Low-scattering carrier structure suitable for aircraft exhaust system and use method of low-scattering carrier structure

Abstract

The invention belongs to the technical field of electromagnetic scattering characteristic measurement, and relates to a low-scattering carrier structure suitable for an aircraft exhaust system and a use method thereof. Comprising a carrier body, the carrier body comprises a pinnacle structure and an ending structure, and the pinnacle structure is smoothly connected with the ending structure; the pinnacle structure comprises a triangular panel arranged on the upper surface of the carrier main body and a semi-conical curved panel arranged on the lower surface of the carrier main body, a cavity structure is arranged in the pinnacle structure, and the ending structure comprises a special-shaped bent surface, a special-shaped curved surface and an ending end surface, so that edge scattering, mirror scattering and traveling wave diffraction of an outer structure of an air passage of the exhaust system can be effectively eliminated; and the state during actual installation can be simulated.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic scattering characteristic measurement, and relates to a low-scattering carrier structure suitable for an aircraft exhaust system and a method of using the same. Background Art

[0002] Radar cross section (RCS) is gaining more and more attention in the field of aircraft design. The exhaust system of an aircraft is an important part of the aircraft propulsion system, and its performance will directly affect the performance and reliability of the engine. The exhaust system of an aircraft is a typical cavity structure and a strong scattering source for the aircraft. In order to significantly reduce the RCS of a conventional aircraft, it is necessary to carefully design its structure and take special technical measures while taking into account the aerodynamics and stealth of the aircraft's intake and exhaust systems.

[0003] According to the current analysis of stealth technology for aircraft exhaust systems, there are roughly two technical routes: 1. Processing inside the exhaust system, specifically: coating the exhaust system with an absorbing coating, applying an absorbing structure, or making the entire air intake duct with absorbing materials to absorb the electromagnetic waves reflected inside the cavity; 2. Processing at the exhaust system outlet, specifically adding a grille at the opening of the exhaust system to achieve electromagnetic shielding and reflect electromagnetic waves to the radar low threat position. When the aircraft exhaust system is separated from the aircraft body, the outer structure of the airway that was originally blocked by the aircraft body will be exposed to electromagnetic waves, resulting in additional irrelevant scattering that is different from its contribution to the scattering of the entire platform in the actual installation state.

[0004] Therefore, it is necessary to design a low-scattering carrier for the aircraft exhaust system to eliminate irrelevant scattering. The scattering level of the low-scattering carrier should be 1 to 2 orders of magnitude lower than that of the target being measured. Aircraft exhaust system components with different design schemes are loaded on the low-scattering carrier for calculation, which can accurately reflect the RCS of the aircraft exhaust system. The low-scattering carrier involved in the current related technology is suitable for leading edge, trailing edge and other parts, but it is difficult to use it for exhaust system RCS analysis. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and to provide a low-scattering carrier structure suitable for an aircraft exhaust system and a method of using the same.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A low-scattering carrier structure for an aircraft exhaust system comprises a carrier body, wherein the carrier body comprises a peak structure and a tail structure, wherein the peak structure is smoothly connected to the tail structure;

[0008] The pointed top structure includes a triangular panel arranged on the upper surface of the carrier body and a semi-conical curved panel arranged on the lower surface of the carrier body, a cavity structure is arranged in the pointed top structure, an opening of the cavity structure is arranged on the triangular panel, a cavity cover plate is arranged at the opening, and the cavity cover plate is detachably connected to the triangular panel;

[0009] The finishing structure includes a special-shaped bending surface, a special-shaped curved surface and a finishing end surface.

[0010] Furthermore, the tip of the pointed structure is defined as the triangular vertex of the triangular panel, the curved vertex of the semi-conical curved panel and the triangular vertex are the same vertex, the first side of the triangular panel is smoothly connected to the first side of the semi-conical curved panel, and the second side of the triangular panel is smoothly connected to the second side of the semi-conical curved panel.

