Lean-burn injector with supply line switching

Abstract

A lean fuel spray nozzle (60) includes a lean fuel spray nozzle head (64) including a pilot fuel injector (70) having a pilot fuel injector outlet (71) and a main fuel injector (72) having a main fuel injector outlet (73); a supply arm (62) adapted to supply pilot fuel from a pilot conduit (175) to the pilot fuel injector (70) through a pilot fuel circuit (67) and to supply main fuel from a main conduit (177) to the main fuel injector (72) through a main fuel circuit (69); and a switching device (74) including a switching valve (180) adapted to switch between a main open position in which the main fuel injector is in fluid communication with the main conduit such that main fuel is sprayed through the main fuel injector outlet and a main closed position in which the main fuel injector outlet is not in fluid communication with the main conduit such that main fuel is prevented from flowing through the main fuel injector.

Description

Technical Field

[0001] This disclosure relates to injectors for lean combustion systems, and more particularly to injectors for lean combustion systems in gas turbine engines with improved thermal management. Background Technology

[0002] Gas turbine engines are used in aircraft, industrial and marine applications.

[0003] Gas turbine engines used in aircraft applications typically include an axially arranged fan, one or more compressors, a combustion system, and one or more turbines. The combustion system typically includes multiple fuel injectors with fuel spray nozzles that combine fuel and airflow to generate a spray of atomized liquid fuel that enters the combustion chamber. The mixture of air and atomized liquid fuel is then burned in the combustion chamber, and the resulting thermal combustion products then expand and thereby drive one or more turbines.

[0004] There is a continued need to reduce the environmental impact of gas turbine engines in terms of carbon emissions and nitrogen oxides (NOx), which begin to form at high temperatures and increase exponentially with increasing temperature.

[0005] To address NOx emissions, "lean combustion" technology has been proposed. In lean combustion, the air-fuel ratio (AFR) is greater than the stoichiometric ratio, which allows the combustion temperature to be kept within known limits for reducing NOx production.

[0006] The lean combustion architecture is characterized by fuel spray nozzles (FSNs) with two separate fuel streams: a "pilot" stream and a "main" stream. The pilot stream is always open, while the main stream can be opened and closed. Opening the main stream is called "staging in," and when staging in, the diversion of fuel along each stream is set by the control system to minimize emissions (typically soot and NOx).

[0007] As the main pipeline gradually shuts off (is closed), the fuel in the main pipeline stagnates and thus absorbs heat, which is undesirable due to its impact on fuel conditions. Stagnant fuel poses safety risks: firstly, it may cause the pipeline to expand and rupture; secondly, stagnant fuel decomposes when heated, and the decomposition products may spread to parts of the system and cause blockages.

[0008] To address this issue, known lean-burn architectures feature recirculated fuel systems; these systems recirculate some fuel back to the central fuel system to maintain continuous flow during phase-out. This requires a series of active valves and—due to the remote location of the splitter unit—a significant amount of additional piping. The architecture includes active valves that toggle flow opening or closing to the main fuel passages in the FSN. An example of this architecture is disclosed in US 2018 / 0372322. Summary of the Invention

[0009] Therefore, there is a need for a lean combustion system for gas turbine engines in aircraft, industrial and marine applications, which has a reduced amount of piping and active valve components, thereby reducing weight and complexity, without compromising the critical function of keeping fuel flowing in the pipeline at a sufficient rate so that fuel decomposition products do not accumulate.

[0010] According to a first aspect, a lean fuel spray nozzle is provided, comprising: a lean fuel spray nozzle head including an ignition fuel injector having an ignition fuel injector outlet and a main fuel injector having a main fuel injector outlet; a supply arm adapted to supply ignition fuel from an ignition conduit through an ignition fuel circuit to the ignition fuel injector, and to supply main fuel from a main conduit through a main fuel circuit to the main fuel injector; and a switching device disposed upstream of the supply arm, the switching device including a switching valve adapted to switch between a main open position and a main closed position, wherein in the main open position, the main fuel injector outlet is in fluid communication with the main conduit through the main fuel circuit, such that main fuel is adapted to flow through the main fuel injector and be sprayed through the main fuel injector outlet; and in the main closed position, the main fuel injector outlet is not in fluid communication with the main conduit through the main fuel circuit and the flow of main fuel is prevented through the main fuel injector. The switching valve in the main closed position is adapted to allow the main conduit to be in fluid communication with the ignition fuel injector through the ignition fuel circuit, thereby allowing main fuel to flow in the ignition fuel circuit.

[0011] Compared to known fuel spray nozzles, in the first-aspect fuel spray nozzle, as the main fuel gradually withdraws, the main fuel continues to flow in the ignition fuel circuit and thus in the main pipe, thereby minimizing the risk of fuel absorbing heat. Therefore, a complex recirculation system with additional piping and valves to prevent fuel stagnation in the main pipe is no longer needed, thus simplifying the lean-burn architecture.

[0012] In this disclosure, upstream and downstream are relative to the fuel flow through the fuel spray nozzle.

[0013] When the switching valve is in the main closed position, the main fuel flowing in the main fuel circuit can be sprayed through the outlet of the ignition fuel injector.

[0014] The lean fuel spray nozzle may further include a flange adapted to secure the lean fuel spray nozzle to the burner housing, with the switching device arranged upstream of the flange.

[0015] In use, when installed on the burner housing, the switching device can be configured to be arranged radially outward relative to the burner housing.

[0016] In an embodiment, when the switching valve is in the main closed position, the main fuel and the ignition fuel can be mixed in the ignition fuel circuit.

[0017] The lean fuel spray nozzle may further include a check valve arranged between the ignition fuel circuit and the main fuel circuit.

[0018] The switching valve may include an inlet adapted to receive main fuel from the main pipeline, a main outlet in fluid communication with the main fuel injector, and an ignition outlet in fluid communication with the ignition fuel injector. The lean fuel spray nozzle may further include a connecting pipe adapted to connect the ignition outlet of the switching device to the ignition fuel circuit, with a check valve arranged along the connecting pipe. The check valve may be located upstream of the switching valve.

[0019] In an embodiment, the ignition fuel circuit may include a primary ignition fuel circuit including a primary ignition fuel supply pipe and a secondary ignition fuel circuit including a secondary ignition fuel supply pipe.

[0020] The primary ignition fuel supply pipe and the secondary ignition fuel supply pipe can be configured to supply ignition fuel and main fuel to the ignition fuel injector outlet, respectively.

[0021] When the switching valve is in the main closed position, the secondary ignition fuel circuit can be fluidly connected to the main pipeline.

[0022] When the switching valve is in the main closed position, the main fuel from the main pipeline can flow in the secondary ignition fuel supply pipe and can be sprayed through the ignition fuel injector outlet.

[0023] When the switching valve is in the main closed position, the main fuel from the main pipeline and the ignition fuel from the ignition pipeline are sprayed through the ignition fuel injector outlet.

[0024] When the switching valve is in the main open position, the secondary ignition fuel circuit may not be fluidly connected to the main pipeline.

[0025] When the switching valve is in the main open position, the main fluid can flow only in the main fuel circuit.

[0026] In one embodiment, the secondary ignition fuel circuit may be connected to the main pipeline upstream of the switching valve at a connector. When the switching valve is in the main open position, the secondary ignition fuel circuit is in fluid communication with the main pipeline. In this embodiment, the lean fuel spray nozzle may further include a channel restrictor disposed downstream of the connector in the secondary ignition fuel circuit to limit the amount of main fuel flowing in the secondary ignition fuel circuit when the switching valve is in the main open position.

