A multidisciplinary integrated high-altitude paraglider automatic optimization design method

Abstract

A multidisciplinary approach to the automated optimization design of high-flying paragliders integrates automated and modularized functions, including geometric modeling, mesh modeling, aerodynamic calculation, and airfoil shape optimization. These modules are integrated through the Isight platform to establish a multidisciplinary optimization design framework. This method decouples the issue of improving the aerodynamic performance of three-dimensional paragliders and automatically optimizes the airfoil based on parameters such as the canopy structure and material. Each module automatically reads previous result files and runs in a loop, requiring no human intervention, to automatically output the optimized airfoil with the highest lift-to-drag ratio. This method is highly efficient, utilizes a functional airfoil design, offers high precision, and facilitates automated processing and production. This method holds significant implications for the optimized design of high-flying paragliders.

Description

Technical Field

[0001] The invention belongs to the field of airborne airdrop and pneumatic deceleration equipment, and in particular relates to the automatic optimization design of a parafoil. Background Art

[0002] Under certain airflow conditions, the parafoil airfoil directly affects the flow field and aerodynamic performance of the ramjet parafoil, and determines the gliding ability of the parafoil.

[0003] Unlike the basic airfoil of a traditional wing, the parafoil airfoil is designed with a cutout at the leading edge to facilitate canopy inflation. The cutout destroys the streamline of the airfoil's leading edge, resulting in a significant difference in the aerodynamic performance of the parafoil airfoil from the basic airfoil. Traditional parafoil designs mostly obtain the aerodynamic performance of the basic airfoil through wind tunnel tests or numerical calculations, and then manually modify the airfoil shape on this basis to obtain the aerodynamically optimal basic airfoil. Finally, the parafoil airfoil is obtained by cutting and modifying the basic airfoil, and then the canopy design is carried out. However, this design process requires a large number of iterative modifications to the basic airfoil shape, and requires repeated tests or modeling calculations based on the experience of professionals, resulting in poor repeatability and low design efficiency.

[0004] In recent years, some researchers have used the Isight platform to optimize the geometry of parafoil airfoils, improving the aerodynamic performance of notched airfoils. However, due to the influence of parafoil structural features such as the low aspect ratio and canopy undershoot on parafoil gliding performance, the maximum glide ratio of a parafoil is not simply proportional to the lift-to-drag ratio of the airfoil. Therefore, optimizing the notched airfoil alone cannot yield the optimal parafoil airfoil for high-speed gliding. Summary of the Invention

[0005] The purpose of the present invention is to solve the difficult problem of coupling the numerical analysis of the aerodynamic performance of complex three-dimensional parafoils with the nonlinear optimization of the airfoil through efficient flow field numerical calculation and theoretical modeling, establish a multidisciplinary integrated parafoil airfoil automatic optimization design framework, and automatically obtain a high-speed gliding parafoil airfoil that meets the requirements of parafoil structure, materials, etc.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A multidisciplinary high-glide paraglider automatic optimization design method integrates multidisciplinary modules and automatically optimizes and outputs a paraglider airfoil that meets high-glide performance requirements, including the following steps:

[0008] Step 1. Establish an automatic geometric modeling module, read the airfoil shape parameter file, and automatically establish the parafoil airfoil geometry model;

[0009] Step 2. Establish an automatic mesh modeling module to automatically establish the flow field of the parafoil airfoil and divide the mesh;

[0010] Step 3. Establish an automatic calculation module for the aerodynamic characteristics of the parafoil, input the structural parameters of the parafoil canopy, automatically calculate the airfoil flow field, and output the maximum lift-to-drag ratio of the canopy. Specifically, it includes: Step 3.1 Read the grid model, carry out computational fluid dynamics analysis, complete the flow field boundary conditions and solution settings, calculate the steady-state flow field of the parafoil airfoil in a certain flight angle of attack range, and output the law of change of the aerodynamic coefficient of the parafoil airfoil with the angle of attack C L,2D (α),C D,2D (α). Step 3.2: Based on the three-dimensional parafoil canopy aerodynamic characteristics calculation model, the three-dimensional parafoil canopy aerodynamic characteristics at different angles of attack α are obtained, thereby determining the maximum lift-to-drag ratio that the parafoil can achieve. Step 3.3: Save the flow field calculation setting file as a batch file, encapsulate it with the three-dimensional parafoil canopy aerodynamic characteristics calculation program, and automatically calculate the maximum lift-to-drag ratio of the parafoil canopy.

