CN118094958B - Design method of simplified model of jet oscillator - Google Patents
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Abstract
The invention provides a design method of a simplified model of a jet oscillator, which comprises the following steps: dividing a jet outlet plane into a plurality of areas, and setting measuring points at the center point of each area; acquiring time-course speed data of each measuring point, and analyzing the speed characteristics of the corresponding area; judging the similarity of the speeds of different areas; drawing a strong similar measuring point thermodynamic diagram based on the judgment result; dividing an equivalent region; the same velocity function is used to describe each equivalent region of similar velocity patterns. The invention achieves the purpose of simplifying the simulation model of the jet oscillator, has good similarity with the simulation result and experimental test result of the complete model, shows that the simplified model can effectively and accurately represent jet behavior, provides a new mode for jet related flow control research, greatly saves future computing resources and improves computing efficiency.
Description
Technical Field
The invention relates to the technical field of oscillation jet simulation, in particular to a design method of a jet oscillator simplified model.
Background
In the numerical simulation calculation of oscillating jet flow in the high-speed train or other fields, in order to better reproduce the internal flow field and the external flow field of the jet flow oscillator, the total number of grids required by the numerical simulation calculation exceeds 2800 ten thousand, and in order to better reproduce the external flow field and aerodynamic force calculation of the high-speed train and the like, the total number of grids required by the numerical simulation calculation exceeds 3700 ten thousand, and the minimum grid size in the grid strategy of the high-speed train is 160 times of the minimum grid size in the grid strategy of the jet flow oscillator. Therefore, if the complete fluidic oscillators are arranged on a high-speed train, the total number of grids required for numerical simulation calculation is increased sharply, and the total number of grids is increased continuously along with the increase of the number of the fluidic oscillators, which greatly increases the cost of the numerical simulation calculation and seriously affects the efficiency of the numerical simulation calculation.
Disclosure of Invention
The purpose of the invention is that: aiming at the defects in the background art, the design method of the simplified model of the jet oscillator is provided, so that the total number of grids is obviously reduced under the same grid strategy, the numerical simulation calculation cost is reduced, and the numerical simulation calculation efficiency is improved.
In order to achieve the above object, the present invention provides a method for designing a simplified model of a fluidic oscillator, comprising the steps of:
s1, dividing a jet outlet plane into a plurality of areas, and setting measuring points at the center point of each area;
S2, acquiring time-course speed data of each measuring point, and analyzing the speed characteristics of the corresponding area;
s3, judging the similarity of the speeds of different areas;
S4, drawing a strong similar measuring point thermodynamic diagram based on the judgment result;
S5, dividing equivalent areas;
S6, describing each equivalent area with similar speed type by using the same speed function.
Further, the jet outlet velocity is determined by the sweep direction velocityAnd flow velocityDominant, and sweeping direction speedHas strong symmetry and strong periodicity.
Further, the areas divided by the plane of the jet outlet are distributed in a thin middle and dense surrounding, data analysis is preferentially carried out on the lower half area of the jet outlet along the sweeping direction, a corresponding speed model is established, and finally the speed model of the upper half area is obtained through mirroring, positive-negative conversion and phase adjustment.
Further, in S3, waveform, phase and amplitude characteristic parameters of the speed time-course curves of the areas of each measuring point are synthesized to judge the similarity of the speeds of different areas.
Further, the waveform and phase similarity of the velocity time-course curve in S3 are evaluated by the cross-correlation coefficient obtained by the cross-correlation function calculation and the corresponding delay time, and the amplitude similarity is evaluated by the main frequency amplitude obtained by the fast fourier transform.
Further, the cross-correlation function is descriptive of a random signal、At any two different moments、The degree of correlation between the values of (2) is defined as:
；
Completing random signals AndAfter the cross-correlation function is calculated, the cross-correlation function is calculatedNormalized to obtain cross-correlation coefficientCross-correlation coefficientThe magnitude of the value of (2) reflects the relative strength of the two signals.
Further, the cross-correlation coefficient of two signalsThe waveforms of the two signals are not smaller than a preset value and represent that the waveforms of the two signals meet the similar requirement, and the cross-correlation coefficients of the two signalsTime difference corresponding to maximum valueThe magnitude of the delay time reflects the phase difference between the two signals, which is the delay time between the two signals.
