Method for calculating aerodynamic impulse of impact wave swept aircraft wing based on Monte-Carlo simulation

Abstract

The invention discloses a Monte-Carlo simulation-based impact wave swept aircraft wing aerodynamic impulse calculation method, and belongs to the technical field of flight mechanics and flight safety, and the method comprises the following steps: S1, impact wave swept wing aerodynamic data preprocessing; s2, carrying out Monte Carlo two-dimensional random sampling and patterning; s3, determining a relative position interval of discrete data; and S4, judging a drop point interval and counting. By adopting the Monte-Carlo simulation-based method for calculating the aerodynamic impulse of the impact wave swept aircraft wing, the problems existing in the calculation of the aerodynamic impulse of the impact wave swept aircraft wing are solved, and the feasibility and the accuracy of the method for calculating the aerodynamic impulse of the impact wave swept aircraft wing by adopting Monte Carlo simulation are verified.

Description

Technical Field

[0001] The invention relates to the technical field of flight mechanics and flight safety, and in particular to a method for calculating aerodynamic impulse of a wing of a shock wave swept aircraft based on Monte-Carlo simulation. Background Art

[0002] When the shock wave sweeps the aircraft in flight, the significant gust effect and time-varying characteristics of the overpressure caused by the shock wave overpressure and dynamic pressure will generate additional aerodynamic forces when acting on the various components of the aircraft. These additional aerodynamic forces have large transient amplitudes, short action times, drastic changes in aerodynamic gradients, and complex waveforms. It is difficult to study the acceleration of aerodynamic forces on the wings. Therefore, in the flight safety verification, the aerodynamic impulse obtained by integrating the aerodynamic force over time is required as the external disturbance input signal for the flight safety verification. As the main lifting surface of the entire aircraft, the wing is most affected by the additional aerodynamic impulse swept by the shock wave, and its influence is mainly reflected in the following aspects: (1) Impact on flight performance: The aerodynamic impulse of the wing swept by the shock wave will change the aerodynamic parameters of the wing, such as lift, drag and pitch moment, and thus affect the flight performance of the aircraft, such as the climb rate, sink rate and maneuverability parameters. (2) Impact on structural dynamic stability: The transient high-intensity aerodynamic impulse generated when the shock wave sweeps the wing will cause transient changes in torque and load on the wing. If the structural design of the wing cannot effectively resist these impulses, it may cause structural deformation or damage; (3) Impact of flight dynamic response: The transient aerodynamic impulse generated when the shock wave sweeps the wing causes the aircraft's flight dynamic response, which may lead to a sharp change in flight state parameters such as flight altitude and flight angle of attack, thus affecting the aircraft's flight dynamic performance. (4) Impact on flight control: The changes in aerodynamic impulse caused by the shock wave sweeping across the wing may also interfere with the flight control system. In extreme cases, the flight control system may malfunction or even fail to respond to these interferences, thus threatening flight safety.

[0003] In summary, the wing aerodynamic impulse needs to be calculated in detail as a general input condition for the verification of aircraft flight mechanics and flight safety under shock wave sweep. For the calculation of the aerodynamic impulse of the wing under shock wave sweep, the present invention adopts the Monte Carlo method for solution for the following reasons: First, the aerodynamic force changes with time is a series of discrete data, and the disturbance characteristics change with time in a complex manner, which cannot be described by equations or functions. The Monte Carlo method only needs to determine the position relationship between the random point and the aerodynamic integral interval, and there is no need to solve the aerodynamic data expression function or equation; second, the shock wave sweep involves the changes in wing drag, side force and lift. When the Monte Carlo method solves the three aerodynamic impulses, the calculation program has universality and does not need to be processed separately for different aerodynamic forces; third, the aerodynamic force changes of the wing under the shock wave sweep have a direction, which may lead to a negative integral interval of the aerodynamic impulse. When the conventional method is used for calculation, the absolute value needs to be taken for segmented accumulation, while the Monte Carlo method only needs to determine the relative position without processing the aerodynamic data. Therefore, from the perspective of simulation calculation, this patent proposes a Monte Carlo calculation method based on statistical experiments to solve the above three problems existing in the calculation of aerodynamic impulse of the wing of a shock wave swept aircraft. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation to solve the problems existing in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides a method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation, comprising the following steps: S1, shock wave swept wing aerodynamic data preprocessing; S2, Monte Carlo two-dimensional random sampling and graphics; S3, determination of relative position interval of discrete data; S4. Determination of the landing point interval and counting statistics.

