Design method, system and storage medium for reducing the rearward rcs of an aeroengine

Abstract

The application discloses a design method, system and medium for reducing the rearward radar scattering cross section of an aero-engine. The method comprises the following steps: modeling the rearward part of the engine; calculating electromagnetic scattering characteristics and identifying strong scattering sources; setting an RCS target value and an optimization strategy; performing structural optimization of part tilting / shading and edge serration modification; applying medium coating or functional composite stealth material; establishing a multidisciplinary optimization model, comprehensively balancing stealth performance and indicators such as aerodynamic, thermal efficiency and weight, and solving an optimal scheme and evaluating through a collaborative optimization algorithm. The application systematically integrates structural stealth and material stealth technologies, and guarantees the comprehensive performance of the engine through multidisciplinary optimization. Compared with the prior art, the application can significantly reduce the rearward RCS of the engine, and provides an efficient and systematic technical process for aero-engine stealth design, and has important engineering application value.

Description

Technical Field

[0001] This invention relates to the field of aero-engine design, and specifically to a design method and system for reducing the rear radar cross section (RCS) of an aero-engine. Background Technology

[0002] Radar cross section (RCS) is a physical quantity that measures the intensity of radar wave scattering by a target, and its value directly determines the probability of an aircraft being detected by radar. As an important component of the rear fuselage of an aircraft, the complex internal structure of the aero engine (such as nozzles, internal cones, stabilizers, etc.) constitutes a strong source of electromagnetic wave scattering, making the rear region of the engine a prominent weakness in the overall stealth performance of the aircraft.

[0003] Currently, research on improving the rearward radar stealth performance of aero-engines largely focuses on exploring single technical measures, such as applying radar-absorbing coatings or modifying local structures. These methods lack systematic design guidance and holistic optimization strategies, often failing to simultaneously reduce RCS while considering core performance indicators such as inherent aerodynamic performance, thermal efficiency, and structural weight. Existing technologies lack a complete, efficient design methodology capable of comprehensively balancing the performance requirements of multiple disciplines, resulting in long and costly stealth design cycles for aero-engines, with the final results failing to meet the stringent requirements of highly stealthy aircraft. Therefore, there is an urgent need to develop an efficient design methodology that can systematically reduce the rearward RCS of aero-engines while comprehensively considering the impact of various engine performance indicators. Summary of the Invention

[0004] The main objective of this invention is to propose a design method, system, and storage medium for reducing the rear radar cross section (RCS) of an aero-engine. This aims to address the technical problems in existing technologies that lack a systematic approach and cannot comprehensively balance stealth performance with other key engine performance indicators. The method of this invention can significantly reduce the engine's rear RCS, improve the overall stealth capability of the aircraft, and ensure that the engine's aerodynamic, thermal efficiency, and weight performance are not negatively affected.

[0005] To achieve the above objectives, the present invention proposes the following technical solution: In a first aspect, the present invention proposes a design method for reducing the rear radar cross-section of an aero-engine, comprising the following steps: S1. Analysis and Modeling of Rearward Components of Engines: Analyze the rearward components of aero-engines, identify key components that affect rearward radar stealth performance, and establish a three-dimensional model containing the key components. S2. Electromagnetic scattering characteristic calculation: Perform electromagnetic scattering characteristic calculation on the three-dimensional model to obtain the distribution of the radar cross section behind the engine, and identify strong backscattering sources through the radar cross section imaging map; S3. Target value setting: Based on the overall stealth requirements of the aircraft, set the target value of the engine's rear radar cross section, and combine the results of the electromagnetic scattering characteristics calculation to formulate optimization strategies for key improvement parts and their expected radar cross section reduction. S4. Structural optimization design: Based on the optimization strategy, the key components are structurally optimized, and the structural optimization design includes at least one of component tilting, occlusion design and edge jaggedness shaping design. S5. Application of stealth materials: Applying stealth materials to the exterior of the components of the backscattering source, wherein the stealth materials include at least one of dielectric coating materials and functional composite materials; S6. Multidisciplinary optimization and comprehensive evaluation: Establish a multidisciplinary optimization model that comprehensively considers radar stealth performance and other engine performance indicators, use a collaborative optimization algorithm to solve the model, obtain the optimal design scheme that meets all performance requirements, and conduct a comprehensive evaluation of the optimal design scheme.