[0011] Step 4. Determine whether the lift-to-drag ratio of the parafoil canopy has converged stably after the airfoil optimization. If so, stop the operation and output the parafoil airfoil parameterization function and the maximum lift-to-drag ratio of the parafoil. Otherwise, use the Isight multi-island genetic algorithm to establish an airfoil shape optimization module. Based on the aerodynamic characteristics calculation results, with the goal of improving the lift-to-drag ratio of the parafoil canopy, automatically optimize the airfoil shape to obtain a new parameterized airfoil function coefficient, and return to step 1 to re-model the geometry.

[0012] Step 5. Integrate the parafoil airfoil automatic geometric modeling module, automatic mesh modeling module, parafoil aerodynamic characteristics automatic calculation module, and airfoil shape optimization module to establish a multidisciplinary optimization design framework. Each module automatically reads the previous result file, runs in a loop, and automatically outputs the optimized airfoil corresponding to the canopy with the maximum lift-to-drag ratio.

[0013] As a preferred embodiment, step 1 specifically includes: step 1.1 selecting the initial parafoil airfoil, establishing the coordinates of the parafoil airfoil based on the body axis coordinate system, with the upper wing surface cut point as O, the chord as the OX axis, the lower wing surface cut point as B, and the airfoil trailing edge point as C (1, 0); step 1.2 using the method of linear superposition of analytical functions, by programming coordinate fitting, respectively establish the parameterized functions y of the upper and lower wing surfaces u (x), y d (x); Step 1.3 fixes the coordinate positions of the airfoil feature points O, B, and C, uses the coefficients of the shape functions of the upper and lower wing surface parameterization functions as control variables, jointly represents the initial airfoil shape, and outputs the shape control parameters as a data file; Step 1.4 reads the optimized airfoil geometric parameter data file, and automatically establishes the parafoil airfoil geometric model according to the positions of the feature points and the coefficients of the shape functions.

[0014] Preferably, in step 1.2, the upper and lower surfaces of the airfoil are functionally represented by the following formula: Among them, N and c k Respectively represent the number and coefficients of type functions, fk (x) is the selected type function: In the formula The lower surface of the airfoil can also be made of a straight wing surface to improve flight stability, and the function is y d (x) = c d1 x+c d2 .

[0015] Preferably, step 2 specifically includes: step 2.1 reading the airfoil geometric model, and establishing a C-type flow field according to the airfoil chord length; step 2.2 dividing the flow field into blocks, and establishing a C-type block based on the airfoil shape; determining the grid size according to the airfoil chord length and the incoming flow conditions, automatically generating a structured grid and outputting a grid model file; step 2.3 saving the grid division process as a batch file to realize automatic modeling of the flow field and grid of the airfoil.

[0016] As a preference, in step 3.2, according to the lift line theory, the lift coefficient of the straight wing is given by Calculate, where represents the slope of the lift line, Δα=α-α0 represents the difference from the zero lift angle of attack, λ is the aspect ratio, and m is a constant. Since the aerodynamic performance of the parafoil is greatly affected by the anhedral angle and the small aspect ratio structural characteristics, the parafoil lift coefficient can be expressed as C L,3D =C Lβ +C Lλ , where C Lβ The effect of the anhedral angle on the lift coefficient, C Lλ The effect of the canopy's small aspect ratio on aerodynamic performance is expressed as: D,3D =C D,2D +C D,S , where C D,2D and C D,S They represent the pressure difference drag caused by the notched airfoil and other drags caused by the canopy; finally, the lift-to-drag ratio is obtained

[0017] As a preferred method, the parafoil lift coefficient is C Lβ Specifically C Lβ =kΔαcos 2 β, where k is the slope of the parafoil lift line, expressed as Calculation, β is the anhedral angle of the parafoil; C Lλ Specifically: C Lλ =(1.67-0.67λ)sinΔαsin2Δα, which represents the influence of small aspect ratio of canopy on aerodynamic performance.

