A grid structure, air intake system and aircraft

Abstract

The application discloses a grid structure, an air intake system and an aircraft. The grid structure is arranged in an air inlet channel. The grid structure comprises an annular outer frame which is sealingly connected to the air inlet channel. An inner ring of the annular outer frame is provided for air flow. An annular cavity is arranged in the annular outer frame. The annular cavity is divided into a first cavity and a second cavity by at least two partitions. An air inlet is arranged in the annular outer frame and is in communication with the first cavity. The air inlet is connected to a high-temperature and high-pressure air source of an engine. An air outlet is arranged in the annular outer frame and is in communication with the second cavity. An inner frame of the grid is arranged in the inner ring of the annular outer frame. The inner frame comprises interlaced horizontal rods and vertical rods. A horizontal channel is arranged in each horizontal rod. A vertical channel is arranged in each vertical rod. The horizontal channels and the vertical channels are independent of each other and are in communication with the first cavity and the second cavity at two ends. The application solves the problems of ice formation in the air inlet channel, engine blade damage caused by ice shape shedding, thrust reduction and flight safety influence.

Description

Technical Field

[0001] This application relates to the field of aircraft air intake technology, and in particular to a grille structure, air intake system and aircraft. Background Technology

[0002] With the rapid development of meteorological science and drone technology, drones are increasingly being used in weather modification. Drones, with their flexibility, autonomous flight, and multi-task collaboration capabilities, have become important tools for conducting cloud precipitation detection and precipitation control operations.

[0003] Under complex weather conditions, drones face serious safety risks when performing operations. When clouds contain a large number of supercooled water droplets with a temperature below 0°C, moisture is prone to condense and freeze on the windward surfaces of the drone (especially the air intake lip, wing surface, and sensor probes).

[0004] The engine provides power to the drone, and the air intake is the core aerodynamic component of the engine. Its design must ensure that the airflow enters the engine uniformly and stably. When the air intake lip freezes, the ice layer covers the lip surface, disrupts the airflow boundary layer, prematurely triggers airflow separation, forms vortices and turbulence, and increases compressor surface distortion. At the same time, the thickness of the ice layer reduces the inlet area, decreases the intake mass flow rate, and leads to a decrease in engine thrust. If the icing intensifies, the further reduction in intake airflow will cause compressor surge, resulting in severe structural vibration and pressure fluctuations, which may even cause the engine to shut down. After leaving the icy environment, the ice fragments on the lip will be sucked into the core engine components. The high-speed impact of the ice fragments can damage the engine blades, leading to aerodynamic performance degradation and even blade breakage, directly affecting the flight safety of the drone.

[0005] Existing anti-icing technologies for UAV air intakes focus on hot air anti-icing or electric heating anti-icing at the lip, without considering solutions for ice detachment entering the engine and damaging compressor blades. Therefore, it is urgent to solve the problems of air intake icing and ice detachment leading to engine blade damage, thrust reduction, and impact on flight safety. Summary of the Invention

[0006] The purpose of this application is to provide a grid structure, an air intake system, and an aircraft that solves the problems of easy icing in the air intake and damage to engine blades, reduced thrust, and impact on flight safety caused by ice shedding, thereby meeting the high safety requirements of the aircraft for performing tasks such as weather detection and emergency rescue under extreme weather conditions.

[0007] To achieve the above objectives, this application provides a grille structure disposed in the air intake, the grille structure comprising:

[0008] An annular outer frame is sealed to the air intake duct. The inner ring of the annular outer frame allows air to circulate. An annular cavity is provided inside the annular outer frame. The annular cavity is divided into a first cavity and a second cavity by at least two partitions.

[0009] An air inlet is located on the annular outer frame and communicates with the first cavity; the air inlet is externally connected to the high-temperature and high-pressure air source of the engine.

[0010] An air outlet is located on the annular outer frame and communicates with the second cavity;

[0011] The inner frame of the grille, located within the inner ring of the annular outer frame, includes intersecting horizontal and vertical bars. The horizontal bars have transverse channels, and the vertical bars have longitudinal channels. The transverse and longitudinal channels are independent of each other and their ends are respectively connected to the first cavity and the second cavity.

