Patent ID: 12228286

DETAILED DESCRIPTION

Aspects of the disclosure described herein are directed to a combustion section, and in particular a combustion section with a primary combustor having a primary combustion chamber fluidly coupled to at least a primary fuel nozzle, and a set of secondary fuel nozzles. The set of secondary fuel nozzles can be fluidly coupled to a secondary combustion chamber, where the secondary combustion chamber is fluidly coupled to the primary combustion chamber at an opening in the outer liner. The set of secondary fuel nozzles can be arranged in multiple dimensions resulting in a cluster or array of fuel nozzles.

For purposes of illustration, the present disclosure will be described with respect to a turbine engine. It will be understood, however, that aspects of the disclosure described herein are not so limited and that a combustion section as described herein can be implemented in engines, including but not limited to turbojet, turboprop, turboshaft, and turbofan engines. Aspects of the disclosure discussed herein may have general applicability within non-aircraft engines having a combustor, such as other mobile applications and non-mobile industrial, commercial, and residential applications.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless specifically identified otherwise, all embodiments described herein should be considered exemplary.

As used herein, the terms “first”, “second”, “third”, and “fourth” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

The terms “forward” and “aft” refer to relative positions within a gas turbine engine or vehicle, and refer to the normal operational attitude of the gas turbine engine or vehicle. For example, with regard to a gas turbine engine, forward refers to a position closer to an engine inlet and aft refers to a position closer to an engine nozzle or exhaust.

As used herein, the term “upstream” refers to a direction that is opposite the fluid flow direction, and the term “downstream” refers to a direction that is in the same direction as the fluid flow. The term “fore” or “forward” means in front of something and “aft” or “rearward” means behind something. For example, when used in terms of fluid flow, fore/forward can mean upstream and aft/rearward can mean downstream.

The term “fluid” may be a gas or a liquid. The terms “fluidly couples” and “fluidly coupled” mean that a fluid is capable of making the connection between the areas specified.

Additionally, as used herein, the terms “radial” or “radially” refer to a direction away from a common center. For example, in the overall context of a turbine engine, radial refers to a direction along a ray extending between a center longitudinal axis of the engine and an outer engine circumference.

All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) may be used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Connection references (e.g., attached, coupled, connected, and joined) may be used and are to be construed broadly and can include intermediate structural elements between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary.

The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Furthermore, as used herein, the term “set” or a “set” of elements can be any number of elements, including only one.

As used herein, the term “array” is a two-dimensional ordered series or arrangement. That is an array has rows and columns that can be staggered or aligned in any desired pattern.

As used herein, the term “cluster” is a group of objects arranged in two dimensions closely together. By way of non-limiting example, a fuel nozzle cluster is a group of at least two fuel nozzles arranged together such that fuel nozzles in the cluster have a cluster distance between the fuel nozzles that is at least 5% less than the distance between a fuel nozzle in the cluster and a fuel nozzle not in the cluster.

FIG.1is a schematic view of a turbine engine10. As a non-limiting example, the turbine engine10can be used within an aircraft. The turbine engine10can include, at least, a compressor section12, a combustion section14, and a turbine section16. A drive shaft18rotationally couples the compressor section12and the turbine section16, such that rotation of one affects the rotation of the other, and defines a rotational axis or a centerline20for the turbine engine10.

The compressor section12can include a low-pressure (LP) compressor22, and a high-pressure (HP) compressor24serially fluidly coupled to one another. The turbine section16can include an LP turbine26, and an HP turbine28serially fluidly coupled to one another. The drive shaft18can operatively couple the LP compressor22, the HP compressor24, the LP turbine26and the HP turbine28together. Alternatively, the drive shaft18can include an LP drive shaft (not illustrated) and an HP drive shaft (not illustrated). The LP drive shaft can couple the LP compressor22to the LP turbine26, and the HP drive shaft can couple the HP compressor24to the HP turbine28. An LP spool can be defined as the combination of the LP compressor22, the LP turbine26, and the LP drive shaft such that the rotation of the LP turbine26can apply a driving force to the LP drive shaft, which in turn can rotate the LP compressor22. An HP spool can be defined as the combination of the HP compressor24, the HP turbine28, and the HP drive shaft such that the rotation of the HP turbine28can apply a driving force to the HP drive shaft which in turn can rotate the HP compressor24.

The compressor section12can include a plurality of axially spaced stages. Each stage includes a set of circumferentially-spaced rotating blades and a set of circumferentially-spaced stationary vanes. The compressor blades for a stage of the compressor section12can be mounted to a disk, which is mounted to the drive shaft18. Each set of blades for a given stage can have its own disk. The vanes of the compressor section12can be mounted to a casing which can extend circumferentially about the turbine engine10. It will be appreciated that the representation of the compressor section12is merely schematic and that there can be any number of stages. Further, it is contemplated, that there can be any other number of components within the compressor section12.

Similar to the compressor section12, the turbine section16can include a plurality of axially spaced stages, with each stage having a set of circumferentially-spaced, rotating blades and a set of circumferentially-spaced, stationary vanes. The turbine blades for a stage of the turbine section16can be mounted to a disk which is mounted to the drive shaft18. Each set of blades for a given stage can have its own disk. The vanes of the turbine section16can be mounted to the casing in a circumferential manner. It is noted that there can be any number of blades, vanes and turbine stages as the illustrated turbine section is merely a schematic representation. Further, it is contemplated, that there can be any other number of components within the turbine section16.

The combustion section14can be provided serially between the compressor section12and the turbine section16. The combustion section14can be fluidly coupled to at least a portion of the compressor section12and the turbine section16such that the combustion section14at least partially fluidly couples the compressor section12to the turbine section16. As a non-limiting example, the combustion section14can be fluidly coupled to the HP compressor24at an upstream end of the combustion section14and to the HP turbine28at a downstream end of the combustion section14.

During operation of the turbine engine10, ambient or atmospheric air is drawn into the compressor section12via a fan (not illustrated) upstream of the compressor section12, where the air is compressed defining a pressurized air. The pressurized air can then flow into the combustion section14where the pressurized air is mixed with fuel and ignited, thereby generating combustion gases. Some work is extracted from these combustion gases by the HP turbine28, which drives the HP compressor24. The combustion gases are discharged into the LP turbine26, which extracts additional work to drive the LP compressor22, and the exhaust gas is ultimately discharged from the turbine engine10via an exhaust section (not illustrated) downstream of the turbine section16. The driving of the LP turbine26drives the LP spool to rotate the fan (not illustrated) and the LP compressor22. The pressurized airflow and the combustion gases can together define a working airflow that flows through the fan, compressor section12, combustion section14, and turbine section16of the turbine engine10.

