Combustor with improved primary combustor zone

Abstract

A lean-burn combustor (16) comprising a plurality of lean-burn fuel injectors (50), each lean-burn fuel injector comprising a fuel supply arm (52) and a lean-burn fuel injector head (54) with a lean-burn fuel injector head tip (72), the lean-burn fuel injector head comprising a pilot fuel injector and a main fuel injector arranged coaxially with the pilot fuel injector and radially outwardly, and a combustor chamber (60) extending in an axial direction (62) and comprising a radially inner annular wall (64), a radially outer annular wall (66) and a metering plate (68) defining the size and shape of the combustor chamber, wherein the combustor chamber comprises a primary combustion zone (80) and a secondary combustion zone (82).

Description

Technical Field

[0001] This disclosure relates to combustion devices, and more particularly to lean-burn combustors for gas turbine engines used in aircraft, industrial and marine applications. Background Technology

[0002] Gas turbine engines for aircraft applications typically include a fan arranged in an axial flow configuration, 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 produce a spray of atomized liquid fuel entering a combustion chamber. The mixture of air and atomized liquid fuel is then burned in the combustion chamber, and the resulting thermal combustion products expand through and thereby drive one or more turbines.

[0003] 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.

[0004] To address NOx emissions, "lean burn" combustion technology has been proposed. In lean burn combustion, the air-to-fuel ratio (AFR) is higher than the stoichiometric ratio, which allows the combustion temperature to be kept within known limits to reduce NOx production.

[0005] On the other hand, maintaining a relatively low combustion temperature may result in incomplete or weak combustion, which in turn may lead to the production of other pollutants such as carbon monoxide (CO) and unburned hydrocarbons (UHC), and / or unstable flames and rumbling, which may in turn cause fatigue failure of components in the engine and / or passenger discomfort, depending on the frequency of the rumbling.

[0006] Gas turbine engines for industrial and marine applications face similar challenges to those for aircraft applications.

[0007] Therefore, there is a need for lean-burn combustion systems for aircraft, industrial, and marine engines, which allow for reductions in NOx, CO, and UHC emissions and improve engine operability. Summary of the Invention

[0008] According to a first aspect, a lean-burn burner is provided, comprising: a plurality of lean-burn fuel injectors, each lean-burn fuel injector including a fuel supply arm and a lean-burn fuel injector head with a lean-burn fuel injector head tip, wherein the lean-burn fuel injector head tip has a lean-burn fuel injector head tip diameter (d), the lean-burn fuel injector head including a pilot fuel injector and a main fuel injector, the main fuel injector being arranged coaxially with the pilot fuel injector and radially outward; and a burner chamber extending in an axial direction, including a radially inner annular wall, a radially outer annular wall, and a metering plate provided upstream of the radially inner annular wall and the radially outer annular wall, the metering plate having a plurality of orifices adapted to receive the lean-burn fuel injector head tips. The radially inner annular wall, the radially outer annular wall, and the metering plate define the size and shape of the burner chamber, wherein the burner chamber has a burner chamber length (L) and includes a primary combustion zone having a primary combustion zone length (Z) and a primary combustion zone depth (D) and a secondary combustion zone having a secondary combustion zone length (LZ) disposed downstream of the primary combustion zone. According to the first aspect, the ratio of the burner chamber length to the primary combustion zone depth, L / D, is less than 2.0.

[0009] In this disclosure, upstream and downstream are relative to the fuel and air flow through the burner, and front and rear are relative to the lean burner, i.e., the lean fuel injector is in the front and the burner chamber is in the rear.

[0010] The inventors have discovered a unique combination of dimensionless parameters for the combustor chamber, which allows for the development of combustor aerodynamics to optimize combustion efficiency and minimize NOx and smoke. The lean-burn combustor according to this disclosure allows the formation of a so-called S-shaped recirculation zone in the primary combustion zone of the combustor chamber, which allows the pilot fuel injector to support the combustion of the main fuel injector. Specifically, the inventors have discovered that the combustor chamber according to this disclosure allows the pilot fuel and air combustion mixture from the pilot fuel injector to form an S-shaped flow recirculation. In detail, the pilot fuel and air combustion mixture from the pilot fuel injector can reach a stagnation point in the primary combustion zone, where the pilot fuel and air mixture has a local velocity of zero, travels backward toward the lean-burn fuel injector, and turns (due to the low static pressure in the main fuel injector) toward the radially inner and radially outer annular walls of the combustor chamber to join and support the combustion of the main fuel and air combustion mixture from the main fuel injector. In other words, the pilot fuel and air combustion mixture from the pilot fuel injector can flow along an S-shaped trajectory.

[0011] Those skilled in the art will recognize that when designing burner chambers for lean-burn burners, aerodynamic studies must be conducted on any burner chamber size to optimize the aerodynamics and combustion of the fuel-air mixture. The inventors have surprisingly discovered that the lean-burn burner according to this disclosure can be scaled up and down without affecting combustion efficiency. In other words, since the L / D ratio is dimensionless, an S-shaped recirculation zone can be effectively and efficiently formed within the primary combustion zone for a wide range of burner chamber sizes according to this disclosure.

[0012] For example, the lean-burn burner according to this disclosure can be sized for adaptation to engines installed on small, medium and large aircraft.

[0013] In this embodiment, the ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be less than 1.9, for example, less than 1.8, or less than 1.75, or less than 1.70, or less than 1.65, or less than 1.60. The ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be greater than 1.0, for example, greater than 1.05, or greater than 1.10, or greater than 1.15, or greater than 1.20, or greater than 1.25.

[0014] The lean-burn fuel injector head can extend generally along the longitudinal direction, forming an angle α with the axial direction. 斜 oblique angle α 斜 Includes the range between 0° and 10°.

[0015] The burner chamber can extend axially between a metering plate (upstream) and an annular outlet (downstream), through which the combustion gases exit the burner chamber. The annular outlet can be defined by a radially inner annular wall and a radially outer annular wall of the burner chamber, and between the two. In this disclosure, the burner chamber length (L) can be defined as the axial distance between the metering plate and the annular outlet.

