DE102015122924A1 - Pilot nozzle in a gas turbine combustor - Google Patents

Abstract

A fuel nozzle for a gas turbine includes: an elongate centerbody; an elongated peripheral wall formed about the central body to define a primary flow annulus therebetween; a primary fuel supply and a primary air supply in fluid communication with an upstream end of the primary flow annulus; and a pilot nozzle. The pilot nozzle may be formed in the centerbody and include: axial elongated mixing tubes defined within a centerbody wall; a fuel port disposed on the mixing tubes for connection to each of a secondary fuel supply; and a secondary air supply configured to communicate with an inlet of each of the mixing tubes in fluid communication. Several of the mixing tubes may be formed as inclined mixing tubes that are adapted to create a swirling downstream flow, while a plurality of the mixing tubes may be oppositely inclined mixing tubes.

Description

BACKGROUND TO THE INVENTION

The present invention relates generally to a gas turbine combusting an air-mixed hydrocarbon fuel to produce a high-temperature gas stream that drives turbine blades to rotate a shaft connected to the blades. In particular, but not by way of limitation, the invention relates to combustor fuel jets containing pilot nozzles which premix a fuel and air to achieve lower nitrogen oxide levels.

Gas turbines are widely used to produce power for many applications. A conventional gas turbine includes a compressor, a combustor and a turbine. In a typical gas turbine, the compressor introduces compressed air to the combustion chamber. The entering into the combustion chamber air is mixed with fuel and burned. Hot combustion gases are exhausted from the combustion chamber and flow into the blades of the turbine to rotate the turbine shaft connected to the blades. Part of this mechanical energy of the rotating shaft drives the compressor and / or other mechanical systems.

Because government regulations disapprove of the release of nitrogen oxides into the atmosphere, it is desirable to keep their production as by-products of gas turbine operation below acceptable levels. One approach to meeting such regulations is to switch from diffusion flame combustors to combustors that use lean fuel-air mixtures in a fully premixed mode of operation to control emissions of, for example, nitrogen oxides (commonly denoted NOx) and carbon monoxide (CO). to reduce. These combustors are variously known in the art as dry low NOx (DLN) (dry low NO x), dry low emission (DLE) (dry low emission) or lean premixed (LPM) (lean premix) combustion systems.

Fuel-air mixing affects both the levels of nitrogen oxides produced in the hot combustion gases of a gas turbine and engine performance. A gas turbine may utilize one or more fuel nozzles to receive air and fuel to assist in fuel-air mixing in the combustion chamber. The fuel nozzles may be disposed in a head end of the combustion chamber and may be configured to receive an airflow that is mixed with a fuel input. Each fuel nozzle may typically be internally supported by a centerbody disposed within the fuel nozzle, and a pilot nozzle may be disposed at the downstream end of the centerbody. Such as in the U.S. Patent No. 6,438,961 which is incorporated herein by reference in its entirety for all purposes herein, a so-called swozzle (integrated swirler with nozzle) may be secured to the outside of the centerbody and located upstream of the pilot nozzle. The swozzle has curved vanes which extend radially from the centerbody over an annular flow channel and from which fuel is introduced into the annular flow channel to be entrained in a stream of air swirled by the vanes of the swozzle.

Various parameters describing the combustion process in the gas turbine correlate with the generation of nitrogen oxides. Higher gas temperatures in the combustion reaction zone are responsible, for example, for the generation of higher amounts of nitrogen oxide. One way to reduce these temperatures is to premix the fuel-air mixture and reduce the ratio of fuel to air that is burned. When the ratio of fuel to air that is burned is reduced, the amount of nitrogen oxides is also reduced. However, there is a trade-off in the performance of the gas turbine. For, if the ratio of fuel to air that is burned is reduced, there is an increased tendency for the flame of the fuel nozzle to go out, thus making the operation of the gas turbine unstable. A diffuser flame type pilot nozzle has been used for better flame stabilization in a combustor, but its use increases NOx emissions. Thus, there remains a need for improved pilot nozzle arrangements that provide flame stabilization benefits while also minimizing NOx emissions generally associated with pilot nozzles.

BRIEF DESCRIPTION OF THE INVENTION

The present application thus describes a fuel nozzle for a gas turbine. The fuel nozzle may include: an axially elongated centerbody; an axially elongated peripheral wall formed about the centerbody to define a primary flow annulus therebetween; a primary fuel supply and a primary air supply in fluid communication with an upstream end of the primary flow annulus; and a pilot nozzle. The pilot nozzle may be formed in the centerbody including: axially elongated mixing tubes disposed within a centerbody wall each of the mixing tubes extending between an inlet defined by an upstream end surface of the pilot nozzle and an outlet formed by a downstream end surface of the pilot nozzle; a fuel port disposed between the inlet and the outlet of each of the mixing tubes for communicating each of the mixing tubes with a secondary fuel supply; and a secondary air supply configured to be in fluid communication with the inlet of each of the mixing tubes. Several of the mixing tubes may be formed as inclined mixing tubes which are arranged, in particular angled with respect to the center axis of the fuel nozzle, to induce a swirling flow about the central axis in a common outlet therefrom. Several of the mixing tubes may be formed as oppositely inclined mixing tubes, which are arranged, in particular with respect to the center axis of the fuel nozzle angled to bring about in relation to the induced by the inclined mixing tubes swirling flow counter-rotating swirling downstream flow in a common outlet thereof.

In the aforementioned fuel nozzle, the inclined mixing tubes may be tangentially inclined with respect to the center axis of the fuel nozzle, and the common outlet may have a combined fuel and air outlet from the plurality of inclined mixing tubes, and the oppositely inclined mixing tubes may be tangentially skewed with respect to the center axis of the fuel nozzle and the common outlet may have a combined fuel and air outlet from the plurality of oppositely inclined mixing tubes.

In one embodiment, each of the slanted mixing tubes and the oppositely inclined mixing tubes may have an exit direction that is tangentially angled with respect to the center axis of the fuel nozzle, wherein the slanted mixing tubes may be configured such that the swirling flow of the common outlet swirls in the same direction a swirling flow caused by swirl vanes of the primary flow annulus.

In a further embodiment, the mixing tubes may each have an outlet portion having an axially narrow downstream portion of the mixing tube located adjacent to the outlet, the outlet portion defining a central axis therethrough, wherein the inclined mixing tubes may be configured such that a continuation of the Central axis of the outlet portion has an acute tangential exit angle with respect to a downstream continuation of the center axis of the fuel nozzle, and wherein the oppositely inclined mixing tubes may be configured such that a continuation of the central axis of the outlet portion has an acute tangential exit angle with respect to the downstream continuation of the center axis of the fuel nozzle.

In the last-mentioned fuel nozzle, the slanted mixing tubes of the pilot nozzle may each have a parallel arrangement with respect to each other, wherein the tangential exit angle of the slanted mixing tubes may have an angle between 10 ° and 70 ° and wherein the oppositely inclined mixing tubes of the pilot nozzle each have a parallel arrangement with respect to each other may have and wherein the tangential exit angle of the oppositely inclined mixing tubes may have an angle between 10 ° and 70 °.

Additionally or alternatively, the centerbody may include axially stacked portions including a forward portion having a secondary fuel supply and a secondary air supply and a rear portion configured as the pilot nozzle, the forward portion of the centerbody having an axially extending central portion Supply line and a secondary flow annulus formed around the central supply line, which extends axially between a connection made with an air source, which is provided in the direction of an upstream end of the center body, and the upstream end face of the pilot nozzle, and wherein the center body wall is an outer wall of the Center body can define and define an outer boundary of the secondary flow annulus.

