In-situ observation device for cryogenic fluid

Abstract

The invention relates to the technical field of observation devices, and provides an in-situ observation device for cryogenic fluid, the in-situ observation device comprises a two-phase flow generation mechanism, an observation mechanism and a vacuum cover, the two-phase flow generation mechanism comprises a cryostat, a first cooling table and a runner pipe, and the runner pipe is arranged on the first cooling table; the observation mechanism comprises a mounting base, an objective lens, a light-transmitting plate and a camera shooting assembly, the light-transmitting plate is arranged on the mounting base and is in sealed connection with the mounting base, and the objective lens and the camera shooting assembly are arranged on the mounting base and located on the two opposite sides of the light-transmitting plate respectively; the vacuum cover covers the two-phase flow generation mechanism and the objective lens and is in sealed connection with the mounting seat, and the two ends of the runner pipe extend out of the vacuum cover and are in sealed connection with the vacuum cover. Therefore, the objective lens and the runner pipe are both located in a low-temperature environment, there is no separator such as a glass plate between the objective lens and the runner pipe, and definition and accuracy of visual research can be ensured. Moreover, the vacuum cover and the mounting seat are matched to form the vacuum cavity, and the objective lens is positioned in the vacuum cavity, so that the problem of heat leakage can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of observation devices, and in particular to an in-situ observation device for cryogenic fluids. Background Art

[0002] Cryogenic fluids are widely used in aerospace, energy, chemical industry, and medical fields. Take liquid nitrogen as an example. Liquid nitrogen is a low-cost, safe, and fast-cooling cryogenic fluid. It is mainly used in high-temperature superconducting magnet cooling, ultra-low temperature processing cooling of high-temperature alloys and fiber-reinforced composite materials, liquid cooling and heat exchange of high-power devices for low-temperature applications, fire protection and extinguishing projects of energy storage power stations, and superconducting composite energy pipelines. As a refrigerant with a small latent heat of vaporization, liquid nitrogen is very easy to absorb heat, boil, and vaporize to form a liquid nitrogen-nitrogen vapor two-phase flow, which causes the flow parameters to fluctuate and the cooling effect to deteriorate. Therefore, the study of the flow and heat transfer characteristics of liquid nitrogen-nitrogen vapor two-phase flow is particularly important.

[0003] At present, the technical means for studying liquid nitrogen-nitrogen vapor two-phase flow are mainly divided into model prediction, numerical simulation and experimental analysis, which cannot analyze the physical phenomena during operation. Some related technologies propose visualization research technical means, specifically generating low temperature in the sample chamber, passing the fluid to be studied into the sample chamber, and opening a window on the side wall of the sample chamber. An observation component facing the window is set outside the sample chamber, and the low-temperature fluid in the sample chamber is observed through the observation component. The setting of the window will cause heat leakage, affecting the accuracy of the observation results. If the thickness of the window glass is increased, the clarity and accuracy of the observation will be affected.

[0004] Therefore, how to solve the problem of heat leakage or poor observation clarity when conducting visualization research on cryogenic fluids has become an important technical problem that technicians in this field need to solve. Summary of the invention

[0005] The present invention provides an in-situ observation device for cryogenic fluid, which is used to solve the defects of heat leakage or poor observation clarity when visualizing the cryogenic fluid.

[0006] The present invention provides an in-situ observation device for cryogenic fluid, comprising: A two-phase flow generating mechanism, comprising a low temperature thermostat, a first cold stage and a flow pipe, wherein the flow pipe is suitable for allowing fluid to pass through, the flow pipe is arranged at the first cold stage, the low temperature thermostat is suitable for providing cold energy to the first cold stage, and the first cold stage is suitable for transferring cold energy to the flow pipe; The observation mechanism comprises a mounting seat, an objective lens, a light-transmitting plate and a camera assembly, wherein the light-transmitting plate is arranged on the mounting seat, the light-transmitting plate is sealed and connected to the mounting seat, the objective lens and the camera assembly are both arranged on the mounting seat, and the objective lens and the camera assembly are respectively located on two opposite sides of the light-transmitting plate, and the objective lens faces the flow tube on the first cold stage; A vacuum cover is arranged outside the two-phase flow generating mechanism and the objective lens, the vacuum cover is sealed and connected to the mounting seat, both ends of the flow tube extend to the outside of the vacuum cover, and the flow tube is sealed and connected to the vacuum cover.

[0007] An in-situ observation device for cryogenic fluid provided by the present invention further comprises: The first cooling conductor is disposed between the cold end of the cryostat and the objective lens, and is suitable for transferring the cold energy of the cold end of the cryostat to the objective lens.

[0008] According to an in-situ observation device for cryogenic fluid provided by the present invention, a containing tank is provided on the first cold stage, and the flow pipe is passed through the containing tank.

[0009] An in-situ observation device for cryogenic fluid provided by the present invention further comprises: The second cooling member is disposed between the cold end of the cryostat and the first cold stage, and the second cooling member is suitable for transferring the cold energy of the cold end of the cryostat to the first cold stage.

[0010] According to an in-situ observation device for cryogenic fluid provided by the present invention, the second cooling member comprises: A cooling rod, wherein at least two first connecting holes are arranged at one end of the cooling rod close to the objective lens, and the first connecting holes are spaced apart along the axial direction of the cooling rod; the first cold stage has a connecting portion, and the connecting portion is provided with a second connecting hole, and the second connecting hole is suitable for being connected to any one of the first connecting holes by a connecting bolt.

