Reflectivity-variable electromagnetic shielding air-inlet grille and control method thereof

Abstract

The invention discloses an electromagnetic shielding air-inlet grille with variable reflectivity and a control method thereof. The electromagnetic shielding air-inlet grille comprises a double-layer grille body, the double-layer grille is arranged at an air inlet of an engine air inlet channel, the double-layer grille comprises a fixed grille body and a rotating grille body, the overall appearance of the fixed grille body and the overall appearance of the rotating grille body are circular, the fixed grille body is composed of an outer fixed ring and an inner fixed grille body, parallel grille bodies are arranged in the inner fixed grille body, and an annular rotating groove is formed in the outer fixed ring in the circumferential direction; parallel grilles are arranged in the rotating grilles, and the rotating grilles are embedded and mounted in the annular rotating groove of the outer fixing ring through the annular rotating groove of the outer fixing ring; and the grating included angle between the rotating grating and the fixed grating is changed through the circumferential rotation of the rotating grating along the annular rotating groove, so that the air inlet area of the air inlet and the radar wave reflectivity are changed. According to the technical scheme, the problem that radar wave reflectivity and engine air inlet efficiency are difficult to consider in addition of the air inlet grille due to the fact that a stealth mode that the grille net is additionally arranged at the air inlet is adopted in the stealth design of the helicopter air inlet channel is solved.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the technical field of helicopter structural design and radar stealth design, and in particular to an electromagnetic shielding air intake grille with variable reflectivity and a control method thereof. Background Art

[0002] Since the radar wave will form a mirror reflection when it hits the engine blade, causing the radar wave to return along the original path of the incident direction and be received by the radar, the air inlet is the scattering source with the widest impact and the strongest scattering in the forward area of ​​the aircraft. The RCS (radar cross section) of an aircraft is one of the most important indicators for evaluating the radar stealth performance of an aircraft. A large amount of data shows that the engine air inlet of a general single-engine aircraft can account for about 40% of the RCS of the entire aircraft in the forward area, while the proportion of the air inlet of a twin-engine aircraft can reach 60% or even higher. Therefore, whether the radar scattering characteristics of the air inlet can be effectively controlled is directly related to the RCS level of the entire aircraft in the forward area. Due to the complexity of the air inlet radar scattering and its relationship with the safety and performance of the aircraft, it is very difficult to control the RCS of the air inlet.

[0003] Existing stealth aircraft use various methods to control the RCS of the air inlet. For example, an S-shaped air inlet is used to shield the air inlet using the shape of the fuselage; another example is a backpack air inlet so that the radar waves emitted by ground radar cannot reach the air inlet; another example is a grille design to prevent the entry of radar waves. For helicopters, the air inlet can be shielded by adding a grille at the air inlet; however, adding a grille at the air inlet will bring an unavoidable disadvantage. Since the grille will reduce the air intake area, it is difficult to take into account the radar wave reflectivity and engine intake efficiency when adding an air intake grille. Summary of the invention

[0004] The purpose of the present invention is: in order to solve the above-mentioned problem, the embodiment of the present invention provides an electromagnetic shielding air intake grille with variable reflectivity and a control method thereof, so as to solve the stealth design of the helicopter air intake duct. Due to the stealth form of adding a grille net at the air inlet, the installation of the air intake grille makes it difficult to take into account both the radar wave reflectivity and the engine air intake efficiency.

[0005] The technical solution of the present invention is as follows: In a first aspect, an embodiment of the present invention provides an electromagnetic shielding air intake grille with variable reflectivity, comprising: a double-layer grille;

[0006] The double-layer grille is arranged at the air inlet of the engine air inlet duct, and the double-layer grille comprises: a fixed grille 1 and a rotating grille 2 whose overall shape is set to be circular, wherein the fixed grille 1 is composed of an outer fixed ring 1a and an inner fixed grille 1b, wherein parallel grilles are arranged in the inner fixed grille 1b, and the outer fixed ring 1a is provided with an annular rotating groove 1c along the circumferential direction;

[0007] Parallel grilles are arranged inside the rotating grille 2, and the rotating grille 2 is embedded and installed in the annular rotating groove 1c of the outer fixed ring 1a through the annular rotating groove 1c of the outer fixed ring 1a; and the grille angle between the rotating grille 2 and the fixed grille 1 is changed by rotating the rotating grille 2 along the annular rotating groove 1c, thereby changing the air intake area and radar wave reflectivity of the air inlet.

