CN110220666B

CN110220666B - Wind field detection device based on microstrain and online wind field detection and evaluation method

Info

Publication number: CN110220666B
Application number: CN201910546310.6A
Authority: CN
Inventors: 祁力钧; 杨泽鹏; 吴亚垒; 肖雨; 程浈浈; 张豪; 杨知伦; 刘婠婠
Original assignee: China Agricultural University
Current assignee: China Agricultural University
Priority date: 2019-06-21
Filing date: 2019-06-21
Publication date: 2024-01-30
Anticipated expiration: 2039-06-21
Also published as: CN110220666A

Abstract

The invention belongs to the field of plant protection spraying, and relates to a micro-strain-based wind field detection device and an online wind field detection and evaluation method, which are mainly used for online detection of stable wind fields generated by unmanned aerial vehicles, wind tunnel tests, air curtain machines and the like in a hovering state. According to the invention, a polypropylene sheet is adopted to simulate the wind pressure bending process of the blade in the wind field, the strain sheet attached to the polypropylene sheet is bent along with the wind pressure bending process and the resistance value change occurs, and the wind speed and the wind direction are measured according to the pressure difference signals in the full-bridge circuit formed by the strain sheet. The invention can realize automatic adjustment of the height of the detected wind, can realize rapid detection of the wind speed at a plurality of points X, Y, Z in the same horizontal plane, calculates the wind direction and the wind speed value of the points, can realize accurate adjustment of the position of the detected points, and can evaluate the distribution uniformity of the wind field. The wind field detection device has the advantages of high detection sensitivity, high detection precision, longer service life, low cost of detection parts and easy replacement.

Description

Wind field detection device based on microstrain and online wind field detection and evaluation method

Technical Field

The invention relates to a wind field detection device based on micro strain and an online wind field detection and evaluation method, and belongs to the field of plant protection spraying.

Background

In the agricultural plant protection field, plant protection unmanned aerial vehicle sprays and uses continuously to advance in the field, and orchard wind helps type spraying machine to replace traditional drenching type spraying machine gradually, utilizes the wind field that machinery produced to help fog droplet to pierce through dense canopy and impel the blade to turn over, improves the blade attachment rate to drift nature, homogeneity and the coverage rate to the fog droplet have important influence, therefore to plant protection unmanned aerial vehicle, orchard wind help type spraying machine etc. to apply the wind field detection in the operation environment of medicine also very important. The Chinese patent application (application number: 201710439738.1) discloses a hidden wind speed detector for a fan, wherein the hidden wind speed detector uses a fan wheel to detect wind speed, and the hidden wind speed detector can be hidden in the inner cavity of a controller shell when the fan is not used; the Chinese patent application (application number: 201810467180.2) discloses a three-dimensional wind field testing system and method of a rotor unmanned aerial vehicle, and provides a three-dimensional wind field testing method of the rotor unmanned aerial vehicle based on the combination of a wireless wind speed sensor and a space grid, which can rapidly measure the wind speed of each space grid test point. The wind speed measuring device mainly comprises a rotating wheel type anemometer and a thermosensitive anemometer, wherein the rotating wheel type anemometer has high precision requirement and high price, the wind wheel is easy to damage and not easy to replace, and the sensing capability of the wind wheel on wind speed change is poor; the platinum wire of the thermosensitive anemometer probe is easy to damage and is easily influenced by turbulence in the washing air flow of the unmanned aerial vehicle, so that the measured value is higher than the true value. The device is difficult to accurately position, can only perform single-point measurement at a time, is difficult to meet the requirement of simultaneous detection of different positions of multiple groups of data in a laboratory, has low acquisition efficiency, and cannot realize accurate positioning measurement and remote regulation.

Disclosure of Invention

Aiming at the technical problems, the invention aims to provide the micro-strain-based wind field detection device which has the advantages of high detection sensitivity, high detection precision, longer service life, low detection component cost, easiness in replacement, high automation degree, high efficiency, rapidness and capability of measuring the wind speed at multiple points.

The invention further aims to provide an online wind field detection method and an online wind field distribution uniformity evaluation method.

In order to achieve the above object, the present invention provides the following technical solutions:

the wind fields with different intensities act on the polypropylene sheets with the same size, bending deformation with different degrees can occur, the four strain sheets attached to the polypropylene sheets are subjected to the same bending deformation, the resistance value of each strain sheet is changed, the output voltage difference is changed, and the output voltage difference is positively related to the wind speed.

The wind field detection device detects the wind field when spraying the plant protection according to the output voltage difference change caused by the resistance change of the strain gauge, and can adjust the measured wind direction and the height of the measured horizontal plane in real time.

A wind field detection device based on microstrain comprises a supporting bar rotating mechanism, a horizontal rotating mechanism, a wind measuring distance adjusting mechanism, a height automatic adjusting mechanism and a control mechanism.

Wherein the horizontal rotation mechanism comprises a rotation frame 1, a rotation disc 12, a first stepping motor 13 and a first angle sensor 18; the rotary frame 1 is a cuboid frame with a square cross section and comprises an upper square frame and a lower square frame which are horizontally arranged.

The lower end surface of the rotary disc 12 is fixed on the output shaft of the first stepping motor 13, and the edge of the rotary disc 12 is fixedly connected with the square frame at the lower layer of the rotary frame 1 through a plurality of support spokes 8; the two parts of the first angle sensor 18 are respectively fixed on the lower end surfaces of the first stepping motor 13 and the rotary disc 12.

The support bar rotating mechanism comprises a support bar 4, a fixed base 5, a movable base 6, a rotating bearing 7, a second angle sensor 30, a rotary driven gear 31, a driving gear 32, a rotary outer wheel 33 and a second stepping motor 34; two opposite cross beams in the upper square frame of the rotating frame 1 are provided with base moving grooves 19 along the length direction of the cross beams.

The pair of fixed bases 5 are respectively fixed in the middle parts of the base moving grooves 19 of the two cross beams, the even pairs of moving bases 6 are horizontally movably arranged in the base moving grooves 19, and the even pairs of moving bases 6 are symmetrically distributed by connecting lines between the two fixed bases 5.

A rotating bearing 7 is arranged in each fixed base 5 and each movable base 6; a supporting bar 4 is fixedly connected between the rotating bearings 7 of the two mutually corresponding fixed bases 5 and between the rotating bearings 7 of each two mutually corresponding movable bases 6; a plurality of polypropylene sheets 2 and a plurality of voltage amplifiers 3 which are in one-to-one correspondence with the polypropylene sheets 2 are arranged on each supporting strip 4, and the polypropylene sheets 2 on each supporting strip 4 are distributed in an n multiplied by n equidistant array in a plane; the surface of the polypropylene sheet 2 is provided with a plurality of pairs of parallel strain sheets 41 which are alternately arranged in the front and back directions, and each strain sheet 41 is connected with the voltage amplifier 3 by adopting a differential full-bridge connection mode.

The outer side of each fixed base 5 is provided with a rotary driven gear 31 connected with a rotary bearing 7 in the fixed base 5, and the outer side of each movable base 6 is provided with a rotary outer wheel 33 connected with the rotary bearing 7 in the movable base 6; the rotary driven gear 31 and the rotary outer wheels 33 on the same side are connected through a rotary connecting rod with adjustable length; the driving gear 32 is meshed with the rotary driven gear 31, and the driving gear 32 is connected with an output shaft of a second stepping motor 34 fixedly connected to a beam of the upper square frame of the rotary frame 1; the two parts of the second angle sensor 30 are fixed to the fixed base 5 and the rotation driven gear 31, respectively.

The wind measuring distance adjusting mechanism is fixedly connected between the fixed base 5 and the movable base 6.

The automatic height adjusting mechanism comprises a multi-stage hydraulic lifting cylinder 14, a displacement sensor 15 and a base 16; the multistage hydraulic lifting cylinder 14 is vertically arranged on the base 16, and the piston rod end of the multistage hydraulic lifting cylinder 14 is fixedly connected with the bottom end of the first stepping motor 13; the displacement sensor 15 is fixed at the bottom end of the first stepper motor 13.

The control mechanism comprises a power supply 9, a data acquisition card 10, a wireless transmission module 11 and a control module 17 which are arranged on a rotary disc 12.

Each voltage amplifier 3 is connected with a data acquisition card 10; the data acquisition card 10 can acquire multiple groups of voltage data simultaneously, and the voltage data are transmitted to a remote computer end through the wireless transmission module 11 to record and draw a wind field diagram.

The power supply 9 supplies power to each voltage amplifier 3, the data acquisition card 10, the wireless transmission module 11, the first stepping motor 13, the multi-stage hydraulic lifting cylinder 14, the displacement sensor 15, the control module 17, the first angle sensor 18, the second angle sensor 30 and the second stepping motor 34.

The control module 17 controls the multi-stage hydraulic lifting cylinder 14, the first stepping motor 13 and the second stepping motor 34, receives monitoring data of the displacement sensor 15, the first angle sensor 18 and the second angle sensor 30, and communicates with a remote computer through the wireless transmission module 11.

The support bar rotating mechanism comprises two pairs of moving bases 6, the rotating connecting rod comprises a rotating inner sleeve rod 24 and two rotating outer sleeve rods 25 which are respectively sleeved at two ends of the rotating inner sleeve rod 24, the rotating inner sleeve rod 24 and the rotating outer sleeve rods 25 are clamped and positioned through inner hexagon bolts 26, hexagon nuts 27 and front and rear gaskets 28, wherein the rotating inner sleeve rod 24 is riveted on a rotating driven gear 31, and the two rotating outer sleeve rods 25 are respectively riveted on two rotating outer wheels 33; the wind measuring distance adjusting mechanism comprises a movable inner sleeve rod 21 and a movable outer sleeve rod 22 sleeved on the outer side of the movable inner sleeve rod 21, wherein the movable inner sleeve rod 21 can slide in the movable outer sleeve rod 22 and is clamped and positioned through a clamping bolt 23; the end of the movable inner loop bar 21 and the end of the movable outer loop bar 22 are fixedly connected to the fixed base 5 and the movable base 6 respectively.

