New energy automobile body drag reduction structure design method based on sharkskin surface microstructure

Abstract

The invention discloses a new energy automobile body anti-drag structure design method based on a sharkskin surface microstructure, and relates to the technical field of new energy automobile body design. Through a systematic design method, sharkskin microstructure data collection, automobile body surface area division, microstructure parameter optimization and graded manufacturing are carried out, and a new energy automobile body anti-drag structure is obtained. Accurate design of the new energy automobile body resistance reduction structure is achieved, in the data acquisition stage, a comprehensive sharkskin surface microstructure database is established, the optimal parameter range is determined in combination with the actual working condition, in the design process, different areas of an automobile body are matched and microstructure parameters are optimized based on computational fluid mechanics simulation, and the design accuracy of the new energy automobile body resistance reduction structure is improved. The non-uniform microstructure distribution network conformal with the curved surface of the vehicle body is formed, a hierarchical manufacturing design scheme is provided, the non-uniform microstructure distribution network is divided into a high-curvature curved surface area, a low-curvature plane area and a transition connection area according to the characteristics of different areas of the vehicle body, and high-precision manufacturing of the microstructure is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle body design, and specifically provides a design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin. Background Art

[0002] New energy vehicles, with their advantage of low emissions, have become an important direction for the development of the automotive industry. However, during high-speed driving, air resistance is one of the main factors leading to energy consumption in new energy vehicles, accounting for 20%-30% of the total energy consumption. Therefore, reducing the air resistance of the vehicle body is of great significance for improving the endurance and reducing energy consumption of new energy vehicles.

[0003] Currently, most existing vehicle drag reduction technologies focus on traditional shape optimization and installation of additional devices. When conducting vehicle drag reduction design, the complex curved surfaces and actual driving conditions of new energy vehicle bodies are not fully considered, resulting in poor adaptability between the microstructure and the vehicle body and unsatisfactory drag reduction effects. Moreover, traditional new energy vehicle body drag reduction designs mostly rely on macroscopic shape optimization, but have limited effects on suppressing microscale turbulence. The micron-scale ribbed structure on the shark skin surface can effectively reduce fluid resistance. Existing technologies fail to conduct differential microstructure design based on airflow characteristics and cannot fully exploit the drag reduction potential of the shark skin microstructure.

[0004] In summary, in order to effectively improve the endurance and energy utilization efficiency of new energy vehicles, there is an urgent need for a design method for a drag reduction structure of a new energy vehicle body with high adaptability and capable of fully exploiting the drag reduction advantages of the shark skin microstructure to solve the problems existing in the prior art. Summary of the Invention

[0005] The purpose of the present invention is to make up for the deficiencies of the prior art and provide a design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin. It can achieve precise design of the drag reduction structure of a new energy vehicle body through a systematic design method, from data acquisition of the shark skin microstructure, division of the vehicle body surface area, optimization of microstructure parameters to hierarchical manufacturing. In the data acquisition stage, a comprehensive database of the shark skin surface microstructure is established, and the optimal parameter range is determined in combination with the actual working conditions. During the design process, based on computational fluid dynamics simulation, the microstructure parameters are matched and optimized for different regions of the vehicle body to form a non-uniform microstructure distribution network conformal to the vehicle body surface, and a targeted manufacturing plan is designed, effectively reducing energy consumption during driving and significantly increasing the endurance of new energy vehicles.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, and the specific steps of this method are as follows:

[0007] S100. Obtain the geometric morphology of the micro-structure on the shark skin surface through 3D scanning technology, extract key parameters, including rib height H, rib spacing S, rib inclination angle θ, and asymmetric corrugation period λ, and establish a parametric database;

[0008] S200. Based on computational fluid dynamics simulation, divide the vehicle body surface into a high-speed turbulent region, a medium-speed transition region, and a low-speed separation region. Combining the flow velocity distribution characteristics of each region, match the shark skin micro-structure parameters from the parametric database;

[0009] S300. Establish a multi-objective optimization function, with the drag coefficient and local pressure gradient as optimization objectives. After iteratively adjusting the micro-structure parameters, generate a non-uniform micro-structure distribution network conformal to the vehicle body surface through topology optimization technology;

[0010] S400. For the non-uniform micro-structure distribution network, design a hierarchical manufacturing design scheme. The hierarchical manufacturing design scheme divides the non-uniform micro-structure distribution network into a high-curvature surface area, a low-curvature plane area, and a transition connection area, forming a dynamic slip boundary similar to the shark skin mucus layer;

[0011] S500. Measure the drag coefficient of the micro-structure vehicle body installed with the hierarchical manufacturing design scheme in a wind tunnel experiment, compare the simulation data, and dynamically adjust the micro-structure parameters in S300.