[0008] Optionally, the electromagnetic shielding air intake grille with variable reflectivity as described above further includes: a transmission gear 3;

[0009] A gear structure 2a is circumferentially arranged on the outer periphery of the rotating grille 2, and a radial opening 1d is opened on the outer fixed ring 1a of the fixed grille 1. Part of the gears of the transmission gear 3 are embedded in the annular rotating groove 1c of the outer fixed ring 1a through the radial opening 1d, and mesh with the gear structure 2a of the rotating grille 2 installed in the annular rotating groove 1c, so that the rotating grille 2 is rotated in the annular rotating groove 1c of the fixed grille 1 through the rotation of the transmission gear 3.

[0010] Optionally, the electromagnetic shielding air intake grille with variable reflectivity as described above further includes: a control motor 4 connected to the transmission gear 3;

[0011] The control motor 4 is used to control the rotation direction and number of rotations of the transmission gear 3 through the control of the host computer, so as to control the rotation direction and rotation angle of the rotating grille 2.

[0012] Optionally, in the electromagnetic shielding air intake grille with variable reflectivity as described above,

[0013] The outer periphery of the rotating grille 2 is specifically provided with a 1 / 4 circle gear structure 2a along the circumferential direction, which is used to form a relative rotation with the fixed grille 1 within the range of 0-90 degrees.

[0014] Optionally, in the electromagnetic shielding air intake grille with variable reflectivity as described above,

[0015] A limiting pin 2b is provided on one end face of the rotating grille 2, and a limiting groove 1e with a 1 / 4 circle is provided on the outer periphery of the inner fixed grille 1b along the circumferential direction. The limiting pin 2b of the rotating grille 2 is inserted into the limiting groove 1e and moves in the limiting groove 1e as the rotating grille 2 rotates, so as to limit the relative rotation of the rotating grille 2 and the fixed grille 1 within the range of 0-90° through the cooperation of the limiting groove 1e and the limiting pin 2b.

[0016] Optionally, in the electromagnetic shielding air intake grille with variable reflectivity as described above,

[0017] The electromagnetic shielding air intake grille with variable reflectivity forms a high reflectivity state and a high air intake efficiency state under different grille angles between the rotating grille 2 and the fixed grille 1 by rotating the rotating grille 2 in the annular rotating groove 1c in the fixed grille 1.

[0018] Optionally, in the electromagnetic shielding air intake grille with variable reflectivity as described above,

[0019] The electromagnetic shielding air intake grille with variable reflectivity has a maximum air intake area and is in a high air intake efficiency state when the rotating grille 2 rotates to overlap the grille of the fixed grille 1.

[0020] Optionally, in the electromagnetic shielding air intake grille with variable reflectivity as described above,

[0021] The electromagnetic shielding air intake grille with variable reflectivity has a maximum reflectivity of radar waves and is in a high reflectivity state when the rotating grille 2 is rotated to a point where its grille is perpendicular to the grille of the fixed grille 1 .

[0022] In a second aspect, an embodiment of the present invention further provides a control method for an electromagnetic shielding air intake grille with variable reflectivity, and the control method is performed using the electromagnetic shielding air intake grille with variable reflectivity as described in any one of the above items, including:

[0023] Step 1, determining the state of the electromagnetic shielding air intake grille according to the mission requirements of the aircraft;

[0024] Step 2, when the aircraft is in high-speed flight or maneuvering flight, the rotating grille 2 is controlled to rotate until its grille overlaps with the fixed grille 1, with a maximum air intake area, and in a high air intake efficiency state;

[0025] Step 3, when the aircraft is in stealth flight, the rotating grid 2 is controlled to rotate until its grid is perpendicular to the grid of the fixed grid 1, has the maximum reflectivity of radar waves, and is in a high reflectivity state.

[0026] Optionally, the control method of the electromagnetic shielding air intake grille with variable reflectivity as described above further includes:

[0027] Step 4, when the aircraft needs to take into account both stealth flight and high-speed maneuvering flight, the rotating grille 2 is controlled to rotate until its grille and the grille of the fixed grille 1 form an arbitrary angle, taking into account the requirements of radar wave reflectivity and high air intake efficiency.

