Low pollution combustion chamber and aircraft engine

Abstract

The application discloses a low-pollution combustion chamber and an aero-engine, wherein the outer ring of a flame tube and the inner ring of the flame tube are provided with mixing holes correspondingly, a combustion cavity forms a quenching mixing area along the axial direction of the combustion cavity corresponding to the space of the mixing holes, and the combustion cavity forms an oil-rich combustion area on one side of the quenching mixing area close to the head of the flame tube and an oil-lean combustion area on the other side of the quenching mixing area away from the head of the flame tube; the outer ring of the flame tube and the inner ring of the flame tube are both bent towards the combustion cavity at the position of the oil-rich combustion area close to the quenching mixing area, so that the combustion cavity forms a contraction cavity body at the quenching mixing area and the oil-lean combustion area. The application adopts a fast contraction profile design for the structure of the flame tube, so as to shorten the radial distance between the mixing holes of the outer ring of the flame tube and the inner ring of the flame tube, improve the mixing jet efficiency, make the gas in the oil-rich combustion area switch to the oil-lean combustion area quickly, realize low-pollution emission of the combustion chamber, and meet the requirement of high-quality temperature distribution at the outlet of the combustion cavity.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and in particular, to a low-emission combustor. Furthermore, it relates to an aero-engine employing this low-emission combustor. Background Technology

[0002] The combustion chamber is one of the core components of an aero-engine / gas turbine. Its function is to burn fuel, converting the chemical energy in the fuel into thermal energy, increasing the total enthalpy of the air entering the combustion chamber, and driving the gas turbine to do work. Its design directly affects the efficiency and emissions of the aero-engine or gas turbine. One of the main development directions for modern civil aero-engine combustion chambers is low-emission combustion to meet increasingly stringent emission standards for aero-engines.

[0003] The currently employed RQL (Rich Burn-Quench-Lean Burn) combustion technology is one of the key technologies for low-emission combustion. Its main principle is staged air combustion: the main combustion zone is a rich fuel combustion zone, the middle zone is a quenched mixing zone, and the rear zone is a lean fuel combustion zone. RQL combustion technology reduces NOx content and achieves low emissions from the combustion chamber by lowering the temperature of the combustion zone and ensuring a uniform temperature field—that is, by controlling the overall and local equivalence ratio. Without increasing the complexity of the combustion chamber, the RQL combustion chamber can effectively avoid the problems of excessively complex flame tubes and fuel supply systems, and can reduce pollution emission levels to a certain extent.

[0004] RQL combustors typically employ film cooling or divergent cooling to reduce the flame tube wall temperature. However, in the rich-fuel combustion zone, the cooling gas often participates in combustion, creating a series of stoichiometric combustion zones, limiting the potential for emission reduction. In the quenching and mixing zone, single-row or double-row mixing holes are usually installed. Cooling gas is injected into the flame tube through these holes to reduce the gas temperature gradient and improve gas homogeneity, achieving the transition from rich-fuel to lean-fuel combustion. However, single-row mixing holes cannot adjust the gas temperature gradient, leading to difficulties in controlling the outlet temperature distribution. Double-row mixing holes result in a large quenching zone volume, causing long gas residence times and conversion times, creating a contradiction between low NOx emissions and a high-quality outlet temperature distribution in the combustor. Furthermore, existing RQL combustors typically have large flame tube volumes and significant radial height differences between the inner and outer rings, resulting in large jet depths in the mixing holes of the quenching and mixing zone, making it difficult to cut off high-temperature gas and extending the gas conversion time. Summary of the Invention

[0005] This invention provides a low-pollution combustion chamber to solve the technical problem of the contradiction between low NOx emissions and high-quality outlet temperature distribution in the existing RQL combustion chamber.

[0006] According to one aspect of the present invention, a low-emission combustion chamber is provided, comprising a combustion chamber casing and a flame tube disposed within the combustion chamber casing. The flame tube includes a flame tube head disposed at the inlet end of the combustion chamber, an outer ring of the flame tube connected to the outer wall of the flame tube head, and an inner ring of the flame tube connected to the inner wall of the flame tube head. The flow channel between the outer ring and the inner ring of the flame tube constitutes the combustion chamber.

