High-temperature metal single-droplet control generation device for droplet breaking experiment

Abstract

The invention belongs to the crossing field of electronic information, electromechanical control and material engineering, and discloses a high-temperature metal single droplet generation device for a droplet breaking experiment. The whole device is composed of a liquid drop generation module, an air pressure control module, a temperature control module, an atmosphere protection module and an optical imaging module. The liquid drop generation module drives a firing pin to instantly strike molten metal in the material storage valve body through an air cylinder, so that the molten metal is sprayed out through a nozzle to form a single liquid drop with the diameter of about 150-400 microns. The air pressure control module provides a stable and adjustable compressed air source, the temperature control module maintains a metal liquid state, inert gas is introduced into the atmosphere protection module to prevent oxidation, and the optical imaging module realizes synchronous observation and kinetic analysis of a droplet generation process by adopting ultra-high-speed photography. The device is compact in structure, accurate in control and stable in operation, can stably generate a single droplet under the normal pressure condition, has good repeatability and controllability, and is suitable for high-temperature droplet experimental research in the fields of material science, aerospace, national defense and the like.

Description

Technical Field

[0001] This invention relates to the field of droplet jetting technology, and in particular to a high-temperature metal single droplet control and generation device for droplet breakage experiments. Background Technology

[0002] With the rapid development of materials science, fluid mechanics, and micro / nano manufacturing technologies, droplet control and generation technology has been widely applied in inkjet printing, microelectronic packaging and soldering, additive manufacturing, precision dispensing, atomization cooling, and high-temperature dynamics research. The generation, collision, breakup, and solidification processes of droplets at the microscale not only directly affect the deposition accuracy and surface quality of materials but also form a crucial foundation for studying heat and mass transfer, interfacial tension, and phase transition dynamics. Particularly in high-temperature metal droplet impact, breakup, and shock wave experiments, the droplet size, temperature, and generation frequency must possess excellent controllability and repeatability, placing higher demands on the stability of droplet generation devices.

[0003] Currently, common droplet generation technologies mainly include gas pressure jetting, piezoelectric atomization, electrothermal excitation, acoustic atomization, and microfluidics. Although these methods have achieved relatively stable droplet output in low-viscosity fluids (such as water, oil, or solutions), they generally face significant technical bottlenecks when dealing with high-temperature molten metals.

[0004] Pneumatic jet method: This method relies on external air pressure pulses to propel liquid through a nozzle and form droplets. While structurally simple, the jet pressure is significantly affected by liquid viscosity and surface tension. Furthermore, in high-temperature metal environments, the nozzle is prone to thermal oxidation or clogging, leading to uneven droplet size and unstable jet intervals. Additionally, continuous airflow often results in multiple droplets or jets, making precise control of individual droplets difficult.

[0005] Piezoelectric actuation: This method uses piezoelectric ceramics to generate instantaneous deformation, squeezing a liquid chamber and ejecting droplets. It is widely used in inkjet printing and micro-dispensing, but piezoelectric ceramic materials are extremely sensitive to temperature; their polarization properties rapidly decay or even fail above 300°C, making them unsuitable for generating droplets from high-temperature liquid metals. Furthermore, the piezoelectric structure has relatively low output energy, resulting in insufficient driving force for high-viscosity, high-density molten metals.

[0006] Electrothermal excitation method: This method utilizes a heating resistor to instantly evaporate a localized area of ​​liquid, generating droplets through bubble bursts. While it can achieve high-speed droplet generation, the instantaneous temperature difference during thermal excitation is too large, making the metal droplets prone to overheating or even splashing. Furthermore, the heating element has a short lifespan and poor repeatability in high-temperature metal environments.

[0007] Acoustic atomization: This method uses an ultrasonic transducer to excite capillary waves on the liquid surface, thereby generating droplets. It is suitable for micro-atomization of cryogenic fluids, but its adaptability to high-temperature molten metals is extremely poor. The high density and high surface tension of molten metals make it difficult for sound waves to propagate effectively, and ultrasonic transducers cannot withstand high-temperature radiation environments.

[0008] Microfluidics has demonstrated high precision and consistency in droplet generation in recent years, achieving periodic droplet separation through shear flow or flow focusing. However, the temperature limits of mainstream chip materials (such as silicon, glass, or polymers) typically do not exceed 200–300°C, making them unsuitable for molten metal environments. More importantly, microfluidic systems struggle to achieve transient operations that generate only one droplet at a time; their droplet generation frequency is fixed and limited by external flow rates, making them unsuitable for experiments involving single, controllable high-temperature droplets.

[0009] In summary, existing droplet generators are mostly designed for low-temperature, low-viscosity, or medium-temperature fluids, making it difficult to meet the requirements for precise, stable, and controllable single-droplet generation of high-temperature metal droplets. Therefore, there is an urgent need to develop a novel high-temperature metal single-droplet control generation device capable of achieving transient ejection of single droplets of molten metal in high-temperature environments, providing reliable technical support for high-temperature droplet dynamics, breakup, and shock wave impact experiments. Summary of the Invention

[0010] This invention addresses the technical problems existing in the prior art by providing a high-temperature metal single droplet control and generation device for droplet breakage experiments. It uses a cylinder to drive a striking pin, which instantaneously impacts the liquid metal under high-temperature molten metal conditions, causing the molten metal to be ejected and form a single droplet.