[0016] The radial outer annular wall can extend substantially axially between the metering plate and the annular outlet. In an embodiment, the radial outer annular wall can form an outer angle α with the axial direction. 外 exterior angle α 外 This includes the range between 0° and 15°, for example, between 0° and 12°, or between 0° and 10°, or between 3° and 15°, or between 5° and 15°.

[0017] The radially outer annular wall may include a first portion and a second portion. The first portion of the radially outer annular wall may be disposed upstream of the second portion of the radially outer annular wall. The first portion and the second portion of the radially outer annular wall may be aligned with each other.

[0018] The radially inner annular wall may include a first portion and a second portion. The first portion of the radially inner annular wall may be disposed upstream of the second portion of the radially inner annular wall. The first portion of the radially inner annular wall may be connected to a metering plate. The second portion of the radially inner annular wall and the second portion of the radially outer annular wall may define an annular outlet of the combustion chamber. The first portion of the radially inner annular wall may be arranged at an angle to the second portion of the radially inner annular wall. The first portion of the radially inner annular wall may be parallel to the radially outer annular wall. The first portion of the radially inner annular wall may be parallel to the axial direction.

[0019] The first part of the radial inner annular wall, the first part of the radial outer annular wall, and the metering plate define the primary combustion zone.

[0020] In this disclosure, the length (Z) of the primary combustion zone can be defined as the axial length of the primary combustion zone. A first portion of the radially inner annular wall can define the length (Z) of the primary combustion zone. A first portion of the radially outer annular wall can also define the length (Z) of the primary combustion zone. The first portions of the radially inner and radially outer annular walls can have the same length in the axial direction.

[0021] In this disclosure, the primary combustion zone depth (D) can be defined as the radial distance between the first portion of the radially inner annular wall and the first portion of the radially outer annular wall. As used herein, the term "radial" can refer to a direction perpendicular to the first portion of the radially inner annular wall and the first portion of the radially outer annular wall.

[0022] The second portion of the radially inner annular wall may converge toward the second portion of the radially outer annular wall in the downstream direction. In an embodiment, the second portion of the radially inner annular wall may form an interior angle α with the first portion of the radially inner annular wall. 内 , interior angle α 内 This includes between 15° and 50°, for example, between 15° and 45°, or between 15° and 40°, or between 20° and 50°, or between 25° and 50°, or between 25° and 45°, or between 25° and 40°.

[0023] The second portion of the radially inner annular wall and the second portion of the radially outer annular wall define the secondary combustion zone. The secondary combustion zone extends between the primary combustion zone and the annular outlet of the combustion chamber. The secondary combustion zone is located downstream of the primary combustion zone. The secondary combustion zone extends to a length (LZ) equal to the secondary combustion zone length (LZ). The second portion of the radially outer annular wall extends to a length equal to (LZ) / cos(α). 内 The length of ).

[0024] The respective inner surfaces of the radially inner annular wall, the radially outer annular wall, and the metering plate can define the size and shape of the combustion chamber (where combustion occurs). In some literature, the radially inner annular wall, the radially outer annular wall, and the metering plate are referred to as combustion liners. In embodiments, the radially inner annular wall, the radially outer annular wall, and the metering plate may each include a corresponding tile. The tile can define the respective inner surfaces of the radially inner annular wall, the radially outer annular wall, and the metering plate, and thus define the size and shape of the combustor chamber (where combustion occurs). The tile, or in other words, the inner surfaces of the radially inner annular wall, the radially outer annular wall, and the metering plate can face the combustion process within the combustion chamber and can be in contact with the fuel and air mixture and / or combustion gases.

[0025] The inventors of this disclosure have also discovered that other dimensionless parameters can be advantageous when designing a burner chamber for a lean-burn burner with improved combustion efficiency.

[0026] In an embodiment, the ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be less than 5, for example, less than 4.5, or less than 4, or less than 3.5, or less than 3, or less than 2.8, or less than 2.6, or less than 2.5, or less than 2.45, or less than 2.4. The ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be greater than 1.5, for example, greater than 1.7, or greater than 1.8, or greater than 1.85, or greater than 1.9, or greater than 2.0.

[0027] In an embodiment, the ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be less than 2.4, for example, less than 2.3, or less than 2.2, or less than 2.1, or less than 2.0. The ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be greater than 1.2. In an embodiment, the ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be greater than 1.3, for example, greater than 1.4, or greater than 1.5.

[0028] In an embodiment, the ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be less than 1.40, for example, less than 1.35, or less than 1.30, or less than 1.25, or less than 1.20. The ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be greater than 0.70, for example, greater than 0.75, or greater than 0.80, or greater than 0.85, or greater than 0.90.

[0029] Those skilled in the art will recognize that since the ratio of the burner chamber length L to the lean fuel injector tip diameter d, the ratio of the primary combustion zone depth D to the lean fuel injector tip diameter d, and the ratio of the primary combustion zone length Z to the lean fuel injector tip diameter d are all dimensionless, they can all be applied to a wide range of lean burners and associated burner chambers, and can help to form an S-shaped recirculation zone within the primary combustion zone.

[0030] According to a second aspect, a lean-burn burner is provided, comprising: a plurality of lean-burn fuel injectors, each lean-burn fuel injector including a fuel supply arm and a lean-burn fuel injector head with a lean-burn fuel injector head tip, wherein the lean-burn fuel injector head tip has a lean-burn fuel injector head tip diameter (d), the lean-burn fuel injector head including a pilot fuel injector and a main fuel injector, the main fuel injector being arranged coaxially with the pilot fuel injector and radially outward; and a burner chamber extending in an axial direction, including a radially inner annular wall, a radially outer annular wall, and a metering plate provided upstream of the radially inner annular wall and the radially outer annular wall, the metering plate having a plurality of orifices adapted to receive the lean-burn fuel injector head tips. The radially inner annular wall, the radially outer annular wall, and the metering plate define the size and shape of the burner chamber, wherein the burner chamber has a burner chamber length (L) and includes a primary combustion zone having a primary combustion zone length (Z) and a primary combustion zone depth (D) and a secondary combustion zone having a secondary combustion zone length (LZ) disposed downstream of the primary combustion zone. According to the second aspect, the ratio D / d of the primary combustion zone depth to the tip diameter of the lean fuel injector head is less than 2.4.

