Method and device for forming large supercooled water droplets and impact test method and system

Abstract

This invention relates to the field of water droplet impact experiment technology, and particularly to a method, apparatus, and impact experiment method / system for forming large supercooled and supercooled water droplets. The method for forming large supercooled and supercooled water droplets includes: forming large water droplets; controlling the large water droplets to be in a suspended state; lowering the temperature of the large water droplets; and obtaining a first temperature of the large water droplets, wherein a large supercooled and supercooled water droplet is considered to be a large supercooled and supercooled water droplet when the first temperature is less than -10°C. The impact experiment method for large supercooled and supercooled water droplets includes: forming supercooled water droplets according to the method; controlling the free fall of the supercooled water droplets to impact a substrate; obtaining images of the dynamic phenomena of the supercooled water droplets impacting the substrate; and obtaining the mathematical model required for the experiment based on the images. This invention can achieve accurate and efficient control of the temperature of the supercooled water droplets, while accurately observing the phase transformation and nucleation phenomena during the impact experiment, facilitating the more realistic formation of the mathematical model required for the experiment.

Description

Technical Field

[0001] This invention relates to the field of water droplet impact experiment technology, and in particular to a method, apparatus, and impact experiment method and system for forming large supercooled and supercooled water droplets. Background Technology

[0002] When aircraft pass through clouds containing supercooled water droplets, icing occurs, which severely impacts flight safety: aircraft icing leads to increased drag, decreased lift, and premature stall; aircraft engine icing causes decreased thrust, compressor surge, and combustion chamber failure. Supercooled water droplets in clouds can be divided into two categories: one is conventional-sized supercooled water droplets, typically less than 40 μm in diameter, while droplets larger than 40 μm are usually referred to as large supercooled water droplets. Compared to conventional-sized supercooled water droplets, large supercooled water droplets typically splash and bounce upon impacting icy surfaces, altering the water collection rate on the surface. Furthermore, the secondary droplets formed by splashing and bouncing further ic up downstream.

[0003] The impact of supercooled large water droplets differs from the freezing of room-temperature water droplets in that phase transformation and nucleation occur simultaneously during the impact. This phase transformation and nucleation also influence the splashing and rebound dynamics of the water droplet impact. Existing splashing and rebound models for supercooled large water droplet impacts are based on room-temperature water droplet impact experiments and do not consider the effects of freezing and nucleation. Furthermore, existing studies on supercooled large water droplet impact experiments achieve supercooling by exchanging heat between room-temperature water droplets and their surrounding cold environment during free fall. However, due to the short free fall time, it is impossible to prepare supercooled water droplets with large degrees of supercooling, and the supercooling temperature of the water droplets is uncontrollable. Moreover, existing supercooled large water droplet impact experiments cannot observe the phase transformation and nucleation phenomena during the impact process.

[0004] Therefore, how to accurately and efficiently control the temperature of supercooled water droplets while accurately observing the phase transformation and nucleation phenomena during impact experiments has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide a method, apparatus, and experimental method / system for forming large supercooled and supercooled water droplets that overcomes or at least partially solves the above problems. The present invention is achieved as follows:

[0006] A method for forming large supercooled and supercooled water droplets includes:

[0007] Large water droplets are formed, with a diameter greater than 40 μm.

[0008] The large water droplets are kept in a suspended state.

[0009] Lower the temperature of the large water droplets;

[0010] The first temperature of the large water droplet is obtained. When the first temperature is less than -10℃, the large water droplet is a supercooled supercooled large water droplet.

[0011] Furthermore, the set temperature of the supercooled large water droplet is obtained, and the temperature of the environment in which the large water droplet is suspended is adjusted to a second temperature. The second temperature is equal to the set temperature. When the difference between the first temperature and the second temperature is within a preset range, the large water droplet is a supercooled large water droplet at the set temperature.

[0012] Furthermore, the large water droplets are kept in a suspended state by an ultrasonic levitation component.

