CN116698902A - Method and device for forming large supercooled water drops with high supercooling degree, impact experiment method and system - Google Patents
Method and device for forming large supercooled water drops with high supercooling degree, impact experiment method and system Download PDFInfo
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Abstract
The application relates to the technical field of water drop impact experiments, in particular to a method and a device for forming large supercooled water drops with high supercooling degree, and an impact experiment method and a system, wherein the method for forming the large supercooled water drops with high supercooling degree comprises the following steps: forming large water drops; controlling the large water drops to be in a suspension state; reducing the temperature of the large water drops; and obtaining a first temperature of the large water drops, and when the first temperature is less than-10 ℃, obtaining the large water drops with large supercooling degree. The large supercooling degree supercooled large water drop impact experiment method comprises the following steps: forming supercooled large water drops according to a large supercooling degree supercooling large water drop forming method; controlling the free falling body of the supercooled large water drop to collide with the substrate; acquiring an image of a dynamic phenomenon when supercooled large water drops strike a substrate; and obtaining a mathematical model required by the experiment according to the image. The application can accurately and efficiently control the temperature of supercooled large water drops, and accurately observe the phase change nucleation phenomenon in the impact experiment process, thereby being convenient for more truly forming a mathematical model required by the experiment.
Description
Technical Field
The application relates to the technical field of water drop impact experiments, in particular to a method and a device for forming large supercooled water drops with high supercooling degree, and an impact experiment method and a system.
Background
Icing occurs when an aircraft passes through a cloud layer containing supercooled water drops, and the flight safety of the aircraft is seriously affected by the icing: the aircraft icing can lead to resistance rising, lift falling and stall advancing, and the aeroengine icing can lead to thrust falling, compressor surge, combustion chamber flameout and the like. Supercooled water droplets in cloud layers can be divided into two categories: one type is a conventional scale supercooled water droplet typically less than 40 μm in diameter, while water droplets greater than 40 μm in diameter are commonly referred to as supercooled large water droplets. Compared with supercooled water drops with conventional size, after the supercooled large water drops strike the icing surface, splashing, rebound and the like can usually occur, so that the water collection rate of the wall surface is changed, and meanwhile, secondary small water drops formed by splashing and rebound can further ice downstream.
The supercooled large water drop impacts are different from normal temperature water drop icing, and phase change nucleation phenomenon can occur in the impact process. The phase change nucleation phenomenon can influence the dynamic phenomena such as splashing, rebound and the like in the water drop impact process. The existing splash rebound models of supercooled large water drop impact are all obtained based on normal-temperature water drop impact experiments, and the influence of freezing nucleation is not considered. Meanwhile, in the existing research supercooling large water drop impact experiment, normal-temperature water drops are subjected to heat exchange with surrounding cold environment in the free falling process, so that supercooling of the water drops is realized, the preparation of supercooled water drops with large supercooling degree cannot be realized due to short free falling time, and meanwhile, the supercooling temperature of the water drops is uncontrollable. In addition, the existing supercooled large water drop impact experiment cannot observe the phase change nucleation phenomenon in the impact experiment process.
Therefore, how to accurately and efficiently control the temperature of supercooled water drops and accurately observe the phase change nucleation phenomenon in the impact experiment process becomes a technical problem to be solved by those skilled in the art.
Disclosure of Invention
In view of the foregoing, it is an object of the present application to provide a method, apparatus, and a large supercooled large water droplet impingement experiment method, system for overcoming or at least partially solving the foregoing problems. The application is realized in the following way:
a method for forming large supercooled water drops with high supercooling degree, comprising:
forming large water droplets, the large water droplets having a diameter greater than 40 μm;
controlling the large water drops to be in a suspension state;
reducing the temperature of the large water droplets;
and acquiring a first temperature of the large water drop, wherein when the first temperature is lower than-10 ℃, the large water drop is the large supercooled water drop with large supercooling degree.
Further, a set temperature of supercooled large water drops is obtained, the temperature of the environment where the large water drops are in a suspension state is regulated to be a second temperature, the second temperature is equal to the set temperature, and when the difference value between the first temperature and the second temperature is in a preset range, the large water drops are supercooled large water drops with the set temperature.
Further, the large water drops are controlled to be in a suspended state by the ultrasonic suspension component.
