Patent Description:
Turbomachines are utilized in a variety of industries and applications for energy transfer purposes. For example, a gas turbine engine generally includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section progressively increases the pressure of a working fluid entering the gas turbine engine and supplies this compressed working fluid to the combustion section. The compressed working fluid and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected, e.g., to a generator to produce electricity. The combustion gases then exit the gas turbine via the exhaust section.

Generally, the combustion section includes one or more fuel nozzles for mixing and injecting gaseous fuel and air into a combustion chamber. Additionally, the combustion section often includes one or more liquid fuel cartridges for mixing and injecting a separate stream of liquid fuel and air into the combustion section, such that the combustion section may operate only with gaseous fuel, only with liquid fuel or simultaneously with gaseous fuel and liquid fuel. In many cases, a power plant can experience long periods of time requiring it to run on liquid fuel only.

Liquid fuel cartridges often include liquid fuel cartridge tips or pilot tips having complex geometries that increase the efficiency of the combustion section. For example, liquid fuel cartridge tips often include multiple injection outlets and premixing chambers that result in richer and more complete burning of the liquid fuel and air within the combustion section.

However, issues exist with the use of many known cartridge tips. For example, transient and steady state thermal stresses can arise within the cartridge tip during liquid fuel operation that can damage the component over time. Thus, an improved cartridge tip is desired in the art. Particularly, an improved cartridge tip, that is capable of having multiple injection outlets and premixing functions without being susceptible to damaging thermal stresses, is desired. <CIT> suggests a combustion system that includes a head end comprising a liquid fuel cartridge. The liquid fuel cartridge has liquid fuel injection ports and is configured to produce combustion products via a diffusion flame. A liner is configured to deliver the combustion products from the head end to an aft frame, and an injector having an outlet is located along the liner between the head end and the aft frame. The injector outlet delivers a stream of oxidant inwardly into the liner, such that a mixedness and a velocity of the combustion products are increased prior to the combustion products reaching the aft frame.

The herein claimed invention relates to the subject matter set forth in the claims. Aspects and advantages of the cartridge tips and turbomachines in accordance with the present disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the technology.

Further, a combustor comprising a cartridge as set forth above is provided.

These and other features, aspects and advantages of the present cartridge tips and combustors will become better understood with reference to the following description and appended claims.

A full and enabling disclosure of the present cartridge tips and turbomachines, including the best mode of making and using the present systems and methods, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:.

Reference now will be made in detail to embodiments of the present cartridge tips and turbomachines, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, rather than limitation of, the technology. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope or spirit of the claimed technology. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

The term "fluid" may be a gas or a liquid. The term "fluid communication" means that a fluid is capable of making the connection between the areas specified.

As used herein, the terms "upstream" (or "forward") and "downstream" (or "aft") refer to the relative direction with respect to fluid flow in a fluid pathway. However, the terms "upstream" and "downstream" as used herein may also refer to a flow of electricity. The term "radially" refers to the relative direction that is substantially perpendicular to an axial centerline of a particular component, the term "axially" refers to the relative direction that is substantially parallel and/or coaxially aligned to an axial centerline of a particular component and the term "circumferentially" refers to the relative direction that extends around the axial centerline of a particular component.

Terms of approximation, such as "about," "approximately," "generally," and "substantially," are not to be limited to the precise value specified. For example, the approximating language may refer to being within a <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent margin in either individual values, range(s) of values and/or endpoints defining range(s) of values. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, "generally vertical" includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive- or and not to an exclusive- or.

Referring now to the drawings, <FIG> illustrates a schematic diagram of one embodiment of a turbomachine, which in the illustrated embodiment is a gas turbine <NUM>. Although an industrial or land-based gas turbine is shown and described herein, the present disclosure is not limited to a land-based and/or industrial gas turbine unless otherwise specified in the claims. For example, the invention as described herein may be used in any type of turbomachine including but not limited to a steam turbine, an aircraft gas turbine, or a marine gas turbine.

As shown, gas turbine <NUM> generally includes an inlet section <NUM>, a compressor section <NUM> disposed downstream of the inlet section <NUM>, a plurality of combustors <NUM> (<FIG>) within a combustor section <NUM> disposed downstream of the compressor section <NUM>, a turbine section <NUM> disposed downstream of the combustor section <NUM>, and an exhaust section <NUM> disposed downstream of the turbine section <NUM>. Additionally, the gas turbine <NUM> may include one or more shafts <NUM> coupled between the compressor section <NUM> and the turbine section <NUM>.

The compressor section <NUM> may generally include a plurality of rotor disks <NUM> (one of which is shown) and a plurality of rotor blades <NUM> extending radially outwardly from and connected to each rotor disk <NUM>. Each rotor disk <NUM> in turn may be coupled to or form a portion of the shaft <NUM> that extends through the compressor section <NUM>.

