A visual experimental device and method for simulating two-phase flow pool entrainment phenomenon

Abstract

The application provides a visual experiment device and method for simulating two-phase flow pool entrainment phenomenon, and belongs to the technical field of two-phase flow experiment devices, and comprises a body, a bypass pipe, the bypass pipe being communicated with the body, the body being installed on a base, an aerator being installed in the base, a top cover being installed on the upper part of the body, two visual shooting windows being symmetrically arranged on the body and being located at the same horizontal height, and a liquid level meter being installed on the top cover and the top part of the bypass pipe respectively. The application is convenient for directly observing the bubble movement, breaking and droplet splashing process; the bypass pipe is arranged and the liquid level meter is arranged in the bypass pipe, the liquid level fluctuation in the bypass pipe is monitored, and then the system pressure fluctuation is calculated; meanwhile, the liquid level meter is arranged in the body, the dynamic change of the liquid level of the two-phase mixture is captured, the visual shooting window is provided, a passage for optical measurement is provided, the accurate capture of the entrainment droplet particle size information is realized, and stable and multifunctional experimental support is provided for the mechanism research of the pool entrainment phenomenon and the safety evaluation of the airborne radioactivity of nuclear facilities.

Description

Technical Field

[0001] This invention belongs to the technical field of two-phase flow experimental devices, specifically relating to a visualization experimental device and method for simulating pool-type entrainment phenomena in two-phase flow. Background Technology

[0002] Pool entrainment, a classic physical phenomenon in chemical engineering, refers to the process by which boiling or rising gas flows break up liquid in a pool into fine droplets and continuously entrain them into the gas phase. In nuclear energy systems engineering, this phenomenon is widely observed in boiling water reactor cores, pressurized water reactor steam generators, spent fuel pools, and liquid waste systems where continuous boiling or gas-liquid two-phase flow exists. It is one of the key mechanisms leading to the migration of radioactive droplets with the gas phase and the formation of gaseous radioactive release.

[0003] Currently, various experimental research methods and related devices have been developed for pool entrainment phenomena, but certain limitations still exist. Some devices can only obtain the total mass of entrained liquid by collecting and weighing it, failing to reveal the dynamic details of bubble bursting and droplet formation. Other devices, while equipped with observation windows to visualize flow at some experimental locations, cannot simultaneously monitor key parameters such as pressure and liquid level in real time. Some experimental systems focus on measuring aerosol deposition efficiency, are structurally complex, and cannot statistically analyze the particle size of entrained droplets. Furthermore, some simulation devices designed for specific engineering structures lack versatility and flexibility in adjusting operating parameters due to their specific scenarios. These devices all focus on a single aspect of measurement or simulation, with relatively limited functions, failing to form a comprehensive experimental platform integrating dynamic process observation, simultaneous acquisition of multiple physical quantities, and analysis of droplet microstructures, thus hindering a systematic understanding of the entire pool entrainment process.

[0004] In conducting systematic experimental studies on pool-type entrainment behavior, to accurately reveal its occurrence mechanism, quantify the entrainment fraction, and assess the risk of radioactive release, it is essential to obtain detailed data on the entire process of droplet generation and entrainment, including multi-parameter information such as bubble motion behavior, droplet size distribution, and pressure and level fluctuations. Therefore, developing an integrated experimental device that combines visualization, simultaneous multi-parameter measurement, and online particle size analysis capabilities is of significant engineering importance for deepening mechanistic research and supporting safety assessments. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical problems and provide a visual experimental device for simulating the entrainment phenomenon in a two-phase flow pool.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A visualization experimental device for simulating the entrainment phenomenon in a two-phase flow pool includes: a main body and a bypass pipe connected to the main body. The main body is mounted on a base, and an aerator is installed inside the base. A top cover is installed on the upper part of the main body. Two visualization shooting windows located at the same horizontal level are symmetrically opened on the main body. Liquid level gauges are respectively installed on the top cover and the top of the bypass pipe.

