A method for identifying electromagnetic sensitive areas on aircraft surfaces

Abstract

The present application belongs to the field of aircraft design technology, and particularly relates to a method for identifying electromagnetic sensitive areas on aircraft surfaces. The method comprises step S1, a panel is provided in front of the aircraft, a ray source of uniform density is provided on the panel, and the ray source is directed to the surface of the aircraft in a direction parallel to the X-axis of the aircraft; step S2, the density of ray landing points on the surface of the aircraft is counted to obtain the illuminated area with the highest landing point density, the shadow area with the lowest landing point density, and the transition area between the two; step S3, using rays to simulate electromagnetic waves, the rays are directed to the surface of the aircraft in a direction parallel to the X-axis of the aircraft in front of the aircraft, and the emitted energy of the rays after irradiating the surface of the aircraft is calculated; step S4, the area where the emitted energy accounts for more than 60% of the incident energy is counted as a high scattering area; step S5, the high scattering area, or the illuminated area and the transition area are regarded as the electromagnetic sensitive area on the surface of the aircraft. The present application effectively solves key problems such as the zoning layout of airborne equipment and the zoning control of surface electromagnetic defects.

Description

Technical Field

[0001] The present application belongs to the field of aircraft design technology, and in particular relates to a method for identifying electromagnetic sensitive areas on an aircraft surface. Background Art

[0002] Low-scattering design has become a hallmark of modern aircraft, and improving low-scattering performance is a constant pursuit in aircraft design. Conventional low-scattering design methods typically fix some boundary conditions while adjusting and optimizing others. This optimization approach is limited, making it difficult to find the optimal solution and is time-consuming and labor-intensive. Therefore, a scientific low-scattering design boundary optimization method is urgently needed.

[0003] Low-scattering performance evaluation typically requires model simplification, meshing, and numerical analysis to solve Maxwell's equations. This approach is time-consuming and resource-intensive, making it difficult to rapidly iterate solutions. The lack of an intuitive, fast boundary optimization method and a low-scattering performance evaluation method hinders the efficiency of solution iteration in aircraft design, creating a bottleneck. Therefore, establishing a fast low-scattering performance optimization method to accelerate solution iteration is crucial.

[0004] The essence of aircraft low-scattering design lies in controlling the aircraft's scattering sources. Once the aircraft's layout and shape are basically determined, the zoning of onboard equipment, the zoning control of surface electromagnetic defects, and the distribution and application of low-scattering materials will become key issues in low-scattering design. Future aircraft will demand increasingly stringent low-scattering performance, and traditional design optimization methods that rely heavily on experience are increasingly unable to meet these demands. Summary of the Invention

[0005] To address the above issues, this application provides a method for identifying electromagnetically sensitive areas on aircraft surfaces, identifying important sensitive areas requiring low-scattering design, and thus providing a basis for low-scattering design. The method mainly includes:

[0006] Step S1: A panel parallel to the YOZ plane of the aircraft coordinate system is provided in front of the aircraft. A ray source of uniform density is provided on the panel, and the ray source is directed toward the surface of the aircraft in a direction parallel to the X-axis of the aircraft.

[0007] Step S2: Counting the density of the ray landing points on the surface of the body to form an illuminated area with the highest landing point density, a shadow area with the lowest landing point density, and a transition area between the two, each accounting for one-third of the total area;

[0008] Step S3: In CATIA software, use rays to simulate electromagnetic waves, shoot them toward the surface of the aircraft in a direction parallel to the aircraft's X-axis from the front of the aircraft, assign each ray an initial incident energy, and calculate the exit energy of the ray after it hits the aircraft surface;

[0009] Step S4: Counting the area where the outgoing energy accounts for more than 60% of the incident energy as a high scattering area;

[0010] Step S5: Use the high scattering area, or the illumination area and the transition area as the electromagnetic sensitive area on the aircraft surface.

[0011] Preferably, in step S2, the ray landing points are projected onto a cloud map, and the illuminated area, shadow area and transition area are counted through the cloud map.

