Systems and methods for control of combustion dynamics in combustion system

The present disclosure generally relates to a system with a gas turbine engine. The gas turbine engine includes a first combustor having a first fuel injector and a second combustor having a second fuel injector. The gas turbine engine further includes a first fuel conduit extending from a first orifice to a first fuel outlet of the first fuel injector. The first fuel conduit has a first acoustic volume between the first orifice and the first fuel outlet. The gas turbine engine further includes a second fuel conduit extending from a second orifice to a second fuel outlet of the second fuel injector. The second fuel conduit has a second acoustic volume between the second orifice and the second fuel outlet, and the first acoustic volume and the second acoustic volume are different from one another.

BACKGROUND

The subject matter disclosed herein relates generally to gas turbine systems, and more particularly, to systems and methods for reducing combustion dynamics, and more specifically, for reducing modal coupling of combustion dynamics within a gas turbine engine.

Gas turbine systems generally include a gas turbine engine having a compressor section, a combustor section, and a turbine section. The combustor section may include one or more combustors (e.g., combustion cans), each combustor having a primary combustion system and a secondary combustion system (e.g., late lean injection (LLI) system) downstream from the primary combustion system. A fuel and/or air mixture may be routed into the primary and secondary combustion systems through fuel nozzles, and each combustion system may be configured to combust the mixture of the fuel and air to generate hot combustion gases that drive one or more turbine stages in the turbine section.

The generation of the hot combustion gases can create a variety of combustion dynamics, which occur when the combustor acoustic oscillations interact with the flame dynamics (also known as the oscillating component of the heat release), to result in a self-sustaining pressure oscillation in the combustor. Combustion dynamics can occur at multiple discrete frequencies or across a range of frequencies, and can travel both upstream and downstream relative to the respective combustor. For example, the pressure waves may travel downstream into the turbine section, e.g., through one or more turbine stages, or upstream into the fuel system. Certain components of the turbine system can potentially respond to the combustion dynamics, particularly if the combustion dynamics generated by the individual combustors exhibit an in-phase and coherent relationship with each other, and have frequencies at or near the natural or resonant frequencies of the components. In the context of combustion dynamics, “coherence” refers to the strength of the linear relationship between two dynamic signals, and is strongly influenced by the degree of frequency overlap between them. In the context of combustion dynamics, “coherence” is a measure of the modal coupling, or combustor-to-combustor acoustic interaction, exhibited by the combustion system.

Accordingly, a need exists to control the combustion dynamics, and/or modal coupling of the combustion dynamics, to reduce the possibility of any unwanted sympathetic vibratory response (e.g., resonant behavior) of components in the turbine system.

BRIEF DESCRIPTION

In a first embodiment, a system includes a gas turbine engine. The gas turbine engine includes a first combustor having a first fuel injector and a second combustor having a second fuel injector. The gas turbine engine further includes a first fuel conduit extending from a first orifice to a first fuel outlet of the first fuel injector. The first fuel conduit has a first acoustic volume between the first orifice and the first fuel outlet. The gas turbine engine further includes a second fuel conduit extending from a second orifice to a second fuel outlet of the second fuel injector. The second fuel conduit has a second acoustic volume between the second orifice and the second fuel outlet, and the first acoustic volume and the second acoustic volume are different from one another.

In a second embodiment, a system includes a first combustor of a gas turbine system. The first combustor includes a first fuel injector having a first fuel outlet and a second fuel injector having a second fuel outlet. The first combustor further includes the first fuel conduit extending from a first orifice to the first fuel outlet of the first fuel injector. The first fuel conduit has a first conduit geometry between the first orifice and the first fuel outlet and the first orifice has a first orifice geometry. The first combustor further includes a second fuel conduit extending from a second orifice to the second fuel outlet of the second fuel injector. The second fuel conduit has a second conduit geometry between the second orifice and the second fuel outlet and the second orifice has a second orifice geometry. The first conduit geometry and the second conduit geometry are different from one another, or the first orifice geometry and the second orifice geometry are different from one another, or a combination thereof.

In a third embodiment, a system includes a first fuel conduit extending from a first orifice to a first fuel outlet of a first fuel injector of a gas turbine engine. The first fuel conduit has a first conduit geometry between the first orifice and the first fuel outlet, and the first orifice has a first orifice geometry. The system further includes a second fuel conduit extending from a second orifice to a second fuel outlet of a second fuel injector of the gas turbine engine. The second fuel conduit has a second conduit geometry between the second orifice and the second fuel outlet. The second orifice has a second orifice geometry different from the first orifice geometry, or the second conduit geometry is different from the first conduit geometry.

