Combustion section having primary combustion chamber and secondary combustion chamber

Abstract

A combustion section of a turbine engine has a primary combustion chamber and a secondary combustion chamber. The primary combustion chamber is at least partially defined by the combustor liner and the domed wall. A primary fuel nozzle having an outlet is located at the domed wall, wherein the outlet of the primary fuel nozzle is fluidly coupled with the primary combustion chamber. At least one opening in the outer liner axially rearward of the domed wall fluidly couples the secondary combustion chamber and the primary combustion chamber. A set of secondary fuel nozzles is fluidly coupled with the secondary combustion chamber.

Description

Technical Field

[0001] The present subject matter relates generally to a combustion section of a turbine engine and, more particularly, to a combustion section having a primary combustion chamber and a secondary combustion chamber. Background Art

[0002] The turbine engine is driven by the flow of combustion gases through the engine to rotate a plurality of turbine blades, which in turn rotate the compressor, thereby providing compressed air to the combustor for combustion. The combustor may be disposed within the turbine engine and fluidly coupled to the turbine into which the combustion gases flow.

[0003] It is known to use hydrocarbon fuels in the combustors of turbine engines. Typically, air and fuel are fed into a combustion chamber, the air is mixed with the fuel, and the fuel is then burned in the presence of air to produce hot gases. The hot gases are then fed into a turbine where they are cooled and expanded to produce power. Byproducts of the fuel combustion typically include environmentally harmful byproducts such as nitrogen oxides and nitrogen dioxide (collectively referred to as NO X ), carbon monoxide (CO), unburned hydrocarbons (UHC) (e.g., methane and volatile organic compounds that contribute to the formation of atmospheric ozone), and other oxides including sulfur oxides (e.g., SO2 and SO3).

[0004] Various fuels are being explored for combustion in turbine engines. Hydrogen or hydrogen mixed with another element or compound can be used for combustion, but hydrogen or hydrogen-blended fuels can result in higher flame temperatures than traditional fuels. That is, hydrogen or hydrogen-blended fuels generally have a wider flammability range and faster burning speed than traditional fuels (such as petroleum-based fuels or petroleum-synthetic fuel blends).

[0005] Standards stemming from global air pollution issues regulate NOx generated by turbine engine operation. X , UHC and CO emissions. In particular, NO is formed in the burner due to the high burner flame temperature during operation. X It is expected that NOx can be reduced by adjusting the temperature distribution and / or flame pattern within the burner. X emissions while still maintaining desired efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In the attached figure:

[0007] Figure 1 It is a schematic diagram of a turbine engine.

[0008] Figure 2 The combustion section of a turbine engine having a primary combustor and a set of secondary combustors is depicted along Figure 1 Cross-sectional view along line II-II.

[0009] Figure 3 Depicts the Figure 2 Schematic cross-sectional view of a primary burner and a secondary burner in the group of secondary burners, taken along line III-III.

[0010] Figure 4 According to the aspects disclosed herein Figure 2 A cross-sectional view of another embodiment of a combustion section of FIG.

[0011] Figure 5 The secondary burner according to the aspects disclosed herein is Figure 4 Schematic cross-sectional view along line VV of .

[0012] Figure 6 The secondary burner according to the aspects disclosed herein is provided with a small dome wall along the Figure 4 Schematic cross-sectional view along line VI-VI.

[0013] Figure 7 According to the aspects disclosed herein Figure 2 Schematic cross-sectional view of yet another embodiment of a combustion section of .

[0014] Figure 8 According to the aspects disclosed herein Figure 7 A portion of the outer liner of the primary combustion section along Figure 7 Schematic cross-sectional view along line VIII-VIII of .

[0015] Figure 9 According to the aspects disclosed herein Figure 7 Schematic cross-sectional view of another embodiment of a portion of an outer liner of a primary combustion section.

[0016] Figure 10 According to the aspects disclosed herein Figure 1 A schematic cross-sectional view of another embodiment of a combustion section of a turbine engine having a primary combustor and a set of secondary combustors.

[0017] Figure 11 According to the aspects disclosed herein Figure 1 A schematic cross-sectional view of yet another embodiment of a combustion section of a turbine engine having a primary combustor and a set of secondary combustors.

[0018] Figure 12 According to the aspects disclosed herein Figure 11 Schematic cross-sectional view of the primary burner taken along line XII-XII.

[0019] Figure 13 According to the aspects disclosed herein Figure 11Schematic cross-sectional view of another embodiment of a primary burner. DETAILED DESCRIPTION

[0020] Aspects of the disclosure described herein relate to a combustion section, particularly a combustion section having a primary combustor and a set of secondary fuel nozzles, the primary combustor having a primary combustion chamber fluidly coupled to at least the primary fuel nozzles. The set of secondary fuel nozzles can be fluidly coupled to the secondary combustion chamber, wherein the secondary combustion chamber is fluidly coupled to the primary combustion chamber at an opening in an outer liner. The set of secondary fuel nozzles can be arranged in multiple dimensions to form a fuel nozzle cluster or array.

[0021] For purposes of illustration, the present disclosure will be described with respect to a turbine engine. However, it will be understood that the disclosed aspects described herein are not limited thereto, and that the combustion sections described herein may be implemented in engines including, but not limited to, turbojets, turboprops, turboshafts, and turbofans. The disclosed aspects discussed herein may have general applicability in non-aircraft engines having combustors, such as in other mobile applications and non-mobile industrial, commercial, and residential applications.

[0022] As used herein, the word "exemplary" means "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Furthermore, unless expressly stated otherwise, all embodiments described herein should be considered exemplary.

[0023] 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 indicate the position or importance of each component.

[0024] The terms "fore" and "aft" refer to relative positions within a gas turbine engine or vehicle and refer to the normal operating attitude of the gas turbine engine or vehicle. For example, for a gas turbine engine, the front position refers to the position closer to the engine inlet, while the aft position refers to the position closer to the engine nozzle or exhaust.

[0025] As used herein, the term "upstream" refers to a direction opposite to the direction of fluid flow, while the term "downstream" refers to a direction in the same direction as the direction of fluid flow. The terms "forward" or "front" mean in front of something, and "rearward" or "rear" mean behind something. For example, when used in relation to fluid flow, forward / front can refer to upstream, and rearward / rear can refer to downstream.

[0026] The term "fluid" may be a gas or a liquid. The terms "fluid coupling" and "fluidically coupled" refer to the ability of a fluid to establish a connection between designated areas.

[0027] Furthermore, as used herein, the term "radial" or "radially" refers to directions away from a common center. For example, in the overall context of a turbine engine, radial refers to directions along a ray extending between the central longitudinal axis of the engine and the periphery of the engine.

[0028] All directional references (e.g., radial, axial, proximal, distal, up, down, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, backward, etc.) may be used for identification purposes to help the reader understand the present disclosure and do not create limitations, particularly with respect to the position, orientation, or use of the disclosed aspects described herein. Connection references (e.g., attach, couple, connect, and join) may be used and will be interpreted broadly and may include intermediate structural elements between a collection of elements and relative movement between elements, unless otherwise indicated. Therefore, a connection reference does not necessarily mean that two elements are directly connected and fixed relative to each other. The exemplary figures are for illustrative purposes only, and the dimensions, positions, orders, and relative sizes reflected in the accompanying figures may vary.

[0029] Unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural references. Also, as used herein, the term "set" or "a group of" elements can refer to any number of elements, including only one.

[0030] As used herein, the term "array" is a two-dimensional ordered sequence or arrangement. That is, the array has rows and columns that can be staggered or aligned in any desired pattern.

[0031] As used herein, the term "cluster" is a group of objects that are closely arranged together in two dimensions. As a non-limiting example, a fuel nozzle cluster is a group of at least two fuel nozzles arranged together such that the fuel nozzles in the cluster have a cluster distance between them that is at least 5% smaller than the distance between the fuel nozzles in the cluster and the fuel nozzles not in the cluster.

