Gas-solid triboelectrification test method and device for moving object

Abstract

The invention discloses a gas-solid triboelectrification test method and device for a moving object, and relates to the technical field of triboelectrification measurement, and the method comprises the following steps: constructing a sample ball and gas triboelectrification model in a free falling process of a sample ball in a glove box with a built-in Faraday cage based on a Maxwell velocity distribution rule; carrying out standardized pretreatment on the sample small balls to remove residual charges on the surfaces of the sample small balls; performing air replacement in the glove box with the built-in Faraday cage until the internal air pressure and environmental parameters meet the test requirements, and determining the diameter range and the falling height of the sample small ball; filtering the electrostatic charge signal, reading the electrostatic charge quantity of the small sample ball at different falling heights, and determining the charge quantity increased by the small sample ball in the free falling process of the glove box with the built-in Faraday cage; the gas-solid friction electrification quantity of the moving object under the influence of the object moving speed, the effective friction area and the environment air pressure factor is measured in a non-contact mode.

Description

Technical Field

[0001] This invention relates to the field of triboelectric measurement technology, and in particular to a method and apparatus for testing gas-solid triboelectricity of moving objects. Background Technology

[0002] Triboelectricity between air and solid is a common physical phenomenon in nature and industrial environments, especially pronounced when high-speed moving objects such as aircraft interact with the atmosphere. During flight, the surface potential of an aircraft can reach as high as 500 kV. The pointed ends of wings and tail fins, due to design requirements, often have large surface curvatures, making them prone to static charge accumulation. This can lead to high-voltage corona discharge, interfering with the normal operation of airborne electronic equipment such as antennas, and even threatening the operational safety of the aircraft. Therefore, in-depth research into the triboelectric mechanism between moving objects and gases is not only of great significance for electrostatic protection of aircraft but also provides a theoretical basis for engineering applications in related fields.

[0003] Currently, research on the charging mechanism of aircraft mainly focuses on three aspects: gas-solid triboelectric charging between atmospheric gas molecules and aircraft skin, collisional charging between atmospheric particles and aircraft skin, and jet charging. Among these, the calculation method for surface triboelectric charging of metal-skinned aircraft flying in dust is relatively mature. Regarding jet charging, some scholars have studied the changes in charged particle concentration in the engine combustion chamber and the charge density distribution outside the combustion chamber through simulation, or measured and calculated the equivalent current of the exhaust gas from the aircraft engine through experiments.

[0004] However, air-solid friction exists throughout the entire operational cycle of an aircraft, and air-solid frictional electrification becomes particularly important as the aircraft's speed and duration of flight increase. Existing research has laid the foundation for understanding the mechanism of air-solid frictional electrification by controlling the gas environment or gas flow rate. However, when the aircraft's speed, attitude, and altitude change, its effective air-solid friction surface area and air-solid collision frequency will dynamically change accordingly. Therefore, research on the mechanism of air-solid frictional electrification should delve into the influence of the object's speed, effective friction area, and ambient air pressure on the amount of air-solid frictional electrification. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a method and apparatus for testing the gas-solid triboelectric charging of a moving object, which realizes the measurement of the gas-solid triboelectric charging of a moving object under the influence of the object's speed, effective friction area, and ambient air pressure in a non-contact manner.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] The first aspect of this application provides a method for testing the gas-solid triboelectric charging of a moving object, comprising the following steps: S101. Construct a model of triboelectric charging of a sample ball and gas during the free fall of the sample ball inside a glove box with a built-in Faraday cage. S102. Perform standardized pretreatment on the sample microspheres to remove residual charge on their surface; S103. Replace the air in the glove box with the built-in Faraday cage until the air pressure and environmental parameters in the glove box with the built-in Faraday cage meet the test requirements, and determine the diameter range and drop height of the sample ball. S104. Based on the triboelectric model of the sample ball and gas, the static charge signal of the sample ball is obtained during the free fall of the sample ball, and the static charge signal is filtered to read the static charge of the sample ball at different fall heights. S105. Based on the static charge of the sample ball at different drop heights, determine the amount of charge added to the sample ball during the free fall of the glove box with a built-in Faraday cage.

