Magnus device and method for measuring large cross-section duct velocity skew and volume

Abstract

The application relates to the technical field and provides a Magnus device and method for measuring the velocity deviation and air volume of a large-section air duct, which comprises the following steps: arranging a plurality of hollow Magnus rollers in an array along the section of the air duct; rotating the plurality of Magnus rollers along the direction perpendicular to the air duct; respectively arranging closed slides above and below the Magnus rollers in the same horizontal direction; respectively connecting upper connecting blocks and lower connecting blocks to the top and bottom of each Magnus roller; arranging a motor in the lower connecting block; rotatingly connecting the output shaft of the motor with the Magnus roller through a roller connecting rod; extending the roller connecting rod from the Magnus roller and connecting the roller connecting rod with the output shaft of the motor; and arranging a displacement measuring mechanism or a pressure measuring mechanism in the closed slide on one side of the Magnus roller. The scheme can evaluate the wind speed distribution of the section at any moment under different air volumes at any time, improves the accuracy of the acquisition of original data, and has practical significance for the research on the air duct flow field distribution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wind speed and direction, and particularly relates to a Magnus device and method for measuring the velocity deviation and air volume of a large-section air duct. BACKGROUND

[0002] Due to the large section of the air duct, the wind speed distribution of the air duct section is very uneven. The commonly used matrix type air volume measuring device can only measure the air volume value, and cannot measure the wind speed of different regions of the section, so the wind speed distribution of the section cannot be effectively evaluated. The conventional manual measurement needs to open a measurement hole on the corresponding air duct, and the backrest pipe of different depths is inserted to cooperate with the micro pressure gauge to manually measure the points, the disadvantage of this method is that the cross-section wind speed is in a rapid fluctuation process, and the reading of the micro pressure gauge is also changing, so the dynamic pressure value read is greatly affected by human subjective factors, and the wind speed of the original measured point may have changed during the process of inserting the backrest pipe or replacing the measuring point, therefore the data obtained by this method is often greatly different from the actual situation, and the cross-section and air volume value cannot be accurately evaluated, which affects the subsequent data analysis. SUMMARY

[0003] To solve the problems in the background art, the application provides a Magnus device and method for measuring the velocity deviation and air volume of a large-section air duct, which can evaluate the wind speed distribution of the section at any time under different air volumes, improve the accuracy of the obtained original data, and has practical significance for studying the flow field distribution of the air duct.

[0004] To achieve the above-mentioned purpose, the application adopts the following scheme: a Magnus device for measuring the velocity deviation and air volume of a large-section air duct, the device is horizontally arranged, the device comprises a plurality of hollow Magnus rollers arranged in an array along the section of the air duct, the plurality of Magnus rollers rotate along the direction perpendicular to the air duct, the upper and lower sides of the Magnus rollers in the same horizontal direction are respectively provided with closed slides, the top and bottom of each Magnus roller is respectively connected with an upper connecting block and a lower connecting block, the upper connecting block and the lower connecting block are respectively arranged in the upper and lower closed slides, a motor is arranged in the lower connecting block, the output shaft of the motor is rotationally connected with the Magnus roller through a roller connecting rod, the roller connecting rod is arranged in the Magnus roller, one end of the roller connecting rod away from the Magnus roller extends out of the Magnus roller and is connected with the output shaft of the motor, a displacement measuring mechanism or a pressure measuring mechanism is arranged in the closed slide on one side of the Magnus roller;

[0005] The displacement measuring mechanism comprises a compression spring and an indicating line, the upper connecting block is fixedly connected with the Magnus cylinder, the upper and lower connecting blocks are slidably connected with the upper and lower airtight slides respectively, two compression springs are arranged on the same side of the compression spring, one end of each of the two compression springs is connected with the upper and lower connecting blocks respectively, and the other end of each of the two compression springs is fixed to the inner wall of the airtight slide, the indicating line is arranged on the same side of the compression spring, one end of the indicating line is fixed to the upper or lower connecting block, the other end of the indicating line extends out of the air duct, and a scale is arranged on the indicating line.

