Divergent cooling structure, flame tube and aeroengine

Abstract

The application discloses a divergent cooling structure, a flame tube and an aero-engine. The divergent cooling structure comprises a cooling ring used for enclosing a flame tube, and an air inlet structure used for introducing a cooling airflow into the flame tube is arranged on the cooling ring. The air inlet structure comprises a main cooling channel used for introducing the cooling airflow into the flame tube and a bifurcated cooling channel used for introducing the cooling airflow to reduce the airflow velocity at the outlet of the main cooling channel. The main cooling channel is communicated with a cold side wall surface and a hot side wall surface of the cooling ring, and the main cooling channel is arranged at an angle with the hot side wall surface. A first end of the bifurcated cooling channel is communicated with one end of the main cooling channel close to the hot side wall surface. A second end of the bifurcated cooling channel is communicated with one end of the main cooling channel close to the cold side wall surface, or the second end of the bifurcated cooling channel is communicated with the cold side wall surface. The cooling airflow into the main combustion zone can be reduced, the cooling air film can be independently formed, the wall temperature gradient of the cooling ring can be reduced, the temperature stress of the cooling ring can be reduced, and the service life of the flame tube can be prolonged.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and in particular, to a divergent cooling structure. Furthermore, this invention also relates to a flame tube including the aforementioned divergent cooling structure. This invention further relates to an aero-engine including the aforementioned flame tube. Background Technology

[0002] The flame tube is a core component of the combustion chamber of an aero-engine / gas turbine. Its function is to organize the mixing and combustion of fuel and air, and to generate high-temperature gas that drives the turbine to do work. Since the flame temperature of aviation kerosene combustion can reach over 2000K, efficient cooling design is one of the core technologies to prevent the flame tube from being burned.

[0003] The continuous improvement of aero-engine performance has led to the development of engine combustion chambers towards higher temperatures and lower emissions. This has resulted in a significant increase in the amount of air involved in combustion, while the amount of air used to cool the flame tube walls has been greatly reduced. Simultaneously, the increase in compressor pressure ratio has also reduced the cooling air's potential. Divergent cooling is a highly efficient cooling method (similar to how the numerous tiny pores on the human skin regulate body temperature through sweating, hence also known as perspiration cooling), greatly saving cooling air consumption. It can be used for cooling the entire flame tube, and is also suitable for small, localized overheated areas of the flame tube or parts of the flame tube where film cooling slots are not suitable. At the front end of divergent cooling, film cooling is generally used to form the initial film. Typical divergent cooling structures and their flame tubes are shown below. Figure 1 As shown.

[0004] Existing divergent cooling and flame tubes typically have the following drawbacks: 1. Divergent cooling usually requires the use of film cooling or a Z-ring or other cooling structure to form an initial film of air in order to achieve a good cooling effect; it is difficult to exist independently. 2. The cooling gas velocity at the outlet of the divergent orifice is usually high, and the cooling gas flow penetrates deeper into the mainstream zone and participates in combustion, making it difficult to form a wall-adhering effect. This should be avoided as much as possible in the cooling design of the main combustion zone of a low-pollution combustion chamber. 3. The metal wall temperature gradient between the two divergent cooling orifices is large, which should be avoided as much as possible in the design of a long-life flame tube. Summary of the Invention

[0005] This invention provides a divergent cooling structure, a flame tube, and an aero-engine to solve the technical problems of existing divergent cooling systems, which require the use of other cooling structures, have high outlet airflow velocities, and large wall temperature gradients.

[0006] According to one aspect of the present invention, a divergent cooling structure is provided, comprising a cooling ring for enclosing and forming a flame tube, wherein the cooling ring has an air intake structure for introducing cooling airflow into the flame tube, the air intake structure comprising a main cooling channel for introducing cooling airflow into the flame tube and a branched cooling channel for introducing cooling airflow to reduce the airflow velocity at the outlet of the main cooling channel; the main cooling channel connects the cold side wall and the hot side wall of the cooling ring, and the main cooling channel is arranged at an angle to the hot side wall; a first end of the branched cooling channel is connected to an end of the main cooling channel near the hot side wall; a second end of the branched cooling channel is connected to an end of the main cooling channel near the cold side wall, or the second end of the branched cooling channel is connected to the cold side wall.

