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.

In some combustors, the generation of combustion gases occurs at two, axially spaced stages. Such combustors are referred to herein as including an "axial fuel staging" (AFS) system, which delivers fuel and an oxidant to one or more fuel injectors downstream of the head end of the combustor. In a combustor with an AFS system, a primary fuel nozzle at an upstream end of the combustor injects fuel and air (or a fuel/air mixture) in an axial direction into a primary combustion zone, and an AFS fuel injector located at a position downstream of the primary fuel nozzle injects fuel and air (or a second fuel/air mixture) as a cross-flow into a secondary combustion zone downstream of the primary combustion zone. The cross-flow is generally transverse to the flow of combustion products from the primary combustion zone.

The AFS fuel injectors are typically supplied with fuel by one or more fluid conduits that extend generally axially along an outer sleeve of the combustor. In some instances, one or more components of the AFS system (such as the fuel conduits) may wear over time causing fuel to leak around the combustor. It is important that the leaked fuel be kept away from any high temperature components of the combustor in order to prevent auto ignition of the leaked fuel, which could damage or destroy components of the combustor.

Accordingly, an improved combustor having an AFS system that advantageously reduces risk of damage from leaked fuel would be desired in the art. <CIT> and <CIT> disclose a combustor showing all features of the preamble of claim <NUM>.

Aspects and advantages of the combustors 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.

In accordance with one embodiment, a combustor is provided. A combustor includes an end cover and a forward casing. The combustor further includes at least one fuel nozzle extending from the end cover and at least partially surrounded by the forward casing. A combustion liner extends between the at least one fuel nozzle and an aft frame. An outer sleeve spaced apart from and surrounding the combustion liner such that an annulus is defined therebetween. The combustion liner defines a combustion chamber having a primary combustion zone downstream from the at least one fuel nozzle and a secondary combustion zone downstream from the primary combustion zone. The combustor further includes a fuel injection assembly. The fuel injection assembly includes a fuel injector that extends through the outer sleeve, the annulus, and the combustion liner to the secondary combustion zone. A fuel supply conduit positioned outside of the outer sleeve. The fuel supply conduit extends to the fuel injector. The fuel injection assembly further includes a shielding assembly coupled to the outer sleeve and at least partially surrounding the fuel supply conduit. The shielding assembly includes a venturi nozzle having a circumferentially converging portion and a circumferentially diverging portion. At least one fuel sweep opening is defined in the outer sleeve immediately forward of the venturi nozzle and disposed within the shielding assembly.

In accordance with another embodiment, a turbomachine is provided. The turbomachine includes a compressor section, a turbine section, and a combustor. The combustor is disposed downstream from the compressor section and upstream from the turbine section. The combustor includes an end cover and a forward casing. The combustor further includes at least one fuel nozzle extending from the end cover and at least partially surrounded by the forward casing. A combustion liner extends between the at least one fuel nozzle and an aft frame. An outer sleeve spaced apart from and surrounding the combustion liner such that an annulus is defined therebetween. The combustion liner defines a combustion chamber having a primary combustion zone downstream from the at least one fuel nozzle and a secondary combustion zone downstream from the primary combustion zone. The combustor further includes a fuel injection assembly. The fuel injection assembly includes a fuel injector that extends through the outer sleeve, the annulus, and the combustion liner to the secondary combustion zone. A fuel supply conduit positioned outside of the outer sleeve. The fuel supply conduit extends to the fuel injector. The fuel injection assembly further includes a shielding assembly coupled to the outer sleeve and at least partially surrounding the fuel supply conduit. The shielding assembly includes a venturi nozzle having a circumferentially converging portion and a circumferentially diverging portion. At least one fuel sweep opening is defined in the outer sleeve immediately forward of the venturi nozzle and disposed within the shielding assembly.

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

A full and enabling disclosure of the present combustors 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 combustors 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 of the claimed technology For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims.

As used herein, the terms "upstream" and "downstream" refer to the relative direction with respect to fluid flow in a fluid pathway. The terms "forward" and "aft," without any further specificity, refer to directions, with "forward" referring to the front or compressor end of the gas turbine, and "aft" referring to the rearward section of the gas turbine.

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 "generally," or "about" include values within ten percent greater or less than the stated value. 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 counterclockwise.

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 (not shown) 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 air or compressed air <NUM> to the combustors <NUM> 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> is a schematic representation of a combustor <NUM>, as may be included in a can annular combustion system for the heavy-duty gas turbine <NUM>. In a can annular combustion system, a plurality of combustors <NUM> (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more) are positioned in an annular array about the shaft <NUM> that connects the compressor section <NUM> to the turbine section <NUM>.

As shown in <FIG>, the combustor <NUM> may define an axial direction A that extends along an axial centerline <NUM>. The combustor may also define a circumferential direction C which extends around the axial direction A and the axial centerline <NUM>. The combustor <NUM> may further define a radial direction R perpendicular to the axial direction A and the axial centerline <NUM>.

