Connection structure of large elbow

Abstract

The application discloses a connecting structure of a large elbow pipe, which is applied to a backflow combustion chamber of an aero-engine and comprises a diffuser assembly and a large elbow pipe installed on an outer ring of a flame tube. The large elbow pipe comprises a front section and a rear section. The rear section comprises an inner wall and an outer wall. The end of the front section extends axially towards the combustion chamber side of the diffuser assembly and is provided with a first connecting structure. The end of the inner wall extends axially towards the combustion chamber side of the diffuser assembly and is provided with a second connecting structure for active sealing connection with the first connecting structure. The outer wall is movably inserted into the second connecting structure. The diffuser assembly is provided with a limiting structure for active limiting connection with the second connecting structure. The large elbow pipe is connected through axial lapping and radial sealing, which facilitates stress release of the large elbow pipe, reduces deformation of the large elbow pipe, prolongs the service life of the large elbow pipe, improves air tightness and enhances the cooling effect.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and in particular, to a connection structure for a large bend in a pipe. Background Technology

[0002] In the field of aero-engines, recirculating combustion chambers are a common structural form used in small and medium-sized gas turbine engines, offering advantages such as compact structure and short engine shaft system. The large bend is a crucial component of the recirculating combustion chamber. Due to its design, the increased circulation parameters lead to a significant increase in aerodynamic and thermal stresses on the large bend, making it prone to deformation and cracking, thus affecting the lifespan and reliability of the recirculating combustion chamber. Therefore, double-walled impact-dispersion composite cooling structures with higher cooling efficiency are gradually being applied to large bends.

[0003] Currently, there are two main ways to connect the double-walled large bend to the outer ring of the flame tube. One way is to weld one side of the inner wall of the large bend to the outer wall of the flame tube to form the outer ring assembly, and the other side is connected to the turbine guide assembly and diffuser assembly by bolts. The outer wall of the large bend is connected to the inner wall of the large bend at the beginning and end by welding, so that the double-walled large bend and the outer ring of the flame tube are connected into an integrated structure. The other way is to install the large bend on the diffuser assembly and form a split structure with the outer ring of the flame tube. As the circulation parameters increase, the aerodynamic and thermal stresses on the large bend tube increase significantly. For the integrated structure connection, the large bend tube has a large radial span and is a thin-walled part with a large curvature, making it difficult to process and lacking precision. This can easily lead to deformation, affecting the impact chamber spacing and further impacting the cooling effect of the large bend tube. Moreover, since the two sides are connected by bolts, it is not easy to release the stress on the large bend tube through elastic deformation, causing cracks at the high stress points and affecting its service life. For the split structure connection, the existing split design places the split part on the outer ring of the flame tube near the inlet end of the recirculation combustion chamber. Since the large bend tube is subjected to a large aerodynamic load, deformation problems still exist. Furthermore, the large bend tube and the outer ring of the flame tube are simply overlapped, resulting in poor airtightness and serious air leakage, which affects the cooling effect of the large bend tube. Summary of the Invention

[0004] This invention provides a connection structure for a large bend pipe to solve the technical problem in the prior art where the deformation and leakage of the large bend pipe in the recirculation combustion chamber affect its service life and cooling effect.

[0005] According to one aspect of the present invention, a large bend connection structure is provided for use in the recirculation combustion chamber of an aero-engine, including a diffuser assembly and a large bend fixed to the outer ring of the flame tube, the large bend including a front section and a rear section, the rear section including a rear section inner wall and a rear section outer wall.

[0006] The end of the front section of the large bend extends axially toward the combustion chamber side of the diffuser assembly to form a first connecting structure, and the end of the inner wall of the rear section extends axially toward the combustion chamber side of the diffuser assembly to form a second connecting structure. The second connecting structure cooperates with the first connecting structure to form a movable sealing connection, and the outer wall of the rear section is movably inserted into the second connecting structure.

[0007] The diffuser assembly has a limiting structure on the combustion chamber side for engaging with the second connecting structure to limit movement.