[0011] The technical solution adopted by the present invention to solve its technical problem is: a high-temperature metal single droplet control and generation device for droplet breakage experiment, including a droplet generation module, a pressure control module, a temperature control module, an atmosphere protection module and an optical imaging module, wherein the droplet generation module includes a storage valve body, a heater, a striking pin and a cylinder.

[0012] The storage valve body has a storage chamber, a material conveying channel, and a striker channel inside. The heater is located outside or inside the storage valve body and is connected to the temperature control module for heating the metal material placed in the storage chamber to melt it into a liquid state. The striker channel runs vertically through the storage valve body, and its inner wall shape matches the striker. A nozzle is provided at its bottom. One end of the material conveying channel is connected to the bottom of the storage chamber, and the other end is connected to the side wall of the striker channel.

[0013] The firing pin is coaxially arranged with the firing pin channel, and its upper end is connected to the piston rod of the cylinder so that it is driven by the cylinder to reciprocate along the firing pin channel. During operation, the cylinder is controlled by the air pressure control module, which drives the firing pin to periodically impact the liquid metal entering the firing pin channel, causing the liquid metal to be ejected from the nozzle in the form of single droplets.

[0014] The atmosphere protection module provides a sealed protective space for the droplet generation module, which is filled with inert gas; the optical imaging module is used to capture the ejection and falling process of the droplets.

[0015] In a preferred embodiment, the atmosphere protection module includes an air inlet, an air outlet, and a sealed cavity. The sealed cavity surrounds the droplet generation module, forming the sealed protective space. The air inlet is connected to an inert gas source and the sealed cavity, and is used to supply inert gas into the sealed cavity and discharge the original gas in the sealed cavity through the air outlet, thereby replacing the atmosphere inside the sealed cavity. The air inlet and / or the air outlet are equipped with a valve or a flow regulating device to achieve stable discharge and controllable adjustment of the internal pressure of the sealed cavity.

[0016] In a preferred embodiment, the atmosphere protection module includes an atmosphere protection cover and a gas storage bottle. The atmosphere protection cover is disposed outside the droplet generating module to form the sealed cavity. The atmosphere protection cover has an air inlet and an air outlet. The gas storage bottle is used to store inert gas and is connected to the air inlet. The inert gas includes one or more of nitrogen and argon. The atmosphere protection module also includes a support platform. The droplet generating module is disposed on the support platform. The atmosphere protection cover overlaps the support platform and together with the support platform, they enclose the sealed cavity.

[0017] In a preferred embodiment, the optical imaging mechanism includes an illumination source and a high-speed camera. The illumination source provides stable illumination conditions to the droplet generation area of ​​the droplet generation module, and the high-speed camera is positioned directly in front of the droplet generation area of ​​the droplet generation module.

[0018] In a preferred embodiment, the sidewall of the sealed cavity is provided with a plurality of transparent observation windows, two of which are arranged opposite to each other. The illumination source is located outside one of the observation windows to provide directional illumination to the droplet generation area; the high-speed camera is located outside the other observation window.

[0019] In a preferred embodiment, the high-speed camera is connected to the main control board of the pneumatic control module. When the main control board drives the cylinder to start the movement of the impact pin, it outputs a trigger signal to the high-speed camera to start the high-speed camera to perform image acquisition, thereby synchronizing the timing of the impact pin movement and the image acquisition.

[0020] In a preferred embodiment, the droplet generation module further includes a height adjustment mechanism connected to the cylinder, which is used to adjust the installation height and initial position of the cylinder and its connected impact pin relative to the storage valve body, so as to precisely control the stroke length and impact energy of the impact pin.

[0021] In a preferred embodiment, the droplet generation module further includes a base, and the height adjustment mechanism and the storage valve body are disposed on the base. The height adjustment mechanism includes a lead screw lifting unit, a fine-tuning dial, and a locking component. The fine-tuning dial is connected to the lead screw of the lead screw lifting unit. By rotating the fine-tuning dial, the lead screw is driven to rise and fall in the vertical direction, thereby adjusting the installation position of the cylinder in the vertical direction. After the cylinder is adjusted to the target position, the locking component locks the relative position of the lead screw lifting unit and the cylinder to achieve stable holding of the cylinder position.

[0022] In a preferred embodiment, the nozzle is detachably connected to the storage valve body, and nozzles with different orifice diameters can be replaced to adjust the diameter of the generated droplets; the storage valve body is made of nickel-plated stainless steel; the heater includes a heating resistance wire wound around the outside of the storage valve body and electrically connected to a temperature control device to achieve constant temperature heating of the storage valve body; the storage chamber is provided with a feeding port, which is detachably connected to a sealing cap.

[0023] In a preferred embodiment, the outer wall of the cylinder is provided with a heat insulation layer to block the heat of the storage valve body from being conducted to the cylinder; it also includes a pneumatic control module, which includes an air tank, a solenoid valve and a main control board. The air tank is connected to the cylinder through the solenoid valve, and the solenoid valve is electrically connected to the main control board to control the opening and closing sequence of the solenoid valve.