[0006] When the air direction of the air duct is the windward direction relative to the air duct section, the compression spring and the indicating line are arranged on the left side of the Magnus cylinder, and the Magnus cylinder is driven to rotate counterclockwise; when the air direction of the air duct is the leeward direction relative to the air duct section, the compression spring and the indicating line are arranged on the right side of the Magnus cylinder, and the Magnus cylinder is driven to rotate clockwise.

[0007] The pressure measuring mechanism comprises a pressure sensor, one end of the upper and lower connecting blocks away from the Magnus cylinder is fixed to the inner wall of the airtight slide, and the upper connecting block is rotatably connected with the Magnus cylinder through a bearing.

[0008] When the air direction of the air duct is the windward direction relative to the air duct section, the pressure sensor is fixed in any one of the upper and lower airtight slides close to the left side of the Magnus cylinder, and the Magnus cylinder is driven to rotate counterclockwise; when the air direction of the air duct is the leeward direction relative to the air duct section, the pressure sensor is fixed in any one of the upper and lower airtight slides close to the right side of the Magnus cylinder, and the Magnus cylinder is driven to rotate clockwise; and the pressure sensor is electrically connected with a controller.

[0009] Further, the motor is connected with a power supply, and the device is arranged at a position 3-5 times the equivalent diameter upstream or downstream of the elbow.

[0010] Further, when the air duct is a high-temperature air duct, the device is made of Q345B steel, and when the air duct is a normal-temperature air duct, the device is made of Q235 steel or PVC plastic lightweight material.

[0011] The method for measuring the speed deviation of a large-section air duct comprises the following steps:

[0012] Step A1, a plurality of sections are selected at intervals along the length direction of the air duct, and the Magnus device is arranged at each section;

[0013] Step A2, the displacement measuring mechanism is arranged at the left side or the right side of the Magnus roller according to the wind direction in the air duct, and the Magnus roller is driven to rotate counterclockwise or clockwise according to the wind direction in the air duct, at this time, the Magnus roller is subjected to leftward or rightward pressure, the compression spring is deformed, and the indicating line is displaced, the displacement value of the indicating line is obtained according to the scale change on the indicating line, and the displacement value of the indicating line represents the sampling point air duct velocity value of the area where the Magnus roller is located;

[0014] Step A3, the displacement values of the indicating lines of all the Magnus rollers in the section are obtained through step A2, and then the average displacement value of the indicating lines is calculated, and the average displacement value of the indicating lines represents the average velocity value of the air duct in the section;

[0015] Step A4, the displacement values of the indicating lines of the sampling points and the average displacement value of the indicating lines in the section in step A3 are substituted into the calculation formula to obtain the velocity standard deviation, wherein is the average displacement of the indicating lines in the section, which represents the average velocity of the air duct in the section, is the displacement of the indicating line of the sampling point J, which represents the velocity of the sampling point J, is the velocity standard deviation, and n is the number of partitions; the relative standard deviation rate is obtained through the calculation formula , wherein is the average velocity of the air duct in the section; and CV is the relative standard deviation rate.

[0016] The method for measuring the air volume of a large-section air duct comprises the following steps:

[0017] Step B1, a plurality of sections are selected at intervals along the length direction of the air duct, and the Magnus device is arranged at each section;

[0018] Step B2, the pressure sensor is arranged in the closed slide way at the left side or the right side of the Magnus roller according to the wind direction in the air duct, and the Magnus roller is driven to rotate counterclockwise or clockwise according to the wind direction in the air duct, at this time, the Magnus roller is subjected to leftward or rightward pressure, the pressure value of the Magnus roller is obtained through the pressure sensor, and the force bearing condition of the Magnus roller is converted into an electric signal in real time and transmitted to the controller;

[0019] Step B3, the sampling point air duct velocity value of the area where the Magnus roller is located is calculated through the pressure value of the Magnus roller;

[0020] Step B4, the sampling point air duct velocity values of the areas where all the Magnus rollers in the section are located are obtained through step B3, and then the average velocity value of the air duct in the section is calculated;

[0021] Step B5, the average wind speed value obtained in step B4 is substituted into the calculation formula Q=VA to obtain the air volume of the air duct section, wherein Q is the air volume, V is the average wind speed, and A is the air duct section area.