FIG.2depicts a cross-sectional view of the combustion section14along line II-II ofFIG.1defining a transverse plane (denoted “TP”). The combustion section14can include an annular arrangement of primary fuel nozzles30disposed around the centerline20of the turbine engine10(FIG.1). Each of the primary fuel nozzles, illustrated by way of example as a set of primary fuel nozzles30, are fluidly coupled to a primary combustor32. It should be appreciated that the annular arrangement of fuel nozzles can be one or multiple fuel nozzles and one or more fuel nozzles of the set of primary fuel nozzles30can have different characteristics.

The primary combustor32can have a can, can-annular, or annular arrangement depending on the type of engine in which the primary combustor32is located. In a non-limiting example, an annular arrangement is illustrated and disposed within a casing36. The primary combustor32is defined by a primary combustor liner38including an outer liner40and an inner liner42concentric with respect to each other and annular about the centerline20. A dome wall44together with the primary combustor liner38define a primary combustion chamber46annular about the centerline20. A compressed air passageway48can surround the primary combustor32and be at least partially defined by the casing36.

The combustion section14further includes a set of secondary combustors50comprising a circumferential arrangement of discrete mini combustors34. As used herein “mini” means that the component referenced with the term mini is smaller than the corresponding like component without the term mini (i.e., the discrete mini combustor34is smaller than the primary combustor32). Each discrete mini combustor34in the set of secondary combustors50is defined by a secondary combustor liner52. The secondary combustor liner52is illustrated, by way of example, as extending generally perpendicular from the primary combustor liner38. The term “generally perpendicular” is defined as an angle equal to or between 85 degrees and 95 degrees. While illustrated as a 90-degree angle, it is contemplated that in a different and non-liming example, that the secondary combustor liner52can extend from the primary combustor liner38at any angle. It is further contemplated that each combustor of the set of secondary combustors50can correspond to a portion of the secondary combustor liner52, where the angle between each portion of the secondary combustor liner52and the primary combustor liner38can vary.

The secondary combustor liner52defines at least a portion of a secondary combustion chamber illustrated, by way of example as a set of secondary combustion chambers54that are circumferentially spaced about the centerline20. The set of secondary combustion chambers54extend from the outer liner40in a radially outward direction or direction away from the centerline20. The set of secondary combustors50are fluidly coupled to the primary combustor32by at least one opening58extending through the outer liner40. More specifically, each secondary combustion chamber of the set of secondary combustion chambers54terminates at an end56at the at least one opening58to define a secondary combustor outlet60. In other words, the at least one opening58can be a plurality of openings where each secondary combustor of the set of secondary combustors50(circumferentially spaced) fluidly couples to the primary combustion chamber46at a corresponding opening58of the plurality of openings.

While illustrated as radially aligning with the primary fuel nozzle30, the secondary combustor outlet60is axially downstream from the primary fuel nozzle30. In other words, the primary fuel nozzle30and dome wall are axially forward (into the page) of the at least one opening58in the outer liner40.

The primary combustor32produces primary exhaust gasses (denoted “G1”) in the primary combustion chamber46. The set of secondary combustors50produce secondary exhaust gasses (denoted “G2”) in the set of secondary combustion chambers54that flows into the primary combustion chamber46. The secondary exhaust gasses G2circulate in the primary combustion chamber46reducing or starving O2levels. This results in a reduction of NOx emissions. The secondary exhaust gasses G2can decrease the temperature in the primary combustion chamber46, further reducing NOx emissions.

It should be understood that the mini combustor34can include a gradually converging body96(FIG.3) as described herein. Further, the mini combustor34can have a constant area cross-section throughout as illustrated inFIG.2. It is further contemplated that any combination of converging, diverging, constant combustor bodies, or any combination herein are considered.

FIG.3depicts a schematic cross-sectional view taken along line III-III ofFIG.2illustrating the combustion section14as viewed in a radial plane (denoted “RP”). It can more clearly be seen that the mini combustor34is open to the primary combustor32. The primary combustor32extends between the dome wall44and a primary combustor outlet78fluidly coupled to the turbine section16(FIG.1).

A dome assembly61includes the dome wall44and houses the primary fuel nozzles30. The primary fuel nozzle30can be fluidly coupled to a fuel inlet62via a fuel passageway64that can be adapted to receive a primary flow of fuel (denoted “F1”). The primary fuel nozzle30terminates in a fuel nozzle outlet also referred to herein as a dome inlet66. In some implementations the primary fuel nozzle30can include a swirler68circumferentially arranged about the dome inlet66. Optionally, a primary igniter70can be fluidly coupled to the primary combustion chamber46.

A dome inlet diameter71is measured across the dome inlet66. The dome inlet diameter71is illustrated, by way of example, as measured at the dome wall44.

A backwall72extends radially from the end56to connect the secondary combustor liner52to the outer liner40. The secondary combustor liner52terminates in the end56located downstream from the dome inlet66.

Optionally, any number of dilution openings74can be located downstream from the mini combustor34in the outer liner40or the inner liner42, or in both the outer liner40and the inner liner42. It is contemplated that the primary combustor liner38is free of dilution openings at any location upstream from the mini combustor34. Alternatively, in a different and non-limiting example, one or more dilution openings can be located axially between the dome inlet66and the mini combustor34.

The mini combustor34includes a mini dome assembly80including a mini dome wall82and a set of secondary fuel nozzles84. The set of secondary fuel nozzles84are illustrated, by way of example, as having multiple mixer tubes86. Alternatively, in a different and non-limiting example, the set of secondary fuel nozzles84can include a swirler (not shown).

Each mixer tube of the multiple mixer tubes86includes a tube outlet88. The set of mixer tubes86fluidly couple to the secondary combustion chamber54at the tube outlets88.

Each mixer tube of the multiple mixer tubes86are defined by walls90. A flow of fuel (denoted “F2”) and an airflow (denoted “A”) can be received by the multiple mixer tubes86. The flow of fuel F2and the airflow A received into one or more portions of the multiple mixer tubes86can be supplied through one or more openings92in walls90. As illustrated, by way of example, each mixer tube of the multiple mixer tubes86can have opposing multiple air passages92, where the flow of fuel F1is injected in center of each mixer tube. The airflow A can be placed around the flow of fuel F1to keep fuel away from the walls90of each mixer tube.

Optionally, a secondary igniter94is fluidly coupled to the secondary combustion chamber54.

It is contemplated that the mini combustor34includes a gradually converging body96. The gradually converging body96is defined as a portion of the mini combustor34where a first cross-sectional area (denoted “CA1”) proximate the mini dome wall82is greater than a second cross-sectional area (denoted “CA2”) proximate the secondary combustor outlet60.

The fuel nozzle outlet or the dome inlet66defines a first centerline (denoted “CL1”). The opening58fluidly coupling the mini combustor34to the primary combustor32defines a second centerline CL2. As illustrated, by way of example, the first centerline CL1and the second centerline CL2overlap. That is, the first centerline CL1and the second centerline CL2intersect to define a first primary combustor angle87in the radial plane RP. The first primary combustor angle87can be 90° as illustrated. While illustrated as 90° the first primary combustor angle87can be in a range from 30° to 150°.