Further, the large water droplets are pure water;
the present application also provides a supercooled large water droplet forming apparatus, which performs a supercooled large water droplet forming method, comprising:
a water droplet forming part for forming large water droplets;
the ultrasonic suspension component is used for controlling the large water drops to be in a suspension state;
a cryogenic cooling chamber for reducing the temperature of the large water droplets;
a first temperature measurement means for acquiring a first temperature of the large water droplet;
the second temperature measuring component is used for acquiring a second temperature of the environment where the large water drop is located, wherein: the environment where the large water drops are located is the low-temperature cold chamber.
The application also provides a large supercooling degree supercooled large water drop impact experiment method, which comprises the following steps:
forming supercooled large water droplets according to a supercooled large water droplet forming method;
controlling the supercooled large water drops to freely fall and collide with the substrate;
acquiring an image of a dynamic phenomenon when the supercooled large water drops strike the substrate;
and obtaining a mathematical model required by the experiment according to the image.
Further, the dynamic phenomenon includes a splash phenomenon, a rebound phenomenon, a re-injection phenomenon of secondary water droplets, and a phase change nucleation phenomenon.
Further, the location at which nucleation occurred, as well as the nucleation rate, was recorded using an infrared camera.
The application also provides a large supercooling degree supercooled large water drop impact experiment system, which executes a supercooling large water drop impact experiment method, comprising the following steps:
a large supercooling degree supercooling large water drop forming apparatus for forming supercooling large water drops according to the supercooling large water drop forming method; wherein: the ultrasonic suspension component is used for controlling the supercooled large water drop to freely fall and collide with the substrate;
a base plate for striking with supercooled large water droplets;
and the observation device is used for acquiring an image of the dynamic phenomenon when the supercooled large water drops strike the substrate.
Further, the observation device comprises a high-speed camera and an infrared camera, wherein the high-speed camera is used for acquiring images of splashing phenomenon, rebound phenomenon and re-injection phenomenon of secondary water droplets when the supercooled large water droplets strike the substrate, and the infrared camera is used for acquiring images of phase-change nucleation phenomenon.
Further, the device also comprises a third temperature measuring component and a temperature inspection instrument, wherein the third temperature measuring component is connected with the substrate and is used for measuring the temperature of a fixed point required to be measured when the supercooled large water drops impact the substrate; the temperature patrol instrument is used for recording the measured value of the third temperature measuring component.
The technical scheme adopted by the application can achieve the following beneficial effects:
the application adopts the ultrasonic suspension component to make the large water drop in suspension state, has uniform and stable shape, can be more rapid and uniform when exchanging heat with the surrounding cold environment, and can fully exchange heat under a shorter distance to obtain the large water drop with large supercooling degree; the large water drops are not contacted with other parts, so that the large water drops are not easy to be polluted and frozen, and the large supercooled water drops with large supercooling degree are formed;
the liquid drop can generate transient nucleation freezing phenomenon at some positions after striking the surface of the substrate, and a great amount of phase change heat can be generated in the process, so that the local temperature is increased, and by utilizing the phenomenon, the nucleation position and the nucleation rate can be obtained through the infrared camera record.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for forming large supercooled water droplets in accordance with embodiment 1 of the present application;
FIG. 2 is a schematic diagram of a large supercooled water droplet forming apparatus according to embodiment 2 of the present application;
FIG. 3 is a schematic flow chart of an experimental method for large supercooled water droplet impingement of embodiment 3 of the present application;
FIG. 4 is a schematic diagram of a large supercooled large water droplet impact experiment system according to embodiment 4 of the present application;
in the figure: 100-water drops, 201-water drop forming parts, 202-ultrasonic suspension parts, 203-a low-temperature cold room, 204-a first temperature measuring part, 205-a second temperature measuring part, 300-a substrate, 401-a high-speed camera, 402-an infrared camera, 500-a processing system, 600-a third temperature measuring part, 700-a temperature inspection instrument and 800-a cold light source.
