An ultrasonic wind speed detection method based on ultrasonic anemometer

Abstract

The present invention relates to the technical field of wind speed measurement, and in particular to an ultrasonic wind speed detection method based on an ultrasonic anemometer. The method comprises: determining the Reynolds number of a target pipeline; if the Reynolds number is greater than 2000, adding at least one intermediate partition parallel to the target pipeline's axis, the intermediate partition dividing the target pipeline into multiple sub-pipelines so that the gas inside all sub-pipelines is laminar, and marking each sub-pipeline as a test pipeline; if the Reynolds number is less than 2000, the target pipeline is used as a test pipeline; a pair of ultrasonic anemometers are installed in the test pipeline to measure the wind speed of the test pipeline, and the wind speed of the target pipeline is determined based on the wind speed of the test pipeline; the sound wave transmitting end and receiving end of one ultrasonic anemometer are both oriented toward the sound wave transmitting end and receiving end of the other ultrasonic anemometer, and the connecting line of the two ultrasonic anemometers passes through the geometric center of the test pipeline in which they are located. The present invention can continuously and accurately measure underground wind speed.

Description

Technical Field

[0001] The present invention relates to the technical field of wind speed testing, and in particular to an ultrasonic wind speed detection method based on an ultrasonic anemometer. Background Art

[0002] At present, the mining of mineral resources mainly includes open-pit mining and underground mining. During underground mining, since the workplace is located underground and personnel work underground, it is necessary to ensure that fresh air continuously enters the underground. The harmful gases such as gas generated during underground mining need to be extracted underground, which requires the establishment of an exhaust system underground.

[0003] To ensure safe production underground, the exhaust system's exhaust volume must be guaranteed, requiring real-time monitoring of the exhaust volume. Monitoring of underground exhaust volume often relies on wind speed monitoring. However, the underground and exhaust system environments are relatively harsh. Currently, wind speed is measured manually at the exhaust system pipe opening using a handheld anemometer, but this method struggles to provide continuous and accurate wind speed measurements. Summary of the Invention

[0004] The embodiment of the present invention provides an ultrasonic wind speed detection method based on an ultrasonic anemometer, which can efficiently and safely monitor wind speed continuously and accurately. The technical solution of the present invention is as follows:

[0005] An ultrasonic wind speed detection method based on an ultrasonic anemometer, comprising:

[0006] Determine the Reynolds number of the target pipeline based on the diameter of the target pipeline, the preset maximum exhaust flow rate, the gas dynamic viscosity and the gas density;

[0007] Determine whether the Reynolds number of the target pipeline is greater than 2000; if the Reynolds number of the target pipeline is greater than 2000, then add at least one intermediate partition in the target pipeline in a direction parallel to its axis, wherein the intermediate partition divides the target pipeline into multiple sub-pipelines so that the gas inside all the sub-pipelines is laminar flow, and mark each sub-pipeline as a test pipeline; if the Reynolds number of the target pipeline is less than 2000, then directly use the target pipeline as a test pipeline;

[0008] A pair of ultrasonic anemometers are installed in the test pipe to measure the wind speed of the test pipe and determine the wind speed of the target pipe based on the wind speed of the test pipe; wherein the sound wave transmitting end and the sound wave receiving end of one ultrasonic anemometer are both oriented towards the sound wave transmitting end and the sound wave receiving end of the other ultrasonic anemometer, and the connecting line of the two ultrasonic anemometers passes through the geometric center of the test pipe in which they are located.

[0009] Optionally, measuring the wind speed of the test duct includes:

[0010] Using a pair of ultrasonic anemometers installed on the test pipe to collect linear wind speed data of the straight line where the two ultrasonic anemometers are connected;

[0011] The average cross-sectional wind speed of the test pipe is determined according to the linear wind speed data and the cross-sectional wind speed model, and the average cross-sectional wind speed of the test pipe is used as the wind speed of the test pipe, wherein the cross-sectional area of ​​the test pipe is a cross-sectional area perpendicular to its axis.