DETAILED DESCRIPTION

The present disclosure is directed towards reducing combustion dynamics and/or modal coupling of combustion dynamics, to reduce unwanted vibratory responses in downstream components of a gas turbine system and/or the combustors themselves. A gas turbine combustor (or combustor assembly) may generate combustion dynamics due to the combustion process, characteristics of intake fluid flows (e.g., fuel, oxidant, diluent, etc.) into the combustor, and various other factors. The combustion dynamics may be characterized as pressure fluctuations, pulsations, oscillations, and/or waves at certain frequencies. The fluid flow characteristics may include velocity, pressure, fluctuations in velocity and/or pressure, variations in flow paths (e.g., turns, shapes, interruptions, etc.), or any combination thereof. Collectively, the combustion dynamics can potentially cause vibratory responses and/or resonant behavior in various components upstream and/or downstream from the combustor, as well as the combustors themselves. For example, the combustion dynamics (e.g., at certain frequencies, ranges of frequencies, amplitudes, combustor-to-combustor phases, etc.) can travel both upstream and downstream in the gas turbine system. If the gas turbine combustors, upstream components, and/or downstream components have natural or resonant frequencies that are driven by these pressure fluctuations (i.e. combustion dynamics), then the pressure fluctuations can potentially cause vibration, stress, fatigue, etc. The components may include combustor liners, combustor flow sleeves, combustor caps, fuel nozzles, turbine nozzles, turbine blades, turbine shrouds, turbine wheels, bearings, fuel supply assemblies, or any combination thereof. The downstream components are of specific interest, as they are more sensitive to combustion tones that are in-phase and coherent. Thus, reducing coherence, altering phase and/or reducing the amplitudes of the combustion dynamics specifically reduces the possibility of unwanted vibrations in downstream components. One way to reduce the coherence of the combustion dynamics among the combustors is to alter the frequency relationship between two or more combustors, diminishing any combustor-to-combustor coupling. As the combustion dynamics frequency in one combustor is driven away from that of the other combustors, modal coupling of combustion dynamics is reduced, which, in turn, reduces the ability of the combustor tone to cause a vibratory response in downstream components. An alternate method of reducing modal coupling is to reduce the constructive interference of the fuel nozzles within the same combustor, by introduction of a phase delay between the fuel nozzles, reducing the amplitudes in each combustor, and potentially preventing or reducing combustor-to-combustor coupling. Furthermore, introducing a phase lag between the combustors, or otherwise altering the phase relationship between two or more combustors may also help to prevent or reduce unwanted vibrations in the gas turbine system.

As discussed in detail below, the disclosed embodiments may vary the physical characteristics of a pre-orifice within a fuel line of a fuel supply assembly (e.g., late lean injection (LLI) fuel circuit) to modify the fuel system acoustic impedance, which may lead to combustion dynamics frequencies in one or more combustors that are different, phase shifted, smeared or spread out over a greater frequency range, or any combination thereof, relative to any resonant frequencies of the components in the gas turbine system. As noted above, a gas turbine system may include one or more combustor assemblies (e.g., combustor cans, combustors, etc.), and each combustor may be configured with a primary combustion zone and a secondary combustion zone. Specifically, in some embodiments, the secondary combustion zone may include an LLI fuel circuit configured to route a secondary fuel into a secondary combustion zone for combustion. In certain embodiments, each LLI fuel circuit includes one or more fuel lines extending along either the liner or the flow sleeve of the combustor, and each fuel line is configured to provide a secondary fuel to one or more fuel injectors that route the secondary fuel into the secondary combustion zone. In particular, each of the one or more LLI fuel lines may include one or more pre-orifices through which the fuel flows in the LLI fuel circuit prior to arriving at the LLI fuel nozzles, where the fuel is injected into the combustor through one or more post-orifices. The fuel system acoustic impedance of the fuel nozzles is defined by the geometry of the pre-orifice, the geometry of the post-orifice and the volume between the pre and post-orifice. Accordingly, varying the position of the pre-orifice within the LLI fuel circuit adjusts the volume between the pre and post orifice, to adjust the fuel system acoustic impedance of one or more fuel nozzles. In addition, altering the size, shape and/or number of holes in the pre-orifice may also alter the fuel system acoustic impedance of one or more fuel nozzles.

In certain embodiments, the physical characteristics (e.g., position, sizing, shape, location, effective area, etc.) of the pre-orifice of each fuel line within the LLI fuel circuit of a single combustor may be different from the physical characteristics of the pre-orifice of another fuel line within the same LLI fuel circuit. For example, the location of the pre-orifice along the LLI fuel line may be shifted, so that it is closer or further away from the post-orifice, thus changing the acoustic volume between the pre and post orifices, thereby altering the fuel system impedance. By further example, the location of the pre-orifice relative to the post-orifice may be shifted relative to other fuel lines of the same combustor, thus changing the acoustic volume between the pre and post orifices and thereby altering the fuel system impedance. Further, in certain embodiments, the physical characteristics of the pre-orifices of the one or more fuel lines within a single combustor may be different from the physical characteristics of the pre-orifices of one or more fuel lines within another (e.g., adjacent, alternating) combustor within the gas turbine system. For example, the location of the pre-orifice relative to the post-orifice along the LLI fuel lines of a first combustor may be shifted when compared to the location of the pre-orifice relative to the post-orifice of another combustor (e.g., an adjacent combustor), thereby changing the acoustic volume between the pre and post orifices and thus altering the fuel system impedance between different combustors within the gas turbine system.