[0031] In an embodiment, the ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be less than 2.3, for example, less than 2.2, less than 2.1, or less than 2.0. The ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be greater than 1.2, for example, greater than 1.3, greater than 1.4, or greater than 1.5.

[0032] In an embodiment, the ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be less than 5, for example, less than 4.5, or less than 4, or less than 3.5, or less than 3, or less than 2.8, or less than 2.6, or less than 2.5, or less than 2.45, or less than 2.4. The ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be greater than 1.8, for example, greater than 1.85, or greater than 1.9, or greater than 2.0.

[0033] In an embodiment, the ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be less than 1.40, for example, less than 1.35, or less than 1.30, or less than 1.25, or less than 1.20. The ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be greater than 0.70, for example, greater than 0.75, or greater than 0.80, or greater than 0.85, or greater than 0.90.

[0034] In this embodiment, the ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be less than 2.0, for example, less than 1.9, or less than 1.8, or less than 1.75, or less than 1.70, or less than 1.65, or less than 1.60. The ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be greater than 1.0, for example, greater than 1.05, or greater than 1.10, or greater than 1.15, or greater than 1.20, or greater than 1.25.

[0035] According to a third aspect, a lean-burn burner is provided, comprising: a plurality of lean-burn fuel injectors, each lean-burn fuel injector including a fuel supply arm and a lean-burn fuel injector head with a lean-burn fuel injector head tip, wherein the lean-burn fuel injector head tip has a lean-burn fuel injector head tip diameter (d), the lean-burn fuel injector head including a pilot fuel injector and a main fuel injector, the main fuel injector being arranged coaxially with the pilot fuel injector and radially outward; and a burner chamber extending in an axial direction, including a radially inner annular wall, a radially outer annular wall, and a metering plate provided upstream of the radially inner annular wall and the radially outer annular wall, the metering plate having a plurality of orifices adapted to receive the lean-burn fuel injector head tips. The radially inner annular wall, the radially outer annular wall, and the metering plate define the size and shape of the burner chamber, wherein the burner chamber has a burner chamber length (L) and includes a primary combustion zone having a primary combustion zone length (Z) and a primary combustion zone depth (D) and a secondary combustion zone having a secondary combustion zone length (LZ) disposed downstream of the primary combustion zone. According to the third aspect, the ratio of the burner chamber length to the tip diameter of the lean fuel injector head, L / d, is less than 5.

[0036] In an embodiment, the ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be less than 4.5, for example, less than 4, or less than 3.5, or less than 3, or less than 2.8, or less than 2.6, or less than 2.5, or less than 2.45, or less than 2.4. The ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be greater than 1.5, for example, greater than 1.7, or greater than 1.8, or greater than 1.85, or greater than 1.9, or greater than 2.0.

[0037] In an embodiment, the ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be less than 2.4, for example, less than 2.3, or less than 2.2, or less than 2.1, or less than 2.0. The ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be greater than 1.2, for example, greater than 1.3, or greater than 1.4, or greater than 1.5.

[0038] In this embodiment, the ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be less than 2.0, for example, less than 1.9, or less than 1.8, or less than 1.75, or less than 1.70, or less than 1.65, or less than 1.60. The ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be greater than 1.0, for example, greater than 1.05, or greater than 1.10, or greater than 1.15, or greater than 1.20, or greater than 1.25.

[0039] In an embodiment, the ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be less than 1.40, for example, less than 1.35, or less than 1.30, or less than 1.25, or less than 1.20. The ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be greater than 0.70, for example, greater than 0.75, or greater than 0.80, or greater than 0.85, or greater than 0.90.

[0040] In embodiments, the lean-burner of the first, second, and third aspects described above may include a pre-diffuser disposed upstream of the lean-burn fuel injector head and adapted to supply compressed air to the combustor chamber. In some documents, the pre-diffuser is simply referred to as a diffuser. The pre-diffuser may be generally annular and may include a radially inner wall and a radially outer wall defining an outlet for compressed air. In this disclosure, the buffer gap (g) may be defined as the axial distance between the midpoint between the radially inner and radially outer walls of the pre-diffuser at the outlet and the midpoint between the radially inner and radially outer annular walls of the combustor chamber at the metering plate. The ratio of the buffer gap g to the diameter d of the lean-burn fuel injector head tip, g / d, may be less than 1.30, for example, less than 1.25, or less than 1.2, or less than 1.15. The ratio of the buffer gap g to the diameter d of the lean-burn fuel injector head tip, g / d, may be greater than 0.65, for example, greater than 0.7, or greater than 0.75, or greater than 0.8, or greater than 0.85.

[0041] Those skilled in the art will recognize that the ratio of the buffer gap g to the diameter d of the lean fuel injector tip g / d is also dimensionless and applicable to a wide range of lean burners and associated burner chambers, and can help to form an S-shaped recirculation zone within the primary combustion zone.

[0042] According to a fourth aspect, a lean-burn burner is provided, comprising: a plurality of lean-burn fuel injectors, each lean-burn fuel injector including a fuel supply arm and a lean-burn fuel injector head with a lean-burn fuel injector head tip, wherein the lean-burn fuel injector head tip has a lean-burn fuel injector head tip diameter (d), the lean-burn fuel injector head including a pilot fuel injector and a main fuel injector, the main fuel injector being arranged coaxially with the pilot fuel injector and radially outward; and a burner chamber extending in an axial direction, including a radially inner annular wall, a radially outer annular wall, and a metering plate provided upstream of the radially inner and radially outer annular walls, the metering plate having a plurality of orifices adapted to receive the lean-burn fuel injector head tip. The radially inner annular wall, the radially outer annular wall, and the metering plate define the size and shape of the burner chamber. The lean-burn burner of the fourth aspect further includes a pre-diffuser arranged upstream of the lean-burn fuel injector head and adapted to supply compressed air to the burner chamber. The pre-diffuser is generally annular and includes a radially inner wall and a radially outer wall defining an outlet for compressed air. A buffer gap (g) is defined as the axial distance between the midpoint between the radially inner and radially outer walls of the pre-diffuser at the outlet and the midpoint between the radially inner and radially outer annular walls of the combustor chamber at the metering plate, wherein the ratio of the buffer gap to the diameter of the lean-burn fuel injector tip, g / d, is less than 1.30.

