Method and device for generating and regulating multi-scale turbulence based on fan matrix

Abstract

The present application relates to the field of fluid mechanics and experimental fluid measurement technology, and more particularly to a multi-scale turbulent flow generation and regulation method and device based on a fan matrix, the regulation device comprising a fan matrix, the fan matrix comprising a plurality of fan groups, the plurality of fan groups being arranged in a matrix in sequence in the longitudinal direction and the transverse direction, each fan group in the fan matrix comprising an adjustment mechanism and a fan, an angle adjustment mechanism adjusting the tilt angle of the fan, a position adjustment mechanism adjusting the spacing between two adjacent fans, each fan being provided with a PWM speed regulator, and each fan outlet being provided with a spoiler. The regulation method is applied to the regulation device and can superimpose periodic or random fluctuations, thereby realizing adjustable turbulent flow in a larger space range and meeting different experimental requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluid mechanics and experimental fluid measurement technology, in particular to a multi-scale turbulent flow generation and regulation method and device based on a fan matrix. BACKGROUND

[0002] Turbulent flow is an important topic in fluid mechanics research and engineering applications, and its complex multi-scale vortex structure has a profound impact on many fields such as aircraft, building ventilation, and environmental flow. In studying the characteristics of turbulent flow, it is often necessary to generate flow fields with different turbulent intensity, vortex scale distribution and energy spectrum characteristics under controllable experimental conditions, in order to study the formation mechanism and energy transfer path of turbulent flow; a fan converts mechanical energy into airflow kinetic energy through blades, when the motor drives the blades to rotate, the interaction between the blades and the air will accelerate the movement of the air and form an airflow; when the airflow passes through the fan, a series of complex vortices and turbulent flows are generated; in the fan matrix, the relative position and angle between each fan will affect the generation, propagation and interaction of vorticity, and fan speed is one of the important factors affecting the amplitude change of turbulent flow spectrum of the fan matrix.

[0003] In the existing method, the influence of turbulent wind parameters is simulated by wind tunnel test, the traditional wind tunnel can provide a relatively stable flow field, but it is difficult to flexibly regulate the turbulent intensity and vortex structure in a large range, some passive adjustment methods for simulating turbulent wind include arranging a turbulence grid, honeycomb grid or other passive devices in the wind tunnel to block or disturb the flow field, but the adjustment means is limited, and it is difficult to achieve fine control of multi-scale and time-variable turbulent flow; in addition, how to simultaneously obtain adjustable turbulent intensity and controllable energy spectrum peak value, small frequency drift and other key indicators in the same device has always been a difficult problem in experimental fluid mechanics. SUMMARY

[0004] The purpose of the present application is to provide a multi-scale turbulent flow generation and regulation method and device based on a fan matrix, which can flexibly change the rotational speed, spacing, inclination angle of the fan and the installation mode of the spoiler, and perform periodic or random fluctuations, thereby realizing adjustable turbulent flow in a large spatial range and meeting different experimental requirements.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] The multi-scale turbulent flow generation and regulation method based on the fan matrix comprises the following steps:

[0007] S1: set a group of fan matrix parameters as initial fan matrix parameters, and measure the initial turbulent flow spectrum and initial vorticity distribution generated by the fan matrix;

[0008] S2: obtaining a fan basic rotating speed No, setting related parameters of superimposed fluctuation, and calculating a fan fluctuating rotating speed after superimposed fluctuation, the fan fluctuating rotating speed including a fan periodic fluctuating rotating speed Nr and a fan random fluctuating rotating speed Ns;

[0009] S3: sequentially sending the obtained fan periodic fluctuating rotating speed Nr and the fan random fluctuating rotating speed Ns to PWM speed regulators of the multiple fans respectively, so that the multiple fans rotate at the same rotating speed Nr or Ns, and current turbulent energy spectrum and current vorticity distribution are obtained respectively; the current turbulent energy spectrum includes periodic fluctuating turbulent energy spectrum and random fluctuating turbulent energy spectrum, and the current vorticity distribution includes periodic fluctuating vorticity distribution and random fluctuating vorticity distribution;

