CN110455490A - Calculation method and device for flow field turbulence in supersonic and hypersonic wind tunnels - Google Patents

Abstract

The embodiment of the present invention discloses a method and device for calculating the degree of turbulence in supersonic and hypersonic wind tunnel flow fields. The pulsating post-wave total pressure data and the actual post-wave total pressure fluctuation data; according to the pre-acquired pressure fluctuation conversion coefficient corresponding to the wind tunnel flow field and the actual post-wave total pressure fluctuation data at each moment, the actual The actual wave front venous pressure pulsation data corresponding to the post-wave total pressure pulsation data; each actual post-wave total pressure pulsation data is divided into multiple data segments according to the characteristic time; according to the average value of each post-wave total pressure data without pulsation Calculate the average value of the wavefront static pressure in the wind tunnel flow field within the preset time period according to the first preset formula, and calculate according to the second preset formula based on the average value of the wavefront static pressure and each actual wavefront static pressure fluctuation data The degree of turbulence corresponding to each data segment. The invention can improve the calculation accuracy of the degree of turbulence.

Description

Calculation method and device for flow field turbulence in supersonic and hypersonic wind tunnels

technical field

The invention relates to the technical field of wind tunnel flow field, in particular to a method and device for calculating the turbulence degree of supersonic and hypersonic wind tunnel flow field.

Background technique

The wind tunnel is the main equipment for aircraft and other ground simulation experiments. The aerodynamic data of the aircraft model obtained in the wind tunnel is the basis and basis for aircraft design and future flight tests. The degree of wind tunnel turbulence is a standard to measure the fluctuating degree of airflow velocity in the experimental section of the wind tunnel. In supersonic or hypersonic wind tunnels, hot wire measurements are relatively difficult, and the measurement result is the pulsation of the flow, resulting in an inaccurate assessment of the degree of turbulence. In recent years, in the development of hypersonic vehicles, it has been found that many flight tests have failed due to the flight tests carried out based on the results of ground supersonic/hypersonic wind tunnel experiments. The reason is that the turbulence of the supersonic/hypersonic wind tunnel flow field is usually 1-2 orders of magnitude higher than the turbulence of the incoming flow in the real flight environment of the aircraft, resulting in a large difference between the ground wind tunnel experiment and the real flight experiment . Therefore, to accurately evaluate the turbulence degree of the existing wind tunnel flow field and to study the influence of the turbulence degree on the ground experiment is a concern in the current supersonic/hypersonic flight research.

Contents of the invention

The purpose of the present invention is to provide a calculation method and device for the turbulence degree of the supersonic and hypersonic wind tunnel flow field in view of the deficiencies in the traditional technology.

In one embodiment, the present invention provides a method for calculating the degree of turbulence in a supersonic and hypersonic wind tunnel flow field, comprising:

Obtain the original total pressure data after the shock wave in the wind tunnel flow field within the preset time period, and decompose the original total pressure data at each moment into the post-wave total pressure data without pulsation and the actual post-wave total pressure fluctuation data;

According to the pre-acquired pressure fluctuation conversion coefficient corresponding to the wind tunnel flow field and each actual post-wave total pressure fluctuation data at each moment, calculate the actual wave-front static pressure fluctuation data corresponding to each actual post-wave total pressure fluctuation data;

Divide the actual post-wave total pressure fluctuation data into multiple data segments according to the pre-selected characteristic time;

Calculate the average value of the wave front static pressure corresponding to the wind tunnel flow field within the preset time period according to the average value of the total pressure data after the wave without pulsation, and calculate the average value of the wave front static pressure according to the first preset formula And each actual wavefront static pressure fluctuation data calculates the turbulence degree corresponding to each data segment according to the second preset formula.

In a specific embodiment, the characteristic time is obtained based on the following steps:

The pre-selected feature times are obtained based on the following steps:

Obtain the physical characteristic length of the target object specified in the wind tunnel flow field, and the uniform incoming flow velocity of the wind tunnel experiment section of the wind tunnel flow field;

The ratio of the physical characteristic length to the uniform incoming velocity is taken as the characteristic time.

In a specific embodiment, the second preset formula is:

Among them, I represents the degree of turbulence corresponding to each data segment, Indicates the average value of the corresponding wavefront static pressure within the preset time period; P' ₁ represents the actual wavefront static pressure fluctuation data.

In a specific embodiment, the first preset formula is:

in, Indicates the average value of the wave front static pressure within the preset time period; Ma ₁ indicates the Mach number of the wind tunnel flow field; γ indicates the specific heat ratio of the gas; Represents the mean value of each postwave total pressure data without pulsation.

