Multi-mechanism composite scattering reduction method for special-shaped cavity structure

Abstract

The invention relates to a multi-mechanism composite scattering reduction method for a special-shaped cavity structure, and the method comprises the following steps: S1, carrying out the scattering diagnosis of a special-shaped cavity through a frequency domain full-wave algorithm, and obtaining the RCS order of magnitude of the special-shaped cavity, S2, analyzing the scattering path of electromagnetic waves in the special-shaped cavity, and obtaining a strong scattering region, and S3, carrying out the recognition based on the strong scattering region, and carrying out the recognition of the RCS order of the special-shaped cavity. S4, designing a deflection / wave-absorbing composite metamaterial based on the incident angle of the electromagnetic wave in the strong scattering area to obtain a composite metamaterial, and S5, laying the composite metamaterial in the strong scattering area, laying a traditional wave-absorbing coating in other areas of the special-shaped cavity to obtain a new special-shaped cavity, and carrying out the design of the deflection / wave-absorbing composite metamaterial. S6, evaluating the scattering reduction effect of the new special-shaped cavity; the invention has the advantages that the geometric shape and the electromagnetic shape are separated, and the technical bottleneck of contradiction between aerodynamic performance and low scattering performance is broken through.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic wave stealth, and in particular relates to a multi-mechanism composite scattering reduction method for a special-shaped cavity structure. Background Art

[0002] The scattering of irregular cavities is one of the scattering sources with the strongest impact on the forward angle domain of combat aircraft. The control of its scattering level has a decisive influence on the electromagnetic stealth performance of the aircraft. The shape of the irregular cavity needs to comprehensively consider aerodynamic performance and stealth performance during the design process. Good stealth requires a larger cavity curvature, while the cavity curvature cannot be too large based on aerodynamic performance considerations. The two are often contradictory, further increasing the difficulty of reducing the design of irregular cavity scattering.

[0003] At present, the main solution for reducing scattering in special-shaped cavities is to apply magnetic absorbing paint on the inner wall, which has the following shortcomings: (1) The absorption effect of traditional absorbing coatings will deteriorate when electromagnetic waves are irradiated at a large angle, and the absorption bandwidth is narrow; (2) Due to the shape of the cavity, the number of times the electromagnetic wave is reflected on the inner wall of the cavity is limited, the loss of the absorbing material is limited, and the scattering reduction effect is not obvious.

[0004] Therefore, in view of the contradiction between stealth and aerodynamic design in the process of stealth design of the air inlet, forming a design method to achieve the separation of electromagnetic and geometric shape is an important means to achieve the reduction of cavity scattering. Summary of the invention

[0005] 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 special-shaped cavity structures that has the characteristics of separating geometric shape and electromagnetic shape and breaking through the technical bottleneck of the contradiction between aerodynamic performance and low scattering performance.

[0006] The technical solution of the present invention is as follows: A multi-mechanism composite scattering reduction method for a special-shaped cavity structure comprises the following steps: S1: Use the frequency domain full-wave algorithm to diagnose the scattering of the special-shaped cavity and 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 area; S3: Based on the identification of the strong scattering area, the incident angle of the electromagnetic wave irradiating the strong scattering area is obtained; S4: Design a deflection / absorption composite metamaterial based on the incident angle of electromagnetic waves in the strong scattering region to obtain a composite metamaterial; S5: The composite metamaterial is arranged in the strong scattering area, and the traditional absorbing coating is arranged in other areas of the special-shaped cavity to obtain a new special-shaped cavity; S6: Evaluate the scattering reduction effect of the new special-shaped cavity.

[0007] Furthermore, the frequency domain full-wave algorithm used in step S1 includes finite element method, moment method, boundary element method, and multi-layer fast multipole method, which is used to simulate and calculate the RCS magnitude of the special-shaped cavity within the incident angle range of -30° to 30°.

[0008] Furthermore, in step S2, asymptotic algorithms including physical optics method and bouncing ray method are used to analyze the scattering path and concentrated area of ​​electromagnetic waves in the irregular cavity within the incident angle domain of ±15° and ±(15°~30°) to obtain a strong scattering area.