[0012] Furthermore, in S100, the 3D scanning technology uses a laser confocal microscope to scan the shark skin sample to obtain complete morphology data including the three-dimensional curvature distribution of the ribs and the phase of the asymmetric corrugations;

[0013] The parametric database also includes the distribution rules of micro-structure parameters and the corresponding hydrodynamic performance data under different shark species and different growth stages, where H ∈ [0.1 mm, 0.5 mm], S ∈ [0.5 mm, 2.0 mm], θ ∈ [10°, 45°], and λ ∈ [1 mm, 8 mm].

[0014] Even further, the process of vehicle body surface zoning and micro-structure parameter matching in S200 is as follows:

[0015] Based on the computational fluid dynamics simulation results, extract the flow velocity distribution data on the vehicle body surface and define the zoning criterion:

[0016] High-speed turbulent region: The region where the flow velocity ≥ 35 m / s and the turbulence intensity ≥ 10%;

[0017] Medium-speed transition region: The region where the flow velocity is 15 - 35 m / s and the absolute value of the pressure gradient ≤ 200 Pa / m;

[0018] Low-speed separation region: The region where the flow velocity ≤ 15 m / s and there are flow separation eddies;

[0019] According to the partition criterion, the front grille, the outer edge of the rearview mirror, and the front side of the A-pillar are divided into a high-speed turbulent zone, the front part of the roof and the middle section of the door are the medium-speed transition zone, and the area behind the rear spoiler and the inner side of the C-pillar are the low-speed separation zone.

[0020] Furthermore, during the process of matching the shark skin microstructure parameters in S200, by establishing the bionic parameter mapping rules for each zone:

[0021] High-speed turbulent zone: Call the parameters of the head area of the shark skin, that is, H = 0.1 - 0.3 mm, S = 0.5 - 1.2 mm, θ = 30° - 45°, λ = 1.0 - 2.5 mm, and limit the angle between the rib direction and the oncoming flow direction ≤ 10°;

[0022] Low-speed separation zone: Call the parameters of the lateral line area of the shark skin, that is, H = 0.3 - 0.5 mm, S = 1.5 - 2.0 mm, θ = 10° - 20°, λ = 5 - 8 mm, and the rib direction deflects 15° - 30° according to the rotation direction of the separation vortex;

[0023] Medium-speed transition zone: Adopt the parameters of the abdomen and lateral line area of the shark skin, that is, H = 0.2 - 0.4 mm, S = 1.0 - 1.5 mm, λ = 2.5 - 4.0 mm, and dynamically adjust θ according to the positive and negative values of the local pressure gradient:

[0024] When the pressure gradient is negative, θ increases by 5° - 8°;

[0025] When the pressure gradient is positive, θ decreases by 3° - 5°.

[0026] Furthermore, the multi-objective optimization function of S300 Among them, C d is the drag coefficient corresponding to the optimization process, Cd0 is the reference drag coefficient without adding the microstructure, is the absolute value of the pressure gradient corresponding to the optimization process, α = 0.7, β = 0.3 are the weight coefficients, is the absolute value of the maximum pressure gradient on the vehicle body surface. With H, S, θ, λ as the design variables, the constraint range is the same as the partition parameters in S200. After determining the design variables, optimize the microstructure combination by adjusting the values of the partition parameters.

[0027] Furthermore, the process of generating a non-uniform microstructure distribution network conformal to the vehicle body surface through topology optimization technology in S300 is as follows:

[0028] After optimizing the microstructure parameters, discretize the vehicle body surface into quadrilateral meshes, and assign a microstructure density coefficient ρ to each mesh element, where ρ = 0 means no structure and ρ = 1 means full structure;

[0029] Taking the minimization of the total energy consumption as the optimization goal, solve the equation where ρ e is the microstructure density coefficient of the e-th grid cell, N is the total number of grid cells, U e is the aerodynamic dissipation energy of the cell, V e is the modulus of the flow velocity gradient. By minimizing the total energy consumption, the microstructures are arranged in the grid cells to optimize the overall aerodynamic performance, that is, the optimal distribution of the microstructures is found from the perspective of energy loss.

