Dynamic turbulence measuring method

Abstract

The invention discloses a dynamic turbulence measurement method. A hot-wire anemometer with two hot-wire probes is adopted to measure the wind speed of two points in a space; then setting the sampling frequency fc of the hot-wire anemometer, and counting the average time ts and the space length r; obtaining voltage data output by the hot-wire anemometer, judging whether the voltage data is normal or not, and removing abnormal data; corrected correction voltage data is obtained; calculating the wind speed u according to the corrected voltage data; determining a time interval td according to a preset sampling frequency fc, calculating a speed structure constant # imgabs0 # by combining the wind speeds measured by the two hot-wire probes, and calculating second-order and third-order turbulence dissipation rates; and calculating the kinematic viscosity coefficient v2 at the in-situ measurement position, the internal scale 10 of the atmospheric turbulence and the turbulence I in sequence. The dynamic turbulence measuring method overcomes the defects that a temperature pulsation instrument cannot measure dynamic turbulence and an ultrasonic anemometer platform is poor in applicability, and has the advantages of being easy and convenient to operate, suitable for being carried on a sounding balloon for high-altitude turbulence measurement in a severe environment and the like.

Description

Technical Field

[0001] The invention relates to an atmospheric optical measurement technology, in particular to a dynamic turbulence measurement method. Background Art

[0002] Atmospheric turbulence is an important form of motion in the atmosphere. Its existence significantly enhances the vertical and horizontal exchange of momentum, heat, water vapor and pollutants in the atmosphere, which is much greater than the exchange intensity of molecular motion. Atmospheric turbulence is mainly caused by the random movement of the atmosphere caused by solar radiation and various meteorological factors. The fluctuations in the atmospheric wind field caused by it will have an important impact on the atmospheric boundary layer process, the transmission and diffusion of pollutants, and the atmospheric propagation of light waves. At the same time, the turbulence caused by horizontal wind shear in the high altitude is an important factor causing high-altitude flight turbulence, and the vertical shear of the near-ground wind plays an important role in causing low-altitude flight turbulence during aircraft takeoff and landing. The existence of atmospheric turbulence also has a certain interference effect on the propagation of light waves, sound waves and electromagnetic waves in the atmosphere. Due to limited observation methods, there is a lack of research and understanding on the fluctuation characteristics of atmospheric wind fields, especially high-altitude atmospheric wind fields. Direct measurement of dynamic turbulence is of great significance to the study of atmospheric turbulence.

[0003] Atmospheric turbulence is generally divided into two categories: dynamic turbulence and thermal turbulence. The intensity of atmospheric thermal turbulence is usually measured by a temperature pulsator. The turbulence it measures is caused by thermal convection, and it cannot measure the dynamic turbulence caused by wind field changes. Ultrasonic anemometers are often used to measure dynamic turbulence. Ultrasonic anemometers use the relationship between sound speed and temperature and humidity. By measuring the transmission time of ultrasonic pulses at a certain distance on three non-orthogonal axes, the three components of wind speed and ultrasonic virtual temperature are obtained through coordinate transformation. However, there are two problems with ultrasonic anemometers in measuring dynamic turbulence: (1) Ultrasonic anemometers measure time series data of single-point sound wind speed in space, while the Taylor assumption is required to solve the dynamic turbulence parameters in space; (2) Due to weight and power consumption limitations, ultrasonic anemometers are usually suitable for ground-based measurements and are difficult to carry on platforms such as drones and soundings for high-altitude turbulence measurements.