Additionally, the primary flow annulus may include a swozzle having a plurality of swirler vanes extending radially across the entire primary annulus and fuel passages extending through the swirler vanes to fuel ports defined by an outer surface of the swirler vane to connect to a fuel plenum, wherein the swirler vanes may have an oblique tangential orientation with respect to the central axis to cause a downstream flow therefrom that swirls about the central axis in a first direction, the fuel opening of each of the inclined mixing tubes and the oppositely inclined mixing tubes may have a lateral fuel port for injecting fuel through an opening formed through a sidewall and the fuel port may have an upstream position relative to an air flow therethrough for each of the inclined mixing tubes and the oppositely inclined mixing tubes ,

In the last-mentioned fuel nozzle, the inclined mixing tubes and the oppositely inclined mixing tubes may each have a plurality of the fuel ports, wherein the plurality of fuel ports may have an upstream concentration relative to an air flow therethrough.

Additionally or alternatively, the inclined mixing tubes and the oppositely inclined mixing tubes may each be configured to receive airflow through the inlet and fuel flow through the fuel aperture to dispense a mixture thereof through the outlet, the outlet having a combustion chamber Combustion chamber may be in fluid communication, wherein the inclined mixing tubes may each have a mixing length defined between an upstream fuel opening and the outlet, wherein, in terms of mixing length, the inclined mixing tubes each have a segmented configuration, including an upstream segment and a downstream segment each side of a compound that marks a change of direction for the inclined mixing tube may have, and wherein the oppositely inclined mixing tubes each have a Mischlän ge, which is defined between an upstream fuel port and the outlet, and wherein, with respect to the mixing length, the oppositely inclined mixing tubes each have a segmented configuration, including an upstream segment and a downstream segment to each side of a compound, which is a change of direction for the marked oppositely inclined mixing tube, may have.

In one embodiment of the last-mentioned fuel nozzle, the inclined mixing tubes and the oppositely inclined mixing tubes may each have a configuration in which the upstream segment is linear and the downstream portion is curved.

In another embodiment, the inclined mixing tubes may each have a configuration in which the upstream segment is linear and axially aligned and the downstream segment is curved and spirally formed about the central axis of the fuel nozzle, and wherein the upstream portion is less than half the mixing length each of the inclined inclined mixing tubes, and wherein the oppositely inclined mixing tubes may each have a configuration in which the upstream segment is linear and axially aligned and the downstream segment is curved and spirally formed about the central axis of the fuel nozzle, and wherein the upstream portion is less than has half the mixing length of the oppositely inclined mixing tubes.

In yet another embodiment, the tangential exit angle of the inclined mixing tubes and the oppositely inclined mixing tubes can each have an angle between 20 ° and 55 °.

In a preferred embodiment, the inclined mixing tubes may be configured such that the swirling flow of the common outlet swirls in the first direction as defined by the direction of the swirling downstream flow created by the swirler vanes of the primary flow annulus.

In the last-mentioned preferred embodiment, the pilot nozzle may have between five and twenty-five of the inclined mixing tubes and between five and twenty-five of the oppositely inclined mixing tubes, wherein the inclined mixing tubes may be circumferentially spaced within the central body wall at regular intervals with the oppositely sloped mixing tubes within the Central body wall may be spaced at regular intervals in the circumferential direction and wherein the plurality of inclined mixing tubes may have an outward position with respect to the plurality of oppositely inclined mixing tubes.

As an alternative, the pilot nozzle may have between five and twenty five of the inclined mixing tubes and between five and twenty five of the oppositely inclined mixing tubes, wherein the inclined mixing tubes may be circumferentially spaced within the central body wall at regular intervals with the oppositely sloped mixing tubes within the central body wall at regular intervals Intervals may be spaced in the circumferential direction and wherein the plurality of inclined mixing tubes may have an internal position with respect to the plurality of oppositely inclined mixing tubes.

In the last mentioned preferred embodiment of the type in which the plurality of inclined mixing tubes have an outboard position with respect to the plurality of oppositely inclined mixing tubes, the plurality of inclined mixing tubes and the plurality of oppositely inclined mixing tubes may be the same The plurality of mixing tubes, wherein the downstream end face of the pilot nozzle may have an arrangement of the outlets, in which the outlets of the inclined mixing tubes are angularly registered with respect to the outlets of the oppositely inclined mixing tubes, and wherein the angular registration of the arrangement of outlets may have Outlets of the inclined mixing tubes are angularly offset with respect to the outlets of the oppositely inclined mixing tubes.

As an alternative, the plurality of inclined mixing tubes and the plurality of oppositely inclined mixing tubes may have the same number of mixing tubes, wherein the downstream end face of the pilot nozzle may have an arrangement of the outlets in which the outlets of the inclined mixing tubes are angularly registered with respect to the outlets of the oppositely inclined mixing tubes and wherein the angular registration of the arrangement of the outlets may have the outlets of the inclined mixing tubes arranged to be angularly coincident with the outlets of the oppositely inclined mixing tubes.

In the last-mentioned preferred embodiment of any kind mentioned above, the slanted mixing tubes may be radially inclined with respect to the center axis of the fuel nozzle, the slanted mixing tubes slanting radially outward from the fuel nozzle at an angle between 0.1 ° and 20 ° can be employed.

In an alternative, the inclined mixing tubes may be made radially inclined with respect to the center axis of the fuel nozzle, wherein the inclined mixing tubes may be inclined radially to an inward direction of the fuel nozzle at an angle between 0.1 ° and 20 °.

Further, the oppositely inclined mixing tubes may be radially inclined with respect to the center axis of the fuel nozzle, wherein the oppositely inclined mixing tubes may be inclined radially to an outward direction of the fuel nozzle at an angle between 0.1 ° and 20 °.

In an alternative, the oppositely inclined mixing tubes can be made radially obliquely with respect to the center axis of the fuel nozzle, wherein the oppositely inclined mixing tubes can be made radially obliquely to an inward direction of the fuel nozzle at an angle between 0.1 ° and 20 °.

In still some embodiments, the inclined mixing tubes may be radially inclined relative to the center axis of the fuel nozzle, and the oppositely inclined mixing tubes may be radially inclined with respect to the center axis of the fuel nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 12 illustrates a block diagram of an exemplary gas turbine in which embodiments of the present invention may be used; FIG.

2 FIG. 15 is a cross-sectional view of an exemplary combustor as shown in FIG 1 shown gas turbine can be used;

3 includes a view, partially in perspective and partially in cross section, showing an exemplary combustor nozzle according to certain aspects of the present invention;

4 illustrates a more detailed cross-sectional view of the combustion chamber from 3 ;

5 FIG. 11 illustrates an end view taken along in FIG 4 cut with 5-5 lines of sight;

6 contains a simplified side view of a mixing tube that can be used in a pilot nozzle;

7 FIG. 4 illustrates a simplified side view of an alternative mixing tube having an inclined configuration according to certain aspects of the present invention; FIG.

8th FIG. 12 is a cross-sectional view depicting an exemplary pilot nozzle having tilted mixing tubes in accordance with certain aspects of the present invention; FIG.

