Helicopter air inlet channel capable of being opened and closed in turnover mode and design method

Abstract

The invention provides a helicopter air inlet channel capable of being opened and closed in a turnover mode and a design method. The air inlet channel comprises an upper section (6), a lower section (7) and a hydraulic supporting rod. The upper end of the upper section (6) is in contact with air and serves as an air inlet channel inlet (1), and a rubber ring is arranged at the lower end; the upper end of the lower section (7) is used for making contact with a rubber ring, and the lower end serves as an air inlet channel outlet (4) and communicates with an air inlet of an engine. The fixed end of the hydraulic supporting rod is arranged on an engine body in an engine compartment, the movable end of the hydraulic supporting rod is connected with the upper section (6), during maintenance, the movable end of the hydraulic supporting rod drives the upper section (6) to rotate to expose the upper end of the lower section (7), and during non-maintenance, the movable end of the hydraulic supporting rod drives the rubber ring of the upper section (6) to extrude the upper end of the lower section (7) to form the L-shaped airflow channel (5). Through the sectional and turnover opening and closing structure appearance design, the daily maintenance requirement of the engine is met.

Description

Technical Field

[0001] This invention belongs to the field of helicopter aerodynamics and aerodynamic design, specifically relating to a flip-open helicopter air intake and its design method. Background Technology

[0002] Conventional helicopter air intakes are typically located at the front or sides of the fuselage, with no obstructions in front, resulting in minimal interference with the airflow field. This reduces the aerodynamic requirements for the air intake, allowing for a shorter intake to meet the engine's intake requirements in terms of total pressure loss and pressure distortion. Furthermore, the shorter intake length makes routine maintenance tasks such as cleaning and dust removal simple and easy to perform.

[0003] However, for helicopters with a three-engine configuration, the third engine is usually located behind the main gearbox, which blocks the air intake and causes significant interference with the airflow field, severely affecting the engine's air intake efficiency. Summary of the Invention

[0004] This invention provides a flip-open helicopter air intake and its design method. It is a method for optimizing the air intake design based on the structure and installation position of a turboshaft engine. This method combines numerical simulation and fluid dynamic analysis to ensure that the air intake provides efficient and stable air supply to the engine.

[0005] The first aspect of the present invention provides a flip-open helicopter air intake, comprising: an upper section 6, a lower section 7, and a hydraulic strut; The upper end of the upper section 6 is in contact with the air and serves as the air intake 1, while the lower end is equipped with a rubber ring. The upper end of the lower section 7 is used to contact the rubber ring, and the lower end serves as the air intake outlet 4, which is connected to the engine air intake. The fixed end of the hydraulic strut is located on the engine compartment, and the movable end is connected to the upper section 6. During maintenance, the movable end of the hydraulic strut drives the upper section 6 to rotate, exposing the upper end of the lower section 7. When not under maintenance, the movable end of the hydraulic strut causes the rubber ring of the upper section 6 to press against the upper end of the lower section 7, forming an L-shaped airflow channel 5.

[0006] Optionally, a lip 3 is provided at the upper air intake inlet 1 of the upper section 6; The lip 3 is connected to the fuselage skin; During maintenance, the movable end of the hydraulic strut causes the upper section 6 and part of the skin at the lip 3 to rotate together.

[0007] Optionally, the air intake 1 is rectangular in shape, with the four sharp corners rounded off, and the radius of the rounded corners is between 75mm and 100mm.

[0008] Optionally, the area of ​​the air intake 1 is 4 to 5 times the area of ​​the air intake outlet 4.

[0009] Optionally, the cross-sectional area of ​​the intake air passage 5 is uniformly reduced along the direction of the intake airflow.

[0010] Optionally, the lip surface 3 is an annular surface around the intake duct inlet 1, with the surfaces connected by tangent continuity or curvature continuity, and the lip radius is 20mm~30mm.

[0011] Optionally, the length of the lower segment 7 is less than the preset length.