[0004] Hot wire anemometers are often used to measure fluid flow rate. Hot wire anemometers play an indispensable role in turbulent pulsation measurement due to their advantages such as high dynamic response, high precision, small interference to the flow field and portability. Hot wire anemometers keep the temperature of the hot wire resistor in the flow field constant. When the wind speed changes, the current flowing through the hot wire resistor changes, thereby causing the voltage at both ends to change. The wind speed data of the current flow field is obtained through the relationship between the voltage signal and the wind speed. In the prior art, the measurement data of conventional hot wire anemometers are spatial single-point acoustic wind speed time series data, and the dynamic turbulence parameters in space need to be calculated using the Taylor assumption. At the same time, conventional hot wire anemometers are mostly used for fixed platform measurements in turbulence measurements. The moving platform is disturbed by platform jitter and rotation, which causes measurement errors in turbulence measurements; conventional hot wire anemometers are usually tested and calibrated in flow fields at room temperature, but large errors will occur under non-calibration conditions such as high temperature and high pressure. Summary of the invention

[0005] The present invention is to avoid the deficiencies existing in the above-mentioned prior art and provide a dynamic turbulence measurement method and a computer program product to solve the problems that the existing temperature pulsation meter principle cannot measure dynamic turbulence, the wind speed data measured by ultrasonic anemometers and conventional hot-wire anemometers cannot directly obtain turbulence parameters related to dynamic turbulence, and the platform applicability of ultrasonic anemometers and conventional hot-wire anemometers is poor.

[0006] The present invention adopts the following technical solutions to solve the technical problems.

[0007] A dynamic turbulence measurement method of the present invention mainly comprises the following steps:

[0008] Step 1: Use a hot wire anemometer with two hot wire probes to measure the wind speed at two points in the space;

[0009] Step 2: After arranging the hot wire anemometer, set the sampling frequency fc, statistical average time ts and spatial length r of the hot wire anemometer;

[0010] Step 3: Obtain the voltage data output by the hot wire anemometer, and determine whether the voltage data is normal based on the identifier Bs, and remove abnormal data;

[0011] Step 4: Correct the voltage data obtained after removing the abnormal data to obtain corrected voltage data;

[0012] Step 5: Calculate the wind speed u based on the corrected voltage data;

[0013] Step 6: Determine the time interval td according to the preset sampling frequency fc, and combine the first wind speed measured by the two hot wire probes and the second wind speed Calculate velocity structure constants

[0014] Step 7: Calculate the second-order turbulence dissipation rate ε 2 and the third-order turbulence dissipation rate ε 3 ;

[0015] Step 8: Calculate the kinematic viscosity coefficient v at the in-situ measurement 2 ;

[0016] Step 9: Calculate the inner scale l of atmospheric turbulence 0 ;

[0017] Step 10: Calculate the turbulence intensity I.

[0018] A method for measuring dynamic turbulence of the present invention is also characterized in that:

[0019] Furthermore, in step 4, the voltage data obtained after removing the abnormal data is corrected using the following formula (1);

[0020]

[0021] In formula (1), E 1 is the output voltage of the hot wire anemometer in the calibration state, E 2 is the output voltage of the hot wire anemometer at the in-situ measurement point; ξ is the correction coefficient, which is related to the velocity, pressure and Reynolds number of the air flow; n is a parameter related to the Reynolds number at the in-situ measurement point, and m is a parameter related to the Reynolds number at the calibration state; v 1 is the kinematic viscosity coefficient of the atmosphere under calibration conditions; T w is the working temperature of the hot wire of the hot wire anemometer; T 1 is the temperature of the hot wire under calibration conditions; T 2 is the temperature of the hot wire at the in-situ measurement point; P 1 T is the atmospheric pressure at the location of the hot wire anemometer during calibration; 2 is the atmospheric pressure at the in-situ measurement location.

[0022] Furthermore, in step 5, the following formula (2) is used to calculate the wind speed u according to the corrected voltage data;

[0023]

[0024] In formula (2), E is the output voltage value of the hot wire anemometer, u is the wind speed corresponding to the output voltage value E, and I w is the hot wire working current corresponding to the output voltage value E, R w is the hot wire working resistance corresponding to the output voltage value E, R fis the constant temperature resistance of the hot wire at room temperature, and A and B are constants related to the length of the hot wire and the physical properties of the fluid.