A primary combustor length (denoted “L1”) is measured parallel to the first centerline CL1between the dome wall44and the primary combustor outlet78. A main combustion zone76is defined as the volume between the wall44and the second centerline CL2. A main combustion length (denoted “LM”) is measured parallel to the first centerline CL1from the dome wall44to the second centerline CL2. The main combustion length LM is from 5% to 90% of the primary combustor length L1. More specifically, the main combustion length LM can be in a range from 5% to 70%, 5% to 50%, or 5% to 40% of the primary combustor length L1.

A secondary combustor length (denoted “L2”) is measured parallel to the first centerline CL1between the dome wall44and the end56. The primary combustion chamber46has a radial dimension extending from the outer liner40to inner liner42and referred to herein as a primary combustor height (denoted “H”). The primary combustor height H can be measured proximate the dome wall44. The primary combustion height H is in a range from 1.1 to 10 times the dome inlet diameter71.

The secondary combustor length L2is in a range of 0% to 70% of the primary combustor length L1. More specifically, the secondary combustor length L2can be in a range of 5% to 50% of the primary combustor length L1.

A radial distance (denoted “RM”) is defined as a radial dimension extending from the first centerline CL1to the secondary combustor outlet60. The radial distance RMvaries from 0.5H to 1.0H. In other words, the radial distance RMmeasurement is in a range from 50% to 100% of the primary combustor height H.

During operation, compressed air (denoted “C”) can be provided to the combustion section14from the compressor section12(FIG.1) via the compressed air passageway48. The compressed air C can be split between the primary combustor32and the set of secondary combustors50, providing compressed air to the primary fuel nozzle30or swirler68. The compressed air C can also form the airflow A provided to the multiple mixer tubes86via openings92in the walls90. By way of non-limiting example, the primary combustor32can receive 50% to 90% of the compressed air C from the compressor section12while the set of secondary combustors50can receive between 10% and 50%.

Alternatively, in a different and non-limiting example, the primary combustor32can receive 60% to 90% of the compressed air C from the compressor section12while the set of secondary combustors50can receive between 10% and 40%. It is further contemplated that the primary combustor32can receive 70% to 90% of the compressed air C from the compressor section12while the set of secondary combustors50can receive between 10% and 30%.

Alternatively, in yet another different and non-limiting example, the primary combustor32can receive 10% to 50% of the compressed air C from the compressor section12while the set of secondary combustors50can receive between 50% and 90%. It is further contemplated that the primary combustor32can receive 10% to 40% of the compressed air C from the compressor section12while the set of secondary combustors50can receive between 60% and 90%.

Compressed air C can be fed into the primary fuel nozzle30and mixed with the primary flow of fuel F1to define a primary fuel/air mixture. The primary fuel nozzle30can dispense a primary fuel/air mixture that is premixed or partially premixed. Further, the flow of fuel F1can be a diffusion fuel free of an air mixture prior to entering the primary combustion chamber46.

Fuel provided to the primary fuel nozzle30and the multiple mixer tubes86can include jet fuel natural gas or a more reacting fuel like hydrogen (H2) and blends of H2. In some implementations, the turbine engine10(FIG.1) can be started on conventional fuel using the set of secondary combustors50where the secondary exhaust gasses G2(FIG.2) are propagated towards the primary combustion chamber46which can be fueled using conventional fuel or H2fuel.

When the secondary exhaust gasses G2are directed towards the primary combustion chamber46, the primary exhaust gasses G1(FIG.2) and the secondary exhaust gasses G2mix which reduces O2levels in the primary combustion chamber46that reduces NOx emissions. Fuel staging between the primary combustion chamber46and the secondary combustion chamber54reduces the fuel/air ratio in these stages of the combustion section14which contributes to a further reduction in temperature and NOx emissions. In comparison a single staged combustor will have relatively higher fuel/air ratios and higher temperatures which leads to higher NOx emissions.

Optionally, a secondary set of dilution openings98can be provided in the secondary combustor liner52for connecting the compressed air passageway48and the secondary combustion chamber54. The secondary set of dilution openings98can be at an aft location of the mini combustor34for trimming a combustor exit temperature profile and pattern factor associated with the mini combustor34and primary combustor32.

By way of non-limiting example, the primary fuel nozzle30can be a rich cup having a swirler68. A rich cup can have a fuel/air ratio higher than the stoichiometric ratio. The primary fuel nozzle30and at least the main combustion zone76can define a primary combustion system. When the primary fuel nozzle30is a rich cup then the primary combustion system can be a rich burn combustion system, where a rich burn combustion system includes an overall fuel/air ratio above the stoichiometric fuel/air ratio.

Alternatively, in a different and non-limiting example, the primary fuel nozzle30can be a lean cup and the primary combustion system can be a lean burn combustion system, where a lean burn combustion system includes an overall fuel/air ratio below the stoichiometric fuel/air ratio.

It is also contemplated that the primary fuel nozzle is controllable between fuel rich and fuel lean, such that the primary fuel nozzle30includes at least one cup that can be a rich cup or a lean cup depending on the controllable fuel supply.

The set of secondary fuel nozzles84and at least the secondary combustion chamber54can define a secondary combustion system. The set of secondary fuel nozzles84can include a flame that can be premixed, partially premixed, or diffused. The set of secondary fuel nozzles84include lean cups, rich cups, or a combination of lean cups and rich cups. The secondary combustion system can be a rich burn combustion system or a lean burn combustion system, depending on the overall fuel/air ratio of the set of secondary fuel nozzles84and resulting burn temperature. It is also contemplated that one or more of the multiple mixer tubes86defining the set of secondary fuel nozzles84can be a pilot tube. As used herein, the term “pilot tube” implies a richer fuel/air mixture. That is, a pilot tube is a mixer tube that receives more fuel per unit air than other mixer tubes in a set of mixer tubes. By way of non-limiting example, the additional fuel per unit air can be provided by one or more of: providing additional fuel to the mixer tube, incorporation of a swirler, where the air and the additional fuel are mixed via a swirler, or providing additional fuel via openings that circumscribing the tube outlet88of the pilot tube. While the pilot tube is considered richer than a lean mixer tube, it is contemplated that the pilot tube can be a rich cup or a lean cup.

The secondary combustion chamber54can be a set of circumferentially spaced secondary combustion chambers, as illustrated inFIG.2. Each secondary combustion chamber54of the set of secondary combustion chambers can create its own secondary combustion system. That is, to break circumferential dynamics mode, some secondary combustion chambers can be made relatively fuel rich and others fuel lean.

It is contemplated that each secondary combustor of the set of secondary combustors is controllable between a rich burn combustion system and a lean burn combustion system. That is, during operation, each combustor of the set of secondary combustors can be controlled to be relatively fuel rich or relatively fuel lean.