The turbine section <NUM> may generally include a plurality of rotor disks <NUM> (one of which is shown) and a plurality of rotor blades <NUM> extending radially outwardly from and being interconnected to each rotor disk <NUM>. Each rotor disk <NUM> in turn may be coupled to or form a portion of the shaft <NUM> that extends through the turbine section <NUM>. The turbine section <NUM> further includes an outer casing <NUM> that circumferentially surrounds the portion of the shaft <NUM> and the rotor blades <NUM>, thereby at least partially defining a hot gas path <NUM> through the turbine section <NUM>.

During operation, a working fluid such as air flows through the inlet section <NUM> and into the compressor section <NUM> where the air is progressively compressed, thus providing pressurized or compressed air <NUM> to the combustors of the combustor section <NUM>. The compressed air <NUM> is mixed with fuel and burned within each combustor to produce combustion gases <NUM>. The combustion gases <NUM> flow through the hot gas path <NUM> from the combustor section <NUM> into the turbine section <NUM>, wherein energy (kinetic and/or thermal) is transferred from the combustion gases <NUM> to the rotor blades <NUM>, causing the shaft <NUM> to rotate. The mechanical rotational energy may then be used to power the compressor section <NUM> and/or to generate electricity. The combustion gases <NUM> exiting the turbine section <NUM> may then be exhausted from the gas turbine <NUM> via the exhaust section <NUM>.

<FIG> illustrates a cross sectional view of a combustor <NUM> in the plurality of combustors <NUM>, in accordance with embodiments of the present disclosure. As shown, the combustor <NUM> defines a cylindrical coordinate system. For example, the combustor <NUM> defines an axial direction A, a radial direction R, and a circumferential direction C. In general, the axial direction A extends parallel to an axial centerline <NUM> of the combustor <NUM>, the radial direction R extends generally orthogonal to the axial centerline <NUM>, and the circumferential direction C extends generally concentrically around the axial centerline <NUM>.

As shown, the combustor <NUM> includes a liner <NUM> that contains and conveys combustion gases <NUM> to the turbine. The liner <NUM> may define a combustion chamber <NUM> within which combustion occurs. The liner <NUM> may have a cylindrical liner portion and a tapered transition portion that is separate from the cylindrical liner portion, as in many conventional combustion systems. Alternately, the liner <NUM> may have a unified body (or "unibody") construction, in which the cylindrical portion and the tapered portion are integrated with one another. Thus, any discussion herein of the liner <NUM> is intended to encompass both conventional combustion systems having a separate liner and transition piece and those combustion systems having a unibody liner. Moreover, the present disclosure is equally applicable to those combustion systems in which the transition piece and the stage one nozzle of the turbine are integrated into a single unit, sometimes referred to as a "transition nozzle" or an "integrated exit piece.

In many embodiments, the liner <NUM> may be surrounded by an outer sleeve <NUM>, which is spaced radially outward of the liner <NUM> to define an annulus <NUM> between the liner <NUM> and the outer sleeve <NUM>. The outer sleeve <NUM> may include a flow sleeve portion at the forward end and an impingement sleeve portion at the aft end, as in many conventional combustion systems. Alternately, the outer sleeve <NUM> may have a unified body (or "unisleeve") construction, in which the flow sleeve portion and the impingement sleeve portion are integrated with one another in the axial direction. As before, any discussion herein of the outer sleeve <NUM> is intended to encompass both conventional combustion systems having a separate flow sleeve and impingement sleeve and combustion systems having a unisleeve outer sleeve.

The combustor <NUM> may further include a head end portion <NUM> that is located upstream from the combustion zone and that surrounds a plurality of fuel nozzles <NUM> (e.g. circumferentially arranged outer fuel nozzles that surround a center fuel nozzle). For example, the head end portion <NUM> may be defined between an end cover <NUM> and a cap plate <NUM> of the combustor <NUM>. The end cover <NUM> may generally cover the forward end of the combustor <NUM> and may include a forward surface <NUM> and an aft surface <NUM>.

In many embodiments, a plurality of fuel nozzles <NUM> may include outer fuel nozzles circumferentially spaced apart from one another and surrounding a center fuel nozzle within the head end portion <NUM>. The fuel nozzles <NUM> may each extend between the end cover <NUM> and the cap plate <NUM>. For example, the fuel nozzles <NUM> may each extend from a respective flange <NUM> coupled to the aft surface <NUM> of the end cover <NUM>, through the cap plate <NUM>, to a respective outlet disposed in the combustion chamber <NUM>. As described below, the fuel nozzles <NUM> shown in <FIG> may be swirler fuel nozzles, bundled tube fuel nozzles, or any other suitable fuel nozzle.

