High angle of attack nonlinear separated flow aerodynamic force correction method
By employing the DES method and matrix correction technology, the problem of inaccurate aerodynamic prediction during high angle-of-attack flight phases was solved, achieving efficient aerodynamic correction and elasticity analysis, thus meeting the overall design requirements for rapid iteration.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA ACAD OF LAUNCH VEHICLE TECH
- Filing Date
- 2022-10-26
- Publication Date
- 2026-05-22
Smart Images
Figure CN115906686B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of aerospace overall design technology, and relates to an aeroelastic design method for a space-to-ground reciprocating vehicle, and particularly to a method for correcting the aerodynamic forces of nonlinear separated flow at large angles of attack. Background Technology
[0002] Reusable spacecraft undergo cross-airspace and cross-velocity flight during their operation. During the hypersonic high angle-of-attack flight phase, flow separation leads to significant nonlinearity in aerodynamic forces, substantially impacting aeroelastic properties. Engineering methods exhibit poor accuracy at this stage, requiring correction. Specifically, aeroelastic analysis requires aerodynamic forces as input and must balance computational accuracy and efficiency. During the high angle-of-attack deceleration phase, surface-element engineering aerodynamic models, such as the piston theory method, are commonly used for aeroelastic analysis. However, in the high angle-of-attack phase, complex flow separation results in strongly nonlinear aerodynamic characteristics, leading to significant deviations in prediction accuracy for engineering methods. While DES-based numerical methods can accurately describe the nonlinear characteristics caused by flow separation in the hypersonic high angle-of-attack phase, their low computational efficiency prevents them from meeting the requirements of rapid iterative overall design. Summary of the Invention
[0003] The purpose of this invention is to overcome the above-mentioned defects and provide a method for correcting aerodynamic forces in nonlinear separated flow at large angles of attack. This method solves the technical problem that existing aerodynamic correction methods cannot balance computational accuracy and computational efficiency. This invention can combine the computational accuracy of CFD with the computational efficiency of engineering methods.
[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0005] A method for correcting the aerodynamics of nonlinear separated flow at large angles of attack includes:
[0006] Data on the surface pressure distribution of the aircraft at zero reduction frequency were obtained using the DES method.
[0007] The surface area of the aircraft is divided into surface elements, and the geometric information of each surface element is determined.
[0008] Based on the geometric information of each surface element, the aerodynamic influence coefficient matrix AIC is generated using the dipole lattice method.
[0009] Based on the aerodynamic influence coefficient matrix AIC generated by the dipole lattice method, the aerodynamic influence coefficient matrix A at zero reduction frequency is then obtained. DLM,k＝0 ;
[0010] Using an RBF-based conservation interpolation method, the aircraft surface pressure distribution data obtained by the DES method is interpolated onto each surface element to obtain the aerodynamic influence coefficient matrix A for all surface elements. DES ;
[0011] According to A DLM,k＝0 and A DES We obtain the force correction matrix W;
[0012] The aerodynamic influence coefficient matrix AIC is corrected using the force correction matrix W to obtain the corrected aerodynamic influence coefficient matrix AIC. * ;
[0013] The modified aerodynamic influence coefficient matrix AIC is used. * Aerodynamic corrections are then performed.
[0014] Furthermore, the surface region of the aircraft is divided into elements based on the pressure distribution data of the aircraft surface, so that the pressure of each element varies at equal intervals in the direction of the incoming flow and the spanwise direction.
[0015] Furthermore, the geometric information of each element includes the coordinates of its vertices, pressure points, and wash control points.
[0016] Furthermore, the pressure point of the surface element is the intersection of the cross-section within the surface element and the quarter-chord line of the surface element.
[0017] The control point for the washout of a surface element is the intersection of the cross section in the surface element and the 3 / 4 chord of the surface element.
[0018] Furthermore, the pressure distribution data of the aircraft surface obtained using the DES method is interpolated onto each surface element to obtain the aerodynamic matrix A of all surface elements. DES The methods include:
[0019] The pressure distribution data of the aircraft surface obtained by the DES method is interpolated onto each surface element to obtain the aerodynamic force and moment at the pressure point of each surface element.
