Device and method for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions

Abstract

The present invention discloses a device and method for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions, belonging to the field of nuclear reactor thermal engineering experimental technology. The device comprises: a circular tube, the angle between the circular tube and the ground can be arbitrarily adjusted in space, and at least two groups of liquid film thickness measuring points are evenly arranged on opposite sides of the inner circumferential wall of the circular tube along the annular direction; a probe, comprising a fixed measuring wire and a movable measuring wire, the probe is used to measure the circumferential liquid film thickness of the annular flow on the inner wall of the circular tube; and a gas-liquid supply device is used to provide annular flow into the circular tube. This application accurately measures the liquid film thickness of the annular flow in the circular tube by setting multiple groups of liquid film thickness measuring points on the inner circumferential wall of the circular tube and using a probe comprising a fixed measuring wire and a movable measuring wire, thereby providing key data for studying the phase interface characteristics of the annular flow. The circular tube can arbitrarily adjust the angle between the circular tube and the ground in space to meet the experimental requirements under different inclined angles, thereby obtaining the phase interface characteristics of the annular flow in the circular tube under different inclined angles.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear reactor thermal experiments, and in particular to a device and method for analyzing the interface characteristics of annular flow in a circular tube under an inclined condition. Background Art

[0002] Annular flow is a crucial flow pattern in reactor thermal hydraulics. For a uniformly heated flow channel, the temperature of the single-phase water at the inlet gradually rises, sequentially entering subcooled boiling and saturated boiling. After saturated boiling begins, the fluid primarily experiences annular flow. As the heat flux continues to increase, the annular flow film gradually dries out, reaching critical boiling point, deteriorating heat transfer in the flow channel, and eventually burning out. In annular flow, the liquid film flows along the channel walls, while a core of gas entrained with liquid droplets flows in the center of the channel. Continuous liquid exchange occurs between the core and the film. Liquid and gas droplets in the core settle toward the film surface. Simultaneously, the high-speed flow of the core entrains the film, generating droplets that enter the core and entrain the droplets. The primary source of vapor in the core is vaporization at the vapor-liquid interface. Under vertical flow conditions, the liquid film within the channel is uniformly distributed, with symmetrical distributions of the wide and narrow edges. However, when the channel is tilted, the film distribution becomes symmetrical and uneven. Due to gravity, the liquid film tends to settle at the bottom of the flow channel, resulting in a thicker film at the bottom and thinner film at the top. This thinning of the film at the top triggers criticality prematurely, lowering the safe heat flux threshold of the flow channel. Over the past few decades, extensive research has been conducted both domestically and internationally on the interfacial properties of annular flow in vertical flow channels, providing important support for nuclear reactor safety analysis.

[0003] Floating nuclear power plants are mobile nuclear power plants built on floating platforms. They can be used for power generation, seawater desalination, and heating, meeting the specialized needs of regional power supply, regional heating, offshore oil production, chemical industry, polar regions, remote areas, and isolated islands. As floating nuclear power plants navigate the ocean, they are subject to the influence of wind and waves, causing the hull to tilt, heave, or sway. Therefore, the interfacial characteristics of annular flow in vertical channels under tilting conditions are crucial for the safety analysis of floating nuclear power plants.

[0004] In view of the above problems, there is an urgent need for a device and method for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions. Summary of the Invention

[0005] In view of this, the present application provides a device and method for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions. The main purpose is to solve the technical problems of achieving annular flow patterns in different mass flow rate ranges and accurately obtaining the phase interface distribution characteristics of annular flow under vertical and inclined conditions.

[0006] According to a first aspect of the present invention, there is provided a device for analyzing the interfacial characteristics of annular flow in a circular tube under inclined conditions, comprising: a circular tube, wherein the angle between the circular tube and the ground can be arbitrarily adjusted in space, and at least two groups of liquid film thickness measuring points are evenly arranged on opposite sides of the inner circumferential wall of the circular tube along an annular direction;

[0007] A probe, comprising a fixed measuring wire and a movable measuring wire, wherein the probe is used to measure the thickness of the liquid film in the circumferential direction of the annular flow on the inner wall of the circular tube;

[0008] The gas-liquid supply device is used to provide an annular flow into the circular tube.

