A microscopic observation system and method for the freezing process of ice crystal-water mixed-phase particles

Abstract

The present invention discloses a microscopic observation system and method for the freezing process of ice crystal - water mixed - phase particles. The system includes an ice crystal - water mixed - phase particle generation subsystem, a microscopic observation subsystem, a sample chamber environmental gas generation subsystem, and a temperature and humidity monitoring subsystem. Among them: The ice crystal - water mixed - phase particle generation subsystem is used to generate, observe, and collect ice crystal - water mixed - phase particles with different degrees of melting; The microscopic observation subsystem is used to provide cooling conditions for the ice crystal - water mixed - phase particles to freeze, and at the same time is used to observe the freezing process of ice crystal - water mixed - phase particles under different temperature - humidity - pressure conditions; The sample chamber environmental gas generation subsystem is used to provide water vapor and air - water vapor mixed gas in the sample chamber; The temperature and humidity monitoring subsystem is used to monitor the temperature and humidity conditions on the surface of the metal sampling sheet. The present invention can be used to explore the micro - and mesoscopic freezing mechanism of ice crystal - water mixed - phase particles under different temperature, humidity, and pressure conditions.

Description

Technical Field

[0001] The present invention relates to the fields of aircraft engine icing and anti-icing tests, and particularly to a microscopic observation system and method for the freezing process of ice crystal-water mixed-phase particles. Background Art

[0002] Icing incidents caused by ice crystals frequently occur at cruising altitudes, seriously affecting flight safety. Different from the external icing of aircraft engines caused by supercooled water droplets, ice crystal icing caused by tiny ice crystal particles at cruising altitudes can directly occur on the surfaces of the intermediate-pressure compressors or even the high-pressure compressor blades of aircraft engines, and further lead to accidents such as thrust loss, surge, vibration overlimit, in-flight shutdown, and structural damage of the engine, seriously affecting flight safety. After the ice crystal particles are inhaled into the aircraft engine, they will melt to form ice crystal-water mixed-phase particles. The freezing of the ice crystal-water mixed-phase particles on the surface of the compressor blade is the direct cause of ice crystal icing. Exploring the micro-mechanism of the freezing process of ice crystal-water mixed-phase particles is of great significance.

[0003] Since 2009, the National Aeronautics and Space Administration (NASA) of the United States and the National Research Council of Canada have done a great deal of work on ice crystal icing test research. NASA has established a full-scale engine ice crystal icing test facility (Griffin T A, Dicki D J, Lizanich P J. PSL icing facility upgrade overview. 6th AIAA Atmospheric and Space Environments Conference, 2014; Struk P M, Tsao J C, Bartkus T P. Plans and preliminary results of fundamental studies of ice crystal icing physics in the NASA propulsion systems laboratory. 8th AIAA Atmospheric and Space Environments Conference, 2016). The National Research Council of Canada has established an ice crystal icing visualization test bench (Mason J G, Chow P, Dan M F. Understanding ice crystal accretion and shedding phenomenon in jet engines using a rig test. Proceedings of ASME Turbo Expo 2010: Power for Land, Sea and Air, 2010). The macroscopic tests carried out based on the above-mentioned devices play a great role in the research of ice crystal icing. However, the ice crystal-water mixed-phase particles continuously impact the structure surface at high speed. It is difficult to capture the details of the freezing process of ice crystal-water mixed-phase particles based on the above-mentioned devices, and it is difficult to reveal the freezing mechanism of ice crystal-water mixed-phase particles with different melting degrees on the structure surface at the micro-nano scale.

[0004] At present, the experimental research on ice crystal icing in China is still in its infancy. AECC Commercial Aircraft Engine Co., Ltd. has proposed an ice crystal simulation system for icing wind tunnels (CN202120483842.2), which can only generate ice crystals in the wind tunnel and cannot carry out the observation and research on the freezing process of ice crystal-water mixed-phase particles. Beihang University and Beihang University Hangzhou Innovation Institute have proposed an experimental device and method for secondary icing of ice crystals on aeroengine compressor blades (CN202210582748.1, CN202210582752.8). The above methods focus on monitoring the ice crystal icing process of aeroengine compressor blades based on a high-speed camera. Due to the limited magnification of the high-speed camera, the above solutions can only observe the ice layer growth on the surface of the compressor blade at the millimeter and sub-micron scales, and it is difficult to observe the freezing process of ice crystal-water mixed-phase particles at the micro-nano scale, and it is difficult to reveal the freezing mechanism of ice crystal-water mixed-phase particles with different melting degrees on the structure surface.