[0020] The aerodynamic matrix A for all facets is obtained based on the aerodynamic forces and moments at the pressure points of each facet. DES .
[0021] Furthermore, the aerodynamic forces and moments at each pressure point of the surface element are obtained according to the following formula:
[0022] f j =H sa T f f ;
[0023] Among them, f j Here, H represents the aerodynamic force and torque at the pressure point of the j-th surface element, where j ≥ 1; saf is the displacement transfer matrix determined using the RBF method. f The pressure distribution in the flow field is the pressure distribution data on the aircraft surface obtained using the DES method.
[0024] Furthermore, the force correction matrix W satisfies the following formula:
[0025] A DLM,k＝0 =A DES *W.
[0026] Furthermore, according to A DLM,k＝0 and A DES The method to obtain the force correction matrix W is to use the Newton-Raphson iteration method to make matrix A DLM,k＝0 and A DES The iteration ends when the deviation of the main diagonal elements of W is less than the preset accuracy requirement, and the force correction matrix W is obtained.
[0027] Furthermore, using the force correction matrix W, the aerodynamic influence coefficient matrix AIC is corrected according to the following formula to obtain the corrected aerodynamic influence coefficient matrix AIC. * :
[0028] AIC * =W* AIC .
[0029] Furthermore, aeroelastic analysis is performed using the modified aerodynamic force as input.
[0030] Compared with the prior art, the present invention has the following advantages:
[0031] (1) This invention uses DES calculation data to correct the surface aerodynamic model, which makes up for the shortcomings of the engineering aerodynamic method in predicting the surface pressure of the aircraft at high angle of attack.
[0032] (2) The modified method of this invention combines the computational accuracy of CFD with the computational efficiency of engineering methods, and can meet the requirements of rapid iteration in overall design;
[0033] (3) This invention proposes a method for dividing surface elements, which improves the accuracy of the aerodynamic matrix;
[0034] (4) The correction method based on matrix multiplication proposed in this invention is simple and easy to implement, and effectively improves computational efficiency. Attached Figure Description
[0035] Figure 1 This is a block diagram of a high angle-of-attack nonlinear separated flow aerodynamic correction method strategy in a preferred embodiment of the present invention;
[0036] Figure 2 This is a typical aerodynamic grid on the surface of a spacecraft that travels between Earth and space.
[0037] Figure 3 Typical examples of separated flow and disturbances;
[0038] Figure 4 This is a schematic diagram of the surface element of the present invention. Detailed Implementation
[0039] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.
[0040] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.
[0041] Unlike traditional axisymmetric rockets, space-to-ground vehicles typically employ a complex aerodynamic layout with multiple control surfaces and a wing-body combination, resulting in high structural flexibility. Supersonic high angle-of-attack deceleration is a unique flight state for space-to-ground vehicles, during which aeroelastic phenomena involving structural and aerodynamic coupling are prone to occur.
[0042] Aeroelastic analysis requires aerodynamic forces as input and must balance computational accuracy and efficiency. For supersonic high angle-of-attack deceleration phases, surface-element engineering aerodynamic models, such as the piston theory method, are commonly used as aerodynamic models for aeroelastic analysis. However, in high angle-of-attack phases, due to complex flow separation, the aerodynamic forces exhibit strong nonlinear characteristics, leading to significant deviations in prediction accuracy for engineering methods. While DES-based numerical methods can accurately describe the nonlinear characteristics caused by flow separation in supersonic high angle-of-attack phases, their computational efficiency is low, failing to meet the requirements of rapid iterative overall design.
[0043] This invention proposes a method for correcting the aerodynamics of nonlinear separated flow at large angles of attack. It uses DES numerical calculations of aircraft surface pressure data to correct the engineering aerodynamic model, thereby improving the accuracy of the engineering aerodynamic analysis. This method is applicable to aerodynamic correction and aeroelastic analysis of nonlinear separated flow at large angles of attack.