[0025] Furthermore, in step 6, the velocity structure constant is calculated using the following formula (3):

[0026]

[0027] In formula (3), D uu (r) represents a vector The second-order structure function of the measured space is: r is the distance between two points in the measured space; C is a dimensionless constant, usually 2; ε 2 is the second-order turbulence dissipation rate of the atmosphere, indicating that the turbulence dissipation rate is obtained through the second-order structure function Calculated; <> indicates statistical average.

[0028] Furthermore, in step 7, the second-order turbulence dissipation rate ε is calculated using the following formula (4): 2 ;

[0029]

[0030] In formula (4), C is a dimensionless constant, usually 2; is the velocity structure constant of wind speed.

[0031] Furthermore, in step 7, the third-order turbulence dissipation rate ε is calculated using the following formula (5): 3 ;

[0032]

[0033] In the above formula (5), Representation vector The third-order structure function of , r is the distance between two points in the measured space.

[0034] Furthermore, in step 8, the kinematic viscosity coefficient v at the in-situ measurement is calculated using the following formula (6): 2 ;

[0035]

[0036] In the above formula (6), v 1 is the kinematic viscosity coefficient of the atmosphere under calibration conditions; v 2 is the kinematic viscosity coefficient at the in-situ measurement location; T 1 is the temperature of the hot wire under calibration conditions; T 2 is the temperature of the hot wire at the in-situ measurement point; P 1 T is the atmospheric pressure at the location of the hot wire anemometer during calibration;2 is the atmospheric pressure at the in-situ measurement location.

[0037] Furthermore, in step 9, the inner scale l of the atmospheric turbulence is calculated using the following formula (7): 0 ;

[0038]

[0039] In the above formula (7), v 2 is the kinematic viscosity coefficient at the in-situ measurement location; ε 3 is the third-order turbulence dissipation rate of the atmosphere ε 3 .

[0040] Furthermore, in step 10, the turbulence I is calculated using the following formula (8):

[0041]

[0042] In the above formula (8), σ is the root mean square of the turbulent fluctuation velocity within the time interval td (i.e., the standard deviation of the wind speed), is the average wind speed in the time interval td.

[0043] The present invention also provides a computer program product, comprising a computer program; when the computer program is executed by a processor, the computer program implements the dynamic turbulence measurement method described above.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] The present invention discloses a dynamic turbulence measurement method, which adopts a hot-wire anemometer with two hot-wire probes to measure the wind speed at two points in space; then sets the sampling frequency fc, statistical average time ts and space length r of the hot-wire anemometer; obtains the voltage data output by the hot-wire anemometer and determines whether the voltage data is normal, and removes abnormal data; obtains the corrected voltage data; calculates the wind speed u according to the corrected voltage data; determines the time interval td according to the preset sampling frequency fc, and calculates the speed structure constant by combining the wind speeds measured by the two hot-wire probes. Calculate the second-order and third-order turbulence dissipation rates; calculate the kinematic viscosity coefficient v at the in-situ measurement point in turn 2 , the inner scale of atmospheric turbulence 0 and turbulence I.

[0046] The dynamic turbulence measurement method of the present invention overcomes the shortcomings of the temperature pulsation meter being unable to measure dynamic turbulence and the poor applicability of the ultrasonic anemometer platform, and has the advantages of being easy to operate, suitable for harsh environments, and being carried on a sounding balloon for high-altitude turbulence measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention is a flow chart of a method for measuring dynamic turbulence.

[0048] Figure 2 A schematic diagram of a hot wire anemometer with two hot wire probes predicted by a dynamic turbulence measurement method of the present invention.

