Airfoil profile generation method for fixed-wing unmanned aerial vehicle
By selecting multiple airfoils from the existing airfoil library and performing coordinate file processing and interpolation processing, new airfoil curves are generated, which solves the problem of traditional airfoil generation methods imposing geometric constraints in the design space, and achieves greater airfoil search space and design diversity.
Patent Information
- Application Number
- CN202311391043.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-25
- Publication Date
- 2025-04-25
AI Technical Summary
Traditional airfoil generation methods impose geometric constraints in the design space, limiting the flexibility and diversity of airfoils and unable to effectively parameterize complex airfoil shapes.
By selecting multiple airfoils as initial airfoils from the existing airfoil library, exporting and processing their coordinate files, the airfoil curves are expanded and interpolated, and a new airfoil curve is generated, allowing negative weighting for further optimization.
The airfoil search space has been expanded, the novelty and diversity of design has been improved, and the search space for airfoil optimization has been liberated, and designer bias has been eliminated.
Smart Images
Figure CN119885410A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of fixed-wing unmanned aerial vehicle design, in particular to an airfoil parameterization method. Background Art
[0002] With the rapid development of UAV technology, people have higher and higher requirements for UAV performance. The traditional method of selecting airfoils from the airfoil library can no longer meet people's pursuit of performance and personalized needs. Therefore, in order to meet users' customization needs and flight requirements, customizing exclusive airfoils has become a future development trend. In the process of customizing exclusive airfoils, the most basic step is to parameterize the airfoil. By changing a small number of parameters, the shape of the airfoil can be flexibly controlled. This parameterization method can not only improve design efficiency, but also accurately meet user needs.
[0003] There are many methods for airfoil parameterization, which can be roughly divided into three categories: shape function method, polynomial method, and spline method. The shape function method includes Hicks-Henne type function, Wagner type function and other methods; the polynomial method includes class function / shape function parameterization method (CST), PARSEC and other methods; the spline method includes Bezier curve, B-spline and other methods.
[0004] Most of the above airfoil parameterization methods have some limitations. These methods impose geometric constraints in the design space and are affected by the designer's personal bias, which limits the design innovation and only allows small local changes. In addition, these methods often cannot effectively parameterize complex airfoil shapes, thus limiting the flexibility and diversity of airfoils. Summary of the invention
[0005] The present invention aims to provide a new method for generating airfoils for fixed-wing UAVs, so as to solve the problem that the search space for airfoil design is small and the complex airfoil shape cannot be effectively parameterized in the traditional airfoil generation method.
[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for generating a fixed-wing UAV airfoil, characterized in that it comprises the following steps:
[0007] (1) Select multiple airfoils from the existing airfoil library as initial airfoils, and export the coordinate files corresponding to the initial airfoils;
[0008] (2) Processing the coordinate file of the initial airfoil to unfold the corresponding airfoil curve;
[0009] (3) performing interpolation processing on the unfolded airfoil curve, unifying the abscissas corresponding to the airfoil curve, and generating the ordinates corresponding to the abscissas;
[0010] (4) weighting, summing and normalizing the ordinates corresponding to the unfolded airfoil curve to generate a new set of ordinates of the airfoil;
[0011] (5) The ordinate of the new airfoil is combined with the abscissa of the initial airfoil after interpolation to generate a new airfoil curve.
[0012] Furthermore, the initial airfoil selected in step (1) should include airfoils with relatively high lift-to-drag ratio and good stall performance, and also include airfoils with poor aerodynamic performance and irregular shapes.
[0013] Furthermore, the number of initial airfoils in step (1) should be between 8 and 16.
[0014] Furthermore, the coordinate file processing of the initial airfoil in step (2) should ensure that the ordinate remains unchanged, while the abscissa of the upper or lower wing surface is multiplied by negative one.
[0015] Furthermore, the number of horizontal coordinate points corresponding to the airfoil curve in step (3) should be greater than 200 and be an odd number.
[0016] Furthermore, the ordinate weighted value in step (4) may be a negative number, but the absolute value of all weights should be less than one.
[0017] The advantages of the present invention compared with the prior art are:
[0018] (1) The initial airfoil selection includes airfoils with high lift-to-drag ratio and good stall performance, as well as airfoils with poor aerodynamic performance and irregular shapes, which increases the size of the airfoil search space and the novelty of the design.
[0019] (2) Allowing the weighted value to be negative, that is, the emergence of airfoil reverse fitting, further liberates the search space for airfoil optimization.
