A design method for the flow path of the air supply system of an aircraft engine with a converging and diverging bleed air system

Abstract

The present invention discloses a method for designing a flow path of a converging and diverging bleed air supply flow in an aero-engine air system, which belongs to the technical field of aero-engine air system design, and is used to optimize the distribution path of the internal air system of an aero-engine, improve the cooling, anti-icing and sealing performance, improve the flow resistance loss, and enhance the system integration. The method constructs an annular converging and diverging structure framework by evenly arranging a number of hollow support plates and hollow diverter cones extending radially along the circumferential direction in an intermediate casing, and introduces secondary air from the engine high-pressure air source through a bleed air short pipe, and evenly distributes the secondary air to the inner cavity of the hollow support plate and the hollow diverter cone based on the gas connection structure. By optimizing the arrangement of anti-icing holes on the surface of the hollow diverter cone, CFD simulation is used to improve the uniformity and stability of the attached air film, so as to achieve efficient anti-icing of the diverter cone; at the same time, the sealing and cooling supply air path of the front bearing cavity and the low-pressure turbine end are optimized to reduce the loss of airflow along the way and ensure stable distribution of airflow.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft engine air system design, and specifically relates to a design method for a converging and diverging bleed air supply flow path of an aircraft engine air system, which is used for optimizing the air flow distribution of an air system in an aircraft engine. Background Art

[0002] As the core power unit of modern aircraft, the operating reliability and performance level of aircraft engines directly affect flight safety and efficiency. The air system is an important airflow management system in aircraft engines in addition to the main gas flow. It mainly undertakes multiple functions such as cooling, sealing, anti-icing and axial force balance of various key components of the engine. This system directly affects the matching and performance of engine components, is closely related to the performance of the entire machine, and is a key component to ensure engine reliability and service life.

[0003] In the design of modern high-performance aircraft engines, due to the increasingly compact structure of the whole machine and the limited internal space of the intermediate casing, the traditional air system generally has problems such as complex air bleed paths and unstable air supply quality in terms of flow path layout and functional integration. Especially in the front end area of ​​the intermediate casing, the anti-icing and sealing functions of key components such as the splitter cone, support plate, and bearing cavity often use independent air bleed pipeline designs, which not only increases the complexity of the structure, but also brings a series of technical problems:

[0004] First, the independent multi-path bleed air pipeline design leads to an increase in the flow resistance along the way. Since the bleed air path from the compressor to the target component is usually long and has many turns, involving multi-stage pipelines, cavities and flow resistance elements, the air flow pressure loss caused by friction and local turbulence during the flow of the gas increases significantly, making it difficult for the pressure of the bearing cavity sealing gas to meet the design requirements. In this case, the oil and gas sealing effect of the bearing cavity deteriorates, and lubricating oil leakage problems are prone to occur, which not only increases the lubricating oil consumption of the engine, but also may cause environmental pollution and equipment corrosion risks. In addition, due to the long path, the gas temperature rises during the transmission process, weakening the cooling and anti-icing effects. At the same time, the excessively long path may also cause a delay in the response of the dynamic air supply system, affecting the engine's ability to quickly adjust.

[0005] Secondly, it is difficult to ensure uniform airflow distribution with a single bleed air duct. Especially in the anti-icing design of large-sized components such as splitter cones and support plates, insufficient airflow supply in local areas will lead to uneven anti-icing effect, affect the aerodynamic characteristics of the flow channel section, and may cause aerodynamic performance loss due to ice accumulation.

[0006] Thirdly, the complex piping layout significantly increases the difficulty of manufacturing and assembly. In the limited space of the intermediate casing, the multi-level piping layout not only increases the number of parts, but also increases the processing precision requirements. At the same time, the complex assembly process also increases the difficulty of quality control and production costs. In addition, in the traditional design, the left and right ends of the engine front bearing cavity are usually sealed with bleed air sources of different pressure levels, which can easily cause a large pressure difference at both ends of the bearing cavity. When the pressure in the bearing cavity is constant, the sealing pressure ratio on one side may be too high while the sealing effect on the other side may be insufficient, affecting the overall sealing performance.