[0008] Furthermore, the base includes a bottom support structure, a surrounding plate structure is installed between the bottom support structure and the flange, the flange is connected to the body, an air inlet pipe and a water inlet pipe are installed on the surrounding plate structure, and a side support structure is installed between the bottom support structure and the surrounding plate structure.

[0009] Furthermore, the air inlet of the air intake pipe is connected to an external air compressor and flow controller.

[0010] Furthermore, the aerator includes an aerator inlet pipe, which is connected to an inlet pipe and a distribution pipe, respectively. The distribution pipe is connected to an outer aeration ring and an inner aeration ring via a connecting pipe. The upper surfaces of the outer aeration ring and the inner aeration ring each have multiple aeration holes.

[0011] Furthermore, the outer aeration ring and the inner aeration ring are concentric structures.

[0012] Furthermore, the top cover includes a circular cover structure, which has an exhaust port and a flange support structure, and the flange support structure is connected to the level gauge.

[0013] Furthermore, the body has a highly transparent cylindrical shape.

[0014] Furthermore, the top of the bypass pipe is at the same height as the top cover.

[0015] Furthermore, the bypass pipe is connected to the main body through two connecting pipes arranged vertically.

[0016] The present invention may also include:

[0017] A visualization experimental method for simulating the entrainment phenomenon in a two-phase flow pool, characterized by using the experimental apparatus described in any one of claims 1-9, the method comprising the following steps:

[0018] First, close all drain valves and inject the experimental liquid into the body through the water inlet pipe of the base until the liquid level reaches the preset height, and confirm it through two liquid level gauges.

[0019] Then, the air compressor is started. After the gas is regulated by the flow controller, it enters the aerator through the air inlet pipe of the base. The gas is sprayed out from the aeration holes of the aerator, forming a large number of fine bubbles and entering the liquid. The bubble group rises under the action of buoyancy, violently agitating the liquid and forming a gas-liquid two-phase mixing entrainment zone. After the gas-liquid two-phase flow carrying the bubbles rises to the top, the gas is discharged from the exhaust port of the top cover, while the liquid remains in the body.

[0020] The entire dynamic process is recorded through visualization shooting windows on both sides. High-speed cameras are used to record the movement, aggregation and rupture behavior of bubbles, or laser particle size analyzers are used to measure the size distribution of bubble groups, thereby enabling quantitative and visual research on pool entrainment phenomena.

[0021] The beneficial effects of this invention are as follows:

[0022] The main body of this invention features a transparent structure, clearly displaying the trajectory of bubbles and their rupture at the liquid surface, causing droplet splashing. An external imaging device can be installed for analysis. A level gauge mounted on the top cover captures liquid level fluctuations during the experiment, and the entrainment volume can be indirectly obtained by measuring the liquid level. Furthermore, a bypass pipe is included, and a level gauge placed within the bypass pipe can measure liquid level fluctuations, allowing for calculation of the pressure fluctuations in the two-phase mixture.

[0023] The present invention has a visual imaging window on its main body, which can measure the droplet size and obtain key experimental parameters.

[0024] The experimental device of this invention has a simple structure. The size of the acrylic experimental body and the structure of the aerator can be determined according to specific experimental conditions. It is easy to disassemble and replace, improving experimental efficiency and providing stable, reliable and multifunctional experimental support for the study of the mechanism of pool entrainment phenomenon and the airborne radioactivity safety assessment of nuclear facilities. Attached Figure Description

[0025] Appendix Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Appendix Figure 2 This is the front view of the present invention;

[0027] Appendix Figure 3 This is a schematic diagram of the aerator of the present invention;

[0028] Appendix Figure 4 This is a front view of the aerator of the present invention;

[0029] Appendix Figure 5 This is a schematic diagram of the structure of the base of the present invention;

[0030] Appendix Figure 6 This is a schematic diagram of the top cover of the present invention;

[0031] Appendix Figure 7 This is a schematic diagram of the structure of the visualization shooting window of the present invention.

