Method, device and medium for analyzing dynamic stability based on aircraft oscillation frequency

Abstract

The present application discloses a method, device and medium for analyzing dynamic stability based on the oscillation frequency of an aircraft. According to the technical solution of the present application, by performing flow modal decomposition on the flow response of the aircraft at different oscillation frequencies, observing the flow modal changes at different frequencies, and combining the pressure changes of the surface under different frequency oscillations, the flow physical mechanism of the influence of the aircraft oscillation frequency on dynamic stability can be analyzed. The present application introduces a flow modal decomposition method when analyzing the dynamic stability flow characteristics, which can quantitatively analyze the flow mechanism of the influence of the oscillation frequency on dynamic stability, and establish the relationship between the microscopic result - flow mode, and the macroscopic performance indicator - dynamic derivative.

Description

Technical Field

[0001] The present application belongs to the field of aircraft aerodynamic design, and specifically, relates to a method, electronic equipment, medium and device for analyzing dynamic stability based on aircraft oscillation frequency. Background Art

[0002] In the development of aircraft, maneuverability is one of our key concerns. In the stability design of aircraft, pitch dynamic derivative is an important parameter to characterize the dynamic stability of aircraft, and is also the main basic data for aircraft aerodynamic modeling and flight control system design. In the process of stability design, the oscillation frequency of the aircraft is an important related parameter for extracting dynamic derivatives. In previous studies, there is an empirical understanding that "the dynamic derivative does not change much with frequency at small angles of attack". When the oscillation frequency of the aircraft is unclear, a forced oscillation frequency of 2Hz-15Hz is generally selected for wind tunnel tests and numerical calculations. However, theoretical analysis and practice show that the oscillation frequency cannot be given arbitrarily. In wind tunnel tests, it was found that at large angles of attack, the pitch dynamic derivative of the aircraft is more sensitive to the oscillation frequency of the aircraft. A slight change in the oscillation frequency will bring about a change in the magnitude of the dynamic derivative. In severe cases, the dynamic derivative may even reverse its sign, which has a great impact on the evaluation of the dynamic stability of the aircraft. Moreover, when the aircraft is actually flying, the change of flight altitude will change the incoming flow density, and the continuous consumption of fuel will cause the moment of inertia to change. These changes and various factors such as unstable gusts will cause the aircraft's oscillation frequency to change continuously, so the impact of the aircraft's oscillation frequency on dynamic stability is crucial. However, previous studies have not found a research method to solve this problem, and a method that can effectively analyze the flow mechanism of the impact of oscillation frequency on aircraft dynamic stability is urgently needed. Summary of the invention

[0003] The present application provides a method for analyzing the influence of aircraft oscillation frequency on dynamic stability instability, and the present application also provides corresponding electronic equipment, medium and device.

[0004] In one aspect of the present application, a method for analyzing dynamic stability based on an aircraft oscillation frequency is provided, the method comprising:

[0005] Step 1: Obtain the data required for numerical simulation of the aircraft model;

[0006] Step 2: numerically simulate the aircraft model based on the data, and obtain the flow field of the aircraft model when it is in a stationary state and in an oscillating motion with different oscillation frequencies at different attack angles, wherein the amplitude of the oscillating motion is within a predetermined amplitude range;

[0007] Step three, obtaining characteristic surface flow field information of the flow field;

[0008] Step 4, performing flow modal decomposition on the characteristic surface flow field information to obtain the flow modes of the aircraft model at different oscillation frequencies;

[0009] Step 5, reconstructing the flow field based on the flow mode to obtain the relationship between the flow mode and the pitching derivative at different oscillation frequencies;

[0010] Step six, analyzing the dynamic stability of the aircraft model based on the pitch dynamic derivative.

[0011] Optionally, step one specifically includes:

[0012] Use mesh generation software to import the aircraft model;

[0013] Generate grid lines on the edge of the aircraft model;

[0014] Distribute grid points on each grid line and encrypt them in local areas;

[0015] Generate a mesh surface through the mesh lines, and project the mesh surface onto the surface of the aircraft model to make the mesh fit the body;

[0016] A mesh block is generated through the mesh surface to generate a space mesh of the aircraft for the numerical simulation.

