A low-scattering carrier for wing leading edge RCS testing

Abstract

The application provides a low-scattering carrier for airfoil leading edge RCS testing, which comprises a detachable connection leading edge cover plate and a carrier body, the carrier body and the carrier end face are integrally formed metal hollow structures, the leading edge of the carrier body is a straight line type structure matched with the airfoil leading edge wave absorbing structure, and the trailing edge of the carrier body is a straight line type structure parallel to the leading edge. The low-scattering carrier of the application adopts a water drop shape design, the carrier end face and the carrier body are integrally formed, and the parallel structure of the airfoil leading edge and the trailing edge is used, so that the influence of the edge on the scattering of the test angle domain is reduced, the vertical polarization and horizontal polarization electromagnetic scattering characteristics of the carrier are greatly reduced, and the stealth performance of the carrier in various radar environments is further improved. The low-scattering carrier of the application has a good traveling wave suppression effect, in the X waveband 0-degree-50-degree range, the RCS average of the horizontal direction polarization can reach-45dBsm, and the RCS average of the vertical direction polarization can reach-40dBsm.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic scattering measurement, and more specifically to a low-scattering carrier for RCS testing of the leading edge of an airfoil. Background Technology

[0002] With the continuous development of radar detection technology, the stealth performance of aircraft is required to improve accordingly. Specular scattering from the leading and trailing edges of wings is one of the important scattering sources for aircraft. To improve the survivability of aircraft, radar stealth optimization design is essential. The main approach of existing technologies is to use absorbing structures at the scattering source, performing a transmission-absorption-reflection-absorption-transmission process on the incident radar wave to reduce the intensity of the reflected echo and decrease scattering.

[0003] During the design and development of the absorbing structure, it is necessary to continuously iterate and conduct a large number of data tests and verify simulation calculation results. Since the size of the full-size model of the aircraft or the wing component is larger than the size of the quiet zone of a typical anechoic chamber, it is impossible to conduct RCS tests. Therefore, a low-scattering carrier of the absorbing structure is designed for RCS testing, which allows it to be tested in an anechoic chamber while avoiding the exposure of the internal structure to the outside by testing the leading edge alone, thus preventing it from becoming a new scattering source that affects the test results.

[0004] Patent CN114104331A discloses an absorber for reducing low-frequency scattering. The low-frequency scattering reduction carrier is approximately rhomboid in shape. The advantage of this carrier is that it can reduce low-frequency scattering from the bottom edge of the component under test during RCS testing, enclosing the bottom edge of the component and shielding its internal cavity structure. However, due to shape limitations, it is difficult to use as a low-scattering carrier for RCS testing of slender, dihedral-like wing-shaped leading-edge absorbing structures.

[0005] Patent CN115856774A discloses a low-scattering carrier for RCS testing. This carrier has a double-droplet spliced ​​structure and exhibits good surface current guiding properties, reducing strong scattering sources such as specular scattering and multiple scattering. It also effectively avoids fluctuations in the carrier body within the low-scattering angular domain. However, due to its shape limitations, it is difficult to use as a low-scattering carrier for RCS testing of slender, dihedral-like fin-shaped leading-edge absorbing structures.

[0006] Patent CN114355311A discloses a low-scattering carrier and testing method for RCS testing of wing leading-edge absorbing structures. This low-scattering carrier itself exhibits a low scattering level due to its stealth design. Its unique structure makes it suitable for RCS testing of wing leading-edge absorbing structures, and the testing method based on this carrier can be directly applied to it. The inventors have carefully studied the aforementioned low-scattering carrier structure and provided a low-scattering carrier with an even lower scattering level for RCS testing of wing leading-edge absorbing structures. Summary of the Invention