[0011] According to an in-situ observation device for cryogenic fluid provided by the present invention, the vacuum cover comprises: a first vacuum cover, disposed outside the cryostat; a second vacuum cover, which is arranged outside the first cold stage and the circulation tube, a vacuum passage for the second cooling member to pass through is formed between the second vacuum cover and the first vacuum cover, an opening is arranged on the second vacuum cover at a position facing the first cold stage, and the opening allows the objective lens to approach or move away from the circulation tube; The vacuum cylinder is arranged between the second vacuum cover and the mounting seat, one end of the vacuum cylinder is sealed and connected to the opening of the second vacuum cover, and the other end of the vacuum cylinder is sealed and connected to the mounting seat.

[0012] According to an in-situ observation device for cryogenic fluid provided by the present invention, a sealing structure is provided between the second vacuum cover and the flow pipe, and the sealing structure comprises: A connecting pipe, disposed on the second vacuum cover, the connecting pipe being suitable for allowing the flow pipe to enter and exit the second vacuum cover; an end cap, arranged at one end of the connecting pipe away from the second vacuum cover, the end cap being sealedly connected to the connecting pipe, and the end cap being provided with a through hole for the circulation pipe to pass through; A sealing ring is sleeved on the outside of the circulation tube, and the sealing ring is tightly fitted to the circulation tube; A pressing piece is arranged on a side of the end cover away from the connecting pipe, the pressing piece is threadedly connected to the end cover, and the pressing piece is suitable for pressing the sealing ring onto the end cover.

[0013] According to an in-situ observation device for cryogenic fluid provided by the present invention, the vacuum cylinder includes a first flexible bellows.

[0014] According to an in-situ observation device for cryogenic fluid provided by the present invention, the cryostat comprises: A refrigerator, comprising a primary cold head and a secondary cold head, at least the primary cold head and the secondary cold head extend into the first vacuum cover, and the secondary cold head is provided with a cold head heat exchanger; A first cold shield is disposed in the first vacuum cover, the first cold shield cover is disposed outside the first-stage cold head, and the first cold shield is sealed and connected to the first vacuum cover through an insulating tube; A second cold screen is arranged in the first vacuum cover, the second cold screen cover is arranged outside the secondary cold head, the second cold screen is connected to the first cold screen through a cooling ring, a second cold stage is arranged at one end of the second cold screen away from the first cold screen, the second cold stage is suitable for connecting with the second cooling member, and the cooling capacity of the second cold screen is lower than that of the second cooling member; a helium source, adapted to fill the space between the first cold shield and the first-stage cold head with helium; A third cold shield is arranged in the first vacuum cover, the third cold shield cover is arranged outside the second cold shield, one end of the third cold shield is closed, and the other end is connected to the cooling ring; A fourth cold screen is arranged in the vacuum channel, the fourth cold screen cover is arranged outside the second cooling member, one end of the fourth cold screen extends to the first vacuum cover and is connected to the third cold screen, and the other end of the fourth cold screen extends into the second vacuum cover.

[0015] An in-situ observation device for cryogenic fluid provided by the present invention further comprises: An optical vibration reduction platform, wherein the first vacuum cover and the second vacuum cover are both arranged on the optical vibration reduction platform; An air-floating vibration-damping bracket, comprising a support platform and a support frame for supporting the support platform, the body of the refrigerator is arranged above the support platform, the primary cold head and the secondary cold head extend to the bottom of the support platform, and an air-floating vibration damper is arranged at the lower end of the support frame; The second flexible bellows is arranged between the supporting platform and the first vacuum cover.

[0016] The in-situ observation device of low-temperature fluid provided by the present invention comprises a two-phase flow generating mechanism, an observation mechanism and a vacuum cover. The two-phase flow generating mechanism comprises a low-temperature thermostat, a first cold stage and a circulation tube, and the circulation tube is used for passing fluid. The circulation tube is arranged on the first cold stage, and the low-temperature thermostat is used to provide cold energy to the first cold stage, and the first cold stage is used to transfer cold energy to the circulation tube, and then transfer the cold energy to the fluid in the circulation tube, reduce the temperature of the fluid, and form a low-temperature fluid. The observation mechanism comprises a mounting seat, an objective lens, a light-transmitting plate and a camera assembly, and the light-transmitting plate is arranged on the mounting seat, and the light-transmitting plate is sealed and connected to the mounting seat. The objective lens and the camera assembly are both arranged on the mounting seat, and the objective lens and the camera assembly are respectively located on two opposite sides of the light-transmitting plate, and the objective lens is directly opposite to the circulation tube on the first cold stage. The camera assembly can obtain the image of the low-temperature fluid at the position opposite to the objective lens through the light-transmitting plate, thereby realizing the visualization research of the low-temperature fluid in the circulation tube. The vacuum cover is arranged outside the two-phase flow generating mechanism and the objective lens, the vacuum cover is sealed and connected with the mounting seat, the two ends of the circulation tube extend to the outside of the vacuum cover, and the circulation tube is sealed and connected with the vacuum cover. The vacuum cover cooperates with the mounting seat to form a vacuum chamber, the vacuum chamber is evacuated, and then the temperature of the vacuum chamber and the first cold stage is reduced to the target temperature by a low temperature thermostat, and a medium is introduced into the circulation tube outside the vacuum cover, and the medium circulates in the circulation tube to the position of the first cold stage to form a low temperature fluid. Starting the camera assembly can obtain the image of the low temperature fluid at the position of the objective lens, and realize the visualization study of the low temperature fluid in the circulation tube. In this way, the objective lens and the circulation tube are both arranged in a low temperature environment, and there is no partition such as a glass plate between the two, which can ensure the clarity and accuracy of the visualization study. Moreover, the vacuum cover cooperates with the mounting seat to form a vacuum chamber, and the objective lens is located in the vacuum chamber, which can effectively avoid the problem of heat leakage, and solves the problem of heat leakage or poor observation clarity when visualizing the low temperature fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic structural diagram of the in-situ observation device for cryogenic fluid provided by the present invention.