[0008] Furthermore, the first connecting structure includes a first lap joint located at the end of the front section of the large bend for movably engaging with the second connecting structure, and an airflow guide edge for guiding the cooling airflow introduced into the inner wall of the rear section.

[0009] The first overlapping portion includes a first overlapping edge extending axially toward the combustion chamber side of the diffuser assembly and a first mounting groove disposed on the first overlapping edge. The opening of the first mounting groove faces away from the rear section of the large bend and is used to install a seal and to perform a movable seal with the second connecting structure through the seal. The airflow guide edge extends axially toward the inner wall of the rear section and is disposed on the inner side of the inner wall of the rear section.

[0010] Furthermore, the second connecting structure includes a second overlapping portion disposed on the inner wall of the rear section for movably overlapping with the first connecting structure, and an outer wall pressure ring disposed on the second overlapping portion for movably inserting with the outer wall of the rear section.

[0011] The second overlapping portion includes a second overlapping edge extending axially toward the combustion chamber side of the diffuser assembly, a limiting plate disposed on the second overlapping edge for engaging with the limiting structure, and a third overlapping edge disposed on the limiting plate and arranged toward the combustion chamber side away from the diffuser assembly. The outer wall pressure ring is fixed to the end of the second overlapping edge.

[0012] The second overlapping edge, the limiting plate, and the third overlapping edge together form a second mounting groove, which is used to accommodate the first connecting structure and to be movably sealed with the first connecting structure.

[0013] Furthermore, the outer wall pressure ring is fixed to the end of the second overlapping edge, and the opening of the outer wall pressure ring is set in the direction away from the combustion chamber side of the diffuser assembly. The end of the rear section of the outer wall extends axially toward the combustion chamber side of the diffuser assembly and passes through the outer wall pressure ring.

[0014] Furthermore, the limiting plate is provided with a first limiting hole and a second limiting hole. The diameter of the first limiting hole is larger than the diameter of the second limiting hole, and the first limiting hole and the second limiting hole are interconnected to form a sliding groove.

[0015] Furthermore, the limiting structure is an I-shaped limiting post, which is fixed to the combustion chamber side wall of the diffuser assembly. The maximum outer diameter of the limiting structure is smaller than the diameter of the first limiting hole of the limiting plate and larger than the diameter of the second limiting hole. The minimum outer diameter of the limiting structure is smaller than the diameter of the second limiting hole.

[0016] Furthermore, a first axial gap is formed between the limiting plate and the first overlapping edge, and a second axial gap is formed between the airflow guide edge and the inner wall of the rear section, the second axial gap being greater than the first axial gap.

[0017] Furthermore, the seal is movably installed in the first mounting groove and is sealed to the third overlapping edge.

[0018] Furthermore, a Z-ring structure is formed on the inner wall of the rear section. The wall surface of the Z-ring structure facing the outer wall of the rear section protrudes to support the outer wall of the rear section in order to control the impact cavity distance between the outer wall of the rear section and the inner wall of the rear section, and to provide cooling space for the inner wall of the rear section. Several Z-ring structures are provided on the inner wall of the rear section.

[0019] Furthermore, the connection structure of the large bend also includes a turbine guide assembly, and the rear section of the large bend is fixedly connected to the turbine guide assembly and the diffuser assembly at the outlet end of the recirculation combustion chamber.

[0020] The present invention has the following beneficial effects:

[0021] The connecting structure of the large bend of this invention separates the large bend at its maximum curvature to form a front section and a rear section. This disperses the stress on the large bend, effectively preventing stress concentration and deformation or cracking at the maximum curvature where stress is high. By setting a first connecting structure and a second connecting structure at the front and rear sections of the large bend respectively, the first and second connecting structures cooperate to axially overlap and provide radial movable sealing. This provides axial space for the elastic deformation of the front and rear sections of the large bend, assisting in stress release and avoiding the influence of aerodynamic forces. Simultaneously, it prevents the front and rear sections of the large bend from... Air leakage occurs between the later sections of the tube, improving the airtightness of the large bend and better controlling the pressure loss in the combustion chamber and the cooling effect of the large bend. A limiting structure is installed on the combustion chamber side of the diffuser assembly, allowing it to engage with the second connecting structure of the later section of the large bend. This locking mechanism helps in assembly, making axial and radial positioning between the large bend and the diffuser assembly easier. Furthermore, the locking mechanism leaves a clearance between the large bend and the diffuser assembly, providing axial and radial space for elastic deformation of the later section of the large bend, reducing the impact of diffuser assembly deformation on the large bend and effectively preventing deformation and cracking. By designing the later section of the large bend as a double-walled structure with an inner and outer wall, an impact cavity is formed between the inner and outer walls. Using this impact cavity for diffused composite cooling improves the cooling efficiency of the cooling gas, thereby reducing the wall temperature of the flame tube and ensuring its service life meets requirements. Optionally, by setting an airflow guide edge extending toward the inner wall of the rear section at the front section of the large bend, an initial air film is provided between the front and rear sections of the large bend, compensating for the lack of cooling design at the connection between the front and rear sections of the large bend; the Z-ring structure set on the inner wall of the rear section can support the outer wall of the rear section and control the impact cavity distance between the outer wall and the inner wall of the rear section, providing cooling space for the inner wall of the rear section.

[0022] 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

[0023] 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:

[0024] Figure 1 This is a schematic diagram of the overall structure of the connection structure of the large bend pipe according to a preferred embodiment of the present invention;

[0025] Figure 2 This is a partially enlarged view of the connection structure of the large bend pipe in a preferred embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of the limiting plate according to a preferred embodiment of the present invention;

[0027] Figure 4 This is a diagram illustrating the installation process of the limiting plate and the I-shaped limiting post according to a preferred embodiment of the present invention.

[0028] Legend:

[0029] 10. Flame tube outer ring; 20. Diffuser assembly; 30. Turbine guide assembly; 40. Front section of large bend; 50. Rear section of large bend; 51. Rear section inner wall; 511. Z-ring structure; 52. Rear section outer wall; 60. First connecting structure; 61. First overlapping edge; 62. First mounting groove; 63. Airflow guide edge; 64. Seal; 70. Second connecting structure; 71. Second overlapping edge; 72. Limiting plate; 721. First limiting hole; 722. Second limiting hole; 73. Third overlapping edge; 74. Outer wall pressure ring; 75. Second mounting groove; 80. Limiting structure. Detailed Implementation

[0030] 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.