[0028] The beneficial effects of the present invention are as follows: the embodiment of the present invention provides an electromagnetic shielding air intake grille with variable reflectivity and a control method thereof. Based on the double-layer requirements of the helicopter air intake duct for radar wave reflectivity and engine air intake efficiency, a double-layer grille structure with adjustable radar wave reflectivity and engine air intake efficiency is designed, namely a fixed grille 1 and a rotating grille 2, wherein parallel grilles are arranged in the inner fixed grille 1b of the fixed grille 1, and an annular rotating groove 1c is arranged circumferentially in the outer fixed ring 1a, and parallel grilles are also arranged in the rotating grille 2. The rotating grille 2 is embedded and installed in the annular rotating groove 1c of the outer fixed ring 1a through the annular rotating groove 1c of the outer fixed ring 1a; and the grille angle between the rotating grille 2 and the fixed grille 1 is changed by rotating the rotating grille 2 along the annular rotating groove 1c circumferentially, thereby changing the air intake area and radar wave reflectivity of the air intake port, thereby realizing the switching between the two states of high reflectivity state (high stealth) and high air intake efficiency state (high air intake rate). The electromagnetic shielding air intake grille provided by the embodiment of the present invention has the following beneficial effects:

[0029] First, the radar reflectivity of the double-layer grille structure provided by the present invention can be adjusted. When the aircraft needs to fly at high speed or maneuver, the rotating grille 2 in the double-layer grille can be switched to a high air intake efficiency state to meet the high-power operation requirements of the engine and help the aircraft quickly escape from the danger zone; when the aircraft needs to fly stealthily, the rotating grille 2 in the double-layer grille can be switched to a high reflectivity state to reduce the aircraft RCS and reduce the risk of being captured by radar;

[0030] Second, through motor control and gear transmission, the double-layer grille structure provided by the present invention can be adjusted steplessly between the two states of high air intake efficiency and high reflectivity, so as to achieve a balance between radar reflectivity and air intake efficiency according to actual mission requirements; in addition, the state change of the double-layer grille can be controlled in the cockpit during flight without stopping the aircraft for operation or manual adjustment;

[0031] Third, a limit pin 2b is provided on the rotating grille 2 in the double-layer grille structure provided by the present invention, and a limit slot 1e is provided on the fixed grille 1. The limit pin 2b can only move in the limit slot 1e, thereby ensuring that the rotating grille 2 rotates between 0-90°, that is, ensuring that the grille angle between the rotating grille 2 and the fixed grille 1 for quality inspection varies between 0-90°. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0033] Figure 1 It is a schematic structural diagram of the electromagnetic shielding air intake grille with variable reflectivity of the present invention;

[0034] Figure 2 for Figure 1 An exploded schematic diagram of an electromagnetic shielding air intake grille with variable reflectivity provided by the illustrated embodiment;

[0035] Figure 3 for Figure 1 A schematic diagram of the electromagnetic shielding air intake grille with variable reflectivity provided by the illustrated embodiment in a high air intake efficiency state;

[0036] Figure 4 for Figure 1 A schematic diagram of the electromagnetic shielding air intake grille with variable reflectivity provided by the illustrated embodiment in a high reflectivity state;

[0037] Figure 5 for Figure 4 The illustrated embodiment provides an enlarged schematic diagram of the grille angle between the rotating grille and the fixed grille of the electromagnetic shielding air intake grille with variable reflectivity in a high reflectivity state. DETAILED DESCRIPTION

[0038] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0039] It has been explained in the above background technology that in the stealth design of the helicopter air inlet, in order to prevent radar waves from irradiating the engine blades to form mirror reflection, the air inlet is currently blocked by installing a grille at the air inlet. The principle of the grille shielding radar waves is: on the one hand, the radar waves will be scattered when irradiated on the grille, and most of the radar waves cannot enter the air inlet and are reflected in a direction that the radar cannot receive; on the other hand, the installation of the grille will form a cavity between the air inlet and the air inlet, and a small part of the radar waves entering the air inlet will be reflected multiple times in the cavity, and the radar wave energy will continue to decay, greatly reducing the echo intensity.