[0005] In summary, the existing devices are difficult to be used to explore the micro-nano scale freezing mechanism of ice crystal-water mixed-phase particles. It is of great significance to develop a microscopic observation system and method for the freezing process of ice crystal-water mixed-phase particles to reveal the micro-meso scale freezing mechanism of ice crystal-water mixed-phase particles. Summary of the Invention

[0006] The purpose of the present invention is to provide a microscopic observation system and method for the freezing process of ice crystal-water mixed-phase particles to solve the problems existing in the prior art. Based on the present invention, microscopic tests on the freezing process of ice crystal-water mixed-phase particles with different melting degrees can be carried out to explore the micro-meso scale freezing mechanism of ice crystal-water mixed-phase particles under different temperature, humidity and pressure conditions.

[0007] To achieve the above object, the present invention provides the following solutions: The present invention provides a microscopic observation system and method for the freezing process of ice crystal-water mixed-phase particles. The system includes an ice crystal-water mixed-phase particle generation subsystem, a microscopic observation subsystem, a sample chamber environmental gas generation subsystem, and a temperature and humidity monitoring subsystem. The ice crystal-water mixed-phase particle generation subsystem includes an ice crusher, an air compressor, a particle size sieve, a temperature control tube, a long focal length microscope I equipped with a high-speed camera, a nozzle, a metal sampling sheet, a valve, and a long focal length microscope II equipped with a high-speed camera. The ice crusher is used to generate ice crystal particles, the air compressor provides a driving air flow for the ice crystal particles, the particle size sieve is used to screen ice crystal particles with an equivalent diameter less than 200 micrometers, the temperature control tube is used to obtain ice crystal-water mixed-phase particles with different melting degrees, the long focal length microscope I equipped with a high-speed camera is used to observe the ice crystal melting process in real time online, the valve is used to control the flow of ice crystal-water mixed-phase particles, the metal sampling sheet is used to collect ice crystal-water mixed-phase particles with different melting degrees ejected from the nozzle, and the long focal length microscope II equipped with a high-speed camera is used to observe the adhesion of ice crystal-water mixed-phase particles on the metal sampling sheet. The microscopic observation subsystem is an environmental scanning electron microscope equipped with a Peltier cold stage. The Peltier cold stage is installed on the stage in the sample chamber of the environmental scanning electron microscope. The metal sampling sheet attached with ice crystal-water mixed-phase particles is placed on the Peltier cold stage. The Peltier cold stage is used to provide cooling conditions for the ice crystal-water mixed-phase particles to freeze. The environmental scanning electron microscope is used to observe the freezing process of ice crystal-water mixed-phase particles under different temperature-humidity-pressure conditions. The sample chamber environmental gas generation subsystem includes a water storage bottle, a water vapor generator, and an air bottle equipped with a mass flow controller. The water storage bottle is used to store distilled water and provide water vapor for the inside of the sample chamber. If only water vapor needs to be provided in the experiment, the water storage bottle is connected to the water vapor inlet of the environmental scanning electron microscope. The water vapor generator and the air bottle equipped with a mass flow controller are used to provide air-water vapor mixed gas for the inside of the sample chamber. If air-water vapor mixed gas needs to be provided in the experiment, the water vapor generated by the water vapor generator is mixed with the air generated by the air bottle equipped with a mass flow controller and then introduced into the other gas inlet of the environmental scanning electron microscope. Since the vacuum degree of the sample chamber of the environmental scanning electron microscope is relatively high, the distilled water in the water storage bottle can evaporate into the sample chamber of the environmental scanning electron microscope. The pressure condition of the sample chamber is monitored and controlled by the sensor inside the environmental scanning electron microscope. It should be noted that during the experiment, a small part of the water phase of the ice crystal-water mixed-phase particles on the metal sampling sheet will also evaporate and be lost due to the relatively high vacuum degree in the sample chamber.The temperature and humidity monitoring subsystem includes a temperature sensor and a humidity sensor. The two sensors penetrate into the sample chamber of the environmental scanning electron microscope through the side flange of the environmental scanning electron microscope, and are respectively used to monitor the temperature and humidity of the surface of the metal sampling piece; based on the temperature sensor provided by the Peltier cold stage, the surface temperature of the Peltier cold stage can be monitored. The metal sampling piece is placed above the Peltier cold stage, and its temperature is different from the temperature of the Peltier cold stage to a certain extent. Therefore, the temperature sensor is needed to monitor the surface temperature of the metal sampling piece; at the same time, the temperature near the Peltier cold stage is relatively low, and the density of water molecules is relatively large. There is a difference between the humidity near the surface of the metal sampling piece and the average humidity of the entire sample chamber. Therefore, the humidity sensor is needed to monitor the surface humidity of the metal sampling piece.