[0012] Preferably, in step S5, the area where the high scattering area overlaps with the illumination area, and the area where the high scattering area overlaps with the transition area are used as electromagnetic sensitive areas on the aircraft surface.

[0013] Preferably, the area where the high scattering area overlaps with the illumination area is used as the first sensitive area, the area where the high scattering area overlaps with the transition area is used as the second sensitive area, and the remaining high scattering area is used as the third sensitive area. The low scattering design intensity of the first sensitive area is higher than that of the second sensitive area, and the low scattering design intensity of the second sensitive area is higher than that of the third sensitive area.

[0014] Preferably, the low scattering design with high intensity refers to at least one of designing antennas with higher density on the aircraft surface, adding a coating material with higher absorption degree to the aircraft surface, or adding a thicker coating to the aircraft surface.

[0015] Preferably, step S5 further comprises:

[0016] Step S51: obtaining the area of ​​a given region S1 pre-designed as a sensitive area on the aircraft surface;

[0017] Step S52: obtaining the area of ​​the region S2 where the high scattering region overlaps with the illumination region;

[0018] Step S53: If the area of ​​region S1 is smaller than that of region S2, then in region S2, based on the density of the impact points, a region with an area of ​​S1 having a higher density is selected as the electromagnetically sensitive area on the aircraft surface; or in region S2, based on the ratio of the outgoing energy to the incoming energy, a region with an area of ​​S1 having a higher ratio is selected as the electromagnetically sensitive area on the aircraft surface;

[0019] Step S54: If the area of ​​region S1 is larger than that of region S2, calculate the area difference S between region S1 and region S2, select an area of ​​size S*a from the area after excluding the overlapping area of ​​the high scattering area as the first compensation area, and select an area of ​​size S*b from the area after excluding the overlapping area of ​​the illuminated area as the second compensation area. Region S1, the first compensation area, and the second compensation area together constitute the electromagnetic sensitive area of ​​the aircraft surface, where a is the compensation weight of the high scattering area, b is the compensation weight of the illuminated area, and a+b=1.

[0020] Preferably, a is 0.8 and b is 0.2.

[0021] Preferably, in step S54, forming the first compensation area includes selecting an area with a higher density as the first compensation area according to the landing point density in the area after discarding the overlapping area of ​​the high scattering area.

[0022] Preferably, in step S54, forming the second compensation area includes selecting an area with a higher ratio of the outgoing energy to the incident energy in the area after discarding the overlapping area of ​​the high scattering area as the second compensation area.

[0023] This application combines ray-based electromagnetic wave simulation and statistical ray distribution in CATIA to identify optimal design boundaries and evaluate low-scattering performance. This effectively addresses key issues such as the zoning of airborne equipment, zoning control of surface electromagnetic defects, the distributed application of low-scattering materials, and rapid evaluation of low-scattering performance. This preliminary approach to low-scattering design optimization has been established. This approach has been applied to aircraft low-scattering design. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a preferred embodiment of the method for identifying electromagnetic sensitive areas on the surface of an aircraft according to the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.

[0026] This application provides a method for identifying electromagnetic sensitive areas on an aircraft surface, such as Figure 1 As shown, it mainly includes:

[0027] Step S1: A panel parallel to the YOZ plane of the aircraft coordinate system is provided in front of the aircraft. A ray source of uniform density is provided on the panel, and the ray source is directed toward the surface of the aircraft in a direction parallel to the X-axis of the aircraft.

[0028] Step S2: Counting the density of the ray landing points on the surface of the body to form an illuminated area with the highest landing point density, a shadow area with the lowest landing point density, and a transition area between the two, each accounting for one-third of the total area;

[0029] Step S3: In CATIA software, use rays to simulate electromagnetic waves, shoot them toward the surface of the aircraft in a direction parallel to the aircraft's X-axis from the front of the aircraft, assign each ray an initial incident energy, and calculate the exit energy of the ray after it hits the aircraft surface;

[0030] Step S4: Counting the area where the outgoing energy accounts for more than 60% of the incident energy as a high scattering area;

[0031] Step S5: Use the high scattering area, or the illumination area and the transition area as the electromagnetic sensitive area on the aircraft surface.