In some embodiments, by varying the physical characteristics of the pre-orifice (e.g., location, size, position, shape, effective area, etc.) of one or more fuel lines within the LLI fuel circuit of the combustor, the magnitude and phase of the fuel system impedance for the fuel nozzle will be changed, which affects the fluctuating component of the heat release, and therefore the combustion dynamics of the combustor. Varying the fuel system impedance between two or more fuel lines within a combustor by varying the physical characteristics of two or more pre-orifices results in different fuel system acoustic impedance magnitudes and phases for the different fuel nozzles. The difference in the phase of the fuel system impedance between the fuel nozzles results in destructive interference of the heat release fluctuations associated with each of the fuel nozzles, reducing the amplitude of the combustion dynamics, and potentially smearing the frequency content of the combustion dynamics across a broader frequency range.

In some embodiments, the physical characteristics of the pre-orifice (e.g., location, size, position, shape, effective area, etc.) of each fuel line within a particular combustor may be the same, but may be varied compared to the pre-orifices of fuel lines within other combustors within the system. Varying the physical characteristics of the pre-orifices among the fuel lines of various combustors may vary the fuel system acoustic impedance and therefore, combustion dynamics, from combustor to combustor in a manner to reduce the combustion dynamics amplitudes, alter the combustion dynamics frequency, alter the phase of the combustion dynamics, and/or reduce modal coupling of the combustion dynamics among the plurality of gas turbine combustors. In some embodiments, the physical characteristics of the pre-orifice may be varied within a particular combustor, as well as among one or more combustors of the system in order to reduce dynamic amplitudes as well as coherence within and/or among the combustors of the system. For example, the physical characteristics of the pre-orifices among the combustors may be varied according to various patterns or groupings, as further explained below. Indeed, such variations may help reduce the amplitudes of the combustion dynamics and/or reduce the possibility of modal coupling of the combustors, particularly at frequencies that are aligned with resonant frequencies of the components of the gas turbine system.

With the forgoing in mind,FIG. 1is a schematic of an embodiment of a gas turbine system10having a plurality of combustors12and a fuel supply circuit14, such as an LLI fuel circuit14. In particular, each combustor12may be associated with a fuel circuit14that routes a liquid and/or gas fuel into the combustors12. For example, the fuel circuit14may be configured to route a liquid and/or gas secondary fuel16(e.g., secondary fuel16, second fuel16) to one or more fuel supply systems18of the combustor12. Each fuel supply system18of the combustor12includes a pre-orifice20disposed along a fuel conduit22(as illustrated inFIG. 2) of the combustor12, and a post-orifice24disposed along the fuel conduit22, and generally disposed within a fuel nozzle, such as a secondary fuel nozzle (as illustrated inFIG. 2) of the combustor12. The secondary fuel16may be provided to the combustor12from the fuel circuit14. From the fuel circuit14, the fuel flows through the pre-orifice20in the fuel conduit22, and may be then routed through the secondary fuel nozzle64via one or more post-orifices24. As noted above, varying the geometries of the pre-orifices20as described above may adjust the fuel system acoustic impedance of one or more of the secondary nozzles64, thereby leading to a shift in combustion dynamics frequency and/or greater variations in the frequency content of the resulting combustion dynamics, and/or reduced amplitudes of the combustion dynamics.

The gas turbine system10includes the one or more combustors12having the fuel line systems18, a compressor26, and a turbine28. The combustors12include primary fuel nozzles30which route a primary fuel32(e.g., liquid fuel and/or a gas fuel, a first fuel, etc.) into the combustors12for combustion within the primary combustion zone. Likewise, the combustors12include secondary fuel nozzles64(as illustrated inFIG. 2) which route a secondary fuel16into the combustors12for combustion within the secondary combustion zone. In particular, each combustor12is associated with the LLI fuel circuit14configured to provide the secondary fuel16to the one or more secondary fuel nozzles64via the one or more fuel conduits22. The combustors12ignite and combust an air-fuel mixture, and then the hot combustion gases34are passed into the turbine28. The turbine28includes turbine blades that are coupled to a shaft36, which is also coupled to several other components throughout the system10. As the combustion gases34pass through the turbine blades in the turbine28, the turbine28is driven into rotation, which causes the shaft36to rotate. Eventually, the combustion gases34exit the turbine system10via an exhaust outlet38. Further, the shaft36may be coupled to a load40, which is powered via rotation of the shaft36. For example, the load40may be any suitable device that may generate power via the rotational output of the turbine system10, such as a power generation plant or an external mechanical load. For instance, the load40may include an electrical generator, a propeller of an airplane, and so forth.

In an embodiment of the turbine system10, compressor blades are included as components of the compressor26. The blades within the compressor26are coupled to the shaft36, and will rotate as the shaft36is driven to rotate by the turbine28, as described above. The rotation of the blades within the compressor26compresses air43from an air intake42into pressurized air44. The pressurized air44is then fed into the primary fuel nozzles30of the combustors12. The primary fuel nozzles30mix the pressurized air44and fuel to produce a suitable mixture ratio for combustion (e.g., a combustion that causes the fuel to more completely burn) so as not to waste fuel or cause excess emissions.