[0017] Optionally, the numerical simulation adopts CFL3D calculation program; the aircraft space grid adopts SST turbulence model and is in plot3d format; the numerical simulation adopts delayed detached vortex algorithm.

[0018] Optionally, in step 2, obtaining the flow field of the aircraft model at different attack angles when it is in oscillating motion at different oscillation frequencies specifically includes:

[0019] The flow fields of the aircraft model when it is in a non-moving state at different attack angles are taken as the initial fields;

[0020] Setting the frequency and amplitude of the oscillating motion in a numerical simulation calculation program;

[0021] Set a predetermined number of data points to be taken per oscillation cycle;

[0022] Set the time interval step for recording the flow field;

[0023] Obtain the flow field under unsteady flow.

[0024] Optionally, in step 2, obtaining the flow field specifically includes:

[0025] In the calculation program for numerical simulation, it is set to record the flow field at the corresponding moment in each calculation step to obtain the flow field at each moment under unsteady flow.

[0026] Optionally, step three specifically includes:

[0027] For each moment, the flow field at that moment is imported into the tecplot software for analysis;

[0028] For each moment, the characteristic surface is selected by analyzing the flow field characteristics at that moment;

[0029] The characteristic surface flow field information of the flow field at each moment is calculated, and the characteristic surface flow field information includes pressure, density, temperature, energy, and velocity of the characteristic surface.

[0030] Optionally, step 4 specifically includes:

[0031] The characteristic surface flow field information at different times is numbered in chronological order;

[0032] Set the desired output modal order;

[0033] The flow field information of the numbered characteristic surfaces at different times is imported into the dynamic mode decomposition (DMD) program for flow mode decomposition;

[0034] According to the unit circle and the modal energy, the mode of the desired output modal order is determined.

[0035] Another aspect of the present application further provides an electronic device, the electronic device comprising:

[0036] A memory storing executable instructions;

[0037] A processor runs the executable instructions in the memory to implement the method for analyzing dynamic stability based on aircraft oscillation frequency as described above.

[0038] In another aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for analyzing dynamic stability based on the oscillation frequency of an aircraft as described above is implemented.

[0039] In another aspect of the present application, there is also provided a device for analyzing dynamic stability based on the oscillation frequency of an aircraft, comprising:

[0040] A data acquisition unit, used to acquire data required for numerical simulation of the aircraft model;

[0041] a flow field acquisition unit, configured to perform numerical simulation on the aircraft model based on the data, and acquire flow fields when the aircraft model is in a stationary state and in an oscillating motion with different oscillation frequencies at different attack angles, wherein the amplitude of the oscillating motion is within a predetermined amplitude range;

[0042] A characteristic surface information acquisition unit, used to acquire characteristic surface flow field information of the flow field;

[0043] A flow mode decomposition unit, used for performing flow mode decomposition on the characteristic surface flow field information to obtain the flow modes of the aircraft model at different oscillation frequencies;

[0044] A frequency dynamic derivative relationship unit, used to reconstruct the flow field based on the flow mode, and obtain the relationship between the flow mode and the pitch dynamic derivative at different oscillation frequencies;

[0045] A dynamic stability analysis unit is used to analyze the dynamic stability of the aircraft model based on the pitch dynamic derivative.

[0046] This application has at least the following advantages:

[0047] (1) Before dynamic stability analysis, the flow mode decomposition method is used to decompose the flow field into a linear combination of several typical modes;

[0048] (2) By adopting the flow mode decomposition method, the contribution of different flow modes to the instantaneous aerodynamic force can be obtained, thereby establishing the relationship between the microscopic results (flow mode) and the macroscopic performance indicators (dynamic derivatives). BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The present invention is a flowchart of a method for analyzing dynamic stability based on aircraft oscillation frequency according to an embodiment of the present application.

[0050] Figure 2 This is a schematic diagram of the appearance of the aircraft model used in the exemplary embodiment of the present application.

[0051] Figure 3 It is a schematic diagram of the CFD mesh topology of the aircraft model in the exemplary embodiment of the present application.

[0052] Figure 4 It is a schematic diagram of sub-iteration convergence of CFD numerical calculation in an exemplary embodiment of the present application.

[0053] Figure 5 It is a schematic diagram of the arrangement of flow mode characteristic surfaces in an exemplary embodiment of the present application.