When the primary combustion system is combined with the secondary combustion system, the secondary combustion system starves at least the primary combustion system of oxygen. This starvation or reduction of available oxygen to form NOx reduces NOx emissions from the primary combustion chamber46.

The equivalence ratio (phi “Φ”) of the primary combustion system or the secondary combustion system can be in a range from 0.4 to 2. When the primary combustion system and the secondary combustion system are lean burn combustion systems, the equivalence ratio (phi Φ) of the primary combustion system or the secondary combustion system can be in a range from 0.4 to 0.8. As used herein, equivalence ratio (phi “Φ”) is defined as the ratio of the fuel-to-oxidizer ratio to the stoichiometric fuel-to-oxidizer ratio.

FIG.4depicts a cross-sectional view of another embodiment of a combustion section114as viewed in a radial plane (denoted “RP”). The combustion section114is similar to the combustion section14ofFIG.3; therefore, like parts will be identified with like numerals increased by 100, with it being understood that the description of the like parts of the combustion section14applies to the combustion section114, except where noted.

A primary combustor132extends between a dome wall144and a primary combustor outlet178fluidly connected to the turbine section16. An outer liner140is spaced radially from an inner liner142to define a primary combustion chamber146of the primary combustor132. A dome assembly161includes the dome wall144and houses a set of primary fuel nozzles130. The set of primary fuel nozzles130are illustrated, by way of example, as multiple primary mixer tubes131. The multiple primary mixer tubes131can be adapted to receive a primary flow of fuel (denoted “F1”) and a primary airflow A1. The set of primary fuel nozzles130can terminate in a set of fuel outlets, also referred to herein as a set of dome inlets166.

A main combustion zone176is defined as the volume between the set of dome inlets166and the second centerline CL2defined by the opening58of the discrete mini combustor34or the mini dome wall82. During operation each fuel nozzle of the set of primary fuel nozzles130can include a flame133that can be premixed, partially premixed, or diffused. The set of primary fuel nozzles130can include lean cups, rich cups, or a combination of lean cups and rich cups. The set of primary fuel nozzles130and at least the main combustion zone176can define a primary combustion system. The primary combustion system can be a rich burn combustion system or a lean burn combustion system, depending on the overall fuel/air ratio of the set of primary fuel nozzles130and resulting burn temperature. It is contemplated that one or more of the multiple primary mixer tubes131of the set of primary fuel nozzles130can be a pilot tube. The set of primary fuel nozzles130are illustrated as having three fuel nozzles when viewed in the radial plane RP, however, any number of fuel nozzles are contemplated.

The secondary combustion chamber54is defined by the secondary combustor liner52and the mini dome wall82. The secondary combustion chamber54fluidly couples to the primary combustion chamber146at the opening58of the outer liner140. During operation each fuel nozzle of the set of secondary fuel nozzles84can include flames135that can be premixed, partially premixed, or diffused. The multiple mixer tubes86can be lean cups, rich cups, or a combination of lean cups and rich cups. It is also contemplated that one or more of the multiple mixer tubes86can be a pilot tube. By way of non-limiting example, the multiple mixer tubes86can be lean and the flames135can be a cluster or array of micro flames.

The set of secondary fuel nozzles84are illustrated as having three fuel nozzles when viewed in the radial plane RP, however, any number of fuel nozzles are contemplated.

The primary combustion system and the secondary combustion system of the combustion section114can be lean burn combustion systems. It is contemplated that while the primary combustion system and the secondary combustion system are lean burn combustion systems, one or more fuel nozzles of the set of primary fuel nozzles130, or one or more fuel nozzles of the set of secondary fuel nozzles84can be a rich cup or a pilot tube.

Alternatively, in a different and non-limiting example, the primary combustion system can be a rich burn combustion system. It is further contemplated that while the primary combustion system is a rich burn combustion system, the set of primary fuel nozzles130can include lean cups and rich cups.

Alternatively, in yet another different and non-limiting example, the secondary combustion system can be a rich burn combustion system. It is further contemplated that while the secondary combustion system is a rich burn combustion system, the set of primary fuel nozzles130can include lean cups and rich cups.

FIG.5depicts a cross-sectional view of the combustion section114along line V-V ofFIG.4in a parallel transverse plane TP to that illustrated inFIG.2. Each mixer tube of the multiple mixer tubes86are defined by walls90. The flow of fuel F2and the airflow A can be received by the multiple mixer tubes86. The fuel F2can be received into each mixer tube of the multiple mixer tubes86from one or more fuel openings92ain the walls90that define the mixer tube. Further the airflow A (a portion of the compressed airflow C (FIG.3) is received into one or more portions of the multiple mixer tubes86being supplied through one or more air openings92bin walls90.

As illustrated, by way of example, the gradually converging body96can be gradually converging in the transverse plane TP as well as the radial plane RP (FIG.4). A third cross-sectional area (denoted “CA3”) proximate the mini dome wall82is greater than a fourth cross-sectional area (denoted “CA4”) proximate the secondary combustor outlet60.

Alternatively, in a different and non-limiting example, the gradually converging body96can gradually converge as viewed by a single plane. Further, in yet another different and non-limiting example, the mini combustor34can have a constant area cross-section throughout. It is further contemplated that any combination of converging, diverging, constant combustor bodies, or any combination herein are considered.

The set of secondary fuel nozzles84are illustrated as having two fuel nozzles when viewed in the transverse plane TP, however, any number of fuel nozzles are contemplated. More specifically, the set of secondary fuel nozzles84can include at least two or more nozzles located or viable in the radial plane RP or the transverse plane TP.

FIG.6depicts a cross-sectional view of the combustion section114along line VI-VI at the mini dome wall82coupled to the secondary combustor liner52ofFIG.4.FIG.6further illustrates the set of secondary fuel nozzles84, showing how the set of secondary fuel nozzles are arranged in an array or a cluster of fuel nozzles84a,84b. By way of example, the illustrated eight fuel nozzles84a,84bcan be arranged in rows and columns where the rows or columns can have a varying number of fuel nozzles. In other words, the set of secondary fuel nozzles84can be staggered in at least two dimensions. That is, the set of secondary fuel nozzles84can include multiple fuel nozzles visible in more than one plane that form a cluster or an array. While illustrated as eight fuel nozzles84a,84b, the set of secondary fuel nozzles84can include any number of fuel nozzles. More specifically, the set of secondary fuel nozzles84can include two or more fuel nozzles.

Orientating the set of secondary fuel nozzles84as a cluster of fuel nozzles84a,84bprovides a temperature control advantage. The cluster of fuel nozzles84a,84bcan also provide a desired temperature gradient. The fuel/air mixture of each mixer tube of the multiple mixer tubes86(FIG.5) can be individually selected or controlled. That is, one or more of the fuel nozzles can have the same or different fuel/air mixture. It is also contemplated that the fuel/air mixture of each mixer tube of the multiple mixer tubes86(FIG.5) can be controlled during operation.