[0007] Furthermore, the bifurcated cooling channel includes an air inlet section that communicates with one end of the main cooling channel near the cold side wall or with the cold side wall, an air outlet section that communicates with one end of the main cooling channel near the hot side wall, and a transition section for connecting the air inlet section and the air outlet section, the transition section being arc-shaped.

[0008] Furthermore, the angle θ between the air outlet section and the main cooling channel is 120~165°.

[0009] Furthermore, the air intake volume of the branched cooling channel is 20-50% of the air intake volume of the main cooling channel.

[0010] Furthermore, multiple branched cooling channels are arranged around the main cooling channel circumferentially.

[0011] Furthermore, the cold side wall is arranged parallel to the hot side wall, and the angle α between the main cooling channel and the hot side wall is 20~60°.

[0012] Furthermore, the aperture d of the branched cooling channel is less than or equal to the aperture D of the main cooling channel.

[0013] Furthermore, the aperture D of the main cooling channel ranges from 0.5 to 1 mm.

[0014] According to another aspect of the present invention, a flame tube is provided, comprising an outer ring and an inner ring, wherein the outer ring and / or the inner ring comprises the aforementioned radiating cooling structure.

[0015] According to another aspect of the invention, an aircraft engine is also provided, including the aforementioned flame tube.

[0016] The present invention has the following beneficial effects: In the divergent cooling structure of this invention, the outer cylindrical surface of the cooling ring is the cold side wall, and the inner cylindrical surface of the cooling ring is the hot side wall. An air intake structure is formed on the cooling ring, allowing high-pressure cooling airflow to pass through the cooling ring and enter the combustion gas side. The main cooling channel of the air intake structure is angled to the hot side wall, allowing the cooling airflow flowing out of the main cooling channel to independently form a cooling air film. When the main cooling channel of the air intake structure introduces high-pressure cooling airflow into the combustion gas side, the branched cooling channels can also introduce cooling airflow. Most of the cooling airflow flows through the main cooling channel, where rapid convective heat transfer carries away heat from the cooling ring. A small portion of the cooling airflow flows through the branched cooling channels, similarly carrying away heat from the cooling ring. The airflow in the cooling channel and the airflow in the bifurcated cooling channel converge on the cooling ring near the combustion chamber side. The two airflows collide violently and enhance convection, which can further improve the cooling efficiency and reduce the outlet airflow velocity of the main cooling channel. The cold air has a wall-adhering effect, which prevents the airflow from penetrating too deeply into the combustion chamber side and participating in the mainstream combustion zone. This ensures that the airflow with reduced velocity can form a wall-adhering, highly efficient cooling air film when it enters the combustion chamber side. The divergent cooling structure further reduces the wall temperature gradient of the cooling ring through the bifurcated cooling channels and slows down the airflow at the outlet of the main cooling channel. This can reduce the temperature stress of the cooling ring and thus extend the life of the combustor. It is particularly suitable for the combustion chamber of aero-engines that require low NOx emissions and long service life.

[0017] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of an existing divergent cooling structure; Figure 2 This is a schematic diagram of the divergent cooling structure according to a preferred embodiment of the present invention; Figure 3 This is one of the structural schematic diagrams of the cooling ring in a preferred embodiment of the present invention; Figure 4 yes Figure 3 The diagram shown is a structural schematic of the main cooling channel of a preferred embodiment of the present invention. Figure 5 yes Figure 4 The AA-direction sectional view shown; Figure 6 This is a second schematic diagram of the cooling ring structure according to a preferred embodiment of the present invention; Figure 7 yes Figure 6The diagram shown is a structural schematic of the main cooling channel of a preferred embodiment of the present invention. Figure 8 yes Figure 7 The BB-direction sectional view shown; Figure 9 This is a schematic diagram of the structure of the flame tube according to a preferred embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of an aero-engine according to a preferred embodiment of the present invention.

[0019] Legend: 1. Cooling ring; 11. Cold side wall; 12. Hot side wall; 2. Intake structure; 21. Main cooling passage; 22. Branch cooling passage; 221. Intake section; 223. Exit section; 222. Transition section; 100. Outer ring of the flame tube; 200. Inner ring of the flame tube; 300. Fuel nozzle; 400. Combustion chamber casing. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, and back), the orientation or positional relationship of the directional indications is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the embodiments according to this application and simplifying the description, and is not intended to indicate or imply that the device or unit referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments according to this application.

