Passive device for aerodynamic optical effect suppression based on owl bionic sawtooth structure

Abstract

The application provides a passive suppression device based on a pneumatic optical effect of an owl bionic sawtooth structure, and relates to the field of aerodynamics and optical engineering. The device comprises a base module, a bionic sawtooth structure module and a connecting module. The base module is used for bearing an optical window; the bionic sawtooth structure module is arranged at an upstream corner point of a flow of the optical window, the position is located in a front edge region of the optical window, the bionic sawtooth structure module is composed of a plurality of protrusion units independent of each other, the plurality of protrusion units are uniformly arranged in a single row and straight line along a span direction of the optical window and the center spacing is equal; and the connecting module is used for fixedly connecting the bionic sawtooth structure module and the base module. The application passively modulates a high-speed flow by the plurality of protrusion units, changes a local flow state near the optical window, reduces a root mean square of an optical path difference of an effective light transmission area of the optical window, and realizes passive suppression of the pneumatic optical effect.

Description

Technical Field

[0001] This application relates to the intersection of aerodynamics and optical engineering, and more specifically, to a passive suppression device for aero-optical effects based on an owl-inspired serrated structure. Background Technology

[0002] With the continuous improvement of flight platform performance and the diversification of mission types, the demand for airborne optical systems to perform tasks such as imaging, mapping, directed energy transmission, and laser communication in higher dynamic environments has increased significantly. These applications place more stringent requirements on optical wavefront stability and imaging resolution. As a core component of airborne optical systems, the discontinuous shape of the optical window significantly alters local flow characteristics, leading to complex aero-optical effects and causing problems such as optical wavefront distortion, imaging blurring, and decreased transmission accuracy.

[0003] To suppress the impact of aero-optical effects on imaging and transmission performance, existing methods mainly fall into two categories: active wavefront compensation at the optical level and flow field manipulation at the fluid level.

[0004] In the field of active optical wavefront compensation, techniques such as deformable mirrors and adaptive optics can correct low-frequency, large-scale wavefront distortions in real time, and have been applied in ground-based telescopes and some laser systems. However, these methods are limited in their response to high-frequency, high-dynamic turbulence disturbances, and the systems are complex and costly, making it difficult to achieve effective compensation in airborne high-speed aerodynamic environments.

[0005] In terms of fluid-level control, researchers have proposed various active control strategies, such as film jets and periodic oscillation excitation. These methods actively intervene in the flow structure of the boundary layer or shear layer by applying external energy, which can weaken the flow field density gradient and refractive index fluctuations to a certain extent, thereby improving optical transmittance. However, the above methods generally suffer from problems such as high energy consumption, complex structure, sensitivity to control parameters, and insufficient reliability, making it difficult to meet the engineering requirements of airborne optoelectronic payloads under space-constrained, power-constrained, and long-term stable operation conditions.

[0006] In contrast, passive flow field manipulation methods alter local flow states through structural geometry design or surface feature optimization, thereby suppressing turbulence development and density disturbances at their source. These methods require no external energy input and offer significant advantages such as low power consumption, high reliability, and ease of integration. They can be integrated into the design of optical windows or the overall body shape, and have become an important development direction in the field of aero-optical effect manipulation.

[0007] Therefore, this application proposes a passive suppression device for aero-optical effects based on an owl-inspired sawtooth structure, in order to overcome the technical problems of existing wavefront active compensation systems being complex, having limited response to high-frequency and high-dynamic turbulence disturbances, being difficult to achieve effective compensation in airborne high-speed aerodynamic environments, and active flow field control methods being energy-intensive, structurally complex, and lacking in reliability. Summary of the Invention

[0008] The purpose of this application is to provide a passive suppression device for aero-optical effects based on an owl-inspired serrated structure, which can solve at least one of the aforementioned technical problems. The specific solution is as follows: According to a specific embodiment of this application, this application provides a passive suppression device for aero-optical effects based on an owl-inspired serrated structure, comprising: Base module, biomimetic sawtooth structure module, connection module; The base module is used to support the optical window and provide an installation interface for the biomimetic sawtooth structure module; The biomimetic sawtooth structure module is located at the upstream corner of the incoming flow of the optical window substrate. The upstream corner of the incoming flow is the area near the leading edge of the optical window. The biomimetic sawtooth structure module is composed of multiple independent protruding units. The multiple protruding units are evenly arranged in a single row along the span of the optical window, and the center distance between adjacent protruding units is equal. The connecting module is used to fix the biomimetic sawtooth structure module to the base module; When the high-speed incoming flow passes through the biomimetic sawtooth structure module, the multiple protruding units passively modulate the high-speed incoming flow to change the local flow state near the optical window, thereby reducing the root mean square optical path difference of the effective light-transmitting area of ​​the optical window and achieving passive suppression of aero-optical effects.