Further, the main frequency amplitude values of the signals are obtained through fast Fourier transformation, and the difference of the main frequency amplitude values of the two signals does not exceed a preset value, so that the amplitude values of the two signals meet the requirement of similarity.
Further, in S4, the cross-correlation coefficient and the delay time meeting the requirements are plotted into a strong similar measurement point thermodynamic diagram, the horizontal coordinate and the vertical coordinate in the thermodynamic diagram are measurement point numbers for performing cross-correlation calculation, the measurement points meeting the similar requirements are marked by different colors, the color bars correspond to the numerical ranges meeting the similar requirements, and simultaneously, the main frequency amplitude thermodynamic diagram is plotted, and the thermodynamic diagram is colored at an instantaneous speed.
Further, for an area composed of a plurality of measuring points, when each measuring point is similar to each other, the area is an equivalent area, when each measuring point of another area is similar to each measuring point of the area, the other area and the area are equivalent areas until all lower half areas are divided, and finally, the division of all areas is completed through mirror images.
Further, for the case of、The divided equivalent areas are different.
The scheme of the invention has the following beneficial effects:
according to the design method of the simplified model of the jet oscillator, provided by the invention, the plane of the jet outlet is divided into a plurality of equivalent areas according to the similarity principle, and an equivalent function is adopted as the speed input for each equivalent area, so that the purpose of simplifying the simulation model of the jet oscillator is achieved, good similarity exists between the simulation results of the simplified model and the complete model and between the simulation results and the experimental test results, the simplified model can effectively and accurately represent the jet behavior, a new mode is provided for the flow control research related to the jet, future calculation resources are greatly saved, and the calculation efficiency is improved;
other advantageous effects of the present invention will be described in detail in the detailed description section which follows.
Drawings
FIG. 1 is a flow chart of the steps of the present invention;
FIG. 2 is a graph of velocity profile at the center point of the jet outlet in the present invention, where (a) is the outlet velocity 19m/s and (b) is the outlet velocity 30m/s;
FIG. 3 is a cloud of different average velocity components of the jet outlet of the present invention, wherein (a) is the average velocity in the sweep direction and (b) is the average velocity in the flow direction;
FIG. 4 is a jet outlet velocity measurement point arrangement in accordance with the present invention;
FIG. 5 is a graph showing velocity profiles at different points of the present invention at a jet exit velocity of 45m/s, where (a) is 41 number, (b) is 45 number, (c) is 51 number, and (d) is 55 number;
FIG. 6 is a schematic view of the present invention The time course curve is strong in a similar measuring point thermodynamic diagram, wherein (a) is a cross-correlation coefficient, and (b) is delay time;
FIG. 7 is a schematic view of the present invention The time course curve is strong in a similar measuring point thermodynamic diagram, wherein (a) is a cross-correlation coefficient, and (b) is delay time;
FIG. 8 is a main frequency amplitude thermodynamic diagram of the velocity component at the bottom half of the plot of the present invention, where (a) is Amplitude of dominant frequency, (b)A dominant frequency amplitude value;
FIG. 9 is a schematic diagram of the equivalent zoning of the present invention;
FIG. 10 is a schematic diagram of equivalent region division in the present invention, wherein (a) is a velocity component (B) is the velocity component；
FIG. 11 shows the time-averaged velocity iso-surface and the average Q-surface in the present invention, wherein (a) is the test monitoring result and (b) is the calculation result of the complete model value; (c) calculating results for simplified model values;
FIG. 12 is a single component of the present invention An isosurface, wherein (a) is a test monitoring result, and (b) is a complete model numerical calculation result; (c) the result of the model numerical calculation is simplified.
Detailed Description
Other advantages and effects of the present disclosure will become readily apparent to those skilled in the art from the following disclosure, which describes embodiments of the present disclosure by way of specific examples. It will be apparent that the described embodiments are merely some, but not all embodiments of the present disclosure. The disclosure may be embodied or practiced in other different specific embodiments, and details within the subject specification may be modified or changed from various points of view and applications without departing from the spirit of the disclosure. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, based on the embodiments in this disclosure are intended to be within the scope of this disclosure.