In a specific embodiment, the pressure fluctuation conversion coefficient corresponding to the pre-acquired wind tunnel flow field is obtained based on the following steps:

According to the obtained wind tunnel flow field under the current working conditions of incoming flow Mach number, shock front total pressure, wind tunnel flow field total temperature, and preset wave front static pressure fluctuation data, through the numerical simulation of wind tunnel flow field The simulation obtains the total pressure fluctuation data after the predicted wave;

The ratio of the pre-set static pressure pulsation data to the predicted post-wave total pressure pulsation data is used as the pressure pulsation conversion factor.

In a specific embodiment, it also includes:

According to the time interval corresponding to each data segment and the degree of turbulence, Fourier transform is performed to obtain the spectrum and power spectrum of the degree of turbulence in the wind tunnel flow field within a preset time period.

In a specific embodiment, the original total pressure data after the shock wave in the wind tunnel flow field is obtained within a preset time period, and the original total pressure data at each moment are decomposed into the post-wave total pressure data without pulsation and the actual The post-wave total pressure pulsation data, including:

Preprocessing the original total pressure data to obtain the post-wave total pressure data without pulsation;

Subtract the post-wave total pressure data without pulsation from the original total pressure data to obtain the actual post-wave total pressure pulsation data.

In a specific embodiment, the preprocessing includes any one of the following preprocessing: polynomial fitting, wavelet decomposition, and empirical mode decomposition.

On the other hand, an embodiment of the present invention also provides a calculation device for the degree of turbulence in a supersonic and hypersonic wind tunnel flow field, including:

The data acquisition and processing module is used to obtain the original total pressure data after the shock wave in the wind tunnel flow field within a preset period of time, and decompose the original total pressure data at each moment into the post-wave total pressure data without pulsation and the actual Post wave total pressure pulsation data;

The pulsation value conversion module is used to calculate the actual value corresponding to each actual post-wave total pressure pulsation data according to the pre-acquired pressure pulsation conversion coefficient corresponding to the wind tunnel flow field and the actual post-wave total pressure pulsation data at each moment. Wavefront static pressure pulsation data;

Segmentation module, for dividing each actual post-wave total pressure pulsation data into multiple data segments according to the pre-selected characteristic time;

The turbulence degree calculation module is used to calculate the average value of the wave front static pressure corresponding to the wind tunnel flow field in the preset time period according to the average value of the total pressure data after the wave without pulsation according to the first preset formula, and according to The average value of the wavefront static pressure and each actual wavefront static pressure fluctuation data are used to calculate the degree of turbulence corresponding to each data segment according to a second preset formula.

On the other hand, an embodiment of the present invention also provides a computer device, including a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the steps of the calculation method for supersonic and hypersonic wind tunnel flow field turbulence are realized .

One of the above technical solutions has the following advantages and beneficial effects:

The method and device for calculating the degree of turbulence in supersonic and hypersonic wind tunnel flow fields of the present invention, by preprocessing the original total pressure data after the shock wave within a preset period of time, decompose the total pressure data after the shock wave without pulsation and the actual The post-wave total pressure fluctuation data can eliminate the influence of non-stationary signal on the calculation of turbulence degree. Furthermore, by converting the actual wavefront static pressure fluctuation data corresponding to the actual wavefront total pressure fluctuation data at each moment, the problem of low precision and inaccurate direct measurement of the wavefront static pressure in the wind tunnel can be avoided. Furthermore, the actual post-wave total pressure fluctuation data at each moment is segmented according to the characteristic time, so that the turbulence degree of the wind tunnel flow field and the law of the turbulence degree changing with time can be calculated and analyzed. Various embodiments of the present invention can make the calculation result of the turbulence degree of the wind tunnel flow field closer to the real situation, improve the calculation accuracy, and provide more detailed data support for analyzing the influence of the turbulence degree on the wind tunnel experiment result.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the following drawings will be briefly introduced in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as It is regarded as limiting the protection scope of the present invention. In the respective drawings, similar components are given similar reference numerals.

Fig. 1 shows a schematic flow chart of a method for calculating the degree of turbulence in a supersonic and hypersonic wind tunnel flow field according to an embodiment of the present invention;

Fig. 2 shows the schematic diagram of the original total pressure data curve after the shock wave in the embodiment of the present invention;

Fig. 3 shows the curve schematic diagram of the total pressure data after the wave without pulsation in the embodiment of the present invention;

Fig. 4 shows the schematic diagram of the curve of the actual post-wave total pressure pulsation data in the present invention;

Fig. 5 shows a schematic structural diagram of a calculation device for flow field turbulence in supersonic and hypersonic wind tunnels according to an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention.

The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

Hereinafter, the terms "comprising", "having" and their cognates that may be used in various embodiments of the present invention are only intended to represent specific features, numbers, steps, operations, elements, components or combinations of the foregoing, And it should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing or adding one or more features, numbers, steps, operations, elements, components or a combination of the foregoing possibilities.