[0049] The present invention will be further described below through specific implementation modes in conjunction with the accompanying drawings. DETAILED DESCRIPTION

[0050] See also Figure 1-2 A dynamic turbulence measurement method of the present invention mainly comprises the following steps:

[0051] Step 1: Use a hot wire anemometer with two hot wire probes to measure the wind speed at two points in the space;

[0052] The hot wire anemometer of the present invention obtains the wind speed by converting the flow velocity signal into a voltage signal and then measuring it. A thin metal wire (also called a hot wire, a tungsten wire is used in the present invention) that is electrically heated is placed in the airflow. The heat dissipated by the hot wire in the airflow is related to the flow velocity, and the heat dissipation causes the temperature of the hot wire to change, which causes the resistance to change, thereby converting the flow velocity signal into a voltage signal. The flow velocity signal can be obtained by measuring the voltage signal, thereby measuring the wind speed. In the present invention, each hot wire probe corresponds to the wind speed at one of the two points in the measurement space. The two hot wire probes are the first hot wire probe and the second hot wire probe. The two points in the space corresponding to the first hot wire probe and the second hot wire probe are the first space point and the second space point.

[0053] The first hot wire probe measures the first wind speed at the first spatial point The second hot wire probe measures the second wind speed at the second spatial point vector vector are the position vectors of the first spatial point and the second spatial point respectively, r is the distance between the first spatial point and the second spatial point to be measured, and also the distance between the two hot wire probes. r is usually taken as 1m, that is, the modulus of the vector like Figure 2 , take the position of the first probe on the left as the coordinate origin O, take the vertical direction as the Y axis, and use the straight line and direction from the first probe to the second probe to determine the X axis, and establish a left-hand coordinate system. In this way, the coordinates of the first probe are (0, 0, 0), and the coordinates of the second probe are (r, 0, 0), which is convenient for calculating vectors and coordinates.

[0054] Step 2: After arranging the hot wire anemometer, set the sampling frequency fc, statistical average time ts and spatial length r of the hot wire anemometer;

[0055] Step 3: Obtain the voltage data output by the hot-wire anemometer, and determine whether the voltage data is normal based on the identifier Bs, and eliminate abnormal data; in the voltage data output by the hot-wire anemometer, except for the last digit of the voltage data, the other data is the voltage value, and the last digit of the voltage data is the custom identifier Bs. The identifier Bs is set by the hot-wire anemometer itself in the measurement program. When the detected voltage value is 0, the output voltage data contains the identifier Bs; from the identifier Bs, it can be seen that the voltage value of the voltage data is 0, indicating that this voltage data is invalid data. If the identifier Bs is not found in the voltage data, the voltage data is considered to be valid data.

[0056] Step 4: Correct the voltage data obtained after removing the abnormal data to obtain corrected voltage data;

[0057] Step 5: Calculate the wind speed u based on the corrected voltage data;

[0058] Step 6: Determine the time interval td according to the preset sampling frequency fc, and combine the first wind speed measured by the two hot wire probes and the second wind speed Calculate velocity structure constants

[0059] In specific implementation, the time interval td is an integer k times of the sampling period 1 / fc, which means that k measurements are performed within the time interval td, and each measurement obtains a set of first wind speeds at the first spatial point and the second spatial point. and the second wind speed A total of k groups of first wind speed were obtained and the second wind speed

[0060] Step 7: Calculate the second-order turbulence dissipation rate ε 2 and the third-order turbulence dissipation rate ε 3 ;

[0061] Step 8: Calculate the kinematic viscosity coefficient v at the in-situ measurement 2 ;

[0062] Step 9: Calculate the inner scale l of atmospheric turbulence 0 ;

[0063] Step 10: Calculate the turbulence intensity I.

[0064] like Figure 1 As shown, in the dynamic turbulence measurement method of the present invention, the method uses Figure 2The hot wire anemometer with two hot wire probes shown in the figure is used to measure the wind speed at two points in space, and then calculate the time series data of the wind speed. Then, under the premise of assuming uniform isotropic turbulence, the wind speed at these two points is differentiated and the velocity structure constant of the wind speed is statistically calculated. Real-time measurement of dynamic turbulence parameters, i.e., the turbulence internal scale l 0 and turbulence I.