Detailed Description
Aspects of the application will be described more fully hereinafter with reference to the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this application. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. Based on the teachings herein one skilled in the art will recognize that the scope of the present application is intended to cover any aspect disclosed herein, whether alone or in combination with any other aspect of the present application. For example, any number of the apparatus or implementations set forth herein may be implemented. In addition, the scope of the present application is intended to encompass other structures, functions, or devices or methods implemented using structures and functions in addition to the aspects of the application set forth herein. It should be understood that it may embody any aspect disclosed herein by one or more elements of the claims.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or "includes" when used herein, specify the presence of stated features, steps, operations, and/or models, but do not preclude the presence or addition of one or more other features, steps, operations, or models.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
In order to make the day, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to the accompanying drawings and examples.
Example 1
Referring to fig. 1, fig. 1 is a flow chart of a method for forming large supercooled water drops according to embodiment 1 of the present application.
In this embodiment, the method includes:
forming large water droplets 100, the large water droplets having a diameter greater than 40 μm; the method comprises the steps of carrying out a first treatment on the surface of the
The large water droplets 100 can form pure water droplets having a diameter of more than 40 μm using the water droplet forming part 201, and can form supercooled large water droplets having a large supercooling degree by utilizing the property that pure water is not easily frozen at a negative temperature, and a desired kinetic phenomenon can be more easily observed when the supercooled large water droplets collide with the substrate 300.
Controlling the large water droplets 100 to be in a suspended state;
the suspension of the large water droplets 100 can adopt the ultrasonic suspension member 202 to suspend the large water droplets 100, it is understood that before the large water droplets 100 are formed and fall, the ultrasonic suspension member 202 is in an open state, the large water droplets 100 are suspended in a uniform and stable shape, and can be more quickly and uniformly heat exchanged with the surrounding cold environment, and as the large water droplets 100 are not contacted with other members in the cooling process, impurities are not easy to be contaminated and frozen, supercooled large water droplets with a large supercooling degree can be formed, the temperature of the supercooled large water droplets with a large supercooling degree is less than-10 ℃,
in a suspended state, the temperature of the large water droplets 100 is lowered;
the formation of the large water droplets 100 may be followed by suspension in the cryocooler 203. In an alternative embodiment, the large water droplets 100 may be suspended before the temperature of the large water droplets 100 is reduced by reducing the temperature of the cryocooler 203, which may result in a longer cooling time. In another preferred embodiment, the large water droplets 100 are formed after the cryogenic cooling chamber 203 is brought to a desired temperature and the large water droplets 100 are suspended, and the large water droplets 100 can exchange heat with the cold environment of the cryogenic cooling chamber 203 to quickly form supercooled large water droplets.
The first temperature of the large water droplets 100 is obtained, and when the first temperature is less than-10 ℃, the large water droplets 100 are supercooled large water droplets with large supercooling degree.
In order to make the temperature of the supercooled large water droplets controllable, the temperature of the environment where the large water droplets 100 are in a suspended state can be adjusted to be a second temperature by acquiring the set temperature of the supercooled large water droplets, the second temperature is equal to the set temperature, and when the difference between the first temperature and the second temperature is within a preset range, the large water droplets 100 are the supercooled large water droplets with the set temperature.
It will be appreciated by those skilled in the art that the ambient temperature is usually stabilized, i.e. the temperature of the low-temperature cooling chamber is stabilized, and then the large water droplets are suspended in the low-temperature cooling chamber, so that the large water droplets exchange heat with the low-temperature cooling chamber sufficiently, and when the large water droplets exchange heat with the low-temperature cooling chamber sufficiently, i.e. the temperature difference between the large water droplets and the low-temperature cooling chamber is small, the temperature of the supercooled large water droplets is uniform. The temperature of the large water drop controlled by the method has higher control precision.
The first temperature measuring component 204 and the second temperature measuring component 205 can be used for measuring the first temperature of the large water drop 100 and the second temperature of the environment where the large water drop 100 is located, so that the supercooling temperature of the large water drop 100 in the process of forming the supercooled large water drop can be controlled, and the supercooled large water drop with the required temperature can be formed easily.
For example, the temperature of the target supercooled large water droplet is required to be-15 ℃, the temperature of the low-temperature cooling chamber is firstly adjusted to be-15 ℃, the temperature of the low-temperature cooling chamber and the temperature of the low-temperature cooling chamber are compared, and when the difference is smaller than 0.1 ℃, the target supercooled large water droplet is considered to be reached. It can be understood that the temperature of 0.1 ℃ is only an example of the embodiment of the present application, the preset range may be preset values of 0.5, 0.8, 1.0, etc., and the preset values may be adaptively adjusted according to experimental requirements, which is not particularly limited by the present application.