As discussed in further detail below, the physical characteristics (e.g., position, size, location, shape, effective area, etc.) of the pre-orifice20may vary between different fuel conduits22of the same combustor12(as shown inFIGS. 5 and 6), and/or may vary between different fuel conduits22of different combustors12within the same gas turbine system10(as shown inFIGS. 7 and 8). As noted above, changing the physical characteristics of the pre-orifice20and/or the volume between the pre-orifice and the post-orifice24between different fuel conduits22of the same combustor12may help vary the fuel system acoustic impedance, and thereby help reduce unwanted vibratory responses within the combustor and/or in downstream components of the system10. Likewise, changing the physical characteristics of the pre-orifice20and/or the volume between the pre-orifice and the post-orifice24between fuel conduits22of different combustors12may help vary fuel system acoustic impedances, thereby helping to reduce amplitudes and/or coherence of the combustion dynamics, and/or alter the phase of the combustion dynamics.

In some embodiments, changes in the physical characteristics of the pre-orifice20for a specific fuel nozzle may change the effective area and/or the pressure ratio for that fuel nozzle, which in turn may result in variations of the mass flow of the secondary fuel16entering the combustor12. For example, the shape of the pre-orifice20(e.g., round, oval, square, polygonal, etc.) may be varied between and/or among different combustors12to vary the effective area and/or the pressure ratio of the pre-orifice20which would vary the mass flow of secondary fuel16entering the combustor12. As a further example, shifting the location of the pre-orifice20relative to the post-orifice24(e.g., closer to the post-orifice24or away from the post-orifice24) may increase or decrease the acoustic volume between the pre-orifice20and the post-orifice24, thereby resulting in a phase delay between one or more secondary fuel nozzles64, and causing destructive interference of the equivalence ratio fluctuations generated by the fuel nozzles64. In this manner, changing the physical characteristics may result in variations between the heat release of the LLI injectors within the combustor, thereby increasing the amount of temporal variation in the dynamic frequency content in the flame region, and/or increasing the destructive interference of the dynamic frequency content in the flame region, which may result in reducing the amplitude of the combustor tones and/or the coherence of the combustion dynamics.

In some embodiments, the size and/or shape of the pre-orifice20may vary between different fuel conduits22of the same combustor12(as shown inFIGS. 5 and 6), and/or may vary between different fuel conduits22of different combustors12within the same gas turbine system10(as shown inFIGS. 7 and 8). Further, while variations on the pre-orifice20are described, it should be noted that changes in the physical characteristics of the post-orifice24(e.g., size, shape, location, position, effective area, etc.) may also help reduce the amplitudes of the combustion dynamics within the system10. Likewise, varying the physical characteristics of the fuel conduit22(e.g., length, width, circumference, diameter, effective area, etc.) in order to change the distance and the acoustic volume between the pre-orifice20and the post-orifice24may help reduce unwanted vibratory responses within the gas turbine system10.

FIG. 2is a schematic view of an embodiment of one of the combustors12depicted inFIG. 1, where the combustor12includes the fuel supply system18(e.g., a first fuel supply system17, a second fuel supply system19, etc.) having the pre-orifice20and the post-orifice24disposed along the fuel conduit22. It should be noted in certain embodiments; the pre-orifice20may be disposed anywhere along the fuel conduit22, as illustrated inFIG. 2. In particular, the physical characteristics (e.g., location, size, shape, dimensions, position) of the components of the fuel supply system18(e.g., the pre-orifice20, the fuel conduit22, and the post-orifice24) may be varied between different fuel supply systems18of the combustor12. For example, the position of the pre-orifice20relative to the post-orifice24(and thus intermediate distance and volume) of the first fuel supply system17may be different than the position of the pre-orifice20(and thus intermediate distance and volume) relative to the post-orifice24of the second fuel supply system19, as described in detail below. Such variations may vary the fuel system acoustic impedance of the associated secondary fuel nozzles64leading to combustion dynamics frequencies that are different and/or phase-shifted between the fuel nozzles64and/or between combustors12, thereby reducing unwanted vibratory responses in the gas turbine system10. For example, maximum destructive interference between the fuel nozzles64occurs when the phase delay between the fuel nozzles64is approximately 180 degrees.

The combustor12includes a head end50having an end cover52, a combustor cap assembly54, and a primary combustion zone56. The end cover52and the combustor cap assembly54may be configured to support the primary fuel nozzles30in the head end50. In the illustrated embodiment, the primary fuel nozzles30route the primary fuel32to the primary combustion zone56. The combustor12includes an outer wall (e.g., flow sleeve68) disposed circumferentially about an inner wall (e.g., combustion liner66). The inner wall may also include a transition piece69, which generally converges towards a first stage of the turbine28. An impingement sleeve67is disposed circumferentially about the transition piece69. Further, the primary fuel nozzles30receive the pressurized air44from the annulus58(e.g., between transition piece69and impingement sleeve67and between liner66and flow sleeve68) of the combustor12and combine the pressurized air44with the primary fuel32to form an air/fuel mixture that is ignited and combusted in the primary combustion zone56to form combustion gases (e.g., exhaust).

