New fuel mixing structure for a central staged combustor

Abstract

The present invention relates to the field of aviation engine technology, and in particular to a novel fuel mixing structure of a central staged combustion chamber, comprising a main combustion stage sleeve, a plurality of partitions and a plurality of main combustion stage swirlers; the partitions are arranged on the inner side of the main combustion stage sleeve, and the partitions divide the inner side of the main combustion stage sleeve into a plurality of mounting cavities; the main combustion stage swirlers correspond to the mounting cavities one by one, and the main combustion stage swirlers are fixed in the corresponding mounting cavities, and the main combustion stage swirlers comprise a mixing tube located in the middle and a plurality of spiral blades arranged on the outer side of the mixing tube, and the rotation direction of each spiral blade is the same. The main combustion stage swirler of the present invention comprises a mixing tube located in the middle and a plurality of spiral blades arranged on the outer side of the mixing tube, which can change the fuel mixing method of the traditional main combustion stage and can greatly improve the swirl intensity; and has the advantages of small size and compact structure, is convenient for installation and operation, and can meet the requirements of small size and high flow rate of modern engines.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation engines, and in particular to a novel fuel mixing structure of a central staged combustion chamber. Background Art

[0002] As society increasingly addresses environmental pollution, pollutant emission standards are becoming increasingly stringent. The combustion of fossil fuels in power plants is a major cause of atmospheric pollution and ozone layer depletion. Therefore, reducing the proportion of combustion exhaust gases emitted from power plants and ensuring more complete fuel combustion is a key approach to controlling environmental pollution. At the same time, future generations of aircraft engines will also place new demands on the combustion performance of combustion chambers. Achieving sufficient oil and gas mixing is a common technical challenge. Due to the high temperature and low pressure inlet parameters and compact size of the main combustion chamber, which results in a high reference velocity, it is necessary to address the oil and gas mixing issue across a wide range of inlet temperatures to achieve efficient combustion and low emissions.

[0003] Staged combustion uses two combustion zones to simultaneously stage fuel and air. Currently, there are four mainstream staged combustion modes, both domestically and internationally: centrally staged, circumferentially staged, axially staged, and radially staged. The centrally staged structure is currently the dominant aircraft engine combustor configuration.

[0004] The central staged combustion chamber generally adopts the combustion organization mode of concentric layered swirl flame, such as Figure 1 As shown, the inner layer is the pre-combustion stage 1, which uses diffusion flame to improve the combustion efficiency in the single flame state and play a role in stabilizing the fire under large working conditions. The outer layer is the main combustion stage 3, which can ensure the combustion efficiency and low emission requirements in the dual flame mode. Both the pre-combustion stage 1 and the main combustion stage 3 are equipped with traditional swirlers 2.

[0005] The traditional center-stage combustion chamber has the following shortcomings: 1. The new generation of main combustion chambers has high requirements for mixing time and mixing distance, and the traditional center-stage combustion chamber cannot adapt to the requirements of compact space; 2. The single-stage axial swirl mixing efficiency of the pre-combustion stage 1 is low; 3. The main combustion stage has a simple structure and adopts blade injection, which can improve the head flow rate but the effect is limited. Summary of the Invention

[0006] The present invention provides a novel fuel mixing structure of a central staged combustion chamber, which is used to solve the problem in the prior art that the effect of using blade injection in the main combustion stage to improve the head flow rate is limited.

[0007] The present invention provides a novel fuel mixing structure of a central staged combustion chamber, comprising:

[0008] Main combustion stage sleeve;

[0009] A plurality of partitions are provided on the inner side of the main combustion stage sleeve, wherein the partitions divide the inner side of the main combustion stage sleeve into a plurality of installation cavities;

[0010] Multiple main combustion stage swirlers correspond one-to-one to the installation cavities. The main combustion stage swirlers are fixed in the corresponding installation cavities. The main combustion stage swirlers include a mixing tube located in the middle and multiple spiral blades arranged on the outside of the mixing tube. The rotation direction of each spiral blade is the same.

[0011] According to a novel fuel mixing structure of a central staged combustion chamber provided by the present invention, each of the main combustion stage swirlers is correspondingly provided with a nozzle.

[0012] According to the novel fuel mixing structure of a central staged combustion chamber provided by the present invention, the nozzle is arranged on the mixing pipe.

[0013] According to a novel fuel mixing structure of a central staged combustion chamber provided by the present invention, the spiral radius of the spiral blade is 5.25 mm and the pitch is 12 mm.