[0027] The channel restrictor may be configured to allow a relatively small amount of main fuel to pass through the secondary ignition fuel circuit, relative to the amount of main fuel flowing in the main fuel circuit, when the switching valve is in the main open position. For example, the ratio of the mass flow rate of the main fuel flowing in the secondary ignition fuel circuit to the mass flow rate of the main fuel flowing in the main fuel circuit may be less than 0.5, for example less than 0.1, or less than 0.05, or less than 0.01, and / or greater than 0.0001, for example greater than 0.0005, or greater than 0.001.

[0028] According to another aspect, a gas turbine engine is provided, comprising: a fan including a plurality of fan blades; an engine core including a compressor, a burner, a turbine, and a spindle connecting the turbine to the compressor; wherein the burner includes a combustion chamber and a plurality of lean fuel spray nozzles according to the first aspect.

[0029] The gas turbine engine may further include a gearbox that receives input from the spindle and outputs drive to the fan so as to drive the fan at a lower speed than the spindle.

[0030] All the features disclosed in the lean fuel spray nozzle of the first aspect can be applied to the gas turbine engine of the second aspect.

[0031] For example, the lean fuel spray nozzle of the gas turbine engine in the second aspect may include a check valve arranged between the ignition fuel circuit and the main fuel circuit.

[0032] For example, the switching valve of the lean fuel spray nozzle of the engine in the second aspect may include an inlet adapted to receive main fuel from the main pipe, a main outlet in fluid communication with the main fuel injector, and an ignition outlet in fluid communication with the ignition fuel injector; the lean fuel spray nozzle may include a connecting pipe adapted to connect the ignition outlet of the switching device to the ignition fuel circuit, and a check valve is arranged along the connecting pipe.

[0033] As described elsewhere herein, this disclosure relates to a gas turbine engine. This gas turbine engine may include an engine core comprising a turbine, a combustor, a compressor, and a spindle connecting the turbine to the compressor. This gas turbine engine may include a fan (with fan blades) located upstream of the engine core.

[0034] The arrangement disclosed herein is particularly, but not exclusively, advantageous for a gearbox-driven fan. Thus, the gas turbine engine may include a gearbox that receives input from the spindle and outputs drive to the fan to drive the fan at a lower speed than the spindle. The input to the gearbox may be directly from the spindle or indirectly from the spindle, for example, via a spur shaft and / or gears. The spindle may rigidly connect the turbine and the compressor such that the turbine and the compressor rotate at the same speed (where the fan rotates at a lower speed).

[0035] The gas turbine engine described and / or claimed herein may have any suitable overall architecture. For example, the gas turbine engine may have any desired number of shafts connecting the turbine and the compressor, such as one, two, or three shafts. By way of example only, the turbine connected to the mandrel may be a first turbine, the compressor connected to the mandrel may be a first compressor, and the mandrel may be a first mandrel. The engine core may further include a second turbine, a second compressor, and a second mandrel connecting the second turbine to the second compressor. The second turbine, the second compressor, and the second mandrel may be arranged to rotate at a higher speed than the first mandrel.

[0036] In this arrangement, the second compressor may be located axially downstream of the first compressor. The second compressor may be arranged to receive (e.g., directly, or via a generally annular duct) the flow from the first compressor.

[0037] The gearbox may be arranged to be driven by a spindle configured to rotate at a minimum speed (e.g., in use) (e.g., the first spindle in the example above). Alternatively, the gearbox may be arranged to be driven solely by a spindle configured to rotate at a minimum speed (e.g., in use) (e.g., only the first spindle in the example above, not the second spindle). Alternatively, the gearbox may be arranged to be driven by any one or more shafts, such as the first shaft and / or the second shaft in the example above.

[0038] The gearbox can be a reduction gearbox (because the output speed to the fan is lower than the input speed from the spindle). Any type of gearbox can be used. As described in more detail elsewhere in this document, for example, the gearbox can be a "planetary" or "radial" gearbox. The gearbox can have any desired reduction ratio (defined as the input shaft speed divided by the output shaft speed), for example, greater than 2.5, for example, in the range of 3 to 4.2, or 3 to 3.8, or 3.2 to 3.8, for example, approximately or at least 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, or 4.2. For example, the gear ratio can be between any two values ​​mentioned in the preceding sentence. By way of example only, the gearbox can be a "radial" gearbox with a ratio in the range of 3.1 or 3.2 to 3.8. In some arrangements, the gear ratio can be outside these ranges.

[0039] As used herein, cruise conditions have a conventional meaning and will be readily understood by those skilled in the art. Therefore, for a given gas turbine engine used in an aircraft, those skilled in the art will immediately recognize that cruise conditions refer to the engine's operating point in the mid-cruise phase of the aircraft (to which the gas turbine engine is designed) for a given mission (which may be referred to in the industry as the "economic mission"). In this respect, the mid-cruise phase is a point in the aircraft's flight cycle where 50% of the total fuel burned between the peak of the climb and the start of the descent has been burned (which can be approximated by the midpoint between the peak of the climb and the start of the descent—in terms of time and / or distance). Therefore, considering the number of engines supplied to the aircraft, cruise conditions define the operating point of the gas turbine engine, which provides thrust that will ensure steady-state operation (i.e., maintaining a constant altitude and a constant Mach number) in the mid-cruise phase of the aircraft (to which the gas turbine engine is designed) of the aircraft. For example, in the case of an engine designed to be attached to an aircraft with two engines of the same type, cruise conditions provide half of the total thrust required for steady-state operation of the aircraft in the mid-cruise phase.

[0040] In other words, for a given gas turbine engine used in an aircraft, cruise conditions define the engine's operating point, which provides specific thrust (required to be provided at a given mid-cruise Mach number—in combination with any other engines on the aircraft—as designed to provide steady-state operation for the attached aircraft) under mid-cruise atmospheric conditions (defined by the mid-cruise altitude according to ISO 2533). For any given gas turbine engine used in an aircraft, the mid-cruise thrust, atmospheric conditions, and Mach number are known, and therefore the engine's operating point under cruise conditions is well-defined.

[0041] By way of example only, the forward speed under cruise conditions can be any point in the range of Mach 0.7 to 0.9 (e.g., 0.75 to 0.85, 0.76 to 0.84, 0.77 to 0.83, 0.78 to 0.82, 0.79 to 0.81, approximately Mach 0.8, approximately Mach 0.85, or in the range of 0.8 to 0.85). Any single speed within these ranges can be a part of the cruise conditions. For some aircraft, cruise conditions can extend beyond these ranges, for example, below Mach 0.7 or above Mach 0.9.

[0042] By way of example only, cruise conditions may correspond to standard atmospheric conditions (according to the International Standard Atmosphere, ISA) at an altitude ranging from 10,000 m to 15,000 m, for example, from 10,000 m to 12,000 m, for example, from 10,400 m to 11,600 m (approximately 38,000 ft), for example, from 10,500 m to 11,500 m, for example, from 10,600 m to 11,400 m, for example, from 10,700 m (approximately 35,000 ft) to 11,300 m, for example, from 10,800 m to 11,200 m, for example, from 10,900 m to 11,100 m, for example, approximately 11,000 m. Cruise conditions may correspond to standard atmospheric conditions at any given altitude within these ranges.