Two pairs of parallel strain gauges 41 which are alternately arranged in the front and back direction are adhered on the surface of the polypropylene sheet 2 through an adhesive film 42, and the two pairs of strain gauges are sequentially as follows: a first strain gage a, a second strain gage b, a third strain gage c, and a fourth strain gage d; the first strain gauge a and the third strain gauge c are stuck on the front surface, and the second strain gauge b and the fourth strain gauge d are stuck on the back surface.

An online wind field detection method using the wind field detection device based on micro strain comprises the following steps:

a. establishing a three-dimensional coordinate system of the wind field detection device:

the wind field detection device is adjusted to an initial state, and the polypropylene sheet 2 is in a horizontal state;

setting the central point of a rotating frame 1 on the horizontal plane where a polypropylene sheet 2 is positioned as a three-dimensional coordinate system origin O, wherein an X axis is parallel to a supporting bar 4, a positive direction is backward, a Y axis is perpendicular to the supporting bar 4, a positive direction is leftward, a Z axis is perpendicular to an XOY horizontal plane, and a positive direction is downward;

b. establishing a simplified relation model of wind speeds v of different wind directions and an output voltage difference U:

b1, setting an anemometer at a certain test distance from an air outlet of the fan with adjustable rotating speed, and respectively measuring n wind speeds v which are gradually increased _i (i=0, 1,2,3 … n) with a wind speed in the range of 0 to 10m/s, where when v ₀ When=0, the resistance of the voltage amplifier 3 is adjusted to make the output voltage difference U be 0, i.e. U ₀ ＝0；

b2, blowing the fan out n wind speeds v measured along the positive Z-axis direction and the negative Z-axis direction of the polypropylene sheet 2 in any horizontal state respectively at the test distance _i Progressively increasing wind, and n wind speeds v measured respectively in the positive Y-axis direction and the negative Y-axis direction of the polypropylene sheet 2 in any vertical state _i Gradually increasing wind; in the process, the data of the corresponding voltage amplifier 3 is acquired by the data acquisition card 10 to obtain the wind speed v under different wind directions _i Corresponding output voltage difference U _i Finally, respectively obtaining a relation model of wind speed v and output voltage difference U in the Z-axis positive direction, the Z-axis negative direction, the Y-axis positive direction, the Y-axis negative direction, the X-axis positive direction and the X-axis negative direction which are expressed by a formula 2; wherein, the positive direction of the X axis and the positive direction of the Y axisThe relation model of the directions is the same, and the relation model of the X-axis negative direction and the Y-axis negative direction is the same; performing polynomial fitting on the obtained n different wind speed values in different wind directions and the output voltage difference signals, establishing a model of wind speed v and output voltage difference U, and determining an error correction coefficient k _j ：

v＝k _j U (j=1, 2,3, 4) equation 2

Wherein, the wind speed V unit is m/s, the output voltage difference U unit is V, k _j Error correction coefficient k for different wind directions ₁ Wind direction calibration coefficient k for positive direction of Z axis ₂ Wind direction calibration coefficient k for negative Z axis direction ₃ A wind direction calibration coefficient k for X, Y axis positive direction ₄ The wind direction calibration coefficient is X, Y in the negative direction;

c. wind field detection:

c1, placing a wind field detection device adjusted to an initial state at a detection position of a wind field to be detected, and simultaneously recording detection coordinates of each polypropylene sheet 2 in a three-dimensional coordinate system;

c2, respectively recording the output voltage difference U in the Z-axis direction of the polypropylene sheet 2 in each horizontal state corresponding to each detection coordinate _z Output voltage difference U in Y-axis direction of polypropylene sheet 2 in each vertical state _y Output voltage difference U in X-axis direction _x The method comprises the steps of carrying out a first treatment on the surface of the According to each U _z 、U _y And U _x B, selecting a relation model of wind speeds v and output voltage differences U of the Z-axis positive direction, the Z-axis negative direction, the Y-axis positive direction, the Y-axis negative direction, the X-axis positive direction and the X-axis negative direction obtained in the step b, and respectively obtaining the wind speeds v of the Z-axis directions corresponding to all detection coordinates _z Wind speed v in Y-axis direction _y And wind speed v in X-axis direction _x ；

c3, calculating the wind speed and the wind direction of each detection coordinate through a formula 3 and a formula 4And the wind speed>

In the formula, v _z Wind speed in Z-axis direction, v _y Wind speed in Y-axis direction, v _x Wind speed in the X-axis direction is in m/s;is a three-dimensional vector and comprises wind direction and wind speed value information; v _x 、v _y 、v _z Including positive and negative direction information and wind speed.

The specific process of the step b2 is as follows:

b2.1, moving the fan to a test distance position right above the polypropylene sheet 2 in any horizontal state, and sequentially blowing n wind speeds v downwards _i Progressively increasing wind at wind speed v _i When the polypropylene sheet 2 is bent downwards in cooperation with the strain gauge 41 to deform, the resistance value of the strain gauge 41 is changed, the output differential voltage is changed, the data acquisition card 10 acquires the voltage data of the voltage amplifier 3, and the wireless transmission module 11 is used for transmitting different wind speeds v _i Corresponding output voltage difference U _i Transmitting to a remote computer end for displaying and recording, and obtaining a polynomial fitting relation model of the wind speed v and the output voltage difference U in the positive direction of the Z axis by the remote computer end according to a formula 2: v=k ₁ U；

b2.2, changing the fan to a test distance position right below the polypropylene sheet 2 in any horizontal state, and sequentially blowing n wind speeds v upwards _i The wind gradually increases step by step, other operations are the same as those in the step b2.1, and the voltage and wind speed are negative at the moment, so that a polynomial fitting relation model of the wind speed v in the negative direction of the Z axis and the output voltage difference U is obtained: v=k ₂ U；

b2.3, changing the fan into blowing along the positive direction of the Y axis, testing the distance unchanged, rotating the supporting bar 4 by 90 degrees clockwise, and adjusting the polypropylene sheet 2 to be vertically downward and vertical to the Y axisOther operations are the same as those in step b2.1, and the voltage and wind speed are positive values, so that a polynomial fitting relation model of the wind speed v in the positive direction of the Y axis and the output voltage difference U is obtained: v=k ₃ U is provided; the relation model of the positive X-axis direction and the positive Y-axis direction is the same;

b2.4, changing the fan into blowing along the negative direction of the Y axis, and other operations are the same as those in the step b2.1, wherein the voltage and the wind speed are negative at the moment, and a polynomial fitting relation model of the wind speed v of the negative direction of the Y axis and the output voltage difference U is obtained: v=k ₄ U is provided; the relationship model of the X-axis negative direction and the Y-axis negative direction is the same.

The specific process of the step c2 is as follows:

1) The polypropylene sheet 2 in a horizontal state can detect the wind field wind speed v in the Z-axis direction _z The polypropylene sheet 2 corresponding to each detection coordinate is cooperated with the strain gauge 41 to sense the bending deformation of the wind field, the resistance value of the strain gauge 41 is changed, the output differential voltage is changed, the data acquisition card 10 acquires the voltage data of each voltage amplifier 3, and the output voltage difference U in the Z-axis direction corresponding to each detection coordinate is acquired through the wireless transmission module 11 _z Transmitting to a remote computer terminal, and the remote computer terminal converting U according to the relation model of the wind speed v and the output voltage difference U in the positive direction or the negative direction of the Z axis in the step b _z Conversion to v _z And recording the data; wherein U is _z Is positive, using an error correction coefficient k ₁ Calculating the wind speed and the wind direction along the positive direction of the Z axis by the positive direction relation model of the Z axis; u (U) _z When the value of (2) is negative, the error correction coefficient is k ₂ Calculating wind speed by a Z-axis negative direction model, and enabling wind direction to be along the Z-axis negative direction;

2) To detect the wind speed v in the Y-axis direction _y The supporting bar 4 rotates 90 degrees clockwise, the polypropylene sheet 2 is adjusted to be vertically downward, vertical to the Y axis and parallel to the X axis, and the output voltage difference U in the Y axis direction corresponding to each detection coordinate is obtained _y B, the remote computer end calculates U according to a relation model of wind speed v in the positive direction of the Y axis or the negative direction of the Y axis in the step b and the output voltage difference U _y Conversion to v _y And recording the data; wherein U is _y Is positive, using an error correction coefficient k ₃ Y-axis positive direction model calculation of (2)Wind speed and direction along the positive direction of the Y axis; u (U) _y When the value of (2) is negative, the error correction coefficient is k ₄ Calculating wind speed by a Y-axis negative direction model, and enabling wind direction to be along the Y-axis negative direction;

3) To detect the wind speed v in the X-axis direction _x The polypropylene sheet 2 is kept in a vertical state, and the horizontal rotating mechanism rotates 90 degrees clockwise to enable the polypropylene sheet 2 to be perpendicular to the X axis and parallel to the Y axis, and at the moment, the position of the original polypropylene sheet 2 is changed, but each detection coordinate corresponds to a new polypropylene sheet 2; obtaining the output voltage difference U of the X-axis direction corresponding to each detection coordinate _x B, the remote computer end calculates U according to the relation model of the wind speed v in the positive direction of the X axis or the negative direction of the X axis and the output voltage difference U in the step b _x Conversion to v _x And recording the data; wherein U is _x Is positive, using an error correction coefficient k ₃ Calculating wind speed by an X-axis positive direction model, wherein the wind direction is along the X-axis positive direction; u (U) _x When the value of (2) is negative, the error correction coefficient is k ₄ The wind speed is calculated by the X-axis negative direction model, and the wind direction is along the X-axis negative direction.