9 Figure 12 illustrates a side view of inclined mixing tubes according to an exemplary embodiment of the present invention;

10 contains a perspective view of the mixing tube 9 ;

11 Figure 11 illustrates a side view of inclined mixing tubes according to an alternative embodiment of the present invention;

12 shows a side view of a tilted mixing tube according to another alternative embodiment of the present invention;

13 illustrates a side view of another embodiment in which linear mixing tubes are combined with inclined mixing tubes;

14 contains a perspective view of the mixing tubes 13 ;

15 shows an inlet view of the mixing tubes 13 ;

16 illustrates an outlet view of the mixing tubes 13 ;

17 FIG. 11 illustrates a side view of another embodiment including counter-rotating spiral mixing tubes according to certain other aspects of the present invention; FIG.

18 contains a perspective view of the mixing tubes 17 ;

19 shows an inlet view of the mixing tubes 17 ;

20 illustrates an outlet view of the mixing tubes 17 ;

21 Figure 11 illustrates an outlet view of an alternative embodiment of the mixing tubes containing a component external to the exit direction;

22 Figure 11 illustrates an outlet view of an alternative embodiment of the mixing tubes containing a component internal to the exit direction;

23 schematically illustrates the results of a directional flow analysis of mixing tubes having a linear or axial orientation; and

24 schematically illustrates the results of a directional flow analysis of mixing tubes having a tangentially tilted orientation.

DETAILED DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned by practice of the invention. Reference will now be made in detail to the present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses terms in the form of numbers and letters to refer to features in the drawings. The same or similar terms in the drawings and the description may be used to refer to the same or similar parts of the invention.

As will be appreciated, each example is provided to illustrate the invention, not for the purpose of limiting the invention. In fact, it will be apparent to those skilled in the art that modifications and changes may be made to the present invention without departing from the scope or scope thereof. For example, features that are illustrated or described as part of one embodiment may be used in another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and changes as fall within the scope of the appended claims and their equivalents. It should be understood that the ranges and limitations mentioned herein include all sub-ranges located within the prescribed limits, including the limits themselves, unless otherwise specified.

In addition, certain terms have been selected to describe the present invention and its component subsystems and parts. Wherever possible, these terms have been selected based on common terminology in the technology field. However, it will be appreciated that such terms are often subjected to different interpretations. For example, what may be described herein as a single component may be referred to in other context as consisting of multiple components, or what may be described herein as comprising a plurality of components may be referred to elsewhere as a single component. Thus, in understanding the scope of the present invention, attention should be given not only to the specific terminology but also to the accompanying description and context, as well as the structure, structure, function, and / or use of the component to which reference is made and which will be described, including the manner in which the term refers to the various figures, as well as, of course, to the precise use of the terminology in the appended claims. Further, while the following examples are described with respect to a particular type of turbine, the technology of the present invention may be applicable to other types of turbines, as one skilled in the art would understand in the relevant technological field.

Taking into account the nature of turbine operation, some descriptive terms throughout this application may be used to explain the operation of the machine and / or any subsystems or components contained therein, and it may prove advantageous to define those terms at the beginning of this section , Accordingly, unless otherwise specified, these terms and their definitions are as follows. Without further specification, the terms "front" and "rear" refer to directions with respect to the orientation of the gas turbine engine. That is, "front" refers to the front or compressor end of the gas turbine, and "rear" refers to the rear or turbine end of the gas turbine. It will be appreciated that each of these terms can be used to refer to a movement or relative position within the turbine. The terms "downstream" and "upstream" are used to refer to a location within a specified conduit with respect to the general direction of the flow moving therethrough. (It will be appreciated that these terms refer to a direction with respect to expected flow during normal operation, which should be readily apparent to one skilled in the art.) The term "downstream" corresponds to the direction in which a fluid flows through the specified conduit during refers to "upstream" in the opposite direction. For example, the primary flow of working fluid through a turbine consisting of the air flowing through the compressor and subsequently becoming combustion gases within and beyond the combustion chamber may thus begin as an upstream location toward an upstream or forward end of the compressor and terminating at a downstream location to a downstream or aft end of the turbine. With regard to the description of the flow direction within a combustor of common type, as described in more detail below, it will be appreciated that the compressor discharge air typically enters the combustor through impingement ducts (in relation to the longitudinal axis of the combustor and the compressor / turbine positioning described below , which defines the difference between front and rear) to focus against the rear end of the combustion chamber. Once in the combustion chamber, the compressed air is directed from a flow annulus formed around an inner chamber toward the forward end of the combustion chamber where the air flow enters the inner chamber and changes its direction of flow in the direction of the rear end of the combustion chamber flows. In still another context, coolant flows may be treated by cooling passages in the same manner.

In addition, given the configuration of a compressor and a turbine about a common centerline, as well as the cylindrical configuration common to many types of combustors, terms describing a position relative to an axis may be used herein. In this regard, it will be appreciated that the term "radial" refers to a movement or position perpendicular to an axis. Related to this, it may be necessary to describe a relative distance from the central axis. In this case, when a first component is closer to the central axis than a second component, it is described herein that the first component is "radially inboard" or "inboard" with respect to the second component. On the other hand, if the first component is farther away from the central axis than the second component, it will be described herein that the first component is "radially outward of" or "outboard" with respect to the second component. In addition, it will be appreciated that the term "axial" refers to a movement or position parallel to an axis. Finally, the term "circumferentially" refers to a movement or position about an axis. As noted, although these terms may be applied to a common centerline extending through the compressor and turbine sections of the engine, these terms may also be applied to other components or subsystems of the turbine. For example, in the case of a cylindrically shaped combustor, which is common to many turbines, the axis, which gives these terms relative importance, may be the longitudinal reference axis extending through the center of the cylindrical cross-sectional shape, which is first cylindrical but a more annular Profile goes over when approaching the turbine.

Referring to 1 is a simplified drawing of some areas of a gas turbine system 10 illustrated. The turbine system 10 may use liquid or gaseous fuel, eg, natural gas and / or a hydrogen-rich syngas, to the turbine system 10 to operate. As shown, mix several fuel-air nozzles (or, as here called "fuel nozzles 12 ") Of the type described in more detail below take a fuel supply 14 on, mix the fuel with an air supply, and direct the fuel-air mixture for combustion in a combustion chamber 16 into it. The burned fuel-air mixture produces hot pressurized exhaust gases passing through a turbine 18 through in the direction of an exhaust outlet 20 can be directed. While the exhaust gases through the turbine 18 flow through, the gases force one or more turbine blades, a shaft 22 along an axis of the turbine system 10 to turn. As shown, the shaft can 22 with different components of the turbine system 10 be connected to which a compressor 24 belongs. The compressor 24 Also contains blades with the shaft 22 can be connected. While the wave 22 turns, the blades run inside the compressor 24 also around, giving them air from an air intake 26 through the compressor 24 and in the fuel nozzles 12 and / or the combustion chamber 16 compacted. The wave 22 can also with a load 28 be connected, which may be a vehicle or a stationary load, such as an electric generator in a power plant or a propeller on an aircraft. As will be understood, the load can 28 comprise any suitable device capable of rotating the turbine system 10 to be driven.