[0010] S4: comparing the current turbulent energy spectrum obtained in S3 with the initial turbulent energy spectrum obtained in S1 respectively, judging whether a change amount of a peak value amplitude of the energy spectrum in a turbulent evolution process meets a set target value; if yes, saving corresponding fan matrix parameters and related parameters of superimposed fluctuation, and entering S5; if not, returning to S2;

[0011] S5: obtaining the current vorticity distribution corresponding to the fan matrix parameters and related parameters of superimposed fluctuation saved in S4, comparing and analyzing the current vorticity distribution with the initial vorticity distribution obtained in S1, judging whether the current vorticity distribution meets a set requirement; if yes, saving corresponding fan matrix parameters and related parameters of superimposed fluctuation, and entering S6; if not, returning to S1 to modify the initial fan matrix parameters;

[0012] S6: outputting the fan matrix parameters and related parameters of superimposed fluctuation corresponding to the condition that the change amount of the peak value amplitude of the energy spectrum reaches the set target value and the vorticity distribution reaches the set requirement.

[0013] Preferably, S2 includes the following steps: if the superimposed fluctuation is set to be periodic fluctuation, obtaining a fan basic rotating speed No, setting related parameters of superimposed periodic fluctuation including fluctuation amplitude A, fluctuation frequency f, and fluctuation period t, and calculating a fan rotating speed Nr after superimposed periodic fluctuation: Nr = No + A x sin (2 x π x f x t).

[0014] Preferably, S2 further includes the following steps:

[0015] If the superimposed fluctuation is set to be random fluctuation, obtaining a fan basic rotating speed No, calculating a fan rotating speed Ns after superimposed random fluctuation: Ns = No + Nm, wherein Nm is a random fluctuating rotating speed, and the random fluctuation is generated by a random number generator or a random signal transmitter.

[0016] Preferably, the S1 comprises the following steps: the fan matrix parameters include fan inclination angle parameters, fan arrangement spacing parameters and jet direction parameters, and the spoiler size parameters, the spoiler position parameters and the spoiler angle parameters.

[0017] Preferably, in the S4, the spectrum peak amplitude change amount is set to be greater than or equal to 30%, and the frequency drift is set to be less than or equal to ±10%; in the S5, the vortex distribution setting requirement is that the current vortex distribution quantity adjustment range is 5% to 30%, and the vortex core diameter adjustment range in the current vortex distribution is 5% to 30%.

[0018] The fan matrix-based multi-scale turbulent flow generation and regulation device is applied to the fan matrix-based multi-scale turbulent flow generation and regulation method, and comprises a fan matrix, wherein the fan matrix comprises a plurality of fan groups, the plurality of fan groups are arranged in a matrix in sequence in the longitudinal direction and the transverse direction, each fan group in the fan matrix comprises an adjustment mechanism and a fan, the adjustment mechanism comprises an angle adjustment mechanism and a position adjustment mechanism, the angle adjustment mechanism can adjust the inclination angle of the fan, and the position adjustment mechanism can adjust the spacing between two adjacent fans, each fan is provided with a PWM speed regulator, each fan outlet is rotationally provided with a spoiler, and the spoiler adjusts the inclination angle through the inclination angle adjustment mechanism.

[0019] Preferably, the fan matrix can simulate and adjust turbulent flow degrees of different scales, and the turbulent flow degree simulation and adjustment range is 5% to 30%.

[0020] Preferably, the fan inclination angle adjustment range is 0° to 30°, the spacing adjustment range between the two adjacent fans is 0 to 10 mm, the spoiler rotation adjustment angle is 0° to 60°, and the fan rotation speed adjustment range is 0 to 20,000 rpm.

[0021] Preferably, the adjustment mechanism further comprises a housing, the position adjustment mechanism is mounted on the housing, the position adjustment mechanism comprises two groups of matching holes respectively formed on the two sides of the housing, each group of matching holes comprises a plurality of adjustment holes arranged at intervals along the side of the housing, guide rods fixedly arranged at the middle of the two sides of the fan correspond to the two groups of matching holes on the two sides of the housing, and the guide rods are connected with one of the adjustment holes in one group of matching holes.

