A dynamic grid-based wind shear test simulation method

Abstract

The application discloses a wind shear test simulation method based on a dynamic grid, wherein the range of opening and closing angles of horizontal grid pieces is determined by taking the determination of the best deflection of the grid pieces and the best vibration direction of adjacent grid axes as the premise, the uniqueness of the fitted test wind shear index is determined, the mapping data set of the average wind speed downstream of the dynamic grid and the opening and closing angles of the horizontal grid pieces is realized by summarizing and screening the test data, the quantitative relationship between the opening and closing angles of the horizontal grid pieces and the wind shear index is determined by linear fitting on the obtained mapping data set, and finally, the opening and closing angle distribution of the horizontal grid pieces is inversely deduced according to the target landform wind shear and verified. The method can systematically and quickly establish the corresponding relationship between the opening and closing angle sequence of the grid pieces and the simulated wind shear index, thereby effectively solving the problem that the wind shear is affected by the multi-parameter coupling of the dynamic grid, and then realizing the test simulation of any wind shear index.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of atmospheric boundary layer test simulation, and relates to an atmospheric boundary layer average wind characteristic test simulation method, more particularly to a wind shear test simulation method based on a dynamic grid. BACKGROUND

[0002] In the atmospheric boundary layer, the variation of wind speed and wind direction is very common, and wind shear is one of the important characteristics of the average wind in the atmospheric boundary layer. In the atmospheric boundary layer, due to the influence of surface roughness caused by topography, water-land interface, high buildings, large trees and other factors, as well as the changes of atmospheric movement itself, the average wind speed increases gradually along the vertical height, and the wind shear is formed accordingly. Wind shear reflects the stability of the atmospheric boundary layer and the surface roughness. Wind turbines operate in the atmospheric boundary layer, and the wind shear characteristics of the atmospheric boundary layer will seriously affect the fatigue load, aerodynamic characteristics and power output characteristics of the wind turbine. In addition, wind shear will also affect the control system of the wind turbine, such as yaw control, power limiting control, etc., increasing the control difficulty and error. Wind shear will also affect the layout and design of the wind farm. When selecting and laying out the wind farm, the influence of topography, ground objects, seasons, weather and other factors on the wind shear gradient needs to be considered. When designing the wind farm, the variation of wind speed and wind direction needs to be considered, and the load and strength requirements at different heights need to be considered to ensure that the wind turbine can operate normally and maximize the output under all conditions. Wind shear also affects the assessment of wind energy resources. The assessment of wind energy resources also needs to consider the variation of wind speed and wind direction, and these variations must be modeled and predicted to assess the wind speed and power density at different heights, considering the variation law and uncertainty at different time scales and spatial scales to determine the best wind energy resource utilization scheme.

[0003] Currently, wind shear simulation methods in the test field are mainly divided into passive simulation and active simulation. Passive simulation mainly uses fixed devices such as sharp wedges, roughness elements, baffles and grids to replace the obstacles such as grass, trees and buildings near the ground surface in the atmospheric boundary layer to simulate the wind shear of the atmospheric boundary layer. Since the fixed devices do not have the ability to actively adjust the flow field, the wind field flow generated by passive simulation technology is passive and fixed. This will result in the need to change the ground state of the wind tunnel for different ground states, which consumes a lot of test cost and time. In addition, it is difficult to simulate the power spectrum and integral scale of the atmospheric boundary layer, especially the simulation of low-frequency turbulence components. Active simulation mainly uses aerodynamic devices connected to a power source to directly inject mechanical energy into the flow field, and controls the movement of these aerodynamic devices through a host computer to simulate the wind shear of the wind tunnel inflow. Compared with passive simulation, active simulation can more simply change the motion state of the flow field and enhance the simulation of low-frequency turbulence components, which has more advantages in wind shear simulation.

[0004] Dynamic grid is a method of actively simulating wind shear. A set of dynamic grids are arranged in the wind tunnel, and different frequencies and amplitudes of fluctuation energy are injected into the wind tunnel by using a fan. By accurately controlling the state of the grid, the turbulent characteristics of the flow field are changed to simulate the wind shear phenomenon under different terrain and weather conditions. For the simulation of atmospheric layer wind shear by using the grid, Chinese invention patent CN202110316825.4 discloses a grid device for wind tunnel test and a control method thereof. The grid device realizes the independent movement and overall cooperation between the horizontal and vertical grids driven by the motor, and simultaneously actively controls the turbulent intensity and wind shear index of the airflow in the test section of the wind tunnel. Chinese invention patent CN202111002140.9 discloses a wind tunnel test device and method for simulating multi-scale turbulent structure of atmospheric boundary layer. The control method using machine learning automatic optimization can significantly reduce the test debugging workload and improve the test efficiency.