[0022] Furthermore, if the embodiments of this invention involve descriptions using terms such as "first," "second," and "third," these terms are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," or "third" may explicitly or implicitly include at least one of those features. The term "multiple" refers to two or more unless otherwise explicitly defined. Terms such as "installed," "connected," "attached," and "fixed" should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "attached" can be a direct connection or an indirect connection through an intermediate medium.

[0023] If the words "and / or" or "and / or" appear in the text, they mean three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution that satisfies both A and B. In addition, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] To better understand the above technical solution, the following detailed explanation is provided in conjunction with the accompanying drawings.

[0025] like Figures 1 to 8 As shown, the divergent cooling structure of this embodiment includes a cooling ring 1 for enclosing and forming a flame tube. The cooling ring 1 has an air intake structure 2 for introducing cooling airflow into the flame tube. The air intake structure 2 includes a main cooling channel 21 for introducing cooling airflow into the flame tube and a branched cooling channel 22 for introducing cooling airflow to reduce the outlet airflow velocity of the main cooling channel 21. The main cooling channel 21 connects the cold side wall 11 and the hot side wall 12 of the cooling ring 1, and the main cooling channel 21 is set at an angle to the hot side wall 12. The first end of the branched cooling channel 22 is connected to the end of the main cooling channel 21 near the hot side wall 12. The second end of the branched cooling channel 22 is connected to the end of the main cooling channel 21 near the cold side wall 11, or the second end of the branched cooling channel 22 is connected to the cold side wall 11.

[0026] In this embodiment of the divergent cooling structure, the outer cylindrical surface of the cooling ring 1 is the cold side wall 11, and the inner cylindrical surface of the cooling ring 1 is the hot side wall 12. The air intake structure 2 is located on the cooling ring 1, allowing high-pressure cooling airflow to pass through the cooling ring 1 and enter the combustion gas side. The main cooling channel 21 of the air intake structure 2 is angled to the hot side wall 12, allowing the cooling airflow flowing out of the main cooling channel 21 to independently form a cooling air film. When the main cooling channel 21 of the air intake structure 2 introduces high-pressure cooling airflow into the combustion gas side, the branched cooling channel 22 can also introduce cooling airflow. Most of the cooling airflow flows through the main cooling channel 21, where rapid convective heat transfer carries away the heat from the cooling ring 1. A small portion of the cooling airflow flows through the branched cooling channel 22, similarly carrying away the heat from the cooling ring 1. Heat is generated when the airflow in the main cooling channel 21 and the airflow in the branched cooling channel 22 converge on the cooling ring 1 near the combustion chamber side. The two airflows collide violently and enhance convection, which can further improve the cooling efficiency and reduce the outlet airflow velocity of the main cooling channel 21. The cold air has a wall-adhering effect, preventing the airflow from penetrating too deeply into the combustion chamber side and participating in the mainstream combustion zone. This ensures that the airflow with reduced velocity can form a wall-adhering, highly efficient cooling film when it enters the combustion chamber side. The divergent cooling structure of this embodiment further reduces the wall temperature gradient of the cooling ring 1 through the branched cooling channel 22 and decelerates the outlet airflow of the main cooling channel 21, which can reduce the temperature stress of the cooling ring 1, thereby extending the life of the flame tube. It is particularly suitable for the combustion chamber of aero-engines that require low NOx emissions and long life. Optionally, such as Figure 3 As shown, the second end of the bifurcated cooling channel 22 is connected to one end of the main cooling channel 21 near the cold side wall 11. The bifurcated cooling channel 22 draws air from the main cooling channel 21. This structure has little impact on the structural strength of the cooling ring 1 and requires 3D printing. Optionally, as... Figure 6 As shown, the second end of the bifurcated cooling channel 22 is connected to the cold side wall 11. The bifurcated cooling channel 22 draws air from the cold air side. Its structure is simple and can be machined, but it has a significant impact on the structural strength of the cooling ring 1.