[0032] Figure 1 is a schematic diagram of a turbine engine 10. As a non-limiting example, the turbine engine 10 may be used within an aircraft. The turbine engine 10 may include at least a compressor section 12, a combustion section 14, and a turbine section 16. A drive shaft 18 rotationally couples the compressor section 12 and the turbine section 16 so that rotation of one affects rotation of the other and defines an axis of rotation or centerline 20 of the turbine engine 10.

[0033] The compressor section 12 may include a low-pressure (LP) compressor 22 and a high-pressure (HP) compressor 24 fluidly coupled in series with each other. The turbine section 16 may include an LP turbine 26 and an HP turbine 28 fluidly coupled in series with each other. The drive shaft 18 may operably couple the LP compressor 22, the HP compressor 24, the LP turbine 26, and the HP turbine 28 together. Alternatively, the drive shaft 18 may include an LP drive shaft (not shown) and an HP drive shaft (not shown). The LP drive shaft may couple the LP compressor 22 to the LP turbine 26, and the HP drive shaft may couple the HP compressor 24 to the HP turbine 28. The LP spool may be defined as the combination of the LP compressor 22, the LP turbine 26, and the LP drive shaft, such that rotation of the LP turbine 26 may apply driving force to the LP drive shaft, which in turn may rotate the LP compressor 22. The HP spool may be defined as the combination of the HP compressor 24, the HP turbine 28, and the HP drive shaft, such that rotation of the HP turbine 28 may apply driving force to the HP drive shaft, which in turn may rotate the HP compressor 24.

[0034] The compressor section 12 may 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 section 12 may be mounted to a disk, which is mounted to the drive shaft 18. Each set of blades for a given stage may have its own disk. The vanes of the compressor section 12 may be mounted to a casing, which may extend circumferentially around the turbine engine 10. It should be understood that the representation of the compressor section 12 is merely schematic and that there may be any number of stages. Further, it is contemplated that there may be any other number of components within the compressor section 12.

[0035] Similar to the compressor section 12, the turbine section 16 may 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 section 16 may be mounted to disks, which are mounted to the drive shaft 18. Each set of blades for a given stage may have its own disk. The vanes of the turbine section 16 may be mounted to the casing in a circumferential manner. It should be noted that there may 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 may be any other number of components within the turbine section 16.

[0036] The combustion section 14 may be disposed in series between the compressor section 12 and the turbine section 16. The combustion section 14 may be fluidly coupled to at least a portion of the compressor section 12 and the turbine section 16 such that the combustion section 14 at least partially fluidly couples the compressor section 12 to the turbine section 16. As a non-limiting example, the combustion section 14 may be fluidly coupled to the HP compressor 24 at an upstream end of the combustion section 14 and to the HP turbine 28 at a downstream end of the combustion section 14.

[0037] During operation of the turbine engine 10, ambient or atmospheric air is drawn into the compressor section 12 via a fan (not shown) upstream of the compressor section 12, where it is compressed, defining pressurized air. The pressurized air may then flow into the combustion section 14, where it is mixed with fuel and ignited, thereby generating combustion gases. The HP turbine 28 extracts some work from these combustion gases, which drives the HP compressor 24. The combustion gases are exhausted to the LP turbine 26, which extracts additional work to drive the LP compressor 22, and the exhaust gases are ultimately exhausted from the turbine engine 10 via an exhaust section (not shown) downstream of the turbine section 16. The drive of the LP turbine 26 drives the LP spool, which rotates the fan (not shown) and the LP compressor 22. Together, the pressurized airflow and the combustion gases may define the working airflow flowing through the fan, compressor section 12, combustion section 14, and turbine section 16 of the turbine engine 10.

[0038] Figure 2 The combustion section 14 is depicted along Figure 1 The combustion section 14 may include a cross-sectional view of the line II-II of the turbine engine 10 ( Figure 1 ). An annular arrangement of primary fuel nozzles 30 is provided about a centerline 20 of the primary fuel nozzles. Each of the primary fuel nozzles (illustrated as a group of primary fuel nozzles 30 as an example) is fluidly coupled to a primary combustor 32. It should be understood that the annular arrangement of fuel nozzles may be one or more fuel nozzles, and one or more fuel nozzles in the group of primary fuel nozzles 30 may have different characteristics.

[0039] Depending on the type of engine in which the primary combustor 32 is located, the primary combustor 32 may have a can shape, a can annular shape, or an annular arrangement. In a non-limiting example, an annular arrangement is shown and disposed within a casing 36. The primary combustor 32 is defined by a primary combustor liner 38, which includes an outer liner 40 and an inner liner 42 that are concentric relative to each other and annularly surround the centerline 20. A dome wall 44, together with the primary combustor liner 38, defines a primary combustion chamber 46 that is annularly surrounds the centerline 20. A compressed air passage 48 may surround the primary combustor 32 and be at least partially defined by the casing 36.

[0040] The combustion section 14 also includes a set of secondary combustors 50 comprising a circumferential arrangement of discrete small combustors 34. As used herein, "small" means that the component referenced by the term small is smaller than a corresponding similar component without the term small (i.e., the discrete small combustor 34 is smaller than the primary combustor 32). Each discrete small combustor 34 in the set of secondary combustors 50 is defined by a secondary combustor liner 52. As an example, the secondary combustor liner 52 is shown as extending generally perpendicularly from the primary combustor liner 38. The term "generally perpendicular" is defined as an angle equal to 85 degrees, 95 degrees, or between 85 and 95 degrees. Although shown at a 90-degree angle, it is contemplated that in different and non-limiting examples, the secondary combustor liner 52 may extend from the primary combustor liner 38 at any angle. It is further contemplated that each combustor in the set of secondary combustors 50 may correspond to a portion of the secondary combustor liner 52 , wherein the angle between each portion of the secondary combustor liner 52 and the primary combustor liner 38 may vary.

[0041] The secondary combustor liner 52 defines at least a portion of a secondary combustion chamber, which is exemplarily shown as a set of secondary combustors 54 circumferentially spaced about the centerline 20. The set of secondary combustors 54 extend from the outer liner 40 in a radially outward direction, or a direction away from the centerline 20. The set of secondary combustors 50 are fluidly coupled to the primary combustor 32 via at least one opening 58 extending through the outer liner 40. More specifically, each secondary combustor in the set of secondary combustors 54 terminates at an end 56 at the at least one opening 58 to define a secondary combustor outlet 60. In other words, the at least one opening 58 may be a plurality of openings, wherein each secondary combustor (circumferentially spaced apart) in the set of secondary combustors 50 is fluidly coupled to the primary combustor 46 at a corresponding opening 58 in the plurality of openings.

[0042] Although shown radially aligned with the primary fuel nozzles 30, the secondary combustor outlets 60 are axially downstream of the primary fuel nozzles 30. In other words, the primary fuel nozzles 30 and the dome wall are axially forward (into the page) of the at least one opening 58 in the outer liner 40.

[0043] The primary burner 32 produces a primary exhaust gas (indicated as "G1") in the primary combustion chamber 46. The set of secondary burners 50 produces a secondary exhaust gas (indicated as "G2") in the set of secondary combustion chambers 54 that flows into the primary combustion chamber 46. The secondary exhaust gas G2 circulates in the primary combustion chamber 46, thereby reducing or depleting the O2 level. This results in NO X The secondary exhaust gas G2 can reduce the temperature in the primary combustion chamber 46, further reducing NO X emission.

[0044] It should be understood that the small burner 34 may include a gradually converging body 96 ( Figure 3 ). In addition, if Figure 2 As shown, the small burner 34 may have a cross-section of constant area throughout. Further contemplated are any combination of converging, diverging, constant burner bodies, or any combination contemplated herein.

[0045] Figure 3 Depicts the Figure 2 A schematic cross-sectional view taken along line III-III of FIG. 1 shows the combustion section 14 as viewed in a radial plane (denoted as "RP"). As can be seen more clearly, the small burners 34 open into the primary burner 32. The primary burner 32 is fluidly coupled to the turbine section 16 ( Figure 1 ) extends between the primary burner outlet 78.

