A regenerative combustion chamber provided with a gas film cooling large bend mechanism

Abstract

The present application relates to the technical field of small aero-engine combustion chamber, and particularly relates to a backflow combustion chamber provided with a film cooling large elbow mechanism. The backflow combustion chamber comprises a diffuser, a casing, a flame tube, a turbine guide vane and a fuel nozzle. The diffuser is provided with a large elbow corresponding to the flame tube. A small elbow is arranged between the casing and the flame tube. The large elbow is designed in a split type and combined with the film cooling technology. The film holes are arranged on the large elbow. The continuous film cover is formed on the surface of the large elbow. The cooling efficiency is not less than 80%. The wall temperature of the large elbow can be significantly reduced, and the service life of the engine is improved. The large elbow and the outer ring flame tube are overlapped to realize load sharing, uniform stress release, avoid local stress concentration and cause structural deformation or damage. The large elbow and the turbine guide vane are designed in a structure of radial overlap and axial gap to realize high-precision cooperation and assist the large elbow to release stress.

Description

Technical Field

[0001] This invention relates to the field of small aircraft engine combustion chamber technology. Background Technology

[0002] In recent years, with the rapid advancement of science and technology, breakthroughs in the performance of military aero engines have mainly focused on high thrust-to-weight ratio, low fuel consumption, and long service life. To achieve these goals, two methods are often employed: increasing the compressor pressure ratio and raising the combustion chamber temperature. This further increases the aerodynamic and thermal loads on the main combustion chamber flame tube of the aero engine, creating a contradiction between high load and long service life in flame tube design. In small and medium-sized aero engines, recirculating combustion chambers are mostly used, which have advantages such as compact structure, short engine shaft system, and favorable overall rotor dynamics design. However, they also have disadvantages such as large flame tube cooling area, uneven pressure difference distribution between inner and outer rings, and difficulty in designing cooling structures. As a key component of the recirculation combustion chamber, the large bend tube is subjected to the impact of airflows flowing in opposite directions. When the engine boost ratio and temperature rise further increase, the load on the large bend tube increases sharply, making it prone to deformation, cracks, and ablation, which affects the engine's lifespan. At the same time, traditional large bend tubes are often assembled into a single unit with the flame tube assembly by welding or bolting. This presents two prominent challenges: first, when the large bend tube faces high loads, it cannot release stress through sufficient expansion, resulting in significant deformation; second, once the large bend tube is damaged, it is difficult to disassemble and repair, and the replacement cost is high. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a recirculation combustion chamber equipped with a large bend mechanism with air film cooling. It adopts full-coverage air film cooling technology combined with separate manufacturing of the large bend and the flame tube, which not only provides efficient cooling protection for the large bend and improves its service life, but also simplifies the installation and replacement procedure of the large bend on the whole machine and improves its sealing effect.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a recirculation combustion chamber equipped with a film cooling large bend tube mechanism, characterized in that it includes a diffuser, a casing, a flame tube, a turbine guide, and a fuel nozzle, a large bend tube is provided after the diffuser corresponding to the flame tube, a small bend tube is provided between the casing and the flame tube, one end of the large bend tube is connected to the diffuser, the other end of the large bend tube is connected to the turbine guide mounting edge on the turbine guide, and an air intake structure is provided on the large bend tube; When the engine is running, the air is compressed by the compressor and enters the diffuser, then enters the combustion chamber casing. The air is divided into two parts along the outer ring of the combustion chamber. One part of the air flows along the outer ring and enters the flame tube and flows through the inner ring of the combustion chamber. The other part of the air flows along one side of the large bend and enters the flame tube through the intake structure on the large bend. The air in the flame tube and the fuel injected by the fuel nozzle are ignited by the igniter to form high-temperature and high-pressure gas. The gas flows out along the flame tube, enters the high-pressure turbine guide vane, and then flows out of the engine.

[0005] Furthermore, the diffuser is provided with a radial diffuser, an axial diffuser, large bend bolt holes, and stator mounting holes. 20-30 large bend bolt holes are evenly distributed circumferentially on the diffuser, and the large bend is mounted on the diffuser via these bolt holes and bolts. 6-10 stator mounting holes are evenly distributed circumferentially on the diffuser, and the diffuser is connected to the turbine guide vane mounting edge via these stator mounting holes. After being compressed by the compressor, the airflow enters the radial and axial diffusers sequentially, reducing the airflow velocity and increasing the static pressure, facilitating the airflow's entry into the combustion chamber for combustion.