[0005] The technical difficulties commonly faced by the prior art including the above two patents in simulating the wind shear of the atmospheric boundary layer by using the dynamic grid are that the wind shear in the wind tunnel test simulation is related to the factors such as the wind speed of the incoming flow in front of each grid piece, the rotation speed, the deflection, the opening angle, etc. However, there is no report on how to establish the corresponding relationship between the parameter distribution of the grid piece and the wind shear index in the prior art disclosed in the prior art, so that the wind shear test simulation by using the dynamic grid is time-consuming and high in cost, and the accuracy and reliability of the wind shear simulation result need to be further improved. SUMMARY

[0006] (I) Invention purpose

[0007] In view of the above problems of the prior art, the present application proposes a wind shear test simulation method based on dynamic grid. By alternately arranging the opening and closing angles of the horizontal grid shaft along the exponential distribution, the downstream wake flow field under the dynamic grid is measured, and the corresponding relationship between the wind shear index of different terrains and the opening and closing angles of the horizontal grid shaft can be quickly established, thereby effectively solving the technical problem that the wind shear is affected by the coupling of multiple parameters of the dynamic grid, and realizing the test simulation of any wind shear index and expanding the range of wind shear to be simulated.

[0008] (II) Technical solutions

[0009] To solve the technical problems and achieve the invention purposes, the technical solutions adopted by the present application are as follows:

[0010] A wind shear test simulation method based on a dynamic grid, wherein the dynamic grid is set at the entrance of the wind tunnel test section and its normal is consistent with the direction of the incoming flow of the wind tunnel, and includes at least a plurality of horizontal grid shafts 4 uniformly and discretely distributed in the vertical direction and extending in the horizontal direction. Each horizontal grid shaft 4 has a plurality of horizontal grid pieces 2 uniformly arranged along its length, and each end of the horizontal grid shaft 4 is correspondingly connected to a stepper motor 1. The stepper motor 1 drives the horizontal grid shaft 4 to rotate, thereby adjusting the opening angle of each horizontal grid piece 2. The wind shear test simulation method is characterized by comprising at least four steps during implementation:

[0011] SS1. Determine the range of opening and closing angles of the horizontal grid plates along the vertical direction.

[0012] Based on the initial setting of the angle range of the horizontal grid plates opening and closing angles and their distribution in the vertical direction, the individual effects of experimental variables, including at least the deflection of the horizontal grid plates and the vibration direction of adjacent horizontal grid axes, on wind shear were investigated through experimental data analysis. The optimal deflection of the horizontal grid plates and the optimal vibration direction of adjacent horizontal grid axes were selected respectively. Based on whether the wind shear index distribution curve simulated within the measurement point range of each test condition is unique, the optimal opening and closing angle range of the horizontal grid plates in the vertical direction, including the optimal opening and closing angle values ​​of the uppermost and lowermost horizontal grid plates, was finally determined. The optimal opening and closing angle value of the uppermost horizontal grid plate corresponds to the minimum value of the horizontal grid plate opening and closing angle, and the optimal opening and closing angle value of the lowermost horizontal grid plate corresponds to the maximum value of the horizontal grid plate opening and closing angle.

[0013] SS2. Establish a mapping dataset between the average wind speed downstream of the dynamic grid and the opening angle of the horizontal grid plates.

[0014] Based on the optimal deviation of the horizontal grid plate selected in step SS1, the optimal vibration direction of the adjacent horizontal grid axis, and the optimal opening and closing angle range of the horizontal grid plate along the vertical direction, several opening and closing angle arrangement sequences are designed within the optimal opening and closing angle range of the horizontal grid plate along the vertical direction. Experimental measurements are conducted, and a mapping dataset of wind speed at the measured point and the opening and closing angle of the horizontal grid plate at the corresponding height is established.

[0015] SS3. Establish a quantitative relationship between the average wind speed downstream of the dynamic bar grid and the opening angle of the horizontal bar grid.

