler segment of the swirler with vanes arranged in the first circumferential direction. 
         FIG. 6B  is an end view illustration of the downstream swirler segment with the vanes arranged in the second circumferential direction. 
         FIG. 7  is a partial side sectional illustration of the swirler mated with a fuel nozzle and a combustor bulkhead. 
         FIG. 8  is an end view illustration of a tip of the fuel nozzle. 
         FIG. 9  is another partial side sectional illustration of the swirler mated with the fuel nozzle and the combustor bulkhead. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a side cutaway illustration of a geared turbine engine  20 . This turbine engine  20  extends along an axial centerline  22  between an upstream airflow inlet  24  and a downstream airflow exhaust  26 . The turbine engine  20  includes a fan section  28 , a compressor section  29 , a combustor section  30  and a turbine section  31 . The compressor section  29  includes a low pressure compressor (LPC) section  29 A and a high pressure compressor (HPC) section  29 B. The turbine section  31  includes a high pressure turbine (HPT) section  31 A and a low pressure turbine (LPT) section  31 B. 
     The engine sections  28 ,  29 A,  29 B,  30 ,  31 A and  31 B are arranged sequentially along the centerline  22  within an engine housing  32 . This housing  32  includes an inner case  34  (e.g., a core case) and an outer case  36  (e.g., a fan case). The inner case  34  may house one or more of the engine sections  29 A- 31 B; e.g., an engine core. The outer case  36  may house at least the fan section  28 . 
     Each of the engine sections  28 ,  29 A,  29 B,  31 A and  31 B includes a respective rotor  38 - 42 . Each of these rotors  38 - 42  includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s). 
     The fan rotor  38  is connected to a gear train  44 , for example, through a fan shaft  46 . The gear train  44  and the LPC rotor  39  are connected to and driven by the LPT rotor  42  through a low speed shaft  47 . The HPC rotor  40  is connected to and driven by the HPT rotor  41  through a high speed shaft  48 . The shafts  46 - 48  are rotatably supported by a plurality of bearings  50 ; e.g., rolling element and/or thrust bearings. Each of these bearings  50  is connected to the engine housing  32  by at least one stationary structure such as, for example, an annular support strut. 
     During operation, air enters the turbine engine  20  through the airflow inlet  24 . This air is directed through the fan section  28  and into a core gas path  52  and a bypass gas path  54 . The core gas path  52  extends sequentially through the engine sections  29 A- 31 B. The air within the core gas path  52  may be referred to as “core air”. The bypass gas path  54  extends through a bypass duct, which bypasses the engine core. The air within the bypass gas path  54  may be referred to as “bypass air”. 
     The core air is compressed by the compressor rotors  39  and  40  and directed into an annular combustion chamber  56  of a combustor  58  in the combustor section  30 . Fuel is injected into the combustion chamber  56  and mixed with the compressed core air to provide a fuel-air mixture. This fuel air mixture is ignited and combustion products thereof flow through and sequentially cause the turbine rotors  41  and  42  to rotate. The rotation of the turbine rotors  41  and  42  respectively drive rotation of the compressor rotors  40  and  39  and, thus, compression of the air received from a core airflow inlet. The rotation of the turbine rotor  42  also drives rotation of the fan rotor  38 , which propels bypass air through and out of the bypass gas path  54 . The propulsion of the bypass air may account for a majority of thrust generated by the turbine engine  20 , e.g., more than seventy-five percent (75%) of engine thrust. The turbine engine  20  of the present disclosure, however, is not limited to the foregoing exemplary thrust ratio. 
     Referring to  FIG. 2 , the combustor section  30  includes a plurality of fuel injector assemblies  60  (one visible in  FIG. 2 ) arranged circumferentially about the centerline  22  in an annular array. The fuel injector assemblies  60  are mounted to an annular bulkhead  62  of the combustor  58 . The fuel injector assemblies  60  are configured to direct a mixture of fuel and compressed air into the combustion chamber  56  for combustion. 
     Each fuel injector assembly  60  includes a high shear swirler  64  and a fuel injector  66 . The fuel injector assembly  60  of  FIG. 2  also includes a mount  68  configured to couple the fuel injector  66  to the swirler  64 . 
