Method for calculating pneumatic optical aberrations
By dividing the external flow field and calculating the Reynolds number and viscous disturbance parameters, and using the benchmark aberration scaling method, the problem of excessive computational requirements caused by multi-dimensional combined analysis is solved, achieving efficient aero-optical aberration prediction and reducing computational resource and time requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
- Filing Date
- 2025-11-21
- Publication Date
- 2026-06-23
AI Technical Summary
Existing technologies require multi-condition and multi-dimensional combined analysis when evaluating the impact of aero-optical transmission effects on the performance of optical systems, which leads to a sharp increase in computational demands, requiring large-scale high-performance computing resources and long-term simulation calculations.
By dividing the external flow field of the aircraft, calculating the Reynolds number and viscous disturbance parameters, dividing the aberration sampling points for calculation and prediction, and scaling the aero-optical aberrations of the reference sampling points, normalized aero-optical aberrations are obtained, reducing the number of calculation condition combinations.
With fixed flight speed, angle of attack, and imaging line-of-sight angle, aberrations at different altitudes can be predicted with only one aero-optical aberration calculation, significantly reducing computational resource requirements and evaluation time.
Smart Images
Figure CN121323938B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optical imaging technology, and in particular relates to a method for calculating aero-optical aberrations. Background Technology
[0002] Airborne optical imaging technology, utilizing imaging sensors mounted on high-speed aircraft, enables precise detection, identification, and tracking of distant targets. It is widely used in reconnaissance, surveillance, precision guidance, and environmental monitoring, playing a crucial role in modern defense and remote sensing. However, when aircraft fly at high or even ultra-high speeds in the atmosphere, they interact violently with the surrounding airflow, creating complex flow field structures outside the optical window. This causes light emitted from the target to deviate from its linear path when passing through this complex aerodynamic environment, resulting in aero-optical transmission effects. These effects cause image shift, blurring, jitter, and energy attenuation, severely limiting imaging accuracy and system performance limits, becoming a key bottleneck for fine airborne optical imaging under high Mach number conditions. Therefore, analyzing and predicting aero-optical transmission effects, and conducting research on aero-optical transmission aberration correction based on this analysis, is of great significance for improving the fine imaging capabilities of high-speed airborne platform optoelectronic imaging systems.
[0003] For a specific aircraft with a defined optical window position and size, the common method for analyzing and predicting aero-optical aberrations is as follows: First, the aero-optical flow field outside the aircraft's optical window is calculated based on flight conditions (including parameters such as flight altitude, flight speed, and angle of attack). Then, ray tracing is performed along different line-of-sight directions to finally obtain the aero-optical aberrations. The difficulty in applying this method lies in the fact that, in order to comprehensively evaluate the impact of aero-optical transmission effects on the performance of the optical system, it is necessary to conduct multi-condition and multi-dimensional combination analysis of variables such as flight altitude, flight speed, angle of attack, and imaging line-of-sight angle. Since each of these four variables has a large number of possible states, the number of combinations increases exponentially with the increase of parameters, forming an extremely large set of conditions. This leads to a sharp increase in computational demands, often requiring the use of large-scale high-performance computing resources for long-term simulation calculations. Summary of the Invention
[0004] In view of this, the present invention aims to provide a method for calculating aero-optical aberrations. The present invention obtains normalized aero-optical aberrations through only one aero-optical transmission aberration calculation, and can then extend it to different flight altitudes. This effectively reduces the number of numerical calculation condition combinations required to comprehensively evaluate the impact of aero-optical transmission effects on the performance of optical systems, and significantly reduces the demand for large-scale computing resources and the time required for evaluation.