[0011] Furthermore, in horizontal projection, the angle at the top is θ It is 48°~52°.

[0012] Further, the special-shaped bending surface includes a first arcuate surface and a first bending transition surface with smooth transition, and the first arcuate surface and the first bending transition surface have smooth transition; the special-shaped curved surface includes a second arcuate surface and a second bending transition surface connected to each other, and the second arcuate surface and the second bending transition surface have smooth transition; the first arcuate edge of the first arcuate surface is connected to the second arcuate edge of the second bending transition surface, and the third arcuate edge of the first bending transition surface is connected to the fourth arcuate edge of the second arcuate surface; the tail end surface is an irregular circular surface, the tail end surface is located at the bottom of the tail structure, and the tail end surface smoothly transitions with the special-shaped bending surface and the special-shaped curved surface;

[0013] The first arc surface is smoothly connected to the triangular panel, and the fourth arc edge of the first bending transition surface, the fifth arc edge of the second bending transition surface, and the sixth arc edge of the second arc surface are all connected to the bottom edge of the semi-conical curved panel.

[0014] Furthermore, the cavity cover plate and the arc-shaped triangular panel form a smooth arc surface.

[0015] Furthermore, the roughness of the triangular panel, the semi-conical curved panel, and the finishing structure are all less than or equal to 1.6.

[0016] Furthermore, the length of the carrier body is greater than twice the length of the exhaust system, the width of the carrier body is greater than twice the width of the exhaust system, and the height of the carrier body is greater than twice the height in the installation posture.

[0017] Furthermore, the surfaces of the triangular panel, the semi-conical curved panel and the finishing structure are coated with a radar absorbing coating.

[0018] Furthermore, the present invention also provides a method for using a low-scattering carrier structure, specifically:

[0019] Place the cavity cover plate on the opening, evaluate the carrier RCS level by measuring the RCS of the carrier body, and determine whether the carrier is at a low scattering level;

[0020] The cavity cover is removed, and the RCS of the cavity structure is measured when an absorbing coating is applied to the exhaust system and a grille is added at the opening of the exhaust system to verify the RCS reduction effect, thereby achieving an accurate evaluation of the RCS of the target components of the exhaust system structure.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the cavity structure in the present invention can be adapted to the exhaust system and can be used for RCS testing of the exhaust system; the carrier body composed of a semi-conical curved panel, a triangular panel and a tail structure can effectively eliminate edge scattering, mirror scattering and traveling wave diffraction of the outer structure of the exhaust system airway, and can simulate the actual state during installation; at the same time, the carrier itself is at a lower scattering level due to the adoption of stealth design measures, and can achieve accurate evaluation of the RCS of target components of the exhaust system structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 It is a schematic diagram of the finishing structure of the low scattering carrier in the present invention;

[0025] Figure 2 It is a schematic diagram of the overall structure of the low scattering carrier in the present invention;

[0026] Figure 3 It is a schematic diagram of the cavity cover structure of the low scattering carrier in the present invention;

[0027] Figure 4 is a schematic diagram of the width of the low scattering carrier in the present invention;

[0028] Figure 5 It is a schematic diagram of the height and length of the low scattering carrier in the present invention;

[0029] Figure 6 is an RCS characteristic curve diagram of the low scattering carrier in the present invention at P-band HH polarization;

[0030] Figure 7 It is the RCS characteristic curve diagram of the low scattering carrier in the present invention at the P band VV polarization;

[0031] Figure 8 is a graph showing the RCS characteristic curve of the low scattering carrier in the present invention at L-band HH polarization;

[0032] Fig. 9 It is the RCS characteristic curve diagram of the low scattering carrier in the present invention at L-band VV polarization.

