CN109668714B - Experimental device and method for impacting rigid wall surface by low-temperature liquid drops - Google Patents
Experimental device and method for impacting rigid wall surface by low-temperature liquid drops Download PDFInfo
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- CN109668714B CN109668714B CN201910038829.3A CN201910038829A CN109668714B CN 109668714 B CN109668714 B CN 109668714B CN 201910038829 A CN201910038829 A CN 201910038829A CN 109668714 B CN109668714 B CN 109668714B
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- 239000007788 liquid Substances 0.000 title claims abstract description 184
- 238000000034 method Methods 0.000 title claims abstract description 17
- 230000003116 impacting effect Effects 0.000 title claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 272
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 136
- 238000001816 cooling Methods 0.000 claims description 15
- 238000001704 evaporation Methods 0.000 claims description 6
- 230000008020 evaporation Effects 0.000 claims description 6
- 238000004321 preservation Methods 0.000 claims description 6
- 238000003466 welding Methods 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 3
- 238000002474 experimental method Methods 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 239000010949 copper Substances 0.000 claims description 2
- -1 polytetrafluoroethylene Polymers 0.000 claims description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 2
- 229910000679 solder Inorganic materials 0.000 claims description 2
- 229910001220 stainless steel Inorganic materials 0.000 claims description 2
- 239000010935 stainless steel Substances 0.000 claims description 2
- 238000003556 assay Methods 0.000 claims 1
- 238000009413 insulation Methods 0.000 abstract description 3
- 238000012800 visualization Methods 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 239000001273 butane Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M10/00—Hydrodynamic testing; Arrangements in or on ship-testing tanks or water tunnels
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B25/00—Models for purposes not provided for in G09B23/00, e.g. full-sized devices for demonstration purposes
Abstract
The invention provides a low-temperature liquid drop impact rigid wall experimental device and a method, wherein the experimental device comprises a liquid nitrogen liquid supply system, an impact cavity system, a low-temperature liquid drop generator, a visualization and data acquisition system; the liquid nitrogen liquid supply system comprises a liquid nitrogen pipeline and an emptying bypass, the shell of the impact cavity system is composed of a heat insulation layer and a precooling channel and is connected with a vacuum pump, a pressure sensor and a temperature sensor, the inside of the impact cavity system comprises a rigid impacted wall surface with adjustable height, a scale and a low-temperature liquid drop generator, and the visualization and data acquisition system comprises a data acquisition device, a light source and a high-speed camera. The invention uses the low-temperature vapor evaporated by liquid nitrogen to precool the inside of the impinging cavity through the precooling channel, thereby realizing the multistage utilization of the liquid nitrogen; the liquid nitrogen supply pressure, the pipe diameter of the 90-degree bent pipe and the height of the rigid impacted wall surface are adjusted to change the diameter of the liquid drop and the impact speed, and a high-speed camera is utilized to capture the impact process of the liquid drop.
Description
Technical Field
The invention relates to a device for testing impact of low-temperature liquid drops on a rigid wall surface, and also relates to an operation method of the device, which has the characteristics of excellent heat insulation performance, controllable diameter and speed of the low-temperature liquid drops, visual impact process and the like.
Background
At present, spray cooling is a very potential efficient cooling mode, and the process involves single liquid drop impact on a wall surface, liquid drop and interaction between liquid drop and liquid film, belongs to a complex multiphase flow problem, and needs to carry out basic research on fluid dynamics under a simplified flow geometry condition. Although spray cooling cannot be expressed as a mechanical addition of individual droplets striking a wall, individual droplets striking a rigid wall have been widely used to describe the process of spray impingement and predict the outcome thereof.
The dynamics and thermodynamic experiment research of single liquid drop impacting the rigid wall surface mainly uses normal temperature medium such as water, ethanol solution, diesel oil, butane and the like, and small liquid drops are generated by an injector; because low-temperature working media such as liquid nitrogen and the like have lower boiling points under normal pressure, the low-temperature liquid drops generated by adopting the traditional mode are immediately evaporated completely at the bottom of a needle hole of the injector, and stable liquid drops cannot be formed, so that experimental research of impacting the rigid wall surface by the low-temperature liquid drops cannot be carried out by adopting the traditional experimental device.