[0032] In the attached diagram: 1. Top cover, 2. Body, 3. Base, 301. Bottom support structure, 302. Air inlet pipe, 303. Flange, 304. Water inlet pipe, 305. Side support structure, 306. Enclosure structure, 4. Level gauge, 5. Bypass pipe, 6. Visual imaging window, 7. Aerator, 701. Outer aeration ring, 702. Inner aeration ring, 703. Aeration hole, 704. Air distribution pipe, 705. Connecting pipe, 706. Aerator air inlet pipe. Detailed Implementation

[0033] The present invention will now be further described with reference to the accompanying drawings.

[0034] This invention provides a visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool, as shown in the attached diagram. Figure 1-2 As shown, the system includes: a top cover 1, an acrylic transparent body 2, a base 3, level gauges 4, a bypass pipe 5, a viewing window 6, and an aerator 7. The diameter of the top cover 1 matches the diameter of the body 2 and can be nested on top of the body 2. Two level gauges 4 are located above the top cover 1 and above the bypass pipe 5, respectively, and are tightly connected to them to prevent the level gauges 4 from shaking and causing measurement errors. The two viewing windows 6 are at the same height on the body 2 and are on the same straight line, and can be nested on the rectangular support platform reserved in the body 2. The aerator 7 is connected to the air inlet pipe 302 inside the base 3.

[0035] Appendix Figure 2 Connections 801, 802, 803, and 804 shown can be flange connections, requiring tight connections and no gas or liquid leakage. Inside the body 2, gas is ejected from the aerator 7, passes through the liquid inside the body 2 and is turbidized, and finally escapes from the top cover 1 and is directly discharged into the atmosphere.

[0036] The main body 2 is a cylindrical tube with high transparency, preferably made of transparent acrylic material. The upper and lower end faces are precision machined to ensure flatness, and its diameter and height are determined according to the scale of the experimental simulation.

[0037] The lower end of the main body 2 is tightly connected to the base 3 via a set of mating flanges, while the upper end is fitted to the top cover 1 via a sleeve or other means. The total height of the bypass pipe (5) is the same as the total height of the main body (2) plus the base (3). Its lower end is connected to the vicinity of the bottom of the main body via a pipeline, and its upper end is connected to the gas space, thus forming a communicating vessel. At an appropriate position on the top cover, a special flange support structure is installed for installing a high-precision liquid level gauge 4. This liquid level gauge is used to directly monitor the change in liquid level in the main body chamber. A liquid level gauge 4 is also installed on the upper part of the bypass pipe to read the height of the liquid level equilibrium in the bypass pipe 5, and the pressure fluctuation of the two-phase mixture is calculated.

[0038] As attached Figure 3-4 As shown, the aerator 7 comprises: an outer aeration ring 701, an inner aeration ring 702, a distribution pipe 704, an aerator inlet pipe 706, and connecting pipes 705. The entire aerator 7 is made of stainless steel or other materials with strong pressure resistance and can be made of tubing. The shape and size of the outer aeration ring 701 and the inner aeration ring 702 can be designed according to experimental requirements, and the size and shape of the aeration holes 703 can also be determined according to the desired bubble size. Two connecting pipes 705 are used to connect the outer aeration ring 701 and the distribution pipe 704, and the other two are used to connect the inner aeration ring 702 and the distribution pipe 704.

[0039] Furthermore, the aerator 7 is preferably constructed from bent and welded stainless steel tubing, requiring excellent pressure resistance and corrosion resistance. The gas distribution pipe 704 serves as a central gas distribution hub, connected to the inlet pipe 302 from the base via a vertical aerator inlet pipe 706. Four connecting pipes 705 extend from the distribution pipe 704, two connecting to a larger-diameter outer aeration ring 701, and the other two connecting to a concentric, smaller-diameter inner aeration ring 702, forming a double-ring gas distribution structure. This design aims to achieve a more uniform gas distribution across the bottom cross-section of the reactor. Numerous tiny aeration holes 703 are drilled at equal intervals along the circumference on the upper surfaces of the outer and inner aeration rings 701 and 702. The hole diameter can be precisely selected according to the target bubble size, which is a core parameter for controlling the initial bubble generation size. The aerator 7 is fixed inside the base 3 by welding or other tight connections, ensuring its top surface is horizontal so that all aeration holes 703 produce gas evenly upwards.