[0043] By way of example only, cruise conditions can correspond to the operating point of an engine that provides a known required thrust level (e.g., values ​​ranging from 30 kN to 35 kN) under standard atmospheric conditions (according to the International Standard Atmosphere) at a forward Mach number of 0.8 and an altitude of 38,000 ft (11,582 m). By way of further example only, cruise conditions can correspond to the operating point of an engine that provides a known required thrust level (e.g., values ​​ranging from 50 kN to 65 kN) under standard atmospheric conditions (according to the International Standard Atmosphere) at a forward Mach number of 0.85 and an altitude of 35,000 ft (10,668 m).

[0044] In use, the gas turbine engines described and / or claimed herein may operate under cruise conditions defined elsewhere herein. Such cruise conditions may be determined by the aircraft's cruise conditions (e.g., mid-cruise conditions), and at least one (e.g., two or four) gas turbine engines may be mounted to the aircraft to provide propulsive thrust.

[0045] According to one aspect, an aircraft is provided that includes a gas turbine engine as described and / or claimed herein. The aircraft according to this aspect is an aircraft to which the gas turbine engine is designed to be attached. Therefore, the cruise conditions according to this aspect correspond to the mid-cruise phase of the aircraft as defined elsewhere herein.

[0046] According to one aspect, a method is provided for operating a gas turbine engine as described and / or claimed herein. This operation can be performed under cruise conditions (e.g., in terms of thrust, atmospheric conditions, and Mach number) as defined elsewhere herein.

[0047] According to one aspect, a method is provided for operating an aircraft comprising a gas turbine engine as described and / or claimed herein. Operation according to this aspect may include (or may be) operation during the mid-cruise phase of the aircraft as defined elsewhere herein.

[0048] Those skilled in the art will recognize that, except in cases of mutual exclusion, any feature or parameter described in relation to any of the foregoing aspects can be applied to any other aspect. Furthermore, except in cases of mutual exclusion, any feature or parameter described herein can be applied to any aspect and / or combined with any other feature or parameter described herein. Attached Figure Description

[0049] Embodiments will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 This is a cross-sectional side view of a gas turbine engine; Figure 2 This is a close-up cross-sectional side view of the upstream section of a gas turbine engine; Figure 3 This is a partial cross-sectional view of a gearbox used in a gas turbine engine; Figure 4 This is a schematic diagram of a lean fuel spray nozzle that includes a main fuel circuit and an ignition fuel circuit; Figure 5a and 5b The layout of the switching device according to the first embodiment in the main closed position and the main open position are schematically shown respectively; Figure 6a and 6b The arrangement of the switching valve according to the first embodiment in the main closed position and the main open position is schematically shown respectively; Figure 7 It is a schematic diagram of a lean fuel spray nozzle that includes a main fuel circuit, a primary ignition fuel circuit, and a secondary ignition fuel circuit; Figure 8a and 8b The layout of the switching device according to the second embodiment in the main closed position and the main open position are schematically shown respectively; Figure 9a and 9b The arrangement of the switching valve according to the second embodiment in the main closed position and the main open position is schematically shown respectively; and Figure 10a and 10b The layout of the switching device according to the third embodiment in the main closed position and the main open position are schematically shown respectively. Detailed Implementation

[0050] Figure 1A gas turbine engine 10 with a main axis of rotation 9 is shown. The engine 10 includes an air inlet 12 and a propulsion fan 23 that generates two airflows (core airflow A and bypass airflow B). The gas turbine engine 10 includes a core 11 that receives core airflow A. The engine core 11 includes a low-pressure compressor 14, a high-pressure compressor 15, a combustion device 16, a high-pressure turbine 17, a low-pressure turbine 19, and a core exhaust nozzle 20, arranged in axial-flow series. A nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. Bypass airflow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low-pressure turbine 19 via a spindle 26 and a rotary gearbox 30.

[0051] In operation, the core airflow A is accelerated in the core duct, compressed by the low-pressure compressor 14, and directed to the high-pressure compressor 15, where further compression occurs. The compressed air discharged from the high-pressure compressor 15 is directed to the combustion device 16, where it is mixed with fuel and the mixture is burned. The resulting thermal combustion products then expand through the high-pressure turbine 17 and low-pressure turbine 19 before being discharged through nozzle 20, thereby driving the high-pressure turbine 17 and low-pressure turbine 19 to provide some propulsive thrust. The high-pressure turbine 17 drives the high-pressure compressor 15 by a suitable interconnecting shaft 27. The fan 23 provides the majority of the propulsive thrust. The rotary gearbox 30 is a reduction gearbox.

[0052] Figure 2 An exemplary arrangement for a geared fan gas turbine engine 10 is shown. The low-pressure turbine 19 (see...) Figure 1 A drive spindle 26 is connected to a sun gear or sun gear 28 of a planetary gear arrangement 30. A plurality of planet gears 32 are radially outward and meshed with the sun gear 28, and these planet gears are connected together by a planet carrier 34. The planet carrier 34 constrains the planet gears 32 to precess synchronously around the sun gear 28, while allowing each planet gear 32 to rotate about its own axis. The planet carrier 34 is connected to a fan 23 via a connecting rod 36 to drive it to rotate about the engine axis 9. A ring gear or annular gear 38 is radially outward and meshed with the planet gears 32, and is connected to a fixed support structure 24 via a connecting rod 40.

[0053] Note that, as used herein, the terms "low-pressure turbine" and "low-pressure compressor" can be understood to refer, respectively, to the lowest-pressure turbine stage and the lowest-pressure compressor stage (i.e., excluding fan 23), and / or the turbine stage and compressor stage connected by a spindle 26 (i.e., excluding the gearbox output shaft driving fan 23) at the lowest speed in the engine. In some literature, the terms "low-pressure turbine" and "low-pressure compressor" used herein may alternatively be referred to as "intermediate-pressure turbine" and "intermediate-pressure compressor." When using such alternative nomenclature, fan 23 may be referred to as the first or lowest-pressure compression stage.

[0054] Turnover gearbox 30 is illustrated by example. Figure 3 The details are shown in more detail below. Each of the sun gear 28, planet gear 32, and ring gear 38 includes teeth surrounding its periphery for meshing with other gears. However, for clarity, Figure 3 Only exemplary portions of the teeth are shown. Four planetary gears 32 are shown, but it will be apparent to those skilled in the art that more or fewer planetary gears 32 may be provided within the scope of the claimed invention. Practical applications of the planetary gearbox 30 generally include at least three planetary gears 32.

[0055] exist Figure 2 and 3 The planetary gearbox 30 shown by way of example is of the planetary type, wherein the planet carrier 34 is connected to the output shaft via a connecting rod 36, while the ring gear 38 is fixed. However, any other suitable type of planetary gearbox 30 may be used. By way of a further example, the planetary gearbox 30 may be of a star arrangement, wherein the planet carrier 34 remains fixed, while allowing the ring (or annular) gear 38 to rotate. In this arrangement, the fan 23 is driven by the ring gear 38. By way of a further alternative example, the gearbox 30 may be a differential gearbox, wherein both the ring gear 38 and the planet carrier 34 are allowed to rotate.