[0012] A second aspect of the present invention provides a design method for a flip-open helicopter air intake, comprising: Step 1: Determine the outline and location of the intake duct outlet; Determine the outline of the intake duct outlet based on the size and shape of the engine intake port. The outline must be physically aligned with the engine intake port, and the center point must be aligned with the center of the engine intake port to ensure the quality of the intake airflow field. Based on the engine intake pressure distortion and pressure loss control requirements, the air in the flow channel must always be in the acceleration process. The intake duct outlet is designed to be the smallest area in the entire intake airflow channel cross-section. Step 2: Determine the inlet profile and location of the air intake; obtain the flow field distribution of the helicopter fuselage and the dynamic characteristics of the rotor flow field corresponding to the helicopter's takeoff weight through numerical simulation, and identify the low-pressure region of the fuselage fairing behind the main gearbox; select the inlet location of the air intake within the identified low-pressure region based on the physical location of the engine and the main gearbox; calculate the inlet area based on the engine's intake flow requirements, air compression characteristics, and the helicopter's mission profile; design the inlet profile based on the outlet shape determined in Step 1, ensuring a smooth and abrupt airflow channel between the inlet and outlet; the design of the inlet profile and location is an iterative optimization process that relies on multiple simulation calculations to ensure that the engine has sufficient air supply under different mission profiles and meets the design requirements given in the engine manual; Step 3: Determine the airflow channel; using the inlet and outlet contours determined in Steps 1 and 2 as the two ends of the airflow channel, four spatial three-dimensional spline curves are introduced. One end of each spline curve is connected to the inlet contour, and the other end is connected to the outlet contour. Using the inlet and outlet contours as control sections and the four spatial three-dimensional spline curves as guide lines, the airflow channel surface is drawn using the multi-section surface method. Numerical simulation is used to evaluate the pressure loss and pressure distortion at the inlet outlet. If the requirements of the engine manual are not met, the curvature of the four contours is adjusted to reduce the vortices caused by unnecessary flow separation. If the requirements are still not met by adjusting the curvature of the four contours, additional contours are added to achieve more precise local control of the airflow channel surface inside the inlet. Step 4: Determine the inlet lip of the air intake: Use a rounded corner method to process the transition area between the curved surface of the air intake channel and the curved surface of the fuselage fairing to form the lip shape surface; control the pressure change, flow velocity distribution and possible flow field separation that occur when the air passes through the lip by controlling the lip radius; calculate and analyze the air intake field by numerical simulation method, and form a design scheme based on the calculation results and weight limit requirements.

[0013] This invention provides a foldable and retractable helicopter air intake and its design method. Numerical simulation and helicopter flight tests both show that this invention can significantly reduce engine air intake pressure loss and pressure distortion, reducing engine installation losses by 3% to 5%. The air intake adopts a two-section foldable and retractable structure, which greatly shortens the daily maintenance and cleaning time of the engine, improves work efficiency by 60%, and has been highly praised by ground maintenance personnel, further reflecting the human-centered innovative concept in engineering design. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the air intake in the working state of the present invention; Figure 2 This is a schematic diagram of the air intake in the flip-open / closed state of the present invention; Explanation of reference numerals in the attached figures: 1-Intake duct inlet, 2-Lip radius, 3-Lip, 4-Intake duct outlet, 5-Airflow passage, 6-Upper section of intake duct, 7-Lower section of intake duct. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0019] like Figure 1 and 2 As shown, this invention, through the design of the intake duct curved surface configuration, combined with intake fluid simulation and dynamic analysis, enables the total pressure loss and pressure distortion to meet the intake requirements of the engine; through the segmented and flip-open structure design, it solves the daily maintenance needs of the engine.

[0020] This invention addresses situations where the engine placement is unfavorable due to limitations in the overall aerodynamic layout design, the airflow field is opposite to the helicopter's flight direction, and the helicopter suffers from high levels of aerodynamic interference. It uses numerical simulation techniques to analyze the correspondence between the airflow field and the air intake duct design parameters, guiding the design of air intake aerodynamic schemes, increasing engine output power, and improving the overall performance of the helicopter.

[0021] The invention is L-shaped overall, consisting of two curved surfaces: an upper section 6 and a lower section 7. One end of the upper section 6 is in direct contact with the air and includes the air intake inlet 1, while the other end is fitted with a compressible rubber ring. One end of the lower section 7 is connected to the end of the upper section 6 with the compressible rubber ring via two telescopic hydraulic struts, while the other end is connected to the engine air intake.