[0007] In summary, the existing air system has deficiencies in terms of flow path length, air supply uniformity, structural complexity, oil leakage control and functional integration. Therefore, developing a more efficient, reliable and compact air system bleed air supply flow path is of great significance to improving engine performance and reliability. Summary of the invention

[0008] 1. Purpose of the invention

[0009] In view of the above-mentioned defects and shortcomings of the prior art, the present invention aims to provide a method for designing a converging and diverging bleed air supply flow path for an aircraft engine air system. By designing a converging and diverging bleed air supply flow path structure, components such as splitter cones, support plates and bearing seats are integrated into an integrated flow path system, and structures such as bleed air short pipes, air vents and air supply pipes are used to achieve efficient distribution and utilization of secondary air. Through the converging and diverging design, the present invention can shorten the air supply path, reduce pressure loss, improve the uniformity of air supply temperature, enhance the anti-icing performance of components and the sealing performance of bearing cavities, while simplifying the system structure, reducing the difficulty of processing and assembly, and ultimately achieving the purpose of improving the overall performance and reliability of aircraft engines.

[0010] (II) Technical solution

[0011] In order to achieve the purpose of the invention and solve the technical problems, the present invention adopts the following technical solutions:

[0012] A method for designing a flow path of a converging and diverging bleed air supply system of an aircraft engine is provided, which is used to optimize the distribution path of the internal air system of the aircraft engine, improve the cooling, anti-icing and sealing performance, improve the flow resistance loss, and enhance the system integration. The flow path design method comprises at least the following steps when implemented:

[0013] SS1. Design and layout of intermediate casing structure

[0014] A plurality of hollow support plates extending radially are evenly arranged in the circumferential direction in the intermediate casing at the front end of the aircraft engine, and the upper and lower ends of each hollow support plate are respectively connected to the outer ring casing and the inner ring casing of the intermediate casing; a hollow flow dividing cone is fixedly connected between each two adjacent hollow support plates, and the two ends of each hollow flow dividing cone are respectively connected to the inner cavity of the two adjacent hollow support plates, and the radial positions of the hollow flow dividing cones are the same and the whole is formed into an annular structure, so that a gas communication structure is formed between each hollow support plate and the hollow flow dividing cone, forming a basic framework of the converging and diverting flow path;

[0015] SS2. Optimization design of air flow path of air system

[0016] An air bleed short pipe is arranged on the trailing edge end face of at least one hollow splitter cone, for introducing secondary air from the high-pressure air source of the aircraft engine and conveying it to the inner cavity of the hollow splitter cone, and the length, diameter, number and circumferential distribution position of the air bleed short pipe are determined according to the pressure margin of the air bleed point at the high-pressure air source end and the sealing pressure difference design requirements of the engine front bearing cavity, so as to optimize the air bleed efficiency and reduce the air flow loss along the way, and the introduced secondary air is evenly distributed to the inner cavity of each hollow support plate and the hollow splitter cone based on the gas communication structure formed by each hollow support plate and the hollow splitter cone;

[0017] SS3. Optimization design of anti-icing air supply path of hollow diverter cone

[0018] A plurality of anti-icing holes for the diverter cones connected to the inner cavity of each hollow diverter cone are discretely opened on the upper and lower surfaces near the leading edge of the diverter cones to spray secondary air and form attached air films on the upper and lower surfaces of the hollow diverter cones. The number, size, distribution position and spray angle of the anti-icing holes for the diverter cones are optimized through computational fluid dynamics (CFD) simulation and according to the geometric shape and airflow characteristics of the hollow diverter cones to ensure that the sprayed secondary air can evenly cover the upper and lower surfaces of the hollow diverter cones.

[0019] SS4. Optimization design of the air supply path of the engine front bearing cavity seal

[0020] An engine front bearing cavity is arranged in the inner ring casing of the intermediate casing, and a downstream bearing seat and a matching downstream comb tooth sealing ring as well as an upstream bearing seat and a matching upstream comb tooth sealing ring are arranged in the engine front bearing cavity; a plurality of first vent holes are arranged along the circumferential direction on the outer ring surface of the downstream bearing seat, so as to introduce the secondary air in the inner cavity of the hollow support plate into the inner cavity of the downstream bearing seat; a plurality of second vent holes are arranged along the circumferential direction on the inner ring surface of the downstream bearing seat, so as to introduce the secondary air in the inner cavity of the downstream bearing seat into the downstream comb tooth sealing ring, and A plurality of sealing vents are provided on the inner ring surface of the sealing ring in the circumferential direction, for supplying secondary air into the downstream sealing grate teeth to achieve sealing of the downstream end of the engine front bearing cavity; a plurality of third vents are provided on the front end surface of the downstream bearing seat in the circumferential direction, and the third vents are connected with the upstream bearing seat and the upstream grate teeth sealing ring through an air supply pipe extending in the axial direction, and a plurality of sealing vents are provided on the inner ring surface of the upstream grate teeth sealing ring in the circumferential direction, for supplying secondary air into the upstream grate teeth sealing structure to achieve sealing of the upstream end of the engine front bearing cavity;