[0040] Installing a grille at the air inlet will bring an unavoidable disadvantage. Since the grille will reduce the air intake area, the total pressure recovery of the air intake duct will be reduced, and the available thrust of the aircraft will be reduced. Therefore, the design of the air intake grille needs to take into account both radar wave reflectivity and engine air intake efficiency. From the perspective of the aircraft's mission requirements, when the aircraft is flying at high speed or maneuvering, the air intake grille needs to first meet the high air intake efficiency requirements to ensure high-power operation of the engine; when the aircraft is flying in stealth, the air intake grille needs to first meet the high reflectivity requirements to reduce the aircraft's RCS so that it cannot be detected by radar.

[0041] In response to the compatibility requirements of the aircraft's stealth performance and the engine's air intake efficiency, an embodiment of the present invention provides an electromagnetic shielding air intake grille with variable reflectivity and a control method thereof. The radar reflectivity of the electromagnetic shielding air intake grille structure can be changed, thereby achieving switching between a high reflectivity state (high stealth) and a high air intake efficiency state (high air intake rate).

[0042] The present invention provides the following specific embodiments which can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments.

[0043] Figure 1 is a schematic structural diagram of the electromagnetic shielding air intake grille with variable reflectivity of the present invention, Figure 2 for Figure 1 The exploded schematic diagram of the electromagnetic shielding air intake grille with variable reflectivity provided by the embodiment shown. Figure 1 and Figure 2 As shown, the composition structure of the electromagnetic shielding air intake grille with variable reflectivity provided by the embodiment of the present invention includes: a double-layer grille.

[0044] like Figure 1 In the structure of the electromagnetic shielding air intake grille shown, the double-layer grille is arranged at the air inlet of the engine air intake duct, and the double-layer grille includes: a fixed grille 1 and a rotating grille 2 whose overall shape is set to be circular, and the fixed grille 1 is composed of an outer fixed ring 1a and an inner fixed grille 1b, parallel grilles are arranged in the inner fixed grille 1b, and the outer fixed ring 1a is provided with an annular rotating groove 1c along the circumferential direction.

[0045] The rotating grille 2 in the embodiment of the present invention is arranged with parallel grilles, and the rotating grille 2 is embedded and installed in the annular rotating groove 1c of the outer fixed ring 1a through the annular rotating groove 1c of the outer fixed ring 1a, and the grille angle between the rotating grille 2 and the fixed grille 1 is changed by the rotating grille 2 rotating circumferentially along the annular rotating groove 1c, thereby changing the air intake area and radar wave reflectivity of the air intake.

[0046] In an implementation of the embodiment of the present invention, a structure for rotating the grille 2 is provided. The electromagnetic shielding air intake grille in the implementation may further include: a transmission gear 3; Figure 2 shown.

[0047] In this implementation, a gear structure 2a is circumferentially arranged on the outer periphery of the rotating grille 2; correspondingly, a radial opening 1d is opened on the outer fixed ring 1a of the fixed grille 1, and some gears of the transmission gear 3 are embedded in the annular rotating groove 1c of the outer fixed ring 1a through the radial opening 1d, and mesh with the gear structure 2a of the rotating grille 2 installed in the annular rotating groove 1c, so that the rotating grille 2 rotates in the annular rotating groove 1c of the fixed grille 1 through the rotation of the transmission gear 3.

[0048] In this implementation, the electromagnetic shielding air intake grille with variable reflectivity may further include: a control motor 4 connected to the transmission gear 3 .

[0049] like Figure 2 As shown, the control motor 4 can control the rotation direction and number of rotations of the transmission gear 3 through the control of the host computer, so as to control the rotation direction and rotation angle of the rotating grille 2.

[0050] It should be noted that the gear structure 2a in the rotating grille 2 only needs to be arranged 1 / 4 of a circle along the circumferential direction, that is, the grille angle between the rotating grille 2 and the fixed grille 1 can be changed from 0° to 90°.

[0051] In the specific implementation of the embodiment of the present invention, a limit pin 2b is provided on one side end face of the rotating grille 2; correspondingly, a 1 / 4 circle limit groove 1e is provided on the outer periphery of the inner fixed grille 1b along the circumferential direction, and the limit pin 2b of the rotating grille 2 is inserted into the limit groove 1e and moves in the limit groove 1e as the rotating grille 2 rotates, so as to limit the relative rotation of the rotating grille 2 and the fixed grille 1 within the range of 0-90° through the cooperation of the limit groove 1e and the limit pin 2b.