[0046] The dome assembly 61 includes the dome wall 44 and houses the primary fuel nozzle 30. The primary fuel nozzle 30 can be fluidly coupled to the fuel inlet 62 via a fuel passage 64, which can be adapted to receive a primary fuel flow (designated "F1"). The primary fuel nozzle 30 terminates in a fuel nozzle outlet (also referred to herein as a dome inlet 66). In some embodiments, the primary fuel nozzle 30 can include a swirler 68 circumferentially arranged around the dome inlet 66. Optionally, a primary igniter 70 can be fluidly coupled to the primary combustion chamber 46.

[0047] The dome inlet diameter 71 is measured across the dome inlet 66. As an example, the dome inlet diameter 71 is shown as measured at the dome wall 44.

[0048] Aft wall 72 extends radially from end 56 to connect secondary combustor liner 52 to outer liner 40 . Secondary combustor liner 52 terminates at end 56 downstream of dome inlet 66 .

[0049] Alternatively, any number of dilution openings 74 may be located in the outer liner 40 or the inner liner 42, or in both the outer liner 40 and the inner liner 42 downstream of the mini-combustor 34. It is contemplated that the primary combustor liner 38 may be free of dilution openings at any location upstream of the mini-combustor 34. Alternatively, in a different and non-limiting example, one or more dilution openings may be located axially between the dome inlet 66 and the mini-combustor 34.

[0050] The small combustor 34 includes a small dome assembly 80 including a small dome wall 82 and a set of secondary fuel nozzles 84. As an example, the set of secondary fuel nozzles 84 is shown as having a plurality of mixer tubes 86. Alternatively, in a different and non-limiting example, the set of secondary fuel nozzles 84 may include a swirler (not shown).

[0051] Each mixer tube in the plurality of mixer tubes 86 includes a tube outlet 88. The set of mixer tubes 86 is fluidly coupled to the secondary combustion chamber 54 at the tube outlet 88.

[0052] Each of the plurality of mixer tubes 86 is defined by a wall 90. A fuel stream (designated "F2") and an air stream (designated "A") can be received by the plurality of mixer tubes 86. The fuel stream F2 and air stream A received into one or more portions of the plurality of mixer tubes 86 can be supplied through one or more openings 92 in the wall 90. As shown, for example, each of the plurality of mixer tubes 86 can have opposing air passages 92, with the fuel stream F1 injected into the center of each mixer tube. The air stream A can be positioned around the fuel stream F1 to keep the fuel away from the wall 90 of each mixer tube.

[0053] Optionally, a secondary igniter 94 is fluidly coupled to the secondary combustion chamber 54 .

[0054] It is contemplated that the mini-combustor 34 includes a gradually converging body 96. The gradually converging body 96 is defined as a portion of the mini-combustor 34 wherein a first cross-sectional area (designated as “CA1”) proximate the mini-dome wall 82 is greater than a second cross-sectional area (designated as “CA2”) proximate the secondary combustor outlet 60.

[0055] The fuel nozzle outlet or dome inlet 66 defines a first centerline (designated "CL1"). The opening 58 that fluidly couples the mini-burner 34 to the primary burner 32 defines a second centerline CL2. As shown, by way of example, the first centerline CL1 and the second centerline CL2 overlap. That is, the first centerline CL1 and the second centerline CL2 intersect to define a first primary burner angle 87 in radial plane RP. As shown, the first primary burner angle 87 may be 90°. Although shown as 90°, the first primary burner angle 87 may be in the range of 30° to 150°.

[0056] The primary burner length (designated "L1") is measured parallel to the first centerline CL1 between the dome wall 44 and the primary burner outlet 78. The primary combustion zone 76 is defined as the volume between the wall 44 and the second centerline CL2. M ”) is measured parallel to the first centerline CL1 from the dome wall 44 to the second centerline CL2. The main combustion length L M 5% to 90% of the primary burner length L1. More specifically, the main combustion length L M It may be in the range of 5% to 70%, 5% to 50% or 5% to 40% of the primary burner length L1.

[0057] The secondary combustor length (designated "L2") is measured parallel to the first centerline CL1 between the dome wall 44 and the end 56. The primary combustion chamber 46 has a radial dimension that extends from the outer liner 40 to the inner liner 42 and is referred to herein as the primary combustor height (designated "H"). The primary combustor height H may be measured proximate the dome wall 44. The primary combustion height H is in the range of 1.1 to 10 times the dome inlet diameter 71.

[0058] The secondary burner length L2 is in the range of 0% to 70% of the primary burner length L1. More specifically, the secondary burner length L2 may be in the range of 5% to 50% of the primary burner length L1.

[0059] Radial distance (denoted as "R M ”) is defined as the radial dimension extending from the first centerline CL1 to the secondary combustor outlet 60. The radial distance R M From 0.5H to 1.0H. In other words, the radial distance R M The measured values ​​are in the range of 50% to 100% of the primary burner height H.

[0060] During operation, compressed air (denoted as “C”) may be drawn from compressor section 12 ( Figure 1) is provided to the combustion section 14. The compressed air C can be split between the primary combustor 32 and the set of secondary combustors 50 to provide compressed air to the primary fuel nozzles 30 or the swirlers 68. The compressed air C can also form an airflow A that is provided to the plurality of mixer tubes 86 via openings 92 in the wall 90. As a non-limiting example, the primary combustor 32 can receive 50% to 90% of the compressed air C from the compressor section 12, while the set of secondary combustors 50 can receive between 10% and 50% of the compressed air C.

[0061] Alternatively, in a different and non-limiting example, the primary combustor 32 may receive 60% to 90% of the compressed air C from the compressor section 12, while the set of secondary combustors 50 may receive between 10% and 40% of the compressed air C. It is further contemplated that the primary combustor 32 may receive 70% to 90% of the compressed air C from the compressor section 12, while the set of secondary combustors 50 may receive between 10% and 30% of the compressed air C.

[0062] Alternatively, in yet another different and non-limiting example, the primary combustor 32 may receive 10% to 50% of the compressed air C from the compressor section 12 , while the set of secondary combustors 50 may receive between 50% and 90% of the compressed air C. It is further contemplated that the primary combustor 32 may receive 10% to 40% of the compressed air C from the compressor section 12 , while the set of secondary combustors 50 may receive between 60% and 90% of the compressed air C.

[0063] Compressed air C may be supplied to the primary fuel nozzle 30 and mixed with the primary fuel flow F1 to define a primary fuel / air mixture. The primary fuel nozzle 30 may dispense a premixed or partially premixed primary fuel / air mixture. Additionally, the fuel flow F1 may be a diffusion fuel without an air mixture before entering the primary combustion chamber 46.

[0064] The fuel provided to the primary fuel nozzles 30 and the plurality of mixer tubes 86 may include jet fuel natural gas or a more reactive fuel, such as a mixture of hydrogen (H2) and H2. In some embodiments, the turbine engine 10 ( Figure 1 ) can be started on conventional fuel using the set of secondary burners 50, where the secondary exhaust gas G2 ( Figure 2 ) propagates toward a primary combustion chamber 46, which may be fueled using conventional fuel or H2 fuel.

[0065] When the secondary exhaust gas G2 is directed to the primary combustion chamber 46, the primary exhaust gas G1 ( Figure 2 ) is mixed with the secondary exhaust gas G2, which reduces the O2 level in the primary combustion chamber 46, thereby reducing NO XEmissions. Fuel staging between the primary combustion chamber 46 and the secondary combustion chamber 54 reduces the fuel / air ratio in these stages of the combustion section 14, which helps to further reduce temperatures and NO X In contrast, a single-stage burner will have a relatively high fuel / air ratio and higher temperatures, which results in higher NO X emission.

[0066] Optionally, a set of secondary dilution openings 98 may be provided in the secondary combustor liner 52 to connect the compressed air passage 48 to the secondary combustion chamber 54. The set of secondary dilution openings 98 may be located behind the small combustor 34 to tailor the combustor outlet temperature distribution and mode factors associated with the small combustor 34 and the primary combustor 32.

[0067] As a non-limiting example, the primary fuel nozzle 30 may be a rich cup with a swirler 68. The rich cup may have a fuel / air ratio that is higher than the stoichiometric ratio. The primary fuel nozzle 30 and at least the main combustion zone 76 may define a primary combustion system. When the primary fuel nozzle 30 is a rich cup, the primary combustion system may be a rich-burn combustion system, wherein the rich-burn combustion system includes an overall fuel / air ratio that is higher than the stoichiometric fuel / air ratio.

