Air inlet flow pipe and design method and application method thereof

Abstract

The invention provides an air inlet flow pipe and a design method and application method thereof, and belongs to the technical field of aerodynamic acoustic tests. The air inlet flow pipe is used for an aeroacoustic test of an aero-engine and comprises a horn mouth section and a circular pipe section which are communicated, the horn mouth section comprises a similar section, the molded line of the similar section is the same as that of an air inlet channel of the aero-engine, and the circular pipe section is provided with a static pressure measuring section. The distance from the static pressure measurement section to one end of the circular pipe section away from the similar section is greater than or equal to the diameter of the circular pipe section. The similar section of the horn mouth section of the air inlet flow pipe adopts the same molded line as the air inlet channel of the aero-engine, that is, the similar section and the air inlet channel of the aero-engine are the same in design formula, and the similar section is obtained by reducing the proportion, so that the similar section is closer to the actual situation. The test can better simulate and measure far-field acoustic characteristics, and the test precision is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of aerodynamic acoustic testing, and in particular to an air intake flow tube and a design method and an application method thereof. Background Art

[0002] The fan component is one of the main noise sources of aircraft engines, and it is very necessary to conduct aeroacoustic performance test research on it. During the fan test, an intake flow tube is usually installed at the air inlet of the test equipment to ensure the intake quality and measure the intake flow. The intake flow tube consists of a bell section and a circular tube section. The air flows into the bell section through the air inlet of the bell section and flows out through the circular tube section. The circular tube section is used to measure the air flow. Figure 1 As shown, the profile of the bell mouth section in the prior art is a double twisted wire, and is designed according to the following formula:

[0003] r 2 =a 2 cos2α

[0004] Wherein: 0.6D<a<0.8D (D is the flow tube diameter), α=0°~45°.

[0005] Tangent position of the bell mouth section and the circular tube section ( Figure 1 The static pressure measurement section from the O point in the circular pipe segment ( Figure 1 The distance from the static pressure measurement section to the end of the circular pipe section away from the bell-mouth section is L1=(0.2~0.25)D; the length L2≥1.5D from the static pressure measurement section to the end of the circular pipe section away from the bell-mouth section.

[0006] According to the above design requirements, the total length of the circular tube section is L1+L2≥(1.7~1.75)D. At this time, the length of the circular tube section will be much longer than the length of the air inlet of the aircraft engine test piece, and the double-negative curve of the bell mouth section is quite different from the curve of the air inlet. The above reasons will cause the far-field noise directivity to be quite different from the actual ground working conditions in the aeroacoustic test research of the aircraft engine, reducing the test accuracy. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defect of low test accuracy caused by unreasonable design of intake flow tube in aerodynamic and acoustic tests of aircraft engines in the prior art, and to provide an intake flow tube and its design method and application method.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] An air intake flow tube is used for aerodynamic acoustic testing of an aircraft engine. The air intake flow tube comprises a bell-mouth section and a circular tube section which are connected to each other. The bell-mouth section comprises a similar section. The profile of the similar section is the same as the profile of the air intake duct of the aircraft engine. The circular tube section has a static pressure measurement section. The distance from the static pressure measurement section to one end of the circular tube section away from the similar section is greater than or equal to the diameter of the circular tube section.

[0010] In the present scheme, the similar section of the bell-mouth section of the intake flow tube adopts the same profile as the intake duct of the aircraft engine, that is, the design formulas of the two are the same. The similar section is obtained by reducing the proportion, so that the similar section is closer to the actual situation, which is beneficial to improving the test accuracy and avoiding the defect of the bell-mouth section in the traditional method adopting a double-negative line profile, which leads to a large difference from the actual situation; the distance from the static pressure measurement section of the circular tube section of the intake flow tube to the end of the circular tube section far away from the similar section is greater than or equal to the diameter of the circular tube section. Compared with the design requirement of the traditional method that the distance from the static pressure measurement section to the end of the circular tube section far away from the similar section is greater than or equal to 1.5 times the diameter of the circular tube section, the length of the circular tube section of the present invention can be designed to be smaller, so that the test can better simulate and measure the far-field acoustic characteristics, further improving the test accuracy.