In exemplary embodiments, the combustor <NUM> may include one or more liquid fuel cartridges <NUM> (e.g. an outer liquid fuel cartridge and/or a center liquid fuel cartridge). For example, the one or more liquid fuel cartridges <NUM> may be at least partially disposed within the head end portion <NUM> of the combustor <NUM>. In particular, each liquid fuel cartridge <NUM> in the one or more liquid fuel cartridges <NUM> may extend through a respective fuel nozzle <NUM>, such that the ratio of fuel nozzles <NUM> to liquid fuel cartridges <NUM> is <NUM>:<NUM>. In other embodiments, the ratio of fuel nozzles <NUM> to liquid fuel cartridges <NUM> may be greater than or less than <NUM> (such that there may be more fuel nozzles than liquid fuel cartridges or vice versa). In many embodiments, each liquid fuel cartridge <NUM> may extend coaxially with a respective fuel nozzle <NUM>.

In many embodiments, each liquid fuel cartridge <NUM> of the one or more liquid fuel cartridges <NUM> may extend from a respective flange <NUM> coupled to the end cover <NUM>, through a respective fuel nozzle <NUM> of the plurality of fuel nozzles <NUM>, to a cartridge tip <NUM>. For example, the flange <NUM> of the liquid fuel cartridge <NUM> may couple to the forward surface <NUM> of the end cover <NUM> (opposite the flange <NUM> of the fuel nozzles <NUM>). As discussed further below, cartridge tip <NUM> may be configured to inject liquid fuel within the combustion chamber <NUM>.

As shown in <FIG>, the liquid fuel cartridge(s) <NUM> may be fluidly coupled to a liquid fuel supply <NUM>, such that the liquid fuel cartridges convey liquid fuel through the head end portion <NUM> to the combustion chamber <NUM>. As shown, the liquid fuel supply <NUM> may be fluidly coupled to the liquid fuel cartridges <NUM> via a liquid fuel supply line <NUM>. In many embodiments, the pure liquid fuel may be supplied from the liquid fuel supply <NUM> to the liquid fuel cartridges <NUM> and/or <NUM> for injection into the combustion chamber <NUM>. In other embodiments, the liquid fuel cartridges <NUM> and/or <NUM> may be supplied with a liquid fuel mixture (such as a mixture of pure liquid fuel and water) from the liquid fuel supply <NUM>. The liquid fuel mixture may originate from a liquid fuel supply system (such as a mixing tank) within which liquid fuel and water are mixed and delivered to the liquid fuel cartridges <NUM> via the liquid fuel supply line <NUM>. As discussed below in more detail, the cartridge tip <NUM> described herein may include one or more fluid circuits, each of which may be operable to receive a separate supply of fuel from the liquid fuel supply <NUM>. For example, a first fluid circuit of the cartridge tip <NUM> may be operable to receive a flow of pure fuel from the liquid fuel supply <NUM>, while a second fuel circuit may be operable to separately receive a flow of liquid fuel and water (or vice versa).

In many embodiments, as shown in <FIG>, the fuel nozzles <NUM> may be fluidly coupled to a gaseous fuel supply <NUM> via a gaseous fuel supply line <NUM>. In this way, each of the fuel nozzles <NUM> may be in fluid communication with the gaseous fuel supply <NUM>, such that the fuel nozzles <NUM> convey gaseous fuel from the gaseous fuel supply <NUM>, through the head end portion <NUM>, to the combustion chamber <NUM>. The gaseous fuel may be mixed with compressed air <NUM> within the fuel nozzles <NUM> prior to injection into the combustion chamber <NUM> by the fuel nozzles <NUM>. The fuel nozzles <NUM> may be swirler fuel nozzles bundled tube fuel nozzles or any other suitable fuel nozzle.

In many embodiments, the combustor <NUM> may be at least partially surrounded by a forward casing <NUM> such as a compressor discharge casing. The forward casing <NUM> may at least partially define a high-pressure plenum <NUM> that at least partially surrounds various components of the combustor <NUM>. The high-pressure plenum <NUM> may be in fluid communication with the compressor section <NUM> (<FIG>) so as to receive compressed air <NUM> therefrom. In various embodiments, the forward casing <NUM> may be fluidly connected to an outlet of the compressor section <NUM>. Compressed air <NUM> may flow from the high-pressure plenum <NUM> into the annulus <NUM> at an aft end of the combustor <NUM>, via openings defined in the outer sleeve <NUM>. Because the annulus <NUM> is fluidly coupled to the head end portion <NUM>, the compressed air <NUM> travels upstream from the aft end of the combustor <NUM> to the head end portion <NUM>, where the compressed air <NUM> reverses direction and enters the fuel nozzles <NUM>. For example, the air <NUM> may travel through the annulus <NUM> in the opposite direction of the combustion gases <NUM> within the liner <NUM>.