[0044] like Figure 1 The present invention provides a method for correcting the aerodynamics of nonlinear separated flow at large angles of attack, comprising the following steps:
[0045] (1) Use the DES method to perform aerodynamic calculations and obtain the surface pressure data of the aircraft;
[0046] (2) Interpolate the surface pressure data calculated by the DES method to the surface element pressure points;
[0047] (3) The iterative method was used to correct the surface element aerodynamic influence coefficient matrix based on DES data;
[0048] (4) The modified aerodynamic influence coefficient matrix is used to perform nonlinear aeroelastic correction and aeroelastic analysis for large angle of attack.
[0049] A method for correcting the aerodynamics of nonlinear separated flow at large angles of attack is proposed. The method uses DES method to calculate data and corrects engineering aerodynamic methods (piston theory method, dipole grid method). It is used for aerodynamic correction and aeroelastic analysis of nonlinear separated flow at large angles of attack.
[0050] The specific steps of this invention are as follows:
[0051] Step (1) Calculate the aerodynamic forces of the aircraft using the DES method.
[0052] The DES numerical method was used to calculate the pressure distribution data on the outer surface of the aircraft at zero reduction frequency, obtain the location and structure of flow separation, and store the pressure data of all flow field grid points. A typical aerodynamic grid for a reciprocating spacecraft surface is shown in the figure. Figure 2 Typical separation flows and disturbances such as Figure 3 .
[0053] Step (II) Data Format Conversion
[0054] By using standard data formats such as Tecplot, the flow field pressure data calculated by structured / unstructured solvers can be converted into a unified unstructured data format.
[0055] Step (3) Surface mesh generation of the aircraft
[0056] The surface area of the aircraft is divided into several surface elements, such as Figure 4 The intersection of the cross section in the marked surface element and the chord line of the 1 / 4 segment is the pressure point, and the intersection of the cross section in the marked surface element and the chord line of the 3 / 4 segment is the wash control point. Figure 4 As shown in the figure. In this step, DES numerical calculation is used to calculate the surface pressure data of the aircraft, and an interpolation mapping relationship is established between the numerical calculation grid and the surface element calculation grid.
[0057] Step (IV) Generation of the AIC matrix (generalized influence coefficient matrix of surface elements) before correction
[0058] The dipole lattice method is used to generate the uncorrected AIC matrix AIC (generalized influence coefficient matrix AIC) based on the geometric information of the surface elements.
[0059] Step (5) Calculation of surface element aerodynamics
[0060] Based on the generalized influence coefficient matrix AIC obtained in the previous step, the aerodynamic matrix A of all surface elements at zero reduction frequency is obtained. DLM,k＝0 .
[0061] Step (VI) Surface element pressure interpolation
[0062] A conservation interpolation method based on RBF is used to interpolate the surface aerodynamic forces calculated by DES onto the j-th surface element. Specifically, a conservation (force and moment) interpolation method based on RBF is used to interpolate the DES distributed force data to the pressure point of the surface element, obtaining the aerodynamic forces and moments (f) at the pressure point. j Generate the aerodynamic matrix A of all surface elements. DES .
[0063] f j =H sa T f f (1)
[0064] Among them, H sa f is the displacement transfer matrix determined using the RBF method. f For the pressure distribution in the flow field, f j Let be the aerodynamic force and torque at the pressure point of the j-th surface element.
[0065] Step (7) Force Correction Matrix Generation
[0066] Based on A obtained in steps five and six DLM,k＝0 and A DES We obtain the force correction matrix W, which satisfies the following equation:
[0067] A DLM,k＝0 =A DES *W (2)
[0068] The specific approach is to use the Newton-Raphson iteration to make A DLM,k＝0 Matrix and A DES The iteration ends when the deviation of the main diagonal elements of the W matrix is less than the preset precision requirement.
[0069] Step (8) Correcting the AIC matrix generation
[0070] Using the force correction matrix obtained in step seven, the modified aerodynamic influence coefficient matrix AIC is generated. * :
[0071] AIC * =W*AIC (3)
[0072] Step (9): Complete aerodynamic correction
[0073] The modified aerodynamic influence coefficient matrix AIC is used. * Aerodynamic corrections can be performed, and further aeroelasticity calculations can be conducted to complete the aerodynamic correction process.