[0006] Preferably, the key components mentioned in step S1 include the nozzle, the inner cone, and the stabilizer; the three-dimensional model is established using computer-aided design software, and the three-dimensional model includes the external dimensions, internal structure, and material property information of each component.

[0007] Preferably, the electromagnetic scattering characteristic calculation in step S2 specifically includes: importing the three-dimensional model into electromagnetic simulation software, setting different frequency ranges, incident angles and polarization modes to simulate the interaction between electromagnetic waves and the engine's rearward components; the radar cross-section imaging map includes one-dimensional, two-dimensional or three-dimensional synthetic aperture radar or inverse synthetic aperture radar imaging maps, used to identify components with high radar cross-section peak values ​​as strong scattering sources.

[0008] Preferably, the target value in step S3 is that the engine's rearward average radar cross section does not exceed -10 dBsm; the expected radar cross section reduction is 5-10 dBsm; and the key improvement areas include the inner cone, stabilizer, and nozzle expansion section.

[0009] Preferably, the component tilting and shielding design in step S4 includes: designing the rearward component of the engine to be tilted at a predetermined angle relative to the engine axis, so that the incident electromagnetic wave is deviated from the key angle region of radar reception after reflection; the predetermined angle is 10 degrees.

[0010] Preferably, the edge serrated shaping design in step S4 includes: using a serrated edge design on the nozzle adjustment plate and fairing to disrupt the specular reflection of electromagnetic waves; the parameters of the serrated edge include: a serrated height of 10 mm, a serrated width of 15 mm, and a serrated angle of 45°.

[0011] Preferably, the dielectric coating material in step S5 is a dielectric absorbing coating or a periodic structure absorbing coating; the type, thickness and coating process of the dielectric coating material are selected according to the working environment and performance requirements of the component; for parts or components that cannot be coated, the functional composite material is used as a substitute or manufactured; the stealth material is applied to the outer surface of the inner cone and the stabilizer, and the dielectric coating material has wave absorption properties in the X-band and Ku-band.

[0012] Preferably, the other engine performance indicators mentioned in step S6 include aerodynamic performance, thermal efficiency, and weight; the collaborative optimization algorithm is a multi-objective genetic algorithm or a sequential quadratic programming method; the comprehensive evaluation includes stealth performance testing, aerodynamic performance testing, and thermal management analysis.

[0013] Secondly, the present invention proposes a design system for reducing the rear radar cross-section of an aero-engine, used to perform the above-described design method, the system comprising: The modeling module is used to create 3D models of the engine's rearward components; An electromagnetic calculation module is used to calculate the electromagnetic scattering characteristics of the three-dimensional model and identify strong scattering sources; The target setting module is used to set the target value of the radar cross section and formulate optimization strategies; The structural optimization module is used to perform structural optimization design for component tilting, occlusion, and edge jaggedness correction; The materials application module is used for selecting and applying stealth materials; The multidisciplinary optimization module is used to establish and solve optimization models that comprehensively consider stealth performance and other performance indicators, and to conduct comprehensive evaluation.

[0014] Thirdly, the present invention proposes a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described design method for reducing the rear radar cross section of an aero-engine.

[0015] Compared with existing technologies, the design method for reducing the rear radar cross section of aero engines provided by this invention has the following beneficial technical effects: (1) By systematically integrating structural optimization and the application of stealth materials, the rearward RCS of the aero-engine is significantly reduced, which effectively improves the overall stealth performance of the aircraft. In particular, the RCS of strong scattering sources such as nozzles, inner cones, and stabilizers can be reduced by 5-10 dBsm.