[0008] The temperature control tube includes a temperature controller, a C-shaped heating tube, and a high-temperature resistant glass tube. The C-shaped heating tube covers the high-temperature resistant glass tube, and the uncovered part can be used as an observation window of the telephoto microscope equipped with a high-speed camera. The temperature controller can control the heating of the C-shaped heating tube, so that different warm environments can be formed inside the high-temperature resistant glass tube, thereby controlling the melting degree of ice crystals in the high-temperature resistant glass tube.

[0009] The metal sampling piece is a thin disc with a groove in the middle, and its diameter is not larger than the size of the refrigeration part of the Peltier cooling platform.

[0010] The test procedure of the present invention is as follows:

[0011] 1) installing a Peltier cold stage in a sample chamber of an environmental scanning electron microscope to form an environmental scanning electron microscope equipped with a Peltier cold stage;

[0012] 2) Provide sample chamber environmental gas according to test requirements: If the test only requires water vapor, connect the water storage bottle to the water vapor inlet of the environmental scanning electron microscope; If the test requires air-water vapor mixed gas, mix the water vapor generated by the water vapor generator with the air of a specific mass flow generated by the air bottle equipped with a mass flow controller and then pass it into other gas inlets of the environmental scanning electron microscope;

[0013] 3) Start the ice crusher, air compressor, and particle size sieving instrument to screen ice crystal particles with an equivalent diameter of less than 200 microns, and allow the ice crystal particles to enter the temperature control tube under the action of compressed air flow;

[0014] 4) Determine the melting degree of ice crystal-water mixed phase particles according to the test requirements, obtain ice crystal-water mixed phase particles with a specific melting degree by adjusting the temperature of the temperature control tube, and start a telephoto microscope equipped with a high-speed camera to observe the ice crystal melting process in real time online;

[0015] 5) Open the valve, collect ice crystal - water mixed - phase particles with a metal sampling sheet, and start the long - focal - length microscope equipped with a high - speed camera to observe in real - time and online the adhesion of ice crystal - water mixed - phase particles to the metal sampling sheet;

[0016] 6) Place the metal sampling sheet with adhered ice crystal - water mixed - phase particles on the Peltier cold stage, and set the Peltier cold stage to 0 °C to maintain the state of ice crystal - water mixed - phase particles;

[0017] 7) Close the valve, ice crusher, particle size sieve, temperature - controlled tube, air compressor, long - focal - length microscope one equipped with a high - speed camera, and long - focal - length microscope two equipped with a high - speed camera in sequence;

[0018] 8) Start the environmental scanning electron microscope, select the environmental scanning mode, and set the sample chamber pressure conditions according to the test requirements;

[0019] 9) Start the temperature sensor and humidity sensor to monitor the temperature and humidity conditions near the ice crystal - water mixed - phase particles on the surface of the metal sampling sheet;

[0020] 10) Change the temperature of the Peltier cold stage according to the test needs to conduct microscopic observation experiments on the freezing process of ice crystal - water mixed - phase particles;

[0021] 11) After the test, turn off the electron gun of the environmental scanning electron microscope, adjust the temperature of the Peltier cold stage to room temperature, restore the air pressure in the sample chamber of the environmental scanning electron microscope to one atmosphere, take out the metal sampling sheet and the Peltier cold stage, and restore the air pressure in the sample chamber of the environmental scanning electron microscope to a high - vacuum state.