[0056] It will be recognized that, Figure 2 and 3 The arrangement shown is merely an example, and various alternatives are within the scope of this disclosure. By way of example only, any suitable arrangement can be used to position the gearbox 30 in the engine 10 and / or to connect the gearbox 30 to the engine 10. By further example, the connection between the gearbox 30 and other parts of the engine 10 (such as the input spindle 26, output shaft, and mounting structure 24) (such as...) Figure 2The connecting rods 36 and 40 in the examples can have any desired level of stiffness or flexibility. By further example, any suitable arrangement of bearings between the rotating and stationary parts of the engine (e.g., between the input and output shafts from the gearbox and a fixed structure such as the gearbox housing) can be used, and this disclosure is not limited to... Figure 2 Exemplary arrangements. For example, in the case where the gearbox 30 has a star arrangement (as described above), those skilled in the art will readily understand that the arrangement of the output and support links and the bearing positions is generally different. Figure 2 As illustrated by example.

[0057] Therefore, this disclosure extends to gas turbine engines having any arrangement of gearbox type (e.g., star or planetary), support structure, input and output shaft arrangement, and bearing location.

[0058] Optionally, the gearbox may drive additional and / or alternative components (e.g., a medium-pressure compressor and / or a booster compressor).

[0059] Other gas turbine engines to which this disclosure is applicable may have alternative configurations. For example, such engines may have an alternative number of compressors and / or turbines and / or an alternative number of interconnecting shafts. As a further example, Figure 1 The gas turbine engine shown has split nozzles 18 and 20, meaning that the flow through the bypass duct 22 has its own nozzle 18, which is separate from the core engine nozzle 20 and radially external. However, this is not limiting, and any aspect of this disclosure can also be applied to engines in which the flow through the bypass duct 22 and the flow through the core 11 are mixed or combined before (or upstream of) a single nozzle (which may be referred to as a mixing nozzle). One or both nozzles (whether mixing or splitting) may have a fixed or variable area. Although the described example relates to a turbofan engine, this disclosure can be applied, for example, to any type of gas turbine engine, such as an open rotor (where the fan stage is not surrounded by a nacelle) or a turboprop engine. In some arrangements, the gas turbine engine 10 may not include a gearbox 30.

[0060] The geometry of the gas turbine engine 10 and its components are defined by a conventional axis system, which includes an axial direction (aligned with the axis of rotation 9) and a radial direction (in... Figure 1 (in the direction from bottom to top) and the circumferential direction (perpendicular to) Figure 1 (Page in the view). The axial, radial, and circumferential directions are perpendicular to each other. As used herein, front and rear are relative to the gas turbine engine, i.e., the fan is in the front and the turbine is in the rear of the engine, and forward refers to the direction from the rear to the front of the gas turbine engine.

[0061] Figure 4 A lean fuel spray nozzle 60 according to a first embodiment is shown, which provides two different fuel supplies from a manifold (not shown for simplicity).

[0062] The fuel spray nozzle 60 includes a supply arm 62 and a lean fuel spray nozzle head 64. The supply arm 62 delivers fuel from a manifold to the nozzle head 64 via an ignition fuel circuit 67 and a main fuel circuit 69 having corresponding ignition fuel supply lines 66 and 68. The supply arm 62 includes a housing 65. The supply arm 62 may include an insulating air gap 63 formed by the housing 65.

[0063] The nozzle head 64 mixes fuel with air and delivers the mixture as an atomized spray into the combustion chamber of the combustion device 16. The nozzle head 64 may also include heat insulation.

[0064] The ignition fuel supply pipe 66 is used to deliver ignition fuel to the ignition fuel injector 70, which has an ignition fuel injector outlet (or atomizer) 71, within the nozzle head 64, and the main fuel supply pipe 68 is used to deliver main fuel to the main fuel injector 72, which has a main fuel injector outlet (or atomizer) 73, within the nozzle head 64. In the example shown, the ignition fuel supply pipe 66 is concentrically arranged within the main fuel supply pipe 68.

[0065] The fuel spray nozzle 60 is provided with a flange 88. The flange 88 is disposed at the upstream end of the supply arm 62 and can be integrally formed with the housing 65. In the assembled engine 10, for example, the fuel spray nozzle 60 can be secured to the burner housing 90 by fasteners (e.g., bolts).

[0066] The nozzle head 64 is substantially cylindrical and extends axially at an angle to the supply arm 63. Within the nozzle head 64, a first air vortex passage 76 extends substantially centrally. A first annular fuel passage 78 is formed around the first air vortex passage 76. The first annular fuel passage 78 is connected to and in fluid communication with the ignition fuel supply pipe 66 to supply ignition fuel to the ignition fuel injector 70.

[0067] The second air cyclone passage 80 is concentrically arranged radially outward from the first annular fuel passage 78, and the second annular fuel passage 82 is arranged radially outward from the second air cyclone passage 80. The second annular fuel passage 82 is connected to and in fluid communication with the main fuel supply pipe 68 to supply main fuel to the main fuel injector 72.

[0068] Each of the first air cyclone passage 76 and the second air cyclone passage 80 receives air from the low-pressure compressor 14 or the high-pressure compressor 15, or both. The air cyclone passages 76 and 80 include cyclone guide vanes (not shown) to impart air turbulence. Similarly, the first annular fuel passage 78 and the second annular fuel passage 82 also include cyclone guide vanes (not shown) to impart fuel turbulence. A cyclone head 84 may be disposed outside the second annular fuel passage 82 to supply more air to the main fuel injector 72.

[0069] In use, air from the first air cyclone passage 76 and the second air cyclone passage 80 is mixed with ignition fuel and main fuel from the first fuel passage 78 and the second fuel passage 82 to provide atomized fuel for injection into the combustion chamber.

[0070] Although the fuel spray nozzle 60 has been described as having two air swirler passages, it will be appreciated that various alternatives are within the scope of this disclosure. By way of example only, fuel spray nozzles with three, four, or five air swirler passages may be used. For example, in an embodiment with three air swirler passages, the third air swirler passage may be concentrically arranged radially outward of the second annular fuel passage 82; in an embodiment with four air swirler passages, the fourth air swirler passage may be concentrically arranged radially outward of the second air passage 80 to provide more air to the main fuel injector 72. Therefore, this disclosure extends to lean fuel spray nozzles 60 with different architectures and different numbers of air swirler passages.

[0071] The fuel spray nozzle 60 further includes a switching device or grading valve 74 for controlling the distribution of fuel between the ignition fuel injector 70 and the main fuel injector 72. The switching device 74 is arranged upstream of the supply arm 62 and the flange 88. In use, when the fuel spray nozzle 60 is connected to the burner housing 90 at the flange 88, the switching device 74 is located radially outward of the burner housing 90.

[0072] The switching device 74 receives fuel from the manifold, and typically, at least some of the fuel is always supplied to the ignition fuel injector 70. The relative proportion of fuel supplied to the ignition fuel injector 70 and the main fuel injector 72 varies depending on environmental conditions and engine operating modes. For example, the proportion of fuel supplied to the ignition fuel injector 70 increases during conditions such as engine ignition, takeoff, ascent, descent, idling, or specific environmental conditions. In some cases, 100 percent of the fuel may be supplied to the ignition fuel injector 70. At other times, a mixture of fuel from the main fuel injector 72 and the ignition fuel injector 70 is used, with contributions from variations in the ignition fuel injector 70. For example, during cruise, the ratio of fuel supplied by the ignition supply to fuel supplied by the main supply may be 20:80, or any other suitable ratio. The switching device 74 controls the fuel distribution between the ignition fuel injector 70 and the main fuel injector 72.

