Large-amplitude oscillation aerodynamic characteristic numerical simulation parameter determination method and device

Abstract

The invention belongs to the technical field of aircraft simulation design, and particularly relates to a large-amplitude oscillation aerodynamic characteristic numerical simulation parameter determination method and device, and the method comprises the steps: S1, obtaining the maximum pitch angle speed and attack angle change range of an aircraft for simulation; s2, calculating the reduction frequency of pitch oscillation according to the maximum pitch angular velocity of the aircraft; s3, determining a balance angle of attack and amplitude according to the angle of attack change range; s4, giving a sine wave motion equation of the aircraft attack angle according to the reduction frequency, the balance attack angle and the amplitude; s5, determining a simulation calculation period according to the sine wave motion equation; and step S6, determining a time interval for calculation in a single simulation calculation period and an iteration step number for calculation in the time interval through simulation, wherein the calculation result is converged in the single simulation calculation period. According to the method, calculation efficiency and data accuracy can be considered, and aerodynamic characteristic data available for engineering can be rapidly obtained.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft simulation design, and in particular relates to a method and device for determining numerical simulation parameters of large-scale oscillation aerodynamic characteristics. Background Art

[0002] Modern aircraft have increasingly higher requirements for maneuverability, and their development directions include high angle of attack post-stall maneuvers and relaxed static stability. One of the most important characteristics is that the aircraft will move at large pitch angular velocity, which has a great impact on the aerodynamic characteristics, especially the severe nonlinear aerodynamic forces and complex unsteady vortex forces. Currently, the aerodynamic characteristics of aircraft under large pitch oscillations are mainly obtained through wind tunnel tests or numerical simulations. However, the influence of the wind tunnel wall on the unsteady aerodynamic force of the model is far more complex than that of steady tests. It is currently impossible to make wall interference corrections for unsteady test data, and the test costs are high and the cycle is long. Numerical simulations require a large number of simulation parameters and mainly rely on the design experience of engineers. The selection of simulation parameters has a great impact on the calculation efficiency and the accuracy of the results. Summary of the Invention

[0003] The present application provides a method and device for determining numerical simulation parameters of large-scale oscillation aerodynamic characteristics to solve the problem of inaccurate simulation parameter selection.

[0004] The first aspect of the present application provides a method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics, mainly comprising:

[0005] Step S1, obtaining the maximum pitch angular velocity and angle of attack variation range of the aircraft used for simulation;

[0006] Step S2: Calculate the reduced frequency of pitch oscillation according to the maximum pitch angular velocity of the aircraft;

[0007] Step S3, determining a balanced angle of attack and amplitude according to the angle of attack variation range;

[0008] Step S4, providing a sinusoidal wave motion equation of the aircraft's angle of attack based on the reduced frequency, the equilibrium angle of attack, and the amplitude;

[0009] Step S5: determining a simulation calculation period according to the sinusoidal wave motion equation;

[0010] Step S6: Determine, through simulation, the time interval for calculation within a single simulation calculation cycle that allows the calculation results to converge and the number of iterative steps for calculation within the time interval.

[0011] Preferably, in step S2, the reduction frequency is calculated by the following formula:

[0012]

[0013] Among them, q is the maximum pitch angular velocity of the aircraft, a is the chord length, and V is the flight speed.

[0014] Preferably, in step S4, the sinusoidal wave motion equation of the aircraft angle of attack α is:

[0015]

[0016] Among them, α0 is the equilibrium angle of attack, A0 is the amplitude, and t is the running time.

[0017] Preferably, step S6 further comprises:

[0018] Step S61: a fixed number of iteration steps within a given time interval, for simulation calculation cycles divided into different given time intervals, using the fixed number of iteration steps to calculate the aerodynamic forces during the aircraft oscillation process, and determining a maximum time interval for convergence of the aerodynamic forces;

[0019] Step S62: Calculate the aerodynamic force during the aircraft oscillation process for given different iteration steps within the maximum time interval, and determine the minimum iteration step for convergence of the aerodynamic force.

[0020] Preferably, in step S61, the aerodynamic force is calculated within a quarter of a simulation calculation cycle.