The combustion gases <NUM>, which are produced by combusting gaseous fuel and/or liquid fuel with compressed air <NUM>, travel downstream toward an aft frame <NUM> of the combustor <NUM>, the aft frame <NUM> representing an aft end of the combustor <NUM>. In many embodiments, the aft frame <NUM> may be connected to the turbine section <NUM>, such that the combustion gases <NUM> may exit the combustor <NUM> at the aft frame <NUM> and enter the turbine section <NUM>.

<FIG> illustrates cross-sectional views of a combustor <NUM> from within the combustion chamber <NUM>. As shown, the liquid fuel cartridges <NUM> may be installed coaxially with the plurality of fuel nozzles <NUM>. Although six fuel nozzles <NUM> are shown (e.g. five outer fuel nozzles and one center fuel nozzle), it should be understood that other numbers of fuel nozzles <NUM> may be employed (such as <NUM>, <NUM>, <NUM>, or <NUM> fuel nozzles <NUM>). Each of the fuel nozzles <NUM> and the liquid fuel cartridges <NUM> may extend through a respective opening defined in the cap plate <NUM> and into the combustion chamber <NUM>.

As should be appreciated, the combustor <NUM> may include any type of fuel nozzle <NUM>. For example, although a swirling fuel nozzle or "swozzle" is shown in <FIG>, the combustor <NUM> may also employ bundled tube fuel nozzles or other suitable fuel nozzles.

As shown in <FIG>, each fuel nozzle <NUM> may include a corresponding liquid fuel cartridge <NUM> extending coaxially therethrough. In such embodiments, both the outer fuel nozzles and the center fuel nozzle may include a respective liquid fuel cartridge <NUM> extending therethrough. However, in other embodiments only the center fuel nozzle may include a liquid fuel cartridge <NUM> extending therethrough, such that the liquid fuel cartridge <NUM> may be a singular liquid fuel cartridge that extends coaxially with both the center fuel nozzle and the combustor <NUM>. In yet still further embodiments, only one or more of the outer fuel nozzles may include a liquid fuel cartridge extending therethrough, such that the center fuel nozzle does not include a liquid fuel cartridge in some embodiments.

<FIG> illustrates a liquid fuel cartridge <NUM> having a cartridge tip <NUM>, in accordance with embodiments of the present disclosure. As shown, the liquid fuel cartridge <NUM> may include a flange <NUM>, a body <NUM>, and a cartridge tip <NUM>. The flange <NUM> may define an inlet <NUM> that receives the liquid fuel (or a liquid fuel and water mixture) from the liquid fuel supply <NUM> (<FIG>). As discussed above, the flange <NUM> may couple the liquid fuel cartridge <NUM> to the end cover <NUM> (such as the forward surface <NUM> of the end cover <NUM>). The body <NUM> of the liquid fuel cartridges may extend from the flange <NUM>, through a respective fuel nozzle <NUM> (<FIG>), to cartridge tip <NUM>. In many embodiments, the body <NUM> of the liquid fuel cartridge may be generally cylindrical.

In various embodiments, the cartridge tip <NUM> may each extend directly from the body <NUM> of the liquid fuel cartridge <NUM>. The cartridge tip <NUM> may be positioned either partially or entirely within the combustion chamber <NUM> (<FIG>). In particular embodiments, the cartridge tip <NUM> may extend axially from a base <NUM> coupled to the body <NUM> of the liquid fuel cartridge to a tip <NUM>. In this way, the base <NUM> may be the axially innermost portion of the cartridge tip <NUM>, and the tip may be the axially outermost portion of the cartridge tip <NUM>.

The cartridge tip <NUM> may generally converge radially inward from the base <NUM> to the tip <NUM>. In various embodiments, as shown best in <FIG>, the cartridge tip <NUM> may be disposed entirely within the combustion chamber <NUM> and terminate at the tip <NUM>, which is positioned downstream from the cap plate <NUM>. In many embodiments, the cartridge tip <NUM> may define an axial centerline <NUM>, which may be generally parallel to the axial centerline <NUM> of the combustor <NUM> (shown in <FIG>).

<FIG> illustrates a perspective view of the cartridge tip <NUM>, and <FIG> illustrates a cross-sectional view of the cartridge tip <NUM> from along the line <NUM>-<NUM> shown in <FIG>, in accordance with embodiments of the present disclosure.

In many embodiments, as shown in <FIG> and <FIG>, the cartridge tip <NUM> may include a main body <NUM> extending from the base <NUM>, along the axial centerline <NUM>, to the tip <NUM>. The main body <NUM> may include an outer annular wall <NUM> and an inner core <NUM> each extending between a respective upstream end <NUM>, <NUM> and a respective downstream end <NUM>, <NUM>.