[0065] In the specific implementation, in step 4, the voltage data obtained after removing the abnormal data is corrected using the following formula (1);

[0066]

[0067] In formula (1), E 1 is the output voltage of the hot wire anemometer in the calibration state, E 2 is the output voltage of the hot wire anemometer at the in-situ measurement point; ξ is the correction coefficient, which is related to the velocity, pressure and Reynolds number of the air flow; n is a parameter related to the Reynolds number at the in-situ measurement point, and m is a parameter related to the Reynolds number at the calibration state; v 1 is the kinematic viscosity coefficient of the atmosphere under calibration conditions; T w is the working temperature of the hot wire of the hot wire anemometer; T 1 is the temperature of the hot wire under calibration conditions; T 2 is the temperature of the hot wire at the in-situ measurement point; P 1 T is the atmospheric pressure at the location of the hot wire anemometer during calibration; 2 is the atmospheric pressure at the in-situ measurement location.

[0068] In specific implementation, the voltage data of the two probes of the hot-wire anemometer are corrected separately, and the correction formula adopts the above formula (1), that is, the above formula (1) is applicable to any probe of the two probes of the hot-wire anemometer. w is the operating temperature of the first hot-wire probe of the two probes in the measurement state, and the other related parameters are also the related parameters of the first hot-wire probe. When correcting the voltage data of the second hot-wire probe, the related parameters corresponding to the second hot-wire probe are used in formula (1). The in-situ measurement point refers to the position of the current measurement point after the hot-wire anemometer determines the measurement position and fixes it.

[0069] In the specific implementation, in step 5, the following formula (2) is used to calculate the wind speed u according to the corrected voltage data;

[0070]

[0071] In formula (2), E is the output voltage value of the hot wire anemometer, u is the wind speed corresponding to the output voltage value E, and I wis the hot wire working current corresponding to the output voltage value E, R w is the hot wire working resistance corresponding to the output voltage value E, R f is the constant temperature resistance of the hot wire at room temperature, and A and B are constants related to the length of the hot wire and the physical properties of the fluid.

[0072] In specific calculations, E is the output voltage value of any one of the two probes of the hot-wire anemometer. Formula (2) is the same as formula (1) and can be applied to any one of the two probes of the hot-wire anemometer. In specific measurements, the working temperatures set for the two probes are the same. Ideally, the first hot-wire probe and the second hot-wire probe are two identical probes with two sets of circuits. The first hot-wire probe measures the first wind speed at the first spatial point x. The second hot wire probe measures the second wind speed at the second spatial point x+r A and B are constants related to the length of the hot wire and the physical properties of the fluid. Through formula (2), a set of two data is obtained each time: the first wind speed and the second wind speed The purpose of using formula (2) to correct voltage data is to correct errors caused by large differences in temperature and air pressure when calibrated in the laboratory under high altitude conditions.

[0073] In the specific implementation, in step 6, the velocity structure constant is calculated using the following formula (3):

[0074]

[0075] In formula (3), D uu (r) represents a vector The second-order structure function of the measured space is: r is the distance between two points in the measured space; C is a dimensionless constant, usually 2; ε 2 is the second-order turbulence dissipation rate of the atmosphere, indicating that the turbulence dissipation rate is obtained through the second-order structure function Calculated; <> indicates statistical average.

[0076] In specific implementation, the time interval td is an integer k times the sampling period 1 / fc, which means that k measurements are performed within the time interval td, and each measurement obtains a pair of wind speed values ​​at two points in space: the first wind speed and the second wind speed A total of k pairs of the first wind speed are obtained and the second wind speed

[0077] In the above formula (3), <> represents the statistical average, which means that the hot wire anemometer performs multiple measurements within the time interval td. Each measurement obtains a set of first wind speed and the second wind speed Indicates the second wind speed of any group With the first wind speed The square of the difference of Taking the average value, we get According to multiple sets of wind speed measurement values ​​within the time interval td, it can be known from formula (3) The velocity structure constant can be calculated

[0078] In the specific implementation, in step 7, the second-order turbulence dissipation rate ε is calculated using the following formula (4): 2 ;

[0079]

[0080] In formula (4), C is a dimensionless constant, usually 2; is the velocity structure constant of wind speed.