[0021] The second aspect of the present application provides a device for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics, mainly comprising:

[0022] The pitch rate and angle of attack acquisition module is used to obtain the maximum pitch rate and angle of attack variation range of the aircraft used for simulation;

[0023] A reduction frequency calculation module, used for calculating the reduction frequency of pitch oscillation according to the maximum pitch angular velocity of the aircraft;

[0024] A balanced angle of attack and amplitude calculation module, configured to determine the balanced angle of attack and amplitude according to the angle of attack variation range;

[0025] a sine wave motion equation acquisition module, configured to provide a sine wave motion equation of the aircraft's angle of attack based on the reduced frequency, the equilibrium angle of attack, and the amplitude;

[0026] A simulation calculation period acquisition module, used to determine the simulation calculation period according to the sinusoidal wave motion equation;

[0027] The time interval and iteration step calculation module is used to determine the time interval for calculation and the iteration step number for calculation in a single simulation calculation cycle that makes the calculation result converge through simulation.

[0028] Preferably, in the reduction frequency calculation module, the reduction frequency is calculated by the following formula:

[0029]

[0030] Among them, q is the maximum pitch angular velocity of the aircraft, a is the chord length, and V is the flight speed.

[0031] Preferably, in the sinusoidal wave motion equation acquisition module, the sinusoidal wave motion equation of the aircraft angle of attack α is:

[0032]

[0033] Among them, α0 is the equilibrium angle of attack, A0 is the amplitude, and t is the running time.

[0034] Preferably, the time interval and iteration step number calculation module includes:

[0035] a maximum time interval calculation unit configured to calculate a fixed number of iteration steps within a given time interval, calculate the aerodynamic forces during the aircraft oscillation process using the fixed number of iteration steps for a given simulation calculation cycle divided into different time intervals, and determine a maximum time interval for convergence of the aerodynamic forces;

[0036] The minimum iteration step calculation unit is used to calculate the aerodynamic force during the aircraft oscillation process for given different iteration steps within the maximum time interval, and determine the minimum iteration step for convergence of the aerodynamic force.

[0037] Preferably, in the maximum time interval calculation unit, the aerodynamic force is calculated within a quarter of a simulation calculation cycle.

[0038] This application can balance computational efficiency and data accuracy, and quickly obtain aerodynamic characteristic data that can be used in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of a preferred embodiment of the method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.

[0041] The first aspect of the present application provides a method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics, such as Figure 1 As shown, it mainly includes:

[0042] Step S1, obtaining the maximum pitch angular velocity and angle of attack variation range of the aircraft used for simulation;

[0043] Step S2: Calculate the reduced frequency of pitch oscillation according to the maximum pitch angular velocity of the aircraft;

[0044] Step S3, determining a balanced angle of attack and amplitude according to the angle of attack variation range;

[0045] Step S4, providing a sinusoidal wave motion equation of the aircraft's angle of attack based on the reduced frequency, the equilibrium angle of attack, and the amplitude;

[0046] Step S5: determining a simulation calculation period according to the sinusoidal wave motion equation;

[0047] Step S6: Determine, through simulation, the time interval for calculation within a single simulation calculation cycle that allows the calculation results to converge and the number of iterative steps for calculation within the time interval.

[0048] Numerical simulation parameters mainly include two categories: one is motion similarity parameters, and the other is calculation parameters. Among them, motion similarity parameters include the reduction frequency during the aircraft's large oscillation, the aircraft's balanced angle of attack, and the amplitude of the large oscillation, which are calculated in steps S2 and S3. The calculation parameters include the calculation period T, the time interval ΔT in each period, and the number of sub-iteration steps k at each time point. During the simulation calculation, the shorter the time interval and the more sub-iteration steps at a single time point, the more accurate the calculation results. However, this will consume a lot of computing resources and affect the calculation efficiency. Therefore, it is necessary to select an appropriate time interval and number of iteration steps, which are calculated in steps S5 and S6.

[0049] In step S1, the present application determines the starting angle of attack and the angle of attack range of the large oscillation based on the aircraft maneuvering history. For example, an aircraft with a chord length of a and a flight speed of V performs a large pitch angular velocity movement at a certain flight altitude H. During this process, the maximum pitch angular velocity is q, and the aircraft's angle of attack α changes rapidly from 10° to 60°, and then returns to its original state.

[0050] In step S2, the reduced frequency of the pitch oscillation is calculated according to the similarity criterion of the Steinhardt number. In some optional embodiments, in step S2, the reduced frequency is calculated by the following formula

[0051] Among them, q is the maximum pitch angular velocity of the aircraft, a is the chord length, and V is the flight speed.