[0011] Preferably, the distance from the static pressure measurement section to the connection between the circular tube segment and the similar segment is equal to 0.2 times the diameter of the circular tube segment, and the distance from the static pressure measurement section to the end of the circular tube segment away from the similar segment is equal to the diameter of the circular tube segment.

[0012] In this scheme, the distance from the static pressure measurement section to the connection point between the circular tube section and the similar section takes the minimum distance required by the traditional design. At the same time, the distance from the static pressure measurement section to the end of the circular tube section away from the similar section takes the minimum distance required by this design, so that the length of the circular tube section can be minimized, which is beneficial to reducing the influence of the length of the circular tube section on the aerodynamic acoustic test and improving the test accuracy.

[0013] Preferably, the bell-mouth section further comprises a lip section, the profile of the lip section is an arc, the lip section extends toward the outer peripheral side of the bell-mouth section and is tangentially connected to the air inlet of the similar section.

[0014] In this scheme, the lip section is connected tangentially to the similar section, which is conducive to a smooth transition. The setting of the lip section is conducive to the flow of air into the similar section. Compared with the traditional design method in which the profile of the bell-mouth section is designed as a double twisted curve, the profile of the lip section is designed as an arc, which is simpler and easier to process.

[0015] Preferably, the profile of the lip section is a 1 / 4 arc.

[0016] In this solution, the 1 / 4 arc profile is simple in design and easy to process.

[0017] Preferably, the radius of the circular arc is 0.1 times the diameter of the circular tube segment.

[0018] In this solution, the radius of the arc is taken as 0.1 times the diameter of the circular tube section, which can ensure the air intake while designing the size of the lip section to be smaller, which is beneficial to improving the test accuracy.

[0019] A design method for an intake flow tube, the design method is applicable to the above-mentioned intake flow tube, the design method comprises the following steps:

[0020] Designing the similar section according to the profile of the air inlet of the aircraft engine to obtain the bell-mouth section;

[0021] Design the circular tube segment in such a manner that the distance from the static pressure measurement section to one end of the circular tube segment is greater than or equal to the diameter of the circular tube segment;

[0022] The bell-mouth section is connected to the circular tube section, and the distance from the static pressure measurement section to the end of the circular tube section away from the similar section is greater than or equal to the diameter of the circular tube section.

[0023] In this solution, the flow tube is processed in sections, and then the bell-mouth section and the round tube section are connected, which is beneficial to improving processing efficiency. At the same time, the similar section of the bell-mouth section adopts the same profile as the air intake of the aircraft engine, that is, the design formula of the two is the same. The similar section is obtained by reducing the proportion, so that the similar section is closer to the actual situation, which is beneficial to improving the test accuracy and avoiding the defect of the bell-mouth section using a double-negative line in the traditional method, which is greatly different from the actual situation; the distance from the static pressure measurement section of the round tube section of the intake flow tube to the end of the round tube section away from the similar section is greater than or equal to the diameter of the round tube section. Compared with the design requirement that the distance from the static pressure measurement section to the end of the round tube section away from the similar section is greater than or equal to 1.5 times the diameter of the round tube section in the traditional method, the length of the round tube section of the present invention can be designed to be smaller, so that the test can better simulate and measure the far-field acoustic characteristics, further improving the test accuracy.

[0024] Preferably, the step of designing the circular tube segment according to the distance from the static pressure measurement section to one end of the circular tube segment being greater than or equal to the diameter of the circular tube segment specifically comprises the following steps:

[0025] The circular tube segment is designed according to the distance from the static pressure measurement section to one end of the circular tube segment being equal to the diameter of the circular tube segment and the distance from the static pressure measurement section to the other end of the circular tube segment being equal to 0.2 times the diameter of the circular tube segment.

