Device for measuring electric quantity of single particle in wind tunnel environment

Abstract

The utility model relates to a device for measuring the electric quantity of a single particle in a wind tunnel environment. The device structurally comprises a wind-sand flow simulation device and a particle collecting and measuring device below the wind-sand flow simulation device, according to the wind-sand flow simulation device, a fan is connected to a port in one side of a square-tube-shaped shell, a net plate, a rough element and a sand blocking plate are sequentially arranged in the shell in the wind coming direction, the area between the sand blocking plate and the rough element is a containing area for particles of the target type, and the periphery of the net plate is connected to the inner wall of the shell in a sealed mode. The rough element and the sand baffle are arranged on the inner bottom surface of the shell; a sand falling opening is formed in the bottom of the shell behind the sand baffle, and a lower turning cover plate is arranged on the sand falling opening; silicone oil is filled in a transparent box body of the particle collecting and measuring device, electrode plates are respectively adhered to two opposite side surfaces of the transparent box body, a camera is arranged in front of the other adjacent side surface, and the two electrode plates are connected with a high-voltage power supply. According to the utility model, by collecting a small amount of particles, the electric quantity of a single particle of a target type at a target wind speed is accurately measured.

Description

Technical Field

[0001] This utility model relates to an electrical charge measuring device, specifically an electrical charge measuring device for a single particle in a wind tunnel environment. Background Technology

[0002] Measuring the charge of dust particles in aeolian environments is a fundamental and crucial task in aeolian environmental research. Since the 1970s and 80s, numerous scholars have measured the charge of dust particles in indoor wind tunnels or in field environments. The specific measurement methods vary across experiments, but the main methods include: space charge density method, Faraday cylinder collection method, impulse current method, and trajectory image processing method. However, these techniques measure the average charge-to-mass ratio of mixed particles and cannot calculate the charge of individual particles. From a statistical physics perspective, the charge distribution of a large number of particles follows certain statistical laws. Accurately calculating the charge of individual particles is fundamental to studying overall statistical laws and helps in establishing more accurate particle dynamics models to describe the behavior of sand and other particulate matter under various external forces.

[0003] Currently, single-particle charge measurement devices involve transfer and equipment connection operations between particle collection and charge measurement, making it impossible to perform collection and measurement simultaneously. This can lead to significant errors during operation (such as particle charge transfer and collection device shaking), resulting in inaccurate calculation of the charge of a single particle. Utility Model Content

[0004] The purpose of this invention is to provide a device for measuring the charge of a single particle in a wind tunnel environment, so as to solve the problem of inaccurate measurement of the charge of a single particle by existing measuring devices, thereby improving efficiency and accuracy.

[0005] The technical solution of this utility model is as follows:

[0006] A device for measuring the charge of a single particle in a wind tunnel environment includes a wind and sand flow simulation device and a particle collection and measurement device disposed below the wind and sand flow simulation device.

[0007] The wind and sand flow simulation device has a fan connected to one end of a square tubular shell. Inside the shell, along the direction of the incoming wind, a mesh plate, a rough element, and a sand baffle are arranged in sequence. The area between the sand baffle and the rough element is the placement area for the target type of particles. The mesh plate is sealed around the inner wall of the shell. The rough element and the sand baffle are located on the inner bottom surface of the shell. A sand drop outlet is opened at the bottom of the shell behind the sand baffle, and a downward-folding cover plate is provided on the sand drop outlet.

[0008] The particle collection and measurement device includes a transparent box, electrode plates, a camera, and a high-voltage power supply. The transparent box has a sand inlet hole at the center of its top surface. Silicone oil is placed inside the transparent box. The camera lens faces the transparent box. The electrode plates are attached to two opposite sides of the transparent box. The high-voltage power supply is electrically connected to the two electrode plates.

[0009] Furthermore, the distance between the rough element and the sand baffle is two-thirds of the total shell length.

[0010] Furthermore, the sand-blocking plate is 2cm higher than the top surface of the target type of particles, and the width of the sand-blocking plate is the same as the width of the shell of the sandstorm simulation device.

[0011] Furthermore, the outer top surface of the transparent box is coated with silicone oil.

[0012] Furthermore, the mesh plate has mesh holes with a side length of 1cm, which are evenly distributed on the mesh plate.

[0013] Furthermore, an anemometer is also installed on the top surface inside the casing of the sandstorm simulation device.

[0014] Furthermore, the particle collection and measurement device also includes an illumination light source, which is disposed below the transparent housing.

[0015] Furthermore, the camera lens is also equipped with a filter.

[0016] Furthermore, both the filter and the illumination light source correspond to the dye used for the target type of particles.