[0021] SS5. Optimization design of air supply path for low pressure turbine end and inlet cone seal

[0022] Sealing grate teeth corresponding to the upstream grate teeth sealing ring are arranged on the upstream end wall of the low-pressure turbine shaft, and vents are opened to introduce secondary air into the axis of the low-pressure turbine shaft. The airflow in the axis of the low-pressure turbine shaft is evenly distributed through the flow resistance optimization structure. Part of it is transported upstream to the intake cone to form an anti-icing airflow, and the other part is transported downstream to the low-pressure turbine end for sealing and cooling.

[0023] (III) Technical Effect

[0024] Compared with the prior art, the design method of the aero-engine air system converging and diverging bleed air supply flow path of the present invention has the following beneficial and significant technical effects:

[0025] (1) The present invention adopts the flow path design concept of confluence and diversion. After the secondary air is introduced from the high-pressure air source of the aircraft engine, such as the compressor blade tip, it is first gathered into a network of interconnected chambers composed of support plates and diverter cones, and then diverted according to the needs of different functional areas, respectively used for diverter cone anti-icing, bearing cavity sealing, intake cone anti-icing and low-pressure turbine end seal cooling. This confluence and diversion design shortens the air supply path, reduces the pressure and temperature losses along the air flow, improves the air supply efficiency, and effectively reduces the flow resistance loss of the engine.

[0026] (2) The present invention simplifies the overall structure of the engine air system by integrating multiple functional air system flow paths in the intermediate casing, reduces the number of components such as pipes and valves, and reduces the weight and complexity of the system. This integrated design is also conducive to reducing the manufacturing cost and assembly difficulty of the engine, and improving the reliability and maintainability of the system.

[0027] (3) The present invention achieves precise control and distribution of secondary air by optimizing the geometric parameters of the air bleed short pipe, the anti-icing holes of the splitter cone, the sealing flow path of the bearing cavity, and the air supply path of the low-pressure turbine end and the intake cone. For example, by adjusting the length and diameter of the air bleed short pipe, the flow rate and pressure of the secondary air entering the inner cavity of the splitter cone can be controlled; by optimizing the number, size, distribution position and injection angle of the anti-icing holes of the splitter cone, it can be ensured that the injected secondary air can evenly cover the surface of the splitter cone, forming a stable and effective attached air film, thereby improving the anti-icing effect.

[0028] (4) The present invention introduces secondary air into the front bearing cavity of the engine and provides vent holes on the bearing seat and the comb seal ring, thereby achieving effective sealing of the bearing cavity, preventing oil leakage, and improving the reliability and service life of the engine. At the same time, by optimizing the geometric parameters of the bearing cavity seal flow path, the flow rate and pressure of the secondary air entering the engine bearing cavity can be controlled, thereby minimizing the consumption of secondary air while ensuring the sealing effect.

[0029] (5) The present invention achieves anti-icing of the intake cone and sealing cooling of the low-pressure turbine end by introducing part of the secondary air into the axis of the low-pressure turbine shaft and delivering it upstream and downstream respectively. This design effectively utilizes the secondary air and improves the overall performance and efficiency of the engine. At the same time, by optimizing the airflow distribution in the axis of the low-pressure turbine shaft, the stability and uniformity of the anti-icing and sealing airflow can be ensured, thereby improving the reliability and service life of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the specification of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute an improper limitation of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings, wherein:

[0031] Figure 1 The figure is a flow chart of the implementation of the method for designing the converging and diverging bleed air supply flow path of the aircraft engine air system according to the embodiment of the present invention;

[0032] Figure 2 The figure is a front view of the intermediate casing at the front end of the aircraft engine in the embodiment of the present invention;

[0033] Figure 3 Shown is an overall cross-sectional view of the front intermediate casing of an aircraft engine in an embodiment of the present invention.