<FIG> illustrates a combustor <NUM> having one or more exemplary fuel injection assemblies <NUM> or (also referred to as an axial fuel staging (AFS) system), as discussed further herein. The combustor <NUM> includes a combustion liner <NUM> that defines a combustion chamber <NUM>. The combustion liner <NUM> is positioned within (i.e., circumferentially surrounded by) an outer sleeve <NUM>, such that an annulus <NUM> is formed therebetween. At least one fuel nozzle <NUM> is positioned at the forward end of the combustor <NUM>. Fuel <NUM> is directed through fuel supply lines <NUM>, which extend through an end cover <NUM>, and into the fuel nozzles <NUM>. The fuel nozzles <NUM> convey the fuel <NUM> and compressed air <NUM> into a primary combustion zone <NUM>, where combustion occurs. In some embodiments, the fuel <NUM> and compressed air <NUM> are combined as a mixture prior to reaching the primary combustion zone <NUM>.

The combustion liner <NUM> may contain and conveys combustion gases <NUM> to the turbine section <NUM>. The combustion liner <NUM> defines the combustion chamber <NUM> within which combustion occurs. As shown in <FIG>, the combustion liner may extend between the fuel nozzles <NUM> and an aft frame <NUM>. The combustion 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 combustion 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 of the combustion liner <NUM> herein 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.

The combustion liner <NUM> is surrounded by an outer sleeve <NUM>, which is spaced radially outward of the combustion liner <NUM> to define an annulus <NUM> between the combustion liner <NUM> and the outer sleeve <NUM>. In exemplary embodiments, the outer sleeve <NUM> may include a flow sleeve <NUM> at the forward end and an impingement sleeve <NUM> at the aft end. The flow sleeve <NUM> and the impingement sleeve <NUM> may be coupled to one another. For example, the flow sleeve <NUM> may include a first end or forward end that is coupled to the forward casing <NUM> and a second end or aft end that extends into and axially overlaps with a forward end of the impingement sleeve <NUM>, such that an interference fit is formed between the impingement sleeve <NUM> and the flow sleeve <NUM>. In many embodiments, the flow sleeve <NUM> extends between a forward casing <NUM> and the impingement sleeve <NUM>. As shown, the impingement sleeve may extend between the flow sleeve <NUM> and the aft frame <NUM> of the combustor <NUM>. Alternately, the outer sleeve <NUM> may have a unified body (or "unisleeve") construction, in which the flow sleeve <NUM> and the impingement sleeve <NUM> are integrated with one another in the axial direction. As before, any discussion of the outer sleeve <NUM> herein is intended to encompass both convention combustion systems having a separate flow sleeve <NUM> and impingement sleeve <NUM> and combustion systems having a unisleeve outer sleeve. However, in exemplary embodiments of the present disclosure, the combustor <NUM> includes a flow sleeve <NUM> and an impingement sleeve <NUM> as separate components coupled to one another.

The combustion liner <NUM> is surrounded by an outer sleeve <NUM>, thereby forming the annulus <NUM> therebetween through which compressed air <NUM> flows to the head end of the combustor <NUM>. Heat is transferred convectively from the combustion liner <NUM> to the compressed air <NUM>, thus cooling the combustion liner <NUM> and warming the compressed air <NUM>. The combustion liner <NUM> may be formed with an upstream liner component and a downstream transition component. The liner component may be generally cylindrical, while the transition component may taper from a cylindrical forward end to a generally rectangular aft end.

The forward casing <NUM> and the end cover <NUM> of the combustor <NUM> may define a head end air plenum <NUM> and that includes one or more fuel nozzles <NUM>. The fuel nozzles <NUM> may be any type of fuel nozzle, such as bundled tube fuel nozzles or swirler nozzles "swozzles. " For example, the fuel nozzles <NUM> are positioned within the head end air plenum <NUM> defined by the forward casing <NUM>. In many embodiments, the fuel nozzles <NUM> may extend from the end cover <NUM>. For example, each fuel nozzle <NUM> may be coupled to an aft surface of the end cover <NUM> via a flange (not shown). As shown in <FIG>, the at least one fuel nozzle <NUM> is partially surrounded by the combustion liner <NUM>. The aft, or downstream ends, of the fuel nozzles <NUM> extend through a cap <NUM> that defines the upstream end of the combustion chamber <NUM>.

The forward casing <NUM> is connected to a compressor discharge casing <NUM>, which defines a high pressure plenum <NUM> around the combustion liner <NUM> and the outer sleeve <NUM>. Compressed air <NUM> from the compressor section <NUM> travels through the high pressure plenum <NUM> and enters the combustor <NUM> via apertures (not shown) in the downstream end of the outer sleeve <NUM> (as indicated by arrows near an aft frame <NUM>). Compressed air travels upstream through the annulus <NUM> and are turned by the end cover <NUM> to enter the fuel nozzles <NUM> and to cool the head end. In particular, compressed air <NUM> flows from high pressure plenum <NUM> into the annulus <NUM> at an aft end of the combustor <NUM>, via openings defined in the outer sleeve <NUM>. The compressed air <NUM> travels upstream from the aft end of the combustor <NUM> to the head end air plenum <NUM>, where the compressed air <NUM> reverses direction and enters the fuel nozzles <NUM>.