2 shows a simplified drawing of cross-sectional views of some sections of the gas turbine system 10 that in the 1 is shown schematically. As in 2 shown schematically contains the turbine system 10 one or more fuel nozzles 12 in a headboard 27 the combustion chamber 16 in the gas turbine 10 are arranged. Each illustrated fuel nozzle 12 may include a plurality of fuel nozzles integrated in a group and / or a stand-alone fuel nozzle, each illustrated fuel nozzle 12 at least substantially or entirely based on internal structural support (eg load-bearing fluid channels). Referring to 2 instructs the system 10 a compressor section 24 for pressurizing a gas, such as air, into the system 10 via an air inlet 26 flows. During operation, air enters the turbine system 10 through the air inlet 26 one and can in the compressor 24 be put under pressure. It should be understood that while gas is referred to herein as air, the gas may be any gas that is suitable for use in a gas turbine system 10 suitable is. Compressed air coming out of the compressor section 24 is discharged, flows into a combustion chamber section 16 into it, the general through several combustion chambers 16 (of which only one in the 1 and 2 illustrated) in an annular array about an axis of the system 10 are arranged around. The air entering the combustion chamber section 16 flows in, is mixed with the fuel and within the combustion chamber 32 the combustion chamber 16 burned. The fuel nozzles 12 For example, a fuel-air mixture in the combustion chamber 16 inject fuel into a fuel-to-air ratio suitable for optimal combustion, emissions, fuel consumption, and power output. The combustion generates hot pressurized exhaust gases, which are then from each combustion chamber 16 to a turbine section 18 ( 1 ) stream to the system 10 drive and produce power. The hot gases drive one or more blades (not shown) within the turbine 18 to the shaft 22 and thus the compressor 24 and the load 28 to turn. The rotation of the shaft 22 causes the blades 30 inside the compressor 24 to circulate and air passing through the inlet 26 is absorbed, fed and compacted. However, it should be readily recognized that a combustion chamber 16 not as described above and configured here illustrated, and that it may generally have any structure that allows compressed air to be mixed with fuel, burned, and routed to a turbine section 18 of the system 10 is transmitted.

By now on 3 to 5 Reference is made to an exemplary configuration of a premixing pilot nozzle 40 (or simply "pilot nozzle 40 ") In accordance with certain aspects of the present invention. The pilot nozzle 40 can do some mixing tubes 41 contained within which a fuel-air mixture for combustion within the combustion chamber 32 is produced. 3 to 5 illustrate an arrangement through which fuel and air different mixing tubes 41 the pilot nozzle 40 can be supplied. Another such fuel-air supply configuration is with respect to 8th and that it should be appreciated that other fuel-air delivery arrangements are also possible and that these examples should not be construed as limiting unless otherwise indicated in the attached set of claims.

As in the 3 . 4 and 5 shown, the mixing tubes 41 have a linear and axial configuration. In such cases, every mixing tube 41 be configured such that a fluid flow is discharged therefrom in one direction (or, as used herein, an "exit direction" contains), which is to the central axis 36 the fuel nozzle 12 runs parallel or alternatively at least the tangentially inclined alignment with respect to the central axis 36 the fuel nozzle does not have. As used herein, such mixing tubes can be used 41 be referred to as "axial mixing tubes". As a result, an axial mixing tube 41 be oriented so that it is substantially parallel to the central axis 36 the fuel nozzle 12 runs, or alternatively, the axial mixing tube 41 be aligned to a radially inclined orientation with respect to the central axis 36 to be included as long as the mixing tube, the tangentially inclined component is missing. Other mixing tubes 41 , which are referred to as "inclined mixing tubes", may include tangentially angled or skewed orientation, such that each of them releases the mixture of fuel and air in one direction with respect to the central axis 36 the fuel nozzle 12 tilted obliquely or tangentially. As described below, this type of configuration can be used to generate, after release, a swirl pattern within the firing zone that determines certain performance aspects of the pilot nozzle 40 and thereby the performance of the fuel nozzle 12 improved.

As illustrated, the fuel nozzle can 12 an axially elongated peripheral wall 50 that defines an outer shell of the component. The peripheral wall 50 the fuel nozzle 12 has an outer surface and an inner surface oriented in the opposite direction to the outer surface and defining an axially elongated inner cavity. As used herein, a central axis 36 the nozzle 12 as the center axis of the fuel nozzle 12 defined in this example as the central axis of the peripheral wall 50 is defined. The fuel nozzle 12 may also include a hollow, axially elongated central body 52 contained within the by the peripheral wall 50 formed cavity is arranged. For a given concentric arrangement, between the peripheral wall 50 and the centerbody 52 can be shown, the central axis 36 be common to every component. The centerbody 52 may be defined axially by a wall defining an upstream end and a downstream end. A primary airflow channel 51 can in the annular space between the peripheral wall 50 and the outer surface of the centerbody 52 be defined.

The fuel nozzle 12 may further include an axially elongated, hollow fuel supply line, here referred to as a "central supply line 54 "Reference is made through the middle of the center body 52 extends through. Defined between the central supply line 54 and the outer wall of the centerbody 52 , may be an elongated internal passage or a secondary flow annulus 53 axially from a forward position adjacent the head end 27 in the direction of the pilot nozzle 40 extend. The central supply line 54 can similarly axially between the front end of the center body 52 while communicating with a fuel source (not shown) through the head end 27 can form through. The central supply line 54 may have a downstream end that at the rear end of the center body 52 is arranged, and can provide a supply of fuel, which eventually enters the mixing tubes 41 the pilot nozzle 40 is injected.

The primary fuel supply of the fuel nozzle 12 can go to the combustion chamber 32 the combustion chamber 16 through several Verwirblerschaufeln 56 be directed, as in 3 may be fixed vanes extending across the primary flow annulus 51 extend. In accordance with aspects of the present invention, the swirler vanes may be used 56 define a so-called "swozzle" -like fuel nozzle in which several vanes 56 radially between the centerbody 52 and the peripheral wall 50 extend. As schematically in 3 shown, each of the swirler paddles can 56 the swozzle desirably with internal fuel channels 57 Be provided in fuel injection ports 58 from which the primary fuel supply (whose flow is indicated by arrows) is introduced into the primary airflow passing through the primary flow annulus 51 is directed. Because of this primary airflow against the swirler blades 56 is directed, a swirl pattern is imparted, which, as will be appreciated, the mixing of the air and fuel feeds within the primary flow annulus 51 supported. Downstream of the swirler blades 56 The swirling air and fuel feeds that flow inside the flowring space can become 51 were mixed continuously, before being burned in the combustion chamber 32 be issued. As used here, if used by the pilot nozzle 40 on the primary flow annulus 51 as a "parent nozzle", and the fuel-air mixture within the primary flow annulus 51 may be referred to as originating within the "parent nozzle". When these terms are used, you will realize that the fuel nozzle 12 contains a parent nozzle and a pilot nozzle and that each of these injects separate fuel-air mixtures into the combustion chamber.

The centerbody 52 can be described as containing axially stacked sections, wherein the pilot nozzle 40 the axial portion is at the downstream or rear end of the center body 52 is arranged. According to the exemplary embodiment shown, the pilot nozzle includes 40 a fuel storage room 64 located at a downstream end of the central supply line 54 is arranged. As illustrated, the fuel plenum 64 with the central supply line 54 over one or more fuel ports 61 in fluid communication. The fuel can thus through the supply line 54 pour over to the fuel ports 61 in the fuel storage room 64 to flow. The pilot nozzle 40 may also have a ring-shaped center body wall 63 included radially outward of the fuel plenum 64 and desirably concentric with respect to the central axis 36 is arranged.