Example 2
In response to the embodiment of the method for forming a large supercooled water droplet, the present application further provides a device for forming a large supercooled water droplet, referring to fig. 2, which is a schematic structural diagram of a device for forming a large supercooled water droplet, and includes:
a large water droplet forming part 201 for forming large water droplets 100, the diameter of which large water droplets 100 may be 500 μm to 3mm; the large water droplet forming part 201 may be a microliter syringe.
The ultrasonic suspension component 202 is used for controlling the large water drops 100 to be in a suspension state when being opened, closing the ultrasonic suspension component after the supercooled large water drops are formed and enabling the supercooled large water drops to freely fall to collide with the substrate 300, the falling height of the supercooled large water drops can be controlled by changing the height of the ultrasonic suspension component 202, and the supercooled large water drop collision process with different speeds can be simulated.
The ultrasonic suspension component 202 may be an ultrasonic suspension instrument, the ultrasonic suspension instrument can realize suspension of the large water drop 100 through standing wave suspension characteristics of ultrasonic waves, a through hole is arranged at the longitudinal axis of the ultrasonic suspension instrument, the diameter of the through hole is larger than that of the large water drop, the large water drop 100 is convenient to enter the ultrasonic suspension instrument from the water drop formation component 201, and the large water drop 100 is convenient to freely fall from the ultrasonic suspension instrument to collide with the substrate 300. In one embodiment, the ultrasonic levitation instrument may include a transmitting end and a reflecting end disposed opposite to each other, the transmitting end may include a plurality of ultrasonic transmitting points, and the reflecting end may include a plurality of ultrasonic reflecting points corresponding to the ultrasonic transmitting points. In another embodiment, the ultrasonic suspension instrument comprises two opposite emitting ends, and the two emitting ends can comprise a plurality of ultrasonic emitting points corresponding to each other.
A cryogenic cooling chamber 203 for reducing the temperature of the large water droplets 100;
the first temperature measuring part 204 is disposed outside the cryocooling chamber 203, and for better measuring effect, the first temperature measuring part 204 is disposed horizontally with the large water droplets 100 in a suspended state for obtaining the first temperature of the large water droplets 100. The temperature measurement by the first temperature measurement component 204 can be performed in a non-contact manner with the large water drop 100, so that the large water drop 100 is not affected by the temperature measurement in the cooling process, and the formation of supercooled large water drops with large supercooling degree is facilitated. The first temperature measurement component 204 may be an instrument with far infrared thermometry functionality, such as an infrared camera.
The second temperature measuring part 205 may be a thermocouple provided in the low temperature cooling chamber 203 for acquiring a second temperature of the low temperature cooling chamber 203 where the large water droplets 100 are located.
By comparing the difference between the first temperature and the second temperature, the large water droplet 100 is a supercooled large water droplet when the difference is within a predetermined range.
The first temperature measuring part 204 and the second temperature measuring part 205 are adopted to measure the first temperature of the large water drop 100 and the second temperature of the environment where the large water drop 100 is positioned, so that the supercooling temperature of the large water drop 100 is controllable in the process of forming the supercooled large water drop, and the supercooled large water drop with the required temperature is formed.
Example 3
Referring to fig. 3, a flow chart of a large supercooled water drop impact experiment method includes:
supercooled large water droplets were formed as described in example 1;
the formation of supercooled large water droplets can be accomplished by the supercooled large water droplet forming apparatus described in example 2.
Controlling the supercooled large water drops to freely fall to collide with the substrate 300;
after the supercooled large water droplets 100 are in a suspended state and formed, the supercooled large water droplets can be controlled to fall by directly closing the ultrasonic suspension member 202, or the ultrasonic suspension member 202 is connected with the processing system 500, and the suspension and the falling of the supercooled large water droplets can be controlled by controlling the switching of the ultrasonic suspension member 202 through the processing system 500.
Acquiring an image of a dynamic phenomenon when supercooled large water droplets strike the substrate 300;
an image of the dynamics of the supercooled large water droplets striking the substrate 300 may be obtained by an observation device, and the substrate 300 may be a material that is required to be simulated for experiments to strike the supercooled large water droplets, such as an aircraft surface material.