[0027] like Figure 3 , Figure 4 and Figure 5As shown, in this embodiment, the bifurcated cooling channel 22 includes an air inlet section 221 connected to one end of the main cooling channel 21 near the cold side wall 11, an air outlet section 223 connected to one end of the main cooling channel 21 near the hot side wall 12, and a transition section 222 for connecting the air inlet section 221 and the air outlet section 223. The transition section 222 is arc-shaped. The bifurcated cooling channel 22 is opened inside the cooling ring 1. The cooling ring 1 does not need to open an air inlet hole for the bifurcated cooling channel 22. The air inlet section 221 draws air from the main cooling channel 21, and the arc-shaped transition section 222 guides the airflow along the outlet section 223. The ejection of air section 223 reduces the velocity loss of the cooling airflow in the bifurcated cooling channel 22, causing the cooling airflow ejected from the outlet section 223 in the main cooling channel 21 to collide violently and enhance convection, thereby reducing the velocity of the airflow at the outlet of the main cooling channel 21 and preventing the airflow from penetrating too deeply into the combustion side and participating in the mainstream combustion zone. Due to the repeated starting and stopping of the engine, the flame tube undergoes fatigue cycles. Too many openings on the cooling ring 1 will affect its own strength and reduce its service life. However, opening the bifurcated cooling channel 22 inside the cooling ring 1 can avoid the influence of the intake structure 2 on the strength of the cooling ring 1 and ensure the service life of the cooling ring 1.

[0028] like Figure 6 , Figure 7 and Figure 8 As shown, in this embodiment, the bifurcated cooling channel 22 includes an air inlet section 221 communicating with the cold side wall 11, an air outlet section 223 communicating with one end of the main cooling channel 21 near the hot side wall 12, and a transition section 222 for connecting the air inlet section 221 and the air outlet section 223. The transition section 222 is arc-shaped. The bifurcated cooling channel 22 is opened inside the cooling ring 1, and the air inlet of the bifurcated cooling channel 22 is opened on the cold side wall 11 of the cooling ring 1. The air inlet section 221 draws air from the cold side, and the arc-shaped transition section 222 guides the air. The airflow is ejected from the outlet section 223, which reduces the velocity loss of the cooling airflow in the bifurcated cooling channel 22. This causes the cooling airflow ejected from the outlet section 223 in the main cooling channel 21 to collide violently and enhance convection, thereby reducing the velocity of the airflow at the outlet of the main cooling channel 21 and preventing the airflow from penetrating too deeply into the combustion chamber and participating in the mainstream combustion zone. Since the bifurcated cooling channel 22 and the main cooling channel 21 have separate air intakes, the design difficulty can be reduced and the air volume ratio between the bifurcated cooling channel 22 and the main cooling channel 21 can be precisely controlled, thereby ensuring that the velocity of the airflow at the outlet of the main cooling channel 21 meets the design requirements.

[0029] like Figure 3 and Figure 6As shown, in this embodiment, the angle θ between the air outlet section 223 and the main cooling channel 21 is 120~165°; when θ < 120°, the cooling airflow at the outlet of the main cooling channel 21 has poor adhesion to the wall, making it difficult to form a wall-adhering, high-efficiency cooling air film; when θ > 165°, the processing is difficult and it is hard to guarantee the processing accuracy.

[0030] In this embodiment, the air intake volume of the branched cooling channel 22 is 20-50% of the air intake volume of the main cooling channel 21. When the air intake volume of the branched cooling channel 22 is greater than 50% of the air intake volume of the main cooling channel, the cooling airflow velocity ejected from the outlet of the main cooling channel 21 is very low, and its axial velocity (parallel to the high-temperature combustion gas velocity) is also very small. The cooling air film formed by the cooling air has a low flow velocity and can only cover a very short section of the flame tube wall, which is insufficient to support the cooling airflow outlet of the next main cooling channel 21. When the air intake volume of the branched cooling channel 22 is less than 20% of the air intake volume of the main cooling channel... At this time, the cooling airflow velocity exiting the main cooling channel 21 is very high, and its normal component velocity (perpendicular to the high-temperature combustion gas velocity) is also very large. The cooling airflow mixes with the high-temperature combustion gas, causing the cooling gas temperature to rise rapidly and its quality to decline rapidly, resulting in poor overall cooling performance. Numerical simulation analysis shows that when the intake volume of the branch cooling channel 22 is 20% to 50% of the intake volume of the main cooling channel 21, the airflow at the exit of the main cooling channel 21 has sufficient axial velocity to ensure the length of the cooling gas film, while the normal component velocity is sufficiently small to ensure that the cooling gas quality does not decline too quickly. Optionally, the intake volume of the branch cooling channel 22 is 35% of the intake volume of the main cooling channel 21.

