Fuel nozzle / swirler assembly for gas turbine engine

Abstract

A fuel nozzle / swirler assembly includes a venturi tube including a heat shield retention wall. The back plate is connected to the venturi tube and includes a plurality of purge holes extending through the back plate. A ceramic matrix composite (CMC) heat shield includes a heat shield attachment wall joined between a heat shield retention wall of the venturi tube and the back plate, and a sealing member is disposed between the back plate and the CMC heat shield. A plurality of purge holes are disposed between the sealing member and the venturi tube and provide a flow of purge air through the plurality of purge holes to flow through the radial gap. The sealing member provides a force against the CMC heat shield such that the heat shield attachment wall of the CMC heat shield axially engages the heat shield retention wall of the venturi.

Description

Technical Field

[0001] The present disclosure relates to a fuel nozzle / swirler assembly for a gas turbine engine. Background Art

[0002] Some conventional gas turbine engines are known to include a dual annular premixing swirler (TAPS) fuel nozzle / swirler assembly. The TAPS fuel nozzle / swirler assembly generally includes a pilot mixer section and a main mixer section annularly arranged around the pilot mixer section. The pilot mixer section includes a metal pilot swirler, a pilot fuel injector, a metal venturi connected to the pilot swirler, a fuel nozzle housing connected to the metal pilot swirler and the metal venturi, and a metal heat shield connected to the downstream end of the metal venturi. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Features and advantages of the present disclosure will be apparent from the following description of various exemplary embodiments as illustrated in the drawings, wherein like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements.

[0004] Figure 1 is a schematic partial cross-sectional side view of an exemplary high bypass turbofan jet engine according to aspects of the present disclosure.

[0005] Figure 2 is a partial cross-sectional side view of an exemplary combustor according to aspects of the present disclosure.

[0006] Figure 3 According to aspects of the present disclosure Figure 2 An enlarged partial cross-sectional view of a TAPS fuel nozzle / swirler assembly taken at detail view 100 of FIG.

[0007] Figure 4 According to aspects of the present disclosure Figure 3 Detailed view of 150 Figure 3 An enlarged partial cross-sectional view of a portion of a fuel nozzle / swirler assembly.

[0008] Figure 5 According to aspects of the present disclosure, a heat shield and a venturi tube are formed through the CMC. Figure 4 A partial cross-sectional view taken at plane 5-5 of .

[0009] Figure 6 According to aspects of the present disclosure Figure 4 Detailed view of 184 Figure 4 An enlarged partial cross-sectional view of a portion of.

[0010] Figure 7 Describes aspects of the present disclosure Figure 6 An enlarged partial cross-sectional view of an alternative arrangement of a sealing member is shown in FIG.

[0011] Figure 8 Describes aspects of the present disclosure Figure 6 An enlarged partial cross-sectional view of another alternative arrangement of a sealing member is shown in FIG.

[0012] Fig. 9 Describes aspects of the present disclosure Figure 6 An enlarged partial cross-sectional view of another alternative arrangement of a sealing member is shown in FIG.

[0013] Fig.10 According to aspects of the present disclosure Figure 4 A partial cross-sectional view of an alternative arrangement of a fuel nozzle / swirler assembly.

[0014] Fig.11 According to aspects of the present disclosure Fig.10 A rear, front partial cross-sectional view of the back panel taken at plane 11-11.

[0015] Fig.12 According to aspects of the present disclosure, Fig.10 A front, rear partial cross-sectional view through an alternative CMC heat shield taken at a plane generally similar to plane 12 - 12 .

[0016] Fig.13 According to aspects of the present disclosure, Fig.10 A front, rear partial cross-sectional view through an alternative venturi tube taken at a plane generally similar to plane 13-13. DETAILED DESCRIPTION

[0017] Features, advantages and embodiments of the present disclosure are set forth or apparent by considering the following detailed description, drawings and claims.In addition, the following detailed description is exemplary and is intended to provide further explanation without limiting the scope of the present disclosure as claimed.

[0018] Various embodiments are discussed in detail below. Although specific embodiments are discussed, this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and scope of the present disclosure.

[0019] The terms "upstream" and "downstream" refer to relative directions relative to the flow of a fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, while "downstream" refers to the direction toward which the fluid is flowing.

[0020] The terms "front" and "rear" refer to opposite sides of an element and may be used interchangeably with the terms "upstream" and "downstream," respectively.

[0021] As used herein, the terms "axial" and "axially" refer to directions and orientations extending substantially parallel to the centerline of the turbine engine. Additionally, the terms "radial" and "radially" refer to directions and orientations extending substantially perpendicular to the centerline of the turbine engine. Additionally, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations extending in an arc around the centerline of the turbine engine.

[0022] As used herein, the term "metal" refers to materials including metals, such as but not limited to titanium, iron, aluminum, stainless steel, and nickel alloys. A metal material or alloy may be a combination of at least two or more elements or materials, at least one of which is a metal.

[0023] As used herein, the term "ceramic matrix composite" ("CMC") refers to a subgroup of composite materials and a subgroup of ceramics. The terms "CMC" and "CMC material" are used interchangeably herein. When an engine component includes or comprises a "CMC" or a "CMC material", it is understood that the engine component may include one or a combination of one or more ceramic matrix composites described herein. Such an engine component may also include non-ceramic matrix composites, such as metal alloys (e.g., CMC materials for airfoils and separate disks with dovetail grooves made of metal alloys).

[0024] More specifically, CMC refers to a class of materials that include a reinforcing material (e.g., reinforcing fibers) surrounded by a ceramic matrix. Typically, the reinforcing fibers provide structural integrity to the ceramic matrix. Some examples of matrix materials for CMCs may include, but are not limited to, non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), oxide ceramics (e.g., silicon oxycarbide, silicon oxynitride, aluminum oxide (Al 2 O 3 ), silicon dioxide (SiO 2 ), aluminosilicates or mixtures thereof) or mixtures thereof. Optionally, ceramic particles (e.g., oxides of Si, Al, Zr, Y and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite and montmorillonite) may also be included in the CMC matrix.

[0025] Some examples of reinforcing fibers for CMCs may include, but are not limited to, non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), non-oxide carbon-based materials (e.g., carbon), oxide ceramics (e.g., silicon oxycarbide, silicon oxynitride, aluminum oxide (AlO), and silicon nitride oxide (SiO). 2 O 3 ), silicon dioxide (SiO 2 ), aluminosilicates (e.g., mullite) or mixtures thereof) or mixtures thereof.

