Aero-engine outer culvert pneumatic high-efficiency design method and system

Abstract

The invention relates to the field of aero-engine aerodynamic design, and discloses an aero-engine outer culvert aerodynamic high-efficiency design method and system. By establishing a typical aero-engine complete machine performance analysis model, a mapping relation between an outer culvert total pressure recovery coefficient and main performance parameters of an aero-engine is determined; determining an outer culvert total pressure recovery coefficient threshold according to design requirements; secondly, key factors influencing the external culvert total pressure recovery coefficient are recognized by conducting external culvert total pressure recovery coefficient influence factor sensitivity analysis, a method for reducing external culvert aerodynamic loss is specifically provided, and an external culvert efficiency comprehensive evaluation method from six dimensions of manufacturability, weight, cost, reliability, thrust and oil consumption is established; and finally, the outer culvert performance optimization means with the efficiency improvement amount larger than 0 is determined as the final outer culvert performance design method, the aerodynamic high-efficiency design requirement of the outer culvert of the aero-engine can be met, and effective support is provided for the ultrahigh-efficiency design of the outer culvert of the aero-engine.

Description

Technical Field

[0001] The invention relates to the field of aerodynamic design of aircraft engines, and discloses a method and system for high-efficiency design of aerodynamics of an aircraft engine outer duct. Background Art

[0002] The outer duct casing connects the engine's intermediate casing and the turbine rear bearing, and forms an outer duct airflow channel with the compressor casing, main combustion chamber casing, and turbine casing. The inlet of the outer duct airflow channel is arranged at the outlet of the intermediate casing diverter ring, and the outer duct airflow outlet is arranged at the force transmission point between the turbine rear bearing ducts. The outer duct airflow is not only an important component of the thrust generation of aircraft engines, but the outer duct casing structure is also an important load-bearing component that transmits loads and supports external accessories.

[0003] The aerodynamic performance of the aircraft engine's outer duct is an important part of the aircraft engine design. The results of its design performance directly affect the overall performance of the aircraft engine, and have the most direct impact on the thrust and fuel consumption rate of the aircraft engine. At present, the military's small bypass ratio engines mainly use the mixed exhaust after the inner and outer ducts are mixed. The aerodynamic design level of the outer duct mainly affects the engine's thrust and afterburner ignition performance. The inner and outer ducts of aircraft engines with medium and above bypass ratios use separate exhaust schemes. The aerodynamic design level of the outer duct mainly affects the engine's thrust and fuel consumption rate. For aircraft engines that pursue economic indicators, the aerodynamic design level of the outer duct directly affects the market competitiveness of engine products.

[0004] With the development of aircraft engine related technologies, the design of aircraft engine related structures has become more sophisticated and complex. At the same time, since the outer duct airflow is a high-quality refrigerant in the engine operation, a heat exchanger and other related functional structures are arranged in the outer duct flow channel. In addition, in order to meet the regulation of the axial force of the high-pressure rotor of the aircraft engine, high-temperature and high-pressure gas is even discharged into the outer duct flow channel. The above reasons have led to the traditional outer duct aerodynamic design experience being unable to meet the performance design requirements.

[0005] The aerodynamic analysis of the duct found that aerodynamic losses are mainly related to the engine's duct structure design, the structural layout of the duct flow passage, the bypass ratio, the airflow rate and the intake angle. However, there is no unified effective prediction and solution method for the existing aero-engine duct aerodynamic design, and specific solutions are often used for different engine models, which makes it impossible to form a general technology for ultra-efficient duct aerodynamic design. Summary of the invention

[0006] The purpose of the present invention is to provide a method and system for high-efficiency aerodynamic design of aircraft engine outer ducts, which can quickly determine the final outer duct performance design method, meet the high-efficiency design requirements of aircraft engine outer duct aerodynamics, and provide effective support for the ultra-high-efficiency design of aircraft engine outer ducts.

[0007] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0008] A method for designing an aerodynamically efficient aircraft engine outer casing, comprising:

[0009] S1. Analyze and obtain a mapping relationship between the total pressure recovery coefficient of the culvert and the main performance of the aircraft engine according to an aircraft engine performance analysis model, wherein the main performance includes thrust and fuel consumption rate;

[0010] S2. Determine the priority value of the main performance of the whole machine according to the performance design requirements of the aircraft engine, and then determine the threshold value of the total pressure recovery coefficient of the outer duct according to the whole machine performance matching and the mapping relationship;

[0011] S3. Conduct three-dimensional aerodynamic performance analysis on a typical culvert aerodynamic model to determine the influencing factors of the culvert total pressure recovery coefficient and the sensitivity of each influencing factor to the culvert total pressure recovery coefficient. The influencing factors include the culvert aerodynamic inlet sudden expansion loss, the culvert airflow flow wall separation loss, the culvert test lead and the sensed part blockage loss, and the aerodynamic vortex blockage loss.

[0012] S4. According to the sensitivity of various influencing factors to the total pressure recovery coefficient of the outer culvert, different technical means are used to improve the total pressure recovery coefficient of the outer culvert; the technical means include the deflection angle method of the intermediate casing diverter ring, the three-stage design method of the outer culvert, the method of adding a flow channel isolation cover, and the casing transition angle control method; among which:

[0013] The intermediate casing splitter ring deflection angle method guides the outer casing airflow to deflect downward by adjusting the downward deflection angle of the intermediate casing splitter ring, so as to enhance the impact on the aerodynamic vortex;

[0014] The outer shroud three-section design method is used to design the outer shroud casing into an outer shroud casing front section, an outer shroud casing middle section, and an outer shroud casing rear section. The outer shroud casing front section structure starts at the intermediate casing outlet and ends near the compressor casing outlet in the axial direction. The outer shroud casing front section is designed as a straight section or a flow channel deflection preset angle value to suppress the outer shroud airflow from flowing in the high radius direction to suppress the formation of aerodynamic vortices.