[0054] Figure 6 Schematic diagram of the variation of pitch derivative with attack angle at different oscillation frequencies in an exemplary embodiment of the present application.

[0055] Figure 7 This is a comparison diagram of typical modes at different frequencies in the exemplary embodiment of the present application. DETAILED DESCRIPTION

[0056] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0057] When an aircraft is actually flying, changes in flight altitude will change the incoming flow density, and continuous fuel consumption will cause changes in rotational inertia. These changes and unstable gusts of wind will cause the aircraft's oscillation frequency to change continuously, so the impact of the aircraft's oscillation frequency on dynamic stability is crucial. This application introduces a flow modal decomposition method when analyzing dynamic stability flow characteristics, which can quantitatively analyze the flow mechanism of the impact of oscillation frequency on dynamic stability and establish the relationship between microscopic results (flow modes) and macroscopic performance indicators (dynamic derivatives).

[0058] Figure 1 The flowchart of the method for analyzing dynamic stability based on the oscillation frequency of an aircraft according to an embodiment of the present application is shown in the figure. As shown in the figure, the method includes steps 1 to 6.

[0059] Step 1: Obtain the data required for numerical simulation of the aircraft model;

[0060] Step 2: numerically simulate the aircraft model based on the data, and obtain the flow field of the aircraft model when it is in a stationary state and in an oscillating motion with different oscillation frequencies at different attack angles, wherein the amplitude of the oscillating motion is within a predetermined amplitude range;

[0061] Step three, obtaining characteristic surface flow field information of the flow field;

[0062] Step 4, performing flow modal decomposition on the characteristic surface flow field information to obtain the flow modes of the aircraft model at different oscillation frequencies;

[0063] Step 5, reconstructing the flow field based on the flow mode to obtain the relationship between the flow mode and the pitching derivative at different oscillation frequencies;

[0064] Step six, analyzing the dynamic stability of the aircraft model based on the pitch dynamic derivative.

[0065] According to this embodiment, a working condition where the aircraft oscillation frequency has a greater impact on the dynamic derivative can be selected. By performing flow modal decomposition on the flow response of the aircraft at different oscillation frequencies, observing the flow modal changes at different frequencies, and combining the pressure changes of the characteristic surface at different frequency oscillations, the flow physical mechanism of the influence of the aircraft oscillation frequency on dynamic stability can be analyzed. This application introduces a flow modal decomposition method when analyzing the dynamic stability flow characteristics, which can quantitatively analyze the flow mechanism of the influence of the oscillation frequency on dynamic stability and establish the relationship between the microscopic results (flow modal) and the macroscopic performance indicators (dynamic derivatives).

[0066] Several specific implementation details of exemplary embodiments of the present application are described below.

[0067] (1) The aerodynamic calculation grid required for CFD (Computational Fluid Dynamics) numerical simulation can be generated according to the characteristics of different types of aircraft models. Pointwise grid generation software can be used to generate the grid. The grid form is a structured grid. When generating the grid, it can be encrypted in areas with more separated flows. Connectors (grid lines) can be generated first, and then connectors are connected to form domains (grid surfaces), and domains are assembled to form blocks (grids), thereby forming a spatial grid.

[0068] (2) According to the flow characteristics of different types of aircraft, aerodynamic settings such as spatial discretization format, time advancement format, turbulence model, preprocessing, entropy correction, etc. can be selected to perform preliminary aerodynamic calculations to obtain aerodynamic forces and flow fields. The flow field can include basic information such as pressure, density, temperature, energy, and velocity. For research conditions with more intense separation flows, the RANS / LES method can also be used to improve the simulation accuracy of the separation flow.

[0069] (3) Based on the initial flow field and aerodynamic force obtained, the grid can be encrypted until the aerodynamic force is almost unchanged, proving that the grid size is reasonable and reliable. When the grid is encrypted, the area with more intense separation flow should be encrypted, and appropriate encryption should be performed in the i, j, and k directions. Based on the initial flow field, the area with more intense separation flow that needs to be encrypted can be determined.

[0070] (4) The flow field of the aircraft at different angles of attack can be simulated to obtain the static aerodynamic force of the aircraft and the unsteady flow field of the aircraft when it is not moving. The flow field at each time point can be recorded as the input file for flow modal decomposition. When recording the unsteady flow calculation results, since the calculation result file is large, the recording time step can be appropriately extended as long as the flow modal decomposition requirements are met.