[0031] like Figure 4 and Figure 7 As shown, in this embodiment, multiple branched cooling channels 22 are arranged around the main cooling channel 21 in the circumference. By adjusting the aperture and number of the branched cooling channels 22, the cooling speed at the outlet of the main cooling channel 21 can be guaranteed to meet the design requirements while minimizing the impact on the strength of the cooling ring 1.

[0032] like Figure 2 As shown, in this embodiment, the cold side wall 11 and the hot side wall 12 are arranged in parallel, and the angle α between the main cooling channel 21 and the hot side wall 12 is 20~60°. When α < 20°, the processing is difficult and it is hard to guarantee the processing accuracy. When α > 60°, the normal velocity of the cooling airflow coming out of the main cooling channel 21 is very high. The cooling airflow mixes with the high temperature gas for heat exchange, and the temperature of the cooling airflow will rise rapidly, losing its cooling effect and failing to provide good cooling for the wall between the cooling air outlets.

[0033] In this embodiment, the aperture d of the branched cooling channel 22 is less than or equal to the aperture D of the main cooling channel 21. When the aperture d of the branched cooling channel 22 is greater than the aperture D of the main cooling channel 21, the amount of cooling air introduced by the branched cooling channel 22 is too large, which will result in insufficient cooling air ejected from the outlet of the main cooling channel 21.

[0034] In this embodiment, the aperture D of the main cooling channel 21 ranges from 0.5 to 1 mm. The aperture D of the main cooling channel 21 cannot be less than 0.5 mm. The material of the flame tube is usually a high-temperature alloy. It is necessary to ensure both the roundness of the opening and the roughness of the hole wall. Using existing machining methods, a diameter of 0.5 mm is the machining limit. When the aperture D of the main cooling channel 21 is less than 0.5 mm, it is difficult to guarantee the machining accuracy. In the early design stage of the product, the total opening area of ​​the flame tube and the total opening area of ​​the cooling holes are determined. When the aperture D of the main cooling channel 21 is greater than 1 mm, the opening area of ​​a single cooling hole is larger, and the number of holes will be drastically reduced (the area is proportional to the square of the aperture). This will result in a larger distance between the holes, causing a larger temperature gradient between the walls of the holes, resulting in greater temperature stress and greatly shortening the life of the flame tube. This is inconsistent with the design concept of radiative cooling through a dense arrangement of a large number of small-diameter holes, forming a pattern similar to the numerous tiny pores on the surface of human skin that regulate body temperature through sweating.

[0035] like Figure 9 As shown, a flame tube includes an outer ring 100 and an inner ring 200. The outer ring 100 and / or the inner ring 200 include the aforementioned divergent cooling structure. The outer ring 100 and / or the inner ring 200 include multiple cooling rings 1. The outer ring 100 and the inner ring 200 are connected through a flame tube head. The outer ring 100, the inner ring 200, and the flame tube head form a flame tube flow channel. A fuel nozzle 300 is provided on the flame tube head. High-pressure air passing through the air intake structure 2 on the outer ring 100 and the inner ring 200 can reduce the amount of cooling air entering the mainstream combustion zone, independently form a cooling gas film, and extend the length of the cooling gas film, thereby reducing the temperature gradient of the cooling ring wall, reducing the temperature stress of the cooling ring, protecting the flame tube from ablation, and extending the flame tube life.

[0036] like Figure 10As shown, an aero-engine includes the aforementioned flame tube, which is installed in the combustion chamber casing 400 of the aero-engine. The outer ring 100 and / or the inner ring 200 of the flame tube include multiple cooling rings 1. The outer ring 100 and the inner ring 200 are connected through a flame tube head. The outer ring 100, the inner ring 200, and the flame tube head form a flame tube flow channel. A fuel nozzle 300 is provided on the flame tube head. High-pressure air compressed by the compressor enters the flame tube flow channel through the air intake structure 2 on the cooling ring 1. The flame tube flow channel includes a main combustion zone, an intermediate zone, and a mixing zone along the airflow direction. Fuel enters the flame tube flow channel through the fuel nozzle 300 and mixes with... High-pressure air mixes and burns within the flame tube's flow channel, forming high-temperature, high-pressure combustion gas. Air entering through the main and secondary mixing holes rapidly quenches the mixed high-temperature, high-pressure combustion gas. The high-temperature gas, with a suitable temperature distribution, then enters the turbine, driving it to perform work. Simultaneously, because the flame temperature of aviation kerosene combustion can reach over 2000K, a portion of the high-pressure air, through the intake structures 2 on the outer ring 100 and inner ring 200 of the flame tube, reduces the amount of cooling air entering the main combustion zone, independently forming a cooling gas film and extending its length. This reduces the temperature gradient of the cooling ring wall, decreases the temperature stress on the cooling ring, protects the flame tube from ablation, and extends its lifespan. It is understandable that the flame tube can also be installed in the combustion chamber of a gas turbine.