[0015] The method of adding a flow channel isolation cover is used to design a flow channel isolation cover structure between the outer duct flow channels, the flow channel isolation cover structure starts at the outlet of the intermediate casing splitter ring structure and ends near the turbine casing in the axial direction; the flow channel isolation cover divides the outer duct flow channel into two parts, an inner flow channel and an outer flow channel, the flow channel isolation cover is provided with an air inlet hole connecting the inner flow channel and the outer flow channel at a position close to the inlet, and the flow channel isolation cover is provided with an exhaust hole connecting the inner flow channel and the outer flow channel at a position close to the outlet; the outer duct airflow mainly flows through the outer duct of the outer duct, and part of the airflow enters the inner flow channel through the air inlet hole of the flow channel isolation cover and merges into the outer flow channel through the exhaust hole, so as to suppress the formation of aerodynamic vortices in the outer duct flow channel;

[0016] The casing transition angle control method is used to control the deflection angle between any adjacent profiles of the outer casing to below 8°, so as to suppress the flow wall separation loss of the outer casing airflow;

[0017] S5. Carry out culvert aerodynamic efficiency analysis and key technology selection based on the engine's culvert total pressure recovery coefficient threshold, calculate the culvert aerodynamic efficiency and analyze the efficiency improvement from six aspects: manufacturability, weight, cost, reliability, thrust and fuel consumption, and determine the culvert performance optimization method with an efficiency improvement greater than 0 as the final culvert performance design method.

[0018] Further, in step S4, when the deflection angle method of the intermediate casing diverter ring is used to adjust the downward deflection angle of the intermediate casing diverter ring, the downward deflection angle of the diverter ring does not exceed 5°.

[0019] Furthermore, in step S4, the preset angle value of the flow passage deflection of the front section of the outer casing does not exceed 3°.

[0020] Furthermore, the aerodynamic efficiency of the outer tube in step S5 is I according to I=k MF E Mf +k M E M +k P E P +k R E R +k F E F +k sfc E sfc The improvement of the aerodynamic efficiency of the outer duct is obtained by analysis according to ΔI = (1-I / 5) × 100%; where k MF is the manufacturing contribution rate coefficient, E Mf is the manufacturing contribution rate, E Mf =1-ΔM f / M f , ,M f is the manufacturing contribution, the manufacturing contribution M f Including pass rate or working hours, ΔM f The amount of change contributed to manufacturability; k M is the mass contribution coefficient, E M is the quality contribution rate, E M =1-ΔM / M, M is the total mass of the aircraft engine outer casing design, ΔM is the total mass change caused by the use of the intermediate casing diverter ring deflection angle method, the outer casing three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k P is the cost contribution rate coefficient, E P is the cost contribution rate, E P=1-ΔP / P, P is the design cost of aircraft engine culvert manufacturing, ΔP is the manufacturing cost change caused by the use of the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k R is the reliability contribution rate coefficient, E R is the reliability contribution rate, E R =1-ΔR / R, R is the reliability coefficient of the aircraft engine culvert design, the reliability coefficient R is obtained by strength analysis, ΔR is the reliability coefficient change caused by the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover addition method or the casing transition angle control method; k F is the thrust contribution coefficient, E F is the thrust contribution rate, E F =1+ΔF / F, F is the design thrust of the aircraft engine, ΔF is the thrust change caused by the use of the intermediate casing diverter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k sfc is the fuel consumption rate contribution coefficient, E sfc is the fuel consumption rate contribution rate, E sfc =1-Δsfc / sfc, sfc is the design fuel consumption rate of the aircraft engine, and Δsfc is the change in fuel consumption caused by the intermediate casing diverter ring deflection angle method, the outer casing three-section design method, the addition of the flow channel isolation cover method or the casing transition angle control method.

[0021] Furthermore, in step S3, the blockage loss of the test lead and the sensed part in the outer duct can be reduced by adjusting the cross section of the sensed part to be streamlined and optimizing the test layout and routing scheme.

[0022] In order to achieve the above technical effects, the present invention also provides an aircraft engine outer duct aerodynamic high efficiency design system, which is used to implement the aircraft engine outer duct aerodynamic high efficiency design method; comprising:

[0023] A first analysis module is used to analyze and obtain a mapping relationship between the total pressure recovery coefficient of the culvert and the main performance of the aircraft engine according to the aircraft engine performance analysis model, wherein the main performance includes thrust and fuel consumption rate;

[0024] A threshold determination module is used to determine the priority value of the main performance of the whole machine according to the performance design requirements of the whole machine of the aircraft engine, and then determine the threshold value of the total pressure recovery coefficient of the outer duct according to the whole machine performance matching and the mapping relationship;

[0025] A sensitivity analysis module is used to conduct a three-dimensional aerodynamic performance analysis on a typical culvert aerodynamic model, determine the influencing factors of the culvert total pressure recovery coefficient, and the sensitivity of each influencing factor to the culvert total pressure recovery coefficient, the influencing factors include the culvert aerodynamic inlet sudden expansion loss, the culvert airflow flow wall separation loss, the culvert test lead and the sensed part blockage loss, and the aerodynamic vortex blockage loss;

[0026] The culvert total pressure recovery coefficient adjustment module is used to improve the culvert total pressure recovery coefficient by using different technical means according to the sensitivity of various influencing factors to the culvert total pressure recovery coefficient; the technical means include the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover addition method and the casing transition angle control method; among which:

[0027] The intermediate casing splitter ring deflection angle method guides the outer casing airflow to deflect downward by adjusting the downward deflection angle of the intermediate casing splitter ring, so as to enhance the impact on the aerodynamic vortex;

[0028] The outer shroud three-section design method is used to design the outer shroud casing into an outer shroud casing front section, an outer shroud casing middle section, and an outer shroud casing rear section. The outer shroud casing front section structure starts at the intermediate casing outlet and ends near the compressor casing outlet in the axial direction. The outer shroud casing front section is designed as a straight section or a flow channel deflection preset angle value to suppress the outer shroud airflow from flowing in the high radius direction to suppress the formation of aerodynamic vortices.

[0029] The method of adding a flow channel isolation cover is used to design a flow channel isolation cover structure between the outer duct flow channels, the flow channel isolation cover structure starts at the outlet of the intermediate casing splitter ring structure and ends near the turbine casing in the axial direction; the flow channel isolation cover divides the outer duct flow channel into two parts, an inner flow channel and an outer flow channel, the flow channel isolation cover is provided with an air inlet hole connecting the inner flow channel and the outer flow channel at a position close to the inlet, and the flow channel isolation cover is provided with an exhaust hole connecting the inner flow channel and the outer flow channel at a position close to the outlet; the outer duct airflow mainly flows through the outer duct of the outer duct, and part of the airflow enters the inner flow channel through the air inlet hole of the flow channel isolation cover and merges into the outer flow channel through the exhaust hole, so as to suppress the formation of aerodynamic vortices in the outer duct flow channel;

[0030] The casing transition angle control method is used to control the deflection angle between any adjacent profiles of the outer casing to below 8°, so as to suppress the flow wall separation loss of the outer casing airflow;

[0031] The discrimination module is used to carry out culvert aerodynamic efficiency analysis and key technology selection according to the threshold of the engine's culvert total pressure recovery coefficient, and to calculate the culvert aerodynamic efficiency and analyze the efficiency improvement from six aspects: manufacturability, weight, cost, reliability, thrust and fuel consumption rate, and to determine the culvert performance optimization means with an efficiency improvement greater than 0 as the final culvert performance design method.