By way of non-limiting example, the fuel nozzles84a, illustrated as a first subset of the secondary fuel nozzles84that make up a portion of the array or the cluster, can be lean cups. The fuel nozzles84b, illustrated as a second subset of the secondary fuel nozzles84that make up a portion of the array or the cluster, can be a pilot tube or a rich cup. While illustrated as two fuel nozzles84b, any number of secondary fuel nozzles84can form the second subset of fuel nozzles84b.

It is contemplated that the fuel/air mixture of each secondary fuel nozzle of the set of secondary fuel nozzles84can be controlled such that a lean cup can become a rich cup or a pilot tube. It is further contemplated that the fuel/air mixture of each secondary fuel nozzle of the set of secondary fuel nozzles84can be controlled such that a rich cup or pilot tube can become a lean cup.

The second centerline CL2, generally perpendicular to the mini dome wall82, is illustrated, by way of example, in the middle of the set of secondary fuel nozzles84. In other words, the second centerline CL2is located at the geometric center point of the cluster of the set of secondary fuel nozzles84. Alternatively, other locations of the intersection of the second centerline CL2and the mini dome wall82are contemplated.

FIG.7depicts a cross-sectional view of yet another embodiment of a combustion section214as viewed in a radial plane (denoted “RP”). The similar combustion section214is similar to the combustion section114ofFIG.4, therefore, like parts will be identified with like numerals further increased by 100, with it being understood that the description of the like parts of the combustion section114apply to the combustion section214, except where noted.

A primary combustor232extends between a dome wall244and a primary combustor outlet278fluidly connected to the turbine section16. An outer liner240is spaced radially from an inner liner242to define a primary combustion chamber246of the primary combustor232. A dome assembly261includes the dome wall244and houses a set of primary fuel nozzles230. The set of primary fuel nozzles230includes a set of fuel outlets266. The set of fuel outlets266define a first centerline (denoted “CL1”).

The combustion section214includes a set of secondary combustion chambers illustrated, by way of example as a forward secondary combustion chamber254aand an aft secondary combustion chamber254b. The forward secondary combustion chamber254acan be one discrete combustion chamber of a set of discrete, circumferentially spaced forward secondary combustion chambers. The aft secondary combustion chamber254bcan be one combustion chamber of a set of discrete, circumferentially spaced aft secondary combustion chambers having axially spaced circumferential centerlines from circumferential centerlines of the forward secondary combustion chambers.

The forward secondary combustion chamber254ais defined by a forward secondary combustor liner252aand a forward mini dome wall282a. A forward set of secondary fuel nozzles284aare coupled to or are received by the forward mini dome wall282a. A forward opening258ain the outer liner240fluidly couples the forward secondary combustion chamber254ato the primary combustion chamber246.

The aft secondary combustion chamber254bis defined by an aft secondary combustor liner252band an aft mini dome wall282b. An aft set of secondary fuel nozzles284bare coupled to or are received by the aft mini dome wall282b. An aft opening258bin the outer liner240fluidly couples the aft secondary combustion chamber254bto the primary combustion chamber246.

A main combustion zone276can be defined as the volume between the set of fuel outlets266of the set of primary fuel nozzles230, and a forward centerline CL3defined by the forward opening258ain the outer liner240located at an exit of a forward discrete mini combustor234a. The set of primary fuel nozzles230can include lean cups, rich cups, or a combination of lean cups and rich cups. The set of primary fuel nozzles230and at least the main combustion zone276can define a primary combustion system. The primary combustion system can be a rich burn combustion system or a lean burn combustion system, depending on the overall fuel/air ratio of the set of primary fuel nozzles230and resulting burn temperature.

A forward secondary combustion system can be defined by the forward secondary combustion chamber254aand the forward set of secondary fuel nozzles284a. The forward set of secondary fuel nozzles284acan include lean cups, rich cups, pilot tubes, or a combination of lean cups and rich cups. The forward secondary combustion system can be a rich burn combustion system or a lean burn combustion system, depending on the overall fuel/air ratio of the forward set of secondary fuel nozzles284aand resulting burn temperature.

An aft secondary combustion system can be defined by the aft secondary combustion chamber234band the aft set of secondary fuel nozzles284b. The aft set of secondary fuel nozzles284bcan include lean cups, rich cups, pilot tubes, or a combination of lean cups and rich cups. The forward secondary combustion system can be a rich burn combustion system or a lean burn combustion system, depending on the overall fuel/air ratio of the aft set of secondary fuel nozzles284band resulting burn temperature.

While illustrated as the same size, the forward secondary combustion chamber254aand the aft secondary combustion chamber254bcan have different volumes or cross-sectional shapes. Further, one of the forward secondary combustion chamber254aor aft secondary combustion chamber254bcan be an annular combustion chamber (seeFIG.10). It is also contemplated that the forward set of secondary fuel nozzles284bor the aft set of secondary fuel nozzles284bcan include any number of fuel nozzles.

FIG.8is a schematic of a portion of the outer liner240as seen from line VIII-VIII inFIG.7. An axial direction (denoted “AD”) extends parallel to the centerline20(FIG.1), a radial direction (denoted “RD”) extends into the page and perpendicular to the axial direction AD, and a circumferential direction (denoted “CD”) is perpendicular to both the radial and axial directions RD, AD. The circumferential direction CD circumscribes the engine centerline20(FIG.1) and extends up and down the page when oriented in two dimensions as illustrated.

The forward opening258acan be a set of forward openings258awhere each forward opening corresponds to a discrete circumferentially spaced forward secondary combustion chamber. Each of the forward openings258aof the set of forward openings258aincludes a corresponding forward centerline CL3.

The aft opening258bcan be a set of aft openings258bwhere each aft opening corresponds to a discrete circumferentially spaced aft secondary combustion chamber. As illustrated, by way of example, the set of aft openings258bare spaced from the set of forward openings258ain the axial direction AD. As illustrated, by way of example, the set of forward openings258aand the set of aft openings258baxially align. While illustrated as completely aligned, it is contemplated that at least a portion of the set of aft openings258baxially align with at least a portion of the set of forward openings258a.

As illustrated, by way of example, the first centerline CL1can pass through at least a portion of the forward opening258aor the aft opening258b. It is contemplated that the first centerline CL1can intersect the third centerline CL3.

Alternatively, in a different and non-limiting example, the forward opening258aand the aft opening258bcan be located in the circumferential direction CD in such a way that the first centerline CL1does not align or pass through any portion of the forward opening258aand the aft opening258b.

FIG.9depicts a schematic cross-sectional view of another embodiment of a portion of an outer liner340similar to the portion of the outer liner240ofFIG.8, therefore, like parts will be identified with like numerals further increased by 100, with it being understood that the description of the like parts of the portion of the outer liner240apply to the portion of the outer liner340, except where noted.

At least one forward opening can be a set of forward openings358awhere each forward opening corresponds to a discrete circumferentially spaced forward secondary combustion chamber. Each of the forward openings of the set of forward openings358acan include a corresponding forward centerline CL3.