[0043] In an embodiment, the ratio of the buffer gap g to the diameter d of the lean fuel injector tip, g / d, can be less than 1.25, for example, less than 1.2 or less than 1.15. The ratio of the buffer gap g to the diameter d of the lean fuel injector tip, g / d, can be greater than 0.65, for example, greater than 0.7, greater than 0.75, greater than 0.8, or greater than 0.85.

[0044] The fourth aspect of the lean-burner has a burner chamber with a burner chamber length (L) and can define a primary combustion zone with a primary combustion zone length (Z) and a primary combustion zone depth (D), and a secondary combustion zone with a secondary combustion zone length (LZ) arranged downstream of the primary combustion zone.

[0045] In an embodiment, the ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be less than 2.4, for example, less than 2.3, or less than 2.2, or less than 2.1, or less than 2.0. The ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip can be greater than 1.2, for example, greater than 1.3, or greater than 1.4, or greater than 1.5.

[0046] In this embodiment, the ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be less than 2.0, for example, less than 1.9, or less than 1.8, or less than 1.75, or less than 1.70, or less than 1.65, or less than 1.60. The ratio of the burner chamber length L to the primary combustion zone depth D, L / D, can be greater than 1.0, for example, greater than 1.05, or greater than 1.10, or greater than 1.15, or greater than 1.20, or greater than 1.25.

[0047] In an embodiment, the ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be less than 5, for example, less than 4.5, or less than 4, or less than 3.5, or less than 3, or less than 2.8, or less than 2.6, or less than 2.5, or less than 2.45, or less than 2.4. The ratio L / d of the burner chamber length L to the diameter d of the lean fuel injector tip can be greater than 1.5, for example, greater than 1.7, or greater than 1.8, or greater than 1.85, or greater than 1.9, or greater than 2.0.

[0048] In an embodiment, the ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be less than 1.40, for example, less than 1.35, or less than 1.30, or less than 1.25, or less than 1.20. The ratio Z / d of the primary combustion zone length Z to the diameter d of the lean fuel injector tip can be greater than 0.70, for example, greater than 0.75, or greater than 0.80, or greater than 0.85, or greater than 0.90.

[0049] According to a fifth aspect, a gas turbine engine is provided, which includes a lean-burn combustor according to any of the aspects described above.

[0050] The fifth aspect refers to gas turbine engines that can be used in aircraft or for industrial and marine applications.

[0051] In an embodiment, the gas turbine engine may further include: an engine core including a compressor, a burner, a turbine, and a spindle connecting the turbine to the compressor; and a fan located upstream of the engine core, the fan including a plurality of fan blades, wherein the burner is a lean-burn burner according to any one of the first, second, third, and fourth aspects.

[0052] In one embodiment, the compressor and turbine can rotate about the main rotational axis of the engine, and the axial direction of the combustor chamber can be parallel to the main rotational axis of the engine.

[0053] As noted above, the lean-burn burner according to this disclosure can be sized for adaptation to engines installed on small, medium and large aircraft. Therefore, according to the fifth aspect, the fan of the gas turbine engine can have a fan diameter greater than (or approximately) any of the following: 220 cm, 230 cm, 240 cm, 250 cm (approximately 100 inches), 260 cm, 270 cm (approximately 105 inches), 280 cm (approximately 110 inches), 290 cm (approximately 115 inches), 300 cm (approximately 120 inches), 310 cm, 320 cm (approximately 125 inches), 330 cm (approximately 130 inches), 340 cm (approximately 135 inches), 350 cm, 360 cm (approximately 140 inches), 370 cm (approximately 145 inches), 380 cm (approximately 150 inches), 390 cm (approximately 155 inches), 400 cm, 410 cm (approximately 160 inches), or 420 cm (approximately 165 inches). The fan diameter can be within an inclusive range defined by any two values ​​in the preceding sentence (i.e., these values ​​can form an upper or lower limit), for example, in the range of 240 cm to 280 cm, or 330 cm to 380 cm.

[0054] The arrangement disclosed herein can be particularly (but not only) advantageous for fans driven via a gearbox. Thus, a gas turbine engine can include a gearbox that receives input from a spindle and outputs drive to a fan to drive the fan at a lower rotational speed than the spindle. The input to the gearbox can come directly from the spindle or indirectly from the spindle, for example, via a spur shaft and / or gears. The spindle can 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).

[0055] The gas turbine engine described and / or claimed herein can have any suitable overall structure. For example, a gas turbine engine can have any desired number of shafts connecting the turbine and the compressor, such as one, two, or three shafts. Purely by example, the turbine connected to the mandrel can be a first turbine, the compressor connected to the mandrel can be a first compressor, and the mandrel can be a first mandrel. The engine core can 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 can be arranged to rotate at a higher rotational speed than the first mandrel.

[0056] In this arrangement, the second compressor can be axially positioned downstream of the first compressor. The second compressor can be arranged to receive (e.g., directly, for example, via an generally annular duct) the flow from the first compressor.

[0057] The gearbox can be arranged to be driven by a spindle (e.g., the first spindle in the example above) configured to rotate at a minimum rotational speed (e.g., in use). For example, the gearbox can be arranged to be driven only by a spindle (e.g., only the first spindle in the example above, not the second spindle) configured to rotate at a minimum rotational speed (e.g., in use). Alternatively, the gearbox can be arranged to be driven by any one or more shafts, such as the first and / or second shafts in the example above.

[0058] The gearbox can be a reduction gearbox (because the output to the fan is at a lower rotational speed than the input from the spindle). Any type of gearbox can be used. For example, the gearbox can be a "planetary" or "star" gearbox, as described in more detail elsewhere in this document. The gearbox can have any desired reduction ratio (defined as the rotational speed of the input shaft divided by the rotational speed of the output shaft), for example, greater than 2.5, for example, in the range of 3 to 4.2 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. Purely by example, the gearbox can be a "star" gearbox with a ratio in the range of 3.1 or 3.2 to 3.8.

[0059] According to one aspect, an aircraft is provided that includes a gas turbine engine as described herein and / or claimed. The aircraft according to this aspect is one to which the gas turbine engine has been designed for attachment.