A fuel injection assembly <NUM> is provided to deliver a second fuel/air mixture to a secondary combustion zone <NUM>. For example, a second flow of fuel and air may be introduced by one or more fuel injection assemblies <NUM> to the secondary combustion zone <NUM>. The secondary combustion zone <NUM> is defined by the combustion liner <NUM> and positioned downstream from the primary combustion zone <NUM>. Such a combustion system having axially separated combustion zones is described as an "axial fuel staging" (AFS) system. The fuel injection assemblies <NUM> may be circumferentially spaced apart from one another on the outer sleeve <NUM> (e.g., equally spaced apart in some embodiments). In many embodiments, the combustor <NUM> may include four fuel injection assemblies <NUM> spaced apart from one another and configured to inject a second mixture of fuel and air into a secondary combustion zone <NUM>, in order to increase the combustion gases <NUM> and temperature thereof. In other embodiments, the combustor <NUM> may include any number of fuel injection assemblies <NUM> (e.g., <NUM>, <NUM>, <NUM>, or up to <NUM>).

As shown in <FIG> each fuel injection assembly <NUM> includes a fuel injector <NUM> and a fuel supply conduit <NUM> that supplies fuel to the fuel injector <NUM> (e.g., gaseous fuel). Each fuel injector <NUM> extends through the outer sleeve <NUM>, the annulus <NUM>, and the combustion liner <NUM> and into the secondary combustion zone <NUM>. The fuel injectors <NUM> each extend radially from the high pressure plenum <NUM>, through the outer sleeve <NUM>, the annulus <NUM>, and the combustion liner <NUM>, such that the fuel injector <NUM> is capable of delivering a second flow of fuel and air to the secondary combustion zone <NUM>. The fuel injectors <NUM> may be coupled to the combustion liner <NUM> and/or the outer sleeve <NUM>, such that each fuel injector <NUM> introduces the second fuel/air mixture as a jet entering a cross-flow of the combustion products produced in the primary combustion zone <NUM>. The second fuel/air mixture(s) are ignited by the combustion products from the primary combustion zone <NUM> and burn in the secondary combustion zone <NUM>.

The fuel injector <NUM> may coupled to the outer sleeve <NUM> and may extend through the outer sleeve <NUM> and the combustion liner <NUM>. In one embodiment, a boss (not shown) supporting the fuel injector <NUM> functions as a fastener for securing the outer sleeve <NUM> to the combustion liner <NUM>. In other embodiments, the fuel injector <NUM> may be coupled to the outer sleeve <NUM> in any suitable manner, and the outer sleeve <NUM> may have any suitable number of components coupled between the flange of the forward casing <NUM> and the turbine nozzle in any suitable manner that permits the fuel injection assembly <NUM> to function as described herein. In addition to the fuel injectors <NUM>, the fuel injection assemblies <NUM> further includes a shielding assembly <NUM> and fuel supply conduits <NUM> corresponding in number to the number of fuel injectors <NUM>.

The fuel supply conduit <NUM> is positioned outside of the outer sleeve <NUM>. For example, the fuel supply conduit <NUM> may be positioned radially outward from the outer sleeve <NUM> and at least partially within the high pressure plenum <NUM>. In many embodiments, as shown in <FIG>, the fuel supply conduit <NUM> may be radially separated from the outer sleeve <NUM>. In various embodiments, the fuel supply conduits <NUM> may extend generally axially along the outer sleeve <NUM> (e.g., generally parallel to the outer sleeve but radially spaced therefrom). As shown in <FIG>, the fuel supply conduit <NUM> may extend between the forward casing <NUM> and the fuel injector <NUM>. For example, the fuel supply conduit <NUM> may extend from an inlet <NUM> positioned outside of the high-pressure plenum <NUM>, through the forward casing <NUM> and into the high pressure plenum <NUM>, to the fuel injector <NUM>. In this way, the fuel injection assemblies <NUM> may receive fuel via the inlets <NUM> and carry the fuel via the fuel supply conduit <NUM>, which is positioned outside the combustor <NUM>, to the fuel injectors <NUM> that inject the fuel with air into the secondary combustion zone <NUM>.

In particular embodiments, the fuel supply conduit may include a forward portion <NUM> and an aft portion <NUM> (<FIG>). The forward portion <NUM> of the fuel supply conduit <NUM> may extend along the flow sleeve <NUM>. For example, the forward portion <NUM> of the fuel supply conduit <NUM> may co-extend generally axially with the flow sleeve <NUM>. Similarly, and the aft portion <NUM> of the fuel supply conduit <NUM> may extend generally along the impingement sleeve <NUM>. For example, the aft portion <NUM> of the fuel supply conduit <NUM> may co-extend generally axially with the flow sleeve <NUM>.

The shielding assemblies <NUM> at least partially surround, and are located radially outward of, the fuel injectors <NUM> and the fuel supply conduit <NUM> to create protective environments around the fuel injectors <NUM> and the fuel supply conduit <NUM>. The shielding assemblies <NUM> protect the fuel supply conduit <NUM> from damage or dislocation, as may occur during the handling, installation, or maintenance of the combustor <NUM>. The shielding assemblies <NUM> may be secured to the outer surface of the outer sleeve <NUM> by mechanical fasteners or by welding or other joining techniques. Alternately, or additionally, the shielding assembly <NUM> may be secured to the fuel injector <NUM>.