As described, the pilot nozzle can 40 several axially elongated, hollow mixing tubes 41 included with respect to the fuel storage room 64 are arranged just outside. The pilot nozzle 40 can through an upstream face 71 and a downstream end surface 72 be defined axially. As illustrated, the mixing tubes can 41 axially through the centerbody wall 63 extend through. Several fuel ports 75 can be inside the center body wall 63 for the supply of fuel from the fuel plenum 64 into the mixing tubes 41 be formed into it. Each of the mixing tubes 41 can be axial between an inlet 65 passing through the upstream face 71 the pilot nozzle 40 is formed through, and an outlet 66 passing through the downstream end face 72 the pilot nozzle 40 is formed through extend. Set up in this way, an airflow can enter the inlet 65 every mixing tube 41 from the secondary flow annulus 53 of the middle body 52 be directed. Every mixing tube 41 can at least one fuel port 75 exhibit that with the fuel collecting space 64 is in fluid communication, so that a fuel flow coming out of the fuel plenum 64 exit, into each mixing tube 41 into flows. A resulting fuel-air mixture may then be downstream in each mixing tube 41 flow and then out of the outlets 66 passing through the downstream end face 72 the pilot nozzle 40 are formed through, in the combustion chamber 32 be injected. As will be seen, at the given linear configuration and axial orientation of the mixing tubes 41 that in the 3 to 5 shown are the fuel-air mixture coming out of the outlets 66 exiting, directed in a direction substantially parallel to the central axis 36 the fuel nozzle 12 is aligned. While the fuel-air mixture after it enters the combustion chamber 32 is injected, which tends to move away from each mixing tube 41 from radial spread, Applicants have found that radial spread is insignificant. Studies have indeed shown that the equivalence ratio (ie the air / fuel ratio) at the section of the combustion exit plane 44 located immediately downstream of the outlet 66 every mixing tube 41 is almost twice as large as the equivalence ratio may be at the portion of the combustion exit plane 44 present immediately downstream of the central axis 36 is arranged. High equivalence ratios at a location immediately downstream of the outlet 66 every mixing tube 41 can continually and effectively ignite the fuel-air mixture through the parent nozzle, and thereby can be used to stabilize the flame even when the flame is blowing near the lean-blow-out condition; "LBO") is operated.

6 and 7 contain a simplified side view, the different orientations of a single mixing tube 41 inside a pilot nozzle 40 with respect to the central axis 36 the fuel nozzle 12 (ie as they pass through the perimeter wall 50 can be defined) compares. 6 shows a mixing tube 41 having an axial configuration which is the configuration described with reference to FIG 3 to 5 described above. As indicated, the mixing tube is 41 substantially parallel to the central axis 36 aligned, so that the fuel-air mixture, which is discharged from it (ie from the outlet 66 ), a direction of exit ("exit direction") 80 which is approximately parallel to a downstream continuation of the central axis 36 the fuel nozzle 12 runs.

As in 7 illustrated contains the mixing tube 41 According to an alternative embodiment of the present invention at a downstream end of an inclined outlet portion 79 , that with respect to the central axis 36 the fuel nozzle 12 angled or tangentially inclined is employed. Set up in this way, the fuel-air mixture points out of the outlet 66 flows, an exit direction 80 resulting from the tangentially skewed orientation of the slanted outlet section 79 extends out and follows this. As used herein, the inclined outlet portion 79 with respect to the acute tangential angle 81 be defined relative to the downstream direction of the axial reference line 82 forms (which, as used herein, is defined as a reference line to the central axis 36 runs parallel).

As described in more detail below, performance advantages for the pilot nozzle 40 can be achieved by arranging the various mixing tubes to contain such slanted orientations. Typically, each of the mixing tubes 41 similarly arranged and arranged in parallel, although certain embodiments described in more detail below contain exceptions thereto. The measure in which the inclined outlet sections 79 the mixing tubes 41 tangentially angled, ie the size of the tangential angle 81 that is between the exit direction 80 and the axial reference line 82 formed, may vary. As you will see, the tangential angle can be 81 depend on different criteria. Further, although the results may be optimal at particular values, different levels of desired performance advantages over a wide range of values for the tangential angles may be provided 81 be achieved. Applicants have been able to determine some preferred embodiments, which will now be disclosed. According to one embodiment, the tangential angle contains 81 of the inclined mixing tube 41 a range between 10 ° and 70 °. According to another embodiment, contains the tangential angle 81 a range between 20 ° and 55 °.

Although the in 7 shown simplified version only a mixing tube 41 shows, each of the mixing tubes 41 have a similar configuration, and they may be aligned parallel to each other. If the angled orientation is consistent on each of the multiple mixing tubes 41 is applied in the pilot nozzle 40 It will be appreciated that the tangential orientation of the exit direction is just downstream of the downstream end face 72 the pilot nozzle 40 creates a swirling flow. As discovered by the present applicants, this swirling flow can be used to achieve certain performance benefits, which are described in more detail below. According to an exemplary embodiment, this may be from the mixing tubes 41 let loose mixture with the swirling fuel-air mixture "in the same direction to swirl", which from the primary flow annulus 51 leakage (ie in cases where the primary flow annulus 51 the swirler blades 56 contains).

As described with reference to some alternative embodiments provided below, the mixing tubes may 41 be adapted to this tangential angled exit direction 80 to achieve in different ways. For example, mixing tubes can 41 containing linear segments which (as in 7 ) are connected to bends or elbows, used to angle the exit direction. In other cases, the mixing tubes can 41 as shown below, may be curved and / or spiraled to achieve the desired exit direction. In addition, combinations of linear segments and curved or spiral segments, as well as any other geometry may be used, that of the exiting flow from the mixing tubes 41 allows, at a tangential angle with respect to the central axis 36 of the primary flow annulus 51 withdraw.

8th to 12 illustrate exemplary embodiments that include a mixing tube 41 containing angled or tilted configurations according to the present invention. 8th shows an exemplary spiral configuration for the mixing tubes 41 and is also provided to illustrate an alternative preferred arrangement with the fuel and air to the mixing tubes 41 the pilot nozzle 40 can be supplied. In this case, an outside fuel channel 85 inside the centerbody wall 63 disposed axially and extending from an upstream connection, which is connected to a fuel line 57 is created, which, as in 3 and 4 also illustrates fuel to the openings 58 the swirler blades 56 supplies. At the given configuration 8th the fuel itself becomes out of the fuel channel 85 supplied by the mixing tubes 41 is located just outboard, rather than that the fuel from a fuel plenum is supplied, with respect to the mixing tube 41 is arranged radially inward.

As you will see, the outside fuel channel can 85 be formed as an annular passage or as a plurality of individual tubes, which are around the circumference of the center body 52 are formed around, so desirably with the locations of the mixing tubes 41 match. One or more fuel ports 75 may be formed to the outer fuel channel 85 with each of the mixing tubes 41 fluidly connect. In this way, an upstream end of each of the mixing tubes 41 be connected to a fuel source. As further illustrated, the secondary flow annulus 53 within the centerbody 52 be formed and extend axially therethrough to a supply of air to each of the inlets 65 the mixing tubes 41 to deliver. It will be appreciated that, unlike the embodiment of the 3 and 4 , the centrally located central supply line 54 of the middle body 52 not used to the mixing tubes 41 To supply fuel. Even then, the central supply line 54 be included to other fuel types for the fuel nozzle 12 to deliver or enable. In any case, the inner passage or the secondary flow annulus 53 be formed as an elongated passage which between a central structure, such as the outer surface of the central feed line 54 and an inner surface of the center body wall 63 is defined. Other configurations are also possible.