The combustion gases flow in a direction60to a secondary combustion zone62. The LLI fuel circuit14provides the secondary fuel16which flows through the pre-orifice20in the fuel conduit22to the post-orifice24. In particular, the post-orifice24in the secondary fuel nozzles64receive the secondary fuel16from the fuel conduit22, and route the secondary fuel16into the secondary combustion zone62to the stream of combustion gases. Further, the secondary fuel nozzles64may receive the pressurized air44from the annulus58of the combustor12and combine the pressurized air44with the secondary fuel16to form an air/fuel mixture that is ignited and combusted in the secondary combustion zone62to form the combustion gases. More specifically, the pressurized air44flows through the annulus58between a transition piece69and an impingement sleeve67, and then between a liner66and a flow sleeve68of the combustor12to reach the head end50. The combustion gases flow in the direction60through the transition piece69of the combustor12, and pass into the turbine28, as noted above.

As described above, combustion dynamics (e.g., generation of hot combustion gases) within the primary combustion zone56and the secondary combustion zone62may lead to unwanted vibratory responses within the combustor12. In may be helpful to reduce combustion dynamics within or among the combustors12to help reduce unwanted vibratory responses. Accordingly, in some embodiments, varying the physical characteristics of the pre-orifice within and/or among the combustors12may help reduce vibratory responses in the gas turbine system10, and minimize vibrational stress, wearing, performance degradation, or other undesirable impacts to the components of the gas turbine system10(e.g., turbine blades, turbine shrouds, turbine nozzles, exhaust components, combustor transition piece, combustor liner, etc.).

In some embodiments, the position of the pre-orifice20relative to the post-orifice24(and thus the intermediate distance and volume) may be varied between the fuel supply systems18of the combustor12, such that the pre-orifice20is shifted along the fuel conduit22to be closer to or further away from the post-orifice24and the secondary fuel nozzles64. For example, a first distance72between the pre-orifice20and the post-orifice24of the first fuel supply system17may be different (e.g., longer, shorter, greater, smaller, etc.) than a second distance74between the pre-orifice20and the post-orifice24of the second fuel supply system19. Indeed, the distances may vary or may be configured to vary based on the location where the pre-orifice20is disposed along the fuel conduit22. In certain embodiments, varying the distance72,74between the pre-orifice20and the post-orifice24may be done by increasing or decreasing the length of the fuel conduit22upstream and downstream of the pre-orifice via one or more sections of flanged tubing. In certain embodiments, the length of the fuel conduits22may be the same between the fuel supply systems18, but the location of the pre-orifices20disposed along the fuel conduit22may vary between the fuel supply systems28. Indeed, varying the distance (e.g., the first distance72and the second distance74of the pre-orifice20relative to the post-orifice24) between the fuel supply systems18may result in phase delays between the fuel supply systems18, leading to destructive interference of the heat release fluctuations of the fuel nozzles64associated with each fuel supply system18, thereby reducing the amplitude of the combustor tones and possibly the coherence of the combustion dynamics.

Further, in some embodiments, physical characteristics (e.g., position, location, size, shape, dimensions, effective area, etc.) of other components of the fuel supply system18may vary between different fuel supply systems18(e.g., the first fuel supply system17and the second fuel supply system19), as further described with respect toFIG. 3. For example, the size and/or effective area of the pre-orifice20or the post-orifice24(e.g., diameter of the opening of the pre-orifice20or the post-orifice24), the shape of the pre-orifice20or the post-orifice24opening (e.g., oval, circular, rectangular, any geometric shape, etc.), the angle of pre-orifice20or the post-orifice24opening (e.g., slanted upward at an angle, slanted downward at an angle, etc.), and so forth may vary between the fuel supply systems18. Further, in some embodiments, the pre-orifice20and the post-orifice24may be an array or pattern of holes. In such embodiments, the size, the shape, the pattern and/or arrangement of the pre-orifice20holes and the post-orifice24holes may vary between different fuel conduits22of the combustor12. In some embodiments, the pre-orifice20and/or the post-orifice24may vary among the plurality of combustors12(e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, or more combustors12) with different diameters, shapes, sizes, etc.

In addition, the physical characteristics of the fuel conduit22may also vary between different fuel conduits22of the combustor12. For example, in addition to varying the length (e.g., the first distance72or the second distance74) of the fuel conduits22, the disclosed embodiments may also vary the diameter of the fuel conduit22, and so forth. Indeed, one or more physical characteristics of the disclosed embodiments also may vary each component within the fuel supply system18between different fuel supply systems18of the combustor12, such that the combustion dynamics at each secondary fuel nozzle64are different (in terms of phase and/or frequency) to help reduce unwanted vibratory responses within the gas turbine system10.

In some embodiments, the dynamic amplitudes as well as coherence may be reduced between different combustors12of the system10by varying the physical characteristics of the pre-orifices among the combustors12, as further described with respect toFIG. 4. For example, while the position of the pre-orifice22relative to the post-orifice24may be the same among the fuel supply systems18of a single combustor12, the position of the pre-orifice22relative to the post-orifice24may be varied between fuel supply systems18of different combustors12within the system10. Further, the physical characteristics (e.g., size, position, shape, location, dimensions, effective area, etc.) of the components of the fuel supply system18(e.g., the pre-orifice20, the fuel conduit22, the post-orifice24) may vary between different combustors12of the system10. In some embodiments, the physical characteristics of the components of the fuel supply system28may vary between fuel lines18of the same combustor12, as well as between fuel lines18of different combustors12.