[0022] Preferably, the inclination angle adjustment mechanism comprises a plurality of vertically arranged first connecting rods and a plurality of second connecting rods arranged in parallel corresponding to the plurality of first connecting rods, the number of the first connecting rods and the second connecting rods is the same as the number of rows in the fan matrix, two fixed rods in each group of first connecting rods are fixedly arranged on the two sides of the fan group, one end of the spoiler close to the fan group is rotationally connected with the fixed rods, and the middle two sides of the spoiler are hingedly connected with two adjustment rods in a corresponding group of second connecting rods.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The fan matrix based multi-scale turbulent flow generation and regulation device provided by the application can simultaneously change vortex scale distribution and energy spectrum characteristics by using the combination of spoiler and fan array, obtain multi-scale turbulent flow, realize the regulation from low turbulent flow degree to high turbulent flow degree, has good scalability and repeatability, and meets the needs of extensive experimental research and engineering test.

[0025] The fan matrix based multi-scale turbulent flow generation and regulation device provided by the application can flexibly change the rotating speed, interval, inclination angle of the fan and the installation mode of the spoiler, and perform periodic or random fluctuation, so that adjustable turbulent flow can be realized in a larger space range, and different experimental needs can be met.

[0026] The fan matrix based multi-scale turbulent flow generation and regulation method provided by the application is applied to the above-mentioned fan matrix based multi-scale turbulent flow generation and regulation device, can simulate the changeable turbulent flow characteristics in actual working conditions by superimposing periodic or random fluctuation, and can sample and analyze the flow field, verify that the regulation method can change the turbulent flow field energy spectrum peak amplitude by greater than or equal to 30%, frequency drift less than or equal to 10%, and can accurately measure and control key turbulent flow parameters such as vortex core diameter and vorticity distribution. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The fan matrix based multi-scale turbulent flow generation and regulation method provided by the application is applied to the above-mentioned fan matrix based multi-scale turbulent flow generation and regulation device, can simulate the changeable turbulent flow characteristics in actual working conditions by superimposing periodic or random fluctuation, and can sample and analyze the flow field, verify that the regulation method can change the turbulent flow field energy spectrum peak amplitude by greater than or equal to 30%, frequency drift less than or equal to 10%, and can accurately measure and control key turbulent flow parameters such as vortex core diameter and vorticity distribution.

[0028] Figure 2 The rotating speed control flow chart when the fluctuation is superimposed;

[0029] Figure 3 The fan matrix arrangement structure schematic diagram in the fan matrix based multi-scale turbulent flow generation and regulation device provided by the application;

[0030] Figure 4 The spoiler and fan connection structure schematic diagram of the application;

[0031] Figure 5 The inclination angle adjustment mechanism, spoiler and fan connection schematic diagram of the application.

[0032] The fan group; 2, the shell; 21, the adjustment hole; 4, the spoiler; 5, the fixed rod; 6, the adjustment rod. DETAILED DESCRIPTION

[0033] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0034] In the following description of the application, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation or be constructed and operated in a particular orientation.

[0035] In addition, the technical fields and installation methods involved in the embodiments of the present application described below can be combined with each other as long as there is no conflict between them.

[0036] Please refer to Figures 3-5 , the fan matrix based multi-scale turbulent flow generation and control device includes a fan matrix, the fan matrix includes a plurality of fan groups 1, the plurality of fan groups 1 are arranged in matrix structure according to longitudinal and transverse direction, the size of the fan matrix is 2.5m x 1.875m, the number of fan groups 1 can be adjusted according to specific use requirements; in this embodiment, the fan matrix includes 300 fan groups 1, the 300 fan groups 1 are arranged in 15 rows x 20 columns matrix group according to longitudinal and transverse direction.