[0016] Based on the mapping dataset of the average wind speed downstream of the dynamic grid and the opening angle of the horizontal grid panels established in step SS2, a linear fit is performed on the obtained mapping dataset to obtain the average wind speed downstream of the dynamic grid. The opening angle θ(z) of the horizontal grid plate i The linear relationship between them is expressed as follows: wherein a and b are the fitting coefficients and constants of the linear expression, respectively;

[0017] SS4. According to the wind shear of the target terrain, the opening angle distribution of the horizontal grid pieces is backstepped and verified

[0018] By determining the wind shear index a of the target terrain and the reference height z ref and the average wind speed at the reference height The theoretical average wind speed at the height of each horizontal grid piece is calculated According to the average wind speed downstream of the dynamic grid established in step SS3 and the relationship between the opening angle θ(z i ) of the horizontal grid piece, the opening angle value θ(z) of the horizontal grid piece at the corresponding height is calculated, the opening angle sequence instruction is input through the host computer control program for test measurement, and the measured average wind speed is obtained by taking the time domain average of the wind speed data The test wind shear index a' is fitted and obtained, and the deviation between a and a' is compared to evaluate the deviation between them. If the deviation between them is less than the simulation allowable error, the simulation of the wind shear of the target terrain is realized.

[0019] Preferably, in the above step SS1, the specific method for determining the opening angle range of the horizontal grid piece in the vertical direction at least includes the following sub-steps:

[0020] SS1.1. Preliminarily set the opening angle distribution form and range of the horizontal grid piece in the vertical direction, and determine the opening angle θ

[0021] The opening angle θ of the horizontal grid piece is arranged in an exponential form along the vertical direction, and the opening angle of the uppermost horizontal grid piece is preliminarily set to 0°, i.e., the uppermost horizontal grid piece is in a fully open state, and the opening angle of the lowermost horizontal grid piece is 90°, i.e., the lowermost horizontal grid piece is in a fully closed state;

[0022] SS1.2. According to the opening angle θ of the horizontal grid piece determined in step SS1.1, the optimal deflection working condition of the horizontal grid piece is determined

[0023] Firstly, the time series wind speed is obtained by test measurement of different deflection working conditions of the horizontal grid piece using a wind speed measuring device, and the exponential wind shear formula can be obtained according to the exponential wind shear formula wherein z ref is the reference height, z is the measured height, is the average wind speed at the reference height, is the average wind speed at the measured height, and a is the wind shear index;

[0024] Secondly, the relationship between and Linear fitting was performed on the two sets of data, and the linear regression equation was obtained where a1 is the fitting wind shear index, is the average wind speed predicted by linear regression;

[0025] Then, the size of the wind shear linear fitting coefficient COD under each deflection working condition was compared, and the optimal deflection working condition of the horizontal grating piece was determined by the maximum value of COD, wherein the calculation formula of COD is:

[0026]

[0027] In the formula, z i is the measured height corresponding to each horizontal grating piece, is the average wind speed at the measured height of each horizontal grating piece, is the average value of the average wind speed at each height of the wind shear, e i is the residual error at each height of the wind shear, and n is the number of working conditions;

[0028] SS1.3. According to the optimal deflection working condition of the horizontal grating piece determined in step SS1.2, the optimal vibration direction of the adjacent horizontal grating shaft is further determined

[0029] The same direction vibration working condition and the opposite direction vibration working condition of the adjacent horizontal grating shaft were respectively tested and measured, the wind shear linear fitting coefficients COD under the two vibration working conditions were compared, and the optimal vibration direction of the adjacent horizontal grating shaft was determined by the maximum value of COD;

[0030] SS1.4. According to the optimal deflection of the horizontal grating piece determined in step SS1.2 and the optimal vibration direction of the adjacent horizontal grating shaft determined in step SS1.3, the optimal opening and closing angle range of the horizontal grating piece is determined

[0031] Based on whether the wind shear index distribution curve simulated in the range of each test point is unique, if the test working conditions in steps SS1.2 and SS1.3 can simulate a unique wind shear index distribution curve in the range of the test point, it is not necessary to adjust the opening and closing angle range of the horizontal grating piece along the vertical direction; if the test working conditions in steps SS1.2 and SS1.3 fail to simulate a unique wind shear index distribution curve in the range of the test point, so that the wind shear index distribution curve has a turning point, the opening and closing angle range of the horizontal grating piece along the vertical direction should be reduced from 0 to 90° to determine the lower critical value θ min and the upper critical value θ max When the opening and closing angle of the horizontal grating piece is less than the lower critical value θ min or greater than the upper critical value θ max , the average wind speed at the corresponding height of the horizontal grating piece no longer changes, wherein θ minThe optimal opening angle of the uppermost horizontal louver, θ max The optimal opening angle of the lowermost horizontal louver.

[0032] Further, in the step SS1.1, the exponential arrangement of the opening angle θ of the horizontal louver in the vertical direction is Wherein, c and d are the exponential arrangement angle adjustment coefficients.