[0013] Furthermore, the large water droplet is pure water;

[0014] The present invention also provides an apparatus for forming supercooled large water droplets, which performs a method for forming supercooled large water droplets, including:

[0015] Water droplet forming component, used to form large water droplets;

[0016] An ultrasonic levitation component is used to control the large water droplets to remain in a suspended state;

[0017] A low-temperature cold chamber is used to lower the temperature of the large water droplets;

[0018] A first temperature measuring component is used to obtain the first temperature of the large water droplet;

[0019] The second temperature measuring component is used to obtain the second temperature of the environment in which the large water droplet is located, wherein the environment in which the large water droplet is located is the low-temperature cold chamber.

[0020] This invention also provides a method for an experiment involving the impact of large supercooled and supercooled water droplets, comprising:

[0021] Supercooled large water droplets are formed according to a method for forming supercooled large water droplets;

[0022] Control the impact of the supercooled water droplets falling freely onto the substrate;

[0023] Image of the dynamic phenomenon when the supercooled large water droplet impacts the substrate is obtained;

[0024] The mathematical model required for the experiment is obtained based on the image.

[0025] Furthermore, the kinetic phenomena include splashing, rebounding, re-injection of secondary water droplets, and phase transformation nucleation.

[0026] Furthermore, an infrared camera was used to record the location and rate of nucleation.

[0027] This invention also provides a system for conducting a supercooled water droplet impact experiment, comprising:

[0028] A device for forming supercooled water droplets is provided for forming supercooled water droplets according to a supercooled water droplet forming method described above; wherein: an ultrasonic levitation component is used to control the free fall of the supercooled water droplets and their impact with the substrate.

[0029] The substrate is designed to impact supercooled large water droplets.

[0030] An observation device is used to acquire images of the dynamic phenomena when the supercooled large water droplets impact the substrate.

[0031] Furthermore, the observation device includes a high-speed camera and an infrared camera. The high-speed camera is used to acquire images of the splashing phenomenon, the rebound phenomenon, and the re-intrusion phenomenon of the secondary small water droplets when the supercooled large water droplets hit the substrate. The infrared camera is used to acquire images of the phase transformation nucleation phenomenon.

[0032] Furthermore, it also includes a third temperature measuring component and a temperature monitoring device connected to the substrate. The third temperature measuring component is used to measure the temperature of the fixed point to be measured when the supercooled water droplet impacts the substrate; the temperature monitoring device is used to record the measured value of the third temperature measuring component.

[0033] The technical solution adopted in this invention can achieve the following beneficial effects:

[0034] This invention uses an ultrasonic levitation component to keep large water droplets in a suspended state, with a uniform and stable shape. When exchanging heat with the surrounding cold environment, it can be faster and more uniform, and sufficient heat exchange can be achieved over a shorter travel distance to obtain large water droplets with high subcooling. Furthermore, since the large water droplets do not come into contact with other components, they are less likely to be contaminated with impurities and freeze, which is also conducive to the formation of large subcooled water droplets with high subcooling.

[0035] Because droplets undergo transient nucleation and freezing at certain locations after hitting the substrate surface, this process generates a large amount of phase transition heat, causing the local temperature to rise. Utilizing this phenomenon, this invention can obtain the location and rate of nucleation by recording with an infrared camera. Attached Figure Description

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1This is a schematic flowchart of a method for forming large water droplets with supercooling according to Embodiment 1 of the present invention;

[0038] Figure 2 This is a schematic diagram of the structure of a large supercooled supercooled large water droplet forming device according to Embodiment 2 of the present invention;

[0039] Figure 3 This is a flowchart illustrating a method for a large supercooled and supercooled water droplet impact experiment according to Embodiment 3 of the present invention.

[0040] Figure 4 This is a schematic diagram of the structure of a large supercooled and supercooled water droplet impact experimental system according to Embodiment 4 of the present invention;

[0041] In the diagram: 100-water droplet, 201-water droplet forming component, 202-ultrasonic levitation component, 203-low temperature cold chamber, 204-first temperature measuring component, 205-second temperature measuring component, 300-substrate, 401-high-speed camera, 402-infrared camera, 500-processing system, 600-third temperature measuring component, 700-temperature monitoring instrument, 800-cold light source. Detailed Implementation

[0042] The various aspects of the invention will be described more fully below with reference to the accompanying drawings. However, the invention can be embodied in many different forms and should not be construed as being limited to any particular structure or function presented throughout the invention. Rather, these aspects are provided to make the invention comprehensive and complete, and to provide those skilled in the art with a full understanding of its scope. Based on the teachings herein, those skilled in the art will recognize that the scope of the invention is intended to cover any aspect disclosed herein, whether implemented alone or in combination with any other aspect of the invention. For example, it can be implemented using any number of the means or methods presented herein. Furthermore, in addition to the various aspects of the invention presented herein, the scope of the invention is more intended to cover means or methods implemented using other structures, functions, or structures and functions. It should be understood that any aspect disclosed herein can be embodied by one or more elements of the claims.