[0037] Each fan group 1 in the fan matrix comprises an adjusting mechanism and a fan, the adjusting mechanism comprises a housing 2 and an angle adjusting mechanism, the housing 2 is provided with a position adjusting mechanism, the position adjusting mechanism comprises two groups of matching holes respectively formed on the two sides of the housing 2, each group of matching holes comprises a plurality of adjusting holes 21 arranged at intervals along the side of the housing 2, the two sides of the fan are respectively connected with the two groups of matching holes on the two sides of the housing 2 through the guide rods fixedly arranged at the middle, the guide rod can be connected with one of the adjusting holes 21 in one group of matching holes, the connection position of the fan and the adjusting hole can be manually adjusted, so as to adjust the relative position of the fan and the adjusting mechanism, and the spacing between the two adjacent fan groups 1 is adjusted, the spacing adjustment range of the two adjacent fans in the horizontal direction or the vertical direction is 0-10mm, and the airflow between the multiple fans interferes with each other to form a vortex and a shear layer; the angle adjusting mechanism comprises an angle adjusting motor (not shown in the figure), a driving gear rotatably arranged on the housing 2 and a driven gear fixedly arranged on the guide rod, the driving gear is connected with the driven gear in meshing mode, the output shaft of the angle adjusting motor is fixedly connected with the driving gear, when the angle adjusting motor is started, the driving gear drives the driven gear to rotate, so as to adjust the fan inclination angle, the angle adjusting mechanism can adjust the fan inclination angle, the fan inclination angle adjustment range is 0°-30°, so as to adjust the jet flow direction of the fan, affect the wind pressure and the air volume, and adjust the jet flow directions of the multiple fans in the fan matrix, so as to change the vortex structure and the distribution of the shear layer flow field; a PWM speed regulator is arranged on each fan, the PWM speed regulator is a pulse width modulation speed regulator, which is a device for realizing motor speed regulation by using pulse width modulation technology, the PWM speed regulator is prior art, and details are not described herein; the speed of each fan can be adjusted by the PWM speed regulator, the speed adjustment range is 0-20000rpm, and the airflow injection intensity is adjusted; the inclination angle, arrangement spacing, jet flow direction of the fan in the multiple fan groups 1 and the interaction between the fans can induce the generation of complex vortex structure and shear layer flow field.

[0038] Each fan outlet is rotatably provided with a spoiler 4, the width of the spoiler 4 is 0.5-1 times the diameter of the fan, the shape and size of the spoiler 4 can be adjusted according to the specific test requirements, common spoilers 4 include flat, arc and sawtooth, etc., the rotating adjustment angle of the spoiler 4 disclosed in the embodiment is 0°-60°, the distance between the spoiler 4 and the fan blade outlet is 5cm, the length and width of the spoiler 4 are the same as the diameter of the fan, and the angle between the spoiler 4 and the vertical plane where the fan outlet is located can be adjusted in size by the inclination adjustment mechanism, the inclination adjustment mechanism includes a plurality of vertically arranged first connecting rods and a plurality of second connecting rods arranged in parallel corresponding to the plurality of first connecting rods, the number of groups of first connecting rods and second connecting rods is the same as the number of rows in the fan matrix, in the embodiment, the number of groups of first connecting rods and second connecting rods is 15, two fixed rods 5 in each group of first connecting rods are fixedly arranged on both sides of the fan group 1, and one end of the spoiler 4 close to the fan group 1 is rotatably connected with the fixed rod 5, the middle two sides of the spoiler 4 are hingedly connected with two adjusting rods 6 in a corresponding group of second connecting rods, adjusting the up and down movement of the second connecting rod can control the angle change of the spoiler 4, so as to trigger vortex structures of different scales, and at the same time, the local shearing and rotating effect of the fan jet flow is realized. The controllable generation of multi-scale turbulence is realized.

[0039] Among them, the fan matrix disclosed in the embodiment can be simulated and adjusted from low turbulence to high turbulence, wherein the low turbulence is about 5%, and the high turbulence is about 30%; Specifically, when the fan basic speed is 3000rpm and the angle of the spoiler 4 is 15°, the rotating fan blade will cut the airflow and easily induce turbulence in the airflow, the turbulence degree of the flow field caused by the fan matrix is about 5%, that is, the low turbulence; when the fan basic speed is 6000rpm and the angle of the spoiler 4 is 45°, the turbulence degree of the flow field caused by the fan matrix is about 30%, that is, the high turbulence.