[0022] Further, in step B3, the method for calculating the fluid velocity value of the area where the Magnus roller is located by the pressure value of the Magnus roller is as follows: first, the radius and the angular velocity of rotation of the Magnus roller are measured and substituted into the calculation formula to obtain the circulation of the Magnus roller, wherein is the circulation, r is the radius of the Magnus roller, and w is the angular velocity of rotation of the Magnus roller; second, the pressure value of the Magnus roller and the circulation of the Magnus roller are substituted into the calculation formula to obtain the fluid velocity value of the area where the Magnus roller is located as the sampling point air duct velocity value, wherein p is the fluid density, V is the fluid velocity, and L is the pressure.

[0023] The present application has the beneficial effects that: the present application utilizes the principle that the rotating Magnus roller is subjected to a transverse force in the fluid, converts the wind speed which cannot be directly measured into force and measures the same, to represent the wind speed, can evaluate the wind speed distribution of the section at any time under different air volumes, improves the accuracy of the original data acquisition, and has practical significance for studying the air duct flow field distribution. The Magnus device with the displacement measuring mechanism can measure the velocity deviation of the large-section air duct, represents the sampling point air duct velocity value of the area where the Magnus roller is located through the displacement value of the indicating line, without converting the displacement into the velocity, and the data acquisition is convenient. In addition, the displacement measuring mechanism can be replaced by the pressure measuring mechanism, is converted into an electrical signal in real time and transmitted to the controller, and can be converted into the area wind speed according to the formula, and then the air duct air volume is calculated. The whole device has simple structure and is easy to operate, the data has timeliness, and the velocity deviation of the air duct section and the air volume can be accurately evaluated. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 It is a structural schematic diagram of the present application;

[0025] Fig. 2 It is a force condition schematic diagram of a single Magnus roller provided with a displacement measuring mechanism in the embodiment of the present application.

[0026] In the figure, 1 is an air duct section, 2 is a Magnus roller, 3 is an indicating line, 4 is a closed slide, 5 is a compression spring, 6 is a power supply, 7 is a motor, 8 is a roller connecting rod, 9 is an upper connecting block, and 10 is a lower connecting block. DETAILED DESCRIPTION

[0027] In order to make the application more clear and understandable, the application is further described in detail below in combination with the drawings and examples. It should be understood that the examples given are only one of the implementations and do not represent all the examples.

[0028] Example One

[0029] In combination Figs. 1-2 , the embodiment provides a Magnus device for measuring the velocity deviation and air volume of a large-section air duct. The device is horizontally arranged, and the airflow should not appear reverse backflow at the arrangement position. The device is arranged at 3-5 times the equivalent diameter upstream or downstream of the elbow. The conventional air duct section 1 is 3*3, 4*4 or 3*5. The size of the air duct section 1 is taken as an array unit. Multiple array units are arranged at intervals along the length direction of the air duct. The wind speed distribution of each section at any time under different air volumes can be evaluated at any time, improving the accuracy of the original data acquisition and having practicality for studying the air duct flow field distribution.

[0030] The device comprises multiple hollow Magnus rollers 2 arranged in an array along the air duct section 1. The multiple Magnus rollers 2 rotate along the direction perpendicular to the air duct. The Magnus rollers 2 in the same horizontal direction are respectively provided with closed slides 4 above and below. Each Magnus roller 2 is respectively connected with an upper connecting block 9 and a lower connecting block 10 at the top and the bottom. The upper connecting block 9 and the lower connecting block 10 are respectively arranged in the closed slides 4 above and below. A motor 7 is arranged in the lower connecting block 10. The output shaft of the motor 7 is rotationally connected with the Magnus roller 2 through a roller connecting rod 8. The roller connecting rod 8 is arranged in the Magnus roller 2. The end of the roller connecting rod 8 away from the Magnus roller 2 extends out of the Magnus roller 2 and is connected with the output shaft of the motor 7. A displacement measuring mechanism or a pressure measuring mechanism is arranged in the closed slide 4 on one side of the Magnus roller 2. The motor 7 is connected with a power supply 6. The Magnus device provided with the displacement measuring mechanism can measure the velocity deviation of the large-section air duct. The Magnus device provided with the pressure measuring mechanism can measure the air volume of the large-section air duct. The device has no sampling hole, avoiding the risk of pipe blockage of the conventional matrix-type measuring device and other types of measuring devices. It can be used in an air duct or flue with relatively large dust content. The Magnus roller 2 in the embodiment is cylindrical and is designed to be hollow. In order to reduce the self-weight of the roller, the height and diameter of the Magnus roller 2 are reasonably selected according to the size of the air duct.