In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present invention belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, Unless clearly defined in various embodiments of the present invention.

Wind tunnels are generally classified by Mach number Ma, 1.4<Ma<5 is a supersonic wind tunnel, and Ma≥5 is a hypersonic wind tunnel. In traditional technology, in the measurement of flow field turbulence in supersonic and hypersonic wind tunnels, pressure fluctuations are often used to measure the turbulence of the wind tunnel. One of the important parameters of reliability. The method of evaluating wind tunnel flow field turbulence with pressure measurement data, in addition to using more accurate methods to measure the pressure fluctuations in the wind tunnel flow field (such as using sensors with high sensitivity and faster frequency response), how to use the original pressure data Calculation of wind tunnel turbulence is also an important link. In traditional techniques, the degree of turbulence is calculated based on the following formula:

Here I is the turbulent flow in the wind tunnel flow field, p ₀₂ is the total pressure after the shock wave at a certain moment in a certain period of time (that is, the pressure data measured by the sensor), p ₀ ′ ₂ is the pulsation value of the total pressure after the shock wave, is the average value of the total post-shock pressure during this period. However, this calculation method can only be aimed at a steady pressure signal (that is, the pressure of the flow field during the operation of the wind tunnel is basically constant without considering the fluctuation). However, the actual operation of most wind tunnels is that the pressure of the flow field may change up and down, such as the pressure gradually rises or falls gradually, or the periodic change of rising and falling. Assuming that the pressure of the flow field increases uniformly during the operation of the wind tunnel, even if the pressure of the flow field does not fluctuate (the degree of turbulence is considered to be zero), a non-zero result of the degree of turbulence can still be calculated according to the above formula, which is inconsistent with the real situation.

On the other hand, the current calculation of the turbulence degree is to calculate the entire measurement signal to obtain the average turbulence degree during the entire measurement process. This parameter can be used as a standard for evaluating the quality of the wind tunnel flow field, but it is based on this data When analyzing the influence of turbulence on the results of wind tunnel experiments, the influence of the frequency and time domain characteristics of turbulence on the experiment is not considered, and there are still problems in such analysis results. It may result in different wind tunnel experiments with the same turbulence value, which have different measured results. Although some studies have considered the frequency characteristics in the wind tunnel turbulence power spectrum, in addition to the influence of the frequency domain characteristics, the influence of the time domain characteristics of the wind tunnel flow field turbulence (turbulence changes with time) on the experimental results cannot be determined. ignore. Even if the frequency domain characteristics of the turbulence are consistent, the difference in the real-time turbulence in the wind tunnel with time will lead to differences in the experimental results.

Referring to Fig. 1 to Fig. 4, the abscissa X in Fig. 2-Fig. 4 represents the sequence number of the sampling data point, which represents the sampling data, and the ordinate kPa represents the pressure. In one embodiment, the present invention provides a method for calculating the degree of turbulence in a supersonic and hypersonic wind tunnel flow field, comprising:

Step S110: Obtain the original total pressure data after the shock wave in the wind tunnel flow field for a preset time period, and decompose the original total pressure data at each moment into the post-wave total pressure data without pulsation and the actual post-wave total pressure heartbeat data.

FIG. 2 is a schematic diagram of the curve of the original total pressure data after the shock wave acquired within a preset time period, and each sampled data point represents a piece of original total pressure data. In order to eliminate the non-stationary characteristics of the flow field pressure signal in the wind tunnel flow field as much as possible, the original total pressure data after the shock wave at each moment is preprocessed and decomposed into the total pressure data after the shock wave without pulsation and the actual total pressure data Post-wave total pressure pulsation data. FIG. 3 shows the total pressure data without pulsation wave over time decomposed from the original total pressure data after the shock wave in FIG. 2 , and each sampling data point represents a total pressure data without pulsation wave. FIG. 4 shows the actual after-wave total pressure pulsation data decomposed from the original post-shock total pressure data in FIG. 2 , and each sampling data point represents an actual after-wave total pressure pulsation data.

The embodiments of the present invention can eliminate the influence of non-stationary changes in the original total pressure data after the shock wave on the calculation of the degree of turbulence, and help to optimize the calculation and accuracy of the degree of turbulence.

In a specific embodiment, the original total pressure data after the shock wave in the wind tunnel flow field is obtained within a preset time period, and the original total pressure data at each moment are decomposed into the post-wave total pressure data without pulsation and the actual The post-wave total pressure pulsation data, including:

Step S2: Preprocessing the original total pressure data to obtain post-wave total pressure data without pulsation.

In a specific embodiment, the preprocessing includes any one of the following preprocessing: polynomial fitting, wavelet decomposition, and empirical mode decomposition.