[0006] Furthermore, the flame tube is made of high-temperature alloy plate, and the outer ring of the flame tube is provided with an installation edge for connecting with the large bend. The outer ring of the flame tube is also provided with cooling holes with a diameter of 1~2mm. 200~240 cooling holes are evenly distributed along the circumference of the outer ring of the flame tube, which are used to form an air film cooling of the initial section of the large bend with the introduced cooling airflow.

[0007] Furthermore, the large bend is made of high-temperature alloy sheet metal through sheet metal processing and EDM drilling. The air intake structure on the large bend includes straight holes, air inlets, and film cooling holes. The diameter of the straight holes is 4.5~5mm, and 20~30 straight holes are evenly distributed along the circumference of the large bend. The air inlets are located on the upper side of the large bend to introduce cooling airflow, and 40~60 air inlets are evenly distributed along the circumference of the large bend, with a diameter of 4~6mm. The film cooling holes are arranged along the airflow direction on the large bend. Three layers are used to achieve full film gas coverage of the large bend. Each layer consists of two rows of film gas holes with a diameter of 0.6~0.8mm. There are 160~220 film gas holes evenly distributed circumferentially in a single row. The two rows of film gas holes in each layer are arranged in a cross pattern to ensure both the air intake of the cooler and the uniformity of the circumferential film gas coverage to meet the design requirements. A large bend mounting edge is set on the inner side of the large bend. The large bend is inserted into the turbine guide vane mounting edge through the large bend mounting edge for installation.

[0008] Furthermore, the large bend is an integrated sheet metal structure formed by die stamping. The angles between the bending structure on the large bend and the engine axis along the airflow direction are 90°, 0°, 45°, 90°, 60°, 80° and 90°, respectively. Each bend on the large bend adopts an arc transition.

[0009] Furthermore, the turbine guide vane mounting edge is provided with a mounting groove and bolt holes. The mounting groove is used to install a large bend. During installation, the large bend fits tightly with the right side of the mounting groove. In the cold state, the large bend provides a pre-tightening force to the right to seal the airflow. When the engine is running, the large bend expands due to heat and fits tightly with the left side of the mounting groove, sealing the airflow under the action of internal and external air pressure. There are 6 to 10 bolt holes evenly distributed around the circumference of the turbine guide vane mounting edge for connecting the diffuser.

[0010] Furthermore, the small bend is welded to the flame tube as a whole, and the rear end of the small bend is connected to the high-pressure turbine guide.

[0011] The beneficial effects of this invention are as follows: This invention provides a recirculation combustion chamber equipped with a large curved tube mechanism for film cooling. The large curved tube, through a split design combined with film cooling technology, achieves axial and radial positioning, facilitating installation and disassembly, significantly reducing maintenance costs and replacement time, and improving the overall maintainability of the engine. Film cooling holes are arranged on the large curved tube, forming a continuous film covering on its surface, achieving a cooling efficiency of no less than 80%, significantly reducing the wall temperature of the large curved tube and extending engine life. The large curved tube and the outer ring flame tube are overlapped, achieving load distribution and uniform stress release, avoiding localized stress concentration that could cause structural deformation or damage. Simultaneously, the film cooling holes on the outer ring flame tube facilitate the formation of a continuous film covering on the surface of the large curved tube, preventing high-temperature ablation. The large curved tube and the turbine guide tube employ a radial overlap and axial clearance structural design, achieving high-precision fit while assisting the large curved tube in releasing stress. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the airflow in the recirculation combustion chamber during the implementation of this invention; Figure 3 This is a schematic cross-sectional view of the diffuser structure of the present invention; Figure 4 This is a partial cross-sectional view of the outer ring of the flame tube of the present invention; Figure 5 This is a schematic cross-sectional view of the large bend in the pipe of the present invention; Figure 6 This is a partial cross-sectional view of the turbine guide installation side of the present invention.

[0013] In the diagram, 1. Diffuser; 11. Radial diffuser; 12. Axial diffuser; 13. Bolt hole for large bend; 14. Stator mounting hole; 2. Casing; 3. Flame tube; 31. Mounting edge; 32. Cooling hole; 4. Fuel nozzle; 5. Large bend; 51. Straight hole; 52. Inlet; 53. Film gas hole; 54. Mounting edge for large bend; 6. Small bend; 7. High-pressure turbine guide; 8. Turbine guide mounting edge; 81. Mounting groove; 82. Bolt hole. Detailed Implementation