The dynamic phenomena comprise splashing phenomenon, rebound phenomenon, re-injection phenomenon of secondary water droplets and phase change nucleation phenomenon, and the image can be a photo taken by an observation device. Wherein:
the splash phenomenon, the rebound phenomenon, and the re-injection phenomenon of the secondary water droplets can be shot by the high-speed camera 401, and at least two high-speed cameras 401 are required to ensure the shooting accuracy, one of the cameras is arranged opposite to the light source for providing illumination, and is used for shooting a horizontal state picture when the supercooled water droplets strike the substrate 300, and the other is arranged at a higher position on the same side as the light source, and is used for shooting an inclined overlook state picture when the supercooled water droplets strike the substrate 300. According to the experiment, the shooting positions and shooting angles of the two high-speed cameras 401 can be adjusted, and the high-speed cameras 401 can be increased to shoot, so that more complete images with more angles can be obtained, and the method is not limited.
The phase-change nucleation phenomenon can be shot through the infrared camera 402, transient nucleation freezing phenomenon can occur at some positions after supercooled large water drops strike the surface of the substrate 300, a large amount of phase-change heat can be generated in the process, the local temperature is increased, the nucleation position and the nucleation rate can be obtained through the recording of the infrared camera 402, and the phase-change nucleation phenomenon in the striking process is indirectly observed. The effect of observing the phase-change nucleation is that the phase-change nucleation occurs simultaneously in the process of the supercooled large water droplets striking the substrate 300. The phase change nucleation phenomenon can influence the dynamic phenomena such as splashing and rebound in the process of large water drop impact, so that the observation of the phase change nucleation phenomenon plays an important role in observing the splashing phenomenon, rebound phenomenon, re-injection phenomenon of secondary small water drops and the like of supercooled large water drops.
Obtaining a mathematical model required by an experiment according to the image;
the Image may be processed by the processing system 500, and the size and position of the captured large water droplets 100 may be measured using Image processing software such as Image-J, etc., and information such as speed may be calculated from time information recorded by the camera. And simultaneously, measuring information such as spreading speed, rebound height, size, number and emergent speed of secondary small water drops on the wall surface in the impact process of the large water drops 100, and the nucleation position and nucleation rate during phase change nucleation, and fitting and modeling to obtain a corresponding mathematical model.
The obtained mathematical model has the effect that the research on the dynamics phenomenon of the impact of the supercooled large water drops is of great significance to the research on the icing of the supercooled large water drops. Therefore, in the icing numerical simulation process of supercooled large water drops, the phenomena of splashing, rebound and secondary small water drops re-incidence need to be simulated first. And simulation of splashing, rebound and secondary water droplet re-incidence requires developing basic supercooled large water droplet impact experiments, analyzing and fitting modeling after obtaining relevant data to obtain corresponding mathematical models.
Example 4
Corresponding to the embodiment of the above-mentioned method for performing the large supercooling degree supercooling large water drop impact experiment, the present application further provides a supercooling large water drop impact experiment system, please refer to a schematic structural diagram of the supercooling large water drop impact experiment system shown in fig. 4, which includes:
a large supercooled large water drop formation apparatus according to embodiment 2, which is configured to form supercooled large water drops according to the method of embodiment 1;
a base plate 300 for striking with supercooled large water droplets;
the substrate 300 may be a material that is simulated to impinge on supercooled large water droplets as required for experimentation, such as aircraft surface material.
An observation device for acquiring an image of a dynamic phenomenon when the supercooled large water droplets strike the substrate 300;
the observation device includes a high-speed camera 401 and an infrared camera 402. Wherein:
the high-speed camera 401 includes at least two cameras for observing a splash phenomenon, a rebound phenomenon and a re-injection phenomenon of secondary water droplets when the supercooled large water droplets strike, one of which is disposed opposite to a light source for providing illumination for taking a horizontal state photograph when the supercooled large water droplets strike the substrate 300, and the other of which is located at a higher position on the same side as the light source for taking an inclined top view photograph when the supercooled large water droplets strike the substrate 300. According to the experiment, the shooting positions and shooting angles of the two high-speed cameras 401 can be adjusted, and the high-speed cameras 401 can be increased to shoot, so that more complete images with more angles can be obtained, and the method is not limited. The light source may be a cold light source 800, and the light emitting surface is opposite to the impact area when the supercooled large water drop impacts the solid wall surface, so that the image obtained by the observation device is clearer, the heating effect is reduced, and the position of the cold light source 800 is opposite to the high-speed camera 401, so that the obtained image is clearer.