[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows:
[0006] A method for calculating aero-optical aberrations includes:
[0007] S1: Define the external flow field for the aircraft model equipped with an optical imaging system; determine the velocity variable conditions and multiple flight altitude sampling points of the aircraft model in the external flow field, as well as the state boundary conditions corresponding to the multiple flight altitude sampling points; calculate the Reynolds number and viscous disturbance parameters under multiple state boundary conditions;
[0008] S2: Based on the Reynolds number and viscous disturbance parameters obtained in step S1, the multiple flight altitude sampling points are divided into calculated aberration sampling points and predicted aberration sampling points; for predicted aberration sampling points, steps S3 and S4 are executed, and for calculated aberration sampling points, step S5 is executed.
[0009] S3: Randomly select one of the predicted aberration sampling points as the reference sampling point, calculate the density distribution of the external flow field under the state boundary conditions corresponding to the reference sampling point, and convert the density distribution into a refractive index distribution; calculate the reference aero-optical aberration generated by the optical imaging system when light passes through the external flow field based on the refractive index distribution;
[0010] S4: Replace other predicted aberration sampling points, and scale the reference aero-optical aberration obtained in step S3 with the state boundary conditions corresponding to the current predicted aberration sampling points to obtain the aero-optical aberration of the optical imaging system under the current state boundary conditions.
[0011] S5: Perform the operation of step S3 on the aberration sampling points to obtain the aero-optical aberrations corresponding to the aberration sampling points.
[0012] Furthermore, step S1, which involves dividing the external flow field of the aircraft model to be analyzed, includes: determining the shape information of the aircraft model and determining the external flow field surrounding the aircraft model based on the shape information; dividing the external flow field into a network and refining the external flow field mesh outside the optical window in the aircraft model.
[0013] Furthermore, in step S1, the velocity variable conditions include the flight speed and angle of attack of the aircraft model, and the state boundary conditions include the free atmospheric density parameter, free atmospheric pressure parameter, and free atmospheric temperature parameter of the aircraft model at the flight altitude sampling point.
[0014] Furthermore, step S1 involves calculating the Reynolds number and viscous disturbance parameters under the current state boundary conditions, including:
[0015] The Reynolds number is calculated based on the free atmospheric density parameter at the flight altitude sampling point, under the condition of the flight altitude sampling point.
[0016] Based on the Reynolds number, the corresponding viscous disturbance parameters are calculated using the following formula:
[0017] ;
[0018] in, The parameters represent viscous disturbances, Ma represents flight speed, Re represents Reynolds number, and ρ represents the viscous disturbance parameter. w ρ represents the flow field density at the wall boundary of the aircraft model. e The flow field density at the outer edge of the boundary layer of the aircraft model is represented by μ. w μ represents the viscosity coefficient at the wall boundary of the aircraft model. e This represents the viscosity coefficient at the outer edge of the boundary layer of the aircraft model.
[0019] Furthermore, in step S2, it is determined whether the Reynolds number and viscous interference parameters obtained in step S1 meet the prediction conditions. The flight altitude sampling points corresponding to the Reynolds number and viscous interference parameters that meet the prediction conditions are divided into prediction aberration sampling points; otherwise, they are divided into calculation aberration sampling points.
[0020] Furthermore, the prediction conditions include: a Reynolds number greater than 10. 6 And the viscosity interference parameter is less than 0.1.
[0021] Furthermore, step S3 includes: numerically solving the NS equation based on the free atmospheric pressure and free atmospheric temperature parameters corresponding to the current flight altitude sampling point to obtain the density distribution of the external flow field; converting the density distribution into a refractive index distribution based on the imaging ray wavelength of the aircraft model through the GD relationship; and numerically solving the ray equation based on the refractive index distribution along the imaging line-of-sight direction to obtain the aero-optical aberrations of the current flight altitude sampling point.
[0022] Furthermore, in step S4: the reference aero-optical aberrations obtained in step S3 are normalized; the normalized aero-optical aberrations are scaled using the following formula to obtain the aero-optical aberrations at the current predicted aberration sampling points:
[0023] ;
[0024] Where Φ represents the aero-optical aberration at the current predicted aberration sampling point. This represents the normalized aero-optical aberrations. This represents the free atmospheric density parameter at the current predicted aberration sampling point.