[0009] Furthermore, the gas-liquid supply device includes: a water tank for providing solution into the circular tube;

[0010] An air compressor, used for providing an air source into the circular tube;

[0011] A pump is provided between the water tank and the circular pipe, and a liquid flow meter is provided downstream of the pump for regulating the flow of the liquid phase entering the circular pipe;

[0012] A flow control valve, together with the pump, regulates the flow of the liquid phase entering the circular pipe.

[0013] Furthermore, a gas flow meter and a flow control valve are provided between the air compressor and the circular pipe;

[0014] The flow pattern control valve obtains the gas phase flow required for annular flow according to the liquid phase flow, and adjusts the flow of the air compressor to a preset annular flow.

[0015] Furthermore, the analysis device further comprises: a droplet measuring device connected to the outlet end of the circular tube;

[0016] The droplet measuring device comprises at least: a liquid film collecting container and a leakage pipe;

[0017] The leakage pipe is used to introduce the annular flow coming out of the circular pipe. One end of the leakage pipe is connected to the liquid film collection container. An overflow hole is arranged on the inner wall of one end of the leakage pipe close to the circular pipe, and the liquid of the liquid film enters the liquid film collection container through the overflow hole.

[0018] Furthermore, the droplet measurement device further comprises: an air core droplet collection container, a connecting pipe;

[0019] The connecting pipe includes a first pipe and a second pipe, and a connection between the first pipe and the second pipe is provided with an angle in the vertical direction;

[0020] One end of the first pipe is connected to the outlet of the leakage pipe, and the second pipe is communicated with the gas core liquid droplet collection container.

[0021] Furthermore, the analysis device further comprises: a discharge pipe, which is connected to the connecting pipe and the gas core droplet collection container respectively;

[0022] An air-water separator is provided inside the discharge pipe for performing air-liquid separation on the air core.

[0023] Furthermore, the diameter of the leakage pipe is consistent with the diameter of the circular pipe.

[0024] Furthermore, a plurality of the probes are evenly distributed along the circumferential direction in each group of the liquid film thickness measurement points.

[0025] Furthermore, according to a second aspect of the present invention, a method for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions is provided, wherein the analysis method is implemented using the analysis device described in the above invention.

[0026] The method comprises: S1, starting an analysis device, supplying a gas-liquid two-phase fluid into a circular tube through a pump, a flow control valve, an air compressor, and a flow pattern control valve to establish an annular flow required for the experiment;

[0027] S2, adjusting the movable measuring wire until the potential difference between the movable measuring wire and the fixed measuring wire is zero, stopping the movement of the movable measuring wire, and inserting the movable measuring wire into the circular tube to transmit the depth data, i.e., the liquid film thickness data, to the terminal;

[0028] S3, sequentially acquiring the liquid film thickness data of the plurality of probes according to S2, and fitting the thickness distribution function of the circumferential liquid film of the annular flow in the circular tube according to the liquid film thickness data of the plurality of probes;

[0029] S4. Adjust the inclination angle between the circular tube and the ground, and adjust the angle between the circular tube and the ground to a new preset angle; repeat steps S1-S3 to obtain the phase interface characteristics of the annular flow in the circular tube at different inclination angles in turn, wherein the phase interface characteristics of the annular flow in the circular tube include the distribution of the circumferential liquid film thickness of the annular flow in the circular tube at different inclination angles.

[0030] Furthermore, the method further includes: S5. The method further includes: transporting the droplets in the circular tube after the test to a droplet measuring device for further gas-liquid separation, and collecting the separated liquid film and gas core droplets respectively.

[0031] The present invention provides a device and method for analyzing the interfacial properties of annular flow in a circular tube under tilted conditions. This device accurately measures interfacial properties such as liquid film thickness. By setting multiple sets of liquid film thickness measurement points on the inner circumference of the circular tube and using a probe consisting of fixed and movable measuring wires, the device can accurately measure the liquid film thickness of the annular flow in the circular tube, providing key data for in-depth research on the interfacial properties of annular flow. The circular tube can be adjusted at any angle with the ground within the tube to meet experimental requirements at different tilt angles. This allows for the analysis of the interfacial properties of the annular flow in the circular tube at different tilt angles, contributing to a comprehensive understanding of the flow patterns of the annular flow under different tilt conditions. Furthermore, the analytical device has a rational structural design, with tight coordination between its components, enabling stable and reliable operation. Furthermore, the operating process is clear, making it easy for experimenters to operate and obtain experimental data. This device accurately obtains interfacial property data of annular flow at different tilt angles, contributing to a deeper understanding of the flow characteristics of annular flow, providing a scientific basis for optimizing the design of industrial processes in fields such as oil extraction, chemical processes, and nuclear energy utilization, thereby improving the efficiency and safety of industrial processes.