[0024] In a preferred embodiment, the firing pin is made of stainless steel with a surface roughness Ra of no more than 0.8 μm; the firing pin is cylindrical with a conical lower end that faces the nozzle; the lower end face of the firing pin is hemispherical or arc-shaped; there is a radial gap between the firing pin and the firing pin channel, the gap size of which is controlled within the range of 0.2 to 0.5 mm.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention employs a cylinder-driven impact pin, combined with a storage valve body, to achieve integrated control of high-temperature metal material melting and droplet ejection. In a high-temperature molten state, the cylinder-driven impact pin delivers a momentary, directional impact to the liquid metal, causing the molten metal to be ejected at high speed from the nozzle, forming a single droplet. This design effectively avoids the technical bottleneck of piezoelectric drive components being prone to depolarization, performance degradation, or even failure under high-temperature environments. Simultaneously, it overcomes the problems of poor ejection repeatability and droplet size dispersion caused by gas source fluctuations, response lag, and unstable pressure control in traditional pneumatic drive systems under high-temperature conditions. Therefore, this invention can achieve high stability, high repeatability, and precise controllability of droplet generation in extreme high-temperature environments, significantly improving the reliability and experimental repeatability of high-temperature metal single droplet generation, and providing an efficient and reliable experimental platform for cutting-edge research on high-temperature droplet breakup, solidification kinetics, and multiphase flow behavior.

[0027] 2. The atmosphere protection module of this invention provides a stable inert atmosphere environment for the droplet generation module during the droplet generation process, effectively isolating oxygen in the air from contact with the high-temperature droplets. This significantly suppresses chemical reactions, surface oxide layer formation, and violent splashing caused by high-temperature oxidation during droplet ejection and flight. This design not only ensures the stability of the original physical state and chemical composition of the droplets but also greatly reduces droplet size fluctuations and ejection inconsistencies caused by oxidation or splashing, thereby further improving the repeatability of experiments and the reliability of data.

[0028] 3. The optical imaging module of this invention can realize high-frequency imaging and data acquisition of the droplet generation process, facilitating the analysis of droplet dynamic characteristics. In particular, the high-speed camera of the optical imaging module is electrically connected to the main control board of the air pressure control module, enabling precise synchronization between image acquisition and droplet generation timing, ensuring the accuracy of data acquisition.

[0029] 4. By adjusting the striker stroke, air source pressure, and nozzle orifice diameter, this invention can control the droplet size, velocity, and spray direction, thereby achieving stable generation and parameterized adjustment of single droplets.

[0030] 5. This invention has a compact structure, precise control, and reliable operation. It can stably generate single metal droplets under high temperature conditions, providing experimental support for the study of droplet breakup, impact, heat transfer, and metal fluid dynamics.

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments; however, the high-temperature metal single droplet control and generation device for droplet breakage experiments of the present invention is not limited to the embodiments. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0033] Figure 2 This is a schematic diagram showing the cooperation between the droplet production module and the support platform of the present invention;

[0034] Figure 3 This is a three-dimensional structural schematic diagram of the droplet generation module of the present invention;

[0035] Figure 4 This is a front view of the droplet generation module of the present invention;

[0036] Figure 5 This is a cross-sectional view of the storage valve body of the present invention;

[0037] Figure 6 This is a schematic diagram of the firing pin structure of the present invention;

[0038] Figure 7 These are experimental results images of the present invention;

[0039] In the diagram, 1-base; 101-fixed boss; 102-clearance channel; 103-mounting hole; 2-storage valve body; 21-impact pin channel; 211-nozzle; 212-connecting seat; 22-storage and feeding chamber; 221-feeding port; 222-sealing cover; 23-material conveying channel; 3-cylinder; 4-impact pin; 5-height adjustment mechanism; 6-heating resistance wire; 7-atmosphere protection cover; 8-temperature control module; 9-light source base; 10-optical positioning platform; 11-lighting source; 12-camera bracket; 13-gas cylinder; 14-observation window; 15-high-speed camera; 16-gas tank; 17-support platform; 171-limiting step surface. Detailed Implementation

[0040] In this invention, the terms "first," "second," and "third," etc., are used only to distinguish similar objects, not to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. The use of terms such as "upper," "lower," "left," "right," "front," "rear," "inner," "outer," and "top / bottom" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings, and is only for the convenience of describing the invention, not to indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation; therefore, it should not be construed as a limitation on the scope of protection of this invention. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] Furthermore, in the description of this invention, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0042] Please see Figures 1-7 As shown, the present invention provides a high-temperature metal single droplet control and generation device for droplet breakage experiments, comprising five functional modules: a droplet generation module, an atmosphere protection module, an optical imaging module, a pressure control module, and a temperature control module.

[0043] like Figures 2-5 As shown, the droplet generation module includes a storage valve body 2, a heater, a striking pin 4, and a cylinder 3. The storage valve body 2 is made of nickel-plated stainless steel, which has excellent high-temperature resistance, corrosion resistance, and good metal wetting properties, and can operate stably in high-temperature environments of 300-600°C. The storage valve body 2 has a storage chamber 22, a material conveying channel 23, and a striking pin channel 21 inside. The upper end of the storage chamber 22 is provided with a feeding port 221, which is detachably connected to a sealing cap 222. The heater is located outside or inside the storage valve body 2 and is connected to a temperature control module 8 for heating the metal material placed in the storage chamber 22, melting it into a liquid state. In this embodiment, the heater preferably uses a heating resistance wire 6, which is wound around the outside of the storage valve body 2 and electrically connected to the temperature control module 8 to achieve constant temperature heating of the storage valve body 2. It can also monitor and control the heating temperature in real time and maintain the metal temperature between 230 and 600°C as needed to meet the melting conditions of metals such as tin, aluminum, and bismuth.