It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concepts of the disclosure by way of illustration, and only the components related to the disclosure are shown in the illustrations, rather than being drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex. In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.
As shown in fig. 1, an embodiment of the present invention provides a method for designing a simplified model of a fluidic oscillator, which aims at carrying out a related study of a swept jet by replacing the simplified model with a complete fluidic oscillator. In this embodiment, the fluidic oscillator is simplified, and components such as a fluid inlet, an oscillation chamber, a feedback channel and the like in the fluidic oscillator are eliminated, so that only the fluidic outlet and the expansion cavity are reserved. Meanwhile, a reasonable swept jet mathematical model is established by researching the speed distribution and change rule at the jet outlet, so that a simplified model can generate a flow field structure basically similar to an external flow field of a complete jet oscillator.
The establishment of a mathematical model of a swept jet first requires the determination of the velocity distribution and the law of variation at the jet outlet. Wherein the jet outlet speed is determined by the sweep direction speedAnd flow velocityDominant, spanwise velocityNot only the value is relatively small, but also the amplitude of the change is small and negligible, therefore, the sweep direction speedAnd flow velocityIs the main study object of the swept jet mathematical model.
FIG. 2 shows the exit velocityVelocity component time course curves at the jet outlet center point at 19 m/s and 30 m/s, respectively. As can be seen from the view of figure 2,AndThe time course curves of (c) exhibit significant periodic oscillations, and resemble a sinusoidal curve, wherein,Is in the time course curve of (2)The vertical oscillation is carried out,Is in the time course curve of (2)Oscillating up and down. Furthermore, withIs used for the increase of (a),AndThe amplitude and oscillation frequency of (a) are both increased in proportion.
FIG. 3 shows the exit velocityCloud of different average velocity components at the jet outlet at 45 m/s. As can be seen from fig. 3 (a), the average velocity in the sweeping directionIs symmetrically distributed along the central line of the jet outlet and is arranged at the position of the spanwise central lineClose to 0, but closer to both sides of the jet outlet,The larger the absolute value of (c). As can be seen from FIG. 3 (b), the average velocity of the flow directionAlso symmetrically distributed along the center line of the jet outlet, and the closer to the center of the jet outlet,The closer the value of (2)And at the boundary of the two sides of the jet outlet,Is reduced to a minimum value, which is caused by the sweeping behaviour of the jet. In addition, as can be seen from the cloud, there is a difference in velocity and distribution of different areas at the jet outlet plane, and the difference becomes larger gradually from the center to the periphery. Thus, the velocity at the jet exit plane is difficult to describe using only one mathematical formula.
In order to further ascertain the velocity distribution and change rule at the jet outlet, in this embodiment, the plane of the jet outlet is divided into 100 areas based on the velocity distribution in the aforementioned average velocity component cloud chart, and corresponding velocity measuring points are set at the center point of each area, so as to exhibit the distribution characteristics of thin middle and dense periphery, as shown in fig. 4. Meanwhile, each measuring point is numbered in the format ofI.e. edgeDirection settingNumber asEdge of the flangeDirection settingNumber as. When (when)In the case of the number of the particles being 10,1, The water is fed into the reactor,Is 0. For example: Represents a number 27 measuring point, Representing measurement points 60.
FIG. 5 shows jet exit velocityTime course curves of speed at different measuring points. As can be seen from FIG. 5, there may be a large difference in the velocity time-course curves at different points, e.g., 41 and 45 points, at both pointsThough the frequency and average value are similar, the amplitude is quite different, and the two measuring points areThere are large differences in the mean value of the time course curve and the amplitude. However, the velocity time-course curves at two adjacent measuring points may be very similar, for example, the 41 st measuring point and the 51 st measuring point, the 45 st measuring point and the 55 st measuring point, and although the average value and the amplitude at the same time have a certain difference in the numerical value, the difference is small and can be ignored as a whole. Thus, the same velocity function can be used to describe velocity-type similar jet outlet areas, further simplifying and building a reasonable mathematical model of the swept jet.