[0009] Furthermore, the base module includes: Aircraft turret base or fuselage skin base; The optical window is embedded in the aircraft turret base or the fuselage skin base.

[0010] Furthermore, the connection module includes: Integrated connection unit or detachable connection unit; The integrated connection unit is used to integrally process the biomimetic sawtooth structure module and the base module. The detachable connection unit is used to detachably and fix the biomimetic sawtooth structure module to the base module.

[0011] Furthermore, the protruding unit is a cylindrical protruding unit; Each of the protruding units has the same height and the same diameter.

[0012] Furthermore, the height of the protruding unit is 0.5mm-5mm; The center-to-center distance between adjacent protrusion units is 0.5mm-5mm; The diameter of the protruding unit is 0.3mm-3mm.

[0013] Furthermore, the top of the protruding unit is provided with a chamfered structure, which is used to avoid stress concentration.

[0014] Furthermore, in the detachable connection unit, The mechanical connection method includes bolt connection or positioning groove connection; The bottom of the bionic sawtooth structure module is provided with a mounting base, the mounting base is provided with a connection hole, and the base module is provided with a positioning groove or threaded hole at the corresponding position. A sealing element is provided between the mounting base and the base module.

[0015] Furthermore, the protrusion unit has a circular cross-section, and the center of the protrusion unit is located on the same straight line along the span of the optical window.

[0016] Furthermore, the number of protruding units is determined by the spanwise width of the optical window and the center-to-center distance between adjacent protruding units.

[0017] Furthermore, the biomimetic sawtooth structure module is positioned within a flow distance range of 0mm-10mm upstream of the leading edge of the optical window.

[0018] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects: 1. This application provides a passive suppression device for aero-optical effects based on an owl-inspired sawtooth structure. By setting it at the upstream corner of the incoming flow in the optical window, it passively modulates the high-speed incoming flow. It can change the local flow state near the optical window without external energy input, fundamentally reducing optical path difference fluctuations and avoiding the defects of existing adaptive optics systems such as complex structure, high energy consumption, and limited response to high-frequency turbulence disturbances.

[0019] 2. This application provides a passive suppression device for aero-optical effects based on an owl-inspired sawtooth structure. Multiple protruding units are uniformly arranged in a single row along the span of the optical window, forming a uniform periodic disturbance band upstream of the optical window. This effectively modulates the incoming flow boundary layer, significantly reducing the root mean square (RMS) optical path difference in the effective light-passing area of ​​the optical window. Verified by combined large eddy simulation and ray tracing, under subsonic conditions at Mach 0.5, the OPD RMS decreased from 0.2914 μm to 0.1822 μm after adding this device, a reduction of 37.5%, resulting in a significant improvement in beam quality.

[0020] 3. This application provides a passive suppression device for aero-optical effects based on an owl-inspired serrated structure. By setting the bionic serrated structure module as a detachable connection unit, the bionic serrated structure module with different geometric parameters can be replaced before the flight mission according to the flight Mach number, flight altitude and optical window geometry, so as to realize the designability of parameters, adapt to different flight conditions, and the modular structure can be used in conjunction with the adaptive optics system to form a multi-level suppression architecture of passive suppression and active compensation, with strong compatibility. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 A schematic diagram of the overall structure of the biomimetic sawtooth structure provided in this application embodiment, installed at the upstream corner of the turret window of an aircraft.

[0022] Figure 2 This is a schematic diagram of the incoming airflow direction of the aircraft turret provided in an embodiment of this application.

[0023] Figure 3 This is a biomimetic schematic diagram of the comb-like serrated structure on the leading edge of an owl's wing provided in an embodiment of this application.

[0024] Figure 4 The velocity cloud diagram of the intermediate section of the flow field without the addition of the biomimetic sawtooth structure is provided in the embodiment of this application.