[0032] Furthermore, in the outer casing total pressure recovery coefficient adjustment module, when the intermediate casing diverter ring deflection angle method is used to adjust the downward deflection angle of the intermediate casing diverter ring, the downward deflection angle of the diverter ring does not exceed 5°.

[0033] Furthermore, in the outer culvert total pressure recovery coefficient adjustment module, a preset angle value of the flow passage deflection of the front section of the outer culvert casing does not exceed 3°.

[0034] Furthermore, the external aerodynamic efficiency in the discrimination module is I according to I=k MF E Mf +k M E M +k P E P +k R E R +k F E F +k sfc E sfc The improvement of the aerodynamic efficiency of the outer duct is obtained by analysis according to ΔI = (1-I / 5) × 100%; where k MF is the manufacturing contribution rate coefficient, E Mf is the manufacturing contribution rate, E Mf =1-ΔM f / M f , ,M f is the manufacturing contribution, the manufacturing contribution M f Including pass rate or working hours, ΔM f The amount of change contributed to manufacturability; k M is the mass contribution coefficient, E M is the quality contribution rate, E M =1-ΔM / M, M is the total mass of the aircraft engine outer casing design, ΔM is the total mass change caused by the use of the intermediate casing diverter ring deflection angle method, the outer casing three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k P is the cost contribution rate coefficient, E P is the cost contribution rate, E P =1-ΔP / P, P is the design cost of aircraft engine culvert manufacturing, ΔP is the manufacturing cost change caused by the use of the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k R is the reliability contribution rate coefficient, E R is the reliability contribution rate, E R =1-ΔR / R, R is the reliability coefficient of the aircraft engine culvert design, the reliability coefficient R is obtained by strength analysis, ΔR is the reliability coefficient change caused by the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover addition method or the casing transition angle control method; kF is the thrust contribution coefficient, E F is the thrust contribution rate, E F =1+ΔF / F, F is the design thrust of the aircraft engine, ΔF is the thrust change caused by the use of the intermediate casing diverter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k sfc is the fuel consumption rate contribution coefficient, E sfc is the fuel consumption rate contribution rate, E sfc =1-Δsfc / sfc, sfc is the design fuel consumption rate of the aircraft engine, and Δsfc is the change in fuel consumption caused by the intermediate casing diverter ring deflection angle method, the outer casing three-section design method, the addition of the flow channel isolation cover method or the casing transition angle control method.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention identifies the key factors affecting the total pressure recovery coefficient of the culvert by conducting a sensitivity analysis of the factors affecting the total pressure recovery coefficient of the culvert, proposes a targeted method to reduce the aerodynamic loss of the culvert, and establishes a comprehensive evaluation method for the culvert performance from six dimensions of manufacturability, weight, cost, reliability, thrust and fuel consumption rate, and finally determines the culvert performance optimization means with an efficiency improvement greater than 0 as the final culvert performance design method, which can meet the high-efficiency design requirements of the aerodynamics of the culvert of an aircraft engine and provide effective support for the ultra-high-efficiency design of the culvert of an aircraft engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart of the method for designing aerodynamic high efficiency of aero-engine outer duct in Embodiment 1 or 2;

[0037] Figure 2 It is a schematic diagram of the installation structure of the intermediate casing, the diverter ring structure and the outer casing in Example 1 or 2;

[0038] Figure 3 It is a schematic diagram of the installation structure of the flow channel isolation cover in the outer casing in Example 1 or 2;

[0039] Figure 4 This is a schematic diagram of the structure of the three-section outer casing in Example 1;

[0040] Figure 5 The structural block diagram of the aero-engine outer duct aerodynamic high efficiency design system in Example 1;

[0041] Among them, 1. intermediate casing; 101. diverter ring structure; 2. outer casing; 201. front section of outer casing; 202. middle section of outer casing; 203. rear section of outer casing; 204. inner flow channel; 205. outer flow channel; 3. flow channel isolation cover; 301. air inlet hole; 302. exhaust hole; 4. first analysis module; 5. threshold determination module; 6. sensitivity analysis module; 7. outer casing total pressure recovery coefficient adjustment module; 8. discrimination module. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the embodiments and drawings. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0043] Example 1

[0044] See also Figure 1-Figure 5 , a method for designing aerodynamically efficient aircraft engine outer casing, comprising:

[0045] S1. Analyze and obtain a mapping relationship between the total pressure recovery coefficient of the culvert and the main performance of the aircraft engine according to an aircraft engine performance analysis model, wherein the main performance includes thrust and fuel consumption rate;

[0046] S2. According to the aircraft engine performance design requirements, determine the priority value of the main performance of the whole machine (such as thrust priority, fuel consumption rate priority, etc.), and then determine the threshold value of the total pressure recovery coefficient of the outer duct according to the whole machine performance matching and the mapping relationship;

[0047] S3. Conduct three-dimensional aerodynamic performance analysis on a typical culvert aerodynamic model to determine the influencing factors of the culvert total pressure recovery coefficient and the sensitivity of each influencing factor to the culvert total pressure recovery coefficient. The influencing factors include the culvert aerodynamic inlet sudden expansion loss, the culvert airflow flow wall separation loss, the culvert test lead and the sensed part blockage loss, and the aerodynamic vortex blockage loss.

[0048] S4. According to the sensitivity of various influencing factors to the total pressure recovery coefficient of the outer culvert, different technical means are used to improve the total pressure recovery coefficient of the outer culvert; the technical means include the deflection angle method of the intermediate casing 1 diverter ring, the three-stage design method of the outer culvert, the method of adding a flow channel isolation cover 3, and the casing transition angle control method; among which:

[0049] See also Figure 2 The deflection angle method of the intermediate casing 1 diverter ring guides the outer casing airflow downward by adjusting the downward deflection angle of the intermediate casing 1 diverter ring, so as to enhance the impact on the aerodynamic vortex;

[0050] See also Figure 4The three-section design method of the outer shroud is used to design the outer shroud casing 2 into a front section 201, a middle section 202, and a rear section 203. The front section 201 structure starts at the outlet of the intermediate casing 1 and ends near the outlet of the compressor casing in the axial direction. The front section 201 is designed as a straight section or a flow channel deflection preset angle value to suppress the outer shroud airflow from flowing in the high radius direction to suppress the formation of aerodynamic vortices.