Similar in the 7 explained configuration, each of the mixing tubes 41 an inclined outlet section 79 included with respect to the central axis 36 the fuel nozzle 12 tangential is angled. In this way, the exit direction 80 for the fuel-air mixture that flows through the mixing tubes 41 through, similar to the central axis 36 the fuel nozzle 12 be tilted. According to the preferred embodiments of 8th to 10 contains each of the mixing tubes 41 an upstream linear section 86 which is in a downstream spiral section 87 passes over, as indicated, around the central axis 36 writhes around. In one embodiment, the fuel ports are 74 in the upstream linear section 86 arranged, and the downstream spiral-shaped section 87 encourages the mixing of fuel and air, reducing the components within the mixing tube 41 be prompted to change direction. It It has been found that this change in direction produces secondary flows and turbulence that promote mixing between fuel and air flowing therethrough, allowing a well mixed fuel-air mixture from the mixing tubes 71 comes out in the desired angled exit direction.

According to preferred embodiments, a plurality of mixing tubes 41 around the circumference of the pilot nozzle 40 provided around. For example, between ten and fifteen tubes may be within the centerbody wall 63 be defined. The mixing tubes 41 may be spaced at regular intervals. The exit direction 80 passing through the slanted outlet section 79 may be configured to coincide with or point in the same direction as the direction of swirling within the primary flow annulus 51 through the swirler blades 56 is produced. In particular, according to a preferred embodiment, the inclined outlet section 79 in the same direction as the swirler blades 56 be angled to generate a current in the same direction about the central axis 36 whirls.

Another exemplary embodiment is in 11 shown the mixing tubes 41 containing a curved spiral formation for the entire mixing length of the mixing tubes 41 contains. As used herein, the mixing length of a mixing tube is 41 the axial length between the location of the initial (ie, the most upstream) fuel opening 75 and the outlet 66 , As you can see, each of the mixing tubes 41 at least one fuel opening 75 contain. According to alternative embodiments, each mixing tube 41 several fuel ports 75 contain. The fuel openings 75 can along the mixing length of the mixing tube 41 axially spaced. According to a preferred embodiment, the fuel openings 75 however, to the upstream end of the mixing tube 41 arranged or concentrated, resulting in fuel and air being brought together early so that more mixing can occur before the combined flow from the outlets 66 in the combustion chamber 32 is injected.

According to a further embodiment, as in 12 illustrates the inclined portion of the mixing tube 41 only to a downstream portion of the mixing tube 41 limited, which, as shown, an axially small length, which is adjacent to the outlet 66 located. With this configuration, the beneficial results can still be achieved because the desired swirl pattern is still within the common outlet from the mixing tubes 41 can be brought about. The degree of fuel-air mixing within the mixing tube 41 but can be less than optimal.

13 to 16 illustrate additional embodiments in which linear and spiral mixing tubes 41 combined. 13 respectively. 14 illustrate a side view and a perspective view of a preferred manner, in the linear axial mixing tubes 41 (ie those that are parallel to the central axis 36 extend) with inclined mixing tubes 41 inside the centerbody wall 63 the nozzle 40 can be arranged. As shown, the tilted mixing tubes can 41 be formed spirally. As you will see, the slanted mixing tubes can 41 also be formed with linear segmented configuration, which between the segments a kink or elbow-like connection between segments, such as the example of 12 , contains. 15 As you will see, this is an inlet view that provides the inlets 65 the axial and inclined mixing tubes 41 at the upstream end surface 71 the pilot nozzle 40 shows. 16 provides an outlet view that provides a representative arrangement of the outlets 66 the axial and inclined mixing tubes 41 at the downstream end face 72 the pilot nozzle 40 shows. According to alternative embodiments, the inclined mixing tubes 41 be adapted to swirl in the same direction, ie about the central axis 36 around in the same direction as the swirling mixture of the parent nozzle of the primary flow annulus 51 to twirl.

The axial and inclined mixing tubes can both be supplied by the same air and fuel sources. Alternatively, each of the different types of mixing tubes may be supplied from different supply leads so that the proportion of fuel and air reaching the mixing tubes is either significantly different or controllable. In particular, as will be appreciated, the supply of each type of pipe with its own controllable air and fuel feeds allows for flexibility in engine operation that may allow for adjustment or adjustment of the fuel-air or equivalence ratio within the combustion chamber. Different settings may be used across the entire range of loads or operating levels, which, as discovered by the assignee of the disclosure, provides a way to address certain problem areas that may occur at different load levels.

For example, in a part load mode of operation, when the combustion temperatures are low relative to the base load, CO is the primary emission problem. In such cases, the Equivalence ratios are increased to increase the peak zone temperatures for improved CO burnout. That is, because the slanted mixing tubes act to attract the reactants of the parent nozzle back to the nozzle tip, the temperature in the tip zone (ie, the tip of the nozzle) may remain cooler than if the tubes were not tangentially angled. In some cases this can lead to excess CO in the emissions of the combustion chamber. By adding the axial mixing tubes (as in 13 to 16 however, the amount of recirculation flow may be adjusted, limited or controlled and thus provides a means for controlling the peak zone temperature. This method may thus serve as an additional way to improve combustion characteristics and emission levels when operating the engine in certain modes.

For example, in other embodiments, the present invention includes the use of conventional control systems and methods for manipulating air flow levels between the two different types of mixing tubes. According to one embodiment, the air flow to the axial mixing tubes 41 be increased to prevent cooler reactant products from the parent nozzle, back into the tip of the pilot nozzle 40 to be drafted. This can be used to raise the temperature of the tip zone, which can reduce CO levels.

In addition, the combustion dynamics may have a strong correlation with the shear in the reaction zones. By adjusting the amount of air passing through each of the different types of mixing tubes (i.e., the inclined and axial), the amount of shear can be tuned to a level that positively affects combustion. This can be achieved by establishing throttle openings to deliver unequal amounts of air to various types of mixing tubes. Alternatively, active control devices may be installed and operated via conventional methods and systems to vary the air supply levels during operation. Further, a control logic and / or a closed loop control loop may be generated such that the control of the devices is responsive to an operating mode or a measured operating parameter. As mentioned, this can lead to varying control settings according to the operating mode of the machine, e.g. when operating at full load or at reduced load levels or in response to measured operator parameter readings. Such systems may also include the same types of control method of varying the amount of fuel supplied to the different types of mixing tubes. This can be achieved by pre-set component configurations, i. Aperture size and the like, or by more active real-time control. As will be appreciated, operating parameters such as e.g. Temperatures within the combustion chamber, acoustic variations, reactance flow patterns, and / or other parameters related to combustor operation may be used as part of a feedback loop in such a control system.

As will be appreciated, these types of control methods and systems may also be applicable to other embodiments described herein, including all of those involving the combination of mixing tubes in the same pilot nozzle having different configurations or swirl directions (including, for example, the counter-swirling embodiments). concerning the 17 to 20 are described, or the embodiments of the 21 and 22 depicting ways in which a subset of flow tubes may be configured to have exit directions containing radial components). Furthermore, these types of control methods and systems may be applicable to other embodiments discussed herein, including all of those involving the combination of mixing tubes in the same pilot nozzle having different configurations or swirl directions (such as those described with reference to FIGS 17 to 20 described embodiments with opposing vertebrae).

