Test method, system and equipment for measuring quantity of electric charges carried by moving liquid drops and medium

Abstract

The invention discloses a test method, system, equipment and medium for measuring the quantity of electric charges carried by moving droplets, and the method comprises the following steps: controlling the dropping of liquid to generate a single droplet with a stable volume, and obtaining an initial droplet sample; applying an electric field with known intensity to obtain a dynamic process of stress movement of the liquid drops in the electric field; performing droplet centroid tracking and motion curve fitting on the calibrated image sequence to obtain a speed-time relation and acceleration of the droplet in the electric field direction; the resultant force of the liquid drops in the electric field direction is substituted into the Newton second law to obtain a stress balance equation about the charge quantity of the liquid drops; and solving the stress balance equation, calculating to obtain a single droplet charge quantity, and carrying out statistical analysis through multiple experiments to obtain a statistical numerical result of the charge quantity carried by the droplet under the conditions of specific low temperature and electric field. According to the invention, the physical accuracy and reliability of charge quantity inversion are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of charge measurement technology, and in particular to a method, system, device and medium for measuring the charge carried by a moving droplet. Background Technology

[0002] In various engineering fields such as aerospace, high-voltage power transmission, inkjet printing, and microfluidics, the behavior of droplets in electric fields has always been a key research subject. Especially in applications such as electro-atomization, electrostatic spraying, electrostatic dust removal, and insulation system design, the motion characteristics of droplets under the influence of an applied electric field and the amount of charge they carry directly affect the system's efficiency, safety, and precision control. However, the charging mechanism of droplets in an electric field is complex, and their charge is affected by multiple factors such as droplet size, ambient humidity, electric field strength, and droplet material, making accurate measurement a significant challenge. Currently used methods suffer from operational complexity, poor applicability, or limited accuracy, making it difficult to meet the demands of modern engineering for high-sensitivity, high-resolution measurements.

[0003] Therefore, developing an efficient, reliable method for measuring the charge of droplets applicable to various operating conditions is of great significance for improving the design level and operational stability of related engineering systems. Especially in low-temperature environments, understanding the charge information of droplets not only helps in a deeper understanding of their motion patterns but also provides data support for engineering safety monitoring and risk early warning. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a test method, system, device and medium for measuring the charge of moving droplets, which solves the problems of complex operation, poor applicability and limited accuracy of existing droplet charge measurement methods.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for measuring the charge carried by a moving droplet, comprising: The physical properties of the liquid to be tested are obtained, and a standardized experimental system is obtained through debugging and calibration. Based on a standardized experimental system, a single droplet with stable volume is generated by controlling the liquid droplet flow, thus obtaining an initial droplet sample. Based on the initial droplet sample, the dynamic process of the droplet moving under the force of the electric field is obtained by applying an electric field of known strength; Based on the dynamic process, droplet centroid tracking and motion curve fitting are performed on the calibrated image sequence to obtain the velocity-time relationship and acceleration of the droplet in the electric field direction. Based on the acceleration, and combined with the droplet's mass, electric field strength, and fluid resistance parameters, by substituting the net force on the droplet in the electric field direction into Newton's second law, the force balance equation for the droplet's charge is obtained. Solve the force balance equation to calculate the charge of a single droplet, and conduct statistical analysis through multiple experiments to obtain statistical numerical results of the charge carried by the droplet under specific low temperature and electric field conditions.

[0007] In a preferred embodiment of the experimental method for measuring the charge of a moving droplet according to the present invention, the step of obtaining the acceleration of the droplet in the electric field direction includes: The motion images of a droplet in a known electric field are acquired using a non-contact motion detection device, and the displacement-time data of the droplet's centroid are determined based on the image sequence. The velocity-time relationship of the droplet in the direction of the electric field is calculated based on the displacement-time data, and the acceleration of the droplet is obtained by differentiating the velocity-time relationship.

[0008] The beneficial effects of this preferred technical solution are that, through non-contact motion detection and precise extraction of centroid displacement-time data, combined with differential processing of velocity-time relationship, high-precision and interference-free measurement of droplet acceleration is achieved, effectively avoiding disturbance of droplet motion state by contact measurement, and improving the accuracy and reliability of charge inversion results.

[0009] As a preferred embodiment of the experimental method for measuring the charge of a moving droplet according to the present invention, wherein obtaining the force balance equation regarding the charge of the droplet includes: The air resistance experienced by the droplet in the direction of the electric field is expressed as a nonlinear resistance term that is proportional to the square of the droplet's velocity. The electric force on the droplet can be expressed as the product of the charge to be determined and the known electric field strength. According to Newton's second law, the net force on a droplet can be expressed as the product of the droplet's mass and its acceleration. Based on the relationship between electric force, air resistance, and resultant force, a force balance equation is established that includes the unknown charge, measured acceleration, real-time velocity, droplet mass, electric field strength, and fluid resistance coefficient.