[0033] Further, in the step SS1.2, the wind speed measuring device is a constant temperature hot wire anemometer or a PIV particle image velocimetry.

[0034] Further, in the step SS1.2, the different deflection conditions of the horizontal louver include all upward deflection conditions, all downward deflection conditions, and adjacent horizontal louver alternating deflection conditions.

[0035] Further, in the step SS1.4, the reduced test angle range is determined by first determining the critical value of the lowermost horizontal louver and then determining the critical value of the uppermost horizontal louver.

[0036] Further, the test is carried out on the horizontal louver opening angle range conditions including 0-60° and 20-60°.

[0037] Preferably, in the step SS2, when the test condition data is screened, the data points outside the optimal opening angle range in the test condition are removed.

[0038] Preferably, in the step SS4, the wind shear index α of the A, B, C, and D four typical landforms in the Chinese building load specification is selected for testing and verification.

[0039] Through the above technical solutions, the present application determines the individual influence of the test variables on the wind shear through experimental means and data analysis methods, calculates the wind shear index α and the wind shear linear fitting coefficient COD by measuring the average wind speed of each point in the vertical direction of the louver downstream wake field, determines the optimal deflection of the louver, the optimal vibration direction of the adjacent louver, and the optimal opening angle range of the horizontal louver axis. The test condition data is summarized and screened to obtain a good linear relationship between the measured point wind speed and the corresponding height louver opening angle. Therefore, the present application proposes to linearly fit the mapping data set obtained by the test to obtain the linear relationship expression of the downstream average wind speed and the horizontal louver opening angle θ(z i ). By determining the wind shear index α of any target landform, the theoretical average wind speed According to the expression calculated in step SS3, the opening and closing angle value of the grid piece at the corresponding height is obtained, finally the opening and closing angle sequence instruction is input through the host computer control program to carry out the test, and the test wind shear index is checked, so that the wind shear simulation method is realized.

[0040] (Three) Technical effects

[0041] Compared with the prior art, the wind shear test simulation method based on the dynamic grid of the present application has at least the following significant technical effects:

[0042] (1) The wind shear test simulation method based on the dynamic grid of the present application can quickly and systematically establish the corresponding relationship between the opening and closing angle sequence of the grid piece and the simulated wind shear index, thereby effectively solving the problem that the wind shear is affected by the coupling of multiple parameters of the dynamic grid, and further realizing the test simulation of any wind shear index. The present application has the advantages of simple operation, high efficiency, high precision, wide application range, etc., which provides strong technical support for the field of wind energy utilization, wind power generation, etc.

[0043] (2) The wind shear test simulation method based on the dynamic grid of the present application determines the individual influence of the test variable on the wind shear through test means and data analysis methods, thereby solving the problem that the wind shear is affected by the coupling of multiple parameters of the dynamic grid. Traditionally, for grid wind tunnel test, it is difficult to determine the influence of a variable on wind shear by adjusting it alone, because there is a coupling relationship between multiple variables. The method proposed in the present application can calculate the wind shear index and the wind shear linear fitting coefficient COD by measuring the average wind speed of each point in the vertical direction of the downstream wake field of the grid, thereby determining the best deflection of the grid piece, the best vibration direction of the adjacent grid piece and the best opening and closing angle range of the horizontal grid axis.

[0044] (3) The wind shear test simulation method based on the dynamic grid of the present application linearly fits the mapping data set obtained by the test, thereby obtaining a linear relationship expression of the downstream average wind speed and the opening and closing angle of the horizontal grid piece. In this way, the theoretical average wind speed at the height of each horizontal grid piece can be calculated by determining the wind shear index of any target topography, and the opening and closing angle value of the grid piece at the corresponding height can be calculated according to the expression. This method can greatly improve the test efficiency and reduce the test cost.

[0045] (4) The wind shear test simulation method based on the dynamic grid of the present application calculates the theoretical average wind speed at the height of each horizontal grid piece by determining the wind shear index of any target topography, and calculates the opening and closing angle value of the grid piece at the corresponding height according to the expression. This method can be applied to wind shear simulation under different topographic conditions.

[0046] (5) The wind shear test simulation method based on the dynamic grid of the present application can input the opening angle sequence instruction for test through the host computer control program, and can check the test wind shear index, so as to automatically perform the test, and can quickly and accurately verify the feasibility and accuracy of the wind shear simulation method. In this way, the efficiency and precision of the test can be greatly improved, and the labor intensity and operation difficulty of the test personnel can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 The dynamic grid structure used by the present application in carrying out wind shear test simulation is shown in the schematic diagram.