[0081] ε 2 The subscript 2 indicates that the turbulent dissipation rate is calculated by the second-order structure function. According to the above formula (4), the velocity structure constant Substituting, when the dimensionless constant C is determined, the second-order turbulence dissipation rate ε can be calculated 2 .

[0082] In the specific implementation, in step 7, the third-order turbulence dissipation rate ε is calculated using the following formula (5): 3 ;

[0083]

[0084] In the above formula (5), Representation vector The third-order structure function of , r is the distance between two points in the measured space.

[0085] Through the third-order structure function Calculate the third-order turbulence dissipation rate ε of the atmosphere 3 ε 3 The subscript 3 indicates that the turbulence dissipation rate is calculated using the third-order structure function. The third-order structure function contains the second wind speed With the first wind speed The cube of the difference.

[0086] In the specific implementation, in step 8, the kinematic viscosity coefficient v at the in-situ measurement is calculated using the following formula (6): 2 ;

[0087]

[0088] In the above formula (6), v1 is the kinematic viscosity coefficient of the atmosphere under calibration conditions; v 2 is the kinematic viscosity coefficient at the in-situ measurement location; T 1 is the temperature of the hot wire under calibration conditions; T 2 is the temperature of the hot wire at the in-situ measurement point; P 1 T is the atmospheric pressure at the location of the hot wire anemometer during calibration; 2 is the atmospheric pressure at the in-situ measurement location.

[0089] In the specific implementation, in step 9, the following formula (7) is used to calculate the inner scale l of the atmospheric turbulence: 0 ;

[0090]

[0091] In the above formula (7), v 2 is the kinematic viscosity coefficient at the in-situ measurement location; ε 3 is the third-order turbulence dissipation rate of the atmosphere ε 3 .

[0092] In the specific implementation, in step 10, the turbulence I is calculated using the following formula (8);

[0093]

[0094] In the above formula (8), σ is the root mean square of the turbulent fluctuation velocity within the time interval td (i.e., the standard deviation of the wind speed), is the average wind speed in the time interval td.

[0095] σ and These are all results calculated based on the data measured by any one of the two hot wire probes within the time interval td.

[0096] For example, the time interval td is an integer k times the sampling period 1 / fc, which means that k measurements are performed within the time interval td. Taking the first probe as an example, k first wind speed measurements are obtained within the time interval td. but The calculation process of is shown in the following formula (9).

[0097]

[0098] In the above formula (9), k measurements are performed within the time interval td, and k first wind speeds are obtained: is the k first wind speed The average value of .

[0099] The calculation process of σ is shown in the following formula (10).

[0100]

[0101] In the above formula (10), k measurements are performed within the time interval td, and k first wind speeds are obtained: is the k first wind speed The average value of . There are k With these k The average of the squares of the differences between the means.

[0102] In specific implementation, since the distance between the first spatial point and the second spatial point is only 1 meter, for large-scale turbulent vortices greater than the distance between the two points, the speeds of the two points are relatively consistent, and it can be considered that the turbulence I calculated from the wind speed values ​​obtained at the first spatial point and the second spatial point is basically the same. Therefore, the calculation of turbulence I only requires a set of first wind speed values. Or a second wind speed No need to adjust the first wind speed and the second wind speed In fact, even if the two sets of wind speed values ​​measured at the first spatial point and the second spatial point are different, the two turbulence intensities I finally calculated are basically the same.

[0103] The present invention also provides a computer program product, comprising a computer program; when the computer program is executed by a processor, the computer program implements the dynamic turbulence measurement method described above.