[0010] The beneficial effects of this preferred technical solution are that by establishing a complete force balance equation including electric force, air resistance (the square of the velocity term), and inertial force, accurate modeling and physically interpretable solution of droplet charge are achieved under the condition of considering real fluid resistance characteristics, which significantly improves the accuracy and theoretical reliability of charge inversion.

[0011] As a preferred embodiment of the experimental method for measuring the charge of a moving droplet according to the present invention, the step of obtaining the charge of a single droplet includes: The force equilibrium equations are solved algebraically to separate the expression for the charge quantity to be determined. By substituting the measured acceleration value, the velocity value at the corresponding moment, the known droplet mass, the electric field strength, and the preset fluid resistance coefficient into the solved expression, the charge of a single droplet is calculated.

[0012] As a preferred embodiment of the experimental method for measuring the charge of a moving droplet according to the present invention, the step of measuring the charge under specific low temperature and electric field conditions includes: The droplet generation system, electric field generation system, and image acquisition system are all placed inside a low-temperature test chamber. Pre-cool the liquid entering the low-temperature test chamber; The ambient temperature of the low-temperature test chamber is controlled to be within the temperature range above and close to the freezing point. A temperature buffer zone is set between the droplet generation system outlet and the electrode plate; The high-speed camera and lens of the image acquisition system are provided with an anti-condensation layer on their outer surfaces.

[0013] As a preferred embodiment of the experimental method for measuring the charge of moving droplets according to the present invention, the standardized experimental system includes a droplet generation system, an electric field generation system, an environmental control system, an image acquisition system, and a data analysis system. The electric field generating system and the environmental control system are connected to the same grounding terminal via a conductor; The image acquisition system includes a high-speed camera, a macro lens, an adjustable lifting platform, and a backlight source; The adjustable lifting platform is fixedly connected to the high-speed camera, allowing for adjustment of the high-speed camera's spatial height. The relative positions of the droplet generation system, the electric field generation system, and the image acquisition system are geometrically calibrated. The droplet moves horizontally within the electric field region generated by the electric field generating system, and the trajectory of the droplet is located at the center of the field of view of the image acquisition system; The backlight source is located behind the electrode plate of the electric field generating system, and the light emission axis of the backlight source coincides with the optical axis of the high-speed camera. The data analysis system is connected to the image acquisition system, receives image signals, and performs a data processing flow for calculating charge. The image acquisition system also includes a calibration plate for spatial calibration; The image acquisition system and the electric field generation system are connected by a synchronization signal for time synchronization.

[0014] As a preferred embodiment of the test method for measuring the charge of a moving droplet according to the present invention, the calibration plate is disposed in the plane where the droplet's movement path is located, and is coplanar with the plane of the droplet's movement or located in the same imaging focal plane. Based on the image of the calibration plate, a mapping relationship between pixel coordinates and physical coordinates is established; The synchronization signal is connected as a synchronization signal line, which transmits the trigger signal of the power controller of the electric field generation system to the image acquisition system to start the image acquisition process; Based on the trigger signal, the timestamp corresponding to each frame of the image during the droplet's movement is determined.

[0015] Secondly, the present invention provides a test system for measuring the charge carried by a moving droplet, comprising: The system calibration and preparation module is used to acquire the physical properties of the liquid to be tested, and through debugging and calibration, a standardized experimental system is obtained; The droplet generation and control module is used to generate a single droplet with stable volume by controlling the liquid droplet discharge based on a standardized experimental system, thereby obtaining an initial droplet sample. The electric field application and dynamic excitation module is used to obtain the dynamic process of the droplet's motion under force in the electric field by applying an electric field of known intensity based on the initial droplet sample. The motion parameter extraction module is used to perform droplet centroid tracking and motion curve fitting on the calibrated image sequence based on the dynamic process, so as to obtain the velocity-time relationship and acceleration of the droplet in the electric field direction; The force modeling and equation construction module is used to obtain the force balance equation for the droplet charge by substituting the net force on the droplet in the electric field direction into Newton's second law based on the acceleration, combined with the mass, electric field strength and fluid resistance parameters of the droplet. The charge calculation and statistical output module is used to solve the force balance equation, calculate the charge of a single droplet, and perform statistical analysis through multiple experiments to obtain statistical numerical results of the charge carried by the droplet under specific low temperature and electric field conditions.