[0025] Figure 5 The velocity cloud diagram of the intermediate section of the flow field after adding the biomimetic sawtooth structure is provided in the embodiment of this application.

[0026] Figure 6 The window OPD distribution diagram provided in this application embodiment without the addition of the biomimetic sawtooth structure.

[0027] Figure 7 The OPD distribution diagram of the window after adding the biomimetic sawtooth structure is provided in the embodiment of this application.

[0028] Explanation of reference numerals in the attached figures: 1. Substrate module; 2. Bionic sawtooth structure module; 3. Optical window; 2-1 Protrusion unit. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0031] The optional embodiments of this application are described in detail below with reference to the accompanying drawings.

[0032] like Figure 1 As shown in the specific embodiments of this application, this application provides a passive suppression device for aero-optical effects based on an owl-inspired serrated structure, including a base module 1, a biomimetic serrated structure module 2, and a connection module.

[0033] The base module 1 supports the optical window 3 and provides an installation interface for the biomimetic sawtooth structure module 2. For example... Figure 2 As shown, the arrows indicate the direction of the incoming flow. The high-speed flow first passes through the front of the turret and then flows along the turret surface to the optical window 3 region. The base module 1 is the aircraft turret base, and the optical window 3 is embedded in the aircraft turret base. The aircraft turret is a commonly used platform for airborne optical systems. The leeward side of the turret is usually the main location for the optical window 3. The leeward side of the turret is directly exposed to the density fluctuations caused by the separation shear layer, which is the main source of aero-optical distortion. Therefore, a biomimetic sawtooth structure module 2 is placed on the leeward side of the turret to intervene before the flow reaches the effective light-transmitting area of ​​the optical window 3.

[0034] As another possible implementation, the substrate module 1 can also be a fuselage skin substrate, with the optical window 3 embedded on the fuselage skin substrate. The fuselage skin substrate solution is suitable for application scenarios where the optical window 3 is directly arranged on the aircraft fuselage.

[0035] The biomimetic sawtooth structure module 2 is positioned at the upstream corner of the incoming flow on the optical window 3 substrate. By placing the biomimetic sawtooth structure module 2 at the upstream corner, its location is near the leading edge of the optical window. This allows the intervention to occur before the incoming flow reaches the leading edge of the optical window, thus modulating the flow during the boundary layer development stage. The flow changes induced by the sawtooth structure have a longer development distance, and the flow changes can form a more sufficient modulation effect when they reach the optical window region.

[0036] In a preferred embodiment of this application, the biomimetic sawtooth structure module 2 is positioned within a flow direction distance range of 0mm-10mm upstream of the leading edge of the optical window 3. When the flow direction distance is 0mm, the biomimetic sawtooth structure module 2 is positioned at the leading edge of the optical window; when the flow direction distance is 10mm, the biomimetic sawtooth structure module 2 is positioned at the upstream corner point. The value between 0mm and 10mm allows the biomimetic sawtooth structure module 2 to modulate the flow at different positions during the boundary layer development stage. A suitable flow direction distance can be selected within the range of 0mm-10mm based on the specific layout position of the optical window 3 on the turret and the available installation space.

[0037] The biomimetic sawtooth structure module 2 consists of multiple independent protruding units 2-1. These independent protruding units 2-1 create discretely distributed disturbance points in the incoming flow. The gaps between adjacent protruding units 2-1 allow fluid to pass between them, preventing excessive obstruction of the incoming flow by a single solid structure. The protruding units 2-1 are arranged uniformly in a single straight row along the span of the optical window 3, with equal center-to-center spacing between adjacent units. This uniformly spaced, single-row arrangement ensures that the flow disturbances generated by each protruding unit 2-1 have consistent periodicity and phase, forming a uniform disturbance band upstream of the optical window 3 and preventing excessive differences in local flow modulation effects due to uneven arrangement. The protruding units 2-1 have a circular cross-section and are arranged in a straight line. The circular cross-section of the protruding units 2-1 results in lower flow resistance and relatively less additional interference and energy loss to the main flow. The connecting module is used to fix the biomimetic sawtooth structure module 2 to the base module 1. The connecting module includes an integrated connecting unit or a detachable connecting unit. The integrated connecting unit is used to integrally machine the biomimetic sawtooth structure module 2 and the base module 1. This integral machining method ensures the flatness and fitting accuracy at the connection point, avoiding flow interference caused by assembly errors, and is suitable for mature flight platforms where the biomimetic sawtooth structure parameters are already determined. The detachable connecting unit is used to detachably fix the biomimetic sawtooth structure module 2 to the base module 1.