[0022] In operation, the two hydraulic struts are in a retracted state, with one strut positioned before and after the air intake along the opening and closing axis. The lower end of each strut connects to the helicopter, and the upper end connects to the fairing of the upper section 6. The rubber ring between the two curved surfaces of the air intake is compressed, allowing air to flow inside the intake. The total pressure loss of the intake airflow is controlled to within 2%, and the pressure distortion is controlled to within -0.3. During routine maintenance, the hydraulic struts are in an extended state, with the upper section 6 curved surface flipped towards the fuselage (it's understood that when the upper section 6 is flipped, it should avoid facing the rotor or other external fuselage structures). The lower section 7 curved surface and the engine intake turbine blades are exposed to ground crew visibility, enhancing maintenance convenience.

[0023] The key points of this invention mainly consist of the following: a) Shape and area of ​​intake manifold outlet 4: To ensure successful assembly with the engine, the shape and area of ​​intake manifold outlet 4 shall be consistent with the engine's pre-reserved installation interface within the allowable tolerance range.

[0024] b) Shape and area of ​​intake duct inlet 1: The intake duct inlet 1 is rectangular in shape, with the four sharp corners rounded off to a radius of 75mm-100mm. Its area is 4-5 times that of the intake duct outlet. c) Shape and radius 2 of the lip 3 of the air intake duct inlet 1: The curved surface of the lip 3 is a ring-shaped curved surface around the air intake duct inlet, with the fairing and the air intake duct curved surface connected at both ends respectively. The connection of the curved surfaces is guaranteed to be tangential and continuous or curvature continuous. The radius 2 of the lip is 20mm~30mm. d) Intake duct 5: Intake duct 5 connects intake duct inlet 1 and intake duct outlet 4. It is L-shaped when viewed from the side. The cross-sectional area of ​​intake duct 5 is uniformly contracted along the direction of intake airflow. The maximum cross-sectional area is equal to the area of ​​intake duct inlet 1, and the minimum cross-sectional area is equal to the area of ​​intake duct inlet 4. e) Flip-opening position: The intake duct surface is divided into two parts, upper section 6 and lower section 7. The flip-opening position is between upper section 6 and lower section 7. The length of lower section 7 is less than the average arm length of ground maintenance personnel obtained through statistics, and ensures that there is no blind spot in the field of vision of lower section 7 along the direction of air inlet after flipping.

[0025] This invention provides a method for designing a flip-open helicopter air intake, the method comprising the following steps: Step 1: Determining the Intake Duct Outlet Profile and Location: First, thoroughly study the interface reserved for the intake duct by the engine, typically including the geometry, dimensions, and location of the interface. Clarify the specific requirements of the intake duct design, including flow rate requirements, pressure loss limits, and whether additional functions such as de-icing or protective devices are needed. Based on this information, use CATIA's 2D sketching function to draw the intake duct outlet profile using appropriate curves and angles. Consider the smoothness of the curves, edge treatment, and joint design to ensure structural integrity and manufacturing feasibility. Check the matching degree between the designed outlet profile and the engine interface. Ensure seamless connection in terms of dimensions and tolerances to avoid assembly problems. Simultaneously, consider the impact of thermal expansion on the connection interface, reserving necessary space to absorb thermal deformation. Finally, form the intake duct outlet profile that matches the engine's reserved interface for the intake duct, thus determining the intake duct outlet shape and location, laying the foundation for subsequent airflow channel design.