[0051] See also Figure 3 The method of adding a flow channel isolation cover 3 is used to design a flow channel isolation cover 3 structure between the outer duct flow channel, the flow channel isolation cover 3 structure starts from the outlet of the diverter ring structure 101 of the intermediate casing 1, and ends near the turbine casing in the axial direction; the flow channel isolation cover 3 divides the outer duct flow channel into two parts, the inner flow channel 204 and the outer flow channel 205, the flow channel isolation cover 3 is provided with an air inlet 301 connecting the inner flow channel 204 and the outer flow channel 205 at a position close to the inlet, and the flow channel isolation cover 3 is provided with an exhaust hole 302 connecting the inner flow channel 204 and the outer flow channel 205 at a position close to the outlet; the outer duct airflow mainly flows through the outer duct 205, and part of the airflow enters the inner flow channel 204 from the air inlet 301 of the flow channel isolation cover 3 and merges into the outer flow channel 205 from the exhaust hole 302, so as to suppress the formation of aerodynamic vortices in the outer duct flow channel;

[0052] The casing transition angle control method is used to control the deflection angle between any adjacent profiles of the outer casing 2 to below 8°, so as to suppress the flow wall separation loss of the outer casing airflow;

[0053] S5. Carry out culvert aerodynamic efficiency analysis and key technology selection based on the engine's culvert total pressure recovery coefficient threshold, calculate the culvert aerodynamic efficiency and analyze the efficiency improvement from six aspects: manufacturability, weight, cost, reliability, thrust and fuel consumption, and determine the culvert performance optimization method with an efficiency improvement greater than 0 as the final culvert performance design method.

[0054] In this embodiment, by establishing a typical aircraft engine performance analysis model and adopting quantitative analysis, an analysis of the influence of the culvert total pressure recovery coefficient on the main performance of the aircraft engine is carried out; through the matching result of the aircraft engine whole machine performance analysis model, the threshold of the culvert total pressure recovery coefficient, that is, the design upper and lower thresholds of the culvert total pressure recovery coefficient are finally determined; then, by conducting a sensitivity analysis of the influencing factors of the culvert total pressure recovery coefficient, the key factors affecting the culvert total pressure recovery coefficient are identified, and a targeted method for reducing the aerodynamic loss of the culvert is proposed, and a comprehensive evaluation method for the culvert efficiency from six dimensions of manufacturability, weight, cost, reliability, thrust and fuel consumption is established, and finally the culvert performance optimization means with an efficiency improvement greater than 0 is determined as the final culvert performance design method, which can meet the high-efficiency design requirements of aircraft engine culvert aerodynamics and provide effective support for the ultra-high efficiency design of aircraft engine culverts.

[0055] In this embodiment, the aerodynamic efficiency of the outer by-pass is I according to I = k MF E Mf +k M E M +k P E P +k R E R +k F E F +k sfc E sfc The improvement of the aerodynamic efficiency of the outer duct is obtained by analysis according to ΔI = (1-I / 5) × 100%; where k MF is the manufacturing contribution rate coefficient, E Mf is the manufacturing contribution rate, E Mf =1-ΔM f / M f , ,M f is the manufacturing contribution, the manufacturing contribution M f Including pass rate or working hours, ΔM f The amount of change contributed to manufacturability; k M is the mass contribution coefficient, E M is the quality contribution rate, E M =1-ΔM / M, M is the total mass of the aircraft engine outer culvert design, ΔM is the total mass change caused by the use of the intermediate casing 1 splitter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method; k P is the cost contribution rate coefficient, E P is the cost contribution rate, E P =1-ΔP / P, P is the design cost of aircraft engine culvert manufacturing, ΔP is the manufacturing cost change caused by the use of the intermediate casing 1 splitter ring deflection angle method, the culvert three-stage design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method; k R is the reliability contribution rate coefficient, E R is the reliability contribution rate, E R =1-ΔR / R, R is the reliability coefficient of the aircraft engine culvert design, the reliability coefficient R is obtained by strength analysis, ΔR is the reliability coefficient change caused by the intermediate casing 1 splitter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover 3 method or the casing transfer angle control method; k F is the thrust contribution coefficient, E F is the thrust contribution rate, E F =1+ΔF / F, F is the design thrust of the aircraft engine, ΔF is the thrust change caused by the intermediate casing 1 splitter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method; k sfc is the fuel consumption rate contribution coefficient, Esfc is the fuel consumption rate contribution rate, E sfc =1-Δsfc / sfc, sfc is the design fuel consumption rate of the aircraft engine, Δsfc is the change in fuel consumption rate caused by the intermediate casing 1 diverter ring deflection angle method, the outer culvert three-section design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method.

[0056] Based on the same inventive concept, this embodiment also provides an aircraft engine outer by-pass aerodynamic high-efficiency design system, including:

[0057] The first analysis module 4 is used to analyze and obtain the mapping relationship between the total pressure recovery coefficient of the culvert and the main performance of the aircraft engine according to the aircraft engine performance analysis model, and the main performance includes thrust and fuel consumption rate;

[0058] The threshold determination module 5 is used to determine the priority value of the main performance of the whole machine according to the performance design requirements of the whole machine of the aircraft engine, and then determine the threshold value of the total pressure recovery coefficient of the outer duct according to the whole machine performance matching and the mapping relationship;

[0059] Sensitivity analysis module 6 is used to carry out three-dimensional aerodynamic performance analysis on a typical culvert aerodynamic model, determine the influencing factors of the culvert total pressure recovery coefficient, and the sensitivity of each influencing factor to the culvert total pressure recovery coefficient, wherein the influencing factors include the culvert aerodynamic inlet sudden expansion loss, the culvert airflow flow wall separation loss, the culvert test lead and the sensed part blockage loss, and the aerodynamic vortex blockage loss;

[0060] The culvert total pressure recovery coefficient adjustment module 7 is used to improve the culvert total pressure recovery coefficient by using different technical means according to the sensitivity of various influencing factors to the culvert total pressure recovery coefficient; the technical means include the intermediate casing 1 diverter ring deflection angle method, the culvert three-stage design method, the method of adding the flow channel isolation cover 3 and the casing transfer angle control method; wherein:

[0061] The deflection angle method of the intermediate casing 1 splitter ring guides the outer casing airflow downward by adjusting the downward deflection angle of the splitter ring of the intermediate casing 1, so as to enhance the impact on the aerodynamic vortex;

[0062] The three-section design method of the outer shroud is used to design the outer shroud casing 2 into a front section 201, a middle section 202, and a rear section 203. The front section 201 structure starts at the outlet of the intermediate casing 1 and ends near the outlet of the compressor casing in the axial direction. The front section 201 is designed as a straight section or a flow channel deflection preset angle value to suppress the outer shroud airflow from flowing in the high radius direction to suppress the formation of aerodynamic vortices.