Disclosure of Invention
The invention aims to solve the problem that the traditional experimental device is difficult to develop experimental study of low-temperature liquid drop impact on the rigid wall surface, and provides the low-temperature liquid drop impact rigid wall surface experimental device which is convenient for developing basic study of dynamics and thermodynamic characteristics of the low-temperature liquid drop impact on the rigid wall surface, and has the characteristics of excellent heat insulation performance of an impact cavity, controllable diameter and speed of the low-temperature liquid drop, visual impact process and the like.
The experimental device comprises an impact cavity; the outer layer of the striking cavity is sequentially provided with a precooling channel, a vacuum layer and a heat preservation layer from inside to outside; the inner wall of the precooling channel is provided with an inlet for communicating the striking cavity with the precooling channel, the outer wall of the precooling channel is provided with an outlet, and the outlet sequentially passes through the vacuum layer and the heat preservation layer through a pipeline and is connected with an external vacuum pump;
a cylindrical liquid nitrogen container, a 90-degree bent pipe and a rigid impacted surface are arranged in the impact cavity; the cylindrical liquid nitrogen container and the 90-degree bent pipe form a low-temperature liquid drop generator; the horizontal pipe part of the 90-degree bent pipe is embedded into the side wall of the cylindrical liquid nitrogen container; the vertical pipe part of the 90-degree bent pipe is positioned at the center of the horizontal direction of the impact cavity, and the rigid impacted surface is positioned right below the vertical pipe part; the inside of the impact cavity is also provided with a temperature sensor, a pressure sensor, a scale, a light source, a high-speed camera and a data acquisition unit; the data acquisition device is connected with the temperature sensor, the pressure sensor and the high-speed camera;
the experimental device also comprises a high-pressure nitrogen bottle; the outlet of the high-pressure nitrogen cylinder is respectively connected with two branches of an emptying bypass and a liquid nitrogen pipeline after passing through a pressure reducing valve and a pressure sensor; the two branches are combined and then connected with a liquid nitrogen tank; a stop valve, a liquid nitrogen Dewar tank and a low-temperature electromagnetic valve are sequentially arranged on the liquid nitrogen pipeline; the outlet of the liquid nitrogen tank is connected with a cylindrical liquid nitrogen container in the impact cavity after passing through a flowmeter; the pipeline between the flowmeter and the cylindrical liquid nitrogen container sequentially passes through the heat preservation layer, the vacuum layer and the precooling channel; the top of the liquid nitrogen Dewar tank is connected with a pressure release valve and a pressure sensor.
The invention also relates to a using method of the low-temperature liquid drop impact rigid wall experimental device, which comprises the following steps:
before the start of the experiment, all valves except the pressure relief valve were closed.
Firstly, a light source and a high-speed camera are started, the distance between the lower end of a 90-degree bent pipe in an impact cavity and a rigid impacted surface is adjusted, the height is fixed, a pressure reducing valve and a stop valve of an emptying bypass are sequentially opened, so that nitrogen sequentially passes through the emptying bypass, a liquid nitrogen tank, a flowmeter, a cylindrical liquid nitrogen container and the 90-degree bent pipe to enter the impact cavity, and air in the impact cavity is discharged;
starting a vacuum pump, maintaining the pressure in the impact cavity to be about 1 MPa, and continuously evacuating until the air in the impact cavity is completely replaced by nitrogen;
step three, closing a stop valve of an emptying bypass, opening a stop valve of a liquid nitrogen pipeline and a low-temperature electromagnetic valve, discharging liquid nitrogen in a liquid nitrogen Dewar tank into the liquid nitrogen pipeline under the action of high-pressure nitrogen, pre-cooling the liquid nitrogen to the vicinity of 78K by a liquid nitrogen tank, measuring the volume flow rate of the liquid nitrogen when the liquid nitrogen enters a low-temperature liquid drop generator by a flowmeter, and recording the volume flow rate;
step four, in order to prevent the generated liquid nitrogen drops from being gasified rapidly and being unable to strike the rigid impacted surface in the form of liquid drops, the liquid nitrogen must be sprayed into the impact cavity first to reduce the temperature of the environment in the impact cavity, the diameter of the pressure reducing valve and the 90-degree bent pipe are adjusted to control the volume flow rate of the liquid nitrogen, once the pipe wall is cooled, the liquid overflows to the outer surface of the pipe through the opening of the 90-degree bent pipe, accumulates at the welding end, breaks away to form liquid drops under the action of gravity, and the pressure and the temperature in the impact cavity are recorded;
and fifthly, calibrating the diameter of the liquid drop by using a high-speed camera and a scale, calculating the initial impact speed, and capturing the motion behavior and the evaporation process of the liquid drop after impacting the rigid impacted surface.