[0007] The outer ring and inner ring of the flame tube are respectively provided with mixing holes. The space corresponding to the mixing holes along the axial direction of the combustion chamber forms a quenching mixing zone. The combustion chamber forms a rich combustion zone on the side of the quenching mixing zone close to the head of the flame tube and a lean combustion zone on the side of the quenching mixing zone away from the head of the flame tube.

[0008] Both the outer and inner rings of the flame tube bend towards the inside of the combustion chamber at positions near the quenching and mixing zone in the rich-oil combustion zone, so that the combustion chamber forms a contracting cavity in the quenching and mixing zone and the lean-oil combustion zone.

[0009] Furthermore, the mixing holes include main mixing holes and secondary mixing holes spaced apart along the axial direction of the combustion chamber. The main mixing holes and secondary mixing holes are respectively provided on the outer ring and inner ring of the flame tube, and the main mixing holes are located on the side of the quenching mixing zone close to the oil-rich combustion zone.

[0010] Both main mixing holes and secondary mixing holes are provided in multiples on the outer and inner rings of the flame tube, with the number of main mixing holes being less than the number of secondary mixing holes.

[0011] Furthermore, the diameter of the primary mixing pore is larger than that of the secondary mixing pore.

[0012] Furthermore, the axial spacing between the main mixing hole and the secondary mixing hole is less than 1.5 times the sum of the diameters of the main mixing hole and the secondary mixing hole.

[0013] Furthermore, both the outer ring and inner ring of the flame tube include a front straight section connected to the head of the flame tube and a contraction section connected to the front straight section in the oil-rich combustion zone. The contraction section is arranged to contract in the direction toward the quenching and mixing zone. The front straight section is provided with gas film cooling holes and impact cooling holes, and the contraction section is provided with divergent cooling holes.

[0014] An air film tongue is fixed on the inner wall of the front straight section. The air film tongue extends from the front straight section to the contraction section and has a gap relative to the contraction section. The impact cooling hole is used to introduce cooling airflow toward the surface of the air film tongue. The air film cooling hole is used to introduce cooling airflow along the extension direction of the air film tongue. The air film tongue is used to guide the cooling airflow introduced by the air film cooling hole and the impact cooling hole to form a wall-adhering air film that conforms to the flow of the contraction section.

[0015] Furthermore, both the outer and inner rings of the flame tube include a first straight section connected to the contraction section in the quenching mixing zone, with the main mixing hole and the secondary mixing hole opened on the first straight section.

[0016] Furthermore, both the outer and inner rings of the flame tube include a second straight section connected to the end of the first straight section away from the head of the flame tube and a rear straight section connected to the end of the combustion chamber casing away from the head of the flame tube in the lean combustion zone. The second straight section and the rear straight section are connected by a bent section to form a Z-shaped structure.

[0017] The second straight section is provided with radiating cooling holes, and the bent section is provided with Z-shaped ring cooling holes.

[0018] Furthermore, the combustion chamber casing includes an outer combustion chamber casing connected to the outer ring of the flame tube and an inner combustion chamber casing connected to the inner ring of the flame tube, wherein the outer combustion chamber casing is configured with a corresponding concave structure for the contraction cavity of the combustion chamber.

[0019] Furthermore, the flame tube also includes a vortex generator connected to the head of the flame tube. A guide plate is connected to the vortex generator. The guide plate is located inside the combustion chamber and extends toward the inner wall of the flame tube to form a recirculation zone with the vortex generator at the head of the flame tube.

[0020] According to another aspect of the invention, an aircraft engine employing this low-emission combustion chamber is also provided.

[0021] The present invention has the following beneficial effects:

[0022] The low-pollution combustion chamber of this invention forms a quenched mixing zone within the combustion chamber by setting mixing holes on the outer and inner rings of the flame tube. Furthermore, a rich-fuel combustion zone and a lean-fuel combustion zone are formed on either side of the quenched mixing zone within the combustion chamber, respectively. This allows for staged combustion of the fuel gas within the combustion chamber using RQL combustion technology. By reducing the temperature of the combustion zone and ensuring a uniform temperature field, NOx content is reduced, achieving low-pollution emissions from the combustion chamber and avoiding the problems associated with an excessively complex flame tube and fuel supply system. By bending the outer and inner rings of the flame tube in the rich combustion zone towards the interior of the combustion chamber at the ends near the quenching mixing zone, the flame tube as a whole forms a concave structure. The aperture of the combustion chamber rapidly contracts from the rich combustion zone towards the quenching mixing zone, reducing the radial height difference between the mixing holes on the outer and inner rings of the flame tube in the quenching mixing zone. This shortens the time for the jet to be cut off through the mixing holes, and the smaller jet depth allows the mixed gas flow to fully mix with the high-temperature gas in a very short time for complete combustion, resulting in high combustion efficiency. This effectively shortens the residence time of the gas in the quenching mixing zone, allowing the gas in the rich combustion zone to quickly switch to the lean combustion zone. In addition, with the combustion equivalence ratio strictly controlled within a certain range, NOx emissions from the combustion chamber can be greatly reduced. At the same time, the mixing holes can also be used to regulate the outlet temperature distribution of the lean combustion zone, ensuring that the outlet gas temperature distribution meets the turbine power requirements and ensuring the stability of the aero-engine combustion chamber. This allows the combustion chamber to simultaneously achieve low NOx emissions and high-quality outlet temperature distribution. Preferably, the low-pollution combustion chamber is equipped with a structure for guiding the cooling airflow to adhere to the wall at the same time as the flame in the rich fuel combustion zone, so as to prevent the cooling air from entering the rich fuel combustion zone to participate in combustion, prevent the formation of a large number of local chemically appropriate combustion zones in the rich fuel combustion zone, and further improve the low-pollution performance of the combustion chamber.

[0023] 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

[0024] 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:

[0025] Figure 1 This is a schematic diagram of the structure of the low-pollution combustion chamber of a preferred embodiment of the present invention.

[0026] Legend:

[0027] 10. Combustion chamber outer casing; 20. Combustion chamber inner casing; 30. Flame tube head; 40. Flame tube outer ring; 50. Flame tube inner ring; 60. Swirler; 70. Diffuser; 80. Rich combustion zone; 81. First front straight section; 82. Connecting section; 821. Film cooling hole; 83. Second front straight section; 831. Impingement cooling hole; 84. Contraction section; 841. Diverging cooling hole; 85. Film cooling tongue; 90. Quenching and mixing zone; 91. First middle straight section; 911. Main mixing hole; 912. Secondary mixing hole; 100. Lean combustion zone; 101. Second middle straight section; 102. Rear straight section; 103. Bend section; 1031. Z-ring cooling hole; 110. Guide plate; 120. Rotating shaft. Detailed Implementation

[0028] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0029] like Figure 1 As shown, the low-emission combustion chamber of this embodiment is an annular combustion chamber arranged between the compressor and the turbine, and the annular combustion chamber rotates around the rotation axis 120. The low-emission combustion chamber includes a combustion chamber casing and a flame tube disposed within the combustion chamber casing. The flame tube includes a flame tube head 30, an outer flame tube ring 40 connected to the outer wall of the flame tube head 30, and an inner flame tube ring 50 connected to the inner wall of the flame tube head 30. The flow channel between the outer flame tube ring 40 and the inner flame tube ring 50 forms a combustion chamber for fuel combustion. The combustion chamber casing is connected to the diffuser 70, which is connected to the compressor to introduce the high-pressure air compressed by the compressor into the combustion chamber. The flame tube head 30 is located at the inlet end of the combustion chamber to connect with the fuel nozzle to introduce fuel into the combustion chamber. A vortex generator 60 connected to the flame tube head 30 forms a recirculation zone at the flame tube head, which mixes the fuel and high-pressure air and promotes fuel atomization. As a result, the fuel-air mixture burns stably in the combustion chamber, and the heat energy generated by the combustion is output towards the turbine at the outlet end of the combustion chamber to provide power for the rotation of the turbine. Specifically, the diffuser 70 introduces the high-pressure air compressed by the compressor into the area between the combustion chamber casing and the flame tube through the diffuser 70 channel. Subsequently, the high-pressure air enters the combustion chamber through the openings on the outer ring 40, inner ring 50, and head 30 of the flame tube. Fuel enters the combustion chamber through the fuel nozzle. The vortex generator 60 causes the incoming airflow to form a recirculation zone at the head 30 of the flame tube to promote thorough mixing of the airflow and the incoming fuel at the inlet end of the combustion chamber. When the combustion chamber is ignited, the ignition nozzle located at the inlet end of the combustion chamber ignites the mixed fuel-air mixture. The ignited fuel-air mixture forms a stable ignition source in the combustion chamber and flows from the inlet end to the outlet end. Then, the turbine at the outlet end of the combustion chamber converts the heat energy generated by the combustion of fuel in the combustion chamber into kinetic energy to do work on the turbine.