[0068] Alternatively, in a different and non-limiting example, the primary fuel nozzle 30 may be a lean cup and the primary combustion system may be a lean-burn combustion system, where the lean-burn combustion system includes an overall fuel / air ratio that is lower than the stoichiometric fuel / air ratio.

[0069] It is also contemplated that the primary fuel nozzle is controllable between fuel rich and fuel lean, such that the primary fuel nozzle 30 includes at least one cup that can be either a rich cup or a lean cup depending on the controllable fuel supply.

[0070] The set of secondary fuel nozzles 84 and at least the secondary combustion chamber 54 can define a secondary combustion system. The set of secondary fuel nozzles 84 can include flames that can be premixed, partially premixed, or diffused. The set of secondary fuel nozzles 84 can include a lean cup, a rich cup, or a combination of lean and rich cups. Depending on the overall fuel / air ratio of the set of secondary fuel nozzles 84 and the resulting combustion temperature, the secondary combustion system can be a rich-burn combustion system or a lean-burn combustion system. It is also contemplated that one or more of the plurality of mixer tubes 86 defining the set of secondary fuel nozzles 84 can be pilot tubes. As used herein, the term "pilot tube" means a richer fuel / air mixture. That is, a pilot tube is a mixer tube that receives more fuel per unit of air than other mixer tubes in the set of mixer tubes. As non-limiting examples, the additional fuel per unit of air can be provided by one or more of the following: providing additional fuel to the mixer tube; incorporating a swirler, wherein the air and additional fuel are mixed via the swirler; or providing additional fuel via an opening in the tube outlet 88 surrounding the pilot tube. While the pilot tube is considered richer than the lean mixer tube, it is contemplated that the pilot tube may be either a rich or lean cup.

[0071] like Figure 2 As shown, the secondary combustion chamber 54 can be a group of circumferentially spaced secondary combustion chambers. Each secondary combustion chamber 54 in the group of secondary combustion chambers can create its own secondary combustion system. That is, in order to break up the circumferential dynamic pattern, some secondary combustion chambers can be relatively fuel rich, while other secondary combustion chambers can be relatively fuel lean.

[0072] It is contemplated that each of the secondary burners in the set of secondary burners is controllable between a rich combustion system and a lean combustion system. That is, during operation, each of the secondary burners in the set of secondary burners can be controlled to be relatively fuel rich or relatively fuel lean.

[0073] When the primary combustion system is combined with the secondary combustion system, the secondary combustion system at least deprives the primary combustion system of oxygen. X The lack or reduction of available oxygen reduces the NO X emission.

[0074] The equivalence ratio (phi "ф") of the primary combustion system or the secondary combustion system may be in the range of 0.4 to 2. When the primary combustion system and the secondary combustion system are lean-burn combustion systems, the equivalence ratio (phi "ф") of the primary combustion system or the secondary combustion system may be in the range of 0.4 to 0.8. As used herein, the equivalence ratio (phi "ф") is defined as the ratio of the fuel-oxidizer ratio to the stoichiometric fuel-oxidizer ratio.

[0075] Figure 4A cross-sectional view of another embodiment of the combustion section 114 as viewed in a radial plane (denoted as "RP") is depicted. The combustion section 114 is similar to Figure 3 thus, like parts will be identified by like numerals increased by 100, it being understood that the description of like parts of the combustion section 14 applies to the combustion section 114 unless otherwise stated.

[0076] The primary combustor 132 extends between the dome wall 144 and a primary combustor outlet 178 that is fluidly connected to the turbine section 16. The outer liner 140 is radially spaced from the inner liner 142 to define a primary combustion chamber 146 of the primary combustor 132. The dome assembly 161 includes the dome wall 144 and houses a set of primary fuel nozzles 130. As an example, the set of primary fuel nozzles 130 is shown as a plurality of primary mixer tubes 131. The plurality of primary mixer tubes 131 can be adapted to receive a primary fuel flow (denoted as "F1") and a primary air flow A1. The set of primary fuel nozzles 130 can terminate in a set of fuel outlets (also referred to herein as a set of dome inlets 166).

[0077] The primary combustion zone 176 is defined as the volume between the set of dome inlets 166 and a second centerline CL2 defined by the openings 58 of the discrete mini-combustors 34 or the mini-dome wall 82. During operation, each fuel nozzle in the set of primary fuel nozzles 130 can include a flame 133, which can be premixed, partially premixed, or diffused. The set of primary fuel nozzles 130 can include a lean cup, a rich cup, or a combination of lean and rich cups. The set of primary fuel nozzles 130 and at least the primary combustion zone 176 can define a primary combustion system. Depending on the overall fuel / air ratio of the set of primary fuel nozzles 130 and the resulting combustion temperature, the primary combustion system can be a rich-burn combustion system or a lean-burn combustion system. It is contemplated that one or more of the plurality of primary mixer tubes 131 of the set of primary fuel nozzles 130 can be a pilot tube. When viewed in radial plane RP, the set of primary fuel nozzles 130 is shown as having three fuel nozzles, however, any number of fuel nozzles is contemplated.

[0078] The secondary combustion chamber 54 is defined by the secondary combustor liner 52 and the small dome wall 82. The secondary combustion chamber 54 is fluidly coupled to the primary combustion chamber 146 at the opening 58 of the outer liner 140. During operation, each fuel nozzle in the set of secondary fuel nozzles 84 can include a flame 135, which can be premixed, partially premixed, or diffused. The plurality of mixer tubes 86 can be lean cups, rich cups, or a combination of lean cups and rich cups. It is also contemplated that one or more of the plurality of mixer tubes 86 can be pilot tubes. As a non-limiting example, the plurality of mixer tubes 86 can be lean, and the flames 135 can be clusters or arrays of micro flames.

[0079] The set of secondary fuel nozzles 84 is shown as having three fuel nozzles when viewed in radial plane RP, however, any number of fuel nozzles is contemplated.

[0080] The primary and secondary combustion systems of the combustion section 114 may be lean-burn combustion systems. It is contemplated that, while the primary and secondary combustion systems are lean-burn combustion systems, one or more of the fuel nozzles in the set of primary fuel nozzles 130 or one or more of the fuel nozzles in the set of secondary fuel nozzles 84 may be rich cups or pilot tubes.

[0081] Alternatively, in a different and non-limiting example, the primary combustion system may 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 nozzles 130 may include lean cups and rich cups.

[0082] Alternatively, in yet another different and non-limiting example, the secondary combustion system may 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 nozzles 130 may include lean cups and rich cups.

[0083] Figure 5 The combustion section 114 is depicted in FIG. Figure 2 The parallel transverse plane TP is shown along Figure 4 . Each of the plurality of mixer tubes 86 is defined by a wall 90. The fuel flow F2 and the air flow A can be received by the plurality of mixer tubes 86. The fuel F2 can be received into each of the plurality of mixer tubes 86 from one or more fuel openings 92a in the wall 90 defining the mixer tubes. In addition, the air flow A (compressed air flow C ( Figure 3 ) is received into one or more portions of the plurality of mixer tubes 86 supplied through one or more air openings 92b in the wall 90.

[0084] As shown, by way of example, the gradually converging body 96 may be formed in the transverse plane TP and the radial plane RP ( Figure 4 The third cross-sectional area (denoted as “CA3”) near the small dome wall 82 is larger than the fourth cross-sectional area (denoted as “CA4”) near the secondary burner outlet 60.

[0085] Alternatively, in a different and non-limiting example, the gradually converging body 96 may be gradually converging when viewed from a single plane. Furthermore, in yet another different and non-limiting example, the small burner 34 may have a cross-section of a constant area throughout. Any combination of converging, diverging, or constant burner bodies is further contemplated, or any combination contemplated herein.

[0086] The set of secondary fuel nozzles 84 is shown as having two fuel nozzles when viewed in transverse plane TP, however, any number of fuel nozzles is contemplated. More specifically, the set of secondary fuel nozzles 84 may include at least two or more nozzles located in or feasible within radial plane RP or transverse plane TP.