[0014] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0015] To achieve the above objectives, the present invention provides the following specific embodiments: Figure 1 As shown, a recirculation combustion chamber equipped with a film cooling large bend pipe mechanism includes a diffuser 1, a casing 2, a flame tube 3, a turbine guide 7, and a fuel nozzle 4. A large bend pipe 5 is provided after the diffuser 1 corresponding to the flame tube 3. A small bend pipe 6 is provided between the casing 2 and the flame tube 3. One end of the large bend pipe 5 is connected to the diffuser 1, and the other end of the large bend pipe 5 is connected to the turbine guide mounting edge 8 on the turbine guide 7. An air intake structure is provided on the large bend pipe 5. like Figure 2 As shown, when the engine is running, the air is compressed by the compressor and enters the diffuser 1, and then enters the combustion chamber casing 2. The air is divided into two parts along the outer ring of the combustion chamber. One part of the air flows along the outer ring and enters the flame tube 3 and flows through the inner ring of the combustion chamber. The other part of the air flows along one side of the large bend pipe 5 and enters the flame tube through the intake structure on the large bend pipe 5. The air in the flame tube 3 and the fuel sprayed from the fuel nozzle 4 are ignited by the igniter to form high-temperature and high-pressure gas. The gas flows out along the flame tube 3, enters the high-pressure turbine guide 7, and then flows out of the engine.

[0016] Furthermore, such as Figure 3 As shown, the diffuser 1 is provided with a radial diffuser 11, an axial diffuser 12, large bend bolt holes 13, and stator mounting holes 14. There are 20 to 30 large bend bolt holes 13 evenly distributed circumferentially on the diffuser 1. The large bend 5 is mounted on the diffuser 1 through the large bend bolt holes 13 and bolts. There are 6 to 10 stator mounting holes 14 evenly distributed circumferentially on the diffuser 1. The diffuser 1 is connected to the turbine guide vane mounting edge 8 through the stator mounting holes 14. After the airflow is compressed by the compressor, it enters the radial diffuser 11 and the axial diffuser 12 in sequence to reduce the airflow velocity and increase the static pressure of the airflow, so as to facilitate the airflow to enter the combustion chamber for combustion.

[0017] Furthermore, such as Figure 4As shown, the flame tube 3 is made of high-temperature alloy plate. The outer ring of the flame tube 3 is provided with an installation edge 31 for connecting with the large bend 5. The outer ring of the flame tube 3 is also provided with cooling holes 32 with a diameter of 1~2mm. 200~240 cooling holes 32 are evenly distributed along the circumference of the outer ring of the flame tube 3, which are used to form an air film cooling of the initial section of the large bend 5 with the introduced cooling airflow.

[0018] Furthermore, such as Figure 5 As shown, the large bend 5 is made of high-temperature alloy sheet metal through sheet metal processing and EDM drilling. The air intake structure on the large bend 5 includes straight holes 51, air inlets 52, and air film holes 53. The diameter of the straight holes 51 is 4.5~5mm, and 20~30 straight holes 51 are evenly distributed along the circumference of the large bend 5. The air inlets 52 are located on the upper side of the large bend 5 to introduce cooling airflow. 40-60 air inlets 52 are evenly distributed along the circumference of the large bend 5, and their diameter is 4~6mm. The air film holes 53 are located along the airflow direction of the large bend 5. Three channels are set on the bend 5 to achieve full air film coverage of the bend 5. Each air film channel consists of two rows of air film holes with a diameter of 0.6~0.8mm. There are 160~220 air film holes evenly distributed circumferentially in a single row of air film holes. The two rows of air film holes in each air film channel are arranged in a cross pattern to ensure both the air intake of the cooler and the uniformity of the circumferential air film coverage to meet the design requirements. A bend 5 mounting edge 54 is set on the inner side of the bend 5. The bend 5 is inserted into the turbine guide vane mounting edge 8 through the bend 5 mounting edge 54 for installation.

[0019] Furthermore, the large bend 5 is an integrated sheet metal structure formed by die stamping. The angles between the bending structure on the large bend 5 and the engine axis along the airflow direction are 90°, 0°, 45°, 90°, 60°, 80° and 90°, respectively. Each bend in the bending structure on the large bend 5 adopts an arc transition.

[0020] Furthermore, the small curved pipe 6 is welded to the flame tube 3 as a whole, and the rear end of the small curved pipe 6 is connected to the high-pressure turbine guide.

