Turbine engine combustor including heat shield

Abstract

A combustor of a turbine engine has a combustion chamber for combusting fuel and air to generate heat. The fuel nozzle mixer assembly mixes fuel and air and injects the fuel and air into the combustion chamber for combustion. The assembly has a heat shield at the rear end for shielding the assembly from heat. The center body housing defines a cooling air flow chamber. A cooling air flow gap is defined between the centerbody housing and the heat shield. The center body housing has a cooling air outlet aperture between the cooling air flow cavity and the cooling air flow gap through which air passes and into the cooling air flow gap. The cooling air exits the cooling air flow gap at a cooling air outlet angle having a non-zero axial rearward component diverting combustion downstream to protect the component.

Description

Technical Field

[0001] The present disclosure generally relates to a turbine engine combustor including a heat shield. Background Art

[0002] For example, a turbine engine for an aircraft typically includes a fan and a turbocharger engine (turbo-engine) arranged in flow communication with each other. Within the core section, the combustor includes one or more fuel nozzle mixer assemblies arranged at the upstream end for introducing and mixing fuel and air for combustion in the combustion chamber. A heat shield on the downstream end of the fuel nozzle mixer assembly protects the fuel nozzle mixer assembly from the heat of combustion. The fuel nozzle mixer assembly is thermally protected in part by directing cooling air in a downstream direction, thereby transferring the combustion process and the generated heat downstream of the fuel nozzle mixer assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The foregoing and other features and advantages will be apparent from the following more particular description of various exemplary embodiments, as illustrated in the drawings, in which like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements.

[0004] Figure 1 is a schematic cross-sectional view of a turbine engine according to the present disclosure, taken along its longitudinal centerline axis.

[0005] Figure 2 is a schematic diagram of a combustor assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor.

[0006] Figure 3 is a schematic cross-sectional view of a portion of a fuel nozzle mixer assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor.

[0007] Figure 4A is a schematic cross-sectional view of a portion of a fuel nozzle mixer assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor.

[0008] Figure 4B is a schematic cross-sectional view of a portion of a fuel nozzle mixer assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor.

[0009] Figure 5A is a schematic cross-sectional view of a portion of a fuel nozzle mixer assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor.

[0010] Figure 5B is a schematic cross-sectional view of a portion of a fuel nozzle mixer assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor.

[0011] Figure 6A is a schematic cross-sectional view of a portion of a fuel nozzle mixer assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor.

[0012] Figure 6B is a schematic cross-sectional view of a portion of a fuel nozzle mixer assembly according to the present disclosure, taken along a longitudinal centerline axis of the combustor. DETAILED DESCRIPTION

[0013] Features, advantages, and embodiments of the present disclosure are set forth or apparent by considering the following detailed description, drawings, and claims. Furthermore, the following detailed description is exemplary and is intended to provide further explanation without limiting the scope of the disclosure as claimed.

[0014] Various embodiments of the present disclosure 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 present disclosure.

[0015] As used herein, the terms “first” and “second” may be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component.

[0016] The terms "upstream" and "downstream" refer to relative directions of fluid flow in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, and "downstream" refers to the direction toward which the fluid is flowing.

[0017] The terms "fore" and "aft" refer to relative positions within a turbine engine or vehicle and refer to the normal operating attitude of the turbine engine or vehicle. For example, with respect to a turbine engine, "fore" refers to a position on the turbine engine that is closer to the propeller or fan, while "aft" refers to a position on the turbine engine that is farther from the propeller or fan.

[0018] As used herein, when used with reference to a compressor, combustor, turbine, shaft, fan, or turbine engine component, the terms "low," "medium" (or "medium"), and "high," or their respective comparatives (e.g., "lower" and "higher," as applicable), refer to relative pressures, relative speeds, relative temperatures, or relative power outputs within the engine, unless otherwise specified. For example, a "low power" setting defines an engine or combustor that is configured to operate at a power output lower than the "high power" setting of the engine or combustor, while a "medium power" setting defines an engine or combustor that is configured to operate at a power output higher than the "low power" setting and lower than the "high power" setting. The terms "low," "medium" (or "medium"), or "high" in such terms may additionally or alternatively be understood as relative to a minimum allowable speed, pressure, or temperature, or relative to a minimum or maximum allowable speed, pressure, or temperature for normal, desired, steady-state, or other operation of the engine. A turbine engine's duty cycle includes, for example, low power operation, medium power operation, and high power operation. Low power operation includes, for example, engine start-up, idling, taxiing, and approach. Medium power operations include, for example, cruising, and high power operations include, for example, takeoff and climb.

[0019] Unless otherwise specified herein, the terms "coupled," "attached," "connected," and the like refer to both direct coupling, fixings, attachments, or connections as well as indirect coupling, fixings, attachments, or connections through one or more intermediate components or features.

[0020] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0021] As used herein throughout the specification and claims, approximating language is applied to modify any quantitative representation that can be permitted to vary without resulting in a change in the basic function to which it is related. Thus, values modified by terms such as "about," "approximately," "roughly," and "substantially" are not limited to the precise values specified. In at least some cases, approximate language can correspond to the precision of an instrument used to measure a value, or the precision of a method or machine used to construct or manufacture a component and / or system. For example, approximate language can refer to within a margin of 1%, 2%, 4%, 10%, 15%, or 20% of a single value, a range of values, and / or an endpoint of a defined range of values.

[0022] As used herein, the terms "air" and "oxidant" are used interchangeably when mixed together for combustion.

[0023] As used herein, a flow angle "having a non-zero axial aft component" refers to flow at least partially in an axial aft direction relative to the longitudinal centerline axis of the burner, including flow substantially parallel to the longitudinal centerline axis of the burner. A flow angle "having a non-zero radial outward component" refers to flow at least partially in a radial outward direction relative to the longitudinal centerline axis of the burner, including substantially radial outward flow away from the longitudinal centerline axis of the burner. Flow "having a non-zero radial outward component" is represented as a positive angle relative to the longitudinal centerline axis of the burner. A flow angle "having a non-zero radial inward component" refers to flow at least partially in a radial inward direction relative to the longitudinal centerline axis of the burner, including substantially radial inward flow toward the longitudinal centerline axis of the burner. Flow "having a non-zero radial inward component" is represented as a negative angle relative to the longitudinal centerline axis of the burner.

[0024] A known combustor includes a fuel nozzle mixer assembly having a pilot swirler including a venturi. The pilot swirler injects a fuel and air mixture into the venturi and then into a combustion chamber where the fuel and air mixture burns. A heat shield is typically provided at the outlet end of the venturi to protect the fuel nozzle mixer assembly. Conventional heat shields include a heat shield flange aligned substantially perpendicular to the centerline of the fuel nozzle, and the outer edge of the heat shield flange is square-pointed. When the fuel and air mixture exiting the venturi burns, the flow path outside the venturi forms a hot zone at the rear surface of the heat shield. Cooling air for cooling the heat shield is conveyed through the fuel nozzle mixer assembly and discharged through a passage therein.

[0025] The present disclosure addresses the above-mentioned problems by providing a heat shield and a fuel nozzle centerbody having a rearward geometry that further directs cooling air in a more axial direction, thereby reducing the hot zone gas temperature or biasing the hot zone toward the rear. According to the present disclosure, the heat shield flange may include a forward-facing rim or include angled heat shield bypass holes. Additionally or alternatively, the fuel nozzle centerbody may include one or more of an additional centerbody rim bypass hole, a concave rearward face, and a rim rearward face having a bullnose shape. By biasing the hot zone further rearward within the combustor, the heat shield is exposed to less heat, thereby providing better durability over time than conventional heat shields by reducing the likelihood of material degradation due to close exposure to heat from the hot zone.

[0026] like Figure 1As used in the following description, the terms "axial" and "axially" refer to directions and orientations extending generally parallel to the longitudinal centerline axis of the turbine engine. Furthermore, the terms "radial" and "radially" refer to directions and orientations extending generally perpendicular to the longitudinal centerline axis of the turbine engine. Furthermore, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations extending in an arc about the longitudinal centerline axis of the turbine engine.