[0087] Figure 6 The combustion section 114 is depicted in Figure 4 A cross-sectional view of the small dome wall 82 coupled to the secondary combustor liner 52 taken along line VI-VI. Figure 6 The set of secondary fuel nozzles 84 is further illustrated, showing how the set of secondary fuel nozzles may be arranged into an array or cluster of fuel nozzles 84a, 84b. As an example, the eight fuel nozzles 84a, 84b shown may be arranged in rows and columns, wherein the rows or columns may have different numbers of fuel nozzles. In other words, the set of secondary fuel nozzles 84 may be staggered in at least two dimensions. That is, the set of secondary fuel nozzles 84 may include a plurality of fuel nozzles forming a cluster or array visible in more than one plane. Although shown as eight fuel nozzles 84a, 84b, the set of secondary fuel nozzles 84 may include any number of fuel nozzles. More specifically, the set of secondary fuel nozzles 84 may include two or more fuel nozzles.

[0088] Orienting the set of secondary fuel nozzles 84 into clusters of fuel nozzles 84a, 84b provides temperature control advantages. The clusters of fuel nozzles 84a, 84b can also provide a desired temperature gradient. Figure 5 The fuel / air mixture of each mixer tube in the ) can be selected or controlled individually. That is, one or more of the fuel nozzles can have the same or different fuel / air mixtures. It is also contemplated that multiple mixer tubes 86 ( Figure 5 ) in each mixer tube.

[0089] As a non-limiting example, fuel nozzle 84a (shown as a first subset of secondary fuel nozzles 84 forming part of an array or cluster) may be a lean cup. Fuel nozzle 84b (shown as a second subset of secondary fuel nozzles 84 forming part of an array or cluster) may be a pilot tube or a rich cup. Although two fuel nozzles 84b are shown, any number of secondary fuel nozzles 84 may form the second subset of fuel nozzles 84b.

[0090] It is contemplated that the fuel / air mixture of each secondary fuel nozzle in the set of secondary fuel nozzles 84 can be controlled so 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 in the set of secondary fuel nozzles 84 can be controlled so that a rich cup or a pilot tube can become a lean cup.

[0091] As an example, the second centerline CL2 (substantially perpendicular to the mini-dome wall 82) is shown centered within the group of secondary fuel nozzles 84. In other words, the second centerline CL2 is located at the geometric center point of the cluster of secondary fuel nozzles 84. Alternatively, other locations for the intersection of the second centerline CL2 and the mini-dome wall 82 are contemplated.

[0092] Figure 7 A cross-sectional view of yet another embodiment of a combustion section 214 as viewed in a radial plane (denoted as "RP") is depicted. Similar combustion sections 214 are similar to Figure 4 thus, like parts will be identified with like numerals further increased by 100, it being understood that the description of like parts of the combustion section 114 applies to the combustion section 214 unless otherwise stated.

[0093] The primary combustor 232 extends between a dome wall 244 and a primary combustor outlet 278 that is fluidly connected to the turbine section 16. The outer liner 240 is radially spaced from the inner liner 242 to define a primary combustion chamber 246 of the primary combustor 232. The dome assembly 261 includes the dome wall 244 and houses a set of primary fuel nozzles 230. The set of primary fuel nozzles 230 includes a set of fuel outlets 266. The set of fuel outlets 266 defines a first centerline (designated "CL1").

[0094] The combustion section 214 includes a set of secondary combustion chambers, which are shown as a front secondary combustion chamber 254a and a rear secondary combustion chamber 254b as an example. The front secondary combustion chamber 254a can be one of a set of discrete, circumferentially spaced front secondary combustion chambers. The rear secondary combustion chamber 254b can be one of a set of discrete, circumferentially spaced rear secondary combustion chambers, the rear secondary combustion chamber having a circumferential centerline axially spaced from the circumferential centerline of the front secondary combustion chamber.

[0095] A forward secondary combustion chamber 254a is defined by a forward secondary combustor liner 252a and a forward mini-dome wall 282a. A set of forward secondary fuel nozzles 284a are coupled to or received by the forward mini-dome wall 282a. A forward opening 258a in the outer liner 240 fluidly couples the forward secondary combustion chamber 254a to the primary combustion chamber 246.

[0096] Aft secondary combustion chamber 254b is defined by aft secondary combustor liner 252b and aft mini-dome wall 282b. A set of aft secondary fuel nozzles 284b are coupled to or received by aft mini-dome wall 282b. Aft opening 258b in outer liner 240 fluidly couples aft secondary combustion chamber 254b to primary combustion chamber 246.

[0097] The primary combustion zone 276 can be defined as the volume between the set of fuel outlets 266 of the set of primary fuel nozzles 230 and the forward centerline CL3 defined by the forward opening 258a in the outer liner 240 at the outlet of the forward discrete mini-combustor 234a. The set of primary fuel nozzles 230 can include a lean cup, a rich cup, or a combination of lean and rich cups. The set of primary fuel nozzles 230 and at least the primary combustion zone 276 can define a primary combustion system. Depending on the overall fuel / air ratio of the set of primary fuel nozzles 230 and the resulting combustion temperature, the primary combustion system can be a rich-burn combustion system or a lean-burn combustion system.

[0098] The front secondary combustion system can be defined by the front secondary combustion chamber 254a and the set of front secondary fuel nozzles 284a. The set of front secondary fuel nozzles 284a can include lean cups, rich cups, pilot tubes, or a combination of lean and rich cups. Depending on the overall fuel / air ratio of the set of front secondary fuel nozzles 284a and the resulting combustion temperature, the front secondary combustion system can be a rich-burn combustion system or a lean-burn combustion system.

[0099] The rear secondary combustion system can be defined by the rear secondary combustion chamber 234b and the set of rear secondary fuel nozzles 284b. The set of rear secondary fuel nozzles 284b can include lean cups, rich cups, pilot tubes, or a combination of lean and rich cups. Depending on the overall fuel / air ratio of the set of rear secondary fuel nozzles 284b and the resulting combustion temperature, the front secondary combustion system can be a rich burn combustion system or a lean burn combustion system.

[0100] Although shown as being of the same size, the front secondary combustion chamber 254a and the rear secondary combustion chamber 254b may have different volumes or cross-sectional shapes. In addition, one of the front secondary combustion chamber 254a or the rear secondary combustion chamber 254b may be an annular combustion chamber (see FIG. Figure 10 It is also contemplated that the set of front secondary fuel nozzles 284b or the set of rear secondary fuel nozzles 284b may include any number of fuel nozzles.

[0101] Figure 8 It is from Figure 7 Schematic diagram of a portion of the outer liner 240 as seen along line VIII-VIII in FIG. The axial direction (denoted as "AD") is parallel to the centerline 20 ( Figure 1), the radial direction (denoted as "RD") extends into the page and is perpendicular to the axial direction AD, and the circumferential direction (denoted as "CD") is perpendicular to the radial direction RD and the axial direction AD. The circumferential direction CD surrounds the engine centerline 20 ( Figure 1 ) and, when oriented in two dimensions as shown, extends up and down the page.

[0102] The forward opening 258a may be a group of forward openings 258b, wherein each forward opening corresponds to a discrete circumferentially spaced forward secondary combustion chamber. Each forward opening 258a in the group of forward openings 258a includes a corresponding forward centerline CL3.

[0103] The rear openings 258b can be a group of rear openings 258b, each of which corresponds to a discrete, circumferentially spaced rear secondary combustion chamber. As shown, the group of rear openings 258b is spaced apart from the group of front openings 258a in the axial direction AD. As shown, the group of front openings 258a and the group of rear openings 258b are axially aligned. Although shown as fully aligned, it is contemplated that at least a portion of the group of rear openings 258b may be axially aligned with at least a portion of the group of front openings 258a.

[0104] As shown, as an example, the first centerline CL1 can pass through at least a portion of the front opening 258a or the rear opening 258b. It is contemplated that the first centerline CL1 can intersect the third centerline CL3.

[0105] Alternatively, in a different and non-limiting example, the front and rear openings 258a, 258b may be positioned in the circumferential direction CD such that the first centerline CL1 does not align with or pass through any portion of the front and rear openings 258a, 258b.