[0074] In summary, this invention proposes a method for correcting the aerodynamics of nonlinear separated flow at large angles of attack. By using a DES-based numerical calculation method to analyze the flow field pressure data and correcting the generalized influence coefficient matrix (AIC) of the surface element, it achieves the dual goals of balancing computational accuracy and analytical efficiency, and meets the requirements for rapid iteration in the overall design.
[0075] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
[0076] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. A method for correcting the aerodynamic forces of a nonlinear separated flow at large angles of attack, characterized in that, include: Data on the surface pressure distribution of the aircraft at zero reduction frequency were obtained using the DES method. The surface area of the aircraft is divided into surface elements, and the geometric information of each surface element is determined. Based on the geometric information of each surface element, the aerodynamic influence coefficient matrix AIC is generated using the dipole lattice method. Based on the aerodynamic influence coefficient matrix AIC generated by the dipole lattice method, the aerodynamic influence coefficient matrix A at zero reduction frequency is then obtained. DLM,k＝0 ; Using an RBF-based conservation interpolation method, the aircraft surface pressure distribution data obtained by the DES method is interpolated onto each surface element to obtain the aerodynamic influence coefficient matrix A for all surface elements. DES ; According to A DLM,k＝0 and A DES We obtain the force correction matrix W; The aerodynamic influence coefficient matrix AIC is corrected using the force correction matrix W to obtain the corrected aerodynamic influence coefficient matrix AIC. * ; The modified aerodynamic influence coefficient matrix AIC is used. * Aerodynamic corrections are then performed.
2. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 1, characterized in that, The surface region of the aircraft is divided into elements based on the pressure distribution data of the aircraft surface, so that the pressure of each element varies at equal intervals in the direction of the incoming flow and the spanwise direction.
3. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 1, characterized in that, The geometric information of each element includes the coordinates of its vertices, pressure points, and wash control points.
4. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 3, characterized in that, The pressure point of a surface element is the intersection of the cross-section within the surface element and the quarter-chord line of the surface element. The control point for the wash of a surface element is the intersection of the cross section in the surface element and the 3 / 4 chord of the surface element.
5. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 4, characterized in that, The pressure distribution data of the aircraft surface obtained using the DES method is interpolated onto each surface element to obtain the aerodynamic matrix A of all surface elements. DES The methods include: The pressure distribution data of the aircraft surface obtained by the DES method is interpolated onto each surface element to obtain the aerodynamic force and moment at the pressure point of each surface element. The aerodynamic matrix A for all facets is obtained based on the aerodynamic forces and moments at the pressure points of each facet. DES .
6. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 5, characterized in that, The aerodynamic forces and moments at each pressure point of the surface element are obtained according to the following formula: f j =H sa T f f ; Among them, f j Let H be the aerodynamic force and torque at the pressure point of the j-th surface element, where j ≥ 1; sa f is the displacement transfer matrix determined using the RBF method. f The pressure distribution in the flow field is the pressure distribution data on the aircraft surface obtained using the DES method.
7. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 1, characterized in that, The force correction matrix W satisfies the following formula: A DLM,k＝0 =A DES *W。 8. The method for correcting aerodynamic forces in a large angle-of-attack nonlinear separated flow according to claim 7, characterized in that, According to A DLM,k＝0 and A DES The method to obtain the force correction matrix W is to use the Newton-Raphson iteration method to make matrix A DLM,k＝0 and A DES The iteration ends when the deviation of the main diagonal elements of W is less than the preset accuracy requirement, and the force correction matrix W is obtained.
9. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 1, characterized in that, Using the force correction matrix W, the aerodynamic influence coefficient matrix AIC is corrected according to the following formula to obtain the corrected aerodynamic influence coefficient matrix AIC. * : AIC * =W*AIC。 10. The aerodynamic correction method for large angle-of-attack nonlinear separated flow according to claim 1, characterized in that, Aeroelastic analysis was performed using the corrected aerodynamic forces as input.