[0012] Optionally, determining the cross-sectional average wind speed of the test pipeline according to the linear wind speed data and the cross-sectional wind speed model includes:

[0013] The average wind speed of the test pipe is determined based on the angle between the direction of the linear wind speed data and the axis direction of the test pipe, combined with the value of the linear wind speed data, and the cross-sectional average wind speed is determined based on the average wind speed.

[0014] Optionally, the test pipe is a rectangular pipe, and the two ultrasonic anemometers are respectively installed on the two pipe walls with the smallest area of ​​the test pipe, and are respectively installed on the center lines of the two pipe walls.

[0015] Optionally, the average wind speed v path Determined by the following formula:

[0016] v path =v 0 / cosθ ;

[0017] in, i is the angle between the direction of the linear wind speed data and the axis direction of the test pipe, v 0 is the value of the linear wind speed data, v path is the average wind speed, v ( x , y ) represents the wind speed at the coordinate (x, y).

[0018] Optionally, determining the cross-sectional average wind speed according to the average wind speed includes:

[0019] Establish a double parabolic cross-section wind speed model for the test duct;

[0020] Integrating the cross-sectional wind speed model and obtaining a cross-sectional average wind speed expression according to the cross-sectional area of ​​the test pipe;

[0021] Using symmetry to simplify the integration of the cross-sectional average wind speed expression, a first expression for the relationship between the cross-sectional average wind speed and the wind speed at the center of the test pipe is obtained;

[0022] Establish a linear wind speed model of the test duct including the average wind speed and the wind speed at the center of the test duct;

[0023] Integrating the linear wind speed model to obtain a second expression for the relationship between the average wind speed and the wind speed at the center of the test duct;

[0024] The relationship between the cross-sectional average wind speed and the average wind speed is determined according to the first expression and the second expression, and the cross-sectional average wind speed is determined according to the average wind speed.

[0025] Optionally, the cross-sectional wind speed model is:

[0026] ;

[0027] in, v max To test the wind speed in the center of the duct, the long side of the rectangular duct is 2 a , the wide side is 2 b , the center point of the cross section is the origin of coordinates, x and y Respectively represent the abscissa and ordinate of a point on the test pipe cross section;

[0028] The expression of the average wind speed of the cross section is:

[0029] ;

[0030] in, is the average wind speed of the cross section;

[0031] The first expression is:

[0032] .

[0033] Optionally, the linear wind speed model is expressed as:

[0034] ;

[0035] The second expression is:

[0036] .

[0037] Optionally, the Reynolds number is determined by the following expression:

[0038] Re=ρvd / m ;

[0039] in, Re is the Reynolds number, d is the equivalent pipe diameter, v is the preset maximum exhaust flow rate, mis the gas dynamic viscosity, r is the gas density, equivalent pipe diameter d =4 ab / ( a + b ), the long side and wide side of the target pipe section are 2 a and 2 b .

[0040] Optionally, the middle partition is made of polytetrafluoroethylene.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] In this embodiment, the Reynolds number of the target pipe is first determined. If the Reynolds number of the target pipe is no more than 2000, the airflow in the target pipe is laminar, and the wind speed can be directly measured using an ultrasonic anemometer. If the Reynolds number of the target pipe is greater than 2000, the airflow in the target pipe is turbulent, and the distribution and scale of the turbulence cannot be determined. When using an ultrasonic anemometer to measure the wind speed in turbulent flow, a certain error will occur, resulting in inaccurate measured results. Therefore, for a target pipe with a Reynolds number greater than 2000, a middle partition parallel to its axis is set, which will not significantly hinder the flow of air. The diameter of the multiple sub-pipes separated by the middle partition is reduced without significantly changing the gas flow rate, reducing the Reynolds number to 2000 or below, making the airflow in the sub-pipes laminar, and measuring the wind speed of the laminar flow in the sub-pipes, and finally obtaining a more accurate pipe wind speed. In summary, the present invention can continuously and accurately measure the wind speed in coal mines and can efficiently and safely monitor the wind speed in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 Schematic diagram of an ultrasonic anemometer installed on a test pipe provided by an embodiment of the present invention.