It should be noted that, the existing calculation data, result analysis and related research on the flow characteristics of the sweeping jet show that the sweeping jet has the flow characteristics of strong symmetry and strong periodicity. Therefore, in order to more efficiently develop the research work of the velocity characteristics of the jet outlet, in this embodiment, data analysis is preferentially performed on the lower half region of the jet outlet along the sweep direction, that is, velocity data obtained from the number 1 measuring point to the number 50 measuring point, a corresponding velocity model is established, and finally, the velocity model of the upper half region is obtained through mirroring, positive-negative conversion, phase adjustment and other manners.
Considering the characteristics of different velocity components at the jet outlet, the similarity of the velocities of different areas needs to be judged by integrating the characteristic parameters such as waveform, phase, average value, amplitude and the like of the velocity time course curve of each measuring point area. Waveform and phase similarity of the velocity time-course curve can be evaluated by cross-correlation coefficients obtained by cross-correlation function calculation and corresponding delay times. The cross-correlation function is a description of random signals、At any two different moments、The degree of correlation between the values of (2) is defined as:
；
It can be seen from the definition that the cross-correlation function is similar to the convolution operation, and is also a sliding multiplication of two sequences, but differs in that: the two sequences of the cross-correlation are not turned over, and the two sequences are directly multiplied and summed in a sliding way; one of the sequences of the convolution needs to be flipped first, then sliding multiplied and summed. Thus, the first and second substrates are bonded together, AndMaking cross-correlation calculations equal toAnd (3) withAnd (5) performing convolution. The cross-correlation function may better reflect the similarity between two sequences or functions, whose maxima also reflect the periodic components when both sequences or functions have the same periodic components. Completing random signalsAndAfter the cross-correlation function is calculated, the cross-correlation function is calculatedNormalized to obtain cross-correlation coefficientCross-correlation coefficientThe magnitude of the value of (c) may reflect the correlation strength of the two signals, i.e., the degree of waveform similarity. The following table gives the cross-correlation coefficientThe magnitude of the value corresponds to the correlation strength.
Table 1: correlation strength corresponding to value of cross correlation coefficient
In the present embodiment, the cross-correlation coefficient of two velocity signals with similar waveforms is setNot less than 0.8. At the same time, the cross-correlation coefficient of two signalsTime difference corresponding to maximum valueNamely, the delay time between the two signals, and the magnitude of the delay time can reflect the phase difference between the two signals. In the present embodiment, the delay time of two speed signals with close phases is set to be 5% of the single sweep period timeIn this case, the jet outlet velocityCorresponding to0.013S.
In this embodiment, commercial MATLAB is used to calculate the cross-correlation function of the velocity component time-course curves of 100 measuring points, and the correlation coefficient and delay time meeting the requirements are drawn into a related strong similar measuring point thermodynamic diagram, as shown in fig. 6 and 7. In this embodiment, cross-correlation calculation is performed on any two measurement points, the horizontal coordinate and the vertical coordinate in the thermodynamic diagram are measurement point numbers for performing cross-correlation calculation, and the color bar on the right side gives a numerical range meeting the similar requirement, so that only the result meeting the requirement in the upper triangle area is colored in the thermodynamic diagram, and the results not meeting the requirement, the self-similarity and the lower triangle area are all displayed as white. As can be seen from fig. 6, the central region satisfiesThe number of the measuring points required by the waveform similarity of the time-course curve is more, and the areas close to the two sides of the jet outlet meet the requirementThe similar requirement of the time course curve waveform requires a smaller number of measuring points, but most of the measuring points are from the delay timeThe phase difference of the time course curves is small. As can be seen from FIG. 7, most of the stationsThe cross-correlation coefficient of the time-course curve meets the similar requirement, and from the aspect of delay time, the number of the measuring points meeting the requirement of delay time is more scattered.