[0040] Please refer to Figures 1-2 , the multi-scale turbulence generation and regulation method based on the fan matrix is applied to the multi-scale turbulence generation and regulation device based on the fan matrix, and includes the following steps:

[0041] S1: Set a group of fan matrix parameters as initial fan matrix parameters, measure the initial turbulence energy spectrum and initial vorticity distribution generated by the fan matrix;

[0042] The fan matrix parameters include fan inclination, fan arrangement spacing, jet direction, and size, position, angle, and other parameters of the spoiler 4. The set of parameters can induce complex vortex structures and shear laminar flow fields. In the embodiment, the initial fan matrix parameters are as follows: the fan inclination angle is 0°, the jet direction is straight ahead, the spacing between adjacent upper and lower fans and the spacing between adjacent left and right fans are both 0.5 times the fan diameter, the spoiler 4 is 5 cm away from the fan blade, the length and width of the spoiler 4 are the same as the fan diameter, and the inclination angle of the spoiler 4 is 30°. Based on the above test parameters, the initial turbulent energy spectrum and the initial vorticity distribution are obtained.

[0043] S2: Obtain the fan basic speed No, set the related parameters of the superimposed fluctuation, and calculate the fan variable speed after superimposed fluctuation. The fan variable speed includes the fan periodic fluctuation speed Nr and the fan random fluctuation speed Ns.

[0044] Specifically, the corresponding fan speed in the initial fan matrix parameters is the basic speed No. If the superimposed fluctuation is periodic fluctuation, the related parameters of the superimposed fluctuation include the fluctuation amplitude A, the fluctuation frequency f, and the fluctuation period t. The fan periodic fluctuation speed Nr after superimposed periodic fluctuation is calculated as follows:

[0045] Nr = No + A x sin(2 x p x f x t)

[0046] If the superimposed fluctuation is random fluctuation, which is used to simulate the randomness of the fan speed, the amplitude and frequency of the random fluctuation can be set according to actual needs. The fan basic speed No is obtained, and the fan random fluctuation speed Ns after superimposed random fluctuation is calculated as follows:

[0047] Ns = No + Nm

[0048] Where Nm is the random fluctuation speed. The random fluctuation can be generated by a random number generator or a random signal transmitter. The generated random fluctuation is superimposed on the basic speed to obtain the actual speed of each fan. This actual speed can be output to the PWM speed regulator in real time to adjust the operation state of the fan.

[0049] In the embodiment, the fluctuation amplitude is between 1% and 10%, and the fluctuation frequency is between 0.1 and 10 Hz.

[0050] S3: send the acquired fan periodic fluctuation rotating speed Nr and fan random fluctuation rotating speed Ns to the PWM speed regulator of the plurality of fans in sequence respectively, so that the plurality of fans rotate at the same rotating speed Nr or Ns, and obtain the current turbulent energy spectrum and current vorticity distribution after the fan matrix superposition fluctuation; the current turbulent energy spectrum includes periodic fluctuation turbulent energy spectrum and random fluctuation turbulent energy spectrum, and the current vorticity distribution includes periodic fluctuation vorticity distribution and random fluctuation vorticity distribution;

[0051] Specifically, a test area is arranged downstream of the fan matrix to ensure that at least 80% of the core test area is covered; sampling points are arranged reasonably according to the size and shape of the test area to ensure the comprehensiveness and accuracy of the data, and the random fluctuation or periodic fluctuation is superimposed on the overall layout of the initial fan matrix, so that the fan rotates at the fan periodic fluctuation rotating speed Nr and the fan random fluctuation rotating speed Ns respectively, and the periodic fluctuation turbulent energy spectrum and the random fluctuation turbulent energy spectrum are acquired respectively, which are used as the current turbulent energy spectrum.

[0052] Further, the particle image velocimetry (PIV) technology is used to scatter tracer particles in the test area, a laser light source is used to illuminate the particles, the moving track of the particles over time is recorded, the velocity field is calculated by using the image processing technology, and thus the current vorticity distribution is derived, which corresponds to the periodic fluctuation vorticity distribution acquired by the fan rotating at the fan periodic fluctuation rotating speed Nr and the random fluctuation vorticity distribution acquired by the fan rotating at the fan random fluctuation rotating speed Ns respectively.