[0025] The aero-optical aberrations obtained in step S3 are normalized using the following formula:
[0026] ;
[0027] Where Φ0 represents the reference aero-optical aberration. This represents the free atmospheric density parameter at the reference sampling point.
[0028] Compared with the prior art, the present invention can achieve the following beneficial effects:
[0029] This invention presents an aero-optical aberration calculation method. By limiting the Reynolds number and viscous disturbance parameters under different altitude conditions, it ensures that the viscous boundary layer is extremely thin and does not significantly affect the flow in the inviscid core region. The method establishes the similarity of aero-optical aberrations through the flow similarity in the inviscid core region. For a given aircraft, this invention obtains normalized aero-optical aberrations under fixed flight speed, angle of attack, and imaging line-of-sight angle. Aero-optical aberrations under different flight altitude conditions can be obtained by scaling the normalized aero-optical aberrations using the local free atmospheric density parameter, successfully achieving the prediction of aero-optical aberrations at different flight altitudes. Therefore, when comprehensively evaluating the impact of aero-optical transmission effects on the performance of the optical system, only the combined analysis of the three variables—flight speed, angle of attack, and imaging line-of-sight angle—needs to be considered, effectively reducing the demand for large-scale computing resources and the evaluation time. Attached Figure Description
[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0031] Figure 1 A schematic flowchart illustrating the aero-optical aberration calculation method described in the embodiments of the present invention;
[0032] Figure 2 A schematic diagram of the geometric structure of the aircraft model described in the embodiments of the present invention;
[0033] Figure 3 A schematic diagram of the external flow field region as described in the embodiments of the present invention;
[0034] Figure 4 A schematic diagram of the grid distribution near the aircraft model described in the embodiment of the present invention;
[0035] Figure 5 The external flow field distribution diagram of the aircraft model under the conditions of flight speed of 3, flight angle of attack of 0°, and initial flight altitude of 6km as described in the embodiment of the present invention;
[0036] Figure 6 The initial aero-optical aberration distribution diagram with an imaging line-of-sight angle of 0° under the conditions of a flight speed of 3, a flight angle of attack of 0°, and an initial flight altitude of 6km, as described in the embodiment of the present invention.
[0037] Figure 7 Normalized aero-optical aberration distribution diagram under the conditions of flight speed of 3, flight angle of attack of 0°, and imaging line of sight of 0° as described in the embodiment of the present invention;
[0038] Figure 8 The aerodynamic optical aberration distribution map is predicted under the conditions of a flight speed of 3, a flight angle of attack of 0°, an imaging line-of-sight angle of 0°, and a flight altitude of 10km as described in the embodiment of the present invention.
[0039] Explanation of reference numerals in the attached figures:
[0040] 1. Aircraft model; 2. Optical window; 3. External flow field. Detailed Implementation
[0041] 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 merely illustrative of the invention and do not constitute a limitation thereof.
[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.
[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0045] The invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0046] like Figure 1 As shown, the aero-optical aberration calculation method described in the embodiments of the present invention includes:
[0047] S1: Define the external flow field for the aircraft model equipped with an optical imaging system; determine the velocity variable conditions and multiple flight altitude sampling points of the aircraft model in the external flow field, as well as the state boundary conditions corresponding to the multiple flight altitude sampling points; calculate the Reynolds number and viscous disturbance parameters under multiple state boundary conditions.
[0048] In some embodiments, the velocity variable conditions in step S1 include the flight speed and angle of attack of the aircraft model, and the state boundary conditions include the flight altitude of the aircraft model, as well as the free atmospheric density parameter, free atmospheric pressure parameter, and free atmospheric temperature parameter at the flight altitude. Specifically, in this embodiment of the invention, the velocity variable conditions are set as follows: flight speed (Mach number) Ma = 3, and flight angle of attack α = 0°.