Fuel <NUM> enters through the inlet <NUM> of the fuel supply conduit <NUM>, which may extend through and/or may be coupled to the forward casing <NUM> (specifically, the casing flange) or to some other convenient location. The fuel injector <NUM> mixes fuel <NUM> with compressed air <NUM> and injects the second fuel/air mixture into combustion chamber <NUM> at the secondary (downstream) combustion zone <NUM>. The first fuel/air mixture and second fuel/air mixture are ignited inside combustion chamber <NUM> to generate a flow of combustion gases <NUM> that are channeled to the turbine section <NUM>.

In some instances, fuel leaks may occur in various components of the fuel injection assemblies <NUM>, such as in the fuel injectors <NUM> and particularly in the fuel supply conduits <NUM> (particularly at one or more weld joints <NUM>). Accordingly, the present fuel injection assemblies <NUM> and combustors <NUM> provides a means for preventing said fuel leaks from contacting any hot surfaces of the combustor <NUM>, which could otherwise cause the leaked fuel to auto ignite outside of the combustion chamber <NUM> and potentially damage the combustor <NUM>.

<FIG> illustrates an enlarged view of combustor <NUM> having a fuel injection assembly <NUM>, which is viewed from radially outward of the outer sleeve <NUM> and at a circumferential location of the fuel injection assembly <NUM>. <FIG> illustrates a cross sectional view of the combustor <NUM> of <FIG>, in accordance with embodiments of the present disclosure. <FIG> illustrates an enlarged perspective view of the forward tube shield <NUM> installed on a combustor <NUM>. <FIG> illustrates an enlarged cross-sectional view of the forward tube shield <NUM> installed on a combustor <NUM>. Additionally, <FIG> illustrates an exploded view of the shielding assembly <NUM> and a fuel supply conduit <NUM> decoupled from a combustor <NUM>, in accordance with embodiments of the present disclosure.

In many embodiments, as discussed above and shown in <FIG> and <FIG>, the outer sleeve <NUM> may include a flow sleeve <NUM> and an impingement sleeve <NUM> coupled to one another. the flow sleeve <NUM> may extend between the forward casing <NUM> and the impingement sleeve <NUM>, and the impingement sleeve <NUM> may extend between the flow sleeve <NUM> and an aft frame <NUM> of the combustor <NUM>. The flow sleeve <NUM> may be inserted axially into the impingement sleeve <NUM> (such that they axially overlap with one another). For example, an outer surface of the flow sleeve <NUM> may form an interference fit (or friction fit) with the interior surface of the impingement sleeve <NUM>.

As shown best in <FIG> and <FIG> (shown as a dashed line in <FIG>), the outer sleeve <NUM> of the combustor <NUM> defines at least one fuel sweep openings <NUM> (such as multiple fuel sweep openings in some embodiments) inward of the fuel supply conduit <NUM>. For example, the at least one fuel sweep openings <NUM> may be disposed radially inward of the fuel supply conduit <NUM> and circumferentially aligned with the fuel supply conduit <NUM>. For example, an axial centerline of the fuel supply conduit <NUM> may be aligned with and generally parallel to an axial centerline of the fuel sweep opening <NUM>. In exemplary embodiments, the fuel sweep opening <NUM> may be defined in the flow sleeve <NUM> of the outer sleeve <NUM>.

For example, each fuel sweep opening <NUM> may be a slot or geometric stadium shaped opening (rectangle having circular ends) defined in the flow sleeve <NUM> directly radially inward of the fuel supply conduit <NUM>. In exemplary embodiments, the fuel sweep opening <NUM> may be partially housed (or entirely housed in some embodiments) within the forward tube shield <NUM>, such that the fuel sweep opening <NUM> is not directly exposed to the high-pressure plenum <NUM>. The fuel sweep opening <NUM> may define a major axis and a minor axis that are mutually perpendicular to one another, with the major axis being longer than the minor axis. The major axis and the minor axis may each extend across the fuel sweep opening <NUM> and through the center point of the fuel sweep opening <NUM>. The longest length of the fuel sweep opening <NUM> may be defined along the major axis (e.g., the major axis may extend from one circular end of the fuel sweep opening to the other circular end). The minor axis of the fuel sweep opening may be generally parallel to the axial direction A and generally parallel to an axial centerline (not shown) of the fuel supply conduit <NUM>. In this way, the minor axis of each fuel sweep opening <NUM> may be disposed directly radially inward of the fuel supply conduit <NUM> and generally parallel to the axial centerline of the fuel supply conduit <NUM>.