[0063] The method of adding a flow channel isolation cover 3 is used to design a flow channel isolation cover 3 structure between the outer duct flow channel, the flow channel isolation cover 3 structure starts from the outlet of the diverter ring structure 101 of the intermediate casing 1, and ends near the turbine casing in the axial direction; the flow channel isolation cover 3 divides the outer duct flow channel into two parts, the inner flow channel 204 and the outer flow channel 205, the flow channel isolation cover 3 is provided with an air inlet 301 connecting the inner flow channel 204 and the outer flow channel 205 at a position close to the inlet, and the flow channel isolation cover 3 is provided with an exhaust hole 302 connecting the inner flow channel 204 and the outer flow channel 205 at a position close to the outlet; the outer duct airflow mainly flows through the outer duct 205 of the outer duct, and part of the airflow enters the inner flow channel 204 through the air inlet 301 of the flow channel isolation cover 3 and merges into the outer flow channel 205 through the exhaust hole 302, so as to suppress the formation of aerodynamic vortices in the outer duct flow channel;

[0064] The casing transition angle control method is used to control the deflection angle between any adjacent profiles of the outer casing 2 to below 8°, so as to suppress the flow wall separation loss of the outer casing airflow;

[0065] The judgment module 8 is used to carry out the aerodynamic efficiency analysis of the culvert and the selection of key technologies according to the threshold of the total pressure recovery coefficient of the culvert of the engine, and to calculate the aerodynamic efficiency of the culvert and analyze the efficiency improvement from six aspects of manufacturability, weight, cost, reliability, thrust and fuel consumption rate, and to determine the culvert performance optimization means with the efficiency improvement greater than 0 as the final culvert performance design method.

[0066] Example 2

[0067] See also Figure 1-Figure 4 , a method for designing aerodynamically efficient aircraft engine outer casing, comprising:

[0068] S1. Analyze and obtain a mapping relationship between the total pressure recovery coefficient of the culvert and the main performance of the aircraft engine according to an aircraft engine performance analysis model, wherein the main performance includes thrust and fuel consumption rate;

[0069] In this embodiment, the threshold identification of the total pressure recovery coefficient of the culvert is first carried out. The total pressure recovery coefficient of the culvert is the main parameter for evaluating the performance design of the culvert. The result of the aerodynamic design performance of the culvert directly affects the overall performance of the aircraft engine, and has the most direct impact on the thrust and fuel consumption rate of the aircraft engine. However, for different types of engines, the better the design of the aerodynamic performance of the culvert is, the more beneficial it is to the overall performance of the engine. It is necessary to carry out the threshold analysis of the total pressure recovery coefficient of the culvert. This embodiment establishes a typical aircraft engine performance analysis model and uses quantitative analysis to carry out the analysis of the influence of the total pressure recovery coefficient of the culvert on the main performance of the aircraft engine. The results are as follows:

[0070] The total pressure loss of the outer duct increases by 1% and the fuel consumption is y=1.1709x 3 +0.0874x 2 +0.0825x

[0071] For every 1% increase in the total pressure loss of the outer duct, the thrust y=-16395x 3 -1143.4x 2 -1135.9x.

[0072] S2. According to the aircraft engine performance design requirements, determine the priority value of the main performance of the whole machine (such as thrust priority, fuel consumption rate priority, etc.), and then determine the threshold value of the total pressure recovery coefficient of the outer duct according to the whole machine performance matching and the mapping relationship;

[0073] In this embodiment, the total pressure recovery coefficient threshold of the ductile iron (including the design upper and lower limits of the total pressure recovery coefficient of the ductile iron) is finally determined through the matching results of the aircraft engine whole machine performance analysis model.

[0074] S3. Conduct three-dimensional aerodynamic performance analysis on a typical culvert aerodynamic model to determine the influencing factors of the culvert total pressure recovery coefficient and the sensitivity of each influencing factor to the culvert total pressure recovery coefficient. The influencing factors include the culvert aerodynamic inlet sudden expansion loss, the culvert airflow flow wall separation loss, the culvert test lead and the sensed part blockage loss, and the aerodynamic vortex blockage loss.

[0075] In this embodiment, a sensitivity analysis of the factors affecting the total pressure recovery coefficient of the culvert is carried out. The typical culvert structure consists of a culvert front casing and a culvert rear casing. By establishing a typical culvert aerodynamic model, performance analysis is carried out to identify the factors affecting the total pressure recovery coefficient of the culvert. Numerical simulation results show that the parameters affecting the aerodynamic performance of the culvert mainly include the aerodynamic inlet sudden expansion loss of the culvert, the wall separation loss of the airflow flow in the culvert, the blockage loss of the test lead and the sensed part in the culvert (for the blockage loss of the test lead and the sensed part in the culvert, the blockage loss is reduced by adjusting the cross-section of the sensed part to be streamlined and optimizing the test layout and routing scheme), aerodynamic vortex blockage loss, and blockage loss caused by the regulating mechanism and various pipelines. The sensitivity of various influencing factors to the total pressure recovery coefficient of the culvert was identified by the control variable method, and the specific results are as follows:

[0076] Aerodynamic vortex blockage loss>Sudden expansion loss of aerodynamic inlet of the outer duct>Collision loss of test leads and sensitive parts in the outer duct>Collision loss caused by regulating mechanism and various pipelines>Separation loss of airflow wall of the outer duct>Others.