[0038] In embodiments employing detachable connection units, the mechanical connection methods include bolt connections or positioning groove mating connections. The bottom of the bionic sawtooth structure module 2 is provided with a mounting base, which has a connection hole. The base module 1 has a corresponding positioning groove or threaded hole. During assembly, the bionic sawtooth structure module 2 is placed in the positioning groove upstream of the base module 1. Bolts are passed through the connection hole on the mounting base and screwed into the threaded hole on the base module 1, detachably fixing the bionic sawtooth structure module 2 to the base module 1. The positioning groove ensures that the position of the bionic sawtooth structure module 2 on the base module 1 is consistent each time it is installed, avoiding installation position deviations that could affect the flow modulation effect. A seal is provided between the mounting base and the base module 1 to prevent high-speed airflow from entering the gap between the mounting base and the base module 1, thus preventing additional vibration or noise. Preferably, the seal is an O-ring.

[0039] When a detachable connection unit is used, the biomimetic sawtooth structure module 2 is a replaceable module before the mission. Different flight missions correspond to different geometric parameters of the biomimetic sawtooth structure module 2, including sawtooth height h, adjacent sawtooth spacing λ, and sawtooth diameter Φ. The replacement of the biomimetic sawtooth structure module 2 is completed on the ground before the flight mission, based on factors including flight Mach number, flight altitude, and the geometric configuration of the optical window 3. For different flight missions, sawtooth modules with different h, λ, and Φ parameters can be replaced during the ground preparation phase; parameter combinations are determined through parametric simulation, surrogate models, and optimization methods. By replacing the biomimetic sawtooth structure module 2 with different parameters, the same base module 1 and optical window 3 can be adapted to various flight conditions, eliminating the need to redesign and manufacture the entire device for each flight condition, thus reducing usage costs and deployment cycle.

[0040] As one possible implementation of this application, the biomimetic sawtooth structure module 2 can be made of a flexible material. This flexible material can adaptively deform under the influence of incoming flow, and this adaptive deformation can modulate the shear layer and its coherent flow structure. The flexible material can be selected from polyimide, silicone rubber, or shape memory alloy. Under the influence of high-speed incoming flow, the tip of the protruding unit 2-1 made of flexible material can undergo slight vibration or bending deformation according to the velocity and pressure of the incoming flow, thereby causing the effective height and windward angle of the protruding unit 2-1 to adaptively change with the incoming flow conditions, producing a passive modulation effect different from that of rigid protrusions. Those skilled in the art can select a suitable flexible material according to the temperature and load requirements of the flight conditions.

[0041] This application provides a preferred technical solution where the protruding unit 2-1 is a cylindrical protruding unit 2-1. Each cylindrical protruding unit 2-1 has the same height h and the same diameter Φ. Using the same height and diameter for each protruding unit 2-1 ensures that the flow disturbance intensity generated by each protruding unit 2-1 is consistent, thereby forming a uniform periodic disturbance array. The center-to-center distance between adjacent cylindrical protruding units 2-1 is denoted as λ.

[0042] The height h of the cylindrical protrusion unit 2-1 is 0.5mm-5mm. Within the range of 0.5mm-5mm, if the value of h is too small, such as close to 0.5mm, the processing difficulty of the protrusion unit 2-1 increases, the structural strength decreases, and it may deform or be damaged under the action of high-speed incoming flow; if the value of h is too large, such as close to 5mm, the protrusion unit 2-1 may induce additional flow separation, which will worsen the flow field uniformity near the light window. Preferably, the height h of the cylindrical protrusion unit 2-1 is 2mm.

[0043] The center-to-center distance λ between adjacent cylindrical protrusion units 2-1 is 0.5mm-5mm. Within the range of 0.5mm-5mm, when the value of λ is too small, the spacing between adjacent protrusion units 2-1 is too dense, increasing the spanwise interference effect between the protrusion units 2-1 and potentially causing unfavorable flow disturbances; when the value of λ is too large, the spacing between adjacent protrusion units 2-1 is too sparse, failing to form an effective periodic disturbance array and weakening the modulation effect on the flow. Preferably, the center-to-center distance λ between adjacent cylindrical protrusion units 2-1 is 2mm.