[0020] (3) No geometric constraints are imposed on the airfoil design space, eliminating the designer’s bias and increasing the diversity of new airfoil types. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a flow chart of the method for generating airfoil of fixed-wing UAV;
[0022] Figure 2 These are the outline drawings of the 12 initial airfoils;
[0023] Figure 3 It is the appearance diagram of the target airfoil in airfoil optimization;
[0024] Figure 4 It is a curve comparison diagram of the optimized airfoil and the target airfoil;
[0025] Figure 5is the error map between the optimized airfoil and the target airfoil. DETAILED DESCRIPTION
[0026] The present invention is now further described and verified in conjunction with the embodiments and drawings:
[0027] Use the fixed-wing UAV airfoil fitting method to generate any airfoil in the airfoil library. The specific steps are as follows:
[0028] (1) Select 13 airfoils as shown in Table 1 from the Profili airfoil library, of which the first 12 airfoils are used as the initial airfoils and the last airfoil is used as the target airfoil, and export the coordinate files corresponding to the 13 airfoils.
[0029] (2) The coordinate files corresponding to the 13 airfoils are processed separately so that the horizontal coordinates corresponding to the upper wing surface of the airfoil are multiplied by negative one, while the other coordinate values remain unchanged.
[0030] (3) Generate an airfoil curve corresponding to the processed coordinate file, evenly select 501 points on the horizontal coordinate corresponding to the airfoil curve, and generate the corresponding vertical coordinate.
[0031] The code to generate the new coordinates is: "x_interpolated = linspace(min(x), max(x), 501);y_interpolated = interp1(x, y, x_interpolated); airfoil=[x_interpolated',y_interpolated'];".
[0032] (4) The ordinate group corresponding to the generated original airfoil is weighted, summed and normalized to generate a new ordinate.
[0033] (5) By controlling the weighted value of the original airfoil, the minimum error between the new ordinate and the target airfoil is sought. When the weight of the initial airfoil is as shown in Table 1, the root mean square error is 3.1653×10 -4 .
[0034] Table 1 Number of airfoil coordinate points and weights of the fitted new airfoil
[0035] Airfoil Name Number of coordinate points before processing Number of coordinate points after interpolation Weight of airfoil AG 24 160 501 0.24761 AH 79-100 B 97 501 -0.27873 AH21 62 501 0.55876 AS5046 82 501 0.06409 BE8457E 35 501 -0.06516 CHEN 98 501 -0.02566 CLARK Y 121 501 0.61012 E205 61 501 0.22341 FX 38-153 97 501 -0.11040 GOE417 33 501 -0.09120 MH115 61 501 0.04528 S1223 81 501 0.06633 NACA2412 97 501
Claims
1. A method for generating airfoil of a fixed-wing UAV, characterized in that: The following steps are involved: Step 1: Select multiple airfoils from the existing airfoil library as the initial airfoil, and export the coordinate file corresponding to the initial airfoil; Step 2: Process the coordinate file of the initial airfoil to unfold the corresponding airfoil curve; Step 3: interpolate the unfolded airfoil curve, unify the abscissa corresponding to the airfoil curve, and generate the ordinate corresponding to the abscissa; Step 4: Weight, sum and normalize the ordinates corresponding to the unfolded airfoil curve to generate a new set of ordinates of the airfoil; Step 5: The ordinate of the new airfoil is combined with the abscissa of the initial airfoil after interpolation to generate a new airfoil curve.
2. The method for generating a fixed-wing UAV airfoil according to claim 1, characterized in that: The initial airfoil selection in step 1 should include airfoils with high lift-to-drag ratio and good stall performance, as well as airfoils with poor aerodynamic performance and irregular shapes.
3. The method for generating a fixed-wing UAV airfoil according to claim 1, characterized in that: The initial number of airfoils in step 1 should be between 8 and 16.
4. The method for generating a fixed-wing UAV airfoil according to claim 1, characterized in that: The coordinate file processing of the initial airfoil in step 2 should ensure that the ordinate remains unchanged, while the abscissa of the upper or lower wing surface is multiplied by negative one.
5. The method for generating airfoil of a fixed-wing UAV according to claim 1, characterized in that: The number of horizontal coordinate points corresponding to the airfoil curve in step 3 should be greater than 200 and an odd number.
6. The method for generating airfoil of a fixed-wing UAV according to claim 1, characterized in that: The ordinate weights in step 4 can be negative, but the absolute values of all weights should be less than one.