[0030] Furthermore, the S400 calculates the curvature of the body surface through CAD modeling and conducts hierarchical manufacturing design on the non-uniform microstructure distribution network according to the curvature:

[0031] High-curvature surface area: The body surface curvature ≥ 0.05 mm -1 and the local flow velocity ≥ 25 m / s. The nanoimprint technology is used to ensure the morphology accuracy;

[0032] Low-curvature flat area: The body surface curvature ≤ 0.01 mm -1 and the absolute value of the pressure gradient ≤ 100 Pa / m. Laser micro-texturing is used;

[0033] Transition connection area: The body surface curvature ∈ is 0.01 - 0.05 mm -1 and there is an abrupt change in the flow curvature. It is used to connect the structures in the high- and low-curvature areas and suppress the airflow separation. Laser micro-texturing is used. The abrupt change in the flow curvature means that when the airflow flows along the body surface, the curvature of the surface changes sharply in the airflow direction.

[0034] Furthermore, the S500 wind tunnel experiment is carried out in a closed-circuit wind tunnel. The new energy vehicle model installed with the microstructures designed by the hierarchical manufacturing design scheme is placed in the wind tunnel test section in the actual driving posture. The air forces received by the vehicle model at different airflow speeds are measured. The pressure sensor is used to measure the pressure distribution on the body surface, and the hot-wire anemometer is used to measure the flow field velocity distribution on the body. The wind resistance coefficient measured in the wind tunnel experiment is compared and analyzed with the computational fluid dynamics simulation data, and the reduction rate of the wind resistance coefficient is calculated When the reduction rate of the wind resistance coefficient δ ≤ 8%, it is determined as ineffective drag reduction, and the microstructure parameters of the S300 are adjusted until the reduction rate of the wind resistance coefficient δ > 8%.

[0035] Compared with the prior art, the design method of the drag reduction structure for the body of the new energy vehicle based on the shark skin surface microstructure has the following beneficial effects:

[0036] 1. The present invention realizes the precise design of the drag reduction structure for the body of a new energy vehicle through a systematic design method, from the data acquisition of shark skin microstructures, the division of the body surface area, the optimization of microstructure parameters to hierarchical manufacturing. In the data acquisition stage, a comprehensive database of shark skin surface microstructures is established, and the optimal parameter range is determined in combination with the actual working conditions. During the design process, based on computational fluid dynamics simulation, the microstructure parameters are matched and optimized for different areas of the body to form a non-uniform microstructure distribution network conformal to the body surface, and a hierarchical manufacturing design scheme is proposed. According to the characteristics of different areas of the body, the non-uniform microstructure distribution network is divided into a high-curvature curved surface area, a low-curvature flat surface area, and a transition connection area, and nanoimprint lithography technology and laser microtexturing processing are respectively used to achieve the high-precision manufacturing of the microstructures, which not only improves the processing quality and stability of the microstructures, but also endows the body surface with drag reduction characteristics similar to the mucus layer of shark skin, providing new ideas and methods for the development of the body manufacturing technology of new energy vehicles.

[0037] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0039] Figure 1 It is an operation flowchart of a design method for the drag reduction structure of the body of a new energy vehicle based on the surface microstructure of shark skin;

[0040] Figure 2 It is a systematic step diagram of a design method for the drag reduction structure of the body of a new energy vehicle based on the surface microstructure of shark skin. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention objective, the following will, in conjunction with the accompanying drawings and preferred embodiments, describe in detail the specific embodiments, structures, features, and their effects of the present invention as follows.

[0042] Embodiment 1

[0043] This embodiment focuses on a design method for the drag reduction structure of the body of a new energy vehicle based on the surface microstructure of shark skin, as Figure 2As shown, through systematic steps, starting from obtaining the microstructure data of shark skin, going through the division of the vehicle body surface area, the optimization of microstructure parameters, the hierarchical manufacturing design, and the experimental verification and parameter adjustment, the aim is to reduce the drag of the new energy vehicle body and improve the endurance ability.