[0021] Furthermore, such as Figure 6 As shown, the turbine guide vane mounting edge 8 is provided with mounting groove 81 and bolt holes 82. The mounting groove 81 is used to install the large bend 5. During installation, the large bend 5 is tightly fitted with the right side of the mounting groove 81. When cold, the large bend 5 provides a pre-tightening force to the right to seal the airflow. When the engine is running, the large bend 5 is heated and expands, tightly fitting with the left side of the mounting groove 81, sealing the airflow under the action of internal and external air pressure. There are 6 to 10 bolt holes 82 evenly distributed around the turbine guide vane mounting edge 8 for connecting the diffuser 1.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A recirculation combustion chamber equipped with a film cooling large bend mechanism, characterized in that, It includes a diffuser, a casing, a flame tube, a turbine guide, and a fuel nozzle. A large bend is provided after the diffuser corresponding to the flame tube, and a small bend is provided between the casing and the flame tube. One end of the large bend is connected to the diffuser, and the other end of the large bend is connected to the turbine guide mounting edge on the turbine guide. An air intake structure is provided on the large bend. When the engine is running, the air is compressed by the compressor and enters the diffuser, then enters the combustion chamber casing. The air is divided into two parts along the outer ring of the combustion chamber. One part of the air flows along the outer ring and enters the flame tube and flows through the inner ring of the combustion chamber. The other part of the air flows along one side of the large bend and enters the flame tube through the intake structure on the large bend. The air in the flame tube and the fuel injected by the fuel nozzle are ignited by the igniter to form high-temperature and high-pressure gas. The gas flows out along the flame tube, enters the high-pressure turbine guide vane, and then flows out of the engine.

2. A recirculation combustion chamber equipped with a large curved air-film cooling mechanism as described in claim 1, characterized in that, The diffuser is provided with a radial diffuser, an axial diffuser, large bend bolt holes, and stator mounting holes. There are 20 to 30 large bend bolt holes evenly distributed circumferentially on the diffuser, and the large bend is installed on the diffuser through the large bend bolt holes and bolts. There are 6 to 10 stator mounting holes evenly distributed circumferentially on the diffuser, and the diffuser is connected to the turbine guide vane mounting edge through the stator mounting holes. After the airflow is compressed by the compressor, it enters the radial diffuser and the axial diffuser successively, which reduces the airflow velocity and increases the static pressure of the airflow, making it easier for the airflow to enter the combustion chamber for combustion.

3. A recirculation combustion chamber equipped with a large curved air-film cooling mechanism as described in claim 1, characterized in that, The flame tube is made of high-temperature alloy plate. The outer ring of the flame tube is provided with an installation edge for connecting with the large bend. The outer ring of the flame tube is also provided with cooling holes with a diameter of 1~2mm. 200~240 cooling holes are evenly distributed along the circumference of the outer ring of the flame tube, which are used to form an air film cooling of the initial section of the large bend with the introduced cooling airflow.

4. A recirculation combustion chamber equipped with a large curved air-film cooling mechanism as described in claim 1, characterized in that, The large bend is made of high-temperature alloy sheet metal through sheet metal processing and EDM drilling. The air intake structure on the large bend includes straight holes, air inlets, and film cooling holes. The diameter of the straight holes is 4.5~5mm, and 20~30 straight holes are evenly distributed along the circumference of the large bend. The air inlets are located on the upper side of the large bend to introduce cooling airflow, and 40-60 air inlets are evenly distributed along the circumference of the large bend, with a diameter of 4~6mm. Three film cooling holes are arranged along the airflow direction on the large bend. This design achieves full film coverage of the large bend. Each film ventilation hole consists of two rows of film ventilation holes with a diameter of 0.6~0.8mm. There are 160~220 film ventilation holes evenly distributed circumferentially in a single row. The two rows of film ventilation holes in each row are arranged in a cross pattern, which ensures both the air intake of the cooler and the uniformity of the circumferential film coverage to meet the design requirements. A large bend mounting edge is set on the inner side of the large bend. The large bend is inserted into the turbine guide vane mounting edge through the large bend mounting edge for installation.

5. A recirculation combustion chamber equipped with a large curved air-film cooling mechanism as described in claim 4, characterized in that, The large bend is an integrated sheet metal structure formed by die stamping. The angles between the bending structure on the large bend and the engine axis along the airflow direction are 90°, 0°, 45°, 90°, 60°, 80° and 90°, respectively. Each bend on the large bend is transitioned by an arc.

6. A recirculation combustion chamber equipped with a large curved air-film cooling mechanism as described in claim 4, characterized in that, The turbine guide vane has a mounting groove and bolt holes on its mounting edge. The mounting groove is used to install a large bend. During installation, the large bend fits tightly with the right side of the mounting groove. When cold, the large bend provides a pre-tightening force to the right to seal the airflow. When the engine is running, the large bend expands due to heat and fits tightly with the left side of the mounting groove, sealing the airflow under the action of internal and external air pressure. There are 6 to 10 bolt holes evenly distributed around the circumference of the turbine guide vane mounting edge for connecting the diffuser.

7. A recirculation combustion chamber equipped with a large curved air-film cooling mechanism as described in any one of claims 1 to 6, characterized in that, The small bend is welded to the flame tube as a whole, and the rear end of the small bend is connected to the high-pressure turbine guide.

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