In the step c1, the multistage hydraulic lifting cylinder 14 is controlled to adjust the detection height of the wind field detection device, so as to realize wind field detection of different horizontal planes; the change of the measured wind distance is realized by adjusting the wind measuring distance adjusting mechanism and the interval distance of the polypropylene sheets 2 on the supporting strips 4.

An online wind field distribution uniformity evaluation method using the wind field detection device based on micro strain comprises the following steps:

b1、the anemometer is arranged at a certain test distance from the air outlet of the fan with adjustable rotating speed, and n wind speeds v which are gradually increased are respectively measured _i (i=0, 1,2,3 … n) with a wind speed in the range of 0 to 10m/s, where when v ₀ When=0, the resistance of the voltage amplifier 3 is adjusted to make the output voltage difference U be 0, i.e. U ₀ ＝0；

b2, blowing the fan out n wind speeds v measured along the positive Z-axis direction and the negative Z-axis direction of the polypropylene sheet 2 in any horizontal state respectively at the test distance _i Progressively increasing wind, and n wind speeds v measured respectively in the positive Y-axis direction and the negative Y-axis direction of the polypropylene sheet 2 in any vertical state _i Gradually increasing wind; in the process, the data of the corresponding voltage amplifier 3 is acquired by the data acquisition card 10 to obtain the wind speed v under different wind directions _i Corresponding output voltage difference U _i Finally, respectively obtaining a relation model of wind speed v and output voltage difference U in the Z-axis positive direction, the Z-axis negative direction, the Y-axis positive direction, the Y-axis negative direction, the X-axis positive direction and the X-axis negative direction which are expressed by a formula 2; wherein, the relation model of the positive direction of the X axis and the positive direction of the Y axis is the same, and the relation model of the negative direction of the X axis and the negative direction of the Y axis is the same; performing polynomial fitting on the obtained n different wind speed values in different wind directions and the output voltage difference signals, establishing a model of wind speed v and output voltage difference U, and determining an error correction coefficient k _j ：

v＝k _j U (j=1, 2,3, 4) equation 2

c. and (3) evaluating the distribution uniformity of the wind field:

returning the wind field detection device to an initial state, and calculating and determining a horizontal rotation angle alpha which is required to be adjusted by the horizontal rotation mechanism and a support bar rotation angle beta which is required to be adjusted by the support bar rotation mechanism according to target detection wind directions (x, y and z) through a formula 5 and a formula 6;

wherein, the units of alpha and beta are degrees;

then the horizontal rotating mechanism and the supporting bar rotating mechanism are respectively driven by the first stepping motor 13 and the second stepping motor 34 to rotate by corresponding angles, so that the polypropylene sheet 2 of each detection coordinate is vertical to the wind direction (x, y, z) of the detected wind field;

each polypropylene sheet 2 senses bending deformation of a wind field in cooperation with the strain gauge 41, the resistance value of the strain gauge 41 changes, the output differential voltage changes, the data acquisition card 10 acquires voltage data of each voltage amplifier 3, the output voltage difference signal U is transmitted to a remote computer end through the wireless transmission module 11, and the remote computer end calculates a wind speed value corresponding to the mth polypropylene sheet 2 through a formula 7

In the method, in the process of the invention,the wind speed value of the mth detection point is m/s; u (U) _m The output voltage difference of the mth detection point is expressed as V; beta is the rotation angle of the support bar rotating mechanism, +.>The direction is (x, y, z);

k _m the error correction coefficient for the mth detection point is determined by:

k _m U _m cos beta isWherein U is _m cos beta is U _m When U is the vertical partial voltage of _m cos beta is positive, using error correction factor k ₁ Calculating the wind speed in the vertical direction by using the relation model, and when U _m When cos beta is negative, then the error correction coefficient is k ₂ A relationship model;

k _m ^* U _m sin beta isHorizontal component velocity of (1), wherein U _m sin beta is U _m Is equal to the horizontal partial voltage of U _m sin beta is positive, and the error correction coefficient is k ₃ Calculating the wind speed in the horizontal direction by the relation model, and when U _m When sin beta is negative, the error correction coefficient is k ₄ A relationship model;

the standard deviation of the wind speed of each polypropylene sheet 2 is calculated by the formula 8, and then the variation coefficient of the wind speed distribution of each polypropylene sheet 2 is calculated by the formula 9:

wherein S is the standard deviation of wind speed of each polypropylene sheet 2,for the average wind speed>The wind speed value of the mth detection point is m/s; q is the total number of detected points; CV is the variation coefficient of wind speed distribution of each point in the plane where the polypropylene sheet 2 is positioned, and the unit is%.

The specific process of the step b2 is as follows:

b2.2, changing the fan to be under the polypropylene sheet 2 in any horizontal state, and sequentially blowing n wind speeds v upwards at the test distance _i The wind gradually increases step by step, other operations are the same as those in the step b2.1, and the voltage and wind speed are negative at the moment, so that a polynomial fitting relation model of the wind speed v in the negative direction of the Z axis and the output voltage difference U is obtained: v=k ₂ U；

b2.3, changing a fan into a fan which blows in the positive direction of the Y axis, testing the distance unchanged, rotating the support bar 4 clockwise by 90 degrees, adjusting the polypropylene sheet 2 to be vertically downward and vertical to the Y axis, and other operations are the same as those in the step b2.1, wherein the voltage and the wind speed are positive values at the moment, and obtaining a polynomial fitting relation model of the wind speed v in the positive direction of the Y axis and the output voltage difference U: v=k ₃ U is provided; the relation model of the positive X-axis direction and the positive Y-axis direction is the same;

The multistage hydraulic lifting cylinder 14 is controlled to adjust the detection height of the wind field detection device so as to obtain wind speed values of more points, and the wind speed standard deviation and the wind speed distribution variation coefficient of each plane in the space are calculated by substituting the wind speed values into the formula 7 and the formula 8.

Compared with the prior art, the invention has the beneficial effects that:

the method is mainly used for online detection of the stable wind field generated by the unmanned plane, the wind tunnel test, the air curtain machine and the like in the hovering state, and can be used for efficiently acquiring the wind speed and wind direction distribution condition of the wind field. The wind field detection device simulates a blade which is bent under a wind field by using a polypropylene sheet, the strain sheet is attached to the polypropylene sheet and bent along with the polypropylene sheet, and the wind speed is detected by converting the resistance change generated by bending the strain sheet into a differential pressure signal, so that the wind speed in the X, Y, Z direction of each point in space can be rapidly detected, and the wind direction and the wind speed value of each point can be calculated; the height of the wind power station can be automatically adjusted according to the experimental purposes, the position of the measuring point can be adjusted by multipoint measurement on the same horizontal plane, the uniformity of the wind speed of each point on the same horizontal plane can be rapidly measured, and the characteristics of the whole wind field can be evaluated; the automatic degree is high, the detection efficiency is high, the complexity of a plurality of measurement processes can be overcome, and online record real-time data can be remotely observed; the method has the characteristics of high detection sensitivity, large detection wind speed range, high detection precision, long service life, low detection component cost, easy replacement and the like.

Drawings

FIG. 1 is a schematic structural diagram of a microstrain-based wind field detection device of the present invention;

FIG. 2 is an enlarged partial schematic view of the support bar rotation mechanism;

fig. 3 is a schematic view showing a structure in which the strain gauge 41 is stuck on the polypropylene sheet 2;

fig. 4 is a schematic diagram of a differential full bridge connection of strain gages.

Wherein the reference numerals are as follows:

1 rotating frame 2 polypropylene sheet

4 support bars of 3 voltage amplifier

5 fixed base 6 moving base

7 rotating bearing 8 supporting spoke

9 power supply 10 data acquisition card

11 Wireless transmission module 12 rotating disc

13 first stepping motor 14 multi-stage hydraulic lifting cylinder

15 displacement sensor 16 base

17 control module 18 first angle sensor

19 base shifting chute 20 limit slide rail

21 move inner sleeve rod 22 move outer sleeve rod

23 clamping bolt 24 rotating inner sleeve

25-rotation outer sleeve rod 26 inner hexagon bolt

27 hexagonal nut 28 spacer

29 second angle sensor of base slide rail hole 30

31 rotary driven gear 32 driving gear

33 rotation outer wheel 34 second step motor

41 strain gauge 42 adhesive film

a first strain gage b second strain gage

c third strain gage d fourth strain gage

Origin of O three-dimensional coordinate system

Detailed Description

The invention will be further described with reference to the drawings and examples.

As shown in FIG. 1, the wind field detection device based on micro-strain comprises a supporting bar rotating mechanism, a horizontal rotating mechanism, a wind measuring distance adjusting mechanism, a height automatic adjusting mechanism and a control mechanism.

The horizontal rotating mechanism and the supporting bar rotating mechanism jointly form an automatic wind direction adjusting unit. Wherein the horizontal rotation mechanism comprises a rotation frame 1, a rotation disc 12, a first stepping motor 13 and a first angle sensor 18. The rotary frame 1 is a cuboid frame with a square cross section, and comprises an upper square frame, a lower square frame and four connecting columns, wherein the upper square frame and the lower square frame are horizontally arranged, and the four connecting columns are respectively and vertically fixedly connected between four corners of the upper square frame and the lower square frame.