[0060] Those skilled in the art will recognize that, except in cases of mutual exclusion, any feature or parameter described with respect 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

[0061] Embodiments will now be described by way of example only, with reference to the accompanying drawings, wherein:

[0062] Figure 1 It is a cross-sectional side view of a gas turbine engine;

[0063] Figure 2 yes Figure 1 A close-up cross-sectional side view of the upstream section of a gas turbine engine;

[0064] Figure 3 This is a partial sectional view of a gearbox used in a gas turbine engine;

[0065] Figure 4 This is a partial rear view of a lean-burn burner according to this disclosure;

[0066] Figure 5 yes Figure 4 A side view of the lean-burn burner along arrow AA in cross section; and

[0067] Figure 6 yes Figure 4 and Figure 5 A schematic representation of the S-shaped flow recirculation in the primary combustion zone of a lean-burn burner. Detailed Implementation

[0068] refer to Figure 1 The gas turbine engine (generally referred to as 10) has a main axis of rotation 9. Engine 10 includes an intake 12 and a propulsion fan with multiple fan blades 23, which generates two airflows: a core airflow A and a bypass airflow B. Gas turbine engine 10 includes a core 11 that receives the core airflow A. Engine core 11 includes, in series along an axial flow path, a low-pressure compressor 14, a high-pressure compressor 15, a combustion device including a lean-burn burner, a high-pressure turbine 17, a low-pressure turbine 19, and a core exhaust nozzle 20. A nacelle 21 generally surrounds 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 is attached to and driven by the low-pressure turbine 19 via a shaft 26 and a rotary gearbox 30.

[0069] In operation, the core airflow A is accelerated and 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 mixes with fuel and the mixture burns. The resulting hot combustion products then expand through the high-pressure turbine and low-pressure turbines 17, 19 before being discharged through nozzle 20, thereby driving the high-pressure and low-pressure turbines to provide some propulsive thrust. The high-pressure turbine 17 drives the high-pressure compressor 15 via a suitable interconnecting shaft 27. A fan typically provides most of the propulsive thrust. The rotary gearbox 30 is a reduction gearbox.

[0070] Note that, as used herein, the terms "low-pressure turbine" and "low-pressure compressor" can be considered to refer, respectively, to the lowest-pressure turbine stage and the lowest-pressure compressor stage (i.e., excluding the fan) and / or the turbine and compressor stages connected together by an interconnecting shaft 26 having the lowest rotational speed in the engine (i.e., excluding the gearbox output shaft driving the fan). In some literature, the terms "low-pressure turbine" and "low-pressure compressor" as used herein may alternatively be known as "intermediate-pressure turbine" and "intermediate-pressure compressor." In the case of using such alternative terminology, the fan may be referred to as the first or lowest-pressure, compression stage.

[0071] Other gas turbine engines to which this disclosure is applicable may have alternative configurations. By way of example, such engines may have an alternative number of interconnecting shafts (e.g., two) and / or an alternative number of compressors and / or turbines. Additionally, the engine may be a gearless engine, i.e., the engine may not include a gearbox provided in the transmission system from the turbine to the compressor and / or fan.

[0072] Figure 2 A more detailed illustration shows the rotary gearbox 30 of the gas turbine engine 10. The low-pressure turbine 19 (see...) Figure 1 A drive shaft 26 is coupled to a sun gear or sun gear 28 of a planetary gearbox 30. A plurality of planet gears 32 are radially outward and meshed with the sun gear 28, and are coupled together by a planet carrier 34. The planet carrier 34 constrains the planet gears 32 to precess around the sun gear 28 in a synchronized manner, while allowing each planet gear 32 to rotate about its own axis. The planet carrier 34 is coupled to a fan 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 coupled to a stationary support structure 24 via a connecting rod 40.

[0073] Figure 3 The rotating gearbox 30 is shown in more detail by way of example. Each of the sun gear 28, planetary gear 32, and ring gear 38 includes teeth around its circumference for meshing with other gears. However, for clarity, Figure 3 Only exemplary portions of the teeth are illustrated. The illustration shows four planetary gears 32, but it will be apparent to those skilled in the art that more or fewer planetary gears 32 can be provided within the scope of the claimed invention. Practical applications of the planetary gearbox 30 typically include at least three planetary gears 32.

[0074] Figure 2 and Figure 3 The planetary gearbox 30 illustrated in the example diagram is of the planetary type, where the planet carrier 34 is coupled 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 can be used. By a further example, the planetary gearbox 30 can be a star arrangement, where the planet carrier 34 remains fixed and the ring (or annular) gear 38 is allowed to rotate. In this arrangement, the fan is driven by the ring gear 38. By a further alternative example, the planetary gearbox 30 can be a differential gearbox, where both the ring gear 38 and the planet carrier 34 are allowed to rotate.

[0075] Will realize, Figure 2 and Figure 3The arrangements shown are by way of example only, and various alternatives are within the scope of this disclosure. Therefore, this disclosure extends to gas turbine engines having any arrangement of gearbox style (e.g., star or planetary), support structure, input and output shaft arrangement, and bearing location.

[0076] Figure 4 and 5 The lean burner 16 is illustrated in more detail.

[0077] The lean-burn burner 16 includes a plurality of lean-burn fuel injectors 50, each lean-burn fuel injector including a fuel supply arm 52 and a lean-burn fuel injector head 54. The fuel supply arm 52 delivers fuel from a distribution system (not shown) to the lean-burn fuel injector head 54, where the fuel and air are mixed.

[0078] The lean fuel injector head 54 includes a pilot fuel injector 56 and a radially outward main fuel injector 58. The main fuel injector 58 is arranged coaxially around the pilot fuel injector 56. The lean fuel injector head 54 further includes air swirlers (not shown for simplicity). According to known arrangements, the lean fuel injector head 54 may include three, four, or five air swirlers adapted to provide a swirling airflow that atomizes fuel from the pilot fuel injector and the main fuel injector. The air swirlers may include swirl blades.

[0079] For example, in a three-swirler arrangement, a pilot fuel injector is provided between the inner and outer air swirlers, and the main fuel injector is also provided between the inner and outer air swirlers; the outer air swirler of the pilot fuel injector is the inner air swirler of the main fuel injector. In a four-swirler arrangement, the pilot fuel injector and the main fuel injector do not share air swirlers, such that each of the pilot fuel injector and the main fuel injector includes its own set of inner and outer air swirlers. In a five-swirler arrangement, an additional air swirler is provided between the outer air swirler of the pilot fuel injector and the inner air swirler of the main fuel injector.