[0044] The firing pin channel 21 extends vertically upwards and downwards, its inner wall shape matching that of the firing pin 4, and a nozzle 211 is provided at its bottom. In a preferred embodiment, the nozzle 211 is detachably connected to the storage valve body 2, facilitating the replacement of nozzles 211 with different orifice diameters to adjust the diameter of the generated droplets according to experimental requirements. Specifically, the orifice diameter of the nozzle 211 can be flexibly changed within the range of 100 μm to 500 μm. A connecting seat 212 is provided at the lower end of the firing pin channel 21 on the storage valve body 2. This connecting seat 212 is threadedly connected to the nozzle 211, and a sealing gasket is provided between them to achieve a reliable seal and prevent liquid metal leakage. The connecting seat 212 can be integrally formed with the storage valve body 2 or it can be a separate component, reliably connected by screws, welding, or other fixing methods. One end of the material conveying channel 23 is connected to the bottom of the storage chamber 22, and the other end is connected to the bottom of the side wall of the impact pin channel 21. The material conveying channel 23 is horizontally arranged. However, the present invention is not limited to a horizontal arrangement. In other embodiments, the material conveying channel 23 can also be inclined, and its lower end is connected to the impact pin channel 21 to adapt to the material flow requirements under different working conditions and ensure that the liquid metal is stably and continuously conveyed to the action area of ​​the impact pin 4 under high temperature conditions.

[0045] The impact pin 4 is coaxially arranged with the impact pin channel 21, and its upper end is connected to the piston rod of the cylinder 3, so that it is driven by the cylinder 3 to reciprocate along the impact pin channel 21. Specifically, the cylinder 3 is located on the storage valve body 2, with its piston rod facing downwards, and is connected to the upper end of the impact pin 4 by threads or pins to ensure stable and reliable motion transmission and avoid loosening or eccentricity under high-frequency impact. During operation, the cylinder 3 is controlled by the pneumatic control module, driving the impact pin 4 to periodically impact the liquid metal entering the impact pin channel 21, causing the liquid metal to be ejected as single droplets through the nozzle 211.

[0046] The air pressure control module includes an air tank 16, a solenoid valve (not shown in the figure), and a main control board (not shown in the figure). The air tank 16 is connected to an external air source system, which fills the air tank 16 with air to maintain the required stable air pressure inside, providing continuous and controllable compressed gas to the cylinder 3. A pressure sensor can be installed inside the air tank 16 to achieve air pressure monitoring and feedback control, ensuring that air pressure fluctuations are within the allowable range, thereby guaranteeing the consistency of droplet generation. The air tank 16 is connected to the cylinder 3 via the solenoid valve, which is electrically connected to the main control board. The solenoid valve precisely adjusts the timing and flow rate of compressed gas entering the cylinder 3 according to the control signal from the main control board, realizing the starting and resetting actions of the impact pin 4. By adjusting the opening duration and frequency of the solenoid valve, the reciprocating speed and impact energy of the impact pin 4 can be precisely controlled, thereby achieving precise adjustment of the droplet generation frequency and droplet size. The gas pressure control module, through the coordinated operation of a stable gas pressure provided by the gas storage tank 16, precise airflow control by a solenoid valve, and the driving of the impact pin 4 by the cylinder 3, achieves high precision, repeatability, and controllability of the impact pin 4's movement during droplet generation, providing reliable power for high-temperature metal droplet experiments. A heat insulation layer is installed on the outer wall of the cylinder 3 to prevent heat transfer from the storage valve body 2 to the cylinder 3, thus preventing aging or failure of the internal seals. This heat insulation layer can be made of high-density heat-insulating cotton material.

[0047] The firing pin 4 is preferably made of high-strength, high-temperature resistant stainless steel, which has good thermal stability, oxidation resistance, and corrosion resistance, and can work stably for a long time in high-temperature environments of 300-600℃ without deformation or adhesion. Figure 5 As shown, the impact pin 4 is cylindrical in shape, with a diameter slightly smaller than the inner diameter of the impact pin channel 21, creating a radial gap between the impact pin 4 and the impact pin channel 21. This gap is controlled within the range of 0.2–0.5 mm to ensure the coaxiality and sealing of the impact pin 4 during reciprocating motion. The lower end of the impact pin 4 has a conical structure and is positioned directly opposite the nozzle 211. The lower end face of the impact pin 4 is machined into a hemispherical or arc transition structure to reduce liquid turbulence during impact and improve impact energy transfer efficiency. The surface of the impact pin 4 is precision machined and polished, with a surface roughness Ra ≤ 0.8 μm, to reduce frictional resistance with the inner wall of the impact pin channel 21 and prevent the adhesion of liquid metal at high temperatures. The overall length of the impact pin 4 is determined according to the device structure, preferably 50–80 mm, to ensure stable impact motion within the effective stroke range (0.5–1 cm).