[0027] Referring now to the accompanying drawings, Figure 1 is a schematic cross-sectional view of a turbine engine 10 taken along a longitudinal centerline axis 12 of the turbine engine 10 according to an embodiment of the present disclosure. Figure 1 As shown, the turbine engine 10 defines an axial direction A (extending parallel to a longitudinal centerline axis 12 for reference) and a radial direction R perpendicular to the axial direction A. Generally, the turbine engine 10 includes a fan section 14 and a turbocharger 16 disposed downstream of the fan section 14 .

[0028] The turbocharger engine 16 includes, in series flow relationship, a compressor section 21, a combustor 26, and a turbine section 27. The turbocharger engine 16 is substantially enclosed within a casing 18, which is substantially tubular and defines an annular inlet 20. Figure 1 As shown schematically, compressor section 21 includes a supercharger or low-pressure (LP) compressor 22, followed downstream by a high-pressure (HP) compressor 24. Combustor 26 is downstream of compressor section 21. Turbine section 27 is downstream of combustor 26 and includes a high-pressure (HP) turbine 28, followed downstream by a low-pressure (LP) turbine 30. Turbocharged engine 16 also includes an exhaust nozzle section 32, a high-pressure (HP) shaft 34 or spool, and a low-pressure (LP) shaft 36, downstream of turbine section 27. HP shaft 34 drivingly connects HP turbine 28 to HP compressor 24. HP turbine 28 and HP compressor 24 rotate in unison via HP shaft 34. LP shaft 36 drivingly connects LP turbine 30 to LP compressor 22. LP turbine 30 and LP compressor 22 rotate in unison via LP shaft 36. Together, compressor section 21, combustor 26, turbine section 27, and exhaust nozzle section 32 define a core air flow path.

[0029] for Figure 1 In the embodiment depicted in FIG, fan section 14 includes a fan 38 (eg, a variable pitch fan) having a plurality of fan blades 40 coupled to a disk 42 in a spaced-apart manner. Figure 1As shown, the fan blades 40 extend outwardly from the disk 42 generally in a radial direction R. In the case of a variable pitch fan, a plurality of fan blades 40 are rotatable about a pitch axis P relative to the disk 42 by means of the fan blades 40 being operably coupled to an actuating member 44, the actuating member 44 being configured to collectively and uniformly vary the pitch of the fan blades 40. The fan blades 40, disk 42, and actuating member 44 are rotatable together about the longitudinal centerline axis 12 via a fan shaft 45, which is powered by the LP shaft 36 across a power gearbox (also referred to as a gearbox assembly 46). In this manner, the fan 38 is drivingly coupled to and powered by the turbocharger engine 16, and the turbine engine 10 is an indirectly driven engine. The gearbox assembly 46 is Figure 1 The gearbox assembly 46 is a speed reduction gearbox assembly for adjusting the rotational speed of the fan shaft 45 when power is transmitted from the LP shaft 36 to the fan shaft 45 , and thus adjusting the rotational speed of the fan 38 relative to the LP shaft 36 .

[0030] Still refer to Figure 1 In the exemplary embodiment of the present invention, disk 42 is covered by a fan hub 48 that is aerodynamically shaped to facilitate airflow through the plurality of fan blades 40. Furthermore, fan section 14 includes an annular fan casing or nacelle 50 that circumferentially surrounds fan 38 and at least a portion of turbocharger engine 16. Nacelle 50 is supported relative to turbocharger engine 16 by a plurality of outlet guide vanes 52 that are circumferentially spaced about nacelle 50 and turbocharger engine 16. Furthermore, a downstream section 54 of nacelle 50 extends over an outer portion of turbocharger engine 16 and, together with outer casing 18, defines a bypass airflow passage 56 therebetween.

[0031] During operation of turbine engine 10, a quantity of air 58 enters turbine engine 10 through nacelle 50 or an inlet 60 of fan section 14. As quantity of air 58 passes through fan blades 40, a first portion of air (also referred to as bypass air 62) is directed into bypass airflow passage 56, and a second portion of air (also referred to as core air 64) is directed into an upstream section of the core air flow path through annular inlet 20 of LP compressor 22. The ratio between bypass air 62 and core air 64 is generally referred to as the bypass ratio. The pressure of core air 64 is then increased, generating compressed air 65. Compressed air 65 is directed through HP compressor 24 and into combustor 26, where it is mixed with fuel and ignited to generate combustion gases 66.

[0032] The combustion gases 66 are directed into the HP turbine 28 and expanded therethrough, where a portion of the thermal or kinetic energy from the combustion gases 66 is extracted via one or more stages of HP turbine rotor blades 70 and HP turbine stator vanes 68 coupled to the HP shaft 34. This causes the HP shaft 34 to rotate, thereby supporting the operation of the HP compressor 24 (a self-sustaining cycle). In this manner, the combustion gases 66 perform work on the HP turbine 28. The combustion gases 66 are then directed into the LP turbine 30 and expanded therethrough. Here, a second portion of the thermal or kinetic energy is extracted from the combustion gases 66 via one or more stages of LP turbine rotor blades 74 and LP turbine stator vanes 72 coupled to the LP shaft 36. This causes the LP shaft 36 to rotate, thereby supporting the operation of the LP compressor 22 (a self-sustaining cycle) and the rotation of the fan 38 via the gearbox assembly 46. In this manner, the combustion gases 66 perform work on the LP turbine 30.

[0033] The combustion gases 66 are then directed through the jet exhaust nozzle section 32 of the turbocharger engine 16 to provide propulsive thrust. Simultaneously, the bypass air 62 is directed through the bypass flow passage 56 before being discharged from the fan nozzle exhaust section 76 of the turbine engine 10, also providing propulsive thrust. The HP turbine 28, the LP turbine 30, and the jet exhaust nozzle section 32 at least partially define a hot gas path 78 for directing the combustion gases 66 through the turbocharger engine 16.

[0034] The turbine engine 10 includes a fuel system that provides fuel to the combustor 26. The fuel is mixed with compressed air 65 from the HP compressor 24 and ignited in the combustor 26 to produce combustion gases 66. The fuel system may include a fuel tank or fuel supply for storing the fuel therein, a fuel supply line, and a fuel injector. The fuel is provided from the fuel tank along the fuel supply line to the fuel injector, which introduces the fuel into the combustor 26. The fuel system may include one or more flow control devices or valves along the fuel supply line for controlling the amount of fuel provided to the combustor 26. The fuel injector may be disposed at the front end of the combustor 26. Thus, the fuel provided along the fuel supply line is provided at the front end of the combustor 26.

[0035] Figure 1The turbine engine 10 depicted in FIG is for example only. In other exemplary embodiments, the turbine engine 10 may have any other suitable configuration. For example, in other exemplary embodiments, the fan 38 may be configured in any other suitable manner (e.g., as a fixed pitch fan) and may also be supported using any other suitable fan frame configuration. The turbine engine 10 may also be a direct drive engine without a power gearbox. For a direct drive engine, the fan speed is the same as the LP shaft speed. In addition, in other exemplary embodiments, any other suitable number or configuration of compressors, turbines, shafts, or combinations thereof may be provided. In still other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable turbine engine, such as a turbofan engine, a propfan engine, a turbojet engine, a turboprop engine, and / or a turboshaft engine.

[0036] exist Figures 2 to 6B In the following description, the terms "axial" and "axially" refer to directions and orientations extending substantially parallel to the longitudinal centerline axis of the combustor. Furthermore, the terms "radial" and "radially" refer to directions and orientations extending substantially perpendicular to the longitudinal centerline axis of the combustor. Furthermore, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations extending in an arc about the longitudinal centerline axis of the combustor.

[0037] Figure 2 Yes Figure 1 A cross-sectional side view of an exemplary combustor 26 of a turbocharged engine 16 is shown. Figure 2 An example of a twin annular premixing swirler (TAPS) type combustor is depicted, and is generally an annular combustor extending circumferentially about a longitudinal centerline axis 12. The combustor 26 includes a shroud 80 comprised of an inner shroud 82 and an outer shroud 84, and a combustor liner 86 having an inner liner 88 and an outer liner 90. Each of the inner liner 88 and the outer liner 90 is an annular liner extending circumferentially about the longitudinal centerline axis 12. In this regard, an annular opening 92 formed between the inner shroud 82 and the outer shroud 84 enables compressed air 65a to enter the combustor 26 through a diffusion opening in a generally axial direction as defined by the combustor longitudinal centerline axis 94. The compressed air 65a may enter a first cavity 96 defined at least in part by an annular dome assembly 98. As will be discussed in more detail below, a portion of the compressed air 65 in the first cavity 96 may be used for combustion, while another portion may be used to cool the combustor 26.