[0043] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms "comprising," "including," etc., as used herein indicate the presence of the described features, steps, operations, and / or models, but do not exclude the presence or addition of one or more other features, steps, operations, or models.

[0044] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0045] Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0046] To make the contents, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0047] Example 1

[0048] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a method for forming large water droplets with supercooling and supercooling, as provided in Embodiment 1 of this application.

[0049] In this embodiment, the method includes:

[0050] Forming large water droplets 100, wherein the diameter of the large water droplets is greater than 40 μm;

[0051] The large water droplet 100 can be formed by the water droplet forming component 201 to form a pure water droplet with a diameter greater than 40 μm. Taking advantage of the property that pure water is not easy to freeze at negative temperatures, a supercooled large water droplet with a large degree of supercooling is formed. When the supercooled large water droplet collides with the substrate 300, the desired dynamic phenomenon is more easily observed.

[0052] Control the large water droplet 100 to remain suspended;

[0053] The suspended large water droplet 100 can be kept in a suspended state by an ultrasonic levitation component 202. It can be understood that the ultrasonic levitation component 202 is already in the activated state before the large water droplet 100 forms and falls. When suspended, the large water droplet 100 has a uniform and stable shape, allowing for faster and more uniform heat exchange with the surrounding cold environment. Furthermore, because the large water droplet 100 does not come into contact with other components during the cooling process, it is less prone to contamination and icing, allowing the formation of a highly subcooled large water droplet with a temperature less than -10℃.

[0054] In a suspended state, reduce the temperature of the large water droplet by 100°C;

[0055] After the large water droplet 100 is formed, it can be suspended in the low-temperature cold chamber 203. In one optional embodiment, the large water droplet 100 can be suspended first, and then the temperature of the large water droplet 100 can be lowered by reducing the temperature of the low-temperature cold chamber 203. This method may take a long time to cool down. In another preferred embodiment, the low-temperature cold chamber 203 is first brought to the required temperature before the large water droplet 100 is formed and suspended. The large water droplet 100 can exchange heat with the cold environment of the low-temperature cold chamber 203 to quickly form a supercooled large water droplet.

[0056] Obtain the first temperature of the large water droplet 100. When the first temperature is less than -10℃, the large water droplet 100 is a supercooled large water droplet with a large degree of subcooling.

[0057] In order to make the temperature of the supercooled water droplet controllable, the set temperature of the supercooled water droplet can be obtained, and the temperature of the environment in which the water droplet 100 is suspended can be adjusted to a second temperature. The second temperature is equal to the set temperature. When the difference between the first temperature and the second temperature is within a preset range, the water droplet 100 is the supercooled water droplet at the set temperature.

[0058] Those skilled in the art will understand that, typically, the ambient temperature is stabilized first, that is, the temperature of the low-temperature cold chamber is stabilized, and then a large water droplet is suspended in the low-temperature cold chamber to allow for sufficient heat exchange between the large water droplet and the low-temperature cold chamber. When the heat exchange between the large water droplet and the low-temperature cold chamber is sufficient, i.e., the temperature difference between the two is very small, the temperature of the supercooled large water droplet is uniform. The temperature control of the large water droplet using this method has higher precision.

[0059] Temperature can be obtained by using a first temperature measuring component 204 and a second temperature measuring component 205 to measure the first temperature of the large water droplet 100 and the second temperature of the environment in which the large water droplet 100 is located, respectively. This makes the supercooling temperature controllable during the formation of the supercooled large water droplet, which is beneficial for forming the supercooled large water droplet at the required temperature.

