A multi-mechanism composite scattering reduction method for special-shaped cavity structures

Abstract

The present invention relates to a multi - mechanism composite scattering reduction method for a special - shaped cavity structure, which comprises the following steps: S1: performing scattering diagnosis on the special - shaped cavity through a full - wave algorithm in the frequency domain to obtain the RCS level of the special - shaped cavity; S2: analyzing the electromagnetic wave scattering path in the special - shaped cavity to obtain the strong scattering region; S3: based on the identification of the strong scattering region, obtaining the incident angle of the electromagnetic wave irradiating the strong scattering region; S4: designing a deflection / absorbing composite metamaterial based on the incident angle of the electromagnetic wave in the strong scattering region to obtain the composite metamaterial; S5: arranging the composite metamaterial in the strong scattering region and arranging a traditional absorbing coating in other regions of the special - shaped cavity to obtain a new special - shaped cavity; S6: evaluating the scattering reduction effect of the new special - shaped cavity; The present invention has the characteristics of separating the geometric shape from the electromagnetic shape, and has the advantage of breaking through the technical bottleneck of the contradiction between aerodynamic performance and low - scattering performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic wave stealth technology, and particularly relates to a multi-mechanism composite scattering reduction method for an irregular cavity structure. Background Art

[0002] Scattering from an irregular cavity is one of the strongest scattering sources affecting the forward angular region of a combat aircraft. Controlling its scattering level has a decisive impact on the electromagnetic stealth performance of the aircraft. In the design process of the irregular cavity shape, both aerodynamic performance and stealth performance need to be considered comprehensively. Good stealth requires a large cavity bend, while considering aerodynamic performance, the cavity bend cannot be too large, and the two are often contradictory, further increasing the difficulty of the scattering reduction design for the irregular cavity.

[0003] Currently, the main scattering reduction scheme for an irregular cavity is to coat the inner wall with a magnetic absorbing coating, which has the following deficiencies:

[0004] (1) The absorption effect of traditional absorbing coatings deteriorates when irradiated by electromagnetic waves at large angles, and at the same time, the absorption bandwidth is narrow;

[0005] (2) Limited by the shape of the irregular cavity, the number of reflections of electromagnetic waves on the inner wall of the cavity is limited, and the loss by the absorbing material is limited, so the scattering reduction effect is not obvious.

[0006] Therefore, in view of the contradiction between stealth and aerodynamic design in the stealth design process of the air intake, forming a design method to separate electromagnetic and geometric shapes is an important means to reduce the cavity scattering. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a multi-mechanism composite scattering reduction method for an irregular cavity structure, which has the characteristics of separating geometric shape and electromagnetic shape and breaks through the technical bottleneck of the contradiction between aerodynamic performance and low scattering performance.

[0008] The technical solution of the present invention is as follows:

[0009] A multi-mechanism composite scattering reduction method for an irregular cavity structure includes the following steps:

[0010] S1: Conduct scattering diagnosis on the irregular cavity through the frequency-domain full-wave algorithm to obtain the RCS level of the irregular cavity;

[0011] S2: Analyze the electromagnetic wave scattering path in the irregular cavity to obtain the strong scattering region;

[0012] S3: Based on the identification of the strong scattering region, obtain the incident angle of the electromagnetic wave irradiating the strong scattering region;

[0013] S4: Design a deflection / absorption composite metamaterial based on the incident angle of the electromagnetic wave in the strong scattering region to obtain the composite metamaterial;

[0014] S5: Lay the composite metamaterial in the strong scattering region, and lay a traditional absorbing coating in other regions of the special-shaped cavity to obtain a new special-shaped cavity;

[0015] S6: Evaluate the scattering reduction effect of the new special-shaped cavity.

[0016] Furthermore, the full-wave frequency-domain algorithm used in step S1 includes the finite element method, the method of moments, the boundary element method, and the multi-level fast multipole method, which are used to simulate and calculate the RCS magnitude of the special-shaped cavity within the incident angle range of -30° to 30° of the special-shaped cavity.

[0017] Furthermore, the asymptotic algorithm used in step S2 includes the physical optics method and the shooting and bouncing ray method to analyze the scattering paths and concentrated regions of electromagnetic waves within the incident angle ranges of ±15° and ±(15° to 30°) in the special-shaped cavity, so as to obtain the strong scattering region.

[0018] Furthermore, for the identification of the strong scattering region in step S3, through the scattering paths of electromagnetic waves in the special-shaped cavity in step S2, identify the concentrated regions on the inner wall of the special-shaped cavity and the angles with the normal directions of the concentrated regions on the inner wall of the special-shaped cavity when the incident angles of electromagnetic waves are ±15° and ±(15° to 30°), so as to obtain the incident angles of electromagnetic waves irradiating on the strong scattering region.

[0019] Furthermore, the working angle of the composite metamaterial in step S4 is the angle with the normal direction of the concentrated region identified in step S3, and it is composed of a deflective metamaterial and an absorbing material.