[0014] According to the present invention, a new fuel mixing structure of a central staged combustion chamber further includes a first pre-combustion stage and a second pre-combustion stage; the first pre-combustion stage, the second pre-combustion stage and the main combustion stage sleeve are sequentially sleeved in the radial direction.

[0015] According to the present invention, a new fuel mixing structure of a central staged combustion chamber is provided, which also includes: an outer ring, a diffuser, a fuel rod nozzle structure and a restriction domain structure; the first-stage pre-combustion stage, the second-stage pre-combustion stage, the main combustion stage sleeve, the baffle, the main combustion stage swirler, the diffuser, the fuel rod nozzle structure and the restriction domain structure are arranged inside the outer ring; the fuel rod nozzle structure is located on the inner side of the first-stage pre-combustion stage, the diffuser is located on the side of the first-stage pre-combustion stage, the second-stage pre-combustion stage and the main combustion stage close to the outer ring airflow inlet, and the restriction domain structure is located on the side of the first-stage pre-combustion stage, the second-stage pre-combustion stage and the main combustion stage close to the outer ring airflow outlet, and a cooling cavity is formed between the restriction domain structure and the outer ring.

[0016] According to a new fuel mixing structure of a central staged combustion chamber provided by the present invention, the diffuser includes guide vanes, which divide the interior of the outer ring into a first channel, a second channel and a third channel arranged downward in sequence, and the first channel, the second channel and the third channel respectively play a role of diffusion.

[0017] According to a novel fuel mixing structure of a central staged combustion chamber provided by the present invention, the blades of the swirlers in the first pre-combustion stage and the second pre-combustion stage have opposite rotation directions.

[0018] The present invention provides a novel fuel mixing structure for a centrally staged combustion chamber. The main combustion stage swirler includes a mixing tube located in the middle and a plurality of spiral blades arranged on the outside of the mixing tube. This can change the traditional main combustion stage fuel mixing method and greatly improve the swirl intensity. It also has the advantages of small size and compact structure, is easy to install and operate, and can meet the requirements of modern engines for small size and high flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 It is a structural diagram of the combustion chamber head in the prior art;

[0021] Figure 2 This is one of the structural schematic diagrams of the main combustion stage in a new fuel mixing structure of a central staged combustion chamber provided by the present invention;

[0022] Figure 3 This is the second structural diagram of the main combustion stage in the novel fuel mixing structure of the central staged combustion chamber provided by the present invention;

[0023] Figure 4 This is a schematic structural diagram of a main combustion stage swirler in a novel fuel mixing structure of a central staged combustion chamber provided by the present invention;

[0024] Figure 5 This is a structural schematic diagram of a novel fuel mixing structure of a central staged combustion chamber provided by the present invention;

[0025] Figure 6 This is one of the schematic diagrams of the coordination structure of the first and second pre-combustion stages in a novel fuel mixing structure of a central staged combustion chamber provided by the present invention;

[0026] Figure 7 This is a second schematic diagram of the coordination structure of the first and second pre-combustion stages in a novel fuel mixing structure of a central staged combustion chamber provided by the present invention;

[0027] Figure 8 This is a structural schematic diagram of a diffuser in a novel fuel mixing structure of a central staged combustion chamber provided by the present invention;

[0028] Figure numerals: 1, pre-combustion stage; 2, swirler; 3, main combustion stage; 4, outer ring; 5, diffuser; 6, oil rod nozzle structure; 7, first-stage pre-combustion stage; 8, second-stage pre-combustion stage; 9, restriction zone structure; 10, first-stage pre-combustion stage sleeve; 11, first-blade swirler; 12, second-stage pre-combustion stage sleeve; 13, second-blade swirler; 14, main combustion stage sleeve; 15, main combustion stage swirler; 16, partition; 17, guide vane; 18, first channel; 19, second channel; 20, third channel; 21, mixing tube; 22, spiral blade. DETAILED DESCRIPTION

[0029] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0030] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0031] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on the specific circumstances.

[0032] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0033] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0034] The following combination Figure 1-Figure 7 The novel fuel mixing structure of the central staged combustion chamber according to the embodiment of the present invention is described.