[0048] Figure 2 The schematic diagram of different deflection of horizontal grid piece in the specific embodiment is shown in the figure.

[0049] Figure 3 The flow chart of the wind shear test simulation method based on the dynamic grid of the present application is shown in the figure.

[0050] Figure 4 The test data measured under the working condition of the best deflection and the best vibration direction of the adjacent grid axis in the specific embodiment is shown in the figure.

[0051] Figure 5 The linear fitting figure of the opening angle of the horizontal grid piece and the wind speed at the corresponding height in the specific embodiment is shown in the figure. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme of the present application more clear and obvious, the present application is further described in detail with specific implementation examples, and with reference to the drawings. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The described embodiments are part of the embodiments of the present application, not all the embodiments, and are intended to explain the present application, and cannot be understood as a limitation of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0053] Figure 1 The dynamic grid structure used by the present application in carrying out wind shear test simulation is shown in the schematic diagram. Figure 1As shown, the dynamic grid is arranged at the entrance of the wind tunnel test section and its normal direction is consistent with the wind tunnel flow direction, and at least includes a plurality of horizontal grid shafts 4 arranged on the grid frame 3 and uniformly distributed in the vertical direction and extending in the horizontal direction, a plurality of horizontal grid pieces 2 are uniformly arranged on each horizontal grid shaft 4 along the length direction thereof, and the end of each horizontal grid shaft 4 is correspondingly connected with a step-by-step driving motor 1, and the end of the horizontal grid shaft 4 is correspondingly provided with a bearing 5 when the horizontal grid shaft 4 is connected with the step-by-step driving motor 1 through the grid frame 3, and the step-by-step driving motor 1 drives the rotation of the horizontal grid shaft 4 to adjust the opening angle of each horizontal grid piece 2 arranged thereon.

[0054] As shown in the figure, Figure 3 the wind shear test simulation method based on the dynamic grid of the present application mainly includes four steps of determining the opening angle range of the horizontal grid piece along the vertical direction, establishing the mapping data set of the average wind speed downstream of the dynamic grid and the opening angle of the horizontal grid piece, establishing the quantitative relationship between the opening angle of the horizontal grid piece and the wind shear index, and verifying the opening angle distribution of the horizontal grid piece according to the target landform wind shear, and the specific implementation of each step is as follows:

[0055] 1. Determine the opening angle range of the horizontal grid piece along the vertical direction

[0056] On the basis of preliminarily setting the angle range of the opening angle of the horizontal grid piece 2 and the distribution form in the vertical direction, the individual influence of the test variables including the deflection of the horizontal grid piece 2 and the vibration direction of the adjacent horizontal grid shaft 4 on the wind shear is sequentially explored by means of test data analysis, the best deflection of the horizontal grid piece 2 and the best vibration direction of the adjacent horizontal grid shaft 4 are respectively selected, and whether the distribution curve of the wind shear index simulated in the range of each test working condition measuring point is unique is taken as the basis, and finally the best opening angle range of the horizontal grid piece along the vertical direction including the best opening angle values of the uppermost horizontal grid piece and the lowermost horizontal grid piece is determined, wherein the best opening angle value of the uppermost horizontal grid piece corresponds to the minimum value θ min of the opening angle of the horizontal grid piece, and the best opening angle value of the lowermost horizontal grid piece corresponds to the maximum value θ max of the opening angle of the horizontal grid piece, and the specific method is as follows:

[0057] 1.1 The opening angle of the horizontal grid piece 2 is arranged in an exponential form along the vertical direction, and the angle range is preliminarily set as 0°-90°, and the angle arrangement exponential formula is z i is the vertical height of each horizontal grid piece 2;

[0058] 1.2 Based on the opening and closing angle determined in step 1.1, determine the optimal biasing condition. Design the biasing conditions for horizontal grid plate 2 as follows: all biased upwards, all biased downwards, and adjacent grid plates alternately biased. Figure 2 As shown from left to right, the time-series wind speed U was obtained by experimentally measuring the different deflection conditions of the horizontal grid plates using a constant-temperature one-dimensional hot-wire anemometer. i (z) and calculate the time-domain mean. Take the wind tunnel reference height z ref The wind speed at the reference height is 1.5m. Take 7.6 m / s, and and The two sets of data were linearly fitted and the wind shear linear fitting coefficients (COD) under each working condition were compared. The COD values ​​for the working conditions of all grid plates deflecting upwards, all grid plates deflecting downwards, and adjacent grid plates deflecting alternately were 0.967, 0.955, and 0.995, respectively. Therefore, it can be determined that the deflection of adjacent grid plates deflecting alternately is the optimal deflection.