[0022] The present invention has achieved the following technical effects compared with the prior art:

[0023] Based on the present invention, microscopic observation experiments on the freezing process of ice crystal - water mixed - phase particles with different melting degrees can be carried out to explore the micro - and nano - scale freezing mechanisms of ice crystal - water mixed - phase particles under different temperature, humidity, and pressure conditions. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 It is a schematic diagram of the microscopic observation system for the freezing process of ice crystal - water mixed - phase particles in the present invention;

[0026] Figure 2 It is a schematic diagram of the temperature - controlled tube;

[0027] Figure 3 Schematic diagram of metal sampling piece

[0028] Among them, 1. Ice crusher; 2. Air compressor; 3. Particle size sieve; 4. Temperature control tube; 4.1. Temperature controller; 4.2. C-shaped heating tube; 4.3. High-temperature resistant glass tube; 5. Long-focus microscope I equipped with a high-speed camera; 6. Nozzle; 7. Metal sampling piece; 8. Valve; 9. Long-focus microscope II equipped with a high-speed camera; 10. Environmental scanning electron microscope equipped with a Peltier cold stage; 11. Water storage bottle; 12. Water vapor generator; 13. Air bottle equipped with a mass flow controller; 14. Temperature sensor; 15. Humidity sensor Specific implementation mode

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention

[0030] The purpose of the present invention is to provide a microscopic observation system and method for the freezing process of ice crystal-water mixed-phase particles, so as to solve the problems existing in the prior art, realize the microscopic observation of the freezing process of ice crystal-water mixed-phase particles with different melting degrees, and reveal the micro and mesoscopic freezing mechanism of ice crystal-water mixed-phase particles

[0031] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation modes

[0032] Embodiment 1

[0033] This embodiment provides a microscopic observation system for the freezing process of ice crystal-water mixed-phase particles. As Figure 1 shown, the system includes an ice crystal-water mixed-phase particle generation subsystem, a microscopic observation subsystem, a sample chamber environmental gas generation subsystem, and a temperature and humidity monitoring subsystem. The ice crystal-water mixed-phase particle generation subsystem is used to generate, observe and collect ice crystal-water mixed-phase particles with different melting degrees; the microscopic observation subsystem is used to provide cooling conditions for the ice crystal-water mixed-phase particles to freeze, and at the same time to observe the freezing process of the ice crystal-water mixed-phase particles under different temperature-humidity-pressure conditions; the sample chamber environmental gas generation subsystem is used to provide water vapor and air-water vapor mixed gas in the sample chamber; the temperature and humidity monitoring subsystem is used to monitor the surface temperature and humidity of the metal sampling piece

[0034] The ice crystal - water mixed - phase particle generation subsystem includes an ice crusher 1, an air compressor 2, a particle size sieve 3, a temperature - control tube 4, a long - focal - length microscope I 5 equipped with a high - speed camera, a nozzle 6, a metal sampling sheet 7, a valve 8, and a long - focal - length microscope II 9 equipped with a high - speed camera. The ice crusher 1 is used to generate ice crystal particles. The ice crystal particles enter the particle size sieve 3 under the action of the driving air flow provided by the air compressor 2. The particle size sieve 3 screens out ice crystal particles with an equivalent diameter less than 200 microns. The above - mentioned particles further enter the temperature - control tube 4 to form ice crystal - water mixed - phase particles with different melting degrees. The long - focal - length microscope I 5 equipped with a high - speed camera is used to observe the ice crystal melting process in real - time online. The nozzle 6 sprays the ice crystal - water mixed - phase particles onto the metal sampling sheet 7. The valve 8 is used to control the flow of the ice crystal - water mixed - phase particles. The long - focal - length microscope II 9 equipped with a high - speed camera is used to observe the adhesion of the ice crystal - water mixed - phase particles on the metal sampling sheet 7.

[0035] The microscopic observation subsystem is an environmental scanning electron microscope 10 equipped with a Peltier cold stage. The Peltier cold stage is installed on the stage in the sample chamber of the environmental scanning electron microscope. The Peltier cold stage is used to provide cooling conditions for freezing the ice crystal - water mixed - phase particles. The environmental scanning electron microscope is used to observe the freezing process of the ice crystal - water mixed - phase particles under different temperature - humidity - pressure conditions. The metal sampling sheet 7 with attached ice crystal - water mixed - phase particles is placed on the Peltier cold stage. The water storage bottle 11 is connected to the water vapor inlet of the environmental scanning electron microscope 10 equipped with a Peltier cold stage. The water vapor generator 12, the air bottle 13 equipped with a mass flow controller are connected to the other gas inlets of the environmental scanning electron microscope 10 equipped with a Peltier cold stage. The temperature sensor 14 and the humidity sensor 15 penetrate into the sample chamber of the environmental scanning electron microscope 10 equipped with a Peltier cold stage through the flange on the side, and are used to monitor the surface temperature and humidity of the metal sampling sheet 7 respectively.