[0034] In the drawings, the meanings of the reference numerals are as follows:

[0035] 100-intermediate casing, 10-outer ring casing, 20-inner ring casing, 30-hollow support plate, 31-support plate vent, 40-hollow diverter cone, 41-diverter cone anti-icing hole, 50-air bleed short pipe, 60-downstream bearing seat, 61-downstream grate sealing ring, 62-first vent, 63-second vent, 64-third vent, 65-sealed vent, 66-air supply pipe, 67-annular cover, 70-upstream bearing seat, 71-upstream grate sealing ring, 72-sealed vent, 80-low-pressure turbine shaft, 81-sealed grate, 82-vent. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. The described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be understood as limiting the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] The embodiment of the present invention provides a method for designing a flow path of a converging and diverging bleed air supply flow in an aircraft engine air system, which is used to optimize the distribution path of the internal air system of the aircraft engine, improve the cooling, anti-icing and sealing performance, improve the flow resistance loss, and enhance the system integration. Figure 1 And refer to the combination Figure 2 , 3 As shown, the flow path design method mainly includes the following steps when implemented:

[0038] SS1. Design and layout of intermediate casing structure

[0039] A number of hollow support plates 30 extending radially are evenly arranged along the circumferential direction in the intermediate casing 100 at the front end of the aircraft engine, and the upper and lower ends of each hollow support plate 30 are respectively connected to the outer ring casing 10 and the inner ring casing 20 of the intermediate casing 100; a hollow diverter cone 40 is fixedly connected between each two adjacent hollow support plates 30, and the two ends of each hollow diverter cone 40 are respectively connected to the inner cavity of the two adjacent hollow support plates 30, and the radial positions of the hollow diverter cones 40 are the same and form an annular structure as a whole, so that a gas connecting structure is formed between each hollow support plate 30 and the hollow diverter cone 40, forming the basic framework of the converging and diverting flow path.

[0040] According to an embodiment of the present invention, Figure 2 , 3As shown, the number of each hollow support plate 30 is 4-8, and each hollow support plate 30 is evenly arranged along the circumference and fixedly connected between the outer ring casing 10 and the inner ring casing 20 of the intermediate casing 100 through a high-strength welding process, and the welding area is finely polished and anti-corrosion treated to enhance the durability of the weld. In addition, support plate vents 31 are provided on the left and right sides of each hollow support plate 30 to connect the hollow support plate 30 with the inner cavity of the hollow diverter cone 40, so that each hollow support plate 30 and the hollow diverter cone 40 form a gas communication structure with the inner cavity connected.

[0041] like Figure 2 , 3 As shown, each hollow flow splitter cone 40 is circumferentially distributed between each hollow support plate 30, and each hollow flow splitter cone 40 is a fan-shaped annular structure extending in the circumferential direction, and its two circumferential ends are respectively connected to two adjacent hollow support plates 30, and its interior is a hollow structure and forms a gas flow chamber, and the radial positions of each hollow flow splitter cone 40 are the same and form an annular structure as a whole. Preferably, the leading edge area of ​​each hollow flow splitter cone 40 is designed as an upper and lower double cone structure, and the leading edges of the upper and lower cones intersect to form a sharp leading edge line, and by optimizing the cone angles of the upper and lower cones, for example, the cone angles of the upper and lower cones of the hollow flow splitter cone 40 are respectively constrained to be within the range of 15 to 30 degrees, so as to improve the flow characteristics of the airflow in the leading edge area of ​​the hollow flow splitter cone 40 and reduce the occurrence of airflow separation and turbulence. In addition, the inner wall surface of each hollow diverter cone 40 and hollow support plate 30 is preferably subjected to high-precision polishing treatment so that its surface roughness is controlled below Ra 0.4µm, so as to improve its surface finish and reduce the friction resistance when the airflow passes through, reduce energy loss, and effectively prevent air path blockage caused by impurity deposition or scaling after long-term operation, thereby further improving the air supply efficiency of the air system.

[0042] SS2. Optimization design of air flow path of air system

[0043] An air bleed short pipe 50 is provided on the trailing edge end face of the hollow splitter cone 40 for introducing secondary air from a high-pressure air source of the aircraft engine (e.g., a compressor blade tip) and conveying it to the inner cavity of the hollow splitter cone 40. The length, diameter, number and circumferential distribution position of the air bleed short pipe 50 are determined according to the pressure margin of the air bleed point at the high-pressure air source end and the design requirements of the sealing pressure difference of the engine front bearing cavity, so as to optimize the air bleed efficiency and reduce the air flow loss along the way. Based on the gas connection structure formed by each hollow support plate and the hollow splitter cone, the introduced secondary air is evenly distributed to the inner cavity of each hollow support plate 30 and the hollow splitter cone 40.