[0016] (2) This invention does not simply pursue the ultimate stealth effect, but rather balances stealth performance with core engine indicators such as aerodynamic performance, thermal efficiency, and weight within the same optimization framework through multidisciplinary optimization and comprehensive evaluation steps. This enables the final design to improve stealth capabilities without sacrificing or sacrificing as little as possible other key engine performance, thus ensuring engine reliability and overall efficiency.

[0017] (3) This invention proposes a complete, closed-loop design process from component analysis, characteristic calculation, target setting, structural optimization, material selection to multidisciplinary evaluation. This process can form a standardized design guide, providing clear theoretical guidance and technical support for the stealth design of aero engines, avoiding the blindness of traditional trial and error methods, significantly shortening the R&D cycle, and reducing design costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 The flowchart illustrates the design method for reducing the rear radar cross section of an aero-engine provided by this invention.

[0020] Figure 2 This is a schematic diagram of the rearward structure of the engine in an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of nozzle tilting and edge shaping in an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of applying a stealth coating to the rearward component of the engine in an embodiment of the present invention. The dashed area (the surface of the inner cone 1) in the figure represents the area where the stealth coating is applied.

[0023] Explanation of the reference numerals: 1-Inner cone, 2-Stabilizer, 3-Nozzle; α represents the nozzle upturn angle, β represents the nozzle adjusting blade serration trimming angle. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, all other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0025] Combination Figures 1 to 4 As shown, this embodiment provides a design method, system, and storage medium for reducing the rearward RCS of an aero-engine, as detailed below: In a first aspect, this embodiment provides a design method for reducing the rear radar cross-section of an aero-engine, including the following steps: I. Analysis and Model Establishment of Rearward Components of the Engine First, a system analysis of the rearward components of the target engine is performed. In this embodiment, the key components that contribute the most to the rearward RCS are identified as: the inner cone 1, the stabilizer 2, and the nozzle 3, such as... Figure 2 As shown.

[0026] Using 3D CAD software (such as Siemens NX or Dassault Systèmes CATIA), a precise 3D model containing the aforementioned key components was created based on the engine's design drawings and digital models. This model not only accurately describes the geometry and assembly relationships of each component but also assigns material properties, such as the dielectric constant and conductivity of high-temperature alloys. During model creation, detailed structures that might cause cavity scattering and multiple reflections (such as the recirculation zone behind the stabilizer and the gaps between nozzle adjustment vanes) were refined to ensure the accuracy of subsequent electromagnetic calculations.

[0027] II. Calculation of Electromagnetic Scattering Characteristics Export the completed 3D model to a suitable format (such as .stp or .sat) and import it into the professional electromagnetic simulation software, CST Microwave Studio Suite.

[0028] The calculation settings are as follows: Frequency range: The focus is on the X-band (8-12GHz) and Ku-band (12-18GHz), which are the operating frequency bands of most fire control radars.

[0029] Incident angle: The azimuth angle is set to 180°±45° (positive for rearward), and the pitch angle is set to -15° to +15°, covering the main threat angle domain behind the aircraft.

[0030] Polarization method: Horizontal polarization (HH) and vertical polarization (VV) are calculated simultaneously, and the average of the two is taken as the final RCS result.

[0031] Solver: A combination of the bouncing ray method (SBR) or the multilevel fast multipole method (MLFMM) is used to balance the solution efficiency and accuracy of electrically large models.

[0032] After the simulation calculation is completed, the average RCS value of the engine's rearward direction is extracted as the baseline value (in this embodiment, the baseline value is +5 dBsm). Simultaneously, an RCS hotspot imaging map is generated, including a one-dimensional range image and a two-dimensional SAR / ISAR image. By analyzing these images, the specific physical location of the RCS peak can be intuitively determined. The calculation results of this embodiment show that under the conditions of a frequency of 10 GHz and rearward incidence (azimuth angle 180°, elevation angle 0°), extremely high RCS peaks exist at the leading edge of the stabilizer 2 and the top of the inner cone 1 inside the nozzle, which are the main sources of strong rearward scattering. Furthermore, the trailing edge of the nozzle trim vanes also contributes significantly to edge diffraction.