The cartridge tip <NUM> may define multiple separate fuel circuits capable of operation together, in any combination, or independently. For example, as discussed below in detail, the cartridge tip <NUM> may define a pilot fuel circuit <NUM> and a main fuel circuit <NUM>. Each fuel circuit (e.g., the pilot fuel circuit <NUM> and the main fuel circuit <NUM>) defined in the cartridge tip <NUM> may be capable of separately receiving a flow of liquid fuel (such as only liquid fuel or a liquid fuel and water mixture) from the liquid fuel supply <NUM>. Additionally, an annular air passage <NUM> may supply a flow of purge air through the cartridge tip <NUM>.

In many embodiments, the outer annular wall <NUM> may generally converge (or taper) radially inward in the axial direction A (or downstream direction). In such embodiments, the outer annular wall <NUM> may include one or more converging, tapered, or otherwise slanted portions with respect to the axial centerline <NUM> of the cartridge tip <NUM>. For example, the outer annular wall <NUM> may include a first cylindrical portion <NUM>, a converging mid portion <NUM> (or tapered mid portion) downstream from the first cylindrical portion <NUM>, a second cylindrical portion <NUM> downstream from the converging mid portion <NUM>, and a converging aft portion <NUM> (or tapered aft portion) downstream from the second cylindrical portion <NUM> and upstream from the aft end <NUM> of the outer annular wall <NUM>. The various portions of the outer annular wall <NUM> collectively form an aerodynamic profile or contoured exterior surface of the cartridge tip <NUM>. Additionally, the converging portions <NUM> and <NUM> advantageously provide both for flow metering and increased mixing within the cartridge tip <NUM>.

In exemplary embodiments, the inner core <NUM> may be radially spaced apart from the outer annular wall <NUM> such that an annular air passage <NUM> is defined at least partially between the outer annular wall <NUM> and the inner core <NUM>. For example, the annular air passage <NUM> may circumferentially surround the inner core <NUM> and be bound between the outer annular wall <NUM> and the inner core <NUM>. In many embodiments, the annular air passage <NUM> may extend between the outer annular wall <NUM> and the inner core <NUM> for the entire axial length of the cartridge tip <NUM>. In particular, the annular air passage <NUM> may be directly bound between a radially inner surface of the outer annular wall <NUM> and a radially outer surface of the inner core <NUM>. In exemplary embodiments, the annular air passage <NUM> may extend from to each of an annular inlet <NUM>, a first plurality of outlets <NUM>, a second plurality of outlets <NUM>, and a central outlet <NUM>.

As shown, the annular inlet <NUM> may be defined between the outer annular wall <NUM> and the inner core <NUM> at the respective upstream end <NUM> of the inner core <NUM>. In exemplary embodiments, the first plurality of outlets <NUM> may be defined within the second cylindrical portion <NUM> of the outer annular wall <NUM>. In such embodiments, each outlet <NUM> in the first plurality of outlets <NUM> may be oriented such that it ejects a discrete jet (or spray) of air generally radially. In other embodiments (not shown), the first plurality of outlets <NUM> may be defined along any portion of the outer annular wall <NUM> upstream of the second plurality of outlets <NUM>, such as the first cylindrical portion <NUM> and/or the converging mid portion <NUM>. In many embodiments, the second plurality of outlets <NUM> may be defined in one or both of the second cylindrical portion <NUM> and the converging aft portion <NUM> of the outer annular wall <NUM>. In various embodiments, the second plurality of outlets <NUM> may be disposed downstream from the first plurality of outlets <NUM>.

As discussed below in more detail, each outlet <NUM> in the second plurality of outlets <NUM> of the annular air passage <NUM> may be both radially and axially spaced apart from, but may circumferentially align with, a respective outlet <NUM> of a plurality of main outlets <NUM> of a main fuel circuit <NUM> defined within the inner core <NUM> of the cartridge tip <NUM>. The central outlet <NUM> may be defined in the converging aft portion <NUM> of the outer annular wall <NUM> downstream from the second plurality of outlets <NUM>. For example, the central outlet <NUM> may be a single, circularly shaped, outlet having a center point along the axial centerline <NUM> of the cartridge tip <NUM>. In many embodiments, the central outlet <NUM> may be both the largest outlet of the cartridge tip <NUM> and the downstream-most outlet of the annular air passage <NUM>.

As shown in in <FIG>, according to the herein claimed invention, the cartridge tip <NUM> further includes a heat shield <NUM> that extends radially inward from the outer annular wall into the annular air passage <NUM>. The heat shield <NUM> extends annularly from the outer annular wall <NUM>, within the annular air passage, to a free end <NUM>. In various embodiments, the heat shield may include a radially extending portion <NUM> and an axially extending portion <NUM>. The radially extending portion <NUM> may extend from the outer annular wall <NUM> to the axially extending portion <NUM>. The axially extending portion <NUM> may extend from the radially extending portion <NUM> to the free end <NUM>. The axially extending portion <NUM> of the heat shield <NUM> is radially spaced apart from both the outer annular wall (such as an interior surface of the outer annular wall) and the inner core (such as an exterior surface of the inner core), such that the heat shield may at least partially divide the annular air passage <NUM> into a downstream-flowing portion <NUM> and an upstream flowing portion <NUM>.