[0026] Typically, a particular CMC can be represented by its fiber type / matrix type combination. For example, C / SiC represents carbon fiber reinforced silicon carbide; SiC / SiC represents silicon carbide fiber reinforced silicon carbide, SiC / SiN represents silicon carbide fiber reinforced silicon nitride; SiC / SiC-SiN represents silicon carbide fiber reinforced silicon carbide / silicon nitride matrix mixture, etc. In other examples, a CMC may include a matrix and reinforcing fibers, the reinforcing fibers including an oxide-based material, such as aluminum oxide (Al2O3). 2 O 3 ), silicon dioxide (SiO 2 ), aluminosilicates and mixtures thereof. Aluminosilicates may include crystalline materials such as mullite (3Al 2 O 3 ·2SiO 2 ) and glassy aluminosilicates.

[0027] In certain embodiments, the reinforcing fibers may be bundled and / or coated before being incorporated into the matrix. For example, the fiber bundles may be formed into reinforcement tapes, such as unidirectional reinforcement tapes. Multiple tapes may be laid together to form a preform component. The fiber bundles may be impregnated with a slurry composition before or after forming the preform. The preform may then be subjected to heat treatment and subsequent chemical treatment to obtain a component formed of a CMC material having a desired chemical composition. For example, the preform may be cured or burned out to produce a high carbon residue in the preform, followed by melt infiltration ("MI") with silicon, or cured or pyrolyzed to produce a silicon carbide matrix in the preform, followed by chemical vapor infiltration ("CVI") with silicon carbide. Other steps may be taken before or after chemical vapor infiltration to improve the densification of the preform by injecting a liquid resin or polymer into the preform, followed by a heat treatment step to fill the voids with silicon carbide. The CMC materials used herein may be formed using any known method or method hereafter developed, including, but not limited to, melt infiltration, chemical vapor infiltration, polymer infiltration pyrolysis (PIP), and any combination thereof.

[0028] Such materials, as well as certain monolithic ceramics (i.e., ceramic materials that do not contain reinforcement materials), are particularly suitable for high temperature applications. In addition, these ceramic materials are lightweight compared to metal alloys (e.g., superalloys), yet can provide strength and durability to components made therefrom. As a result, such materials are currently being considered for use in many gas turbine components used in the high temperature sections of gas turbine engines, such as airfoils (e.g., turbines and buckets), combustors, shrouds, and other similar components that would benefit from the lighter weight and higher temperature capabilities that these materials can provide.

[0029] Some conventional gas turbine engines are known to include a dual annular premixing swirler (TAPS) fuel nozzle / swirler assembly. The TAPS fuel nozzle / swirler assembly typically includes a pilot mixer portion and a main mixer portion arranged annularly around the pilot mixer portion. The pilot mixer portion includes a metal pilot swirler, a pilot fuel injector, a metal venturi connected to the pilot swirler, a fuel nozzle housing connected to the metal pilot swirler and the metal venturi, and a metal heat shield connected to the downstream end of the metal venturi. The metal heat shield is typically arranged at the rear end of the venturi on the combustion chamber side of the fuel nozzle assembly, and is radially arranged between the outlet of the venturi and the fuel nozzle housing to protect the fuel nozzle housing from the heat of the flame and combustion products in the combustion chamber. The metal venturi is affected by the flame and high temperature during combustion, may be damaged over time, and the heat shield needs to be replaced. Replacing the heat shield can be a cumbersome and expensive process that requires downtime to repair the engine.

[0030] The present disclosure solves the above-mentioned problems by implementing a ceramic matrix composite (CMC) heat shield in a TAPS fuel nozzle / swirler assembly. Specifically, the TAPS fuel nozzle / swirler assembly provides an arrangement in which the CMC heat shield is installed between the attachment wall of the venturi tube and the backing plate, and a sealing member is arranged in the backing plate to apply an axial force against the CMC heat shield, thereby axially retaining the CMC heat shield while allowing radial and circumferential expansion between the CMC heat shield, the metal backing plate and the venturi tube. In addition, the backing plate includes a purge hole arranged between the venturi tube and the sealing member, and a radial gap is provided between the CMC heat shield and the venturi tube to allow a purge air flow from the purge hole to pass through the radial gap to purge any hot gas that may be sucked between the CMC heat shield, the venturi tube and the backing plate. Therefore, a more durable heat shield can be achieved, which requires less maintenance and fewer heat shield replacement times, while also providing an easier device for replacing the heat shield (if necessary).

[0031] Now referring to the accompanying drawings, Figure 1 1 is a schematic partial cross-sectional side view of an exemplary high bypass turbofan jet engine 10, referred to herein as "engine 10," which may include various embodiments of the present disclosure. Although further described below with reference to a ducted turbofan engine, the present disclosure is also applicable to turbomachinery in general, including turbojets, turbopropellers, and turboshaft gas turbine engines, including marine and industrial turbine engines and auxiliary power units. Furthermore, the present disclosure is not limited to ducted fan-type turbine engines (e.g., Figure 1Instead of the ducted fan type turbine engine shown in FIG. 1 , it can be implemented in an unducted fan (UDF) type turbine engine, which can include a double annular premixing swirler (TAPS) combustor. Figure 1 As shown, engine 10 has a longitudinal centerline axis 12 extending therethrough from an upstream end 98 of engine 10 to a downstream end 99 of engine 10 for reference. Generally, engine 10 may include a fan assembly 14 and a core engine 16 disposed downstream of fan assembly 14.

[0032] The core engine 16 may generally include a casing 18 that defines an annular inlet 20 of the core engine 16. The casing 18 surrounds or at least partially forms a supercharger or low pressure (LP) compressor 22, a high pressure (HP) compressor 24, a combustor 26, an HP turbine 28, an LP turbine 30, and an ejection exhaust nozzle 32 in series flow relationship. An HP rotor shaft 34 drivingly connects the HP turbine 28 to the HP compressor 24. An 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 certain embodiments, as shown in FIG. Figure 1 As shown, the LP rotor shaft 36 can be connected to the fan shaft 38 via a reduction gearbox assembly 40, such as in an indirect drive or gear drive configuration. In other embodiments, although not shown, the engine 10 can also include an intermediate pressure (IP) compressor and an IP turbine that can rotate with an intermediate pressure shaft connecting the IP turbine and the IP compressor.

[0033] like Figure 1 As shown, the fan assembly 14 includes a plurality of fan blades 42 that are coupled to and extend radially outward from the fan shaft 38. An annular fan case or nacelle 44 circumferentially surrounds the fan assembly 14 and / or at least a portion of the core engine 16. The nacelle 44 may be supported relative to the core engine 16 by a plurality of circumferentially spaced outlet guide vanes or struts 46. In addition, at least a portion of the nacelle 44 may extend over an outer portion of the core engine 16, thereby defining a bypass airflow passage 48 between the nacelle 44 and the outer casing 18.