[0033] Among them: 1 is a semi-conical curved panel; 2 is a triangular panel; 3 is a finishing structure; 3.1 is a special-shaped bending surface; 3.11 is a first arc surface; 3.2 is a special-shaped curved surface; 3.22 is a second arc surface; 3.3 is a finishing end surface; 4 is a cavity structure; 5 is a cavity cover plate. DETAILED DESCRIPTION

[0034] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples of devices consistent with some aspects of the present invention as detailed in the appended claims.

[0035] Example

[0036] A low-scattering carrier structure for an aircraft exhaust system, comprising a carrier body, wherein the carrier body comprises a peak structure and a tail structure 3, wherein the peak structure is smoothly connected to the tail structure 3;

[0037] The pointed top structure includes a triangular panel 2 arranged on the upper surface of the carrier body and a semi-conical curved panel 1 arranged on the lower surface of the carrier body, a cavity structure 4 is arranged in the pointed top structure, an opening of the cavity structure 4 is arranged on the triangular panel 2, a cavity cover plate 5 is arranged at the opening, and the cavity cover plate 5 is detachably connected to the triangular panel 2;

[0038] The end structure 3 comprises a special-shaped bending surface 3.1, a special-shaped curved surface 3.2 and an end surface 3.3.

[0039] like Figures 1 to 5As shown, an embodiment of the present invention provides a low-scattering carrier that can be used in an aircraft exhaust system, comprising a semi-conical curved panel 1, a triangular panel 2, a tail structure 3; a cavity structure 4; a cavity cover 5; the overall shape of the low-scattering carrier is similar to an almond shape, and the approximate geometric structure of the low-scattering carrier is divided into three areas: front, middle and rear, based on the assessment angle region, the front part is a pointed roof structure, the rear part adopts a tail structure, the pointed roof structure is smoothly connected to the tail structure 3, the middle area of ​​the low-scattering carrier has a cavity structure 4 reserved according to the shape of the exhaust system, the outer side of the cavity structure 4 is provided with a carrier cover 5, and the contour of the carrier cover 5 is consistent with the geometric contour of the end of the cavity structure 4.

[0040] The carrier body has a flat triangular panel 2 and an outwardly protruding semi-conical curved panel 1, which are combined with a finishing structure 3. The semi-conical curved panel 1, the triangular panel 2 and the finishing structure 3 have a smooth and continuous transition, and the cavity structure 4 in the middle area of ​​the triangular panel 2 is adapted to the shape of the exhaust system.

[0041] The carrier cover plate 5 has a smooth transition with the upper surface of the carrier body. When the cavity structure 4 is loaded with the carrier cover plate 5, it can be used to evaluate the carrier performance; when it is removed, the RCS of the exhaust system structure target component can be accurately evaluated.

[0042] Furthermore, the tip of the pointed structure is defined as the triangular vertex of the triangular panel 2, the curved surface vertex of the semi-conical curved panel 1 and the triangular vertex are the same vertex, the first side edge of the triangular panel 2 is smoothly connected to the first side edge of the semi-conical curved panel 1, and the second side edge of the triangular panel 2 is smoothly connected to the second side edge of the semi-conical curved panel 1.

[0043] Furthermore, in horizontal projection, the angle at the top is θ It is 48° to 52°. Preferably, the front end included angle θ of the horizontal projection of the low scattering carrier is 50°, and the front end vertex angle of the horizontal projection is θ.

[0044] Furthermore, the special-shaped bending surface 3.1 includes a first arcuate surface 3.11 and a first bending transition surface 3.12 with smooth transition, and the first arcuate surface 3.11 and the first bending transition surface 3.12 have smooth transition; the special-shaped curved surface 3.2 includes a second arcuate surface 3.22 and a second bending transition surface 3.21 connected to each other, and the second arcuate surface 3.22 and the second bending transition surface 3.21 have smooth transition; the first arcuate edge of the first arcuate surface 3.11 is connected to the second arcuate edge of the second bending transition surface 3.21, and the third arcuate edge of the first bending transition surface 3.12 is connected to the fourth arcuate edge of the second arcuate surface 3.22; the tail end surface 3.3 is an irregular circular surface, and the tail end surface 3.3 is located at the bottom of the tail structure 3, and the tail end surface 3.3 smoothly transitions with the special-shaped bending surface 3.1 and the special-shaped curved surface 3.2;