[0026] In this scheme, the distance from the static pressure measurement section to one end of the circular tube section takes the minimum distance required by this design, and the distance from the static pressure measurement section to the other end of the circular tube section takes the minimum distance required by the traditional design, so that the length of the circular tube section can be minimized, which is beneficial to reducing the influence of the length of the circular tube section on the aerodynamic acoustic test and improving the test accuracy.

[0027] Preferably, the bell mouth section further comprises a lip section, the profile of the lip section is an arc, the lip section extends toward the outer peripheral side of the bell mouth section and is tangentially connected to the air inlet of the similar section;

[0028] The step of designing the similar section according to the profile of the air inlet of the aircraft engine to obtain the bell mouth section also includes the following steps:

[0029] Designing the lip section according to the arc profile;

[0030] The lip section is tangentially connected to the air inlet of the similar section and the lip section is extended toward the outer peripheral side of the bell mouth section.

[0031] In this scheme, compared with the traditional design method in which the profile of the bell mouth section is designed as a double twisted curve, the profile of the lip section is designed as an arc, which is simpler and easier to process. The lip section is tangentially connected to the similar section, which is conducive to a smooth transition.

[0032] Preferably, the profile of the lip section is a 1 / 4 arc;

[0033] The step of designing the lip section according to the arc profile specifically comprises the following steps:

[0034] The lip section is designed according to the profile of a 1 / 4 arc.

[0035] In this solution, the 1 / 4 arc profile is simple in design and easy to process.

[0036] Preferably, the radius of the circular arc is 0.1 times the diameter of the circular tube segment;

[0037] The step of designing the lip section according to the profile of a quarter arc specifically comprises the following steps:

[0038] The circular arc is designed according to the diameter of the circular tube segment whose radius length is 0.1 times.

[0039] In this solution, the radius of the arc is taken as 0.1 times the diameter of the circular tube section, which can ensure the air intake while designing the size of the lip section to be smaller, which is beneficial to improving the test accuracy.

[0040] An application method of an intake flow tube, the application method is applicable to the above-mentioned intake flow tube, and the application method comprises the following steps:

[0041] The air outlet of the intake flow tube is arranged opposite to the intake cone of the test piece of the aircraft engine, so that the distance from the static pressure measurement section to the intake cone is greater than or equal to the diameter of the circular pipe section.

[0042] In this solution, the distance from the static pressure measurement section to the air intake cone is greater than or equal to the diameter of the circular pipe section, which can ensure that the air flow at the static pressure measurement section is not affected by the air intake cone and improve the test accuracy.

[0043] The positive and progressive effects of the present invention are:

[0044] In the present invention, the similar section of the bell-mouth section of the intake flow tube adopts the same profile as the intake duct of the aircraft engine, that is, the design formulas of the two are the same. The similar section is obtained by reducing the proportion, so that the similar section is closer to the actual situation, which is beneficial to improving the test accuracy and avoiding the defect of the bell-mouth section in the traditional method adopting a double-loop profile line, which is greatly different from the actual situation; the distance from the static pressure measurement section of the circular tube section of the intake flow tube to the end of the circular tube section away from the similar section is greater than or equal to the diameter of the circular tube section. Compared with the design requirement of the traditional method that the distance from the static pressure measurement section to the end of the circular tube section away from the similar section is greater than or equal to 1.5 times the diameter of the circular tube section, the length of the circular tube section of the present invention can be designed to be smaller, so that the test can better simulate and measure the far-field acoustic characteristics, further improving the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a profile design drawing of an intake flow tube in the prior art.

[0046] Figure 2 The figure is a profile design drawing of an intake flow tube according to an embodiment of the present invention.

[0047] Figure 3 FIG. 1 is a positional relationship diagram of an intake cone and an intake flow tube according to an embodiment of the present invention.