[0031] Specifically, the displacement measuring mechanism comprises a compression spring 5 and an indicating line 3, the upper connecting block 9 is fixedly connected with the Magnus cylinder 2, the upper and lower connecting blocks 9 and 10 are respectively slidably connected with the upper and lower airtight slides 4, the compression spring 5 is provided with two upper and lower compression springs 5 on the same side, one end of each of the two compression springs 5 is connected with the upper and lower connecting blocks 9 and 10 respectively, and the other end of each of the two compression springs 5 is fixed to the inner wall of the airtight slide 4, the indicating line 3 is provided on the same side of the compression spring 5, one end of the indicating line 3 is fixed to the upper or lower connecting block 9 or 10, the other end of the indicating line 3 extends out of the air duct, and the indicating line 3 is provided with a scale. It should be understood that the indicating line 3 can be arranged on the upper and lower connecting blocks 9 and 10, but as a preferred scheme, Figs. 1-2 The sliding friction coefficients of the airtight slides 4 with the upper and lower connecting blocks 9 and 10 are as small as possible, and the compression spring 5 can be directly welded to the airtight slide 4.

[0032] In the embodiment, when the air duct wind direction is the windward direction relative to the air duct cross section 1, the compression spring 5 and the indicating line 3 are arranged on the left side of the Magnus cylinder 2, and the Magnus cylinder 2 is driven to rotate counterclockwise; when the air duct wind direction is the leeward direction relative to the air duct cross section 1, the compression spring 5 and the indicating line 3 are arranged on the right side of the Magnus cylinder 2, and the Magnus cylinder 2 is driven to rotate clockwise. The above arrangement is mainly to arrange the compression spring 5 and the indicating line 3 in the pressure area, because the indicating line 3 moves outward under the pressure and moves inward under the tension, and moving outward is more conducive to reading the displacement of the indicating line 3.

[0033] As Fig. 2 When the air duct wind direction is inward from the paper, that is, the windward direction relative to the air duct cross section 1, according to the Kutta-Joukowski theorem, a low wind speed and high pressure area is formed on the right side of the Magnus cylinder 2, and a high wind speed and low pressure area is formed on the left side of the Magnus cylinder 2, and the force direction is from right to left. At this time, the Magnus cylinder 2 is pushed to the left to press the compression spring 5, and the indicating line 3 with the scale also changes in displacement.

[0034] In this embodiment, the displacement measuring mechanism can also be replaced by a pressure measuring mechanism. Specifically, the pressure measuring mechanism comprises a pressure sensor, and the upper connecting block 9 and the lower connecting block 10 are fixed to the inner wall of the closed slide 4 away from one end of the Magnus cylinder 2. The upper connecting block 9 is rotationally connected to the Magnus cylinder 2 through a bearing. When the wind direction of the air duct relative to the air duct cross section 1 is the windward direction, the pressure sensor is fixed in any of the upper and lower closed slides 4 close to the left side of the Magnus cylinder 2, and the Magnus cylinder 2 is driven to rotate counterclockwise. When the wind direction of the air duct relative to the air duct cross section 1 is the leeward direction, the pressure sensor is fixed in any of the upper and lower closed slides 4 close to the right side of the Magnus cylinder 2, and the Magnus cylinder 2 is driven to rotate clockwise. The pressure sensor is electrically connected with a controller. The pressure sensor is provided to measure the air volume of the air duct cross section 1. Only the Magnus cylinder 2 needs to rotate in place, and the upper connecting block 9 and the lower connecting block 10 do not need to slide in the closed slide 4. In order to simply realize the rotation of the Magnus cylinder 2 and the upper connecting block 9, a slot can be arranged at the bottom of the upper connecting block 9, and the bearing is fixed in the slot to realize the rotation relationship between the two. The position of the pressure sensor is also based on the setting of the pressure sensor in the pressure area.