As shown in <FIG> and <FIG>, both the flow sleeve <NUM> and the impingement sleeve <NUM> may define impingement apertures <NUM>, <NUM> that provide for fluid communication between the high-pressure plenum <NUM> and the annulus <NUM> of the combustor <NUM>. For example, the impingement sleeve <NUM> may define a plurality of impingement apertures <NUM> in an irregularly arranged array (or scattered arrangement) on the impingement sleeve <NUM>, such that compressed air <NUM> may enter the annulus <NUM> through each of the impingement apertures <NUM>. Although only a portion of the impingement sleeve <NUM> is shown in <FIG> and <FIG>, the impingement apertures <NUM> may be spaced apart and defined circumferentially (e.g., defined in the impingement sleeve <NUM> at each circumferential location) around the axial centerline <NUM> of the combustor. In this way, a circumferentially uniform flow of compressed air <NUM> may be supplied into the annulus <NUM>, which may advantageously increase the operating efficiency of the combustor <NUM>.

In various embodiments, the flow sleeve <NUM> may define multiple rows <NUM> of impingement apertures <NUM> in the circumferential direction of the combustor <NUM>. As shown in <FIG>, The multiple rows <NUM> of impingement apertures <NUM> may be axially spaced apart from one another. In exemplary embodiments, the multiple rows <NUM> of impingement apertures <NUM> may fluidly couple the high-pressure plenum <NUM> to the annulus <NUM>. As shown in <FIG>, each impingement aperture <NUM> in a row <NUM> may be circumferentially spaced apart and at a similar axial location, such that each impingement apertures <NUM> in a row <NUM> is positioned on a common circumferentially extending line. The rows <NUM> of impingement apertures <NUM> defined within the flow sleeve <NUM> may increase the flow uniformity of compressed air <NUM> within the annulus <NUM> by introducing a circumferentially uniform flow of compressed air at varying axial locations, thereby increasing the efficiency of the combustor <NUM>.

In exemplary embodiments, the fuel sweep opening <NUM> may be positioned upstream of the multiple rows <NUM> of impingement apertures <NUM> with respect to the flow of combustion gases <NUM> through the combustor <NUM>. In many embodiments, the fuel sweep opening <NUM> may be larger than the impingement apertures <NUM> and <NUM> (e.g., may have a larger area), in order to induce a strong flow of compressed air <NUM> through the forward tube shield <NUM>. In many embodiments, the multiple rows <NUM> of impingement apertures <NUM> may be axially spaced apart from one another. Additionally, the fuel sweep opening <NUM> may be positioned closer to the end cover <NUM> than the multiple rows <NUM> of impingement apertures <NUM>.

In some embodiments, the flow sleeve <NUM> may define a plurality of openings <NUM> upstream from both the multiple rows <NUM> of impingement apertures <NUM> and the fuel sweep opening <NUM> with respect to the flow of combustion gases <NUM> within the combustor <NUM>. For example, the plurality of openings <NUM> may be circumferentially spaced (e.g., equally spaced) apart from one another around the entire flow sleeve <NUM>, with the exception of the circumferential location of the fuel injection assemblies <NUM>, where no opening <NUM> is defined. In many embodiments, the plurality of openings <NUM> may be disposed axially between the forward casing <NUM> and the fuel sweep opening <NUM>.

In various embodiments, as shown in <FIG>, the shielding assembly <NUM> may further include a forward tube shield <NUM> and an aft tube shield <NUM> that each surround a portion the fuel supply conduit <NUM> and define respective flow passages <NUM>, <NUM>. In many embodiments, the forward tube shield <NUM> may be coupled (e.g., directly coupled) to the flow sleeve <NUM>, and the aft tube shield <NUM> may be coupled (e.g., directly coupled) to the impingement sleeve <NUM>.

In many embodiments, the forward tube shield <NUM> and the flow sleeve <NUM> may collectively surround a forward portion <NUM> of the fuel supply conduit <NUM>. The at least one fuel sweep opening <NUM> may be defined in the flow sleeve <NUM> and disposed within the forward tube shield <NUM>, such that the first flow passage <NUM> is defined within the forward tube shield <NUM>. The first flow passage <NUM> be in fluid communication with both the at least one fuel sweep opening <NUM> and the high pressure plenum <NUM>. For example, the first flow passage <NUM> may receive compressed air <NUM> from the high pressure plenum <NUM> and expel the compressed air <NUM> into the annulus <NUM> via the fuel sweep opening(s) <NUM>. The forward tube shield <NUM> may extend axially from proximate a mounting flange <NUM> to the aft tube shield <NUM>. The mounting flange <NUM> may couple the fuel injection assembly <NUM> to the forward casing <NUM>.

The aft tube shield <NUM> may surround the aft portion <NUM> of the fuel supply conduit <NUM>, such that the second flow passage <NUM> is defined within the aft tube shield <NUM>. The second flow passage <NUM> be in fluid communication with both the injector <NUM> and the high pressure plenum <NUM>. For example, the second flow passage <NUM> may receive compressed air <NUM> from the high pressure plenum <NUM> and expel the compressed air <NUM> into the combustion chamber <NUM>. The aft tube shield <NUM> may extend axially between the forward tube shield <NUM> and an inlet flow conditioner <NUM>.