[0006] Preferably, step S1 specifically comprises: S11, obtain the database and coordinate system of the aircraft wing swept by the shock wave, give the integral directions of the wing drag, side force and lift according to the research working conditions, and calculate the change of the shock wave pressure over time; S12, output time step sequence ,in, is the number of time steps, , and according to the sampling time step Output discrete data of the aerodynamic force of the aircraft wing swept by the shock wave over time; S13, cleaning the time-varying data of the aircraft wing drag, side force, and lift under the shock wave sweep in step S12 to remove wild values, and the obtained time-varying sequence sets of the wing aerodynamic data are respectively expressed as: 、 、 .

[0007] Preferably, step S2 specifically comprises: S21. Given random sampling sample size , using a pseudo-random number generator to implement random point sampling, the random point sampling set is , for any point The coordinates of , ; S22, according to step S12 Sequence and step S13 , 、 Sequence, respectively establish the time-varying matrices of the aerodynamic drag, side force, and lift of the wing of the shock wave swept aircraft 、 、 ; S23, write a program to draw 、 、 Two-dimensional distribution scatter plot.

[0008] Preferably, step S3 specifically comprises: S31. Define the floor function: ,in, is a time series, so , To take integer values, such as , , ; S32, for any point in the sample size , get In the time step sequence In order to find the relative position interval middle There are two cases to be discussed: (a) coincides with the endpoint, that is ( The situation is the same); or (b) lie in Between the intervals, that is ; S33, for any point in the sample capacity ,calculate: ; According to the definition in step S12 、 ,like The time step sequence meets the above S32 (a) case; if The time step sequence meets the situation of type (b) in S32 above.

[0009] Preferably, step S4 is specifically: S41, according to the two-dimensional distribution scatter plot in step S2, for any point ,like If the situation meets category (a), then compare The size of the elements corresponding to each aerodynamic matrix; taking the aerodynamic drag matrix as an example (the judgment method of side force and lift is the same), if Open interval, then The count is accumulated; if Open interval, then The count is not accumulated, where is the number of sample points falling into each aerodynamic effective accumulation interval; S42. For any point ,like The following situations meet the requirements of category (b): ; ; ; ; when When it is within the valid interval, we have: ; Right now: ; like When the above formula is satisfied, The count is accumulated; if If the above formula is not satisfied, then Counts are not cumulative; S43. After the accumulation of random sampling points of aerodynamic forces is completed, the wing drag impulse is calculated: ; in, is the area of ​​the figure, The calculation method of the dynamic pressure, the impulse of the side force of the wing swept by the shock wave, and the disturbance of the lift impulse are the same; S44. Take the sampling capacity For each sampling sample size, the Monte Carlo method is used several times to calculate the aerodynamic impulse of the shock wave swept wing. The change of the calculated mean with the size of the sampling sample size is analyzed and compared with the theoretical value of the shock wave swept aerodynamic impulse to verify the calculation accuracy of the Monte Carlo method.

[0010] Therefore, the present invention adopts the above-mentioned Monte-Carlo simulation-based shock wave swept aircraft wing aerodynamic impulse calculation method, which has the following beneficial effects: (1) By using the Monte Carlo method, it is only necessary to determine the position relationship between the random point and the aerodynamic integration interval, without solving the aerodynamic data expression function or equation; (2) The Monte Carlo method is universal when solving the three aerodynamic impulses, and there is no need to process different aerodynamic forces separately. (3) The Monte Carlo method only needs to determine the relative position without processing the aerodynamic data.