In addition, such methods and systems can be applied to pilot nozzle configurations where all of the mixing tubes are set up in the same way and are aligned parallel to each other. In these cases, the control systems may be operated to control combustion processes by varying air and / or fuel distributions between the parent nozzle and the pilot nozzle to affect combustion characteristics. According to other embodiments, the control methods and systems may be configured to vary fuel and / or air supply levels unevenly around the circumference of the pilot nozzle, which may be used, for example, to break certain flow patterns or prevent the generation of harmful acoustics. Such measures may be taken prospectively or in response to a detected abnormality. For example, the fuel and air supply may be increased or decreased to a particular subset of the mixing tubes. This action may be on a predefined periodic basis, in response to measured operating parameters or other conditions are taken.

17 to 20 illustrate additional exemplary embodiments in which inclined mixing tubes 41 having counter-rotating configurations within the centerbody wall 63 are defined. 17 us 18 12 illustrate a side view and a perspective view, respectively, of a representative arrangement of counter-rotating spiral mixing tubes 41 inside the centerbody wall 63 , 19 As will be appreciated, provides an inlet view of the pilot nozzle 40 ready to provide a representative arrangement of the inlets 65 the counter-rotating spiral mixing tubes 41 at the upstream end surface 71 the pilot nozzle 40 illustrated. 20 represents an outlet view of the pilot nozzle 40 ready, which illustrates a preferred way in which the outlets 66 the counter-rotating spiral mixing tubes 41 at the downstream end face 72 the pilot nozzle 40 can be arranged. As can be seen, the addition of the counter-swirling inclined mixing tubes 41 be used in the manner described above to control the temperature at the tip zone of the nozzle. In addition, the counter-swirling, inclined mixing tubes, due to increased shear caused by the counter-swirling pilot streams, promote greater mixing in the peak zone region, which may be advantageous for certain operating conditions.

21 and 22 illustrate alternative embodiments in which a radial component to the outlet direction of the mixing tubes 41 will be added. As you will see, illustrated 21 an outlet view of an alternative embodiment of the mixing tubes, which contains an external component with respect to the discharge direction. In contrast illustrated 22 an outlet view of an alternative embodiment of the mixing tubes, which contains an internal component with respect to the discharge direction. In this way, the inclined mixing tubes of the present invention may be configured to have both a radial component and a tangential component in the exit direction. According to an alternative embodiment, the mixing tubes may be arranged to have an outlet direction which has a radial component but no component in the circumferential direction. Thus, the inboard and outboard radial components can be added to the axial or slanted mixing tubes. According to exemplary embodiments, the angle of the inboard and / or outboard radial component may include a range between 0.1 ° and 20 °. As described above, the radial component may be included in a subset of the mixing tubes and thereby may be used to manipulate the shear action of the pilot nozzle so as to favorably control recirculation.

23 schematically illustrates the results of a directional flow analysis of a pilot nozzle 40 , the axial mixing tubes 41 having an axial outlet portion while the 24 the results of a directional flow analysis of inclined mixing tubes 41 schematically illustrated, having an inclined outlet portion. Axial mixing tubes 41 As shown, they can counteract the reverse flow created by the swirl caused by the superordinate nozzles, which can affect flame stability and increase the likelihood of lean flash flame blowing. In contrast, the inclined outlet portion may be configured to swirl the pilot reactants about the fuel nozzle axis in the same direction as the swirl generated in the primary or superordinate nozzle. As the results show, the swirling flow proves to be advantageous because the pilot nozzle now works together with the parent nozzle to create and / or enhance a central recirculation zone. As illustrated, the recirculation zone associated with the tilted mixing tubes contains a much more pronounced and centralized recirculation that causes reactants to be brought from a far downstream position back to the outlet of the fuel nozzle. As will be appreciated, the central recycle zone forms the basis for turbulence stabilized combustion because the products of combustion are drawn back to the nozzle outlet and exposed to fresh reactants so as to ensure the ignition of these reactants and thereby continue the process. The tilted mixing tubes can thus be used to enhance recirculation and thereby further stabilize the combustion that can be used to further stabilize lean fuel-air mixtures that may allow lower NOx emission levels. In addition, pilot nozzles, which, as mentioned, have tilted mixing tubes, can provide performance benefits associated with CO emission levels. This is achieved due to an enrichment circuit that creates a locally hot zone at the outlet of the fuel nozzle, which binds the nozzle flames and allows for further CO burnout. In addition, the pronounced recirculation produced by the inclined mixing tubes of the present invention can assist in CO burn-out by mixing the products and CO produced during combustion back into the central recirculation zone to minimize the likelihood of CO escaping unburned.

In this written description, examples are used to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using devices or systems and practicing methods contained therein. The patentable scope of the invention is defined by the claims, and may include other examples to which the person skilled in the art thinks. These 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.

A fuel nozzle for a gas turbine includes:
an elongated central body; an elongated peripheral wall formed about the central body to define a primary flow annulus therebetween; a primary fuel supply and a primary air supply in fluid communication with an upstream end of the primary flow annulus; and a pilot nozzle. The pilot nozzle may be formed in the centerbody and include: axial elongated mixing tubes defined within a centerbody wall; a fuel port disposed on the mixing tubes for connection to each of a secondary fuel supply; and a secondary air supply configured to communicate with an inlet of each of the mixing tubes in fluid communication. Several of the mixing tubes may be formed as inclined mixing tubes that are adapted to create a swirling downstream flow, while a plurality of the mixing tubes may be oppositely inclined mixing tubes.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6438961 [0004]

Claims (15)