[0048] An atmosphere protection module is located outside the droplet generation module to provide a controllable protective atmosphere during droplet generation, preventing high-temperature metal oxidation. Specifically, the atmosphere protection module provides a sealed protective space for the droplet generation module, filled with inert gas. Preferably, the atmosphere protection module includes an inlet, an outlet, and a sealed cavity. The inlet is connected to the inert gas source and the sealed cavity, supplying inert gas into the sealed cavity and discharging the original gas (i.e., the gas already in the sealed cavity before the inert gas supply, specifically air) from the sealed cavity through the outlet, thereby replacing the atmosphere inside the sealed cavity and creating a low-oxygen or inert protective environment. The inlet and / or outlet are equipped with valves or flow regulators to achieve stable discharge and controllable adjustment of the internal pressure of the sealed cavity. Specifically, in this embodiment, the inlet flow rate can be precisely controlled by a flow regulator to ensure atmosphere stability. The outlet is equipped with a valve or flow regulator to achieve stable discharge and pressure control. The sealed cavity is made of a high-temperature resistant material that does not react with high-temperature molten metal droplets, preventing high-temperature metal splashing or atmosphere leakage. By adjusting the gas flow rate and the cavity's sealing performance, a low-oxygen experimental environment with controllable oxygen content can be achieved, effectively preventing molten metal oxidation and improving the repeatability and reliability of droplet generation experiments.

[0049] In this embodiment, as Figure 1 As shown, the atmosphere protection module includes an atmosphere protection cover 7 and a gas storage bottle 13. The atmosphere protection cover 7 is placed outside the droplet generation module. The gas storage bottle 13 is used to store inert gas. The atmosphere protection cover 7 has an inlet and an outlet. The inlet is connected to the gas storage bottle 13 through a gas pipe, and the outlet is connected to an exhaust pipe. During the experiment, the gas storage bottle 13 continuously supplies inert gas into the atmosphere protection cover 7, and the exhaust port discharges the internal gas to maintain a low-oxygen environment inside. The inert gas includes one or more of nitrogen, argon, etc. In this embodiment, nitrogen is used as an example of inert gas, but it is not limited to this. Therefore, the gas storage bottle 13 stores nitrogen and can also be called a nitrogen bottle. The atmosphere protection cover 7 has a transparent observation window 14. The atmosphere protection cover 7 is preferably made of high-temperature resistant opaque metal or ceramic material to improve heat resistance and light blocking performance. Its observation window 14 is made of high-temperature resistant quartz glass or high borosilicate glass, which has good optical transmittance and sealing performance.

[0050] The optical imaging module, used to capture the ejection and descent of droplets, includes an illumination source 11 and a high-speed camera 15. The illumination source 11 provides stable lighting conditions to the droplet generation area of ​​the droplet generation module, while the high-speed camera 15 is positioned directly over the droplet generation area to capture the ejection and descent of droplets. Through the optical imaging module, researchers can observe and record droplet ejection, trajectory, and fracture morphology in real time, providing precise experimental data for droplet dynamics analysis, droplet breakup behavior research, and droplet parameter optimization.

[0051] In this embodiment, the high-speed camera 15 is configured with high-speed shooting capabilities, and its sampling frequency is adjustable within the range of 500-4000Hz, achieving clear frame imaging. The illumination source 11 is a high-brightness LED array or a pulsed laser source.

[0052] The optical shaping module is located outside the sealed cavity (i.e., the atmosphere protection shroud 7). Specifically, the side wall of the atmosphere protection shroud 7 has multiple observation windows 14, with two observation windows 14 arranged opposite each other. An illumination source 11 is located outside one of the observation windows 14 to provide directional, uniform, and stable illumination to the droplet generation area, ensuring clear visibility of the droplets and the ejection process. A high-speed camera 15 is located outside the other observation window 14, parallel to the illumination source 11 and aligned with the droplet generation area, to capture the high-speed motion of droplet ejection, splitting, and breakup.

[0053] In a preferred embodiment, the high-speed camera 15 is electrically connected to the main control board of the pneumatic control module. When the main control board drives the cylinder 3 to start the movement of the impact pin 4, it outputs a trigger signal to the high-speed camera 15 to start the high-speed camera 15 to acquire images, thereby synchronizing the timing of the impact pin 4's movement and the image acquisition.

[0054] In a preferred embodiment, the droplet generation module further includes a height adjustment mechanism 5, which is connected to the cylinder 3. This mechanism adjusts the installation height and initial position of the cylinder 3 and its connected impact pin 4 relative to the storage valve body 2, thereby precisely controlling the stroke length and impact energy of the impact pin 4. The droplet generation module also includes a base 1, on which the storage valve body 2 is mounted. The height adjustment mechanism 5 is also mounted on the base 1, fixing the storage valve body and the height adjustment mechanism 5 relative to each other. The height adjustment mechanism 5 includes a lead screw lifting unit, a fine-tuning dial, and a locking component. The fine-tuning dial is connected to the lead screw of the lead screw lifting unit. Rotating the fine-tuning dial drives the lead screw to rise and fall vertically, achieving a displacement control accuracy of 0.1 mm, thus precisely adjusting the installation position of the cylinder 3 in the vertical direction. After the cylinder 3 is adjusted to the target position, the locking component locks the relative position of the lead screw lifting unit and the cylinder 3, ensuring stable and fixed position of the cylinder 3 under high-frequency reciprocating operation. The height adjustment mechanism 5 allows for flexible setting of the initial position of the impact pin 4 before the experiment, based on the physical properties of the metal used (such as melting point, viscosity, and density) and the gas source pressure, thereby achieving precise matching of impact kinetic energy. For example, under a constant gas source pressure, appropriately increasing the distance between the cylinder 3 and the storage valve body 2 can result in a longer stroke of the impact pin 4 and higher impact kinetic energy, suitable for high-viscosity, high-melting-point liquid metals; conversely, shortening the stroke of the impact pin 4 can achieve low-energy impact, which is beneficial for generating smaller, more stable single droplets.