[0033] III. Target Value Setting and Optimization Strategy Formulation Based on the overall stealth performance requirements of the aircraft equipped with this type of engine (the average rearward RCS of the entire aircraft must be less than -5dBsm), and combined with the scattering budget of the engine nacelle itself, the target value of the average rearward RCS of the engine is set to not exceed -10dBsm.

[0034] Based on the calculation results of step two, the following optimization strategy is formulated: Key areas for optimization: Inner cone 1, stabilizer 2, and the expansion section adjustment plate of nozzle 3.

[0035] Expected RCS reduction: For the two strong scattering sources, the inner cone and stabilizer, the goal is to reduce their contributed RCS by 5-10 dBsm through structural modification and material loading. For the trailing edge of the nozzle control plate, serrated modification is expected to reduce its edge diffraction contribution by approximately 3-5 dBsm.

[0036] Technical approach: The inner cone and stabilizer adopt a comprehensive solution of "shape modification + absorbing coating"; the nozzle adjustment plate adopts a solution of "tilting design + serrated modification".

[0037] IV. Structural Optimization Design Based on the above optimization strategy, perform specific structural optimization design: 1. Component tilt design: The nozzle 3 at the rear of the engine is designed to be tilted upwards by 10° relative to the engine axis (i.e., Figure 3(The α angle is 10°). This upward-curving design causes the incident radar waves to be reflected by the inner wall of the nozzle expansion section, with the energy mainly deflected upwards and to the upper sides, rather than returning directly along the incident direction, thus significantly reducing the echo intensity in the rearward ±15° key angular region. At the same time, the support structure of the inner cone 1 was also angularly optimized, causing its reflecting surface to deviate from the rearward direction.

[0038] 2. Edge serration shaping: The trailing edge of each adjusting piece of spray 3 is serrated. Specific parameters are: serration height 10mm, serration width 15mm, serration angle 45° (i.e., ... Figure 3 (The β angle in the design is 45°). This design transforms the originally continuous and neat trailing edge diffraction into a series of small scatterers from different directions, whose scattered energy is uniformly "dispersed" in the azimuth direction, thereby reducing the peak RCS at any specific angle.

[0039] V. Application of Stealth Materials To absorb residual scattered energy that cannot be eliminated through structural modification, stealth materials are applied to key components: Applications of dielectric coating materials: Combination Figure 4 As shown, a dual-band (X / Ku) high-performance radar absorbing coating is applied to the outer surfaces of the inner cone 1 and the stabilizer 2. This coating is a dielectric absorbing material with a thickness controlled between 1.5 mm and 2.5 mm and an areal density of less than 4 kg / m³. 2 The coating exhibits an average reflectivity of over -6dB in the 8-18GHz range, effectively attenuating incident wave energy and reducing cavity scattering intensity within the nozzle. Plasma spraying is employed to ensure coating adhesion under high-temperature airflow.

[0040] Application of Functional Composite Materials: Considering that stabilizer 2 operates in the high-temperature environment of the afterburner, some areas cannot be directly coated with organic microwave absorbing coatings. Therefore, some non-load-bearing structural components of the stabilizer are remanufactured using microwave absorbing composite materials. This composite material uses silicon carbide fibers as reinforcement, and by controlling the resistivity of the fibers, it combines structural load-bearing and electromagnetic wave absorption functions. This material can reduce the scattering signal of the stabilizer itself at the source, and its temperature resistance meets the application requirements.

[0041] VI. Multidisciplinary Optimization and Comprehensive Evaluation To verify and ensure the overall performance of the final solution, multidisciplinary optimization and evaluation were conducted.