[0018] As a preferred option, according to the working principle of the parafoil, the canopy resistance can be decomposed into C D,S =C D,Q +C D,M +CD,Y , where C D,Q 、C D,M and C D,Y They represent the leading edge notch flow resistance, the friction resistance caused by the irregularity of the airfoil and the roughness of the fabric, and the induced drag at both ends of the parafoil. The notch flow resistance calculation formula is C D,Q =qh / c, where q is a constant and h / c is the relative height of the cutout. The induced drag can be calculated based on the aspect ratio. The specific formula is:

[0019] Preferably, step 4 outputs the maximum canopy lift-to-drag ratio corresponding to the airfoil in each iteration process, and if the fluctuation of the iteration results for five consecutive times is no more than 5%, it is considered that the iteration has converged.

[0020] As a preference, in the genetic algorithm optimization module in step 4, the optimization variable is the parafoil airfoil function coefficient {c k}, with the three-dimensional canopy lift-drag ratio λ 3D,max =max{λ 3D (α)} reaches the maximum as the objective function, and the constraint condition is λ 3D,max ≥λ 3D,max,0 , where λ 3D,max,0 is the maximum parafoil canopy lift-to-drag ratio corresponding to the initial airfoil.

[0021] The multidisciplinary integrated high-speed paraglider automatic optimization design method according to the present invention has the following beneficial effects:

[0022] 1. This invention decouples the complex three-dimensional parafoil aerodynamic lift problem into an airfoil geometry optimization problem through a parafoil aerodynamic characteristic model. This multidisciplinary optimization design framework integrates multiple modules, including parafoil geometry modeling, flow field mesh modeling, flow field calculation and analysis, and shape optimization. This not only considers the impact of parafoil structural characteristics such as cutouts, undercuts, and aspect ratio on aerodynamic performance, but also avoids frequent manual data updates within and between modules. The entire optimization design process automatically cycles, greatly improving optimization efficiency.

[0023] 2. Based on the intelligent optimization algorithm, an appearance optimization module was established to realize the automated parametric optimization design of the parafoil airfoil. On the one hand, it does not rely on the design experience of technical personnel, improves design efficiency and reduces manual errors; on the other hand, it directly obtains the function model of the airfoil, which facilitates intelligent processing and manufacturing, and reduces processing errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an optimization flow chart of an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the airfoil coordinates and parameterized function model of an embodiment of the present invention.

[0026] Figure 3 A schematic diagram of an airfoil flow field, a mesh model, and mesh details according to an embodiment of the present invention;

[0027] Figure 4 This is a lift-to-drag ratio iteration result diagram for one embodiment of the present invention;

[0028] Figure 5 A comparison diagram of the optimized front and rear airfoil geometries of an embodiment of the present invention;

[0029] Figure 6 A comparison diagram of pressure distribution of the optimized airfoil before and after an embodiment of the present invention;

[0030] Figure 7 1 is a comparison diagram of velocity vector distribution before and after optimization according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the library of applicable embodiments of the present invention. All other embodiments derived by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] The present invention discloses a multidisciplinary fusion airfoil automatic optimization design method, such as Figure 1 As shown, geometric modeling is performed by a self-programmed program to obtain a parameterized function model of the parafoil; the flow field grid modeling is automatically performed on the airfoil geometric model to obtain the flow field calculation model of the airfoil; the airfoil is subjected to computational fluid dynamics analysis using flow field analysis software to obtain the aerodynamic characteristic data of the airfoil; the maximum lift-to-drag ratio of the three-dimensional parafoil canopy is determined according to the aerodynamic characteristic calculation model of the three-dimensional parafoil canopy; an intelligent optimization algorithm is selected to perform parameter optimization on the geometric shape of the parafoil airfoil according to the aerodynamic characteristics of the three-dimensional parafoil; a multidisciplinary optimization design integrated framework is established to realize the automatic cycle operation of the entire optimization process, iterative screening until the optimal aerodynamic performance conditions are reached, and the airfoil shape and flow field results under the optimal aerodynamic performance conditions are output. The method of the present invention integrates airfoil modeling, flow field modeling, flow field calculation analysis, and genetic algorithm optimization software through the multidisciplinary optimization design framework software, realizes accurate analysis of various disciplines and automatic operation of the entire optimization cycle process, solves the difficult problem of flow field analysis and calculation of complex three-dimensional parafoil and multidisciplinary multi-objective coupled optimization, and can be used in the optimization design problems of various aircraft to improve design efficiency.