In order to more accurately measure the size of the image captured by the high speed camera 401, the high speed camera 401 needs to calibrate the pixels on the captured image for the actual size before use, which can be calibrated using a standard calibration grid.
The infrared camera 402 is used for observing a phase change nucleation phenomenon when supercooled large water drops strike, transient nucleation freezing phenomenon can occur at some positions after supercooled large water drops strike the surface of the substrate 300, a large amount of phase change heat can be generated in the process, the local temperature is increased, the nucleation position and the nucleation rate can be obtained through recording of the infrared camera 402, and the phase change nucleation phenomenon in the striking process is indirectly observed.
The infrared camera 402 may have a temperature deviation, and thus, calibration adjustment is required, so that the third temperature measurement component 600 and the temperature inspection device 700 are used for calibration, the third temperature measurement component 600 is used for measuring the temperature of the fixed point required to be measured when the supercooled large water drop hits the substrate 300, and the temperature inspection device 700 is used for recording the measured value of the third temperature measurement device. The third temperature measuring part 600 is connected with the processing system 500 through the temperature inspection device 700, and the third temperature measuring part 600 may be a thermocouple, the working end of which is located on the surface of the substrate 300, specifically, the thermocouple may be disposed in a mounting hole by disposing a vertical mounting hole on the substrate 300, and meanwhile, the working end of the thermocouple faces upwards to the surface of the substrate 300 for measuring the temperature change of the surface of the substrate 300.
The calibration can be classified into a calibration before the experiment and a calibration after the experiment. Before the experiment is started, the recorded data of the temperature inspection instrument 700 and the observed data of the infrared camera 402 are compared, and if the difference value between the measured value of the infrared camera 402 and the measured value of the third temperature measurement component 600 at the same position is out of the preset range, the setting of the infrared camera 402 is adjusted, so that the measurement accuracy is improved. After the experiment is completed, the observation result of the infrared camera 402 is compared with the record of the temperature inspection instrument 700, and if the difference value between the measured value of the infrared camera 402 and the record of the temperature inspection instrument 700 at the same position is out of the preset range, the measurement result of the infrared camera 402 is adjusted to make the data more accurate. Meanwhile, the third temperature measuring part 600 and the temperature patrol instrument 700 may also calibrate the first temperature measuring part 204.
A processing system 500 for deriving a mathematical model required for the experiment from the image;
the processing system 500 is connected with the ultrasonic suspending component 202, the first temperature measuring component 204, the second temperature measuring component 205, the temperature inspection instrument 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, judges whether the difference value between the first temperature and the second temperature is within a preset range, and if the difference value between the first temperature and the second temperature is within the preset range, the suspending function of the ultrasonic suspending component 202 is turned to be in a closed state. The processing system 500 may acquire recorded values of the temperature patrol 700 and images captured by the observation device. The measurement result of the observation device is calibrated by the value of the temperature patrol instrument 700. After calibration, image processing software such as Image-J is adopted to measure the size and position of the large water drop 100 obtained by shooting and calculate information such as speed according to the time information recorded by the camera. And simultaneously, measuring information such as spreading speed, rebound height, size, number and emergent speed of secondary small water drops on the wall surface in the impact process of the large water drops 100, and the nucleation position and nucleation rate during phase change nucleation, and fitting and modeling to obtain a corresponding mathematical model. The data information or the control device can be conveniently acquired through the action of the processing system 500, the experimental efficiency is improved, the manual operation error is not easy to occur when the processing system 500 directly acquires the result, and the experimental accuracy is higher.