[0031] like Figure 1 and Figure 2As shown, the large bend connection structure of this embodiment is applied to the recirculation combustion chamber of an aero-engine, including a diffuser assembly 20 and a large bend. The large bend is fixed to the outer ring 10 of the flame tube. The outer ring 10 of the flame tube is assembled and positioned with the casing of the recirculation combustion chamber at the inlet end of the recirculation combustion chamber by several pins. The assembly of the outer ring 10 of the flame tube by pins allows the outer ring 10 of the flame tube to have a certain amount of play, thereby providing a certain stress relief space for the large bend installed on the outer ring 10 of the flame tube. The large bend includes a front section 40 and a rear section 50. The front section 40 of the large bend is fixedly connected to the outer ring 10 of the flame tube at the inlet end of the recirculation combustion chamber, and is fixed to the diffuser assembly 20 at the outlet end of the recirculation combustion chamber by bolts to initially position the large bend. Preferably, the separation point of the front section 40 and the rear section 50 of the large bend is located at the maximum curvature of the large bend, where the stress is greatest. Separating the large bend at the maximum curvature point allows it to release stress through elastic deformation, preventing cracks or deformation at high stress points. The rear section 50 includes an outer wall 52 and an inner wall 51. By configuring the rear section 50 as a double-walled structure with an inner wall 51 and an outer wall 52, an impact cavity is formed between the inner wall 51 and the outer wall 52. Using this impact cavity for diffused composite cooling improves the cooling efficiency of the cooling gas. Optionally, the front section 40 of the large bend can also be configured as a double-walled structure. The end of the front section 40 of the large bend extends axially toward the combustion chamber side of the diffuser assembly 20 to form a first connecting structure 60, and the end of the inner wall 51 of the rear section extends axially toward the combustion chamber side of the diffuser assembly 20 to form a second connecting structure 70. The first connecting structure 60 is movably inserted into the second connecting structure 70, so that it cooperates with the second connecting structure 70 to form a movable sealing connection, thereby realizing the axial overlap and radial sealing of the front section 40 and the rear section 50 of the large bend, providing axial movement space for the elastic deformation of the rear section 50 of the large bend. At the same time, the first connecting structure 60 and the second connecting structure 70 are radially sealed to prevent the front section 40 and the rear section of the large bend from overlapping. Air leakage occurs between sections 50, affecting the pressure loss in the combustion chamber and the cooling effect of the large bend. The rear outer wall 52 extends axially at one end near the front section 40 of the large bend to form an extension edge. The extension edge of the rear outer wall 52 is movably inserted into the second connecting structure 70 of the rear inner wall 51, so that the rear outer wall 52 and the rear inner wall 51 are movably connected through the cooperation of the extension edge and the second connecting structure 70. Since there is a temperature difference between the rear inner wall 51 and the rear outer wall 52, compared with the prior art of fixing the rear outer wall and the rear inner wall by welding, the movable connection method can avoid the problem of deformation and cracking of the rear outer wall 52 and the rear inner wall 51 due to the temperature difference.Meanwhile, a movable gap is provided between the extended edge of the rear outer wall 52 and the second connecting structure 70, providing axial and radial movement space for the rear outer wall 52, facilitating stress release and preventing deformation or cracks. A limiting structure 80 is provided on the combustion chamber side of the diffuser assembly 20, facing the outer wall surface of the large bend, for engaging with the second connecting structure 70 on the rear inner wall 51 to limit the movement of the rear section 50 of the large bend. On the one hand, the engaging method can assist in the assembly between the large bend and the diffuser assembly 20, making the axial and radial positioning between the large bend and the diffuser assembly 20 more convenient. On the other hand, the axial and radial movement gap between the large bend and the diffuser assembly 20 after engagement provides room for elastic deformation of the rear section 50 of the large bend, reducing the impact of the diffuser assembly 20 deformation on the large bend, effectively preventing deformation and cracks in the large bend, and improving the service life of the large bend.

[0032] like Figure 2 As shown, the front section 40 and rear section 50 of the large bend are axially overlapped and radially sealed through the cooperation of the first connecting structure 60 and the second connecting structure 70. The first connecting structure 60 includes a first overlapping portion and an airflow guide edge 63 disposed at the end of the front section 40. The first overlapping portion includes a first overlapping edge 61 extending axially toward the combustion chamber side of the diffuser assembly 20 and a first mounting groove 62 disposed on the first overlapping edge 61. The airflow guide edge 63 extends axially toward the rear section 50 along the front section 40 and is disposed on the inner side of the inner wall 51 of the rear section. A plurality of air film holes are opened on the inner wall 51 of the rear section, through which air film holes are formed. The cooling airflow introduced through the air film holes on the rear section inner wall 51 forms an initial air film at the end of the rear section inner wall 51, compensating for the lack of cooling design at the connection between the front section 40 and the rear section 50 of the large bend. An movable gap is formed between the airflow guide edge 63 and the inner wall of the rear section inner wall 51. The setting of the airflow guide edge 63 allows the cooling airflow entering through the air film holes on the rear section inner wall 51 to flow along the inner wall of the rear section inner wall 51 through the narrow movable gap, forming an initial air film with good wall adhesion to protect the end of the rear section inner wall 51. At the same time, the setting of the airflow guide edge 63 can provide guidance for the initial air film and enhance the cooling effect at the end of the rear section inner wall 51.