[0017] This invention utilizes a glass housing with a fan at one end and a mesh panel near the fan outlet to stabilize the airflow. Roughness elements made of wood are placed along the fan's direction to simulate the atmospheric boundary layer, ensuring the similarity between the wind tunnel experiment and actual field conditions, resulting in more accurate particle charge measurements. Placing the transparent housing of the particle collection and measurement device below the wind tunnel end of the sand flow simulation device allows for simultaneous particle collection and charge measurement, simplifying the experiment and reducing measurement errors. A sand inlet hole at the center of the transparent housing reduces the number of wind-blown particles falling into the housing. Using a matching light source and filter, the charge of individual particles is more easily calculated. A downward-opening cover at the sand inlet allows for more accurate measurements, as the particles falling into the housing are at the target wind speed. The charge of each particle is determined by the particle's movement distance, mass, and surrounding electric field strength in the image. Based on images taken at different times and the time intervals between images (the time intervals between images are small), the charge of a single particle under different erosion durations can be calculated. The materials used in this device are all common materials, the manufacturing process is simple, and the cost is low.

[0018] This invention can also measure the charge of a single particle of a target type in a mixture of particulate matter. Particles become charged when blown by wind because of friction between the air and the particles, and between the particles themselves. The charge of the target type of particles differs when wind blows in an environment containing only the target type of particles versus an environment where the target type of particles are mixed with other types of particles. Since most aeolian sand environments do not contain only one type of particle, other types of particles are added between the roughness element and the sand barrier. The target type of particles are then stained, and a matching light source and filter are used. Even if the target type of particles are mixed with different types of particles, the camera can only capture the target type of particles. The measured charge of the target type of particles more closely matches the charge of the target type of particles in actual aeolian sand environments, resulting in more accurate measurements. Attached Figure Description

[0019] Figure 1 This is a structural diagram of the present invention.

[0020] Figure 2 It is a moving image of PVC particles.

[0021] In the figure: 1. Sandstorm simulation device; 2. Particle collection and measurement device; 11. Shell; 12. Mesh plate; 13. Rough element; 14. Anemometer; 15. Sand baffle; 16. Flip-down cover; 21. Transparent box; 22. Irradiation light source; 23. Electrode plate; 24. Camera; 25. High voltage power supply. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] like Figure 1 As shown, the wind tunnel environment single particle charge measurement device provided by this utility model includes a wind and sand flow simulation device 1 and a particle collection and measurement device 2.

[0024] Among them, the particle collection and measurement device 2 is located below the wind and sand flow simulation device 1 and is used to collect charged particles.

[0025] The sandstorm simulation device 1 includes a shell 11, a fan, a mesh plate 12, a rough element 13, a sand baffle 15, and a lower cover plate 16. One side of the square tubular shell is open, and the opposite side is connected to a fan to form a wind tunnel. The mesh plate 12, the rough element 13, and the sand baffle 15 are arranged in sequence inside the shell 11 in the direction of the fan's airflow. The mesh plate 12 is sealed around the inner wall of the shell 11. The area between the sand baffle 15 and the rough element 13 is the placement area for the target type of particles. The rough element 13 and the sand baffle 15 are set on the inner bottom surface of the shell 11. A sand drop port is opened at the bottom of the shell 11 behind the sand baffle 15, and a lower cover plate 16 is set on the sand drop port.

[0026] The shell 11 of the sandstorm simulation device 1 can be made of glass. The blower is connected to one side of the shell, allowing the blower to simulate the wind blowing into the shell in an outdoor environment. The height of the mesh plate 12 is the same as the internal height of the shell 11, and the width of the mesh plate 12 is the same as the internal width of the shell 11. The mesh plate 12 can be made of stainless steel, and the side length of the mesh holes in the mesh plate 12 is 1 cm, evenly distributed on the mesh plate 12. The roughness element 13 is fixed to the bottom of the shell 11. The air blown by the blower passes through the mesh plate 12, making the incoming flow more stable and uniform. The distance between the roughness element 13 and the sand baffle 15 is two-thirds of the length of the shell 11 of the sandstorm simulation device.

[0027] The shape and arrangement of the rough elements 13 behind the mesh plate 12 were obtained through continuous experimentation. The rough elements 13 are cubes, cuboids, or cones of different heights made of wooden blocks. The arrangement and shape of the rough elements are continuously changed in the wind tunnel cross-section simulation device until the wind speed distribution meets the logarithmic distribution law, making the average wind speed profile curve smoother and making the wind conditions inside the shell 11 more consistent with the actual wind conditions in the field. For example, the rough elements can be five rows of cubes and one row of cuboids. The side length of the cube rough elements is one-thirtieth of the shell height, and the length and width of the cuboid rough elements are both one-thirtieth of the shell height, and the height is one-fifteenth of the shell height.