[0037] In the engineering design of the flame tube of a high-temperature combustion chamber for an aero-engine, the following three schemes were compared: Option 1: Conventional film cooling + radiative cooling (e.g., Figure 1 (Existing divergent cooling structure shown). Option 2: The air intake of the branched cooling channel 22 originates from the reverse countercurrent cooling of the main cooling channel 21 (e.g., Figure 3 (as shown) Option 3: The air intake of the bifurcated cooling channel 22 originates from the reverse counter-current cooling of the cold air side (e.g., Figure 6 (as shown) In all three schemes, the orifice diameter D of the main cooling channel 21 and the orifice diameter d of the branched cooling channel 22 are both 0.7 mm. In Scheme 2, the airflow angle θ1 between the branched cooling channel 22 and the main cooling channel 21 is 150°; in Scheme 3, the airflow angle θ2 between the branched cooling channel 22 and the main cooling channel 21 is 155°. With a combustion chamber inlet temperature of 700 K, a combustion gas temperature of 1890 K, and a consistent total cooling gas volume across the three schemes, the average wall temperature is 980 K in Scheme 1, 910 K in Scheme 2, and 902 K in Scheme 3. Therefore, Schemes 2 and 3 show significantly better cooling performance than the conventional schemes.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A divergent cooling structure, characterized in that, It includes a cooling ring (1) for enclosing and forming a flame tube, and an air intake structure (2) for introducing cooling airflow into the flame tube is provided on the cooling ring (1). The air intake structure (2) includes a main cooling channel (21) for introducing cooling airflow into the flame tube and a branched cooling channel (22) for introducing cooling airflow to reduce the airflow velocity at the outlet of the main cooling channel (21). The main cooling channel (21) connects the cold side wall (11) and the hot side wall (12) of the cooling ring (1), and the main cooling channel (21) and the hot side wall (12) are arranged at an angle. The first end of the branched cooling channel (22) is connected to the end of the main cooling channel (21) near the hot side wall (12). The second end of the bifurcated cooling channel (22) is connected to the end of the main cooling channel (21) near the cold side wall (11), or the second end of the bifurcated cooling channel (22) is connected to the cold side wall (11).

2. The divergent cooling structure as described in claim 1, characterized in that, The bifurcated cooling channel (22) includes an air intake section (221) that is connected to one end of the main cooling channel (21) near the cold side wall (11) or to the cold side wall (11), an air outlet section (223) that is connected to one end of the main cooling channel (21) near the hot side wall (12), and a transition section (222) for connecting the air intake section (221) and the air outlet section (223), wherein the transition section (222) is arc-shaped.

3. The divergent cooling structure as described in claim 2, characterized in that, The angle θ between the air outlet section (223) and the main cooling channel (21) is 120~165°.

4. The divergent cooling structure as described in claim 1, characterized in that, The air intake of the branched cooling channel (22) is 20-50% of the air intake of the main cooling channel (21).

5. The divergent cooling structure as described in claim 1, characterized in that, Multiple branched cooling channels (22) are arranged around the main cooling channel (21) circumferentially.

6. The divergent cooling structure as described in claim 1, characterized in that, The cold side wall (11) is arranged parallel to the hot side wall (12), and the angle α between the main cooling channel (21) and the hot side wall (12) is 20~60°.

7. The divergent cooling structure as described in claim 1, characterized in that, The aperture d of the branched cooling channel (22) is less than or equal to the aperture D of the main cooling channel (21).

8. The divergent cooling structure as described in claim 1, characterized in that, The aperture D of the main cooling channel (21) ranges from 0.5 to 1 mm.

9. A flame tube, comprising an outer ring (100) and an inner ring (200), characterized in that, The outer ring (100) of the flame tube and / or the inner ring (200) of the flame tube include a radiating cooling structure as described in any one of claims 1 to 8.

10. An aircraft engine, characterized in that, Includes the flame tube as described in claim 9.

Images