[0044] First, enter the stage of shark skin microstructure data acquisition and database establishment (S100). Select a laser confocal microscope to scan the shark skin sample. The working principle of the laser confocal microscope is to use a laser beam to scan the sample point by point. Through the focusing system, the laser is focused on a specific depth of the sample. Only the fluorescence signal on the focal plane can be received by the detector, excluding the interference of other layers, and obtaining high-resolution sample images, including the complete morphology data of the three-dimensional curvature distribution of the ribs and the phase of the asymmetric corrugations. From these image data, the rib height H, rib spacing S, rib inclination angle θ, and asymmetric corrugation period λ are extracted, where H ∈ [0.1 mm, 0.5 mm], S ∈ [0.5 mm, 2.0 mm], θ ∈ [10°, 45°], λ ∈ [1 mm, 8 mm]. Establish a comprehensive parameterized database, collect the distribution laws of microstructure parameters under different shark species and different growth stages, and obtain the corresponding hydrodynamic performance data through experimental measurements to establish a parameterized database.

[0045] Then, enter the stage of body surface area division and microstructure parameter matching (S200). Use computational fluid dynamics simulation technology to simulate the flow field around the body of a new energy vehicle, and obtain the parameters of the flow velocity and pressure at each point in the flow field. Based on the simulation results, extract the flow velocity distribution data on the body surface, and divide the body surface according to the predefined zoning criteria. The high-speed turbulent region is defined as the region where the flow velocity ≥ 35 m / s and the turbulence intensity ≥ 10%. The medium-speed transition region is the region where the flow velocity is 15 - 35 m / s and the absolute value of the pressure gradient ≤ 200 Pa / m. The low-speed separation region is the region where the flow velocity ≤ 15 m / s and there are flow separation eddies. Taking the front intake grille of the vehicle head, the outer edge of the rearview mirror, and the front side of the A-pillar as examples, it is found in the simulation that the flow velocity in these regions reaches the standard of the high-speed turbulent region during vehicle driving, and the turbulence intensity also meets the requirements. Therefore, they are divided into the high-speed turbulent region. The flow velocity and pressure gradient of the front part of the roof and the middle section of the door meet the criteria of the medium-speed transition region. The flow field characteristics behind the rear spoiler of the vehicle tail and inside the C-pillar meet the conditions of the low-speed separation region, thus completing the division of the body surface area. Next, perform microstructure parameter matching. For the high-speed turbulent region, call the microstructure parameters of the shark skin head region. This is because the shark head faces the impact of high-speed water flow during swimming, and its microstructure has evolved to adapt to this environment over a long time, which can effectively reduce resistance. According to the established biomimetic parameter mapping rules, the microstructure parameters of the high-speed turbulent region are H = 0.1 - 0.3 mm, S = 0.5 - 1.2 mm, θ = 30° - 45°, λ = 1.0 - 2.5 mm, and the angle between the rib direction and the oncoming flow direction is restricted to ≤ 10° to ensure that the microstructure can play the role of drag reduction to the greatest extent. For the low-speed separation region, call the microstructure parameters of the shark skin lateral line region. Since there is an air flow separation phenomenon in the low-speed separation region, and the microstructure in the shark skin lateral line region can stabilize the water flow in a relatively complex water flow environment, its parameters are H = 0.3 - 0.5 mm, S = 1.5 - 2.0 mm, θ = 10° - 20°, λ = 5 - 8 mm, and the rib direction deflects 15° - 30° according to the rotation direction of the separation vortex to adapt to the flow characteristics of the separation vortex and reduce the resistance caused by air flow separation. For the medium-speed transition region, adopt the microstructure parameters of the shark skin abdomen and lateral line region, with parameters H = 0.2 - 0.4 mm, S = 1.0 - 1.5 mm, λ = 2.5 - 4.0 mm, and dynamically adjust θ according to the positive and negative values of the local pressure gradient. When the pressure gradient is negative, θ increases by 5° - 8°, and when the pressure gradient is positive, θ decreases by 3° - 5°.