[0038] The dome assembly 98 extends between the inner liner 88 and the outer liner 90. The inner liner 88, the outer liner 90, and the dome assembly 98 together define a combustion chamber 100. More specifically, the combustor 26 includes an inner annular dome 102 attached to the forward end of the inner liner 88 and an outer annular dome 104 attached to the forward end of the outer liner 90. In the combustion chamber 100, an initial chemical reaction of an ignited pilot fuel-oxidant mixture 108 injected into the combustion chamber 100 by a pilot swirler portion (described below) of a fuel nozzle mixer assembly 106 connected to the dome assembly 98 may occur to generate the combustion gases 66. In higher power operation of the combustor 26, a main fuel-oxidant mixture 110 is also passed through the fuel nozzle mixer assembly 106 ( Figure 3 The primary swirler portion (shown in FIG. 1 ) is injected into the combustor 100 to generate combustion gases 66. The combustion gases 66 then flow further downstream through the first stage turbine nozzle 124 at the downstream end 116 of the combustor 100 into the HP turbine 28 and the LP turbine 30 ( Figure 1 ).

[0039] The combustor 26 also includes a plurality of fuel nozzle mixer assemblies 106 spaced circumferentially between the inner annular dome 102 and the outer annular dome 104. The fuel nozzle mixer assemblies 106 and the downstream end 116 of the combustion chamber 100 generally define the combustor longitudinal centerline axis 94. A plurality of contoured cups 118 circumferentially spaced about the longitudinal centerline axis 12 may be formed in the annular dome assembly 98, and each cup 118 defines an opening in which a swirler, cyclone separator, or fuel nozzle mixer assembly 106 is mounted, attached, or otherwise integrated for introducing an air / fuel mixture into the combustion chamber 100. Notably, compressed air may be introduced or directed from the combustor 26 through one or more of the fuel nozzle mixer assemblies 106 to support combustion in the upstream end of the combustion chamber 100.

[0040] Liquid and / or gaseous fuel is delivered to the combustor 26 via a fuel distribution system (not shown) and introduced at the front end of the combustion chamber 100. In the exemplary embodiment, each fuel nozzle mixer assembly 106 may define an opening for receiving a fuel injector 120 (details omitted for clarity). The fuel injector 120 may inject fuel in an axial direction (i.e., along the combustor longitudinal centerline axis 94) and in a generally radial direction (orthogonal to the combustor longitudinal centerline axis 94), where the fuel may be swirled with the incoming compressed air. Thus, each fuel nozzle mixer assembly 106 receives compressed air from the annular opening 92 and fuel from a corresponding fuel injector 120. The fuel and compressed air swirl and mix together through the fuel nozzle mixer assembly 106, and the resulting fuel and air mixture is discharged into the combustion chamber 100 for combustion thereof.

[0041] The combustor 26 may also include an igniter 122 extending through the outer liner 90 and suitable for igniting the fuel-air mixture. Upon ignition, the resulting combustion gases 66 may flow through the combustion chamber 100 in a generally axial direction (along the combustor longitudinal centerline axis 94) into and through the turbine section of the engine 10, where a portion of the thermal and / or kinetic energy from the combustion gases 66 is extracted via sequential stages of turbine stator vanes and turbine rotor blades. More specifically, the combustion gases 66 may flow into an annular first-stage turbine nozzle 124. As is generally understood, the first-stage turbine nozzle 124 may be defined by an annular flow channel including a plurality of radially extending, circularly spaced nozzle vanes (not shown) that rotate the gases so that they flow at an angle and impinge on the HP turbine 28 ( Figure 1 ) of the first stage turbine blades (not shown).

[0042] Each dome assembly 98 has a heat shield, such as a deflector assembly 128, that thermally isolates the annular dome assembly 98 from the extremely high temperatures generated in the combustion chamber 100 during engine operation. The inner annular dome 102, the outer annular dome 104, and the deflector assembly 128 can define a plurality of openings (e.g., cups 118) for receiving the fuel nozzle mixer assembly 106. As shown, in one embodiment, the plurality of openings are circular. However, in other embodiments, the openings can be oval, elliptical, polygonal, rectangular, or other non-circular cross-sections.

[0043] The combustor 26 also includes an outer shell 130 extending circumferentially about the longitudinal centerline axis 12 and an inner shell 132 also extending circumferentially about the longitudinal centerline axis 12. An outer flow passage 134 is defined between the outer shell 130 and the outer liner 90, while an inner flow passage 136 is defined between the inner shell 132 and the inner liner 88. The outer shell 130 and the inner shell 132 converge at an upstream end 138 of the combustor 26 and together define a plenum 140. The outer shell 130 and the inner shell 132 are also connected to a diffuser 114. The diffuser 114 is in flow communication with the HP compressor 24 to receive a flow of compressed air 65 from the HP compressor 24 and provide the flow of compressed air 65 to the plenum 140. An igniter 122 may be connected to the outer shell 130 and extend through the outer flow passage 134 and the outer liner 90. The igniter 122 provides an ignition source (e.g., a spark) to ignite the pilot fuel-oxidizer mixture 108. The main fuel-oxidizer mixture 110 may be ignited via the ignited pilot fuel-oxidizer mixture 108 , or the igniter 122 may also be used to ignite the main fuel-oxidizer mixture 110 .

[0044] Return Reference Figure 1In operation, a certain amount of inlet air 58 enters the nacelle 50 at the nacelle inlet 60, and the inlet air 58 is forced by the fan 38 and passes therethrough. A portion of the inlet air 58 forced by the fan 38 flows into the LP compressor 22 as core air 64. The core air 64 is compressed by the LP compressor 22 to generate compressed air 65. The compressed air 65 then flows to the HP compressor 24, where the compressed air 65 is further compressed, thereby increasing the pressure of the compressed air 65. The compressed air 65 from the HP compressor 24 is passed through the diffuser 114 ( Figure 2 ) enters the combustor 26. Another portion of the inlet air 58 forced by the fan 38 flows through the bypass airflow passage 56, thereby providing a flow of bypass air 62. The bypass air 62 provides the majority of the thrust for the turbine engine 10.

[0045] Return Reference Figure 2 As discussed above, the compressed air 65 flows through the diffuser 114, which reduces the velocity of the compressed air 65 entering the plenum 140. A portion of the compressed air 65 in the plenum 140 enters the shroud 80 (schematically shown as air 65a), while another portion of the compressed air 65 is directed to the outer flow passage 134 and the inner flow passage 136 (schematically shown as compressed air stream 65b). The air 65a passes through the fuel nozzle mixer assembly 106 and mixes with the fuel to produce the pilot fuel-oxidant mixture 108 and the main fuel-oxidant mixture 110, which are then ignited in the primary combustion zone 142 or the secondary combustion zone 144 to produce the combustion gases 66. The compressed air flow 65b in the outer flow channel 134 and the inner flow channel 136 may be used for various purposes, such as providing dilution air (not shown) to the combustion chamber 100 through dilution openings (not shown) in the liner 88 and the outer liner 90, for cooling the liner 88 and the outer liner 90, or for cooling other components of the turbine engine 10.

[0046] Figure 3 is an enlarged partial cross-sectional view of a fuel nozzle mixer assembly 106 according to the present disclosure. The fuel nozzle mixer assembly 106 includes a pilot mixer 146, a main mixer 148, and a fuel manifold 150 positioned therebetween. The pilot mixer 146 includes an annular venturi 152 extending circumferentially about the combustor longitudinal centerline axis 94 and a pilot fuel injector 154 mounted within the venturi 152. Furthermore, the pilot mixer 146 includes a first pilot swirler 172 comprising a plurality of swirl vanes disposed radially outward from the pilot fuel injector 154. The first pilot swirler 172 is oriented generally parallel to the combustor longitudinal centerline axis 94 and includes a plurality of vanes for swirl air passing therethrough. During the engine operating cycle, fuel and air are generally always provided to the pilot mixer 146.