[0045] In the picture:

[0046] 1- Test pipeline;

[0047] 2- Ultrasonic anemometer. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0049] like Figure 1 As shown, an embodiment of the present invention provides an ultrasonic wind speed detection method based on an ultrasonic anemometer, comprising:

[0050] Determine the Reynolds number of the target pipeline based on the diameter of the target pipeline, the preset maximum exhaust flow rate, the gas dynamic viscosity and the gas density;

[0051] Determine whether the Reynolds number of the target pipeline is greater than 2000; if the Reynolds number of the target pipeline is greater than 2000, then add at least one intermediate partition in the target pipeline in a direction parallel to its axis, wherein the intermediate partition divides the target pipeline into multiple sub-pipelines so that the gas inside all the sub-pipelines is laminar flow, and mark each sub-pipeline as a test pipeline; if the Reynolds number of the target pipeline is less than 2000, then directly use the target pipeline as a test pipeline;

[0052] A pair of ultrasonic anemometers are installed in the test pipe to measure the wind speed of the test pipe and determine the wind speed of the target pipe based on the wind speed of the test pipe; wherein the sound wave transmitting end and the sound wave receiving end of one ultrasonic anemometer are both oriented towards the sound wave transmitting end and the sound wave receiving end of the other ultrasonic anemometer, and the connecting line of the two ultrasonic anemometers passes through the geometric center of the test pipe in which they are located.

[0053] In this embodiment, the target pipe refers to a pre-deployed pipe in the coal mine's underground exhaust system for testing wind speed. First, based on the underground exhaust demand and the diameter of the target pipe, the Reynolds number of the target pipe is determined when the air volume in the target pipe is at its maximum. If the Reynolds number of the target pipe is no greater than 2000, the airflow within the target pipe is laminar, and wind speed can be measured directly using an ultrasonic anemometer. If the Reynolds number of the target pipe is greater than 2000, the airflow within the target pipe is turbulent, and the distribution and scale of the turbulence cannot be determined. When using an ultrasonic anemometer to measure wind speed in turbulent flow, certain errors will occur, resulting in inaccurate results. Therefore, for target pipes with a Reynolds number greater than 2000, a central partition is installed in the portion or all of the pipe used for wind speed measurement. The central partition is parallel to the axis of the target pipe and does not significantly obstruct the airflow. This allows the diameters of the multiple sub-pipes separated by the central partition to be reduced without significantly changing the gas flow rate, thereby reducing the Reynolds number to 2000 or below. The target pipe with a high Reynolds number is reduced to a sub-pipe with a low Reynolds number through the middle partition, so that the airflow in the sub-pipe is laminar. The wind speed of the laminar flow in the sub-pipe is measured, and finally a more accurate pipe wind speed is obtained.

[0054] In this embodiment, each test duct is laminar flow. After the wind speed of each test duct is obtained through testing, the flow rate per unit time of the target duct can be known. Specifically: when the target duct is a test duct without an intermediate partition, the wind speed of one test duct is the wind speed of the target duct, and the flow rate per unit time of the target duct can be obtained by combining the cross-sectional area of ​​the duct; when the target duct is a plurality of test ducts separated by at least one intermediate partition, the wind speeds of the plurality of test ducts together become the wind speed of the target duct. When calculating the flow rate of the target duct, the wind speed and cross-sectional area of ​​each test duct are multiplied to obtain the flow rate per unit time of each test duct, and then all the flow rates per unit time are summed to obtain the flow rate per unit time of the target duct, that is, the flow rate per unit time of the target duct in the exhaust system.

[0055] It should be noted that the number of the intermediate partitions may be one or more, and the target pipeline generating turbulent flow is divided based on the standard of isolating the laminar flow.

[0056] In some embodiments of the present invention, measuring the wind speed of the test duct includes:

[0057] Using a pair of ultrasonic anemometers installed on the test pipe to collect linear wind speed data of the straight line where the two ultrasonic anemometers are connected;

[0058] The average cross-sectional wind speed of the test pipe is determined according to the linear wind speed data and the cross-sectional wind speed model, and the average cross-sectional wind speed of the test pipe is used as the wind speed of the test pipe, wherein the cross-sectional area of ​​the test pipe is a cross-sectional area perpendicular to its axis.