[0033] like Figure 2 and Figure 4As shown, the second connecting structure 70 includes a second overlapping portion disposed at the end of the rear inner wall 51 of the rear section of the large bend 50 and an outer wall pressure ring 74 disposed on the second overlapping portion. The second overlapping portion includes a second overlapping edge 71 extending axially toward the combustion chamber side of the diffuser assembly 20, a limiting plate 72 disposed on the second overlapping edge 71, and a third overlapping edge 73 disposed on the limiting plate 72. The limiting plate 72 is fixed to the end of the second overlapping edge 71 and is disposed toward the front section 40 of the large bend, for engaging with the limiting structure 80 on the combustion chamber side of the diffuser assembly 20 for movable limiting. The third overlapping edge 73 is fixed to the side wall of the limiting plate 72 and is disposed toward the combustion chamber side away from the diffuser assembly 20, so that it surrounds the second overlapping edge 71 and the limiting plate 72 to form a second mounting groove 75. The outer wall pressure ring 74 is fixed to the end of the second overlapping edge 71 and is positioned away from the limiting plate 72. The opening of the outer wall pressure ring 74 faces the outer wall surface of the rear inner wall 51. The end of the rear inner wall 51 extends axially towards the inner wall of the diffuser assembly 20 to form an extension edge, which is inserted into the outer wall pressure ring 74. A clearance is provided between the extension edge at the end of the rear inner wall 51 inserted into the outer wall pressure ring 74 and the outer wall pressure ring 74 in both the axial and radial directions, thereby limiting the movement of the rear outer wall 52 through the outer wall pressure ring 74. The rear section 50 of the large bend... The outer wall 52 is located on the cold air side, where the temperature is low. Inserting the rear section of the outer wall 52 into the outer wall pressure ring 74 can reduce the amount of air leakage between the rear section of the inner wall 51 and the rear section of the outer wall 52, improve air tightness, and better control the pressure loss in the combustion chamber and the cooling effect of the large bend. At the same time, the setting of the outer wall pressure ring 74 provides the rear section of the outer wall 52 with axial and radial movement space, which facilitates the release of stress in the rear section of the outer wall 52 to reduce the deformation problem of the rear section of the outer wall 52, thereby avoiding the impact cavity distance between the rear section of the outer wall 52 and the rear section of the inner wall 51 due to the deformation of the rear section of the outer wall 52, and ensuring the cooling effect of the large bend.

[0034] Specifically, the first overlapping edge 61 is inserted into the second mounting groove 75, and the first mounting groove 62 is disposed on the first overlapping edge 61 with its opening facing the side wall of the third overlapping edge 73. The sealing element 64 is installed in the first mounting groove 62 and is in contact with the third overlapping edge 73 for movable engagement, thereby sealing the first connecting structure 60 and the second connecting structure 70. Preferably, the sealing element 64 is an expansion ring. Through the expansion force of the expansion ring, the rear section 50 of the large bend pipe and the front section 40 of the large bend pipe can be tightly connected to prevent air leakage, improve airtightness, and thus enhance the cooling effect on the large bend pipe. In addition, the expansion ring also has a certain fixing function, which can ensure the relative position of the front section 40 of the large bend pipe and the rear section 50 of the large bend pipe. Since the large bend pipe is affected by high temperature, high pressure and vibration during operation, the expansion ring can provide a certain support to ensure the stability of the assembly between the rear section 50 of the large bend pipe and the front section 40 of the large bend pipe. Preferably, the first and second overlapping portions employ relatively stringent fit dimensions to ensure airtightness between the front section 40 and the inner wall 51 of the rear section of the large bend. Radial gaps are maintained between the sealing element 64 and the bottom wall of the first mounting groove 62, and between the first overlapping edge 61 and the second overlapping edge 71, forming a movable seal between the first and second overlapping portions. This provides radial movement space for the front section 40 of the large bend, assisting in the radial stress release of the front section 40 and preventing excessive stress on the front section 40 from causing deformation or cracking. A first axial gap is formed between the limiting plate 72 and the first overlapping edge 61, and a second axial gap is formed between the airflow guide edge 63 and the inner wall 51 of the rear section, to provide axial movement space for the front section 40 of the large bend, assisting in the axial stress release of the front section 40 and preventing excessive stress on the front section 40 from causing deformation or cracking. Furthermore, the second axial gap is greater than the first axial gap, so that when the front section 40 of the large bend is subjected to greater stress, causing the first overlapping edge 61 to abut against the side wall of the limiting plate 72, there is still a certain axial gap between the airflow guide edge 63 and the inner wall of the rear section inner wall 51, so as to avoid the airflow guide edge 63 sticking to the inner wall of the rear section inner wall 51 and causing blockage of the air film pores, thus affecting the airflow cooling effect.