[0053] Specifically, the PIV technology is used to acquire the regulated velocity field and perform velocity measurement respectively to capture all characteristics of the turbulent flow, the collected data is preprocessed, such as denoising and filtering, to improve the data quality, and the preprocessed data is subjected to Fourier transform to calculate the energy density under different frequencies, and thus the current turbulent energy spectrum after regulation is obtained.

[0054] S4: compare the current turbulent energy spectrum acquired in S3 with the initial turbulent energy spectrum acquired in S1 respectively, and determine whether the amplitude variation of the energy spectrum peak value in the turbulent evolution process meets the set target value; if yes, save the corresponding fan matrix parameters and the related parameters of the superimposed fluctuation, and enter S5; if not, return to S2.

[0055] Specifically, in the embodiment, the set amplitude variation of the energy spectrum peak value in the current target value is ≥30%, and the frequency drift is <±10%.

[0056] The peak value of the current turbulent energy spectrum obtained after regulating the S4 fan speed is compared with the peak value of the turbulent energy spectrum obtained in S1, the change amount of the peak value of the current turbulent energy spectrum after regulation is calculated, in this embodiment, the percentage is used to represent the size of the change amount, the peak value amplitude change amount of the current turbulent energy spectrum is calculated, and whether it satisfies the set amplitude change ≥ 30% is calculated. If it satisfies, it enters S5; if it does not satisfy, it returns to S2, re-sets the related parameters of the superimposed fluctuation, and re-calculates the fan periodic fluctuation speed Nr and the fan random fluctuation speed Ns after the superimposed fluctuation.

[0057] Further, by analyzing the initial turbulent energy spectrum and the turbulent energy spectrum obtained after S4 multiple regulations, the energy distribution under different frequencies is observed, the range and characteristics of the frequency drift are determined, and the numerical value of the frequency drift is calculated. In this embodiment, the change of the frequency drift is represented by its relative frequency change rate, and it is observed that the frequency drift < ± 10%.

[0058] S5: The current vortex distribution corresponding to the related parameters of the superimposed fluctuation of the fan matrix parameters saved in S4 is obtained, which is compared with the initial vortex distribution obtained in S1 for analysis, to determine whether the current vortex distribution meets the set requirements; if it meets, the corresponding fan matrix parameters and the related parameters of the superimposed fluctuation are saved, and S6 is entered; if it does not meet, it returns to S1, and the initial fan matrix parameters are re-set to generate turbulence;

[0059] Specifically, the vortex distribution reveals the distribution number of different scale turbulent vortices and the vortex core diameter of different scale turbulent vortices, wherein the different scale turbulent vortices include large scale turbulent vortices and small scale turbulent vortices, and the distribution number of different scale turbulent vortices and the vortex core diameter of different scale turbulent vortices are set according to the test requirements. In this embodiment, the adjustment range of the current vortex distribution number is 5% to 30%, and the adjustment range of the vortex core diameter of different scale turbulent vortices in the current vortex distribution is 5% to 30%. The fan matrix parameters and the related parameters of the superimposed fluctuation saved in S4 are called, the current vortex distribution corresponding to the set of parameters is obtained, and data statistical analysis is performed on the initial vortex distribution and the current vortex distribution obtained in S1, respectively. The initial vortex distribution and the current vortex distribution can be observed by flow field visualization technology, and the statistical quantities such as mean and variance of the initial vortex distribution and the current vortex distribution are calculated, and the vortex distribution law after the superimposed fluctuation is observed.

[0060] If the distribution number and the vortex core diameter of different scale turbulent vortices in the current vortex distribution meet the set requirements, S6 is entered; if the distribution number and the vortex core diameter of different scale turbulent vortices in the current vortex distribution do not meet the set requirements, S1 is returned, the initial fan matrix parameters are modified, the initial fan matrix parameters are re-set, and the regulation of turbulence is performed.

[0061] S6: output the fan matrix parameters corresponding to the situation that the energy spectrum peak amplitude variation reaches the set target value and the vorticity distribution reaches the set requirement, and the related parameters of superimposed fluctuations.