[0032] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, as part of this disclosure, are intended to provide a further understanding of the disclosure. The exemplary embodiments of the disclosure and their descriptions are intended to explain the disclosure and do not constitute undue limitations thereon. Obviously, the drawings described below are merely examples, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0034] In the attached figure:

[0035] Figure 1 A schematic structural diagram of a device for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions provided by an embodiment of the present invention is shown;

[0036] Figure 2 A schematic diagram of the partial structure of a device for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions provided by an embodiment of the present invention is shown;

[0037] Figure 3 Another partial structural diagram of a device for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions provided by an embodiment of the present invention is shown;

[0038] Figure 4A flow chart of a method for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions provided by an embodiment of the present invention is shown.

[0039] Figure Number:

[0040] 1. Circular tube; 11. Probe; 2. Liquid film thickness measuring point; 3. Air compressor; 4. Water tank; 41. Pump; 5. Liquid flow meter; 6. Flow control valve; 7. Gas flow meter; 8. Flow pattern control valve; 9. Droplet measuring device; 91. Liquid film collecting container; 92. Leakage pipe; 93. Gas core droplet collecting container; 94. Connecting pipe; 941. First pipeline; 942. Second pipeline; 10. Discharge pipe; 101. Gas-water separator.

[0041] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0043] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0044] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0045] Example 1

[0046] like Figure 1-3As shown, a device for analyzing the interface characteristics of annular flow in a circular tube under inclined conditions includes: a circular tube 1, which is the core component of the entire analysis device and has the function of arbitrarily adjusting the angle with the ground in space. It can simulate the working conditions of the circular tube at different inclined angles, so as to study the influence of the inclined conditions on the interface characteristics of the annular flow. At least two groups of liquid film thickness measuring points 2 are evenly arranged on opposite sides of the inner circumferential wall of the circular tube along the annular direction. These measuring points provide basic positions for subsequent measurement of the liquid film thickness; the probe 11 includes a fixed measuring wire and a movable measuring wire. The probe 11 is used to measure the circumferential liquid film thickness of the annular flow on the inner wall of the circular tube 1. Specifically, the fixed measuring wire is fixed and the movable measuring wire can be moved. During the experiment, the fixed measuring wire and the movable measuring wire are arranged near the inner wall of the circular tube 1, and the movable measuring wire is moved step by step. The potential difference between the fixed measuring wire and the movable measuring wire is continuously measured until the potential difference between the movable measuring wire and the fixed measuring wire drops to zero, the movable measuring wire is stopped from being moved, and the insertion depth of the movable wire at this moment is read, which is the thickness of the liquid film; the gas-liquid supply equipment is used to provide annular flow into the circular tube 1.

[0047] In this embodiment, the gas-liquid supply equipment includes: a water tank 4 for providing a solution to the circular tube 1. Preferably, the solution in the water tank 4 uses a potassium chloride solution with a concentration of 1000 PPM as the liquid working fluid; an air compressor 3 for providing an air source to the circular tube 1; a pump 41 is provided between the water tank 4 and the circular tube 1. The pump is a variable frequency metering pump connected to the water tank 4 to inject the solution in the water tank 4 into the circular tube 1. Downstream of the pump 41, a liquid flow meter 5 is provided to regulate the liquid flow rate entering the circular tube 1; and a flow control valve 6 is provided to regulate the liquid flow rate entering the circular tube 1 together with the pump 41.

[0048] In one feasible embodiment, a gas flowmeter 7 and a flow pattern control valve 8 are provided between the air compressor 3 and the circular tube 1. The flow pattern control valve 8 determines the gas flow rate required for annular flow based on the liquid flow rate and adjusts the flow rate of the air compressor 3 to a preset annular flow rate. In experiments, after the liquid flow rate entering the circular tube 1 is determined, the flow pattern control valve 8 calculates the gas flow rate required for the experimental annular flow based on the liquid flow rate. Based on the gas flow rate required for the experimental annular flow, the valve automatically adjusts the flow rate to produce an annular flow that meets the experimental requirements. The liquid and gas phases mix and enter the circular tube 1.