[0106] Figure 9 A schematic cross-sectional view of another embodiment of a portion of an outer liner 340 is depicted, similar to Figure 8 A portion of the outer liner 240 is shown, and therefore, like parts will be identified with like numerals further increased by 100, and it should be understood that unless otherwise specified, the description of like parts of a portion of the outer liner 240 applies to a portion of the outer liner 340.

[0107] The at least one forward opening may be a set of forward openings 358a, wherein each forward opening corresponds to a discrete circumferentially spaced forward secondary combustion chamber. Each forward opening in the set of forward openings 358a may include a corresponding forward centerline CL3.

[0108] The aft openings may be a group of aft openings 358b, each of which corresponds to a discrete circumferentially spaced aft secondary combustion chamber. As shown, the group of aft openings 358b is spaced apart from the group of forward openings 358a in the axial direction AD. As shown, the group of forward openings 358a and the group of aft openings 358b are axially offset from each other.

[0109] As shown in the figure, as an example, the third center line CL3 is located between adjacent first center lines CL1.

[0110] A first axial distance (designated as "S1") can be measured between one of the front openings 358a and one of the rear openings 358b in the axial direction AD. As shown by a second axial distance (designated as "S2"), the axial distances between the front opening 358a and the rear opening 358b can be equal, however, in various and non-limiting examples, it is contemplated that the first axial distance S1 and the second axial distance S2 can be different.

[0111] Figure 10 A cross-sectional view of another embodiment of a combustion section 414 is depicted as viewed in a transverse plane (denoted as "TP"). The combustion section 414 includes a portion of the combustion section 414 surrounding the turbine engine 10 ( Figure 1 ) is an annular arrangement of primary fuel nozzles 430 disposed about the centerline 20 of the primary combustion engine. Each of the primary fuel nozzles 430 is fluidly coupled to a primary combustor 432. It should be understood that the annular arrangement of fuel nozzles may include one or more fuel nozzles, and that one or more of the primary fuel nozzles 430 may have different characteristics. Depending on the type of engine in which the primary combustor 432 is located, the primary combustor 432 may have a can shape, a can annular shape, or an annular arrangement. In a non-limiting example, an annular arrangement is shown and disposed within a casing 436. The primary combustor 432 is defined by a primary combustor liner 438, which includes an outer liner 440 and an inner liner 442 that are concentric relative to each other and annularly surrounding the centerline 20. A dome wall 444, together with the primary combustor liner 438, defines a primary combustion chamber 446 that is annularly surrounding the centerline 20. A compressed air passage 448 may surround the primary combustor 432 and be at least partially defined by the casing 436.

[0112] Combustion section 414 also includes a set of secondary combustors 450, including annular small combustors 434. Annular small combustors 434 are defined by a secondary combustor liner 452 that is concentric with outer liner 440 and inner liner 442 and annularly surrounds centerline 20. Secondary combustor liner 452, together with outer liner 440, defines at least a portion of a secondary combustion chamber 454 that is circumferentially arranged about centerline 20. Annular small combustors 434 open into primary combustor 432. More specifically, secondary combustor liner 452 terminates at end 456 axially downstream of primary fuel nozzle 430.

[0113] The primary burner 432 produces a primary exhaust gas (designated as "G1") in the primary combustion chamber 446. The set of secondary burners 450 produces a secondary exhaust gas (designated as "G2") in the secondary combustion chamber 454, which flows into the primary combustion chamber 446. The secondary exhaust gas G2 circulates in the primary combustion chamber 446, depleting the O2 level and reducing the temperature in the primary combustion chamber 446. This results in NO X Reduction of emissions.

[0114] It is conceivable that Figure 3 、 Figure 4 or Figure 7 The cross section shown in may be a cross section of a portion of the combustion section 414. That is, the secondary combustion chamber 54, the front secondary combustion chamber 254a, or the rear secondary combustion chamber 254b may be an annular combustion chamber rather than a set of discrete secondary combustion chambers.

[0115] In the case of an annular mini-combustor 434, the circumferential fuel supply can be varied to make some exhaust gases hotter than others, thereby circumferentially varying the heat release rate. In other words, the fuel supplied to each secondary fuel nozzle in the set of secondary fuel nozzles, or to the cluster of secondary fuel nozzles surrounding the annular mini-combustor 434, is controllable. By circumferentially controlling the fuel supply, the temperature can be varied or adjusted at different portions of the annular mini-combustor 434. In other words, each secondary fuel nozzle, each cluster of secondary mixer tubes, or each secondary mixer tube is controllable between fuel-rich and fuel-lean.

[0116] Figure 11 A cross-sectional view of yet another embodiment of a combustion section 514 as viewed in a transverse plane (denoted as "TP") is depicted. The combustion section 514 includes a portion of the combustion section 514 surrounding the turbine engine 10 ( Figure 1) is an annular arrangement of primary fuel nozzles 530 disposed about the centerline 20 of the engine. Each of the primary fuel nozzles 530 is fluidly coupled to a primary combustor 532. It should be understood that the annular arrangement of fuel nozzles may be one or more fuel nozzles, and that one or more of the primary fuel nozzles 530 may have different characteristics. Depending on the type of engine in which the primary combustor 532 is located, the primary combustor 532 may have a can shape, a can annular shape, or an annular arrangement. In a non-limiting example, an annular arrangement is shown and disposed within a casing 536. The primary combustor 532 is defined by a primary combustor liner 538, which includes an outer liner 540 and an inner liner 542 that are concentric relative to each other and annularly surrounding the centerline 20. A dome wall 544, together with the primary combustor liner 538, defines a primary combustion chamber 546 that is annularly surrounding the centerline 20. A compressed air passage 548 may be located between at least a portion of the casing 536 and the primary combustor 532.

[0117] The combustion section 514 also includes a set of secondary fuel nozzles 584 axially downstream of the primary fuel nozzles 530. The set of secondary fuel nozzles 584 includes a cluster of mixer tubes, shown as mixer tubes 541, 543, 545. The mixer tubes 541, 543, 545 are fluidly coupled to the primary combustion chamber 546 at the outer liner 540. The mixer tubes 541, 543, 545 can extend through the casing 536 and the outer liner 540. Alternatively, in another different and non-limiting example, the mixer tubes 541, 543, 545 can be defined by the casing 536. Alternatively, in yet another different and non-limiting example, the mixer tubes 541, 543, 545 can be located within the outer liner 540, with air and fuel provided to the mixer tubes 541, 543, 545 via conduits (not shown) passing through the casing 536.

[0118] While each primary fuel nozzle 530 is shown as corresponding to a corresponding set of secondary fuel nozzles 584, it is contemplated that the set of secondary fuel nozzles 584 may be circumferentially arranged or located at any point on the outer liner 540. That is, in various and non-limiting examples, the set of secondary fuel nozzles 584 may be circumferentially spaced or distributed about the centerline 20 by equal arc lengths.

[0119] The primary burner 532 produces a primary exhaust gas (designated as "G1") in the primary combustion chamber 546. The set of secondary fuel nozzles 584 produces a micro-flame in the primary combustion chamber 546. The micro-flame consumes some of the O2 in the primary combustion chamber 546, reducing the O2 level and thereby reducing NO X emission.

[0120] Figure 12 Depicts the Figure 11Schematic cross-sectional view taken along line XII-XII of FIG. 5 shows the combustion section 514 as viewed in a radial plane (designated "RP"). As can be seen more clearly, the set of secondary fuel nozzles 584 opens into the primary combustor 532. The primary combustor 532 is fluidly coupled to the turbine section 16 ( Figure 1 ) extends between the primary burner outlet 578.

[0121] The dome assembly 561 includes a dome wall 544 and houses a set of primary fuel nozzles 530. As an example, the set of primary fuel nozzles 530 is shown as a plurality of primary mixer tubes 531. The plurality of primary mixer tubes 531 can be adapted to receive a primary fuel flow (designated "F1") and a primary air flow A1. The set of primary fuel nozzles 530 can terminate in a set of fuel outlets (also referred to herein as a set of dome inlets 566).