[0019] Figure 2 It is a cross-sectional view of the in-situ observation device for cryogenic fluid provided by the present invention at a cutting plane position (the optical vibration reduction platform and the air-floating vibration reduction bracket are not shown).

[0020] Figure 3 yes Figure 1 Enlarged view at the center X position.

[0021] Figure 4 It is a cross-sectional view of the in-situ observation device for cryogenic fluid provided by the present invention at another cutting plane position.

[0022] Figure 5 It is a schematic diagram of the relative positions of the flow tube, the first cold stage and the objective lens provided by the present invention.

[0023] Figure 6 It is a structural schematic diagram of the first cooling stage provided by the present invention.

[0024] Figure 7 It is a schematic diagram of the sealing structure between the circulation tube and the second vacuum cover provided by the present invention.

[0025] Reference numerals: 1. First cold stage; 2. Circulation tube; 3. Mounting seat; 4. Objective lens; 5. Translucent plate; 6. Accommodating groove; 7. Cooling rod; 8. First connecting hole; 9. Connecting part; 10. Second connecting hole; 11. First vacuum cover; 12. Second vacuum cover; 13. Vacuum channel; 14. Opening; 15. Vacuum cylinder; 16. Connecting tube; 17. End cover; 18. Sealing ring; 19. Pressing member; 20. Refrigerator; 21. First-stage cold head; 22. Secondary cold head; 23. Cold head heat exchanger; 24. First cold screen; 25. Insulation tube; 26. Second cold screen; 27. Second cold stage; 28. Helium source; 29. ​​Third cold screen; 30. Fourth cold screen; 31. Optical vibration reduction platform; 32. Support platform; 33. Support frame; 34. Air-floating vibration reducer; 35. Second flexible bellows; 36. Objective lens moving mechanism; 37. Spectroscope and light source; 38. CCD camera; 39. Inflatable seat. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Combine the following Figures 1 to 7 The in-situ observation device for cryogenic fluid of the present invention is described.

[0028] like Figures 1 to 7 As shown, the in-situ observation device for cryogenic fluid provided by an embodiment of the present invention includes a two-phase flow generating mechanism, an observation mechanism and a vacuum cover.

[0029] Specifically, the two-phase flow generating mechanism includes a cryostat, a first cold stage 1 and a flow pipe 2 .

[0030] The flow pipe 2 is used for passing the fluid, and the flow pipe 2 is arranged on the first cold stage 1. The low temperature thermostat is used to provide cold energy to the first cold stage 1, and the first cold stage 1 is used to transfer cold energy to the flow pipe 2, and then transfer the cold energy to the fluid in the flow pipe 2, reduce the temperature of the fluid, and form a low temperature fluid.

[0031] The observation mechanism includes a mounting seat 3, an objective lens 4, a light-transmitting plate 5 and a camera assembly.

[0032] The light-transmitting plate 5 is disposed on the mounting seat 3, and the light-transmitting plate 5 is sealed and connected to the mounting seat 3. The objective lens 4 and the camera assembly are both disposed on the mounting seat 3, and the objective lens 4 and the camera assembly are respectively located on opposite sides of the light-transmitting plate 5, and the objective lens 4 faces the flow tube 2 on the first cold stage 1.

[0033] In order to observe the fluid in the flow tube 2 , the portion of the flow tube 2 located at the first cold stage 1 is set to be transparent, and the specific material may be transparent glass.

[0034] The camera assembly can obtain the image of the cryogenic fluid at the position pointed by the objective lens 4 through the light-transmitting plate 5 , thereby realizing a visualized study of the cryogenic fluid in the flow tube 2 .

[0035] The vacuum cover is arranged outside the two-phase flow generating mechanism and the objective lens 4, the vacuum cover is sealedly connected to the mounting seat 3, both ends of the flow tube 2 extend to the outside of the vacuum cover, and the flow tube 2 is sealedly connected to the vacuum cover.

[0036] The vacuum cover cooperates with the mounting seat 3 to form a vacuum chamber, and the vacuum chamber is evacuated. Then, the temperature of the vacuum chamber and the first cold stage 1 is lowered to the target temperature by a low-temperature thermostat, and a medium is introduced into the circulation tube 2 from the outside of the vacuum cover. The medium flows in the circulation tube 2 to the position of the first cold stage 1 to form a low-temperature fluid. Starting the camera assembly can obtain an image of the low-temperature fluid at the position where the objective lens 4 is facing, so as to realize a visual study of the low-temperature fluid in the circulation tube 2.