[0036] As Figure 2 shown, the temperature - control tube 4 includes a temperature controller 4.1, a C - shaped heating tube 4.2, and a high - temperature - resistant glass tube 4.3. The C - shaped heating tube 4.2 covers the high - temperature - resistant glass tube 4.1. The uncovered part can be used as the observation window of the long - focal - length microscope I 5 equipped with a high - speed camera. By controlling the heating of the C - shaped heating tube 4.2 through the temperature controller 4.1, different warm environments can be formed inside the high - temperature - resistant glass tube 4.3, so as to control the melting degree of the ice crystal particles in the high - temperature - resistant glass tube 4.3.

[0037] As Figure 3 shown, the metal sampling sheet 7 is a thin circular sheet with a groove in the middle, and its diameter is not larger than the size of the refrigerating part of the Peltier cold stage.

[0038] Based on this embodiment, microscopic tests on the freezing process of ice crystal - water mixed - phase particles with different melting degrees can be carried out to explore the microscopic freezing mechanism of ice crystal - water mixed - phase particles under different temperature, humidity, and pressure conditions.

[0039] Embodiment 2:

[0040] This embodiment provides a method for observing the adhesion - freezing process of ice crystal - water mixed - phase particles, including the following steps:

[0041] 1) Install the Peltier cold stage in the sample chamber of the environmental scanning electron microscope to form an environmental scanning electron microscope 10 equipped with a Peltier cold stage;

[0042] 2) Provide the environmental gas in the sample chamber according to the test requirements: If only water vapor needs to be provided for the test, connect the water storage bottle 11 to the water vapor inlet of the environmental scanning electron microscope 10 equipped with a Peltier cold stage; If an air - water vapor mixed gas needs to be provided for the test, mix the water vapor generated by the water vapor generator 12 with the air at a specific mass flow rate generated by the air bottle 13 equipped with a mass flow controller and then introduce it into the other gas inlet of the environmental scanning electron microscope 10 equipped with a Peltier cold stage;

[0043] 3) Start the ice crusher 1, air compressor 2, and particle size sieve 3. The ice crusher 1 generates ice crystal particles, the air compressor 2 generates a compressed air flow, and the particle size sieve 3 screens ice crystal particles with an equivalent diameter less than 200 microns and makes the ice crystal particles enter the temperature - controlled tube 4 under the action of the compressed air flow;

[0044] 4) Determine the melting degree of the ice crystal - water mixed - phase particles according to the test requirements, obtain the ice crystal - water mixed - phase particles with the required melting degree by adjusting the temperature of the temperature - controlled tube 4, and start the long - focal - length microscope 5 equipped with a high - speed camera to observe the ice crystal melting process in real - time;

[0045] 5) Open the valve 8, collect the ice crystal - water mixed - phase particles with the metal sampling sheet 7, and start the long - focal - length microscope 9 equipped with a high - speed camera to observe the adhesion of the ice crystal - water mixed - phase particles on the metal sampling sheet 7 in real - time;

[0046] 6) Place the metal sampling sheet 7 with the adhered ice crystal - water mixed - phase particles on the Peltier cold stage, and set the Peltier cold stage to 0 °C to maintain the state of the ice crystal - water mixed - phase particles;

[0047] 7) Close the valve 8, ice crusher 1, particle size sieve 3, temperature - controlled tube 4, air compressor 2, long - focal - length microscope 5 equipped with a high - speed camera, and long - focal - length microscope 9 equipped with a high - speed camera in sequence;

[0048] 8) Start the environmental scanning electron microscope 10 equipped with a Peltier cold stage, select the environmental scanning mode, and set the pressure condition of the sample chamber according to the test requirements;

[0049] 9) Activate the temperature sensor 14 and the humidity sensor 15 to monitor the temperature and humidity conditions near the ice crystal-water mixed-phase particles on the surface of the metal sampling sheet 7;

[0050] 10) Change the temperature of the Peltier cold stage according to the test requirements to conduct microscopic observation tests on the freezing process of ice crystal-water mixed-phase particles;

[0051] 11) After the test, turn off the electron gun of the environmental scanning electron microscope 10 equipped with the Peltier cold stage, adjust the temperature of the Peltier cold stage to room temperature, restore the air pressure in the sample chamber to one atmosphere, take out the metal sampling sheet 7 and the Peltier cold stage, and restore the air pressure in the environmental scanning electron microscope sample chamber to the high vacuum state.