In particular embodiments, the forward tube shield <NUM> and the flow sleeve <NUM> may collectively define the boundary of the first flow passage <NUM>. For example, the forward tube shield <NUM> may be flush with, and contact, the flow sleeve <NUM> on either side of the fuel supply conduit <NUM> as the forward tube shield <NUM> co-extends generally axially with the flow sleeve <NUM>. In this way, the flow sleeve <NUM> and the forward tube shield <NUM> may collectively define the first flow passage <NUM>. The forward tube shield <NUM> may define a multiple inlets <NUM>, <NUM>, <NUM> to the first flow passage <NUM>, each of which may be in direct fluid communication with the high-pressure plenum <NUM>.

In particular, the forward tube shield <NUM> may include a first radial wall <NUM>, a second radial wall <NUM> spaced apart from the first radial wall and disposed on an opposite side of the fuel supply conduit <NUM>, and a circumferential wall <NUM> extending between the first radial wall <NUM> and the second radial wall <NUM>. The first radial wall <NUM> may extend generally radially outward from the exterior surface of the flow sleeve <NUM> to the circumferential wall <NUM>. In other words, the first radial wall <NUM> may be in flush contact with the exterior surface of the flow sleeve <NUM> and disposed on a first side of the fuel supply conduit <NUM>. The second radial wall <NUM> may extend generally radially outward from the exterior surface of the flow sleeve <NUM> to the circumferential wall <NUM>. In other words, the second radial wall <NUM> may be in flush contact with the exterior surface of the flow sleeve <NUM> and disposed on a second side of the fuel supply conduit <NUM>. The first radial wall <NUM>, the second radial wall <NUM>, the circumferential wall <NUM> and the flow sleeve <NUM> may collectively surround the forward portion <NUM> of the fuel supply conduit <NUM> (e.g., may collectively extend <NUM> degrees around the fuel supply conduit <NUM>), such that the first flow passage <NUM> is defined around the forward portion <NUM> of the fuel supply conduit <NUM>.

In many embodiments, as shown, both the forward tube shield <NUM> and the aft tube shield may extend axially from respective forward ends <NUM>, <NUM> to respective aft ends <NUM>, <NUM>, which define the terminal ends of the shields <NUM>, <NUM> in the axial direction A. For example, the forward tube shield <NUM> may extend axially from a forward end <NUM> proximate the mounting flange <NUM> to an aft end <NUM> disposed forward of the impingement sleeve <NUM>. Similarly, the aft tube shield <NUM> may extend axially from a forward end <NUM> to an aft end <NUM>. More particularly, as discussed below, the aft tube shield <NUM> may include a roof portion <NUM> and a floor portion <NUM> that couple to one another and collectively surround a portion of the fuel supply conduit <NUM> to define a second flow passage <NUM>. In such embodiments, the roof portion <NUM> may extend from the forward end <NUM> to the aft end <NUM>, and the floor portion <NUM> may extend separately from a forward end <NUM> to and aft end <NUM>. As shown in <FIG>, the forward end <NUM> of the floor portion <NUM> may be axially offset from the forward end <NUM> of the roof portion <NUM> to define the inlet <NUM> to the second flow passage <NUM>.

In various embodiments, as shown best in <FIG>, the forward tube shield <NUM> may be spaced apart from and axially overlap the aft tube shield <NUM>. For example, the forward end <NUM> of the aft tube shield <NUM> may extend axially into the forward tube shield <NUM> (e.g., without contacting the forward tube shield <NUM> to allow space for compressed air <NUM> to enter the first flow passage <NUM>). Particularly, although the tube shields <NUM> and <NUM> axially overlap one another, they do not contact one another. For example, the aft end <NUM> of the forward tube shield <NUM> may be entirely spaced apart from the aft tube shield <NUM>, thereby advantageously allowing for compressed air <NUM> to uniformly enter the first flow passage <NUM> defined by the forward tube shield <NUM> and the flow sleeve <NUM> at the aft end <NUM> of the forward tube shield <NUM>.

In many embodiments, the forward tube shield <NUM> may define a first inlet <NUM> at the forward end <NUM> of the forward tube shield <NUM>, a second inlet <NUM> at the aft end <NUM> of the forward tube shield <NUM>, and a third inlet <NUM> between the forward end <NUM> and the aft end <NUM> of the forward tube shield <NUM>. For example, the third inlet <NUM> may be defined in either the first radial wall <NUM>, the second radial wall <NUM>, or the circumferential wall <NUM> at a location between the forward end <NUM> and the aft end <NUM> of the forward tube shield. In exemplary embodiments, as shown in <FIG>, the third inlet <NUM> may be defined in the second radial wall <NUM> aft of the fuel sweep opening(s) <NUM>, such that compressed air <NUM> entering the third inlet <NUM> flows opposite the axial direction A towards the fuel sweep opening(s) <NUM>.