[0052] In step S3, the equilibrium angle of attack of the large oscillation and the amplitude of the large oscillation are calculated, that is, the median value of the angle of attack from 10° to 60° and the degree of deviation from the median value are determined. In this embodiment, the equilibrium angle of attack is Amplitude of large oscillations

[0053] Finally, in step S4, the motion equation is given in the form of a sine wave to simulate the motion law of large oscillation. In some optional embodiments, in step S4, the sinusoidal wave motion equation of the aircraft angle of attack α is:

[0054]

[0055] Among them, α0 is the equilibrium angle of attack, A0 is the amplitude, and t is the running time.

[0056] Then, in step S5, the simulation calculation period is determined. The simulation calculation period T is equal to the period of the aircraft's large oscillation. The period of the large oscillation can be obtained from the motion equation, namely:

[0057]

[0058] Finally, in step S6, an appropriate time step and number of iterations are selected within a single motion cycle. After completely calculating 2 to 3 cycles of motion, the aircraft aerodynamic force within the last cycle is taken to finally obtain the relationship curve between the aerodynamic characteristics and the angle of attack during the aircraft's large oscillation process.

[0059] In some optional implementations, step S6 further includes:

[0060] Step S61: a fixed number of iteration steps within a given time interval, for simulation calculation cycles divided into different given time intervals, using the fixed number of iteration steps to calculate the aerodynamic forces during the aircraft oscillation process, and determining a maximum time interval for convergence of the aerodynamic forces;

[0061] Step S62: Calculate the aerodynamic force during the aircraft oscillation process for given different iteration steps within the maximum time interval, and determine the minimum iteration step for convergence of the aerodynamic force.

[0062] In this embodiment, in a single simulation calculation cycle T, the more computing nodes there are, that is, the smaller the time interval is, the more accurate the calculation result will be, but the more resources will be consumed. Therefore, it is necessary to find the minimum computing node, that is, to determine the maximum time interval in step S61. Simulations are performed sequentially, with the first aerodynamic force calculated using ΔT1 and the second aerodynamic force calculated using ΔT2. This interval is the required time interval ΔT until the results converge to a stable solution. For example, if the results of ΔT3 and ΔT4 are essentially the same, the time interval ΔT can be determined to be ΔT3.

[0063] In step S61, to ensure data comparability, the same number of iteration steps is set within each time interval, that is, a fixed number of iteration steps is pre-set, for example, 20. On the other hand, to improve computational efficiency, in some optional embodiments, the aerodynamic forces may be calculated within only one-quarter of the simulation computation cycle (T / 4).

[0064] Next, in step S62, the number of iterations for a single time interval needs to be determined. Using the same method as in step S61, within the calculated time interval ΔT, simulations are performed sequentially for iterations k1 = 20, k2 = 30, k3 = 40, and so on. When the calculation results converge to a stable solution, this iteration number is the minimum required to balance data accuracy and computational efficiency.

[0065] This application can quickly and accurately obtain aircraft large-scale oscillation aerodynamic characteristic data, taking into account both calculation efficiency and data accuracy, obtain aerodynamic characteristic data that can be used in engineering, and improve engineering development efficiency.

[0066] The second aspect of the present application provides a device for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics corresponding to the above method, mainly comprising:

[0067] The pitch rate and angle of attack acquisition module is used to obtain the maximum pitch rate and angle of attack variation range of the aircraft used for simulation;

[0068] A reduction frequency calculation module, used for calculating the reduction frequency of pitch oscillation according to the maximum pitch angular velocity of the aircraft;

[0069] A balanced angle of attack and amplitude calculation module, configured to determine the balanced angle of attack and amplitude according to the angle of attack variation range;

[0070] a sine wave motion equation acquisition module, configured to provide a sine wave motion equation of the aircraft's angle of attack based on the reduced frequency, the equilibrium angle of attack, and the amplitude;

[0071] A simulation calculation period acquisition module, used to determine the simulation calculation period according to the sinusoidal wave motion equation;

[0072] The time interval and iteration step calculation module is used to determine the time interval for calculation and the iteration step number for calculation in a single simulation calculation cycle that makes the calculation result converge through simulation.

[0073] In some optional implementations, in the reduced frequency calculation module, the reduced frequency is calculated by the following formula:

[0074]

[0075] Among them, q is the maximum pitch angular velocity of the aircraft, a is the chord length, and V is the flight speed.

[0076] In some optional implementations, in the sinusoidal wave motion equation acquisition module, the sinusoidal wave motion equation of the aircraft angle of attack α is:

[0077]

[0078] Among them, α0 is the equilibrium angle of attack, A0 is the amplitude, and t is the running time.