[0052] Adaptations made according to actual requirements are within the scope of protection of the present invention.

[0053] It should be noted that for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A microscopic observation system for the freezing process of ice crystal - water mixed - phase particles, characterized in that, It includes an ice crystal - water mixed - phase particle generation subsystem, a microscopic observation subsystem, a sample chamber environmental gas generation subsystem, and a temperature - humidity monitoring subsystem. The ice crystal - water mixed - phase particle generation subsystem is used to generate, observe, and collect ice crystal - water mixed - phase particles with different degrees of melting; the microscopic observation subsystem is used to provide cooling conditions for the freezing of ice crystal - water mixed - phase particles and simultaneously observe the freezing process of ice crystal - water mixed - phase particles under different temperature - humidity - pressure conditions; the sample chamber environmental gas generation subsystem is used to provide water vapor and air - water vapor mixed gas in the sample chamber; the temperature - humidity monitoring subsystem is used to monitor the surface temperature and humidity of the metal sampling sheet; the microscopic observation system for the freezing process of ice crystal - water mixed - phase particles can be used for the microscopic observation of the freezing process of ice crystal - water mixed - phase particles with different degrees of melting to explore the micro - and mesoscopic freezing mechanism of ice crystal - water mixed - phase particles; The ice crystal - water mixed - phase particle generation subsystem includes an ice crusher, an air compressor, a particle size sieve, a temperature - controlled tube, a long - focal - length microscope one equipped with a high - speed camera, a nozzle, a metal sampling sheet, a valve, and a long - focal - length microscope two equipped with a high - speed camera. The ice crusher is used to generate ice crystal particles, the air compressor provides driving air flow for the ice crystal particles, the particle size sieve is used to screen ice crystal particles with an equivalent diameter less than 200 microns, the temperature - controlled tube is used to obtain ice crystal - water mixed - phase particles with different degrees of melting, the long - focal - length microscope one equipped with a high - speed camera is used to observe the ice crystal melting process in real - time online, the valve is used to control the flow of ice crystal - water mixed - phase particles, the metal sampling sheet is used to collect ice crystal - water mixed - phase particles with different degrees of melting ejected from the nozzle, and the long - focal - length microscope two equipped with a high - speed camera is used to observe the adhesion of ice crystal - water mixed - phase particles on the metal sampling sheet.

2. The microscopic observation system for the freezing process of ice crystal-water mixed-phase particles according to claim 1, characterized in that, The microscopic observation subsystem is an environmental scanning electron microscope equipped with a Peltier cold stage. The Peltier cold stage is installed on the stage in the sample chamber of the environmental scanning electron microscope. The metal sampling sheet with attached ice crystal - water mixed - phase particles is placed on the Peltier cold stage. The Peltier cold stage is used to provide cooling conditions for the freezing of ice crystal - water mixed - phase particles, and the environmental scanning electron microscope is used to observe the freezing process of ice crystal - water mixed - phase particles under different temperature - humidity - pressure conditions.

3. The microscopic observation system for the freezing process of ice crystal-water mixed-phase particles according to claim 2, characterized in that, The sample chamber environmental gas generation subsystem includes a water storage bottle, a water vapor generator, and an air bottle equipped with a mass flow controller; the water storage bottle is used to store distilled water and provide water vapor to the sample chamber. If only water vapor needs to be provided for the test, the water storage bottle is connected to the water vapor inlet of the environmental scanning electron microscope; the water vapor generator and the air bottle equipped with a mass flow controller are used to provide air-water vapor mixed gas to the sample chamber. If air-water vapor mixed gas needs to be provided for the test, the water vapor generated by the water vapor generator is mixed with the air with a specific mass flow generated by the air bottle equipped with a mass flow controller and then introduced into the other gas inlet of the environmental scanning electron microscope; due to the relatively high vacuum degree of the sample chamber of the environmental scanning electron microscope, the distilled water in the water storage bottle can evaporate into the sample chamber of the environmental scanning electron microscope, and the pressure condition of the sample chamber is monitored and controlled by the internal sensor of the environmental scanning electron microscope.