[0059] In this embodiment, a pair of ultrasonic anemometers can be used to measure the linear wind speed data of the line connecting the two. According to the linear wind speed data and the cross-sectional wind speed model, a more accurate and comprehensive cross-sectional average wind speed can be obtained.

[0060] In this embodiment, since the gas in the test pipe is laminar flow, the wind speed distribution of the laminar flow conforms to the parabolic law. The laminar flow with a certain wind speed distribution law can obtain relatively accurate wind speed data through data processing.

[0061] In some embodiments of the present invention, determining the cross-sectional average wind speed of the test pipeline according to the linear wind speed data and the cross-sectional wind speed model includes:

[0062] The average wind speed of the test pipe is determined based on the angle between the direction of the linear wind speed data and the axis direction of the test pipe, combined with the value of the linear wind speed data, and the cross-sectional average wind speed is determined based on the average wind speed.

[0063] In this embodiment, the linear wind speed data is the average wind speed along the line where the pair of ultrasonic anemometers are located. The wind direction within the test duct is along the duct's axis. Therefore, the measured linear wind speed data is the component of the average wind speed along the duct's axis in the measurement direction. The average wind speed in the test duct can be calculated based on the angle between the measurement direction (the direction of the line where the pair of ultrasonic anemometers are located) and the duct's axis and the measured linear wind speed data.

[0064] It should be noted that, compared with the existing method of measuring two wind speeds by two pairs of ultrasonic anemometers in orthogonal directions, which synthesizes the average wind speed in the axial direction of the pipeline based on the wind speeds of two orthogonal lines, the embodiment of the present invention makes the airflow in the test pipeline laminar, and determines the direction of the airflow as a known condition, which is consistent with the axial direction of the test pipeline. Therefore, a pair of ultrasonic anemometers can obtain the average wind speed along the axis of the test pipeline.

[0065] In some embodiments of the present invention, the test pipe is a rectangular pipe, and the two ultrasonic anemometers are respectively installed on the two pipe walls with the smallest area of ​​the test pipe and are respectively installed on the center lines of the two pipe walls.

[0066] The line connecting the two ultrasonic anemometers is the direction of the measured linear wind speed data. The straight line in this direction falls on a parabolic wind speed distribution surface (the surface that bisects the test pipe). The wind speed distribution on each straight line perpendicular to the pipe wall on this surface is parabolic, so that the linear wind speed data measured by the ultrasonic anemometer is located on the plane with symmetry of the wind speed, and the measured results are more accurate.

[0067] It should be noted that the direction of laminar flow velocity is the axis of the test duct. However, since ultrasonic anemometers must be fixed to the inner wall of the duct or intermediate partition, if two ultrasonic anemometers are installed on the same inner wall, the measured data is the linear velocity close to the inner wall. Although it is laminar flow, the wind speed at different cross-sections will still vary, making the data measured close to the inner wall less accurate. In addition, if the distance from the inner wall of the test duct is too close, the test duct will generate reflected waves that interfere with the test data.

[0068] In some embodiments of the present invention, the average wind speed v path Determined by the following formula:

[0069] v path =v 0 / cosθ ;

[0070] in, i is the angle between the direction of the linear wind speed data and the axis direction of the test pipe, v 0 is the value of the linear wind speed data, v path is the average wind speed, v ( x , y ) represents the wind speed at the coordinate (x, y).

[0071] In some embodiments of the present invention, determining the cross-sectional average wind speed according to the average wind speed includes:

[0072] Establish a double parabolic cross-section wind speed model for the test duct;

[0073] Integrating the cross-sectional wind speed model and obtaining a cross-sectional average wind speed expression according to the cross-sectional area of ​​the test pipe;

[0074] Using symmetry to simplify the integration of the cross-sectional average wind speed expression, a first expression for the relationship between the cross-sectional average wind speed and the wind speed at the center of the test pipe is obtained;

[0075] Establish a linear wind speed model of the test duct including the average wind speed and the wind speed at the center of the test duct;

[0076] Integrating the linear wind speed model to obtain a second expression for the relationship between the average wind speed and the wind speed at the center of the test duct;

[0077] The relationship between the cross-sectional average wind speed and the average wind speed is determined according to the first expression and the second expression, and the cross-sectional average wind speed is determined according to the average wind speed.