[0012] Optionally, the multiple horizontal bars are horizontally and equidistantly distributed, the multiple vertical bars are vertically and equidistantly distributed, the spacing between adjacent horizontal bars is equal to the spacing between adjacent vertical bars, and the grid holes formed by the inner frame of the grid are uniformly distributed in the cross-section.

[0013] Optionally, one of the crossbar and the longitudinal bar is a straight bar, and the other is a corrugated bar. The corrugated bar has protrusions that are in the same direction as and / or opposite to the airflow direction, and the straight bar is located in a recess formed on the back of the protrusions.

[0014] Optionally, the air inlet and the air outlet are inclined at 45° to the horizontal plane and symmetrically arranged, with the air inlet located at the midpoint of the first cavity and the air outlet located at the midpoint of the second cavity.

[0015] Optionally, the cross-sectional area of ​​the air inlet and the air outlet is greater than or equal to the sum of the cross-sectional areas of the horizontal bar and the vertical bar, and the cross-sectional area of ​​the air inlet is equal to the cross-sectional area of ​​the air outlet.

[0016] Optionally, it also includes a connecting flange located on the outer ring of the annular outer frame. The connecting flange is integrally formed with the annular outer frame. The two flange faces of the connecting flange are fixedly connected with a front clamp and a rear clamp, and a sealing ring is provided between the front clamp and the flange face and between the rear clamp and the flange face.

[0017] Optionally, the front clamp and the rear clamp include two semi-circular annular clamps, the ends of the two semi-circular annular clamps are engaged and fixed, the front clamp and the rear clamp cover the outer periphery of the air intake and are interference fit with the air intake.

[0018] Optionally, the porosity of the grid holes formed by the inner frame of the grid is 0.8~0.9, and the outer surface temperature of the inner frame of the grid is higher than 0°C.

[0019] An air intake system includes an air intake duct and a grille structure as described above. The length of the grille structure from the lip to the installation position along the centerline of the air intake duct accounts for 70% to 80% of the total length of the air intake duct. The angle between the windward surface of the grille structure and the tangent of the centerline of the air intake duct is 88° to 92°.

[0020] An aircraft comprising the aforementioned air intake system.

[0021] The beneficial effects of this application are as follows: by placing the grille structure on the intake duct, the high-temperature, high-pressure air source from the engine is introduced through the intake port, which can rapidly increase the temperature of the annular outer frame and the inner frame of the grille, thereby eliminating icing on the outer surface of the grille structure. Furthermore, the transverse and longitudinal channels are independent and unidirectional, ensuring that the high-temperature gas in the transverse and longitudinal channels does not affect each other. This results in higher heat exchange efficiency between the crossbars, longitudinal bars, and the high-temperature gas, making it easier to transfer heat to the outer surfaces of the crossbars and longitudinal bars. In addition, the inner frame of the grille forms multiple grille holes in the inner ring of the annular outer frame (i.e., the cross-section of the intake duct). Each grille hole has a hole wall with a certain temperature (the hole wall is a crossbar, longitudinal bar, or the annular outer frame), preventing supercooled water droplets from condensing at the grille holes and thus not affecting the intake mass flow rate. Even if icing occurs, the ice crystals will be blocked by the inner frame after detachment, preventing ice fragments from entering the engine, or causing large ice fragments to collide and break at the inner frame of the grille, thus avoiding large ice fragments affecting the engine and ensuring the engine's safety and reliability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the intake system structure provided in an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the grid structure installation provided in an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the grille structure provided in an embodiment of this application;

[0026] Figure 4 for Figure 3 Sectional view along line AA;

[0027] Figure 5This is a schematic diagram of the crossbar and longitudinal bar structure provided in the embodiments of this application;

[0028] Figure 6 This is an exploded view of the grid structure provided in the embodiments of this application;

[0029] Figure 7 This is a simulation diagram of the total pressure recovery coefficient of the AIP surface without a grid structure, provided in an embodiment of this application.

[0030] Figure 8 The simulation diagram shows the total pressure recovery coefficient of the AIP surface when the grid structure is provided in the embodiment of this application.