[0071] (5) The unsteady flow field of the aircraft in the non-moving state obtained in (4) can be used as the initial field to simulate the small amplitude motion of the aircraft at different angles of attack, and the instantaneous flow field of the aircraft at each time point can be recorded as the input file for flow modal decomposition. When recording the unsteady flow calculation results, since the calculation result file is large, the recording time step can be appropriately extended as long as the flow modal decomposition requirements are met.

[0072] (6) The unsteady flow field in (4) can be subjected to flow modal decomposition to obtain the flow mode of the aircraft under static conditions. Since flow modal decomposition of the entire three-dimensional flow field will consume a lot of computer memory and may even be impossible to calculate, in order to ensure the efficiency and accuracy of this method, a plane that can represent the flow characteristics can be selected as a feature surface for flow modal decomposition according to different aircraft characteristics.

[0073] (7) The unsteady flow field of the aircraft in the small amplitude oscillation motion mode obtained in (5) can be decomposed into flow modes to obtain flow modes. In the process of selecting flow modes, it should be noted that only the first few modes (i.e., the modal order of the expected output) are selected. Retaining too many modes is meaningless for flow analysis.

[0074] (8) The flow modes obtained in (6) and (7) can be compared, and the influence of oscillatory motion on the flow modes can be analyzed.

[0075] (9) A method similar to (5) can be used to simulate the unsteady flow of an aircraft at different oscillation frequencies, and the unsteady flow field information of the aircraft at different oscillation frequencies can be recorded as the input file for flow modal decomposition. When recording the unsteady flow calculation results, since the calculation result file is large, the recording time step can be appropriately extended as long as the flow modal decomposition requirements are met.

[0076] (10) The flow field files at different oscillation frequencies obtained in (9) can be subjected to flow modal decomposition to obtain the flow modes of the aircraft at different oscillation frequencies, and the influence of the oscillation frequency on the flow mode can be analyzed.

[0077] (11) By reconstructing the unsteady flow field of the flow modes at different frequencies, the modal coefficients of different flow modes can be obtained, and the contribution values ​​of the first few flow modes to the aerodynamic pressure on the object surface can also be obtained.

[0078] (12) By analyzing the contribution of the flow mode to the aerodynamic pressure on the object surface, the influence of different oscillation frequencies on the dynamic stability characteristics can be obtained, and the relationship between the flow mode and the dynamic derivative can be established.

[0079] This application takes the analysis of the impact of the oscillation frequency of a flying wing layout aircraft on its dynamic stability as an example.

[0080] The grid file required for numerical simulation of the standard flying wing model can be generated first. The research object of this application is the domestic standard flying wing model with a small aspect ratio, and its three-dimensional schematic diagram is as follows Figure 2 , whose CFD mesh topology is as follows Figure 3As shown. The model scale is 1:25, and the calculation state is: Mach number Ma=0.1, angle of attack α=20°~60°. The simulation accuracy of the unsteady flow on the leeward side of the flying wing standard model is very important. In view of the relatively simple appearance of the flying wing standard model, the calculation in this exemplary embodiment can adopt an O-type structural grid topology, which can not only meet the calculation accuracy well, but also ensure the calculation efficiency. In order to more finely capture the unsteady flow phenomena such as vortex breakup point oscillation, vortex shedding oscillation, spiral waves, etc., the leeward side of the flying wing standard model should be purposefully locally encrypted along the span direction, and a certain grid density should also be maintained along the axial direction. In terms of the amount of grids, in order to meet the DDES simulation requirements and ensure the efficiency of unsteady flow calculations, a compromise is adopted between calculation accuracy and efficiency, and the initial structural grid amount is set to be about 1500W.