[0016] Thirdly, the present invention provides an electronic device, comprising: Memory, used to store programs; A processor is configured to execute the computer-executable instructions, which, when executed by the processor, implement the steps of the experimental method for measuring the charge carried by the moving droplet.

[0017] Fourthly, the present invention provides a computer-readable storage medium comprising: when the program is executed by a processor, the steps of implementing the experimental method for measuring the charge carried by the moving droplet.

[0018] The beneficial effects of this invention are as follows: By integrating the droplet generation system, electric field generation system, and image acquisition system into a low-temperature environment control device, and pre-regulating the temperature of the liquid entering the system while controlling the ambient temperature to be within a stable range above and close to the freezing point, this invention achieves stable droplet generation and movement under low-temperature conditions, effectively preventing the droplets from freezing due to overcooling during the dripping process and ensuring the feasibility of experiments in extreme environments. By setting a calibration plate on the droplet motion plane and establishing a mapping relationship between pixels and physical coordinates, combined with the synchronous signal connection between the image acquisition system and the electric field generation system, precise calibration of spatial displacement and high-precision time synchronization between image acquisition and electric field application are achieved, ensuring the accuracy of motion parameter extraction and the temporal consistency of dynamic process analysis. By using non-contact high-speed imaging combined with droplet centroid tracking and velocity-time curve differentiation to obtain acceleration, and constructing a force balance equation containing the velocity square term and air resistance based on Newton's second law for algebraic solution, this invention achieves non-interference, high-precision indirect measurement of droplet charge, significantly improving the reliability and physical interpretability of the measurement results. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments 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. Wherein: Figure 1 This is a schematic diagram of the basic process of a test method for measuring the charge of a moving droplet according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an apparatus for measuring the charge of a moving droplet, as provided in one embodiment of the present invention. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0021] Example 1, referring to Figure 1 As an embodiment of the present invention, a test method for measuring the charge carried by a moving droplet is provided, comprising: S100: Obtain the physical properties of the liquid to be tested, and obtain a standardized experimental system through debugging and calibration; S200: Based on a standardized experimental system, by controlling the liquid droplet, a single droplet with stable volume is generated to obtain an initial droplet sample; S300: Based on the initial droplet sample, by applying an electric field of known strength, the dynamic process of the droplet moving under force in the electric field is obtained; S400: Based on the dynamic process, droplet centroid tracking and motion curve fitting are performed on the calibrated image sequence to obtain the velocity-time relationship and acceleration of the droplet in the electric field direction; S500: Based on the acceleration, combined with the droplet's mass, electric field strength, and fluid resistance parameters, by substituting the net force on the droplet in the electric field direction into Newton's second law, the force balance equation for the droplet's charge is obtained. S600: Solve the force balance equation to calculate the charge of a single droplet, and conduct statistical analysis through multiple experiments to obtain statistical numerical results of the charge carried by the droplet under specific low temperature and electric field conditions.

[0022] It should be noted that existing methods for measuring the charge of droplets face multiple challenges in practical operation. These include: many methods rely on contact probes or electrodes to directly collect the charge, which easily interferes with the natural motion of the droplets, leading to measurement distortion; secondly, measurement accuracy is easily affected by environmental factors (such as temperature, humidity, and airflow), especially under complex conditions such as low temperature and high humidity, where droplets are prone to freezing or evaporation, resulting in signal interruption or unreliable data; traditional methods often struggle to achieve real-time, dynamic tracking of individual moving droplets, lacking the ability to accurately acquire key motion parameters such as droplet velocity and acceleration; existing technologies have extremely high requirements for the uniformity of the electric field distribution and the stability of droplet generation, resulting in complex system debugging, poor repeatability, and most methods do not fully consider the influence of nonlinear forces such as air resistance, leading to oversimplification of the charge inversion model and insufficient physical basis; and the lack of effective spatiotemporal synchronization and calibration mechanisms makes it difficult to ensure temporal consistency and spatial accuracy between image acquisition, electric field application, and data analysis, limiting the measurement resolution and reliability.