[0059] 1.3 Based on the optimal bias condition determined in step 1.2, the optimal vibration direction of the adjacent horizontal grid shaft 4 is further determined. By conducting experimental measurements on the co-directional and anti-directional vibration conditions of the adjacent horizontal grid shaft 4, the linear fitting coefficients COD under the two conditions are 0.990 and 0.977, respectively. Therefore, it can be determined that the optimal vibration direction of the adjacent grid shaft 4 is co-directional vibration.

[0060] 1.4 Based on the optimal deflection of the horizontal grid plate 2 determined in step 1.2 and the optimal vibration direction of the adjacent horizontal grid axis 4 determined in step 1.3, determine the optimal opening and closing angle range of the horizontal grid plate 2. Since the test conditions in steps 1.2 and 1.3 failed to simulate a unique wind shear index within the measuring point range, such as... Figure 4 As shown, the experiment found that when the opening angle is less than 8°, the average wind speed at the corresponding height of the horizontal grid plate 2 remains basically unchanged, and the wind shear no longer satisfies the exponential law change. Therefore, the opening angle range of the horizontal grid axis 4 was reduced from 0 to 90° to determine the critical value θ0 of the opening angle of the uppermost horizontal grid plate as 8°. No critical value was found in the experiment on the lower horizontal grid plate.

[0061] 2. Establish a mapping dataset between the average wind speed downstream of the dynamic grid and the opening angle of the horizontal grid plates.

[0062] Based on the optimal deflection of the horizontal grid plates selected in step 1, the optimal vibration direction of adjacent horizontal grid axes, and the optimal opening and closing angle range of the horizontal grid plates, experiments were conducted on three different indices of the horizontal grid plates. The angles of the bottom horizontal grid plates were set to 30°, 45°, and 60°, respectively, with corresponding angle arrangements as follows: The data obtained from the test conditions were summarized to establish a mapping dataset between the wind speed at the measured points and the opening and closing angle of the grid at the corresponding height.

[0063] 3. Establish a quantitative relationship between the opening and closing angle of horizontal grid plates and the wind shear index.

[0064] As described in step 2, a linear fit is performed on the obtained mapping dataset to obtain the average wind speed downstream of the dynamic grid. The opening angle θ(z) of the horizontal grid plate i The linear relationship between ) is expressed as follows: Linear relationship fitting graph as shown Figure 5 As shown.

[0065] 4. Based on the wind shear of the target terrain, infer and verify the distribution of the opening and closing angles of the horizontal grid plates.

[0066] Taking a typical Class C landform in the Chinese Building Load Code as an example, the wind shear index α in the code is 0.22, and the selected reference height z ref The average wind speed at a reference height of 1.5m. Given a wind speed of 7.6 m / s, calculate the theoretical average wind speed at the height of each horizontal grid panel 2. Based on the expression in step 3, the opening and closing angle θ(z) of the grid at the corresponding height is calculated. The opening and closing angle sequence value is input through the bus card program to control the stepper drive motor 1 to drive the horizontal grid shaft 4 to carry out the test measurement. The time domain mean of the wind speed data is taken to obtain the measured average wind speed. The wind shear index α1 was obtained by fitting and was found to be 0.231. The wind shear simulation method has been realized within the allowable error range of 0.02.

[0067] As can be seen from the above technical solutions, this invention proposes to determine the individual influence of experimental variables on wind shear through experimental means and data analysis methods. By measuring the average wind speed at various points in the vertical direction of the wake field downstream of the grid, the wind shear index α and the wind shear linear fitting coefficient COD are calculated to determine the optimal deflection of the grid panels, the optimal vibration direction of adjacent grid panels, and the optimal opening and closing angle range of the horizontal grid axis. After summarizing and filtering the data from various experimental conditions, it is found that there is a good linear relationship between the wind speed at the measured points and the opening and closing angle of the grid at the corresponding height. Therefore, this invention proposes to perform linear fitting on the mapping dataset obtained from the experiments to obtain the downstream average wind speed. The opening angle θ(z) of the horizontal grid plate i The linear relationship expression is obtained. By determining the wind shear index α for any target terrain, the theoretical average wind speed at the height of each horizontal grid plate is calculated. The corresponding height grid piece opening angle value θ(z) is calculated according to the expression in step SS3, finally the opening angle sequence instruction is input through the host computer control program to carry out the test, and the test wind shear index is checked, so that the wind shear simulation method is realized. It can be seen that the method can quickly and systematically establish the corresponding relationship between the grid piece opening angle sequence and the simulated wind shear index, thereby effectively solving the problem that the wind shear is affected by the dynamic grid multi-parameter coupling, and then realizing the test simulation of any wind shear index.