[0028] A sand drop opening is provided at the bottom of the shell between the sand baffle 15 and the opening, allowing particles to fall from the sand drop opening and into the particle collection and measurement device. A fan with a fixed target wind speed can be used. At the beginning of the blowing, the wind speed may not reach the target wind speed. It is necessary to cover the sand drop opening with the lower cover 16 to prevent particles from falling into the particle collection and measurement device. When the fan blows air steadily, the lower cover 16 is opened. The particle charge measured at this time is the particle charge at the target wind speed.

[0029] An anemometer is also installed on the top surface of the shell 11 at the front end of the target type of particle shell. For variable speed fans, the changes in wind speed can be observed more intuitively, making it easier to adjust the wind speed.

[0030] This invention requires measuring particles that have undergone a jump but have not experienced charge transfer. The sand baffle 15 can prevent creeping particles from entering the particle collection and measurement device. The bottom of the housing behind the sand baffle 15 is coated with silicone oil. The silicone oil coating can adhere to particles that come into contact with and collide with the housing, preventing particles that have undergone charge transfer from entering the particle collection and measurement device.

[0031] The particle collection and measurement device 2 includes a transparent box 21, electrode plates 23, a high-voltage power supply 25, and a camera 24. A sand inlet hole is opened in the center of the top surface of the transparent box. Silicone oil is filled in the transparent box 21. The electrode plates 23 are respectively attached to two opposite sides of the transparent box. The lens of the camera 24 faces the side adjacent to the side with the electrode plates attached. The high-voltage power supply 25 is connected to the two electrode plates 23 respectively.

[0032] In the particle collection and measurement device 2, the center of the sand inlet of the transparent box 21 is directly below the center of the sand drop outlet at the bottom of the shell 11 in the wind and sand flow simulation device 1. This allows for the simultaneous collection of particles and measurement of charge, reducing other operations between collection and measurement and making the measurement result less erroneous.

[0033] The transparent box 21 can be made of glass.

[0034] The outer top surface of the transparent box 21 is coated with silicone oil.

[0035] Taking PVC particles as an example, the target particle type of this invention is a transparent box 21 placed directly below the tail end of the wind tunnel to collect PVC particles. Before each experiment, silicone oil is applied to the inside bottom surface of the shell at the tail end of the wind tunnel (i.e., behind the sand baffle) and the top surface of the transparent box 21, with the silicone oil level 10mm from the top surface of the transparent box. One side electrode plate 23 of the transparent box 21 is connected to the output terminal of the high-voltage power supply 25, and the other side electrode plate 23 is grounded. The high-voltage power supply 25 is set to 20kV. The center of the camera 24 can be directly aligned with the center of the plane of the transparent box 21; alternatively, COMSOL software can be used to numerically simulate the electric field generated by the parallel electrode plates on both sides of the transparent box to determine the uniform electric field region and electric field value inside the box when a 20kV high voltage value is applied to the electrode plates. A model was constructed based on the actual conditions of the transparent box, silicone oil, and electrode plates. The voltage of one electrode plate was set to 20kV, while the other electrode plate was grounded. The simulation results showed that the uniform electric field region inside the transparent box was between 8-16cm above the liquid surface, with an electric field value of 261000.093V / m. Camera 24 was positioned in front of the transparent box 21. A calibration ruler was placed in the center of the transparent box, and the camera was focused on the plane containing the calibration ruler, ensuring that the shooting area was within the uniform electric field. This reduces measurement errors and ensures that the captured particle movements occur under the same electric field conditions. This avoids interference from differences in particle motion states caused by varying electric field strengths, improving the accuracy and reliability of the measurement.

[0036] In this invention, only target type particles are placed between the rough element 13 and the sand baffle 15. A suitable fan is used, or the fan is adjusted to a suitable wind speed, so that a small number of target type particles fall from the sand drop outlet into the transparent box 21.

[0037] This invention can also place target particles and other particles between the rough element 13 and the sand baffle 15 to measure the charge of the target particles when blown by the wind in the mixed particles, making the measured charge of the target particles more accurate. At this point, the target particles need to be dyed. The particle collection and measurement device also includes an illumination light source 22, which is located below the transparent box 21 and can illuminate the interior of the transparent box 21. A filter is set on the lens of the camera 24. The illumination light source 22 and the filter of the camera 24 used in this invention are matched with the dye used to dye the target particles. For example, when using Nile Red dye to dye the target particles, an ultraviolet lamp needs to be selected as the illumination light source to excite the dyed PVC particles to emit fluorescence; a filter that only allows light above 560 nanometers to pass through is used. The selection of the ultraviolet lamp and filter needs to ensure that the light is sufficient to excite the dyed particles to emit fluorescence, and that the filter can filter out undyed particles. When using Rhodamine 123 to stain target particles, it exhibits green fluorescence. The excitation wavelength is generally around 500 nm, and blue or green light can be used as the irradiation source. A filter that allows light of 520-550 nm to pass through should be used.