[0037] In this way, the objective lens 4 and the flow tube 2 are both placed in a low-temperature environment, and there is no partition such as a glass plate between the two, which can ensure the clarity and accuracy of the visualization research. In addition, the vacuum cover and the mounting seat 3 cooperate to form a vacuum chamber, and the objective lens 4 is located in the vacuum chamber, which can effectively avoid the problem of heat leakage, and solve the problem of heat leakage or poor observation clarity when visualizing the low-temperature fluid.

[0038] It should be noted that the above fluid can be, but is not limited to, hydrogen, liquefied natural gas, nitrogen, oxygen, neon, etc. When the vacuum chamber and the first cold stage 1 are cooled by a low temperature thermostat, the target temperature can be determined according to the composition of the fluid and the state to be observed. For example, when the flow and heat transfer characteristics of the liquid nitrogen-nitrogen vapor two-phase flow need to be observed, the temperature of the vacuum chamber and the first cold stage 1 needs to be controlled at about 77 Kelvin (symbol K).

[0039] In an embodiment of the present invention, the in-situ observation device of the low-temperature fluid also includes a first cooling member, which is arranged between the cold end of the low-temperature thermostat and the objective lens 4. The first cooling member is used to transfer the cold energy of the cold end of the low-temperature thermostat to the objective lens 4 to reduce the temperature of the objective lens 4, which can further reduce the heat leakage problem of the objective lens 4.

[0040] In the embodiment of the present invention, a receiving tank 6 is provided on the first cooling stage 1, and the flow pipe 2 is provided in the receiving tank 6. Figure 5 and Figure 6 The receiving groove 6 is a through groove provided on the first cold stage 1 , and the cross-sectional shape of the receiving groove 6 is close to the cross-sectional shape of the flow pipe 2 .

[0041] With such arrangement, after the flow tube 2 is inserted into the receiving groove 6 , the outer wall of the flow tube 2 contacts the side wall of the receiving groove 6 , thereby increasing the contact area between the flow tube 2 and the first cooling stage 1 , and improving the cooling efficiency of the first cooling stage 1 to the flow tube 2 .

[0042] In an embodiment of the present invention, the in-situ observation device for cryogenic fluid further comprises a second cooling member, which is arranged between the cold end of the cryostat and the first cold stage 1 , and is used to transfer the cold energy of the cold end of the cryostat to the first cold stage 1 .

[0043] In this way, the cryostat is separated from the first cold stage 1, which can reduce the influence of the vibration of the cryostat on the first cold stage 1 and the flow tube 2, ensuring the clarity and accuracy of observation. Moreover, it is conducive to the modular design of the in-situ observation device of the cryogenic fluid, which is more flexible and convenient for layout.

[0044] In this embodiment, the second cooling member includes a cooling rod 7, and a first connecting hole 8 is provided at one end of the cooling rod 7 close to the objective lens 4. At least two first connecting holes 8 are provided, and each first connecting hole 8 is spaced apart along the axial direction of the cooling rod 7. The first cold stage 1 has a connecting portion 9, and a second connecting hole 10 is provided on the connecting portion 9, and the second connecting hole 10 can be connected to any one of the first connecting holes 8 by a connecting bolt.

[0045] When the second connecting hole 10 is connected to different first connecting holes 8, the first cold stage 1 and the cooling rod 7 can have different relative positions, which can adapt to different distances between the first cold stage 1 and the cold end of the low-temperature thermostat, which is beneficial to reducing the requirements for the accuracy of the relative position of the first cold stage 1 and the low-temperature thermostat, and is beneficial to reducing the requirements for processing accuracy.

[0046] In this embodiment, the vacuum cover includes a first vacuum cover 11 , a second vacuum cover 12 and a vacuum cylinder 15 .

[0047] The first vacuum cover 11 is disposed outside the cryostat to reduce the loss of cold at the cold end of the cryostat and reduce heat leakage.

[0048] The second vacuum cover 12 is disposed outside the first cooling stage 1 and the circulation pipe 2 to reduce the cold loss of the first cooling stage 1 and the circulation pipe 2 and reduce heat leakage.

[0049] A vacuum channel 13 is formed between the second vacuum cover 12 and the first vacuum cover 11, and the second vacuum cover 12 and the first vacuum cover 11 are both connected to the vacuum channel 13. Figure 3 , an extension tube with a flange at the end can be respectively provided on the first vacuum cover 11 and the second vacuum cover 12, and the two extension tubes are fastened together by connecting bolts. To ensure sealing, a sealing gasket can be provided between the two extension tubes. Figure 3 Only the docking method of the two extension tubes is illustrated, and the sealing gasket and the connecting bolts are not shown. The vacuum channel 13 is for the second cooling member to pass through. The second cooling member located in the vacuum channel 13 has one end extending to the first vacuum cover 11 to connect with the cold end of the cryostat, and the other end extending to the second vacuum cover 12 to connect with the first cold stage 1.

[0050] An opening 14 is provided on the second vacuum cover 12 , and the opening 14 is directly opposite to the first cold stage 1 , so as to allow the objective lens 4 to approach or move away from the flow tube 2 , thereby facilitating the adjustment of the distance between the objective lens 4 and the flow tube 2 .

[0051] The vacuum cylinder 15 is disposed between the second vacuum cover 12 and the mounting seat 3. The vacuum cylinder 15 is a cylindrical structure with two open ends. One end of the vacuum cylinder 15 is sealed and connected to the opening 14 of the second vacuum cover 12, and the other end is sealed and connected to the mounting seat 3. The vacuum cylinder 15 is used to reduce the cold loss of the objective lens 4 to the outside and reduce heat leakage.