[0008] Furthermore, constructing a model of triboelectric charging of the sample ball and gas during the free fall process within a glove box with a built-in Faraday cage includes the following steps: Let the area of ​​a surface element on the surface of the sample sphere be... Construct sample microspheres in a column with a volume of The height of the column is The molecular number differential equation for the collisions with gas molecules during a free fall in space is expressed as follows: ; in, This is the differential of the number of molecules that collide with gas molecules during the free fall of the sample sphere within a glove box containing a built-in Faraday cage. For Maxwell's velocity distribution, Let be the velocity of the sample ball on the Z-axis. The derivative of the velocity of the sample ball along the XYZ axes; By performing velocity integral calculations, the velocity of the sample ball per unit time is obtained. Inside and per unit area The number of gas molecules that collide Its expression is as follows: ; in, The collision frequency between the sample sphere and gas molecules. Mass of a single gas molecule Let be the absolute temperature of the gas. For Boltzmann constant, This refers to gas pressure. Let Avogadro's constant be 1. Let be the ideal gas constant. The velocity of the sample ball; The equation for the velocity of the sample ball as a function of the drop height during free fall is constructed as follows: ; ; in, For the velocity of the sample ball, The air resistance coefficient of the sample sphere. The mass of the sample pellet. It is the acceleration due to gravity. The molar mass of air, Let be the cross-sectional area of ​​the small sphere. The drop height of the sample ball; By introducing average charge transfer The amount of electricity generated by friction between the surface of the small ball and a single gas molecule is used to represent the amount of electricity generated by friction between the small ball and the surface of the small ball. Therefore, the sample ball has a drop time of [time value missing]. Effective surface area The amount of charge transferred by collision with gas molecules As shown in the following expression: ; ; in, This represents the amount of charge transferred during the collision between the sample microsphere and gas molecules. This is the average charge transfer amount. For ambient air pressure, The absolute temperature of the gas. For effective surface area, For the time of the fall, Let Avogadro's constant be 1. Let be the ideal gas constant. This is the charge transfer coefficient during collisions between the spherical material and gas molecules. For the velocity of the sample ball, It is the Boltzmann constant.

[0009] Furthermore, the sample microspheres undergo a standardized pretreatment to remove residual surface charges, including the following steps: Anhydrous ethanol was used to clean the sample pellets once to remove surface contaminants. High-purity nitrogen gas was used to purge the sample pellets to remove residual impurities; Anhydrous ethanol was used to perform a secondary cleaning treatment on the sample microspheres to eliminate residual surface charge. The processed sample pellets are placed on the sample stage for later use to avoid recontamination.

[0010] Furthermore, the air inside the glove box with the built-in Faraday cage is replaced until the air pressure and environmental parameters inside the glove box with the built-in Faraday cage meet the test requirements, and the diameter range and drop height of the sample ball are determined, including the following steps: During the process of maintaining negative pressure by evacuating the air from the glove box with the built-in Faraday cage or replacing it with synthetic air, the dust particle density signal in the glove box with the built-in Faraday cage is continuously acquired. The experiment can only begin when the dust particle number density in the glove box with the built-in Faraday cage is 0.3um < 1000 particles / L, 0.5um < 200 particles / L, 1um < 15 particles / L, 2.5um < 2 particles / L, 5um < 0 particles / L, and 10um < 0 particles / L. The ambient air pressure range inside the glove box with the built-in Faraday cage is controlled to be 0.5 atm-1 atm; The diameter of the sample balls was selected to be in the range of 12mm-30mm in order to control the effect of their effective frictional surface area on the charge generated. The drop height of the sample balls inside the glove box with the built-in Faraday cage is controlled within the range of 0.1m-1.5m.

[0011] Furthermore, based on the triboelectric model of the sample ball and gas, the electrostatic charge signal of the sample ball is obtained during the free fall of the sample ball, and the electrostatic charge signal is filtered to read the amount of electrostatic charge of the sample ball at different fall heights. This includes the following steps: Electrostatic charge signal acquisition points at different heights were set up to obtain the electrostatic charge signal of the sample ball during the free fall of the sample ball; Discrete wavelet transform was performed on the electrostatic charge signal of the sample spheres to determine the main frequency range of the noise. By using the different heights of the electrostatic charge signal acquisition points, the signal frequency range of the sample ball when passing through the electrostatic charge signal acquisition points at different heights was determined. The electrostatic charge signal of the sample microspheres is filtered. The signal peak value of the sample ball at different drop heights is read to obtain the static charge of the sample ball at different drop heights.

[0012] Furthermore, based on the static charge of the sample ball at different drop heights, determining the amount of charge gained by the sample ball during free fall from the glove box with a built-in Faraday cage includes the following steps: The static charge of the sample ball at the first drop height sampling point is taken as the initial surface charge of the sample ball. The static charge of the sample ball at the second drop height sampling point is taken as the charge of the sample ball after triboelectric charging. The difference between the static charge of the sample ball at the second drop height sampling point and the static charge of the sample ball at the first drop height sampling point is calculated to obtain the amount of charge added to the surface of the sample ball during the drop between the first and second sampling points.