[0032] First of all, it should be noted that the body coordinate system is established to determine the relative position, velocity, acceleration, and components of the external force vector when establishing the aircraft's motion equations or representing various positions on the aircraft. Commonly used coordinate axis systems all use right-handed rectangular coordinate systems. In order to describe the motion state of the aircraft, an appropriate coordinate system must be selected. In step S1, the coordinate system involved is the body coordinate system OXYZ commonly used by those skilled in the art. This is a coordinate system fixed to the aircraft body, with the origin at the center of gravity of the aircraft. The X-axis is consistent with the aircraft's longitudinal axis and points to the front of the aircraft; the Y-axis is perpendicular to the aircraft's plane of symmetry and points to the right; the Z-axis is within the aircraft's plane of symmetry and perpendicular to the longitudinal axis, pointing downward.

[0033] It should also be noted that the panel set in front of the aircraft must be large enough to at least ensure that the radiation source on the panel can cover all surfaces of the aircraft body when shining towards the aircraft along the X-axis of the aircraft coordinate system.

[0034] In steps S1 and S2, the present application selects the illuminated area and / or transition area as one type of aircraft surface electromagnetic sensitive area based on the density of the landing point, and determines the boundaries of each electromagnetic sensitive area. In steps S3 and S4, the application uses ray simulation of electromagnetic waves in CATIA to select high-scattering areas as another type of aircraft surface electromagnetic sensitive area, and determines the boundaries of each electromagnetic sensitive area. In step S5, the final aircraft surface electromagnetic sensitive area is selected from these two types of aircraft surface electromagnetic sensitive areas. In alternative embodiments, the above two partition boundary optimization strategies can be used separately or in combination, and are described below.

[0035] 1. Partition Boundary Optimization Strategy Based on Ray Landing Point Distribution Statistics

[0036] Airborne equipment and surface electromagnetic defects are important elements in low-scattering design. In order to balance low-scattering and performance requirements, the airborne design is arranged in zones in low-scattering design. In order to balance low-scattering and manufacturing requirements, surface electromagnetic defects are controlled in zones in low-scattering design. The key to zone control is to obtain the boundaries of illuminated areas, transition areas, shadow areas, and other areas on the aircraft surface. Traditional designs usually adopt the method of visual inspection, point selection, and line connection in CATIA, which is time-consuming, labor-intensive, low-precision, and unable to accurately define transition areas. These extensive design methods have been unable to meet the increasingly high low-scattering index requirements, and there is an urgent need to find a refined way to obtain zone boundaries. The application of low-scattering materials is a key link in the low-scattering design of aircraft. The thickness of the low-scattering material is directly related to the low-scattering performance, but the increase in the thickness of the low-scattering material also comes at a weight cost. Low-scattering materials are usually distributed and applied to achieve a balance between weight and performance. The key to the distribution of low-scattering materials is to find the key scattering points on the aircraft and apply thick or high-performance materials at key locations, so as to "use good steel on the blade" and achieve optimal low-scattering performance.

[0037] In terms of a partition boundary optimization strategy based on ray landing point distribution statistics, the problem of zoning the aircraft's surface electromagnetic wave illuminated, transitional, and shadowed areas is transformed into a problem of ray landing point density. Taking into account the aircraft's most frequently used attitude angles, a sufficiently large plane is set in front of the aircraft. A large number of points are evenly selected on this plane. Rays are drawn parallel to the x-axis along these points toward the aircraft's surface. Finally, the ray landing point density is calculated. The area with the highest density is the illuminated area, followed by the transition area, and the area with the lowest density is the shadow area. This strategy can be used independently to guide aircraft antenna placement, surface electromagnetic defect zoning control, and the application of low-scattering materials, with excellent results.

[0038] 2. Rapid evaluation strategy of low-scattering performance based on energy tracking

[0039] This strategy, based primarily on the Monte Carlo method, simulates electromagnetic waves using rays in CATIA. Each ray is assigned an initial energy, and the energy loss of the rays is tracked. The energy of the outgoing rays is then calculated, and the RCS scattering value is derived by comparing the incident and outgoing energies. The greater the outgoing energy, the more sensitive the corresponding aircraft surface area. Generally, when the incident energy is equivalent to 1, an outgoing energy exceeding 0.6 is considered an electromagnetically sensitive area.