[0052] The vacuum cylinder 15, the second vacuum cover 12, the vacuum channel 13 and the first vacuum cover 11 are connected, and the vacuum cylinder 15, the second vacuum cover 12, the vacuum channel 13 and the first vacuum cover 11 can be evacuated simultaneously using only the same vacuum pumping device, which is convenient for operation and management.

[0053] A quick-release connector may be provided on the first vacuum cover 11 and the second vacuum cover 12 for connecting a vacuum pumping device to realize a vacuum pumping operation.

[0054] In this embodiment, a sealing structure is provided between the second vacuum cover 12 and the circulation tube 2 to prevent the cold energy in the second vacuum cover 12 from being lost to the outside through the gap between the second vacuum cover 12 and the circulation tube 2 .

[0055] The sealing structure includes a connecting pipe 16 , an end cover 17 , a sealing ring 18 and a pressing member 19 .

[0056] The connecting pipe 16 is disposed on the second vacuum housing 12 , and is used for allowing the flow pipe 2 to enter and exit the second vacuum housing 12 .

[0057] The end cap 17 is arranged at one end of the connecting pipe 16 away from the second vacuum cover 12, and the end cap 17 is sealed and connected to the connecting pipe 16. A through hole is arranged on the end cap 17 for the circulation pipe 2 to pass through, and the sealing ring 18 is sleeved on the outside of the circulation pipe 2, and the sealing ring 18 is tightly fitted with the circulation pipe 2. The pressing piece 19 is arranged on the side of the end cap 17 away from the connecting pipe 16, and the pressing piece 19 is threadedly connected with the end cap 17, so that the sealing ring 18 can be pressed against the end cap 17, so that the pressing piece 19 and the end cap 17 are tightly fitted with the sealing ring 18, so as to achieve the sealing of the gap around the circulation pipe 2.

[0058] Such an arrangement facilitates the assembly connection between the circulation tube 2 and the second vacuum cover 12, and the sealing structure is a dynamic seal, which can allow the circulation tube 2 to move relative to the second vacuum cover 12, the connecting tube 16, the end cover 17, the sealing ring 18 and the clamping piece 19, and can adapt to the relative position displacement of the circulation tube 2 and the second vacuum cover 12 caused by the thermal expansion and contraction of the circulation tube 2, thereby reducing stress.

[0059] The camera assembly includes an objective lens moving mechanism 36, a beam splitter and a light source 37, and a CCD camera 38, which are all arranged on the mounting seat 3. The beam splitter and the light source 37 are used to provide light and adjust the light intensity, and the CCD camera 38 is used to obtain the image of the cryogenic fluid at the position where the objective lens 4 is facing. The position of the mounting seat 3 is adjustable, and the objective lens moving mechanism 36 is used to adjust the position of the mounting seat 3 in the horizontal, longitudinal and vertical directions, thereby adjusting the distance between the objective lens 4 and the flow tube 2, and making the objective lens 4 face the position to be observed of the flow tube 2.

[0060] It should be noted that, during specific use, the CCD camera 38 needs to be connected to a display device so that the image information acquired by the CCD camera 38 can be presented on the display device for easy research.

[0061] In this embodiment, the vacuum cylinder 15 includes a first flexible bellows, one end of which is connected to the second vacuum cover 12, and the other end of which is connected to the mounting seat 3. The first flexible bellows can be deformed, and the deformation of the first flexible bellows can adapt to the displacement of the mounting seat 3 and the objective lens 4 relative to the second vacuum cover 12, and ensure that the sealing between the first flexible bellows and the second vacuum cover 12 and the sealing between the first flexible bellows and the mounting seat 3 are not affected.

[0062] In addition, the first flexible bellows realizes a flexible connection between the second vacuum cover 12 and the mounting base 3, and can also reduce the transmission of vibration of the second vacuum cover 12 to the mounting base 3 and the spectrometer and light source 37 and CCD camera 38 located on the mounting base 3, thereby reducing the impact of vibration on the camera assembly and ensuring the clarity and accuracy of visualization research.

[0063] In the embodiment of the present invention, the cryostat includes a refrigerator 20 , a first cold shield 24 , a second cold shield 26 , a helium source 28 , a third cold shield 29 and a fourth cold shield 30 .

[0064] The refrigerator 20 has a primary cold head 21 and a secondary cold head 22, and the temperature of the secondary cold head 22 is lower than that of the primary cold head 21. The refrigerator 20 may be a GM refrigerator or a GM pulse tube refrigerator, and does not require a cryogenic refrigerant, thereby improving the long-term stability and life of the system.

[0065] At least one primary cold head 21 and one secondary cold head 22 extend into the first vacuum cover 11, and a first cold shield 24 and a second cold shield 26 are both disposed in the first vacuum cover 11. The first cold shield 24 is disposed outside the primary cold head 21 to reduce the radiation heat leakage from the external environment to the primary cold head 21. The second cold shield 26 is disposed outside the secondary cold head 22 to reduce the radiation heat leakage from the external environment to the secondary cold head 22.