[0013] The second aspect of this application provides a gas-solid triboelectric testing device for a moving object, comprising a glove box with a built-in Faraday cage, a drop height control mechanism, a two-stage pressure reducing valve, a synthetic air bottle, a coaxial shielded cable, an air passage pipe, a vacuum pump, a BNC high-vacuum sealed adapter, a sample ball, a lower through-type Faraday cylinder, an electrometer for acquiring the electrostatic charge signal of the sample ball during its drop, a temperature and humidity sensor for acquiring the temperature and humidity signal inside the glove box with the built-in Faraday cage, a pressure sensor for acquiring the pressure signal inside the glove box with the built-in Faraday cage, a dust particle counter for acquiring the particle density of 0.3-10μm dust particles in the environment inside the glove box with the built-in Faraday cage, a ball receiving base, and a controller. The controller is connected to the vacuum pump, the dust particle counter, the temperature and humidity sensor, and the pressure sensor. A force sensor, an electrometer, and a drop height control mechanism are connected. The drop height control mechanism is installed inside a glove box with a built-in Faraday cage. The glove box with the built-in Faraday cage has a displacement hole and an adapter hole. A secondary pressure reducing valve is fixedly installed on the displacement hole. The input end of the secondary pressure reducing valve is connected to a synthetic air cylinder, and the output end of the secondary pressure reducing valve is connected to one end of an air supply pipe. The other end of the air supply pipe is connected to the air inlet of the glove box with the built-in Faraday cage. A vacuum pump is connected to the air outlet of the glove box with the built-in Faraday cage through the air supply pipe. A BNC high-vacuum sealed adapter is fixedly installed on the adapter hole. The drop height control mechanism is electrically connected to one end of the BNC high-vacuum sealed adapter through a coaxial shielded cable. The electrometer is electrically connected to the other end of the BNC high-vacuum sealed adapter through a coaxial shielded cable.

[0014] Furthermore, the drop height control mechanism includes a three-axis electric robotic arm, mechanical grippers, an upper through-type Faraday cylinder, a lower through-type Faraday cylinder, and a ball receiving base. The mechanical grippers are fixedly mounted on the top of the upper through-type Faraday cylinder, and the ball receiving base is fixedly mounted on the bottom of the lower through-type Faraday cylinder. The upper and lower through-type Faraday cylinders are fixedly mounted on the three-axis electric robotic arm. One end of a BNC high-vacuum sealed adapter is electrically connected to the upper and lower through-type Faraday cylinders via a coaxial shielded cable. By controlling the operation of the three-axis electric robotic arm, the upper through-type Faraday cylinder is displaced, thereby controlling the drop height of the sample ball.

[0015] The beneficial effects of this application are as follows: By constructing a triboelectric model of a sample sphere and gas, it is shown that when the ambient temperature is constant, the charge generated is jointly determined by the collision frequency between gas molecules and the solid surface and the effective friction area, wherein the collision frequency is affected by the object's moving speed and the ambient air pressure. By controlling the influence of the sample sphere's velocity, effective friction area, and ambient air pressure, triboelectric experiments are conducted, demonstrating the degree to which these influencing factors affect the increase in charge caused by gas-solid triboelectric charging. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the collision between the sample sphere and gas molecules during the falling process of the present invention; Figure 2 This is a schematic diagram of the static charge signal of the sample microspheres at different drop heights according to the present invention; Figure 3 This is a schematic diagram of the structure of a gas-solid triboelectric testing device for a moving object according to the present invention.

[0018] Attached image labels: 1- Glove box with built-in Faraday cage, 2- Three-axis electric robotic arm, 3- Secondary pressure reducing valve, 4- Synthetic air bottle, 5- Coaxial shielded cable, 6- Air pipeline, 7- Vacuum pump, 8- BNC high vacuum sealed adapter, 9- Electrometer, 10- Mechanical gripper, 11- Upper through-type Faraday cylinder, 12- Sample ball, 13- Aluminum profile, 14- Slide table, 15- Lower through-type Faraday cylinder, 16- Insulating tape, 17- Ball receiving base. Detailed Implementation

[0019] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1 A method for testing the gas-solid triboelectricity of a moving object, comprising the following steps: S101. Construct a model of triboelectric charging of a sample ball and gas during the free fall of the sample ball inside a glove box with a built-in Faraday cage. like Figure 1 As shown, according to the kinetic theory of gases, gas molecules can be considered as rigid spheres, and the collision between the sample sphere and gas molecules can be equivalent to a perfectly elastic collision. A schematic diagram of the sample sphere falling and interacting with gas molecules is shown below. Figure 2 As shown, the surface area of ​​a micro-element on the surface of the sample sphere can be selected. Its normal direction is along the negative Z-axis, calculated using... Indicated Within a time period, encounter In terms of area, speed is The number of molecules within a certain range can be considered as the number of molecules located at the level of […]. as the base, with With axis, Within a tall cylinder, the velocity is The number of molecules within the range, assuming the volume of the column formed by the free fall of the sample spheres is... ,get ,in Given the Maxwell velocity distribution, according to Maxwell's law of velocity distribution, gas molecules move freely in space. When the sample sphere is stationary... Gas molecules in the range of 0 to ∞ can collide with the sample sphere. Since the sample sphere has velocity and its direction of motion is opposite to that of the gas molecules, this allows... In - Gas molecules in the range of 0 collide with the surface of the sample sphere ( (The velocity of the sample ball).