[0073] Referring now to the schematic illustrations of the layout of the switching device 74 according to the first embodiment in the main closed position and the main open position, respectively. Figure 4 , 5a The switching device 74 will be described in more detail in conjunction with 5b.

[0074] The switching device 74 includes a first inlet 176 for receiving ignition fuel from an ignition fuel supply via an ignition conduit 175, and a second inlet 178 for receiving main fuel from a main fuel supply via a main conduit 177. The switching device 74 further includes a first outlet 179 for delivering main fuel to a next fuel spray nozzle. The switching device 74 further includes a switching valve 180 in fluid communication with the second inlet 178. Figure 5a and 5b (The center is shown as a circle). The switching valve 180 is configured as follows: Figure 5a The first ignition-only (or main shut-off) position shown is as follows: Figure 5b The second ignition and main (or tiered, main open) positions are shown. The switching valve 180 includes an inlet adapted to receive main fuel from the main line 177, and two outlets adapted to direct main fuel to the main outlet and ignition outlet of the main fuel injector 72 or the ignition fuel injector 70, respectively. In the ignition-only position, the main outlet is fluidly disconnected from the switching valve inlet. With engine installation optimization, the ignition line 175 can be introduced into the switching device 74 and then exited again to the next fuel spray nozzle (similar to the main arrangement). Alternatively, a "T-joint" may be present in the ignition line 175 such that only a single supply line connects the ignition line 175 to the switching device 74.

[0075] The ignition-only position of the switching valve 180 corresponds to the gradual exit of the mainstream, while the ignition and main positions of the switching valve 180 correspond to the gradual entry of the mainstream.

[0076] In the ignition-only position, switching valve 180 directs the primary fuel supplied by autonomous fuel supply to the ignition fuel supply line 66 of the ignition fuel circuit 67 of the fuel spray nozzle 60 via connecting pipe 81. Connecting pipe 81 connects the ignition outlet of switching device 180 to the ignition fuel circuit 67. In the ignition-only position, all primary fuel entering switching device 74 through second inlet 178 is transferred to ignition fuel supply line 66 via connecting pipe 81. In the ignition-only position, main line 177 is in fluid communication with ignition fuel supply line 66. The primary fuel entering switching device 74 can be adjusted as needed, depending on engine operating mode, flight conditions, and / or environmental conditions, by means of any suitable devices and systems (such as valves, e.g., weight distribution valves). Allowing primary fuel to flow in ignition fuel circuit 67 prevents fuel from stagnating in main line 177 and thus absorbing heat. Compared to known switching devices that include an on / off valve instead of the recommended switching valve 180, this fuel spray nozzle allows fuel to continue flowing in the main pipe 177 and therefore does not absorb heat.

[0077] When in the ignition and master position, switching valve 180 directs main fuel from the main fuel supply to the main fuel supply pipe 68 of the main fuel circuit 69. When in the ignition and master position, the main fuel circuit 69 is disconnected from the ignition fuel circuit 67. In other words, when in the ignition and master position, main fuel is not supplied to the ignition fuel supply pipe 66.

[0078] The position of the switching valve does not affect the ignition fuel, because when the switching valve 180 is in the ignition-only position and when the switching valve 180 is in the ignition and main positions, the ignition fuel is only directed to the ignition fuel supply pipe 66 of the ignition fuel circuit 67.

[0079] Under normal operating conditions and when in ignition-only mode, the pressure in main pipe 177 will be higher than the pressure in ignition pipe 175, which ensures that the cooling flow passes through the main pipe before moving to the ignition.

[0080] However, in ignition-only mode, there is a possibility that the main line pressure may drop below the ignition line pressure. An example would be when the switching valve 180 is stuck in the ignition and main position when it should be in the ignition-only position. To prevent reverse flow—that is, fuel flowing from the ignition fuel supply line 66 through the switching valve 180 to the main line 177—a check valve (NRV) 83 may be provided between the ignition fuel circuit 67 and the main fuel circuit 69.

[0081] like Figure 5a and 5bAs shown, NRV83 can be placed between the ignition outlet of the switching valve and the ignition fuel supply pipe 66, for example, along the connecting pipe 81. In other words, NRV83 is arranged downstream of the switching valve 180. Alternatively, NRV83 can be placed upstream of the switching valve 180 in the fluid passage between the main pipe 177 and the switching valve 180.

[0082] Optionally, the current limiter can be combined with or connected in series with the NRV83 to affect the flow and pressure drop between the ignition section and the main section of the system. This feature is also useful when adjusting the system size for fault conditions.

[0083] NRVs can be conventional mechanical valves, such as those with a spring-on-seat arrangement, or fluid diode types, such as Tesla valves.

[0084] The switching valve 180 can be actuated electrically (e.g., by using a solenoid, motor, etc.), pneumatically, or hydraulically. For this purpose, when pneumatically or hydraulically actuated, such as Figure 4 In one embodiment, the switching device 74 further includes a fluid actuation circuit 160 having an additional third inlet 186 and an additional second outlet 188 for actuating fluids such as air, oil, or any other suitable fluid.

[0085] like Figure 5a and 5b As shown, the weight distribution valve (WDV) can optionally be incorporated into the switching valve 180, and can be located downstream or upstream of the switching valve 180. Specifically, the ignition weight distribution valve 192 is arranged in the ignition fuel circuit 67. The main weight distribution valve 193 is arranged upstream of the switching valve 180 in the main fuel circuit 69. The WDV is used to correct for the effect of fuel manifold pressure head differential on fuel distribution to the fuel spray nozzles 60. Figure 5a and 5b As shown by the dashed circle in the diagram, NRV83 (if present) can be positioned upstream or downstream of the main weight distribution valve 193, and upstream of the switching valve 180.

[0086] Now see Figure 6a and 6b A more detailed example of the switching valve 180 is provided.

[0087] The switching valve 180 includes a chamber containing a movable piston 150 biased by a spring 152. The piston 150 is pneumatically or hydraulically actuated by means of an actuating fluid flowing in a fluid actuation circuit 160 and supplied via an additional inlet 186 and discharged via an additional outlet 188.

[0088] Piston 150 in the corresponding Figure 6aThe first position of the ignition-only position of the switching valve 180 shown is corresponding to Figure 6b The switching valve 180 shown is movable between the ignition and the second position of the main position.

[0089] When pressurized actuating fluid is supplied to switching valve 180, the force it exerts on piston 150 exceeds the force of spring 152, causing piston 150 to move to a second position and remain in that position. When the pressure of the actuating fluid is released, spring 152 biases piston 150 back to the first position.

[0090] The switching valve 180 can be understood as a four-way valve, having an input 154 for receiving main fuel from the second inlet 178 of the switching device 74, and a first output 156, a second output 157, and a third output 158 ​​for delivering main fuel to the ignition fuel circuit 67, the main fuel circuit 69, and the next fuel spray nozzle, respectively. In other words, the third output 158 ​​of the switching valve 180 is in fluid communication with the first outlet 179 of the switching device 74 of the next fuel spray nozzle 60.

[0091] When in the first position, piston 150 closes the second output 157 and opens the first output 156 and the third output 158, allowing input 154 to flow fluidly with the ignition fuel circuit 67 and the next fuel spray nozzle. In other words, when piston 150 is in the first position, the main fuel entering switching valve 180 is directed toward the ignition fuel supply pipe 66 and the main pipe 177.