[0049] In this embodiment, the circular tube 1 is configured to be arranged vertically or tilted relative to the ground. Specifically, the tilt angle can be adjusted to 10°, 20°, 30°, 40°, 50°, 60°, 70°, and 80°. This multi-angle adjustment capability enables comprehensive research on the effects of different tilt angles on the interfacial properties of annular flow. Preferably, three layers of liquid film thickness measurement points 2 are arranged sequentially along the inner wall of the circular tube 1 in the direction of liquid flow. Each layer of liquid film thickness measurement points 2 has eight probes 11 evenly arranged along the circumference, for real-time measurement of the circumferential liquid film thickness of the annular flow within the circular tube.

[0050] In a feasible embodiment, the analysis device also includes: a droplet measuring device 9, which is connected to the outlet end of the circular tube 1; the droplet measuring device 9 includes at least: a liquid film collecting container 91 and a leakage tube 92; the leakage tube 92, the annular flow coming out of the circular tube 1 is introduced into the leakage tube 92, one end of the leakage tube 92 is connected to the liquid film collecting container 91, and an overflow hole is arranged on the inner wall of one end of the leakage tube 92 close to the circular tube 1, and the liquid of the liquid film enters the liquid film collecting container 91 through the overflow hole.

[0051] In this embodiment, the droplet measuring device 9 also includes: an air core droplet collecting container 93, a connecting pipe 94; the connecting pipe 94 includes a first pipe 941 and a second pipe 942, and the connection between the first pipe 941 and the second pipe 942 is provided with an angle in the vertical direction; one end of the first pipe 941 is connected to the outlet of the leakage pipe 92, and the second pipe 942 is connected to the air core droplet collecting container 93.

[0052] In a feasible embodiment, the analysis device further includes: a discharge pipe 10, which is connected to the connecting pipe 94 and the gas core droplet collection container 93 respectively; a gas-water separator 101 is provided inside the discharge pipe 10 for performing gas-liquid separation on the gas core.

[0053] In this embodiment, the diameter of the leakage tube 92 is consistent with the diameter of the circular tube 1, ensuring that the annular flow coming out of the circular tube 1 can enter the leakage tube 92 smoothly and stably, reducing the impact of the change in tube diameter on the fluid flow state, so that the collected liquid film and air core droplets can more truly reflect the actual situation of the annular flow in the circular tube, thereby improving the accuracy of the experimental results.

[0054] In this embodiment, each group of the liquid film thickness measuring points 2 is evenly distributed with multiple probes 11 along the circumferential direction, which can comprehensively and accurately measure the liquid film thickness at different circumferential positions of the annular flow in the circular tube 1, reduce measurement errors, and improve the reliability of the liquid film thickness data, thereby more accurately analyzing the thickness distribution of the circumferential liquid film of the annular flow in the circular tube 1.

[0055] Example 2

[0056] like Figure 4 As described in the flowchart, a method for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions is implemented using the analysis device described in the above embodiment 1;

[0057] The method comprises: S1, starting the analysis device, supplying gas-liquid two-phase fluid into the circular tube 1 through the pump 41, the flow control valve 6, the air compressor 3 and the flow pattern control valve 8, and establishing the annular flow required for the experiment;

[0058] S2, adjusting the movable measuring wire until the potential difference between the movable measuring wire and the fixed measuring wire is zero, stopping the movement of the movable measuring wire, and inserting the movable measuring wire into the circular tube 1 to transmit the depth data, i.e., the liquid film thickness data, to the terminal;

[0059] S3, sequentially acquiring the liquid film thickness data of the plurality of probes 11 according to S2, and fitting the thickness distribution function of the circumferential liquid film of the annular flow in the circular tube 1 according to the liquid film thickness data of the plurality of probes 11;

[0060] S4. Adjust the inclination angle between the circular tube 1 and the ground, and adjust the angle between the circular tube 1 and the ground to a new preset angle; repeat steps S1-S3 to obtain the phase interface characteristics of the annular flow in the circular tube 1 at different inclination angles in turn, and the phase interface characteristics of the annular flow in the circular tube include the distribution of the circumferential liquid film thickness of the annular flow in the circular tube at different inclination angles.

[0061] In a feasible embodiment, the method further includes: S5, the method further includes: gas-liquid separation and collection: the droplets in the circular tube 1 after the test are transported to the droplet measuring device 9 for further gas-liquid separation, and the separated liquid film and gas core droplets are collected separately.