[0052] Based on the structure of the above-mentioned electromagnetic shielding air intake grille with variable reflectivity provided in an embodiment of the present invention, by rotating the rotating grille 2 in the annular rotating groove 1c in the fixed grille 1, a high reflectivity state and a high air intake efficiency state are formed under different grille angles between the rotating grille 2 and the fixed grille 1.

[0053] Specifically, when the rotating grille 2 rotates to overlap with the fixed grille 1, that is, when the grille angle is 0°, the electromagnetic shielding air intake grille has the maximum air intake area and is in a high air intake efficiency state. Figure 3 As shown, Figure 1 The illustrated embodiment is a schematic diagram of an electromagnetic shielding air intake grille with variable reflectivity in a high air intake efficiency state.

[0054] When the rotating grille 2 rotates to a point where its grille is perpendicular to the fixed grille 1, that is, when the grille angle is 90°, the electromagnetic shielding air intake grille has the maximum reflectivity of radar waves and is in a high reflectivity state. Figure 4 As shown, Figure 1 The embodiment shown is a schematic diagram of an electromagnetic shielding air intake grille with variable reflectivity in a high reflectivity state. Figure 5 for Figure 4 The illustrated embodiment provides an enlarged schematic diagram of the grille angle between the rotating grille and the fixed grille of the electromagnetic shielding air intake grille with variable reflectivity in a high reflectivity state.

[0055] Based on the electromagnetic shielding air intake grille with variable reflectivity provided by the embodiment of the present invention, the embodiment of the present invention also provides a control method for the electromagnetic shielding air intake grille with variable reflectivity. Specifically, the electromagnetic shielding air intake grille with variable reflectivity provided by any of the above embodiments is used to perform the control method, including the following steps:

[0056] Step 1, determining the state of the electromagnetic shielding air intake grille according to the mission requirements of the aircraft;

[0057] Step 2, when the aircraft is in high-speed flight or maneuvering flight, the rotating grille 2 is controlled to rotate until its grille overlaps with the fixed grille 1, with a maximum air intake area, and in a high air intake efficiency state;

[0058] Step 3, when the aircraft is in stealth flight, the rotating grid 2 is controlled to rotate until its grid is perpendicular to the grid of the fixed grid 1, has the maximum reflectivity of radar waves, and is in a high reflectivity state.

[0059] Furthermore, the control method of the electromagnetic shielding air intake grille with variable reflectivity provided by the embodiment of the present invention may also include:

[0060] Step 4, when the aircraft needs to take into account both stealth flight and high-speed maneuvering flight, the rotating grille 2 is controlled to rotate until its grille and the grille of the fixed grille 1 form an arbitrary angle, taking into account the requirements of radar wave reflectivity and high air intake efficiency.

[0061] The electromagnetic shielding air intake grille with variable reflectivity and its control method provided by the embodiment of the present invention are designed based on the double-layer requirements of the helicopter air intake for radar wave reflectivity and engine air intake efficiency, and the double-layer grille structure with adjustable radar wave reflectivity and engine air intake efficiency is designed, namely, a fixed grille 1 and a rotating grille 2, wherein the inner fixed grille 1b of the fixed grille 1 is arranged with parallel grilles, the outer fixed ring 1a is provided with an annular rotating groove 1c along the circumference, and the rotating grille 2 is also arranged with parallel grilles, and the rotating grille 2 is embedded and installed in the annular rotating groove 1c of the outer fixed ring 1a through the annular rotating groove 1c of the outer fixed ring 1a; and the grille angle between the rotating grille 2 and the fixed grille 1 is changed by rotating the rotating grille 2 along the annular rotating groove 1c circumferentially, thereby changing the air intake area and radar wave reflectivity of the air intake port, so as to achieve switching between the two states of high reflectivity state (high stealth) and high air intake efficiency state (high air intake rate). The electromagnetic shielding air intake grille provided by the embodiment of the present invention has the following beneficial effects:

[0062] First, the radar reflectivity of the double-layer grille structure provided by the present invention can be adjusted. When the aircraft needs to fly at high speed or perform maneuvering flight, by rotating the rotating grille 2 in the double-layer grille, it can be switched to a high intake efficiency state to meet the high-power operation requirements of the engine and help the aircraft quickly escape from the dangerous area. When the aircraft needs to perform stealth flight, by rotating the rotating grille 2 in the double-layer grille, it can be switched to a high reflectivity state to reduce the RCS of the aircraft and lower the risk of being captured by radar.