[0048] Figure 4 The figure is a flow chart of a method for designing an intake flow tube according to an embodiment of the present invention.

[0049] Figure 5 FIG. 4 is a typical static pressure distribution diagram of an intake flow tube according to an embodiment of the present invention.

[0050] Figure 6 The figure is a comparison diagram of the far-field noise directivity of an intake flow tube according to an embodiment of the present invention and an intake flow tube of a conventional design.

[0051] Description of reference numerals:

[0052] Bell mouth section 1

[0053] Similar paragraph 11

[0054] Lip section 12

[0055] Round pipe section 2 DETAILED DESCRIPTION

[0056] The present invention will be described more clearly and completely below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiments.

[0057] See also Figure 2 The present embodiment provides an intake flow tube for aerodynamic acoustic test of an aircraft engine. The intake flow tube includes a bell mouth section 1 and a circular tube section 2 which are connected to each other. The bell mouth section 1 includes a similar section 11. The profile of the similar section 11 is the same as the profile of the intake duct of the aircraft engine. The circular tube section 2 has a static pressure measurement section ( Figure 2 The distance from the static pressure measurement section to the end of the circular pipe section 2 away from the similar section 11 ( Figure 2 L5 in the figure is greater than or equal to the diameter of the circular tube section 2. The similar section 11 of the bell mouth section 1 of the intake flow tube adopts the same profile as the intake duct of the aircraft engine, that is, the design formulas of the two are the same, and the similar section 11 is obtained by reducing the proportion, so that the similar section 11 is closer to the actual situation, which is conducive to improving the test accuracy and avoiding the defect that the bell mouth section 1 adopts a double-negative profile in the traditional method, which leads to a large difference from the actual situation; the distance from the static pressure measurement section of the circular tube section 2 of the intake flow tube to the end of the circular tube section 2 far away from the similar section 11 is greater than or equal to the diameter of the circular tube section 2. Compared with the design requirement that the distance from the static pressure measurement section to the end of the circular tube section 2 far away from the similar section 11 is greater than or equal to 1.5 times the diameter of the circular tube section 2 in the traditional method, the length of the circular tube section 2 of the present invention can be designed to be smaller, so that the test can better simulate and measure the far-field acoustic characteristics, and further improve the test accuracy.

[0058] Specifically, in this embodiment, the circular pipe segment 2 has a constant diameter, which is determined according to the diameter of the fan inlet flow channel; the length of the circular pipe segment 2 and the selection of the static pressure measurement section can be determined by aerodynamic calculation, and the selection criteria of the static pressure measurement section are: the flow in this section is axial flow, which can be judged by streamlines or static pressure distribution; the above calculation methods are all existing technologies and will not be repeated here.

[0059] In this embodiment, the static pressure measurement section is from the connection between the circular pipe section 2 and the similar section 11 ( Figure 2The distance from the static pressure measurement section to the end of the circular tube segment 2 far from the similar section 11 is equal to 0.2 times the diameter of the circular tube segment 2, and the distance from the static pressure measurement section to the end of the circular tube segment 2 far from the similar section 11 is equal to the diameter of the circular tube segment 2. The distance from the static pressure measurement section to the connection between the circular tube segment 2 and the similar section 11 takes the minimum distance required by the traditional design, and the distance from the static pressure measurement section to the end of the circular tube segment 2 far from the similar section 11 takes the minimum distance required by the present design, so that the length of the circular tube segment 2 can be reduced to the maximum extent, which is conducive to reducing the influence of the length of the circular tube segment 2 on the aerodynamic acoustic test and improving the test accuracy.

[0060] In this embodiment, the bell mouth section 1 further includes a lip section 12, the profile of the lip section 12 is an arc, the lip section 12 extends toward the outer peripheral side of the bell mouth section 1 and is tangently connected to the air inlet of the similar section 11, and the tangent point is as follows: Figure 2 As shown in point A in FIG. The lip section 12 is tangentially connected to the similar section 11, which is conducive to a smooth transition. The setting of the lip section 12 is conducive to the air flowing into the similar section 11. Compared with the traditional design method in which the profile of the bell mouth section 1 is designed as a double twisted curve, the profile of the lip section 12 is designed as an arc, which is simpler and convenient for processing.