[0034] Figure 2 yes Figure 1 A cross-sectional side view of an exemplary combustor 26 of the core engine 16 is shown in FIG. Figure 2An example of a double annular premixing swirler (TAPS) type combustor is depicted, and is generally an annular combustor that extends circumferentially around a longitudinal centerline axis 12. The combustor 26 includes a shroud 60 and a combustor liner 50, the combustor liner 50 having an inner liner 52 and an outer liner 54. Each of the inner liner 52 and the outer liner 54 is an annular liner that extends circumferentially around the longitudinal centerline axis 12. A dome 56 extends between the inner liner 52 and the outer liner 54. The inner liner 52, the outer liner 54, and the dome 56 together define a combustion chamber 62. In the combustion chamber 62, an initial chemical reaction of an ignited pilot fuel-oxidant mixture 57 injected into the combustion chamber 62 by a pilot swirler portion (described below) of a fuel nozzle / swirler assembly 58 connected to the dome 56 can occur to produce combustion gases 86. In higher power operation of the combustor 26, the main fuel-oxidant mixture 61 is injected into the combustion chamber 62 through the main swirler portion of the fuel nozzle / swirler assembly 58 (described below) to produce combustion gases 86. The combustion gases 86 then flow further downstream into the HP turbine 28 and the LP turbine 30 ( Figure 1 ).

[0035] The combustor 26 also includes an outer shell 64 extending circumferentially about the longitudinal centerline axis 12, and an inner shell 65 also extending circumferentially about the longitudinal centerline axis 12. An outer flow passage 88 is defined between the outer shell 64 and the outer liner 54, and an inner flow passage 90 is defined between the inner shell 65 and the inner liner 52. The outer shell 64 and the inner shell 65 meet at the upstream end 70 of the combustor 26 and together define a plenum 66. The outer shell 64 and the inner shell 65 are also connected to a diffuser 68. The diffuser 68 is in flow communication with the HP compressor 24 to receive a compressed air flow 82 from the high pressure compressor 24 and provide the compressed air flow 82 to the plenum 66. An igniter 69 may be connected to the outer shell 64 and extend through the outer flow passage 88 and the outer liner 54. The igniter 69 provides an ignition source (e.g., a spark) to ignite the pilot fuel-oxidant mixture 57. The main fuel-oxidizer mixture 61 may be ignited via the ignited pilot fuel-oxidizer mixture 57 , or the igniter 69 may also be used to ignite the main fuel-oxidizer mixture 61 .

[0036] Reference back Figure 1In operation, a volume of inlet air 72 enters the nacelle 44 at the nacelle inlet 76, and the inlet air 72 is propelled through the fan assembly 14. A portion of the inlet air 72 propelled by the fan assembly 14 enters the LP compressor 22 as a compressor inlet airflow 80, where it is compressed by the LP compressor 22 to produce compressed air 81. The compressed air 81 then flows to the HP compressor 24, where the compressed air 81 is further compressed to produce compressed air 82. The compressed air 82 from the HP compressor 24 is passed through the diffuser 68 ( Figure 2 ) enters the combustor 26. Another portion of the inlet air 72 propelled by the fan assembly 14 flows through the bypass airflow passage 48, thereby providing a bypass airflow 78. The bypass airflow 78 provides the majority of the thrust for the engine 10.

[0037] Reference back Figure 2 As discussed above, the compressed air 82 flows through the diffuser 68, which reduces the velocity of the compressed air 82 entering the plenum 66 and increases the pressure of the compressed air 82 within the plenum 66. A portion of the compressed air 82 in the plenum 66 enters the shroud 60 (schematically shown as compressed air 82a), while another portion of the compressed air 82 is passed to the outer flow passage 88 and the inner flow passage 90 (schematically shown as compressed air 82b). The compressed air 82a is mixed with the fuel through the fuel nozzle / swirler assembly 58 to generate the pilot fuel-oxidant mixture 57 and the main fuel-oxidant mixture 61, which are then ignited to generate the combustion gases 86. The compressed air 82b in the outer flow passage 88 and the inner flow passage 90 can be used for various purposes, such as dilution air (not shown) provided to the combustion chamber 62 through dilution openings (not shown) in the inner liner 52 and the outer liner 54, for cooling the inner liner 52 and the outer liner 54, or for cooling other components of the engine 10.

[0038] Reference back Figure 1 , the combustion gases 86 flow from the combustor 26 to the high pressure turbine 28, where work is extracted from the combustion gases 86 to rotate the high pressure turbine 28. The rotation of the high pressure turbine 28 thereby supports the rotation of the high pressure compressor 24 via the HP rotor shaft 34. The combustion gases 86 then continue to flow downstream of the HP turbine 28 to the LP turbine 30, where additional work is extracted from the combustion gases 86 to rotate the LP turbine 30. The rotation of the LP turbine 30 thereby supports the rotation of the LP compressor 22 via the LP rotor shaft 36, and also supports the rotation of the fan assembly 14 via the fan shaft 38 connected to the reduction gearbox assembly 40. The remaining combustion gases 86 pass through the jet exhaust nozzle 32 and provide core engine thrust.

[0039] Figure 3 According to aspects of the present disclosure Figure 2100 of the detailed view of FIG. 100 is an enlarged partial cross-sectional view of the fuel nozzle / swirler assembly 58. The fuel nozzle / swirler assembly 58 includes a pilot mixer 102, a main mixer 104, and a fuel manifold 106 positioned therebetween. The pilot mixer 102 includes an annular venturi 108 extending circumferentially around a fuel nozzle centerline axis 112 and a pilot fuel injector 110 mounted within the venturi 108. In addition, the pilot mixer 102 includes a first pilot swirler 114, which is composed of a plurality of swirl vanes arranged radially outward of the pilot fuel injector 110. The pilot swirler 114 is oriented generally parallel to the fuel nozzle centerline axis 112 and includes a plurality of vanes for swirling air traveling therethrough. During an engine operating cycle, fuel and air are generally always provided to the pilot mixer 102.

[0040] The pilot fuel injector 110 may be a pure air injection (PAB) type fuel injector, wherein pre-filming and atomization of the fuel provided thereby is accomplished almost entirely by injecting air into the fuel. Fuel is provided by a fuel pipe 142 in flow communication with a fuel source (not shown) to a conduit 144 connected to the pilot fuel injector 110. The fuel is injected from the pilot fuel injector 110 into the venturi 108. The pilot fuel-oxidizer mixture 57 ( Figure 2 ). The pilot fuel-oxidant mixture 57 is then injected into the combustion chamber 62 where it is ignited and combusted to produce combustion gases 86.