[0040] As attached Figure 5As shown, the base 3 includes: a bottom support structure 301, an air inlet pipe 302, a flange 303 connected to the body 2, a water inlet pipe 304, a side support structure 305, and a surrounding plate structure 306. The base 3 is made entirely of stainless steel or other materials with good corrosion resistance, and can be made of pipes and stainless steel plates. The flange 303 is matched to the flange size of the acrylic transparent body 2 to ensure a seal. The air inlet pipe 302 has an air inlet at end C and an air outlet at end D, which inputs gas into the aerator inlet pipe 706 of the aerator 7. End C is connected to the gas phase source. End E of the water inlet pipe 304 is connected to the liquid phase source, and end F is the water inlet, which directly delivers the liquid phase into the body 2.

[0041] Furthermore, the base is constructed entirely of stainless steel profiles and plates, possessing excellent structural strength and corrosion resistance. A vertical side support structure 305 and a surrounding plate structure 306 are provided on the side, forming a stable box-like structure. The core component located at the top of the base 3 is a stainless steel flange 303 precisely matched with the lower flange of the acrylic body, secured and sealed by evenly distributed bolts. Near the center of the flange, a water inlet pipe 304 is provided, its inlet end E connected to an external water pump or high-level liquid tank via a quick-connect fitting or other connection method, and connected in series with a liquid flow control valve and flow meter to precisely adjust and record the liquid flow rate and total volume injected into the body. An air inlet pipe 302 is installed on the side or rear of the base 3, with the air inlet C connected to an external air compressor and gas mass flow controller. Gas is transported via the air inlet pipe (302) to the aerator inlet pipe 706 located in the central area D inside the base.

[0042] As attached Figure 6 As shown, the top cover 1 includes: a flange support structure 101 for connecting to the level gauge, a vent 102, and a round cover structure 103. The flange support structure 101 for connecting to the level gauge can be determined according to the specific shape of the level gauge. The size of the vent 102 can be varied according to specific experimental requirements. The round cover structure 103 matches the size of the body 2, while ensuring that the round cover structure 103 can seal with the body 2.

[0043] The top cover 1 is a circular cover structure 103 that matches the inner diameter of the body 2, allowing it to fit tightly onto the upper end of the body 2, and is sealed with a sealing ring. A vent 102 is located at the center of the top cover 1. The diameter of the vent 102 can be designed according to the expected maximum gas flow rate to ensure that gas rising to the liquid surface can be smoothly discharged into the atmosphere, avoiding pressure buildup at the top. A dedicated flange support structure 101 is welded or assembled at an appropriate location on the top cover 1 for installing a high-precision level gauge. This level gauge is used to directly monitor changes in the liquid level within the body chamber.

[0044] As attached Figure 7As shown, side A of the visualization window 6 is the exterior, and side B is the interior. Side B matches the rectangular support platform pre-installed on the acrylic transparent body 2. An optical-grade quartz glass plate is embedded in the visualization window 6 to meet the optical path requirements of the particle size analyzer and enable visual observation of entrainment phenomena. This quartz glass plate has extremely high light transmittance and excellent optical uniformity, meeting the high requirements of precision optical measurement equipment such as laser particle size analyzers, high-speed cameras, or PIV systems for optical paths. During installation, side B (inner side) of the window assembly must be flush with the support platform of the body opening to ensure that the window is flush with or smoothly transitions to the body wall, thus avoiding interference with the flow field or optical path.

[0045] This embodiment also provides a visualization experimental method for simulating the entrainment phenomenon in a two-phase flow pool. In the specific implementation of the experiment, firstly, all drain valves are closed, and experimental liquid (such as water or a specific solution) is injected into the main body 2 through the water inlet pipe 302 of the base 3 until the liquid level reaches a preset height, which is confirmed by two level gauges 4. Then, the gas source is activated, and the gas, after being regulated by the flow controller, enters the aerator 7 through the air inlet pipe 302 of the base. The gas is ejected from the inner and outer ring aeration holes 703 of the aerator 7, forming a large number of fine bubbles that enter the liquid. The bubble group rises under the action of buoyancy, violently agitating the liquid and forming an entrainment zone of gas-liquid two-phase mixing. The operator can change the intensity of the entrainment by adjusting the gas flow rate. After the gas-liquid two-phase flow carrying the bubbles rises to the top, the gas is discharged from the exhaust port 102 of the top cover 1, while the liquid remains in the main body 2.