[0066] The first cold screen 24 is sealed and connected to the first vacuum cover 11 through the insulating tube 25, which can isolate the space between the first cold screen 24 and the first cold head 21 and the space between the first cold screen 24 and the first vacuum cover 11, and reduce the transfer of cold energy from the first cold screen 24 to the first vacuum cover 11, thereby reducing heat leakage.

[0067] Considering the insulation performance and mechanical properties of the insulation tube 25 , the sealed connection between the insulation tube 25 and the first cold shield 24 , and the sealed connection between the insulation tube 25 and the first vacuum cover 11 , the insulation tube 25 may be made of stainless steel.

[0068] The second cold shield 26 is connected to the first cold shield 24 through a cooling ring, and a second cold stage 27 is provided at one end of the second cold shield 26 away from the first cold shield 24, and the second cold stage 27 can seal the second cold shield 26. In this way, the space between the first cold shield 24 and the first-level cold head 21 and the space between the second cold shield 26 and the second-level cold head 22 are interconnected and in a closed state.

[0069] The helium source 28 is used to fill the space between the first cold shield 24 and the first-stage cold head 21 with helium, and the helium can also flow to the space between the second cold shield 26 and the second-stage cold head 22. The helium source 28 can be, but is not limited to, a helium storage tank.

[0070] The refrigerator 20 is turned on to provide a cold source. The temperature of the first-stage cold head 21 of the refrigerator 20 is higher than that of the second-stage cold head 22, and there is a temperature gradient. Due to the difference in the thermal field, the helium forms an annular convection heat exchange, and the reciprocating cycle cooling of the helium is realized. The helium is cooled to form liquid helium, which gathers downward above the second cold stage 27, and the liquid helium transfers the cold energy to the second cold stage 27.

[0071] The second cooling stage 27 is used to be connected to the second cooling conduction member, and the cooling energy of the second cooling stage 27 can be transferred to the first cooling stage 1 through the second cooling conduction member.

[0072] The cooling capacity of the second cold screen 26 is lower than that of the second cooling component. Specifically, the cooling capacity of the second cold screen 26 can be made as low as possible, and the cooling capacity of the second cold screen 26 is much lower than that of the second cooling component, so that the cooling capacity of the second cold stage 27 can be transferred to the first cold stage 1 as much as possible, and the cooling capacity of the second cold stage 27 is reduced to the second cold screen 26 and the cooling ring, thereby reducing heat leakage.

[0073] A cold head heat exchanger 23 is provided on the secondary cold head 22. The cold head heat exchanger 23 may be a block structure made of copper, which has a strong cooling effect. The block structure is provided with a plurality of fins, which can increase the contact area with the helium, thereby greatly improving the cooling efficiency of the secondary cold head 22 for the helium.

[0074] The third cold shield 29 is disposed in the first vacuum cover 11, and the third cold shield 29 is disposed outside the second cold shield 26. One end of the third cold shield 29 is closed, and the other end is connected to the cooling ring. The third cold shield 29 is located outside the second cold stage 27, and is used to reduce the radiation heat leakage of the external environment to the second cold stage 27.

[0075] The fourth cold shield 30 is disposed in the vacuum channel 13 , and the fourth cold shield 30 is disposed outside the second cooling member to reduce radiation heat leakage from the external environment to the second cooling member.

[0076] One end of the fourth cold shield 30 extends to the first vacuum cover 11, and the fourth cold shield 30 is connected to the third cold shield 29. The other end of the fourth cold shield 30 extends into the second vacuum cover 12, and the fourth cold shield 30 extends to an end of the second cooling member away from the first vacuum cover 11.

[0077] A notch is provided on the fourth cold stage 30 at a position corresponding to the first cold stage 1 , so that the first cold stage 1 can pass through the fourth cold stage 30 .

[0078] When the first cooling member is used to connect the cold end of the cryostat to the objective lens 4, the first cooling member can be connected to the fourth cold shield 30 of the cryostat. The first cooling member can be a flexible copper braid to ensure the transfer of cold and reduce the transfer of vibration to the objective lens 4.

[0079] In the embodiment of the present invention, the in-situ observation device for cryogenic fluid further includes an optical vibration reduction platform 31 , an air-floating vibration reduction bracket and a second flexible bellows 35 .

[0080] The optical vibration reduction platform 31 is arranged on the ground, and the first vacuum cover 11 and the second vacuum cover 12 are both arranged on the optical vibration reduction platform 31. The optical vibration reduction platform 31 is used to provide support for the first vacuum cover 11 and the second vacuum cover 12, and can reduce the transmission of vibration on the ground side to the first vacuum cover 11 and the second vacuum cover 12. At the same time, it can reduce the vibration of the first vacuum cover 11 and the second vacuum cover 12 themselves to a certain extent.

[0081] The air-floating vibration-damping bracket comprises a support platform 32 and a support frame 33, wherein the support frame 33 is used to support the support platform 32. An air-floating vibration damper 34 is arranged at the lower end of the support frame 33 to reduce the transmission of vibration.

[0082] The body of the refrigerator 20 is arranged above the support platform 32, the first-stage cold head 21 and the second-stage cold head 22 extend to the bottom of the support platform 32, and the first vacuum cover 11 is located below the support platform 32. The air-floating vibration-damping bracket can support the refrigerator 20, and can reduce the transmission of vibration between the refrigerator 20 and the ground, reduce the transmission of vibration on the ground side to the refrigerator 20, and can reduce the vibration of the refrigerator 20 itself.