[0033] Combine Figures 2 to 7 Taking the shape optimization of the Clark-Y parafoil as an example, the parafoil span b is 8m, the chord length c is 4m, and the aspect ratio λ is 2, the implementation steps of the present invention are specifically described:

[0034] Step 1. Establish an automatic geometric modeling module, read the airfoil shape parameter file, and automatically establish the parametric geometric model of the parafoil airfoil. Specifically include:

[0035] Step 1.1 Select Clark-Y notch airfoil as the initial parafoil airfoil, and establish the coordinate description of the parafoil airfoil based on the body axis coordinate system. The upper wing surface notch point is O(0,0), and the lower wing surface notch point is B(0.046,-

[0036] 0.045), the trailing edge point of the airfoil is C(1,0), and the specific coordinates are shown in Table 1:

[0037] Table 1 Clark-Y notch airfoil coordinate description

[0038]

[0039]

[0040] Step 1.2 uses the method of linear superposition of analytical functions to establish the parameterized function y of the upper wing surface u (x), the formula is:

[0041] y u (x)=c1f1(x)+c2f2(x)+c3f3(x)+c4f4(x)+c5f5(x)+c6f6(x)+c7f7(x);

[0042] where f k (x) is the airfoil function, and the formula is In the formula {c k} is the shape function coefficient of the upper wing function

[0043] By using Matlab programming to fit the coordinates, the initial values ​​of the coefficients of the type function are determined:

[0044] c1=0.0032, c2=0.0425, c3=0.0209, c4=0.0346, c5=0.0171, c6=0.0249, c7=0.0147

[0045] In order to ensure the flight stability of the parafoil, the lower wing surface adopts a straight wing surface, and the lower wing surface function y is obtained by programming fitting. d (x) = 0.0472x - 0.0472.

[0046] The original airfoil coordinates and parameterized model represent the airfoil shape as follows Figure 2 As shown in Figure 2, the two are basically consistent, which shows the accuracy of the parameterized model.

[0047] Step 1.3 Fix the coordinate positions of the airfoil feature points O, B, and C. The coefficients of the various types of the airfoil parameterization function are {c k}control variables, which together represent the initial airfoil shape, and output the shape control parameters as a data file.

[0048] Step 1.4 uses the batch file to read the optimized airfoil geometry parameter data file, and automatically establishes the notch airfoil geometry model in ICEM according to the position of the characteristic points and the coefficients of the characteristic function. The initial parafoil geometry is as follows: Figure 2 The center blank area is shown.

[0049] Step 2. Establish an automatic mesh modeling module to automatically establish the airfoil flow field and divide the mesh. Specifically include:

[0050] Step 2.1: With the cutout point on the upper surface of the notched airfoil as the geometric center, establish a C-shaped flow field based on the airfoil chord length c, where the semicircle diameter is 10c and the rectangular part is 10c × 12c;

[0051] Step 2.2 divides the flow field into blocks and establishes a C-type block based on the airfoil shape. The grid size is determined according to the airfoil chord length, incoming flow conditions, etc. The number of grids is about 78,000, and a C-type structured grid is generated. The initial airfoil calculation flow field and grid are as follows Figure 3 As shown, the grid file is output at the same time.

[0052] Step 2.3 saves the meshing process as an ICEM script file, which can automatically model the flow field and mesh of the airfoil.

[0053] Step 3: Establish an automatic calculation module for the aerodynamic characteristics of the parafoil, automatically calculate the airfoil flow field, and output the maximum lift-to-drag ratio of the parafoil. Specifically, it includes:

[0054] Step 3.1: Read the grid file output by ICEM and use the commercial software Fluent to establish a computational model for the notched airfoil flow field and conduct computational fluid dynamics analysis. The incoming flow velocity v = 12 m / s at the infinity of the airfoil, and the outlet is a free outlet; the turbulence model uses the Spalart-Allmaras single equation model, and the equations are discretized using a second-order upwind scheme. The airfoil surface adopts a no-slip wall condition. Calculate the steady-state flow field of the parafoil airfoil in the flight angle range of -4° to 12°, and automatically output the aerodynamic characteristics C of the two-dimensional parafoil airfoil as the angle of attack α changes. L,2D (α),C D,2D (α).