[0022] The steps for constructing a model of triboelectric charging of a sample ball with gas during free fall within a glove box with a built-in Faraday cage are as follows: Let the area of ​​a surface element on the surface of the sample sphere be... Construct sample microspheres in a column with a volume of The height of the column is The molecular number differential equation for the collisions with gas molecules during a free fall in space is expressed as follows: ; in, This is the differential of the number of molecules that collide with gas molecules during the free fall of the sample sphere within a glove box containing a built-in Faraday cage. For Maxwell's velocity distribution, Let be the velocity of the sample ball on the Z-axis. The derivative of the velocity of the sample ball along the XYZ axes; By performing velocity integral calculations, the velocity of the sample ball per unit time is obtained. Inside and per unit area The number of gas molecules that collide (That is, the collision frequency between the sample sphere and gas molecules), its expression is as follows: ; in, The collision frequency between the sample sphere and gas molecules. Mass of a single gas molecule Let be the absolute temperature of the gas. For Boltzmann constant, This refers to gas pressure. Let Avogadro's constant be 1. Let be the ideal gas constant. The velocity of the sample ball; The equation for the velocity of the sample ball as a function of the drop height during free fall is constructed as follows: ; ; in, For the velocity of the sample ball, The value is the air resistance coefficient of the sample sphere. When the surface of the sample sphere is relatively smooth and the velocity is less than 30 m / s, it can be taken as 0.5. The mass of the sample pellet. It is the acceleration due to gravity. The molar mass of air, Let be the cross-sectional area of ​​the small sphere. The drop height of the sample ball; By introducing average charge transfer The amount of electricity generated by friction between the surface of the small ball and a single gas molecule is used to represent the amount of electricity generated by friction between the small ball and the surface of the small ball. Therefore, the sample ball has a drop time of [time value missing]. Effective surface area The amount of charge transferred by collision with gas molecules As shown in the following expression: ; ; in, This represents the amount of charge transferred during the collision between the sample microsphere and gas molecules. This is the average charge transfer amount. For ambient air pressure, The absolute temperature of the gas. For effective surface area, For the time of the fall, Let Avogadro's constant be 1. Let be the ideal gas constant. This is the charge transfer coefficient during collisions between the spherical material and gas molecules. For the velocity of the sample ball, This is the Boltzmann constant. When the air composition remains constant... The value depends on the electron gain and loss capability of the sample microsphere material. For charge transfer occurring during collisions between gas molecules and the microsphere surface, the smallest unit of transfer is one electron, i.e., 1.6 × 10⁻⁶. -19 C.

[0023] S102. Perform standardized pretreatment on the sample microspheres to remove residual charge on their surface; Standardized pretreatment of sample spheres is crucial for ensuring experimental accuracy. Any contaminants or residual charges on the surface of the sample spheres can severely affect the triboelectric measurement results. This invention effectively removes organic contaminants and inorganic impurities (surface stains) from the surface of the sample spheres by performing a primary cleaning treatment with anhydrous ethanol. After the primary cleaning, the sample spheres are purged with high-purity nitrogen to remove residual impurities and prevent them from participating in the charge transfer process during the experiment. After the high-purity nitrogen purging, the sample spheres are then cleaned a second time with anhydrous ethanol. The polarity of ethanol molecules neutralizes or removes the surface charge (eliminating residual surface charge), ensuring that the sample spheres are electrically neutral before the experiment.

[0024] The standardization pretreatment of the sample microspheres to remove residual surface charge includes the following steps: Anhydrous ethanol was used to clean the sample pellets once to remove surface contaminants. High-purity nitrogen gas was used to purge the sample pellets to remove residual impurities; Anhydrous ethanol was used to perform a secondary cleaning treatment on the sample microspheres to eliminate residual surface charge. The processed sample pellets are placed on the sample stage for later use to avoid recontamination.