[0045] The first curved surface 3.11 is smoothly connected to the triangular panel 2, and the fourth curved edge of the first bending transition surface 3.12, the fifth curved edge of the second bending transition surface 3.21, and the sixth curved edge of the second curved surface 3.22 are all connected to the bottom edge of the semi-conical curved panel 1. The second curved surface 3.22 is shaped like a half petal.

[0046] Furthermore, the cavity cover plate 5 and the arc-shaped triangular panel 2 form a smooth arc surface.

[0047] Furthermore, the roughness of the triangular panel 2, the semi-conical curved panel 1, and the finishing structure 3 are all less than or equal to 1.6, and the entire carrier surface is a smooth curved surface with a roughness of ≤1.6.

[0048] Furthermore, the length of the carrier body is greater than 2 times the length of the exhaust system, the width of the carrier body is greater than 2 times the width of the exhaust system, and the height of the carrier body is greater than 2 times the height in the installation posture. The length of the carrier body is L, the width is W, and the height is H.

[0049] In order to ensure that the device is at a low scattering level, a high roughness surface will introduce defect scattering on the surface, a front angle that is too large will cause abnormal peaks in the device's inspection angle area, and a device size that is too small will result in an unsmooth appearance. The above three points will lead to an increase in the RCS of the device, resulting in device failure. Therefore, the parameter settings are as follows:

[0050] The carrier plate 1, plate 2 and plate 3 are all smooth curved surfaces with a roughness of ≤1.6.

[0051] The angle θ of the front end of the horizontal projection of the carrier is preferably 50°.

[0052] The carrier has a length greater than twice the length of the exhaust system, a width greater than approximately twice the width of the exhaust system, and a height greater than approximately twice the height of the exhaust system in an installed posture.

[0053] Furthermore, the surfaces of the triangular panel 2, the semi-conical curved panel 1 and the finishing structure 3 are coated with a radar absorbing coating. The overall material of the low-scattering carrier is metal, and the radar absorbing coating is coated on the metal surface.

[0054] In addition, this solution also provides a method for using a low-scattering carrier structure, specifically:

[0055] Place the cavity cover plate 5 on the opening, evaluate the RCS level of the carrier by measuring the RCS of the carrier body, and judge whether the carrier is at a low scattering level. If the carrier is at a low scattering level, it proves that the carrier body can meet the RCS evaluation requirements of the exhaust system structure target component;

[0056] The cavity cover plate 5 is removed, and the RCS of the cavity structure 4 is measured when an absorbing coating is applied to the exhaust system and a grille is added at the opening position of the exhaust system, respectively, to verify the RCS reduction effect, thereby achieving an accurate evaluation of the RCS of the target components of the exhaust system structure.

[0057] Under the condition of loading the carrier cover, the RCS characteristic curves of the low-scattering carrier in the P and L bands, typical elevation, azimuth and different polarization conditions are as follows: Figures 6 to 9 As shown, the average RCS of P and L bands is less than -35dBsm;

[0058] As shown in Table 1, the low-scattering carrier is at a lower scattering level, which enables accurate evaluation of the RCS of exhaust system structural target components.

[0059] Table 1 Mean statistics of examples

[0060]

[0061] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0062] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A low scattering carrier structure for an aircraft exhaust system, characterized in that: The carrier body comprises a tip structure and a tail structure (3), wherein the tip structure is smoothly connected to the tail structure (3); The pointed roof structure comprises a triangular panel (2) arranged on the upper surface of the carrier body and a semi-conical curved panel (1) arranged on the lower surface of the carrier body, a cavity structure (4) is arranged in the pointed roof structure, an opening of the cavity structure (4) is arranged on the triangular panel (2), a cavity cover plate (5) is arranged at the opening, and the cavity cover plate (5) is detachably connected to the triangular panel (2); The finishing structure (3) comprises a special-shaped bending surface (3.1), a special-shaped curved surface (3.2) and a finishing end surface (3.3).