[0035] As an optimization, the key materials such as the Magnus cylinder 2 in the device need to be selected according to the temperature of the medium. The high-temperature air duct selects Q345B steel, and the normal-temperature air duct selects Q235 steel or PVC plastic lightweight material.

[0036] Embodiment two

[0037] The embodiment provides a method for measuring the velocity deviation of a large-section air duct based on a Magnus device provided with a displacement measuring mechanism, which comprises the following steps:

[0038] Step A1, a plurality of sections are selected along the length direction of the air duct, and the Magnus device is arranged at each section. The plurality of sections are array units, and the Magnus device for measuring the velocity deviation of the large-section air duct is a device provided with a displacement measuring mechanism.

[0039] Step A2, the displacement measuring mechanism is arranged at the left side or the right side of the Magnus cylinder 2 according to the wind direction in the air duct, and the Magnus cylinder 2 is driven to rotate counterclockwise or clockwise according to the wind direction in the air duct. At this time, the Magnus cylinder 2 is subjected to leftward or rightward pressure, the compression spring 5 is deformed, and the indicating line 3 is displaced. The displacement value of the indicating line 3 is obtained according to the scale change on the indicating line 3, the displacement value of the indicating line 3 represents the sampling point air duct velocity value of the region where the Magnus cylinder 2 is located, and the displacement does not need to be converted into velocity. It should be noted that the position of the displacement measuring mechanism needs to be ensured to be in the pressure area.

[0040] Step A3, the displacement value of the indicator line 3 of all the Magnus roller 2 in the cross section is obtained by step A2, and then the average displacement value of the indicator line 3 is calculated, and the average velocity value of the air duct of the cross section is also represented by the average displacement value of the indicator line 3, and the formula is as follows: Wherein, The average velocity is represented by the average displacement, The velocity of the sampling point is represented by the displacement of the indicator line 3 of the sampling point, and n is the number of sampling points;

[0041] Step A4, the displacement value of the indicator line 3 of the sampling point and the average displacement value of the indicator line 3 of the cross section in step A3 are substituted into the calculation formula The velocity standard deviation is obtained, wherein The average velocity of the cross section is represented by the average displacement of the indicator line 3 of the cross section, The velocity of the sampling point J is represented by the displacement of the indicator line 3 of the sampling point, The velocity standard deviation is obtained, wherein The relative standard deviation rate is obtained, wherein The average velocity of the cross section is represented by the average displacement of the indicator line 3 of the cross section, and CV is the relative standard deviation rate.

[0042] Example three

[0043] The embodiment provides a method for measuring the velocity deviation of a large cross section air duct based on a Magnus device provided with a pressure measuring mechanism, which comprises the following steps:

[0044] Step B1, a plurality of cross sections are selected along the length direction of the air duct, and the Magnus device is arranged at each cross section. The plurality of cross sections are array units, and the Magnus device for measuring the velocity deviation of the large cross section air duct is a device provided with a pressure measuring mechanism.

[0045] Step B2, the pressure sensor is arranged in the closed slide 4 on the left side or the right side of the Magnus roller 2 according to the wind direction in the air duct, and the Magnus roller 2 is driven to rotate counterclockwise or clockwise according to the wind direction in the air duct, so that the Magnus roller 2 is subjected to the pressure from the left or the right. The pressure value of the Magnus roller 2 is obtained through the pressure sensor, the force bearing condition of the Magnus roller 2 is converted into an electrical signal in real time by the pressure sensor and transmitted to the controller. It should be understood that the position of the pressure measuring mechanism needs to be ensured in the pressure bearing area.

[0046] Step B3, the sampling point air duct velocity value of the area where the Magnus roller 2 is located is calculated through the pressure value of the Magnus roller 2. The specific method is as follows: first, the radius of the Magnus roller 2 and the angular velocity of rotation are measured and substituted into the calculation formula The circulation of the Magnus roller 2 is obtained, wherein is the circulation, r is the radius of the Magnus cylinder 2, w is the angular velocity of the rotation of the Magnus cylinder 2; secondly, the pressure value of the Magnus cylinder 2 and the circulation of the Magnus cylinder 2 are substituted into the calculation formula The fluid velocity value of the area where the Magnus cylinder 2 is located is obtained as the sampling point air duct velocity value, wherein p is the fluid density, V is the fluid velocity, is the circulation, L is the pressure.