[0025] S103. Replace the air in the glove box with the built-in Faraday cage until the air pressure and environmental parameters in the glove box with the built-in Faraday cage meet the test requirements, and determine the diameter range and drop height of the sample ball. By selecting a specific drop height for the sample sphere within a glove box containing a built-in Faraday cage, the charge transfer coefficient of gas-solid triboelectric charging can be fitted, and the influence of drop height on the gas-solid triboelectric charging model can be verified (verification of the relationship between object velocity and gas-solid triboelectric charge). Ensuring the dust particle number density in the test environment within the glove box meets the experimental conditions, and selecting a range for the diameter of the sample sphere, the influence factor in the theoretical model—effective surface area (i.e., the relationship between effective surface area and gas-solid triboelectric charge)—can be verified by adjusting the diameter of the sample sphere. Selecting a range for adjusting the ambient air pressure allows for verification of the influence factor in the theoretical model—ambient air pressure (i.e., the relationship between gas molecule number density and gas-solid triboelectric charge)—by adjusting the ambient air pressure.

[0026] The air inside the glove box with the built-in Faraday cage is replaced until the air pressure and environmental parameters inside the glove box with the built-in Faraday cage meet the test requirements, and the diameter range and drop height of the sample ball are determined, including the following steps: During the process of maintaining negative pressure by evacuating the air from the glove box containing the Faraday cage or replacing it with synthetic air, the dust particle density signal inside the glove box of the Faraday cage is continuously acquired. The experiment can only begin when the dust particle number density inside the glove box of the Faraday cage is 0.3um < 1000 particles / L, 0.5um < 200 particles / L, 1um < 15 particles / L, 2.5um < 2 particles / L, 5um < 0 particles / L, and 10um < 0 particles / L. The ambient air pressure range inside the glove box with the built-in Faraday cage is controlled to be 0.5 atm-1 atm; The diameter of the sample balls was selected to be in the range of 12mm-30mm in order to control the effect of their effective frictional surface area on the charge generated. The drop height of the sample balls inside the glove box with the built-in Faraday cage is controlled within the range of 0.1m-1.5m.

[0027] S104. Based on the triboelectric model of the sample ball and gas, the static charge signal of the sample ball is obtained during the free fall of the sample ball, and the static charge signal is filtered to read the static charge of the sample ball at different fall heights. During the free fall, the sample ball accumulates charge through friction and collision with gas molecules along its path. The electrostatic charge signal of the sample ball during the free fall is acquired in real time by an electrometer. The electrostatic charge signal of the sample ball is filtered, and the peak value of the signal at different fall heights is read to reduce the error caused by the filtering process.

[0028] Based on the triboelectric model of the sample ball and gas, the electrostatic charge signal of the sample ball is obtained during the free fall of the sample ball, and the electrostatic charge signal is filtered to read the amount of electrostatic charge of the sample ball at different drop heights. The steps include: Electrostatic charge signal acquisition points at different heights were set up to obtain the electrostatic charge signal of the sample ball during the free fall of the sample ball; Discrete wavelet transform was performed on the electrostatic charge signal of the sample spheres to determine the main frequency range of the noise. By using the different heights of the electrostatic charge signal acquisition points, the signal frequency range of the sample ball when passing through the electrostatic charge signal acquisition points at different heights was determined. The electrostatic charge signal of the sample microspheres is filtered. The signal peak value of the sample ball at different drop heights is read to obtain the static charge of the sample ball at different drop heights.

[0029] S105. Based on the static charge of the sample ball at different drop heights, determine the amount of charge added to the sample ball during the free fall of the glove box with a built-in Faraday cage. like Figure 2 As shown, Figure 2 (a) is the original signal without filtering. Figure 2 (b) is the filtered signal, showing the static charge of the sample pellet at the first drop height. The static charge of the sample microsphere at the second drop height was During its free fall, the sample ball passed through the first drop height sampling point and the second drop height sampling point in sequence. The electrostatic charge of the sample ball at the second drop height was measured. The static charge of the sample microsphere at the first drop height The difference between the two peak signals is obtained by performing a subtraction operation. Thus, the amount of charge added to the sample ball during its free fall within the glove box containing the Faraday cage is obtained.

[0030] The determination of the charge gain of the sample ball during free fall in a glove box with a built-in Faraday cage, based on the static charge of the sample ball at different drop heights, includes the following steps: The static charge of the sample ball at the first drop height sampling point is taken as the initial surface charge of the sample ball. The static charge of the sample ball at the second drop height sampling point is taken as the charge of the sample ball after triboelectric charging. The difference between the static charge of the sample ball at the second drop height sampling point and the static charge of the sample ball at the first drop height sampling point is calculated to obtain the amount of charge added to the surface of the sample ball during the drop between the first and second sampling points.

[0031] Example 2 The above is a method for testing the gas-solid triboelectricity of a moving object according to the embodiments of this application. The following is a system for testing the gas-solid triboelectricity of a moving object according to the embodiments of this application.