[0061] In this embodiment, the profile of the lip section 12 is a 1 / 4 arc, and the profile design is simple and convenient for processing.

[0062] In this embodiment, the radius of the arc is 0.1 times the diameter of the circular tube section 2, so that the size of the lip section 12 can be designed to be smaller while ensuring air intake, which is beneficial to improving the test accuracy.

[0063] See also Figure 3This embodiment also provides a design method for an intake flow tube, which is applicable to the above-mentioned intake flow tube, and the design method includes the following steps: designing a similar section 11 according to the profile of the intake duct of the aircraft engine to obtain a bell mouth section 1; designing a round tube section 2 according to the distance from the static pressure measurement section to one end of the round tube section 2 being greater than or equal to the diameter of the round tube section 2; connecting the bell mouth section 1 with the round tube section 2, and making the distance from the static pressure measurement section to the end of the round tube section 2 away from the similar section 11 greater than or equal to the diameter of the round tube section 2. Processing the flow tube in sections and then connecting the bell mouth section 1 and the round tube section 2 is conducive to improving processing efficiency. At the same time, the similar section 11 of the bell-mouth section 1 adopts the same profile as the air intake duct of the aircraft engine, that is, the design formulas of the two are the same. The similar section 11 is obtained by reducing the proportion, so that the similar section 11 is closer to the actual situation, which is beneficial to improving the test accuracy and avoiding the defect of the bell-mouth section 1 in the traditional method that adopts a double-loop profile, which is significantly different from the actual situation; the distance from the static pressure measurement section of the circular tube section 2 of the intake flow tube to the end of the circular tube section 2 away from the similar section 11 is greater than or equal to the diameter of the circular tube section 2. Compared with the design requirement of the traditional method that the distance from the static pressure measurement section to the end of the circular tube section 2 away from the similar section 11 is greater than or equal to 1.5 times the diameter of the circular tube section 2, the length of the circular tube section 2 of the present invention can be designed to be smaller, so that the test can better simulate and measure the far-field acoustic characteristics, further improving the test accuracy.

[0064] In this embodiment, the step of designing the circular tube segment 2 according to the distance from the static pressure measurement section to one end of the circular tube segment 2 being greater than or equal to the diameter of the circular tube segment 2 specifically includes the following steps: designing the circular tube segment 2 according to the distance from the static pressure measurement section to one end of the circular tube segment 2 being equal to the diameter of the circular tube segment 2 and the distance from the static pressure measurement section to the other end of the circular tube segment 2 being equal to 0.2 times the diameter of the circular tube segment 2. The distance from the static pressure measurement section to one end of the circular tube segment 2 takes the minimum distance required by this design, and the distance from the static pressure measurement section to the other end of the circular tube segment 2 takes the minimum distance required by the traditional design, so that the length of the circular tube segment 2 can be reduced to the maximum extent, which is conducive to reducing the influence of the length of the circular tube segment 2 on the aerodynamic acoustic test and improving the test accuracy.

[0065] In this embodiment, the bell-mouth section 1 also includes a lip section 12, the profile of the lip section 12 is an arc, the lip section 12 extends to the outer peripheral side of the bell-mouth section 1 and is tangentially connected to the air inlet of the similar section 11; the step of designing the similar section 11 according to the profile of the air inlet of the aircraft engine to obtain the bell-mouth section 1 also includes the following steps: designing the lip section 12 according to the arc profile; tangentially connecting the lip section 12 to the air inlet of the similar section 11 and extending the lip section 12 to the outer peripheral side of the bell-mouth section 1. Compared with the traditional design method in which the profile of the bell-mouth section 1 is designed as a double twisted curve, the profile of the lip section 12 is designed as an arc, which is simpler and easier to process. The lip section 12 is tangentially connected to the similar section 11, which is conducive to smooth transition.