The nitrogen in the high-pressure nitrogen cylinder discharges the liquid nitrogen stored in the liquid nitrogen Dewar tank into a liquid nitrogen pipeline, the liquid nitrogen enters a low-temperature liquid drop generator after being precooled by a liquid nitrogen tank, the liquid nitrogen overflows to the outer surface of the pipe through an opening of a 90-degree bent pipe, is accumulated at a welding end and is separated under the self weight to form stable liquid nitrogen drops, and the liquid nitrogen drops vertically and downwards do free falling movement and finally collide with a rigid impacted surface; on the one hand, because the boiling point of liquid nitrogen is lower, air in the impact cavity must be discharged, or ice blockage is easy to occur at the opening of the 90-degree bent pipe, on the other hand, the ambient temperature is relatively high, liquid nitrogen is atomized and then rapidly evaporated, a large amount of low-temperature vapor is generated, the pressure in the impact cavity is increased, the low-temperature vapor is forced to enter the pre-cooling channel through the inlet of the pre-cooling channel and is discharged out of the impact cavity after surrounding the impact cavity for a week, the impact cavity can be effectively pre-cooled, and the rapid evaporation of liquid drops before impacting the rigid wall surface is restrained.
The low-temperature liquid drop generator is formed by the cylindrical liquid nitrogen container and the 90-degree bent pipe, the cylindrical liquid nitrogen container is made of polytetrafluoroethylene, the specification is D= cm and H= cm, the bottom of the 90-degree bent pipe is blocked by solder, the middle outer wall of the 90-degree bent pipe is provided with small holes, the material is stainless steel, the pipe diameter is adjustable within 0.5-3 mm, and the diameter of the low-temperature liquid drop can be controlled by replacing bent pipes with different pipe diameters.
The height of the rigid impacted surface is adjustable, and the wall surface area is 1 cm 2 The material is red copper, the scale is vertically fixed on the rigid impacted surface, and the scale is used for calibrating the diameter of the liquid drop.
Aiming at the defects existing in the prior art, the invention realizes the control of the diameter of the low-temperature liquid drop by adjusting the pressure of the liquid supply and the diameter of the 90-degree bent pipe; the initial speed of impact of the low-temperature liquid drops is regulated by regulating the height of the rigid impacted surface; precooling the inside of the impact cavity by adopting a liquid nitrogen vapor precooling channel to inhibit the rapid evaporation of low-temperature liquid drops; the diameter of the low-temperature liquid drop is calibrated by adopting a high-speed camera and a vertical scale fixed on the rigid impacted surface, and the dynamic spreading process of the liquid drop impacting the rigid wall surface is captured.
Drawings
FIG. 1 is a schematic diagram of the composition of the experimental device for impact of low-temperature liquid drops on a rigid wall surface;
fig. 2 is a schematic diagram of the structure of the cryogenic liquid droplet generator of the invention.
Reference numerals in the figures: the device comprises a high-pressure nitrogen cylinder 1, a pressure reducing valve 2, a pressure sensor 3, a stop valve 4, a liquid nitrogen dewar tank 5, a pressure reducing valve 6, an emptying bypass 7, a liquid nitrogen pipeline 8, a low-temperature electromagnetic valve 9, a liquid nitrogen tank 10, a flowmeter 11, a heat-insulating layer 12, a vacuum layer 13, a precooling channel 14, a bent pipe 15 degrees, a high-speed camera 16, a scale 17, a rigid impacted surface 18, a vacuum pump 19, a cylindrical liquid nitrogen container 20, a temperature sensor 21, a light source 22, an impacting cavity 23 and a data collector 24.