[0035] Combine Figure 1 The main combustion stage 3 and pre-combustion stage 1, as the key structures of the central staged combustion chamber, directly affect the efficiency of aviation kerosene combustion and the pollution emission results. The swirler 2 is a structure that mixes the incoming air and fuel by forming a specific restricted area at the head of the combustion chamber. It can effectively improve the fuel mixing effect, enhance combustion efficiency and reduce pollutant emissions. The center is the pre-combustion stage 1, which adopts a diffusion flame to ensure the combustion efficiency and flame stability in the slow-running state (only the pre-combustion stage 1 is turned on, single flame); the periphery is the main combustion stage 3, which can ensure high combustion efficiency and low emissions under large working conditions such as approach, climb, and takeoff (the main combustion stage 3 and pre-combustion stage 1 work at the same time, double flame).

[0036] With the continuous development of science and technology, people's requirements for aircraft performance are constantly increasing. On the one hand, people have put forward more stringent index requirements for existing aircraft engine combustion chambers, including increasingly stringent emission requirements; on the other hand, future aircraft engine combustion chambers will develop in the direction of compact space, high combustion efficiency and high head flow rate, which makes the existing aircraft engine combustion chambers unable to adapt to the requirements of the new generation of main combustion chambers for mixing time and mixing distance.

[0037] According to an embodiment of the present invention, the novel fuel mixing structure of the central staged combustion chamber includes a main combustion stage sleeve 14, a plurality of main combustion stage swirlers 15 and a plurality of baffles 16; the plurality of baffles 16 are arranged on the inner side of the main combustion stage sleeve 14, and the baffles 16 divide the inner side of the main combustion stage sleeve 14 into a plurality of installation cavities; the plurality of main combustion stage swirlers 15 correspond one-to-one to the installation cavities, and the main combustion stage swirlers 15 are fixed in the corresponding installation cavities, and the main combustion stage swirlers 15 include a mixing tube 21 located in the middle and a plurality of spiral blades 22 arranged on the outside of the mixing tube 21, and the rotation direction of each spiral blade 22 is the same.

[0038] This embodiment of the present invention replaces the traditional centrally staged combustor blade swirl method with a multi-flame method. Through the novel mixing method of the main stage swirler 15, this improves head mixing and atomization performance, ultimately achieving the goal of improving combustor combustion and emissions performance. The main stage swirler 15 meets the small size and high flow rate requirements of modern engines; it has no moving parts, making it easy to install and operate. The mixing unit, consisting of multiple main stage swirlers 15 and multiple baffles 16, operates independently without interfering with each other, significantly increasing swirl intensity.

[0039] Optionally, the main combustion stage swirler 15 includes four spiral blades 22, each spiral blade 22 is evenly arranged along the circumference of the mixing tube 21, and the edge of the spiral blade 22 is in contact with the inner wall of the partition 16.

[0040] Optionally, each main combustion stage swirler 15 is provided with a corresponding nozzle.

[0041] Optionally, the nozzle is provided at the mixing tube 21 .

[0042] In this embodiment, the new fuel mixing structure of the central staged combustion chamber is small in size and compact in structure. No pressure nozzle is used. The main combustion stage 3 nozzle is welded by a 15 mm long capillary tube. The capillary tube is inserted into the mixing tube 21 to provide fuel injection.

[0043] Optionally, the spiral blade 22 has a spiral radius of 5.25 mm and a spiral pitch of 12 mm.

[0044] Optionally, the length of the baffle 16 is greater than that of the main combustion stage swirler 15. At the airflow inlet, the main combustion stage swirler 15 is aligned with the baffle 16. At the airflow outlet, a 4 mm margin is left between the ends of the main combustion stage swirler 15 and the baffle 16. This enhances the atomization effect by lengthening the restricted area of the fuel and air premixing channel, while also preventing kerosene self-ignition and flashback.

[0045] The new fuel mixing structure of the central staged combustion chamber also includes an outer ring 4 and a diffuser 5, an oil rod nozzle structure 6, a first-stage pre-combustion stage 7, a second-stage pre-combustion stage 8, and a restriction domain structure 9 arranged inside the outer ring 4; the first-stage pre-combustion stage 7, the second-stage pre-combustion stage 8 and the main combustion stage sleeve 14 are arranged in sequence along the radial direction, and the main combustion stage swirler 15 and the baffle 16 are located between the second-stage pre-combustion stage 8 and the main combustion stage sleeve 14; the oil rod nozzle structure 6 is located on the inner side of the first-stage pre-combustion stage 7, the diffuser 5 is located on the side of the first-stage pre-combustion stage 7, the second-stage pre-combustion stage 8 and the main combustion stage sleeve 14 close to the air flow inlet of the outer ring 4, the restriction domain structure 9 is located on the side of the first-stage pre-combustion stage 7, the second-stage pre-combustion stage 8 and the main combustion stage sleeve 14 close to the air flow outlet of the outer ring 4, and a cooling cavity is formed between the restriction domain structure 9 and the outer ring 4.