[0047] The pilot fuel injector 154 can perform pre-filming and atomization of the fuel almost entirely by injecting air toward the fuel. The fuel is supplied from a fuel pipe 162 in fluid communication with a fuel source (not shown) to a conduit 164 connected to the pilot fuel injector 154. The fuel is injected from the pilot fuel injector 154 into the venturi 152. The pilot fuel-oxidizer mixture 108 ( Figure 2 The pilot fuel-oxidant mixture 108 is then injected into the combustion chamber 100 where it is ignited and combusted to generate the combustion gases 66 .

[0048] The main mixer 148 is attached to a centerbody housing 180 surrounding the pilot mixer 146. The main mixer 148 includes an annular main housing 182 radially surrounding the centerbody housing 180, wherein the main housing 182 defines an annular cavity 184 and a primary swirler 186. The primary swirler 186 includes a first swirler 188 oriented substantially radially relative to the combustor longitudinal centerline axis 94 and comprising a plurality of vanes (generally shown) for swirling the compressed air 65a flowing therethrough. The vanes are substantially uniformly spaced circumferentially and define a plurality of substantially uniform passages between adjacent vanes. The main swirler 186 also includes a second swirler 192 oriented substantially parallel to the combustor longitudinal centerline axis 94. The second swirler 192 also includes a plurality of vanes (generally shown) for swirling the compressed air 65a flowing therethrough. The vanes of the second swirler 192 are substantially uniformly spaced circumferentially, defining a plurality of substantially uniform passages therebetween.

[0049] As described above, the fuel manifold 150 is located between the pilot mixer 146 and the main mixer 148 and is in flow communication with a fuel supply (not shown). A plurality of main fuel injectors 196 are provided at the fuel manifold 150, and the center body housing 180 includes a plurality of main fuel injector orifices 198 therethrough. The main fuel injectors 196 are arranged to inject fuel through the main fuel injector orifices 198 and into the annular cavity 184 of the main mixer 148. Figure 3As shown, the main fuel injector 196 is preferably positioned so that fuel is provided into the annular cavity 184 downstream of the first swirler 188 and downstream of the second swirler 192. By mixing the compressed air 65a that passes through the first swirler 188 and the second swirler 192 with the fuel injected into the annular cavity 184 by the main fuel injector 196, a main fuel-oxidant mixture 110 is generated within the annular cavity 184. The main fuel-oxidant mixture 110 then flows into the combustion chamber 100, where it is ignited and combusted to generate combustion gases 66.

[0050] Still refer to Figure 3 The center body housing 180 includes a back plate 202 at the downstream end 123 of the center body housing 180. A heat shield 204 is integrally formed with the venturi 152 downstream of the back plate 202. The heat shield 204 thermally protects adjacent components of the fuel nozzle mixer assembly 106, such as the center body housing 180 and the fuel manifold 150, from heat generated in the combustor 100 and may be constructed of a ceramic matrix composite (CMC) or similar thermally insulating material.

[0051] The venturi 152, the centerbody housing 180, and the back plate 202 define a generally annular cooling air flow cavity 208. The air 65a flows through the cooling air flow cavity 208 and exits the cooling air flow cavity 208 through one or more cooling air outlet holes 210 in the back plate 202. The cooling air outlet holes 210 allow the air 65a to exit the cooling air flow cavity 208, thereby maintaining a continuous flow of the air 65a through the cooling air flow cavity 208. The air 65a exits the cooling air flow cavity 208 through the cooling air outlet holes 210 and first enters a cooling air flow gap 212, which is arranged circumferentially about the combustor longitudinal centerline axis 94 and axially between the back plate 202 and the heat shield 204. The air 65a flows through and exits the cooling air flow gap 212 in a generally radially outward direction, whereupon the air 65a merges with the flow of the main fuel-oxidant mixture 110. After exiting the cooling air flow gap 212, the main fuel-oxidant mixture 110 flowing in a generally axial downstream direction introduces downstream components into the flow direction of the air 65a.

[0052] Figure 4A The rear portion of the fuel nozzle mixer assembly 400 is shown. The fuel nozzle mixer assembly 400 includes a venturi body 402 and a center body housing 404. Upon exiting the fuel nozzle mixer assembly 400, the mixed fuel and air are combusted in the combustor 100. The extremely high temperatures in the combustor 100 require the inclusion of a heat shield 406 to protect the various components of the fuel nozzle mixer assembly 400 and the fuel contained therein from the heat generated in the combustor 100.

[0053] The venturi body 402 includes a venturi tube 408 to provide the pilot fuel-oxidant mixture 108 for pilot combustion, as described with respect to FIG. Figure 3 The heat shield 406 for thermally protecting the fuel nozzle mixer assembly is formed as one piece with the venturi body 402 and is provided at the rear end of the venturi body 402. The heat shield outer surface 410 is rounded and forms a "bull nose" shape when viewed in cross section, as shown in FIG. Figure 4A The heat shield 406 has a forward face 412 that is arranged generally normal to the combustor longitudinal centerline axis 94 .

[0054] The center body housing 404 partially defines a cooling air flow cavity 414 and an array of circular cooling air outlet holes 416 that allow air 65a to flow therethrough. The cooling air outlet holes 416 are arranged in a circular pattern relative to the combustor longitudinal centerline axis 94 and allow the air 65a to flow out of the cooling air flow cavity 414 in a generally axially aft direction. The size and number of the cooling air outlet holes 416 can be designed to achieve a desired volume and shape of the flow of air 65a from the fuel nozzle mixer assembly 400 into the combustion chamber 100. The center body housing 404 also includes a center body rim 418 that protrudes from the center body housing 404 in the axially aft direction and is circumferentially arranged about the combustor longitudinal centerline axis 94. Figure 4A As shown, the centerbody rim 418 of the centerbody housing 404 has a generally planar centerbody rim aft face 420 oriented generally normal to the combustor longitudinal centerline axis 94 .

[0055] A cooling air flow gap 422 is defined between the heat shield 406 and the center body casing 404. A center body aft-facing face 424 is generally normal to the combustor longitudinal centerline axis 94 and is substantially parallel to the forward-facing face 412 of the heat shield 406. Upon exiting through the cooling air exit apertures 416, the air 65a flows in a radially outward direction between the center body aft-facing face 424 and the forward-facing face 412 at the upstream end of the cooling air flow gap 422.

[0056] At the downstream end of cooling air flow gap 422, cooling air flow gap 422 is defined by centerbody rim inner surface 426, heat shield outer surface 410, centerbody aft face 424, and forward face 412. Centerbody rim aft face 420 is offset axially downstream of forward face 412. The shape, position, and orientation of centerbody rim aft face 420, forward face 412, centerbody rim inner surface 426, and heat shield outer surface 410 collectively define the downstream end of cooling air flow gap 422. Because centerbody rim inner surface 426 is radially outboard of heat shield outer surface 410, and because centerbody rim aft face 420 is rearward of forward face 412, air 65a flowing through the downstream end of cooling air flow gap 422 turns in an aft direction and flows at least partially in an axial aft direction.

[0057] Air 65a exits cooling air flow gap 422 at a gap cooling air outlet angle 428. Cooling air outlet angle 428 may have a non-zero axial rearward component. Additionally, gap cooling air outlet angle 428 may have a non-zero radially inward component or a non-zero radially outward component. Gap cooling air outlet angle 428 is typically between -45 and 45 degrees. Gap cooling air outlet angle 428 may preferably be between -10 and 45 degrees. Gap cooling air outlet angle 428 depends largely (though not entirely) on the configuration of centerbody rim inner surface 426. That is, when centerbody rim inner surface 426 approaches a cylindrical shape, gap cooling air outlet angle 428 will approach zero, i.e., extend in the axial rearward direction. Gap cooling air outlet angle 428 can be further reduced (extended further aft) by increasing the distance that centerbody rim rearward face 420 is offset rearward relative to forward face 412. Conversely, the gap cooling air outlet angle 428 may be increased (extended in a more radial direction) by decreasing the distance that the centerbody edge aft face 420 is offset aft relative to the forward face 412. Offsetting the centerbody edge aft face 420 forward relative to the forward face 412 may result in a larger gap cooling air outlet angle 428 relative to the combustor longitudinal centerline axis 94.