[0009] Furthermore, the strong scattering area is identified in step S3 by identifying the scattering path of the electromagnetic wave in the irregular cavity in step S2, and the angle between the concentrated area on the inner wall of the irregular cavity and the normal of the concentrated area on the inner wall of the irregular cavity when the incident angle of the electromagnetic wave is in the range of ±15° and ±(15°~30°), so as to obtain the incident angle of the electromagnetic wave irradiating the strong scattering area.

[0010] Furthermore, the working angle of the composite metamaterial in step S4 is the angle of the normal of the concentrated area identified in step S3, and is formed by combining the deflection metamaterial and the absorbing material.

[0011] Furthermore, 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.

[0012] Furthermore, the composite metamaterial arrangement in step S5 is to arrange the composite metamaterial working at a specific angle in the electromagnetic wave concentration area on the inner wall of the special-shaped cavity identified in step S3, and arrange traditional absorbing coatings in other areas.

[0013] Furthermore, in step S6, a frequency domain full-wave algorithm is used to evaluate the scattering magnitude of the special-shaped cavity within the incident angle range of -30° to 30° after the composite metamaterial is deployed, and compared with the calculation result in step S1 to evaluate the scattering reduction effect of the scheme.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention can realize the separation of geometric shape and electromagnetic shape through multi-mechanism combination, adjust the reflection angle of electromagnetic waves through the scattering and deflection of electromagnetic waves, increase the number of reflections of electromagnetic waves in the special-shaped cavity, and combine with the absorbing material on the inner wall of the cavity to scatter and absorb at the same time, increase the number of times electromagnetic waves are lost in reflection, and greatly reduce the electromagnetic scattering of the special-shaped cavity.

[0015] In short, the present invention can be applied to cavity parts such as air inlets, breaking through the technical bottleneck of the contradiction between the electromagnetic shape and the aerodynamic shape of traditional coating stealth technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 It is a schematic diagram of a typical special-shaped cavity structure; Figure 3 The horizontal polarization and vertical polarization RCS simulation curves of the special-shaped cavity selected for the invention after adopting the traditional absorbing coating solution; Figure 4 Schematic diagram of the propagation path of electromagnetic waves in a special-shaped cavity, where Figure 4 (a) is the path diagram of multiple reflections of electromagnetic waves in the special-shaped cavity when the incident angle range is ±15°. Figure 4 (b) is the path diagram of multiple reflections of electromagnetic waves in the special-shaped cavity when the incident angle range is ±(15°~30°); Figure 5 The figure is a schematic diagram of the strong scattering area of ​​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 areas ②, ④ and ⑤; when the incident angle range is ±(15°~30°), the strong scattering areas are distributed in areas ①, ③ and ⑥; Figure 6 This is a comparison of the horizontally polarized RCS simulation curves of the special-shaped cavity after adopting the composite mechanism scattering reduction scheme and the traditional absorbing coating scheme; Figure 7 This is a comparison of the vertically polarized RCS simulation curves of the special-shaped cavity after adopting the composite mechanism scattering reduction scheme and the traditional absorbing coating scheme; DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] like Figure 1-7 As shown, a multi-mechanism composite scattering reduction method for a special-shaped cavity structure includes the following steps: S1: Use the frequency domain full-wave algorithm to diagnose the scattering of the special-shaped cavity and obtain the RCS magnitude of the special-shaped cavity; The specific contents of S1 include: using fast multi-layer multipole algorithm to simulate and calculate the RCS magnitude of the shaped cavity within the incident angle range of -30°~30°. The shaped cavity adopts the traditional absorbing coating stealth solution. The absorbing coating mainly works in the X-band. The X-band ±30° angular domain RCS curve is simulated and the average value is calculated. The horizontal polarization and vertical polarization are simulated. The simulation angular domain interval is 1°. The calculated horizontal polarization RCS average is -36.94dBsm, and the vertical polarization RCS average is -33.59dBsm. The frequency domain full-wave algorithm also uses the finite element method, moment method, and boundary element method to simulate the RCS magnitude of the special-shaped cavity within the incident angle range of -30°~30°.