[0066] In this embodiment, the profile of the lip segment 12 is a 1 / 4 arc; the steps of designing the lip segment 12 according to the arc profile specifically include the following steps: designing the lip segment 12 according to the profile of the 1 / 4 arc. The profile of the 1 / 4 arc is simple to design and easy to process.

[0067] In this embodiment, the radius of the arc is 0.1 times the diameter of the circular tube segment 2; the step of designing the lip segment 12 according to the profile of the 1 / 4 arc specifically includes the following steps: designing the arc according to the radius of the arc being 0.1 times the diameter of the circular tube segment 2. The radius of the arc is 0.1 times the diameter of the circular tube segment 2, so that the size of the lip segment 12 can be designed to be smaller while ensuring air intake, which is conducive to improving the test accuracy.

[0068] Specifically, in this embodiment, after the preliminary design of the intake flow tube is completed, the far-field noise directivity calculation, intensity calculation and iteration can be performed: that is, the directivity of the noise of the concerned frequency in the far field and the aerodynamics and intensity of the intake flow tube are calculated. If the directivity does not match the ground working conditions or the aerodynamics and intensity do not meet the requirements, the geometric dimensions of the similar section 11 can be adjusted and recalculated until the directivity results, aerodynamics, and intensity meet the requirements. The above-mentioned noise directivity calculation, intensity calculation and iterative calculation methods are all existing technologies and will not be repeated here.

[0069] This embodiment also provides an application method of an intake flow tube, which is applicable to the above-mentioned intake flow tube, see Figure 3 The position relationship diagram of the intake cone and the intake flow tube, the application method includes the following steps: the air outlet of the intake flow tube is arranged relative to the intake cone 101 of the test piece of the aircraft engine, so that the distance from the static pressure measurement section to the intake cone is greater than or equal to the diameter of the circular tube section 2. The distance from the static pressure measurement section to the intake cone is greater than or equal to the diameter of the circular tube section 2, which can ensure that the air flow at the static pressure measurement section is not affected by the intake cone, thereby improving the test accuracy.

[0070] The intake flow tube of this embodiment is simulated in Fluent software according to the above design method, wherein the design parameters of the intake flow tube are as follows: the radius R of the lip section 12 is 0.1D, the length L3 of the similar section 11 is 1D, the cross-sectional diameter D of the circular tube section 2 is 0.6m, the distance L4 from the static pressure measurement section to the connection between the circular tube section 2 and the similar section 11 is 0.2D, the distance L5 from the static pressure measurement section to the end of the circular tube section 2 away from the similar section 11 is 1D, and the airflow Mach number of the static pressure measurement section is 0.6.

[0071] Figure 4The following is a typical static pressure distribution diagram of the intake flow tube obtained by simulation calculation based on the above model. In the figure, point D is the vertex of the intake cone, point E is the location of the static pressure measurement section, and the distance between the two is equal to the diameter of the circular tube section 2. From the simulation results, it can be seen that when the distance from the static pressure measurement section to the intake cone is equal to the diameter of the circular tube section 2, it can ensure that the air flow at the static pressure measurement section is not affected by the intake cone, thereby improving the test accuracy.

[0072] Figure 5 This is a comparison diagram of the far-field noise directivity of the intake flow tube of this embodiment and the intake flow tube of traditional design obtained after simulation calculation based on the above model. Directivity refers to the distribution of the noise sound pressure level at the far-field observation angle, usually distributed on an arc with the center of the inlet of the measured fan as the center. The horizontal axis in the figure is the observation angle, and the vertical axis is the far-field sound pressure level. It can be found from the figure that the design of the intake flow tube of this embodiment can adjust the far-field directivity. After adjustment, the use of this flow tube can achieve consistency between the directivity and the angle where the peak of the fan forward noise is located. Figure 5 Each grid on the horizontal axis represents 15°, and each grid on the vertical axis represents 10dB.