For example, polynomial fitting is performed on the original total pressure data after the shock wave, and the data on the fitting curve is used as the post-shock total pressure data without pulsation (such as 5th-order polynomial fitting, 7th-order polynomial fitting, etc.); or Perform wavelet decomposition on the original total pressure data after the shock wave, and decompose the signal into low-frequency signals and high-frequency signals of different layers. Adaptive filtering is performed according to the empirical mode decomposition, and the obtained data is used as the post-wave total pressure data without pulsation.

Among them, the polynomial fitting method is more suitable for processing the original total pressure data after the shock wave that gradually rises or falls gradually, and the wavelet decomposition and empirical mode decomposition are more suitable for processing the original total pressure data after the periodically changing shock wave. deal with.

Step S4: subtracting the post-wave total pressure data without pulsation from the original total pressure data to obtain actual post-wave total pressure pulsation data.

The embodiments of the present invention can preprocess the original total pressure data after shock waves with different trends in various ways, which helps to improve the accuracy of data processing.

Step S120: According to the pre-acquired pressure fluctuation conversion coefficient corresponding to the wind tunnel flow field and each actual post-wave total pressure fluctuation data at each moment, calculate the actual wave-front static pressure corresponding to each actual post-wave total pressure fluctuation data heartbeat data.

Among them, the wind tunnel flow field corresponds to a pressure fluctuation conversion coefficient under each working condition, which represents the proportional relationship between the total pressure fluctuation data after the wave and the static pressure fluctuation data before the wave. In the numerical simulation of the flow field, in the analysis of the process of the acoustic wave disturbance with the angle of attack passing through the shock wave, the proportional relationship between the actual static pressure fluctuation data before the wave and the actual total pressure fluctuation data after the wave is provided, as follows, which can be The actual wave-front venous pressure pulsation data corresponding to each actual post-wave total pressure pulsation data is obtained based on the following relational formula:

Among them, P'1 represents the actual wave-front static pressure pulsation data, _P'2 represents the actual wave _- back total pressure pulsation data, is the coefficient obtained by the transfer function of the pressure fluctuation before and after the shock wave, that is, the pressure fluctuation conversion coefficient, which is a certain value in a certain working condition of the wind tunnel flow field, and is used to convert the actual post-wave total pressure fluctuation data corresponding to The actual wavefront venous pressure pulsation data.

Step S130: Divide each actual post-wave total pressure pulsation data into multiple data segments according to the pre-selected characteristic time.

The characteristic time is a length of time. The selection of the characteristic time is related to the wind tunnel experimental model and the characteristics of the flow field. After segmentation, each data segment contains one or more data within the characteristic time. Divide each actual post-wave total pressure pulsation data into multiple data segments according to the pre-selected characteristic time, which can be segmented in the following way: For example, each actual post-wave total pressure pulsation data is equally divided into multiple data segments with the characteristic time as the unit. data segment; or the time length corresponding to each segment of data can be a multiple of the characteristic time, so that each data can be divided into multiple segments, such as the characteristic time is expressed as 1T, then the time corresponding to each segment of data is 1T, 5T, 10T, 0.1 T, 0.5T, etc. Therefore, the embodiment of the present invention is helpful for analyzing the influence of time variation on the degree of turbulence, and improves the analysis accuracy.

In the embodiment of the present invention, each actual post-wave total pressure fluctuation data is segmented according to the selected characteristic time, which helps to obtain the turbulence degree varying with time and the change law of the turbulence degree, thereby improving the wind tunnel test results based on the turbulence degree. analysis accuracy.

Some specific frequencies have a great influence on the wind tunnel flow field, such as boundary layer transition, etc., and the different times of certain specific frequencies have different effects. For example, if a specific frequency appears first, the wind tunnel flow field will be affected, leading to changes in the experimental results. Even if the specific frequency disappears later, the influence of the wind tunnel flow field will not disappear immediately, or even remain. Therefore, the timing of the appearance of the specific frequency may lead to different changes in the flow field and have different effects on the experimental results. Most of the analysis methods in the traditional technology only have a time-averaged turbulence degree result and the corresponding spectrum distribution of the turbulence degree within the entire data period, and ignore the influence of time-varying characteristics, which is not conducive to the analysis of experimental results based on the turbulence degree.

In a specific embodiment, the pre-selected characteristic time is obtained based on the following steps:

Step S6: Obtain the physical characteristic length of the target object specified in the wind tunnel flow field, and the uniform incoming flow velocity of the wind tunnel experiment section of the wind tunnel flow field.

The wind tunnel experiment section is the area where models are placed for experiments. The selection of characteristic time is related to the wind tunnel experimental model and flow field characteristics. For example, the uniform incoming flow velocity of the wind tunnel test section is represented by _Uf as the characteristic velocity, and _Lf is represented by a certain physical size as the characteristic length. The physical characteristic length can be selected according to actual needs. For the shape of a certain aircraft, its length or width can be selected as the characteristic length. If a certain flow structure is concerned, a certain physical length of the structure is used as the physical characteristic length. For example, hypersonic aircraft is more concerned For boundary layer flow, the boundary layer thickness can be chosen as the physical characteristic length.