[0077] S4. According to the sensitivity of various influencing factors to the total pressure recovery coefficient of the outer culvert, different technical means are used to improve the total pressure recovery coefficient of the outer culvert; the technical means include the deflection angle method of the intermediate casing 1 diverter ring, the three-stage design method of the outer culvert, the method of adding a flow channel isolation cover 3, and the casing transition angle control method; among which:

[0078] See also Figure 2The deflection angle method of the diverter ring of the intermediate casing 1 guides the outer airflow downward by adjusting the downward deflection angle of the diverter ring of the intermediate casing 1, so as to enhance the impact on the aerodynamic vortex and reduce the range of action of the aerodynamic vortex; in this embodiment, when the deflection angle of the diverter ring of the intermediate casing 1 is adjusted by the deflection angle method of the diverter ring of the intermediate casing 1, the downward deflection angle of the diverter ring does not exceed 5°.

[0079] See also Figure 4 The three-section design method of the outer duct is used to design the outer duct casing 2 into a front section 201, a middle section 202, and a rear section 203. The front section 201 structure starts at the outlet of the intermediate casing 1 and ends near the outlet of the compressor casing in the axial direction. The front section 201 is designed as a straight section or a preset angle value of the flow channel deflection. In this embodiment, the preset angle value of the flow channel deflection of the front section 201 does not exceed 3°, which inhibits the outer duct airflow from flowing in the direction of high radius to inhibit the formation of aerodynamic vortices; the middle section 202 and the front section 201 are deflected along the flow channel at an appropriate angle, and the deflection angle is strictly controlled to be below 8° to avoid a large airflow separation and ensure that the flow area between the outer duct casing 2 and the combustion chamber casing is not reduced. The rear section 203 of the outer duct casing 2 of the three-section design method is designed as a straight section connected to the middle section 202. The advantage of this method is that the front section 201 of the three-stage design method is designed as a straight section or a small angle deflection of the flow channel, which can effectively control the direction of the outer duct airflow and effectively suppress the range of action of the aerodynamic vortex. At the same time, compared with the traditional two-stage design method of the outer duct, it can effectively reduce the overall weight of the outer duct casing 2, while reducing the height of the structural parts passing through the outer duct flow channel, thereby improving the structural reliability, and will not cause additional problems.

[0080] See also Figure 3 The method of adding a flow channel isolation cover 3 is used to design a flow channel isolation cover 3 structure between the outer duct flow channel, the flow channel isolation cover 3 structure starts from the outlet of the diverter ring structure 101 of the intermediate casing 1, and ends near the turbine casing in the axial direction; the flow channel isolation cover 3 divides the outer duct flow channel into two parts, an inner flow channel 204 and an outer flow channel 205, the flow channel isolation cover 3 is provided with an air inlet hole 301 connecting the inner flow channel 204 and the outer flow channel 205 at a position close to the inlet, and the flow channel isolation cover 3 is provided with an exhaust hole 302 connecting the inner flow channel 204 and the outer flow channel 205 at a position close to the outlet; the outer duct airflow mainly flows through the outer duct 205 of the outer duct, and part of the airflow enters the inner flow channel 204 through the air inlet hole 301 of the flow channel isolation cover 3 and merges into the outer flow channel 205 through the exhaust hole 302; due to the effect of the flow channel isolation cover 3 structure, the aerodynamic vortex of the outer duct flow channel cannot be formed, and the flows of the two flow paths do not interfere with each other, and the blockage loss caused by the aerodynamic vortex can be completely realized. The advantage of this method is that by adding the flow channel isolation cover 3 structure, blockage caused by aerodynamic vortices can be effectively avoided. However, the disadvantage of this solution is that the flow channel isolation cover 3 structure and its related structures are added, the structure is complex, the engine weight cost is increased, and the structural reliability is reduced.

[0081] In this embodiment, the sudden expansion loss airflow is caused by the sudden expansion of the aerodynamic area of ​​the outer duct from the outlet of the intermediate casing splitter ring. By changing the downward deflection angle of the splitter ring, adopting the outer duct three-stage design method and adding the flow channel isolation cover 3 structure, the area expansion ratio can be reduced to achieve the purpose of reducing the sudden expansion loss.

[0082] The casing transition angle control method is used to control the deflection angle between any adjacent profiles of the outer casing 2 to below 8°, so as to suppress the flow wall separation loss of the outer casing airflow.

[0083] S5. Carry out culvert aerodynamic efficiency analysis and key technology selection based on the culvert total pressure recovery coefficient threshold of the engine, calculate the culvert aerodynamic efficiency and analyze the efficiency improvement from six aspects: manufacturability, weight, cost, reliability, thrust and fuel consumption, and determine the culvert performance optimization method with an efficiency improvement greater than 0 as the final culvert performance design method;

[0084] The aerodynamic efficiency of the external bypass in this embodiment is I according to I=k MF E Mf +k M E M +k P E P +k R E R +k F E F +k sfc E sfc The improvement of the aerodynamic efficiency of the outer duct is obtained by analysis according to ΔI = (1-I / 5) × 100%; where k MF is the manufacturing contribution rate coefficient, E Mf is the manufacturing contribution rate, E Mf =1-ΔM f / M f , ,M f is the manufacturing contribution, the manufacturing contribution M f Including pass rate or working hours, ΔM f The amount of change contributed to manufacturability; k M is the mass contribution coefficient, E M is the quality contribution rate, E M =1-ΔM / M, M is the total mass of the aircraft engine outer culvert design, ΔM is the total mass change caused by the use of the intermediate casing 1 splitter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method; k P is the cost contribution rate coefficient, E P is the cost contribution rate, E P=1-ΔP / P, P is the design cost of aircraft engine culvert manufacturing, ΔP is the manufacturing cost change caused by the use of the intermediate casing 1 splitter ring deflection angle method, the culvert three-stage design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method; k R is the reliability contribution rate coefficient, E R is the reliability contribution rate, E R =1-ΔR / R, R is the reliability coefficient of the aircraft engine culvert design, the reliability coefficient R is obtained by strength analysis, ΔR is the reliability coefficient change caused by the intermediate casing 1 splitter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover 3 method or the casing transfer angle control method; k F is the thrust contribution coefficient, E F is the thrust contribution rate, E F =1+ΔF / F, F is the design thrust of the aircraft engine, ΔF is the thrust change caused by the intermediate casing 1 splitter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method; k sfc is the fuel consumption rate contribution coefficient, E sfc is the fuel consumption rate contribution rate, E sfc =1-Δsfc / sfc, sfc is the design fuel consumption rate of the aircraft engine, Δsfc is the change in fuel consumption rate caused by the intermediate casing 1 diverter ring deflection angle method, the outer culvert three-section design method, the addition of the flow channel isolation cover 3 method or the casing transition angle control method.