[0060] For example, if the required temperature for the target supercooled water droplet is -15°C, the temperature of the low-temperature cold chamber is first adjusted to -15°C. The two temperatures are then compared. When the difference is less than 0.1°C, the required temperature for the target supercooled water droplet is considered to have been reached. It is understood that 0.1°C is merely an example of an embodiment of this application, and the preset range can also be 0.5, 0.8, 1.0, etc., and can be adaptively adjusted according to experimental requirements. This application does not impose specific limitations in this regard.

[0061] Example 2

[0062] Corresponding to the above embodiment of the method for forming large water droplets with supercooling and supercooling, the present invention also provides an apparatus for forming large water droplets with supercooling and supercooling, please refer to... Figure 2 The schematic diagram shown illustrates the structure of a device for forming large supercooled and supercooled water droplets, which includes:

[0063] Large droplet forming component 201 is used to form large droplets 100, the diameter of which can be from 500 μm to 3 mm; the large droplet forming component 201 can be a micro-injector.

[0064] The ultrasonic levitation component 202 is used to control the large water droplet 100 to be in a levitation state when it is turned on, and to be turned off after the supercooled large water droplet is formed so that the supercooled large water droplet can fall freely and collide with the substrate 300. The falling height of the supercooled large water droplet can be controlled by changing the height of the ultrasonic levitation component 202 to simulate the impact process of supercooled large water droplets at different speeds.

[0065] The ultrasonic levitation component 202 can be an ultrasonic levitation device, which can levitate a large water droplet 100 using the standing wave levitation characteristics of ultrasonic waves. The ultrasonic levitation device has a through hole at its longitudinal axis, the diameter of which is larger than the diameter of the large water droplet, facilitating the entry of the large water droplet 100 from the droplet forming component 201 into the ultrasonic levitation device and allowing the large water droplet 100 to fall freely from the ultrasonic levitation device and impact the substrate 300. In one embodiment, the ultrasonic levitation device may include a transmitting end and a reflecting end, which are arranged opposite to each other. The transmitting end may include multiple ultrasonic emission points, and the reflecting end may include multiple ultrasonic reflection points corresponding to the ultrasonic emission points. In another embodiment, the ultrasonic levitation device includes two oppositely arranged transmitting ends, which may include multiple corresponding ultrasonic emission points.

[0066] Low-temperature cold chamber 203 is used to reduce the temperature of large water droplets 100;

[0067] The first temperature measuring component 204 is disposed outside the low-temperature cold chamber 203. For better measurement results, the first temperature measuring component 204 is horizontally positioned with the large water droplet 100 in a suspended state to acquire the first temperature of the large water droplet 100. By measuring the temperature with the first temperature measuring component 204, non-contact temperature measurement can be performed on the large water droplet 100, ensuring that the large water droplet 100 is not affected by the temperature measurement during the cooling process, which is more conducive to the formation of a supercooled large water droplet with a large degree of supercooling. The first temperature measuring component 204 can be an instrument with far-infrared thermometry capabilities, such as an infrared camera.

[0068] The second temperature measuring component 205 may be a thermocouple installed in the low-temperature cold chamber 203, used to obtain the second temperature of the low-temperature cold chamber 203 where the large water droplet 100 is located.

[0069] By comparing the difference between the first temperature and the second temperature, when the difference is within a preset range, the large water droplet 100 is considered a supercooled large water droplet.

[0070] The first temperature measuring component 204 and the second temperature measuring component 205 are used to measure the first temperature of the large water droplet 100 and the second temperature of the environment in which the large water droplet 100 is located, respectively, so that the supercooling temperature of the large water droplet 100 can be controlled during the formation of the supercooled large water droplet, which is conducive to the formation of the supercooled large water droplet at the required temperature.

[0071] Example 3

[0072] A method for experimental handling of large supercooled and supercooled water droplets impacting each other; please refer to [reference needed]. Figure 3 The flowchart shown is a method for an experiment involving the impact of a supercooled large water droplet, including:

[0073] Supercooled large water droplets are formed according to the method described in Example 1;

[0074] The formation of supercooled large water droplets can be accomplished using the supercooled large water droplet forming apparatus described in Example 2.