[0092] When in the second position, piston 150 closes the first output 156 and opens the second output 157 (with the third output 158 ​​remaining open), allowing input 154 to flow fluidly with the main fuel circuit 69 and the next fuel spray nozzle. In other words, when piston 150 is in the second position, the main fuel entering switching valve 180 is directed toward the main fuel supply line 68 and the main line 177.

[0093] It should be noted that the third output 158 ​​is open in both the first and second positions of the piston 150 to allow the main fuel to always flow in the main pipe 177.

[0094] In an alternative embodiment (not shown), the switching valve may be configured such that when pressurized actuating fluid is supplied, piston 150 moves to a first position in which second outlet 157 is closed and inlet 154 is in fluid communication with first output 156 to deliver main fuel to ignition fuel circuit 67 and with third outlet 158, while when the pressure of the actuating fluid is released, piston 150 moves to a second position in which first output 156 is closed and inlet 154 is in fluid communication with second output 157 to deliver main fuel to main fuel circuit 69 and with third outlet 158.

[0095] like Figure 6a and 6b As shown, the weight distribution valve (WDV) is located downstream of the switching valve 180. More specifically, the ignition weight distribution valve 190 is located downstream of the switching valve 180 in the ignition fuel circuit 67. The main weight distribution valve 191 is located downstream of the switching valve 180 in the main fuel circuit 69.

[0096] In alternative embodiments, such as Figure 5a and 5b As shown, the ignition weight distribution valve and the main weight distribution valve can be arranged upstream of the switching valve 180.

[0097] Figure 7 The lean fuel spray nozzle 260 according to the second embodiment is schematically shown.

[0098] Fuel spray nozzle 260 is similar to [see reference]. Figure 4 Fuel spray nozzle 60 is described, and the same reference numerals are used to indicate similar features. The main difference between fuel spray nozzle 60 and fuel spray nozzle 260 will be described here.

[0099] The fuel spray nozzle 260 includes a supply arm 62 and a lean fuel spray nozzle head 64. The supply arm 62 delivers fuel from a manifold to the nozzle head 64 via an ignition fuel circuit 265 and a main fuel circuit 69 including a main fuel supply line 68. The supply arm 62 includes a housing 65. The supply arm 62 may include an insulating air gap 63 formed by the housing 65. The nozzle head 64 may also include insulation. The ignition fuel circuit 265 includes a primary ignition fuel circuit 266 including a primary ignition fuel supply line 267 and a secondary ignition fuel circuit 268 including a secondary ignition fuel supply line 269.

[0100] The primary ignition fuel supply pipe 267 and the secondary ignition fuel supply pipe 269 are used to deliver ignition fuel and main fuel to the ignition fuel injector outlet (or atomizer) 71 of the ignition fuel injector 70 in the nozzle head 64, respectively. The main fuel supply pipe 68 is used to deliver main fuel to the main fuel injector outlet (or atomizer) 73 of the main fuel injector 72 in the nozzle head 64.

[0101] The fuel spray nozzle 260 is provided with a flange 88. The flange 88 is arranged at the upstream end of the supply arm 62 and can be integrally implemented with the housing 65. In the assembled engine 10, the fuel spray nozzle 260 can be secured to the burner housing 90, for example, by fasteners (e.g., bolts).

[0102] Within the nozzle head 64, a first air vortex passage 76 extends substantially centrally. A first annular fuel passage 78 is formed around the first air vortex passage 76. The first annular fuel passage 78 is connected to a primary ignition fuel supply pipe 267 and a secondary ignition fuel supply pipe 269 to supply ignition fuel and main fuel to the ignition fuel injector 70, respectively.

[0103] The second air cyclone passage 80 is concentrically arranged radially outward from the first annular fuel passage 78, and the second annular fuel passage 82 is arranged radially outward from the second air cyclone passage 80. The second annular fuel passage 82 is connected to the main fuel supply pipe 68 to supply main fuel to the main fuel injector 72.

[0104] Each of the first air cyclone passage 76 and the second air cyclone passage 80 receives air from the low-pressure compressor 14 or the high-pressure compressor 15, or both. The air cyclone passages 76 and 80 may include cyclone guide vanes (not shown) to impart air turbulence. Similarly, the first annular fuel passage 78 and the second annular fuel passage 82 may also include cyclone guide vanes (not shown) to impart fuel turbulence. A cyclone head 84 may be disposed on the outside of the second annular fuel passage 82 to supply more air to the main fuel injector 72.

[0105] In use, air from the first air cyclone passage 76 and the second air cyclone passage 80 is mixed with ignition fuel and main fuel from the first fuel passage 78 and the second fuel passage 82 to provide atomized fuel for injection into the combustion chamber.

[0106] Similar to fuel spray nozzle 60, although fuel spray nozzle 260 has been described as having two air swirler passages, it will be appreciated that various alternatives are within the scope of this disclosure. By way of example only, fuel spray nozzles having three, four, or five air swirler passages can be used. For example, it is foreseeable, as referenced... Figure 4 The embodiments of the fuel spray nozzle 60 with three and four air swirler passages are shown. Therefore, this disclosure extends to lean fuel spray nozzles 260 with different architectures and different numbers of air swirler passages.

[0107] The fuel spray nozzle 260 further includes a switching device or staged valve 174 for controlling the distribution of fuel between the ignition fuel injector 70 and the main fuel injector 72, similar to the switching device 74 shown with reference to the first embodiment. The same reference numerals are used to indicate similar features. The differences between the switching device 74 of the first embodiment and the switching device 174 of the second embodiment will be described herein primarily.

[0108] The switching device 174 is arranged upstream of the supply arm 62 and the flange 88. In use, when the fuel spray nozzle 260 is connected to the burner housing 90 at the flange 88, the switching device 174 is located radially outward of the burner housing 90.

[0109] Referring now to the schematic illustrations of the layout of the switching device 174 according to the second embodiment in the main closed position and the main open position, respectively. Figure 8a and 8b To describe the switching device 174.

[0110] The switching device 174 includes a first inlet 176 for receiving ignition fuel from the ignition fuel supply via ignition conduit 175, and a second inlet 178 for receiving main fuel from the main fuel supply via main conduit 177. The first inlet 176 of the switching device 174 receives the ignition fuel from the ignition fuel supply and supplies this ignition fuel to the primary ignition fuel circuit 266.

[0111] The switching device 174 further includes a first outlet 179 for delivering main fuel to the next fuel spray nozzle. The switching device 174 further includes a switching valve 180 (in... Figure 8a and 8b (shown as a circle in the middle), its structure is as follows: Figure 8a The first ignition-only (or main shut-off) position shown is as follows: Figure 8b The switch between the second ignition and main (or tiered, main start) positions is shown.