[0044] According to an embodiment of the present invention, Figure 3As shown, the air bleed short pipe 50 is used to introduce secondary air from the high-pressure air source of the aircraft engine and transport it to the inner cavity of the hollow diverter cone 40, and then transport the secondary airflow to the inner cavity of each hollow support plate 30 and the inner cavity of the hollow diverter cone 40 based on the gas connection structure, so as to achieve anti-icing and uniform heating of each hollow support plate 30 and the hollow diverter cone 40. Preferably, each air bleed short pipe 50 is evenly distributed along the circumferential direction on the trailing edge end surface of different hollow diverter cones 40, and is sealed and connected to the trailing edge end surface of the hollow diverter cone 40 through a sealing ring, and the length and diameter of the air bleed short pipe 50 are optimized and adjusted according to the actual operating conditions to adapt to different pressure margins and flow requirements of the air bleed point at the high-pressure air source end, meet the cooling, anti-icing and sealing requirements of different parts of the engine, and reduce the airflow loss along the way by optimizing the structural parameters of the air bleed short pipe 50. Improve the air supply efficiency.

[0045] SS3. Optimization design of anti-icing air supply path of hollow diverter cone

[0046] A plurality of diverter cone anti-icing holes 41 connected to the inner cavity of each hollow diverter cone 40 are discretely opened on the upper and lower surfaces near the leading edge thereof for injecting secondary air and forming an attached air film on the upper and lower surfaces of the hollow diverter cone. The number, size, distribution position and injection angle of the diverter cone anti-icing holes 41 are optimized through CFD simulation and according to the geometric shape and airflow characteristics of the hollow diverter cone to ensure that the injected secondary air can evenly cover the upper and lower surfaces of the hollow diverter cone 40.

[0047] According to an embodiment of the present invention, Figure 3 As shown, the diverter cone anti-icing holes 41 are evenly distributed and arranged along the airflow direction, and their number and layout are preferably designed by CFD simulation optimization. The central axis forms a certain angle with the upper and lower surfaces of the hollow diverter cone 40, and the aperture gradually decreases from the inside to the outside. A chamfered structure is provided at the inlet, and a diffusion section design is adopted at the outlet to optimize the flow state of the secondary air in the anti-icing hole, ensuring that the injected secondary air can evenly cover the upper and lower surfaces of the hollow diverter cone 41 to form a stable attached air film to enhance the anti-icing effect.

[0048] SS4. Optimization design of the air supply path of the engine front bearing cavity seal

[0049] An engine front bearing cavity is arranged in the inner ring casing 20 of the intermediate casing 100, and a downstream bearing seat 60 and a matching downstream comb tooth sealing ring 61 as well as an upstream bearing seat 70 and a matching upstream comb tooth sealing ring 71 are arranged in the engine front bearing cavity; a plurality of first vent holes 62 are circumferentially provided on the outer ring surface of the downstream bearing seat 60 for introducing secondary air in the inner cavity of the hollow support plate 30 into the inner cavity of the downstream bearing seat 60; a plurality of second vent holes 63 are circumferentially provided on the inner ring surface of the downstream bearing seat 60 for introducing secondary air in the inner cavity of the downstream bearing seat 60 into the downstream comb tooth sealing ring 61, and A plurality of sealing vents 65 are circumferentially formed on the inner ring surface of the downstream comb teeth sealing ring 61 for supplying secondary air into the downstream sealing comb teeth to achieve sealing of the downstream end of the engine front bearing cavity; a plurality of third vents 64 are circumferentially formed on the front end surface of the downstream bearing seat 60, and the third vents 64 are connected to the upstream bearing seat 70 and the upstream comb teeth sealing ring 71 through an axially extending air supply pipe 66, and a plurality of sealing vents 72 are circumferentially formed on the inner ring surface of the upstream comb teeth sealing ring 71 for supplying secondary air into the upstream comb teeth sealing structure to achieve sealing of the upstream end of the engine front bearing cavity.