[0041] The main mixer 104 is attached to a pilot fuel nozzle housing 122 surrounding the pilot mixer 102. The main mixer 104 includes an annular main housing 124 that radially surrounds the pilot fuel nozzle housing 122, wherein the main housing 124 defines an annular cavity 126 and a main swirler 128. The main swirler 128 includes a first swirler 130 that is oriented substantially radially relative to the fuel nozzle centerline axis 112 and includes a plurality of vanes (shown generally) for swirling the compressed air 82a flowing therebetween. The vanes are substantially uniformly circumferentially spaced apart and define a plurality of substantially uniform channels between adjacent vanes. The main swirler 128 also includes a second swirler 134 that is oriented substantially parallel to the fuel nozzle centerline axis 112. The second swirler 134 also includes a plurality of vanes (shown generally) for swirling the compressed air 82a flowing therebetween. The vanes of the second swirler 134 are substantially evenly circumferentially spaced apart, thereby defining a plurality of substantially even passages therebetween.

[0042] As described above, the fuel manifold 106 is located between the pilot mixer 102 and the main mixer 104 and is in flow communication with a fuel supply (not shown). A plurality of main fuel injectors 138 are disposed at the fuel manifold 106, and the pilot fuel nozzle housing 122 includes a plurality of main fuel injector holes 140 therethrough. The main fuel injectors 138 are arranged to inject fuel into the annular cavity 126 of the main mixer 104 through the main fuel injector holes 140. Figure 3 As shown, the main fuel injector 138 is preferably positioned so that the fuel is provided into the annular cavity 126 downstream of the first swirler 130 and downstream of the second swirler 134. The main fuel-oxidant mixture 61 ( Figure 2 ). The main fuel-oxidant mixture 61 then flows into the combustion chamber 62 where the main fuel-oxidant mixture 61 is ignited and combusted to produce combustion gases 86.

[0043] Still refer to Figure 3 , a back plate 146 is connected to the downstream end 123 of the pilot fuel nozzle housing 122, and the back plate 146 is connected to the venturi 108. A ceramic matrix composite (CMC) heat shield 148 is also connected to the fuel nozzle / swirler assembly 58 on the downstream side of the back plate 146. The connection of the CMC heat shield 148 to the fuel nozzle / swirler assembly 58 will now be described in more detail.

[0044] Figure 4 is Figure 3 An enlarged partial cross-sectional view of the fuel nozzle / swirler assembly 58 taken at the detailed view 150 of FIG. Figure 4 An example arrangement of an assembly of a CMC heat shield 148 with the venturi 108 and the backing plate 146 is depicted. The CMC heat shield 148 may include a protective coating 149 on the back side of the CMC heat shield 148. Figure 4As shown, the venturi 108 includes a backing plate connection surface 152, which may be an outer surface of the venturi 108 that extends circumferentially about the fuel nozzle centerline axis 112. The backing plate 146 includes a venturi connection surface 154, which may be a radially inner surface of the backing plate 146 that extends circumferentially about the fuel nozzle centerline axis 112. The backing plate 146 is axially mounted on the venturi 108 so that the rear side 160 of the backing plate 146 abuts the clock tang 158 (described below), and then the backing plate connection surface 152 and the venturi connection surface 154 are brazed together at the brazed joint 156 to connect the backing plate 146 to the venturi 108. While the backing plate 146 and the venturi 108 may be joined together by brazing to form the brazed joint 156 , an additional level of safety may be achieved by attaching a snap ring 180 disposed within a snap ring groove 182 in the venturi 108 .

[0045] The venturi 108 includes a heat shield retaining wall 164 disposed at a downstream end 165 of the venturi 108, which extends in a circumferential direction about the fuel nozzle centerline axis 112. The CMC heat shield 148 has a front surface 167 and a rear surface 169, and a venturi attachment recess 171 extends from the rear surface 169 into the CMC heat shield 148 and extends circumferentially about the fuel nozzle centerline axis 112. By means of the venturi attachment recess 171, the CMC heat shield 148 includes a heat shield attachment wall 166, which extends circumferentially about the fuel nozzle centerline axis 112. The venturi attachment recess 171 engages with the heat shield retaining wall 164 of the venturi 108. The axial thickness 168 of the heat shield attachment wall 166 is such that when the CMC heat shield 148 is assembled to the venturi 108 before forming the brazed joint 156, and then the backing plate 146 is assembled to the venturi 108 to abut the clock tang 158, and then the brazed joint 156 is formed, the heat shield attachment wall 166 is engaged between the heat shield retaining wall 164 of the venturi 108 and the backing plate 146 to provide an axial gap 170 between the backing plate 146 and the CMC heat shield 148.

[0046] Figure 5 1 is a partial cross-sectional view taken at plane 5-5 through the CMC heat shield 148 and the venturi 108. As discussed above, the heat shield retaining wall 164 ( Figure 4 ) includes a clock shank 158. Figure 5 As shown, three clock tangs 158 are included in the venturi 108 and are shown as being circumferentially spaced apart at an angular spacing 172. Figure 5, the angular spacing 172 is an equal circumferential spacing about the fuel nozzle centerline axis 112. Of course, the present disclosure is not limited to three clock tangs 158, but may alternatively include more than three clock tangs 158 or less than three clock tangs 158. Furthermore, the clock tangs 158 need not be equally spaced, and may be arranged at any unequal angular spacing about the heat shield retention wall 164.

[0047] exist Figure 5 , it can be seen that the CMC heat shield 148 includes a corresponding number of clock slots 162, which corresponds to the number of clock tangs 158 and has a corresponding angular spacing 172. The clock slots 162 engage the clock tangs 158 to circumferentially position the CMC heat shield 148 on the venturi 108. Referring back to Figure 4 , the radial dimensions of the radially outer ends of the clock tangs 158 and the radial dimensions of the clock slots 162 provide a radial gap 178 between the heat shield retaining wall 164 of the venturi 108 and the heat shield attachment wall 166 of the CMC heat shield 148. The radial gap 178 allows radial adjustment to compensate for different expansion rates between the CMC heat shield 148 and the metal venturi 108. In addition, as will be explained in more detail below, the radial gap 178 is used to purge hot gases that may be drawn between the CMC heat shield 148 and the metal venturi 108.

[0048] Still refer to Figure 4 , the back plate 146 includes a sealing recess 174 located in the rear side 160 of the back plate 146, wherein the sealing recess 174 extends circumferentially around the fuel nozzle centerline axis 112. A sealing member 176 is disposed within the sealing recess 174. The sealing member 176 is configured to provide an axial force against an upstream side 179 of the CMC heat shield 148 in a downstream direction. The axial force provides an axial pressure against the upstream side 179 of the CMC heat shield 148 to maintain an axial engagement between the heat shield attachment wall 166 of the CMC heat shield 148 and the heat shield retaining wall 164 of the venturi 108. The sealing member 176 also provides a sealing function to prevent hot gases from being drawn between the venturi 108, the CMC heat shield 148, and the back plate 146. As will be described in more detail below, various types of sealing members 176 may be implemented.