[0085] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing aerodynamically efficient aircraft engine outer casing, characterized in that: include: S1. Analyze and obtain a mapping relationship between the total pressure recovery coefficient of the culvert and the main performance of the aircraft engine according to an aircraft engine performance analysis model, wherein the main performance includes thrust and fuel consumption rate; S2. Determine the priority value of the main performance of the whole machine according to the performance design requirements of the aircraft engine, and then determine the threshold value of the total pressure recovery coefficient of the outer duct according to the whole machine performance matching and the mapping relationship; S3. Conduct three-dimensional aerodynamic performance analysis on a typical culvert aerodynamic model to determine the influencing factors of the culvert total pressure recovery coefficient and the sensitivity of each influencing factor to the culvert total pressure recovery coefficient. The influencing factors include the culvert aerodynamic inlet sudden expansion loss, the culvert airflow flow wall separation loss, the culvert test lead and the sensed part blockage loss, and the aerodynamic vortex blockage loss. S4. According to the sensitivity of various influencing factors to the total pressure recovery coefficient of the outer culvert, different technical means are used to improve the total pressure recovery coefficient of the outer culvert; the technical means include the deflection angle method of the intermediate casing diverter ring, the three-stage design method of the outer culvert, the method of adding a flow channel isolation cover, and the casing transition angle control method; among which: The intermediate casing splitter ring deflection angle method guides the outer casing airflow to deflect downward by adjusting the downward deflection angle of the intermediate casing splitter ring, so as to enhance the impact on the aerodynamic vortex; The outer shroud three-section design method is used to design the outer shroud casing into an outer shroud casing front section, an outer shroud casing middle section, and an outer shroud casing rear section. The outer shroud casing front section structure starts at the intermediate casing outlet and ends near the compressor casing outlet in the axial direction. The outer shroud casing front section is designed as a straight section or a flow channel deflection preset angle value to suppress the outer shroud airflow from flowing in the high radius direction to suppress the formation of aerodynamic vortices. The method of adding a flow channel isolation cover is used to design a flow channel isolation cover structure between the outer duct flow channels, the flow channel isolation cover structure starts at the outlet of the intermediate casing splitter ring structure and ends near the turbine casing in the axial direction; the flow channel isolation cover divides the outer duct flow channel into two parts, an inner flow channel and an outer flow channel, the flow channel isolation cover is provided with an air inlet hole connecting the inner flow channel and the outer flow channel at a position close to the inlet, and the flow channel isolation cover is provided with an exhaust hole connecting the inner flow channel and the outer flow channel at a position close to the outlet; the outer duct airflow mainly flows through the outer duct of the outer duct, and part of the airflow enters the inner flow channel through the air inlet hole of the flow channel isolation cover and merges into the outer flow channel through the exhaust hole, so as to suppress the formation of aerodynamic vortices in the outer duct flow channel; The casing transition angle control method is used to control the deflection angle between any adjacent profiles of the outer casing to below 8°, so as to suppress the flow wall separation loss of the outer casing airflow; S5. Carry out culvert aerodynamic efficiency analysis and key technology selection based on the engine's culvert total pressure recovery coefficient threshold, calculate the culvert aerodynamic efficiency and analyze the efficiency improvement from six aspects: manufacturability, weight, cost, reliability, thrust and fuel consumption, and determine the culvert performance optimization method with an efficiency improvement greater than 0 as the final culvert performance design method.

2. The method for designing aerodynamically efficient aircraft engine outer duct according to claim 1, characterized in that: In step S4, when the deflection angle method of the intermediate casing diverter ring is used to adjust the downward deflection angle of the intermediate casing diverter ring, the downward deflection angle of the diverter ring does not exceed 5°.

3. The method for designing aerodynamically efficient aircraft engine outer duct according to claim 1, characterized in that: In step S4, the preset angle value of the flow passage deflection of the front section of the outer casing does not exceed 3°.

4. The method for designing aerodynamically efficient aircraft engine outer duct according to claim 1, characterized in that: The aerodynamic efficiency of the outer tube in step S5 is I according to I=k MF E Mf +k M E M +k P E P +k R E R +k F E F +k sfc E sfc The improvement of the aerodynamic efficiency of the outer duct is obtained by analysis according to ΔI = (1-I / 5) × 100%; where k MF is the manufacturing contribution rate coefficient, E Mf is the manufacturing contribution rate, E Mf =1-ΔM f / M f , ,M f is the manufacturing contribution, the manufacturing contribution M f Including pass rate or working hours, ΔM f The amount of change contributed to manufacturability; k M is the mass contribution coefficient, E M is the quality contribution rate, E M =1-ΔM / M, M is the total mass of the aircraft engine outer casing design, ΔM is the total mass change caused by the use of the intermediate casing diverter ring deflection angle method, the outer casing three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k p is the cost contribution rate coefficient, E P is the cost contribution rate, E P =1-ΔP / P, P is the design cost of aircraft engine culvert manufacturing, ΔP is the manufacturing cost change caused by the use of the intermediate casing splitter ring deflection angle method, the culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k R is the reliability contribution rate coefficient, E R is the reliability contribution rate, E R =1-ΔR / R, R is the reliability coefficient of the aircraft engine culvert design, the reliability coefficient R is obtained by strength analysis, ΔR is the reliability coefficient change caused by the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover addition method or the casing transition angle control method; k F is the thrust contribution coefficient, E F is the thrust contribution rate, E F =1+ΔF / F, F is the design thrust of the aircraft engine, ΔF is the thrust change caused by the use of the intermediate casing diverter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k sfc is the fuel consumption rate contribution coefficient, E sfc is the fuel consumption rate contribution rate, E sfc =1-Δsfc / sfc, sfc is the design fuel consumption rate of the aircraft engine, and Δsfc is the change in fuel consumption caused by the intermediate casing diverter ring deflection angle method, the outer casing three-section design method, the addition of the flow channel isolation cover method or the casing transition angle control method.

5. The method for designing aerodynamically efficient aircraft engine outer duct according to claim 1, characterized in that: In step S3, the blockage loss of the test lead and the sensed part in the outer duct can be reduced by adjusting the cross section of the sensed part to be streamlined and optimizing the test layout and routing scheme.