[0050] According to an embodiment of the present invention, Figure 3 As shown, the number, diameter and distribution position of the first vent hole 62, the second vent hole 63 and the third vent hole 64 of the downstream bearing seat 60 are designed according to the sealing pressure difference and lubricating oil sealing requirements of the front bearing cavity of the engine, and the first vent hole 62 is evenly distributed along the circumference of the outer ring surface of the downstream bearing seat 60 to ensure that the secondary air is efficiently introduced from the inner cavity of the hollow support plate 30 to the inner cavity of the downstream bearing seat 60, and to reduce the local air flow pressure loss. The sealing vent holes 65 and 72 of the downstream comb tooth sealing ring 61 and the upstream comb tooth sealing ring 71 preferably adopt a tapered flow channel design to improve the secondary air jet effect, the diameter and position of the sealing vent holes 65 and 72 are optimized according to the lubricating oil sealing requirements and airflow distribution characteristics, and the inner walls of the sealing vent holes 65 and 72 are preferably polished to reduce the airflow resistance and prevent scaling and clogging after long-term operation.

[0051] In some preferred examples, the front end face of the downstream bearing seat 60 is fixedly connected to an annular cover plate 67 by a plurality of bolts evenly distributed along the circumference. The annular cover plate 67 is formed with a plurality of bell mouths evenly distributed along the circumference. Each bell mouth corresponds coaxially to the third air vent 64, and each bell mouth is fixedly connected to the corresponding air supply pipe 66 and sealed by an O-ring to transmit the secondary air in the inner cavity of the downstream bearing seat 60 to the upstream bearing seat 70 through the air supply pipe 66, thereby simplifying the structure and improving assembly efficiency.

[0052] SS5. Optimization design of air supply path for low pressure turbine end and inlet cone seal

[0053] A sealing grate 81 corresponding to the upstream grate sealing ring 71 is arranged on the upstream end wall of the low-pressure turbine shaft 80, and an air vent 82 is opened to introduce secondary air into the axis of the low-pressure turbine shaft 80. The airflow in the axis of the low-pressure turbine shaft 80 is evenly distributed through the flow resistance optimization structure. A part of it is transported upstream to the intake cone to form an anti-icing airflow, and the other part is transported downstream to the low-pressure turbine end for sealing and cooling.

[0054] In some preferred examples, the flow path in the axis of the low-pressure turbine shaft 80 adopts a segmented optimization design, the inlet part of the axial flow path is provided with a pressure diffuser structure to reduce the airflow velocity and increase the pressure, the middle part is provided with a flow equalizer to reduce the airflow turbulence and ensure the uniform distribution of the airflow, and the outlet part is provided with a guide diffuser section to optimize the path of the airflow to the low-pressure turbine end and the intake cone, thereby improving the sealing and anti-icing effect. Preferably, the anti-icing airflow of the intake cone is transported upstream through the axis of the low-pressure turbine shaft 80, and anti-icing holes are opened on the surface of the intake cone. The number and distribution position of the anti-icing holes are optimized according to the airflow impact characteristics and icing risk areas under flight conditions to ensure that the anti-icing airflow can cover the surface of the intake cone, and the outlet of the anti-icing hole adopts a diffuser design to enhance the adhesion and stability of the anti-icing airflow.

[0055] The technical principle of the design method of the air flow path of the aero-engine air system of the present invention is as follows: by arranging a hollow support plate and a hollow diverter cone in the intermediate casing to form an annular converging and diverting flow path framework, the secondary air of the high-pressure air source is introduced and evenly distributed to the inner cavity of the support plate and the diverter cone based on the gas connection structure, so as to achieve the coordinated optimization of the internal cooling, anti-icing and sealing functions of the aero-engine. This method significantly improves the uniformity and stability of the air film attached to the surface of the diverter cone by optimizing the geometric design and anti-icing hole layout of the hollow diverter cone, and enhances the anti-icing capability under low temperature conditions; at the same time, according to the sealing and cooling requirements of the front bearing cavity and the low-pressure turbine end, an efficient sealing and cooling air supply path is designed, and the air flow loss along the way is reduced through structures such as vents and tapered flow channels, thereby improving the air supply efficiency and system integration. In addition, the present invention accurately optimizes the key air flow path and the layout of the vent holes based on CFD simulation, ensuring the uniform distribution of the secondary air in the complex flow path, effectively reducing the flow resistance and temperature rise.