[0068] The above only describes one embodiment of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the present application.

Claims

1. A dynamic grid based wind shear test simulation method, the dynamic grid is arranged at the entrance of the test section of a wind tunnel and the normal direction of the dynamic grid is consistent with the flow direction of the wind tunnel, and the dynamic grid comprises at least a plurality of horizontal grid shafts which are uniformly distributed in the vertical direction and extend in the horizontal direction, a plurality of horizontal grid pieces are uniformly arranged on each of the horizontal grid shafts along the length direction of the horizontal grid shaft, and the end of each of the horizontal grid shafts is correspondingly connected with a step-by-step driving motor, the step-by-step driving motor drives the rotation of the horizontal grid shaft, thereby adjusting the opening angle of each of the horizontal grid pieces arranged on the horizontal grid shaft, characterized in that, The wind shear test simulation method comprises at least four steps when implemented: SS1. Determine the opening and closing angle range of the horizontal grid sheet in the vertical direction On the basis of the preliminary setting of the angle range of the opening and closing angle of the horizontal grid sheet and the distribution form in the vertical direction, the individual effects of the test variables including the deflection of the horizontal grid sheet and the vibration direction of the adjacent horizontal grid shaft on the wind shear are sequentially explored by means of test data analysis, the optimal deflection of the horizontal grid sheet and the optimal vibration direction of the adjacent horizontal grid shaft are respectively selected, and whether the wind shear index distribution curve simulated in the range of each test working condition measuring point is unique is taken as the basis to finally determine the optimal opening and closing angle range of the horizontal grid sheet in the vertical direction including the optimal opening and closing angle values of the uppermost horizontal grid sheet and the lowermost horizontal grid sheet, wherein the optimal opening and closing angle value of the uppermost horizontal grid sheet corresponds to the minimum value of the opening and closing angle of the horizontal grid sheet, and the optimal opening and closing angle value of the lowermost horizontal grid sheet corresponds to the maximum value of the opening and closing angle of the horizontal grid sheet; SS2. Establish the mapping data set of the average wind speed downstream of the dynamic grid and the opening and closing angle of the horizontal grid sheet According to the optimal deflection of the horizontal grid sheet, the optimal vibration direction of the adjacent horizontal grid shaft and the optimal opening and closing angle range of the horizontal grid sheet in the vertical direction selected in step SS1, a plurality of opening and closing angle arrangement sequences are designed within the optimal opening and closing angle range of the horizontal grid sheet in the vertical direction, test measurement is performed, and the mapping data set of the wind speed at the measuring point and the opening and closing angle of the horizontal grid sheet at the corresponding height is established; SS3. Establish the quantitative relationship between the average wind speed downstream of the dynamic grid and the opening and closing angle of the horizontal grid sheet According to the mapping dataset of the average wind speed downstream of the dynamic grid established in step SS2 and the opening angle of the horizontal grid piece, a linear fitting is performed on the obtained mapping dataset to obtain a linear relationship between the average wind speed downstream of the dynamic grid and the opening angle of the horizontal grid piece θ(z , which is expressed as i wherein a and b are the fitting coefficient and constant of the linear expression, respectively.​ SS4. According to the target landform wind shear, the opening and closing angle distribution of the horizontal grid sheet is back calculated and verified By determining the wind shear exponent α of any target terrain and the reference height z ref The average wind speed at the reference height The theoretical average wind speed at the height of each horizontal grid piece is calculated The average wind speed downstream of the dynamic grid established in step SS3 The relationship between the average wind speed at the reference height and the opening angle θ(z i ) of the horizontal grid piece at the corresponding height is calculated to obtain the opening angle value θ(z) of the horizontal grid piece at the corresponding height. The opening angle sequence instruction is input through the host computer control program for experimental measurement, and the time domain average of the wind speed data is taken to obtain the measured average wind speed The experimental wind shear exponent α' is fitted, and the deviation between α and α' is compared to evaluate the deviation between them. If the deviation between them is less than the simulation allowable error, the simulation of the wind shear of the target terrain is realized.

2. The dynamic grid based wind shear test simulation method of claim 1, wherein, In the above step SS1, the specific method for determining the opening and closing angle range of the horizontal grid sheet in the vertical direction comprises at least the following sub-steps: SS1.