FIG. 3is a cross-sectional view of an embodiment of the combustor12depicted inFIG. 2, illustrating one or more fuel supply systems18each receiving the secondary fuel16. Particularly, the secondary fuel16is routed through the pre-orifice20, through the fuel conduit22, and then through the post-orifice24, of the secondary fuel nozzles64(as illustrated inFIG. 2). The fuel conduits22, composed of one or more sections of flanged tubing, extend along the outside of the flow sleeve68of the combustor12, as illustrated inFIG. 2, such that the fuel conduits22route the secondary fuel16from the pre-orifice20to the one or more secondary fuel nozzles64. While the illustrated embodiment depicts the fuel conduits22with alternating large and small diameters, as further explained below, it should be noted that in other embodiments, the fuel conduits22may have any sized diameters.

In particular, the physical characteristics of the components of each fuel supply system18within the combustor12may vary, such that the size, shape, dimensions, configuration, position, location, and so forth, are different between the fuel supply systems18of a single combustor12and/or between adjacent combustors12. For example, in the illustrated embodiment, the size of the pre-orifice20and the fuel conduit22is different for each adjacent fuel supply system18. For example, a first diameter78of the fuel conduit22of the first fuel supply system17is greater than a second diameter80of the fuel conduit22of the second fuel supply system19. It should be noted that while the illustrated embodiment depicts alternating and/or adjacent fuel supply systems18(e.g., the first supply system17and the second fuel supply system19) having variations in the physical characteristics of the pre-orifice20and/or the fuel conduit22, in other embodiments, any combination and/or pattern of fuel supply systems18may have variations in the physical characteristics of the components of the fuel supply systems18. Further, there may be one or more physical characteristics variations between any two fuel supply systems18. As noted above, the illustrated embodiment depicts fuel conduits22that alternate between the first diameter78and the second diameter80. In other embodiments, the diameter size of the fuel conduits22may alternate between 2, 3, 4, 5, 6, 7, 8, 9, 10 or more different sizes, shapes, etc.

FIG. 4is a schematic of an embodiment of the gas turbine system10ofFIG. 1, depicting a plurality of combustors12each having one or more fuel supply systems18. In particular, each fuel supply system18includes various components such as the pre-orifice20, the fuel conduit22, and the post-orifice24, and the physical characteristics (e.g., size, position, dimensions, location, shape, geometric characteristics, etc.) of one or more components of the fuel supply system18may vary within and/or between the one or more combustors12of the system10. As noted above, variations within the components of the fuel supply systems18of a single combustor12and/or between the components of fuel supply systems18of one or more combustors12result in changes to the fuel system acoustic impedance for one or more fuel nozzles64, thereby leading to a shift in combustion dynamics frequency and/or greater variations in the frequency content of the resulting combustion dynamics, and/or reduced amplitudes of the combustion dynamics, and/or differences in phase of the combustion dynamics between two or more combustors12. In particular, the illustrated embodiment depicts the variations of the fuel supply systems18within the combustor12and/or between combustors12.

In the illustrated embodiment, the gas turbine system10includes four combustors12coupled to the turbine28. However, in other embodiments, the gas turbine system10includes any number of combustors12(e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or more combustors). In particular, each combustor12includes the fuel circuit14configured to provide the secondary fuel16to the pre-orifice20positioned in the fuel conduit22near the head50of the combustor12. Further, the secondary fuel16is routed through the pre-orifice20, through the fuel conduit22, and through the post-orifice24. In particular, the post-orifice24is configured to route the secondary fuel16from the secondary fuel nozzle64, into the secondary combustion zone62. As noted above, combustors12ignite and combust the air-fuel mixture (e.g., the secondary fuel16and/or compressed air44), and then the hot combustion gases34are passed into the turbine28. As the combustion gases34pass through the turbine blades in the turbine28, various combustion dynamics may produce unwanted vibratory responses.

In some embodiments, the components of the fuel supply system18within the combustor12have variability among other components of the fuel supply system18within the same combustor12. For example, in a first combustor75, the first distance72(and thereby the acoustic volume) between the pre-orifice20and the post-orifice24of the first fuel supply system17is greater than a second distance74(and thereby the acoustic volume) between the pre-orifice20and the post-orifice24of the second fuel supply system19. Particularly, in the illustrated example, the pre-orifice20is shifted along the fuel conduit22so that it is closer or further away from the post-orifice24. As noted above, varying the distance between the pre-orifice20and the post-orifice24varies the acoustic volume between the pre-orifice20and the post orifice24, and may be done by increasing or decreasing the length (and/or diameter) of one or more sections of tubing (e.g. flanged tubing), making up the fuel conduit22. The pre-orifice20can be contained between the flanges (e.g. sandwich plate), or embedded as part of one of the sections of tubing. By varying the length of the sections of fuel conduit22positioned upstream and downstream of the pre-orifice20, the distance (and/or diameter) between the pre-orifice and the post-orifice can be varied between fuel supply systems18. Further, varying the acoustic volume among different fuel supply systems18(e.g., first fuel supply system17and the second fuel supply system19) within the same combustor (e.g., the first combustor75) may help to vary the fuel system impedance between the combustors12. It should be noted that in other embodiments, as shown inFIG. 7, the combustor12may have variability among other fuel supply system18components, such as the size and/or shape and/or effective areas of the pre-orifice20or the post-orifice24, the length of the fuel conduit22, the diameter of the fuel conduit22, the volume of the fuel conduit22, the construction material of the components of the fuel supply systems18, and so forth.