Step S8: Take the ratio of the physical characteristic length to the uniform incoming flow velocity as the characteristic time.

The embodiment of the present invention determines the characteristic time by specifying the physical characteristic length of the target object and the uniform incoming velocity of the wind tunnel experiment section, which helps to improve the accuracy of calculating the degree of turbulence, and at the same time provides a basis for analyzing the influence of the degree of turbulence on the results of wind tunnel experiments. More detailed data support. Further, in the comparison with the results of similar experiments (i.e., experiments with the same target object), in order to facilitate the extraction of the rules of the experimental results, the same physical parameters as the same type of experiments can be selected, such as the characteristic length of the target object and the wind tunnel experiment section The uniform inflow velocity of the flow rate is used as a characteristic parameter, which is helpful for the analysis of the experimental results and the comparison with the results of similar experiments.

Step S140: Calculate the average value of the wave front static pressure in the wind tunnel flow field within the preset time period according to the average value of the total pressure data after the wave without pulsation, and calculate the average value of the wave front static pressure according to the first preset formula value and each actual wavefront static pressure fluctuation data to calculate the degree of turbulence corresponding to each data segment according to the second preset formula.

In a specific embodiment, the first preset formula is:

in, Indicates the average value of the corresponding wavefront static pressure within the preset time period; Ma ₁ indicates the Mach number of the wind tunnel flow field; γ indicates the gas specific heat ratio; Represents the mean value of each postwave total pressure data without pulsation.

The implementation of the present invention is based on the first preset formula to obtain the average value of the wave front static pressure of the wind tunnel flow field within a preset time period, the calculation process is simple, and the redundancy of the program can be reduced.

In a specific embodiment, the second preset formula is:

Among them, I represents the degree of turbulence corresponding to each data segment, Indicates the average value of the corresponding wavefront static pressure within the preset time period; P' ₁ represents the actual wavefront static pressure fluctuation data. Further, Σ(P' ₁ )2 is the sum of the squares of the corresponding actual wavefront static pressure fluctuation data in each data segment.

The embodiment of the present invention is based on the second preset formula, the sum of the squares of the corresponding actual wavefront static pressure fluctuation data in each data segment, and the average of the wavefront static pressure corresponding to the wind tunnel flow field within a preset time period value, the degree of turbulence at different time periods can be obtained, the calculation is simple, and the calculation accuracy of the degree of turbulence can be improved. At the same time, it is helpful to obtain the change law of turbulence degree with time according to the turbulence degree results of each segment of data, and provide more detailed data for analyzing the influence of turbulence degree on the results of wind tunnel experiments.

The method for calculating the degree of turbulence in the supersonic and supersonic wind tunnel flow field of the embodiment of the present invention, by preprocessing the original total pressure data after the shock wave within a preset period of time, decomposes the total pressure data after the shock wave without pulsation and The actual post-wave total pressure fluctuation data can eliminate the influence of non-stationary signals on the calculation of turbulence degree. Furthermore, by converting the actual wavefront static pressure fluctuation data corresponding to the actual post-wave total pressure fluctuation data at each moment, the problem of low precision and inaccurate direct measurement of the wind tunnel wavefront flow field static pressure can be avoided. Furthermore, the actual post-wave total pressure fluctuation data at each moment is segmented according to the characteristic time, so that the turbulence degree of the wind tunnel flow field and the law of the turbulence degree changing with time can be calculated and analyzed. The embodiment of the present invention can make the calculation result of the turbulence degree of the wind tunnel flow field closer to the real situation, improve the calculation accuracy, and provide more detailed data support for analyzing the influence of the turbulence degree on the wind tunnel experiment result.

In a specific embodiment, it also includes:

According to the time interval corresponding to each data segment and the degree of turbulence, Fourier transform is performed to obtain the spectrum and power spectrum of the degree of turbulence in the wind tunnel flow field within a preset time period.

Each data segment is segmented according to a pre-selected characteristic time. Therefore, the time interval corresponding to each data segment, that is, the length of time, may be a characteristic time or a multiple of the characteristic time. Specifically, the turbulence degree corresponding to each data segment is used as the sample parameter, and the time interval corresponding to each data segment is used as the sampling interval and converted to the frequency used, and the Fourier transform is performed by a function commonly used in Matlab such as the Fourier function , so as to calculate the frequency spectrum and power spectrum of the turbulence degree in the wind tunnel flow field in the preset time period.