[0080] The lean-burn burner 16 further includes a burner chamber 60 extending in an axial direction 62. In the illustrated embodiment, the axial direction 62 is substantially parallel to the engine's main axis of rotation 9. In other embodiments not illustrated, the axial direction 62 may not be parallel to the engine's main axis of rotation 9. In other words, the combustion chamber may extend at an angle to the axial direction 62, for example, at an angle between 0° and 20°.

[0081] The burner chamber 60 includes a radially inner annular wall 64, a radially outer annular wall 66, and a metering plate 68 provided upstream of the radially inner and outer annular walls 64 and 66. Axially opposite to the metering plate 68, the burner chamber 60 is characterized by an annular outlet 67 through which the combustion gases exit the burner chamber 60. The annular outlet is defined between the respective downstream end portions of the radially inner annular wall 64 and the radially outer annular wall 66 of the burner chamber 60. In other words, the burner chamber 60 extends axially from the upstream metering plate 68 and the downstream annular outlet 67 to a length L.

[0082] The metering plate 68 is provided with a plurality of orifices 70 for receiving lean fuel injectors 50. Specifically, the lean fuel injectors 50 are connected to the metering plate 68 at the tip 72 of the lean fuel injector head 54 (coaxially received in the orifices 70).

[0083] The lean-burn fuel injector head 54 can generally extend along the longitudinal direction 55. In the illustrated embodiment, the longitudinal direction 55 is parallel to the axial direction 62. In other words, the angle α defined between the longitudinal direction 55 and the axial direction 62... 斜 It is 0°. In an embodiment not shown, the lean fuel injector head 54 may be coaxial with the orifice 70, or in other words, at an angle α. 斜 It can be different from 0°, for example, it can be included between 0° and 10°.

[0084] The lean-burn fuel injector 50 is configured to inject fuel and air into the combustor chamber 60. The midpoint 69 of the metering plate is defined as the midpoint between the radially inner annular wall 64 and the radially outer annular wall 66 at the metering plate 68.

[0085] The lean fuel injector head tip 72 is characterized by a lean fuel injector head tip diameter d, which corresponds to the diameter of the orifice 70.

[0086] The radial inner annular wall 64 and the radial outer annular wall 66 are connected to the metering plate 68 at their upstream end portions. The radial inner annular wall 64, the radial outer annular wall 66 and the metering plate 68 define the size and shape of the burner chamber 60 with their respective inner surfaces.

[0087] In an embodiment not shown, the radially inner annular wall 64, the radially outer annular wall 66, and the metering plate 68 may each include corresponding tiles. If present, the tiles define the respective inner surfaces of the radially inner annular wall 64, the radially outer annular wall 66, and the metering plate 68, and thus define the size and shape of the combustor chamber 60 (where combustion occurs). The tiles, or in other words, the inner surfaces of the radially inner annular wall 64, the radially outer annular wall 66, and the metering plate 68 face the combustion process within the combustion chamber 60 and are in contact with the fuel-air mixture and / or combustion gases.

[0088] The radially outer annular wall 66 extends substantially axially between the metering plate 68 and the annular outlet 67. In other words, the radially outer annular wall 66 forms an exterior angle α with the axial direction 62 that is substantially equal to 0°. 外 In an embodiment not shown, the radially outer annular wall 66 may form an exterior angle α different from 0° along the axial direction 62. 外 The direction extends, for example, the outer angle is between 0° and 15°.

[0089] The radially outer annular wall 66 includes a first portion 74 and a second portion 75. The first portion 74 of the radially outer annular wall 66 is disposed upstream of the second portion 75 of the radially outer annular wall 66. The upstream portion of the first portion 74 of the radially outer annular wall 66 is connected to the metering plate 68. The downstream end portion of the second portion 75 of the radially outer annular wall 66 defines an annular outlet 67 of the combustion chamber 60. In the illustrated embodiment, the first portion 74 and the second portion 75 of the radially outer annular wall 66 are integral and aligned with each other in the axial direction 62.

[0090] The radially inner annular wall 64 includes a first portion 76 and a second portion 77. The first portion 76 of the radially inner annular wall 64 is disposed upstream of the second portion 77 of the radially inner annular wall 64. The upstream portion of the first portion 76 of the radially inner annular wall 64 is connected to the metering plate 68. The downstream end portion of the second portion 77 of the radially inner annular wall 64 and the downstream end portion of the second portion 75 of the radially outer annular wall 66 define an annular outlet 67 of the combustion chamber 60. The first portion 76 of the radially inner annular wall 64 is arranged at an angle to the second portion 77 of the radially inner annular wall 64. The first portion 76 of the radially inner annular wall 64 is generally parallel to the axial direction 62. The first portion 76 of the radially inner annular wall 64 is generally parallel to the first portion 74 of the radially outer annular wall 66. The second portion 75 of the radially inner annular wall 64 converges toward the radially outer annular wall 66 in the downstream direction to form the annular outlet 67. The second portion 77 of the radially inner annular wall 64 is arranged at an angle to the first portion 76 of the radially inner annular wall 64. Furthermore, the second portion 77 of the radial inner annular wall 64 forms an interior angle α with the first portion 76 of the radial inner annular wall 64. 内 . Internal angle α 内 Typically, this angle is between 25° and 40°. Since the first portion 76 of the radially inner annular wall 76 and the radially outer annular wall 74 are generally parallel to the axial direction 62, the second portion 77 of the radially inner annular wall 64 is at an interior angle α with respect to the axial direction 62 and the radially outer annular wall 74. 内 Arrangement.

[0091] The burner chamber 60 includes a primary combustion zone 80 and a secondary combustion zone 82.

[0092] The primary combustion zone 80 is defined by a first portion 76 of a radially inner annular wall 64, a first portion 74 of a radially outer annular wall 66, and a metering plate 68. The primary combustion zone 80 is annular in cross-section and extends axially from the metering plate 68 to a length Z. In the illustrated embodiment, both the first portion 74 of the radially outer annular wall 66 and the first portion 76 of the radially inner annular wall 64 extend axially to a length Z. Furthermore, the primary combustion zone 80 extends radially (i.e., in a direction perpendicular to the axial direction 62) to a depth D between the first portion 76 of the radially inner annular wall 64 and the first portion 74 of the radially outer annular wall 66.