[0026] Step 2: Determining the Inlet Profile and Location: Clarify the engine's relative position within the overall aerodynamic layout, as well as the aerodynamic shape of the fuselage fairing. Numerical simulation is used to obtain the flow field distribution at the fuselage fairing and the dynamic characteristics of the rotor flow field corresponding to the helicopter's takeoff weight. Based on the flow field distribution at the fuselage fairing, identify low-pressure areas. Based on the dynamic characteristics of the rotor flow field, obtain the distribution range of the downwash airflow in the rotor flow field. Compare the low-pressure areas at the fuselage fairing and the downwash areas of the rotor flow field to determine their intersection. This intersection area is preferentially selected as the location of the air intake, as it maximizes the smoothness and stability of airflow under various flight conditions. After selecting the air intake location, the air intake area is determined based on the engine's maximum intake flow rate, air compression characteristics, and the helicopter's mission profile. This stage of calculation requires a precise combination of intake volume requirements and flight mission requirements to ensure sufficient air supply to the engine under different loads and environmental conditions. Based on the determined outlet shape, the inlet profile of the air intake is designed to ensure a smooth and abrupt airflow path between the inlet and outlet. Inlet profile design is an iterative optimization process that relies on multiple computational simulations and requires consideration of various factors, including air acceleration within the channel, the likelihood of vortex generation, and the feasibility of structural fabrication.

[0027] Step 3: Airflow Channel Design: Ensuring the aerodynamic performance of the internal flow channels of the intake is crucial during the intake channel design process. Therefore, the cross-sectional shape is first determined based on the intake inlet and outlet profiles from steps S1 and S2. These two key profiles not only determine the geometry of the intake channel but also directly affect the efficiency and stability of airflow. To achieve smooth airflow between the inlet and outlet, four profiles are introduced in the design. These profiles are designed to maintain a side-view projection shape perpendicular to the airflow direction, ensuring they are generally consistent and thus forming a uniform transition.

[0028] All four contour lines are in the form of three-dimensional spline curves. One end connects to the inlet contour line, and the other end connects to the outlet contour line to ensure overall continuity and smoothness. Using a multi-section surface drawing method, the inlet and outlet of the air intake are used as sections, and these four contour lines are used as guide lines to initially construct the airflow channel surface scheme inside the air intake. This design method not only improves the selectivity of airflow paths but also provides a flexible basis for subsequent adjustments and optimizations.

[0029] Numerical simulation technology is used to accurately calculate and analyze the flow field of the airflow channel surface inside the air intake. Particular attention is paid to the pressure loss and pressure distortion data at the air intake outlet. These two parameters are key indicators for judging the quality of the air intake design and directly affect the subsequent engine performance.

[0030] The simulation results are then compared and analyzed with the engine's design requirements. If the pressure loss or pressure distortion data at the engine's intake outlet does not meet the design standards, optimization measures will be taken. Firstly, the airflow speed and direction can be improved by adjusting the curvature of the four contour lines, thereby reducing the size and influence range of the separation zone. This adjustment allows for smoother airflow, avoiding pressure loss caused by unnecessary eddies and flow separation.

[0031] If simple curvature adjustment is insufficient, additional contour lines can be added to provide more precise local control over the airflow path within the intake duct. This method, by adding control points and guide lines, allows for fine-tuning of airflow within the design space, thereby ensuring that the pressure loss and pressure distortion at the outlet meet engine design requirements.

[0032] During the optimization process, iterative adjustments are made continuously until numerical simulation results show that the pressure loss and pressure distortion at the intake outlet are within reasonable ranges and meet the predetermined engine design standards. At this point, the final aerodynamic shape of the airflow channel surface inside the intake can be determined, providing a basis for subsequent engineering implementation. If the preliminary simulation results meet the requirements, the current design is directly determined as the final solution, avoiding redundant modifications and waste.

[0033] Step 4: Inlet Lip Design: The transition between the inlet airflow channel surface and the fuselage fairing surface is addressed using a rounded corner method, forming the lip's shape. Parametric design of the lip shape is fundamental to the entire design process. The lip shape is typically controlled by the rounded corner radius to ensure a smooth airflow transition. Therefore, the primary task in lip design is determining the rounded corner radius. A smaller radius allows for a more compact shape and reduced weight, but may increase the risk of flow separation. A larger radius provides a smoother airflow path, but may affect fuselage space configuration and increase weight. Numerical simulation is used to calculate and analyze the inlet airflow field. In the simulation, different rounded corner radii are adjusted to observe pressure changes, flow velocity distribution, and potential vortices as the gas flows through the lip. Under different flow conditions (such as high-speed cruise and low-speed hovering), the influence of the rounded corner radius on aerodynamic performance is analyzed, and the lip design scheme is determined based on the inlet performance parameters. Ensure a smooth connection between the lip, fuselage fairing, and inlet airflow channel using either a tangential or curvature-continuous approach. The tangential continuity of the curved surface ensures that airflow does not cause flow disturbance when passing through the lip. Curvature continuity reduces pressure fluctuations at the surface junctions and prevents vortex generation. A wind tunnel test model is designed to simulate the intake airflow field under different flight conditions, obtaining performance data under real airflow environments. Based on the test results, the lip design can be fine-tuned, such as adjusting the transition curvature of the rounded corners or improving the surface treatment process, to achieve optimal performance and ultimately form the final intake design scheme.