[0055] like Figure 3As shown, the base 1 is provided with a fixing boss 101 for mounting the storage valve body 2. The storage valve body 2 is mounted on the fixing boss 101, and the nozzle 211 of the storage valve body 2 is arranged downwards to ensure that the droplets are accurately sprayed in a vertical direction. Specifically, the storage valve body is reliably locked to the fixing boss 101 by multiple screws, but the fixing method is not limited to this. In order to realize the free fall of the droplets and subsequent observation, the fixing boss 101 has a horizontally penetrating clearance channel 102 in the area directly below the corresponding nozzle 211. The end of the nozzle 211 is suspended in the middle of the clearance channel 102, forming an unobstructed vertical passage. The bottom area of ​​the clearance channel 102 is dedicated to receiving the sprayed droplets to avoid droplet splashing and contaminating the surrounding structure. Therefore, the fixing boss 101 is preferably integrally formed of high temperature resistant and corrosion resistant metal or ceramic composite material to withstand the heat load when the nozzle is working. A high-speed camera 15 and an illumination source 11 are respectively positioned on both sides of the clearance channel 102 in the horizontal direction. Through the clearance channel 102, synchronous, interference-free high-definition imaging and uniform illumination of the nozzle 211 area (i.e., the droplet generation area) are achieved, ensuring high-precision acquisition of key parameters such as droplet morphology, size, frequency, and jet stability. The base 1 has a plate-like structure with good rigidity. Its fixing boss 101 is integrally formed with the base 1, resulting in strong structural integrity. Multiple mounting holes 103 are distributed on the base 1, facilitating the secure installation of the entire machine onto the working platform (such as the support platform 17 mentioned below) using standard fasteners, ensuring the system's positioning accuracy and vibration resistance during long-term operation. Preferably, the atmosphere protection module also includes the support platform 17, on which the droplet generation module is mounted. The atmosphere protection cover 7 overlaps the support platform 17, and together with the support platform 17, they form the aforementioned sealed cavity. Specifically, the base 1 of the droplet generation module is adjustablely positioned on the top surface of the support platform 17. The support platform 17 has limiting step surfaces 171 around its perimeter for positioning the atmosphere protection shroud 7. The bottom of the atmosphere protection shroud 7 rests against these limiting step surfaces 171, and the two fit together vertically. The support platform 17 is specifically a flat plate structure with good flatness and load-bearing capacity. However, the invention is not limited to this; in other embodiments, the support platform 17 can adopt various workbench structures with horizontal surfaces. The temperature control module 8 and the gas storage tank 16 are located outside the atmosphere protection shroud 7. The atmosphere protection shroud 7 has clearance holes for conductive wires and gas pipes to pass through. A light source support frame 9 and a camera bracket 12 are respectively located on opposite sides of the support platform 17. The high-speed camera 15 is mounted on the camera bracket 12, and the illumination source 11 is mounted on the light source support frame 9, with adjustable illumination angle and distance to align the illumination direction with the field of view of the high-speed camera 15. Specifically, an optical positioning platform 10 is provided on the light source support frame 9, and the lighting source 11 is installed on the optical positioning platform 10.

[0056] The invention is further illustrated below with specific experiments: Tin is selected as the experimental metal material, which can fully melt and maintain good liquid flowability at a storage valve body temperature of 300℃. The nozzle 211 orifice diameter is set to 200 micrometers to achieve controllable generation of micro-scale droplets. The stroke of the impact pin 4 is fixed at 0.5 cm to ensure stable displacement and impact energy for each impact. The gas source pressure is controlled within the range of 0.15 MPa to 0.4 MPa, and precise adjustment is achieved through a gas pressure control module to match different spray frequencies and droplet size requirements.

[0057] Before the experiment, the entire apparatus was first calibrated. The operator needed to precisely adjust the relative height between the cylinder 3 and the storage valve 2 using the height adjustment mechanism 5, based on the type of metal being tested, the size of the target droplet, and the impact frequency, and set the required impact stroke. After adjustment, the height adjustment mechanism 5 was locked, and the coaxiality of the impact pin 4 within the impact pin channel 21 was checked to ensure smooth, unobstructed movement. Subsequently, the entire droplet generation module was placed on the support platform 17, covered with the atmosphere protection shroud 7, and its position within the atmosphere protection shroud 7 was adjusted so that the nozzle 211 outlet was located in the imaging center area of ​​the observation window 14, while ensuring that the optical axes of the illumination source 11 and the high-speed camera 15 were parallel. After the droplet generation module's position was adjusted, screws were used to lock the base to the top surface of the support platform 17, achieving precise positioning and mechanical fixation of the liquid generation module. The illumination angle and distance of the illumination source 11 were finely adjusted using the optical positioning platform 10 to fix the positions of the high-speed camera 15 and the illumination source 11, and the synchronous trigger connection between them and the main control board was checked. After the device is positioned, check whether the connection between the air inlet and the air outlet is secure.