Detailed description of the preferred embodiments
The low-temperature liquid drop impact rigid wall experimental device of the invention is described below with reference to the accompanying drawings, and fig. 1 is a schematic diagram of the composition of the low-temperature liquid drop impact rigid wall experimental device of the invention, and the device comprises: the liquid nitrogen liquid supply system, the impact cavity system, the low-temperature liquid drop generator, the visualization and data acquisition system; the high-pressure nitrogen cylinder 1, the pressure reducing valve 2, the stop valve 4, the liquid nitrogen Dewar tank 5 and the low-temperature electromagnetic valve 9 respectively form an evacuation bypass 7 and a liquid nitrogen pipeline 8, the evacuation bypass 7 and the liquid nitrogen pipeline 8 are connected in parallel and then connected with a cylindrical liquid nitrogen container 20 through a liquid nitrogen tank 10 and a flowmeter 11, a 90-degree bent pipe 15 horizontal pipe is partially embedded into the side wall of the cylindrical liquid nitrogen container 20 to form a liquid drop generator, a scale 17 is arranged on the upper surface of a rigid impacted surface 18 with adjustable height, a vacuum pump 19 is connected with a pipeline at the top of the left side of a precooling channel 14, an insulating layer 12 and a vacuum layer 13 are heat insulating layers of an impact cavity 23, and the pressure sensor 3, a temperature sensor 21 and a high-speed camera 16 are connected with an external data collector 24.
Fig. 2 is a schematic structural view of the low-temperature droplet generator of the present invention, wherein the low-temperature droplet generator comprises a cylindrical liquid nitrogen container 20 and a 90 ° elbow 15, the horizontal pipe portion of the 90 ° elbow 15 is embedded into the side wall of the cylindrical liquid nitrogen container 20, liquid nitrogen enters the cylindrical liquid nitrogen container 20 and the 90 ° elbow 15 after being precooled by a liquid nitrogen tank 10, once the pipe wall is cooled, liquid nitrogen overflows to the outer surface of the pipe through an opening of the 90 ° elbow 15, accumulates at the welding end, and is separated under the self weight, thus forming stable liquid nitrogen droplets.
After the system is started, firstly, an evacuation bypass 7 is opened to fully replace the gas in the impact cavity 23 with nitrogen so as to prevent ice blockage; nitrogen in the high-pressure nitrogen cylinder 1 is discharged into a liquid nitrogen pipeline 8 through liquid nitrogen stored in a liquid nitrogen Dewar tank 5, and enters a liquid drop generator to generate stable low-temperature liquid drops after being precooled by a liquid nitrogen tank 10, the liquid drops freely fall to strike a rigid impacted surface 18, and the liquid nitrogen tank 10 is kept near 78K for ensuring that the temperature of the liquid nitrogen enters the low-temperature liquid drop generator; the purpose of the pre-cooling channel 14 is to fully utilize low-temperature nitrogen evaporated by liquid nitrogen to reduce the temperature in the impact cavity 23, and the evaporated nitrogen is guided to wind the channel for a circle at the inlet at the top of the right side of the pre-cooling channel 14 and then is discharged out of the impact cavity 23 through the outlet at the top of the left side of the pre-cooling channel 14; the vacuum pump 19 was used to stabilize the pressure in the impingement chamber 23 at 1 MPa and the droplet diameter was measured using the scale 17 and the high-speed camera 16.
The liquid nitrogen Dewar 5 is liquid nitrogen liquid supply equipment, and provides reliable and sufficient liquid nitrogen for the system, and the liquid nitrogen Dewar 5 is connected with the pressure sensor 3 and the pressure release valve 6 to prevent the pressure in the liquid nitrogen Dewar 5 from increasing due to slow evaporation in the long-term storage process of the liquid nitrogen;
the using method of the low-temperature liquid drop impact rigid wall experimental device comprises the following steps:
(1) Firstly, a light source and a high-speed camera are started, the distance between the lower end of a 90-degree bent pipe in an impact cavity and a rigid impacted surface is adjusted, the height is fixed, a pressure reducing valve and a stop valve of an emptying bypass are sequentially opened, so that nitrogen sequentially passes through the emptying bypass, a liquid nitrogen tank, a flowmeter, a cylindrical liquid nitrogen container and the 90-degree bent pipe to enter the impact cavity, and air in the impact cavity is discharged;
(2) Starting a vacuum pump, maintaining the pressure in the striking cavity to be about 1 MPa, and continuously evacuating until the air in the striking cavity is completely replaced by nitrogen;
(3) Closing a stop valve of an emptying bypass, opening a stop valve of a liquid nitrogen pipeline and a low-temperature electromagnetic valve, discharging liquid nitrogen in a liquid nitrogen Dewar tank into the liquid nitrogen pipeline under the action of high-pressure nitrogen, pre-cooling the liquid nitrogen to the vicinity of 78K by a liquid nitrogen tank, measuring the volume flow rate of the liquid nitrogen when the liquid nitrogen enters a low-temperature liquid drop generator by a flowmeter, and recording the volume flow rate;
(4) In order to prevent the generated liquid nitrogen drops from being gasified rapidly and being unable to strike the rigid impacted surface in the form of liquid drops, the liquid nitrogen must be sprayed into the striking cavity first to reduce the temperature of the internal environment of the striking cavity, the volume flow rate of the liquid nitrogen is controlled by adjusting the diameter of the pressure reducing valve and the 90-degree bent pipe, once the pipe wall is cooled, the liquid overflows to the outer surface of the pipe through the opening of the 90-degree bent pipe, accumulates at the welding end, breaks away to form liquid drops under the action of gravity, and the pressure and the temperature in the striking cavity are recorded;
(5) And calibrating the diameter of the liquid drop by using a high-speed camera and a scale, calculating the initial impact speed, and capturing the motion behavior and the evaporation process of the liquid drop after impacting the rigid impacted surface.