[0049] Figure 6 According to aspects of the present disclosure Figure 4 Detailed view of 184 Figure 4 An enlarged partial cross-sectional view of a portion of the Figure 6 , it can be seen that the back plate 146 includes a plurality of purge holes 186 ( Figure 6 One is shown in FIG. 1 ). Although Figure 6One purge hole 186 is depicted, but multiple purge holes 186 may be disposed through the back plate 146, circumferentially spaced about the fuel nozzle centerline axis 112. The purge holes 186 are disposed radially inward of the seal member 176 and radially outward of the venturi connection surface 154 of the back plate 146. The purge holes 186 provide a flow of purge air 82c (which is a portion of the compressed air 82a flowing through the fuel nozzle / swirler assembly 58) to a purge cavity 188 extending circumferentially about the fuel nozzle centerline axis 112. As described above, the rear side 160 of the back plate 146 abuts the clock tang 158, but as described above, the back side 160 of the back plate 146 abuts the clock tang 158. Figure 6 As shown in the lower portion of the drawing, where the clock tang 158 is not provided, there is a gap so that the purge air 82c can flow out of the purge cavity 188 and through the radial gap 178 between the clock groove 162 of the CMC heat shield 148 and the clock tang 158 of the heat shield retaining wall 164 to purge any hot gas that may be drawn into the radial gap 178 and / or the purge cavity 188.

[0050] exist Figure 6 In the embodiment, the back plate 146 further includes a purge flow recess 190 arranged radially outside the sealing recess 174, and a plurality of second purge flow holes 192 arranged through the back plate 146 to provide a purge air 82d flow to the purge flow recess 190 therethrough. The purge flow recess 190 extends circumferentially around the fuel nozzle centerline axis 112. Then, the purge air 82d flow flowing to the purge flow recess 190 through the second purge flow holes 192 can purge the axial gap 170 of any hot gas that may have been sucked into the axial gap 170 by purging the hot gas radially outside the axial gap 170. Although Figure 6 One second purge flow hole 192 is depicted, but a plurality of second purge flow holes 192 are arranged circumferentially spaced apart through the backing plate 146 to provide a purge air 82d flow to the purge flow recess 190. In addition, the backing plate 146 may include a plurality of cooling air flow holes 194 arranged through the radially outer end of the backing plate 146. The cooling air flow holes 194 may provide an impingement cooling air flow 82e to the radially outer side 195 of the CMC heat shield 148. Although in Figure 6 One cooling air flow hole 194 is shown in FIG. 1 , but a plurality of cooling air flow holes 194 may be arranged through the back plate 146 and may be circumferentially spaced about the fuel nozzle centerline axis 112 .

[0051] exist Figure 6In the embodiment of the present invention, the sealing member 176 is depicted as a brush seal 196, which includes a metal brush 198, such as a wire bristle made of a cobalt superalloy metal, which allows the bristles to be bent up to forty-five degrees. As discussed above, the sealing member 176 provides an axial force against the upstream side 179 of the CMC heat shield 148. When the brush seal 196 is implemented, the bristles of the metal brush 198 are allowed to bend and push against the upstream side 179 of the CMC heat shield 148 to provide the axial force. The bristles of the metal brush 198 also provide a sealing function to prevent hot gases from being drawn into the radially inner side of the sealing member 176 and to prevent the purge air flow from the purge chamber 188 from flowing to the radially outer side of the sealing member 176.

[0052] Figure 7 Describes aspects of the present disclosure Figure 6 An enlarged partial cross-sectional view of an alternative arrangement of the sealing member 176 is shown in FIG. Figure 7 In, with Figure 6 The same components have the same reference numerals. Figure 7 Aspects include a C-seal 200 in place of the brush seal 196. Similar to the brush seal 196, the C-seal 200 extends circumferentially about the fuel nozzle centerline axis 112. The C-seal 200 may be made of a flexible metal alloy material that, when axially compressed (i.e., compressed in the longitudinal direction L) within the sealing recess 174, provides an axial force against the upstream side 179 of the CMC heat shield 148 and also provides a sealing function between the C-seal 200 and the upstream side 179 of the CMC heat shield 148.

[0053] Figure 8 Describes aspects of the present disclosure Figure 6 An enlarged partial cross-sectional view of another alternative arrangement of the sealing member 176 is shown in FIG. Figure 8 In, with Figure 6 The same components have the same reference numerals. Figure 8 Aspects include a W-type seal 202 in place of the brush seal 196. Similar to the brush seal 196, the W-type seal 202 extends circumferentially about the fuel nozzle centerline axis 112. The W-type seal 202 may be made of a flexible metal alloy material that, when axially compressed (i.e., compressed in the longitudinal direction L) within the seal recess 174, provides an axial force against the upstream side 179 of the CMC heat shield 148 and also provides a sealing function between the W-type seal 202 and the upstream side 179 of the CMC heat shield 148.

[0054] Fig. 9 According to another aspect of the present disclosure, Figure 6An enlarged partial cross-sectional view of yet another alternative arrangement of the sealing member 176 is shown in FIG. Fig. 9 In, with Figure 6 The same components have the same reference numerals. Fig. 9 Aspects include a rope seal 204 in place of the brush seal 196. Similar to the brush seal 196, the rope seal 204 extends circumferentially about the fuel nozzle centerline axis 112. The rope seal 204 may be made of a metal alloy material or any other material for providing a sealing function that provides an axial force against the upstream side 179 of the CMC heat shield 148 when axially compressed (i.e., compressed in the longitudinal direction L) within the sealing recess 174 and also provides a sealing function between the rope seal 204 and the upstream side 179 of the CMC heat shield 148.