[0007] The main objective of this invention is to provide a low-scattering carrier for RCS testing of the leading edge of an airfoil. The low-scattering carrier of this invention adopts a teardrop-shaped design, with the carrier end face and the carrier body integrally formed, and uses a parallel structure of the leading and trailing edges of the airfoil. This reduces the influence of the edge on the scattering of the test angular domain, and greatly reduces the vertical and horizontal polarization electromagnetic scattering characteristics of the carrier. In the X-band 0-50 degree range, the average RCS value of the horizontal polarization can reach -45 dBsm, and the average RCS value of the vertical polarization can reach -40 dBsm.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A low-scattering carrier for RCS testing of wing leading edge is used for RCS testing of wing leading edge absorbing structure. The low-scattering carrier includes a leading edge cover plate, a carrier body and a carrier end face. The leading edge cover plate and the carrier body are detachably connected. The carrier body is a flat elongated structure that is thick in the middle and gradually flattens at the front and rear sides. The front and rear ends of the carrier body are teardrop-shaped with one thick and one thin.

[0010] The carrier end face is configured with two faces, one thick and one thin, which are respectively set at the two ends of the flat elongated structure of the carrier body; the two side lines of the carrier end face are parallel.

[0011] The leading edge of the carrier body is a straight structure that fits into the wave-absorbing structure at the leading edge of the wing. The curved surfaces at the connection between the leading edge cover and the carrier body are tangent and continuous without surface steps. The trailing edge of the carrier body is a straight structure that is parallel to the leading edge.

[0012] Optionally, the front edge cover is a cover structure that fits against one side of the front edge of the carrier body and is detachably mounted on one side of the front edge of the carrier body.

[0013] Optionally, the carrier end face is a flat cover structure with the upper and lower curved surfaces contracting into a curve. The edge diffraction of the curve replaces the specular scattering caused by the flat surface of the carrier end face, thereby reducing the lateral RCS.

[0014] Optionally, the carrier end face and the carrier body are integrally formed metal hollow structures. The integral structure of the carrier end face and the carrier body reduces the interference of connection gaps on electromagnetic wave scattering, and the metal material ensures that the carrier has good conductivity and stability.

[0015] Optionally, the included angle between the carrier body and the carrier end face is greater than or equal to 65°. A larger included angle helps to reduce scattering and improve stealth performance.

[0016] Optionally, the width of the carrier body is greater than or equal to 3.2 times the signal wavelength corresponding to the lowest frequency tested during RCS testing.

[0017] Optionally, the carrier has no surface step and a surface roughness of no more than 1.6, thereby reducing the scattering generated when electromagnetic waves propagate on the carrier.

[0018] Optionally, the low-scattering carrier has a length of 4300 mm, a width of 800 mm, and a height of 200 mm.

[0019] Optionally, when testing the wing-side absorbing structure, the leading edge cover is removed and the wing-side absorbing structure is installed; when verifying the RCS of the low-scattering carrier, the leading edge cover is used to shield the cavity of the low-scattering carrier.

[0020] This invention employs shape stealth design measures to design the carrier structure. The continuous, tangential curved surface without surface steps provides excellent current guidance. During RCS testing of dihedral reflector-like absorbing structures such as the leading edge of the wing, it eliminates edge scattering and chaotic scattering caused by internal structural factors in existing absorbing structures, resulting in a low scattering level. Using the described testing method, RCS testing was conducted on a carrier equipped with a leading edge absorbing structure, demonstrating the reduction effect of the leading edge absorbing structure on the peak specular scattering.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The low-scattering carrier of the present invention has a good traveling wave suppression effect. In the X-band 0-50 degree range, the average RCS value of horizontal polarization can reach -45dBsm and the average RCS value of vertical polarization can reach -40dBsm, which has low low-scattering performance. When the carrier is used in combination with the airfoil absorbing structure, the accurate polarization RCS of the airfoil absorbing structure can be obtained.

[0023] 2. The low-scattering carrier of the present invention adopts a teardrop-shaped design and uses a parallel structure of the leading and trailing edges of the wing, which reduces the influence of the edges on the scattering of the test angular domain, greatly reduces the vertical and horizontal polarization electromagnetic scattering characteristics of the carrier, and further improves the stealth performance of the carrier in various radar environments; moreover, the teardrop-shaped design and the parallel structure of the leading and trailing edges of the wing are relatively simple and easy to manufacture and maintain.