[0046] Subsequently, enter the stage of multi-objective optimization and non-uniform microstructure distribution network generation (S300), and establish a multi-objective optimization function The purpose of this function is to comprehensively optimize the drag coefficient and local pressure gradient. Among them, C d is the drag coefficient corresponding during the optimization process, and Cd0 is the reference drag coefficient without adding microstructures is the absolute value of the corresponding pressure gradient during the optimization process, is the absolute value of the maximum pressure gradient on the vehicle body surface. In this embodiment, α = 0.7 and β = 0.3 are weight coefficients. With H, S, θ, and λ as design variables, their constraint ranges are the same as the partition parameters described in S200. By adjusting the values of these design variables, the microstructure combination is continuously optimized to make the objective function F reach the optimum. During the optimization process, the values of the design variables are adjusted according to the results of the previous iteration in each iteration, gradually approaching the optimal solution. After optimizing the microstructure parameters, a non-uniform microstructure distribution network conformal to the vehicle body surface is generated through topology optimization technology. The vehicle body surface is discretized into quadrilateral meshes, and a microstructure density coefficient ρ is assigned to each mesh unit. ρ = 0 indicates no structure, and ρ = 1 indicates full structure. With minimizing the total energy consumption as the optimization goal, the equation is solved, where ρ e is the microstructure density coefficient of the e-th mesh unit, N is the total number of mesh units, U e is the unit aerodynamic dissipation energy, V e is the modulus of the flow velocity gradient, U e reflects the energy consumed by the airflow due to viscous action within the unit, and V e reflects the degree of change in the flow velocity within the unit. By minimizing the total energy consumption, it can be determined that arranging microstructures in the mesh units can optimize the overall aerodynamic performance, that is, finding the best distribution method of microstructures from the perspective of energy loss. During the solution process, ρ e is continuously adjusted until the convergence condition is met, and the optimal microstructure distribution network is obtained.

[0047] Secondly, enter the implementation stage of the hierarchical manufacturing design scheme (S400). Calculate the curvature of the vehicle body surface through CAD modeling, and perform hierarchical manufacturing design on the non-uniform microstructure distribution network according to the curvature. That is, for the high-curvature surface area: the vehicle body surface curvature ≥ 0.05 mm -1 and the area where the local flow velocity ≥ 25 m / s, the nanoimprint technology is used to ensure the topography accuracy. The high-curvature surface area is usually located in some key parts of the vehicle body, such as the corners of the vehicle body. The airflow velocity at these parts is fast and the direction changes greatly. The principle of the nanoimprint technology is to replicate the micro-nano structure onto the substrate material using a mold. In this embodiment, the mold with a specific shark skin microstructure pattern is brought into contact with the material of the high-curvature surface area of the vehicle body. By applying pressure and appropriate temperature or light and other conditions, the material undergoes plastic deformation or curing, so that the microstructure on the mold is accurately replicated onto the vehicle body, ensuring the high precision and integrity of the microstructure to meet the requirements of high curvature and high-speed airflow; for the low-curvature flat area: the vehicle body surface curvature ≤ 0.01 mm -1In the region where the absolute value of the pressure gradient ≤ 100 Pa / m, laser micro-texturing is used. The low-curvature planar region is relatively flat and the air flow is relatively stable. Laser micro-texturing utilizes the interaction between a high-energy-density laser beam and the material, causing physical changes such as melting and vaporization on the material surface, thereby forming specific microstructures on the material surface. In this embodiment, by precisely controlling the parameters of the laser power, pulse frequency, and scanning speed, shark skin microstructures are processed in the low-curvature planar region to achieve a drag reduction effect; for the transition connection region: the body surface curvature ∈ 0.01 - 0.05 mm -1 And in the region where there is a sudden change in the flow curvature, which is used to connect the high- and low-curvature region structures and suppress air flow separation. Laser micro-texturing is also used. The air flow state in the transition connection region is complex, with a sudden change in the flow curvature, which easily leads to air flow separation. Laser micro-texturing is used to achieve a smooth transition and effectively suppress air flow separation, improving the overall drag reduction performance.