[0031] In the diagram: 1-Air intake; 2-Grill structure; 3-Front clamp; 4-Rear clamp; 5-Sealing ring;

[0032] 11-Lips and mouth;

[0033] 21-Annular outer frame; 22-Horizontal bar; 23-Vertical bar; 24-Divider; 25-Air inlet; 26-Air outlet; 211-First cavity; 212-Second cavity; 221-Transverse channel; 231-Vertical channel; 232-Protrusion; 233-Recess. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] It should be noted that in this embodiment, the orientation or positional relationship indicated by terms such as "upper," "lower," "front," and "rear" is based on the orientation or positional relationship shown in the accompanying drawings. It is used only for the convenience of describing this application and for simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 2 and Figure 3As shown, in this embodiment, a grille structure 2 is provided, which is installed on the air intake duct 1 and includes an annular outer frame 21, an inner grille frame, an air intake 25 and an air outlet 26. The annular outer frame 21 is sealed to the air intake duct 1, so that the air flowing through the air intake duct 1 must pass through the inner ring of the annular outer frame 21 before flowing to the engine. The annular outer frame 21 has an annular cavity inside, which is divided into a first cavity 211 and a second cavity 212 by at least two partitions 24, wherein the first cavity 211 and the second cavity 212 are semi-circular cavity structures.

[0038] An air inlet 25 is located on the annular outer frame 21 and communicates with the first cavity 211. The air inlet 25 is connected to a high-temperature and high-pressure air source of the engine. This high-temperature and high-pressure air source is the mixed gas discharged after combustion to generate thrust in the engine. An air outlet 26 is located on the annular outer frame 21 and communicates with the second cavity 212.

[0039] The inner frame of the grille is located within the inner ring of the annular outer frame 21. The inner frame includes intersecting horizontal bars 22 and vertical bars 23, with the horizontal bars 22 and vertical bars 23 perpendicular to each other. The horizontal bars 22 have transverse channels 221, and the vertical bars 23 have longitudinal channels 231. The transverse channels 221 and longitudinal channels 231 are independent of each other, with their two ends connected to the first cavity 211 and the second cavity 212, respectively. Specifically, one end of the transverse channel 221 can connect to the air inlet 25 through the first cavity 211, and the other end can connect to the air outlet 26 through the second cavity 212. This allows the high-temperature, high-pressure gas to exchange heat with the horizontal bars 22 within the transverse channel 221, thereby increasing the surface temperature of the horizontal bars 22. Similarly, the surface temperature of the vertical bars 23 can also be increased.

[0040] As can be seen, this application, by setting a heat medium flow channel inside the grille structure 2, heats the surface of the grille structure 2 through convection heat conduction, making its surface reach the condition that prevents supercooled water droplets (-10~0℃) from condensing on the surface of the grille structure 2. Furthermore, through the grille holes formed by the grille structure 2, ice chips cannot cross the grille structure 2, or only some small ice chips cross the grille structure 2, thereby ensuring that the engine is not affected by ice chips.

[0041] In summary, this application introduces a high-temperature, high-pressure air source from the engine through the air inlet 25, which can rapidly increase the temperature of the annular outer frame 21 and the inner frame of the grille, thereby eliminating the icing phenomenon on the outer surface of the grille structure 2. The transverse channel 221 and the longitudinal channel 231 are independent of each other and are both single-flow channels, so that the high-temperature gas in the transverse channel 221 and the longitudinal channel 231 does not affect each other. The heat exchange efficiency between the crossbar 22, the longitudinal bar 23 and the high-temperature gas is higher, and it is easier to transfer heat to the outer surface of the crossbar 22 and the longitudinal bar 23. Furthermore, the inner frame of the grille forms multiple grille holes in the inner ring of the annular outer frame 21 (i.e., the cross-section of the intake duct 1). Each grille hole has a hole wall with a certain temperature (the hole wall is a horizontal bar 22, a vertical bar 23, or the annular outer frame 21), preventing supercooled water droplets from condensing at the grille holes and thus not affecting the intake air mass flow rate. Even if icing occurs, the ice crystals will be blocked by the inner frame of the grille after they fall off, preventing ice chips from entering the engine, or causing large ice chips to collide and break at the inner frame of the grille, thus preventing large ice chips from affecting the engine and ensuring the engine's safety and reliability.