[0035] like Figure 1 and Figure 2As shown, the limiting structure 80 is an I-shaped limiting post, which is fixed to the inner wall of the diffuser assembly 20 and arranged towards the outer wall of the large bend. The I-shaped limiting post includes a cylinder and an annular groove formed radially along the cylinder. The limiting plate 72 of the second connecting structure 70 has a first limiting hole 721 and a second limiting hole 722. Preferably, the first limiting hole 721 and the second limiting hole 722 are elongated holes, and the first limiting hole 721 and the second limiting hole 722 are interconnected to form an I-shaped... The limiting post has a sliding groove, and the diameter of the first limiting hole 721 is larger than the diameter of the second limiting hole 722. The diameter of the first limiting hole 721 is larger than the maximum outer diameter of the I-shaped limiting post, and the diameter of the second limiting hole 722 is larger than the minimum outer diameter of the I-shaped limiting post but smaller than the maximum outer diameter of the I-shaped limiting post. This allows the I-shaped limiting post to pass through the first limiting hole 721 into the limiting plate 72 and slide along the first limiting hole 721 into the second limiting hole 722, where it is then locked in place by the second limiting hole 722. Preferably, several I-shaped limiting posts are provided on the combustion chamber side of the diffuser assembly 20, and the number of limiting plates 72 corresponds to the number of I-shaped limiting posts. The limiting structure 80 and the limiting plate 72 are limited by the snap-fit ​​connection between the I-shaped limiting post and the second limiting hole 722. On the one hand, the height of the annular groove of the I-shaped limiting post is greater than the thickness of the limiting plate 72, so that after the limiting plate 72 and the I-shaped limiting post are assembled, an axial gap is formed through the annular groove. The diameter of the second limiting hole 722 on the limiting plate 72 is greater than the minimum outer diameter of the I-shaped limiting post, so that after the I-shaped limiting post is snapped into the second limiting hole 722, a radial gap is formed in the second limiting hole 722. Thus, the axial gap and the radial gap provide room for the elastic deformation of the rear section 50 of the large bend, ensuring the stress release of the rear section 50 of the large bend, and at the same time reducing the impact of the deformation of the diffuser assembly 20 on the rear section 50 of the large bend. On the other hand, the limiting plate 72 is provided with a groove structure formed by the first limiting hole 721 and the second limiting hole 722. The I-shaped limiting post is engaged with the groove on the limiting plate 72 to make the axial and radial positioning between the large bend and the diffuser assembly 20 more convenient and improve the assembly efficiency.

[0036] like Figure 4 As shown, during the assembly of the I-shaped limiting post and the limiting plate 72, the first limiting hole 721 on the limiting plate 72 of the second connecting structure 70 is aligned with the I-shaped limiting post. Then, the limiting plate 72 is moved towards the direction close to the I-shaped limiting post, so that the I-shaped limiting post passes through the limiting plate 72 and the limiting plate 72 is placed in the annular groove of the I-shaped limiting post. Then, the rear section 50 of the large bend is rotated to drive the limiting plate 72 to move, so that the I-shaped limiting post and the limiting plate 72 move relative to each other, so that the I-shaped limiting post slides from the first limiting hole 721 to the second limiting hole 722, and is thus locked by the second limiting hole 722 for movement limitation.

[0037] Preferably, the fit dimensions between the I-shaped limiting post and the second limiting hole 722 can adopt a relatively loose tolerance range, providing axial and radial movement space for the inner wall 51 of the rear section to ensure the release of stress in the inner wall 51 of the rear section, reducing the influence of the deformation of the diffuser assembly 20 on the rear section 50 of the large bend, and avoiding assembly difficulties caused by material deformation after hot working, thus reducing the difficulty of the process.