[0044] The diameter Φ of the cylindrical protrusion unit 2-1 is 0.3mm-3mm. Within the range of 0.3mm-3mm, when the value of Φ is too small, the stiffness of the protrusion unit 2-1 is insufficient, and it is prone to flutter or breakage under the action of high-speed flow; when the value of Φ is too large, the blocking effect generated by the protrusion unit 2-1 in the flow field is enhanced, which may induce additional flow separation. Preferably, the diameter Φ of the cylindrical protrusion unit 2-1 is 1mm.

[0045] The above-mentioned preferred values ​​h=2mm, λ=2mm, and Φ=1mm are parameter combinations verified by joint simulation of large eddy simulation and ray tracing. Under the above-mentioned preferred parameter combinations, the OPD RMS of the effective light-transmitting area of ​​optical window 3 is reduced from 0.2914μm without the addition of the bionic sawtooth structure to 0.1822μm, a reduction of about 37.5%.

[0046] The technical solution of this application embodiment also provides a preferred embodiment, wherein the top end of the protruding unit 2-1 is provided with a chamfer structure. The chamfer structure is used to avoid stress concentration. Under high-speed incoming flow conditions, the top end of the protruding unit 2-1 bears a large aerodynamic load. If the top end of the protruding unit 2-1 is a sharp edge, stress concentration is likely to occur at the root of the protruding unit 2-1, leading to structural fatigue or fracture. By providing a chamfer structure at the top end of the protruding unit 2-1, stress can be effectively dispersed, improving the service life and reliability of the structure.

[0047] like Figure 3 As shown, the comb-like serrated structure of the owl wing leading edge can effectively weaken the coherent vortex structure of the shear layer under conditions without external energy input, thereby achieving the dispersion of turbulent energy and significant suppression of flow noise. The technical solution of this application, drawing on the comb-like serrated configuration of the owl wing leading edge and considering the specific requirements for suppressing aero-optical effects at the airborne optical window 3, sets multiple cylindrical protrusion units 2-1 arranged along the spanwise direction upstream of the incoming flow at the optical window 3. This passively modulates the flow near the optical window 3 to reduce optical path difference fluctuations.

[0048] When the high-speed incoming flow passes through the biomimetic sawtooth structure module 2, multiple protruding units 2-1 passively modulate the flow. These protruding units 2-1 are uniformly arranged along the spanwise direction, forming a continuous disturbance band upstream of the optical window 3. This alters the velocity distribution and flow state of the incoming flow reaching the optical window 3 region compared to the case without sawtooths, thereby reducing the root mean square optical path difference (OPD RMS) of the effective light-transmitting region of the optical window 3 and achieving passive suppression of aero-optical effects. The technical solution of this application does not rely on specific energy spectrum migration or vortex structure evolution laws as essential technical features, but rather uses the OPD RMS of the effective light-transmitting region of the optical window 3 as a quantitative evaluation index of the aero-optical suppression effect.

[0049] Verified by joint simulation using Large Eddy Simulation (LES) and ray tracing, under the conditions of flight Mach number Ma=0.5 and optical window 3 located on the leeward side of the turret, without the addition of the biomimetic sawtooth structure, the OPD RMS of the effective light-transmitting area of ​​optical window 3 is 0.2914 μm; after adding the biomimetic sawtooth structure of this embodiment, the height h of protruding unit 2-1 is 2 mm, the center-to-center distance λ between adjacent protruding units 2-1 is 2 mm, and the diameter Φ of protruding unit 2-1 is 1 mm, the OPD RMS is reduced to 0.1822 μm, a reduction of approximately 37.5%. Figures 4 to 7 As shown. Figure 4 and Figure 5 Velocity contour plots of the flow field at the mid-section are presented under the same flight conditions, with and without the biomimetic sawtooth structure. Figure 4 and Figure 5 The color swatch ranges are different. Figure 4 and Figure 5 The images are mainly used to show the distribution pattern; the quantitative aero-optical effects are uniformly based on OPD RMS. Figure 6 and Figure 7 The window OPD distribution diagrams are given for the window without and with the biomimetic serrated structure.