[0040] It's worth noting that this method doesn't require model simplification and can account for complex aircraft structures, such as engine blades and structural thickness. This significantly simplifies the aircraft low-scattering performance evaluation process, allowing it to be completed directly within CATIA. Furthermore, it eliminates the need for model simplification, simulating realistic aircraft conditions. This significantly improves evaluation efficiency, reducing the low-scattering performance evaluation process from several days to just a few minutes.

[0041] In some optional embodiments, in step S2, the illuminated area, shadow area, and transition area are counted by projecting the ray landing point onto a cloud map. In this embodiment, the cloud map can intuitively show which areas of the aircraft surface belong to the illuminated area and which areas belong to the shadow area.

[0042] In some optional embodiments, in step S5, the area where the high scattering area overlaps with the illuminated area, and the area where the high scattering area overlaps with the transition area are used as electromagnetic sensitive areas on the aircraft surface. In this embodiment, step S5 combines the illuminated area and the transition area formed by the partition boundary optimization strategy based on the ray landing point distribution statistics with the high scattering area formed by the low scattering performance rapid evaluation strategy based on energy tracing, and uses the overlapping area as the electromagnetic sensitive area on the aircraft surface. In an alternative embodiment, the illuminated area and the transition area formed by the partition boundary optimization strategy based on the ray landing point distribution statistics, and the high scattering area formed by the low scattering performance rapid evaluation strategy based on energy tracing can also be used as electromagnetic sensitive areas on the aircraft surface.

[0043] In some optional embodiments, the area where the high scattering area overlaps with the illumination area is used as the first sensitive area, the area where the high scattering area overlaps with the transition area is used as the second sensitive area, and the remaining high scattering area is used as the third sensitive area. The low scattering design intensity of the first sensitive area is higher than that of the second sensitive area, and the low scattering design intensity of the second sensitive area is higher than that of the third sensitive area.

[0044] In some optional embodiments, the low scattering design with high intensity refers to at least one of designing antennas with a higher density on the aircraft surface, adding a coating material with a higher absorption degree to the aircraft surface, or adding a thicker coating to the aircraft surface.

[0045] It can be understood that the above embodiment further divides the electromagnetic sensitive area into areas with different sensitivity levels, and then carries out targeted low-scattering design. For example, the coating designed in the first sensitive area on the aircraft surface is thicker, the coating designed in the second sensitive area is the second thickest, and the coating designed in the third sensitive area is the thinnest.

[0046] In some optional implementations, step S5 further includes:

[0047] Step S51: obtaining the area of ​​a given region S1 pre-designed as a sensitive area on the aircraft surface;

[0048] Step S52: obtaining the area of ​​the region S2 where the high scattering region overlaps with the illumination region;

[0049] Step S53: If the area of ​​region S1 is smaller than that of region S2, then in region S2, based on the density of the impact points, a region with an area of ​​S1 having a higher density is selected as the electromagnetically sensitive area on the aircraft surface; or in region S2, based on the ratio of the outgoing energy to the incoming energy, a region with an area of ​​S1 having a higher ratio is selected as the electromagnetically sensitive area on the aircraft surface;

[0050] Step S54: If the area of ​​region S1 is larger than that of region S2, calculate the area difference S between region S1 and region S2, select an area of ​​size S*a from the area after excluding the overlapping area of ​​the high scattering area as the first compensation area, and select an area of ​​size S*b from the area after excluding the overlapping area of ​​the illuminated area as the second compensation area. Region S1, the first compensation area, and the second compensation area together constitute the electromagnetic sensitive area of ​​the aircraft surface, where a is the compensation weight of the high scattering area, b is the compensation weight of the illuminated area, and a+b=1.

[0051] For this embodiment, two sub-embodiments are listed below for illustration.