[0023] Therefore, addressing the issues of complex operation, poor applicability, and limited accuracy in existing droplet charge measurement methods, this paper proposes a method that integrates droplet generation, electric field application, cryogenic control, and high-speed imaging systems through steps S100-S600. This method, combined with spatiotemporal synchronous calibration and centroid tracking technology, enables precise capture of the dynamic motion of droplets in an electric field. Furthermore, a force balance equation incorporating air resistance with a velocity square term is constructed and solved, effectively improving the physical accuracy and reliability of charge inversion. Example 2, refer to Figure 2 As an embodiment of the present invention, based on the previous embodiment, a method for measuring the charge of a moving droplet is provided, comprising: In this embodiment of the application, the standardized experimental system in step S100 includes a droplet generation system, an electric field generation system, an environmental control system, an image acquisition system, and a data analysis system; The electric field generation system and the environmental control system are connected to the same grounding terminal via a conductor. The image acquisition system includes a high-speed camera, a macro lens, an adjustable lifting platform, and a backlight source; The adjustable lifting platform is fixedly connected to the high-speed camera, allowing for adjustment of the camera's height. The relative positions of the droplet generation system, the electric field generation system, and the image acquisition system are geometrically calibrated. The droplet moves horizontally within the electric field region generated by the electric field generating system, and the trajectory of the droplet is located at the center of the field of view of the image acquisition system; The backlight source is located behind the electrode plate of the electric field generating system, and the light emission axis of the backlight source coincides with the optical axis of the high-speed camera. The data analysis system connects to the image acquisition system, receives image signals, and performs data processing procedures to calculate charge. The image acquisition system also includes a calibration plate for spatial calibration; A synchronization signal connection for time synchronization is set between the image acquisition system and the electric field generation system.

[0024] In the embodiments of this application, such as Figure 2 As shown, the "low-temperature test chamber or outdoor natural conditions (windproof)" indicated by the blue box is the environmental control system, used to achieve a specific temperature environment; its internal "injection pump + syringe" constitutes the droplet generation system, which generates stable droplets by precisely controlling the liquid droplet output; the "electrode" and its connected "high-voltage power supply" together form the electric field generation system, applying a horizontal electric field of known intensity; the "cold light source" and "high-speed camera" constitute the image acquisition system, realizing non-contact high-speed imaging of the droplet movement process; the "thermometer and hygrometer" are used to monitor environmental parameters in real time to ensure that experimental conditions are controllable; and the "computer" serves as the data analysis system, receiving image signals and completing centroid tracking, motion fitting, and charge calculation. The overall layout clearly reflects the integrated relationship of each subsystem in three-dimensional space, jointly supporting the high-precision measurement process of droplet charge.

[0025] In this embodiment, the droplet generation system is used to generate droplets. A smart syringe pump (such as XMSP-1C) is used, connected to a precision micro-syringe, to control the droplet rate and volume. The syringe pump's stepper motor ensures a stable droplet volume. The water sample temperature is typically adjusted to 0-5°C to simulate a low-temperature environment and prevent premature freezing of the droplets due to overcooling.

[0026] In this embodiment, the electric field generating system provides a high-voltage / high-field-strength environment. A high-voltage DC power supply (such as TCM6002 or DW-N154-15ACJ5) provides the adjustable voltage, with a maximum output exceeding 50kV and ripple <5‰. The accompanying electrodes feature an adjustable-spacing design, with a spacing range of 0-10cm, and a droplet channel and viewing window are located at the center. The electrodes share a common ground with all equipment to prevent interference with the electric field distribution. An adjustable lifting platform is located at the bottom of the electrodes for fine-tuning the alignment of the droplet landing point with the focal point.

[0027] In this embodiment, the environmental control system is used to control temperature and humidity parameters. Experiments can be conducted outdoors in a natural low-temperature environment, or simulated indoors using a low-temperature chamber (such as RHP-408BT), with a minimum controllable temperature of -30°C. A temperature and humidity sensor (such as HL-NT3-D) is used to monitor and record the experimental environment in real time, ensuring that the experimental data matches the environmental conditions.

[0028] In this embodiment, the image acquisition system is used to record the trajectory of the droplet. The core acquisition device is a high-speed camera (such as the Phantom v2012), coupled with a 105mm macro lens (such as the Nikon 105mm F / 2.8 AF-S), enabling high-speed, high-resolution imaging. A cold light source is used for supplemental lighting to avoid localized heating caused by illumination. During the experimental shooting process, uniform backlighting and a scale are used for calibration to facilitate post-processing analysis. An adjustable lifting platform is provided at the bottom of the camera for fine-tuning the alignment of the droplet's landing point with the focus.

[0029] In this embodiment, experimental image data is imported into analysis software (such as Tracker), and the droplet's center of mass trajectory is tracked manually or automatically to export position-time data. The velocity is further fitted, the derivative is calculated to obtain the acceleration, and the charge is calculated using a formula. The analysis process supports batch processing, facilitating the processing of large sample experimental data.

[0030] When used together, the above experimental setup can stably achieve the function of measuring droplet charge. It features a compact structure, high control precision, and strong repeatability, making it suitable for scientific research and engineering testing scenarios.