[0055] Step 3.2 calculates lift and drag based on the three-dimensional parafoil canopy aerodynamic characteristics calculation model.

[0056] The lift coefficient formula is C L =C Lβ+C Lλ ,

[0057] Among them C Lβ =kΔαcos 2 β, Δα=α-α0 represents the difference from the zero lift angle of attack, β is the anhedral angle of the parafoil, and is given by Calculation, in this embodiment, the equivalent length of the parachute rope is L sh =4.8m, and β is calculated to be 23.8°.

[0058] The lift line slope k of the parafoil is determined according to the lift line slope of the two-dimensional airfoil and the canopy aspect ratio. Where m is the non-elliptical correction coefficient, and the minimum aspect ratio is 0.046.

[0059] C Lλ =(1.67-0.67λ)sinΔαsin2Δα, which represents the influence of small aspect ratio of canopy on aerodynamic performance.

[0060] The drag coefficient calculation formula is C D,3D =C D,2D +C D,S ,

[0061] Among them C D,2D , and C D,S They represent the pressure difference drag caused by the notched airfoil and other drags caused by the canopy respectively;

[0062] According to the working principle of parafoil, the canopy resistance can be decomposed into three parts, namely C D,S =C D,Q +C D,M +C D,Y , where C D,Q 、C D,M and C D,Y They represent the flow resistance of the leading edge cutout, the friction resistance caused by the irregularity of the airfoil and the roughness of the fabric, and the induced drag at both ends of the parafoil.

[0063] The calculation formula of the cut flow resistance is based on C D,Q = qh / c, q is a constant, which is 0.3 according to engineering experience, and the relative height of the cut is h / c = 0.067, so C D,Q =0.02.

[0064] The common fabric material of parafoil is brocade silk, and the friction resistance coefficient can be C D,M =0.004. The induced drag coefficient of the airfoil is based on calculate.

[0065] According to the above formula, Matlab programming is used to establish a three-dimensional parafoil canopy aerodynamic characteristic model, and the aerodynamic coefficient C under different aerodynamic attack angles is automatically calculated. L,3D (α),CD,3D (α), and output the parafoil lift-drag ratio

[0066] Step 3.3 saves the flow field calculation setting file as a Fluent log file and encapsulates it with the three-dimensional canopy aerodynamic characteristics calculation program. The grid file obtained in the second step can be used to automatically calculate the aerodynamic characteristics of the two-dimensional airfoil and three-dimensional canopy, and automatically output the maximum lift-to-drag ratio of the parafoil.

[0067] Step 4. Determine whether the lift-to-drag ratio of the parafoil canopy has converged stably after the airfoil optimization. If it has converged, stop the operation and output the parafoil airfoil parameterization function and the maximum lift-to-drag ratio of the parafoil. Otherwise, use the Isight multi-island genetic algorithm to establish the airfoil shape optimization module. The genetic algorithm parameters are: sub-species population size is 5, the number of sub-population individuals is 6, the number of iterations is 200, the hybridization probability is 0.9, the mutation probability is 0.01, the migration rate is 0.3, and the migration interval is 4. Based on the aerodynamic characteristics calculation results, the lift-to-drag ratio λ is taken as the maximum value. 3D (α) is maximized as the goal, and constraints are set: after optimization, the lift coefficient increases and the drag coefficient decreases, that is, C L,3D >C L,3D0 ,C D,3D <C D,3D0 , automatically get the new parameterized airfoil function coefficient {c k}. Return to step 1.4 to automatically re-model the geometry.

[0068] Step 5. Integrate the parafoil airfoil automatic geometric modeling module, automatic mesh modeling module, parafoil aerodynamic characteristics automatic calculation module, and airfoil shape optimization module to establish a multidisciplinary optimization design framework. Each module automatically reads the previous result file, runs in a loop, and automatically outputs the optimized airfoil corresponding to the canopy with the maximum lift-to-drag ratio.