[0048] Finally, it enters the wind tunnel experiment verification and parameter adjustment stage (S500). The wind tunnel experiment is carried out in a closed-circuit wind tunnel. The working principle of the closed-circuit wind tunnel is that the motor drives the fan to make the air flow circulate in a closed loop. The new energy vehicle model installed with the microstructures of the hierarchical manufacturing design scheme is placed in the wind tunnel test section in the actual driving attitude. During the experiment, the air forces received by the vehicle model at different air flow speeds are measured. A pressure sensor is used to measure the pressure distribution on the vehicle body surface, and a hot-wire anemometer is used to measure the flow field velocity distribution on the vehicle body. The pressure sensor senses the pressure on the vehicle body surface and converts the pressure signal into an electrical signal for measurement. The hot-wire anemometer is based on the principle of heat conduction. When an electric current passes through the hot wire, the hot wire will heat up, and the air flow passing over the hot wire will carry away the heat. The air flow velocity can be measured according to the change in the hot wire temperature. Based on these measurement data, the wind resistance coefficient Cd1 of the vehicle model is calculated. The wind resistance coefficient Cd1 measured in the wind tunnel experiment is compared with the wind resistance coefficient C in the computational fluid dynamics simulation data d for comparative analysis, and the reduction rate of the wind resistance coefficient is calculated When the reduction rate δ of the wind resistance coefficient ≤ 8%, it is determined as ineffective drag reduction, and the microstructure parameters in S300 need to be adjusted. We analyze the regions with air flow separation and large resistance based on the pressure distribution and flow field velocity distribution data obtained in the wind tunnel experiment, and specifically adjust parameters such as the rib height H, rib spacing S, rib inclination angle θ, and asymmetric corrugation period λ. After adjustment, re-perform the multi-objective optimization and non-uniform microstructure distribution network generation in S300, as well as subsequent hierarchical manufacturing and experimental verification until the reduction rate δ of the wind resistance coefficient > 8%, achieving the expected drag reduction effect.

[0049] In summary, through complete and systematic steps, this embodiment implements a drag reduction structure design method for new energy vehicle bodies based on the microstructures on shark skin. Starting from the acquisition of shark skin microstructure data, through the division of vehicle body surface areas, the optimization of microstructure parameters, hierarchical manufacturing design, and then to wind tunnel experiment verification and parameter adjustment, each link is closely connected, achieving precise design and optimization of the drag reduction structure for new energy vehicle bodies, effectively improving the drag reduction effect of new energy vehicles, and verifying the feasibility and effectiveness of this design method in enhancing the endurance and energy utilization efficiency of new energy vehicles.

[0050] Embodiment Two

[0051] This embodiment provides a drag reduction method for new energy vehicle bodies that combines biological bionics and engineering design. As Figure 1 shown, through systematic research on shark skin microstructures and matching with the characteristics of the vehicle body flow field, high-precision drag reduction structure design is achieved. The specific steps are as follows:

[0052] Shark Skin Microstructure Data Acquisition and Database Construction

[0053] Microstructure Morphology Scanning: Use three-dimensional scanning technology to perform high-precision scanning on shark skin samples to obtain surface geometric morphology data such as the three-dimensional curvature of riblets, the phase of asymmetric corrugations, etc.;

[0054] Key Parameter Extraction: Extract core parameters such as riblet height (H), spacing (S), inclination angle (θ), and asymmetric corrugation period (λ) from the scanned data, and record the parameter differences of different shark species and growth stages;

[0055] Database Establishment: Integrate the extracted parameters with the corresponding hydrodynamic performance data to establish a parametric database containing multi-dimensional information;

[0056] Vehicle Body Surface Flow Field Analysis and Region Division

[0057] Computational Fluid Dynamics Simulation: Perform flow field simulation on the new energy vehicle body to obtain flow velocity distribution, turbulence intensity, and pressure gradient data at different vehicle speeds;

[0058] Partition Criterion Definition:

[0059] High-Speed Turbulent Region: Regions where the flow velocity ≥ 35 m / s and the turbulence intensity ≥ 10% (such as the front intake grille of the vehicle head, the outer edge of the rearview mirror, the front side of the A-pillar);

[0060] Medium-Speed Transition Region: Regions where the flow velocity is 15 - 35 m / s and the absolute value of the pressure gradient ≤ 200 Pa / m (such as the front part of the roof, the middle section of the door);

[0061] Low-Speed Separation Region: Regions where the flow velocity ≤ 15 m / s and there are airflow separation eddies (such as behind the rear spoiler of the vehicle tail, the inner side of the C-pillar);

[0062] Body area division: The body surface is divided into the above three types of areas according to the criteria, and the boundaries and flow field characteristics of each area are clarified;

[0063] Microstructure parameter matching and preliminary design

[0064] Biological parameter mapping: Retrieve the microstructure parameters of the corresponding parts of shark skin from the database and match the flow field requirements of each area of the vehicle body;

[0065] Parameter dynamic adjustment:

[0066] High-speed area: Adopt a high rib height (H), small pitch (S), and large inclination angle (θ) to ensure that the angle between the rib direction and the oncoming flow is ≤10°;