The lower end face of the rotary disc 12 is hinged and fixed on the output shaft of the first stepping motor 13 through a flange, and the edge of the rotary disc 12 is fixedly connected with the lower square frame of the rotary frame 1 through a plurality of support spokes 8. The two parts of the first angle sensor 18 are respectively fixed on the lower end surfaces of the first stepping motor 13 and the rotary disc 12.

Preferably, the edge of the rotary disk 12 is fixedly connected with four corners of the lower square frame of the rotary frame 1 through four support spokes 8 respectively.

The support bar rotating mechanism includes a support bar 4, a fixed base 5, a moving base 6, a rotating bearing 7, a second angle sensor 30, a rotary driven gear 31, a driving gear 32, a rotary outer wheel 33, and a second stepping motor 34. Two opposite cross beams in the upper square frame of the rotating frame 1 are provided with base moving grooves 19 along the length direction of the cross beams, and the base moving grooves 19 are provided with limiting sliding rails 20.

The pair of fixed bases 5 are respectively fixed in the middle parts of the base moving grooves 19 of the two cross beams, the even pairs of moving bases 6 are horizontally movably arranged on the limiting slide rails 20 in the base moving grooves 19 through base slide rail holes 29 arranged at the bottoms of the moving bases 6, and the even pairs of moving bases 6 are symmetrically distributed by connecting lines between the two fixed bases 5.

A rotating bearing 7 is arranged in each fixed base 5 and each movable base 6; a supporting bar 4 is fixedly connected between the rotating bearings 7 of the two mutually corresponding fixed bases 5 and between the rotating bearings 7 of each two mutually corresponding movable bases 6. A plurality of polypropylene sheets 2 and a plurality of voltage amplifiers 3 which are in one-to-one correspondence with the polypropylene sheets 2 are arranged on each supporting strip 4, and the polypropylene sheets 2 on each supporting strip 4 are distributed in an n multiplied by n equidistant array in a plane. A plurality of pairs of parallel strain gauges 41 alternately arranged in the opposite directions are stuck on the surface of the polypropylene sheet 2 through an adhesive film 42, and each strain gauge 41 is connected with the voltage amplifier 3 by adopting a differential full-bridge connection mode.

As shown in fig. 2, a rotary driven gear 31 connected with the rotary bearing 7 in the fixed base 5 is arranged on the outer side of each fixed base 5, and a rotary outer wheel 33 connected with the rotary bearing 7 in the movable base 6 is arranged on the outer side of each movable base 6; the rotary driven gear 31 and the rotary outer wheels 33 on the same side are connected by a rotary connecting rod of adjustable length. The driving gear 32 is meshed with the rotary driven gear 31, and the driving gear 32 is connected with an output shaft of a second stepping motor 34 fixedly connected to a beam of the upper square frame of the rotary frame 1. When the second stepping motor 34 drives the driving gear 32 to rotate, the driving gear 32 drives the rotary driven gear 31 to rotate, and the rotary driven gear 31 drives the rotary outer wheel 33 to synchronously rotate through the rotary connecting rod, so that the rotary bearing 7 connected with the rotary driven gear 31 and the rotary outer wheel 33 synchronously rotates, and further the support bar 4 synchronously rotates. The two parts of the second angle sensor 30 are fixed to the fixed base 5 and the rotation driven gear 31, respectively.

Preferably, the rotary connecting rod comprises a rotary inner sleeve rod 24 and two rotary outer sleeve rods 25 respectively sleeved at two ends of the rotary inner sleeve rod 24, the rotary inner sleeve rod 24 and the rotary outer sleeve rods 25 are clamped and positioned through an inner hexagonal bolt 26, a hexagonal nut 27 and front and rear gaskets 28, wherein the rotary inner sleeve rod 24 is riveted on a rotary driven gear 31, and the two rotary outer sleeve rods 25 are respectively riveted on two rotary outer wheels 33.

The wind measuring distance adjusting mechanism is fixedly connected between the fixed base 5 and the movable base 6, so that the relative distance between the movable base 6 and the fixed base 5 can be changed, and further the relative distance between the adjacent support bars 4 can be changed, and the change of the measured wind distance can be realized.

Preferably, the wind-measuring distance adjusting mechanism comprises a movable inner sleeve rod 21 and a movable outer sleeve rod 22 sleeved on the outer side of the movable inner sleeve rod 21, wherein the movable inner sleeve rod 21 can slide in the movable outer sleeve rod 22 and can be clamped and positioned through a clamping bolt 23; the end of the movable inner loop bar 21 and the end of the movable outer loop bar 22 are fixedly connected to the fixed base 5 and the movable base 6 respectively.

Preferably, the movable inner loop bar 21 and the rotary inner loop bar 24 are marked with scales, so that the loop bar is convenient to position.

The automatic height adjusting mechanism comprises a multi-stage hydraulic lifting cylinder 14, a displacement sensor 15 and a base 16. The multistage hydraulic lifting cylinder 14 is vertically arranged on the base 16, and the piston rod end of the multistage hydraulic lifting cylinder 14 is fixedly connected with the bottom end of the first stepping motor 13; the displacement sensor 15 is fixed at the bottom end of the first stepper motor 13.

The inside of each lower hydraulic lifting cylinder in the multistage hydraulic lifting cylinders 14 is provided with a movable rail, the bottom of each upper hydraulic lifting cylinder is provided with a rail groove matched with the movable rail, and the hydraulic cylinders are limited to rotate, so that the multistage hydraulic lifting cylinders 14 can only vertically lift.

The strain gauge 41 on each polypropylene sheet 2 is connected with one voltage amplifier 3 through a wire, and each voltage amplifier 3 is connected with the data acquisition card 10 through a wire; the data acquisition card 10 can acquire multiple groups of voltage data at the same time, and transmits the voltage data to a remote computer end through the wireless transmission module 11 to record and draw a wind field diagram.

As shown in fig. 3, two pairs of parallel strain gauges 41 alternately arranged in opposite directions are adhered to the surface of the polypropylene sheet 2 through an adhesive sheet 42, and the two pairs of strain gauges are sequentially arranged in the following order: a first strain gage a, a second strain gage b, a third strain gage c, and a fourth strain gage d; the first strain gauge a and the third strain gauge c are stuck on the front surface, and the second strain gauge b and the fourth strain gauge d are stuck on the back surface.

The strain gauge 41 is an elongated strain gauge, and preferably, the length of the strain gauge 41 is 5cm; too short a length has insignificant resistance change, and too long a length can increase the area of the polypropylene sheet and reduce the measurement accuracy. The strain gauge 41 adopts differential full-bridge connection, the circuit connection mode is shown in fig. 4, and compared with the connection of a single bridge and a differential half-bridge, the strain gauge has better sensitivity, and the measured voltage change precision is more accurate. The output voltage difference is U, the power supply voltage is E, the connection ports of the power supply and the strain gauge are connected with the voltage amplifier 3, the positive electrode of the power supply is connected with the VCC end of the voltage amplifier 3, and the negative electrode of the power supply is connected with the GND end. E. Two ends of the U are respectively connected with four interfaces of the P end of the voltage amplifier 3, the out end of all the voltage amplifiers 3 is connected with the data acquisition card 10 to transmit a differential pressure signal U, and the data acquisition card 10 only needs one port to be connected with GND.

When no wind exists, the polypropylene sheets 2 are in a horizontal state, the resistance value of the voltage amplifier 3 is adjusted to enable the output voltage difference U to be 0, when the wind direction is along the positive direction of the Z axis of the three-dimensional coordinate system, each polypropylene sheet 2 and each strain gauge 41 are downwards bent, the first strain gauge a and the third strain gauge c which are stuck on the front face are stretched, the resistance value is increased, the second strain gauge b and the fourth strain gauge d which are stuck on the back face are compressed, the resistance value is reduced, and the output voltage difference U is positive; when the wind direction is along the negative Z-axis direction, the strain gauge 41 is bent upwards, the first strain gauge a and the third strain gauge c stuck on the front side are compressed, the resistance is reduced, the second strain gauge b and the fourth strain gauge d stuck on the back side are stretched, the resistance is increased, and the output voltage difference U is negative. Thus, the positive and negative of the output voltage difference U represent opposite wind directions. Theoretically, the relationship between wind speed v and output voltage difference U is:

Wherein U is the output voltage difference, E is the power supply voltage, E ^* Calibrating coefficient, K for polypropylene sheet deformation model ^* The mu is the Poisson ratio of the strain gauge material and r is the correlation coefficient between the relative deformation of the length of the strain gauge and the relative deformation of the polypropylene gauge in the vertical plane direction ₀ Is the air density under the state of maximum wind speed, v is bearableIs subjected to the maximum wind speed.The deformation of the polypropylene sheet in the vertical plane direction under the condition of wind pressure is negative, and the upward bending is positive, wherein r ₀ The air density under the wind pressure state is v is the wind speed variation, E ^* And calibrating the coefficient for the polypropylene sheet deformation model in the state.

The working mode of the wind field detection device based on micro strain is as follows:

before detection, a target detection point is required to be determined, the target detection point must be 3×3, 5×5 or 7×7, etc. apart from an array point, the array center point is O, the distance between two adjacent points is the detection distance d, a group of polypropylene sheets 2 and voltage amplifiers 3 are arranged at each point, and a corresponding number of support bar rotating mechanisms and wind measuring distance adjusting mechanisms are required correspondingly and are adhered to a target position for fixing.