An aft opening can be a set of aft openings358bwhere each aft opening corresponds to a discrete circumferentially spaced aft secondary combustion chamber. As illustrated, by way of example, the set of aft openings358bare spaced from the set of forward openings358ain the axial direction AD. As illustrated, by way of example, the set of forward openings358aand the set of aft openings358baxially offset from each other.

As illustrated, by way of example, the third centerline CL3is located between adjacent first centerlines CL1.

A first axial distance (denoted “S1”) can be measured in the axial direction AD between one of the forward openings358aand one of the aft openings358b. As illustrated by a second axial distance (denoted “S2”), the axial distance between the forward openings358aand the aft openings358bcan be equal, however it is contemplated in a different and non-limiting example, that the first axial distance S1and the second axial distance S2can be different.

FIG.10depicts a cross-sectional view of another embodiment of a combustion section414as viewed in a transverse plane (denoted “TP”). The combustion section414includes an annular arrangement of primary fuel nozzles430disposed around the centerline20of the turbine engine10(FIG.1). Each of the primary fuel nozzles430are fluidly coupled to a primary combustor432. It should be appreciated that the annular arrangement of fuel nozzles can be one or multiple fuel nozzles and one or more of the primary fuel nozzles430can have different characteristics. The primary combustor432can have a can, can-annular, or annular arrangement depending on the type of engine in which the primary combustor432is located. In a non-limiting example, an annular arrangement is illustrated and disposed within a casing436. The primary combustor432is defined by a primary combustor liner438including an outer liner440and an inner liner442concentric with respect to each other and annular about the centerline20. A dome wall444together with the primary combustor liner438define a primary combustion chamber446annular about the centerline20. A compressed air passageway448can surround the primary combustor432and be at least partially defined by the casing436.

The combustion section414further includes a set of secondary combustors450comprising an annular mini combustor434. The annular mini combustor434is defined by a secondary combustor liner452concentric with respect to the outer liner440and the inner liner442and annular about the centerline20. The secondary combustor liner452together with the outer liner440defines at least a portion of a secondary combustion chamber454circumferentially arranged about the centerline20. The annular mini combustor434is open to the primary combustor432. More specifically, the secondary combustor liner terminates at an end456axially downstream from the primary fuel nozzles430.

The primary combustor432produces primary exhaust gasses (denoted “G1”) in the primary combustion chamber446. The set of secondary combustors450produce secondary exhaust gasses (denoted “G2”) in the secondary combustion chamber454that flow into the primary combustion chamber446. The secondary exhaust gasses G2circulate in the primary combustion chamber446starving O2levels and reducing temperatures in the primary combustion chamber446. This results in a reduction of NOx emissions.

It is contemplated that the cross sections illustrated inFIG.3,FIG.4, orFIG.7can be cross sections of a portion of the combustion section414. That is, the secondary combustion chamber54, the forward secondary combustion chamber254a, or the aft secondary combustion chamber254bcan be an annular combustion chamber instead of a discrete set of secondary combustion chambers.

In the case of the annular mini combustor434, circumferential fuel supply can be varied to make portions of the exhaust hotter than the rest to change heat release rates circumferentially. That is, fuel supplied to each secondary fuel nozzle of the set of secondary fuel nozzles, or a cluster of secondary fuel nozzles circumscribing the annular mini combustor434are controllable. By controlling the fuel supply circumferentially, temperature can be changed or adjusted at different portions of the annular mini combustor434. In other words, each secondary fuel nozzle, each cluster of secondary mixer tubes, or each secondary mixer tube are controllable between fuel rich and fuel lean.

FIG.11depicts a cross-sectional view of yet another embodiment of a combustion section514as viewed in a transverse plane (denoted “TP”). The combustion section514includes an annular arrangement of primary fuel nozzles530disposed around the centerline20of the turbine engine10(FIG.1). Each of the primary fuel nozzles530are fluidly coupled to a primary combustor532. It should be appreciated that the annular arrangement of fuel nozzles can be one or multiple fuel nozzles and one or more of the primary fuel nozzles530can have different characteristics. The primary combustor532can have a can, can-annular, or annular arrangement depending on the type of engine in which the primary combustor532is located. In a non-limiting example, an annular arrangement is illustrated and disposed within a casing536. The primary combustor532is defined by a primary combustor liner538including an outer liner540and an inner liner542concentric with respect to each other and annular about the centerline20. A dome wall544together with the primary combustor liner538define a primary combustion chamber546annular about the centerline20. A compressed air passageway548can be located between at least a portion of the casing536and the primary combustor532.

The combustion section514further includes a set of secondary fuel nozzles584axially downstream from the primary fuel nozzles530. The set of secondary fuel nozzles584include a cluster of mixer tubes illustrated as mixer tubes541,543,545. The mixer tubes541,543,545are fluidly coupled to the primary combustion chamber546at the outer liner540. The mixer tubes541,543,545can extend through the casing536and the outer liner540. Alternatively, in another different and non-limiting example, the mixer tubes541,543,545can be defined by the casing536. Alternatively, in yet another different and non-limiting example, the mixer tubes541,543,545can be located within the outer liner540, wherein air and fuel are provided to the mixer tubes541,543,545via a conduit (not shown) that passes through the casing536.

While illustrated as each primary fuel nozzle530corresponding to a respective set of secondary fuel nozzles584, it is contemplated that the set of secondary fuel nozzles584can be circumferentially arranged or located at any point of the outer liner540. That is, in a different and non-limiting example, the set of secondary fuel nozzles584can be circumferentially spaced or distributed at equal arclengths about the centerline20.

The primary combustor532produces primary exhaust gasses (denoted “G1”) in the primary combustion chamber546. The set of secondary fuel nozzles584produce micro flames in the primary combustion chamber546. The micro flames consume some of the O2in the primary combustion chamber546, reducing the levels O2, resulting in a reduction of NOx emissions.

FIG.12depicts a schematic cross-sectional view taken along line XII-XII ofFIG.11illustrating the combustion section514as viewed in a radial plane (denoted “RP”). It can more clearly be seen that the set of secondary fuel nozzles584are open to the primary combustor532. The primary combustor532extends between the dome wall544and a primary combustor outlet578fluidly coupled to the turbine section16(FIG.1).

A dome assembly561includes the dome wall544and houses a set of primary fuel nozzles530. The set of primary fuel nozzles530are illustrated, by way of example, as multiple primary mixer tubes531. The multiple primary mixer tubes531can be adapted to receive a primary flow of fuel (denoted “F1”) and a primary airflow A1. The set of primary fuel nozzles530can terminate in a set of fuel outlets, also referred to herein as a set of dome inlets566.

By way of non-limiting example, the set of primary fuel nozzles530can be one or more of lean cups, rich cups, or pilot tubes.