[0067] Low-speed area: Adopt a low rib height, large pitch, and long corrugation period (λ), and deflect the rib direction by 15° - 30° according to the rotation direction of the separated vortex;

[0068] Medium-speed area: Dynamically adjust the inclination angle (θ) according to the local pressure gradient by linearly interpolating and fusing the parameters of the shark skin abdomen and lateral line;

[0069] Multi-objective optimization and non-uniform distribution design

[0070] Optimization objective setting: Aim to reduce the drag coefficient and balance the local pressure gradient, and iteratively adjust the microstructure parameters;

[0071] Topological optimization processing: Combine the body surface curvature to transform the microstructure parameters into a non-uniform distribution network conformal to the surface;

[0072] Graded manufacturing process design and implementation

[0073] Regional process division:

[0074] High-curvature surface area: Adopt nanoimprint technology to achieve microstructure transfer with an accuracy of 5μm and ensure the adaptability of complex surfaces;

[0075] Low-curvature plane area: Use laser micro-texturing processing to rapidly form and control the surface roughness;

[0076] Transition connection area: Adopt laser processing and optimize the rib arrangement to suppress air flow separation;

[0077] Wind tunnel experiment verification and parameter iteration

[0078] Experimental data acquisition: Place the processed vehicle body model in the wind tunnel, measure the drag coefficient, pressure distribution, and flow field velocity at different wind speeds, and obtain the actual drag reduction effect data;

[0079] Effect comparison and analysis: Compare the experimental data with the simulation results and calculate the drag coefficient reduction rate;

[0080] Iterative optimization: If the drag reduction effect does not meet the target, the rib height (H) and inclination angle (θ) in the high-speed area are adjusted specifically, and the microstructure distribution network is regenerated and manufactured until the aerodynamic performance target is met.

[0081] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A design method for the drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, The specific steps of this method are as follows: S100. Obtain the geometric morphology of the shark skin surface microstructure through three-dimensional scanning technology, extract key parameters, including rib height H, rib spacing S, rib inclination angle θ, and asymmetric corrugation period λ, and establish a parametric database; S200. Based on computational fluid dynamics simulation, divide the vehicle body surface into a high-speed turbulent region, a medium-speed transition region, and a low-speed separation region. Combine the flow velocity distribution characteristics of each region, and match the shark skin microstructure parameters from the parametric database; S300. Establish a multi-objective optimization function, with the drag coefficient and local pressure gradient as optimization objectives. After iteratively adjusting the microstructure parameters, generate a non-uniform microstructure distribution network conformal to the vehicle body surface through topology optimization technology; S400. For the non-uniform microstructure distribution network, design a hierarchical manufacturing design plan. The hierarchical manufacturing design plan divides the non-uniform microstructure distribution network into a high-curvature surface region, a low-curvature plane region, and a transition connection region, forming a dynamic slip boundary similar to the shark skin mucus layer; S500. Measure the drag coefficient of the microstructure vehicle body installed with the hierarchical manufacturing design plan in a wind tunnel experiment, compare the simulation data, and dynamically adjust the microstructure parameters in S300.

2. A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, In S100, the three-dimensional scanning technology uses a laser confocal microscope to scan the shark skin sample to obtain complete morphology data including the three-dimensional curvature distribution of the ribs and the phase of the asymmetric corrugations; The parametric database also includes the distribution rules of microstructure parameters and the corresponding hydrodynamic performance data for different shark species and different growth stages, where H ∈ [0.1 mm, 0.5 mm], S ∈ [0.5 mm, 2.0 mm], θ ∈ [10°, 45°], and λ ∈ [1 mm, 8 mm].

3. A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, The process of vehicle body surface zoning and microstructure parameter matching in S200 is as follows: Based on the computational fluid dynamics simulation results, extract the flow velocity distribution data on the vehicle body surface and define the zoning criteria: High-speed turbulent region: The region where the flow velocity ≥ 35 m / s and the turbulence intensity ≥ 10%; Medium-speed transition region: The region where the flow velocity is 15 - 35 m / s and the absolute value of the pressure gradient ≤ 200 Pa / m; Low-speed separation region: The region where the flow velocity ≤ 15 m / s and there are flow separation eddies; According to the zoning criteria, divide the front grille of the vehicle head, the outer edge of the rearview mirror, and the front side of the A-pillar into the high-speed turbulent region, the front part of the roof and the middle section of the door into the medium-speed transition region, and the area behind the rear spoiler of the vehicle tail and the inner side of the C-pillar into the low-speed separation region.