Taking fig. 1 as an example, the support bar rotating mechanism comprises three support bars 4, which are arranged at equal intervals of 3×3. When the distance is adjusted, the distance between the wind measuring points is determined by adjusting the distance between the movable base 6 on the left and the right sides and the middle fixed base 5. As shown in fig. 2, the distance between the two bases is adjusted to adjust the distance between the two support bars, the distance between the right side support bar 4 and the middle support bar 4 is equal to the distance between the right side moving base 6 and the fixed base 5, and the distances between the right side rotating outer wheel 33 and the rotating driven gear 31 and the center of the riveting points of the rotating inner loop bar 24 and the rotating outer loop bar 25 respectively. The two clamping bolts 23 and the inner hexagon bolts 25 on the right side are loosened, the relative distance between the rotary inner sleeve rod 24 and the rotary outer sleeve rod 25 is changed to reach the target distance, and then the inner hexagon bolts 26 are screwed down to limit the movement of the rotary sleeve rod. To ensure synchronous rotation of the right-side rotary outer race 33 and the rotary driven gear 31, the total length of the fit of the movable outer race 22 and the movable inner race 21 should satisfy a difference from the target distance of the horizontal distance of the center of the rotary bearing 7 from the right side wall of the fixed base 6. The two-sided clamping bolts 23 are then tightened, limiting the movement of the right-side moving base 6. Similarly, the distance adjustment of the left side moving base is the same as that of the right side moving base, and two sides are required to be symmetrically arranged.

In order to realize automatic adjustment of the height of the rotating frame, the power supply 9 is started, the wireless transmission module 11 is used for receiving signals of a remote computer end, the control module 17 is used for transmitting instructions to the multi-stage hydraulic lifting cylinder 14, the height is pressurized and lifted, the height is reduced, the displacement sensor 15 is used for monitoring the height information in real time and transmitting the height information to the control module 17, and then the wireless transmission module 11 is used for transmitting the height information to the remote computer end for display, so that lifting is stopped when the target height is reached.

When the wind field is detected, firstly, the wind field detection device is returned to an initial state, the power supply 9 is started, the remote computer end sends an instruction to the control module 17, the multistage hydraulic lifting cylinder 14 is controlled to be adjusted to a detection height, and the displacement sensor 15 monitors the height in real time and feeds back the height to the remote computer end through the control module 17; the remote computer end sends an instruction to the control module 17 to control the first stepping motor 13 and the second stepping motor 34 to return to the initial rotation angles, and the first angle sensor 18 and the second angle sensor 30 respectively monitor the rotation of the horizontal rotating mechanism to the horizontal initial rotation angle alpha in real time ₀ And the support bar rotating mechanism rotates to the initial rotation angle beta of the support bar ₀ The real-time feedback is sent back to the computer end through the control module 17, and the nine groups of polypropylene sheets 2 are rotated to a horizontal state, so that a coordinate system XYZ is established according to a coordinate system calibration mode; in the initial state, the wind speed in the Z-axis direction can be detected, and the polypropylene sheet 2 is positioned on the XOY plane; when the wind speed in the Y-axis direction is detected, the supporting bar rotating mechanism needs to rotate 90 degrees clockwise, so that the polypropylene sheet 2 is positioned on the XOZ plane, a computer end sends an instruction to the control module 17 through the wireless transmission module 11, the control module 17 controls the second stepping motor 34 to rotate anticlockwise, the second stepping motor 34 drives the driving gear 32 to rotate, the rotating driven gear 31 drives the two side rotating outer wheels 33 to synchronously rotate through the rotating inner loop bar 24 and the rotating outer loop bar 25, and the angle sensor 30 monitors the rotating angle of the supporting bar 4 in real time, feeds back the rotating angle to the control module 17 and transmits the rotating angle to a remote computer end for display through the wireless transmission module 11; when the wind speed in the X-axis direction is detected, after the supporting bar rotating mechanism rotates 90 degrees clockwise, the horizontal rotating mechanism needs to be adjusted to rotate 90 degrees clockwise, the polypropylene sheet 2 is positioned on the YOZ plane, a computer end sends an instruction to the control module 17 through the wireless transmission module 11, and the control module 17 controls the first stepping motor 13 to rotate clockwise to drive The rotary disc 12 and the whole rotary frame 1 rotate around the center of the output shaft of the first stepping motor 13, the first angle sensor 18 monitors the rotating angle of the rotary frame 1 in real time, and the rotating angle is fed back to the control module 17 and is transmitted to a remote computer end for display through the wireless transmission module 11. Wherein, when the second stepping motor 34 rotates, the rotating inner loop bar 24 and the rotating outer loop bar 25 are always in a horizontal state, and the two rotating outer loop bars 33 and the rotating driven gear 31 drive the rotating bearings 7 and the supporting bars 4 which are respectively connected to rotate by the same angle, thereby ensuring that the three supporting bars 4 and the nine polypropylene sheets 2 are always parallel to each other, and bending deformation of different degrees occurs on the polypropylene sheets 2 along with different wind pressures, and the larger the wind speed is, the larger the deformation is. The strain gauge changes along with the wind field sensed by the polypropylene sheet 2, the larger the bending degree of the strain gauge is, the larger the resistance value is changed, the larger the output voltage difference U is, and the positive and negative of the output voltage difference U represent opposite wind directions. The nine voltage amplifiers 3 transmit differential pressure signals to the data acquisition card 10, and the data acquisition card 10 acquires nine groups of data simultaneously and transmits the nine groups of data to a remote computer end for recording and drawing a wind field diagram through the wireless transmission module 11. After the detection is finished, the polypropylene sheet 2 is rotated to be in a vertical state, so that the polypropylene sheet is prevented from sagging due to the influence of gravity when the polypropylene sheet is not used for a long time.

An online wind field detection method comprises the following steps:

the three-dimensional coordinate system of the calibration wind field detection device is shown in fig. 1, and the X-direction view is a front view of the wind field detection device.

Adjusting the wind field detection device to an initial state: the multistage hydraulic lift cylinder 14 is at the highest elevation, and the horizontal initial rotation angle of the first angle sensor 18 is alpha ₀ The support bar of the second angle sensor 30 has an initial rotation angle beta ₀ The polypropylene sheet 2 is in a horizontal state;

the center point of the rotating frame 1 on the horizontal plane of the polypropylene sheet 2 is set as the origin O of the three-dimensional coordinate system. The X axis is parallel to the support bar 4 and the positive direction is backward. The Y axis is perpendicular to the supporting bar 4 and the positive direction is leftward. The Z axis is perpendicular to the XOY horizontal plane, with the positive direction downward. The coordinate system does not change along with rotation, and the clockwise rotation and the anticlockwise rotation of the horizontal rotation mechanism and the support bar rotation mechanism are respectively determined by observing along the Z, X positive direction.

b1, setting an anemometer at a certain test distance (preferably 20 cm) from the air outlet of the fan with adjustable rotating speed, and respectively measuring n wind speeds v which are gradually increased _i (i=0, 1,2,3 … n) with a wind speed in the range of 0 to 10m/s, where when v ₀ When=0, the resistance of the voltage amplifier 3 is adjusted to make the output voltage difference U be 0, i.e. U ₀ ＝0。

b2, blowing the fan out n wind speeds v measured along the positive Z-axis direction and the negative Z-axis direction of the polypropylene sheet 2 in any horizontal state respectively at the test distance _i Progressively increasing wind, and n wind speeds v measured respectively in the positive Y-axis direction and the negative Y-axis direction of the polypropylene sheet 2 in any vertical state _i Gradually increasing wind; in the process, the data of the corresponding voltage amplifier 3 is acquired by the data acquisition card 10 to obtain the wind speed v under different wind directions _i Corresponding output voltage difference U _i Finally, respectively obtaining a relation model of wind speed v and output voltage difference U in the Z-axis positive direction, the Z-axis negative direction, the Y-axis positive direction, the Y-axis negative direction, the X-axis positive direction and the X-axis negative direction which are expressed by a formula 2; because the polypropylene sheet 2 and the wind speed in the Y-axis direction are arranged in a vertical state when the wind speed in the X-axis direction is detected, the relation model of the positive direction of the X-axis and the positive direction of the Y-axis is the same, and the relation model of the negative direction of the X-axis and the negative direction of the Y-axis is the same. Performing polynomial fitting on the obtained n different wind speed values in different wind directions and the output voltage difference signals to establish wind speedModel of output voltage difference U and determine error correction coefficient k _j ：

v＝k _j U (j=1, 2,3, 4) equation 2

Wherein v is wind speed, and the unit is m/s; u is the output voltage difference of the voltage amplifier 3, and the unit is V; k (k) _j Error correction coefficient k for different wind directions ₁ Is vertically squareCalibration coefficient, k, of wind direction (i.e. positive Z axis direction) ₂ The wind direction calibration coefficient is k for the vertical negative direction (namely the negative direction of the Z axis) ₃ The wind direction calibration coefficient k is the wind direction calibration coefficient in the horizontal positive direction (i.e. the X, Y axis positive direction) ₄ Wind direction calibration coefficients are for the horizontal negative direction (i.e. the X, Y axis negative direction).