[0069] During the optimization process, the aerodynamic characteristics of the optimized iterative airfoil can be output in real time. After 200 iterations, the lift-to-drag ratio of the parafoil obtained in the optimization process changes as follows: Figure 4 ,It can be seen from the figure that the lift-to-drag ratio of the parafoil increases significantly with the increase of optimization times and finally reaches stability.

[0070] The airfoil geometry modeling module in step 1 automatically outputs the optimized airfoil geometry. After optimization, the airfoil shape changes as follows: Figure 5 ,It can be seen that after optimization, the maximum thickness of the leading edge of the airfoil is slightly increased, and the camber of the airfoil is significantly improved, which is beneficial to improving the lift of the airfoil.

[0071] The airfoil aerodynamic performance after optimization is automatically output by the airfoil aerodynamic characteristic calculation module in step 3. Figure 6 and Figure 7Specifically, the pressure and velocity vector distributions of the airfoil before and after optimization are shown. The pressure diagrams before and after optimization show that the pressure on the lower surface of the optimized airfoil remains essentially unchanged, while the pressure on the upper surface decreases. Correspondingly, the velocity vector diagram shows that the flow velocity on the upper surface of the optimized airfoil increases, resulting in increased lift. Flow field results demonstrate that the optimized airfoil can achieve improved aerodynamic performance. The lift-to-drag ratio of the parafoil, as calculated in the airfoil aerodynamic characteristics calculation module, increases from 3.94 to 4.18, a 6.1% improvement, effectively increasing the glide distance of the parafoil airdrop system.

[0072] It should be noted that the present invention integrates the above optimization design steps and modules, and the entire optimization process runs automatically, which can realize the automatic optimization design of the high-speed paraglider.

[0073] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A multidisciplinary high-glide paraglider automatic optimization design method integrates multidisciplinary modules and automatically optimizes and outputs a paraglider airfoil that meets high glide performance requirements, characterized by: The following steps are involved: Step 1. Establish an automatic geometric modeling module, read the airfoil shape parameter file, and automatically establish the parafoil airfoil geometry model; Step 2. Create an automatic mesh modeling module to automatically create the flow field of the parafoil airfoil and divide the mesh; Step 3. Establish a parafoil aerodynamic characteristics automatic calculation module, input the parafoil canopy structural parameters, automatically calculate the airfoil flow field, and output the canopy maximum lift-to-drag ratio, specifically including: Step 3.1 Read the grid model, conduct computational fluid dynamics analysis, complete the flow field boundary conditions and solution settings, calculate the steady-state flow field of the parafoil airfoil at a certain flight angle of attack, and output the law of change of the aerodynamic coefficient of the parafoil airfoil with the angle of attack , ; Step 3.2 Obtain different angles of attack based on the aerodynamic characteristics calculation model of the three-dimensional parafoil canopy The three-dimensional aerodynamic characteristics of the canopy under the wing can be determined to determine the maximum lift-to-drag ratio that the parafoil can achieve; Step 3.3 Save the flow field calculation setting file as a batch file, encapsulate it with the three-dimensional canopy aerodynamic characteristics calculation program, and automatically calculate the maximum lift-to-drag ratio of the parafoil canopy; Step 4. Determine whether the lift-to-drag ratio of the parafoil canopy has converged stably after the airfoil optimization. If so, stop the process and output the parafoil airfoil parameterization function and the parafoil's maximum lift-to-drag ratio. Otherwise, use the Isight multi-island genetic algorithm to establish an airfoil shape optimization module. Based on the aerodynamic characteristics calculation results, with the goal of improving the parafoil canopy's lift-to-drag ratio, automatically optimize the airfoil shape to obtain new parameterized airfoil function coefficients, and return to step 1 to re-model the geometry. Step 5. Integrate the parafoil airfoil automatic geometry modeling module, automatic mesh modeling module, parafoil aerodynamic characteristics automatic calculation module, and airfoil shape optimization module to establish a multidisciplinary optimization design framework. Each module automatically reads the previous result file, runs in a loop, and automatically outputs the optimized airfoil corresponding to the canopy with the maximum lift-to-drag ratio.