[0058] Figure 4B The rear portion of the fuel nozzle mixer assembly 401 is shown, and the fuel nozzle mixer assembly 401 is constructed similarly to Figure 4A The fuel nozzle mixer assembly 400 has a configuration that enables a negative clearance cooling air outlet angle 429. Figure 4A The gap cooling air outlet angle 428 is shown as having a non-zero radially outward component, but the gap cooling air outlet angle 429 may alternatively have a non-zero radially inward flow component, as shown. Figure 4B That is, the flow pattern of the air 65a when it leaves the cooling air flow gap 422 and enters the combustion chamber 100 can expand radially outward relative to the longitudinal centerline axis 94 of the combustor (e.g., Figure 4A ), or expand radially inward (as shown Figure 4B This orientation is influenced at least in part by the geometry of the heat shield 406 and at least in part by the center body shell 404 ( Figure 4A ) shape. Gap cooling air outlet angle 428 ( Figure 4A ) and gap cooling air outlet angle 429( Figure 4B ) all have a non-zero axial rear component.

[0059] exist Figure 4B In the fuel nozzle mixer assembly 401, the center body housing 405 has a center body edge 419, which is larger than the center body edge 419. Figure 4A The centerbody rim 418 of the centerbody housing 404 of the fuel nozzle mixer assembly 400 extends further aft. In the fuel nozzle mixer assembly 401, the centerbody rim aft face 421 extends further aft, causing the cooling air flow gap 423 to be angled radially inward at a negative clearance cooling air outlet angle 429. The downstream shape of the cooling air flow gap 423 is defined by the heat shield outer surface 410 and the centerbody rim inner surface 427, resulting in a negative clearance cooling air outlet angle 429. Specifically, the edge effect of the heat shield outer surface 410 and the shape of the centerbody rim 419 can cause at least a portion of the air 65a flow to be diverted radially inward toward the combustor longitudinal centerline axis 94. In the following description of Figures 5A to 6B In the description of , the same radially inward flow component may similarly exist for any additional embodiments.

[0060] Reference again Figure 4A , combustion gas 66( Figure 1 ) is extremely hot and can damage components of the fuel nozzle mixer assembly 400. By having an axial component in the direction of the air 65 a exiting the cooling air flow gap 422, the air 65 a not only cools the heat shield 406 at the forward face 412 of the heat shield 406 in the cooling air flow gap 422 by directly transferring heat to the air 65 a, but also diverts the hot combustion gases 66 downstream in the combustor 100, increasing the distance between the actual combustion and the fuel nozzle mixer assembly 400, and reducing the temperature at the heat shield 406.

[0061] Now refer to Figure 5A The fuel nozzle mixer assembly 500 incorporates the Figure 4A and Figure 4B The venturi body 402 described above, but with a different center body housing 504. Figure 4A The center body housing 404 and Figure 4BCompared to the centerbody housing 405, the centerbody housing 504 also has a cooling air flow cavity 514 that defines a path for air 65a. Air 65a exits the cooling air flow cavity 514 at its downstream end through cooling air outlet openings 516 arranged circularly about the combustor longitudinal centerline axis 94 and enters a cooling air flow gap 522. At the upstream end of the cooling air flow gap 522, the forward face 412 and the centerbody aft face 524 of the centerbody housing 504 are generally planar and perpendicular to the combustor longitudinal centerline axis 94. The forward face 412 is positioned rearward of the centerbody aft face 524, thereby defining the cooling air flow gap 522. A centerbody rim 518, arranged circumferentially about the combustor longitudinal centerline axis 94, extends from the aft end of the centerbody housing 504. In this configuration, the centerbody rim aft face 520 of the centerbody rim 518 is circular, having a bullnose cross-sectional shape.

[0062] The center body housing 504 includes additional features that further direct the air 65a in an axial direction, thereby transferring the combustion gases 66 and the generated heat aft, away from the heat shield 406. The center body rim inner surface 526 of the center body rim 518 at the exit of the cooling air flow gap 522 is cylindrical relative to the combustor longitudinal centerline axis 94. In this manner, the air 65a exits the cooling air flow gap 522 at a gap cooling air exit angle 528 having a non-zero axial aft component. Figure 5A In the configuration of the fuel nozzle mixer assembly 500 shown in FIG. 5 , the gap cooling air exit angle is substantially parallel to the combustor longitudinal centerline axis upon exiting the cooling air flow gap 522 .

[0063] Now refer to Figure 5B The fuel nozzle mixer assembly 501 is similar in construction to that described with respect to Figure 5AThe fuel nozzle mixer assembly 500 is described above. However, in the configuration of the centerbody housing 505 of the fuel nozzle mixer assembly 501, the air 65a also exits the cooling air flow cavity 514 by flowing through a circumferential array of centerbody cooling air outlet holes 530. The centerbody cooling air outlet holes 530 extend from the cooling air flow cavity 514 through the centerbody rim 518 in an aft and radially outward direction, allowing the air 65a to flow directly into the combustion chamber 100, bypassing the cooling air flow gap 522, and exiting at a centerbody cooling air outlet angle 532 having a non-zero axial aft component and a non-zero radially outward component. The air 65 a exiting the cooling air flow cavity 514 via the cooling air flow gap 522 at the gap cooling air outlet angle 528 and the air 65 a exiting the cooling air flow gap 522 via the centerbody cooling air outlet hole 530 at the centerbody cooling air outlet angle 532 may be unequal, resulting in divergence of the air 65 a exiting the fuel nozzle mixer assembly 501, diverting the combustion of air and fuel aft within the combustor 100, thereby reducing heat exposure of the combustion process to the heat shield 406.

[0064] A centerbody cooling air outlet angle 532 may be established by arranging the centerbody cooling air outlet holes 530 so that the resultant combination of air 65 a exiting the fuel nozzle mixer assembly 501 from the cooling air flow gap 522 and exiting the centerbody cooling air outlet holes 530 has a desired size and shape to properly divert the combustion process behind the heat shield 406. Similarly, the number of cooling air outlet holes 516 and the centerbody cooling air outlet holes 530 may be set, and their relative diameters may be sized, to achieve a desired flow ratio of the air 65 a through each cooling air outlet hole 516 and the centerbody cooling air outlet hole 530, and thus achieve a desired combined volume, distribution, and direction of the air 65 a exiting the fuel nozzle mixer assembly 501.

[0065] Figure 6A An additional embodiment of a fuel nozzle mixer assembly 600 is shown consisting of a venturi body 602 and a center body housing 604. Figures 4A to 5B Similar to the illustrated embodiment, the venturi body 602 includes a heat shield 606 for protecting the fuel nozzle from the heat of the combustion process within the combustor 100. The venturi body 602 also includes a venturi tube 608 for mixing the pilot fuel-oxidizer mixture 108 for combustion in the combustor 100, and the centerbody housing 604 at least partially defines a cooling air flow cavity 614 through which air 65a flows and at least partially exits through cooling air outlet holes 616 arranged in a circular pattern relative to the combustor longitudinal centerline axis 94 to divert the combustion process away from the heat shield 606.

[0066] exist Figure 6AIn the embodiment of the present invention, a plurality of features are shown, which can be respectively represented by Figure 4A 、 Figure 4B 、 Figure 5A and Figure 5B 6. An improvement to the fuel nozzle mixer assemblies 400, 401, 500, and 501 shown in . In the fuel nozzle mixer assembly 600, a cooling air flow gap 622 is defined at the upstream end between the centerbody aft face 624 and the heat shield forward face 612 such that air 65a initially flows in a radially outward direction in the cooling air flow gap 622. Moving in the downstream flow direction, the cooling air flow gap 622 is then defined by a concave centerbody aft face 626 in the centerbody housing 604 and a heat shield rim 636 on the forward end of the heat shield 606. The heat shield rim 636 is generally circumferentially disposed relative to the combustor longitudinal centerline axis 94 and projects forwardly from the heat shield 606 and has a heat shield outer surface 610. The heat shield outer surface 610 may be generally cylindrical, such as Figure 6A As shown, or can have any other shape as desired, thereby producing a preferred gap cooling air outlet angle 628. The gap cooling air outlet angle 628 has a non-zero axial rear component. Figure 6A As shown, the gap cooling air exit angle is oriented substantially axially aft. Heat shield rim inner surface 638 may be a cylindrical heat shield rim inner surface 638 as shown, or may have another shape suitable for the application, to direct the flow of air 65a generally forward after flowing generally radially outward in the region of centerbody aft face 624 and heat shield forward face 612. A heat shield circular forward edge surface 640 is present at the forward end of heat shield rim 636. When viewed in cross section, the arc of forward heat shield circular forward edge surface 640 is substantially concentric with the arc of concave centerbody aft face 626, thereby directing air 65a radially outward before exiting cooling air flow gap 622 in the axial aft direction, wherein gap cooling air exit angle 628 is zero or near zero.