[0049] In some embodiments, step S1, which involves dividing the external flow field of the aircraft model to be analyzed, includes: determining the shape information of the aircraft model and determining the external flow field surrounding the aircraft model based on the shape information; dividing the external flow field into a mesh and refining the mesh outside the optical window of the aircraft model. The mesh can be of various forms, such as structured mesh, unstructured mesh, Cartesian mesh, or mosaic mesh. In this embodiment, the aircraft model is selected as a blunt cone model, and the mesh outside the optical window of the aircraft model is refined. Detailed geometric parameters of the aircraft model are as follows: Figure 2 As shown: The semi-cone angle is 12°, the spherical head radius is 100mm, and the blunt cone model has a planar optical window on its side. The plane containing the optical window makes an angle of 10° with the central axis of the blunt cone aircraft. The diameter of the optical window is 200mm, and the distance between its center and the center of the spherical head is 800mm. The external flow field distribution is as follows. Figure 3As shown, the outer flow field 3 completely surrounds the aircraft model 1 and completely covers the compressed flow field region generated by the aircraft model 1 during its ultra-high-speed flight. Furthermore, in this embodiment of the invention, a mosaic grid is used to visualize the outer flow field as follows: Figure 4 The network division operation is shown, and a boundary layer mesh is added. At the same time, the embodiment of the present invention also densifies the external flow field mesh outside the optical window, that is, densifies the mesh in the light transmission region, thereby increasing the mesh density in the light transmission region, that is, increasing the sampling resolution of the flow field in this part, obtaining more refined flow field data, and making the numerical calculation of light transmission more accurate.
[0050] In some embodiments, calculating the Reynolds number and viscous disturbance parameters under the current state boundary conditions in step S1 includes:
[0051] Based on the free atmosphere density parameter at the flight altitude sampling point, the Reynolds number under the condition of the flight altitude sampling point is calculated as follows:
[0052] ;
[0053] Where μ represents the viscosity coefficient, and V represents the relative velocity between the air and the aircraft model. Indicates the characteristic length;
[0054] Based on the Reynolds number, the corresponding viscous disturbance parameters are calculated using the following formula:
[0055] ;
[0056] in, The parameters represent viscous disturbances, Ma represents flight speed, Re represents Reynolds number, and ρ represents the viscous disturbance parameter. w ρ represents the flow field density at the wall boundary of the aircraft model. e The flow field density at the outer edge of the boundary layer of the aircraft model is represented by μ. w μ represents the viscosity coefficient at the wall boundary of the aircraft model. e This represents the viscosity coefficient at the outer edge of the boundary layer of the aircraft model.
[0057] S2: Based on the Reynolds number and viscous disturbance parameters obtained in step S1, the multiple flight altitude sampling points are divided into calculated aberration sampling points and predicted aberration sampling points; for predicted aberration sampling points, steps S3 and S4 are executed, and for calculated aberration sampling points, step S5 is executed.
[0058] In some embodiments, it is determined whether the Reynolds number and viscous disturbance parameters obtained in step S1 meet the prediction conditions. Flight altitude sampling points corresponding to Reynolds number and viscous disturbance parameters that meet the prediction conditions are classified as prediction aberration sampling points; otherwise, they are classified as calculation aberration sampling points. The prediction conditions include: a Reynolds number greater than 10. 6 Furthermore, the viscosity disturbance parameter is less than 0.1, indicating that the boundary layer air thickness of the aircraft model is extremely thin, so that the viscous flow inside the boundary layer will not have a significant impact on the inviscid core region outside the boundary layer.
[0059] S3: Randomly select one of the predicted aberration sampling points as the reference sampling point, calculate the density distribution of the external flow field under the state boundary conditions corresponding to the reference sampling point, and convert the density distribution into a refractive index distribution; calculate the reference aero-optical aberration generated by the optical imaging system when light passes through the external flow field based on the refractive index distribution.