[0030] The outer ring 40 and inner ring 50 of the flame tube are respectively provided with mixing holes. The combustion chamber forms a quenched mixing zone 90 in the space corresponding to the mixing holes along its axial direction. A rich combustion zone 80 is formed on the side of the quenched mixing zone 90 near the head 30 of the flame tube, and a lean combustion zone 100 is formed on the side of the quenched mixing zone 90 away from the head of the flame tube. Thus, the rich combustion zone 80 at the inlet end of the combustion chamber constitutes the main combustion zone due to the high temperature, high oxygen, and high fuel oil environment. The quenched mixing zone 90 jets the fuel-air mixture flowing into the rich combustion zone 80 by introducing a high-speed cooling airflow into the mixing holes to cut off the high temperature gas and further mix the airflow. At the same time, it reduces the temperature gradient of the gas, so that the gas that meets the temperature field can enter the lean combustion zone 100 for combustion. Thus, by adopting RQL combustion technology to perform staged combustion of gas, low pollution emissions can be achieved. Both the outer ring 40 and inner ring 50 of the flame tube bend inwards towards the combustion chamber at positions near the quenching mixing zone 90 in the rich combustion zone 80. This causes the combustion chamber to form a contracting cavity in the quenching mixing zone 90 and the lean combustion zone 100. This rapid contraction profile design of the flame tube allows the aperture of the combustion chamber to contract rapidly from the rich combustion zone 80 towards the quenching mixing zone 90. This reduces the radial height difference between the mixing holes on the outer ring 40 and inner ring 50 at the quenching mixing zone 90, thus shortening the time it takes for the cooling airflow to enter the quenching mixing zone 90 and be intercepted. The smaller jet depth allows the mixed airflow to... Within a short time, the gas is fully mixed with the high-temperature combustion gas to ensure complete combustion, resulting in high combustion efficiency. This effectively shortens the residence time of the gas in the quenching and mixing zone 90, allowing the fuel-air mixture in the rich combustion zone 80 to be quickly switched to the lean combustion zone 100. In addition, the cooling airflow introduced into the quenching and mixing zone 90 meets the optimal range of combustion equivalence ratio, which can greatly reduce NOx emissions from the combustion chamber. At the same time, the design of the mixing orifice can also control the outlet temperature distribution of the lean combustion zone 100, ensuring that the gas temperature distribution at the outlet meets the turbine power requirements and ensuring the stability of the aero-engine combustion chamber. This allows the combustion chamber to achieve both low NOx emissions and high-quality outlet temperature distribution.

[0031] like Figure 1As shown, the mixing holes include a main mixing hole 911 and a secondary mixing hole 912 spaced apart along the axial direction of the combustion chamber. Both the main mixing hole 911 and the secondary mixing hole 912 are circumferentially opened on the outer ring 40 and the inner ring 50 of the flame tube. The main mixing hole 911 is located on the side of the quenching mixing zone 90 close to the oil-rich combustion zone 80. The combustion chamber between the main mixing hole 911 and the secondary mixing hole 912 forms the quenching mixing zone 90. By introducing a mixed cooling airflow into the main mixing hole 911 and the secondary mixing hole 912, the high-temperature combustion gas flowing into the quenching mixing zone 90 is jet-intercepted, and the mixed airflow is fully mixed with the high-temperature combustion gas to reduce its temperature gradient and adjust the temperature distribution at the combustion chamber outlet. Preferably, multiple main mixing holes 911 and multiple secondary mixing holes 912 are arranged circumferentially along the outer ring 40 and inner ring 50 of the flame tube, and the multiple main mixing holes 911 and multiple secondary mixing holes 912 are equidistant from each other. The number of main mixing holes 911 is less than the number of secondary mixing holes 912, and the aperture of the main mixing holes 911 is larger than the aperture of the secondary mixing holes 912. By adopting a design with a large aperture and a small number of main mixing holes 911, the high-temperature fuel gas flowing in from the rich combustion zone 80 can be efficiently cut off. The design with a small aperture and a large number of secondary mixing holes 912 can better adjust the temperature gradient, so that the temperature distribution coefficient at the outlet of the combustion chamber meets the requirements, thereby enabling the combustion chamber to achieve low NOx emissions and high-quality outlet temperature distribution.