[0058] During the experiment, the illumination source 11 and high-speed camera 15 were turned on, and the illumination angle and brightness of the light source were adjusted to ensure uniform illumination and clear imaging of the experimental area. Then, the gas storage bottle 13 was opened to continuously fill the atmosphere protection chamber 7 with nitrogen gas for about 5 minutes to fully replace the air in the atmosphere protection chamber 7, ensuring that the experimental space is in a low-oxygen or oxygen-free state to prevent oxidation of the high-temperature liquid metal during the generation process.

[0059] After the internal atmosphere stabilizes, the temperature control module 8 is activated to heat the storage valve body 2, raising its temperature to the set value (e.g., 300℃~600℃) and maintaining it at a constant temperature for about 5~10 minutes to ensure that the metal raw material is completely melted and forms a liquid state with good fluidity.

[0060] After the temperature stabilizes, compressed gas is introduced into the gas storage tank 16 through the gas supply system and the pressure is stabilized. The gas pressure is then adjusted to the set range as needed. Subsequently, the main control board sends a trigger signal to drive the solenoid valve to open, allowing compressed gas to enter the cylinder 3 chamber. This pushes the piston rod, causing the impact pin 4 to move downwards, completing one impact action. Under inertia, the impact pin 4 impacts the liquid metal flowing to the lower part of the impact pin channel 21, causing it to be ejected from the nozzle 211, generating a single metal droplet.

[0061] Upon receiving the synchronization trigger signal, the high-speed camera 15 immediately begins capturing images at a frequency of 2000 Hz to capture transient dynamic information throughout the entire process of droplet formation, separation, and descent. By analyzing the resulting high-speed image sequence, dynamic parameters such as droplet diameter, velocity, deformation, and separation characteristics can be obtained.

[0062] Figure 6 is a schematic diagram of the droplet generation process captured by high-speed camera 15 during the experiment of this invention. As can be seen from the figure, the droplets exhibit uniform shape and stable formation during the spraying process, without obvious breakage, atomization, or unexpected splashing, indicating that this invention has excellent spraying consistency and dynamic stability. The experiment shows that when the nozzle 211 orifice diameter is 200 micrometers, the stroke of the impact pin 4 is fixed at 0.5 cm, and the gas source pressure is 0.15–0.4 MPa, this invention can stably generate single metal droplets with a diameter of approximately 150–400 μm. The droplet size increases with increasing gas source pressure, demonstrating good reliability. The generated droplets are approximately spherical in shape, with smooth surfaces, stable falling trajectories, and consistent directions, showing good repeatability and controllability.

[0063] Further research revealed that nozzle orifice diameter, impact pin stroke, and gas source pressure are key parameters affecting droplet formation characteristics. When the nozzle orifice diameter varies within the optimal range of 100–500 μm, the droplet diameter increases with increasing orifice size, and the generated droplet morphology is better. Outside this optimal range, while smaller orifice diameters help control droplet morphology, they can lead to insufficient spraying due to excessive flow resistance. Larger orifice diameters, while effectively reducing flow resistance, increasing flow rate, and improving spray stability, can result in larger droplet size and wider distribution, affecting droplet morphology. The optimal impact pin stroke range is 0.2–3 cm. Within this range, appropriately increasing the stroke can increase impact kinetic energy and promote droplet detachment, while excessive stroke can lead to continuous liquid ejection, forming a jet phenomenon and affecting the formation of individual droplets.

[0064] Meanwhile, the gas source pressure also plays a significant role in droplet breakage and formation. When the gas source pressure is below 0.1 MPa, droplets cannot be effectively ejected; while when the pressure exceeds 0.4 MPa, continuous jetting of liquid or satellite droplet formation is likely to occur, thus reducing droplet size uniformity. By comprehensively adjusting the parameters of the nozzle diameter, the striker stroke, and the gas source pressure, precise control of droplet size, morphology, and stability can be achieved.

[0065] The above results fully verify that the present invention possesses excellent repeatability, stability, and size adjustability in the high-temperature metal single droplet generation process. Therefore, the impact structure driven by cylinder 3 in this invention has advantages such as adjustable energy, fast response speed, and stable output. Compared with traditional pneumatic injection and microfluidic methods, this structure can achieve controllable generation of single droplets in a high-temperature environment, with uniform droplet size and adjustable frequency, making it suitable for the breakup, shock wave impact, and thermophysical property research of high-temperature metal droplets.

[0066] The present invention provides a high-temperature metal single droplet control and generation device for droplet breakage experiments. The parts not described herein are the same as or can be implemented using existing technologies.