[0060] In this embodiment of the invention, the predicted aberration sampling point at a flight altitude H0 = 6 km is selected as the reference sampling point. The free atmospheric density parameter corresponding to a flight altitude H0 = 6 km can be found. =0.659697kg / m 3 Free atmospheric pressure parameters =47181Pa, and free atmosphere temperature parameters =249.15K. The external flow field distribution of the aircraft model under the conditions of flight speed Ma=3, flight angle of attack α=0°, and flight altitude H0=6km is as follows: Figure 5 As shown. Correspondingly, the free atmosphere density parameter in the baseline state boundary condition. =0.659697kg / m 3 The corresponding Reynolds number Re = 3.94 × 10⁻⁶ 7 >10 6 Viscous interference parameters Satisfying the Reynolds number Re greater than 10 6 The viscous interference parameter needs to be less than 0.1 for prediction conditions to enable subsequent prediction of aero-optical aberrations under different flight altitude conditions.
[0061] In some embodiments, step S3 includes:
[0062] S31: Based on the free atmospheric pressure and temperature parameters corresponding to the sampling point at the current flight altitude, the Navier-Stokes (NS) equations are numerically solved to obtain the density distribution of the external flow field. In this embodiment of the invention, the Reynolds stress-averaged method is used to numerically solve the NS equations to obtain the density distribution of the external flow field. In other embodiments, the density distribution of the external flow field can also be obtained numerically through methods such as large eddy simulation and direct numerical simulation.
[0063] S32: Based on the imaging light wavelength of the aircraft model, the density distribution is converted into a refractive index distribution using the GD relationship. In this embodiment of the invention, the wavelength of the imaging light from the aircraft model is λ = 635 nm, and the density distribution is converted into a refractive index distribution using the following formula:
[0064] n(x,y,z)=1+K G-D ρ(x,y,z);
[0065] Where n(x,y,z) represents the refractive index distribution at position (x,y,z), ρ(x,y,z) represents the density distribution at position (x,y,z), and K... G-D The function representing the relationship between wavelength and light intensity; the K value corresponding to the imaging light wavelength λ=635nm of the aircraft model. G-D The parameter is 2.27 × 10 -4 m 3 / kg.
[0066] S33: Along the imaging line-of-sight angle direction, the ray equation is numerically solved based on the refractive index distribution to obtain the aero-optical aberrations at the sampling point at this flight altitude. In this embodiment of the invention, along the direction perpendicular to the optical window of the aircraft model, i.e., the direction of imaging line-of-sight angle γ=0°, the ray equation is numerically solved using the fourth-order Runge-Kutta method based on the refractive index distribution to calculate the aero-optical aberrations generated by the light rays passing through the external flow field of the aircraft model, such as... Figure 6 As shown. It should be noted that this embodiment of the invention only provides a method for calculating aerodynamic optical aberrations at the imaging line-of-sight angle. In actual calculations, the fourth-order Runge-Kutta method is used to numerically solve the ray equations based on the refractive index distribution to calculate the aerodynamic optical aberrations at each imaging line-of-sight angle. Furthermore, it is well known to those skilled in the art that, in the process of calculating the aerodynamic optical aberrations at the flight altitude sampling point, it is necessary to numerically solve the ray equations and perform extensive ray tracing to obtain the aerodynamic optical aberrations. This is because the purpose of solving the ray equations is to perform ray tracing (i.e., to obtain information about a single ray), and then the information from many rays is combined to obtain the aerodynamic optical aberrations. In other embodiments, cellular automata, Richardson extrapolation, Adams linear multistep method, and other methods can also be used to calculate the aerodynamic optical aberrations at each imaging line-of-sight angle.
[0067] S4: Replace other predicted aberration sampling points, and scale the reference aero-optical aberration obtained in step S3 with the state boundary conditions corresponding to the current predicted aberration sampling points to obtain the aero-optical aberration of the optical imaging system under the current state boundary conditions.