Preferably, due to the spacing between the fans of the fans, the resulting wind velocity v _i With small ripple, the resulting output voltage difference U _i For continuous value with small change, taking multiple output voltage difference values measured in unit time, taking average value as accurate value U _i ；

The specific process of the step b2 is as follows:

b2.1, the fan is moved to a position right above the polypropylene sheet 2 in any horizontal state for testing a distance (20 cm), and n wind speeds v are blown downwards in sequence _i Progressively increasing wind at wind speed v _i When the polypropylene sheet 2 is bent downwards in cooperation with the strain gauge 41 to deform, the resistance value of the strain gauge 41 is changed, the output differential voltage is changed, the data acquisition card 10 acquires the voltage data of the voltage amplifier 3, and the wireless transmission module 11 is used for transmitting different wind speeds v _i Corresponding output voltage difference U _i Transmitting to a remote computer end for displaying and recording, and obtaining a polynomial fitting relation model of the wind speed v and the output voltage difference U in the positive direction of the Z axis by the remote computer end according to a formula 2: v=k ₁ U。

b2.2, changing the fan to a position right below the polypropylene sheet 2 in any horizontal state at a test distance (20 cm), and sequentially blowing n wind speeds v upwards _i The wind gradually increases step by step, other operations are the same as those in the step b2.1, and the voltage and wind speed are negative at the moment, so that a polynomial fitting relation model of the wind speed v in the negative direction of the Z axis and the output voltage difference U is obtained: v=k ₂ U。

b2.3, changing a fan into a fan which blows in the positive direction of the Y axis, testing the distance unchanged, rotating the support bar 4 clockwise by 90 degrees, adjusting the polypropylene sheet 2 to be vertically downward and vertical to the Y axis, and other operations are the same as those in the step b2.1, wherein the voltage and the wind speed are positive values at the moment, and obtaining a polynomial fitting relation model of the wind speed v in the positive direction of the Y axis and the output voltage difference U: v=k ₃ U, U. Positive direction of X-axis and YThe relationship model in the axial direction is the same.

b2.4, changing the fan into blowing along the negative direction of the Y axis, and other operations are the same as those in the step b2.1, wherein the voltage and the wind speed are negative at the moment, and a polynomial fitting relation model of the wind speed v of the negative direction of the Y axis and the output voltage difference U is obtained: v=k ₄ U, U. The relationship model of the X-axis negative direction and the Y-axis negative direction is the same.

c. Wind field detection:

In the formula, v _z Wind speed in Z-axis direction, v _y Wind speed in Y-axis direction, v _x The wind speed is in the X-axis direction, and the unit is m/s.Is a three-dimensional vector and comprises wind direction and wind speed value information; v _x 、v _y 、v _z Including positive and negative direction information and wind speed.

The specific process of the step c2 is as follows:

1) The polypropylene sheet 2 in a horizontal state can detect the wind field wind speed v in the Z-axis direction _z The polypropylene sheet 2 corresponding to each detection coordinate is cooperated with the strain gauge 41 to sense the bending deformation of the wind field, the resistance value of the strain gauge 41 is changed, the output differential voltage is changed, the data acquisition card 10 acquires the voltage data of each voltage amplifier 3, and the output voltage difference U in the Z-axis direction corresponding to each detection coordinate is acquired through the wireless transmission module 11 _z Transmitting to a remote computer terminal, and the remote computer terminal converting U according to the relation model of the wind speed v and the output voltage difference U in the positive direction or the negative direction of the Z axis in the step b _z Conversion to v _z And records the data. Wherein U is _z Is positive, using an error correction coefficient k ₁ Calculating the wind speed and the wind direction along the positive direction of the Z axis by the positive direction relation model of the Z axis; u (U) _z When the value of (2) is negative, the error correction coefficient is k ₂ Calculating wind speed by a Z-axis negative direction model, and enabling wind direction to be along the Z-axis negative direction;

2) To detect the wind speed v in the Y-axis direction _y The supporting bar 4 rotates 90 degrees clockwise, the polypropylene sheet 2 is adjusted to be vertically downward, vertical to the Y axis and parallel to the X axis, and the output voltage difference U in the Y axis direction corresponding to each detection coordinate can be obtained in the same way _y B, the remote computer end calculates U according to a relation model of wind speed v in the positive direction of the Y axis or the negative direction of the Y axis in the step b and the output voltage difference U _y Conversion to v _y And records the data. Wherein U is _y Is positive, using an error correction coefficient k ₃ Calculating wind speed by a Y-axis positive direction model, wherein the wind direction is along the Y-axis positive direction; u (U) _y When the value of (2) is negative, the error correction coefficient is k ₄ Y axis of (C)The negative direction model calculates wind speed, wind direction along the negative Y-axis direction.

3) To detect the wind speed v in the X-axis direction _x The polypropylene sheet 2 is kept in a vertical state, and the horizontal rotating mechanism rotates 90 degrees clockwise to enable the polypropylene sheet 2 to be perpendicular to the X axis and parallel to the Y axis, and at the moment, the position of the original polypropylene sheet 2 is changed, but each detection coordinate corresponds to a new polypropylene sheet 2; similarly, the output voltage difference U in the X-axis direction corresponding to each detection coordinate can be obtained _x B, the remote computer end calculates U according to the relation model of the wind speed v in the positive direction of the X axis or the negative direction of the X axis and the output voltage difference U in the step b _x Conversion to v _x And records the data. Wherein U is _x Is positive, using an error correction coefficient k ₃ Calculating wind speed by an X-axis positive direction model, wherein the wind direction is along the X-axis positive direction; u (U) _x When the value of (2) is negative, the error correction coefficient is k ₄ The wind speed is calculated by the X-axis negative direction model, and the wind direction is along the X-axis negative direction.

Preferably, in the step c1, the detection heights of the wind field detection devices are adjusted by remotely controlling the multi-stage hydraulic lifting cylinder 14, so as to realize wind field detection of different levels.

Preferably, in the step c1, the measured wind distance is changed by adjusting the wind distance adjusting mechanism and the distance between the polypropylene sheets 2 on the supporting strips 4.

When evaluating the wind field, the uniformity of the wind field is critical, the uniformity of the wind speed in the horizontal direction is required to be detected in a wind tunnel test, and the uniformity of the wind speed in the vertical direction is required to be detected in the air flow of the unmanned plane rotor wing.

An online wind field distribution uniformity evaluation method comprises the following steps:

Adjusting the wind field detection device to an initial state: the multi-stage hydraulic lift cylinder 14 is at the highest elevation, the first angle sensor 18Is alpha ₀ The support bar of the second angle sensor 30 has an initial rotation angle beta ₀ The polypropylene sheet 2 is in a horizontal state;

b2, blowing the fan out n wind speeds v measured along the positive Z-axis direction and the negative Z-axis direction of the polypropylene sheet 2 in any horizontal state respectively at the test distance _i Progressively increasing wind, and n wind speeds v measured respectively in the positive Y-axis direction and the negative Y-axis direction of the polypropylene sheet 2 in any vertical state _i Gradually increasing wind; in the process, the data of the corresponding voltage amplifier 3 is acquired by the data acquisition card 10 to obtain the wind speed v under different wind directions _i Corresponding output voltage difference U _i Finally, respectively obtaining a relation model of wind speed v and output voltage difference U in the Z-axis positive direction, the Z-axis negative direction, the Y-axis positive direction, the Y-axis negative direction, the X-axis positive direction and the X-axis negative direction which are expressed by a formula 2; because the polypropylene sheet 2 and the wind speed in the Y-axis direction are arranged in a vertical state when the wind speed in the X-axis direction is detected, the relation model of the positive direction of the X-axis and the positive direction of the Y-axis is the same, and the relation model of the negative direction of the X-axis and the negative direction of the Y-axis is the same. Performing polynomial fitting on the obtained n different wind speed values in different wind directions and the output voltage difference signals, establishing a model of wind speed v and output voltage difference U, and determiningConstant error correction coefficient k _j ：

v＝k _j U (j=1, 2,3, 4) equation 2

Wherein v is wind speed, and the unit is m/s; u is the output voltage difference of the voltage amplifier 3, and the unit is V; k (k) _j Error correction coefficient k for different wind directions ₁ The wind direction calibration coefficient k is the vertical positive direction (namely the Z-axis positive direction) ₂ The wind direction calibration coefficient is k for the vertical negative direction (namely the negative direction of the Z axis) ₃ The wind direction calibration coefficient k is the wind direction calibration coefficient in the horizontal positive direction (i.e. the X, Y axis positive direction) ₄ Wind direction calibration coefficients are for the horizontal negative direction (i.e. the X, Y axis negative direction).

The specific process of the step b2 is as follows:

b2.2, the fan is moved to the position right below the polypropylene sheet 2 in any horizontal state, and n wind speeds v are blown upwards in sequence at the test distance (20 cm) _i The wind gradually increases step by step, other operations are the same as those in the step b2.1, and the voltage and wind speed are negative at the moment, so that a polynomial fitting relation model of the wind speed v in the negative direction of the Z axis and the output voltage difference U is obtained: v=k ₂ U。

b2.3, changing the fan into a fanBlowing in the positive direction of the Y axis, testing the distance unchanged, rotating the support bar 4 clockwise by 90 degrees, adjusting the polypropylene sheet 2 to be vertical downwards and vertical to the Y axis, and other operations are the same as those in the step b2.1, wherein the voltage and the wind speed are positive values at the moment, and obtaining a polynomial fitting relation model of the wind speed v in the positive direction of the Y axis and the output voltage difference U: v=k ₃ U, U. The relationship model of the positive X-axis direction and the positive Y-axis direction is the same.

c. And (3) evaluating the distribution uniformity of the wind field:

In the formula, the units of alpha and beta are degrees.

Then the horizontal rotating mechanism and the supporting bar rotating mechanism are respectively driven by the first stepping motor 13 and the second stepping motor 34 to rotate by corresponding angles, so that the polypropylene sheet 2 of each detection coordinate is vertical to the wind direction (x, y, z) of the detected wind field; when alpha is positive, the horizontal rotating mechanism rotates clockwise, and when alpha is negative, the horizontal rotating mechanism rotates anticlockwise; and when beta is positive value, the supporting bar rotating mechanism rotates clockwise, and when beta is negative value, the supporting bar rotating mechanism rotates anticlockwise.