[0055] Fig.10 According to another aspect of the present disclosure Figure 4 A partial cross-sectional view of an alternative arrangement of a fuel nozzle / swirler assembly 58 . Fig.11 According to aspects of the present disclosure, Fig.10 A front partial cross-sectional view of the rear portion of the back plate 146a taken at a plane substantially similar to plane 11-11 of FIG. Fig.11 For the sake of clarity, the Fig.10 1 and 108a, and only a cross-sectional view through the alternative backing plate 146a is depicted. Fig.10 and Fig.11 , Fig.10 and Fig.11 Aspects and Figure 4 Some of the differences between the aspects are, Fig.10 and Fig.11 The heat shield retaining wall 164a of the alternative venturi tube 108a does not include Figure 4 aspect of the clock tang 158 of the venturi 108, and Fig.10 and Fig.11 Aspects of the alternative CMC heat shield 148a do not include Figure 4 In contrast, the clock slot 162 in the heat shield attachment wall 166 is formed in the Fig.10 and Fig.11 In one embodiment, the alternative back plate 146a includes a plurality of clock tangs 206 extending from a downstream side 208 of the alternative back plate 146a. Fig.11 As shown, the plurality of clock tangs 206 may be circumferentially spaced apart from one another at angular intervals 212 about the fuel nozzle centerline axis 112 . Fig.11Three clock tangs 206 are depicted, and are shown as being equally spaced at an angular spacing 212, but may alternatively include more than three clock tangs 206 or fewer than three clock tangs 206. Furthermore, the clock tangs 206 need not be equally spaced at the same angular spacing 212, and the clock tangs 206 may alternatively be spaced at different angular spacings. Furthermore, while Fig.10 and Fig.11 The clock tang 206 is depicted as being integral with the replacement back plate 146a, but the clock tang 206 may be a separate component part assembled to the replacement back plate 146a. For example, the clock tang 206 may alternatively be a separate part that is configured to be inserted into a slot or hole in the replacement back plate 146a (e.g., such as a rectangular or round clock pin 206a that is installed in a hole (not shown) in the back plate 148a). The heat shield attachment wall 166a of the CMC heat shield 148a may include a corresponding number of clock openings 210a that are configured (i.e., sized and circumferentially arranged) to accommodate the clock pins 206a when the fuel nozzle / swirler assembly 58 is assembled.

[0056] The replacement back plate 146a also includes a sealing recess 174a, a purge flow recess 190a, a plurality of purge holes 186a, a plurality of second purge flow holes 192a, and a plurality of cooling air flow holes 194a. The sealing recess 174a can be connected to the sealing recess 174 ( Figure 4 ) and the purge flow recess 190a may be identical to the purge flow recess 190( Figure 4 ) is the same. Similarly, the plurality of purge holes 186a may be the same as the plurality of purge holes 186( Figure 4 ), the plurality of second purge holes 192a may be the same as the plurality of second purge holes 192( Figure 4 ) are the same, and the plurality of cooling airflow holes 194a may be the same as the plurality of cooling airflow holes 194( Figure 4 ). In addition, Fig.10 In terms of Figures 6 to 9 Any sealing member 176 described in the aspects may be implemented within the sealing recess 174a.

[0057] Fig.12 According to aspects of the present disclosure, Fig.10 A front rear partial cross-sectional view through the alternative CMC heat shield 148a taken at a plane substantially similar to plane 12-12. Fig.12 , the alternative CMC heat shield 148a is seen to include a plurality of clock slots 210. The number of the plurality of clock slots 210 included in the alternative CMC heat shield 148a is the same as the number of clock tangs 206 provided in the alternative backplane 146a. Fig.12The alternative CMC heat shield 148a includes three clock slots 210 that are circumferentially spaced apart at angular spacings 214. The angular spacings 214 of the clock slots 210 are the same as the angular spacings 212 of the clock tangs 206. Fig.12 As shown, the clock tang 206 extends into the clock slot 210 and includes radial and circumferential clearance from the clock slot 210 to allow for radial and circumferential expansion between the metal replacement backing plate 146a and the replacement CMC heat shield 148a.

[0058] Fig.12 The alternative CMC heat shield 148a of the present invention also includes a plurality of axially extending (ie, extending in the longitudinal direction L through the alternative CMC heat shield ( Fig.10 )) of the purge flow groove 216, the purge flow groove 216 is arranged to pass through the radial inner surface 218 of the replacement heat shield attachment wall 166a of the replacement CMC heat shield 148a. The purge flow groove 216 is arranged to pass through the radial inner surface 218 of the replacement heat shield attachment wall 166a of the replacement CMC heat shield 148a. Fig.12 2 as having a generally semicircular cross-sectional shape, however, the purge flow slot 216 may alternatively have any other shape, including a rectangular cross-sectional shape, a triangular cross-sectional shape, an elliptical cross-sectional shape, and the like.

[0059] Fig.13 According to aspects of the present disclosure Fig.10 A front-rear partial cross-sectional view through the alternative venturi tube 108a taken at plane 13-13 of FIG. Fig.13 In the figure, the cross-sectional view of the alternative CMC heat shield 148a is omitted for clarity. Fig.13 In the embodiment of the present invention, the heat shield retaining wall 164a of the alternative venturi tube 108a includes a plurality of purge flow slots 220 through the front surface 222 of the heat shield retaining wall 164a. However, the heat shield retaining wall 164a may not include a clock slot 210 ( Fig.10 ) area (in Fig.13 Otherwise, the plurality of purge flow slots 220 may be arranged circumferentially spaced apart from each other by an angular spacing 226 about the fuel nozzle centerline axis 112 .

[0060] Each of the above aspects provides an arrangement of a TAPS fuel nozzle / swirler assembly including a CMC heat shield. The CMC heat shield is connected to the fuel nozzle / swirler assembly in such a manner that axial, radial, and circumferential expansion of the metal components of the fuel nozzle / swirler assembly can be easily accommodated by the CMC heat shield. In addition, the CMC heat shield provides better durability for the fuel nozzle / swirler assembly because the CMC heat shield does not need to be replaced as frequently as a metal heat shield, thereby requiring less engine downtime.

[0061] Although the above description is directed to some exemplary embodiments of the present disclosure, other changes and modifications will be apparent to those skilled in the art and may be made without departing from the spirit or scope of the present disclosure. In addition, even if not explicitly stated above, the features described in conjunction with one embodiment of the present disclosure may also be used in conjunction with other embodiments.

[0062] Further aspects of the disclosure are provided by the subject matter of the following clauses.

[0063] A fuel nozzle / swirler assembly for a combustor of a gas turbine, the fuel nozzle assembly comprising: a venturi tube, the venturi tube comprising a heat shield retaining wall arranged at a downstream end of the venturi tube; a back plate, the back plate being connected to the venturi tube and comprising a plurality of purge holes extending through the back plate; a ceramic matrix composite (CMC) heat shield, the ceramic matrix composite (CMC) heat shield comprising a heat shield attachment wall engaged between the heat shield retaining wall of the venturi tube and the back plate, an axial gap being provided between the CMC heat shield and the back plate, and a radial gap is provided between the heat shield attachment wall of the CMC heat shield and the heat shield retaining wall of the venturi tube; and a sealing member is arranged between the backing plate and the CMC heat shield, wherein the plurality of purge holes are arranged between the sealing member and the venturi tube and provide a purge air flow through the plurality of purge holes to flow through the radial gap, and the sealing member provides a force against the CMC heat shield to make the heat shield attachment wall of the CMC heat shield axially engage the heat shield retaining wall of the venturi tube.