[0024] 3. The integrated design and detachable connection of the low-scattering carrier described in this invention improve the accuracy and efficiency of RCS measurement of the wing leading edge radar-absorbing structure, reduce radar interference, and improve the stealth of the aircraft. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings:

[0026] Figure 1 This is an isometric view of the front edge cover plate of the present invention not being installed on the carrier body;

[0027] Figure 2 This is a top view of the front edge cover plate of the present invention not being installed on the carrier body;

[0028] Figure 3 This is an isometric view of the front edge cover plate of the present invention mounted on the carrier body;

[0029] Figure 4 This is a cross-sectional view in the thickness direction of the front edge cover plate of the present invention when it is installed on the carrier body;

[0030] Figure 5 This is a simulation test curve of the low scattering carrier described in this invention in the X-band;

[0031] In the diagram: 1. Front edge cover plate, 2. Carrier body, 3. Carrier end face, 4. Front edge, 5. Rear edge, 6. Seam. Detailed Implementation

[0032] like Figures 1-4 As shown, a low-scattering carrier for RCS testing of a wing leading-edge absorbing structure is provided. The carrier includes a leading-edge cover plate 1, a carrier body 2, and carrier end faces 3. The leading-edge cover plate 1 and the carrier body 2 are detachably connected. The carrier body 2 is a long, elongated structure that gradually flattens outwards, with one end thicker than the other. The cross-section of the carrier body 2 in the thickness direction is a teardrop shape, blunt at the front and pointed at the back. The carrier end faces 3 are configured with two faces, one thick and one thin, corresponding to the two ends of the flat, elongated structure of the carrier body 2. The two side lines of the carrier end faces 3 are parallel, which helps reduce scattering. The leading edge 4 of the carrier body 2 is a straight structure that fits snugly against the wing leading-edge absorbing structure, and the curved surfaces at the connection between the leading-edge cover plate 1 and the carrier body 2 are tangent and continuous without surface steps. The trailing edge 5 of the carrier body 2 is a straight structure parallel to the leading edge 4.

[0033] In a preferred embodiment, the leading edge cover 1 is a cover structure that fits against one side of the leading edge 4 of the carrier body 2. Its shape is the same as that of the leading edge absorbing structure of the wing. It is installed on the carrier body to test the RCS of the all-metal carrier. It can be detached and the leading edge absorbing structure of the wing can be installed in situ to test the RCS of the carrier after the leading edge absorbing structure of the wing is installed.

[0034] In a preferred embodiment, the carrier end face 3 is a curved surface that shrinks into a curve and becomes flat. The edge diffraction of the curve replaces the specular scattering caused by the flat surface of the carrier end face, thereby reducing the lateral RCS.

[0035] In a preferred embodiment, the carrier end face 3 and the carrier body 2 are integrally formed metal hollow structures. The integral forming ensures the continuity and smoothness of the carrier surface, reduces scattering caused by discontinuities at the connection, and the use of metal material can effectively guide current and reduce electromagnetic wave scattering.

[0036] In a preferred embodiment, the angle between the carrier end face 3 and the carrier body 2 is greater than or equal to 65°. A larger angle helps to smooth the transition, reduce edge effects, further reduce scattering, and improve stealth performance.

[0037] In a preferred embodiment, the width of the carrier body 2 is greater than or equal to 3.2 times the signal wavelength corresponding to the lowest frequency tested during RCS testing, so that the carrier body meets the RCS testing requirements for different frequencies.

[0038] In a preferred embodiment, the carrier has no surface step difference and a surface roughness of no more than 1.6, which reduces the scattering generated when electromagnetic waves propagate on the carrier; the continuous curved surface between the carrier body 2 and the front edge cover plate 1 has a good current guiding effect, avoiding the problem of introducing new weak scattering sources due to discontinuous shape changes.