[0034] Step 5: Flip-opening position design: Although the design scheme formed in steps 1-4 has been carefully optimized in terms of aerodynamic performance and can effectively guide airflow to the front end of the engine intake turbine to achieve efficient power transmission, the problem of maintenance difficulties is often overlooked in actual operation. This design ignores the limitations of line of sight and space, making it very inconvenient for personnel to inspect blade damage and perform routine cleaning, dust removal and other maintenance work.

[0035] Conventional air intake structures are typically one-piece molded, with a flow path shape suitable for smooth airflow. However, this presents an obstacle during inspection and maintenance. Specially configured air intakes are often longer than the reach of a human arm, and their complex internal curved surfaces obstruct vision, making it impossible to directly observe the turbine blades. Ground inspectors, during routine engine maintenance, need to visually inspect the engine blades, a crucial step in early detection of potential problems such as blade cracks and corrosion. Furthermore, long, one-piece air intakes easily accumulate dust and grime, increasing the difficulty of cleaning, and the limited operating distance makes the cleaning process incomplete and inefficient.

[0036] To improve the maintainability of this system, a novel segmented air intake design was proposed. Specifically, the curved surface of the air intake is broken into upper and lower sections. This structural adjustment not only preserves superior aerodynamic performance but also significantly enhances the system's maintainability. The upper section connects to the fuselage fairing, ensuring a streamlined appearance; while the lower section connects to the engine, guaranteeing the integrity of power transmission. A retractable hydraulic strut connects these two sections. This design allows for easy opening of the air intake during engine maintenance, dividing it into an upper (moving) and lower (fixed) section. This enables ground maintenance personnel to easily access the air intake for engine maintenance and better clean dust and dirt, greatly improving maintenance efficiency.

[0037] Of particular note is the inclusion of a compressible sealing rubber ring at the upper connection point. This design primarily addresses the compatibility issue between power and sealing performance. The rubber ring provides sufficient elastic deformation space when the hydraulic strut pulls the upper and lower sections apart, preventing damage to the sealing components in the open state. Simultaneously, it ensures the seal between the upper and lower sections remains intact when in place, maintaining both aerodynamic efficiency and safety in aviation operations.

[0038] This innovative segmented design demonstrates significant advantages in terms of maintenance costs, efficiency, and safety. By reducing the length of each segment to less than the maximum operating range of maintenance personnel (generally no longer than the length of a human arm), each operator can easily perform tasks ranging from simple inspections to complex repairs without the need for special tools to extend the operating area. The shorter segment design reduces the surface complexity of each segment, eliminating visual obstacles caused by the original large curvature areas, enabling visual inspection to achieve blind-spot-free coverage.

[0039] This segmented intake design not only retains the advantages of the traditional one-piece design, but also saves maintenance time, improves work efficiency, and reduces potential risks and damage caused by difficult-to-access equipment through its flexible and user-friendly design. By combining all these advantages, the reliability and operability of the entire intake system are enhanced.

[0040] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A reversible opening and closing intake for a helicopter, characterized in that, Comprise: Upper section (6), lower section (7) and hydraulic support rod; The upper end of the upper section (6) is in contact with air, serving as the air inlet (1), and the lower end is provided with a rubber ring; The upper end of the lower section (7) is used to contact with the rubber ring, and the lower end serves as the air outlet (4) and communicates with the engine air inlet; The fixed end of the hydraulic support rod is arranged on the engine body in the engine compartment, and the movable end is connected with the upper section (6); during maintenance, the movable end of the hydraulic support rod drives the upper section (6) to rotate, exposing the upper end of the lower section (7); during non-maintenance, the movable end of the hydraulic support rod drives the rubber ring of the upper section (6) to extrude on the upper end of the lower section (7), forming an L-shaped air flow channel (5).