The set of secondary fuel nozzles584are located axially downstream from the dome wall544. The mixer tube543can be upstream or forward of another mixer tube547that are part of the cluster of mixer tubes that include at least mixer tubes541(FIG.11),545(FIG.11),543,547. The mixer tubes543,547are fluidly coupled to the primary combustion chamber546at openings558of an outer liner540that partially defines the primary combustion chamber546.

By way of non-limiting example, the set of secondary fuel nozzles584can be one or more of lean cups, rich cups, or pilot tubes. The equivalence ratio (phi “Φ”) of a combustion system including the primary combustion chamber546, the set of primary fuel nozzles530, and the set of secondary fuel nozzles584can be in a range from 0.4 to 2.

The set of secondary fuel nozzles584produce micro flames (denoted “MF”) in the primary combustion chamber546. The micro flames MF consume some of the O2in the primary combustion chamber546, reducing the levels O2, resulting in a reduction of NOx emissions.

The set of dome inlets566define a first centerline (denoted “CL1”). One or more of the openings558fluidly coupling one of the set of secondary fuel nozzles584to the primary combustor532can define a second centerline CL2. The first centerline CL1and the second centerline CL2intersect to define an angle587in the radial plane RP. The angle587can be 90° as illustrated. While illustrated as a 90-degree angle, it is contemplated that in a different and non-liming example, that the angle587can vary from 30° to 150°, as further illustrated inFIG.13.

FIG.13depicts a schematic cross-sectional view of another embodiment of a combustion section614as viewed in a radial plane (denoted “RP”). The combustion section614is similar to the combustion section514ofFIG.12, therefore like parts will be identified with like numerals further increased by 100, with it being understood that the description of the like parts of the combustion section514applies to the combustion section614, except where noted.

A primary combustor632extends between the dome wall644and a primary combustor outlet678fluidly coupled to the turbine section16(FIG.1). A dome assembly661includes the dome wall644and houses a set of primary fuel nozzles630. The set of primary fuel nozzles630are illustrated, by way of example, as multiple primary mixer tubes631. The multiple primary mixer tubes631can be adapted to receive a primary flow of fuel (denoted “F1”) and a primary airflow A1. The set of primary fuel nozzles630can terminate in a set of fuel outlets, also referred to herein as a set of dome inlets666. By way of non-limiting example, the set of primary fuel nozzles630can be one or more of lean cups, rich cups, or pilot tubes.

A set of secondary fuel nozzles684are located axially downstream from the dome wall644. The set of secondary fuel nozzles684can be mixer tubes643,647,649that are part of the cluster of mixer tubes. The mixer tubes643,647,649are fluidly coupled to a primary combustion chamber646at openings658of an outer liner640that partially defines the primary combustion chamber646. By way of non-limiting example, the set of secondary fuel nozzles684can be one or more of lean cups, rich cups, or pilot tubes.

It is contemplated that the primary combustor632includes a gradually converging body696. The gradually converging body696is defined as a portion of the primary combustor632where a forward cross-sectional area (denoted “FCA”) is greater than an aft cross-sectional area (denoted “ACA”). The forward cross-sectional area FCA can be measured proximate the dome wall644or upstream of the set of secondary fuel nozzles684. The aft cross-sectional area ACA can be measured downstream of the set of secondary fuel nozzles684or proximate the primary combustor outlet678.

The set of dome inlets666define a first centerline (denoted “CL1”). The openings658can define a second centerline (denoted “CL2”). The first centerline CL1and the second centerline CL2intersect to define an angle in the radial plane RP. The angle can be less than 90° as illustrated. While illustrated as less than 90°, it is contemplated in a different and non-limiting example, that the angle687can be in a range from 30° to 150°.

Benefits of the angle687being different than 90° can include increase in turbulation of the air in the primary combustor632, further reducing the O2in the primary combustion chamber646.

Benefits of the gradually converging body696includes reducing residence time of the combustion section614which helps to reduce NOx emission. Furthermore, converging the primary combustor632helps to penetrate the exhaust from the set of secondary fuel nozzles684(or a secondary combustor) to the middle of the primary combustor632. Having less height to penetrate to reach middle of the primary combustor632thereby achieves the desired mixing of the secondary exhaust gasses G2(FIG.2orFIG.11) from the set of secondary fuel nozzles684(or the secondary combustor) with bulk flow or the primary exhaust gasses G1(FIG.2orFIG.11) in the primary combustion chamber646.

Benefits associated with the set of secondary combustors in combination with the primary combustor and methods described herein are to reduce NOx emissions even in a severe cycle with a higher operating air pressure, higher temperature, higher fuel/air ratio and with heated fuel. Typically, higher fuel/air ratio within a combustion system leads to a higher flame temperature which results in higher NOx. By having two combustion chambers within the combustion system, fuel can be split between these chambers thereby reducing the fuel/air ratio in each chamber and in turn achieving lower temperature and hence lower NOx emission. By directing product of combustion from a secondary combustion into a primary combustion chamber, O2levels in the primary combustion chamber can be reduced, further reducing NOx emission. The combustions section herein can operate with 100% H2fuel.

The set of secondary fuel nozzles create smaller compact flame structures in the secondary combustor that helps to reduce length of the secondary combustor. Smaller multiple compact flame structures also reduces NOx. The set of secondary fuel nozzles distribute uniform temperature created by multiple flames and carbon emission, where smaller flames have higher lengths available post flame for CO burn out.

While described with respect to a turbine engine, it should be appreciated that the combustor as described herein can be for any engine having a combustor that emits NOx. It should be appreciated that application of aspects of the disclosure discussed herein are applicable to engines with propeller sections or fan and booster sections along with turbojets and turbo engines as well.

To the extent not already described, the different features and structures of the various embodiments can be used in combination, or in substitution with each other as desired. That one feature is not illustrated in all of the embodiments is not meant to be construed that it cannot be so illustrated, but is done for brevity of description. Thus, the various features of the different embodiments can be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure.

This written description uses examples to describe aspects of the disclosure described herein, including the best mode, and also to enable any person skilled in the art to practice aspects of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of aspects of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Further aspects are provided by the subject matter of the following clauses:

A combustion section for a turbine engine, the combustion section comprising a primary combustor liner including an inner liner and an outer liner, a dome wall extending between the inner liner and the outer liner, a primary combustion chamber defined at least in part by the inner liner, the outer liner, and the dome wall, wherein the outer liner defines at least one opening aft of the dome wall, a primary fuel nozzle having an outlet at the dome wall, wherein the outlet of the primary fuel nozzle is fluidly coupled with the primary combustion chamber, a secondary combustion chamber defined at least in part by a secondary combustor liner, the secondary combustion chamber fluidly coupled to the primary combustion chamber at the at least one opening, and a set of secondary fuel nozzles comprising multiple mixer tubes having outlets at the secondary combustor liner, wherein the outlets of the mixer tubes are fluidly coupled with the secondary combustion chamber.