[0104] The above steps 1 to 10 are compiled into a measurement algorithm and embedded in the output program of the hot wire anemometer, so that real-time measurement of dynamic turbulence parameters can be performed.

[0105] like Figure 2 : is a schematic diagram of the structure of the hot-wire anemometer used in the present invention. The hot-wire anemometer includes a hot-wire anemometer host 4, and two support rods 3 are arranged at the top of the hot-wire anemometer host 4. The two support rods 3 are V-shaped. The bottom of each support rod 3 is connected to the hot-wire anemometer host, and a metal bracket 2 is arranged at the top of each support rod 3. A thin metal wire is arranged at the top of the metal bracket 2, and the thin metal wire used in the present invention is a tungsten wire 1.

[0106] The dynamic turbulence measurement method of the present invention uses a hot wire anemometer with two hot wire probes to measure the time series data of the velocity at two points in space. Under the assumption of uniform isotropic turbulence, the velocities of the two points are differentiated to calculate the velocity structure constant, and the dynamic turbulence parameters are measured in real time. The method of the present invention is easy to operate and can be observed for a long time without human supervision; it overcomes the shortcomings of the temperature pulsator that cannot measure dynamic turbulence and the poor applicability of the ultrasonic anemometer platform, and provides a guarantee for the long-term continuous acquisition of dynamic turbulence parameters.

[0107] In addition, the dynamic turbulence measurement method of the present invention can realize unattended, long-term continuous real-time measurement of dynamic turbulence parameters in harsh environments such as marine atmosphere environment, high temperature and cold environment, strong wind weather, etc., and can be applied to high-altitude turbulence measurement carried out on sounding balloons.

[0108] The dynamic turbulence measurement method of the present invention is a new method for real-time measurement of dynamic turbulence parameters using a hot-wire anemometer with two hot-wire probes. The method uses a hot-wire anemometer with a high dynamic response and high precision dual-point hot-wire probe to measure the velocity time series data of two points in space, which to a certain extent eliminates the measurement errors caused by the conventional hot-wire anemometer and ultrasonic anemometer located on a moving platform and the influence of solar radiation in the high-altitude environment on the conventional single-point hot-wire anemometer. At the same time, according to factors such as the temperature and pressure of the current different working environments, the temperature and pressure are corrected at the in-situ measurement point. Using the corrected velocity time series data, under the assumption of uniform isotropic turbulence, the velocities of the two points are differentiated and statistically calculated to obtain the velocity structure constant. The new method for real-time measurement of dynamic turbulence parameters provides a guarantee for all-weather and long-term continuous acquisition of dynamic turbulence parameters.

[0109] In summary, the dynamic turbulence measurement method of the present invention overcomes the shortcomings of the temperature pulsation meter being unable to measure dynamic turbulence and the poor applicability of the ultrasonic anemometer platform, and has the advantages of being easy to operate, suitable for harsh environments, and being carried on a sounding balloon for high-altitude turbulence measurement.

[0110] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0111] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for measuring dynamic turbulence, characterized in that: The steps include: Step 1: Use a hot wire anemometer with two hot wire probes to measure the wind speed at two points in the space; Step 2: After arranging the hot wire anemometer, set the sampling frequency fc, statistical average time ts and spatial length r of the hot wire anemometer; Step 3: Obtain the voltage data output by the hot wire anemometer, and determine whether the voltage data is normal based on the identifier Bs, and remove abnormal data; Step 4: Correct the voltage data obtained after removing the abnormal data to obtain corrected voltage data; Step 5: Calculate the wind speed u based on the corrected voltage data; Step 6: Determine the time interval td according to the preset sampling frequency fc, and combine the first wind speed measured by the two hot wire probes and the second wind speed Calculate velocity structure constants Step 7: Calculate the second-order turbulence dissipation rate ε2 and the third-order turbulence dissipation rate ε3; Step 8: Calculate the kinematic viscosity coefficient v2 at the in-situ measurement location; Step 9: Calculate the inner scale l0 of atmospheric turbulence; Step 10: Calculate the turbulence intensity I.