[0042] 1. Multidisciplinary Optimization: An optimization model was established, with design variables including: nozzle upturn angle α (5°-15°), serration angle β (30°-60°), and absorbing coating thickness (1-3mm). The optimization objective was to minimize the backward average RCS (frequency band 8-12GHz, angular domain ±15°). Constraints included: engine thrust loss no greater than 2%, turbine back-end temperature no increase, and total structural weight gain no more than 15kg. A multi-objective genetic algorithm (NSGA-II) was used for optimization. After 50 iterations, a set of Pareto front solutions was obtained. A compromise solution was selected: α=10°, β=45°, and coating thickness 2.0mm. This solution predicted a backward average RCS of -12.3dBsm, a thrust loss of 1.2%, and a weight gain of 12kg, while satisfying all constraints.

[0043] 2. Comprehensive Evaluation: Conduct a comprehensive performance verification of the above optimal solution: Stealth performance testing: A scaled-down model (1:3 scale) of the rearward engine compartment was manufactured, and RCS testing was conducted in a microwave anechoic chamber. The test results showed good agreement with the simulation predictions. The average RCS within the rearward ±15° angular range was -11.8 dBsm, which is 16.8 dB lower than the baseline value (+5 dBsm), achieving the expected target.

[0044] Aerodynamic performance testing: Full engine or component tests were conducted on an engine bench. Measurement results showed that the aerodynamic losses due to the nozzle upturn and serrated profile were minimal, with an actual thrust loss of 1.5%, which is within the design tolerances.

[0045] Thermal management analysis: The temperature distribution of the inner cone after applying the microwave-absorbing coating was calculated using finite element analysis software. The results show that the coating's excellent thermal insulation performance even slightly reduces the substrate temperature of the inner cone, which is beneficial and harmless to thermal management.

[0046] The comprehensive evaluation results confirm that the engine optimized using the design method of this embodiment exhibits a significant reduction in rearward RCS, while key performance indicators such as aerodynamics, thermodynamics, and weight all meet design requirements. This fully demonstrates the effectiveness, systematicity, and superiority of the method proposed in this invention.

[0047] Secondly, this embodiment provides a design system for reducing the rear radar cross-section of an aero-engine, used to perform the above-described design method, the system comprising: The modeling module is used to create 3D models of the engine's rearward components; An electromagnetic calculation module is used to calculate the electromagnetic scattering characteristics of the three-dimensional model and identify strong scattering sources; The target setting module is used to set the target value of the radar cross section and formulate optimization strategies; The structural optimization module is used to perform structural optimization design for component tilting, occlusion, and edge jaggedness correction; The materials application module is used for selecting and applying stealth materials; The multidisciplinary optimization module is used to establish and solve optimization models that comprehensively consider stealth performance and other performance indicators, and to conduct comprehensive evaluation.

[0048] Thirdly, this embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the above-described design method for reducing the rear radar cross section of an aero-engine.

[0049] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A design method for reducing the rear radar cross-section of an aero-engine, characterized in that, Includes the following steps: S1. Analysis and Modeling of Rearward Components of Engines: Analyze the rearward components of aero-engines, identify key components that affect rearward radar stealth performance, and establish a three-dimensional model containing the key components. S2. Electromagnetic scattering characteristic calculation: Perform electromagnetic scattering characteristic calculation on the three-dimensional model to obtain the distribution of the radar cross section behind the engine, and identify strong backscattering sources through the radar cross section imaging map; S3. Target value setting: Based on the overall stealth requirements of the aircraft, set the target value of the engine's rear radar cross section, and combine the results of the electromagnetic scattering characteristics calculation to formulate optimization strategies for key improvement parts and their expected radar cross section reduction. S4. Structural optimization design: Based on the optimization strategy, the key components are structurally optimized, and the structural optimization design includes at least one of component tilting, occlusion design and edge jaggedness shaping design. S5. Application of stealth materials: Applying stealth materials to the exterior of the components of the backscattering source, wherein the stealth materials include at least one of dielectric coating materials and functional composite materials; S6. Multidisciplinary optimization and comprehensive evaluation: Establish a multidisciplinary optimization model that comprehensively considers radar stealth performance and other engine performance indicators, use a collaborative optimization algorithm to solve the model, obtain the optimal design scheme that meets all performance requirements, and conduct a comprehensive evaluation of the optimal design scheme.