[0032] like Figure 3 As shown, a gas-solid triboelectric charging test device for a moving object includes: The system includes a glove box with a built-in Faraday cage, a drop height control mechanism, a two-stage pressure reducing valve, a synthetic air cylinder, a coaxial shielded cable, an air duct, a vacuum pump, a BNC high-vacuum sealed adapter, sample spheres, a bottom-through Faraday cylinder, an electrometer for acquiring the electrostatic charge signal during the sample sphere's fall, a temperature and humidity sensor for acquiring the temperature and humidity signals inside the glove box with the built-in Faraday cage, a pressure sensor for acquiring the pressure signal inside the glove box with the built-in Faraday cage, a dust particle counter for acquiring the particle density of 0.3-10μm dust particles in the environment inside the glove box with the built-in Faraday cage, a sphere receiving base, and a controller. The controller is connected to the vacuum pump, dust particle counter, temperature and humidity sensor, pressure sensor, and electrometer, respectively. It is connected to the drop height control mechanism, which is installed inside the glove box with a built-in Faraday cage. The glove box with a built-in Faraday cage has a displacement hole and an adapter hole. The secondary pressure reducing valve is fixedly installed on the displacement hole. The input end of the secondary pressure reducing valve is connected to the synthetic air cylinder, and the output end of the secondary pressure reducing valve is connected to one end of the air passage pipe. The other end of the air passage pipe is connected to the air inlet of the glove box with a built-in Faraday cage. The vacuum pump is connected to the air outlet of the glove box with a built-in Faraday cage through the air passage pipe. The BNC high vacuum sealed adapter is fixedly installed on the adapter hole. The drop height control mechanism is electrically connected to one end of the BNC high vacuum sealed adapter through a coaxial shielded cable. The electrometer (the electrometer can be a Keithley 6517B electrometer) is electrically connected to the other end of the BNC high vacuum sealed adapter through a coaxial shielded cable.

[0033] When placing the sample pellets on the drop height control mechanism, the test personnel opened the sealed door of the glove box containing the built-in Faraday cage and placed the standardized pre-treated sample pellets on the drop height control mechanism. After placing the sample pellets on the drop height control mechanism and closing the sealed door of the glove box containing the built-in Faraday cage, the air inside the glove box containing the built-in Faraday cage was replaced by a vacuum pump in conjunction with an air supply pipe, and a synthetic air bottle in conjunction with a secondary pressure reducing valve and an air supply pipe to control the density of dust particles, air humidity, ambient temperature, and air pressure.

[0034] The drop height control mechanism includes a three-axis electric robotic arm, mechanical grippers, an upper through-type Faraday cylinder, a lower through-type Faraday cylinder, and a ball receiving base. The mechanical grippers are fixedly mounted on the top of the upper through-type Faraday cylinder, and the ball receiving base is fixedly mounted on the bottom of the lower through-type Faraday cylinder. The upper and lower through-type Faraday cylinders are fixedly mounted on the three-axis electric robotic arm. One end of a BNC high-vacuum sealed adapter is electrically connected to the upper and lower through-type Faraday cylinders via a coaxial shielded cable. By controlling the operation of the three-axis electric robotic arm, the upper through-type Faraday cylinder is displaced, thereby controlling the drop height of the sample ball. Optionally, the ball receiving base is fixedly mounted on the bottom of the lower through-type Faraday cylinder with insulating tape, the mechanical grippers are fixedly mounted on the top of the upper through-type Faraday cylinder with an aluminum profile, and the upper through-type Faraday cylinder is fixedly mounted on the three-axis electric robotic arm via a slide table. During the controlled drop test of the sample ball, a three-axis electric robotic arm is used to align the through holes of the upper and lower through-type Faraday cylinders in the plumb line. Then, the mechanical grippers release the sample ball, causing it to fall sequentially from the through holes of the upper and lower through-type Faraday cylinders to the ball receiving base. In this invention's test, the structural parameters of the upper and lower through-type Faraday cylinders are as follows: inner cylinder diameter 63.5 mm, height 80 mm; outer cylinder inner diameter 75.8 mm, height 90 mm, wall thickness 0.8 mm. The top and bottom covers of the cylinders have 50 mm diameter through holes to ensure the sample ball can completely enter the cylinder.