[0038] Taking PVC granules as an example, Nile red dye is used to dye the PVC granules. First, a fluorescent dyeing solution is prepared, with 10 mg of Nile red dye dissolved in 1 L of ethanol solution, and stirred until the Nile red dye is fully dissolved. Then, the fluorescent dyeing solution is poured into the PVC granules, and fluorescent dyeing is carried out for 30 minutes, followed by air drying in a cool place. Finally, the dyed PVC granules and sand are mixed at a ratio of 1:50 and spread evenly on the bottom of the shell between the rough element 13 and the sand baffle 15.

[0039] The camera 24 used in this invention can also be a high-speed camera. In this case, a computer is needed to control the camera 24 to shoot and store images, and the camera 24 is connected to the computer.

[0040] The method of using this utility model is as follows:

[0041] The wind tunnel test begins. The fan is turned on, and the anemometer 14 is observed. Once the wind speed reaches the target speed of 12 m / s, the lower cover 16 is opened. Charged particles eroded by the wind will fall into the transparent chamber 21 through the sand inlet hole on the top surface. Particles that come into contact with the tail end of the shell or the transparent chamber will be adhered to by the silicone oil coating, preventing particles that undergo charge transfer from entering the transparent chamber 21. After the particles in the transparent chamber 21 settle into the field of view of the camera 24, the camera 24 with a filter begins to record the trajectory of the dyed PVC particles. Then, the 20kV high-voltage power supply is turned on. Under the action of the electric field, the charged particles begin to move towards the electrode plate (negatively charged) connected to the power output terminal or towards the grounded electrode plate (positively charged). After a certain period of time, the high-voltage power supply is turned off to prevent the particles from contacting the chamber wall.

[0042] like Figure 2 As shown, camera 24 stops filming and stores the moving images of the dyed PVC particles.

[0043] Use a glass pipette to collect the particles one by one into a small glass vial, label them with numbers and record the collection location, and use a microbalance to determine their mass.

[0044] After the experiment, the motion images of the dyed PVC particles were processed. The displacement of the PVC particles was calculated based on their position, brightness, and size in multiple consecutive frames. Bitwise operations were then performed, with the time interval between two frames used to obtain the velocity information of the PVC particles. The charge of each particle was then calculated using the following formula:

[0045]

[0046] Where m is the mass of a single particle, g is the gravitational acceleration, E is the electric field strength, which can be obtained by modeling the transparent box 21 using Comsol multi-simulation physics software, and v x It is the horizontal velocity of a single particle, v y It is the vertical velocity of a single particle, ρ o It is the density of silicone oil, ρ m It is the density of the particles.

[0047] As shown in Table 1, the charge of different particles was obtained.

[0048] Table 1: Electricity carried by a single PVC particle

[0049]

Claims

1. A device for measuring the charge of a single particle in a wind tunnel environment, characterized in that, It includes a sandstorm simulation device and a particle collection and measurement device installed below the sandstorm simulation device; The wind and sand flow simulation device has a fan connected to one end of a square tubular shell. Inside the shell, along the direction of the incoming wind, a mesh plate, a rough element, and a sand baffle are arranged in sequence. The area between the sand baffle and the rough element is the placement area for the target type of particles. The mesh plate is sealed around the inner wall of the shell. The rough element and the sand baffle are located on the inner bottom surface of the shell. A sand drop outlet is opened at the bottom of the shell behind the sand baffle, and a downward-folding cover plate is provided on the sand drop outlet. The particle collection and measurement device includes a transparent box, electrode plates, a camera, and a high-voltage power supply. The transparent box has a sand inlet hole at the center of its top surface. Silicone oil is placed inside the transparent box. The camera lens faces the transparent box. The electrode plates are attached to two opposite sides of the transparent box. The high-voltage power supply is connected to the two electrode plates.

2. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 1, characterized in that, The distance between the rough element and the sand baffle is two-thirds of the total shell length.

3. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 1, characterized in that, The sand-blocking plate is 2cm higher than the top surface of the target type of particles, and the width of the sand-blocking plate is the same as the width of the shell of the sandstorm simulation device.

4. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 1, characterized in that, The outer top surface of the transparent box is coated with silicone oil.

5. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 1, characterized in that, The mesh has 1cm side lengths and is evenly distributed on the mesh.

6. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 1, characterized in that, An anemometer is also installed on the top surface inside the casing of the sandstorm simulation device.

7. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 1, characterized in that, The particle collection and measurement device also includes an illumination light source, which is located below the transparent housing.

8. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 7, characterized in that, The camera lens also has a filter.

9. The device for measuring the charge of a single particle in a wind tunnel environment according to claim 8, characterized in that, Both the filter and the illumination light source correspond to the dye used for the target type of particles.

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