[0068] In this embodiment of the invention, keeping the velocity variable conditions unchanged (i.e., flight speed (Mach number) Ma=3, flight angle of attack α=0°, imaging line-of-sight angle γ=0°), and changing the predicted aberration sampling point at flight altitude H0=10km, the current free atmospheric density parameter corresponding to the current predicted aberration sampling point can be found. =0.412707kg / m 3 Current free atmospheric pressure parameters =26436.3 Pa, and current free atmosphere temperature parameters =223.15K, at which point the corresponding Reynolds number Re is calculated to be 2.55 × 10⁻⁶. 7 >>1, Viscous Interference Parameter It still satisfies the condition that the Reynolds number Re is greater than 10. 6 The viscous disturbance parameter needs to be less than 0.1 in the prediction condition to prove that after the flight altitude of the aircraft model changes, the thickness of the boundary layer of the aircraft model is still extremely thin, so that the viscous flow inside the boundary layer will not have a significant impact on the inviscid core region outside the boundary layer.
[0069] In some embodiments, step S4 includes:
[0070] S41: Normalize the reference aero-optical aberrations obtained in step S3, as shown in the following formula:
[0071] ;
[0072] in, The aero-optical aberrations are normalized, and Φ0 represents the reference aero-optical aberrations. In this embodiment of the invention, the normalized aero-optical aberrations are decomposed using complete two-dimensional basis functions. Using normalized basis function coefficient vectors Characterizing normalized aero-optical aberrations The complete two-dimensional basis functions can be Zernike polynomial functions or other forms, normalizing aero-optical aberrations. The distribution is as follows Figure 7 As shown.
[0073] S42: The normalized aero-optical aberrations are scaled using the following formula to obtain the aero-optical aberrations at the current predicted aberration sampling points:
[0074] ;
[0075] Where Φ represents the aero-optical aberration at the current predicted aberration sampling point. In this embodiment of the invention, the current free atmosphere density parameter is used. For the normalized basis function coefficient vector After scaling, we obtain the basis function coefficient vector a, that is:
[0076] ;
[0077] Wherein, the basis function coefficient vector 'a' represents the predicted aero-optical aberrations of the aircraft model under the conditions of current flight altitude, current flight speed Ma, current flight angle of attack α, and current imaging line-of-sight angle γ. The distribution of the predicted aero-optical aberration Φ is as follows: Figure 8 As shown.
[0078] S5: Perform the operation of step S3 on the aberration sampling points to obtain the aero-optical aberrations corresponding to the aberration sampling points.
[0079] For the flight conditions of Ma=3, angle of attack α=0°, and line-of-sight γ=0°, this invention obtains the normalized aero-optical aberrations through only one aero-optical transmission aberration calculation. This allows for its application to different flight altitudes, effectively reducing the number of numerical calculation conditions required to comprehensively assess the impact of aero-optical transmission effects on optical system performance, and significantly reducing the need for large-scale computing resources and the time required for evaluation.
[0080] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.
[0081] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A method for calculating aero-optical aberrations, characterized in that, include: S1: Delineate the external flow field for the aircraft model equipped with an optical imaging system; Determine the velocity variable conditions and multiple flight altitude sampling points of the aircraft model in the external flow field, as well as the state boundary conditions corresponding to the multiple flight altitude sampling points; calculate the Reynolds number and viscous disturbance parameters under multiple state boundary conditions; S2: Based on the Reynolds number and viscous disturbance parameters obtained in step S1, the multiple flight altitude sampling points are divided into calculated aberration sampling points and predicted aberration sampling points; for predicted aberration sampling points, steps S3 and S4 are executed, and for calculated aberration sampling points, step S5 is executed. S3: Randomly select one of the predicted aberration sampling points as the reference sampling point, calculate the density distribution of the external flow field under the state boundary conditions corresponding to the reference sampling point, and convert the density distribution into a refractive index distribution; calculate the reference aero-optical aberration generated by the optical imaging system when light passes through the external flow field based on the refractive index distribution; S4: Replace other predicted aberration sampling points, and scale the reference aero-optical aberration obtained in step S3 with the state boundary conditions corresponding to the current predicted aberration sampling points to obtain the aero-optical aberration of the optical imaging system under the current state boundary conditions. S5: Perform the operation of step S3 on the aberration sampling points to obtain the aero-optical aberrations corresponding to the aberration sampling points.