[0093] The secondary combustion zone 82, located downstream of the primary combustion zone 80, is defined by a second portion 77 of a radially inner annular wall 64 and a second portion 75 of a radially outer annular wall 66. In practice, the secondary combustion zone 82 extends from the downstream end portion of the primary combustion zone 80 to the annular outlet 67. The secondary combustion zone 82 extends axially to a length LZ. In the described embodiment, the second portion 75 of the radially outer annular wall 66 extends to the same length LZ, and the second portion 77 of the radially inner annular wall 64 extends to a length equal to (LZ)·sinα. 内 The length of the secondary combustion zone 82 is annular and truncated conical, converging downstream toward the annular outlet 67.

[0094] The dimensions of the combustion chamber 60 are determined such that the ratio of the combustor chamber length L to the primary combustion zone depth D, L / D, is less than 2.0 (e.g., less than 1.60) and greater than 1.0 (e.g., greater than 1.25). A ratio of L / D less than 2.0 (e.g., less than 1.60) and greater than 1.0 (e.g., greater than 1.25) allows for optimization of the aerodynamics of the fuel and air mixture from the main fuel injector and the pilot fuel injectors 56, 58 and the associated air swirlers, thereby improving combustion efficiency.

[0095] This will refer to Figure 6 To describe in more detail.

[0096] The pilot fuel-air mixture travels along a so-called S-shaped trajectory 86 within the primary combustion zone 80. The pilot fuel-air mixture from the tip 72 of the lean fuel injector head reaches a stagnation point SP, where the pilot fuel-air mixture has a local velocity of zero, and then turns backward toward the radially outer and radially inner annular walls 74, 76 (due to the low static pressure exerted by the main fuel-air mixture 84), where the pilot fuel-air mixture contacts and supports / stabilizes the combustion of the main fuel-air mixture 84.

[0097] A ratio L / D less than 2.0 (e.g., less than 1.60) and greater than 1.0 (e.g., greater than 1.25) allows for S-shaped flow recirculation of the pilot fuel-air mixture within the primary combustion zone 80. In other words, the pilot fuel-air mixture stagnation point SP is located within the primary combustion zone 80, and the pilot fuel-air mixture mixes with the main fuel-air mixture 84 within the primary combustion zone 80.

[0098] Other dimensionless parameters can have a positive impact on the formation of the S-shaped trajectory 86 of the pilot fuel-air mixture within the primary combustion zone 80.

[0099] The dimensions of the burner chamber 60 can be determined such that the ratio of the burner chamber length L to the diameter d of the lean fuel injector tip, L / d, is less than 5 or less than 2.5, and greater than 1.5 or greater than 2.0. In an embodiment, the burner chamber 60 may have a ratio L / d of 3.5.

[0100] Furthermore, the dimensions of the combustion chamber 60 can be determined such that the ratio D / d of the primary combustion zone depth D to the diameter d of the lean fuel injector tip is between 1.2 and 2.4, preferably between 2.0 and 2.4. In an embodiment, the combustor chamber 60 may have a ratio D / d of 2.2.

[0101] Furthermore, the dimensions of the combustion chamber 60 can be determined such that the ratio Z / d of the primary combustion zone length L to the diameter d of the lean fuel injector tip is greater than 0.7 and less than 1.40, preferably between 0.9 and 1.25. In an embodiment, the combustor chamber 60 may have a ratio Z / d of 1.05.

[0102] The ratios (L / d, D / d, and Z / d) above can help optimize the aerodynamics of the fuel and air mixture from the main fuel injector and the pilot fuel injectors 56, 58 and the associated air vortex, and improve combustion efficiency.

[0103] It should be noted that all the above ratios (L / D, L / d, D / d, and Z / d) are dimensionless and therefore applicable to a wide range of lean-burn burners. For example, D can include between 90 mm and 150 mm, for example, between 110 mm and 140 mm; d can include between 60 mm and 100 mm, for example, between 70 mm and 85 mm; Z can include between 50 mm and 130 mm, for example, between 60 mm and 110 mm; and L can include between 100 mm and 200 mm.

[0104] The lean burner 16 further includes a pre-diffuser 90 for supplying compressed air from the high-pressure compressor 15 to the lean fuel injector head 54. The pre-diffuser is annular and includes a radially inner wall 92 and a radially outer wall 94 defining an outlet 96 for compressed air. The outlet pre-diffuser midpoint 98 is defined midway between the radially inner wall 92 and the radially outer wall 94 at the outlet 96.

[0105] A pre-diffuser 90 is disposed upstream of the lean fuel injector head 54 at a distance g (buffer gap) from the metering plate 68. The buffer gap g is defined as the axial distance between the midpoint 98 of the outlet pre-diffuser and the midpoint 69 of the metering plate. The pre-diffuser 90 is spaced from the combustor chamber 60 such that the ratio g / d of the buffer gap g to the diameter d of the lean fuel injector head tip can be less than 1.30, for example, less than 1.15, and greater than 0.65, for example, greater than 0.85. In an embodiment, the combustor chamber 60 can have a ratio g / d of 1.05.

[0106] Arranging the pre-diffuser 90 at a distance from the metering plate 68 such that the ratio of the buffer gap g to the diameter d of the lean fuel injector tip g / d can be less than 1.30 and greater than 0.65 can further improve the aerodynamics of the pilot fuel and main fuel-air mixture within the combustor chamber 60 (and especially within the primary combustion zone 80).

[0107] Although this disclosure has been described with reference to turbofan gas turbine engines, its use in turbojet gas turbine engines, turboshaft gas turbine engines, or turboprop gas turbine engines is equally possible. Similarly, although this disclosure has been described with reference to aviation gas turbine engines, its use in marine gas turbine engines or industrial gas turbine engines is equally possible.