The polypropylene sheets 2 cooperate with the strain sheets 41 to sense the bending deformation of the wind field, the resistance value of the strain sheets 41 changes, and the output difference is obtainedThe voltage of the motor changes, the data acquisition card 10 acquires the voltage data of each voltage amplifier 3, and transmits the output voltage difference signal U to a remote computer end through the wireless transmission module 11, and the remote computer end calculates the wind speed value corresponding to the mth polypropylene sheet 2 through the formula 7

In the method, in the process of the invention,the wind speed value of the mth detection point is m/s; u (U) _m The output voltage difference of the mth detection point is expressed as V; beta is the rotation angle of the support bar rotating mechanism, and the unit is degree, < + >>The direction is (x, y, z).

k _m U _m cos beta isWherein U is _m cos beta is U _m When U is the vertical partial voltage of _m cos beta is positive, using error correction factor k ₁ Calculating the wind speed in the vertical direction by using the relation model, and when U _m When cos beta is negative, then the error correction coefficient is k ₂ And (5) a relation model.

k _m ^* U _m sin beta isHorizontal component velocity of (1), wherein U _m sin beta is U _m Is equal to the horizontal partial voltage of U _m sin beta is positive, and the error correction coefficient is k ₃ Relational model computationWind speed in horizontal direction, when U _m When sin beta is negative, the error correction coefficient is k ₄ And (5) a relation model.

Preferably, the detection height of the wind field detection device is adjusted by remotely controlling the multi-stage hydraulic lifting cylinder 14 so as to obtain more wind speed values, and the wind speed standard deviation and the wind speed distribution variation coefficient of each plane in the space are calculated by substituting the wind speed values into the formula 7 and the formula 8.

The smaller the wind speed distribution variation coefficient CV and the standard deviation S are, the more uniform the wind speed of the wind field is. For wind fields with high requirements on wind speed uniformity, such as wind tunnel tests, if the variation coefficient CV of wind speed distribution exceeds 10%, the wind field structure needs to be optimized, so that the uniformity of wind speed of the wind field is improved.

Claims

1. Wind field detection device based on little meeting an emergency, its characterized in that: the device comprises a support bar rotating mechanism, a horizontal rotating mechanism, a wind measuring distance adjusting mechanism, a height automatic adjusting mechanism and a control mechanism;

the horizontal rotating mechanism comprises a rotating frame (1), a rotating disc (12), a first stepping motor (13) and a first angle sensor (18); the rotary frame (1) is a cuboid frame with a square cross section and comprises an upper square frame and a lower square frame which are horizontally arranged;

the lower end face of the rotary disc (12) is fixed on an output shaft of the first stepping motor (13), and the edge of the rotary disc (12) is fixedly connected with a square frame at the lower layer of the rotary frame (1) through a plurality of support spokes (8); two parts of the first angle sensor (18) are respectively fixed on the lower end surfaces of the first stepping motor (13) and the rotary disc (12);

the support bar rotating mechanism comprises a support bar (4), a fixed base (5), a movable base (6), a rotating bearing (7), a second angle sensor (30), a rotary driven gear (31), a driving gear (32), a rotary outer wheel (33) and a second stepping motor (34); two opposite cross beams in the upper square frame of the rotary frame (1) are provided with base moving grooves (19) along the length direction of the cross beams;

The pair of fixed bases (5) are respectively fixed in the middle parts of base moving grooves (19) of the two cross beams, the even pairs of moving bases (6) are horizontally movably arranged in the base moving grooves (19), and the even pairs of moving bases (6) are symmetrically distributed by connecting lines between the two fixed bases (5);

a rotating bearing (7) is arranged in each fixed base (5) and each movable base (6); a supporting bar (4) is fixedly connected between the rotating bearings (7) of the two mutually corresponding fixed bases (5) and between the rotating bearings (7) of each two mutually corresponding movable bases (6); a plurality of polypropylene sheets (2) and a plurality of voltage amplifiers (3) which are in one-to-one correspondence with the polypropylene sheets (2) are arranged on each supporting strip (4), and the polypropylene sheets (2) on each supporting strip (4) are distributed in an n multiplied by n equidistant array in a plane; the upper surface of the polypropylene sheet (2) is provided with a plurality of pairs of parallel strain gauges (41) which are alternately arranged in the front and back directions, and each strain gauge (41) is connected with the voltage amplifier (3) in a differential full-bridge connection mode;

the outer side of each fixed base (5) is provided with a rotary driven gear (31) connected with a rotary bearing (7) in the fixed base (5), and the outer side of each movable base (6) is provided with a rotary outer wheel (33) connected with the rotary bearing (7) in the movable base (6); the rotary driven gear (31) and the rotary outer wheels (33) on the same side are connected through a rotary connecting rod with adjustable length; the driving gear (32) is meshed with the rotary driven gear (31), and the driving gear (32) is connected with an output shaft of a second stepping motor (34) fixedly connected to a cross beam of the upper square frame of the rotary frame (1); two parts of the second angle sensor (30) are respectively fixed on the fixed base (5) and the rotary driven gear (31);

The wind measuring distance adjusting mechanism is fixedly connected between the fixed base (5) and the movable base (6);

the automatic height adjusting mechanism comprises a multi-stage hydraulic lifting cylinder (14), a displacement sensor (15) and a base (16); the multistage hydraulic lifting cylinder (14) is vertically arranged on the base (16), and the piston rod end of the multistage hydraulic lifting cylinder (14) is fixedly connected with the bottom end of the first stepping motor (13); the displacement sensor (15) is fixed at the bottom end of the first stepping motor (13);

the control mechanism comprises a power supply (9), a data acquisition card (10), a wireless transmission module (11) and a control module (17) which are arranged on the rotary disc (12);

each voltage amplifier (3) is connected with a data acquisition card (10); the data acquisition card (10) can acquire multiple groups of voltage data at the same time, and the voltage data are transmitted to a remote computer end through the wireless transmission module (11) to record and draw a wind field diagram;

the power supply (9) is used for supplying power to each voltage amplifier (3), the data acquisition card (10), the wireless transmission module (11), the first stepping motor (13), the multi-stage hydraulic lifting cylinder (14), the displacement sensor (15), the control module (17), the first angle sensor (18), the second angle sensor (30) and the second stepping motor (34);

the control module (17) controls the multi-stage hydraulic lifting cylinder (14), the first stepping motor (13) and the second stepping motor (34), receives monitoring data of the displacement sensor (15), the first angle sensor (18) and the second angle sensor (30), and communicates with a remote computer end through the wireless transmission module (11);

The support bar rotating mechanism comprises two pairs of moving bases (6), the rotating connecting rod comprises a rotating inner loop bar (24) and two rotating outer loop bars (25) which are respectively sleeved at two ends of the rotating inner loop bar (24), clamping and positioning are carried out between the rotating inner loop bar (24) and the rotating outer loop bars (25) through inner hexagon bolts (26), hexagon nuts (27) and front and rear gaskets (28), wherein the rotating inner loop bars (24) are riveted on a rotating driven gear (31), and the two rotating outer loop bars (25) are respectively riveted on two rotating outer wheels (33); the wind measuring distance adjusting mechanism comprises a movable inner sleeve rod (21) and a movable outer sleeve rod (22) sleeved on the outer side of the movable inner sleeve rod (21), wherein the movable inner sleeve rod (21) can slide in the movable outer sleeve rod (22) and is clamped and positioned through a clamping bolt (23); the tail end of the movable inner loop bar (21) and the tail end of the movable outer loop bar (22) are fixedly connected to the fixed base (5) and the movable base (6) respectively.

2. The microstrain-based wind farm detection device of claim 1, wherein: two pairs of parallel strain gauges (41) which are alternately arranged in the front and the back are stuck on the surface of the polypropylene sheet (2) through a sticking film (42), and the two strain gauges are sequentially as follows: a first strain gage (a), a second strain gage (b), a third strain gage (c), and a fourth strain gage (d); wherein the first strain gauge (a) and the third strain gauge (c) are stuck on the front surface, and the second strain gauge (b) and the fourth strain gauge (d) are stuck on the back surface.

3. An on-line wind field detection method using the microstrain-based wind field detection device of claim 1, wherein: the method comprises the following steps:

the wind field detection device is adjusted to an initial state, and the polypropylene sheet (2) is in a horizontal state;

setting the central point of a rotating frame (1) on the horizontal plane of a polypropylene sheet (2) as a three-dimensional coordinate system origin O, wherein an X axis is parallel to a supporting bar (4), a positive direction is backward, a Y axis is perpendicular to the supporting bar (4), a positive direction is leftward, a Z axis is perpendicular to an XOY horizontal plane, and a positive direction is downward;

b1, setting an anemometer at a certain test distance from an air outlet of the fan with adjustable rotating speed, and respectively measuring n wind speeds v which are gradually increased _i (i=0, 1,2,3 … n) with a wind speed in the range of 0 to 10m/s, where when v ₀ When=0, the resistance of the voltage amplifier (3) is adjusted to make the output voltage difference U be 0, i.e. U ₀ ＝0；

b2, blowing the fan out n wind speeds v measured along the positive Z-axis direction and the negative Z-axis direction of the polypropylene sheet (2) in any horizontal state respectively at the test distance _i Progressively increasing wind, and respectively blowing out n measured wind speeds v along the positive direction and the negative direction of the Y axis to the polypropylene sheet (2) in any vertical state _i Gradually increasing wind; in the process, the data of the corresponding voltage amplifier (3) are acquired by the data acquisition card (10) to obtain the wind speed v under different wind directions _i Corresponding output voltage difference U _i Finally, respectively obtaining a relation model of wind speed v and output voltage difference U in the Z-axis positive direction, the Z-axis negative direction, the Y-axis positive direction, the Y-axis negative direction, the X-axis positive direction and the X-axis negative direction which are expressed by a formula 2; wherein, the relation model of the positive direction of the X axis and the positive direction of the Y axis is the same, and the relation model of the negative direction of the X axis and the negative direction of the Y axis is the same; performing polynomial fitting on the obtained n different wind speed values in different wind directions and the output voltage difference signals, establishing a model of wind speed v and output voltage difference U, and determining an error correction coefficient k _j ：