2. The aero-optical aberration calculation method according to claim 1, characterized in that, Step S1 involves dividing the external flow field of the aircraft model to be analyzed, including: determining the shape information of the aircraft model and determining the external flow field surrounding the aircraft model based on the shape information; dividing the external flow field into a network and refining the external flow field mesh outside the optical window in the aircraft model.
3. The aero-optical aberration calculation method according to claim 1, characterized in that, In step S1, the velocity variable conditions include the flight speed and angle of attack of the aircraft model, and the state boundary conditions include the free atmospheric density parameter, free atmospheric pressure parameter, and free atmospheric temperature parameter of the aircraft model at the flight altitude sampling point.
4. The aero-optical aberration calculation method according to claim 3, characterized in that, Step S1 involves calculating the Reynolds number and viscous disturbance parameters under the current state boundary conditions, including: The Reynolds number is calculated based on the free atmospheric density parameter at the flight altitude sampling point, under the condition of the flight altitude sampling point. Based on the Reynolds number, the corresponding viscous disturbance parameters are calculated using the following formula: ； in, The parameters represent viscous disturbances, Ma represents flight speed, Re represents Reynolds number, and ρ represents the viscous disturbance parameter. w ρ represents the flow field density at the wall boundary of the aircraft model. e The flow field density at the outer edge of the boundary layer of the aircraft model is represented by μ. w μ represents the viscosity coefficient at the wall boundary of the aircraft model. e This represents the viscosity coefficient at the outer edge of the boundary layer of the aircraft model.
5. The method for calculating aero-optical aberrations according to claim 3, characterized in that, In step S2, it is determined whether the Reynolds number and viscous interference parameters obtained in step S1 meet the prediction conditions. The flight altitude sampling points corresponding to the Reynolds number and viscous interference parameters that meet the prediction conditions are classified as prediction aberration sampling points; otherwise, they are classified as calculation aberration sampling points.
6. The method for calculating aero-optical aberrations according to claim 5, characterized in that, Prediction conditions include: Reynolds number greater than 10 6 And the viscosity interference parameter is less than 0.
1.
7. The method for calculating aero-optical aberrations according to claim 3, characterized in that, Step S3 includes: The NS equations are numerically solved based on the free atmospheric pressure and temperature parameters corresponding to the sampling points at the current flight altitude, and the density distribution of the external flow field is obtained. Based on the imaging light wavelength of the aircraft model, the density distribution is converted into a refractive index distribution through the GD relationship; Along the imaging line-of-sight angle, the ray equation is numerically solved based on the refractive index distribution to obtain the aero-optical aberrations at the sampling point at the flight altitude.
8. The method for calculating aero-optical aberrations according to claim 3, characterized in that, In step S4: The reference aero-optical aberrations obtained in step S3 are normalized; the normalized aero-optical aberrations are scaled using the following formula to obtain the aero-optical aberrations at the current predicted aberration sampling points: ； Where Φ represents the aero-optical aberration at the current predicted aberration sampling point. This represents the normalized aero-optical aberrations. This represents the free atmospheric density parameter at the current predicted aberration sampling point.
9. The method for calculating aero-optical aberrations according to claim 8, characterized in that, The aero-optical aberrations obtained in step S3 are normalized using the following formula: ； Where Φ0 represents the reference aero-optical aberration. This represents the free atmospheric density parameter at the reference sampling point.