[0063] Second, through motor control and gear transmission, the double-layer grille structure provided by the present invention can be steplessly adjusted between the two states of high intake efficiency and high reflectivity to achieve a balance between radar reflectivity and intake efficiency according to actual mission requirements. In addition, the state change of the double-layer grille can be controlled in the cockpit during flight without the need for shutdown operation or manual adjustment.

[0064] Third, a limit pin 2b is provided on the rotating grille 2 in the double-layer grille structure provided by the present invention, and a limit groove 1e is opened on the fixed grille 1. The limit pin 2b can only move in the limit groove 1e, ensuring that the rotating grille 2 rotates between 0 - 90°, that is, ensuring that the grille angle between the rotating grille 2 and the fixed grille 1 changes between 0 - 90°.

[0065] The implementation manner of the electromagnetic shielding intake grille with variable reflectivity and its control method provided by the embodiments of the present invention is schematically described below through a specific embodiment. Specific Embodiment

[0067] Reference Figures 1 to 5 The electromagnetic shielding intake grille with variable reflectivity shown has the following characteristics:

[0068] (1) The electromagnetic shielding intake grille provided in this embodiment includes: a fixed grille 1, a rotating grille 2, a transmission gear 3, and a control motor 4. Among them, the fixed grille 1 is fixed at the engine intake port of the aircraft at a certain angle to the course, and a rotating groove 1c is provided around its inner circumference. The rotating grille 2 is placed in the rotating groove 1c of the fixed grille, and the rotating groove 1c is coated with grease. The rotating grille 2 rotates in the rotating groove 1c to realize the switching between the "one"-shaped grille and the "well"-shaped grille states in the projection direction of the grille surface to meet different reflectivity and intake efficiency requirements.

[0069] (2) A gear structure 2a is arranged in the circumferential range of 0 - 90° of the rotating grille 2 and meshes with the transmission gear 3, and the transmission gear 3 drives the rotating grille 2 to rotate between 0 - 90°.

[0070] (3) The grille spacing on the fixed grille 1 and the rotating grille 2 is 5 mm, and the grille bar width is 2 mm. Under high air intake rate conditions, the angle between the fixed grille and the rotating grille is 0°. In this state, the effective air intake area accounts for 71%.

[0071] (4) In the high reflectivity state, the angle between the fixed grille 1 and the rotating grille 2 is 90°; projected along the incident direction of the radar wave, the fixed grille 1 and the rotating grille 2 together form a "well"-shaped grille, and the grille holes are square with a side length of 5mm. In this state, the grille structure has a reflectivity of more than 90% for radar waves with a wavelength greater than 30mm (frequency less than 10GHz), and the effective air intake area accounts for 51%.

[0072] (5) The rotating grille 2 is provided with a limit pin 2b, and the fixed grille is provided with a limit slot 1e. The limit pin 2b can only move in the limit slot 1e, thereby ensuring that the rotating grille 2 can rotate between 0-90 degrees.

[0073] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. An electromagnetic shielding air intake grille with variable reflectivity, characterized in that: include: Double grille; The double-layer grille is arranged at the air inlet of the engine air inlet duct, and comprises: a fixed grille (1) and a rotating grille (2) whose overall shape is set to be circular, wherein the fixed grille (1) is composed of an outer fixed ring (1a) and an inner fixed grille (1b), parallel grilles are arranged inside the inner fixed grille (1b), and the outer fixed ring (1a) is provided with an annular rotating groove (1c) along the circumferential direction; Parallel grilles are arranged inside the rotating grille (2), and the rotating grille (2) is embedded and installed in the annular rotating groove (1c) of the outer fixed ring (1a) through the annular rotating groove (1c) of the outer fixed ring (1a); and the grille angle between the rotating grille (2) and the fixed grille (1) is changed by the rotating grille (2) rotating circumferentially along the annular rotating groove (1c), thereby changing the air intake area and radar wave reflectivity of the air intake.