c. wind field detection:

c1, placing a wind field detection device adjusted to an initial state at a detection position of a wind field to be detected, and simultaneously recording detection coordinates of each polypropylene sheet (2) in a three-dimensional coordinate system;

c2, respectively recording the output voltage difference U in the Z-axis direction of the polypropylene sheet (2) in each horizontal state corresponding to each detection coordinate _z Output voltage difference U in Y-axis direction of polypropylene sheet (2) in each vertical state _y Output voltage difference U in X-axis direction _x The method comprises the steps of carrying out a first treatment on the surface of the According to each U _z 、U _y And U _x B, selecting a relation model of wind speeds v and output voltage differences U of the Z-axis positive direction, the Z-axis negative direction, the Y-axis positive direction, the Y-axis negative direction, the X-axis positive direction and the X-axis negative direction obtained in the step b, and respectively obtaining the wind speeds v of the Z-axis directions corresponding to all detection coordinates _z Wind speed v in Y-axis direction _y And wind speed v in X-axis direction _x ；

4. A method according to claim 3, characterized in that: the specific process of the step b2 is as follows:

b2.1, moving the fan to a test distance position right above the polypropylene sheet (2) in any horizontal state, and sequentially blowing down n wind speeds v _i Progressively increasing wind at wind speed v _i When the polypropylene sheet (2) is bent downwards in cooperation with the strain gauge (41) to deform, the resistance value of the strain gauge (41) is changed, the output differential voltage is changed, the data acquisition card (10) acquires voltage data of the voltage amplifier (3), and different wind speeds v are obtained through the wireless transmission module (11) _i Corresponding output voltage difference U _i Transmitting to a remote computer end for displaying and recording, and obtaining a polynomial fitting relation model of the wind speed v and the output voltage difference U in the positive direction of the Z axis by the remote computer end according to a formula 2: v=k ₁ U；

b2.2, changing the fan to a test distance position right below the polypropylene sheet (2) in any horizontal state, and sequentially blowing n wind speeds v upwards _i The wind gradually increases step by step, other operations are the same as those in the step b2.1, and the voltage and wind speed are negative at the moment, so that a polynomial fitting relation model of the wind speed v in the negative direction of the Z axis and the output voltage difference U is obtained: v=k ₂ U；

b2.3, changing a fan into a fan which blows in the positive direction of the Y axis, testing the distance unchanged, rotating the supporting bar (4) by 90 degrees clockwise, adjusting the polypropylene sheet (2) to be vertically downward and vertical to the Y axis, and other operations are the same as those in the step b2.1, wherein the voltage and the wind speed are positive values at the moment, and obtaining a polynomial fitting relation model of the wind speed v in the positive direction of the Y axis and the output voltage difference U: v=k ₃ U is provided; the relation model of the positive X-axis direction and the positive Y-axis direction is the same;

5. A method according to any one of claims 3-4, characterized in that: the specific process of the step c2 is as follows:

1) The polypropylene sheet (2) in a horizontal state can detect the wind field wind speed v in the Z-axis direction _z The polypropylene sheet (2) corresponding to each detection coordinate senses bending deformation of a wind field in cooperation with the strain gauge (41), the resistance value of the strain gauge (41) changes, the output differential voltage changes, the data acquisition card (10) acquires voltage data of each voltage amplifier (3), and the output voltage difference U in the Z-axis direction corresponding to each detection coordinate is acquired through the wireless transmission module (11) _z Transmitting to a remote computer terminal, and the remote computer terminal converting U according to the relation model of the wind speed v and the output voltage difference U in the positive direction or the negative direction of the Z axis in the step b _z Conversion to v _z And recording the data; wherein U is _z Is positive, using an error correction coefficient k ₁ Calculating the wind speed and the wind direction along the positive direction of the Z axis by the positive direction relation model of the Z axis; u (U) _z When the value of (2) is negative, the error correction coefficient is k ₂ Calculating wind speed by a Z-axis negative direction model, and enabling wind direction to be along the Z-axis negative direction;

2) To detect the wind speed v in the Y-axis direction _y The supporting bar (4) rotates 90 degrees clockwise, the polypropylene sheet (2) is adjusted to be vertically downward, vertical to the Y axis and parallel to the X axis, and the output voltage difference U in the Y axis direction corresponding to each detection coordinate is obtained _y B, the remote computer end calculates U according to a relation model of wind speed v in the positive direction of the Y axis or the negative direction of the Y axis in the step b and the output voltage difference U _y Conversion to v _y And recording the data; wherein U is _y Is positive, using an error correction coefficient k ₃ Calculating wind speed by a Y-axis positive direction model, wherein the wind direction is along the Y-axis positive direction; u (U) _y When the value of (2) is negative, the error correction coefficient is k ₄ Calculating wind speed by a Y-axis negative direction model, and enabling wind direction to be along the Y-axis negative direction;

3) To detect the wind speed v in the X-axis direction _x The polypropylene sheet (2) is kept in a vertical state, and the horizontal rotating mechanism rotates 90 degrees clockwise to enable the polypropylene sheet (2) to be perpendicular to the X axis and parallel to the Y axis, and the position of the original polypropylene sheet (2) is changed at the moment, but each detection coordinate is optionally matched with a new polypropylene sheet (2)) Corresponding to the above; obtaining the output voltage difference U of the X-axis direction corresponding to each detection coordinate _x B, the remote computer end calculates U according to the relation model of the wind speed v in the positive direction of the X axis or the negative direction of the X axis and the output voltage difference U in the step b _x Conversion to v _x And recording the data; wherein U is _x Is positive, using an error correction coefficient k ₃ Calculating wind speed by an X-axis positive direction model, wherein the wind direction is along the X-axis positive direction; u (U) _x When the value of (2) is negative, the error correction coefficient is k ₄ The wind speed is calculated by the X-axis negative direction model, and the wind direction is along the X-axis negative direction.

6. A method according to claim 3, characterized in that: in the step c1, a multistage hydraulic lifting cylinder (14) is controlled to adjust the detection height of a wind field detection device, so that wind field detection of different horizontal planes is realized; the change of the measured wind distance is realized by adjusting the wind distance adjusting mechanism and the interval distance of the polypropylene sheet (2) on the supporting bar (4).

7. An on-line wind field distribution uniformity evaluation method using the micro-strain based wind field detection device of claim 1, characterized in that: the method comprises the following steps:

b1, setting an anemometer at a certain test distance from an air outlet of the fan with adjustable rotating speed, and respectively measuring n wind speeds v which are gradually increased _i (i=0, 1,2,3 … n) with a wind speed in the range of 0 to 10m/s, where when v ₀ When=0, the resistance of the voltage amplifier (3) is adjusted to make the output voltage difference UIs 0, i.e. U ₀ ＝0；

v＝k _j U (j=1, 2,3, 4) equation 2

c. and (3) evaluating the distribution uniformity of the wind field:

wherein, the units of alpha and beta are degrees;

then the horizontal rotating mechanism and the supporting bar rotating mechanism are respectively driven by the first stepping motor (13) and the second stepping motor (34) to rotate by corresponding angles, so that the polypropylene sheet (2) of each detection coordinate is vertical to the wind direction (x, y, z) of the detected wind field;

each polypropylene sheet (2) senses bending deformation of a wind field in cooperation with a strain gauge (41), the resistance value of the strain gauge (41) changes, the output differential voltage changes, a data acquisition card (10) acquires voltage data of each voltage amplifier (3), an output voltage difference signal U is transmitted to a remote computer end through a wireless transmission module (11), and the remote computer end calculates a wind speed value corresponding to an mth polypropylene sheet (2) through a formula 7

k _m U _m cos beta isIs vertical to (2)Direct speed of separation, U _m cos beta is U _m When U is the vertical partial voltage of _m cos beta is positive, using error correction factor k ₁ Calculating the wind speed in the vertical direction by using the relation model, and when U _m When cos beta is negative, then the error correction coefficient is k ₂ A relationship model;

calculating the standard deviation of the wind speed of each polypropylene sheet (2) through a formula 8, and then calculating the variation coefficient of the wind speed distribution of each polypropylene sheet (2) through a formula 9:

wherein S is the standard deviation of wind speed of each polypropylene sheet (2),for the average wind speed>The wind speed value of the mth detection point is m/s; q is the total number of detected points; CV is the variation coefficient of wind speed distribution of each point in the plane where the polypropylene sheet (2) is positioned, and the unit is percent.

8. The method according to claim 7, wherein: the specific process of the step b2 is as follows:

b2.2, changing the fan to be under the polypropylene sheet (2) in any horizontal state, and sequentially blowing n wind speeds v upwards at the test distance _i The wind gradually increases step by step, other operations are the same as those in the step b2.1, and the voltage and wind speed are negative at the moment, so that a polynomial fitting relation model of the wind speed v in the negative direction of the Z axis and the output voltage difference U is obtained: v=k ₂ U；

9. The method according to claim 7, wherein: the multistage hydraulic lifting cylinder (14) is controlled to adjust the detection height of the wind field detection device so as to obtain wind speed values of more points, and the wind speed values are substituted into the formula 7 and the formula 8 to calculate the wind speed standard deviation and the wind speed distribution variation coefficient of each plane in the space.