[0020] Furthermore, the deflective metamaterial is composed of a metal array structure and a dielectric substrate, and the absorbing material includes a traditional absorbing coating and a metamaterial absorbing structure.

[0021] Furthermore, the layout of the composite metamaterial in step S5 is to lay the composite metamaterial working at a specific angle in the concentrated region of electromagnetic waves on the inner wall of the special-shaped cavity identified in step S3, and lay a traditional absorbing coating in other regions.

[0022] Furthermore, in step S6, the full-wave frequency-domain algorithm is used to evaluate the scattering magnitude within the incident angle range of -30° to 30° of the special-shaped cavity after laying the composite metamaterial, and compare it with the calculation result in step S1 to evaluate the scattering reduction effect of the scheme.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The present invention can achieve the separation of geometric shape and electromagnetic shape through multiple mechanisms. By scattering and deflecting electromagnetic waves, the reflection angle of electromagnetic waves is regulated, the number of reflections of electromagnetic waves in a special-shaped cavity is increased, and combined with the wave-absorbing material on the inner wall of the cavity, scattering and absorption are carried out simultaneously, increasing the number of times of electromagnetic wave loss during reflection, and greatly reducing the electromagnetic scattering of the special-shaped cavity.

[0025] In summary, the present invention can be applied to cavity components such as air intakes, breaking through the technical bottleneck of the contradiction between electromagnetic shape and aerodynamic shape in traditional coating stealth technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic flow chart of the present invention;

[0027] Figure 2 is a schematic diagram of a typical special-shaped cavity structure;

[0028] Figure 3 is a simulation curve graph of horizontal polarization and vertical polarization RCS after the traditional wave-absorbing coating scheme is adopted for the selected special-shaped cavity of the invention;

[0029] Figure 4 is a schematic diagram of the propagation path of electromagnetic waves in a special-shaped cavity, where Figure 4 (a) is the multiple reflection route diagram of electromagnetic waves in the special-shaped cavity when the incident angle range is ±15°,

[0030] and Figure 4 (b) is the multiple reflection route diagram of electromagnetic waves in the special-shaped cavity when the incident angle range is ±(15° - 30°);

[0031] Figure 5 is a schematic diagram of the strong scattering area on the inner wall divided according to the propagation path of electromagnetic waves in the special-shaped cavity; when the incident angle range is ±15°, the strong scattering areas are distributed in No. 2, No. 4, and No. 5, and when the incident angle range is ±(15° - 30°)

[0032] the strong scattering areas are distributed in No. 1, No. 3, and No. 6 areas;

[0033] Figure 6 is a comparison graph of the horizontal polarization RCS simulation curves of the special-shaped cavity with the composite mechanism scattering reduction scheme and the traditional wave-absorbing coating scheme.

[0034] Figure 7 is a comparison graph of the vertical polarization RCS simulation curves of the special-shaped cavity with the composite mechanism scattering reduction scheme and the traditional wave-absorbing coating scheme; DETAILED DESCRIPTION OF THE INVENTION

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] As Figure 1-7 shown, a multi-mechanism composite scattering reduction method for a special-shaped cavity structure includes the following steps:

[0037] S1: Perform scattering diagnosis on the special-shaped cavity through the frequency-domain full-wave algorithm to obtain the RCS magnitude of the special-shaped cavity;

[0038] The specific content of S1 includes: using the fast multi-level multi-pole algorithm to simulate and calculate the RCS magnitude of the special-shaped cavity within the incident angle range of -30° to 30° of the special-shaped cavity. The traditional absorbing coating stealth scheme is adopted for the special-shaped cavity, and the absorbing coating mainly works in the X band. Simulate the RCS curves in the ±30° angular range of the X band and statistically calculate the mean value. Simulate the horizontal polarization and vertical polarization, with an angular interval of 1°. The calculated horizontal polarization RCS mean value is -36.94 dBsm, and the vertical polarization RCS mean value is -33.59 dBsm;

[0039] Among them, the frequency-domain full-wave algorithm also realizes the simulation and calculation of the RCS magnitude of the special-shaped cavity within the incident angle range of -30° to 30° of the special-shaped cavity through the finite element method, the method of moments, and the boundary element method.

[0040] S2: Analyze the electromagnetic wave scattering path in the special-shaped cavity to obtain the strong scattering region;

[0041] The specific content of S2 includes: using the shooting and bouncing ray method to analyze the electromagnetic wave scattering path in the special-shaped cavity, setting the maximum number of reflections to 30 times to ensure that all electromagnetic waves can have a complete propagation path on the inner wall of the special-shaped cavity. Analyze the scattering path of electromagnetic waves in the special-shaped cavity in two angular ranges of ±15° and ±(15° to 30°), identify the concentrated region of electromagnetic waves on the inner wall of the special-shaped cavity, and divide the strong scattering region according to the reflection regions of electromagnetic waves on the inner wall of the special-shaped cavity in the two angular ranges of ±15° and ±(15° to 30°);

[0042] Among them, the shooting and bouncing ray method can be replaced by the physical optics method.