[0047] Step B4: The sampling point air duct velocity values of all the areas where the Magnus cylinder 2 is located in the cross section are obtained through step B3, and then the average air duct velocity value of the cross section is calculated. The formula is as follows: wherein, is the average velocity, is the sampling point air duct velocity, and n is the number of sampling points.

[0048] Step B5: The average air duct velocity value obtained in step B4 is substituted into the calculation formula Q=VA to obtain the air volume of the air duct cross section 1, wherein Q is the air volume, V is the average air duct velocity, and A is the air duct cross section area.

[0049] The specific embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A Magnus device for measuring velocity deviation and air volume in large cross-section air ducts, said device being arranged horizontally, characterized in that: The device comprises a plurality of hollow Magnus rollers (2) arranged along the cross section (1) of the air duct, the plurality of Magnus rollers (2) rotate along the direction perpendicular to the air duct, the same horizontal direction of the Magnus rollers (2) is respectively provided with airtight slide (4) above and below, the top and bottom of each Magnus roller (2) is respectively connected with upper connecting block (9) and lower connecting block (10), the upper connecting block (9) and the lower connecting block (10) are arranged in the airtight slide (4) above and below respectively, the lower connecting block (10) is provided with motor (7), the output shaft of the motor (7) is connected with the Magnus roller (2) through roller connecting rod (8), the roller connecting rod (8) is arranged in the Magnus roller (2), the end of the roller connecting rod (8) away from the Magnus roller (2) extends out of the Magnus roller (2) and is connected with the output shaft of the motor (7), the airtight slide (4) on one side of the Magnus roller (2) is provided with displacement measuring mechanism or pressure measuring mechanism; The displacement measuring mechanism comprises compression spring (5) and indicating line (3), the upper connecting block (9) is fixedly connected with the Magnus roller (2), the upper connecting block (9) and the lower connecting block (10) are respectively connected with the airtight slide (4) above and below, the compression spring (5) is provided with two on the same side, one end of the two compression springs (5) is respectively connected with the upper connecting block (9) and the lower connecting block (10), the other end of the two compression springs (5) is fixedly connected with the inner wall of the airtight slide (4), the indicating line (3) is arranged on the same side of the compression spring (5), one end of the indicating line (3) is fixedly connected with the upper connecting block (9) or the lower connecting block (10), the other end of the indicating line (3) extends out of the air duct, the indicating line (3) is provided with scale; when the wind direction of the air duct is relative to the wind direction of the cross section (1) of the air duct, the compression spring (5) and the indicating line (3) are arranged on the left side of the Magnus roller (2), the Magnus roller (2) is driven to rotate counterclockwise; when the wind direction of the air duct is relative to the wind direction of the cross section (1) of the air duct, the compression spring (5) and the indicating line (3) are arranged on the right side of the Magnus roller (2), the Magnus roller (2) is driven to rotate clockwise; The pressure measuring mechanism comprises a pressure sensor, the upper connecting block (9) and the lower connecting block (10) are fixed to the inner wall of the closed slide (4) at the end away from the Magnus roller (2), and the upper connecting block (9) is rotationally connected to the Magnus roller (2) through a bearing; when the air duct wind direction is relative to the air duct section (1) in the windward direction, the pressure sensor is fixed in any of the upper and lower closed slides (4) close to the left side of the Magnus roller (2), and the Magnus roller (2) is driven to rotate counterclockwise; when the air duct wind direction is relative to the air duct section (1) in the leeward direction, the pressure sensor is fixed in any of the upper and lower closed slides (4) close to the right side of the Magnus roller (2), and the Magnus roller (2) is driven to rotate clockwise; the pressure sensor is electrically connected with a controller.