[0081] Key parameters and calculation methods required for numerical simulation can also be selected. When the flow field is characterized by attached flow or very weak separated flow, the Reynolds average (RANS) method commonly used in engineering can obtain better calculation accuracy and efficiency. For the flying wing layout, due to the separated flow, concentrated vortex, vortex rupture and other phenomena at larger angles of attack, the traditional RANS method cannot achieve accurate simulation. Therefore, for the separated flow, this study intends to use the DDES method. This method can use the RANS method in the attached flow area and the LES (large eddy simulation) method in the separated flow. It combines the advantages of the two and can accurately simulate the small-scale vortex of the separated flow while ensuring efficiency. The spatial discretization uses the Roe format, the time advancement uses the format, and the dual time step method is used. Its sub-iterative convergence process is as follows: Figure 4 shown.

[0082] Modal decomposition of complex separation flow at large angles of attack can be performed. Through numerical calculation of unsteady flow, at least 200 instantaneous flow fields are obtained as data input for the DMD method. Since DMD analysis of the overall flow field will bring a huge amount of calculation, in order to efficiently obtain the modal characteristics of the separation flow on the leeward side of the flying wing standard model, and capture the flow modes and characteristic frequencies of different flow phenomena. In this application, the pressure of the flying wing standard model surface and the "monitoring surface" in space are collected to obtain the pressure change history over time, and a variety of flow modal characteristics are obtained through the DMD method. Taking the unsteady characteristics of delta wing separation flow in the literature as a reference, the unsteady flow characteristics of the flying wing standard model are mainly vortex rupture point oscillation, vortex shedding unsteadiness, and spiral wave development unsteadiness after vortex rupture. In order to capture these different types of unsteady flow frequencies, a "monitoring surface" is arranged at the corresponding position of the leeward side of the flying wing standard model. The distribution diagram of the "monitoring surface" is shown in the figure. Figure 5 .

[0083] After obtaining the pressure change history of the object surface and the monitoring surface over time, the flow field snapshot data matrix can be established:

[0084] {U1,U2,U3,……,U i}

[0085] U represents the flow field information, and the subscript represents the number generated in chronological order. Assuming that there is a matrix A that makes the relationship between adjacent time layers linear, then there exists:

[0086] U i+1 =AU i

[0087] For flow fields with large amounts of data, A is a very large matrix, so DMD uses a low-dimensional optimization approximation matrix To replace A, by solving the approximate matrix The eigenvalues ​​and eigenvectors of are used to obtain the amplitude and growth rate of the flow mode, and the flow field can be further reconstructed. In order to evaluate the error of DMD in reconstructing the unsteady flow field, the loss function F is defined loss , where represents the original flow field, represents the reconstructed flow field, ‖·‖ represents the Frobenius norm:

[0088]

[0089] The pitch derivatives at different oscillation frequencies can be obtained, such as Figure 6 The rigid dynamic grid technology and the double time step method can be used to numerically simulate the small amplitude motion of the aircraft pitching around the body axis to obtain the time-varying history of the aerodynamic coefficients, and then the static / dynamic derivatives can be obtained from the unsteady calculation results using the least squares method.

[0090] In the working conditions where the flow is more unsteady, due to the dramatic change of aerodynamic force over time, the amplitude of aerodynamic force change may even exceed the amplitude of flow change caused by forced vibration. At this time, the amplitude can be appropriately increased, and a sufficient number of calculation cycles can be ensured. At the same time, the spectrum analysis of the aerodynamic force signal and the appropriate filtering of the frequency band with lower energy are beneficial to eliminate "signal noise" in the dynamic derivative identification and ensure the accuracy of dynamic derivative identification. Evaluate the impact of different sampling cycles, amplitudes, and frequencies on dynamic derivative identification. Considering the time-consuming nature of unsteady calculations, it is proposed to use a multi-grid method. The number of points distributed by the grid topology connector meets the rule of 8n+1, which accelerates the convergence speed of the unsteady calculation sub-iteration and can reduce the calculation time by 30%-50%. When selecting the amplitude, it should be controlled within 5° as much as possible to meet the linear assumption.

[0091] The influence of oscillation frequency on flow mode can be obtained, such as Figure 7. Typical working conditions (i.e. working conditions where the vibration frequency has a greater impact on the dynamic derivative) are selected for research, and the instantaneous flow of small-amplitude oscillations (typical monitoring surfaces, object surfaces, etc.) is reconstructed to obtain the contribution of different modes to the instantaneous aerodynamic force. Since the premise of the dynamic derivative is the small perturbation linear assumption, the instantaneous aerodynamic force can be regarded as the sum of the static aerodynamic force, the static derivative term, and the dynamic derivative term (damping term). If the static aerodynamic force and the static derivative term are both known, the contribution of different flow modes to the dynamic derivative term can be extracted, thereby establishing the relationship between the flow mode and the dynamic derivative. At the same time, the flow mode is closely related to the oscillation frequency, which reveals the influence mechanism of the oscillation frequency on dynamic stability.