[0078] In this embodiment, the average wind speed is obtained based on the linear wind speed, and the data source is the linear wind speed data. However, the calculation of the air volume needs to rely on the cross-sectional average wind speed. The average wind speed determined by trigonometric functions from the linear wind speed data does not take into account the cross-sectional scale. Therefore, its data accuracy needs to be further improved. Specifically, a double parabola cross-sectional wind speed model of the test duct is first established so that every point on the cross section can be represented by this model. The cross-sectional wind speed model is integrated to obtain the sum of the wind speeds at all points on the cross section, and then divided by the cross-sectional area to obtain the cross-sectional average wind speed expression. The parabola has symmetry, and the cross-sectional average wind speed expression is symmetrically simplified and integrated, ultimately obtaining the relationship between the maximum wind speed at the center of the cross section (center wind speed) and the cross-sectional average wind speed, i.e., the first expression. A linear wind speed model of the test duct is established. The linear wind speed model is the wind speed model of the line where the cross-sectional bisector lies. The cross-sectional bisector and the line where the direction of the linear wind speed data lies are located in the same plane. After integrating the linear wind speed model, a second expression representing the relationship between the average wind speed of the linear wind speed and the central wind speed is obtained. The second expression relates the average wind speed representing the linear wind speed to the cross-sectional average wind speed representing the surface wind speed, and finally, the cross-sectional average wind speed is obtained.

[0079] In some embodiments of the present invention, the cross-sectional wind speed model is:

[0080] ;

[0081] in, v max To test the wind speed in the center of the duct, the long side of the rectangular duct is 2 a , the wide side is 2 b , the center point of the cross section is the coordinate origin, x and y represent the horizontal and vertical coordinates of the point on the test pipe cross section respectively;

[0082] The expression of the cross-sectional average wind speed is:

[0083] ;

[0084] in, is the average wind speed of the cross section;

[0085] The first expression is:

[0086] .

[0087] In some embodiments of the present invention, the linear wind speed model is expressed as:

[0088] ;

[0089] The second expression is:

[0090] .

[0091] In some embodiments of the present invention, the Reynolds number is determined by the following expression:

[0092] Re=ρvd / m ;

[0093] in, Re is the Reynolds number, d is the equivalent pipe diameter, v is the preset maximum exhaust flow rate, m is the gas dynamic viscosity, r is the gas density, equivalent pipe diameter d =4 ab / ( a + b ), the long side and wide side of the target pipe section are 2 a and 2 b .

[0094] In this embodiment, since the target pipe is a rectangular pipe, the equivalent pipe diameter is not the diameter of the circular pipe, but is obtained from the side length.

[0095] In some embodiments of the present invention, the intermediate partition is made of polytetrafluoroethylene.