[0046] The entire dynamic process can be recorded via visualization windows 6 on both sides, using a high-speed camera to record the movement, aggregation, and collapse of bubbles, or using a laser particle size analyzer to measure the size distribution of the bubble swarm, thus enabling quantitative and visual research on pool-type entrainment phenomena. All connections of the apparatus, especially the flange connections numbered 801 to 804, must be tightened with appropriate force and sealed with suitable sealing materials to ensure no gas or liquid leakage throughout the entire experimental pressure range, guaranteeing experimental safety and data accuracy.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A visual experimental apparatus for simulating entrainment phenomena in a two-phase flow pool, characterized in that, include: The main body (2) and the bypass pipe (5) are connected to the main body (2). The main body (2) is installed on the base (3). An aerator (7) is installed inside the base (3). A top cover (1) is installed on the upper part of the main body (2). Two visual shooting windows (6) located at the same horizontal height are symmetrically opened on the main body (2). A level gauge (4) is installed on the top of the top cover (1) and the bypass pipe (5).

2. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 1, characterized in that, The base (3) includes a bottom support structure (301), a surrounding plate structure (306) is installed between the bottom support structure (301) and the flange (303), the flange (303) is connected to the body (2), an air inlet pipe (302) and a water inlet pipe (304) are installed on the surrounding plate structure (306), and a side support structure (305) is installed between the bottom support structure (301) and the surrounding plate structure (306).

3. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 2, characterized in that, The air inlet of the air inlet pipe (302) is connected to an external air compressor and flow controller.

4. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 1, characterized in that, The aerator (7) includes an aerator inlet pipe (706), which is connected to an inlet pipe (302) and a distribution pipe (704) respectively. The distribution pipe (704) is connected to an outer aeration ring (701) and an inner aeration ring (702) respectively through a connecting pipe (705). The upper surfaces of the outer aeration ring (701) and the inner aeration ring (702) each have multiple aeration holes (703).

5. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 4, characterized in that, The outer aeration ring (701) and the inner aeration ring (702) are concentric structures.

6. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 1, characterized in that, The top cover (1) includes a round cover structure (103), which has an exhaust port (102) and a flange support structure (101) connected to a level gauge.

7. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 1, characterized in that, The body (2) has a highly transparent cylindrical tube.

8. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 1, characterized in that, The top of the bypass pipe (5) is at the same height as the top cover (1).

9. The visualization experimental apparatus for simulating the entrainment phenomenon in a two-phase flow pool according to claim 1, characterized in that, The bypass pipe (5) is connected to the main body (2) through two connecting pipes arranged vertically.

10. A visualization experimental method for simulating the entrainment phenomenon in a two-phase flow pool, characterized in that it uses the experimental apparatus described in any one of claims 1-9, and the method comprises the following steps: First, close all drain valves and inject experimental liquid into the body (2) through the water inlet pipe (304) of the base (3) until the liquid level reaches the preset height, and confirm it through two liquid level gauges (4); Then, the air compressor is started. After the gas is regulated by the flow controller, it enters the aerator (7) through the air inlet pipe (302) of the base (3). The gas is sprayed out from the aeration hole (703) of the aerator (7), forming a large number of tiny bubbles and entering the liquid. The bubble group rises under the action of buoyancy, violently agitating the liquid and forming a gas-liquid two-phase mixing zone. After the gas-liquid two-phase flow carrying the bubbles rises to the top, the gas is discharged from the exhaust port (102) of the top cover (1), while the liquid remains in the body (2). The entire dynamic process is recorded by using a high-speed camera through the visualization shooting windows on both sides (6), which records the movement, aggregation and rupture behavior of bubbles, or by using a laser particle size analyzer to measure the size distribution of the bubble group, thereby realizing a quantitative and visual study of the pool entrainment phenomenon.

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