In some embodiments, the components of the fuel supply system18within the combustor12may have variability compared to the components of the fuel supply systems18among other combustors12within the system10(as shown inFIGS. 4, 7, and 8. For example, while the physical characteristics of the components (e.g., the pre-orifice20, the fuel conduit22, the post-orifice24) of the fuel supply systems18of the second combustor77may be substantially similar, in some embodiments, the physical characteristics of the components of the fuel supply systems18of the second combustor77may be different from the physical characteristics of the fuel supply systems18of the first combustor75(e.g., the first fuel supply system17and/or the second fuel supply system19), and the physical characteristics of the components of the fuel supply system18of the third combustor79may be different from the physical characteristics of the fuel supply systems18of the first combustor75and/or the second combustor77as inFIGS. 7 and 8). In the illustrated embodiment, the distance of the pre-orifice20relative to the post-orifice24of the second combustor77may be different between one or more fuel supply systems18of the second combustor77. In other words, the position of the pre-orifice20along the fuel conduit22relative to the post-orifice24may be different between the fuel supply systems18of the second combustor77. Indeed, it should be noted that the pre-orifice20may be disposed anywhere along the fuel conduit22, such that the distance between the pre-orifice20and the post-orifice24along the fuel conduit22may be different between fuel supply systems18despite having a substantially similar length fuel conduit22, as illustrated in the second combustor77. Further, the position of the pre-orifice20along the fuel conduit22relative to the post-orifice24(e.g., the distance between the pre-orifice20and the post-orifice24) within the second combustor77is different than the first distance72and/or the second distance74within the first combustor75. Accordingly, the combustion dynamics and the acoustic fuel system impedance of the first combustor75relative to the second combustor77are different, thereby helping to reduce combustion dynamic amplitudes and/or possibly modal coupling of the combustion dynamics between the two combustors12, and/or alter the phase delay between the two combustors12.

In some embodiments, as shown inFIGS. 5 and 7, other physical characteristics may be varied between the components of the fuel supply systems18within the same combustor12. For example, in the illustrated embodiment, the first diameter78of a third fuel supply system21of a third combustor79is larger than the second diameter80of a fourth fuel supply system23of the same third combustor79. In some embodiments, the first distance72of the third fuel supply system21is greater than the second distance74of the fourth fuel supply system23. Further, in some embodiments, the shape or physical configuration of the fuel supply systems18may vary within and/or between the combustors12. For example, in a fourth combustor81shown inFIG. 4, the shape of the fuel conduit22within the fuel supply system25is curved convexly towards the exit70of the fourth combustor81. In other physical configurations of the fuel supply system18, the shape of the fuel conduit22may include one or more angles (e.g., jagged shape), waves, rough edges, and so forth, such that the one or more tubing sections of the fuel conduit22is shaped differently than adjacent fuel conduits22within or between the combustors12. For example, a fuel supply system27of the fourth combustor81includes a fuel conduit22in a wave form. Further, in some embodiments, the fuel conduits22may include protrusions82(e.g., waves, rough edges, angles, and so forth) on an inner surface84of the fuel conduit22that provides variations in the fuel flow of the secondary fuel16. The protrusions82may be formed from the same material as the fuel conduit22. As noted above, such variations of the physical characteristics between various components of the fuel supply systems18help to reduce the amplitudes of the combustor tones and/or the coherence of the combustion dynamics.

FIG. 5is a schematic of an embodiment of the third fuel supply system21and the fourth fuel supply system23of the third combustor79, where the third combustor79is illustrated inFIG. 4. Specifically, the illustrated embodiment depicts physical variations between the third fuel supply system21and the fourth fuel supply system23, such as variations in distance between the pre-orifice20and the post-orifice24and variations in diameter of the fuel conduit22. For example, the first distance72between the pre-orifice20and the post-orifice24of the third fuel supply system21is greater than the second distance74between the pre-orifice20and the post-orifice24of the fourth fuel supply system23. Further, the first diameter78of the fuel conduit22of the third fuel supply system21is greater than the second diameter80of the fuel conduit22of the fourth fuel supply system23. Accordingly, a first acoustic volume83within the third fuel supply system21may be greater than a second acoustic volume85within the fourth fuel supply system23. It should be noted that in other embodiments, the first acoustic volume83within a particular fuel supply system18may be different than the second acoustic volume85within another (e.g., adjacent) fuel supply system18.

In some embodiments, other variations between the fuel supply systems18(e.g., the third fuel supply system21and the fourth fuel supply system23) may exist. In certain embodiments, the width of the pre-orifice20may vary between different fuel supply systems18. For example, a first width86(or diameter, cross-sectional area, shape, etc.) of the pre-orifice20in the third fuel supply system21may be greater than a second width88(or diameter, cross-sectional area, shape, etc.) of the pre-orifice20in the fourth fuel supply system23. Similarly, a third width90(or diameter, cross-sectional area, shape, etc.) of the post-orifice24of the third fuel supply system21may be greater than a fourth width92(or diameter, cross-sectional area, shape, etc.) of the post-orifice24of the fourth fuel supply system23. Further, the width of the pre-orifice20(e.g., the first width86and/or the second width88) may be different than the width of the post-orifice24(e.g., the third width90and/or the fourth width92) within and/or between the fuel supply systems18(e.g., between the fuel supply systems21and23).