2. The reversible opening and closing helicopter inlet according to claim 1, characterized in that, The air inlet (1) of the upper end of the upper section (6) is provided with a lip (3); The lip (3) is connected with the fuselage skin; During maintenance, the movable end of the hydraulic support rod drives the upper section (6) and part of the skin at the lip (3) to rotate together.

3. The reversible opening and closing helicopter inlet according to claim 1, characterized in that, The shape of the air inlet (1) is overall rectangular, and the four sharp corners of the rectangle are rounded, with a rounding radius of 75mm-100mm.

4. The reversible opening and closing helicopter inlet according to claim 3, characterized in that, The area of the air inlet (1) is 4-5 times the area of the air outlet (4).

5. The reversible opening and closing helicopter inlet according to claim 4, characterized in that, The cross-sectional area of the air flow channel (5) uniformly shrinks along the flow direction of the air flow field.

6. The reversible opening and closing helicopter inlet of claim 2, wherein, The curved surface of the lip (3) is a ring-shaped curved surface along the periphery of the air inlet (1), and the connection of the curved surface is tangent continuous or curvature continuous, and the radius of the lip is 20mm-30mm.

7. The reversible opening and closing helicopter inlet of claim 2, wherein, The length of the lower section (7) is less than the preset length.

8. A method of designing a reversible opening and closing intake for a helicopter, characterized in that, Comprise: Step 1, determine the air inlet outlet contour line and position; determine the air inlet outlet contour line according to the size and shape of the engine air inlet, and the contour line is completely physically coincident with the engine air inlet, and the center point needs to be coincident with the center of the engine air inlet to ensure the quality of the air flow field, according to the engine air pressure distortion and pressure loss control requirements, the air in the flow channel is always in the acceleration process, the air inlet outlet is designed as the smallest area in the whole air flow channel space section; Step 2, determine the air inlet contour line and position; obtain the flow field distribution law of the helicopter fuselage and the dynamic characteristics of the rotor flow field corresponding to the helicopter take-off weight by numerical simulation method, identify the low pressure area of the fairing cover behind the main reducer; according to the physical position of the engine and the main reducer, select the air inlet position in the identified low pressure area; according to the engine air flow demand, air compression characteristics and helicopter mission profile, calculate the air inlet area size; According to the outlet shape determined in step 1, the air flow channel curved surface between the air inlet and the outlet is smooth and has no abrupt change as the principle, the air inlet contour line is designed; the inlet contour line and position design is a repeated optimization process, which depends on multiple simulation calculations to ensure that the engine has enough air supply under different mission profiles and meets the design requirements given in the engine manual; Step 3, determining the air flow channel; taking the inlet and outlet profile lines determined in steps 1 and 2 as two ends of the air flow channel, four three-dimensional spline curves are introduced, one end of the spline curve is connected with the inlet profile line, and the other end is connected with the outlet profile line; taking the inlet and outlet profile lines as control sections and the four three-dimensional spline curves as guide lines, the air flow channel surface is drawn by the multi-section surface method; the pressure loss and pressure distortion at the inlet of the air inlet are evaluated by the numerical simulation method, if it does not meet the requirements of the engine manual, the curvature of the four profile lines is adjusted to weaken the vortex caused by unnecessary flow separation, if it still cannot meet the requirements after adjusting the curvature of the four profile lines, additional profile lines are added to more accurately control the air flow channel surface inside the air inlet; Step 4, determining the inlet lip: the transition area between the air flow channel surface and the fairing surface of the fuselage is treated by the round corner method to form the lip shape surface; the pressure change, flow velocity distribution and possible flow field separation occurring when flowing through the lip are controlled by the lip radius; the air inlet flow field is calculated and analyzed by the numerical simulation method, and the design scheme is formed according to the calculation results and the weight limit requirements.

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