[0122] As non-limiting examples, the set of primary fuel nozzles 530 may be one or more of a lean cup, a rich cup, or a pilot tube.

[0123] The set of secondary fuel nozzles 584 is located axially downstream of the dome wall 544. The mixer tube 543 may be upstream or in front of another mixer tube 547, and the mixer tubes 543 and 547 are at least a mixer tube 541 ( Figure 11 )、545( Figure 11 ), 543, 547 are part of a mixer tube cluster. The mixer tubes 543, 547 are fluidly coupled to the primary combustion chamber 546 at openings 558 of an outer liner 540 that partially defines the primary combustion chamber 546.

[0124] As non-limiting examples, the set of secondary fuel nozzles 584 can be one or more of a lean cup, a rich cup, or a pilot tube. The equivalence ratio (phi "ф") of the combustion system including the primary combustor 546, the set of primary fuel nozzles 530, and the set of secondary fuel nozzles 584 can be in the range of 0.4 to 2.

[0125] The set of secondary fuel nozzles 584 generates a micro flame (denoted as "MF") in the primary combustion chamber 546. The micro flame MF consumes some of the O2 in the primary combustion chamber 546, reducing the O2 level and thereby reducing NO X emission.

[0126] The set of dome inlets 566 defines a first centerline (designated as "CL1"). One or more of the openings 558 that fluidly couple one of the set of secondary fuel nozzles 584 to the primary combustor 532 may define a second centerline CL2. The first centerline CL1 and the second centerline CL2 intersect to define an angle 587 in radial plane RP. As shown, angle 587 may be 90°. Although shown as a 90 degree angle, it is contemplated that in various and non-limiting examples, angle 587 may vary from 30° to 150°, as shown. Figure 13 As further shown in .

[0127] Figure 13 A schematic cross-sectional view of another embodiment of a combustion section 614 is depicted as viewed in a radial plane (denoted as "RP"). The combustion section 614 is similar to Figure 12 thus, like parts will be identified with like numerals further increased by 100, it being understood that the description of like parts of the combustion section 514 applies to the combustion section 614 unless otherwise stated.

[0128] Primary combustor 632 is fluidly coupled to turbine section 16 at dome wall 644. Figure 1 ) extends between the primary burner outlet 678 of the dome assembly 661. The dome assembly 661 includes a dome wall 644 and houses a set of primary fuel nozzles 630. As an example, the set of primary fuel nozzles 630 is shown as a plurality of primary mixer tubes 631. The plurality of primary mixer tubes 631 can be adapted to receive a primary fuel flow (denoted as "F1") and a primary air flow A1. The set of primary fuel nozzles 630 can terminate in a set of fuel outlets (also referred to herein as a set of dome inlets 666). As non-limiting examples, the set of primary fuel nozzles 630 can be one or more of a lean cup, a rich cup, or a pilot tube.

[0129] Axially downstream of the dome wall 644 is a set of secondary fuel nozzles 684. The set of secondary fuel nozzles 684 may be mixer tubes 643, 647, 649, which are part of a mixer tube cluster. The mixer tubes 643, 647, 649 are fluidly coupled to the primary combustion chamber 646 at openings 658 of the outer liner 640 that partially defines the primary combustion chamber 646. As non-limiting examples, the set of secondary fuel nozzles 684 may be one or more of a lean cup, a rich cup, or a pilot tube.

[0130] It is envisioned that the primary combustor 632 includes a gradually converging body 696. The gradually converging body 696 is defined as a portion of the primary combustor 632 in which the front cross-sectional area (denoted as "FCA") is greater than the rear cross-sectional area (denoted as "ACA"). The front cross-sectional area FCA can be measured near the dome wall 644 or upstream of the set of secondary fuel nozzles 684. The rear cross-sectional area ACA can be measured downstream of the set of secondary fuel nozzles 684 or near the primary combustor outlet 678.

[0131] The set of domed inlets 666 defines a first centerline (designated "CL1"). The opening 658 may define a second centerline (designated "CL2"). The first centerline CL1 and the second centerline CL2 intersect to define an angle in radial plane RP. As shown, the angle may be less than 90°. Although shown as less than 90°, it is contemplated that, in various and non-limiting examples, the angle 687 may be in the range of 30° to 150°.

[0132] Benefits of angle 687 being different than 90° may include increasing turbulence of the air in primary combustor 632 , thereby further reducing O 2 in primary combustion chamber 646 .

[0133] Benefits of the gradually converging body 696 include reducing the residence time of the combustion section 614, which helps reduce NO X In addition, the converging primary burner 632 helps to penetrate the exhaust gas from the group of secondary fuel nozzles 684 (or secondary burners) to the middle of the primary burner 632. Having a smaller penetration height to reach the middle of the primary burner 632 enables the secondary exhaust gas G2 ( Figure 2 or Figure 11 ) and the large flow or primary exhaust gas G1 ( Figure 2 or Figure 11 ) of the desired mixture.

[0134] The benefits associated with the set of secondary burners in combination with the primary burner and the method described herein are that NOx can be reduced even in severe cycles with higher operating air pressures, higher temperatures, higher fuel / air ratios, and heating fuel. X Emissions. Typically, higher fuel / air ratios within the combustion system result in higher flame temperatures, which in turn results in higher NO X By having two combustion chambers within the combustion system, the fuel can be split between these chambers, thereby reducing the fuel / air ratio in each chamber, thereby achieving lower temperatures and therefore lower NO X By directing the combustion products from the secondary combustion into the primary combustion chamber, the O2 level in the primary combustion chamber can be reduced, thereby further reducing NOX Emissions. The combustion section herein can be operated using 100% H2 fuel.

[0135] The group of secondary fuel nozzles forms a smaller, compact flame structure in the secondary burner, which helps to reduce the length of the secondary burner. The smaller, multiple, compact flame structure also reduces NO X The set of secondary fuel nozzles distributes uniform temperature resulting from multiple flames and carbon emissions, with smaller flames having greater length behind the flame for CO burnout.

[0136] Although described with respect to a turbine engine, it should be understood that the combustor described herein may be used with a turbine engine having NOx emissions. X It should be understood that the application of the various aspects of the disclosure discussed herein may also be applied to engines having a propeller section or a fan and supercharger section, as well as turbojets and turbine engines.

[0137] To the extent not already described, the various features and structures of the various embodiments may be combined or substituted for one another as desired. The fact that a feature is not shown in all embodiments does not mean it cannot be shown in such a manner; rather, it is shown for the sake of brevity. Thus, various features of different embodiments may be mixed and matched as desired to form new embodiments, whether or not such new embodiments are explicitly described. All combinations or permutations of the features described herein are covered by this disclosure.

[0138] This written description uses examples to describe the 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 the various 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 language of the claims.

[0139] Further aspects are provided by the subject matter of the following clauses:

[0140] 19. The combustion section of a turbine engine, the combustion section comprising: a primary combustor liner, the primary combustor liner comprising an inner liner and an outer liner; a dome wall, the dome wall extending between the inner liner and the outer liner; a primary combustion chamber, the primary combustion chamber being at least partially defined by the inner liner, the outer liner and the dome wall, wherein the outer liner defines at least one opening behind the dome wall; a primary fuel nozzle, the primary fuel nozzle having an outlet at the dome wall, wherein the outlet of the primary fuel nozzle is fluidly coupled to the primary combustion chamber; a secondary combustion chamber, the secondary combustion chamber being at least partially defined by a secondary combustor liner, the secondary combustion chamber being fluidly coupled to the primary combustion chamber at the at least one opening; and a set of secondary fuel nozzles, the set of secondary fuel nozzles comprising a plurality of mixer tubes having outlets at the secondary combustor liner, wherein the outlet of the mixer tubes is fluidly coupled to the secondary combustion chamber.

[0141] 19. The combustion section of a turbine engine, comprising: a primary combustor liner comprising an inner liner and an outer liner; a dome wall extending between the inner liner and the outer liner; a primary combustion chamber at least partially defined by the inner liner, the outer liner and the dome wall, wherein the outer liner defines at least one opening behind the dome wall; a primary fuel nozzle having an outlet at the dome wall, wherein the outlet of the primary fuel nozzle is fluidly connected to the primary combustion chamber; and a set of secondary fuel nozzles, wherein the set of secondary fuel nozzles comprises a cluster of annularly spaced mixer tubes having outlets at the outer liner, wherein the outlet of the mixer tubes is fluidly connected to the primary combustion chamber.