[0067] If you can Figure 6A , the heat shield rim 636 projects forwardly beyond the centerbody rim aft face 620 of the centerbody housing 604, which together provide a curved shape for the downstream portion 634 of the cooling air flow gap 622 and, in turn, a zero or near zero gap cooling air exit angle 628. The forwardly projecting heat shield rim 636 beyond the centerbody rim aft face 620 allows for greater flexibility than would be possible with an otherwise equivalent fuel nozzle mixer assembly, such as a conventional fuel nozzle mixer assembly, without the forwardly projecting heat shield rim 636 and corresponding concave centerbody aft face 626. Figures 4A to 5B ) having a zero or near-zero clearance cooling air outlet angle 628 at a shorter axial distance.

[0068] An additional feature of the configuration of the fuel nozzle mixer assembly 600 is a circumferential array of centerbody cooling air outlet holes 630 extending rearwardly and radially outwardly between the cooling air flow cavity 614 and the circular edge of the centerbody housing 604 defined by the centerbody rim aft face 620 and the centerbody outer diameter surface 642. Figure 5A and Figure 5B As discussed above, centerbody cooling air outlet holes 530, centerbody cooling air outlet holes 630 are arranged in a circular pattern relative to the combustor longitudinal centerline axis 94 and allow for additional flow paths for the air 65a passing through the cooling air flow cavity 614. A centerbody cooling air outlet angle 632 can be established by arranging the centerbody cooling air outlet holes 630 so that the resulting combined flow of air 65a exiting the fuel nozzle mixer assembly 600 from the cooling air flow gap 622 and the centerbody cooling air outlet holes 630 has a desired size and shape to properly divert the combustion process behind the heat shield 606. Additionally, the relative diameters of the cooling air outlet holes 616 and the centerbody cooling air outlet holes 630 can be sized or numbered to achieve a desired flow ratio of the air 65a through each cooling air outlet hole 616 and the centerbody cooling air outlet hole 630, and thus achieve a desired distribution and direction of the flow of the air 65a exiting the fuel nozzle mixer assembly 600. Likewise, the centerbody cooling air outlet angle 632 may be arranged in a manner to achieve a desired shape and distribution of the air 65a flow entering the combustion chamber 100 to adequately or more advantageously divert the combustion process downstream of the heat shield 606. Figure 6A As shown, the centerbody cooling air outlet angle 632 has a non-zero axial aft component and a non-zero radial outward component. The centerbody cooling air outlet angle 632 may not be equal to the clearance cooling air outlet angle 628.

[0069] Now refer to Figure 6B The fuel nozzle mixer assembly 601 is similar in construction to that described with respect to Figure 6AThe fuel nozzle mixer assembly 600 discussed herein further includes a venturi body 603 having heat shield cooling air outlet holes 644 arranged in a circular pattern relative to the combustor's longitudinal centerline axis and extending between the cooling air flow gap 622 and the combustion chamber 100. The heat shield cooling air outlet holes 644 direct air 65a in an aft and radially outward direction, exiting at a heat shield cooling air outlet angle 646. The heat shield cooling air outlet angle 646 has a non-zero axial aft component and a non-zero radially outward component. The heat shield cooling air outlet angle 646 may not be equal to the gap cooling air outlet angle 628 and may not be equal to the centerbody cooling air outlet angle 632. Similar to the centerbody cooling air outlet holes 630, the presence of the heat shield cooling air outlet holes 644 allows a greater total volume of air 65a to flow through the fuel nozzle mixer assembly 601 via the cooling air flow cavity 614. Furthermore, similarly, the heat shield cooling air outlet holes 644 may be sized, and their centerbody cooling air outlet angles 632 may be arranged, taking into account the cooling air flow gaps 622, the centerbody cooling air outlet holes 630, or both the cooling air flow gaps 622 and the centerbody cooling air outlet holes 630 so that the resultant combined flow of air 65 a exiting the fuel nozzle mixer assembly 600 from all locations has a desired size and shape to properly divert the combustion process behind the heat shield 606.

[0070] As mentioned above, Figures 4A to 6B As shown, the embodiments of the present invention each include one or more features that can be used to introduce an additional flow of air 65a into the combustion chamber 100, at least partially in an axially aft direction relative to the combustor longitudinal centerline axis 94. Other arrangements are contemplated that include more, fewer, or different combinations of the features of the various embodiments described.

[0071] The fuel nozzle mixer assembly is provided in the combustor 26 ( Figure 2 ) and exposed to the combustion chamber 100 ( Figure 2 ) combustion occurs in the fuel nozzle mixer assembly. Thus, the fuel nozzle mixer assembly is exposed to the extreme temperatures generated by the combustion. Although heat shields can be applied to protect the fuel nozzle mixer assembly from the extreme heat, Figure 2 ) introduced into the combustion chamber 100, flowing at least partially in an aft direction, can be used to shift combustion aft and away from the heat shield, thereby reducing the risk of thermal damage and extending the service life of the heat shield. Additional cooling air outlet holes from the fuel nozzle heat shield assembly to the combustion chamber 100 increase the volume of air 65a flow and can allow for design flexibility.

[0072] Further aspects are provided by the subject matter of the following clauses.

[0073] 19. The combustor of a turbine engine, comprising: a combustion chamber for burning fuel and air, wherein the combustion of the fuel and the air generates heat; a fuel nozzle mixer assembly, wherein the fuel nozzle mixer assembly is arranged at a front end of the combustor, and is used to receive and mix the fuel and the air, and inject the fuel and the air into the combustion chamber for combustion, wherein the fuel nozzle mixer assembly and the combustion chamber generally define a longitudinal centerline axis of the combustor, and the fuel nozzle mixer assembly comprises: a heat shield, wherein the heat shield is arranged at a rear end of the fuel nozzle mixer assembly, and is used to shield the fuel nozzle mixer assembly from the influence of the heat; and a center body casing, wherein the center body casing A core body shell partially defines a cooling air flow cavity for distributing a cooling air flow through the fuel nozzle mixer assembly, the center body shell and the heat shield defining a cooling air flow gap therebetween, and a circular array of cooling air outlet holes between the cooling air flow cavity and the cooling air flow gap, the cooling air flow passing from the cooling air flow cavity through the cooling air outlet holes before entering the cooling air flow gap and exiting the cooling air flow gap at a gap cooling air outlet angle relative to a longitudinal centerline axis of the combustor, the gap cooling air outlet angle having a non-zero axial aft component to divert the combustion in a downstream direction within the combustion chamber to isolate the heat from the heat shield.

[0074] The combustor of the preceding clause, wherein the gap cooling air outlet angle has a non-zero radially outward component relative to the combustor longitudinal centerline axis.

[0075] The combustor of any preceding clause, wherein the heat shield comprises a heat shield outer surface arranged substantially cylindrically relative to the combustor longitudinal centerline axis, and wherein the heat shield outer surface is rounded and has a bullnose cross-sectional shape.

[0076] The combustor of any preceding clause, wherein the heat shield comprises a heat shield outer surface arranged substantially cylindrically relative to the combustor longitudinal centerline axis and the heat shield outer surface is cylindrical relative to the combustor longitudinal centerline axis.

[0077] The combustor of any preceding clause, wherein the centerbody housing further comprises a plurality of centerbody cooling air outlet holes arranged circularly about the combustor longitudinal centerline axis from the cooling air flow cavity to the combustion chamber at a centerbody cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0078] The combustor of the preceding clause, wherein the centerbody cooling air outlet angle is not equal to the gap cooling air outlet angle.