[0056] Through the above embodiments, the purpose of the present invention is fully and effectively achieved. Those skilled in the art can understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Although the present invention has been described with respect to the most practical and preferred embodiments currently considered, it should be understood that the present invention is not limited to the disclosed embodiments, and any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A method for designing a flow path for a shunting type bleed air supply system of an aircraft engine, characterized in that: The flow path design method comprises at least the following steps when implemented: SS1. Design and layout of intermediate casing structure A plurality of hollow support plates extending radially are evenly arranged in the circumferential direction in the intermediate casing at the front end of the aircraft engine, and the upper and lower ends of each hollow support plate are respectively connected to the outer ring casing and the inner ring casing of the intermediate casing; a hollow flow dividing cone is fixedly connected between each two adjacent hollow support plates, and the two ends of each hollow flow dividing cone are respectively connected to the inner cavity of the two adjacent hollow support plates, and the radial positions of the hollow flow dividing cones are the same and the whole is formed into an annular structure, so that a gas communication structure is formed between each hollow support plate and the hollow flow dividing cone, forming a basic framework of the converging and diverting flow path; SS2. Optimization design of air flow path of air system An air bleed short pipe is arranged on the trailing edge end surface of at least one hollow diverter cone, for introducing secondary air from the high-pressure air source of the aircraft engine and conveying it to the inner cavity of the hollow diverter cone, and the length, diameter, number and circumferential distribution position of the air bleed short pipe are determined according to the pressure margin of the air bleed point at the high-pressure air source end and the sealing pressure difference design requirements of the engine front bearing cavity, and the introduced secondary air is evenly distributed to the inner cavity of each hollow support plate and the hollow diverter cone based on the gas communication structure formed by each hollow support plate and the hollow diverter cone; SS3. Optimization design of anti-icing air supply path of hollow diverter cone A plurality of diverter cone anti-icing holes connected to the inner cavity of each hollow diverter cone are discretely opened on the upper and lower surfaces near the leading edge of the diverter cone to spray secondary air and form attached air films on the upper and lower surfaces of the hollow diverter cone. The number, size, distribution position and spray angle of the diverter cone anti-icing holes are optimized through CFD simulation and according to the geometric shape and airflow characteristics of the hollow diverter cone to ensure that the sprayed secondary air can evenly cover the upper and lower surfaces of the hollow diverter cone. SS4. Optimization design of the air supply path of the engine front bearing cavity seal An engine front bearing cavity is arranged in the inner ring casing of the intermediate casing, and a downstream bearing seat and a matching downstream comb tooth sealing ring as well as an upstream bearing seat and a matching upstream comb tooth sealing ring are arranged in the engine front bearing cavity; a plurality of first vent holes are arranged along the circumferential direction on the outer ring surface of the downstream bearing seat, so as to introduce the secondary air in the inner cavity of the hollow support plate into the inner cavity of the downstream bearing seat; a plurality of second vent holes are arranged along the circumferential direction on the inner ring surface of the downstream bearing seat, so as to introduce the secondary air in the inner cavity of the downstream bearing seat into the downstream comb tooth sealing ring, and A plurality of sealing vents are provided on the inner ring surface of the sealing ring in the circumferential direction, for supplying secondary air into the downstream sealing grate teeth to achieve sealing of the downstream end of the engine front bearing cavity; a plurality of third vents are provided on the front end surface of the downstream bearing seat in the circumferential direction, and the third vents are connected with the upstream bearing seat and the upstream grate teeth sealing ring through an air supply pipe extending in the axial direction, and a plurality of sealing vents are provided on the inner ring surface of the upstream grate teeth sealing ring in the circumferential direction, for supplying secondary air into the upstream grate teeth sealing structure to achieve sealing of the upstream end of the engine front bearing cavity; SS5. Optimization design of air supply path for low pressure turbine end and inlet cone seal Sealing grate teeth corresponding to the upstream grate teeth sealing ring are arranged on the upstream end wall of the low-pressure turbine shaft, and vents are opened to introduce secondary air into the axis of the low-pressure turbine shaft. The airflow in the axis of the low-pressure turbine shaft is evenly distributed through the flow resistance optimization structure. Part of it is transported upstream to the intake cone to form an anti-icing airflow, and the other part is transported downstream to the low-pressure turbine end for sealing and cooling.

2. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 1, characterized in that: In step SS1, each hollow support plate is evenly arranged along the circumferential direction and fixedly connected between the outer ring casing and the inner ring casing of the intermediate casing through a welding process, and the welding area is finely polished and anti-corrosion treated to enhance the durability of the weld; the leading edge area of ​​each hollow diverter cone is designed as an upper and lower double-conical surface structure, and the leading edges of the upper and lower conical surfaces intersect to form a sharp leading edge line, and the airflow separation and turbulence in the leading edge area of ​​the hollow diverter cone are improved by optimizing the cone angles of the upper and lower conical surfaces.

3. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 1, characterized in that: In step SS1, the inner wall surface of each hollow diverter cone and hollow support plate is polished with high precision to control the surface roughness below Ra 0.4 µm, so as to reduce the friction resistance of the airflow and reduce energy loss, and effectively prevent the air path blockage caused by impurity deposition or scaling after long-term operation.

4. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 1, characterized in that: In step SS2, each air bleed short pipe is evenly distributed along the circumferential direction on the trailing edge end face of different hollow diverter cones, and each air bleed short pipe is sealed and connected to the trailing edge end face of the hollow diverter cone through a sealing ring, and the length and diameter of the air bleed short pipe are adjusted according to the actual operating conditions to adapt to the pressure margin and flow requirements of different air bleed points at the high-pressure gas source end, and the structural parameters of the air bleed short pipe are optimized to reduce the air flow loss along the way.

5. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 1, characterized in that: In step SS3, the anti-icing holes of the diverter cone are evenly distributed and set along the airflow direction. Their number and layout are designed by CFD simulation optimization. The central axis forms a certain angle with the surface of the hollow diverter cone, and the aperture gradually decreases from the inside to the outside. A chamfered structure is provided at the inlet, and a diffusion section design is adopted at the outlet to optimize the flow state of the secondary air in the anti-icing holes, ensuring that the injected secondary air evenly covers the upper and lower surfaces of the hollow diverter cone to form a stable attached air film to enhance the anti-icing effect.

6. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 1, characterized in that: In step SS4, the number, diameter and distribution position of the first air vent, the second air vent and the third air vent of the downstream bearing seat are designed according to the sealing pressure difference and lubricating oil sealing requirements of the front bearing cavity of the engine, and the first air vent is evenly distributed along the circumference of the outer ring surface of the downstream bearing seat to ensure that the airflow is efficiently introduced from the inner cavity of the hollow support plate into the inner cavity of the downstream bearing seat.

7. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 6, characterized in that: In step SS4, the sealing vents of the downstream comb tooth sealing ring and the upstream comb tooth sealing ring adopt a tapered flow channel design to improve the secondary air jet effect. The diameter and position of the sealing vents are optimized according to the lubricating oil sealing requirements and airflow distribution characteristics, and the inner wall of the sealing vents is polished to reduce airflow resistance and prevent scaling and clogging after long-term operation.

8. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 7, characterized in that: In step SS4, the front end face of the downstream bearing seat is fixedly connected to an annular cover plate by multiple bolts evenly distributed along the circumference. The annular cover plate is formed with multiple bell mouths evenly distributed along the circumference. Each bell mouth is coaxially arranged with the corresponding third air vent, and each of the bell mouths is fixedly and sealedly connected to the corresponding air supply pipe.

9. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 1, characterized in that: In step SS5, the flow path inside the axis of the low-pressure turbine shaft is designed in a segmented optimization manner. A diffuser structure is provided at the inlet part of the axial flow path to reduce the airflow velocity and increase the pressure. A flow equalizer is provided in the middle part to reduce airflow turbulence and ensure uniform airflow distribution. A guide diffuser section is provided at the outlet part to optimize the path of airflow delivery to the low-pressure turbine end and the intake cone.

10. The method for designing a flow path for a converging and diverging bleed air supply system of an aircraft engine according to claim 1, characterized in that: In step SS5, the anti-icing airflow of the intake cone is transported upstream through the axis of the low-pressure turbine shaft, and anti-icing holes are opened on the surface of the intake cone. The number and distribution of the anti-icing holes are optimized according to the airflow impact characteristics and icing risk areas under flight conditions to ensure that the anti-icing airflow can cover the surface of the intake cone. The anti-icing hole outlet adopts a diffusion section design to enhance the adhesion and stability of the anti-icing airflow.

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