2. A method for measuring dynamic turbulence according to claim 1, characterized in that: In step 4, the voltage data obtained after removing the abnormal data is corrected using the following formula (1); In formula (1), E1 is the output voltage of the hot wire anemometer in the calibration state, E2 is the output voltage of the hot wire anemometer in the in-situ measurement position; ξ is the correction coefficient, which is related to the velocity, pressure and Reynolds number of the air flow; n is a parameter related to the Reynolds number in the in-situ measurement position, m is a parameter related to the Reynolds number in the calibration state; v1 is the kinematic viscosity coefficient of the atmosphere in the calibration state; T w is the working temperature of the hot wire of the hot wire anemometer; T1 is the temperature of the hot wire in the calibration state; T2 is the temperature of the hot wire at the in-situ measurement point; P1 is the atmospheric pressure at the location of the hot wire anemometer in the calibration state; T2 is the atmospheric pressure at the in-situ measurement point.

3. A method for measuring dynamic turbulence according to claim 1, characterized in that: In step 5, the following formula (2) is used to calculate the wind speed u according to the corrected voltage data; In formula (2), E is the output voltage value of the hot wire anemometer, u is the wind speed corresponding to the output voltage value E, and I w is the hot wire working current corresponding to the output voltage value E, R w is the hot wire working resistance corresponding to the output voltage value E, R f is the constant temperature resistance of the hot wire at room temperature, and A and B are constants related to the length of the hot wire and the physical properties of the fluid.

4. A method for measuring dynamic turbulence according to claim 1, characterized in that: In step 6, the velocity structure constant is calculated using the following formula (3): In formula (3), D uu (r) represents a vector The second-order structure function, r is the distance between the two points in the measured space; C is a dimensionless constant, usually taken as 2; ε2 is the second-order turbulence dissipation rate of the atmosphere, indicating that the turbulence dissipation rate is through the second-order structure function Calculated; <> indicates statistical average.

5. A method for measuring dynamic turbulence according to claim 1, characterized in that: In step 7, the second-order turbulence dissipation rate ε2 is calculated using the following formula (4); In formula (4), C is a dimensionless constant, usually 2; is the velocity structure constant of wind speed.

6. A method for measuring dynamic turbulence according to claim 5, characterized in that: In step 7, the third-order turbulence dissipation rate ε3 is calculated using the following formula (5); In the above formula (5), Representation vector The third-order structure function of , r is the distance between two points in the measured space.

7. A method for measuring dynamic turbulence according to claim 1, characterized in that: In step 8, the kinematic viscosity coefficient v2 at the in-situ measurement location is calculated using the following formula (6); In the above formula (6), v1 is the kinematic viscosity coefficient of the atmosphere under the calibration state; v2 is the kinematic viscosity coefficient at the in-situ measurement point; T1 is the temperature of the hot wire under the calibration state; T2 is the temperature of the hot wire at the in-situ measurement point; P1 is the atmospheric pressure at the location of the hot wire anemometer under the calibration state; T2 is the atmospheric pressure at the in-situ measurement point.

8. A method for measuring dynamic turbulence according to claim 6, characterized in that: In step 9, the inner scale l0 of atmospheric turbulence is calculated using the following formula (7); In the above formula (7), v2 is the kinematic viscosity coefficient at the in-situ measurement point; ε3 is the third-order turbulence dissipation rate ε3 of the atmosphere.

9. A method for measuring dynamic turbulence according to claim 1, characterized in that: In step 10, the turbulence I is calculated using the following formula (8); In the above formula (8), σ is the root mean square of the turbulent fluctuation velocity within the time interval td, is the average wind speed in the time interval td.

10. A computer program product, comprising a computer program; wherein: When the computer program is executed by a processor, the computer program implements the dynamic turbulence measurement method according to any one of claims 1 to 9.

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