[0079] The combustor of any preceding clause, wherein the heat shield includes heat shield cooling air outlet holes arranged circularly about the combustor longitudinal centerline axis from the cooling air flow gap to the combustion chamber at a heat shield cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0080] The combustor of the preceding clause, wherein the heat shield cooling air outlet angle is not equal to the gap cooling air outlet angle.

[0081] 19. The combustor according to claim 1, wherein the centerbody housing further comprises a centerbody aft face and a centerbody rim, the centerbody rim projecting from the centerbody housing in an axial aft direction and arranged circumferentially about the combustor longitudinal centerline axis, the centerbody rim having a centerbody rim aft face and a centerbody rim inner surface, the heat shield comprising a heat shield forward face arranged substantially orthogonal to the combustor longitudinal centerline axis and a heat shield outer surface arranged circumferentially relative to the combustor longitudinal centerline axis, and the cooling air flow gap is further defined by the centerbody aft face, the centerbody rim inner surface, the heat shield forward face, and the heat shield outer surface.

[0082] A combustor according to the preceding clause, wherein said center body rim inner surface is non-cylindrical.

[0083] A combustor according to any preceding clause, wherein the centre body rim inner surface is cylindrical.

[0084] A combustor according to any preceding clause, wherein said centre body rim rearwardly facing face is rounded to have a bullnose cross-sectional shape.

[0085] A combustor according to any preceding clause, wherein said centre body rim aft facing face is planar and arranged substantially normal to said combustor longitudinal centreline axis.

[0086] The combustor of any preceding clause, wherein the heat shield forward facing face is axially forward of the centerbody rim aft facing face.

[0087] The combustor of any preceding clause, wherein the centerbody rim inner surface is radially outward of the heat shield outer surface.

[0088] A combustor according to any preceding clause, wherein the centerbody housing further comprises a circular array of centerbody cooling air outlet holes extending from the cooling air flow cavity through the centerbody rim to the combustion chamber at a centerbody cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0089] The combustor of the preceding clause, wherein the centerbody cooling air outlet angle is not equal to the gap cooling air outlet angle.

[0090] The combustor according to any preceding clause, wherein the heat shield further comprises an axially forwardly projecting heat shield rim having a heat shield circular front rim face and a heat shield rim inner surface, the heat shield rim inner surface being arranged substantially cylindrically relative to the combustor longitudinal centerline axis.

[0091] The combustor of the preceding clause, wherein said centerbody housing further comprises a centerbody aft-facing face, and wherein said heat shield circular forward edge face is axially forward of said centerbody aft-facing face.

[0092] The combustor of the preceding clause, wherein the centerbody aft face comprises a concave centerbody aft face, and wherein the heat shield circular leading edge face and the concave centerbody aft face are generally concentric when viewed in cross-section.

[0093] 19. The turbojet engine of claim 18, wherein the combustion chamber further comprises a fan, the fan having a plurality of fans, the fan being arranged to move the fans toward the combustion chamber, the fan being arranged to move the fans toward the combustion chamber, the fan being arranged to move the fans toward the combustion chamber, the fan being arranged to move the fans toward the combustion chamber, and the fan being arranged to move the fans toward the combustion chamber. protecting the fuel nozzle mixer assembly from the effects of the heat; and a centerbody casing, the centerbody casing partially defining a cooling air flow cavity for distributing air flow through the fuel nozzle mixer assembly, the centerbody casing and the heat shield defining a cooling air flow gap therebetween, the centerbody casing including a circular array of cooling air outlet holes between the cooling air flow cavity and the cooling air flow gap, wherein the air flow passes from the cooling air flow cavity through the cooling air outlet holes before entering the cooling air flow gap and exits the cooling air flow gap at a gap cooling air outlet angle relative to a longitudinal centerline axis of the combustor, the gap cooling air outlet angle having a non-zero axial aft component to divert the combustion gases in a downstream direction within the combustion chamber to isolate the heat from the heat shield.

[0094] The turbine engine according to the preceding clause, wherein the clearance cooling air outlet angle has a non-zero radially outward component or a non-zero radially inward component relative to the combustor longitudinal centerline axis.

[0095] The turbine engine of any preceding clause, wherein the heat shield includes a heat shield outer surface arranged substantially cylindrically relative to the combustor longitudinal centerline axis, and wherein the heat shield outer surface is rounded and has a bullnose cross-sectional shape.

[0096] The turbine engine of any preceding clause, wherein the heat shield includes a heat shield outer surface that is substantially cylindrically arranged relative to the combustor longitudinal centerline axis and is cylindrical relative to the combustor longitudinal centerline axis.

[0097] A turbine engine according to any preceding clause, wherein the centerbody casing further comprises a plurality of centerbody cooling air outlet holes arranged circularly about the combustor longitudinal centerline axis from the cooling air flow cavity to the combustion chamber at a centerbody cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0098] The turbine engine according to the preceding clause, wherein said centerbody cooling air outlet angle is not equal to said gap cooling air outlet angle.

[0099] A turbine engine according to any preceding clause, wherein the heat shield includes heat shield cooling air outlet holes arranged circularly about the combustor longitudinal centerline axis from the cooling air flow gap to the combustion chamber at a heat shield cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0100] The turbine engine according to the preceding clause, wherein the heat shield cooling air outlet angle is not equal to the gap cooling air outlet angle.

[0101] 14. The turbine engine according to claim 13, wherein the centerbody housing further includes a centerbody aft face and a centerbody rim, the centerbody rim projecting from the centerbody housing in an axial aft direction and arranged circumferentially about the combustor longitudinal centerline axis, the centerbody rim having a centerbody rim aft face and a centerbody rim inner surface, the heat shield including a heat shield forward face arranged substantially orthogonal to the combustor longitudinal centerline axis and a heat shield outer surface arranged circumferentially relative to the combustor longitudinal centerline axis, and the cooling air flow gap is further defined by the centerbody aft face, the centerbody rim inner surface, the heat shield forward face, and the heat shield outer surface.

[0102] A turbine engine according to the preceding clause, wherein said center body rim inner surface is non-cylindrical.

[0103] A turbine engine according to any preceding clause, wherein the center body rim inner surface is cylindrical.

[0104] A turbine engine according to any preceding clause, wherein said center body edge is rounded along a rearward face, presenting a bullnose cross-sectional shape.

[0105] A turbine engine according to any preceding clause, wherein said centerbody rim aft-facing face is planar and arranged substantially normal to said combustor longitudinal centerline axis.

[0106] A turbine engine according to any preceding clause, wherein the heat shield forward face is axially forward of the centerbody rim aft face.

[0107] A turbine engine as claimed in any preceding clause, wherein the centrebody rim inner surface is radially outward of the heat shield outer surface.

[0108] A turbine engine according to any preceding clause, wherein the centerbody housing further includes a circular array of centerbody cooling air outlet holes extending from the cooling air flow cavity through the centerbody rim to the combustion chamber at a centerbody cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0109] The turbine engine according to the preceding clause, wherein said centerbody cooling air outlet angle is not equal to said gap cooling air outlet angle.

[0110] A turbine engine according to any preceding clause, wherein the heat shield further comprises an axially forwardly projecting heat shield rim having a heat shield circular front rim face and a heat shield rim inner surface, the heat shield rim inner surface being arranged substantially cylindrically relative to the combustor longitudinal centerline axis.

[0111] The turbine engine according to the preceding clause, wherein said centerbody casing includes a centerbody aft-facing face, and wherein said heat shield circular forward edge face is axially forward of said centerbody aft-facing face.

[0112] The turbine engine according to the preceding clause, wherein the centerbody aft surface comprises a concave centerbody aft surface, and the heat shield circular leading edge surface and the concave centerbody aft surface are generally concentric when viewed in cross-section.

[0113] A method of operating a combustor in a turbine engine, the method comprising flowing an airflow through a cooling air flow cavity defined in part by a centerbody casing, flowing the airflow from the cooling air flow cavity through a circular array of cooling air outlet holes to a cooling air flow gap defined between the centerbody casing and a heat shield, and flowing the cooling airflow through the cooling air flow gap and into a combustion chamber, wherein the cooling airflow exits the cooling air flow gap at a gap cooling air outlet angle having a non-zero axial aft component relative to a longitudinal centerline axis of the combustor.