[0031] In this embodiment, the entire experimental platform is debugged, including the wiring and grounding of the electric field device, the position correction of the droplet injection system, and the adjustment of the field of view of the high-speed camera. This ensures the stable operation of all experimental equipment. Clear scales or reference objects are set up in the shooting area to facilitate physical quantity conversion during image post-processing.

[0032] In this embodiment, step S200 employs a high-precision micro-injection pump connected to a needle to form a droplet generation system. By precisely controlling the pump's propulsion speed and pause time, droplet generation is achieved drop by drop. The droplets form and fall outside the electric field region, avoiding electric field polarization or premature charging during the generation process, thus ensuring the consistency of the initial state.

[0033] In this embodiment of the application, the droplet generation method in step S200 includes using a high-precision micro-injection pump to control the syringe to drip liquid, generating a volume-stable droplet (about 13 μL) by adjusting the pump speed and pause time, and forming it outside the electric field to avoid premature charging.

[0034] In an optional implementation, the droplet generation method in step S200 can also utilize a piezoelectric droplet generator to generate a volume-stable single droplet outside the electric field region through voltage pulse excitation, forming an initial droplet sample.

[0035] In an optional implementation, the droplet generation method in step S200 can also be controlled by the opening and closing of a high-level liquid storage container and a micro solenoid valve to generate a single droplet with controllable volume outside the electric field region as an initial droplet sample.

[0036] In this embodiment of the application, in order to achieve precise control of the droplet volume, the parameters of the syringe pump are adjusted to stabilize the volume of each droplet at about 13 μL, and the volume deviation is controlled within ±0.5 μL.

[0037] In this embodiment of the application, the critical droplet volume can be predicted and verified using the following theoretical model: The detachment of the droplet at the needle tip is determined by the balance between gravity and surface tension, and its dimensionless Bond number (Bo) satisfies: (1) in, The relative strength of the interaction between gravity and surface tension is defined as: (2) Φ is a dimensionless parameter related to the droplet radius, defined as: (3) By combining equations (1) to (3), the formula for calculating the critical volume V of the droplet can be derived: (4) in, The radius of the needle outlet. For liquid surface tension, For the density of the liquid, This is the acceleration due to gravity.

[0038] In this embodiment, a needle with an inner diameter of 0.35 mm is used. The liquid to be tested is pure water (surface tension). ,density ), gravitational acceleration Substituting into equation (4), the theoretical critical drop volume under this condition is calculated as follows: The result closely matches the experimental set value of 13 μL, verifying the rationality and predictability of droplet volume control. This method allows for the generation of initial droplet samples with highly consistent volumes, providing a reliable prerequisite for subsequent high-precision charge measurement.

[0039] In this embodiment, step S300 involves adjusting the electrode voltage and electrode spacing using a high-voltage power supply to precisely control the experimental electric field strength. A typical experimental electric field strength is set to 0-6 kV / cm. The droplet moves horizontally within the electric field, and its movement path is observed from the frontal view of the camera. The horizontal direction of the electric field ensures that the force acting on the droplet aligns with its direction of motion, facilitating dynamic analysis.

[0040] In this embodiment of the application, the electric field application method in step S300 includes using parallel plate electrodes connected to a high-voltage power supply to apply a uniform electrostatic field in the horizontal direction in the droplet movement region. The electric field strength is controlled by adjusting the voltage and the distance between the plates (0–6 kV / cm).

[0041] In an optional implementation, the electric field application method in step S300 can also be to apply a non-uniform electric field to the droplet movement region through a needle-plate electrode, so that the droplet moves under the action of the electric field force.

[0042] In an optional implementation, the electric field application method in step S300 can also be to apply an alternating voltage to make the droplet oscillate periodically in the electric field, obtain acceleration information by using the dynamic response of the oscillating motion, and solve the amount of droplet charge based on the force balance equation.

[0043] In this embodiment of the application, obtaining the acceleration of the droplet in the electric field direction in step S400 includes: The motion images of a droplet in a known electric field are acquired using a non-contact motion detection device, and the displacement-time data of the droplet's centroid are determined based on the image sequence. The velocity-time relationship of the droplet in the direction of the electric field is calculated based on the displacement-time data, and the acceleration of the droplet is obtained by differentiating the velocity-time relationship.