2. A low scattering carrier structure for an aircraft exhaust system according to claim 1, characterized in that: The tip of the pointed top structure is defined as the triangular vertex of the triangular panel (2), the curved surface vertex of the semi-conical curved panel (1) and the triangular vertex are the same vertex, the first side edge of the triangular panel (2) is smoothly connected to the first side edge of the semi-conical curved panel (1), and the second side edge of the triangular panel (2) is smoothly connected to the second side edge of the semi-conical curved panel (1).

3. A low scattering carrier structure for an aircraft exhaust system according to claim 2, characterized in that: In horizontal projection, the angle θ at the pinnacle is 48° to 52°.

4. The low scattering carrier structure for an aircraft exhaust system according to claim 1, characterized in that: The special-shaped bending surface (3.1) comprises a first arcuate surface (3.11) and a first bending transition surface (3.12) with smooth transition, and the first arcuate surface (3.11) and the first bending transition surface (3.12) have smooth transition; the special-shaped curved surface (3.2) comprises a second arcuate surface (3.22) and a second bending transition surface (3.21) connected to each other, and the second arcuate surface (3.22) and the second bending transition surface (3.21) have smooth transition; the first arcuate surface (3.11) and the first bending transition surface (3.12) have smooth transition. The first arcuate edge of the surface (3.11) is connected to the second arcuate edge of the second bending transition surface (3.21), and the third arcuate edge of the first bending transition surface (3.12) is connected to the fourth arcuate edge of the second arcuate surface (3.22); the tail end surface (3.3) is an irregular circular surface, the tail end surface (3.3) is located at the bottom of the tail structure (3), and the tail end surface (3.3) smoothly transitions with the special-shaped bending surface (3.1) and the special-shaped curved surface (3.2); The first arcuate surface (3.11) is smoothly connected to the triangular panel (2), and the fourth arcuate edge of the first bent transition surface (3.12), the fifth arcuate edge of the second bent transition surface (3.21), and the sixth arcuate edge of the second arcuate surface (3.22) are all connected to the bottom edge of the semi-conical curved panel (1).

5. The low scattering carrier structure for an aircraft exhaust system according to claim 1, characterized in that: The cavity cover plate (5) and the arc-shaped triangular panel (2) form a smooth arc surface.

6. The low scattering carrier structure for an aircraft exhaust system according to claim 1, characterized in that: The roughness of the triangular panel (2), the semi-conical curved panel (1) and the finishing structure (3) are all less than or equal to 1.

6.

7. The low scattering carrier structure for an aircraft exhaust system according to claim 1, characterized in that: The length of the carrier body is greater than twice the length of the exhaust system, the width of the carrier body is greater than twice the width of the exhaust system, and the height of the carrier body is greater than twice the height of the exhaust system in an installed posture.

8. The low scattering carrier structure for an aircraft exhaust system according to claim 1, characterized in that: The surfaces of the triangular panel (2), the semi-conical curved panel (1) and the finishing structure (3) are coated with a radar absorbing coating.

9. A method for using a low-scattering carrier structure as claimed in claims 1 to 8, characterized in that: Specifically: The cavity cover plate (5) is placed on the opening, and the RCS level of the carrier is evaluated by measuring the RCS of the carrier body to determine whether the carrier is at a low scattering level. The cavity cover plate (5) is removed, and the RCS of the cavity structure (4) is measured when an absorbing coating is applied to the exhaust system and a grille is added at the opening position of the exhaust system, respectively, to verify the RCS reduction effect, thereby achieving an accurate evaluation of the RCS of the target components of the exhaust system structure.

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