[0079] In some optional implementations, the time interval and iteration step number calculation module includes:

[0080] a maximum time interval calculation unit configured to calculate a fixed number of iteration steps within a given time interval, calculate the aerodynamic forces during the aircraft oscillation process using the fixed number of iteration steps for a given simulation calculation cycle divided into different time intervals, and determine a maximum time interval for convergence of the aerodynamic forces;

[0081] The minimum iteration step calculation unit is used to calculate the aerodynamic force during the aircraft oscillation process for given different iteration steps within the maximum time interval, and determine the minimum iteration step for convergence of the aerodynamic force.

[0082] In some optional implementations, in the maximum time interval calculation unit, the aerodynamic force is calculated within a quarter of a simulation calculation cycle.

[0083] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics, characterized in that: include: Step S1, obtaining the maximum pitch angular velocity and angle of attack variation range of the aircraft used for simulation; Step S2: Calculate the reduced frequency of pitch oscillation according to the maximum pitch angular velocity of the aircraft; Step S3, determining a balanced angle of attack and amplitude according to the angle of attack variation range; Step S4, providing a sinusoidal wave motion equation of the aircraft's angle of attack based on the reduced frequency, the equilibrium angle of attack, and the amplitude; Step S5: determining a simulation calculation period according to the sinusoidal wave motion equation; Step S6: Determine, through simulation, the time interval for calculation within a single simulation calculation cycle that allows the calculation results to converge and the number of iterative steps for calculation within the time interval.

2. The method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 1, characterized in that: In step S2, the reduction frequency is calculated by the following formula Among them, q is the maximum pitch angular velocity of the aircraft, a is the chord length, and V is the flight speed.

3. The method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 1, characterized in that: In step S4, the sinusoidal motion equation of the aircraft angle of attack α is: Among them, α0 is the equilibrium angle of attack, A0 is the amplitude, and t is the running time.

4. The method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 1, characterized in that: Step S6 further comprises: Step S61: a fixed number of iteration steps within a given time interval, for simulation calculation cycles divided into different given time intervals, using the fixed number of iteration steps to calculate the aerodynamic forces during the aircraft oscillation process, and determining a maximum time interval for convergence of the aerodynamic forces; Step S62: Calculate the aerodynamic force during the aircraft oscillation process for given different iteration steps within the maximum time interval, and determine the minimum iteration step for convergence of the aerodynamic force.

5. The method for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 4, characterized in that: In step S61, the aerodynamic force is calculated within a quarter of a simulation calculation cycle.

6. A device for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics, characterized in that: include: The pitch rate and angle of attack acquisition module is used to obtain the maximum pitch rate and angle of attack variation range of the aircraft used for simulation; A reduction frequency calculation module, used for calculating the reduction frequency of pitch oscillation according to the maximum pitch angular velocity of the aircraft; A balanced angle of attack and amplitude calculation module, configured to determine the balanced angle of attack and amplitude according to the angle of attack variation range; a sine wave motion equation acquisition module, configured to provide a sine wave motion equation of the aircraft's angle of attack based on the reduced frequency, the equilibrium angle of attack, and the amplitude; A simulation calculation period acquisition module, used to determine the simulation calculation period according to the sinusoidal wave motion equation; The time interval and iteration step calculation module is used to determine the time interval for calculation and the iteration step number for calculation in a single simulation calculation cycle that makes the calculation result converge through simulation.

7. The device for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 6, characterized in that: In the reduced frequency calculation module, the reduced frequency is calculated by the following formula: Among them, q is the maximum pitch angular velocity of the aircraft, a is the chord length, and V is the flight speed.

8. The device for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 6, characterized in that: In the sinusoidal wave motion equation acquisition module, the sinusoidal wave motion equation of the aircraft angle of attack α is: Among them, α0 is the equilibrium angle of attack, A0 is the amplitude, and t is the running time.

9. The device for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 6, characterized in that: The time interval and iteration step number calculation module includes: a maximum time interval calculation unit configured to calculate a fixed number of iteration steps within a given time interval, calculate the aerodynamic forces during the aircraft oscillation process using the fixed number of iteration steps for a given simulation calculation cycle divided into different time intervals, and determine a maximum time interval for convergence of the aerodynamic forces; The minimum iteration step calculation unit is used to calculate the aerodynamic force during the aircraft oscillation process for given different iteration steps within the maximum time interval, and determine the minimum iteration step for convergence of the aerodynamic force.

10. The device for determining parameters of numerical simulation of large-scale oscillation aerodynamic characteristics according to claim 9, characterized in that: In the maximum time interval calculation unit, the aerodynamic force is calculated within a quarter of a simulation calculation cycle.

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