1. Preliminarily set the opening and closing angle distribution form and range of the horizontal grid sheet in the vertical direction, and determine the opening and closing angle θ of each horizontal grid sheet The opening and closing angle θ of the horizontal grid sheet is arranged in an exponential form along the vertical direction, and the opening and closing angle of the uppermost horizontal grid sheet is preliminarily set to 0°, i.e. the uppermost horizontal grid sheet is in a fully open state, and the opening and closing angle of the lowermost horizontal grid sheet is 90°, i.e. the lowermost horizontal grid sheet is in a fully closed state; SS1.

2. According to the opening and closing angle θ of the horizontal grid sheet determined in step SS1.1, determine the optimal deflection working condition of the horizontal grid sheet Firstly, the time series wind speed is obtained by the experiment of different deflection conditions of horizontal grating blades using wind speed measuring device, and the wind shear formula is as follows wherein, z ref is the reference height, z is the measured height, is the average wind speed at the reference height, is the average wind speed at the measured height, and α is the wind shear index. Secondly, and By performing a linear fit on the two sets of data, a linear regression equation can be obtained. Where α1 is the fitted wind shear index. To predict the mean wind speed using linear regression; Then, the sizes of the wind shear linear fitting coefficients COD under each deflection working condition are compared, and the optimal deflection working condition of the horizontal grid sheet is determined by the maximum value of COD, wherein the calculation formula of COD is: where z i is the measured height of each horizontal grating piece, is the average wind speed at the measured height of each horizontal grating piece, is the average value of the average wind speed at each height of the wind shear, e i is the residual at each height of the wind shear, and n is the number of working conditions. SS1.

3. According to the optimal deflection working condition of the horizontal grid sheet determined in step SS1.2, further determine the optimal vibration direction of the adjacent horizontal grid shaft The same direction vibration working condition and the opposite direction vibration working condition of the adjacent horizontal grid shaft are respectively tested and measured, the wind shear linear fitting coefficients COD under the two vibration working conditions are compared, and the optimal vibration direction of the adjacent horizontal grid shaft is determined by the maximum value of COD; SS1.

4. determining the optimal opening angle range of the horizontal louvers according to the optimal deflection of the horizontal louvers determined in step SS1.2 and the optimal vibration direction of the adjacent horizontal louver determined in step SS1.3 whether the wind shear exponent distribution curve simulated in the range of the test points of each test condition is unique, if the test conditions carried out in steps SS1.2 and SS1.3 can simulate a unique wind shear exponent distribution curve in the range of the test points, it is not necessary to adjust the opening angle range of the horizontal grating sheet along the vertical direction, if the test conditions carried out in steps SS1.2 and SS1.3 fail to simulate a unique wind shear exponent distribution curve in the range of the test points, so that the wind shear exponent distribution curve has a turning point, the opening angle range of the horizontal grating sheet along the vertical direction should be reduced from 0-90° to determine the lower critical value θ min and the upper critical value θ max When the opening angle of the horizontal grating sheet is less than the lower critical value θ min or greater than the upper critical value θ max , the average wind speed at the corresponding height of the horizontal grating sheet no longer changes, wherein θ min corresponds to the best opening angle of the uppermost horizontal grating sheet, and θ max corresponds to the best opening angle of the lowermost horizontal grating sheet.

3. The dynamic grid based wind shear test simulation method of claim 2, wherein, In the step SS1.1, the exponential arrangement form of the horizontal louver blade opening angle θ along the vertical direction is where c and d are the exponential arrangement angle adjustment coefficients.

4. The dynamic grid based wind shear test simulation method of claim 2, wherein, In the step SS1.2, the wind speed measuring device is a constant temperature hot wire anemometer or a PIV particle image velocimeter.

5. The dynamic grid based wind shear test simulation method of claim 2, wherein, In the step SS1.2, the different deflection conditions of the horizontal louvers include at least all upward deflection conditions, all downward deflection conditions, and alternating deflection conditions of adjacent horizontal louvers.

6. The dynamic grid based wind shear test simulation method of claim 2, wherein, In the step SS1.4, the test angle range is reduced by first determining the critical value of the lowermost horizontal louver and then determining the critical value of the uppermost horizontal louver.

7. The dynamic grid based wind shear test simulation method of claim 6, wherein, The test is sequentially carried out on the horizontal louver opening angle range conditions including 0-60° and 20-60°.

8. The dynamic-mesh-based wind shear test simulation method of claim 1, wherein, In the step SS2, when screening the test condition data, the data points outside the optimal opening angle range in the test condition are removed.

9. The dynamic-mesh-based wind shear test simulation method of claim 1, wherein, In the step SS4, the wind shear index α of the A, B, C, and D four typical landforms in the Chinese building load specification is selected for testing and verification.

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