[0050] Figure 4 and Figure 5 Velocity contour maps of the flow field at the mid-section are presented under the same flight conditions, with and without the biomimetic sawtooth structure. Figure 4 and Figure 5 This displays the velocity distribution across a cross-section of the flow field, using color depth or color scales to represent velocity values ​​at different locations. The horizontal axis represents the position along the direction of the incoming flow, i.e., the direction of airflow, while the vertical axis represents the position perpendicular to the direction of the incoming flow. Both graphs use dark blue to represent low-velocity regions and red to represent high-velocity regions, with color scales covering the range of 0–270 m / s. This allows for direct comparison of differences in the velocity distribution patterns of the flow field, rather than directly comparing absolute values ​​based on the same color. Figure 4 As shown, without the addition of the biomimetic sawtooth structure, when the high-speed incoming flow from upstream of the turret flows along the turret surface to the optical window 3 region, a significant velocity shear layer forms above the optical window 3, resulting in a large-scale, uncontrolled vortex structure exhibiting significant flow separation characteristics. This large-scale vortex structure leads to an uneven distribution of the flow field density gradient in the effective light-transmitting area of ​​the optical window 3, which is the main cause of the flow field fluctuations in optical path difference. The narrow and intense transition zone between the high-speed and low-speed regions indicates that the shear layer has a high strength. When the high-speed incoming flow flows along the turret surface to the optical window 3 region, due to the discontinuous shape of the optical window 3, the flow separates at the leading edge of the window, forming a large-scale vortex structure. The large area of ​​uneven color shown in the contour map reflects the spatial distribution of the large-scale vortex structure. The large velocity gradient inside the vortex structure leads to intense density pulsations. Figure 5 As shown, after the addition of the bionic sawtooth structure, the flow pattern upstream of the optical window 3 changes significantly. The velocity distribution and flow state near the optical window 3 are different from those without the bionic sawtooth structure, and the flow field structure is more uniform than that without the bionic sawtooth structure. Figure 5 The velocity transition band near optical window 3 is extended, indicating that the biomimetic sawtooth structure modulates the flow within the boundary layer. The color distribution of the flow field above the optical window is relative to... Figure 4 The flow is more uniform, indicating that large-scale vortex structures are suppressed. The scale of the flow separation region is reduced, and the flow field structure is more ordered compared to when no biomimetic sawtooth structure was added.

[0051] Figure 6 and Figure 7Optical path difference distribution diagrams of the optical window without and with the biomimetic serrated structure are presented under the same flight conditions. The optical path difference values ​​at different locations are represented by color depth or color scales. The color scale ranges of the two diagrams differ; the images primarily illustrate the spatial morphology of the optical path difference distribution and do not directly compare absolute values ​​based on the same color. The horizontal axis represents the spanwise direction of optical window 3, i.e., the position of the arrangement direction of multiple protruding units 2-1, and the vertical axis represents the normal direction of optical window 3, i.e., the position perpendicular to the spanwise direction. Different colored areas in the diagram represent the magnitude of the optical path difference at the corresponding positions; the smaller the overall fluctuation amplitude, the better the suppression of aero-optical effects. Figure 6 As shown, without the biomimetic sawtooth structure, the spatial distribution of the optical path difference in the effective light-passing area of ​​optical window 3 exhibits a large range of alternating positive and negative fluctuations. The red and blue regions are interspersed and have large areas, indicating large amplitude and drastic spatial variations in the optical path difference. The root mean square of the optical path difference is 0.2914 μm. The spatial distribution of the optical path difference shows obvious non-uniformity. The existence of large-scale alternating positive and negative regions indicates that a complete large-scale coherent structure is preserved in the unmodulated flow field. This structure causes a large-scale density gradient change above the optical window, thus causing significant optical path difference fluctuations. Figure 7 As shown, after adding the biomimetic sawtooth structure, the areas of the red and blue regions are reduced, and the color transition is smoother, indicating that the fluctuation amplitude of the optical path difference is reduced and the spatial distribution is more uniform. The overall fluctuation amplitude of the root mean square spatial distribution of the optical path difference is significantly reduced, with the root mean square of the optical path difference decreasing to 0.1822 μm, a reduction of approximately 37.5%, indicating that the fluctuation of the optical path difference in the effective light-passing area of ​​optical window 3 is effectively suppressed.