[0011] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The present invention is a flow chart of aerodynamic impulse calculation of a shock wave swept aircraft wing based on Monte Carlo simulation; Figure 2 The present invention is a scatter plot of the ratio of the aerodynamic force and the dynamic pressure of the wing of the shock wave swept aircraft over time; wherein (a) is a scatter plot of the ratio of the shock wave swept drag and the dynamic pressure over time; (b) is a scatter plot of the ratio of the shock wave swept side force and the dynamic pressure over time; (c) is a scatter plot of the ratio of the shock wave swept lift and the dynamic pressure over time; Figure 3 This is a schematic diagram of the calculation of the landing point position interval vector of the present invention; Figure 4 The present invention is a schematic diagram of the variation of the aerodynamic impulse calculation results of the wing of a shock wave swept aircraft with the sampling sample size; (a) is a schematic diagram of the variation of the aerodynamic drag impulse calculation results with the sampling sample size; (b) is a schematic diagram of the variation of the aerodynamic side force impulse calculation results with the sampling sample size; (c) is a schematic diagram of the variation of the aerodynamic lift impulse calculation results with the sampling sample size. DETAILED DESCRIPTION

[0013] Example In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0014] like Figure 1 As shown, a method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation comprises the following steps: S1. Preprocessing of aerodynamic data of shock wave swept wing S11, obtain the database and coordinate system of the aircraft wing swept by the shock wave, give the integral directions of the wing drag, side force and lift according to the research working conditions, and calculate the change of the shock wave pressure over time; S12, output time step sequence (in is the number of time steps, ), and according to the sampling time step Output discrete data of the aerodynamic force of the aircraft wing swept by the shock wave over time; S13, cleaning the time-varying data of the aircraft wing drag, side force, and lift under the shock wave sweep in S12 to remove wild values, and the obtained time-varying sequence sets of the wing aerodynamic data are respectively expressed as: 、 、 .

[0015] S2, Monte Carlo 2D random sampling and graphics S21. Given random sampling sample size , using a pseudo-random number generator to implement random point sampling, the random point sampling set is For any point Coordinates for , ; S22. According to S12 Sequence and step S13 、 、 Sequence, respectively establish the time-varying matrices of the aerodynamic drag, side force, and lift of the wing of the shock wave swept aircraft 、 、 ; S23, write a program to draw 、 、 Two-dimensional distribution scatter plot. The scatter plot of the aerodynamic force of the aircraft wing swept by the shock wave over time is as follows Figure 2 As shown, for the convenience of expressing all aerodynamic data, dynamic pressure has been removed ( )deal with, .

[0016] S3. Determination of relative position interval of discrete data S31. Define the floor function: ,in, is a time series, so , To take integer values, such as 、 、 ; S32, for any point in the sample size , get In time series The relative position interval in middle There are two situations that need to be discussed in detail: (a) Coincident with the endpoint ( The situation is the same); or (b) lie in Between the intervals, that is .

[0017] S33, for any point in the sample ,calculate: ; According to the definition in step S12 、 .like time series, it meets the above-mentioned category (a) of S32 (hereinafter referred to as category a); if Time series, then it meets the above-mentioned S32 (b) situation (hereinafter referred to as category b).

[0018] S4. Determination of the landing interval and counting statistics S41, according to the aerodynamic scatter point distribution diagram in step S2, for any point ,like If it meets the a category, then compare The size of the elements corresponding to each aerodynamic matrix. Taking the aerodynamic drag matrix as an example (the judgment method of side force and lift is the same), if Open interval, then The count is accumulated; if Open interval, then The count is not accumulated, where is the number of sample points falling into each aerodynamic effective accumulation interval; S42. For any point ,like In line with category b, according to Figure 3 ,have: ; ; ; ; when When it is within the valid interval, we have: ; Right now: ; Point A and point B are located at The above formula is satisfied on both the same and different sides of the axis. When the above formula is satisfied, The count is accumulated; if If the above formula is not satisfied, then Counts are not cumulative; S43. After the accumulation of random sampling points of aerodynamic forces is completed, the wing drag impulse is calculated: ; in, is the sampling sample capacity in step S21; for Figure 2 (a) The area of ​​the figure, in this embodiment ; The calculation method of the disturbance of the wing side force impulse and lift impulse swept by the shock wave is the same.

[0019] S44, sample capacity For each sample size, the Monte Carlo method is used to calculate the aerodynamic impulse of the shock wave swept wing multiple times. The change of the calculated mean with the size of the sampling sample size is analyzed and compared with the theoretical value of the shock wave swept aerodynamic impulse to verify the calculation accuracy of the Monte Carlo method.