[0038] like Figure 1 and Figure 2 As shown, the rear section 50 of the large bend adopts an impact hole and film cooling structure. The impact holes are located on the outer wall 52 of the rear section, and the film cooling holes are located on the inner wall 51 of the rear section. A Z-ring structure 511 protruding towards the outer wall 52 of the rear section is formed on the inner wall 51 of the rear section to create an impact chamber for airflow between the inner wall 51 and the outer wall 52 of the rear section. Preferably, the impact holes and film cooling holes are arranged in a diamond-shaped staggered pattern to accelerate heat exchange efficiency. The cooling airflow first enters the impact chamber through the impact holes of the rear outer wall 52, and then enters the air film pores of the rear inner wall 51 from the impact chamber. The Z-ring structure 511 can enhance the cooling effect of the rear inner wall 51. Experiments show that the Z-ring structure 511 allows the cooling airflow to stay in the impact chamber between the rear inner wall 51 and the rear outer wall 52 for a longer time, and the cooling airflow is closer to the wall surface of the rear inner wall 51, thus improving the cooling effect of the rear inner wall 51 and enhancing the cooling of the rear section 50 of the large bend. On the other hand, it can also provide cooling for the rear section... The outer wall 52 provides support and allows for more precise control of the impact cavity distance between the rear outer wall 52 and the rear inner wall 51. This ensures that the impact cavity distance remains constant when the rear outer wall 52 deforms under a large load, thus guaranteeing the cooling effect. It also prevents the rear outer wall 52 from sticking to the wall surface of the rear inner wall 51 under hot conditions, causing blockage of the air film pores and affecting the entry of cooling airflow. At the same time, it prevents the impact cavity distance from being too large or too small, which would result in poor cooling effect due to the impact of the cooling airflow on the rear inner wall 51. This enhances heat transfer and improves the enhanced heat transfer coefficient. Preferably, multiple Z-ring structures 511 are provided, and the multiple Z-ring structures 511 are arranged sequentially and spaced apart along the circumference of the rear section inner wall 51 to prevent the rear section outer wall 52 from sticking to the rear section inner wall 51 under hot conditions, thereby affecting the effect of impact cooling; or multiple Z-ring structures 511 are provided at both ends of the rear section inner wall 51 to prevent the ends of the rear section outer wall 52 from sticking to the ends of the rear section inner wall 51 under hot conditions, thereby affecting the cooling effect of the end of the rear section 50 of the large bend.

[0039] like Figure 1As shown, the connection structure of the large bend also includes a turbine guide assembly 30, which is located at the outlet end of the recirculation combustion chamber. The rear section 50 of the large bend is bolted to the turbine guide assembly 30 and the diffuser assembly 20 at the outlet end of the recirculation combustion chamber. Specifically, the rear inner wall 51 of the rear section 50 is fixedly connected to the turbine guide assembly 30 near its end. The rear outer wall 52 of the rear section 50 extends axially near its end to form a connecting plate, which is located between the turbine guide assembly 30 and the diffuser assembly 20. Bolts are passed sequentially through the turbine guide assembly 30, the connecting plate, and the diffuser assembly 20 to fix the rear outer wall 52 to both the turbine guide assembly 30 and the diffuser assembly 20. The connection method between the rear inner wall 51 and the rear outer wall 52 near its end to the turbine guide assembly 30 is a known prior art and will not be described in detail here.

[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 large bend pipe connection structure applied to the recirculation combustion chamber of an aero-engine, comprising a diffuser assembly (20) and a large bend pipe mounted on the outer ring (10) of the flame tube, characterized in that, The large bend includes a front section (40) and a rear section (50), and the rear section (50) includes an inner wall (51) and an outer wall (52). The end of the front section (40) of the large bend extends axially toward the combustion chamber side of the diffuser assembly (20) to form a first connecting structure (60), and the end of the inner wall (51) of the rear section extends axially toward the combustion chamber side of the diffuser assembly (20) to form a second connecting structure (70). The second connecting structure (70) cooperates with the first connecting structure (60) to form a movable sealing connection, and the outer wall (52) of the rear section is movably inserted into the second connecting structure (70). The diffuser assembly (20) has a limiting structure (80) on the combustion chamber side for engaging with the second connecting structure (70) to limit movement. The second connecting structure (70) includes a second overlapping portion disposed at the end of the rear inner wall (51) for movably overlapping with the first connecting structure (60), and an outer wall pressure ring (74) disposed on the second overlapping portion for movably inserting with the rear outer wall (52). The second overlapping portion includes a second overlapping edge (71) extending axially toward the combustion chamber side of the diffuser assembly (20), and a second overlapping edge (71) disposed on the second overlapping edge (71) for engaging with the limiting structure (80). The connecting limiting plate (72) and the third overlapping edge (73) disposed on the limiting plate (72) and arranged in a direction away from the combustion chamber side of the diffuser assembly (20), the outer wall pressure ring (74) is fixed to the end of the second overlapping edge (71), the second overlapping edge (71), the limiting plate (72) and the third overlapping edge (73) surround to form a second mounting groove (75) for accommodating the first connecting structure (60) and movably sealing with the first connecting structure (60).