[0044] In this embodiment, when the droplet falls, a high-speed camera system (such as Phantom v2012) is used to capture the entire horizontal motion of the droplet after it enters the electric field at a high frame rate. The image frame rate can reach 20,000 fps, ensuring sufficient time accuracy to acquire droplet displacement data. The droplet trajectory is extracted using image processing software (such as Tracker), and curve fitting is performed to obtain the velocity-time relationship. It can be approximated that the droplet undergoes uniform acceleration motion within a small sampling time, and the acceleration of the droplet in the direction parallel to the electric field intensity can be calculated.

[0045] In this embodiment of the application, the image acquisition and motion detection in step S400 includes non-contact shooting using a high-speed camera and a backlight source, extracting displacement-time data from the image sequence using a centroid tracking algorithm, and then obtaining velocity and acceleration through differentiation.

[0046] In an optional implementation, the image acquisition and motion detection in step S400 can also utilize laser Doppler velocimetry (LDV) to perform non-contact velocity field measurement on the droplet moving in the electric field, obtain the velocity-time data of the droplet in the direction of the electric field, and calculate the acceleration.

[0047] In an optional implementation, the image acquisition and motion detection in step S400 can also be achieved by setting multiple photogates with known spacing along the droplet's motion path, detecting the time it takes for the droplet to pass through each point, calculating its velocity, and fitting the acceleration.

[0048] In this embodiment of the application, step S500 yields the force balance equation regarding the charge of the droplet, including: The air resistance experienced by the droplet in the direction of the electric field is expressed as a nonlinear resistance term that is proportional to the square of the droplet's velocity. The electric force on the droplet can be expressed as the product of the charge to be determined and the known electric field strength. According to Newton's second law, the net force on a droplet can be expressed as the product of the droplet's mass and its acceleration. Based on the relationship between electric force, air resistance, and resultant force, a force balance equation is established that includes the unknown charge, measured acceleration, real-time velocity, droplet mass, electric field strength, and fluid resistance coefficient.

[0049] In this embodiment, after neglecting forces with minimal impact on droplet motion, such as fluid inhomogeneity forces and droplet acceleration forces, the equation of motion of the droplet in the electric field is derived based on Newton's second law: (5) (6) in, For electric field strength, For the droplet to carry a charge, For the mass of the droplet, This is the air drag coefficient, which can be taken as a constant of 0.47 for a sphere. air density, For the density of water, The relative motion contact area, For droplets The velocity on the axis. The charge of the droplet can be calculated from the above formula. Specific charge of droplets .

[0050] The solution to the above equation regarding velocity is in the form of: (7) in, A , B All are constants.

[0051] However, in real-world scenarios, since the time it takes for the droplet to be extracted in the software is very short, the droplet velocity can be approximated as linear. The charge can be calculated by replacing the acceleration in equation (5) with the slope. The curve showing the change of the value over time. However, in this device, due to the small droplet velocity, the change in air resistance is small, therefore, The values ​​are basically constants.

[0052] In this embodiment of the application, obtaining the charge of a single droplet in step S600 includes: The force equilibrium equations are solved algebraically to separate the expression for the charge to be determined. By substituting the measured acceleration value, the velocity value at the corresponding moment, the known droplet mass, the electric field strength, and the preset fluid resistance coefficient into the solved expression, the charge of a single droplet is calculated.

[0053] In this embodiment of the application, step S600, under specific low temperature and electric field conditions, includes: The droplet generation system, electric field generation system, and image acquisition system are all placed inside a low-temperature test chamber. Pre-cool the liquid entering the low-temperature test chamber; The ambient temperature of the low-temperature test chamber is controlled to be within the temperature range above and close to the freezing point. A temperature buffer zone is set between the droplet generation system outlet and the electrode plate; The high-speed camera and lens of the image acquisition system are equipped with an anti-condensation layer on their outer surface.

[0054] In this embodiment of the application, in step S600, the calibration plate is set in the plane where the droplet's motion path is located, and is coplanar with the plane of the droplet's motion or is located in the same imaging focal plane; Based on the image of the calibration plate, establish the mapping relationship between pixel coordinates and physical coordinates; The synchronization signal is connected as a synchronization signal line, which transmits the trigger signal of the power controller of the electric field generation system to the image acquisition system to start the image acquisition process; Based on the trigger signal, the timestamp corresponding to each frame of the image during the droplet's motion is determined.

[0055] In this embodiment of the application, multiple droplets were obtained through multiple experiments. The values ​​are calculated, and the average and standard deviation are used for statistical analysis to remove outliers. If the acceleration-time curve shows a linear relationship, it indicates that the droplet is under stable force and its charged state is reliable. Ultimately, a quantitative relationship between a certain electric field strength and the charge of the droplet can be obtained, providing a data foundation for further theoretical analysis and engineering applications.