[0064] A fuel nozzle / swirler assembly as described in the preceding clause, wherein said venturi and said backing plate are metallic.

[0065] A fuel nozzle / swirler assembly according to any preceding clause, wherein the backing plate further comprises a plurality of cooling air flow holes therethrough, the plurality of cooling air flow holes being arranged to provide cooling air flow to a radially outer side of the CMC heat shield.

[0066] A fuel nozzle / swirler assembly according to any of the preceding clauses, wherein the venturi tube extends circumferentially around a fuel nozzle centerline axis of the fuel nozzle / swirler assembly and includes a back plate connection surface, and the back plate extends circumferentially around the fuel nozzle centerline axis and includes a venturi tube connection surface, the venturi tube connection surface being connected to the back plate connection surface.

[0067] A fuel nozzle / swirler assembly according to any preceding clause, wherein the back plate connection surface and the venturi connection surface are connected via brazing to form a brazed joint.

[0068] A fuel nozzle / swirler assembly according to any of the preceding clauses, further comprising a snap ring, and the venturi tube comprises a snap ring groove, the snap ring being disposed in the snap ring groove to retain the backing plate.

[0069] A fuel nozzle / swirler assembly according to any preceding clause, wherein the back plate further comprises a sealing recess extending circumferentially about the fuel nozzle centreline axis, the sealing member being arranged within the sealing recess.

[0070] A fuel nozzle / swirler assembly according to any preceding clause, wherein the plurality of purge holes are arranged radially inwardly of the sealing recess and radially outwardly of the venturi connection surface.

[0071] A fuel nozzle / swirler assembly according to any of the preceding clauses, wherein the back plate further comprises a purge flow recess arranged radially outside the sealing recess, and a plurality of secondary purge flow holes, the plurality of secondary purge flow holes being arranged to pass through the back plate so as to provide a purge air flow to the purge flow recess and to provide a purge air flow to the axial gap between the back plate and the CMC heat shield so as to purge the axial gap.

[0072] A fuel nozzle / swirler assembly according to any preceding clause, wherein the sealing member comprises one of a brush seal, a C-seal, a W-seal or a rope seal.

[0073] A fuel nozzle / swirler assembly according to any of the preceding clauses, wherein the CMC heat shield extends circumferentially about a fuel nozzle centerline axis, the CMC heat shield having a front surface and a rear surface, and including a heat shield attachment wall extending circumferentially about the fuel nozzle centerline axis, and having a venturi tube attachment recess extending from the rear surface into the CMC heat shield.

[0074] A fuel nozzle / swirler assembly as claimed in any preceding clause wherein the venturi attachment recess engages the heat shield retaining wall.

[0075] A fuel nozzle / swirler assembly as in any preceding clause, wherein the heat shield retention wall includes at least one clock tang and the heat shield attachment wall of the CMC heat shield includes at least one clock slot that engages the at least one clock tang.

[0076] A fuel nozzle / swirler assembly according to any of the preceding clauses, wherein the backing plate includes at least one clocking tang extending from a downstream side of the backing plate, and the heat shield attachment wall of the CMC heat shield includes at least one clocking groove that engages the at least one clocking tang.

[0077] A fuel nozzle / swirler assembly according to any preceding clause, wherein the backing plate includes at least one clocking pin extending from a downstream side of the backing plate, and the heat shield attachment wall of the CMC heat shield includes at least one clocking opening engaged with the at least one clocking pin.

[0078] A fuel nozzle / swirler assembly according to any preceding clause, wherein the CMC heat shield comprises a plurality of purge flow slots arranged through a radially inner surface of the heat shield attachment wall.

[0079] A fuel nozzle / swirler assembly according to any preceding clause, wherein the heat shield retention wall of the venturi tube further comprises a plurality of purge slots in a front surface of the heat shield retention wall, the front surface engaging the heat shield attachment wall of the CMC heat shield.

[0080] The fuel nozzle / swirler assembly according to any of the preceding items further comprises: a pilot mixer; and a pilot fuel nozzle housing, the pilot fuel nozzle housing surrounding the pilot mixer, wherein the venturi tube is connected to the pilot mixer and the back plate is connected to the downstream end of the pilot fuel nozzle housing.

[0081] A fuel nozzle / swirler assembly according to any preceding clause, further comprising a main mixer connected to a radially outer side of the pilot fuel nozzle housing.

[0082] The fuel nozzle / swirler assembly according to any of the preceding items further comprises: a pilot fuel injector arranged to inject fuel into the pilot mixer; and a plurality of main fuel injectors arranged to inject fuel into the main mixer, wherein the pilot fuel nozzle housing comprises a plurality of main fuel injector holes passing therethrough, and the plurality of main fuel injectors are arranged to inject the fuel through the main fuel injector holes.

[0083] A gas turbine engine includes a compressor section, a combustor, and a turbine section in a series flow relationship, the combustor including a combustor liner, a dome assembly, and a plurality of fuel nozzle / swirler assemblies connected to the dome assembly, each of the plurality of fuel nozzle / swirler assemblies including: a venturi tube, the venturi tube including a heat shield retaining wall arranged at a downstream end of the venturi tube; a back plate, the back plate connected to the venturi tube and including a plurality of purge holes extending through the back plate; a ceramic matrix composite (CMC) heat shield including a heat shield retaining wall engaged between the heat shield retaining wall of the venturi tube and the back plate; a shield attachment wall, an axial gap is provided between the CMC heat shield and the backing plate, and a radial gap is provided between the heat shield attachment wall of the CMC heat shield and the heat shield retaining wall of the venturi tube; and a sealing member arranged between the backing plate and the CMC heat shield, wherein the plurality of purge holes are arranged between the sealing member and the venturi tube and provide a purge air flow through the plurality of purge holes to flow through the radial gap, and the sealing member provides a force against the CMC heat shield to make the heat shield attachment wall of the CMC heat shield axially engage the heat shield retaining wall of the venturi tube.

[0084] The gas turbine engine according to the preceding clause, wherein said venturi and said back plate are metallic.

[0085] A gas turbine engine according to any preceding clause, wherein the back plate further comprises a plurality of cooling air flow holes therethrough, the plurality of cooling air flow holes being arranged to provide cooling air flow to a radially outer side of the CMC heat shield.

[0086] A gas turbine engine according to any of the preceding clauses, wherein the venturi tube extends circumferentially around the fuel nozzle centerline axis of the fuel nozzle / swirler assembly and includes a back plate connection surface, and the back plate extends circumferentially around the fuel nozzle centerline axis and includes a venturi tube connection surface, the venturi tube connection surface being connected to the back plate connection surface.

[0087] A gas turbine engine according to any preceding clause, wherein the back plate connection surface and the venturi connection surface are connected via brazing to form a brazed joint.