2. The electromagnetic shielding air intake grille with variable reflectivity according to claim 1, characterized in that: Also includes: Transmission gear (3); The outer periphery of the rotating grille (2) is provided with a gear structure (2a) along the circumferential direction, and the outer fixed ring (1a) of the fixed grille (1) is provided with a radial opening (1d). Part of the gears of the transmission gear (3) are embedded in the annular rotating groove (1c) of the outer fixed ring (1a) through the radial opening (1d) and mesh with the gear structure (2a) of the rotating grille (2) installed in the annular rotating groove (1c), so that the rotating grille (2) is rotated in the annular rotating groove (1c) of the fixed grille (1) through the rotation of the transmission gear (3).

3. The electromagnetic shielding air intake grille with variable reflectivity according to claim 2, characterized in that: Also includes: A control motor (4) connected to the transmission gear (3); The control motor (4) is used to control the rotation direction and number of rotations of the transmission gear (3) through the control of the host computer, so as to control the rotation direction and rotation angle of the rotating grille (2).

4. The electromagnetic shielding air intake grille with variable reflectivity according to claim 2, characterized in that: The outer periphery of the rotating grille (2) is specifically provided with a 1 / 4 circle gear structure (2a) along the circumferential direction, which is used to form a relative rotation with the fixed grille (1) within a range of 0-90 degrees.

5. The electromagnetic shielding air intake grille with variable reflectivity according to claim 4, characterized in that: A limiting pin (2b) is provided on one end face of the rotating grille (2); a limiting groove (1e) with a length of 1 / 4 of a circle is provided on the outer periphery of the inner fixed grille (1b) along the circumferential direction; the limiting pin (2b) of the rotating grille (2) is inserted into the limiting groove (1e) and moves in the limiting groove (1e) as the rotating grille (2) rotates, so that the relative rotation of the rotating grille (2) and the fixed grille (1) within the range of 0-90° is limited by the cooperation of the limiting groove (1e) and the limiting pin (2b).

6. The electromagnetic shielding air intake grille with variable reflectivity according to any one of claims 1 to 5, characterized in that: The electromagnetic shielding air intake grille with variable reflectivity forms a high reflectivity state and a high air intake efficiency state at different grille angles between the rotating grille (2) and the fixed grille (1) by rotating the rotating grille (2) in the annular rotating groove (1c) in the fixed grille (1).

7. The electromagnetic shielding air intake grille with variable reflectivity according to claim 6, characterized in that: The electromagnetic shielding air intake grille with variable reflectivity has a maximum air intake area and is in a high air intake efficiency state when the rotating grille (2) rotates until its grille overlaps with the fixed grille (1).

8. The electromagnetic shielding air intake grille with variable reflectivity according to claim 6, characterized in that: The electromagnetic shielding air intake grille with variable reflectivity has a maximum reflectivity of radar waves and is in a high reflectivity state when the rotating grille (2) is rotated to a point where its grille is perpendicular to the grille of the fixed grille (1).

9. A control method for an electromagnetic shielding air intake grille with variable reflectivity, characterized in that: A control method is performed using the electromagnetic shielding air intake grille with variable reflectivity according to any one of claims 1 to 8, comprising: Step 1, determining the state of the electromagnetic shielding air intake grille according to the mission requirements of the aircraft; Step 2, when the aircraft is in high-speed flight or maneuvering flight, the rotating grille (2) is controlled to rotate until its grille overlaps with the fixed grille (1), thereby having a maximum air intake area and being in a high air intake efficiency state; Step 3, when the aircraft is in stealth flight, the rotating grid (2) is controlled to rotate until its grid is perpendicular to the grid of the fixed grid (1), has the maximum reflectivity of radar waves, and is in a high reflectivity state.

10. The control method of the electromagnetic shielding air intake grille with variable reflectivity according to claim 9, characterized in that: Also includes: Step 4, when the aircraft needs to take into account both stealth flight and high-speed maneuvering flight, the rotating grille (2) is controlled to rotate until its grille and the fixed grille (1) form an arbitrary angle, taking into account the requirements of radar wave reflectivity and high air intake efficiency.

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