[0043] S3: Based on the identification of the strong scattering region, obtain the incident angle of the electromagnetic wave irradiating the strong scattering region;

[0044] The specific content of S3 includes: statistically calculating the normal angle between the electromagnetic wave and the inner wall area of the special-shaped cavity during each reflection. When the incident angle is in the angular range of ±15°, the angle is around 70°. When the incident angle is in the angular range of ±(15° - 30°), the angle is around 50°, so as to obtain the incident angle of the electromagnetic wave irradiating the strong scattering area.

[0045] S4: Design a deflection / absorbing composite metamaterial based on the incident angle of the electromagnetic wave in the strong scattering area to obtain a deflection / absorbing composite metamaterial;

[0046] The specific content of S4 includes: respectively designing deflection / absorbing composite metamaterials for incident angles of 50° and 70°. The working band is designed as the X band, and the deflection angle is less than the incident angle to increase the number of reflections of the electromagnetic wave in the special-shaped cavity.

[0047] S5: Deploy the composite metamaterial in the strong scattering area, and deploy traditional absorbing coatings in other areas of the special-shaped cavity to obtain a new special-shaped cavity;

[0048] The specific content of S5 includes: deploying the designed deflection / absorbing composite metamaterial with a working angle of 50° in areas ①

[0049] , ③ and ⑥, and deploying the deflection / absorbing composite metamaterial with a working angle of 70° in areas ②, ④ and ⑤

[0050] (as shown in Figure 5 ), and deploying traditional absorbing coatings in other areas.

[0051] S6: Evaluate the scattering reduction effect of the new special-shaped cavity;

[0052] The specific content of S6 includes: simulating the RCS curve of the special-shaped cavity using the multi-mechanism composite scattering reduction method with the same settings as in the first step and statistically calculating the mean value. Compared with the traditional absorbing coating stealth scheme, the horizontal polarization is reduced by 5.70 dB, and the vertical polarization is reduced by 6.43 dB, which proves the feasibility of the scheme.

[0053] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-mechanism composite scattering reduction method for special-shaped cavity structures, characterized in that It includes the following steps: S1: Conduct scattering diagnosis on the special-shaped cavity through the full-wave frequency-domain algorithm to obtain the RCS magnitude of the special-shaped cavity; S2: Analyze the electromagnetic wave scattering path in the special-shaped cavity to obtain the strong scattering region; S3: Based on the identification of the strong scattering region, obtain the incident angle of the electromagnetic wave irradiating the strong scattering region; S4: Design the deflection / absorbing composite metamaterial based on the incident angle of the electromagnetic wave in the strong scattering region to obtain the composite metamaterial, where the deflection angle of the composite metamaterial is less than the incident angle to increase the number of reflections of the electromagnetic wave in the special-shaped cavity; S5: Deploy the composite metamaterial in the strong scattering region, and deploy the traditional absorbing coating in other regions of the special-shaped cavity to obtain a new special-shaped cavity; S6: Evaluate the scattering reduction effect of the new special-shaped cavity.

2. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 1, characterized in that: The full-wave frequency-domain algorithm used in step S1 includes the finite element method, the method of moments, the boundary element method, and the multilevel fast multipole method, which are used to simulate and calculate the RCS magnitude of the special-shaped cavity in the incident angle range of -30° to 30° of the special-shaped cavity.

3. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 1, characterized in that: The asymptotic algorithm used in step S2 includes the physical optics method and the shooting and bouncing ray method to analyze the scattering path and concentration region of the electromagnetic wave in the special-shaped cavity within the incident angle ranges of ±15° and ±(15° to 30°) to obtain the strong scattering region.

4. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 3, characterized in that: For the identification of the strong scattering region in step S3, through the scattering path of the electromagnetic wave in the special-shaped cavity in step S2, identify the concentrated region on the inner wall of the special-shaped cavity and the angle with the normal direction of the concentrated region on the inner wall of the special-shaped cavity when the incident angle of the electromagnetic wave is in the ranges of ±15° and ±(15° to 30°), so as to obtain the incident angle of the electromagnetic wave irradiating the strong scattering region.

5. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 4, characterized in that: The working angle of the composite metamaterial in step S4 is the angle with the normal direction of the concentrated region identified in step S3, and it is composed of the deflection metamaterial and the absorbing material.

6. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 5, characterized in that: The deflection metamaterial is composed of a metal array structure and a dielectric substrate, and the absorbing material includes a traditional absorbing coating and a metamaterial absorbing structure.

7. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 4, characterized in that: The deployment of the composite metamaterial in step S5 is to deploy the composite metamaterial working at the incident angle in the strong scattering region in the concentrated region of the electromagnetic wave on the inner wall of the special-shaped cavity identified in step S3, and deploy the traditional absorbing coating in other regions.

8. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 1, characterized in that: In step S6, the full-wave frequency-domain algorithm is used to evaluate the scattering magnitude of the special-shaped cavity within the incident angle range of -30° to 30° after deploying the composite metamaterial, and compare it with the calculation result in step S1 to evaluate the scattering reduction effect of the scheme.

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