[0088] A gas turbine engine according to any preceding clause, wherein the fuel nozzle / swirler assembly further comprises a snap ring, and the venturi tube comprises a snap ring groove, the snap ring being disposed in the snap ring groove to retain the back plate.

[0089] The gas turbine engine according to any of the preceding clauses, wherein the back plate further comprises a sealing recess extending circumferentially around the centerline axis of the fuel nozzle, the sealing member being arranged in the sealing recess.

[0090] The gas turbine engine according to any one of the preceding clauses, wherein the plurality of purge holes are arranged radially inwardly of the sealing recess and radially outwardly of the venturi tube connection surface.

[0091] A gas turbine engine according to any of the preceding clauses, wherein the back plate further comprises a purge flow recess arranged radially outside the sealing recess, and a plurality of secondary purge flow holes arranged to pass through the back plate to provide a purge air flow to the purge flow recess and the axial gap between the back plate and the CMC heat shield to purge the axial gap.

[0092] A gas turbine engine according to any preceding clause, wherein the sealing member comprises one of a brush seal, a C-seal, a W-seal or a rope seal.

[0093] A gas turbine engine according to any of the preceding clauses, wherein the CMC heat shield extends circumferentially about a fuel nozzle centerline axis, the CMC heat shield having a front surface and a rear surface, and including a heat shield attachment wall extending circumferentially about the fuel nozzle centerline axis, and having a venturi tube attachment recess extending from the rear surface into the CMC heat shield.

[0094] A gas turbine engine as claimed in any preceding clause, wherein the venturi attachment recess engages the heat shield retaining wall.

[0095] A gas turbine engine as claimed in any preceding clause, wherein the heat shield retention wall comprises at least one clock tang and the heat shield attachment wall of the CMC heat shield comprises at least one clock slot engaged with the at least one clock tang.

[0096] A gas turbine engine according to any of the preceding clauses, wherein the back plate includes at least one clock tang extending from a downstream side of the back plate, and the heat shield attachment wall of the CMC heat shield includes at least one clock groove engaged with the at least one clock tang.

[0097] A gas turbine engine according to any preceding clause, wherein the back plate includes at least one clock pin extending from a downstream side of the back plate, and the heat shield attachment wall of the CMC heat shield includes at least one clock opening engaged with the at least one clock pin.

[0098] A gas turbine engine as claimed in any preceding clause, wherein the CMC heat shield comprises a plurality of purge slots arranged through a radially inner surface of the heat shield attachment wall.

[0099] A gas turbine engine as in any preceding clause, wherein the heat shield retention wall of the venturi tube further comprises a plurality of purge slots in a front surface of the heat shield retention wall, the front surface engaging the heat shield attachment wall of the CMC heat shield.

[0100] A gas turbine engine according to any of the preceding clauses, wherein the fuel nozzle / swirler assembly further comprises a pilot mixer; and a pilot fuel nozzle housing, the pilot fuel nozzle housing surrounding the pilot mixer, wherein the venturi tube is connected to the pilot mixer and the back plate is connected to the downstream end of the pilot fuel nozzle housing.

[0101] A gas turbine engine according to any preceding clause, wherein the fuel nozzle / swirler assembly further comprises a main mixer connected to a radially outer side of the pilot fuel nozzle housing.

[0102] A gas turbine engine according to any of the preceding clauses, wherein the fuel nozzle / swirler assembly further comprises a pilot fuel injector arranged to inject fuel into the pilot mixer; and a plurality of main fuel injectors arranged to inject fuel into the main mixer, wherein the pilot fuel nozzle housing comprises a plurality of main fuel injector holes therethrough, and the plurality of main fuel injectors are arranged to inject the fuel through the main fuel injector holes.

Claims

1. A fuel nozzle / swirler assembly for a combustor of a gas turbine, characterized in that: The fuel nozzle assembly comprises: a venturi tube including a heat shield retaining wall disposed at a downstream end of the venturi tube; a backing plate connected to the venturi and including a plurality of purge holes extending through the backing plate; a ceramic matrix composite (CMC) heat shield including a heat shield attachment wall engaged between the heat shield retaining wall of the venturi tube and the backing plate, an axial gap being provided between the CMC heat shield and the backing plate, and a radial gap being provided between the heat shield attachment wall of the CMC heat shield and the heat shield retaining wall of the venturi tube; and a sealing member disposed between the backing plate and the CMC heat shield, wherein the plurality of purge holes are disposed between the sealing member and the venturi tube and provide a purge air flow through the plurality of purge holes to flow through the radial gap, and the sealing member provides a force against the CMC heat shield to cause the heat shield attachment wall of the CMC heat shield to axially engage the heat shield retaining wall of the venturi tube.

2. The fuel nozzle / swirler assembly according to claim 1, characterized in that in, The venturi and the back plate are metal.

3. The fuel nozzle / swirler assembly according to claim 1, characterized in that in, The backing plate further includes a plurality of cooling airflow holes therethrough, the plurality of cooling airflow holes being arranged to provide cooling air flow to a radially outer side of the CMC heat shield.

4. The fuel nozzle / swirler assembly according to claim 1, characterized in that in, The venturi extends circumferentially about a fuel nozzle centerline axis of the fuel nozzle / swirler assembly and includes a back plate connection surface, and the back plate extends circumferentially about the fuel nozzle centerline axis and includes a venturi connection surface connected to the back plate connection surface.

5. The fuel nozzle / swirler assembly according to claim 4, characterized in that in, The back plate connection surface and the venturi connection surface are connected via brazing to form a brazed joint.

6. The fuel nozzle / swirler assembly according to claim 4, characterized in that A snap ring is further included, and the venturi tube includes a snap ring groove, and the snap ring is disposed in the snap ring groove to retain the backing plate.

7. The fuel nozzle / swirler assembly according to claim 4, characterized in that in, The backing plate further includes a sealing recess extending circumferentially about the fuel nozzle centerline axis, the sealing member being disposed within the sealing recess.

8. The fuel nozzle / swirler assembly according to claim 7, characterized in that in, The plurality of purge holes are arranged radially inwardly of the sealing recess and radially outwardly of the venturi connection surface.

9. The fuel nozzle / swirler assembly according to claim 7, characterized in that: in, The backing plate further includes a purge flow recess arranged radially outside the sealing recess and a plurality of secondary purge flow holes arranged to pass through the backing plate to provide a purge air flow to the purge flow recess and to provide a purge air flow to the axial gap between the backing plate and the CMC heat shield to purge the axial gap.

10. The fuel nozzle / swirler assembly according to claim 7, characterized in that in, The sealing member includes one of a brush seal, a C-seal, a W-seal or a rope seal.

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