Claims

1. A lean-burn burner (16), comprising: - A plurality of lean-burn fuel injectors (50), each lean-burn fuel injector including a fuel supply arm (52) and a lean-burn fuel injector head (54) with a lean-burn fuel injector head tip (72), wherein the lean-burn fuel injector head tip (72) has a lean-burn fuel injector head tip diameter d, and the lean-burn fuel injector head (54) includes a pilot fuel injector (56) and a main fuel injector (58), the main fuel injector (58) being arranged coaxially with the pilot fuel injector (56) and radially outward; and - A burner chamber (60) extending in an axial direction (62) and including a radially inner annular wall (64), a radially outer annular wall (66), and a metering plate (68) provided upstream of the radially inner annular wall and the radially outer annular wall, the metering plate having a plurality of orifices (70) adapted to receive the tip (72) of the lean fuel injector head, the radially inner annular wall (64), the radially outer annular wall (66), and the metering plate (68) defining the size and shape of the burner chamber (60), wherein the burner chamber (60) has a burner chamber length L and includes a primary combustion zone (80) having a primary combustion zone length Z and a primary combustion zone depth D, and a secondary combustion zone (82) having a secondary combustion zone length LZ disposed downstream of the primary combustion zone (80). Wherein, the ratio L / D of the burner chamber length to the primary combustion zone depth is less than 2.

0.

2. The lean-burn burner according to claim 1, wherein, The ratio of the burner chamber length to the primary combustion zone depth, L / D, is less than 1.

6.

3. The lean-burn burner according to claim 1, wherein, The ratio L / D of the burner chamber length to the primary combustion zone depth is greater than 1.

0.

4. The lean-burn burner according to claim 1, wherein, The ratio L / D of the burner chamber length to the primary combustion zone depth is greater than 1.

25.

5. The lean-burn burner according to any one of claims 1-4, wherein, The ratio L / d of the burner chamber length to the tip diameter of the lean fuel injector head is less than 4.5; and / or wherein the ratio L / d of the burner chamber length to the tip diameter of the lean fuel injector head is greater than 1.

5.

6. The lean-burn burner according to any one of claims 1-4, wherein, The ratio L / d of the burner chamber length to the tip diameter of the lean fuel injector head is less than 2.8; and / or wherein the ratio L / d of the burner chamber length to the tip diameter of the lean fuel injector head is greater than 2.

0.

7. The lean-burn burner according to any one of claims 1-4, wherein, The ratio D / d of the primary combustion zone depth to the tip diameter of the lean fuel injector head is less than 2.3; and / or wherein the ratio D / d of the primary combustion zone depth to the tip diameter of the lean fuel injector head is greater than 1.

3.

8. The lean-burn burner according to any one of claims 1-4, wherein, The ratio D / d of the primary combustion zone depth to the tip diameter of the lean fuel injector head is less than 2.1; and / or wherein the ratio D / d of the primary combustion zone depth to the tip diameter of the lean fuel injector head is greater than 1.

4.

9. The lean-burn burner according to any one of claims 1-4, wherein, The ratio Z / d of the length of the primary combustion zone to the diameter of the tip of the lean fuel injector is less than 1.40; and / or wherein the ratio Z / d of the length of the primary combustion zone to the diameter of the tip of the lean fuel injector is greater than 0.

70.

10. The lean-burn burner according to any one of claims 1-4, wherein, The ratio Z / d of the length of the primary combustion zone to the diameter of the tip of the lean fuel injector is less than 1.20; and / or wherein the ratio Z / d of the length of the primary combustion zone to the diameter of the tip of the lean fuel injector is greater than 0.

90.

11. The lean-burn burner according to any one of claims 1-4, further comprising a pre-diffuser (90) disposed upstream of the lean-burn fuel injector head (54) and adapted to supply compressed air to the burner chamber (60), the pre-diffuser (90) being generally annular and comprising a radially inner wall (92) and a radially outer wall (94) defining an outlet (96), the buffer gap g being defined as the axial distance between the midpoint (98) of the pre-diffuser (90) between the radially inner wall (92) and the radially outer wall (94) at the outlet (96) and the midpoint (69) of the burner chamber (60) between the radially inner annular wall (64) and the radially outer annular wall (66) at the metering plate (68), wherein, The ratio g / d between the buffer gap and the tip diameter of the lean fuel injector is less than 1.

25.

12. The lean-burn burner according to claim 11, wherein, The ratio g / d between the buffer gap and the tip diameter of the lean fuel injector head is less than 1.

15.

13. The lean-burn burner according to claim 11, wherein, The ratio g / d between the buffer gap and the diameter of the tip of the lean fuel injector is greater than 0.

7.

14. The lean-burn burner according to claim 11, wherein, The ratio g / d between the buffer gap and the diameter of the tip of the lean fuel injector is greater than 0.

85.

15. The lean-burn burner according to any one of claims 1-4, wherein, The radial outer annular wall (66) of the burner chamber (60) forms an outer angle α with the axial direction (62). 外 The outer angle α 外 Includes the range between 0° and 15°.

16. The lean-burn burner according to any one of claims 1-4, wherein, The radial inner annular wall (64) of the burner chamber (60) includes a first portion (76) and a second portion (77), the second portion (77) forming an interior angle α with the first portion (76). 内 The interior angle α 内 This includes the range between 15° and 50°.

17. The lean-burn burner according to claim 16, wherein, The interior angle α 内 Includes the range between 25° and 40°.

18. The lean-burn burner according to any one of claims 1-4, wherein, The lean fuel injector head (54) generally extends along the longitudinal direction (55), which forms an angle α with the axial direction (62). 斜 The oblique angle α 斜 Includes the range between 0° and 10°.

19. The lean-burn burner according to any one of claims 1-4, wherein, The radial inner annular wall (64), the radial outer annular wall (66), and the metering plate (68) are each provided with a corresponding tile, the tile defining the respective inner surface of the radial inner annular wall (64), the radial outer annular wall (66), and the metering plate (68).

20. A gas turbine engine (10) comprising a lean-burn burner (16) according to any one of claims 1-19.

21. The gas turbine engine of claim 20, further comprising: - Engine core (11), the engine core including compressor (14), lean burner, turbine (19) and spindle (26) connecting turbine (19) to compressor (14). - A fan located upstream of the engine core, the fan comprising a plurality of fan blades (23).

22. The gas turbine engine according to claim 21, wherein, The compressor (14) and turbine (19) rotate about the main rotation axis (9) of the engine, and the axial direction (62) of the combustor chamber (60) is parallel to the main rotation axis (9) of the engine.

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