Claims (2)
1. A low-temperature droplet impact rigid wall experimental device is characterized in that,
the experimental device comprises an impact cavity (23); the outer layer of the striking cavity (23) is sequentially provided with a precooling channel (14), a vacuum layer (13) and a heat preservation layer (12) from inside to outside; an inlet for enabling the impact cavity (23) to be communicated with the pre-cooling channel (14) is formed in the inner wall of the pre-cooling channel (14), an outlet is formed in the outer wall of the pre-cooling channel (14), and the outlet sequentially penetrates through the vacuum layer (13) and the heat preservation layer (12) through a pipeline to be connected with an external vacuum pump (19);
a cylindrical liquid nitrogen container (20), a 90-degree bent pipe (15) and a rigid impacted surface (18) are arranged in the impact cavity (23); the cylindrical liquid nitrogen container (20) and the 90-degree bent pipe (15) form a low-temperature liquid drop generator; the horizontal pipe part of the 90-degree bent pipe (15) is embedded into the side wall of the cylindrical liquid nitrogen container (20); the vertical pipe part of the 90-degree elbow pipe (15) is positioned at the center of the horizontal direction of the impact cavity (23), and the rigid impacted surface (18) is positioned right below the impact cavity; a temperature sensor (21), a pressure sensor (3), a scale (17), a light source (22), a high-speed camera (16) and a data collector (24) are also arranged in the impact cavity (23); the data collector (24) is connected with the temperature sensor (21), the pressure sensor (3) and the high-speed camera (16);
the experimental device also comprises a high-pressure nitrogen cylinder (1); the outlet of the high-pressure nitrogen cylinder (1) is respectively connected with two branches of an emptying bypass (7) and a liquid nitrogen pipeline (8) after passing through a pressure reducing valve (2) and a pressure sensor (3); the two branches are combined and then connected with an inlet of a liquid nitrogen tank (10); a stop valve (4) is arranged on the emptying bypass (7), and the stop valve (4), the liquid nitrogen Dewar (5) and the low-temperature electromagnetic valve (9) are sequentially arranged on the liquid nitrogen pipeline (8); an outlet of the liquid nitrogen tank (10) is connected with a cylindrical liquid nitrogen container (20) in the impact cavity (23) after passing through a flowmeter (11); the pipeline between the flowmeter (11) and the cylindrical liquid nitrogen container (20) sequentially passes through the heat preservation layer (12), the vacuum layer (13) and the pre-cooling channel (14); the top of the liquid nitrogen Dewar tank (5) is connected with a pressure release valve (6) and a pressure sensor (3);
the cylindrical liquid nitrogen container (20) is made of polytetrafluoroethylene, the specification is D= cm and H= cm, the bottom of the 90-degree bent pipe (15) is blocked by solder, the middle outer wall is provided with small holes, the cylindrical liquid nitrogen container is made of stainless steel, and the pipe diameter is adjustable within 0.5-3 mm;
the rigid impacted surface (18) has adjustable height and wall surface area of 1 cm 2 The material is red copper, and the scale (17) is vertically fixed on the rigid impacted surface (18).