[0052] For a given flight condition, the sawtooth height h, the distance λ between adjacent sawtooths, and the sawtooth diameter Φ of the biomimetic sawtooth structure module 2 are determined as follows: Based on the aircraft's predetermined flight Mach number Ma, flight altitude H, and the geometric configuration of the turret and optical window 3, an aerodynamic flow field calculation model and a ray tracing calculation model are established. The flight Mach number and flight altitude determine the flow field characteristic parameters such as the velocity, density, temperature, and boundary layer thickness of the incoming flow. The geometric configuration of the turret and optical window 3 determines the location of flow separation and the development path of the shear layer. These parameters together constitute the input conditions for the aerodynamic flow field calculation and ray tracing calculation.

[0053] Using the height h of the biomimetic sawtooth structure, the spacing λ between adjacent biomimetic sawtooth structures, and the diameter Φ of the biomimetic sawtooth structure as design variables, multiple parameter combinations are set. For example, in a specific implementation, the value range of h can be selected as 0.5mm-5mm, the value range of λ can be selected as 0.5mm-5mm, and the value range of Φ can be selected as 0.3mm-3mm. Several discrete values ​​are selected within each value range and combined to form multiple parameter combinations.

[0054] Aerodynamic flow field calculations and ray tracing calculations were performed for each parameter combination to obtain the OPD RMS of the effective light-transmitting area of ​​optical window 3 for each parameter combination. OPD RMS is a commonly used indicator for quantitatively evaluating the strength of aero-optical effects. The smaller the OPD RMS value, the smaller the optical path difference fluctuation within the effective light-transmitting area of ​​optical window 3, and the higher the imaging or transmission quality.

[0055] In the technical solution of this application embodiment, the number n of protruding units 2-1 is determined by the spanwise width W of the optical window 3 and the center distance λ between adjacent protruding units 2-1, that is, n = W / λ.

[0056] In practical applications, the number of protruding units 2-1 also depends on the margin between the first and last protruding units 2-1 and the edges of the two sides of the optical window 3. When the spanwise width of the optical window 3 is W, n protruding units 2-1 need to be arranged within the range of W. The distance between the first protruding unit 2-1 and one side edge of the optical window 3 is... The distance from the last protruding unit 2-1 to the other side boundary of the optical window 3 is If the center-to-center distance between adjacent protrusion units 2-1 is λ, then the following condition is met: Preferably, and Equal to each other, such that multiple protruding units 2-1 are centrally arranged in the spanwise direction of the optical window 3; preferably, and All are not less than This is to ensure the flow modulation effect of the edge protrusion unit 2-1 on the edge region of the optical window 3.

[0057] To ensure the biomimetic sawtooth structure can form an effective periodic perturbation array, the number n of protruding units 2-1 is greater than or equal to 3. If the number of protruding units 2-1 is less than 3, the spanwise spacing between adjacent protruding units 2-1 is too large, and the flow perturbations generated by each protruding unit 2-1 are independent, failing to form a continuous perturbation band. Therefore, the modulation effect on the shear layer is insufficient to effectively reduce optical path difference fluctuations. When the number of protruding units 2-1 is greater than or equal to 3, multiple protruding units 2-1 are uniformly distributed along the spanwise direction of the optical window 3. The perturbations generated by adjacent protruding units 2-1 are superimposed in the spanwise direction, forming a continuous perturbation band upstream of the optical window 3, effectively changing the local flow state near the optical window 3. For example, if the spanwise width W of the optical window 3 is 10 mm and the center-to-center spacing λ of adjacent protruding units 2-1 is 2 mm, then the number of protruding units 2-1 is n = 10 / 2 = 5, satisfying the condition n ≥ 3.

[0058] When a detachable connection unit is used, the biomimetic sawtooth structure module 2 is a replaceable module before the mission. Different flight missions correspond to different geometric parameters of the biomimetic sawtooth structure module 2, including sawtooth height h, adjacent sawtooth spacing λ, and sawtooth diameter Φ. The replacement of the biomimetic sawtooth structure module 2 is completed on the ground before the flight mission, based on factors including flight Mach number, flight altitude, and the geometric configuration of optical window 3. For different flight missions, sawtooth modules with different h, λ, and Φ parameters can be replaced during the ground preparation phase. After obtaining the root mean square of optical path difference corresponding to different parameter combinations through parametric numerical simulation, a surrogate model is established with the minimum root mean square of optical path difference as the optimization objective, and an optimization algorithm is used to determine the sawtooth parameter combination suitable for the flight condition.