Each of the inlets <NUM>, <NUM>, <NUM> may provide a separate entrance for compressed air <NUM> from the high pressure plenum <NUM> to flow into the first flow path <NUM>. In particular implementations, all of the compressed air <NUM> within the first flow path <NUM> may flow towards the fuel sweep openings <NUM>. For example, compressed air <NUM> entering the first inlet <NUM> may flow in the axial direction A towards the fuel sweep openings <NUM>. Oppositely, compressed air <NUM> entering the second inlet <NUM> or third inlet <NUM> may flow opposite the axial direction A towards the fuel sweep openings <NUM>. In this way, the fuel sweep openings <NUM> may induce airflow within the forward tube shield <NUM> in opposite directions.

The shielding assembly <NUM> further includes a venturi nozzle <NUM> having a circumferentially converging portion <NUM> and a circumferentially diverging portion <NUM>. In particular, the venturi nozzle <NUM> may be defined by the forward tube shield <NUM> immediately aft of the fuel sweep openings <NUM>. As shown, the circumferentially converging portion <NUM> may converge circumferentially inwardly while extending in the downstream (or axial) direction. In other words, in the circumferentially converging portion <NUM>, the first radial wall <NUM> and the second radial wall <NUM> may taper or converge towards one another as they extend in the axial direction A. For example, the circumferential distance between the walls <NUM>, <NUM> may decrease in the axial direction A in the circumferentially converging portion <NUM>.

Oppositely, the circumferentially diverging portion <NUM> may diverge circumferentially outwardly while extending in the downstream (or axial) direction. In other words, in the circumferentially diverging portion <NUM>, the first radial wall <NUM> and the second radial wall <NUM> may taper or diverge away from one another as they extend in the axial direction A. For example, the circumferential distance between the walls <NUM>, <NUM> may increase in the axial direction A in the circumferentially diverging portion <NUM>. In many embodiments, the circumferentially diverging portion <NUM> may extend directly from the circumferentially converging portion <NUM>, such that a throat <NUM> may be defined between the circumferentially converging portion <NUM> and the circumferentially diverging portion <NUM>. The throat <NUM> may define the smallest circumferential length (and smallest cross-sectional area) of the forward tube shield <NUM>.

In this way, the circumferentially converging portion <NUM> and the circumferentially diverging portion <NUM> collectively define the venturi nozzle <NUM>, which advantageously ensures that all of the compressed air <NUM> within the forward tube shield <NUM> is directed towards one of the fuel sweep openings <NUM> by creating a pressure differential within the first flow passage <NUM> (and ensures that the air does not flow beyond the fuel sweep openings <NUM>).

In operation, the fuel sweep openings <NUM> function to induce a flow of compressed air <NUM> within the first passage <NUM>, which may advantageously sweep away any fuel leaks in the fuel supply conduit <NUM> during operation of the combustor <NUM>. In particular embodiments, the fuel supply conduit <NUM> may include a weld joint <NUM> (e.g., where portions of the fuel supply conduit are jointed together). The weld joint <NUM> may be disposed proximate the fuel sweep openings <NUM>, such that any fuel leaks from the weld joint <NUM> may be advantageously swept away by compressed air <NUM>. For example, the flow of compressed air <NUM> within the forward tube shield <NUM> may carry leaked fuel from the fuel supply conduit <NUM> (particularly from the forward portion <NUM> of the fuel supply conduit <NUM>) through the first flow passage <NUM>, the fuel sweep opening <NUM>, and into the annulus <NUM>. In this way, any leaked fuel from the forward portion <NUM> of the fuel supply conduit <NUM> may get carried away (or swept away) by the first flow of compressed air <NUM> for eventual use in the one or more fuel nozzles <NUM>. For example, any leaked fuel from the fuel supply conduit <NUM> will flow into first passage <NUM> and be swept away by the flow of compressed air <NUM>, thereby eventually traveling to the one or more fuel nozzles <NUM> for use in the primary combustion zone <NUM>. As such, the at least one fuel sweep openings <NUM> and the forward tube shield <NUM> ensure that leaked fuel from the forward portion <NUM> of the fuel supply conduit <NUM> does not travel to hot components of the combustor <NUM> (which could otherwise cause auto ignition of the leaked fuel and damage the combustor <NUM>).

In particular embodiments, the aft tube shield <NUM> may include a roof portion <NUM> and a floor portion <NUM> that collectively define the boundary of the second flow passage <NUM>. Both the roof portion <NUM> and the floor portion <NUM> may be radially spaced apart from the impingement sleeve <NUM>. Although the roof portion <NUM> and the floor portion <NUM> are shown as two separate components that collectively form the aft tube shield <NUM>, in some embodiments, the aft tube shield <NUM> may be a singular component that surrounds the aft portion <NUM> of the fuel supply conduit <NUM>.

In many embodiments, the aft tube shield <NUM> may be spaced apart from both the flow sleeve <NUM> and the aft portion <NUM> of the fuel supply conduit <NUM>, in order to define the second flow passage <NUM>. For example, the aft tube shield <NUM> may annularly surround the aft portion <NUM> of the fuel supply conduit <NUM> and may co-extend generally axially with both the impingement sleeve <NUM> and the aft portion <NUM> of the fuel supply conduit <NUM>. In various embodiments, the aft tube shield <NUM> may define an inlet <NUM> to the second flow passage <NUM> between the roof portion <NUM> and the floor portion <NUM> at a forward end of the aft tube shield <NUM>, which may be in direct fluid communication with the high-pressure plenum <NUM>. Compressed air <NUM> within the second flow passage <NUM> may flow from the inlet <NUM> towards the fuel injector <NUM>.