The calculation method of the turbulence degree of the supersonic and supersonic wind tunnel flow field in the embodiment of the present invention is based on the time-varying turbulence degree to obtain the frequency spectrum and power spectrum through Fourier transformation, so as to further obtain the law of the turbulence degree changing with time , that is, the spectral distribution and power spectral distribution, which provide a more accurate basis for analyzing the influence of the turbulence degree of the wind tunnel flow field on the experimental results.

In a specific embodiment, the pressure fluctuation conversion coefficient corresponding to the pre-acquired wind tunnel flow field is obtained based on the following steps:

Step S10: According to the acquired flow Mach number, total pressure before the shock wave, total temperature of the wind tunnel flow field, and the preset static pressure fluctuation data of the wind tunnel flow field under the current working condition, pass through the wind tunnel flow field The numerical simulation simulation obtained the predicted total pressure fluctuation data after the wave.

According to the working condition of the wind tunnel flow field determined by the wind tunnel experiment, in order to obtain a more accurate pressure fluctuation conversion coefficient of the wind tunnel flow field under the current working condition, the numerical simulation experiment of the wind tunnel flow field can be calculated in advance . The preset wavefront static pressure fluctuation data can be set manually, and is used to simulate the wavefront static pressure fluctuation of the wind tunnel flow field. Specifically, the parameters of the wind tunnel flow field under the current working conditions are input at the inlet boundary of the numerical simulation, including the incoming flow Mach number of the wind tunnel flow field, the total pressure before the shock wave, the total temperature of the wind tunnel flow field, and the preset Wavefront static pressure pulsation data, so as to simulate the predicted total pressure pulsation data after the wave.

Step S12: The ratio of the pre-set static pressure pulsation data before the wave to the predicted post-wave total pressure pulsation data is used as the pressure pulsation conversion factor.

According to the proportional relationship between the static pressure pulsation before the wave, the total pressure pulsation after the wave, and the transfer functions before and after the shock wave, that is, the relational expression of the above-mentioned embodiment: Replace the preset static pressure fluctuation data before the wave with P' ₁ , and replace the predicted total pressure fluctuation data after the wave by numerical simulation with P' ₂ . The ratio of the pressure fluctuation data is used as the pressure fluctuation conversion coefficient, which determines the corresponding pressure fluctuation conversion coefficient under the current working condition of the wind tunnel flow field

The method for calculating the degree of turbulence in the supersonic and hypersonic wind tunnel flow field of the embodiment of the present invention can be based on the current working conditions of the specific wind tunnel flow field and the proportional relationship between the static pressure fluctuation data and the post-wave total pressure fluctuation data , to obtain a high-precision pressure pulsation conversion factor. Therefore, based on the pressure fluctuation conversion coefficient, the actual wave-front static pressure fluctuation data can be converted according to the actual wave-back total pressure fluctuation data, so that the turbulence degree can be calculated by using the actual wave-front static pressure fluctuation data and the average value of the wave-front static pressure, so that the wind The calculated results of the turbulence in the cave flow field are closer to the real situation.

According to the definition of the degree of turbulence, the degree of turbulence is calculated from the pressure data. The pressure data here refers to the static pressure data of the wind tunnel flow field, but the supersonic and hypersonic wind tunnels usually use the total after shock wave measured by the pitot tube. Compress data. Therefore, the degree of turbulence calculated by the total pressure data after the shock wave is different from the degree of turbulence calculated by the static pressure, while the calculation by the data of the static pressure and the static pressure fluctuation is more in line with the definition of the degree of turbulence.

Referring to Fig. 5, in one embodiment, the present invention also provides a calculation device for supersonic and hypersonic wind tunnel flow field turbulence, including:

The data acquisition and processing module 510 is used to acquire the original total pressure data after the shock wave in the wind tunnel flow field within a preset time period, and decompose the original total pressure data at each moment into the post-wave total pressure data without pulsation and the actual The post-wave total pressure pulsation data.

The pulsation value conversion module 520 is used to calculate the corresponding value of each actual post-wave total pressure pulsation data according to the pre-acquired pressure pulsation conversion coefficient corresponding to the wind tunnel flow field and each actual post-wave total pressure pulsation data at each moment. Actual wavefront venous pulsation data.

The segmentation module 530 is configured to divide each actual post-wave total pressure pulsation data into multiple data segments according to the pre-selected characteristic time.

The turbulence degree calculation module 540 is used to calculate the average value of the wave front static pressure of the wind tunnel flow field in the preset time period according to the average value of the total pressure data after the wave without pulsation according to the first preset formula, and according to the wave The average value of the front static pressure and the fluctuation data of each actual wave front static pressure calculate the turbulence degree corresponding to each data segment according to the second preset formula.