[0056] In this embodiment of the application, the ambient temperature control method in step S600 includes placing the entire experimental system (droplet generation, electric field, imaging) in a low-temperature test chamber and controlling the ambient temperature in the range above and close to the freezing point to prevent the droplets from freezing.

[0057] In an optional implementation, the ambient temperature control method in step S600 can also be to use a semiconductor cooling chip or cooling jacket to locally cool only the droplet generating system and the movement path area in order to maintain the stability of the droplet at low temperature.

[0058] In an optional implementation, the ambient temperature control method in step S600 can also prevent the droplet surface from condensing or freezing and maintain its liquid stability by controlling humidity or introducing dry inert gas into the test chamber in a low-temperature environment.

[0059] Example 3 is an embodiment of the present invention. This embodiment differs from the first embodiment in that it provides a test system for measuring the charge carried by a moving droplet.

[0060] It should be noted that the technical solution of the test system for measuring the charge of moving droplets is based on the same concept as the technical solution of the test method for measuring the charge of moving droplets described above. For details not described in detail in the technical solution of the test system for measuring the charge of moving droplets in this embodiment, please refer to the description of the technical solution of the test method for measuring the charge of moving droplets described above.

[0061] This embodiment provides a test system for measuring the charge carried by a moving droplet, comprising: The system calibration and preparation module is used to acquire the physical properties of the liquid to be tested, and through debugging and calibration, a standardized experimental system is obtained; The droplet generation and control module is used to generate a single droplet with stable volume by controlling the liquid droplet discharge based on a standardized experimental system, thereby obtaining an initial droplet sample. The electric field application and dynamic excitation module is used to obtain the dynamic process of the droplet's motion under force in the electric field by applying an electric field of known intensity based on the initial droplet sample. The motion parameter extraction module is used to perform droplet centroid tracking and motion curve fitting on the calibrated image sequence based on the dynamic process, so as to obtain the velocity-time relationship and acceleration of the droplet in the electric field direction; The force modeling and equation construction module is used to obtain the force balance equation for the droplet charge by substituting the net force on the droplet in the electric field direction into Newton's second law based on the acceleration, combined with the mass, electric field strength and fluid resistance parameters of the droplet. The charge calculation and statistical output module is used to solve the force balance equation, calculate the charge of a single droplet, and perform statistical analysis through multiple experiments to obtain statistical numerical results of the charge carried by the droplet under specific low temperature and electric field conditions.

[0062] This embodiment also provides an electronic device applicable to a test method for measuring the charge of a moving droplet, including: The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement a test method for measuring the charge of a moving droplet, as described in the above embodiments.

[0063] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a test method for measuring the charge of a moving droplet as proposed in the above embodiments.

[0064] The storage medium proposed in this embodiment and the experimental method for measuring the charge of a moving droplet proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0065] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for measuring the charge carried by a moving droplet, characterized in that, include: The physical properties of the liquid to be tested are obtained, and a standardized experimental system is obtained through debugging and calibration. Based on a standardized experimental system, a single droplet with stable volume is generated by controlling the liquid droplet flow, thus obtaining an initial droplet sample. Based on the initial droplet sample, the dynamic process of the droplet moving under the force of the electric field is obtained by applying an electric field of known strength; Based on the dynamic process, droplet centroid tracking and motion curve fitting are performed on the calibrated image sequence to obtain the velocity-time relationship and acceleration of the droplet in the electric field direction. Based on the acceleration, and combined with the droplet's mass, electric field strength, and fluid resistance parameters, by substituting the net force on the droplet in the electric field direction into Newton's second law, the force balance equation for the droplet's charge is obtained. Solve the force balance equation to calculate the charge of a single droplet, and conduct statistical analysis through multiple experiments to obtain statistical numerical results of the charge carried by the droplet under specific low temperature and electric field conditions.

2. The experimental method for measuring the charge of a moving droplet as described in claim 1, characterized in that: The acceleration of the droplet in the direction of the electric field is obtained, including: The motion images of a droplet in a known electric field are acquired using a non-contact motion detection device, and the displacement-time data of the droplet's centroid are determined based on the image sequence. The velocity-time relationship of the droplet in the direction of the electric field is calculated based on the displacement-time data, and the acceleration of the droplet is obtained by differentiating the velocity-time relationship.