In various embodiments, the fuel injection assembly <NUM> may further include an inlet flow conditioner <NUM> that generally surrounds the fuel injector <NUM>. The inlet flow conditioner <NUM> may define a plurality of holes <NUM> that condition the compressed air <NUM> prior to entrance into the fuel injector <NUM>, which advantageously increases the mixing of air and fuel within the fuel injector <NUM>. As shown in <FIG>, a forward end of the inlet flow conditioner <NUM> may axially overlap with and contact the roof portion <NUM> of the aft tube shield <NUM>, in order to ensure that any fuel leakage in the aft portion <NUM> of the fuel supply conduit <NUM> safely passes into the fuel injector <NUM>.

In exemplary embodiments, compressed air <NUM> from the high-pressure plenum <NUM> may enter the second flow passage <NUM> at the inlet <NUM> and exit the second flow passage <NUM> at the fuel injector <NUM>. For example, the compressed air <NUM> within the second flow passage <NUM> may flow in the axial direction A towards the fuel injector <NUM>. In this way, any leaked fuel within the aft portion <NUM> of the fuel supply conduit <NUM> may be swept away by the compressed air <NUM> within second flow passage <NUM> for eventual use within the fuel injector <NUM>.

In operation, the fuel injector <NUM> may partially function to induce the flow of compressed air <NUM> within the second passage <NUM>, which may advantageously sweep away any fuel leaks in the fuel supply conduit <NUM> during operation of the combustor <NUM>. For example, the compressed air <NUM> within the second passage <NUM> may carry leaked fuel from the fuel supply conduit <NUM> (particularly from the aft portion <NUM> of the fuel supply conduit <NUM>) into the fuel injector <NUM> for injection into the secondary combustion zone <NUM>. As such, the aft tube shield <NUM> ensures that leaked fuel from the aft portion <NUM> of the fuel supply conduit <NUM> does not travel to hot components of the combustor <NUM> (which could otherwise cause auto ignition of the leaked fuel and damage the combustor <NUM>).

In various embodiments, the forward tube shield <NUM> may include one or more flanges <NUM> that couple directly to the flow sleeve <NUM>. For example, in some embodiments, the flanges <NUM> may define slots, through which one or more bolts <NUM> may extend and couple the flanges <NUM> to the flow sleeve <NUM> with threaded fasteners. In other embodiments, the flanges <NUM> may be welded or fixedly coupled to the flow sleeve <NUM>. In exemplary embodiments, the flanges <NUM> may be integrally formed with the forward tube shield <NUM>, such that the forward tube shield <NUM> and the flanges <NUM> are a singular component.

Similarly, the aft tube shield <NUM> may include one or more attachment flanges <NUM>, which may couple the aft tube shield <NUM> to the impingement sleeve <NUM>. As shown in <FIG> and <FIG>, the attachment flanges <NUM> may be integrally formed as a single component with the aft tube shield <NUM>. The attachment flange <NUM> may support and couple the aft tube shield <NUM> to the impingement sleeve <NUM> (e.g., via a bolt and threaded fastener, a weld, or other suitable coupling means).

Claim 1:
A combustor (<NUM>) comprising:
an end cover (<NUM>);
at least one fuel nozzle (<NUM>) extending from the end cover (<NUM>) and at least partially surrounded by a combustion liner (<NUM>), the combustion liner (<NUM>) extending from the at least one fuel nozzle (<NUM>) toward an aft frame (<NUM>), wherein the combustion liner (<NUM>) defines a combustion chamber (<NUM>) having a primary combustion zone (<NUM>) downstream from the at least one fuel nozzle (<NUM>) and a secondary combustion zone (<NUM>) downstream from the primary combustion zone (<NUM>);
an outer sleeve (<NUM>) spaced apart from and surrounding the combustion liner (<NUM>) such that an annulus (<NUM>) is defined therebetween; and
a fuel injection assembly (<NUM>), the fuel injection assembly (<NUM>) comprising:
a fuel injector (<NUM>) extending through the outer sleeve (<NUM>), the annulus (<NUM>), and the combustion liner (<NUM>) to the secondary combustion zone (<NUM>);
a fuel supply conduit (<NUM>) positioned outside of the outer sleeve (<NUM>), the fuel supply conduit (<NUM>) extending to the fuel injector (<NUM>); and
a shielding assembly (<NUM>) coupled to the outer sleeve (<NUM>) and at least partially surrounding the fuel supply conduit (<NUM>), wherein the shielding assembly (<NUM>) includes a venturi nozzle (<NUM>) having a circumferentially converging portion (<NUM>) and a circumferentially diverging portion (<NUM>),
characterized in that at least one fuel sweep opening (<NUM>) is defined in the outer sleeve (<NUM>) immediately forward of the venturi nozzle (<NUM>), and wherein the at least one fuel sweep opening (<NUM>) is disposed within the shielding assembly (<NUM>).