[0073] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. An air intake flow tube for aerodynamic acoustic testing of an aircraft engine, the air intake flow tube comprising a bell mouth section and a circular tube section connected to each other, characterized in that: The bell-mouth section includes a similar section, the profile of the similar section is the same as the profile of the air inlet of the aircraft engine, the circular tube section has a static pressure measurement section, and the distance from the static pressure measurement section to one end of the circular tube section away from the similar section is greater than or equal to the diameter of the circular tube section.

2. The intake flow tube according to claim 1, characterized in that: The distance from the static pressure measurement section to the connection between the circular tube segment and the similar segment is equal to 0.2 times the diameter of the circular tube segment, and the distance from the static pressure measurement section to the end of the circular tube segment away from the similar segment is equal to the diameter of the circular tube segment.

3. The intake flow tube according to claim 1, characterized in that: The bell mouth section also includes a lip section, the profile of the lip section is an arc, the lip section extends toward the outer peripheral side of the bell mouth section and is tangentially connected to the air inlet of the similar section.

4. The intake flow tube according to claim 3, characterized in that: The profile of the lip section is a 1 / 4 arc.

5. The intake flow tube according to claim 3, characterized in that: The radius of the circular arc is 0.1 times the diameter of the circular tube segment.

6. A method for designing an intake flow tube, characterized in that: The design method is applicable to the intake flow tube according to any one of claims 1 to 5, and the design method comprises the following steps: Designing the similar section according to the profile of the air inlet of the aircraft engine to obtain the bell-mouth section; Design the circular tube segment in such a manner that the distance from the static pressure measurement section to one end of the circular tube segment is greater than or equal to the diameter of the circular tube segment; The bell-mouth section is connected to the circular tube section, and the distance from the static pressure measurement section to the end of the circular tube section away from the similar section is greater than or equal to the diameter of the circular tube section.

7. The method for designing an intake flow tube according to claim 6, characterized in that: The step of designing the circular tube segment according to the distance from the static pressure measurement section to one end of the circular tube segment being greater than or equal to the diameter of the circular tube segment specifically comprises the following steps: The circular tube segment is designed according to the distance from the static pressure measurement section to one end of the circular tube segment being equal to the diameter of the circular tube segment and the distance from the static pressure measurement section to the other end of the circular tube segment being equal to 0.2 times the diameter of the circular tube segment.

8. The method for designing an intake flow tube according to claim 6, characterized in that: The bell mouth section also includes a lip section, the profile of the lip section is an arc, the lip section extends toward the outer peripheral side of the bell mouth section and is tangentially connected to the air inlet of the similar section; The step of designing the similar section according to the profile of the air inlet of the aircraft engine to obtain the bell mouth section also includes the following steps: Designing the lip section according to the arc profile; The lip section is tangentially connected to the air inlet of the similar section and the lip section is extended toward the outer peripheral side of the bell mouth section.

9. The method for designing an intake flow tube according to claim 8, characterized in that: The profile of the lip section is a 1 / 4 arc; The step of designing the lip section according to the arc profile specifically comprises the following steps: The lip section is designed according to the profile of a 1 / 4 arc.

10. The method for designing an intake flow tube according to claim 9, characterized in that: The radius of the circular arc is 0.1 times the diameter of the circular tube segment; The step of designing the lip section according to the profile of a quarter arc specifically comprises the following steps: The circular arc is designed according to the diameter of the circular tube segment whose radius length is 0.1 times.

11. An application method of an intake flow tube, characterized in that: The application method is applicable to the intake flow tube according to any one of claims 1 to 5, and the application method comprises the following steps: The air outlet of the intake flow tube is arranged opposite to the intake cone of the test piece of the aircraft engine, so that the distance from the static pressure measurement section to the intake cone is greater than or equal to the diameter of the circular pipe section.

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