[0092] The working condition where the aircraft oscillation frequency has a greater impact on the dynamic derivative can be selected. By performing flow modal decomposition on the flow response of the aircraft at different oscillation frequencies, observing the flow modal changes at different frequencies, and combining the pressure changes of the surface under different frequency oscillations, the flow physical mechanism of the impact of the aircraft oscillation frequency on dynamic stability can be analyzed. This application introduces a flow modal decomposition method when analyzing the dynamic stability flow characteristics, which can quantitatively analyze the flow mechanism of the impact of the oscillation frequency on dynamic stability and establish the relationship between the microscopic results (flow mode) and the macroscopic performance indicators (dynamic derivatives).

[0093] The present application also provides a device for analyzing dynamic stability based on aircraft oscillation frequency, comprising:

[0094] A data acquisition unit, used to acquire data required for numerical simulation of the aircraft model;

[0095] a flow field acquisition unit, configured to perform numerical simulation on the aircraft model based on the data, and acquire flow fields when the aircraft model is in a stationary state and in an oscillating motion with different oscillation frequencies at different attack angles, wherein the amplitude of the oscillating motion is within a predetermined amplitude range;

[0096] A characteristic surface information acquisition unit, used to acquire characteristic surface flow field information of the flow field;

[0097] A flow mode decomposition unit, used for performing flow mode decomposition on the characteristic surface flow field information to obtain the flow modes of the aircraft model at different oscillation frequencies;

[0098] A frequency dynamic derivative relationship unit, used to reconstruct the flow field based on the flow mode, and obtain the relationship between the flow mode and the pitch dynamic derivative at different oscillation frequencies;

[0099] A dynamic stability analysis unit is used to analyze the dynamic stability of the aircraft model based on the pitch dynamic derivative.

[0100] For other details of this embodiment, please refer to the above.

[0101] An electronic device according to an embodiment of the present application includes a memory and a processor.

[0102] The memory is used to store non-temporary computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0103] The processor may be a central processing unit (CPU) or other forms of processing units with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of the present application, the processor is used to run the computer-readable instructions stored in the memory.

[0104] Those skilled in the art should be able to understand that in order to solve the technical problem of how to obtain a good user experience, the present embodiment may also include well-known structures such as a communication bus and an interface, and these well-known structures should also be included in the scope of protection of the present application.

[0105] For detailed description of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0106] An embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the method for analyzing dynamic stability based on aircraft oscillation frequency is implemented.

[0107] According to the computer-readable storage medium of the embodiment of the present application, non-transitory computer-readable instructions are stored thereon. When the non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the method of each embodiment of the present application are executed.

[0108] The above-mentioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or mobile hard disk), media with built-in rewritable non-volatile memory (e.g., memory card) and media with built-in ROM (e.g., ROM box)

[0109] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0110] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for analyzing dynamic stability based on aircraft oscillation frequency, characterized in that: The method comprises: Step 1: Obtain the data required for numerical simulation of the aircraft model; Step 2: numerically simulate the aircraft model based on the data, and obtain the flow field of the aircraft model when it is in a stationary state and in an oscillating motion with different oscillation frequencies at different attack angles, wherein the amplitude of the oscillating motion is within a predetermined amplitude range; Step three, obtaining characteristic surface flow field information of the flow field; Step 4, performing flow modal decomposition on the characteristic surface flow field information to obtain the flow modes of the aircraft model at different oscillation frequencies; Step 5, reconstructing the flow field based on the flow mode to obtain the relationship between the flow mode and the pitching derivative at different oscillation frequencies; Step six, analyzing the dynamic stability of the aircraft model based on the pitch dynamic derivative; Wherein, in step 2, obtaining the flow field when the aircraft model is in oscillation motion with different oscillation frequencies at different attack angles specifically includes: The flow fields of the aircraft model when it is in a non-moving state at different attack angles are taken as the initial fields; Setting the frequency and amplitude of the oscillating motion in a numerical simulation calculation program; Set a predetermined number of data points to be taken per oscillation cycle; Set the time interval step for recording the flow field; Obtain the flow field under unsteady flow; Step three specifically includes: For each moment, the flow field at that moment is imported into the tecplot software for analysis; For each moment, the characteristic surface is selected by analyzing the flow field characteristics at that moment; Calculating characteristic surface flow field information of the flow field at each moment, wherein the characteristic surface flow field information includes pressure, density, temperature, energy, and velocity of the characteristic surface; Step 4 specifically includes: The characteristic surface flow field information at different times is numbered in chronological order; Set the desired output modal order; The flow field information of the numbered characteristic surfaces at different times is imported into the dynamic mode decomposition (DMD) program for flow mode decomposition; According to the unit circle and the modal energy, the mode of the desired output modal order is determined.