[0032] like Figure 1 As shown, the axial distance between the main mixing hole 911 and the secondary mixing hole 912 is less than 1.5 times the sum of the diameters of the main mixing hole 911 and the secondary mixing hole 912. Therefore, by adopting an ultra-short distance symmetrical jet quenching design between the main mixing hole 911 and the secondary mixing hole 912, the mixing cooling airflow introduced into the main mixing hole 911 can efficiently intercept the high-temperature gas flowing into the quenching mixing zone 90, and then quickly adjust the temperature gradient of the gas through the secondary mixing hole 912 to meet the temperature field requirements of the lean combustion zone 100. This greatly shortens the residence time of the high-temperature gas in the quenching mixing zone 90, realizes the rapid conversion from the fuel gas mixture in the rich combustion zone 80 to the lean combustion zone 100, greatly improves the combustion efficiency, and achieves low pollution emissions from the combustion chamber.

[0033] like Figure 1As shown, both the outer ring 40 and the inner ring 50 of the flame tube include a front straight section and a contraction section 84 connected to the front straight section in the oil-rich combustion zone 80. Specifically, the front straight section includes a first front straight section 81, a second front straight section 83, and a connecting section 82 arranged between the first front straight section 81 and the second front straight section 83. The first front straight section 81 is connected to the flame tube head 30. The connecting section 82 is arranged in the radial direction away from the combustion chamber and is fixed to the first front straight section 81 and the second front straight section 83 respectively. The contraction section 84 is connected to the end of the second front straight section 83 away from the flame tube head 30. The contraction section 84 is contracted in the direction towards the quenching mixing zone 90.

[0034] A film cooling hole 821 is provided on the wall of the connecting section 82, and an impact cooling hole 831 is provided on the wall of the second front straight section 83, so that the second front straight section 83 introduces cooling airflow into the combustion chamber through the impact cooling hole 831, and the connecting section 82 introduces cooling airflow into the combustion chamber through the film cooling hole 821, so as to cool the wall of the flame tube. A film cooling tongue 85 is fixed to the inner wall of the front straight section. The film cooling tongue 85 is fixed to the inner wall of the connection between the first front straight section 81 and the connecting section 82 and extends from the second front straight section 83 to the contraction section 84. The film cooling tongue 85 has a gap relative to the contraction section 84, so that the cooling airflow introduced into the film cooling hole 821 of the connecting section 82 and the impact cooling hole 831 of the second front straight section 83 can be guided by the film cooling tongue 85 to form a wall-adhering film that fits the flow of the contraction section 84. By utilizing the wall-adhering effect generated by the contraction profile of the contraction section 84, the cooling effect on the flame tube wall is not only enhanced, but also the cooling gas in the entire fuel-rich combustion zone 80 is prevented from participating in combustion, thus reducing NOx emissions while ensuring efficient cooling. A divergent cooling hole 841 is opened on the wall of the contraction section 84, so that the flame tube is cooled in the fuel-rich combustion zone 80 by a combination of film cooling, impact cooling and divergent cooling, further enhancing the cooling effect.

[0035] like Figure 1As shown, both the outer ring 40 and the inner ring 50 of the flame tube include a first straight section 91 in the quenching mixing zone 90. The first straight section 91 is connected to the end of the contraction section 84 away from the head 30 of the flame tube. The main mixing hole 911 and the secondary mixing hole 912 are opened on the first straight section 91. This positions the quenching mixing zone 90 at the contraction point of the outer ring 40 and inner ring 50 of the flame tube. Consequently, the radial distance between the main mixing hole 911 and the secondary mixing hole 912 between the outer ring 40 and inner ring 50 of the flame tube is greatly shortened, reducing the jet depth of the mixed gas. This allows for rapid cutoff of the high-temperature combustion gas, enabling the low-temperature mixed air introduced into the mixing hole to mix rapidly and uniformly with the combustion products of the oil-rich combustion zone 80. This significantly shortens the residence time of the high-temperature combustion gas in the quenching mixing zone 90, improves combustion efficiency, and facilitates the rapid conversion of the combustion gas from the oil-rich combustion zone 80 to the oil-lean combustion zone 100. It also lowers the temperature of the combustion products and greatly reduces NOx production.