[0019] S2: Analyze the electromagnetic wave scattering path in the special-shaped cavity to obtain the strong scattering area; The specific contents of S2 include: using the bouncing ray method to analyze the electromagnetic wave scattering path in the special-shaped cavity, setting the maximum number of reflections to 30 times, ensuring that all electromagnetic waves have a complete propagation path on the inner wall of the special-shaped cavity, dividing the electromagnetic wave scattering path in the special-shaped cavity into two angular domains of ±15° and ±(15°~30°), identifying the concentrated area of ​​the electromagnetic wave on the inner wall of the special-shaped cavity, and dividing the strong scattering area according to the reflection area of ​​the electromagnetic wave on the inner wall of the special-shaped cavity in the two angular domains of ±15° and ±(15°~30°); Among them, the bouncing ray method can be replaced by the physical optics method.

[0020] S3: Based on the identification of the strong scattering area, the incident angle of the electromagnetic wave irradiating the strong scattering area is obtained; The specific contents of S3 include: calculating the angle between the electromagnetic wave and the normal of the inner wall area of ​​the irregular cavity at each reflection, which is about 70° when incident in the ±15° angular domain and about 50° when incident in the ±(15°~30°) angular domain, so as to obtain the incident angle of the electromagnetic wave irradiating the strong scattering area.

[0021] S4: Design a deflection / absorption composite metamaterial based on the incident angle of electromagnetic waves in the strong scattering region to obtain a deflection / absorption composite metamaterial; The specific contents of S4 include: designing deflection / absorbing composite metamaterials for incident angles of 50° and 70° respectively, the working band is designed to be X-band, and the deflection angle is smaller than the incident angle to increase the number of reflections of electromagnetic waves in the special-shaped cavity.

[0022] S5: The composite metamaterial is arranged in the strong scattering area, and the traditional absorbing coating is arranged in other areas of the special-shaped cavity to obtain a new special-shaped cavity; The specific contents of S5 include: arranging the designed deflection / absorbing composite metamaterial with a working angle of 50° in areas ①, ③ and ⑥, and arranging the deflection / absorbing composite metamaterial with a working angle of 70° in areas ②, ④ and ⑤ (such as Figure 5 As shown in the figure), other areas are covered with traditional absorbing coatings.

[0023] S6: Evaluate the scatter reduction effect of the new shaped cavity; The specific contents of S6 include: using the same settings as the first step to simulate the RCS curve of the special-shaped cavity using the multi-mechanism composite scattering reduction method and statistically average it. Compared with the traditional radar-absorbing coating stealth solution, the horizontal polarization is reduced by 5.70dB and the vertical polarization is reduced by 6.43dB, proving the feasibility of the solution.

[0024] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-mechanism composite scattering reduction method for a special-shaped cavity structure, characterized in that: The steps include: S1: Use the frequency domain full-wave algorithm to diagnose the scattering of the special-shaped cavity and 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 area; S3: Based on the identification of the strong scattering area, the incident angle of the electromagnetic wave irradiating the strong scattering area is obtained; S4: Design a deflection / absorption composite metamaterial based on the incident angle of electromagnetic waves in the strong scattering region to obtain a composite metamaterial; S5: The composite metamaterial is arranged in the strong scattering area, and the traditional absorbing coating is arranged in other areas 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. The multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 1, characterized in that: The frequency domain full-wave algorithm used in step S1 includes finite element method, moment method, boundary element method, and multi-layer fast multipole method, which is used to simulate and calculate the RCS magnitude of the special-shaped cavity within the incident angle range of -30° to 30°.

3. The multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 1, characterized in that: In step S2, asymptotic algorithms including physical optics method and bouncing ray method are used to analyze the scattering path and concentrated area of ​​electromagnetic waves in the irregular cavity within the incident angle domain of ±15° and ±(15°~30°) to obtain a strong scattering area.

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

5. The 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 of the normal of the concentrated area identified in step S3, and is formed by combining the deflection metamaterial and the absorbing material.

6. The 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. The multi-mechanism composite scattering reduction method for a special-shaped cavity structure according to claim 4, characterized in that: The composite metamaterial arrangement in step S5 is to arrange the composite metamaterial working at a specific angle in the electromagnetic wave concentration area on the inner wall of the special-shaped cavity identified in step S3, and arrange traditional absorbing coatings in other areas.

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

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