[0042] When the grille structure 2 is assembled with the air intake duct 1, the horizontal bar 22 and the vertical bar 23 can be inclined relative to the horizontal plane, or the horizontal bar 22 can be arranged horizontally and the vertical bar 23 can be arranged vertically; as per the attached instruction manual. Figure 4 Multiple horizontal bars 22 are distributed horizontally and equidistantly, and multiple vertical bars 23 are distributed vertically and equidistantly. The spacing between adjacent horizontal bars 22 is equal to the spacing between adjacent vertical bars 23, so that the grid holes formed by the inner frame of the grid are evenly distributed on its cross-section. The core function of the uniform arrangement of the grid structure 2 channels on the cross-section is to optimize the flow field distribution so that the impact probability of large ice particles remains basically consistent on the cross-section, thereby improving the anti-icing effect and safety.

[0043] It should be noted that the size of the grille holes needs to ensure that ice particles of typical diameter can be broken, while the design of the internal channel size of the grille frame needs to take into account the structural strength and the flow requirements of the heat medium. By taking the size of the grille holes and the size of the transverse channel 221 / vertical channel 231 as design variables, the configuration of the grille structure 2 can be determined after multiple rounds of iterative optimization.

[0044] In some embodiments, one of the crossbar 22 and the longitudinal bar 23 is a straight bar, and the other is a corrugated bar. Please refer to [reference needed]. Figure 5 Here, we will take the example of a straight bar 22 and a corrugated bar 23. With the horizontal bar 22 arranged horizontally and the vertical bar 23 arranged vertically, the high-temperature and high-pressure gas flows from left to right along the horizontal channel 221, which is a straight channel. The high-temperature and high-pressure gas flows from top to bottom along the vertical channel 231, which is a corrugated channel.

[0045] The longitudinal bar 23 has protrusions 232 that are in the same direction as and / or opposite to the airflow direction, please refer to Figure 5 The horizontal bar 22 is located in the recess 233 formed on the back of the protrusion 232. The arrangement of the horizontal bar 22 and the vertical bar 23 can effectively utilize the internal space of the annular outer frame 21, while ensuring that the grid structure 2 has a certain thickness, so that the structural strength of the ice particles impacting the inner frame of the grid meets the design requirements. The corrugated bar increases the heat exchange area between the heat medium and the inner frame of the grid, increases the turbulence intensity of the heat medium, and thus increases the heat exchange efficiency between the heat medium and the grid structure 2.

[0046] Furthermore, the air inlet 25 and the air outlet 26 are inclined at 45° to the horizontal plane and are symmetrically arranged. The air inlet 25 is located at the midpoint of the first cavity 211, and the air outlet 26 is located at the midpoint of the second cavity 212. This allows the heat medium to diffuse evenly to both sides of the first cavity 211 when it enters the first cavity 211 through the air inlet 25, thereby ensuring that the heat medium can enter each transverse channel 221 and longitudinal channel 231 evenly. After the heat medium flows through the transverse channel 221 and the longitudinal channel 231, it gathers in the second cavity 212 and is discharged from the air outlet 26.

[0047] The cross-sectional areas of the inlet 25 and outlet 26 are greater than or equal to the sum of the cross-sectional areas of the horizontal bar 22 and the vertical bar 23, thereby ensuring that each horizontal channel 221 and vertical channel 231 can be filled with heat medium, ensuring the heat exchange effect of the inner frame of the grille; furthermore, the cross-sectional areas of the horizontal channel 221 and the vertical channel 231 are much smaller than the cross-sectional area of ​​the inlet 25. By reducing the cross-sectional dimensions of the horizontal channel 221 and the vertical channel 231, the heat medium wetting area and heat exchange efficiency are increased. The cross-sectional area of ​​the inlet 25 is equal to the cross-sectional area of ​​the outlet 26, thereby ensuring that the intake efficiency and exhaust efficiency are matched.