The calculation device for the degree of turbulence in the supersonic and supersonic wind tunnel flow field of the embodiment of the present invention, by preprocessing the original total pressure data after the shock wave within a preset period of time, decomposes the total pressure data after the shock wave without pulsation and The actual post-wave total pressure fluctuation data can eliminate the influence of non-stationary signals on the calculation of turbulence degree. Furthermore, by converting the actual wavefront static pressure fluctuation data corresponding to the actual wavefront total pressure fluctuation data at each moment, the problem of low precision and inaccurate direct measurement of the wavefront static pressure in the wind tunnel can be avoided. Furthermore, the actual post-wave total pressure fluctuation data at each moment is segmented according to the characteristic time, so that the turbulence degree of the wind tunnel flow field and the law of the turbulence degree changing with time can be calculated and analyzed. The embodiment of the present invention can make the calculation result of the turbulence degree of the wind tunnel flow field closer to the real situation, improve the calculation accuracy, and provide more detailed data support for analyzing the influence of the turbulence degree on the wind tunnel experiment result.

In a specific embodiment, it also includes:

The feature acquisition module is used to acquire the physical characteristic length of the target object specified in the wind tunnel flow field, and the uniform incoming flow velocity of the wind tunnel experiment section of the wind tunnel flow field.

The characteristic time calculation module is used to use the ratio of the physical characteristic length to the uniform incoming flow velocity as the characteristic time.

In a specific embodiment, also include:

The numerical simulation module is used to obtain the incoming flow Mach number, the total pressure before the shock wave, the total temperature of the wind tunnel flow field, and the preset static pressure fluctuation data of the wind tunnel flow field under the current working conditions, through The numerical simulation of the wind tunnel flow field obtains the predicted post-wave total pressure fluctuation data.

The conversion coefficient calculation module is used to use the ratio of the pre-wave static pressure fluctuation data to the predicted total pressure fluctuation data after the wave as the pressure fluctuation conversion coefficient.

In a specific embodiment, also include:

The transformation module is used to perform Fourier transformation according to the time interval and turbulence degree corresponding to each data segment, so as to obtain the frequency spectrum and power spectrum of the turbulence degree of the wind tunnel flow field within a preset time period.

In a specific embodiment, the data acquisition processing module includes:

The first preprocessing unit is configured to preprocess the original total pressure data to obtain post-wave total pressure data without pulsation.

The second preprocessing unit is used to subtract the post-wave total pressure data without pulsation from the original total pressure data to obtain actual post-wave total pressure pulsation data.

For the specific limitations of the calculation device for the turbulence degree of the supersonic and hypersonic wind tunnel flow field, please refer to the above-mentioned limitation of the calculation method for the turbulence degree of the flow field of the supersonic and hypersonic wind tunnel, and will not be repeated here. Each module in the above-mentioned computing device for the degree of turbulence in the flow field of supersonic and hypersonic wind tunnels can be fully or partially realized by software, hardware and combinations thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, and can also be stored in the memory of the computer device in the form of software, so that the processor can invoke and execute the corresponding operations of the above-mentioned modules.

In one embodiment, the present invention also provides a computer device, including a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the steps of the calculation method for supersonic and hypersonic wind tunnel flow field turbulence are realized .

The computer equipment may be a terminal, and the computer equipment includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. Wherein, the processor of the computer device is used to provide calculation and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by a processor, a method for calculating the turbulence degree of a supersonic and hypersonic wind tunnel flow field is realized. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a button, a trackball or a touch pad provided on the casing of the computer device , and can also be an external keyboard, touchpad, or mouse.

In one implementation, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, a method for calculating turbulence in supersonic and hypersonic wind tunnel flow fields is realized.

In the several embodiments provided in this application, it should be understood that the disclosed devices and methods may also be implemented in other ways. The device embodiments described above are only illustrative. For example, the flow charts and structural diagrams in the accompanying drawings show the possible implementation architecture and functions of devices, methods and computer program products according to multiple embodiments of the present invention. and operation. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code that includes one or more Executable instructions. It should also be noted that, in alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or they may sometimes be executed in the reverse order, depending upon the functionality involved. It is also to be noted that each block of the block diagrams and/or flow diagrams, and combinations of blocks in the block diagrams and/or flow diagrams, can be implemented by a dedicated hardware-based system that performs the specified function or action. may be implemented, or may be implemented by a combination of special purpose hardware and computer instructions.

In addition, each functional module or unit in each embodiment of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a smart phone, a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes. .

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention.