[0112] In the ignition-only position, switching valve 180 directs the primary fuel supplied by autonomous fuel to the secondary ignition fuel supply line 269 of the secondary ignition fuel circuit 268 of the fuel spray nozzle 260. In the ignition-only position, all primary fuel entering switching valve 180 through second inlet 178 is transferred to the secondary ignition fuel supply line 269. In the ignition-only position, main line 177 is in fluid communication with the secondary ignition fuel supply line 269. In the ignition-only position, second inlet 178 is in fluid communication with both the secondary ignition fuel circuit 268 and the secondary ignition fuel supply line 269. The primary fuel entering switching valve 180 can be adjusted as needed, depending on the engine operating mode, flight conditions, and / or environmental conditions, by means of any suitable metering device and system, such as valves, e.g., weight distribution valves. Allowing primary fuel to flow in the secondary ignition fuel circuit 268 prevents fuel stagnation in main line 177 and thus heat absorption. Compared to known switching devices that include an on / off valve instead of the recommended switching valve 180, this fuel spray nozzle allows fuel to continue flowing in the main pipe 177 and therefore does not absorb heat.

[0113] When in the ignition and master position, switching valve 180 directs main fuel from the main fuel supply to the main fuel supply pipe 68 of the main fuel circuit 69. When in the ignition and master position, the main fuel circuit 69 and main pipe 177 are disconnected from the secondary ignition fuel circuit 268. In other words, when in the ignition and master position, main fuel is not supplied to the secondary ignition fuel supply pipe 269.

[0114] In the fuel spray nozzle 260, the switching valve 180 is adapted to fluidly communicate the second inlet 178 with the secondary ignition fluid supply line 269 (when the switching valve 180 is in the ignition-only position) or the main fuel supply line 68 (when the switching valve 180 is in the ignition and main positions). In other words, the second inlet 178 of the switching device 174 receives main fuel from the main fuel supply, which, depending on the position of the switching valve 180, is then supplied to the secondary ignition fuel circuit 268 or the main fuel circuit 69.

[0115] When the switching valve 180 is in the ignition-only position or both the ignition and main positions, the primary ignition fuel circuit 266 is always in fluid communication with the ignition conduit 175.

[0116] When in the ignition-only position, the ignition fuel injector 70 receives ignition fuel from the ignition pipe 175 through the first inlet 176 of the switching device 174, and receives main fuel from the main pipe 177 through the second inlet 178 and the switching valve 180.

[0117] The switching valve 180 can be actuated electrically (e.g., by using a solenoid, motor, etc.), pneumatically, or hydraulically. For this purpose, when pneumatically or hydraulically actuated, such as Figure 4 In one embodiment, the switching device 174 further includes an additional third inlet 186 and an additional second outlet 188 for actuating fluids such as air, oil, or any other suitable fluid.

[0118] The first weight distribution valve 192 is arranged to regulate the ignition fuel flow in the primary ignition fuel supply pipe 267. The second weight distribution valve 193 is arranged to regulate the main fuel flow upstream of the switching valve 180. Alternatively, such as Figure 9a and 9b As shown, the second weight distribution valve 193 can be replaced by two separate weight distribution valves 194 and 195 arranged downstream of the switching valve 180. Weight distribution valve 194 is arranged in the secondary ignition fuel circuit 268 to adjust the main fuel flow in the secondary ignition fuel supply pipe 269; weight distribution valve 195 is arranged in the main fuel circuit 69 to adjust the main fuel flow in the main fuel supply pipe 68.

[0119] Figure 9a and 9b A more detailed schematic illustration shows what is suitable for use Figure 7Example of switching valve 180 in switching device 174.

[0120] The switching valve 180 of the switching device 174 is basically the same as the switching valve 180 of the switching device 74.

[0121] The switching valve 180 includes a chamber containing a movable piston 150 biased by a spring 152. The piston 150 is pneumatically or hydraulically actuated by means of an actuating fluid flowing in a fluid actuation circuit 160 and supplied via an additional inlet 186 and discharged via an additional outlet 188.

[0122] Piston 150 can be in the corresponding Figure 9a The first position of the ignition-only position of the switching valve 180 shown is corresponding to Figure 9b The switching valve 180 shown moves between the ignition and main positions of the second position.

[0123] When pressurized actuating fluid is supplied to switching valve 180, the force it exerts on piston 150 exceeds the force of spring 152, causing piston 150 to move to a second position and remain in that position. When the pressure of the actuating fluid is released, spring 152 biases piston 150 back to the first position.

[0124] The switching valve 180 can be understood as a four-way valve, having an input 154 for receiving main fuel from the second inlet 178 of the switching device 74, and a first output 156, a second output 157, and a third output 158 ​​for delivering main fuel to the secondary ignition fuel circuit 268, the main fuel circuit 69, and the next fuel spray nozzle, respectively. In other words, the third output 158 ​​of the switching valve 180 is in fluid communication with the first outlet 179 of the switching device 174 to deliver main fuel to the next fuel spray nozzle 260.

[0125] When in the first position, piston 150 closes the second output 157 and opens the first output 156 and the third output 158, allowing input 154 to flow in fluid communication with the secondary ignition fuel circuit 268 and the next fuel spray nozzle 260. In other words, when piston 150 is in the first position, the main fuel entering the switching valve 180 is directed toward the secondary ignition fuel supply line 269 and the main line 177.

[0126] When in the second position, piston 150 closes the first output 156 and opens the second output 157 (the third outlet 158 ​​remains open), allowing input 154 to fluidly communicate with the main fuel circuit 69 and the next fuel spray nozzle 260. In other words, when piston 150 is in the second position, the main fuel entering switching valve 180 is directed toward the main fuel supply line 68 and the main line 177.

[0127] It should be noted that, as in the first embodiment, the third output 158 ​​is open in both the first and second positions of the piston 150 to allow the main fuel to always flow in the main conduit 177.

[0128] In an alternative embodiment (not shown), the switching valve may be configured such that when pressurized actuating fluid is supplied, piston 150 moves to a first position in which second outlet 157 is closed and inlet 154 is in fluid communication with first output 156 to deliver main fuel to secondary ignition fuel supply line 269 and with third outlet 158, while when the pressure of the actuating fluid is released, piston 150 moves to a second position in which first output 156 is closed and inlet 154 is in fluid communication with second output 157 to deliver main fuel to main fuel circuit 69 and with third outlet 158.

[0129] Figure 10a and 10b The layout of another embodiment of the switching device or staged valve 274 is shown, adapted for use in a fuel spray nozzle 260, instead of referring to Figure 7-9b The switching device 174 shown.

[0130] The switching device 274 controls the distribution of fuel between the ignition fuel injector 70 and the main fuel injector 72.

[0131] The switching device 274 is arranged upstream of the supply arm 62 and the flange 88. In use, when the fuel spray nozzle 260 is connected to the burner housing 90 at the flange 88, the switching device 274 is located radially outward of the burner housing 90.

[0132] The layout of the switching device 274 is schematically shown in Figure 10a The main closing position in the middle Figure 10b In the main opening position.

[0133] The switching device 274 is in fluid communication with the ignition pipe 175 via the first inlet 176 to supply ignition fuel to the primary ignition fuel circuit 266, and is in fluid communication with the main pipe 177 via the second inlet 178 to supply main fuel to the main fuel circuit 69 and to the secondary ignition fuel circuit 268.

[0134] The ignition weight distribution valve 190 is arranged upstream of the ignition fuel injector 70 along the primary ignition fuel circuit 266.

[0135] The switching device 274 further includes a switching valve 280 (in Figure 10a and 10b (shown as a circle in the middle), its structure is as follows: Figure 10a The first ignition-only (or main shut-off) position shown is as follows: Figure 10bThe switch between the second ignition and main (or tiered, main start) positions is shown.