[0142] The combustion section of any preceding clause, wherein at least one mixer tube of the plurality of mixer tubes is a pilot tube.

[0143] The combustion section of any preceding clause, wherein the primary fuel nozzle is a plurality of primary fuel nozzles.

[0144] The combustion section of any preceding clause, wherein the plurality of primary fuel nozzles comprises a plurality of primary mixer tubes, and wherein at least one primary mixer tube is a pilot tube.

[0145] The combustion section of any preceding clause, wherein the plurality of primary fuel nozzles includes at least one fuel rich cup.

[0146] The combustion section of any preceding clause, wherein the plurality of primary fuel nozzles includes at least one lean fuel cup.

[0147] A combustion section as in any preceding clause, wherein the primary fuel nozzle comprises at least one cup controllable between a fuel rich cup and a fuel lean cup.

[0148] A combustion section as in any preceding clause, wherein each primary fuel nozzle of the plurality of primary fuel nozzles comprises at least one cup controllable between a fuel rich cup and a fuel lean cup.

[0149] The combustion section of any preceding clause, wherein the at least one opening is defined by the secondary combustor liner.

[0150] A combustion section according to 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, wherein each secondary combustion chamber in the set of circumferential combustion chambers is fluidly coupled to the primary combustion chamber at each opening in the plurality of circumferentially spaced openings.

[0151] A combustion section as in any preceding clause, wherein the secondary combustion chamber is an annular combustion chamber defined in part by the outer liner.

[0152] A combustion section as in any preceding clause, wherein secondary mixer tube clusters are spaced circumferentially about the annular combustion chamber.

[0153] A combustion section as in any preceding clause, wherein the secondary mixer tube cluster is controllable between fuel rich and fuel lean.

[0154] The combustion section of any preceding clause, wherein a first centerline defined by the primary fuel nozzle overlaps a second centerline defined by the at least one opening.

[0155] 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.

[0156] The combustion section of any preceding clause, wherein the secondary combustion chamber is a plurality of secondary combustion chambers, and a set of secondary burners is defined by the plurality of secondary combustion chambers, and the set of secondary fuel nozzles is a lean burn system.

[0157] The combustion section of any preceding clause, wherein a primary combustor defined by the primary combustion chamber and the primary fuel nozzles is a lean burn system, and wherein a set of secondary combustors defined by the secondary combustion chamber and the set of secondary fuel nozzles is a rich burn system.

[0158] The combustion section of any preceding clause, wherein a primary burner defined by the primary combustion chamber and the primary fuel nozzles is a lean burn system, and wherein a set of secondary burners defined by the secondary combustion chamber and the set of secondary fuel nozzles is a lean burn system.

[0159] The combustion section of any preceding clause, wherein each secondary burner in the set of secondary burners is controllable between a rich burn combustion system and a lean burn combustion system.

[0160] The combustion section of any preceding clause, wherein the set of secondary burners is controllable between a rich burn combustion system and a lean burn combustion system.

[0161] The combustion section of any preceding clause, wherein the plurality of mixer tubes form a mixer tube cluster.

[0162] A combustion section according to any preceding clause, wherein the primary combustion chamber includes a primary burner length measured from the dome wall to the primary burner 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 the range of 1.1 to 10 times the dome inlet diameter measured across the dome inlet.

[0163] A combustion section according to any preceding clause, wherein the at least one opening is located at an end of the secondary combustion chamber, wherein the end is separated from the dome wall by an axial distance, and wherein the axial distance is in the range of 0% to 70% of the length of the primary combustor.

[0164] A combustion section according to any preceding clause, wherein the primary combustion chamber includes a primary outlet centerline defined by the primary burner outlet, and wherein the radial distance between the at least one opening and the primary outlet centerline is in the range of 30% to 100% of the primary combustion height.

[0165] A combustion section as in any preceding clause, wherein the primary fuel nozzle defines a rich cup and the secondary mixer tube cluster defines a plurality of lean cups.

[0166] A combustion section according to any preceding clause, wherein the secondary combustion chamber is a group of secondary combustion chambers having a leading secondary combustion chamber and a trailing secondary combustion chamber, the trailing secondary combustion chamber being axially spaced from the leading secondary combustion chamber.

[0167] A combustion section according to any preceding clause, wherein the rear secondary combustion chamber is fluidly coupled to the primary combustion chamber at a rear opening, and the front secondary combustion chamber is fluidly coupled to the primary combustion chamber at a front opening.

[0168] A combustion section as in any preceding clause, wherein the front opening and the rear opening are axially aligned.

[0169] A combustion section according to any preceding clause, wherein the first centreline CL1 passes through at least a portion of the front opening or the rear opening.

[0170] A combustion section as in any preceding clause, wherein the front opening and the rear opening are axially offset from one another.

[0171] 19. The turbojet engine of claim 18, wherein the exhaust gas fan is configured to exhaust gas streams from a first combustion chamber and a second combustion chamber, the exhaust gas fan being configured to exhaust gas streams from a first combustion chamber to a second combustion chamber. The exhaust gas fan is configured to exhaust gas streams from a first combustion chamber to a second combustion chamber. The exhaust gas fan is configured to exhaust gas streams from a first combustion chamber to a second combustion chamber.

[0172] A turbine engine according to any preceding clause, wherein the secondary combustion chamber extends from the outer liner in a radially outward direction.

[0173] The turbine engine of any preceding clause, wherein 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 the range of 30 degrees to 150 degrees.

[0174] A turbine engine according to any preceding clause, wherein the primary combustion chamber or the secondary combustion chamber has a phi (equivalence ratio) in the range of 0.4 to 2.

[0175] A turbine engine according to any preceding clause, wherein the primary combustion chamber and the secondary combustion chamber have a phi (equivalence ratio) in the range of 0.4 to 2.

Claims

1. A combustion section for a turbine engine, characterized in that: The combustion section comprises: a primary combustor liner, the primary combustor liner comprising an inner liner and an outer liner; a dome wall extending between the inner liner and the outer liner; a primary combustion chamber at least partially defined by the inner liner, the outer liner, and the dome wall, wherein the outer liner defines at least one opening rearward 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 to the primary combustion chamber; a secondary combustion chamber at least partially defined 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 includes a plurality of mixer tubes having outlets at the secondary combustor liner, wherein the outlets of the mixer tubes are fluidly coupled to the secondary combustion chamber.

2. The combustion section according to claim 1, characterized in that: in, At least one mixer tube of the plurality of mixer tubes is a pilot tube.

3. The combustion section according to claim 1, characterized in that: in, The primary fuel nozzle is a plurality of primary fuel nozzles.

4. The combustion section according to claim 3, characterized in that in, The plurality of primary fuel nozzles includes a plurality of primary mixer tubes, and wherein at least one of the primary mixer tubes is a pilot tube.

5. The combustion section according to claim 1, characterized in that: in, The secondary combustion chamber is a group of secondary combustion chambers having a front secondary combustion chamber and a rear secondary combustion chamber, and the rear secondary combustion chamber is axially spaced apart from the front secondary combustion chamber.

6. The combustion section according to claim 1, characterized in that in, 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, wherein each secondary combustion chamber in the set of circumferential combustion chambers is fluidly coupled to the primary combustion chamber at each opening in the plurality of circumferentially spaced openings.

7. The combustion section according to claim 1, characterized in that in, The secondary combustion chamber is an annular combustion chamber defined in part by the outer liner.

8. The combustion section according to claim 7, characterized in that in, Secondary mixer tube clusters are spaced circumferentially around the annular combustion chamber.

9. The combustion section according to claim 1, characterized in that in, A first centerline defined by the primary fuel nozzle overlaps a second centerline defined by the at least one opening.

10. The combustion section according to claim 1, characterized in that in, A primary combustor defined by the primary combustion chamber and the primary fuel nozzle is a rich-burning system.

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