[0083] The second flexible bellows 35 is disposed between the support platform 32 and the first vacuum cover 11, one end of the second flexible bellows 35 is connected to the first vacuum cover 11, and the other end of the second flexible bellows 35 is connected to the support platform 32. The second flexible bellows 35 can be deformed, and the second flexible bellows 35 realizes the flexible connection between the first vacuum cover 11 and the support platform 32, which can reduce the transmission of the vibration of the refrigerator 20 to the first vacuum cover 11, and further reduce the vibration transmitted to the second vacuum cover 12 and the camera assembly, reduce the influence of the vibration on the camera assembly, and ensure the clarity and accuracy of the visualization research.

[0084] In this way, combined with the setting of the second flexible bellows 35 and the reciprocating cycle cooling of helium, the cold capacity of the refrigerator 20 is transferred to the second cold stage 27, while the rigid connection between the refrigerator 20 and the second cold stage 27 is avoided, which greatly reduces the transmission of the vibration of the refrigerator 20 to the second cold stage 27.

[0085] For the structure related to the helium source 28 filling the space between the primary cold head 21 and the first cold screen 24 with helium, an inflatable seat 39 may be provided above the support platform 32, and the inflatable seat 39 is sealed and connected to the support platform 32. An inflatable channel is provided on the inflatable seat 39, and a connecting channel for connecting the inflatable channel and the space between the primary cold head 21 and the first cold screen 24 is provided on the support platform 32. The helium source 28 is connected with the inflatable channel, and the helium passes through the inflatable channel of the inflatable seat 39 and the connecting channel of the support platform 32 in sequence, and can enter the space between the primary cold head 21 and the first cold screen 24.

[0086] It should be noted that an exhaust channel is also provided on the gas charging seat 39, one end of the exhaust channel is connected to the space between the primary cold head 21 and the first cold screen 24, and the other end of the exhaust channel is connected to a vacuum pumping device. When filling the space between the primary cold head 21 and the first cold screen 24 with helium, it is necessary to first perform a vacuum pumping operation on the space between the primary cold head 21 and the first cold screen 24 to discharge the residual gas in the space between the primary cold head 21 and the first cold screen 24, and ensure the purity of the helium between the primary cold head 21 and the first cold screen 24. In addition, when filling the space between the primary cold head 21 and the first cold screen 24 with helium, a gas washing operation can be performed, which will not be elaborated in detail.

[0087] In summary, the embodiment of the present invention combines the use of the refrigerator 20 and the sealing and anti-heat leakage settings at various positions, so that the in-situ observation device of the low-temperature fluid can meet the observation of fluids in a wide temperature range of 10~300K, and can cover the working temperature range of low-temperature fluids such as liquid hydrogen, liquid neon, liquid nitrogen, liquid oxygen and liquefied natural gas.

[0088] The following describes the method for using the in-situ observation device for cryogenic fluids provided in this embodiment by taking the visualization study of the flow and heat transfer characteristics of a liquid nitrogen-nitrogen vapor two-phase flow as an example.

[0089] First, a vacuum pumping device is used to perform a vacuum pumping operation until the pressure inside the first vacuum cover 11 and the second vacuum cover 12 is less than 10 -3 Pa or less. Then, the refrigerator 20 is turned on, and helium is filled from the helium source 28 to realize reciprocating cycle cooling of the helium. When the temperature in the second vacuum cover 12 drops to about 77K and reaches a steady state, nitrogen is introduced into the circulation pipe 2. When the nitrogen flows through the circulation pipe 2 to the position where the first cold stage 1 is located, the liquid nitrogen-nitrogen vapor two-phase flow state is reached. The CCD camera 38 and the light source are started, and the position of the objective lens 4 is adjusted so that the CCD camera 38 can obtain the image of the low-temperature fluid at the position where the objective lens 4 is located, and the image obtained by the CCD camera 38 is presented using a display device, thereby realizing the fine in-situ observation of the flow and heat exchange characteristics of the liquid nitrogen-nitrogen vapor two-phase flow.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An in-situ observation device for cryogenic fluid, characterized in that: include: A two-phase flow generating mechanism, comprising a low temperature thermostat, a first cold stage (1) and a flow pipe (2), wherein the flow pipe (2) is suitable for allowing fluid to pass through, the flow pipe (2) is arranged on the first cold stage (1), the low temperature thermostat is suitable for providing cold energy to the first cold stage (1), and the first cold stage (1) is suitable for transferring cold energy to the flow pipe (2); An observation mechanism, comprising a mounting seat (3), an objective lens (4), a light-transmitting plate (5) and a camera assembly, wherein the light-transmitting plate (5) is arranged on the mounting seat (3), the light-transmitting plate (5) is sealedly connected to the mounting seat (3), the objective lens (4) and the camera assembly are both arranged on the mounting seat (3), and the objective lens (4) and the camera assembly are respectively located on two opposite sides of the light-transmitting plate (5), and the objective lens (4) faces the flow tube (2) on the first cold stage (1); A vacuum cover is arranged outside the two-phase flow generating mechanism and the objective lens (4), the vacuum cover is sealedly connected to the mounting seat (3), both ends of the flow tube (2) extend to the outside of the vacuum cover, and the flow tube (2) is sealedly connected to the vacuum cover.