4. A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, In S200, during the process of matching the shark skin microstructure parameters, by establishing the bionic parameter mapping rules for each region: High-speed turbulent region: Call the parameters of the shark skin head region, that is, H = 0.1 - 0.3 mm, S = 0.5 - 1.2 mm, θ = 30° - 45°, λ = 1.0 - 2.5 mm, and limit the angle between the rib direction and the oncoming flow direction ≤ 10°; Low-speed separation region: Call the parameters of the shark skin lateral line region, that is, H = 0.3 - 0.5 mm, S = 1.5 - 2.0 mm, θ = 10° - 20°, λ = 5 - 8 mm, and deflect the rib direction by 15° - 30° according to the rotation direction of the separation vortex; Medium-speed transition zone: Adopt the parameters of the sharkskin belly and the lateral line area, i.e., H = 0.2 - 0.4 mm, S = 1.0 - 1.5 mm, λ = 2.5 - 4.0 mm, and dynamically adjust θ according to the positive and negative values of the local pressure gradient: When the pressure gradient is negative, θ increases by 5° - 8°; When the pressure gradient is positive, θ decreases by 3° - 5°.

5. A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, The S300 multi-objective optimization function where C d is the corresponding drag coefficient during the optimization process, Cd0 is the baseline drag coefficient without adding microstructures, ▽P is the absolute value of the pressure gradient during the optimization process, α = 0.7 and β = 0.3 are weight coefficients, and |▽P| max = 200 Pa / m is the absolute value of the maximum pressure gradient on the vehicle body surface. With H, S, θ, and λ as design variables, the constraint ranges are the same as the partition parameters described in S200. After determining the design variables, the micro-structure combination is optimized by adjusting the values of the partition parameters.

6. A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, The process of generating a non-uniform microstructure distribution network conformal to the body surface by topology optimization technology in the S300 is as follows: After optimizing the microstructure parameters, discretize the body surface into quadrilateral meshes, and assign a microstructure density coefficient ρ to each mesh element, where ρ = 0 means no structure and ρ = 1 means full structure; Taking the minimization of the total energy consumption as the optimization goal, solve the equation where ρ e is the microstructure density coefficient of the e-th grid cell, N is the total number of grid cells, U e is the aerodynamic dissipation energy of the cell, V e is the modulus of the flow velocity gradient. By minimizing the total energy consumption, determine the arrangement of the microstructures in the grid cells to optimize the overall aerodynamic performance, that is, find the optimal distribution of the microstructures from the perspective of energy loss.

7. A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, The S400 calculates the curvature of the body surface through CAD modeling and conducts hierarchical manufacturing design on the non-uniform microstructure distribution network according to the curvature: High-curvature surface area: the curvature of the vehicle body surface ≥ 0.05 mm -1 and the area where the local flow velocity ≥ 25 m / s, the nanoimprint technology is used to ensure the topography accuracy; Low-curvature planar region: the curvature of the vehicle body surface ≤ 0.01 mm -1 and the region with the absolute value of the pressure gradient ≤ 100 Pa / m is processed by laser micro-texturing; Transition connection area: the curvature of the vehicle body surface ∈ 0.01 - 0.05 mm -1 And there is an area where the flow curvature changes abruptly, which is used to connect the structures of the high and low curvature areas and suppress the airflow separation, and laser micro-texturing processing is adopted.

8. A design method for a drag reduction structure of a new energy vehicle body based on the surface microstructure of shark skin, characterized in that, The S500 wind tunnel test was conducted in a closed recirculation wind tunnel. A new energy vehicle model equipped with a hierarchical manufacturing design microstructure was placed in the wind tunnel test section according to its actual driving posture. The air force acting on the vehicle model at different airflow speeds was measured. The pressure distribution on the vehicle body surface was measured using a pressure sensor, and the flow field velocity distribution on the vehicle body was measured using a hot wire anemometer. The drag coefficient obtained from the wind tunnel test was compared and analyzed with computational fluid dynamics simulation data to calculate the reduction rate of the drag coefficient. When the drag coefficient reduction rate δ is ≤ 8%, it is determined that the drag reduction is ineffective, and the S300 microstructure parameters are adjusted until the drag coefficient reduction rate δ is greater than 8%.

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