A combustion section for a turbine engine, the combustion section comprising a primary combustor liner including an inner liner and an outer liner, a dome wall extending between the inner liner and the outer liner, a primary combustion chamber defined at least in part by the inner liner, the outer liner, and the dome wall, wherein the outer liner defines at least one opening aft of the dome wall, a primary fuel nozzle having an outlet at the dome wall, wherein the outlet of the primary fuel nozzle is fluidly coupled with the primary combustion chamber, and a set of secondary fuel nozzles comprising annularly spaced clusters of mixer tubes having outlets at the outer liner, wherein the outlets of the mixer tubes are fluidly coupled with the primary combustion chamber.

The combustion section of any preceding clause, wherein at least one mixer tube of the multiple mixer tubes is a pilot tube.

The combustion section of any preceding clause, wherein the primary fuel nozzle is a plurality of primary fuel nozzles.

The combustion section of any preceding clause, wherein the plurality of primary fuel nozzles includes multiple primary mixer tubes, and wherein at least one primary mixer tube is a pilot tube.

The combustion section of any preceding clause, wherein the plurality of primary fuel nozzle includes at least one rich fuel cup.

The combustion section of any preceding clause, wherein the plurality of primary fuel nozzles includes at least one lean fuel cup.

The combustion section of any preceding clause, wherein the primary fuel nozzle includes at least one cup controllable between a rich fuel cup and a lean fuel cup.

The combustion section of any preceding clause, wherein each primary fuel nozzle of the plurality of primary fuel nozzles includes at least one cup controllable between a rich fuel cup and a lean fuel cup.

The combustion section of any preceding clause, wherein the at least one opening is defined by the secondary combustor liner.

The combustion section of any preceding clause, wherein the secondary combustion chamber is a set of circumferentially spaced combustion chambers and the at least one opening is a plurality of circumferentially spaced openings, where each secondary combustion chamber of the set of circumferentially combustion chambers fluidly couples to the primary combustion chamber at each opening of the plurality of circumferentially spaced openings.

The combustion section of any preceding clause, wherein the secondary combustion chamber is an annular combustion chamber defined in part by the outer liner.

The combustion section of any preceding clause, wherein a cluster of secondary mixer tubes are circumferentially spaced about the annular combustion chamber.

The combustion section of any preceding clause, wherein the cluster of secondary mixer tubes are controllable between fuel rich and fuel lean.

The combustion section of any preceding clause, wherein a first centerline defined by the primary fuel nozzle overlaps with a second centerline defined by the at least one opening.

The combustion section of any preceding clause, wherein a primary combustor defined by the primary combustion chamber and the primary fuel nozzles is a rich burn system.

The combustion section of any preceding clause, wherein the secondary combustion chamber is a plurality of secondary combustion chambers, and a set of secondary combustors are defined by the plurality of secondary combustion chambers and the set of secondary fuel nozzles is a lean burn system.

The combustion section of any preceding clause, wherein a primary combustor defined by the primary combustion chamber and the primary fuel nozzles are a lean burn system, and wherein a set of secondary combustors defined by the secondary combustion chambers and set of secondary fuel nozzles are a rich burn system.

The combustion section of any preceding clause, wherein a primary combustor defined by the primary combustion chamber and the primary fuel nozzles are a lean burn system, and wherein a set of secondary combustors defined by the secondary combustion chambers and set of secondary fuel nozzles are a lean burn system.

The combustion section of any preceding clause, wherein each secondary combustor of the set of secondary combustors is controllable a rich burn combustion system and a lean burn combustion system.

The combustion section of any preceding clause, wherein the set of secondary combustors is controllable a rich burn combustion system and a lean burn combustion system.

The combustion section of any preceding clause, wherein the multiple mixer tubes form a cluster of mixer tubes.

The combustion section of any preceding clause, wherein the primary combustion chamber includes a primary combustor length measured from the dome wall to a primary combustor outlet and a primary combustion height measured radially across the primary combustion chamber from the inner liner to the outer liner, wherein the primary combustion height is in a range from 1.1 to 10 times a dome inlet diameter measured across the dome inlet.

The combustion section of any preceding clause, wherein the at least one opening is located at an end of the secondary combustion chamber, where the end is an axial distance from the dome wall, and wherein the axial distance is in a range of 0% to 70% of the primary combustor length.

The combustion section of any preceding clause, wherein the primary combustion chamber includes a primary outlet centerline defined by the primary combustor outlet, and wherein a radially distance between the at least one opening and the primary outlet centerline is in a range of 30% to 100% of the primary combustion height.

The combustion section of any preceding clause, wherein the primary fuel nozzle defines a rich cup and a cluster of secondary mixer tubes define a plurality of lean cups.

The combustion section of any preceding clause, wherein the secondary combustion chamber is a set of secondary combustion chambers having a forward secondary combustion chamber and an aft secondary combustion chamber, axially spaced from the forward secondary combustion chamber.

The combustion section of any preceding clause, wherein the aft secondary combustion chamber fluidly couples to the primary combustion chamber at an aft opening and the forward secondary combustion chamber fluidly couples to the primary combustion chamber at a forward opening.

The combustion section of any preceding clause, wherein the forward opening and the aft opening axially align.

The combustion section of any preceding clause, wherein the first centerline CL1passes through at least a portion of the forward opening or the aft opening.

The combustion section of any preceding clause, wherein the forward opening and the aft opening are axially offset from each other.

A turbine engine comprising a compressor section, a combustion section, and a turbine section in serial flow arrangement along an engine centerline, the combustion section comprising a primary combustor liner including an inner liner and an outer liner, a dome wall extending between the inner liner and the outer liner, a primary combustion chamber defined at least in part by the inner liner, the outer liner, and the dome wall, a primary fuel nozzle having an outlet at the dome wall, wherein the outer liner defines at least one opening aft of the dome wall, wherein the outlet of the primary fuel nozzle is fluidly coupled with the primary combustion chamber, a secondary combustion chamber defined at least in part by a secondary combustor liner, the secondary combustion chamber fluidly coupled to the primary combustion chamber at the at least one opening, and a set of secondary fuel nozzles comprising multiple mixer tubes having outlets at the secondary combustor liner, wherein the outlets of the mixer tubes are fluidly coupled with the secondary combustion chamber.

The turbine engine of any preceding clause, wherein the secondary combustion chamber extends from the outer liner in a radially outward direction.

The turbine engine of any preceding clause, where the primary fuel nozzle defines a first mixer tube centerline and the opening defines a second centerline, wherein an angle between the first mixer tube centerline and the second centerline is in a range from 30 degrees to 150 degrees.

The turbine engine of any preceding clause, wherein the primary combustion chamber or the secondary combustion chamber have a phi (equivalence ratio) in a range from 0.4 to 2.

The turbine engine of any preceding clause, wherein the primary combustion chamber and the secondary combustion chamber have a phi (equivalence ratio) in a range from 0.4 to 2.