2. The design method for reducing the rear radar cross-section of an aero-engine according to claim 1, characterized in that, The key components mentioned in step S1 include the nozzle, the inner cone, and the stabilizer; the three-dimensional model is established using computer-aided design software, and the three-dimensional model contains the external dimensions, internal structure, and material property information of each component.

3. The design method for reducing the rear radar cross-section of an aero-engine according to claim 1, characterized in that, The electromagnetic scattering characteristic calculation in step S2 specifically includes: importing the three-dimensional model into electromagnetic simulation software, setting different frequency ranges, incident angles and polarization modes to simulate the interaction between electromagnetic waves and the engine's rearward components; the radar cross-section imaging map includes one-dimensional, two-dimensional or three-dimensional synthetic aperture radar or inverse synthetic aperture radar imaging maps, used to identify components with high radar cross-section peak values ​​as strong scattering sources.

4. The design method for reducing the rear radar cross section of an aero-engine according to claim 1, characterized in that, The target value in step S3 is that the engine's rearward average radar cross section does not exceed -10 dBsm; the expected radar cross section reduction is 5-10 dBsm; the key improvement areas include the inner cone, stabilizer, and nozzle expansion section.

5. The design method for reducing the rear radar cross-section of an aero-engine according to claim 1, characterized in that, The component tilting and shielding design in step S4 includes: designing the rearward component of the engine to be tilted at a predetermined angle relative to the engine axis, so that the incident electromagnetic wave is deviated from the key angle region of radar reception after reflection; the predetermined angle is 10 degrees.

6. The design method for reducing the rear radar cross-section of an aero-engine according to claim 1, characterized in that, The edge serrated shaping design in step S4 includes: using a serrated edge design on the nozzle adjustment plate and fairing to disrupt the specular reflection of electromagnetic waves; the parameters of the serrated edge include: a serrated height of 10mm, a serrated width of 15mm, and a serrated angle of 45°.

7. The design method for reducing the rear radar cross-section of an aero-engine according to claim 1, characterized in that, The dielectric coating material mentioned in step S5 is a dielectric absorbing coating or a periodic structure absorbing coating; the type, thickness and coating process of the dielectric coating material are selected according to the working environment and performance requirements of the component; for parts or components that cannot be coated, the functional composite material is used as a substitute or manufactured; the stealth material is applied to the outer surface of the inner cone and the stabilizer, and the dielectric coating material has wave absorption properties in the X-band and Ku-band.

8. The design method for reducing the rear radar cross-section of an aero-engine according to claim 1, characterized in that, The other engine performance indicators mentioned in step S6 include aerodynamic performance, thermal efficiency, and weight; the collaborative optimization algorithm is a multi-objective genetic algorithm or a sequential quadratic programming method; the comprehensive evaluation includes stealth performance testing, aerodynamic performance testing, and thermal management analysis.

9. A design system for reducing the rear radar cross-section of an aero-engine, characterized in that, The system for performing the design method according to any one of claims 1 to 8 includes: The modeling module is used to create 3D models of the engine's rearward components; An electromagnetic calculation module is used to calculate the electromagnetic scattering characteristics of the three-dimensional model and identify strong scattering sources; The target setting module is used to set the target value of the radar cross section and formulate optimization strategies; The structural optimization module is used to perform structural optimization design for component tilting, occlusion, and edge jaggedness correction; The materials application module is used for selecting and applying stealth materials; The multidisciplinary optimization module is used to establish and solve optimization models that comprehensively consider stealth performance and other performance indicators, and to conduct comprehensive evaluation.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the design method for reducing the rear radar cross section of an aero-engine as described in any one of claims 1 to 8.

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