[0046] In the embodiment of the present invention, the first-stage pre-combustion stage 7 and the second-stage pre-combustion stage 8 constitute a two-stage axial pre-combustion stage structure. The incoming gas enters from the left head, is atomized by the shearing action of the two-stage blades, and then enters the interior of the combustion chamber to mix with the kerosene sprayed from the oil rod nozzle structure 6. The atomization effect is better than that of the single-stage axial pre-combustion stage, the layout of the combustion chamber is improved, the combustion performance and emission performance are optimized, and a wider ignition range and working range can be achieved than the existing combustion chamber.

[0047] In some embodiments of the present invention, the first pre-combustion stage 7 includes a first pre-combustion stage sleeve 10 and a first vane swirler 11 disposed inside the first pre-combustion stage sleeve 10, and the oil boom nozzle structure 6 is located inside the first vane swirler 11. The second pre-combustion stage 8 includes a second pre-combustion stage sleeve 12 sleeved outside the first pre-combustion stage sleeve 10 and a second vane swirler 13 disposed between the first pre-combustion stage sleeve 10 and the second pre-combustion stage sleeve 12.

[0048] The length of the first-stage pre-combustion stage sleeve 10 is smaller than that of the second-stage pre-combustion stage sleeve 12 . The end of the first-stage pre-combustion stage sleeve 10 close to the diffuser 5 is aligned with the second-stage pre-combustion stage sleeve 12 , and the end of the first-stage pre-combustion stage sleeve 10 away from the diffuser 5 is located inside the second-stage pre-combustion stage sleeve 12 .

[0049] The first vane swirler 11 and the second vane swirler 13 are conventional vane swirler structures.

[0050] Optionally, a partial section between the two ends of the first-stage pre-combustion stage sleeve 10 and the second-stage pre-combustion stage sleeve 12 is provided with a variable diameter structure with a reduced inner diameter, and the end of the first-stage pre-combustion stage sleeve 10 and the second-stage pre-combustion stage sleeve 12 away from the diffuser 5 is provided with a flaring structure with a gradually increasing inner diameter.

[0051] Optionally, a limit plate is provided on the outer side of the end of the second pre-combustion stage sleeve 12 away from the diffuser 5, and the limit plate cooperates with the end of the main combustion stage structure away from the diffuser 5 to limit the position. A stepped structure is formed between the main combustion stage structure and the pre-combustion stage, which can separate the two jets of the main combustion stage structure and the pre-combustion stage. The main combustion stage flame is outside and the pre-combustion stage flame is inside, which affects the intersection position of the two airflows, thereby affecting the flow field, emissions, ignition, lean flameout and other performance.

[0052] In some embodiments of the present invention, the blade rotation directions of the swirlers in the first pre-combustion stage 7 and the second pre-combustion stage 8 are opposite, that is, the blade rotation directions of the first vane swirler 11 and the second vane swirler 13 are opposite, for example, the rotation direction of the first vane swirler 11 is clockwise, and the rotation direction of the blade of the second vane swirler 13 is counterclockwise, or the rotation direction of the first vane swirler 11 is counterclockwise, and the rotation direction of the blade of the second vane swirler 13 is clockwise.

[0053] Optionally, the swirlers in the first pre-combustion stage 7 and the second pre-combustion stage 8 are arranged at one end of the first pre-combustion stage 7 and the second pre-combustion stage 8 close to the diffuser 5 .

[0054] In some embodiments of the present invention, the diffuser 5 includes two guide vanes 17, which are arranged opposite to each other and arranged vertically. The guide vanes 17 separate the inner portion of the outer ring 4 near the air flow inlet into a first channel 18, a second channel 19 and a third channel 20 arranged downward in sequence. The first channel 18, the second channel 19 and the third channel 20 respectively play a role of diffusion.

[0055] The diffuser 5 of this embodiment comprises a multi-channel pre-diffuser and a sudden expansion zone. Unlike a single-channel sudden expansion diffuser, the rear end of the pre-diffuser does not extend into the sudden expansion zone. Airflow first enters the pre-diffuser, where it is divided into three by built-in guide vanes 17. The airflow then enters three channels, each equivalent to a small diffuser, for deceleration and expansion. The guide vanes 17 direct the airflow toward the inner and outer annular channels and the flame tube, reducing the required turning angle of the airflow in the sudden expansion zone.