[0052] In the first sub-embodiment, step S51 is used to obtain the low-scattering target given by the top-level design. For example, it is intended to implement a low-scattering design scheme for the surface coating in an area S1 that is 10% of the aircraft surface. According to the description of steps S1 to S4 of this application, the area of ​​the illumination area is approximately 33%, while the area of ​​the high-scattering area is assumed to be 60%, and the overlapping area S2 of the two is assumed to be 20%. Therefore, it can be seen that 10% of the area needs to be selected from this 20% overlapping area S2 as the final design area. To this end, in step S53, from this 20% overlapping area S2, an area with an area size of 10% with a high density can be selected as the electromagnetic sensitive area of ​​the aircraft surface according to the density of the landing points. In another alternative embodiment, an area with an area size of 10% with a high density can also be selected from this 20% area S2 according to the ratio of the outgoing energy to the incident energy as the electromagnetic sensitive area of ​​the aircraft surface.

[0053] In sub-embodiment 2, step S51 is used to obtain a low-scattering target given by the top-level design. For example, a low-scattering surface coating design is intended to be implemented in an area S1 of 50% of the aircraft surface. According to the description of steps S1 through S4 of this application, the illuminated area is approximately 33%, while the high-scattering area is assumed to be 60%. The overlap area S2 between the two is assumed to be 20%. Therefore, it is necessary to select an additional 30% of the area to compensate for the overlap area S2, so that together with the 20% overlap area, a 50% electromagnetically sensitive area on the aircraft surface is formed. To this end, in step S54, it is first determined that after removing the 20% overlap area from the 60% high-scattering area, 40% of the first area remains. After removing the 20% overlap area from the 33% illuminated area, approximately 13% of the second area remains. The 30% area requiring compensation is then divided and compensated according to weights. For example, 24% of the first area is selected as the first compensation area with a weight of 0.8, and 6% of the second area is selected as the second compensation area with a weight of 0.2.

[0054] In other alternative implementations, a and b may both be designed to be 0.5, and the values ​​of weights a and b indicate the importance of the above two strategies.

[0055] In some optional embodiments, in step S54, forming the first compensation area includes, in the area after discarding the overlapping area of ​​the high scattering area, selecting an area with a higher density as the first compensation area according to the density of the landing points. Still taking the above case as an example, in the process of selecting 24% of the area from the first area as the first compensation area according to the weight of 0.8, it is preferred to select an area with a higher density from the first area according to the density of the landing points, thereby taking into account the above two strategies. Similarly, in step S54, forming the second compensation area includes, in the area after discarding the overlapping area of ​​the high scattering area, selecting an area with a higher ratio as the second compensation area according to the ratio of the outgoing energy to the incident energy, that is, in the process of selecting 6% of the area from the second area as the second compensation area according to the weight of 0.2, it is preferred to select an area with a higher ratio as the ratio of the outgoing energy to the incident energy from the second area, also taking into account the above two strategies.

[0056] It should also be noted that, for the above embodiment, if a sufficient area cannot be selected from the first region as the first compensation region based on the proportion, compensation is selected from the second region. Correspondingly, if a sufficient area cannot be selected from the second region as the second compensation region based on the proportion, compensation is selected from the first region. If the conditions are still not met, the initial parameters are modified, for example, the parameters for selecting the high-scattering region in step S4 are modified to define the region where the outgoing energy accounts for 50% (or less) of the incoming energy as the high-scattering region.

[0057] This application combines ray-based electromagnetic wave simulation and statistical ray distribution in CATIA to identify optimal design boundaries and evaluate low-scattering performance. This effectively addresses key issues such as the zoning of airborne equipment, zoning control of surface electromagnetic defects, the distributed application of low-scattering materials, and rapid evaluation of low-scattering performance. This preliminary approach to low-scattering design optimization has been established. This approach has been applied to aircraft low-scattering design.

[0058] Although the present application has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present application. Therefore, such modifications or improvements, which do not depart from the spirit of the present application, are within the scope of protection claimed in the present application.