[0035] During the experiment, all small balls underwent a standardized pretreatment process: anhydrous ethanol was used to clean away surface stains, high-purity nitrogen was used to purge away residual impurities, and anhydrous ethanol was used twice before the test to eliminate residual surface charge. The treated sample balls were placed on the sample stage for later use. Using a grounded clamp and gloves through the glove box, the sample balls were selected from the sample stage and placed in the mechanical gripper. Power was supplied to the three-axis electric robotic arm and the mechanical gripper via the robotic arm power supply. The controller aligns the through holes of the upper and lower through-hole Faraday cages and precisely adjusts the drop height. The temperature, humidity, and air pressure inside the glove box with its built-in Faraday cage were controlled to meet the experimental requirements. After the Keithley 6517B electrometer was activated to record data, the controller output a command to release the sample ball from the mechanical gripper, allowing it to fall through the upper and lower through-hole Faraday cages. The upper through-type Faraday cylinder is used as the first drop height acquisition point for the electrostatic charge signal of the sample ball, and the lower through-type Faraday cylinder is used as the second drop height acquisition point. When the charged sample ball enters the Faraday cylinder, an electrostatic charge is generated on the inner wall of the Faraday cylinder due to electrostatic induction. The Keithley 6517B electrometer measures the induced charge to indirectly obtain the electrostatic charge of the sample ball. By continuously measuring the charge difference of the ball as it passes through the two cylinders, the dynamic measurement of the gas-solid friction charge is achieved, and the data obtained by the Keithley 6517B electrometer is observed and stored. By repeating the above process, this device can measure the gas-solid friction charge of a moving object under the influence of three factors: drop height (movement speed), sample ball diameter (effective friction area), and ambient air pressure (gas molecule number density).

[0036] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0037] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for testing the gas-solid triboelectricity of a moving object, characterized in that, Includes the following steps: S101. Construct a model of triboelectric charging of a sample ball and gas during the free fall of the sample ball inside a glove box with a built-in Faraday cage. S102. Perform standardized pretreatment on the sample microspheres to remove residual charge on their surface; S103. Replace the air in the glove box with the built-in Faraday cage until the air pressure and environmental parameters in the glove box with the built-in Faraday cage meet the test requirements, and determine the diameter range and drop height of the sample ball. S104. Based on the triboelectric model of the sample ball and gas, the static charge signal of the sample ball is obtained during the free fall of the sample ball, and the static charge signal is filtered to read the static charge of the sample ball at different fall heights. S105. Based on the static charge of the sample ball at different drop heights, determine the amount of charge added to the sample ball during the free fall of the glove box with a built-in Faraday cage. Among them, a frictional electrification model of sample spheres and gas was constructed based on Maxwell's velocity distribution law.

2. The method for testing the gas-solid triboelectric charging of a moving object according to claim 1, characterized in that, Step S101 includes the following steps: Let the area of ​​a surface element on the surface of the sample sphere be... Construct sample microspheres in a column with a volume of The height of the column is The molecular number differential equation for the collisions with gas molecules during a free fall in space is expressed as follows: ； in, This is the differential of the number of molecules that collide with gas molecules during the free fall of the sample sphere within a glove box containing a built-in Faraday cage. For Maxwell's velocity distribution, Let be the velocity of the sample ball on the Z-axis. The derivative of the velocity of the sample ball along the XYZ axes; By performing velocity integral calculations, the velocity of the sample ball per unit time is obtained. Inside and per unit area The number of gas molecules that collide Its expression is as follows: ； in, The collision frequency between the sample sphere and gas molecules. Mass of a single gas molecule Let be the absolute temperature of the gas. For Boltzmann constant, This refers to gas pressure. Let Avogadro's constant be 1. Let be the ideal gas constant. The velocity of the sample ball; The equation for the velocity of the sample ball as a function of the drop height during free fall is constructed as follows: ； ； in, For the velocity of the sample ball, The air resistance coefficient of the sample sphere, The mass of the sample pellet. It is the acceleration due to gravity. The molar mass of air, Let be the cross-sectional area of ​​the small sphere. The drop height of the sample ball; By introducing average charge transfer The amount of electricity generated by friction between the surface of the small ball and a single gas molecule is used to represent the amount of electricity generated by friction between the small ball and the surface of the small ball. Therefore, the sample ball has a drop time of [time value missing]. Effective surface area The amount of charge transferred by collision with gas molecules As shown in the following expression: ； ； in, This represents the amount of charge transferred during the collision between the sample microsphere and gas molecules. This is the average charge transfer amount. For ambient air pressure, The absolute temperature of the gas. For effective surface area, For the time of the fall, Let Avogadro's constant be 1. Let be the ideal gas constant. This is the charge transfer coefficient during collisions between the spherical material and gas molecules. For the velocity of the sample ball, It is the Boltzmann constant.

3. The method for testing the gas-solid triboelectric charging of a moving object according to claim 1, characterized in that, Step S102 includes the following steps: Anhydrous ethanol was used to clean the sample pellets once to remove surface contaminants. High-purity nitrogen gas was used to purge the sample pellets to remove residual impurities; Anhydrous ethanol was used to perform a secondary cleaning treatment on the sample microspheres to eliminate residual surface charge. The processed sample pellets are placed on the sample stage for later use to avoid recontamination.