[0136] The main weight distribution valve 191 is located upstream of the main fuel injector 72, for example, upstream of the switching valve 280. In an embodiment not shown, the main weight distribution valve 191 may be located downstream of the switching valve 280 along the main fuel circuit 69.

[0137] The main difference between switching device 274 and switching device 174 is that the main conduit 177 is permanently connected to the secondary ignition fuel circuit 268, ensuring that the main fuel always flows within the secondary ignition fuel circuit 268, regardless of the position of switching device 280. For this purpose, the secondary ignition fuel circuit 268 is connected to the main conduit 177 upstream of switching device 274 at connector 200. Connector 200 may be located downstream of the main weight distribution valve 191. Connector 200 diverts the main fuel flow between the secondary ignition fuel circuit 268 and switching valve 280. Because switching valve 280 is located in the main fuel circuit 69 downstream of connector 200, the main fuel flow in the secondary ignition fuel circuit 268 is substantially unaffected by whether switching valve 280 is in the ignition-only position or the ignition and main position.

[0138] Channel restrictor 201 may be arranged in the secondary ignition fuel circuit 268 downstream of connector 200 to ensure that only known and relatively low flow can enter the secondary ignition fuel circuit 268. As the main flow gradually enters and the flow through the main fuel circuit 69 increases, channel restrictor 201 limits the amount of flow that can be “lost” to the secondary ignition fuel circuit 268. If necessary, the flow in the primary ignition fuel circuit 266 can be altered to offset the increased flow in the secondary ignition fuel circuit 268, for example, by means of ignition weight distribution valve 190 or other dedicated valves. For example, when the main flow gradually enters, the fuel flow in the secondary ignition fuel circuit 268 is less than 1:10 of the fuel flow in the main fuel circuit 69.

[0139] When in the ignition-only position, switching valve 280 prevents main fuel from entering the main fuel supply line 68. When in the ignition-only position, main line 177 is not in fluid communication with the main fuel circuit 69.

[0140] When in the ignition and main position, switching valve 280 connects main pipe 177 to main fuel supply pipe 68.

[0141] The switching valve 280 can be actuated electrically (e.g., by using a solenoid, motor, etc.), pneumatically, or hydraulically (e.g., by means of an actuating fluid, such as air, oil, or any other suitable fluid).

[0142] When the switching valve 280 is in the ignition-only position and when the switching valve 280 is in both the ignition and main positions, the secondary ignition fuel circuit 268 is in fluid communication with the main pipeline 177.

[0143] It will be understood that the present invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the conception set forth herein. Except where mutually exclusive, any feature may be used separately or in combination with any other feature, and this disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

Claims

1. A lean fuel spray nozzle (60, 260), comprising: - Lean fuel spray nozzle head (64), which includes an ignition fuel injector (70) having an ignition fuel injector outlet (71) and a main fuel injector (72) having a main fuel injector outlet (73). - A supply arm (62) adapted to supply ignition fuel from ignition conduit (175) through ignition fuel circuits (67, 265) to the ignition fuel injector (70), and to supply main fuel from main conduit (177) through main fuel circuit (69) to the main fuel injector (72); and - A switching device (74, 174, 274) arranged upstream of the supply arm, the switching device including a switching valve (180) adapted to switch between a main open position and a main closed position, in which the main fuel injector outlet (73) is in fluid communication with the main pipeline (177) through the main fuel circuit (69), such that main fuel is adapted to flow through the main fuel injector (72) and be sprayed through the main fuel injector outlet (73), in which the main fuel injector outlet (73) is not in fluid communication with the main pipeline (177) through the main fuel circuit (69) and the flow of main fuel is blocked through the main fuel injector (72). The switching valve (180) in the main closed position is adapted to allow the main pipe (177) to be in fluid communication with the ignition fuel injector (70) through the ignition fuel circuit (67, 265), thereby allowing the main fuel to flow in the ignition fuel circuit (67, 265). The ignition fuel circuit (265) includes a primary ignition fuel circuit (266) including a primary ignition fuel supply pipe (267) and a secondary ignition fuel circuit (268) including a secondary ignition fuel supply pipe (269), wherein the primary ignition fuel supply pipe (267) and the secondary ignition fuel supply pipe (269) are configured to supply ignition fuel and main fuel to the ignition fuel injector outlet (71), respectively.

2. The lean fuel spray nozzle according to claim 1, wherein, When the switching valve (180) is in the main closed position, the main fuel flowing in the main fuel circuit (69) is sprayed through the ignition fuel injector outlet (71).

3. The lean fuel spray nozzle according to claim 1, further comprising a flange (88) adapted to secure the lean fuel spray nozzle to the burner housing (90), wherein the switching device (74, 174, 274) is arranged upstream of the flange (88).

4. The lean fuel spray nozzle according to claim 1, wherein, When the switching valve (180) is in the main closed position, the secondary ignition fuel circuit (268) is in fluid communication with the main pipeline (177).

5. The lean fuel spray nozzle according to claim 4, wherein, When the switching valve (180) is in the main closed position, the main fuel from the main pipe (177) and the ignition fuel from the ignition pipe (175) are sprayed through the ignition fuel injector outlet (71).

6. The lean fuel spray nozzle according to claim 1, wherein, When the switching valve (180) is in the main open position, the secondary ignition fuel circuit (268) is not in fluid communication with the main pipeline (177).

7. The lean fuel spray nozzle according to claim 6, wherein, When the switching valve (180) is in the main open position, the main fluid flows only in the main fuel circuit (69).

8. The lean fuel spray nozzle according to claim 1, wherein, The secondary ignition fuel circuit (268) is connected to the main pipeline (177) upstream of the switching valve (180) at a joint (200).

9. The lean fuel spray nozzle according to claim 8, wherein, When the switching valve (180) is in the main open position, the secondary ignition fuel circuit (268) is in fluid communication with the main pipeline (177).

10. The lean fuel spray nozzle according to claim 9, further comprising: A channel restrictor (201) is arranged downstream of the connector (200) in the secondary ignition fuel circuit (268) to limit the amount of primary fuel flowing in the secondary ignition fuel circuit (268) when the switching valve (180) is in the main open position.

11. The lean fuel spray nozzle according to claim 1, further comprising a check valve (83) disposed between the ignition fuel circuit (67) and the main fuel circuit (69).

12. The lean fuel spray nozzle according to claim 11, wherein, The switching valve (180) includes an inlet adapted to receive main fuel from the main pipe (177), a main outlet in fluid communication with the main fuel injector (72), and an ignition outlet in fluid communication with the ignition fuel injector (70). The lean fuel spray nozzle further includes a connecting pipe (81) adapted to connect the ignition outlet of the switching valve (180) to the ignition fuel circuit (67). The check valve (83) is arranged along the connecting pipe (81).

13. The lean fuel spray nozzle according to claim 11, wherein, The check valve (83) is located upstream of the switching valve (180).

14. A gas turbine engine (10), comprising: - Fan (23), which includes multiple fan blades; - Engine core (11), which includes compressor (15), burner (16), turbine (19) and spindle (26) connecting the turbine to the compressor. The burner (16) includes a combustion chamber and a plurality of lean fuel spray nozzles (60, 260) according to any one of the preceding claims.

15. The gas turbine engine of claim 14, further comprising a gearbox (30) that receives input from the spindle (26) and outputs drive to the fan (23) to drive the fan (23) at a lower speed than the spindle (26).

Images