Claims

1. A method for identifying electromagnetic sensitive areas on an aircraft surface, characterized in that: include: Step S1: A panel parallel to the YOZ plane of the aircraft coordinate system is provided in front of the aircraft. A ray source of uniform density is provided on the panel, and the ray source is directed toward the surface of the aircraft in a direction parallel to the X-axis of the aircraft. Step S2: Counting the density of the ray landing points on the surface of the body to form an illuminated area with the highest landing point density, a shadow area with the lowest landing point density, and a transition area between the two, each accounting for one-third of the total area; Step S3: In CATIA software, use rays to simulate electromagnetic waves, shoot them toward the surface of the aircraft in a direction parallel to the aircraft's X-axis from the front of the aircraft, assign each ray an initial incident energy, and calculate the exit energy of the ray after it hits the aircraft surface; Step S4: Counting the area where the outgoing energy accounts for more than 60% of the incident energy as a high scattering area; Step S5: using the high scattering area, or the illumination area and the transition area as an electromagnetic sensitive area on the aircraft surface; Step S5 further comprises: Step S51: obtaining the area of ​​a given region S1 pre-designed as a sensitive area on the aircraft surface; Step S52: obtaining the area of ​​the region S2 where the high scattering region overlaps with the illumination region; Step S53: If the area of ​​region S1 is smaller than that of region S2, then in region S2, based on the density of the impact points, a region with an area of ​​size S1 having a larger density is selected as the electromagnetically sensitive area on the aircraft surface; or in region S2, based on the ratio of the outgoing energy to the incident energy, a region with an area of ​​size S1 having a larger ratio is selected as the electromagnetically sensitive area on the aircraft surface; Step S54: If the area of ​​region S1 is larger than that of region S2, calculate the area difference S between region S1 and region S2, select an area of ​​size S*a from the area after excluding the overlapping area of ​​the high scattering area as the first compensation area, and select an area of ​​size S*b from the area after excluding the overlapping area of ​​the illuminated area as the second compensation area. Region S1, the first compensation area, and the second compensation area together constitute the electromagnetic sensitive area of ​​the aircraft surface, where a is the compensation weight of the high scattering area, b is the compensation weight of the illuminated area, and a+b=1.

2. The method for identifying electromagnetic sensitive areas on an aircraft surface according to claim 1, wherein: In step S2, the ray landing points are projected onto a cloud map, and the illuminated area, shadow area, and transition area are counted through the cloud map.

3. The method for identifying electromagnetic sensitive areas on an aircraft surface according to claim 1, wherein: In step S5, the area where the high scattering area overlaps with the illumination area, and the area where the high scattering area overlaps with the transition area are used as electromagnetic sensitive areas on the aircraft surface.

4. The method for identifying electromagnetic sensitive areas on an aircraft surface according to claim 3, wherein: The area where the high scattering area overlaps with the illumination area is used as the first sensitive area, the area where the high scattering area overlaps with the transition area is used as the second sensitive area, and the remaining high scattering area is used as the third sensitive area. The low scattering design intensity of the first sensitive area is higher than that of the second sensitive area, and the low scattering design intensity of the second sensitive area is higher than that of the third sensitive area.

5. The method for identifying electromagnetic sensitive areas on an aircraft surface according to claim 4, wherein: The low scattering design with high intensity refers to at least one of designing antennas with higher density on the aircraft surface, adding a coating material with higher absorption degree to the aircraft surface, or adding a thicker coating to the aircraft surface.

6. The method for identifying electromagnetic sensitive areas on an aircraft surface according to claim 1, wherein: a is 0.8 and b is 0.

2.

7. The method for identifying electromagnetic sensitive areas on an aircraft surface according to claim 1, wherein: In step S54 , forming the first compensation area includes selecting an area with a larger density as the first compensation area according to the landing point density in the area after discarding the overlapping area of ​​the high scattering area.

8. The method for identifying electromagnetic sensitive areas on an aircraft surface according to claim 1, wherein: In step S54 , forming the second compensation area includes selecting an area with a larger ratio of outgoing energy to incident energy from the area after discarding the overlapping area of ​​the high scattering area as the second compensation area.

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