     Referring to  FIG. 3 , the swirler  64  extends circumferentially around an axis  70  (e.g., a centerline of the swirler  64 ) thereby providing the swirler  64  with a full hoop body. The swirler  64  extends axially along the axis  70  between a swirler upstream end  72  and a swirler downstream end  74 . 
     The swirler  64  of  FIG. 3  includes an upstream swirler segment  76 , a flanged intermediate swirler segment  77  and a flanged downstream swirler segment  78 . These swirler segments  76 - 78  configure the swirler  64  with a tubular swirler outer wall  80 , a tubular swirler inner wall  82  (e.g., a fuel filmer) and a plurality of swirler passages  84  and  86 . 
     The upstream swirler segment  76  extends circumferentially around the axis  70 . The upstream swirler segment  76  is located at (e.g., on, adjacent or proximate) the swirler upstream end  72 . The upstream swirler segment  76  of  FIG. 3 , for example, extends axially along the axis  70  from the swirler upstream end  72  to an annular upstream swirler segment surface  88 . 
     Referring to  FIG. 4A , the upstream swirler segment  76  is configured with an upstream set of vanes  90 . These upstream vanes  90  are arranged circumferentially around the axis  70  in an annular array. Each upstream vane  90  is circumferentially separated from each circumferentially adjacent (e.g., neighboring) upstream vane  90  by a respective air gap  92 . The gaps  92  collectively form an upstream airflow inlet  94  into the swirler  64  at the swirler upstream end  72 ; see also  FIG. 3 . The upstream vanes  90  may be configured such that air entering the swirler  64  through the upstream airflow inlet  94  generally flows in a first circumferential direction  96  (e.g., a clockwise direction) about the axis  70 . Alternatively, referring to  FIG. 4B , the upstream vanes  90  may be configured such that air entering the swirler  64  through the upstream airflow inlet  94  generally flows in a second circumferential direction  98  (e.g., a counterclockwise direction) about the axis  70 . 
     In the specific embodiment of  FIG. 3 , the upstream vanes  90  are arranged at the swirler upstream end  72 . With this arrangement, each gap  92  may extend partially axially into the upstream swirler segment  76  from a castellated surface  100  of the segment  76  at the swirler upstream end  72  to a gap end surface  102 . Of course, in other embodiments, each gap  92  may be formed completely axially within the swirler  64  and, for example, its upstream swirler segment  76 . 
     The intermediate swirler segment  77  includes an annular intermediate swirler segment base  104  (e.g., a radial flange) and the swirler inner wall  82 . The intermediate swirler segment  77  and each of its components  82  and  104  extends circumferentially around the axis  70 . 
     The intermediate swirler segment base  104  is abutted axially against the upstream swirler segment  76 . The intermediate swirler segment base  104 , for example, may be coupled (e.g., bonded to) the upstream swirler segment surface  88 . The intermediate swirler segment base  104  extends axially along the axis  70  from the upstream swirler segment  76  to an annular intermediate swirler segment surface  106 . 
     Referring to  FIG. 5A , the intermediate swirler segment base  104  is configured with an intermediate set of vanes  108 . These intermediate vanes  108  are arranged circumferentially around the axis  70  in an annular array. Each intermediate vane  108  is circumferentially separated from each circumferentially adjacent (e.g., neighboring) intermediate vane  108  by a respective gap  110 . The gaps  110  collectively form an intermediate airflow inlet  112  into the swirler  64 ; see also  FIG. 3 . The intermediate vanes  108  may be configured such that air entering the swirler  64  through the intermediate airflow inlet  112  generally flows in the first circumferential direction  96  (e.g., the clockwise direction) about the axis  70 . Alternatively, referring to  FIG. 5B , the intermediate vanes  108  may be configured such that air entering the swirler  64  through the intermediate airflow inlet  112  generally flows in the second circumferential direction  98  (e.g., the counterclockwise direction) about the axis  70 . This circumferential direction for the intermediate vanes  108  may be the same as the circumferential direction for the upstream vanes  90 . However, in other embodiments, the circumferential direction for the intermediate vanes  108  may be the opposite as the circumferential direction for the upstream vanes  90 . 