Air within the downstream-flowing portion <NUM> of the annular air passage <NUM> may flow in the downstream or axial direction A, and air within the upstream-flowing portion <NUM> of the annular air passage <NUM> may flow in the upstream direction (opposite the axial direction A). The upstream-flowing portion <NUM> of the annular air passage <NUM> is disposed between the heat shield <NUM> and the outer annular wall <NUM>. The downstream-flowing portion <NUM> of the annular air passage <NUM> is disposed between the heat shield <NUM> and the inner core <NUM>. For example, the annular heat shield <NUM> may extend within the annular air passage <NUM> from a coupled end disposed on the outer annular wall <NUM> to the free end <NUM> downstream from the coupled end, such that the downstream-flowing portion <NUM> of the annular air passage <NUM> extends on a first side of the heat shield <NUM> and the upstream-flowing portion <NUM> of the annular air passage <NUM> extends on a second side of the heat shield <NUM>. In exemplary implementations, the heat shield <NUM> provides an additional conductive heat transfer path, which advantageously reduces the thermal gradients experienced by the cartridge tip <NUM> thereby lengthening hardware life.

In many embodiments, the cartridge tip <NUM> may further include a circumferential rib <NUM> that extends radially outward from the inner core <NUM> and into the downstream-flowing portion <NUM> of the annular air passage <NUM>. The circumferential rib may advantageously prevent a backflow of air within the downstream-flowing portion <NUM> of the annular air passage <NUM>. The circumferential rib <NUM> may be disposed axially within the downstream-flowing portion <NUM> of the annular air passage <NUM> (e.g., at the axial location of the axial portion <NUM> of the heat shield <NUM>). In many embodiments, the circumferential rib <NUM> may have a generally frustoconical shaped cross-sectional shape, such that it advantageously acts as a nozzle (such as a venturi nozzle) that prevents air backflow. For example, the circumferential rib <NUM> may extend radially from the exterior surface of the inner core <NUM> towards the heat shield <NUM> (but may be radially spaced apart from the heat shield <NUM>).

As shown in <FIG>, the inner core <NUM> may further define a pilot fuel circuit <NUM> and a main fuel circuit <NUM>. The pilot fuel circuit <NUM> may extend between a pilot inlet <NUM> defined in the upstream end <NUM> of the inner core <NUM> and a pilot outlet <NUM> defined in the downstream end <NUM> of the inner core <NUM>. In many embodiments, the pilot fuel circuit <NUM> may extend at least partially along the axial centerline <NUM> of the cartridge tip <NUM>. For example, the pilot fuel circuit <NUM> may include (e.g., in a serial flow order) an inlet portion <NUM>, an annular portion <NUM>, a plurality of tangential passages <NUM>, and an aft plenum <NUM>.

In exemplary embodiments, the inlet portion <NUM> may extend from the pilot inlet <NUM> to the annular portion <NUM>. As shown in <FIG>, at least a portion of the inlet portion <NUM> may extend along the axial centerline <NUM>. The plurality of tangential passages <NUM> may extend between the annular portion <NUM> and the aft plenum <NUM>. In many embodiments, a protrusion <NUM> may extend axially into the pilot fuel circuit <NUM> to form the annular portion <NUM> of the pilot fuel circuit <NUM>. As discussed below, the plurality of tangential passages <NUM> may each extend along a radially oriented plane in a direction angled to the radial direction R, such that a swirling flow is produced by the plurality of tangential passages <NUM> in the aft plenum <NUM>. The aft plenum <NUM> may generally converge radially as it extends axially from the outlets of the plurality of tangential passages <NUM> to the pilot outlet <NUM>. As shown, the pilot outlet <NUM> may be axially spaced apart (e.g., axially inward) of the aft end <NUM> of the outer annular wall <NUM>.

The main fuel circuit <NUM> may be defined within inner core <NUM> of the main body <NUM>. The main fuel circuit <NUM> may extend between a main inlet <NUM> in the upstream end <NUM> of the inner core <NUM> and a plurality of main outlets <NUM>. The plurality of main outlets <NUM> may be circumferentially spaced apart from one another and disposed upstream from the pilot outlet <NUM>. For example, the plurality of main outlets <NUM> may be disposed both radially and axially inward of the second plurality of outlets of the <NUM>. In particular, each main outlet <NUM> of the plurality of main outlets <NUM> of the main fuel circuit <NUM> may be circumferentially aligned (e.g., disposed on a common injection axis) with a respective second outlet <NUM> of the plurality of second outlets <NUM> of the annular air passage <NUM>.