According to the embodiment of the method and the device for forming the supercooled large water drops with high supercooling degree and the method and the system for performing the impact experiment on the supercooled large water drops with high supercooling degree, the ultrasonic suspension component 202 is adopted to enable the large water drops 100 to be in a suspension state, so that the shape of the large water drops 100 is uniform and stable during suspension, the large water drops 100 can be more quickly and uniformly exchanged with the surrounding cold environment, and the large water drops 100 are not contacted with other components, are not easy to be polluted by impurities and freeze, and can form supercooled large water drops with high supercooling degree. In addition, the images of the splashing phenomenon, the rebound phenomenon and the re-injection phenomenon of the secondary water droplets when the supercooled large water droplets strike the substrate 300 are acquired by adopting the two high-speed cameras 401 with different positions and different heights, and the experimental results are more accurate and stereoscopic by comparing the images at two angles. The infrared camera 402 is adopted to acquire the image of the phase change nucleation phenomenon, so that the nucleation position and nucleation rate can be obtained, a mathematical model required by an experiment can be formed more truly, and the method has important significance for researching the icing of supercooled water drops.
Finally, it should be noted that: the above embodiments and features of the embodiments may be combined with each other without conflict. The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be appreciated by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not drive the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.
Claims (10)
1. A method for forming large supercooled water droplets with a large supercooling degree, comprising:
forming large water droplets, the large water droplets having a diameter greater than 40 μm;
controlling the large water drops to be in a suspension state;
in the suspended state, reducing the temperature of the large water droplets;
and acquiring a first temperature of the large water drop, wherein when the first temperature is lower than-10 ℃, the large water drop is a supercooled large water drop with large supercooling degree.
2. The method for forming supercooled water droplets with high supercooling degree according to claim 1, wherein a set temperature of supercooled large water droplets is obtained, a temperature of an environment in which the large water droplets are in a suspended state is adjusted to be a second temperature, the second temperature is equal to the set temperature, and when a difference between the first temperature and the second temperature is within a preset range, the large water droplets are oversized water droplets with the set temperature.
3. The method for forming supercooled large water droplets of claim 1, wherein the water droplets are controlled to be in a suspended state by an ultrasonic suspending means.
4. A large supercooled water droplet forming apparatus, characterized in that a large supercooled water droplet forming method according to any one of claims 1 to 3 is carried out, comprising:
a water droplet forming part for forming large water droplets;
the ultrasonic suspension component is used for controlling the large water drops to be in a suspension state;
a cryogenic cooling chamber for reducing the temperature of the large water droplets;
a first temperature measurement means for acquiring a first temperature of the large water droplet;
the second temperature measuring component is used for acquiring a second temperature of the environment where the large water drop is located, wherein: the environment where the large water drops are located is the low-temperature cold chamber.
5. The large supercooling water drop impact experiment method is characterized by comprising the following steps of:
a method according to any one of claims 1-3 to form supercooled large water droplets;
controlling the supercooled large water drops to freely fall and collide with the substrate;
acquiring an image of a dynamic phenomenon when the supercooled large water drops strike the substrate;
and obtaining a mathematical model required by the experiment according to the image.
6. The method according to claim 5, wherein the dynamic phenomena include splashing, rebound, re-injection of secondary droplets and phase change nucleation.
7. The method of claim 6, wherein the location of nucleation and the nucleation rate are recorded by an infrared camera.
8. A large supercooled large water drop impingement experiment system, characterized in that a large supercooled large water drop impingement experiment method according to any one of claims 5 to 7 is performed, comprising:
the large supercooled water drop forming apparatus of claim 4, wherein: controlling the supercooled large water drops to be cooled in a suspension state by adopting an ultrasonic suspension component, and enabling the supercooled large water drops to freely fall and collide with a substrate when the ultrasonic suspension component is closed;
a base plate for striking with supercooled large water droplets;
and the observation device is used for acquiring an image of the dynamic phenomenon when the supercooled large water drops strike the substrate.
9. The large supercooled large water droplet impact experiment system of claim 8, wherein the observation means includes a high-speed camera for acquiring images of a splash phenomenon, a rebound phenomenon, and a re-injection phenomenon of secondary water droplets when the supercooled large water droplets impact the substrate, and an infrared camera for acquiring images of a phase change nucleation phenomenon.
10. The large supercooled large water drop impact experiment system of claim 9, further comprising a third temperature measuring means and a temperature inspection apparatus connected to the substrate, the third temperature measuring means being adapted to measure the temperature of a fixed point to be measured when the supercooled large water drop impacts the substrate; the temperature patrol instrument is used for recording the measured value of the third temperature measuring component.
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