In this embodiment, the amplitude of the velocity component time-course curve is also an important reference parameter for determining the similarity of the velocities of different regions. However, through preliminary analysis, the velocity amplitude of the swept jet fluctuates greatly, and even the velocity time-course curve amplitude of the same measuring point can have a large difference at different moments, especially the velocity amplitude in the sweeping direction has a large absolute value difference of positive and negative amplitude, as shown in fig. 5. Therefore, determining the magnitudes of the velocity components of the different regions by only the maximum peak of the time course curve is inaccurate. Considering that each velocity component time-course curve is a discrete signal, in order to obtain an amplitude value that can accurately represent the amplitude of each velocity component time-course curve, signal processing is performed on the velocity component time-course curve by using a discrete fourier transform (Discrete Fourier Transform, abbreviated as DFT). The definition of DFT is derived from fourier transform and the definition formula is as follows:
In the middle of The number of points being a time domain discrete signal,Numbering of discrete signals in the time domain (the range of values is），Numbering of the frequency domain signals (the range of values is) The number of points of the frequency domain signal is also，Also known as twiddle factor. According to the Euler formula:
the final DFT may be written in the form:
DFT is a form in which the fourier transform takes on discrete form in both the time and frequency domains, transforming samples of the time domain signal into samples in the discrete time fourier transform (DISCRETE TIME Fourier Transform, DTFT) frequency domain. Formally, the sequences at both ends of the transform (in the time and frequency domains) are finite, and in practice both sets of sequences should be considered as the dominant sequence of discrete periodic signals, which should be considered as being transformed after a period continuation into periodic signals even if DFT is performed on the finite-length discrete signals. The fast fourier transform (Fast Fourier Transform, FFT for short) is a generic term of an efficient and fast computing method using computer computing, and by adopting this algorithm, the number of multiplications required for computing DFT by the computer can be greatly reduced, and the computing efficiency can be greatly improved. The specific implementation formula of the FFT is as follows:
In the middle of . And carrying out FFT operation on each speed component time-course curve of 50 measuring points in the lower half area of the jet outlet by adopting commercial mathematical software MATLAB, and extracting the main frequency and the corresponding amplitude of each measuring point speed time-course curve.
FIG. 8 shows the points of the lower half of the jet outletAndThe main frequency amplitude of the time course curve, and coloring the thermodynamic diagram at a speed range of 0-60 m/s. As can be seen from figure 8 (a),The amplitude variation of the main frequency of the (A) is larger, wherein, the measurement points 41 and 50 areThe main frequency amplitude reaches the maximum value of 57 m/sThe areas with larger main frequency amplitude are concentrated near the two measuring points, and 1-10 measuring pointsThe main frequency amplitude is within 6-9 m/s, and the jet inlet is the jet inletThe region where the dominant frequency amplitude is minimal. As can be seen from figure 8 (b),The amplitude variation of the main frequency is smaller and is larger than 30m/sThe region of greater dominant frequency amplitude is concentrated in the central region of the jet inlet. In additionAndThe main frequency amplitude values of the time course curves of the (4) all show bilateral symmetry distribution characteristics.
Therefore, the equivalent regions can be divided based on fig. 6, 7, 8, and it is apparent that for、The divided equivalent areas are different. The division in this embodiment is that the areas satisfying the speed similarity requirement are merged into the same area, and the speed change of the entire area is expressed by the same speed function. The following requirements need to be met for the measurement points in the velocity-similar region: the cross correlation coefficient of the speed time course curves of any two measuring points is not less than 0.8; the delay time of the speed time course curve of any two measuring points is not more than; The difference value of the main frequency amplitude values of the speed time course curves of any two measuring points is not more than 5%. For a certain area composed of four measuring points, when the four measuring points are similar in pairs (the cross-correlation coefficient, the delay time and the main frequency amplitude meet the similar requirements), the area is an equivalent area, and for another area, when the measuring points of the other area are similar in pairs to the measuring points of the area, the other area and the area are equivalent areas, and the like, until the lower half area is divided, the division of the whole area is finished in a mirror image mode, and approximation is performed to a certain extent, so that the shape of each equivalent area is regular, and the setting is convenient, as shown in fig. 9 and 10. After the dividing work of the speed similar area in the lower half area is completed, the speeds of all measuring points in the similar area are averaged, the speed difference among the measuring points is further reduced, and MATLAB software is used for performing sine and cosine function fitting on the averaged component speed data, so that a sweep jet equivalent function model of the lower half area is finally obtained. Tables 2 and 3 show velocity components of similar regions of jet exit velocityAndIs a partial fit function of (c). Wherein the velocity component at the jet outletExhibits the characteristics of up-down symmetry and opposite positive and negative, and the equivalent functions of the same numbered regions are different by half period, so that the region numbers in the upper half region are added with suffixesThe area numbers of the lower half area are added with suffixesNegative signs are added to the fitting function formulas in the lower half area, positive and negative are kept opposite to the fitting function formulas of the same patch in the upper half area, and meanwhile, the fitting function of the same patch in the upper half area is shifted for half a period and kept in the same phase with the fitting function formulas in the lower half area.