3. The experimental method for measuring the charge of a moving droplet as described in claim 1 or 2, characterized in that: The obtained force balance equations regarding the charge of the droplet include: The air resistance experienced by the droplet in the direction of the electric field is expressed as a nonlinear resistance term that is proportional to the square of the droplet's velocity. The electric force on the droplet can be expressed as the product of the charge to be determined and the known electric field strength. According to Newton's second law, the net force on a droplet can be expressed as the product of the droplet's mass and its acceleration. Based on the relationship between electric force, air resistance, and resultant force, a force balance equation is established that includes the unknown charge, measured acceleration, real-time velocity, droplet mass, electric field strength, and fluid resistance coefficient.

4. The experimental method for measuring the charge of a moving droplet as described in claim 3, characterized in that: The process of obtaining the charge of a single droplet includes: The force equilibrium equations are solved algebraically to separate the expression for the charge quantity to be determined. By substituting the measured acceleration value, the velocity value at the corresponding moment, the known droplet mass, the electric field strength, and the preset fluid resistance coefficient into the solved expression, the charge of a single droplet is calculated.

5. The experimental method for measuring the charge of a moving droplet as described in claim 4, characterized in that: The conditions under specific low temperature and electric field include: The droplet generation system, electric field generation system, and image acquisition system are all placed inside a low-temperature test chamber. Pre-cool the liquid entering the low-temperature test chamber; The ambient temperature of the low-temperature test chamber is controlled to be within the temperature range above and close to the freezing point. A temperature buffer zone is set between the droplet generation system outlet and the electrode plate; The high-speed camera and lens of the image acquisition system are provided with an anti-condensation layer on their outer surfaces.

6. The experimental method for measuring the charge of a moving droplet as described in claim 5, characterized in that: The standardized experimental system includes a droplet generation system, an electric field generation system, an environmental control system, an image acquisition system, and a data analysis system. The electric field generating system and the environmental control system are connected to the same grounding terminal via a conductor; The image acquisition system includes a high-speed camera, a macro lens, an adjustable lifting platform, and a backlight source; The adjustable lifting platform is fixedly connected to the high-speed camera, allowing for adjustment of the high-speed camera's spatial height. The relative positions of the droplet generation system, the electric field generation system, and the image acquisition system are geometrically calibrated. The droplet moves horizontally within the electric field region generated by the electric field generating system, and the trajectory of the droplet is located at the center of the field of view of the image acquisition system; The backlight source is located behind the electrode plate of the electric field generating system, and the light emission axis of the backlight source coincides with the optical axis of the high-speed camera. The data analysis system is connected to the image acquisition system, receives image signals, and performs a data processing flow for calculating charge. The image acquisition system also includes a calibration plate for spatial calibration; The image acquisition system and the electric field generation system are connected by a synchronization signal for time synchronization.

7. The experimental method for measuring the charge of a moving droplet as described in claim 6, characterized in that: The calibration plate is positioned in the plane of the droplet's motion path, is coplanar with the plane of the droplet's motion, and is located on the same imaging focal plane. Based on the image of the calibration plate, a mapping relationship between pixel coordinates and physical coordinates is established; The synchronization signal is connected as a synchronization signal line, which transmits the trigger signal of the power controller of the electric field generation system to the image acquisition system to start the image acquisition process; Based on the trigger signal, the timestamp corresponding to each frame of the image during the droplet's movement is determined.

8. A test system for measuring the charge of a moving droplet, using the method described in any one of claims 1-7, characterized in that, include: The system calibration and preparation module is used to acquire the physical properties of the liquid to be tested, and through debugging and calibration, a standardized experimental system is obtained; The droplet generation and control module is used to generate a single droplet with stable volume by controlling the liquid droplet discharge based on a standardized experimental system, thereby obtaining an initial droplet sample. The electric field application and dynamic excitation module is used to obtain the dynamic process of the droplet's motion under force in the electric field by applying an electric field of known intensity based on the initial droplet sample. The motion parameter extraction module is used to perform droplet centroid tracking and motion curve fitting on the calibrated image sequence based on the dynamic process, so as to obtain the velocity-time relationship and acceleration of the droplet in the electric field direction; The force modeling and equation construction module is used to obtain the force balance equation for the droplet charge by substituting the net force on the droplet in the electric field direction into Newton's second law based on the acceleration, combined with the mass, electric field strength and fluid resistance parameters of the droplet. The charge calculation and statistical output module is used to solve the force balance equation, calculate the charge of a single droplet, and perform statistical analysis through multiple experiments to obtain statistical numerical results of the charge carried by the droplet under specific low temperature and electric field conditions.

9. An electronic device, characterized in that, include: Memory, used to store programs; A processor for loading the program to perform the steps of the method as claimed in any one of claims 1-7.

10. A computer-readable storage medium storing a program, characterized in that, When the program is executed by a processor, it implements the steps of the method as described in any one of claims 1-7.

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