[0039] In a preferred embodiment, the low-scattering carrier has a length of 4300 mm, a width of 800 mm, and a height of 200 mm.

[0040] In a preferred embodiment, when performing RCS testing on the leading edge absorbing structure of the wing, the leading edge cover plate 1 is removed and the leading edge absorbing structure of the wing is installed; when verifying the RCS of the low-scattering carrier, the leading edge cover plate 1 is used to shield the cavity of the low-scattering carrier.

[0041] In testing the RCS of the leading edge absorbing structure of the wing, the leading edge cover plate 1 is removed, and the leading edge absorbing structure is installed in the position of the leading edge cover plate 1. The low-scattering carrier is tightly connected to the edge of the leading edge absorbing structure of the wing without any step difference, and aluminum foil is pasted at the seam between the two to ensure that there are no surface discontinuous echo reflections and strong specular reflection sources at the connection. When verifying the RCS of the low-scattering carrier, the leading edge cover plate 1 and the carrier body are connected to block the cavity of the low-scattering carrier to verify the low scattering property of the low-scattering carrier.

[0042] In a preferred embodiment, the low-scattering carrier has an average vertical polarization scattering RCS of -40 dBsm and an average horizontal polarization scattering RCS of -45 dBsm within an azimuth angle of 0 to 50 degrees in the X-band, providing the aircraft with stronger stealth performance.

[0043] Combination Figure 2-4The length of the radar-absorbing carrier at the leading edge of the wing to be tested is 3500mm. The total length of the carrier must be less than the quiet zone size of the anechoic chamber to ensure the stability and accuracy of the test environment. The wavelength corresponding to the center frequency is 32mm. The width of the carrier body must be greater than or equal to 3.2 times the wavelength corresponding to the lowest test frequency. This ensures that the carrier's width dimension is within the optical zone of electromagnetic scattering, avoiding the problem of the RCS oscillating violently with frequency changes due to the carrier being too small and thus in the resonant zone, and the insignificant effect of shape stealth measures on RCS reduction. The angle between the carrier body 2 and the carrier end face 3 is greater than or equal to 65° to reduce scattering and improve stealth performance.

[0044] To verify the accuracy of the RCS scattering of the carrier's leading-edge absorbing structure after detachment from the aircraft structure, a carrier with L = 4300 mm, W1 = 800 mm, and H = 200 mm was selected for testing. The carrier is a hollow metal structure, with its leading edge 4 and trailing edge 5 parallel, and the angle between its main body 2 and end face 3 equal to 65°. Aluminum foil is attached to the seam 6 of the carrier. The following tests were conducted. The specific test method is as follows:

[0045] Step 1: Conduct a darkroom background test;

[0046] Step 2: Select and install the horn antenna based on the signal band of the RCS test;

[0047] Step 3: Set the polarization mode;

[0048] Step 4: Install the front edge cover plate onto the carrier body and cover the seam between the front edge cover plate and the carrier body with aluminum foil;

[0049] Step 5: Place the low-scattering carrier on the turntable of the RCS test, with the length direction of the low-scattering carrier parallel to the 0° direction of the incident electromagnetic wave.

[0050] Step 6: Perform RCS tests on the all-metal low-scattering carrier and record the test data values;

[0051] Step 7: Remove the leading edge cover plate of the low-scattering carrier, install the leading edge absorbing structure of the wing front edge onto the carrier body, and cover the seam between the leading edge absorbing structure of the wing front edge and the carrier body with aluminum foil;

[0052] Step 8: Place the low-scattering carrier with the wing front edge absorbing structure installed on the turntable, with its length direction parallel to the 0° direction of the incident electromagnetic wave;

[0053] Step 9: Conduct RCS tests on the low-scattering carrier after installing the wing leading edge absorbing structure, and record the test data values;

[0054] Step 10: Compare the test data results from Step 6 and Step 9 to obtain the reduction in the leading-edge peak value of the metal of the low-scattering carrier by the wing leading-edge absorbing structure.