[0096] In this embodiment, the provision of the middle partition will generate a certain amount of friction on the airflow, thereby reducing the total velocity of the airflow. Therefore, in order to minimize the impact of the middle partition on the total flow velocity, polytetrafluoroethylene material with very low friction is selected to make the middle partition.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An ultrasonic wind speed detection method based on an ultrasonic anemometer, characterized in that: include: Determine the Reynolds number of the target pipeline based on the diameter of the target pipeline, the preset maximum exhaust flow rate, the gas dynamic viscosity and the gas density; Determine whether the Reynolds number of the target pipeline is greater than 2000; if the Reynolds number of the target pipeline is greater than 2000, then add at least one intermediate partition in the target pipeline in a direction parallel to its axis, wherein the intermediate partition divides the target pipeline into multiple sub-pipelines so that the gas inside all the sub-pipelines is laminar flow, and mark each sub-pipeline as a test pipeline; if the Reynolds number of the target pipeline is less than 2000, then directly use the target pipeline as a test pipeline; A pair of ultrasonic anemometers are installed in the test duct to measure the wind speed in the test duct and determine the wind speed of the target duct based on the wind speed in the test duct; wherein the sound wave transmitting end and the sound wave receiving end of one ultrasonic anemometer are both oriented toward the sound wave transmitting end and the sound wave receiving end of the other ultrasonic anemometer, and the connecting line of the two ultrasonic anemometers passes through the geometric center of the test duct in which they are located; The measuring of the wind speed of the test duct comprises: Using a pair of ultrasonic anemometers installed on the test pipe to collect linear wind speed data of the straight line where the two ultrasonic anemometers are connected; Determine the average cross-sectional wind speed of the test duct according to the linear wind speed data and the cross-sectional wind speed model, and use the average cross-sectional wind speed of the test duct as the wind speed of the test duct, wherein the cross-sectional wind speed of the test duct is a cross-sectional wind speed perpendicular to the axis of the test duct; Determining the average cross-sectional wind speed of the test pipeline according to the linear wind speed data and the cross-sectional wind speed model includes: Determine the average wind speed of the test pipe based on the angle between the direction of the linear wind speed data and the axis direction of the test pipe, combined with the value of the linear wind speed data, and determine the cross-sectional average wind speed based on the average wind speed; Determining the cross-sectional average wind speed according to the average wind speed includes: Establish a double parabolic cross-section wind speed model for the test duct; Integrating the cross-sectional wind speed model and obtaining a cross-sectional average wind speed expression according to the cross-sectional area of ​​the test pipe; Using symmetry to simplify the integration of the cross-sectional average wind speed expression, a first expression for the relationship between the cross-sectional average wind speed and the wind speed at the center of the test pipe is obtained; Establish a linear wind speed model of the test duct including the average wind speed and the wind speed at the center of the test duct; Integrating the linear wind speed model to obtain a second expression for the relationship between the average wind speed and the wind speed at the center of the test duct; The relationship between the cross-sectional average wind speed and the average wind speed is determined according to the first expression and the second expression, and the cross-sectional average wind speed is determined according to the average wind speed.

2. The ultrasonic wind speed detection method based on an ultrasonic anemometer according to claim 1, characterized in that: The test pipe is a rectangular pipe, and the two ultrasonic anemometers are respectively installed on the two pipe walls with the smallest area of ​​the test pipe and are respectively installed on the center lines of the two pipe walls.

3. The ultrasonic wind speed detection method based on an ultrasonic anemometer according to claim 1, characterized in that: The average wind speed v path Determined by the following formula: ； in, θ is the angle between the direction of the linear wind speed data and the axis direction of the test pipe, v 0 is the value of the linear wind speed data, v path is the average wind speed.

4. The ultrasonic wind speed detection method based on an ultrasonic anemometer according to claim 1, characterized in that: The cross-sectional wind speed model is: ； in, v max To test the wind speed in the center of the duct, the long side of the rectangular duct is 2 a , the wide side is 2 b , the center point of the cross section is the coordinate origin, x and y Respectively represent the horizontal and vertical coordinates of the points on the test pipe section, v ( x , y ) represents the wind speed at the coordinate (x, y); The expression of the average wind speed of the cross section is: ； in, is the average wind speed of the cross section; The first expression is: 。 5. The ultrasonic wind speed detection method based on an ultrasonic anemometer according to claim 4, characterized in that: The expression of the linear wind speed model is: ； The second expression is: 。 6. The ultrasonic wind speed detection method based on an ultrasonic anemometer according to claim 1, characterized in that: The Reynolds number is determined by the following expression: ； in, Re is the Reynolds number, d is the equivalent pipe diameter, v is the preset maximum exhaust flow rate, μ is the gas dynamic viscosity, ρ is the gas density, equivalent pipe diameter d =4 ab / ( a + b ), the long side and wide side of the target pipe section are 2 a and 2 b .

7. The ultrasonic wind speed detection method based on an ultrasonic anemometer according to claim 1, characterized in that: The middle partition is made of polytetrafluoroethylene.

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