2. The connection structure of the large bend pipe according to claim 1, characterized in that, The first connecting structure (60) includes a first lap joint disposed at the end of the front section (40) of the large bend for movably inserting with the second connecting structure (70) and an airflow guide edge (63) for guiding the cooling airflow introduced into the inner wall (51) of the rear section. The first overlapping portion includes a first overlapping edge (61) extending axially toward the combustion chamber side of the diffuser assembly (20) and a first mounting groove (62) disposed on the first overlapping edge (61). The opening of the first mounting groove (62) faces away from the rear section (50) of the large bend and is used to install a seal (64) and to perform a movable seal with the second connecting structure (70) through the seal (64). The airflow guide edge (63) extends axially toward the inner wall (51) of the rear section and is disposed on the inner side of the inner wall (51) of the rear section.

3. The connection structure of the large bend pipe according to claim 1, characterized in that, The outer wall pressure ring (74) is fixed to the end of the second overlapping edge (71), and the opening of the outer wall pressure ring (74) is arranged in a direction away from the combustion chamber side of the diffuser assembly (20). The end of the rear outer wall (52) extends axially toward the combustion chamber side of the diffuser assembly (20) and is movably inserted into the outer wall pressure ring (74).

4. The connection structure of the large bend pipe according to claim 1, characterized in that, The limiting plate (72) is provided with a first limiting hole (721) and a second limiting hole (722). The diameter of the first limiting hole (721) is larger than the diameter of the second limiting hole (722), and the first limiting hole (721) and the second limiting hole (722) are interconnected to form a sliding groove.

5. The connection structure of the large bend pipe according to claim 4, characterized in that, The limiting structure (80) is an I-shaped limiting post, which is fixed to the wall of the combustion chamber side of the diffuser assembly. The maximum outer diameter of the limiting structure (80) is smaller than the diameter of the first limiting hole (721) of the limiting plate (72) and larger than the diameter of the second limiting hole (722). The minimum outer diameter of the limiting structure (80) is smaller than the diameter of the second limiting hole (722).

6. The connection structure of the large bend pipe according to claim 2, characterized in that, A first axial gap is formed between the limiting plate (72) and the first overlapping edge (61), and a second axial gap is formed between the airflow guiding edge (63) and the rear inner wall (51), the second axial gap being greater than the first axial gap.

7. The connection structure of the large bend pipe according to claim 2, characterized in that, The sealing element (64) is movably installed in the first mounting groove (62) and is in contact with the third overlapping edge (73) for sealing.

8. The connection structure of the large bend pipe according to claim 1, characterized in that, A Z-ring structure (511) is formed on the inner wall (51) of the rear section. One end of the Z-ring structure (511) protrudes toward the inner wall surface of the outer wall (52) of the rear section, which is used to support the outer wall (52) of the rear section to control the impact cavity distance between the outer wall (52) of the rear section and the inner wall (51) of the rear section, and to provide cooling space for the inner wall (51) of the rear section. The Z-ring structure (511) has several of them on the inner wall (51) of the rear section.

9. The connection structure of the large bend pipe according to claim 1, characterized in that, The connection structure of the large bend also includes a turbine guide assembly (30), and the rear section (50) of the large bend is fixedly connected to the turbine guide assembly (30) and the diffuser assembly (20) at the outlet end of the recirculation combustion chamber.

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