Claims (10)

1. A calculation method for supersonic and hypersonic wind tunnel flow field turbulence, characterized in that it comprises: Obtain the original total pressure data after the shock wave in the wind tunnel flow field within the preset time period, and decompose the original total pressure data at each moment into the post-wave total pressure data without pulsation and the actual post-wave total pressure fluctuation data; According to the pre-acquired pressure fluctuation conversion coefficient corresponding to the wind tunnel flow field and each actual post-wave total pressure fluctuation data at each moment, calculate the actual wave-front static pressure fluctuation corresponding to each actual post-wave total pressure fluctuation data data; Divide the actual post-wave total pressure pulsation data into multiple data segments according to the pre-selected characteristic time; Calculate the average value of the wave front static pressure corresponding to the wind tunnel flow field in the preset time period according to the average value of the total pressure data after the wave without pulsation according to the first preset formula, and according to the wave The average value of the front static pressure and each of the actual wave front static pressure fluctuation data is used to calculate the degree of turbulence corresponding to each of the data segments according to a second preset formula. 2. according to the calculation method of supersonic speed and hypersonic speed wind tunnel flow field turbulence degree according to claim 1, the described characteristic time of preselection obtains based on the following steps: Obtain the physical characteristic length of the target object specified in the wind tunnel flow field, and the uniform incoming flow velocity of the wind tunnel experiment section of the wind tunnel flow field; The ratio of the physical characteristic length to the uniform incoming flow velocity is taken as the characteristic time. 3. supersonic speed according to claim 1 and the calculation method of hypersonic speed wind tunnel flow field turbulence degree, it is characterized in that, described second preset formula is: Wherein, I represents the degree of turbulence corresponding to each said data segment, Represents the average value of the corresponding wavefront static pressure within the preset time period; _P'1 represents the actual wavefront static pressure fluctuation data. 4. supersonic speed according to claim 1 and the calculation method of hypersonic speed wind tunnel flow field turbulence degree, it is characterized in that, described first preset formula is: in, Represents the average value of the corresponding wavefront static pressure within the preset time period; Ma ₁ represents the Mach number of the wind tunnel flow field; γ represents the gas specific heat ratio; Represents the mean value of each postwave total pressure data without pulsation. 5. The method for calculating supersonic and hypersonic wind tunnel flow field turbulence according to claim 1, wherein the pressure fluctuation conversion coefficient corresponding to the wind tunnel flow field obtained in advance is obtained based on the following steps: According to the obtained Mach number of the incoming flow of the wind tunnel flow field under the current working condition, the total pressure before the shock wave, the total temperature of the wind tunnel flow field, and the preset static pressure fluctuation data of the wave front, through the flow field of the wind tunnel Numerical simulation to obtain the total pressure fluctuation data after the predicted wave; The ratio of the preset wave-front venous pressure pulsation data to the predicted post-wave total pressure pulsation data is used as the pressure pulsation conversion factor. 6. supersonic speed according to claim 1 and the calculating method of hypersonic wind tunnel flow field turbulence degree, it is characterized in that, also comprise: Perform Fourier transform according to the time interval corresponding to each data segment and the degree of turbulence to obtain the frequency spectrum and power spectrum of the degree of turbulence in the wind tunnel flow field within the preset time period. 7. The calculation method of supersonic and hypersonic wind tunnel flow field turbulence according to any one of claims 1 to 6, characterized in that the original total pressure data after the shock wave in the wind tunnel flow field preset time period is obtained , and decompose the original total pressure data at each moment into post-wave total pressure data without pulsation and actual post-wave total pressure pulsation data, including: Preprocessing the original total pressure data to obtain the post-wave total pressure data without pulsation; Subtracting the post-wave total pressure data without pulsation from the original total pressure data to obtain the actual post-wave total pressure pulsation data. 8. The calculation method of supersonic and hypersonic wind tunnel flow field turbulence according to claim 7, wherein said preprocessing comprises any of the following preprocessing: polynomial fitting, wavelet decomposition and empirical mode decomposition . 9. A computing device for supersonic and hypersonic wind tunnel flow field turbulence, characterized in that it comprises: The data acquisition and processing module is used to obtain the original total pressure data after the shock wave in the wind tunnel flow field within a preset time period, and decompose the original total pressure data at each moment into the post-wave total pressure data without pulsation and Actual post-wave total pressure pulsation data; The pulsation value conversion module is used to calculate the corresponding value of each actual post-wave total pressure pulsation data according to the pre-acquired pressure pulsation conversion coefficient corresponding to the wind tunnel flow field and each actual post-wave total pressure pulsation data at each moment. The actual wavefront static pressure pulsation data; Segmentation module, used to divide each of the actual post-wave total pressure pulsation data into multiple data segments according to the pre-selected characteristic time; A turbulence degree calculation module, configured to calculate the average value of the wave front static pressure of the wind tunnel flow field within the preset time period according to the first preset formula based on the average value of each post-wave total pressure data without pulsation, And according to the average value of the wavefront static pressure and each of the actual wavefront static pressure fluctuation data, the degree of turbulence corresponding to each of the data segments is calculated according to a second preset formula. 10. A computer device, characterized in that it comprises a memory and a processor, the memory stores a computer program, wherein the processor executes the computer program described in any one of claims 1 to 8. Calculation method of turbulence in supersonic and hypersonic wind tunnel flow field described above.