2. The in-situ observation device for cryogenic fluid according to claim 1, characterized in that: Also includes: A first cooling conductor is arranged between the cold end of the cryostat and the objective lens (4), and the first cooling conductor is suitable for transferring the cold energy of the cold end of the cryostat to the objective lens (4).

3. The in-situ observation device for cryogenic fluid according to claim 1, characterized in that: The first cold stage (1) is provided with a containing groove (6), and the flow pipe (2) is passed through the containing groove (6).

4. The in-situ observation device for cryogenic fluid according to claim 1, characterized in that: Also includes: A second cooling member is arranged between the cold end of the cryostat and the first cold stage (1), and the second cooling member is suitable for transferring the cold energy of the cold end of the cryostat to the first cold stage (1).

5. The in-situ observation device for cryogenic fluid according to claim 4, characterized in that: The second cooling member comprises: A cooling rod (7), wherein at least two first connection holes (8) are arranged at one end of the cooling rod (7) close to the objective lens (4), and each of the first connection holes (8) is spaced apart along the axial direction of the cooling rod (7); the first cold stage (1) has a connecting portion (9), and a second connection hole (10) is arranged on the connecting portion (9), and the second connection hole (10) is suitable for being connected to any one of the first connection holes (8) by a connecting bolt.

6. The in-situ observation device for cryogenic fluid according to claim 4, characterized in that: The vacuum hood comprises: A first vacuum cover (11), which is arranged outside the cryostat; a second vacuum cover (12) disposed outside the first cold stage (1) and the circulation tube (2); a vacuum passage (13) for the second cooling member to pass through is formed between the second vacuum cover (12) and the first vacuum cover (11); an opening (14) is provided on the second vacuum cover (12) at a position facing the first cold stage (1); the opening (14) allows the objective lens (4) to approach or move away from the circulation tube (2); A vacuum cylinder (15) is arranged between the second vacuum cover (12) and the mounting seat (3); one end of the vacuum cylinder (15) is sealedly connected to the opening (14) of the second vacuum cover (12), and the other end is sealedly connected to the mounting seat (3).

7. The in-situ observation device for cryogenic fluid according to claim 6, characterized in that: A sealing structure is provided between the second vacuum cover (12) and the flow pipe (2), the sealing structure comprising: A connecting pipe (16) is arranged on the second vacuum cover (12), the connecting pipe (16) being suitable for allowing the flow pipe (2) to enter and exit the second vacuum cover (12); an end cover (17) disposed at an end of the connecting pipe (16) away from the second vacuum cover (12), the end cover (17) being sealedly connected to the connecting pipe (16), and the end cover (17) being provided with a through hole for the circulation pipe (2) to pass through; A sealing ring (18) is sleeved on the outside of the circulation tube (2), and the sealing ring (18) is tightly fitted to the circulation tube (2); A pressing piece (19) is arranged on a side of the end cover (17) away from the connecting pipe (16), the pressing piece (19) is threadedly connected to the end cover (17), and the pressing piece (19) is suitable for pressing the sealing ring (18) against the end cover (17).

8. The in-situ observation device for cryogenic fluid according to claim 6, characterized in that: The vacuum cylinder (15) comprises a first flexible bellows.

9. The in-situ observation device for cryogenic fluid according to any one of claims 6 to 8, characterized in that: The cryostat comprises: A refrigerator (20) having a primary cold head (21) and a secondary cold head (22), wherein at least the primary cold head (21) and the secondary cold head (22) extend into the first vacuum cover (11), and the secondary cold head (22) is provided with a cold head heat exchanger (23); A first cold shield (24) is arranged in the first vacuum cover (11), the first cold shield (24) is arranged outside the first-stage cold head (21), and the first cold shield (24) is sealed and connected to the first vacuum cover (11) via an insulating tube (25); A second cold shield (26) is arranged in the first vacuum cover (11), the second cold shield (26) is arranged outside the secondary cold head (22), the second cold shield (26) is connected to the first cold shield (24) via a cooling ring, a second cold stage (27) is arranged at one end of the second cold shield (26) away from the first cold shield (24), the second cold stage (27) is suitable for connecting with the second cooling member, and the cooling capacity of the second cold shield (26) is lower than the cooling capacity of the second cooling member; a helium source (28) adapted to fill the space between the first cold shield (24) and the first-stage cold head (21) with helium; A third cold shield (29) is arranged in the first vacuum cover (11), the third cold shield (29) is arranged outside the second cold shield (26), one end of the third cold shield (29) is closed, and the other end is connected to the cooling ring; A fourth cold shield (30) is arranged in the vacuum channel (13); the fourth cold shield (30) is covered outside the second cooling member; one end of the fourth cold shield (30) extends to the first vacuum cover (11) and is connected to the third cold shield (29); and the other end of the fourth cold shield (30) extends into the second vacuum cover (12).

10. The in-situ observation device for cryogenic fluid according to claim 9, characterized in that: Also includes: An optical vibration reduction platform (31), wherein the first vacuum cover (11) and the second vacuum cover (12) are both arranged on the optical vibration reduction platform (31); An air-floating vibration-damping bracket, comprising a support platform (32) and a support frame (33) for supporting the support platform (32), the body of the refrigerator (20) being arranged above the support platform (32), the first-stage cold head (21) and the second-stage cold head (22) extending below the support platform (32), and an air-floating vibration-damping device (34) being arranged at the lower end of the support frame (33); A second flexible bellows (35) is arranged between the support platform (32) and the first vacuum cover (11).

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