[0055] Step 11: Repeat steps 3-10 to complete the RCS test for all polarization modes at one frequency;

[0056] Step 12: Repeat steps 2-11 to complete the RCS test at all frequencies.

[0057] Figure 5 RCS simulation curves were generated for the carrier within the aforementioned value range, calculated using the multilayer fast multipole algorithm. Here, VV represents the simulation test curve for vertical polarization, and HH represents the simulation test curve for horizontal polarization. As shown in the figure, except for a peak value close to -20 dBsm at 26°, the RCS is below -30 dBsm at most azimuth angles under horizontal polarization HH, with an average value reaching -40 dBsm. Under vertical polarization VV, the RCS is below -40 dBsm at most azimuth angles, with an average value reaching -45 dBsm. The carrier's stealth design results in a low scattering level.

[0058] The low-scattering carrier described in this invention adopts a teardrop-shaped design with a structure in which the leading and trailing edges of the wing are parallel, which greatly reduces the vertical and horizontal polarization electromagnetic scattering characteristics of the carrier. Compared with the teardrop-shaped low-scattering carrier in 202210230306.0, it has been greatly optimized and modified, and the reduction in X-band can reach 15dBsm, providing the aircraft with stronger stealth performance.

[0059] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A low-scattering carrier for RCS testing of a wing leading-edge absorbing structure, characterized in that: The low-scattering carrier includes a front edge cover plate (1), a carrier body (2) and a carrier end face (3). The front edge cover plate (1) and the carrier body (2) are detachably connected. The carrier body (2) is a flat elongated structure that is thick in the middle and gradually flattens at the front and rear sides. The front and rear ends of the carrier body (2) are teardrop shapes with one thick and one thin. The carrier end face (3) is configured as two, one thick and one thin, respectively corresponding to the two ends of the flat elongated structure of the carrier body (2); the two side lines of the carrier end face (3) are parallel; the carrier end face (3) and the carrier body (2) are integrally formed metal hollow structures; the included angle between the carrier end face (3) and the carrier body (2) is greater than or equal to 65°. The leading edge (4) of the carrier body (2) is a straight structure that fits into the wave-absorbing structure at the leading edge of the wing. The curved surfaces at the connection between the leading edge cover plate (1) and the carrier body (2) are tangent and continuous without surface step difference. The trailing edge (5) of the carrier body (2) is a straight structure that is parallel to the leading edge (4).

2. The low-scattering carrier for RCS testing of the wing leading edge absorbing structure according to claim 1, characterized in that: The front edge cover plate (1) is a cover plate structure that fits against one side of the front edge (4) of the carrier body (2) and is detachably set on one side of the front edge of the carrier body.

3. The low-scattering carrier for RCS testing of the wing leading edge absorbing structure according to claim 1, characterized in that: The carrier end face (3) is a flat cover plate structure where the upper and lower curved surfaces shrink into a curve.

4. The low-scattering carrier for RCS testing of the wing leading edge absorbing structure according to claim 1, characterized in that: The width of the carrier body (2) is greater than or equal to 3.2 times the signal wavelength corresponding to the lowest frequency tested during RCS testing.

5. The low-scattering carrier for RCS testing of the wing leading edge absorbing structure according to claim 1, characterized in that: The carrier has no surface step difference and its surface roughness is no greater than 1.

6.

6. The low-scattering carrier for RCS testing of the wing leading edge absorbing structure according to claim 1, characterized in that: The length of the low-scattering carrier is 4300 mm. The width of the low-scattering carrier is 800 mm. The height of the low-scattering carrier is 200 mm.

7. The low-scattering carrier for RCS testing of the wing leading edge absorbing structure according to claim 1, characterized in that: When testing the wing surface absorbing structure, the leading edge cover plate (1) is removed and the wing front edge absorbing structure is installed; when verifying the RCS of the low-scattering carrier, the leading edge cover plate (1) is used to shield the cavity of the low-scattering carrier.

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