[0048] In addition, the grille structure 2 needs to be able to be installed and removed from the air intake duct 1. Please refer to [the relevant documentation]. Figure 6 The grid structure 2 includes a connecting flange located on the outer ring of the annular outer frame 21. The connecting flange can be integrally formed with the annular outer frame 21. The two flange faces of the connecting flange are fixedly connected with a front clamp 3 and a rear clamp 4. A sealing ring 5 is provided between the front clamp 3 and the flange face and between the rear clamp 4 and the flange face. The connecting flange is fixedly connected to the sealing ring 5 and the clamp by bolts, thereby ensuring the structural stability and overall sealing of the grid structure 2.

[0049] Furthermore, the front clamp 3 and the rear clamp 4 include two semi-circular ring clamps, the ends of which are snapped together for quick replacement and maintenance. This allows them to adapt to flight missions under complex and conventional weather conditions, reducing maintenance costs. The front clamp 3 and the rear clamp 4 cover the outer periphery of the air intake 1 and are press-fitted with the air intake 1 to ensure the connection stability and airtightness between the grille structure 2 and the air intake 1.

[0050] The grille structure 2 must have a certain structural strength and can be made of TC4-ELI (titanium alloy). The grille structure 2 can withstand the impact of ice blocks with a speed of 100m / s and a diameter of 40mm. The airflow impact will break large ice particles into smaller particles, thus preventing ice particles from damaging the engine.

[0051] The grid structure 2 will generate a certain aerodynamic drag. If the grid hole spacing is too large, it will not be able to effectively block large ice chips. If the grid hole spacing is too small, it will increase the aerodynamic drag loss of the intake duct 1 and block the airflow. Through simulation and iterative calculation, the porosity of the grid holes formed by the inner frame of the grid in this embodiment is 0.8~0.9, which is used to optimize the airflow uniformity of the outlet section and reduce the risk of boundary layer separation.

[0052] The heat transfer medium is high-temperature and high-pressure hot gas, drawn from the engine. The gas source pressure is 0.2~0.3Mpa and the gas source temperature is 170~220℃, ensuring that the hot gas can pass through the interior of the grille structure 2. The surface of the grille structure 2 exchanges heat fully with the gas source, so that the outer surface temperature of the inner frame of the grille is higher than 0℃, preventing supercooled water droplets (-10~0℃) from condensing on the surface of the grille structure 2. If the local ice thickness increases significantly, the air intake flow of the grille structure 2 can be dynamically adjusted to increase the surface temperature of the grille structure 2 and accelerate the melting of the ice layer.

[0053] This application also provides an air intake system, which includes an air intake duct 1 and a grille structure 2 as described above. Please refer to... Figure 1 and Figure 2 Regarding the specific location of the grille structure 2, such as its installation at the lip 11 or at a certain position along the air intake 1, and the tilt angle of the grille structure 2, it is necessary to conduct a specific analysis based on the design state of the UAV and the velocity vector distribution within the air intake 1. By installing the grille structure 2 at different positions along the air intake 1 (from the lip 11 to the engine inlet) and implementing different tilt angles (0~10°), CFD simulation analysis is required to ensure that the total pressure recovery coefficient loss and circumferential total pressure distortion index at the AIP surface (the interface between the air intake 1 and the engine) caused by the grille structure 2 meet the engine performance requirements.

[0054] In this embodiment, the grille structure 2 is installed in the rear half of the air intake duct 1. Specifically, the length from the lip 11 to the installation position of the grille structure 2 along the centerline of the air intake duct 1 accounts for 70% to 80% of the total length of the air intake duct 1. The angle between the windward surface of the grille structure 2 and the tangent of the centerline of the air intake duct 1 is 88° to 92°. In this embodiment, the installation position of the grille structure 2 is selected at the 76% position, with a tangent angle of 89°. Figure 2 As shown, the position is chosen at the front of the engine to avoid premature installation of the grille structure 2, which would cause airflow disturbance. The 89° angle design makes the windward side of the grille structure 2 perpendicular to the airflow direction of the intake duct 1, reducing direct impact loss, while using aerodynamics to assist in anti-icing.