[0075] Control the impact of the supercooled large water droplet falling freely with the substrate 300;

[0076] When the large water droplet 100 is in a suspended state and forms a supercooled large water droplet, the supercooled large water droplet can be controlled to fall by directly turning off the ultrasonic levitation component 202, or the ultrasonic levitation component 202 can be connected to the processing system 500 and the ultrasonic levitation component 202 can be controlled by the processing system 500 to control the suspension and fall of the supercooled large water droplet.

[0077] Image of the dynamic phenomenon when a supercooled large water droplet impacts a substrate 300;

[0078] Images of the dynamic phenomena when a supercooled large water droplet impacts a substrate 300 can be obtained using an observation device. The substrate 300 can be the material that the experiment needs to simulate when it impacts a supercooled large water droplet, such as an aircraft surface material.

[0079] The dynamic phenomena include splashing, rebounding, re-injection of secondary water droplets, and phase transformation nucleation. The images can be photographs taken by the observation device. Among them:

[0080] The splashing, rebounding, and re-intrusion phenomena of secondary small water droplets can be captured by a high-speed camera 401. To ensure accuracy, at least two high-speed cameras 401 are required. One camera is positioned opposite the light source to capture a horizontal image of the supercooled water droplet impacting the substrate 300. The other camera is positioned higher on the same side as the light source to capture a tilted, top-down image of the supercooled water droplet impacting the substrate 300. The shooting positions and angles of the two high-speed cameras 401 can be adjusted according to experimental needs. Additional high-speed cameras 401 can also be added to capture more complete images from various angles; no restrictions are imposed here.

[0081] Phase transition nucleation can be captured by infrared camera 402. When a supercooled large water droplet impacts the surface of substrate 300, transient nucleation and freezing occur at certain locations. This process generates a large amount of phase transition heat, causing a local temperature increase. By recording the nucleation location and rate with infrared camera 402, the phase transition nucleation phenomenon during the impact can be obtained, allowing indirect observation of the phase transition nucleation phenomenon. The significance of observing phase transition nucleation lies in the fact that phase transition nucleation occurs simultaneously with the impact of the supercooled large water droplet on substrate 300. Phase transition nucleation also affects the dynamic phenomena such as splashing and rebound during the impact of the large water droplet. Therefore, observing phase transition nucleation is crucial for observing the splashing, rebounding, and re-intrusion phenomena of supercooled large water droplets.

[0082] The mathematical model required for the experiment is obtained from the image;

[0083] The image can be processed by the processing system 500 using image processing software such as Image-J to measure the size and position of the captured large water droplet 100 and calculate its velocity based on the time information recorded by the camera. Simultaneously, the system measures the spreading speed, rebound height, size and number of secondary water droplets, and ejection velocity of the large water droplet 100 during its impact with the wall, as well as the nucleation location and rate during phase transformation. A corresponding mathematical model is then obtained through fitting and modeling.

[0084] The mathematical model is valuable because studying the dynamics of supercooled large water droplet impacts is crucial for understanding supercooled large water droplet icing. Therefore, the numerical simulation of supercooled large water droplet icing requires first simulating splashing, rebound, and secondary droplet re-injection. Simulating splashing, rebound, and secondary droplet re-injection necessitates conducting basic supercooled large water droplet impact experiments, obtaining relevant data, analyzing the data, and fitting and modeling to derive the corresponding mathematical model.

[0085] Example 4

[0086] Corresponding to the above embodiment of the supercooled water droplet impact experiment method, the present invention also provides a supercooled water droplet impact experiment system, please refer to... Figure 4 The schematic diagram shown is of a supercooled large water droplet impact experimental system, including:

[0087] A large supercooled water droplet forming apparatus as described in Example 2 is used to form supercooled water droplets according to the method described in Example 1.

[0088] Substrate 300 is used to impact supercooled large water droplets;

[0089] The substrate 300 can be the material that the experiment needs to simulate impact with supercooled large water droplets, such as aircraft surface material.