4. The method for testing the gas-solid triboelectric charging of a moving object according to claim 1, characterized in that, Step S103 includes the following steps: During the process of maintaining negative pressure by evacuating the air from the glove box with the built-in Faraday cage or replacing it with synthetic air, the dust particle density signal in the glove box with the built-in Faraday cage is continuously acquired. The experiment can only begin when the dust particle number density in the glove box with the built-in Faraday cage is 0.3um < 1000 particles / L, 0.5um < 200 particles / L, 1um < 15 particles / L, 2.5um < 2 particles / L, 5um < 0 particles / L, and 10um < 0 particles / L. The ambient air pressure range inside the glove box with the built-in Faraday cage is controlled to be 0.5 atm-1 atm; The diameter of the sample balls was selected to be in the range of 12mm-30mm in order to control the effect of their effective frictional surface area on the charge generated. The drop height of the sample balls inside the glove box with the built-in Faraday cage is controlled within the range of 0.1m-1.5m.

5. The method for testing the gas-solid triboelectric charging of a moving object according to claim 1, characterized in that, Step S104 includes the following steps: Electrostatic charge signal acquisition points at different heights were set up to obtain the electrostatic charge signal of the sample ball during the free fall of the sample ball; Discrete wavelet transform was performed on the electrostatic charge signal of the sample spheres to determine the main frequency range of the noise. By using the different heights of the electrostatic charge signal acquisition points, the signal frequency range of the sample ball when passing through the electrostatic charge signal acquisition points at different heights was determined. The electrostatic charge signal of the sample microspheres is filtered. The signal peak value of the sample ball at different drop heights is read to obtain the static charge of the sample ball at different drop heights.

6. The method for testing the gas-solid triboelectric charging of a moving object according to claim 1, characterized in that, Step S105 includes the following steps: The static charge of the sample ball at the first drop height sampling point is taken as the initial surface charge of the sample ball. The static charge of the sample ball at the second drop height sampling point is taken as the charge of the sample ball after triboelectric charging. The difference between the static charge of the sample ball at the second drop height sampling point and the static charge of the sample ball at the first drop height sampling point is calculated to obtain the amount of charge added to the surface of the sample ball during the drop between the first and second sampling points.

7. A device for testing the triboelectricity of a moving object, used to implement the triboelectricity testing method for a moving object as described in any one of claims 1-6, characterized in that, The system includes a glove box with a built-in Faraday cage, a drop height control mechanism, a two-stage pressure reducing valve, a synthetic air cylinder, a coaxial shielded cable, an air duct, a vacuum pump, a BNC high-vacuum sealed adapter, sample spheres, a lower-through Faraday cylinder, an electrometer for acquiring the electrostatic charge signal during the sample sphere's fall, a temperature and humidity sensor for acquiring the temperature and humidity signals inside the glove box with the built-in Faraday cage, a pressure sensor for acquiring the pressure signal inside the glove box with the built-in Faraday cage, a dust particle counter for acquiring the particle density of 0.3-10μm dust particles in the environment inside the glove box with the built-in Faraday cage, a sphere receiving base, and a controller. The controller is connected to the vacuum pump, dust particle counter, temperature and humidity sensor, pressure sensor, electrometer, and drop height control mechanism, respectively. The drop height control mechanism is installed inside the glove box of the built-in Faraday cage. The glove box of the built-in Faraday cage is provided with a displacement hole and an adapter hole. The secondary pressure reducing valve is fixedly installed on the displacement hole. The input end of the secondary pressure reducing valve is connected to the synthetic air cylinder. The output end of the secondary pressure reducing valve is connected to one end of the air passage pipe. The other end of the air passage pipe is connected to the air inlet of the glove box of the built-in Faraday cage. The vacuum pump is connected to the air outlet of the glove box of the built-in Faraday cage through the air passage pipe. The BNC high vacuum sealed adapter is fixedly installed on the adapter hole. The drop height control mechanism is electrically connected to one end of the BNC high vacuum sealed adapter through a coaxial shielded cable. The electrometer is electrically connected to the other end of the BNC high vacuum sealed adapter through a coaxial shielded cable.

8. The gas-solid triboelectric testing device for moving objects according to claim 7, characterized in that, The drop height control mechanism includes a three-axis electric robotic arm, a mechanical gripper, an upper through-type Faraday cylinder, a lower through-type Faraday cylinder, and a ball receiving base. The mechanical gripper is fixedly installed at the top of the upper through-type Faraday cylinder, and the ball receiving base is fixedly installed at the bottom of the lower through-type Faraday cylinder. The upper and lower through-type Faraday cylinders are fixedly installed on the three-axis electric robotic arm. One end of a BNC high-vacuum sealed adapter is electrically connected to the upper and lower through-type Faraday cylinders via a coaxial shielded cable. By controlling the operation of the three-axis electric robotic arm, the upper through-type Faraday cylinder is displaced, thereby controlling the drop height of the sample ball.

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