[0055] By adding grille structure 2 to intake duct 1 and dividing it into an unstructured mesh, the aerodynamic parameters of the AIP surface (the interface between intake duct 1 and the engine) can be obtained through CFD simulation. The total pressure recovery coefficient of the AIP surface without grille structure 2 is as follows: Figure 7 As shown, the total pressure recovery coefficient of the AIP surface after adding grid structure 2 is as follows: Figure 8 As shown, the grille structure 2 straightens the airflow and suppresses the two small vortices on the left and right sides of the lower wall. After adding the grille structure 2, the total pressure recovery coefficient at the intake matching point is greater than 0.98 and the circumferential total pressure distortion index is less than 0.01, which can meet the design requirements of the intake duct 1 and the matching requirements of the engine.

[0056] This application also provides an aircraft, which may be a drone, but is not limited to a drone, and the aircraft includes the aforementioned air intake system.

[0057] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0058] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A grid structure, characterized in that, Located in the air intake (1), the grille structure (2) includes: An annular outer frame (21) is sealed to the air intake (1). The inner ring of the annular outer frame (21) is for air circulation. An annular cavity is provided inside the annular outer frame (21). The annular cavity is divided into a first cavity (211) and a second cavity (212) by at least two partitions (24). An air inlet (25) is provided on the annular outer frame (21) and communicates with the first cavity (211). The air inlet (25) is connected to the high temperature and high pressure air source of the engine. An air outlet (26) is provided on the annular outer frame (21) and communicates with the second cavity (212); The inner frame of the grille, located in the inner circle of the annular outer frame (21), includes intersecting horizontal bars (22) and vertical bars (23). The horizontal bars (22) have a transverse channel (221), and the vertical bars (23) have a longitudinal channel (231). The transverse channel (221) and the longitudinal channel (231) are independent of each other and their two ends are respectively connected to the first cavity (211) and the second cavity (212). Among them, the multiple horizontal bars (22) are horizontally and equidistantly distributed, the multiple vertical bars (23) are vertically and equidistantly distributed, the spacing between adjacent horizontal bars (22) is equal to the spacing between adjacent vertical bars (23), and the grid holes formed by the inner frame of the grid are evenly distributed in the cross section. The air inlet (25) and the air outlet (26) are inclined at 45° to the horizontal plane and are symmetrically arranged. The air inlet (25) is located at the midpoint of the first cavity (211), and the air outlet (26) is located at the midpoint of the second cavity (212).

2. The grid structure according to claim 1, characterized in that, One of the crossbar (22) and the longitudinal bar (23) is a straight bar, and the other is a corrugated bar. The corrugated bar has a protrusion (232) that is in the same direction as and / or opposite to the airflow direction. The straight bar is located in a recess (233) formed on the back of the protrusion (232).

3. The grid structure according to claim 1, characterized in that, The cross-sectional area of ​​the air inlet (25) and the air outlet (26) is greater than or equal to the sum of the cross-sectional areas of the cross bar (22) and the vertical bar (23), and the cross-sectional area of ​​the air inlet (25) is equal to the cross-sectional area of ​​the air outlet (26).

4. The grid structure according to claim 1, characterized in that, It also includes a connecting flange located on the outer ring of the annular outer frame (21), the connecting flange being integrally formed with the annular outer frame (21), the two flange faces of the connecting flange being fixedly connected with a front clamp (3) and a rear clamp (4), and a sealing ring (5) is provided between the front clamp (3) and the flange face and between the rear clamp (4) and the flange face.

5. The grid structure according to claim 4, characterized in that, The front clamp (3) and the rear clamp (4) include two semi-circular ring clamps, the ends of the two semi-circular ring clamps are snapped together and fixed, the front clamp (3) and the rear clamp (4) cover the outer periphery of the air intake (1) and are interference fit with the air intake (1).

6. The grid structure according to claim 1, characterized in that, The porosity of the grid holes formed by the inner frame of the grid is 0.8~0.9, and the outer surface temperature of the inner frame of the grid is higher than 0℃.

7. An intake system, characterized in that, Includes an air intake (1) and a grille structure (2) as described in any one of claims 1-6, wherein the length along the centerline of the air intake (1) from the lip (11) to the installation position of the grille structure (2) accounts for 70% to 80% of the total length of the air intake (1), and the angle between the windward surface of the grille structure (2) and the tangent of the centerline of the air intake (1) is 88° to 92°.

8. An aircraft, characterized in that, Includes the air intake system as described in claim 7.

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