[0059] The passive aero-optical effect suppression device based on an owl-inspired sawtooth structure proposed in this application can be used in conjunction with existing adaptive optics systems. The biomimetic sawtooth structure module 2 is installed upstream of the optical window 3 to passively modulate the high-speed incoming flow, reducing optical path difference fluctuations at the flow field source. The adaptive optics system is positioned downstream of the optical window 3 in the optical path to actively compensate for residual wavefront distortion. The biomimetic sawtooth structure module 2 and the adaptive optics system are arranged in series along the optical path, forming a multi-stage aero-optical effect suppression architecture of passive suppression and active compensation, which can further improve the overall performance of the optical system.

[0060] This application provides a passive suppression device for aero-optical effects based on an owl-inspired sawtooth structure. It has a simple structure, requires no external power source, and its parameters can be designed according to flight conditions. It can be widely used to suppress the aero-optical effects of optical windows 3 of various aircraft, and can also be extended to other scenarios that require suppression of turbulence-induced optical distortion, such as airborne photoelectric detection systems, spaceborne optical remote sensing equipment, and airborne laser communication terminals.

[0061] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0062] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A passive suppression device for aero-optical effects based on an owl-inspired serrated structure, characterized in that, include: Base module, biomimetic sawtooth structure module, connection module; The base module is used to support the optical window and provide an installation interface for the biomimetic sawtooth structure module; The biomimetic sawtooth structure module is located at the upstream corner of the optical window substrate. The biomimetic sawtooth structure module is composed of multiple independent protruding units. The multiple protruding units are evenly arranged in a single straight line along the span of the optical window, and the center distance between adjacent protruding units is equal. The connecting module is used to fix the biomimetic sawtooth structure module to the base module; When the high-speed incoming flow passes through the biomimetic sawtooth structure module, the multiple protruding units passively modulate the high-speed incoming flow to change the local flow state near the optical window, thereby reducing the root mean square optical path difference of the effective light-transmitting area of ​​the optical window and achieving passive suppression of aero-optical effects.

2. The passive suppression device for aero-optical effects according to claim 1, characterized in that, The base module includes: Aircraft turret base or fuselage skin base; The optical window is embedded in the aircraft turret base or the fuselage skin base.

3. The passive suppression device for aero-optical effects according to claim 1, characterized in that, The connection module includes: Integrated connection unit or detachable connection unit; The integrated connection unit is used to integrally process the biomimetic sawtooth structure module and the base module. The detachable connection unit is used to detachably and fix the biomimetic sawtooth structure module to the base module.

4. The passive suppression device for aero-optical effects according to claim 1, characterized in that, The protruding unit is a cylindrical protruding unit; Each of the protruding units has the same height and the same diameter.

5. The passive suppression device for aero-optical effects according to claim 4, characterized in that, The height of the protruding unit is 0.5mm-5mm; The center-to-center distance between adjacent protrusion units is 0.5mm-5mm; The diameter of the protruding unit is 0.3mm-3mm.

6. The passive suppression device for aero-optical effects according to claim 1, characterized in that, The top of the protruding unit is provided with a chamfered structure, which is used to avoid stress concentration.

7. The passive suppression device for aero-optical effects according to claim 3, characterized in that, In the detachable connection unit Mechanical connection methods include bolted connections or locating groove connections; The bottom of the bionic sawtooth structure module is provided with a mounting base, the mounting base is provided with a connection hole, and the base module is provided with a positioning groove or threaded hole at the corresponding position. A sealing element is provided between the mounting base and the base module.

8. The passive suppression device for aero-optical effects according to claim 1, characterized in that, The protruding unit has a circular cross-section, and multiple protruding units are arranged in a straight line.

9. The passive suppression device for aero-optical effects according to claim 1, characterized in that, The number of protrusion units is determined by the spanwise width of the optical window and the center-to-center distance between adjacent protrusion units.

10. The passive suppression device for aero-optical effects according to claim 1, characterized in that, The biomimetic sawtooth structure module is positioned within a flow distance range of 0mm-10mm upstream of the leading edge of the optical window.

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