[0062] Specifically, the fan matrix parameters corresponding to the situation that the energy spectrum peak amplitude variation reaches the set target value and the vorticity distribution reaches the set requirement, and the related parameters of superimposed fluctuations, indicate that the multi-scale turbulent flow generation and regulation device based on the fan matrix can realize fine control of multi-scale variable turbulent flow through the above method, and adjustable turbulent intensity, controllable energy spectrum peak and smaller frequency drift index can also be obtained in the device.

[0063] Specifically, the output fan matrix parameters include fan inclination angle parameters, fan arrangement spacing parameters and jet direction parameters, as well as size parameters, position parameters and angle parameters of the spoiler 4, and the related parameters of superimposed fluctuations include the fan periodic fluctuation speed Nr after superimposed periodic fluctuations and the fan random fluctuation speed Ns after superimposed random fluctuations, and the corresponding random fluctuation speed Nm.

[0064] The multi-scale turbulent flow generation and regulation device based on the fan matrix provided by the application can simultaneously change the vorticity scale distribution and energy spectrum characteristics by using the combination of the spoiler 4 and the fan array, so that multi-scale turbulent flow is obtained; the adjustment from low turbulent intensity to high turbulent intensity is realized, good scalability and repeatability are achieved, and the needs of extensive experimental research and engineering testing are met.

[0065] The multi-scale turbulent flow generation and regulation device based on the fan matrix provided by the application can flexibly change the speed, spacing, inclination angle of the fan and the installation mode of the spoiler 4, and perform periodic or random fluctuations, so that adjustable turbulent flow is realized in a larger space range, and different experimental needs are met.

[0066] The multi-scale turbulent flow generation and regulation method based on the fan matrix provided by the application is applied to the above-mentioned multi-scale turbulent flow generation and regulation device based on the fan matrix, and through superimposed periodic or random fluctuations, the variable turbulent flow characteristics in actual working conditions can be simulated, the flow field can be sampled and analyzed, and it is verified that the regulation method can change the turbulent flow field energy spectrum peak amplitude by ≥30%, the frequency drift is <±10%, and the key turbulent flow parameters such as vortex core diameter and vorticity distribution can be accurately measured and controlled.

Claims

1. A method for multi-scale turbulence generation and control based on fan matrix, characterized in that: The method comprises the following steps: S1: setting a group of fan matrix parameters as initial fan matrix parameters, and measuring initial turbulence energy spectrum and initial vorticity distribution generated by the fan matrix; S2: obtaining a fan basic rotating speed No, setting related parameters of superimposed fluctuations, and calculating a fan variable rotating speed after superimposed fluctuations, the fan variable rotating speed comprising a fan periodic fluctuation rotating speed Nr and a fan random fluctuation rotating speed Ns; S3: sequentially sending the obtained fan periodic fluctuation rotating speed Nr and the fan random fluctuation rotating speed Ns to PWM speed regulators of a plurality of fans respectively, so that the plurality of fans rotate at the same rotating speed Nr or Ns, and current turbulence energy spectrum and current vorticity distribution are obtained respectively; the current turbulence energy spectrum comprises periodic fluctuation turbulence energy spectrum and random fluctuation turbulence energy spectrum, and the current vorticity distribution comprises periodic fluctuation vorticity distribution and random fluctuation vorticity distribution; S4: comparing the current turbulence energy spectrum obtained in S3 with the initial turbulence energy spectrum obtained in S1 respectively, judging whether a turbulence evolution process energy spectrum peak amplitude change amount meets a set target value; if yes, saving corresponding fan matrix parameters and related parameters of superimposed fluctuations, and entering S5; if no, returning to S2; S5: obtaining current vorticity distribution corresponding to the fan matrix parameters and related parameters of superimposed fluctuations saved in S4, comparing and analyzing the current vorticity distribution with the initial vorticity distribution obtained in S1, judging whether the current vorticity distribution meets a set requirement; if yes, saving corresponding fan matrix parameters and related parameters of superimposed fluctuations, and entering S6; if no, returning to S1, and modifying initial fan matrix parameters; S6: outputting fan matrix parameters and related parameters of superimposed fluctuations corresponding to the fact that the energy spectrum peak amplitude change amount reaches the set target value and the vorticity distribution reaches the set requirement.