2. A method of using the cryogenic liquid drop impact rigid wall assay device of claim 1, characterized by the steps of:
before the experiment starts, all valves except the pressure release valve (6) are in a closed state;
firstly, a light source (22) and a high-speed camera (16) are started, the distance from the lower end of a 90-degree bent pipe (15) in an impact cavity (23) to a rigid impacted surface (18) is adjusted, the height is fixed, a pressure reducing valve (2) and a stop valve (4) of an emptying bypass (7) are sequentially opened, so that nitrogen sequentially passes through the emptying bypass (7), a liquid nitrogen tank (10), a flowmeter (11), a cylindrical liquid nitrogen container (20) and the 90-degree bent pipe (15) to enter the impact cavity (23), and air in the impact cavity (23) is discharged;
starting a vacuum pump (19), maintaining the pressure in the impact cavity (23) to be about 1 MPa, and continuously exhausting until the air in the impact cavity (23) is completely replaced by nitrogen;
step three, closing a stop valve (4) of an emptying bypass (7), opening the stop valve (4) of a liquid nitrogen pipeline (8) and a low-temperature electromagnetic valve (9), discharging liquid nitrogen in a liquid nitrogen Dewar tank (5) into the liquid nitrogen pipeline (8) under the action of high-pressure nitrogen, pre-cooling the liquid nitrogen to the vicinity of 78K by a liquid nitrogen tank (10), measuring the volume flow rate of the liquid nitrogen when the liquid nitrogen enters a low-temperature liquid drop generator by a flowmeter (11), and recording the volume flow rate;
in order to prevent the generated liquid nitrogen drops from being gasified rapidly and being unable to impact the rigid impacted surface (18) in the form of liquid drops, the liquid nitrogen must be sprayed into the impact cavity (23) firstly, the internal environment temperature of the impact cavity (23) is reduced, the diameters of the pressure reducing valve (2) and the 90-degree elbow (15) are adjusted to control the volume flow rate of the liquid nitrogen, once the pipe wall is cooled, the liquid overflows to the outer surface of the pipe through the opening of the 90-degree elbow (15), is accumulated at the welding end, is separated to form liquid drops under the action of gravity, and records the pressure and the temperature of the impact cavity (23);
and fifthly, calibrating the diameter of the liquid drop by using a high-speed camera (16) and a scale (17), calculating the initial impact speed, and capturing the motion behavior and the evaporation process of the liquid drop after impacting the rigid impacted surface (18).
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| CN110530603B (en) * | 2019-07-09 | 2020-08-18 | 西安交通大学 | Low-boiling-point high-volatility medium normal-pressure environment liquid drop generation, evaporation observation and wall collision test system and method |
| CN111665170B (en) * | 2020-06-16 | 2023-02-07 | 中国石油大学(华东) | Liquid drop impact experimental device for quantitatively controlling deformation and tension of flexible substrate through ventilation |
| CN113280570B (en) * | 2021-07-13 | 2021-10-22 | 中国飞机强度研究所 | Supercooled water drop generating device |
| CN113588497B (en) * | 2021-08-02 | 2024-02-23 | 安徽工程大学 | Experimental device for be used for studying drop evolution process under impact effect |
| CN113984598B (en) * | 2021-09-30 | 2022-09-27 | 西安交通大学 | Liquid nitrogen liquid drop preparation facilities with controllable particle size |
| CN114460125B (en) * | 2022-01-21 | 2023-11-03 | 西安航空学院 | Experimental device and method for solidifying supercooled liquid drops on metal surface |
| CN114577441A (en) * | 2022-03-14 | 2022-06-03 | 北京理工大学 | Gas acceleration liquid drop impact low-temperature wall surface experimental device |
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| CN209745517U (en) * | 2019-01-16 | 2019-12-06 | 南京航空航天大学 | Low-temperature liquid drop impact rigid wall surface experimental device |
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| CN107121264A (en) * | 2017-06-20 | 2017-09-01 | 大连理工大学 | Experimental system and experimental method that a kind of controllable micron particles of humiture are collided with different surfaces |
| CN108225987A (en) * | 2017-12-27 | 2018-06-29 | 天津科技大学 | Solve the System and method for that micron order drop hits spherical surface freezing coating |
| CN209745517U (en) * | 2019-01-16 | 2019-12-06 | 南京航空航天大学 | Low-temperature liquid drop impact rigid wall surface experimental device |
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