Table 2: velocity similar region velocity componentFitting function
Table 3: velocity similar region velocity componentFitting function
Therefore, the equivalent functions corresponding to the jet flow region division are respectively input into CFD software as flow rates for simulation calculation, and compared with the complete model numerical calculation and experimental test results, the simplified model has good similarity with the complete model simulation results and experimental test results, and as shown in fig. 11 and 12, the simplified model is illustrated to effectively and accurately characterize jet flow behaviors, a new mode is provided for jet flow related flow control research, and future calculation resources are greatly saved.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of the application should be assessed as that of the appended claims.
Claims (3)
1. The design method of the simplified model of the jet oscillator is characterized by comprising the following steps of:
s1, dividing a jet outlet plane into a plurality of areas, and setting measuring points at the center point of each area;
S2, acquiring time-course speed data of each measuring point, and analyzing the speed characteristics of the corresponding area;
s3, judging the similarity of the speeds of different areas; the waveform, the phase and the amplitude characteristic parameters of the speed time course curve of each measuring point area are synthesized to judge the similarity of the speeds of different areas;
Waveform and phase similarity of the speed time-course curve are evaluated through a cross-correlation coefficient obtained through cross-correlation function calculation and corresponding delay time, and amplitude similarity is evaluated through a main frequency amplitude obtained through fast Fourier transformation;
the cross-correlation function is a description of random signals 、At any two different moments、The degree of correlation between the values of (2) is defined as:
；
Completing random signals AndAfter the cross-correlation function is calculated, the cross-correlation function is calculatedNormalized to obtain cross-correlation coefficientCross-correlation coefficientThe magnitude of the value of (2) reflects the relative strength of the two signals;
cross-correlation coefficient of two signals The waveforms of the two signals are not smaller than a preset value and represent that the waveforms of the two signals meet the similar requirement, and the cross-correlation coefficients of the two signalsTime difference corresponding to maximum valueThe delay time between two signals is the delay time, and the magnitude of the delay time reflects the phase difference between the two signals;
The main frequency amplitude values of the signals are obtained through fast Fourier transformation, and the difference of the main frequency amplitude values of the two signals does not exceed a preset value, so that the amplitude values of the two signals meet the requirement of similarity;
S4, drawing a similar measuring point thermodynamic diagram based on the judging result; drawing a cross-correlation coefficient and delay time meeting requirements into a similar measurement point thermodynamic diagram, wherein the horizontal coordinate and the vertical coordinate in the thermodynamic diagram are measurement point numbers for performing cross-correlation calculation, marking the measurement points meeting the similar requirements through different colors, correspondingly matching the color bars with a numerical range meeting the similar requirements, and simultaneously drawing a main frequency amplitude thermodynamic diagram, and coloring the thermodynamic diagram at an instantaneous speed;
S5, dividing equivalent areas; for an area formed by a plurality of measuring points, when the measuring points are similar in pairs, the area is an equivalent area, when the measuring points of another area are similar in pairs, the other area and the area are equivalent areas until the lower half area of the whole area is divided, and finally the division of the whole area is completed through mirror images;
S6, describing each equivalent area with similar speed type by using the same speed function.
2. The method for designing a simplified model of a fluidic oscillator according to claim 1, wherein the jet outlet speed is determined by the sweep direction speedAnd flow velocityDominant, and sweeping direction speedHas symmetrical and periodic flow characteristics.
3. The method for designing a simplified model of a fluidic oscillator according to claim 2, wherein the area divided by the plane of the fluidic outlet is a thin-middle and dense-periphery distribution, the data analysis is performed on the lower half area of the fluidic outlet along the sweeping direction, a corresponding velocity model is established, and then the velocity model of the upper half area is obtained through mirroring, positive-negative conversion and phase adjustment.
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| CN112597583A (en) * | 2020-12-11 | 2021-04-02 | 五邑大学 | Jet flow pneumatic drag reduction numerical simulation analysis method and device for high-speed train tail part |
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