[0036] like Figure 1 As shown, both the outer ring 40 and inner ring 50 of the flame tube include a second straight section 101 connected to the first straight section 91, a rear straight section 102 located at the combustion chamber outlet, and a bent section 103 located between the second straight section 101 and the rear straight section 102 in the lean combustion zone 100. The bent section 103 extends radially outward from the combustion chamber and connects the second straight section 101 and the rear straight section 102, forming a Z-shaped structure. The second straight section 101 has a divergent cooling hole 841, and the bent section 103 has a Z-shaped ring cooling hole. Both the divergent cooling hole 841 and the Z-shaped ring cooling hole face towards the combustion chamber outlet. Therefore, by combining divergent cooling and Z-shaped ring cooling in the lean combustion zone 100, the walls of the outer ring 40 and inner ring 50 of the flame tube can be cooled. Furthermore, the Z-shaped structure allows the cooling airflow to achieve a specific flow velocity and pressure distribution as it passes through the Z-shaped ring cooling holes, forming a stable cooling gas film on the flame tube wall. This cooling gas film not only isolates the combustion gases in the lean combustion zone 100 from direct contact with the flame tube wall, reducing the wall temperature, but also carries away some heat through the airflow, thereby regulating the temperature distribution at the combustion chamber outlet to meet engine requirements. Preferably, the flow rate and velocity of the cooling airflow can be controlled by changing parameters such as the diameter, number, and distribution of the Z-shaped ring cooling holes, optimizing the temperature distribution at the combustion chamber outlet to meet the cooling requirements of the flame tube under different operating conditions.

[0037] like Figure 1As shown, the combustion chamber casing includes an outer combustion chamber casing 10 connected to the outer ring 40 of the flame tube and an inner combustion chamber casing 20 connected to the inner ring 50 of the flame tube. The outer combustion chamber casing 10 is designed with a concave structure corresponding to the shrinkage cavity of the combustion chamber, which can reduce the overall volume of the combustion chamber, greatly reduce the weight of the combustion chamber, improve the thrust-to-weight ratio of the aero-engine, and reduce energy consumption and emissions.

[0038] like Figure 1 As shown, a guide plate 110 is connected to the vortex generator 60. The guide plate 110 is located inside the combustion chamber and extends towards the walls of the outer ring 40 and inner ring 50 of the flame tube. The end of the guide plate 110 away from the vortex generator 60 extends towards the outlet end of the combustion chamber. Thus, the guide plate 110 can, on the one hand, isolate the high-temperature radiation of the rich combustion zone 80 and protect the wall of the flame tube head 30 from the direct impact and erosion of the high-temperature combustion gas. On the other hand, it can form a recirculation zone with the vortex generator 60 at the flame tube head 30, optimize the flow field characteristics in the combustion chamber, promote the atomization and mixing of fuel in the rich combustion zone 80, so as to form a stable flame in the rich combustion zone 80 and improve combustion efficiency and combustion stability.

[0039] In addition, the present invention also discloses an aircraft engine that includes the aforementioned low-emission combustion chamber.