2. The Magnus device for measuring velocity skewness and volume of large cross section ducts as claimed in claim 1 wherein: The motor (7) is connected with a power supply (6), and the device is arranged at 3-5 times equivalent diameter upstream or downstream of the elbow.

3. The Magnus device for measuring velocity skewness and volume of large cross section ducts as claimed in claim 1 wherein: When the air duct is a high-temperature air duct, the device selects Q345B steel, and when the air duct is a normal-temperature air duct, the device selects Q235 steel or PVC plastic lightweight material.

4. A method of measuring velocity profile in a large cross-section duct using the Magnus device of claim 1 for measuring velocity profile and air volume in a large cross-section duct, characterized by, The method comprises the following steps: Step A1, a plurality of sections are selected along the length direction of the air duct, and the Magnus device is arranged at each section; Step A2, a displacement measuring mechanism is arranged at the left side or the right side of the Magnus roller (2) according to the wind direction in the air duct, and the Magnus roller (2) is driven to rotate counterclockwise or clockwise according to the wind direction in the air duct, at this time, the Magnus roller (2) is subjected to leftward or rightward pressure, the compression spring (5) is deformed, and the indicating line (3) is displaced, the displacement value of the indicating line (3) is obtained according to the scale change on the indicating line (3), and the displacement value of the indicating line (3) represents the sampling point air duct velocity value of the region where the Magnus roller (2) is located; Step A3, the displacement values of the indicating lines (3) of all the Magnus rollers (2) at the section are obtained through step A2, and then the average displacement value of the indicating lines (3) is calculated, and the average displacement value of the indicating lines (3) represents the average velocity value of the air duct at the section; Step A4, the sampled point indicating line (3) displacement value in step A3 and the indicating line (3) average displacement value of the section are substituted into the calculation formula The velocity standard deviation is obtained, wherein The indicating line (3) average displacement of the section represents the air duct average velocity of the section, The indicating line (3) displacement of the sampled point represents the velocity of the sampled point J, The velocity standard deviation is obtained, wherein n is the number of partitions; the calculation formula is The relative standard deviation rate is obtained, wherein The air duct average velocity of the section; and the CV is the relative standard deviation rate.

5. A method of measuring the volume of air in a large cross-section air duct using the Magnus device of claim 1 for measuring velocity bias and volume of air in a large cross-section air duct, characterized by, The method comprises the following steps: Step B1, a plurality of sections are selected along the length direction of the air duct, and the Magnus device is arranged at each section; Step B2, a pressure sensor is arranged in the closed slide (4) at the left side or the right side of the Magnus roller (2) according to the wind direction in the air duct, and the Magnus roller (2) is driven to rotate counterclockwise or clockwise according to the wind direction in the air duct, at this time, the Magnus roller (2) is subjected to leftward or rightward pressure, the pressure value of the Magnus roller (2) is obtained through the pressure sensor, and the force bearing condition of the Magnus roller (2) is converted into an electric signal in real time and transmitted to the controller by the pressure sensor; Step B3, the sampling point air duct velocity value of the region where the Magnus roller (2) is located is calculated through the pressure value of the Magnus roller (2). Step B4, obtain the sampling point duct velocity value of the area where all the Magnus roller (2) of the cross section is located by step B3, and then calculate the average duct velocity value of the cross section; Step B5, substitute the average duct velocity value obtained in step B4 into the calculation formula Q=VA to obtain the air volume of the duct cross section (1), wherein Q is the air volume, V is the average duct velocity, and A is the area of the duct cross section (1).

6. The method of claim 5, wherein, In step B3, the method for calculating the fluid velocity value of the area where the Magnus roller (2) is located by the pressure value of the Magnus roller (2) is as follows: first, the radius of the Magnus roller (2) and the angular velocity of rotation are measured and substituted into the calculation formula The circulation of the Magnus roller (2) is obtained, wherein is the circulation, r is the radius of the Magnus roller (2), and w is the angular velocity of rotation of the Magnus roller (2); secondly, the pressure value of the Magnus roller (2) and the circulation of the Magnus roller (2) are substituted into the calculation formula The fluid velocity value of the area where the Magnus roller (2) is located is obtained as the sampling point air duct velocity value, wherein p is the fluid density, V is the fluid velocity, and L is the pressure.

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