2. The multidisciplinary high-speed paraglider automatic optimization design method according to claim 1 is characterized in that: Step 1 specifically includes: Step 1.1 Select the initial parafoil airfoil and establish its coordinates based on the body axis coordinate system. The upper wing cut point is O, the chord is the OX axis, the lower wing cut point is B, and the trailing edge of the airfoil is C(1,0). Step 1.2: Use the method of linear superposition of analytical functions to establish the parameterized functions of the upper and lower wing surfaces through programming coordinate fitting. 、 ; Step 1.3: Fix the coordinate positions of the airfoil feature points O, B, and C, use the coefficients of the upper and lower airfoil parameterization functions as control variables, and jointly represent the initial airfoil shape. Output the shape control parameters as a data file. Step 1.4: Read the optimized airfoil geometry parameter data file and automatically establish the parafoil airfoil geometry model based on the positions of the feature points and the coefficients of the shape function.

3. The multidisciplinary high-speed paraglider automatic optimization design method according to claim 2 is characterized in that: In step 1.2, the upper and lower surfaces of the airfoil are functionally represented using the following formula: ， in, and Respectively represent the number and coefficients of type functions, The selected type function is: ， In the formula ; or the lower surface of the airfoil adopts a straight wing surface to improve flight stability, the function is .

4. The multidisciplinary high-speed paraglider automatic optimization design method according to claim 3 is characterized in that: Step 2 specifically includes: Step 2.1 Read the airfoil geometry model and establish the C-type flow field based on the airfoil chord length; Step 2.2: Divide the flow field into blocks and establish a C-shaped block based on the airfoil shape; determine the grid size based on the airfoil chord length and incoming flow conditions, automatically generate a structured grid, and output the grid model file; Step 2.3 Save the meshing process as a batch file to automatically model the flow field and mesh of the airfoil.

5. The multidisciplinary high-altitude paraglider automatic optimization design method according to any one of claims 1 to 4, characterized in that: According to the lift line theory in step 3.2, the lift coefficient of the straight wing is given by Calculate, where represents the slope of the lift line, represents the difference from the zero lift angle of attack, is the aspect ratio, is a constant; Since the aerodynamic performance of the parafoil is greatly affected by the structural characteristics of the anhedral angle and small aspect ratio, the lift coefficient of the parafoil can be expressed as , where represents the effect of anhedral angle on lift coefficient, It shows the effect of small aspect ratio of canopy on aerodynamic performance; The drag coefficient of the parafoil can be expressed as ,in and They represent the pressure difference drag caused by the notched airfoil and other drags caused by the canopy respectively; Finally, the lift-to-drag ratio .

6. The multidisciplinary high-speed paraglider automatic optimization design method according to claim 5 is characterized in that: The lift coefficient of the parafoil is Specifically ,in is the slope of the parafoil lift line, expressed as , is the anhedral angle of the parafoil; Specifically: , which represents the influence of the small aspect ratio of the canopy on the aerodynamic performance.

7. The multidisciplinary high-speed paraglider automatic optimization design method according to claim 6 is characterized in that: According to the working principle of parafoil, the canopy resistance can be decomposed into ,in 、 and They represent the leading edge notch flow resistance, the friction resistance caused by the irregularity of the airfoil and the roughness of the fabric, and the induced drag at both ends of the parafoil. The calculation formula for the notch flow resistance is: ,in is a constant, is the relative height of the cutout; the induced drag can be calculated based on the aspect ratio, the specific formula is .

8. The multidisciplinary high-speed paraglider automatic optimization design method according to claim 7 is characterized in that: Step 4 outputs the maximum canopy lift-to-drag ratio corresponding to the airfoil in each iteration process. If the fluctuation of the results for five consecutive iterations is no more than 5%, the iteration is considered to have converged.

9. The multidisciplinary high-speed paraglider automatic optimization design method according to claim 8 is characterized in that: In the airfoil shape optimization module in step 4, the optimization variable is the parafoil airfoil function coefficient , based on the three-dimensional canopy lift-drag ratio The objective function is to maximize the value, and the constraints are ,in is the maximum parafoil canopy lift-to-drag ratio corresponding to the initial airfoil.

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