A fuel nozzle for a combustion chamber of a gas turbine, wherein the fuel nozzle comprises: an axially elongate central body; an axially elongated peripheral wall formed about the central body to define a primary flow annulus space therebetween, the peripheral wall defining a center axis of the fuel nozzle; a primary fuel supply and a primary air supply in fluid communication with an upstream end of the primary flow annulus; and a pilot nozzle having a downstream portion of the centerbody, the pilot nozzle including: axially elongated mixing tubes defined within a central body wall, each of the mixing tubes extending between an inlet defined by an upstream end face of the pilot nozzle and an outlet formed by a downstream end face of the pilot nozzle; a fuel port disposed between the inlet and the outlet of each of the mixing tubes for communicating each of the mixing tubes with a secondary fuel supply; and a secondary air supply configured to be in fluid communication with the inlet of each of the mixing tubes; wherein the mixing tubes contain a plurality of inclined mixing tubes and a plurality of oppositely inclined mixing tubes; wherein the inclined mixing tubes are single of the mixing tubes angled with respect to the center axis of the fuel nozzle to produce a downstream swirling flow in a common outlet therefrom; and wherein the counter-tilted mixing tubes are single of the mixing tubes angled with respect to the center axis of the fuel nozzle to produce a countercurrently swirling downstream flow in a common outlet thereof in relation to the swirling flow caused by the inclined mixing tubes. The fuel nozzle according to claim 1, wherein the inclined mixing tubes are tangentially inclined with respect to the center axis of the fuel nozzle and the common outlet has a combined fuel and air outlet from the plurality of inclined mixing tubes, and wherein the oppositely inclined mixing tubes are tangentially inclined with respect to the center axis of the fuel nozzle and the common outlet having a combined fuel and air outlet from the plurality of oppositely inclined mixing tubes; and / or wherein each of the inclined mixing tubes and the oppositely inclined mixing tubes has an exit direction that is tangentially angled with respect to the center axis of the fuel nozzle, and wherein the inclined mixing tubes are configured such that the swirling flow of the common outlet swirls in the same direction a swirling flow caused by swirl vanes of the primary flow annulus. A fuel nozzle according to claim 1 or 2, wherein the mixing tubes each have an outlet portion having an axially narrow downstream portion of the mixing tube located adjacent to the outlet, the outlet portion defining a central axis therethrough; wherein the inclined mixing tubes are arranged such that a continuation of the central axis of the outlet section has an acute tangential exit angle relative to a downstream continuation of the center axis of the fuel nozzle; and wherein the oppositely inclined mixing tubes are arranged such that a continuation of the central axis of the outlet portion has an acute tangential exit angle with respect to the downstream continuation of the center axis of the fuel nozzle A fuel nozzle according to claim 3, wherein all of the slanted mixing tubes of the pilot nozzle have a parallel arrangement with respect to each other and wherein the tangential exit angle of the slanted mixing tubes has an angle of between 10 ° and 70 °; and wherein all of the oppositely inclined mixing tubes of the pilot nozzle have a parallel arrangement with respect to each other and wherein the tangential exit angle of the oppositely inclined mixing tubes has an angle between 10 ° and 70 °. A fuel nozzle according to claim 3 or 4, wherein the center body has axially stacked portions including: a front portion having a secondary fuel supply and a secondary air supply; and a rear portion configured as the pilot nozzle; wherein the front portion of the centerbody has an axially extending central supply line and a secondary flow annulus formed around the central supply line extending axially between a connection made with an air source formed toward the upstream end of the centerbody and a second extending upstream face of the pilot nozzle; and wherein the center body wall defines an outer wall of the centerbody and defines an outer boundary of the secondary flow annulus. The fuel nozzle of claim 5, wherein the primary flow annulus has a swozzle that includes a plurality of swirler vanes extending radially across the primary flow annulus; and fuel passages extending through the swirler vanes to connect fuel ports formed by an outer surface of the swirler vane to a fuel plenum; the swirler vanes having an oblique tangential orientation with respect to the central axis to cause a downstream flow therefrom that swirls about the central axis in a first direction; wherein the fuel port of each of the inclined mixing tubes and the oppositely inclined mixing tubes has a side fuel hole for injecting fuel through an opening formed through a side wall, and the fuel port for each of the inclined mixing tubes and the oppositely inclined mixing tubes has an upstream position relative to having an air flow therethrough; wherein the inclined mixing tubes and the oppositely inclined mixing tubes each preferably have a plurality of the fuel ports and wherein the plurality of fuel ports preferably have an upstream concentration relative to an air flow therethrough. A fuel nozzle according to claim 6, wherein each of said inclined mixing tubes and said counter-tilting mixing tubes is adapted to receive air flow through said inlet and a fuel flow through said fuel aperture to dispense a mixture thereof through said outlet, and wherein said outlet communicates with a combustion chamber Combustion chamber is in fluid communication; wherein the inclined mixing tubes each have a mixing length defined between an upstream fuel port and the outlet, and wherein, in terms of mixing length, the inclined mixing tubes each have a segmented configuration including an upstream segment and a downstream segment to each side of a joint marked a change of direction for the inclined mixing tube, have; and wherein the oppositely inclined mixing tubes each have a mixing length defined between an upstream fuel opening and the outlet, and wherein, with respect to the mixing length, the oppositely inclined mixing tubes each have a segmented configuration including an upstream segment and a downstream segment to each side of a joint , which marks a change of direction for the opposite inclined mixing tube, have. The fuel nozzle according to claim 7, wherein the inclined mixing tubes and the counter-tilted mixing tubes each have a configuration in which the upstream segment is linear and the downstream portion is curved; and / or wherein the inclined mixing tubes each have a configuration in which the upstream segment is linear and axially aligned and the downstream segment is curved and spirally formed about the central axis of the fuel nozzle, and wherein the upstream portion is preferably less than half the mixed length of the inclined mixing tubes, and wherein the oppositely inclined mixing tubes each have a configuration in which the upstream segment is linear and axially aligned and the downstream segment is curved and spiraled about the central axis of the fuel nozzle, and wherein the upstream portion is less than half the mixing length of the oppositely inclined mixing tubes. A fuel nozzle according to claim 7 or 8, wherein the tangential exit angle of the inclined mixing tubes and the oppositely inclined mixing tubes each have an angle between 20 ° and 55 °. A fuel nozzle according to any one of claims 7-9, wherein the inclined mixing tubes are arranged such that the swirling flow of the common outlet swirls in the first direction as defined by the direction of the swirling downstream flow passing through the swirler vanes of the primary flow annulus is produced. A fuel nozzle according to claim 10, wherein the pilot nozzle comprises between five and twenty five of the inclined mixing tubes and between five and twenty five of the oppositely inclined mixing tubes; wherein the inclined mixing tubes are circumferentially spaced within the centerbody wall at regular intervals; wherein the oppositely inclined mixing tubes are circumferentially spaced within the centerbody wall at regular intervals; and wherein the plurality of inclined mixing tubes have an outboard position with respect to the plurality of oppositely inclined mixing tubes, or wherein the plurality of inclined mixing tubes have an inboard position with respect to have several oppositely inclined mixing tubes. The fuel nozzle according to claim 11, wherein the plurality of inclined mixing tubes and the plurality of oppositely inclined mixing tubes have the same number of the mixing tubes; wherein the downstream end face of the pilot nozzle has an arrangement of the outlets in which the outlets of the inclined mixing tubes are angularly registered with respect to the outlets of the oppositely inclined mixing tubes; and wherein the angular registration of the array of outlets comprises that the outlets of the inclined mixing tubes are angularly offset with respect to the outlets of the oppositely inclined mixing tubes, or wherein the angular registration of the arrangement of the outlets has the outlets of the inclined mixing tubes arranged such that they angularly coincident with the outlets of the oppositely inclined mixing tubes. A fuel nozzle according to any one of claims 10-12, wherein the inclined mixing tubes are radially inclined with respect to the center axis of the fuel nozzle, and wherein the inclined mixing tubes are inclined radially to an outward direction of the fuel nozzle at an angle between 0.1 ° and 20 ° are; or wherein the slanted mixing tubes are set radially obliquely with respect to the center axis of the fuel nozzle and wherein the slanted mixing tubes are inclined radially to an inward direction of the fuel nozzle at an angle between 0.1 ° and 20 °. A fuel nozzle according to any of claims 10-13, wherein the oppositely inclined mixing tubes are radially skewed with respect to the center axis of the fuel nozzle and wherein the oppositely inclined mixing tubes are radially outward of the fuel nozzle at an angle between 0.1 ° and 20 ° are employed obliquely; or wherein the oppositely inclined mixing tubes are set radially obliquely with respect to the center axis of the fuel nozzle and wherein the oppositely inclined mixing tubes are inclined radially to an inward direction of the fuel nozzle at an angle between 0.1 ° and 20 °. A fuel nozzle according to any one of claims 10-12, wherein the inclined mixing tubes are radially inclined with respect to the center axis of the fuel nozzle; and wherein the oppositely inclined mixing tubes are set radially obliquely with respect to the center axis of the fuel nozzle.

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