6. An aircraft engine duct aerodynamic high efficiency design system, used to implement the aircraft engine duct aerodynamic high efficiency design method according to claim 1; characterized in that: include: A first analysis module is used to analyze and obtain a mapping relationship between the total pressure recovery coefficient of the culvert and the main performance of the aircraft engine according to the aircraft engine performance analysis model, wherein the main performance includes thrust and fuel consumption rate; A threshold determination module is used to determine the priority value of the main performance of the whole machine according to the performance design requirements of the whole machine of the aircraft engine, and then determine the threshold value of the total pressure recovery coefficient of the outer duct according to the whole machine performance matching and the mapping relationship; A sensitivity analysis module is used to conduct a three-dimensional aerodynamic performance analysis on a typical culvert aerodynamic model, determine the influencing factors of the culvert total pressure recovery coefficient, and the sensitivity of each influencing factor to the culvert total pressure recovery coefficient, the influencing factors include the culvert aerodynamic inlet sudden expansion loss, the culvert airflow flow wall separation loss, the culvert test lead and the sensed part blockage loss, and the aerodynamic vortex blockage loss; The culvert total pressure recovery coefficient adjustment module is used to improve the culvert total pressure recovery coefficient by using different technical means according to the sensitivity of various influencing factors to the culvert total pressure recovery coefficient; the technical means include the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover addition method and the casing transition angle control method; among which: The intermediate casing splitter ring deflection angle method guides the outer casing airflow to deflect downward by adjusting the downward deflection angle of the intermediate casing splitter ring, so as to enhance the impact on the aerodynamic vortex; The outer shroud three-section design method is used to design the outer shroud casing into an outer shroud casing front section, an outer shroud casing middle section, and an outer shroud casing rear section. The outer shroud casing front section structure starts at the intermediate casing outlet and ends near the compressor casing outlet in the axial direction. The outer shroud casing front section is designed as a straight section or a flow channel deflection preset angle value to suppress the outer shroud airflow from flowing in the high radius direction to suppress the formation of aerodynamic vortices. The method of adding a flow channel isolation cover is used to design a flow channel isolation cover structure between the outer duct flow channels, the flow channel isolation cover structure starts at the outlet of the intermediate casing splitter ring structure and ends near the turbine casing in the axial direction; the flow channel isolation cover divides the outer duct flow channel into two parts, an inner flow channel and an outer flow channel, the flow channel isolation cover is provided with an air inlet hole connecting the inner flow channel and the outer flow channel at a position close to the inlet, and the flow channel isolation cover is provided with an exhaust hole connecting the inner flow channel and the outer flow channel at a position close to the outlet; the outer duct airflow mainly flows through the outer duct of the outer duct, and part of the airflow enters the inner flow channel through the air inlet hole of the flow channel isolation cover and merges into the outer flow channel through the exhaust hole, so as to suppress the formation of aerodynamic vortices in the outer duct flow channel; The casing transition angle control method is used to control the deflection angle between any adjacent profiles of the outer casing to below 8°, so as to suppress the flow wall separation loss of the outer casing airflow; The discrimination module is used to carry out culvert aerodynamic efficiency analysis and key technology selection according to the threshold of the engine's culvert total pressure recovery coefficient, and to calculate the culvert aerodynamic efficiency and analyze the efficiency improvement from six aspects: manufacturability, weight, cost, reliability, thrust and fuel consumption rate, and to determine the culvert performance optimization means with an efficiency improvement greater than 0 as the final culvert performance design method.

7. The aerodynamic high efficiency design system for aircraft engine outer duct according to claim 6, characterized in that: In the outer culvert total pressure recovery coefficient adjustment module, when the intermediate casing diverter ring deflection angle method is used to adjust the downward deflection angle of the intermediate casing diverter ring, the downward deflection angle of the diverter ring does not exceed 5°.

8. The aerodynamic high-efficiency design system for aircraft engine outer duct according to claim 6, characterized in that: In the outer culvert total pressure recovery coefficient adjustment module, the preset angle value of the flow channel deflection of the front section of the outer culvert casing does not exceed 3°.

9. The aerodynamic high efficiency design system for aircraft engine outer duct according to claim 6, characterized in that: The external aerodynamic efficiency in the discrimination module is I according to I=k MF E Mf +k M E M +k P E P +k R E R +k F E F +k sfc E sfc The improvement of the aerodynamic efficiency of the outer duct is obtained by analysis according to ΔI = (1-I / 5) × 100%; where k MF is the manufacturing contribution rate coefficient, E Mf is the manufacturing contribution rate, E Mf =1-ΔM f / M f , ,M f is the manufacturing contribution, the manufacturing contribution M f Including pass rate or working hours, ΔM f The amount of change contributed to manufacturability; k M is the mass contribution coefficient, E M is the quality contribution rate, E M =1-ΔM / M, M is the total mass of the aircraft engine outer casing design, ΔM is the total mass change caused by the use of the intermediate casing diverter ring deflection angle method, the outer casing three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k P is the cost contribution rate coefficient, E P is the cost contribution rate, E P =1-ΔP / P, P is the design cost of aircraft engine culvert manufacturing, ΔP is the manufacturing cost change caused by the use of the intermediate casing splitter ring deflection angle method, the culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k R is the reliability contribution rate coefficient, E R is the reliability contribution rate, E R =1-ΔR / R, R is the reliability coefficient of the aircraft engine culvert design, the reliability coefficient R is obtained by strength analysis, ΔR is the reliability coefficient change caused by the intermediate casing diverter ring deflection angle method, the culvert three-stage design method, the flow channel isolation cover addition method or the casing transition angle control method; k F is the thrust contribution coefficient, E F is the thrust contribution rate, E F =1+ΔF / F, F is the design thrust of the aircraft engine, ΔF is the thrust change caused by the use of the intermediate casing diverter ring deflection angle method, the outer culvert three-stage design method, the addition of the flow channel isolation cover method or the casing transition angle control method; k sfc is the fuel consumption rate contribution coefficient, E sfc is the fuel consumption rate contribution rate, E sfc =1-Δsfc / sfc, sfc is the design fuel consumption rate of the aircraft engine, and Δsfc is the change in fuel consumption caused by the intermediate casing diverter ring deflection angle method, the outer casing three-section design method, the addition of the flow channel isolation cover method or the casing transition angle control method.

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