2. The method according to claim 1, characterized in that Step 1 specifically includes: Use mesh generation software to import the aircraft model; Generate grid lines on the edge of the aircraft model; Distribute grid points on each grid line and encrypt them in local areas; Generate a mesh surface through the mesh lines, and project the mesh surface onto the surface of the aircraft model to make the mesh fit the body; A mesh block is generated through the mesh surface to generate a space mesh of the aircraft for the numerical simulation.

3. The method according to claim 2, characterized in that: The numerical simulation adopts CFL3D calculation program; The aircraft space grid adopts the SST turbulence model and is in plot3d format; The numerical simulation adopts a delayed detached vortex algorithm.

4. The method according to any one of claims 1 to 3, characterized in that In step 2, obtaining the flow field specifically includes: In the calculation program for numerical simulation, it is set to record the flow field at the corresponding moment in each calculation step to obtain the flow field at each moment under unsteady flow.

5. An electronic device, characterized in that: The electronic device comprises: A memory storing executable instructions; A processor, wherein the processor runs the executable instructions in the memory to implement the method for analyzing dynamic stability based on aircraft oscillation frequency according to any one of claims 1 to 4.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for analyzing dynamic stability based on aircraft oscillation frequency according to any one of claims 1 to 4 is implemented.

7. A device for analyzing dynamic stability based on aircraft oscillation frequency, characterized in that: include: A data acquisition unit, used to acquire data required for numerical simulation of the aircraft model; a flow field acquisition unit, configured to perform numerical simulation on the aircraft model based on the data, and acquire flow fields when the aircraft model is in a stationary state and in an oscillating motion with different oscillation frequencies at different attack angles, wherein the amplitude of the oscillating motion is within a predetermined amplitude range; A characteristic surface information acquisition unit, used to acquire characteristic surface flow field information of the flow field; A flow mode decomposition unit, used for performing flow mode decomposition on the characteristic surface flow field information to obtain the flow modes of the aircraft model at different oscillation frequencies; A frequency dynamic derivative relationship unit, used to reconstruct the flow field based on the flow mode, and obtain the relationship between the flow mode and the pitch dynamic derivative at different oscillation frequencies; A dynamic stability analysis unit, configured to analyze the dynamic stability of the aircraft model based on the pitch dynamic derivative; Wherein, the flow field acquisition unit is specifically used for: The flow fields of the aircraft model when it is in a non-moving state at different attack angles are taken as the initial fields; Setting the frequency and amplitude of the oscillating motion in a numerical simulation calculation program; Set a predetermined number of data points to be taken per oscillation cycle; Set the time interval step for recording the flow field; Obtain the flow field under unsteady flow; The feature surface information acquisition unit is specifically used for: For each moment, the flow field at that moment is imported into the tecplot software for analysis; For each moment, the characteristic surface is selected by analyzing the flow field characteristics at that moment; Calculating characteristic surface flow field information of the flow field at each moment, wherein the characteristic surface flow field information includes pressure, density, temperature, energy, and velocity of the characteristic surface; The flow mode decomposition unit is specifically used for: The characteristic surface flow field information at different times is numbered in chronological order; Set the desired output modal order; The flow field information of the numbered characteristic surfaces at different times is imported into the dynamic mode decomposition (DMD) program for flow mode decomposition; According to the unit circle and the modal energy, the mode of the desired output modal order is determined.

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