4. The microscopic observation system for the freezing process of ice crystal-water mixed-phase particles according to claim 1, characterized in that, The temperature and humidity monitoring subsystem includes a temperature sensor and a humidity sensor. The two sensors penetrate into the sample chamber of the environmental scanning electron microscope through the side flange of the environmental scanning electron microscope, and are respectively used to monitor the surface temperature and humidity of the metal sampling sheet.

5. The microscopic observation system for the freezing process of ice crystal-water mixed-phase particles according to claim 1, wherein The temperature control tube includes a temperature controller, a C-shaped heating tube, and a high-temperature resistant glass tube. The C-shaped heating tube covers the high-temperature resistant glass tube, and the uncovered part can be used as the observation window of the long-focus microscope I equipped with a high-speed camera. The heating of the C-shaped heating tube can be controlled through the temperature controller, so that different warm environments can be formed inside the high-temperature resistant glass tube, thereby controlling the melting degree of ice crystal particles in the high-temperature resistant glass tube.

6. The microscopic observation system for the freezing process of ice crystal-water mixed-phase particles according to claim 2, wherein The metal sampling sheet is a thin round sheet with a groove in the middle, and its diameter is not larger than the size of the refrigeration part of the Peltier cold stage.

7. A microscopic observation method for the freezing process of ice crystal - water mixed - phase particles, based on the microscopic observation system for the freezing process of ice crystal - water mixed - phase particles described in claim 3, characterized in that, It includes the following steps: 1) Install the Peltier cold stage in the sample chamber of the environmental scanning electron microscope to form an environmental scanning electron microscope equipped with a Peltier cold stage; 2) According to the test requirements, provide the environmental gas in the sample chamber: if only water vapor needs to be provided for the test, connect the water storage bottle to the water vapor inlet of the environmental scanning electron microscope; if air-water vapor mixed gas needs to be provided for the test, mix the water vapor generated by the water vapor generator with the air with a specific mass flow generated by the air bottle equipped with a mass flow controller and then introduce it into the other gas inlet of the environmental scanning electron microscope; 3) Start the ice crusher, air compressor, and particle size sieve, screen ice crystal particles with an equivalent diameter less than 200 microns, and make the ice crystal particles enter the temperature control tube under the action of the compressed air flow; 4) Determine the melting degree of the ice crystal-water mixed phase particles according to the test requirements, obtain ice crystal-water mixed phase particles with a specific melting degree by adjusting the temperature of the temperature control tube, and start the long-focus microscope I equipped with a high-speed camera to observe the ice crystal melting process in real time online; 5) Open the valve, collect the ice crystal-water mixed phase particles with the metal sampling sheet, and start the long-focus microscope II equipped with a high-speed camera to observe the adhesion of the ice crystal-water mixed phase particles on the metal sampling sheet in real time online; 6) Place the metal sampling sheet with attached ice crystal - water mixed - phase particles on the Peltier cold stage, and set the Peltier cold stage to 0 °C to maintain the ice crystal - water mixed - phase particle state; 7) Close the valve, ice crusher, particle size sieve analyzer, temperature - controlled tube, air compressor, long - focal - length microscope I equipped with a high - speed camera, and long - focal - length microscope II equipped with a high - speed camera in sequence; 8) Start the environmental scanning electron microscope, select the environmental scanning mode, and set the sample chamber pressure conditions according to the test requirements; 9) Start the temperature sensor and humidity sensor to monitor the temperature and humidity conditions near the ice crystal - water mixed - phase particles on the surface of the metal sampling sheet; 10) Change the temperature of the Peltier cold stage according to the test needs to conduct a microscopic test on the freezing process of ice crystal - water mixed - phase particles; 11) After the test, turn off the electron gun of the environmental scanning electron microscope, adjust the temperature of the Peltier cold stage to room temperature, restore the air pressure in the sample chamber of the environmental scanning electron microscope to one atmosphere, take out the metal sampling sheet and the Peltier cold stage, and restore the air pressure in the sample chamber of the environmental scanning electron microscope to a high - vacuum state.

Images