In yet other embodiments, the pre-orifices20and/or the post-orifices24may have physical characteristics (e.g., shape, dimensions, holes, thickness, material, arrangement, pattern, hole shape, hole size, etc.) that are different within and/or between combustors12. For example, a first pre-orifice94of the third fuel supply system21may be different than a second pre-orifice96of the fourth fuel supply system23, as explained further with respect toFIG. 6.

FIG. 6is a schematic of an embodiment of the pre-orifices20of the fuel supply systems18. Specifically, the pre-orifice94of the third fuel supply system21may have physical characteristics that vary from the second pre-orifice96of the fourth fuel supply system23. For example, the pre-orifices94and96have differences in hole shapes and patterns, which may change the effective area and/or the pressure ratio of the mass flow of the secondary fuel16through the pre-orifices94and96. In the illustrated embodiment, the pre-orifice94may include five circular holes arranged in an annular pattern around a central hole100. Further, the pre-orifice96may include five triangular holes102arranged in an annular pattern around a central square104. However, it should be noted that in other patterns and configurations, any number of holes (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.) may be arranged in any shape or pattern (symmetrical, spirals, random, waves, checkered, etc.), such that the pre-orifices94and96are different from one another.

In some embodiments, as shown inFIG. 7, variations between the fuel supply systems18in different combustors (e.g., between the first fuel supply system17of the first combustor75and the third fuel supply system21of the second combustor79) may exist, instead of, or in addition to, differences between the fuel supply systems18of each combustor. In the first fuel supply system17of the first combustor75, the pre-orifice20has a first thickness106and multiple orifice holes, each having a width116(or diameter, cross-sectional area, shape, etc.); the fuel conduit22has a first diameter126; the post-orifice24defines a first width136; and a first acoustic volume123is defined over the distance72between the pre-orifice20and the post-orifice24. In the second fuel supply system19of the first combustor75, the pre-orifice20has a second thickness108and an orifice hole having a width118(or diameter, cross-sectional area, shape, etc.); the fuel conduit22has a second diameter128; the post-orifice24defines a second width138; and a second acoustic volume133is defined over the distance74between the pre-orifice20and the post-orifice24. In the third fuel supply system21of the third combustor79, the pre-orifice20has a third thickness112and an orifice hole having a width86(or diameter, cross-sectional area, shape, etc.); the fuel conduit22has a third diameter78; the post-orifice24defines a third width90; and a third acoustic volume83is defined over the distance72between the pre-orifice20and the post-orifice24. In the fourth fuel supply system23of the third combustor79, the pre-orifice20has a fourth thickness114and an orifice hole having a width88(or diameter, cross-sectional area, shape, etc.); the fuel conduit22has a fourth diameter80; the post-orifice24defines a fourth width92; and a fourth acoustic volume85is defined over the distance74between the pre-orifice20and the post-orifice24.

As illustrated, the first fuel supply system17of the first combustor75has components that are different from the third fuel supply system21of the third combustor79(e.g., in number of orifices, width/size of pre-orifice, thickness of pre-orifice, diameter of fuel conduit, and/or width of post-orifice), even though the distance72between the pre-orifice20and the post-orifice24is the same. Additionally, or alternately, the second fuel supply system19of the first combustor75has components that are different from the fourth fuel supply system23of the third combustor79(e.g., in number of orifices, width/size of pre-orifice, thickness of pre-orifice, diameter of fuel conduit, and/or width of post-orifice), even though the distance74between the pre-orifice20and the post-orifice24is the same. The differences in the number of orifices and the width/size of the pre-orifices is shown schematically inFIG. 8.

Technical effects of the invention include reducing unwanted vibratory responses associated with combustion dynamics within or among combustors12of the gas turbine system10by varying the physical characteristics of the pre-orifice20within the one or more fuel supply systems18of the combustor12to adjust the fuel system acoustic impedance (magnitude and phase) within the system10. For example, from one fuel conduit22to another, the position of the pre-orifice20may be shifted along the fuel conduit22, so that it is closer or further away from the post-orifice24, thereby changing the acoustic volume between the pre-orifice20and the post-orifice24. In other embodiments, the physical characteristics of other components of the fuel supply systems18(e.g., the post-orifice24, the fuel conduit22, and the pre-orifice20) may be varied within or among the combustors12. For example, the dimensions (e.g., length, width, diameter, volume) of the fuel conduit22, the size and/or shape (e.g., width, length, diameter, effective area) of the pre-orifice20and/or the post-orifice24, the patterns or configurations of the pre-orifice20or the post-orifice24(e.g., holes, arrangements of the holes, etc.), the shape of the fuel conduit22, the inner surface of the fuel conduit22, and so forth, may vary between one or more fuel supply systems18within the same combustor12or among different combustors12.