[0090] An observation device is used to acquire images of the dynamic phenomena when the supercooled large water droplets impact the substrate 300;

[0091] The observation device includes a high-speed camera 401 and an infrared camera 402. Among them:

[0092] The high-speed camera 401 includes at least two units, used to observe the splashing, rebounding, and re-intrusion phenomena of supercooled large water droplets impacting the substrate 300. One unit is positioned opposite the illumination source to capture a horizontal photograph of the supercooled large water droplet impacting the substrate 300. The other unit is positioned higher on the same side as the light source to capture a tilted, top-down photograph of the supercooled large water droplet impacting the substrate 300. The shooting positions and angles of the two high-speed cameras 401 can be adjusted according to experimental needs. Additional high-speed cameras 401 can also be added to capture more complete images from more angles; no limitation is imposed here. The aforementioned light source can be a cold light source 800, with its emitting surface facing the impact area of ​​the supercooled large water droplet impacting the solid wall surface. This makes the images acquired by the observation device clearer and reduces the heating effect. The position of the cold light source 800 relative to the high-speed camera 401 provides better supplementary lighting, resulting in clearer images.

[0093] In order to more accurately measure the size of the images captured by the high-speed camera 401, the high-speed camera 401 needs to be calibrated for the actual size of the captured images before use. This can be done using a standard calibration grid.

[0094] Infrared camera 402 is used to observe the phase transformation nucleation phenomenon when supercooled large water droplets collide. After supercooled large water droplets collide with the surface of substrate 300, transient nucleation and freezing phenomena will occur at some locations. This process will generate a large amount of phase transformation heat, causing the local temperature to rise. By recording the location and rate of nucleation by infrared camera 402, the phase transformation nucleation phenomenon during the collision process can be obtained, and the impact phase transformation nucleation phenomenon can be indirectly observed.

[0095] The infrared camera 402 may exhibit temperature deviations during observation, necessitating calibration. Therefore, a third temperature measuring component 600 and a temperature monitoring device 700 are used for calibration. The third temperature measuring component 600 measures the temperature at a fixed point when the supercooled water droplet impacts the substrate 300, while the temperature monitoring device 700 records the measured values. The third temperature measuring component 600 is connected to the processing system 500 via the temperature monitoring device 700. The third temperature measuring component 600 can be a thermocouple, with its working end located on the surface of the substrate 300. Specifically, this can be achieved by providing a vertical mounting hole in the substrate 300, placing the thermocouple in the hole with its working end facing upwards towards the surface of the substrate 300, and measuring the temperature change on the surface of the substrate 300.

[0096] Calibration can be divided into pre-experiment calibration and post-experiment calibration. Before starting the experiment, the recorded data from the temperature monitoring instrument 700 and the observed data from the infrared camera 402 are compared. If the difference between the measured value of the infrared camera 402 and the measured value of the third temperature measuring component 600 at the same location is outside the preset range, the settings of the infrared camera 402 are adjusted to improve the measurement accuracy. After completing the experiment, the observed results of the infrared camera 402 are compared with the records of the temperature monitoring instrument 700. If the difference between the measured value of the infrared camera 402 and the recorded value of the temperature monitoring instrument 700 at the same location is outside the preset range, the measurement results of the infrared camera 402 are adjusted to make the data more accurate. Simultaneously, the third temperature measuring component 600 and the temperature monitoring instrument 700 can also calibrate the first temperature measuring component 204.

[0097] Processing system 500 is used to obtain the mathematical model required for the experiment based on the image;

[0098] The processing system 500 is connected to the ultrasonic levitation component 202, the first temperature measuring component 204, the second temperature measuring component 205, the temperature detector 700, and the observation device. The processing system 500 reads the measured values ​​of the first temperature measuring component 204 and the second temperature measuring component 205, and determines whether the difference between the first temperature and the second temperature is within a preset range. If the difference is within the preset range, the levitation function of the ultrasonic levitation component 202 is turned off. The processing system 500 can acquire the recorded values ​​of the temperature detector 700 and the images captured by the observation device. The measurement results of the observation device are calibrated using the values ​​of the temperature detector 700. After calibration, image processing software such as Image-J is used to measure the size and position of the captured large water droplet 100 and calculate information such as velocity based on the time information recorded by the camera. At the same time, the spreading speed, rebound height, size and number of secondary small water droplets, and ejection velocity of the large water droplet 100 during impact with the wall are measured, as well as the nucleation position and nucleation rate during phase transformation nucleation. A fitting model is then used to obtain the corresponding mathematical model. The processing system 500 facilitates the acquisition of data and control of devices, improving experimental efficiency. The processing system 500 directly acquires results, reducing the likelihood of human error and increasing experimental accuracy.