     In the specific embodiment of  FIG. 3 , the intermediate vanes  108  are arranged at a joint between the swirler segments  76  and  77 . With this arrangement, each gap  110  may extend partially axially into the intermediate swirler segment  77  from a castellated surface  114  of the segment at the to a gap end surface  116 . Of course, in other embodiments, each gap may be formed completely axially within the swirler  64  and, for example, its intermediate swirler segment  77 . 
     The swirler inner wall  82  projects out from the intermediate swirler segment base  104  and extends axially (in a downstream direction along the axis  70 ) to an annular distal inner wall end  118 . As the swirler inner wall  82  extends towards the distal inner wall end  118 , the swirler inner wall  82  may (e.g., smoothly and/or continuously) radially taper inwards towards the axis  70 . The swirler inner wall  82  may thereby have a tubular conical geometry with tubular conical inner and outer wall surfaces  120  and  122 . The swirler inner wall  82  and its distal end  118  are each disposed radially with and axially overlapped by the swirler outer wall  80 . 
     The downstream swirler segment  78  includes an annular downstream swirler segment base  124  (e.g., a radial flange) and the swirler outer wall  80 . The downstream swirler segment  78  and each of its components  80  and  124  extends circumferentially around the axis  70 . 
     The downstream swirler segment base  124  is abutted axially against the intermediate swirler segment  77 . The downstream swirler segment base  124 , for example, may be coupled (e.g., bonded to) the intermediate swirler segment surface  106 . The downstream swirler segment base  124  extends axially along the axis  70  from the intermediate swirler segment  77  to an annular downstream swirler segment surface  126 . 
     Referring to  FIG. 6A , the downstream swirler segment base  124  is configured with a downstream set of vanes  128 . These downstream vanes  128  are arranged circumferentially around the axis  70  in an annular array. Each downstream vane  128  is circumferentially separated from each circumferentially adjacent (e.g., neighboring) downstream vane  128  by a respective gap  130 . The gaps  130  collectively form a downstream airflow inlet  132  into the swirler  64 ; see also  FIG. 3 . The downstream vanes  128  may be configured such that air entering the swirler  64  through the downstream airflow inlet  132  generally flow in the first circumferential direction  96  (e.g., the clockwise direction) about the axis  70 . Alternatively, referring to  FIG. 6B , the downstream vanes  128  may be configured such that air entering the swirler  64  through the downstream airflow inlet  132  generally flows in the second circumferential direction  98  (e.g., the counterclockwise direction) about the axis  70 . This circumferential direction for the downstream vanes  128  may be the same as the circumferential direction for the upstream vanes  90  and/or the intermediate vanes  108 . However, in other embodiments, the circumferential direction for the downstream vanes  128  may be the opposite as the circumferential direction for the upstream vanes  90  and/or the intermediate vanes  108 . 
     In the specific embodiment of  FIG. 3 , the downstream vanes  128  are arranged at a joint between the swirler segments  77  and  78 . With this arrangement, each gap  130  may extend partially axially into the downstream swirler segment  78  from a castellated surface  134  of the segment at the to a gap end surface  136 . Of course, in other embodiments, each gap  130  may be formed completely axially within the swirler  64  and, for example, its downstream swirler segment  78 . 
     The swirler outer wall  80  projects out from the downstream swirler segment base  124  and extends axially (in the downstream direction along the axis  70 ) to an annular distal outer wall end  138 . As the swirler outer wall  80  extends towards the distal outer wall end  138 , the swirler outer wall  80  may (e.g., smoothly and/or continuously) radially taper inwards towards the axis  70 . The swirler outer wall  80  may thereby have a generally tubular conical geometry with a tubular conical inner wall surface  140 . The swirler outer wall  80  axially overlaps and circumscribes the swirler outer wall  80 . 
     The swirler  64  is configured such that the distal inner wall end  118  and the distal outer wall end  138  are axially offset from one another along the axis  70 . The distal inner wall end  118  of  FIG. 3 , for example, is axially recessed into the swirler  64  from the distal outer wall end  138 . More particularly, the distal inner wall end  118  is disposed an axial distance (d) upstream of the distal outer wall end  138 . The distal outer wall end  138  may thereby define a downstream most surface of the swirler  64 ; e.g., a dump plane of the swirler  64 . 