[0067] The above embodiments are only used to further illustrate a high-temperature metal single droplet control and generation device for droplet breakage experiments according to the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A high-temperature metal single-droplet controlled generation device for droplet breakage experiments, characterized in that: It includes a droplet generation module, a pressure control module, a temperature control module, an atmosphere protection module, and an optical imaging module. The droplet generation module includes a storage valve body, a heater, a firing pin, and a cylinder. The storage valve body has a storage chamber, a material conveying channel, and a striker channel inside. The heater is located outside or inside the storage valve body and is connected to the temperature control module for heating the metal material placed in the storage chamber to melt it into a liquid state. The striker channel runs vertically through the storage valve body, and its inner wall shape matches the striker. A nozzle is provided at its bottom. One end of the material conveying channel is connected to the bottom of the storage chamber, and the other end is connected to the side wall of the striker channel. The firing pin is coaxially arranged with the firing pin channel, and its upper end is connected to the piston rod of the cylinder so that it is driven by the cylinder to reciprocate along the firing pin channel. During operation, the cylinder is controlled by the air pressure control module, which drives the firing pin to periodically impact the liquid metal entering the firing pin channel, causing the liquid metal to be ejected from the nozzle in the form of single droplets. The atmosphere protection module provides a sealed protective space for the droplet generation module, which is filled with inert gas; the optical imaging module is used to capture the ejection and falling process of the droplets.

2. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 1, characterized in that: The atmosphere protection module includes an air inlet, an air outlet, and a sealed cavity. The sealed cavity surrounds the droplet generation module, forming the sealed protective space. The air inlet is connected to the inert gas source and the sealed cavity, and is used to supply inert gas into the sealed cavity and discharge the original gas in the sealed cavity through the air outlet, thereby replacing the atmosphere inside the sealed cavity. The air inlet and / or the air outlet are equipped with a valve or flow regulating device to achieve stable discharge and controllable adjustment of the internal pressure of the sealed cavity.

3. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 2, characterized in that: The atmosphere protection module includes an atmosphere protection cover and a gas storage bottle. The atmosphere protection cover is installed outside the droplet generation module. The atmosphere protection cover has an air inlet and an air outlet. The gas storage bottle is used to store inert gas and is connected to the air inlet. The inert gas includes one or more of nitrogen and argon. The atmosphere protection module also includes a support platform. The droplet generation module is set on the support platform. The atmosphere protection cover is attached to the support platform and together with the support platform, they form the sealed cavity.

4. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 2 or 3, characterized in that: The optical imaging mechanism includes an illumination source and a high-speed camera. The illumination source is used to provide stable illumination conditions to the droplet generation area of ​​the droplet generation module, and the high-speed camera is positioned directly in front of the droplet generation area of ​​the droplet generation module.

5. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 4, characterized in that: The sidewall of the sealed cavity is provided with multiple transparent observation windows, two of which are arranged opposite each other. The illumination source is located outside one of the observation windows to provide directional illumination to the droplet generation area; the high-speed camera is located outside the other observation window.

6. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 4, characterized in that: The high-speed camera is electrically connected to the main control board of the pneumatic control module. When the main control board drives the cylinder to start the movement of the impact pin, it outputs a trigger signal to the high-speed camera to start the high-speed camera to perform image acquisition, thereby synchronizing the timing of the impact pin movement and the image acquisition.

7. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 1, characterized in that: The droplet generation module also includes a height adjustment mechanism connected to the cylinder, which is used to adjust the installation height and initial position of the cylinder and the connected impact pin relative to the storage valve body, so as to precisely control the stroke length and impact energy of the impact pin.

8. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 7, characterized in that: The droplet generation module also includes a base, and the height adjustment mechanism and the storage valve body are disposed on the base. The height adjustment mechanism includes a lead screw lifting unit, a fine-tuning dial, and a locking component. The fine-tuning dial is connected to the lead screw of the lead screw lifting unit. By rotating the fine-tuning dial, the lead screw is driven to rise and fall in the vertical direction, thereby adjusting the installation position of the cylinder in the vertical direction. After the cylinder is adjusted to the target position, the locking component locks the relative position of the lead screw lifting unit and the cylinder to achieve stable holding of the cylinder position.

9. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 1, characterized in that: The nozzle is detachably connected to the storage valve body, and nozzles with different orifice diameters can be replaced to adjust the diameter of the generated droplets; the storage valve body is made of nickel-plated stainless steel; the heater includes a heating resistance wire, which is wound around the outside of the storage valve body and electrically connected to the temperature control module to achieve constant temperature heating of the storage valve body; the storage chamber is provided with a feeding port, which is detachably connected to a sealing cap.

10. The high-temperature metal single droplet control and generation device for droplet breakage experiments according to claim 1, characterized in that: The air pressure control module includes an air tank, a solenoid valve, and a main control board. The air tank is connected to the cylinder through the solenoid valve, and the solenoid valve is electrically connected to the main control board to control the opening and closing sequence of the solenoid valve. The outer wall of the cylinder is provided with a heat insulation layer to prevent the heat from the storage valve body from being conducted to the cylinder. The firing pin is made of stainless steel with a surface roughness Ra of no more than 0.8 μm. The firing pin is cylindrical with a conical lower end that faces the nozzle. The lower end face of the firing pin is hemispherical or arc-shaped. There is a radial gap between the firing pin and the firing pin channel, and the gap size is controlled within the range of 0.2 to 0.5 mm.

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