[0040] 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 low-pollution combustion chamber, comprising a combustion chamber casing and a flame tube disposed within the combustion chamber casing, the flame tube comprising a flame tube head (30), an outer flame tube ring (40) connected to the outer wall of the flame tube head (30), and an inner flame tube ring (50) connected to the inner wall of the flame tube head (30), wherein a flow channel between the outer flame tube ring (40) and the inner flame tube ring (50) constitutes a combustion chamber, characterized in that, The outer ring (40) and inner ring (50) of the flame tube are respectively provided with mixing holes. The combustion chamber forms a quenching mixing zone (90) in the space corresponding to the mixing holes along its axial direction. The combustion chamber forms a rich combustion zone (80) on the side of the quenching mixing zone (90) close to the head (30) of the flame tube and a lean combustion zone (100) on the side of the quenching mixing zone (90) away from the head (30) of the flame tube. The outer ring (40) and the inner ring (50) of the flame tube are both bent toward the combustion chamber at the position of the rich oil combustion zone (80) near the quenching and mixing zone (90), so that the combustion chamber forms a contraction cavity in the quenching and mixing zone (90) and the lean oil combustion zone (100); Both the outer ring (40) and the inner ring (50) of the flame tube include a front straight section connected to the head (30) of the flame tube and a converging section (84) connected to the front straight section in the oil-rich combustion zone (80). The converging section (84) is arranged to contract in the direction toward the quenching mixing zone (90). The front straight section is provided with a gas film cooling hole (821) and an impact cooling hole (831). The converging section (84) is provided with a diverging cooling hole (841). An air film tongue (85) is fixed on the inner wall of the front straight section. The air film tongue (85) extends from the front straight section to the contraction section (84) and has a gap relative to the contraction section (84). The impact cooling hole (831) is used to introduce cooling airflow toward the surface of the air film tongue (85). The air film cooling hole (821) is used to introduce cooling airflow along the extension direction of the air film tongue (85). The air film tongue (85) is used to guide the cooling airflow introduced by the air film cooling hole (821) and the impact cooling hole (831) to form a wall-adhering air film that flows in accordance with the contraction section (84).

2. The low-pollution combustion chamber according to claim 1, characterized in that, The mixing holes include a main mixing hole (911) and a secondary mixing hole (912) spaced apart along the axial direction of the combustion chamber. The main mixing hole (911) and the secondary mixing hole (912) are respectively provided on the outer ring (40) and the inner ring (50) of the flame tube, and the main mixing hole (911) is provided on the side of the quenching mixing zone (90) close to the oil-rich combustion zone (80). Both the main mixing hole (911) and the secondary mixing hole (912) are provided in multiples on the outer ring (40) and the inner ring (50) of the flame tube, and the number of the main mixing hole (911) is less than the number of the secondary mixing hole (912).

3. The low-pollution combustion chamber according to claim 2, characterized in that, The diameter of the main mixing hole (911) is larger than the diameter of the secondary mixing hole (912).

4. The low-pollution combustion chamber according to claim 2, characterized in that, The axial distance between the main mixing hole (911) and the secondary mixing hole (912) is less than 1.5 times the sum of the diameters of the main mixing hole (911) and the secondary mixing hole (912).

5. The low-pollution combustion chamber according to claim 2, characterized in that, Both the outer ring (40) and the inner ring (50) of the flame tube include a first straight section (91) connected to the contraction section (84) in the quenching mixing zone (90), and the main mixing hole (911) and the secondary mixing hole (912) are opened on the first straight section (91).

6. The low-pollution combustion chamber according to claim 5, characterized in that, Both the outer ring (40) and the inner ring (50) of the flame tube include a second straight section (101) connected to the end of the first straight section (91) away from the head (30) of the flame tube, and a rear straight section (102) connected to the end of the combustion chamber casing away from the head (30) of the flame tube in the lean combustion zone (100). The second straight section (101) and the rear straight section (102) are connected by a bent section (103) to form a Z-shaped structure. The second straight section (101) is provided with a diverging cooling hole (841), and the bent section (103) is provided with a Z-shaped ring cooling hole.

7. The low-pollution combustion chamber according to claim 1, characterized in that, The combustion chamber casing includes an outer combustion chamber casing (10) connected to the outer ring (40) of the flame tube and an inner combustion chamber casing (20) connected to the inner ring (50) of the flame tube. The outer combustion chamber casing (10) is configured with a concave structure corresponding to the contraction cavity of the combustion chamber.

8. The low-pollution combustion chamber according to claim 1, characterized in that, The flame tube also includes a vortex generator (60) connected to the flame tube head (30), and a guide plate (110) is connected to the vortex generator (60). The guide plate (110) is located in the combustion chamber and extends toward the inner wall of the flame tube, and is used to form a recirculation zone with the vortex generator (60) at the flame tube head (30).

9. An aircraft engine, characterized in that, Includes the low-pollution combustion chamber as described in any one of claims 1 to 8.

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