     The inner passage  84  of  FIG. 3  is an inner bore of the swirler  64 . This inner passage  84  is formed radially within and by each of the swirler segments  76  and  77 . The inner passage  84  is fluidly coupled with the upstream airflow inlet  94  and the intermediate airflow inlet  112 . The inner passage  84  of  FIG. 3  extends from the airflow inlets  94  and  112  to an inner nozzle outlet  142 . This inner nozzle outlet  142  is defined by and radially within the swirler inner wall  82  at the distal inner wall end  118 . 
     The outer passage  86  of  FIG. 3  is an annular passage formed by the swirler segments  77  and  78 . This outer passage  86  is formed radially between the swirler inner wall  82  and the swirler outer wall  80 . The outer passage  86  is fluidly coupled with the downstream airflow inlet  132 . The outer passage  86  of  FIG. 3  extends from the downstream airflow inlet  132  to an outer nozzle outlet  144 . This outer nozzle outlet  144  is defined by and radially between the swirler inner and outer walls  82  and  80  at their distal ends  118  and  138 . 
     The outer passage  86  and its nozzle outlet  144  are configured with an inner diameter (D sw-ex ) at the distal outer wall end  138 . This diameter (D sw-ex ) is measured from, for example, the inner wall surface  140  of the swirler outer wall  80  on a corner between that surface  140  and an annular distal outer wall end surface  146 . 
     Referring to  FIG. 2 , the swirler  64  is mated with the bulkhead  62 . In particular, the swirler inner and outer walls  82  and  80  project axially into or through a respective aperture  148  in the bulkhead  62 . The swirler  64  is mounted to the bulkhead  62 . The downstream swirler segment  78 , for example, may be bonded (e.g., brazed or welded) and/or otherwise connected to the bulkhead  62  and, for example, a shell  150  of the bulkhead  62 . 
     The fuel injector  66  includes a fuel injector stem  152  and a fuel injector nozzle  154 . The fuel injector stem  152  is configured to support and route fuel to the fuel injector nozzle  154 . The fuel injector nozzle  154  is cantilevered from the fuel injector stem  152 , and projects along the axis  70  partially into the inner bore of the swirler  64 . A tip  156  of the fuel injector nozzle  154  is thereby disposed within the inner passage  84 . 
     Referring to  FIG. 7 , the fuel injector nozzle  154  includes a plurality of nozzle orifices  158  arranged circumferentially about the axis  70  in an annular array; see also  FIG. 8 . These nozzle orifices  158  may be axially aligned with (e.g., axially overlapped by) the swirler inner wall  82  and its inner wall surface  120 . One or more or each of these nozzle orifices  158  is configured to direct a jet of fuel to impinge against the swirler inner wall  82  and its inner wall surface  120 . 
     The fuel injector nozzle  154  may also include a central nozzle orifice  160 ; see also  FIG. 8 . This central nozzle orifice  160  may be coaxial with the axis  70  and thereby centrally located between the nozzle orifices  158 . The central nozzle orifice  160  is configured to direct a jet of fuel along the axis  70 , through the inner nozzle outlet  142 , and into the combustion chamber  56 . A quantity of fuel provided by this central nozzle orifice  160  may be less than a collective quantity of fuel provided by the nozzle orifices  158 ; however, the present disclosure is not limited to such a relationship. 
     The mount  68  is configured to couple the fuel injector nozzle  154  to the swirler  64 . The mount  68  of  FIG. 7 , for example, includes a mount base  162  and a nozzle guide plate  164 . The mount base  162  is connected (e.g., bonded) to the upstream swirler segment  76  and, for example, to its castellated surface  100 . The mount base  162  is configured to capture the nozzle guide plate  164  in such a fashion that the nozzle guide plate  164  may float, to a limited degree, relative to the swirler  64 . The nozzle guide plate  164  in turn is mated with the fuel injector nozzle  154 . The fuel injector nozzle  154 , for example, projects through a bore in the nozzle guide plate  164 . The bore is sized such that the fuel injector nozzle  154  may slide axially along the axis  70  relative to the nozzle guide plate  164 . The mount  68  thereby may (e.g., loosely) couple and locate the fuel injector nozzle  154  to the swirler while enabling for slight shifts due to differential thermal expansion as well as vibrations. 