[0020] In summary, through calculation, the box diagram of the aerodynamic drag, side force, and lift impulse disturbance of the shock wave swept aircraft wing is as follows: Figure 4As shown in Figure 2, it can be seen that as the sampling sample size increases, the accuracy of the wing aerodynamic impulse calculation results increases. When the sample size reaches When , the maximum value, minimum value, upper and lower quartiles and mean of the box plot are relatively small, which is consistent with the numerical integration calculation results ( ), the aerodynamic drag impulse error is , the aerodynamic drag impulse error is , the aerodynamic drag impulse error is Therefore, the feasibility and accuracy of the Monte Carlo simulation method for calculating the aerodynamic impulse of the shock wave swept aircraft wing are verified.

[0021] Therefore, the present invention adopts the above-mentioned method for calculating the aerodynamic impulse of the wing of a shock wave swept aircraft based on Monte-Carlo simulation, solves the problems existing in the calculation of the aerodynamic impulse of the wing of a shock wave swept aircraft, and verifies the feasibility and accuracy of the method for calculating the aerodynamic impulse of the wing of a shock wave swept aircraft using Monte Carlo simulation.

[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation, characterized in that: The following steps are involved: S1, shock wave swept wing aerodynamic data preprocessing; S2, Monte Carlo two-dimensional random sampling and graphics; S3, determination of relative position interval of discrete data; S4. Determination of the landing point interval and counting statistics.

2. The method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation according to claim 1, characterized in that: Step S1 is specifically as follows: S11, obtain the database and coordinate system of the aircraft wing swept by the shock wave, give the integral direction of the wing aerodynamic force according to the research working conditions, the aerodynamic force includes drag, side force and lift, and calculate the change of shock wave pressure over time; S12, output time step sequence ,in, is the number of time steps, , and according to the sampling time step Output discrete data of the aerodynamic force of the aircraft wing swept by the shock wave over time; S13, cleaning the time-varying data of the aircraft wing drag, side force, and lift under the shock wave sweep in step S12 to remove wild values, and the obtained time-varying sequence sets of the wing aerodynamic data are respectively expressed as: 、 、 .

3. The method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation according to claim 1, characterized in that: Step S2 is specifically as follows: S21. Given random sampling sample size , using a pseudo-random number generator to implement random point sampling, the random point sampling set is , for any point The coordinates of , ; S22, according to step S12 Sequence and step S13 , 、 Sequence, respectively establish the time-varying matrices of the aerodynamic drag, side force, and lift of the wing of the shock wave swept aircraft 、 、 ; S23, write a program to draw 、 、 Two-dimensional distribution scatter plot.

4. The method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation according to claim 1, characterized in that: Step S3 is specifically as follows: S31. Define the floor function: ,in, is a time series, so , To take integer value; S32. For any point in the sample size , get In the time step sequence In order to find the relative position interval middle There are two cases to be discussed: (a) coincides with the endpoint, ; or (b) lie in Between the intervals, ; S33, for any point in the sample capacity ,calculate: ； According to the definition in step S12 、 ,like The time step sequence meets the above S32 (a) case; if The time step sequence meets the situation of type (b) in S32 above.

5. The method for calculating the aerodynamic impulse of a shock wave swept aircraft wing based on Monte-Carlo simulation according to claim 1, characterized in that: Step S4 is specifically as follows: S41, according to the two-dimensional distribution scatter plot in step S2, for any point ,like If the situation meets category (a), then compare The size of the elements corresponding to the time-varying matrices of each aerodynamic force; S42. For any point ,like The following situations meet the requirements of category (b): ； ； ； ； when When it is within the valid interval, we have: ； for: ; like When the above formula is satisfied, The count is accumulated; if If the above formula is not satisfied, then Counts are not cumulative; S43. After the accumulation of random sampling points of aerodynamic forces is completed, the wing drag impulse is calculated: ； in, is the area of ​​the figure, The calculation method of the dynamic pressure, the impulse of the side force of the wing swept by the shock wave, and the disturbance of the lift impulse are the same; S44. Take the sampling capacity For each sampling sample size, the Monte Carlo method is used several times to calculate the aerodynamic impulse of the shock wave swept wing. The change of the calculated mean with the size of the sampling sample size is analyzed and compared with the theoretical value of the shock wave swept aerodynamic impulse to verify the calculation accuracy of the Monte Carlo method.

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