2. The fan-matrix-based multi-scale turbulence generation and control method of claim 1, wherein: The S2 comprises the following steps: if the set superimposed fluctuations are periodic fluctuations, obtaining a fan basic rotating speed No, setting related parameters of superimposed periodic fluctuations, the related parameters comprising a fluctuation amplitude A, a fluctuation frequency f, and a fluctuation period t, and calculating a fan rotating speed Nr after superimposed periodic fluctuations: Nr=No+A×sin(2×π×f×t).

3. The fan-matrix-based multi-scale turbulence generation and control method of claim 2, wherein: The S2 further comprises the following steps: If the set superimposed fluctuations are random fluctuations, obtaining a fan basic rotating speed No, calculating a fan rotating speed Ns after superimposed random fluctuations: Ns=No+Nm, wherein Nm is a random fluctuation rotating speed, and the random fluctuation is generated by a random number generator or a random signal transmitter.

4. The fan-matrix based multi-scale turbulence generation and control method of claim 1, wherein: The S1 comprises the following steps: the fan matrix parameters comprise fan inclination parameters, fan arrangement spacing parameters, jet direction parameters, size parameters of spoiler plates, position parameters of the spoiler plates, and angle parameters of the spoiler plates.

5. The fan-matrix based multi-scale turbulence generation and control method of claim 1, wherein: In the S4, the set energy spectrum peak amplitude change amount is ≥30%, and the set frequency drift is <±10%; in the S5, the set requirement of the vorticity distribution is that an adjustment range of a current vorticity distribution quantity is 5% to 30%, and an adjustment range of a vortex core diameter in the current vorticity distribution is 5% to 30%.

6. A device for generating and controlling multi-scale turbulence based on fan matrix, applied to the method for generating and controlling multi-scale turbulence based on fan matrix according to any one of claims 1-5, characterized in that: The fan matrix comprises a plurality of fan groups arranged in a matrix in sequence in the longitudinal direction and the transverse direction, each fan group in the fan matrix comprises an adjusting mechanism and a fan, the adjusting mechanism comprises an angle adjusting mechanism and a position adjusting mechanism, the angle adjusting mechanism is capable of adjusting the tilt angle of the fan, and the position adjusting mechanism is capable of adjusting the spacing between two adjacent fans, each fan is provided with a PWM speed regulator, and each fan outlet is rotatably provided with a spoiler, and the spoiler is adjusted in the tilt angle by the tilt angle adjusting mechanism.

7. The fan-matrix based multi-scale turbulence generation and control apparatus of claim 6, wherein: The fan matrix can simulate adjustment of different scales of turbulence, and the turbulence simulation adjustment range is 5% to 30%.

8. The fan-matrix based multi-scale turbulence generation and control apparatus of claim 6, wherein: The fan tilt angle adjustment range is 0° to 30°, the spacing adjustment range between two adjacent fans is 0 to 10 mm, the spoiler rotation adjustment angle is 0° to 60°, and the fan rotation speed adjustment range is 0 to 20000 rpm.

9. The fan-matrix based multi-scale turbulence generation and control apparatus of claim 6, wherein: The adjusting mechanism further comprises a housing, the position adjusting mechanism is mounted on the housing, the position adjusting mechanism comprises two groups of matching holes respectively formed on the two sides of the housing, each group of matching holes comprises a plurality of adjusting holes arranged at intervals along the side of the housing, the guide rods fixedly arranged at the middle of the two sides of the fan correspond to the two groups of matching holes on the two sides of the housing, and the guide rods are connected to one of the adjusting holes in one group of matching holes.

10. The fan-matrix based multi-scale turbulence generation and control apparatus of claim 6, wherein: The tilt angle adjusting mechanism comprises a plurality of vertically arranged first connecting rods and a plurality of second connecting rods arranged in parallel and corresponding to the plurality of first connecting rods, the number of the first connecting rods and the second connecting rods is the same as the number of rows in the fan matrix, two fixed rods in each group of first connecting rods are fixedly arranged on the two sides of the fan group, one end of the spoiler close to the fan group is rotatably connected with the fixed rods, and the two sides of the middle of the spoiler are hingedly connected with two adjusting rods in a corresponding group of second connecting rods.

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