[0056] Optionally, the overall expansion angle a of the diffuser 5 is 68.286°, the expansion angle of the first channel 18 is 17.574°, the expansion angle of the second channel 19 is 56.7872°, and the expansion angle of the third channel 20 is 6.0186°; the sudden expansion gap of the diffuser 5 (the distance from the outlet of the diffuser 5 to the inlet of the flame tube) is 15.1mm to 17.3mm, the inlet height of the diffuser 5 (the distance between the two first guide vanes at the air flow inlet end) is 27.4976mm, and the sudden expansion gap ratio ε of the diffuser 5 (defined as ε = sudden expansion gap / diffuser 5 inlet height) is 0.54 to 0.63.

[0057] The novel fuel mixing structure of the central staged combustion chamber provided by the present invention utilizes the deceleration and pressurization of the diffuser 5 and the strong swirl effect of the head structure to reasonably distribute the incoming air volume, enhance the atomization effect, improve the flow rate of the combustion chamber head and shorten the residence time; at the same time, due to the reasonable structure, the layout of the combustion chamber is improved, making the combustion chamber more compact, optimizing the combustion performance and emission performance, and achieving a wider ignition and extinction range and operating range than the existing combustion chamber.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A central staged combustion chamber fuel mixing structure, characterized in that: include: Main combustion stage sleeve; A plurality of partitions are provided on the inner side of the main combustion stage sleeve, wherein the partitions divide the inner side of the main combustion stage sleeve into a plurality of installation cavities; A plurality of main combustion stage swirlers correspond one-to-one to the installation cavities, and the main combustion stage swirlers are fixed in the corresponding installation cavities. The length of each baffle is greater than the length of each main combustion stage swirler. Each pair of baffles and the main combustion stage swirler are aligned at the air flow inlet end, and a margin is reserved at the outlet end; the main combustion stage swirler includes a mixing tube located in the middle and a plurality of spiral blades arranged on the outside of the mixing tube, and the rotation direction of each spiral blade is the same. The mixing unit composed of the plurality of main combustion stage swirlers and the plurality of baffles works independently, and the spiral blades are evenly arranged along the circumference of the mixing tube, and the edge of the spiral blade is in contact with the inner wall of the baffle.

2. The central staged combustion chamber fuel mixing structure according to claim 1, characterized in that: Each of the main combustion stage swirlers is correspondingly provided with a nozzle.

3. The central staged combustion chamber fuel mixing structure according to claim 2, characterized in that: The nozzle is arranged on the mixing tube.

4. The central staged combustion chamber fuel mixing structure according to any one of claims 1 to 3, characterized in that: The spiral blade has a spiral radius of 5.25 mm and a pitch of 12 mm.

5. The central staged combustion chamber fuel mixing structure according to claim 1, characterized in that: It also includes a first-stage pre-combustion stage and a second-stage pre-combustion stage; the first-stage pre-combustion stage, the second-stage pre-combustion stage and the main combustion stage sleeve are sequentially sleeved in the radial direction.

6. The central staged combustion chamber fuel mixing structure according to claim 5, characterized in that: Also includes: An outer ring, a diffuser, a fuel rod nozzle structure and a restriction domain structure; the first-stage pre-combustion stage, the second-stage pre-combustion stage, the main combustion stage sleeve, the partition, the main combustion stage swirler, the diffuser, the fuel rod nozzle structure and the restriction domain structure are arranged inside the outer ring; the fuel rod nozzle structure is located on the inner side of the first-stage pre-combustion stage, the diffuser is located on the side of the first-stage pre-combustion stage, the second-stage pre-combustion stage and the main combustion stage close to the outer ring airflow inlet, the restriction domain structure is located on the side of the first-stage pre-combustion stage, the second-stage pre-combustion stage and the main combustion stage close to the outer ring airflow outlet, and a cooling cavity is formed between the restriction domain structure and the outer ring.

7. The central staged combustion chamber fuel mixing structure according to claim 6, characterized in that: The diffuser includes guide vanes, which divide the interior of the outer ring into a first channel, a second channel, and a third channel arranged downward in sequence. The first channel, the second channel, and the third channel respectively play a role of pressure diffusion.

8. The central staged combustion chamber fuel mixing structure according to any one of claims 5 to 7, characterized in that: The blades of the swirlers in the first pre-combustion stage and the second pre-combustion stage have opposite rotation directions.

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