In exemplary embodiments, the main fuel circuit <NUM> may include, in a serial flow order, an inlet portion <NUM>, an annular plenum <NUM>, and a plurality of circumferentially spaced passages <NUM>. The inlet portion <NUM> may extend from the main inlet <NUM> and include a first branch <NUM> and a second branch <NUM>. In many embodiments, the inlet portion <NUM> may extend between the main inlet <NUM> and the annular plenum <NUM>. In particular, the annular plenum <NUM> may fluidly coupled to the first branch <NUM> and the second branch <NUM> of the inlet portion <NUM>. In this way, the inlet portion <NUM> may supply a flow of fuel to the annular plenum <NUM> via both the first branch <NUM> and the second branch <NUM>, which advantageously uniformly distributes the fuel within the annular plenum <NUM>. In particular, the outlet of the first branch <NUM> and the second branch <NUM> may be disposed opposite from one another in the annular plenum <NUM> to uniformly distribute fuel. The plurality of circumferentially spaced passages <NUM> may each extend from the annular plenum <NUM> to a respective main outlet <NUM> of the plurality of main outlets <NUM>. The plurality of circumferentially spaced passages <NUM> may extend generally axially from the annular plenum <NUM> towards the plurality of main outlets <NUM>.

<FIG> illustrate different cross-sectional views of the cartridge tip <NUM> from along various positions of the axial centerline <NUM>, as indicated by the cross-section lines in <FIG>. For example, <FIG> illustrates a cross-sectional view of the cartridge tip <NUM> from along the line <NUM>-<NUM> shown in <FIG>. <FIG> illustrates a cross-sectional view of the cartridge tip <NUM> from along the line <NUM>-<NUM> shown in <FIG>. <FIG> illustrates a cross-sectional view of the cartridge tip <NUM> from along the line <NUM>-<NUM> shown in <FIG>. <FIG> illustrates a cross-sectional view of the cartridge tip <NUM> from along the line <NUM>-<NUM> shown in <FIG>.

As shown in <FIG> and <FIG>, the cartridge tip <NUM> may include one or more struts <NUM> that couple the outer annular wall <NUM> to the inner core <NUM>. In exemplary embodiments, the cartridge tip <NUM> may only include two struts <NUM> diametrically opposed to one another (e.g., about <NUM>° apart in the circumferential direction C) and extending radially from the outer annular wall <NUM> to the inner core <NUM>. However, in other embodiments, the cartridge tip <NUM> may include any number of struts <NUM> (such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, up to <NUM> or more) and should not be limited to any specific number of struts <NUM> unless specifically recited in the claims. In many embodiments, the one or more struts <NUM> may be disposed in the annular air passage <NUM> immediately downstream from the annular inlet <NUM>, such that the struts <NUM> are proximate the upstream end of the cartridge tip <NUM>. In exemplary embodiments, outer annular wall <NUM> may couple to the inner core <NUM> only by the one or more struts <NUM>, such that the inner core is rigidly suspended within the outer annular wall <NUM> by the one or more struts <NUM>.

As shown in <FIG> and <FIG>, the annular air passage <NUM> may be disposed radially outward from both the pilot fuel circuit <NUM> and the main fuel circuit <NUM>. Additionally, in many embodiments, the annular plenum <NUM> of the main fuel circuit <NUM> may surround the pilot fuel circuit <NUM>. In particular, the annular plenum <NUM> of the main fuel circuit <NUM> may entirely circumferentially surround the inlet portion <NUM> of the pilot fuel circuit <NUM>. In exemplary embodiments, as shown, the first branch <NUM> and the second branch <NUM> of the main fuel circuit <NUM> may each separately fluidly couple to the annular plenum <NUM>. For example, the first branch <NUM> and the second branch <NUM> may fluidly couple to the annular plenum <NUM> on opposite sides (e.g., diametrically opposed to one another) of the pilot fuel circuit <NUM>, thereby equally distributing fuel to the annular plenum <NUM> during operation for higher combustion efficiency.

As shown in <FIG> and <FIG>, the plurality of circumferentially spaced passages <NUM> may each extend from the annular plenum <NUM> to a respective main outlet <NUM> of the plurality of main outlets <NUM>. The plurality of circumferentially spaced passages <NUM> may extend generally axially from the annular plenum <NUM> towards the plurality of main outlets <NUM>. In exemplary embodiments, each circumferentially spaced passage <NUM> of the plurality of circumferentially spaced passages <NUM> may be operable to eject a discrete flow of fuel into the combustor <NUM> during operation thereof. Each of the plurality of circumferentially spaced passages <NUM> may be disposed radially outward from the pilot fuel circuit <NUM> and may extend generally axially through the inner core <NUM>. Although <FIG> illustrates an embodiment of a cartridge tip <NUM> having eight circumferentially spaced passages <NUM>, the cartridge tip <NUM> may include any number of circumferentially spaced passages (such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or up to <NUM> or more).