[0099] This invention provides an embodiment of a method, apparatus, and experimental method / system for forming supercooled and supercooled large water droplets. Because an ultrasonic levitation component 202 is used to suspend the large water droplet 100, the droplet 100 maintains a uniform and stable shape during suspension. This allows for faster and more uniform heat exchange with the surrounding cold environment. Furthermore, since the large water droplet 100 does not contact other components, it is less prone to contamination and icing, thus enabling the formation of supercooled large water droplets with high supercooling. Additionally, two high-speed cameras 401 at different positions and heights are used to acquire images of the splashing, rebound, and re-intrusion phenomena of secondary small water droplets when the supercooled large water droplet impacts the substrate 300. Comparing these images from two different angles makes the experimental results more accurate and comprehensive. An infrared camera 402 is used to acquire images of the phase transformation nucleation phenomenon, allowing for the determination of the nucleation location and rate, facilitating the formation of a more realistic mathematical model for the experiment. This is of significant importance for studying the icing of supercooled water droplets.

[0100] Finally, it should be noted that, unless otherwise specified, the above embodiments and features can be combined with each other. The above embodiments are merely illustrative of the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

Claims

1. A method for an experiment involving the impact of large supercooled and supercooled water droplets, characterized in that, include: The formation of supercooled large water droplets; Control the impact of the supercooled water droplets falling freely onto the substrate; Images of the dynamic phenomena of the supercooled large water droplets impacting the substrate are obtained; the dynamic phenomena include splashing, rebounding, re-injection of secondary small water droplets, and phase transformation nucleation. Infrared cameras were used to record the location and rate of nucleation. The mathematical model required for the experiment is obtained based on the image. The formation of supercooled large water droplets includes: Large water droplets are formed, with a diameter greater than 40 μm; The large water droplets are kept in a suspended state. In the suspended state, the temperature of the large water droplets is reduced; The first temperature of the large water droplet is obtained. When the first temperature is less than -10℃, the large water droplet is a supercooled large water droplet with a large degree of supercooling.

2. A large supercooled and supercooled water droplet impact experimental system, characterized in that, The method for performing a large supercooling and supercooling water droplet impact experiment as described in claim 1 includes a large supercooling and supercooling water droplet forming device, wherein the large supercooling and supercooling water droplet forming device includes: a water droplet forming component for forming large water droplets; An ultrasonic levitation component is used to control the large water droplets to remain in a suspended state; A low-temperature cold chamber is used to lower the temperature of the large water droplets; A first temperature measuring component is used to obtain the first temperature of the large water droplet; The second temperature measuring component is used to obtain the second temperature of the environment where the large water droplet is located, wherein the environment where the large water droplet is located is the low-temperature cold chamber; The system includes: an ultrasonic levitation component to control the cooling of the supercooled water droplet in a suspended state, and a free-falling supercooled water droplet that impacts a substrate when the ultrasonic levitation component is turned off; a substrate for impacting the supercooled water droplet; and an observation device for acquiring images of the dynamic phenomena of the supercooled water droplet impacting the substrate. The ultrasonic levitation component has a through hole at its longitudinal axis. The diameter of the through hole is larger than the diameter of the large water droplet, which facilitates the large water droplet entering the ultrasonic levitation component from the water droplet forming component and allows the large water droplet to fall freely from the ultrasonic levitation component and impact the substrate.

3. The experimental system for impacting large supercooled and supercooled water droplets according to claim 2, characterized in that, The observation device includes a high-speed camera and an infrared camera. The high-speed camera is used to acquire images of the splashing phenomenon, the rebound phenomenon, and the re-intrusion phenomenon of the secondary small water droplets when the supercooled large water droplets hit the substrate. The infrared camera is used to acquire images of the phase transformation nucleation phenomenon.

4. The experimental system for impacting large supercooled and supercooled water droplets according to claim 3, characterized in that, It also includes a third temperature measuring component and a temperature monitoring device connected to the substrate. The third temperature measuring component is used to measure the temperature of the fixed point to be measured when the supercooled water droplet hits the substrate. The temperature monitoring device is used to record the measured value of the third temperature measuring component.

Images