[0114] A method as in the preceding clause, wherein the gap cooling air outlet angle has a non-zero radially outward component relative to the combustor longitudinal centerline axis.

[0115] The method of any preceding clause, wherein the heat shield comprises a heat shield outer surface arranged substantially cylindrically relative to the combustor longitudinal centerline axis, and wherein the heat shield outer surface is rounded and has a bullnose cross-sectional shape.

[0116] The method of any preceding clause, wherein the heat shield comprises a heat shield outer surface arranged substantially cylindrically relative to the combustor longitudinal centerline axis and the heat shield outer surface is cylindrical relative to the combustor longitudinal centerline axis.

[0117] A method according to any preceding clause, wherein the centerbody housing further includes a plurality of centerbody cooling air outlet holes, the plurality of centerbody cooling air outlet holes being circularly arranged about the combustor longitudinal centerline axis from the cooling air flow cavity to the combustion chamber, the method further comprising flowing a portion of the air flow through the centerbody cooling air outlet holes to the combustion chamber to exit the centerbody cooling air outlet holes at a centerbody cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0118] The method of the preceding clause, wherein the centerbody cooling air outlet angle is not equal to the gap cooling air outlet angle.

[0119] A method according to any preceding clause, wherein the heat shield includes heat shield cooling air outlet holes, the heat shield cooling air outlet holes being arranged in a circle about the combustor longitudinal centerline axis from the cooling air flow gap to the combustion chamber, the method further comprising flowing a portion of the air flow through the heat shield cooling air outlet holes to the combustion chamber, the portion of the air flow exiting the heat shield cooling air outlet holes at a heat shield cooling air outlet angle relative to the combustor longitudinal centerline axis.

[0120] The method of the preceding clause, wherein the heat shield cooling air outlet angle is not equal to the gap cooling air outlet angle.

[0121] A method according to any preceding clause, wherein the centerbody housing further includes a centerbody aft face and a centerbody rim, the centerbody rim projecting from the centerbody housing in an axial aft direction and arranged circumferentially about the combustor longitudinal centerline axis, the centerbody rim having a centerbody rim aft face and a centerbody rim inner surface, the heat shield including a heat shield forward face arranged substantially orthogonal to the combustor longitudinal centerline axis and a heat shield outer surface arranged circumferentially relative to the combustor longitudinal centerline axis, and the cooling air flow gap is further defined by the centerbody aft face, the centerbody rim inner surface, the heat shield forward face, and the heat shield outer surface.

[0122] A method as defined in the preceding clause, wherein the centerbody rim inner surface is non-cylindrical.

[0123] A method according to any preceding clause, wherein the centerbody rim inner surface is cylindrical.

[0124] A method according to any preceding clause, wherein the center body edge is rounded along a rearward face, presenting a bullnose cross-sectional shape.

[0125] A method according to any preceding clause, wherein the centerbody rim aft face is planar and arranged substantially normal to the combustor longitudinal centerline axis.

[0126] A method as in any preceding clause, wherein the heat shield forward facing face is axially forward of the centerbody rim aft facing face.

[0127] A method as in any preceding clause, wherein the centerbody rim inner surface is radially outward of the heat shield outer surface.

[0128] A method according to any preceding clause, wherein the centerbody housing further includes a circular array of centerbody cooling air outlet holes, the circular array of centerbody cooling air outlet holes extending from the cooling air flow cavity through the centerbody rim to the combustion chamber, the method further comprising flowing a portion of the air flow through the centerbody cooling air outlet holes to the combustion chamber, the portion of the air flow exiting the centerbody cooling air outlet holes at a centerbody cooling air outlet angle relative to the longitudinal centerline axis of the combustor.

[0129] The method of the preceding clause, wherein the centerbody cooling air outlet angle is not equal to the gap cooling air outlet angle.

[0130] A method according to any preceding clause, wherein the heat shield further comprises an axially forwardly projecting heat shield rim having a heat shield circular front rim face and a heat shield rim inner surface, the heat shield rim inner surface being arranged substantially cylindrically relative to the combustor longitudinal centerline axis.

[0131] The method of the preceding clause, wherein the centerbody housing further comprises a centerbody aft-facing face, and wherein the heat shield circular forward edge face is axially forward of the centerbody aft-facing face.

[0132] The method of the preceding clause, wherein the centerbody aft face comprises a concave centerbody aft face, and wherein the heat shield circular leading edge face and the concave centerbody aft face are generally concentric when viewed in cross-section.

[0133] Although the foregoing description is directed to preferred embodiments of the present disclosure, other changes and modifications are obvious to those skilled in the art and may be made without departing from the present disclosure. In addition, features described in conjunction with one embodiment of the present disclosure may be used in conjunction with other embodiments, even if not explicitly stated above.

Claims

1. A combustor for a turbine engine, characterized in that: The burner comprises: a combustion chamber for burning fuel and air, the combustion of the fuel and air generating combustion gas and heat; and a fuel nozzle mixer assembly disposed at a front end of the combustor for receiving and mixing the fuel and the air and injecting the fuel and the air into the combustion chamber for combustion, the fuel nozzle mixer assembly and the combustion chamber generally defining a longitudinal centerline axis of the combustor, the fuel nozzle mixer assembly comprising: a heat shield disposed at a rear end of the fuel nozzle mixer assembly for thermally protecting the fuel nozzle mixer assembly from the heat; and a centerbody housing partially defining a cooling air flow cavity for distributing air flow through the fuel nozzle mixer assembly, the centerbody housing and the heat shield defining a cooling air flow gap therebetween, the centerbody housing including a circular array of cooling air outlet holes between the cooling air flow cavity and the cooling air flow gap, wherein the air flow passes from the cooling air flow cavity through cooling air outlet holes before entering the cooling air flow gap and exits the cooling air flow gap at a gap cooling air outlet angle relative to the combustor longitudinal centerline axis, the gap cooling air outlet angle having a non-zero axial aft component to divert the combustion gases in a downstream direction within the combustion chamber to isolate the heat from the heat shield.

2. The burner according to claim 1, characterized in that in, The gap cooling air outlet angle has a non-zero radially outward component or a non-zero radially inward component relative to the combustor longitudinal centerline axis.

3. The burner according to claim 1, characterized in that in, The heat shield includes a heat shield outer surface that is substantially cylindrically arranged relative to the combustor longitudinal centerline axis, and the heat shield outer surface is rounded and has a bullnose cross-sectional shape.

4. The burner according to claim 1, characterized in that in, The heat shield includes a heat shield outer surface that is substantially cylindrically arranged relative to the combustor longitudinal centerline axis, and the heat shield outer surface is cylindrical relative to the combustor longitudinal centerline axis.

5. The burner according to claim 1, characterized in that in, The centerbody housing further includes a plurality of centerbody cooling air outlet holes circularly arranged about the combustor longitudinal centerline axis from the cooling air flow cavity to the combustion chamber at a centerbody cooling air outlet angle relative to the combustor longitudinal centerline axis.

6. The burner according to claim 5, characterized in that in, The center body cooling air outlet angle is not equal to the gap cooling air outlet angle.

7. The burner according to claim 1, characterized in that in, The heat shield includes heat shield cooling air outlet holes circularly arranged about the combustor longitudinal centerline axis from the cooling air flow gap to the combustion chamber at a heat shield cooling air outlet angle relative to the combustor longitudinal centerline axis.

8. The burner according to claim 7, characterized in that in, The heat shield cooling air outlet angle is not equal to the gap cooling air outlet angle.

9. The burner according to claim 1, characterized in that in, The centerbody housing further includes a centerbody aft face and a centerbody rim, the centerbody rim protruding from the centerbody housing in an axial aft direction and arranged circumferentially around the longitudinal centerline axis of the combustor, the centerbody rim having a centerbody rim aft face and a centerbody rim inner surface, the heat shield including a heat shield forward face arranged substantially orthogonal to the longitudinal centerline axis of the combustor and a heat shield outer surface arranged circumferentially relative to the longitudinal centerline axis of the combustor, and the cooling air flow gap is further defined by the centerbody aft face, the centerbody rim inner surface, the heat shield forward face, and the heat shield outer surface.

10. The burner according to claim 9, characterized in that in, The inner surface of the center body edge is not cylindrical.

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