The cartridge tip <NUM> may advantageously have a more solid structure as compared to prior designs, which favorably increases the amount of conductive heat transfer paths and minimizes high thermal stress zones within the cartridge tip <NUM>. For example, the amount of material (e.g., metal) used to form the cartridge tip may be expressed by a ratio between material volume (e.g., the amount of physical material present in the cartridge tip <NUM> component) and total part volume (e.g., the total volume of the cartridge tip <NUM> calculated using an exterior profile of the cartridge tip <NUM>). In particular, the ratio of material volume to total volume may be between about <NUM> and about <NUM>, such as between about <NUM> and about <NUM>, such as about <NUM>.

As shown in <FIG> and <FIG>, each tangential passage of the plurality of tangential passages <NUM> may extends from the annular portion <NUM> to the aft plenum <NUM>. In exemplary embodiments, each of the tangential passages <NUM> of the plurality of tangential passages <NUM> extend at least partially tangentially from the aft plenum <NUM> along a radial plane such that the plurality of tangential passages <NUM> is operable to induce a swirling flow of fuel within the aft plenum <NUM> upstream from the pilot outlet <NUM>. For example, the cross-sectional shape of the aft plenum <NUM> may be generally circular, and each of the tangential passages <NUM> may extend at least partially tangentially from the circular shape of the aft plenum <NUM>. In other words, each of the tangential passages may extend along a radial plane in a direction angled, sloped, and/or slanted with respect to the radial direction R. In this way, the tangential passages <NUM> advantageously produce a swirling flow of fuel within the aft plenum <NUM> during operation of the cartridge tip <NUM>, thereby resulting in a more complete combustion of the fuel within the combustion chamber.

In many embodiments, the cartridge tip <NUM> may be integrally formed. For example, the cartridge tip <NUM> described herein may be integrally formed as a single component. That is, each of the subcomponents, e.g., the outer annular wall <NUM>, the inner core <NUM>, and all of the various voids, gaps and passages, may be manufactured together as a single body. In exemplary embodiments, this may be done by utilizing an additive manufacturing system and method, such as direct metal laser sintering (DMLS), direct metal laser melting (DMLM), or other suitable additive manufacturing techniques. In other embodiments, other manufacturing techniques, such as casting or other suitable techniques, may be used. In this regard, by utilizing additive manufacturing methods, the cartridge tip <NUM> may be integrally formed as a single piece of continuous metal and may thus include fewer sub-components and/or joints compared to prior designs. The integral formation of the cartridge tip <NUM> through additive manufacturing may advantageously improve the overall assembly process. For example, the integral formation reduces the number of separate parts that must be assembled, thus reducing associated time and overall assembly costs. Additionally, existing issues with, for example, leakage, joint quality between separate parts, and overall performance may advantageously be reduced. Further, the integral formation of the cartridge tip <NUM> may favorably reduce the weight of the cartridge tip <NUM> as compared to other manufacturing methods.

Claim 1:
A cartridge tip (<NUM>) for a liquid fuel cartridge (<NUM>) of a gas turbine combustor (<NUM>) the cartridge tip (<NUM>) comprising:
a main body (<NUM>) comprising an outer annular wall (<NUM>) and an inner core (<NUM>) each extending between a respective upstream end (<NUM>, <NUM>) and a respective downstream end (<NUM>, <NUM>), the inner core (<NUM>) radially spaced apart from the outer annular wall (<NUM>) such that an annular air passage (<NUM>) is defined at least partially between the outer annular wall (<NUM>) and the inner core (<NUM>);
a pilot fuel circuit (<NUM>) defined in the inner core (<NUM>) of the main body (<NUM>), the pilot fuel circuit (<NUM>) extending between a pilot inlet (<NUM>) defined in the upstream end (<NUM>) of the inner core (<NUM>) and a pilot outlet (<NUM>) defined in the downstream end (<NUM>) of the inner core (<NUM>), wherein the pilot fuel circuit (<NUM>) extends at least partially along an axial centerline (<NUM>) of the cartridge tip (<NUM>); and
a main fuel circuit (<NUM>) defined in the inner core (<NUM>) of the main body (<NUM>), the main fuel circuit (<NUM>) extending between a main inlet (<NUM>) in the upstream end (<NUM>) of the inner core (<NUM>) and a plurality of main outlets (<NUM>) circumferentially spaced apart from one another and disposed upstream from the pilot outlet (<NUM>), characterized in that an annular heat shield (<NUM>) extends from the outer annular wall (<NUM>) within the annular air passage (<NUM>) to a free end (<NUM>), wherein a downstream-flowing portion (<NUM>) of the annular air passage (<NUM>) is disposed between the heat shield (<NUM>) and the inner core (<NUM>), and wherein an upstream-flowing portion (<NUM>) of the annular air passage (<NUM>) is disposed between the heat shield (<NUM>) and the outer annular wall (<NUM>).