     During operation of the fuel injector assembly  60  of  FIG. 7 , the nozzle orifices  158  direct the jets of fuel to impinge against the swirler inner wall  82 . Upon hitting the inner wall surface  120 , the swirling air introduced into the inner passage  84  form the airflow inlets  94  and  112  (see  FIG. 3 ) may cause the fuel from the jets to form a thin film of fuel on the inner wall surface  120 . This film of fuel travels along the inner wall surface  120  towards the inner nozzle outlet  142 . At the inner nozzle outlet  142 , the film of fuel separates from the swirler inner wall  82  and is acted upon by swirling air exiting both the inner nozzle outlet  142  and the outer nozzle outlet  144 . The air may exit the nozzle outlets  142  and  144  at different speeds and thereby subject the separated fuel to a shear force. This shear force may cause the separated fuel to break up and atomize for combustion within the combustion chamber  56 . 
     Atomization quality may depend upon a thickness of the film of fuel as well as a velocity and swirl of the air from the inner and the outer passages  84  and  86 . The thickness of the film of fuel may depend upon an amount of fuel injected by the nozzle orifices  158  onto the swirler inner wall  82  and a length of travel along the swirler inner wall  82 . Therefore, in general, decreasing the length of travel of the film of fuel along the swirler inner wall  82  may result in a thinner film thickness. Thus, the distal inner wall end  118  is positioned forward of the distal outer wall end  138  as described above. By providing a thinner film thickness, the fuel injector assembly  60  of the present disclosure may be operable to facilitate improved fuel and air mixing and/or a reduction in combustion dynamics. 
     Referring to  FIG. 9 , the tip  156  of the fuel injector nozzle  154  is disposed an axial distance (D) along the axis  70  from the distal outer wall end  138 . By minimizing the equation (D−d)/D sw-ex , by decreasing the equation D/D sw-ex  and/or by increasing the equation d/D sw-ex , it has been found that combustion tones within the combustion chamber  56  may be reduced. For example, the fuel injector assembly  60  may be configured such that the equation (D−d)/D sw-ex  is less than or equal to one (e.g., less than 0.80) and/or greater than or equal to 0.25 (e.g., greater than 0.30). The fuel injector assembly  60 , for example, may be configured such that the equation (D−d)/D sw-ex  is between 0.35 and 0.68. 
     The fuel injector assembly  60  may be configured such that the equation D/D sw-ex  is less than or equal to one and/or greater than or equal to 0.40. The fuel injector assembly  60 , for example, may be configured such that the equation D/D sw-ex  is between 0.50 and 0.75. 
     The fuel injector assembly  60  may be configured such that the equation d/D sw-ex  is less than or equal to 0.20 and/or greater than or equal to 0.05. The fuel injector assembly  60 , for example, may be configured such that the equation d/D sw-ex  is between 0.07 and 0.15. 
     The swirler  64  is described above with a multi-segment body, where each segment  76 - 78  may be discretely formed and subsequently connected (e.g., bonded and/or mechanically fastened) to the other segment(s). However, in other embodiments, the swirler  64  may be configured such that any two or all of the segments  76 - 78  are formed integrally together as a unitary, monolithic body via, for example, casting and/or additive manufacturing. 
     In some embodiments, the swirler  64  may be configured with two airflow inlets. The swirler  64 , for example, may be configured without the upstream swirler segment  76 . In still other embodiments, the swirler  64  may be configured with more than three airflow inlets. 
     The fuel injector assembly  60  may be included in various turbine engines other than the one described above as well as in other types of fuel powered equipment. The fuel injector assembly  60 , for example, may be included in a geared turbine engine where a gear train connects one or more shafts to one or more rotors in a fan section, a compressor section and/or any other engine section. Alternatively, the fuel injector assembly  60  may be included in a turbine engine configured without a gear train. The fuel injector assembly  60  may be included in a geared or non-geared turbine engine configured with a single spool, with two spools (e.g., see  FIG. 1 ), or with more than two spools. The turbine engine may be configured as a turbofan engine, a turbojet engine, a propfan engine, a pusher fan engine or any other type of turbine engine. The present disclosure therefore is not limited to any particular types or configurations of turbine engines or equipment. 
     While various embodiments of the present disclosure have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the disclosure. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents.