Pilot fuel nozzle assembly with multi-angle venturi

Abstract

A pilot fuel nozzle assembly includes a fuel nozzle, a swirler, and a vented pilot venturi. The vented pilot venturi has an annular wall with an oxidant flow channel therein and a venturi expansion surface. The venturi expansion surface includes a plurality of tapered surface segments extending circumferentially about the fuel nozzle centerline axis. The at least two tapered surface segments are mechanically joined together. One or more of the plurality of tapered surface segments have a plurality of venturi oxidant outlet ports extending through the venturi expansion surface. The plurality of venturi oxidant outlet ports are circumferentially spaced about the fuel nozzle centerline axis.

Description

Technical Field

[0001] The present disclosure relates to a venturi for a pilot fuel nozzle assembly of a combustor of a gas turbine engine. Background Art

[0002] Some burners in use are called TAPS (Twin Annular Pre-mixing Swirler) burners. A TAPS burner includes a premixer / swirler fuel nozzle assembly in which air and fuel are mixed. The TAPS premixer / swirler fuel nozzle assembly includes a pilot swirler and a main premixer. The pilot swirler includes a venturi into which the fuel and air mixture is injected through a pilot fuel nozzle and a surrounding air swirler. The fuel and air mixture leaves the venturi and enters a combustion chamber where it is ignited and burns. At the outlet end of the venturi, a heat shield is typically provided to protect the fuel nozzle assembly. The rear surface of the heat shield, which faces the combustion chamber, is subjected to the high temperatures from the burning fuel and air mixture leaving the venturi. 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 partial cross-sectional side view of an exemplary high bypass turbofan jet engine according to an embodiment of the present disclosure.

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

[0006] Figure 3 is a partial cross-sectional side view of an exemplary pilot fuel nozzle assembly according to an embodiment of the present disclosure.

[0007] Figure 4 According to an embodiment of the present disclosure Figure 3 FIG. 1 is a partial cross-sectional side view of a portion of a fuel nozzle in FIG. 1 , showing a venturi expansion surface of a ventilation pilot venturi of a pilot fuel nozzle assembly having a generally curved profile shape.

[0008] Figure 5 According to another embodiment of the present disclosure Figure 3 A partial cross-sectional side detail view of a portion of a fuel nozzle in , showing the venturi expansion surface of the ventilation pilot venturi of the pilot fuel nozzle assembly, the venturi expansion surface being a dual angle surface.

[0009] Figure 6 According to another embodiment of the present disclosure Figure 3 Details captured at AA Figure 3 A partial cross-sectional side detail view of a portion of a fuel nozzle in FIG. Figure 3 The arrangement of the oxidant outlet ports is shown in FIG.

[0010] Figure 7 is a cross-sectional side detail view of a portion of a fuel nozzle showing a venturi expansion surface of a ventilation pilot venturi of a pilot fuel nozzle assembly according to another embodiment of the present disclosure.

[0011] Figure 8 is a cross-sectional side detail view of a portion of a fuel nozzle according to yet another embodiment of the present disclosure showing a venturi expansion surface of a ventilation pilot venturi of a pilot fuel nozzle assembly.

[0012] Figure 9 is a rear-front view of a pilot fuel nozzle assembly according to an embodiment of the present disclosure. 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 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,” “second,” and “third” 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 singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0018] As used herein, the terms "axial" and "axially" refer to directions and orientations extending generally parallel to the centerline of a turbine engine. Furthermore, the terms "radial" and "radially" refer to directions and orientations extending generally perpendicular to the centerline of a turbine engine. Furthermore, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations extending in an arc about the centerline of a turbine engine.

[0019] As used herein throughout the specification and claims, approximating language is applied to modify any quantitative expression 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," 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.

[0020] Here and throughout the specification and claims, range limitations are combined and interchanged. Unless context or language indicates otherwise, such ranges are identified and include all subranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0021] A known TAPS combustor includes a fuel nozzle assembly with a pilot swirler, which includes a flow splitter and a venturi. The pilot swirler injects a fuel and air mixture into the venturi, which then flows into a combustion chamber where it ignites and burns. A heat shield is typically provided at the outlet end of the venturi to protect the fuel nozzle assembly. The heat shield typically includes a flange, with cooling air supplied to the front surface to cool the flange, and some cooling air also supplied to the rear surface.

[0022] The present disclosure discusses a fuel nozzle architecture having a ventilation venturi feature. More specifically, the present disclosure provides a ventilation venturi as part of a pilot fuel nozzle assembly, wherein the arrangement of the ventilation venturi reduces high temperatures on the surface of the venturi. According to the present disclosure, the ventilation venturi has an air flow channel within the venturi wall and a plurality of rows of oxidant outlet ports extending from the air flow channel through the wall of the venturi to the inner surface of the venturi. The oxidant flows within the air flow channel and through the oxidant outlet ports to provide cooling air to the inner surface of the venturi, and also to the outer end portion of the venturi. The oxidant outlet ports are circumferentially spaced apart in a circumferential direction around the circumference of the inner surface of the venturi and the circumference of the outlet end of the venturi.

[0023] To address the issue of the fuel nozzle assembly's rear heat shield being susceptible to oxidation, which reduces its durability, the heat shield area is minimized, and the shape and design of the Venturi tube wall are customized to reduce wall gas temperatures while maintaining the overall flow structure. The Venturi tube can be made from a single piece or from several segments joined together and arranged at various angles. The Venturi tube has multiple holes. One or more of the Venturi tube segments are provided with a row of cooling holes. One or more of the Venturi tube segments can be free of cooling holes.

[0024] Referring now to the accompanying drawings, Figure 1 is a schematic partial cross-sectional side view of an exemplary high bypass turbofan jet engine 10 (referred to herein as "engine 10") according to an embodiment of the present disclosure. Although further described below with reference to a turbofan engine, the present disclosure is also applicable to turbomachinery in general, including turbojets, turboprops, and turboshaft gas turbine engines, including marine and industrial turbine engines and auxiliary power units. Figure 1 As shown, the engine 10 has a longitudinal centerline axis 12 extending therethrough from an upstream end 98 to a downstream end 99 for reference. Generally, the engine 10 may include a fan assembly 14 and a turbo-engine 16 disposed downstream of the fan assembly 14.

[0025] The turbocharged engine 16 may generally include a substantially tubular casing 18 defining an annular inlet 20. The casing 18 encloses or at least partially forms, in serial flow relationship: a compressor section having a supercharger or low pressure (LP) compressor 22, a high pressure (HP) compressor 24; a combustion section 26; a turbine section including a high pressure (HP) turbine 28, a low pressure (LP) turbine 30; and an ejection exhaust nozzle section 32. A high pressure (HP) rotor shaft 34 drivingly connects the HP turbine 28 to the HP compressor 24. A low pressure (LP) rotor shaft 36 drivingly connects the LP turbine 30 to the LP compressor 22. The LP rotor shaft 36 may also be connected to a fan shaft 38 of the fan assembly 14. In certain embodiments, as shown Figure 1 As shown, the LP rotor shaft 36 can be connected to the fan shaft 38 via a reduction gear 40, such as in an indirect drive or geared configuration. In other embodiments, although not shown, the engine 10 can also include an intermediate pressure (IP) compressor and a turbine rotatable with an IP shaft (not shown).

[0026] like Figure 1As shown, fan assembly 14 includes a plurality of fan blades 42 coupled to and extending radially outward from fan shaft 38. An annular fan casing or nacelle 44 circumferentially surrounds fan assembly 14 and / or at least a portion of turbocharger engine 16. In one embodiment, nacelle 44 may be supported relative to turbocharger engine 16 by a plurality of circumferentially spaced outlet guide vanes or struts 46. Furthermore, at least a portion of nacelle 44 may extend over an outer portion of turbocharger engine 16 to define a bypass airflow passage 48 therebetween.

[0027] Figure 2 According to an embodiment of the present disclosure Figure 1 A partial cross-sectional side view of an exemplary combustion section 26 of the turbocharged engine 16 is shown in FIG. Figure 2 The combustion section 26 in FIG. 2 is depicted as an exemplary dual annular premixing swirler (TAPS) type combustor section. The present disclosure may be implemented in other combustor types, and thus the TAPS combustion section is exemplary only. Figure 2 As shown in , the combustion section 26 may generally include a combustor assembly 50 (e.g., an annular-type combustor assembly) having an annular inner liner 52, an annular outer liner 54, a bulkhead 56, and a dome assembly 58 that together define a combustion chamber 60. The combustion chamber 60 may more specifically define a region defining a primary combustion zone 62, where an initial chemical reaction of the fuel-oxidant mixture and / or recirculation of combustion gases 86 may occur before flowing further downstream, wherein mixing and / or recirculation of combustion products and air may occur before flowing to the HP turbine 28 and the LP turbine 30. The combustor assembly 50 also includes a pilot fuel nozzle assembly 70 having a pilot fuel nozzle portion 73 and a main premixer portion 72. As will be described below, the pilot fuel nozzle section 73 includes a pilot fuel nozzle and a pilot air swirler that produce a swirling pilot fuel and air mixture that is injected into the pilot venturi and then enters the combustion chamber 60, where it is combusted to produce combustion gases 86. The pilot fuel nozzle section 73 generally operates under all operating conditions of the engine 10. The main premixer section 72 has a main fuel nozzle and a main air swirler that produce a main fuel and air mixture that is injected into the combustion chamber 60, where it is also ignited and combusted. The main premixer section 72 generally operates under higher power operation of the engine 10 (e.g., during takeoff or cruise).

[0028] During operation of the engine 10, as Figure 1 and Figure 2As shown collectively, a quantity of air, schematically indicated by arrows 74, enters engine 10 from upstream end 98 through nacelle 44 and / or associated inlet 76 of fan assembly 14. As inlet air 74 passes through fan blades 42, a portion of the air, schematically indicated by arrows 78, is directed or channeled into bypass airflow passage 48, while another portion of the air, schematically indicated by arrows 80, is directed or channeled into LP compressor 22. Air portion 80 is progressively compressed as it flows through LP compressor 22 and HP compressor 24 toward combustion section 26. Figure 2 As shown, the now compressed air, as schematically indicated by arrows 82 , flows through the compressor exit guide vanes (CEGVs) 64 and through the prediffuser 66 into the diffuser cavity 68 of the combustion section 26 .

[0029] Compressed air 82 pressurizes the diffuser cavity 68. A first portion of the compressed air 82, schematically indicated by arrow 82(a), flows from the diffuser cavity 68 into the pilot fuel nozzle assembly 70. Within the pilot fuel nozzle assembly 70, the first portion of the compressed air 82 is premixed with fuel and injected and combusted from the pilot fuel nozzle assembly 70, thereby generating combustion gases, schematically indicated by arrow 86, within the primary combustion zone 62 of the combustor assembly 50. Typically, the LP compressor 22 and the HP compressor 24 provide more compressed air to the diffuser cavity 84 than is required for combustion. Therefore, a second portion of the compressed air 82, schematically indicated by arrow 82(b), can be used for various purposes other than combustion.

[0030] Return to common reference Figure 1 and Figure 2 The combustion gases 86 generated in the combustion chamber 60 flow from the combustor assembly 50 into the HP turbine 28, thereby rotating the HP rotor shaft 34 to support the operation of the HP compressor 24. Figure 1 As shown, combustion gases 86 are then directed through LP turbine 30, thereby rotating LP rotor shaft 36 to support operation of LP compressor 22 and / or rotation of fan shaft 38. Combustion gases 86 are then exhausted through jet exhaust nozzle section 32 of turbocharger engine 16 to provide propulsion at downstream end 99.

[0031] Figure 3 According to the embodiment of the present disclosure Figure 2 A partial cross-sectional side view of an exemplary pilot fuel nozzle portion 73 taken at detail 3-3 in FIG. Figure 2 In FIG. 1 , the pilot fuel nozzle assembly 70 includes a pilot fuel nozzle portion 73 and a main premixer portion 72 attached thereto. The main premixer portion 72 is not Figure 3, and only the pilot fuel nozzle portion 73 is depicted therein. The pilot fuel nozzle portion 73 includes a pilot oxidant inlet 108 and a pilot fuel nozzle 100 aligned along a longitudinal centerline axis 102 (the venturi centerline axis). Figure 3 , the pilot fuel nozzle 100 is shown only as a general representation of a pilot fuel nozzle, and for the sake of clarity, Figure 3 Not shown are internal components such as fuel lines, etc., which are part of the pilot fuel nozzle in what is known as a TAPS type pilot fuel nozzle.

[0032] The pilot fuel nozzle 100 is surrounded by a pilot flow divider 104, which is separated from the pilot fuel nozzle 100 by a pilot inner air passage 110. Positioned within the pilot inner air passage 110 are inner air passage swirl vanes 106. Surrounding the pilot flow divider 104 is a ventilation pilot venturi 116, which will be described in more detail in the following paragraphs. A pilot outer air passage 112 is formed between the pilot flow divider 104 and the ventilation pilot venturi 116, with outer air passage swirl vanes 114 disposed within the pilot outer air passage 112. In operation, air 82(a) enters the pilot oxidant inlet 108, and the flow of air 82(a) is split between the pilot inner air passage 110 and the pilot outer air passage 112 by the pilot flow divider 104. The swirl is introduced into the air 82(a) flowing through the pilot inner air passage 110 and the pilot outer air passage 112 by the inner air passage swirl vanes 106 and the outer air passage swirl vanes 114. Thus, the pilot flow divider 104, the inner air passage swirl vanes 106 and the outer air passage swirl vanes 114 act as a pilot oxidant swirler 115 (formed by the pilot oxidant swirler 115). Figure 3 (Indicated by the dashed circle in FIG. ). The swirling airflow mixes with fuel 118 injected from the pilot fuel nozzle 100 (as indicated by the arrows) in the open cavity portion 120 of the ventilation pilot ignition venturi 116 to produce a swirling fuel and air mixture (not shown). The swirling fuel and air mixture swirls generally circumferentially (C) around the open cavity portion 120 (i.e., swirls in the pilot swirl direction). The swirling fuel and air mixture within the open cavity portion 120 flows toward the outlet 122 of the ventilation pilot ignition venturi 116, where it is ignited and combusted within the combustion chamber 60.

[0033] The ventilation pilot ignition venturi 116 will now be described in greater detail. As shown, the ventilation pilot ignition venturi 116 omits some elements that may be included as part of the pilot fuel nozzle assembly 70, which elements are not necessary for understanding the ventilation pilot ignition venturi 116. In particular, although Figure 3The cross-section of FIG. 1 depicts a generally solid area (e.g., area 124) around the outer portion of the venturi, but area 124 may include elements such as a primary fuel circuit and a primary air flow passage that form part of the main premixer portion 72. Such primary fuel circuits and primary air flow passages that form part of a TAPS-type premixer are known to those skilled in the art.

[0034] exist Figure 3 108. In FIG, the ventilation pilot venturi 116 is shown as being formed by a generally annular wall 128 that extends in a longitudinal direction (L) along the longitudinal centerline axis 102 from an inlet end 126 to an outlet 122. The ventilation pilot venturi 116 also extends circumferentially about the longitudinal centerline axis 102. The annular wall 128 includes an oxidant flow channel 130 within the annular wall 128. The oxidant flow channel 130 extends from the inlet end 126 of the ventilation pilot venturi 116 to an outlet end 132 of the ventilation pilot venturi 116 adjacent the outlet 122. That is, the oxidant flow channel 130 terminates within the annular wall 128 prior to the outlet 122 near a circular outlet tip portion 134. The oxidant flow channel 130 is in fluid communication with the pilot oxidant inlet 108. That is, the inlet end of the ventilation pilot venturi 116 includes a flow passage inlet 136 where air 82 ( a ) from the pilot oxidant inlet 108 may enter the oxidant flow passage 130 .

[0035] The annular wall 128 further defines an inner venturi surface 138 that extends from the venturi inlet end 126 to the venturi outlet 122 and at least partially defines the open cavity portion 120 of the venturi 116 through which the venturi 116 is ignited. Figure 314 (depicted in bold for emphasis) extends circumferentially about the longitudinal centerline axis 102. The inner venturi surface 138 can be generally viewed as comprising an upstream portion 140 that forms the exterior surface of the pilot outer air passage 112, a throat region 142, and a venturi expansion surface 144 downstream of the throat region 142. Thus, the throat region 142 is disposed between the inlet end 126 of the ventilation pilot venturi 116 and the outlet 122 of the ventilation pilot venturi 116. The throat region 142 can be viewed as having a first diameter 117 that is smaller than the remainder of the venturi expansion surface 144 downstream of the throat region. That is, the venturi expansion surface 144 can be viewed as an expanding flow surface portion whose diameter expands as the inner venturi surface 138 progresses from the throat region 142 to the outlet 122. Thus, the venturi expansion surface 144 from the throat region 142 to the outlet 122 of the ventilation pilot venturi 116 includes a first diameter 117 at the throat region and a second diameter 119 at the outlet 122 , wherein the second diameter 119 at the outlet 122 is greater than the first diameter 117 at the throat region 142 .

[0036] The annular wall 128 further defines a plurality of oxidant outlet ports 146. The oxidant outlet ports 146 extend from the oxidant flow passage 130 through the venturi expansion surface 144. Thus, the oxidant outlet ports 146 are apertures that allow air 82(a) flowing through the oxidant flow passage 130 in the annular wall to flow through the apertures and into the open cavity portion 120. The oxidant outlet ports 146 will be described in greater detail below, but the plurality of oxidant outlet ports 146 may be circumferentially spaced apart in the circumferential direction (C) about the longitudinal centerline axis 102.

[0037] Figure 4 The venturi expansion surface 144 is shown as having a generally curved profile extending from the throat region 142 to the outlet 122. Alternatively, the venturi expansion surface 144 may be a generally tapered portion (i.e., a tapered surface) extending from the throat region 142 to the outlet 122. The half angle 148 of the venturi expansion surface 144 (e.g., a single tapered venturi expansion surface) may range from fifteen degrees to forty degrees. Of course, the present disclosure is not limited to the aforementioned ranges, and other half angles may be implemented alternatively.

[0038] Figure 5A venturi expansion surface 144 according to an embodiment of the present disclosure is depicted as a dual-angle surface. That is, a first conical surface segment 150 of the venturi expansion surface 144 may be a generally conical surface extending along the first conical surface segment 150 from the throat region 142 to a breakpoint 158. The first conical surface segment 150 may have a first conical half-angle 154. A second conical surface segment 152 of the venturi expansion surface 144 may also be a generally conical surface extending from the breakpoint 158 to the outlet 122. The second conical surface segment 152 may have a second conical half-angle 156. In one aspect, the first conical half-angle may range from 15 to 30 degrees, while the second conical half-angle may range from 30 to 40 degrees. In another aspect, the first conical half-angle may range from 30 to 40 degrees, while the second conical half-angle may range from 15 to 30 degrees. Of course, the present disclosure is not limited to the aforementioned ranges, and other half-angles may alternatively be implemented. Furthermore, the expansion surfaces of the present disclosure are not limited to only two conical surfaces, and other arrangements may alternatively be implemented. For example, the first tapered surface section 150 may be implemented up to the breakpoint 158, and a curved surface implemented downstream of the breakpoint. Alternatively, a curved surface may be implemented in place of the first tapered surface section 150 up to the breakpoint 158, and then the second tapered surface section 152 may be included from the breakpoint 158 to the outlet 122. Furthermore, the present disclosure is not limited to dividing the venturi expansion surface 144 into two sections, but rather more than two sections may be implemented. For example, three tapered surface sections may be implemented, with two separate breakpoints between the tapered surfaces.

[0039] Figure 6 is Figure 3 The enlarged image taken at AA in the detail of Figure 3 The arrangement of the oxidant outlet port 146 is shown in FIG. Figure 6 The dual angle venturi expansion surface 144 is shown with the arrangement of the oxidant outlet port 146. Therefore, the arrangement of the oxidant outlet port 146 relative to the dual angle expansion surface will be described. The first conical surface section 150 is considered to include the oxidant outlet ports 162 and 182 (corresponding to Figure 3oxidant outlet ports 146). Each of the oxidant outlet ports 162 and 182 extends from the oxidant flow channel 130 through the first conical surface segment 150. In the ventilated venturi of the present disclosure, a plurality of oxidant outlet ports 162 are arranged around the periphery of the first conical surface segment 150, and a plurality of oxidant outlet ports 182 are arranged around the periphery of the first conical surface segment 150. The plurality of oxidant outlet ports 162 arranged around the periphery of the first conical surface segment 150 may be referred to as a first row of oxidant outlet ports, and the plurality of oxidant outlet ports 182 arranged around the periphery of the first conical surface segment 150 may be referred to as a second row of oxidant outlet ports. Collectively, the first row of oxidant outlet ports 162 and the second row of oxidant outlet ports 182 may be referred to as a first group of oxidant outlet ports. In Figure 6 , the first row of oxidant outlet ports 162 may be disposed at a radial distance 178 from the longitudinal centerline axis 102 , while the second row of oxidant outlet ports 182 may be considered disposed at a radial distance 180 that is different from the radial distance 178 .

[0040] The oxidant outlet port 162 can be aligned at an angle 184 relative to the first tapered surface segment 150 in the longitudinal direction (L). The oxidant outlet port 182 can be aligned at an angle 166 relative to the first tapered surface segment 150 in the longitudinal direction (L). Angles 184 and 166 can be the same, or can be different from each other. In some aspects of the present disclosure, angles 184 and 166 can range from twelve degrees to thirty degrees. Of course, the present disclosure is not limited to the above ranges, and angles 184 and 166 can alternatively be arranged at other angles.

[0041] The second conical surface section 152 is seen to include oxidant outlet ports 164 and 172 (also corresponding to Figure 3 oxidant outlet ports 146). Each of the oxidant outlet ports 164 and 172 extends from the oxidant flow channel 130 through the second conical surface segment 152. In the ventilated venturi of the present disclosure, a plurality of oxidant outlet ports 164 are arranged around the periphery of the second conical surface segment 152, and a plurality of oxidant outlet ports 172 are arranged around the periphery of the second conical surface segment 152. The plurality of oxidant outlet ports 164 arranged around the periphery of the second conical surface segment 152 may be referred to as a third row of oxidant outlet ports, and the plurality of oxidant outlet ports 172 arranged around the periphery of the second conical surface segment 152 may be referred to as a fourth row of oxidant outlet ports. Collectively, the third row of oxidant outlet ports 164 and the fourth row of oxidant outlet ports 172 may be referred to as a second group of oxidant outlet ports. Figure 6, the third row of oxidant outlet ports 164 may be considered to be arranged at a radial distance 176 from the longitudinal centerline axis 102 , while the fourth row of oxidant outlet ports 172 may be considered to be arranged at a radial distance 174 that is different from the radial distance 176 .

[0042] The oxidant outlet port 164 can be aligned at an angle 168 relative to the second tapered surface segment 152 in the longitudinal direction (L). The oxidant outlet port 172 is seen to be aligned at an angle 186 relative to the second tapered surface segment 152 in the longitudinal direction (L). Angles 168 and 186 can be the same, or can be different from each other. In some aspects of the present disclosure, angles 168 and 186 can range from twelve degrees to thirty degrees. Of course, the present disclosure is not limited to the above ranges, and other angles can be implemented alternatively.

[0043] exist Figure 6 , the circular outlet tip portion 134 is viewed as including a tip oxidant outlet port 160. The tip oxidant outlet port 160 extends from the oxidant flow channel 130 through the circular outlet tip portion 134. The tip oxidant outlet port 160 is viewed as being aligned at an angle 190 relative to the longitudinal centerline axis 102, wherein the angle 190 extends radially outward and rearward. Similar to the oxidant outlet ports 164, 172, the angle 190 of the tip oxidant outlet port can range from twelve degrees to thirty degrees. Of course, the present disclosure is not limited to a tip oxidant outlet port 160 at the circular outlet tip portion 134, and as Figure 6 As shown, a second tip oxidant outlet port 170 may be included. Additional tip oxidant outlet ports may also be included depending on the cooling effect to be achieved. Of course, the present disclosure is not limited to the above range, and angle 190 may be arranged at other angles instead.

[0044] Figure 7 and Figure 8 FIG. 2 shows the venturi expansion surface 244 of the ventilation and ignition venturi 116 according to another embodiment of the present disclosure. Figure 7 and Figure 8 As shown, the venturi expansion surface 244 has a first venturi expansion surface portion 244A and a second venturi expansion surface portion 244B. The first venturi expansion surface portion 244A extends along the venturi expansion surface 244 from the throat region 142 to a breakpoint 246 (e.g., a junction). The second venturi expansion surface portion 244B extends from the breakpoint 246 to a tip portion 248 of the ventilation and ignition venturi 116. The first venturi expansion surface portion 244A is mechanically joined (e.g., brazed, soldered, welded, or connected) to the second venturi expansion surface portion 244B at the breakpoint 246. For example, Figure 7As shown, the second venturi expansion surface portion 244B has a square edge at the breakpoint 246 for mating with a corresponding square edge of the first venturi expansion surface portion 244A. The tip portion 248 of the ventilation pilot venturi is located radially outward of the longitudinal centerline axis 102 compared to the breakpoint 246. The first venturi expansion surface portion 244A is located at a first radial distance from the longitudinal centerline axis 102, and the second venturi expansion surface portion 244B is located at a second radial distance from the longitudinal centerline axis 102, the second radial distance being greater than the first radial distance. The second venturi expansion surface portion 244B is formed from a single segment made from a single material selected to withstand combustion temperatures. The first venturi expansion surface portion 244A is formed from one or more surface segments. As Figure 7 and Figure 8 As shown, the first venturi expansion surface portion 244A has a plurality of tapered surface segments 250. The plurality of tapered surface segments 250 form a circumferential tapered annular surface about the longitudinal centerline axis 102. Figure 7 At least two of the plurality of tapered surface segments 250 are shown mechanically joined together in series. The term "in series" is used herein to indicate that one end of one tapered surface segment is connected to an adjacent or next tapered surface segment, which in turn is connected to yet another adjacent or next tapered surface segment, and so on. In embodiments, the plurality of tapered surface segments 250 are separate pieces joined together using any joining technique. Examples of joining techniques include brazing, soldering, or welding the plurality of tapered surface segments 250. Another example of a joining technique includes adhesive bonding or chemical bonding. In embodiments, the plurality of tapered surface segments 250 can be made of the same material or different materials. In another embodiment, at least two of the plurality of tapered surface segments 250 can be made of the same material as a single, unitary piece. In embodiments, as will be described in further detail in the following paragraphs, the plurality of tapered surface segments 250 are angled relative to each other and relative to the longitudinal centerline axis 102. Any number of tapered surface segments 250 can be used. When the number of tapered surface segments 250 is relatively high (eg, greater than ten), the shape of the first venturi expansion surface portion 244A can be said to vary continuously, and the edges between the tapered surface segments are smoothed.

[0045] Figure 7A first venturi expansion surface portion 244A is shown having two surface segments, namely, a first conical surface segment 250A and a second conical surface segment 250B. For example, for purposes of explanation and illustration, two conical surface segments 250A and 250B are discussed herein. However, any number of conical surface segments may be used. The first conical surface segment 250A defines a first conical half-angle θ1 relative to the longitudinal centerline axis 102. The second conical surface segment 250B defines a second conical half-angle θ2 relative to the longitudinal centerline axis 102. The first conical surface segment 250A and the second conical surface segment 250B are joined together such that one end of the first conical surface segment is connected to one end of the second conical surface segment.

[0046] Figure 8 A first venturi expansion surface portion 244A is shown having three surface segments, namely, a first tapered surface segment 250A, a second tapered surface segment 250B, and a third tapered surface segment 250C. The first tapered surface segment 250A defines a first tapered half-angle θ1 relative to the longitudinal centerline axis 102. The second tapered surface segment 250B defines a second tapered half-angle θ2 relative to the longitudinal centerline axis 102. The third tapered surface segment 250C defines a third tapered half-angle θ3 relative to the longitudinal centerline axis 102. Although Figure 7 and Figure 8 , two and three surface segments are depicted, respectively, but the first tapered surface segment 250A may have one, two, or more surface segments. The first tapered half-angle θ1 may be between approximately 15° and 40°. The second tapered half-angle θ2 may be between approximately 20° and 40°. The third tapered half-angle θ3 may be between approximately 30° and 40°.

[0047] like Figure 7 and Figure 8 As shown, the second venturi expansion surface portion 244B has a single tapered surface segment 245 that forms a fourth tapered half-angle θ4 relative to the longitudinal centerline axis 102, and the single tapered surface segment 245 is formed as a single piece (e.g., made of a single material) selected to withstand combustion temperatures. The fourth tapered half-angle θ4 can be between approximately 40° and 50°. However, the present disclosure is not limited to the above range, and other half-angles can be implemented alternatively. In an embodiment, as shown in FIG. Figure 7 As shown, the single tapered surface segment 245 of the second venturi expansion surface portion 244B is mechanically engaged with the second tapered surface segment 250B of the first venturi expansion surface portion 244A. Figure 7 As shown, the edge of the single tapered surface segment 245 is mechanically engaged (fitted, brazed, welded, etc.) with the edge of the second tapered surface segment 250B. Figure 7As shown, the single tapered surface segment 245 of the second venturi expansion surface portion 244B has two ends. One edge is connected to the tip portion 248 of the ventilation pilot venturi 116, and the opposite edge is connected to the edge of the second tapered surface segment 250B. Figure 7 , the single tapered surface segment 245 of the second venturi expansion surface portion 244B can have a polygonal cross-sectional shape selected to allow for an increased number of rows of oxidant outlet ports or holes in the single tapered surface segment 245 of the second venturi expansion surface portion 244B. While the second venturi expansion surface portion 244B is shown as having a single tapered surface segment 245, the second venturi expansion surface portion 244B can also have multiple tapered surface segments.

[0048] In an embodiment, the first taper half-angle θ1 is smaller than the second taper half-angle θ2, the second taper half-angle θ2 is smaller than the third taper half-angle θ3, and the third taper half-angle θ3 is smaller than the fourth taper half-angle θ4 (i.e., θ1<θ2<θ3<θ4). In another embodiment, the first taper half-angle θ1 is smaller than the second taper half-angle θ2, the second taper half-angle θ2 is smaller than the third taper half-angle θ3, and the third taper half-angle θ3 is larger than the fourth taper half-angle θ4 (i.e., θ1<θ2<θ3>θ4). In another embodiment, the first taper half-angle θ1 is smaller than the second taper half-angle θ2, the second taper half-angle θ2 is larger than the third taper half-angle θ3, and the third taper half-angle θ3 is smaller than the fourth taper half-angle θ4 (i.e., θ1<θ2>θ3<θ4). In another embodiment, the first cone half-angle θ1 is less than the second cone half-angle θ2, the second cone half-angle θ2 is greater than the third cone half-angle θ3, and the third cone half-angle θ3 is greater than the fourth cone half-angle θ4 (i.e., θ1 < θ2 > θ3 > θ4). The angles of the segments can be advantageously selected to provide a desired flow structure or control the boundary layer of the gas flow, which helps to achieve an optimally low gas temperature on the venturi surface. In addition, the angles can be selected to provide a desired pilot air volume and recirculation zone, thereby improving flame stability.

[0049] like Figure 7 and Figure 8 As shown, the plurality of tapered surface segments 250 are shown as being flat or linear. However, any one or more of the plurality of tapered surface segments 250 may have a curved surface. For example, while the first tapered surface segment 250A may be flat, the second tapered surface segment 250B may have a curved surface.

[0050] like Figure 7As shown, the ventilation pilot venturi 116 has a plurality of oxidant outlet ports 262 distributed on the venturi expansion surface 244. The plurality of oxidant outlet ports 262 can be provided on the first venturi expansion surface portion 244A and / or the second venturi expansion surface portion 244B of the venturi expansion surface 244. Alternatively, in another embodiment, any of the first venturi expansion surface portion 244A and / or the second venturi expansion surface portion 244B may not be provided with an oxidant outlet port. In an embodiment, at least one row of oxidant outlet ports 262 is provided through each segment (e.g., the first venturi expansion surface portion 244A and the second venturi expansion surface portion 244B), or one or more segments (e.g., the first venturi expansion surface portion 244A or the second venturi expansion surface portion 244B) may not have an oxidant outlet port 262. For clarity, Figure 8 The multiple oxidant outlet ports 262 arranged on the venturi tube expansion surface 244 are not shown in order to more clearly show the first conical half-angle θ1, the second conical half-angle θ2 and the third conical half-angle θ3 of the multiple conical surface segments 250, and the fourth conical half-angle θ4 of the single conical surface segment 245 of the second venturi tube expansion surface portion 244B.

[0051] exist Figure 7 In the illustrated embodiment, a first plurality of oxidant outlet ports 264 are arranged about the periphery of the first conical surface segment 250A, and a second plurality of oxidant outlet ports 266 are arranged about the periphery of the second conical surface segment 250B. The first plurality of oxidant outlet ports 264 arranged about the periphery of the first conical surface segment 250A may be referred to as a first row of oxidant outlet ports, and the second plurality of oxidant outlet ports 266 arranged about the periphery of the second conical surface segment 250B may be referred to as a second row of oxidant outlet ports. The first plurality of oxidant outlet ports 264 may be arranged at a radial distance R1 from the longitudinal centerline axis 102, while the second plurality of oxidant outlet ports 266 may be arranged at a radial distance R2 that is different from the radial distance R1 (e.g., the radial distance R2 is greater than the radial distance R1).

[0052] In an embodiment, a third plurality of oxidant outlet ports 268 may be provided on the second venturi expansion surface portion 244B. Figure 7As shown, a third plurality of oxidant outlet ports 268 are arranged around the periphery of the second venturi expansion surface portion 244B as a plurality of third rows of oxidant outlet ports. The third plurality of oxidant outlet ports 268 can be arranged at a radial distance R3 from the longitudinal centerline axis 102, where the radial distance R3 is greater than the radial distance R2 and the radial distance R1. In an embodiment, the number of rows of the third plurality of oxidant outlet ports 268 provided on the second venturi expansion surface portion 244B (e.g., four rows, e.g., Figure 7 ) is greater than the number of rows of the first plurality of oxidant outlet ports 264 arranged around the periphery of the first conical surface segment 250A (e.g., one row, as shown). Figure 7 ) and the number of rows of the second plurality of oxidant outlet ports 266 arranged around the periphery of the second conical surface segment 250B (e.g., two rows, as shown in FIG. Figure 7 ), because the second venturi expansion surface portion 244B is subjected to a higher temperature than the first tapered surface segment 250A. In an embodiment, since the venturi surface area increases with increasing radius in the axial direction (2·π·r), the number of outlet ports is increased to achieve effective cooling of the venturi wall.

[0053] Although the above description is made with reference to one row of a first plurality of oxidant outlet ports 264 around the periphery of the first conical surface segment 250A and two rows of a second plurality of oxidant outlet ports 266 around the periphery of the second conical surface segment 250B (three rows total), the present disclosure is not limited to three rows of oxidant outlet ports. More specifically, the number of rows of oxidant outlet ports can range from one row of oxidant outlet ports to ten rows of oxidant outlet ports. Similarly, the third plurality of oxidant outlet ports 268 are arranged around the periphery of the second venturi expansion surface portion 244B as a plurality of third rows of oxidant outlet ports, which can be two or more rows (e.g., four rows, as in Figure 7 ). However, the number of rows is not limited to the above, and the number of rows may be selected based on the desired cooling effect to be achieved. In addition, one or more of the plurality of conical surface segments 250 (e.g., the first conical surface segment 250A and / or the second conical surface segment 250B) may not have any oxidant outlet ports.

[0054] Figure 9 is a rear-front view of a pilot fuel nozzle assembly according to aspects of the present disclosure. Figure 9As shown, the third plurality of oxidant outlet ports 268 are circumferentially spaced about the periphery of the second venturi expansion surface portion 244B. The circumferential spacing 300 of the third plurality of oxidant outlet ports 268 can be based on the size of the third plurality of oxidant outlet ports 268. For example, the circumferential spacing 300 can be at least twice the average diameter of the third plurality of oxidant outlet ports 268, or up to six times the average diameter of the third plurality of oxidant outlet ports 268. Here, the average diameter of the third plurality of oxidant outlet ports 268 can be from 0.02 inches to 0.038 inches (or, approximately 0.50 mm to 0.965 mm). The above spacing and outlet port diameter dimensions can also apply to the first plurality of oxidant outlet ports 264 and the second plurality of oxidant outlet ports 266. The spacing between the first plurality of oxidant outlet ports 264, the second plurality of oxidant outlet ports 266, or the third plurality of oxidant outlet ports 268 can be the same or different. The circumferential spacing 300 between the first plurality of oxidant outlet ports 264, the second plurality of oxidant outlet ports 266, or the third plurality of oxidant outlet ports 268 can be at least two times, or up to six times, the average diameter of the oxidant outlet ports. Of course, the spacing and dimensions of the outlet ports are not limited to the foregoing, and other spacings or port dimensions may alternatively be implemented depending on the cooling effect to be achieved. The interface edge 290 between the first venturi expansion surface portion 244A and the second venturi expansion surface portion 244B is at Figure 9 The interface edge 290 corresponds to Figure 7 The breakpoint 246 (eg, junction) shown in FIG.

[0055] The first plurality of oxidant outlet ports 264 arranged around the periphery of the first conical surface segment 250A and / or the second plurality of oxidant outlet ports 266 arranged around the periphery of the second conical surface segment 250B may also be arranged at an angle relative to the circumferential direction (C) to provide a swirl of air within the venturi. For example, the first plurality of oxidant outlet ports 264 and / or the second plurality of oxidant outlet ports 266 may be arranged at a co-swirl circumferential angle 302 to provide air flow in a co-swirl direction relative to the ignition swirl direction. In one aspect, the co-swirl circumferential angle 302 may range from zero degrees to sixty degrees. Of course, the co-swirl circumferential angle 302 is not limited to the above range, and other angles may be implemented alternatively based on the desired swirl effect. Additionally, although Figure 9 A single co-swirling circumferential angle 302 is depicted for the row of oxidant outlet ports closest to the longitudinal centerline axis 102 , but oxidant outlet ports arranged in rows outboard of the innermost row may also be angled in the co-swirling direction.

[0056] The above-mentioned ventilation venturi provides additional cooling of the outlet end of the venturi. The air flowing through the outlet port is used to cool the venturi wall. The air flowing through the outlet port is not intended to mix with the fuel-air mixture exiting the pilot burner. The ventilation venturi can be made of a single part, or it can be made of several segments joined together and arranged at different segment angles. Each segment can have multiple oxidant outlet ports. One or more segments of the venturi are provided with a row of cooling oxidant outlet ports. One or more segments of the venturi can also not have cooling oxidant outlet ports. In an embodiment, the ventilation venturi can have an overall larger divergence angle to create a larger recirculation zone for pilot flame stability. The divergence angle corresponds to the overall increase in the angle from the inlet end of the venturi to the outlet end of the venturi. The larger venturi angle causes the pilot flame to be closer to the main flame, surrounding the main flame, and thus promoting flame stability in the fuel staging mode. The larger the discharge angle of the venturi tube, the closer the fuel-air mixture emitted from the pilot burner (i.e., the pilot fuel-air mixture) is to the main fuel-air mixer. The pilot fuel-air mixture and the main fuel-air mixture interact closely, thereby improving flame stability.

[0057] While the above description generally relates to gas turbine engines, gas turbine engines can be implemented in a variety of environments. For example, the engine can be implemented in an aircraft, but can also be implemented in non-aircraft applications such as power plants, marine applications, or oil and gas production applications. Therefore, the present disclosure is not limited to use in aircraft.

[0058] Further aspects are provided by the subject matter of the following clauses.

[0059] 19. The burner assembly of claim 18, wherein the burner assembly comprises a first pilot fuel nozzle and a second pilot fuel nozzle, the first pilot fuel nozzle and the second pilot fuel nozzle having a central axis extending along a central axis of the burner. The second pilot fuel nozzle comprises a first pilot fuel nozzle and a second pilot fuel nozzle having a central axis extending along a central axis of the burner. The second pilot fuel nozzle comprises a first pilot fuel nozzle and a second pilot fuel nozzle having a central axis extending along a central axis of the burner. The second pilot fuel nozzle comprises a first pilot fuel nozzle and a second pilot fuel nozzle having a central axis extending along a central axis of the burner. The orifice fluid is connected to define an ignition outer air passage between the ignition diverter and the ventilation pilot venturi tube, the ventilation pilot venturi tube including an annular wall, the annular wall extending circumferentially around the centerline axis of the fuel nozzle and extending in the longitudinal direction along the centerline axis of the fuel nozzle from the inlet end of the ventilation pilot venturi tube to the outlet of the ventilation pilot venturi tube, the annular wall including an oxidant flow channel within the annular wall, the oxidant flow channel extending from the inlet end of the ventilation pilot venturi tube to the outlet end of the ventilation pilot venturi tube adjacent to the outlet, and the oxidant flow channel is connected to the ignition oxidant inlet fluid. The annular wall defines an inner venturi surface, which defines an open cavity through the ventilation and ignition venturi, the inner venturi surface including: a throat region, which is arranged between the inlet end of the ventilation and ignition venturi and the outlet of the ventilation and ignition venturi, the throat region having a diameter smaller than the remaining portion of the inner venturi surface downstream of the throat region; and a venturi expansion surface, which is arranged in the longitudinal direction from the throat region to the outlet of the ventilation and ignition venturi, the venturi expansion surface having a first diameter at the throat region and a second diameter at the outlet, the second diameter being larger than the first diameter. The venturi expansion surface includes a plurality of conical surface segments extending circumferentially about the fuel nozzle centerline axis, and at least two conical surface segments are mechanically joined together, and one or more of the plurality of conical surface segments have a plurality of venturi oxidant outlet ports extending from the oxidant flow channel through the venturi expansion surface, and the plurality of venturi oxidant outlet ports are circumferentially spaced about the fuel nozzle centerline axis.

[0060] The pilot fuel nozzle assembly according to the preceding clause, wherein the plurality of conical surface segments are separate segment pieces joined together.

[0061] The pilot fuel nozzle assembly of any preceding clause, wherein the plurality of conical surface segments are made of the same material.

[0062] The pilot fuel nozzle assembly of any preceding clause, wherein two or more of the plurality of conical surface segments are fabricated from a single unitary piece of the same material.

[0063] The pilot fuel nozzle assembly of any preceding clause, wherein the plurality of conical surface segments are angled relative to each other and relative to the fuel nozzle centerline axis.

[0064] The pilot fuel nozzle assembly of any preceding clause, wherein one or more of the plurality of tapered surface segments is flat or curved.

[0065] The pilot fuel nozzle assembly of any preceding clause, wherein each of the plurality of venturi oxidant outlet ports is arranged at a radially outwardly extending angle relative to the fuel nozzle centerline axis.

[0066] A pilot fuel nozzle assembly according to any preceding clause, wherein the plurality of venturi oxidant outlet ports are arranged in a row circumferentially about the venturi expansion surface, and wherein the circumferential spacing between each of the venturi oxidant outlet ports in the row is in the range of two times the average diameter of the venturi oxidant outlet ports to six times the average diameter of the venturi oxidant outlet ports.

[0067] A pilot fuel nozzle assembly according to any preceding clause, wherein the plurality of venturi oxidant outlet ports are arranged at a co-swirl circumferential angle relative to a circumferential direction about a centerline axis of the fuel nozzle, the co-swirl circumferential angle being in the range of zero to sixty degrees, and the co-swirl circumferential angle being in the same direction as the pilot swirl direction of the pilot oxidant swirler.

[0068] A pilot fuel nozzle assembly according to any preceding clause, wherein the venturi expansion surface includes a first venturi expansion surface portion and a second venturi expansion surface portion, wherein the first venturi expansion surface portion includes a first conical surface segment and a second conical surface segment, the second conical surface segment is connected to the first conical surface segment, and the second venturi expansion surface portion includes a single conical surface segment, wherein a first plurality of oxidant outlet ports are arranged as a first row of oxidant outlet ports around the periphery of the first conical surface segment, and a second plurality of oxidant outlet ports are arranged as a second row of oxidant outlet ports around the periphery of the second conical surface segment, wherein a third plurality of oxidant outlet ports are arranged on the single conical surface segment of the second venturi expansion surface portion as a plurality of third rows of oxidant outlet ports, and wherein the number of rows of the third plurality of oxidant outlet ports is greater than the number of rows of the first plurality of oxidant outlet ports and greater than the number of rows of the second plurality of oxidant outlet ports.

[0069] A pilot fuel nozzle assembly according to any preceding clause, wherein the venturi expansion surface has a first venturi expansion surface portion and a second venturi expansion surface portion, the first venturi expansion surface portion extending along the venturi expansion surface from the throat region to a breakpoint, and the second venturi expansion surface portion extending from the breakpoint to a tip portion of the ventilation pilot venturi.

[0070] The pilot fuel nozzle assembly of any preceding clause, wherein the second venturi expansion surface portion has a single conical surface segment formed from a single material selected to withstand combustion temperatures.

[0071] The pilot fuel nozzle assembly of any preceding clause, wherein the first venturi expansion surface portion includes a first conical surface segment, a second conical surface segment, and a third conical surface segment, the third conical surface segment connected to the second conical surface segment, and the second conical surface segment connected to the first conical surface segment.

[0072] The pilot fuel nozzle assembly of any preceding clause, wherein the first conical surface segment defines a first conical half-angle θ1 relative to the fuel nozzle centerline axis, the second conical surface segment defines a second conical half-angle θ2 relative to the fuel nozzle centerline axis, and the third conical surface segment defines a third conical half-angle θ3 relative to the fuel nozzle centerline axis.

[0073] A pilot fuel nozzle assembly according to any preceding clause, wherein the second venturi tube expansion surface portion has a single conical surface segment, the single conical surface segment defining a fourth conical half-angle θ4 relative to the fuel nozzle centerline axis, wherein the first conical half-angle θ1 is less than the second conical half-angle θ2, the second conical half-angle θ2 is less than the third conical half-angle θ3, and the third conical half-angle θ3 is less than the fourth conical half-angle θ4.

[0074] A pilot fuel nozzle assembly according to any preceding clause, wherein the second venturi tube expansion surface portion has a single conical surface segment, the single conical surface segment defining a fourth conical half-angle θ4 relative to the fuel nozzle centerline axis, wherein the first conical half-angle θ1 is less than the second conical half-angle θ2, the second conical half-angle θ2 is less than the third conical half-angle θ3, and the third conical half-angle θ3 is greater than the fourth conical half-angle θ4.

[0075] A pilot fuel nozzle assembly according to any preceding clause, wherein the second venturi tube expansion surface portion has a single conical surface segment, the single conical surface segment defining a fourth conical half-angle θ4 relative to the fuel nozzle centerline axis, wherein the first conical half-angle θ1 is less than the second conical half-angle θ2, the second conical half-angle θ2 is greater than the third conical half-angle θ3, and the third conical half-angle θ3 is less than the fourth conical half-angle θ4.

[0076] A pilot fuel nozzle assembly according to any preceding clause, wherein the second venturi tube expansion surface portion has a single conical surface segment, the single conical surface segment defining a fourth conical half-angle θ4 relative to the fuel nozzle centerline axis, wherein the first conical half-angle θ1 is less than the second conical half-angle θ2, the second conical half-angle θ2 is greater than the third conical half-angle θ3, and the third conical half-angle θ3 is greater than the fourth conical half-angle θ4.

[0077] The pilot fuel nozzle assembly of any preceding clause, wherein the second venturi expansion surface portion has a single conical surface segment, the single conical surface segment defining a fourth conical half-angle θ4 relative to the fuel nozzle centerline axis, wherein the first conical half-angle θ1 is between 15° and 40°, the second conical half-angle θ2 is between 20° and 40°, the third conical half-angle θ3 is between 30° and 40°, and the fourth conical half-angle θ4 is between approximately 40° and 50°.

[0078] 1. A turbine engine, comprising a combustor having a pilot fuel nozzle assembly, the pilot fuel nozzle assembly comprising: a pilot fuel nozzle, the pilot fuel nozzle being defined around a fuel nozzle centerline axis; a pilot oxidizer inlet, the pilot oxidizer inlet being arranged adjacent to the pilot fuel nozzle; a pilot flow divider, the pilot flow divider being arranged radially outward from the pilot fuel nozzle to define a pilot inner air passage between the pilot fuel nozzle and the pilot flow divider, the pilot inner air passage being in fluid communication with the pilot oxidizer inlet; and a ventilation pilot venturi, the ventilation pilot venturi being arranged radially outward from the pilot flow divider and in fluid communication with the pilot oxidizer inlet The orifice fluid is connected to define an ignition outer air passage between the ignition diverter and the ventilation pilot venturi tube, the ventilation pilot venturi tube including an annular wall, the annular wall extending circumferentially around the centerline axis of the fuel nozzle and extending in the longitudinal direction along the centerline axis of the fuel nozzle from the inlet end of the ventilation pilot venturi tube to the outlet of the ventilation pilot venturi tube, the annular wall including an oxidant flow channel within the annular wall, the oxidant flow channel extending from the inlet end of the ventilation pilot venturi tube to the outlet end of the ventilation pilot venturi tube adjacent to the outlet, and the oxidant flow channel is connected to the ignition oxidant inlet fluid. The annular wall defines an inner venturi surface, which defines an open cavity through the ventilation and ignition venturi, the inner venturi surface including: a throat region, which is arranged between the inlet end of the ventilation and ignition venturi and the outlet of the ventilation and ignition venturi, the throat region having a diameter smaller than the remaining portion of the inner venturi surface downstream of the throat region; and a venturi expansion surface, which is arranged in the longitudinal direction from the throat region to the outlet of the ventilation and ignition venturi, the venturi expansion surface having a first diameter at the throat region and a second diameter at the outlet, the second diameter being larger than the first diameter. The venturi expansion surface includes a plurality of conical surface segments extending circumferentially about the fuel nozzle centerline axis, and at least two conical surface segments are mechanically joined together, and one or more of the plurality of conical surface segments have a plurality of venturi oxidant outlet ports extending from the oxidant flow channel through the venturi expansion surface, and the plurality of venturi oxidant outlet ports are circumferentially spaced about the fuel nozzle centerline axis.

[0079] 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 pilot fuel nozzle assembly for a combustor of a gas turbine engine, characterized in that: The pilot fuel nozzle assembly comprises: a pilot fuel nozzle defined about a fuel nozzle centerline axis; a pilot oxidant inlet, the pilot oxidant inlet being disposed adjacent to the pilot fuel nozzle; a pilot flow splitter disposed radially outward from the pilot fuel nozzle to define a pilot inner air passage between the pilot fuel nozzle and the pilot flow splitter, the pilot inner air passage being in fluid communication with the pilot oxidant inlet; and and a nozzle which extends from a nozzle into the nozzle of the nozzle and into the nozzle of the nozzle, wherein the nozzle is rotatable and has a nozzle which extends outwardly from the nozzle of the nozzle to the nozzle of the nozzle, wherein the nozzle is rotatable and has a nozzle which extends outwardly from the nozzle of the nozzle to the nozzle of the nozzle, wherein the nozzle is rotatable and has a nozzle which extends outwardly from the nozzle of the nozzle to the nozzle of the nozzle, wherein the nozzle is rotatable and has a nozzle which extends outwardly from the nozzle of the nozzle to the nozzle of the nozzle, wherein the annular wall defines an inner venturi surface, the inner venturi surface defining an open cavity through which the ventilation ignition venturi passes, the inner venturi surface comprising: (a) a throat region disposed between the inlet end of the ventilation pilot ignition venturi and the outlet of the ventilation pilot ignition venturi, the throat region having a smaller diameter than a remainder of the inner venturi surface downstream of the throat region; and (b) a venturi expansion surface disposed in the longitudinal direction from the throat region to the outlet of the ventilation pilot venturi, the venturi expansion surface having a first diameter at the throat region and a second diameter at the outlet, the second diameter being greater than the first diameter, wherein the venturi expansion surface includes a plurality of conical surface segments extending circumferentially about the fuel nozzle centerline axis, and at least two of the plurality of conical surface segments are mechanically joined together, and one or more of the plurality of conical surface segments have a plurality of venturi oxidant outlet ports extending from the oxidant flow channel through the venturi expansion surface, and the plurality of venturi oxidant outlet ports are circumferentially spaced about the fuel nozzle centerline axis.

2. The pilot fuel nozzle assembly according to claim 1, wherein: in, The plurality of tapered surface segments are separate segments joined together.

3. The pilot fuel nozzle assembly according to claim 1, wherein: in, The plurality of tapered surface segments are made of the same material.

4. The pilot fuel nozzle assembly according to claim 1, wherein: in, Two or more of the plurality of tapered surface segments are made from the same material as a single unitary piece.

5. The pilot fuel nozzle assembly according to claim 1, wherein: in, The plurality of tapered surface segments are angled relative to each other and relative to the fuel nozzle centerline axis.

6. The pilot fuel nozzle assembly according to claim 1, wherein: in, One or more of the plurality of tapered surface segments is flat or curved.

7. The pilot fuel nozzle assembly according to claim 1, wherein: in, Each of the plurality of venturi oxidant outlet ports is arranged at a radially outwardly extending angle relative to the fuel nozzle centerline axis.

8. The pilot fuel nozzle assembly according to claim 1, wherein: in, The plurality of venturi oxidant outlet ports are circumferentially arranged in a row around the venturi expansion surface, and wherein the circumferential spacing between each of the venturi oxidant outlet ports in the row is in the range of two times the diameter of the venturi oxidant outlet port to six times the diameter of the venturi oxidant outlet port.

9. The pilot fuel nozzle assembly according to claim 1, wherein: in, The plurality of venturi oxidant outlet ports are arranged at a co-swirl circumferential angle relative to a circumferential direction about a centerline axis of the fuel nozzle, the co-swirl circumferential angle being in a range of zero to sixty degrees, and the co-swirl circumferential angle being in the same direction as a pilot swirl direction of the pilot oxidant swirler.

10. The pilot fuel nozzle assembly of claim 1, wherein: in, the venturi expansion surface comprising a first venturi expansion surface portion and a second venturi expansion surface portion, wherein the first venturi expansion surface portion comprises a first conical surface segment and a second conical surface segment, the second conical surface segment being connected to the first conical surface segment, and the second venturi expansion surface portion comprises a single conical surface segment, wherein a first plurality of oxidant outlet ports are arranged as a first row of oxidant outlet ports around a periphery of the first conical surface segment, and a second plurality of oxidant outlet ports are arranged as a second row of oxidant outlet ports around a periphery of the second conical surface segment, wherein a third plurality of oxidant outlet ports are arranged on said single conical surface segment of said second venturi expansion surface portion as a third plurality of rows of oxidant outlet ports, and The number of rows of the third plurality of oxidant outlet ports is greater than the number of rows of the first plurality of oxidant outlet ports and greater than the number of rows of the second plurality of oxidant outlet ports.

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