[0062] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments of equivalent changes using the above-mentioned technical contents without departing from the scope of the technical solution of the present invention. The implementation schemes in the above-mentioned embodiments can also be further combined or replaced. However, any simple modifications, equivalent changes and modifications made to the above-mentioned embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A device for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions, characterized in that: include: A circular tube (1), wherein the angle between the circular tube (1) and the ground can be arbitrarily adjusted in space, and at least two groups of liquid film thickness measuring points (2) are evenly arranged on opposite sides of the inner circumferential wall of the circular tube (1) along a circular direction; A probe (11) comprising a fixed measuring wire and a movable measuring wire, the probe (11) being used to measure the thickness of the liquid film in the circumferential direction of the annular flow on the inner wall of the circular tube (1), the fixed measuring wire and the movable measuring wire being arranged near the inner wall of the circular tube (1), the movable measuring wire being moved in a step-by-step manner, and the potential difference between the fixed measuring wire and the movable measuring wire being continuously measured until the potential difference between the movable measuring wire and the fixed measuring wire drops to zero, the movable measuring wire being stopped from being moved, and the insertion depth of the movable measuring wire at this moment being read as the thickness of the liquid film; A gas-liquid supply device for providing an annular flow into the circular tube (1); The analysis device further comprises: a droplet measuring device (9) connected to the outlet end of the circular tube (1); The liquid droplet measuring device comprises at least: a liquid film collecting container (91) and a leakage pipe (92); The leakage pipe (92) is used to guide the annular flow from the circular pipe (1) into the leakage pipe (92). One end of the leakage pipe (92) is connected to the liquid film collecting container (91). An overflow hole is provided on the inner wall of one end of the leakage pipe (92) close to the circular pipe (1). The liquid of the liquid film enters the liquid film collecting container (91) through the overflow hole. The droplet measuring device further comprises: an air core droplet collecting container (93), a connecting pipe (94); The connecting pipe (94) comprises a first pipe (941) and a second pipe (942), and an angle is provided at the connection between the first pipe (941) and the second pipe (942) in the vertical direction; One end of the first pipe (941) is connected to the outlet of the leakage pipe (92), and the second pipe (942) is connected to the gas core droplet collection container (93); The analysis device further comprises: a discharge pipe (10), which is respectively connected to the connecting pipe (94) and the gas core droplet collection container (93); A gas-water separator (101) is provided inside the discharge pipe (10) for performing gas-liquid separation on the gas core.

2. The device for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions according to claim 1 is characterized in that: The gas-liquid supply device comprises: a water tank (4) for providing solution into the circular tube (1); An air compressor (3) for providing an air source into the circular tube (1); A pump (41) is provided between the water tank (4) and the circular pipe (1), and downstream of the pump (41) is provided a liquid flow meter (5) for regulating the flow of the liquid phase entering the circular pipe (1); The flow control valve (6) and the pump (41) jointly regulate the flow of the liquid phase entering the circular pipe (1).

3. The device for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions according to claim 2, characterized in that: A gas flow meter (7) and a flow type control valve (8) are provided between the air compressor (3) and the circular pipe (1); The flow pattern control valve (8) obtains the gas phase flow required for annular flow according to the liquid phase flow, and adjusts the flow of the air compressor (3) to a preset annular flow.

4. The device for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions according to claim 1, characterized in that: The diameter of the leakage pipe (92) is consistent with the diameter of the circular pipe (1).

5. The device for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions according to claim 1, characterized in that: Each group of liquid film thickness measurement points (2) has a plurality of probes (11) evenly distributed along the circumferential direction.

6. A method for analyzing the phase interface characteristics of annular flow in a circular tube under inclined conditions, characterized in that: The analysis method is implemented using the analysis device as described in any one of claims 1 to 5 above; The method comprises: S1, starting the analysis device, supplying gas-liquid two-phase fluid into the circular tube (1) through the pump (41), the flow control valve (6), the air compressor (3) and the flow pattern control valve (8), and establishing the annular flow required for the experiment; S2, adjusting the movable measuring wire until the potential difference between the movable measuring wire and the fixed measuring wire is zero, stopping the movement of the movable measuring wire, and inserting the movable measuring wire into the circular tube (1) to transmit the depth data, i.e., the liquid film thickness data, to the terminal; S3, sequentially acquiring the liquid film thickness data of the plurality of probes (11) according to S2, and fitting the thickness distribution function of the circumferential liquid film of the annular flow in the circular tube (1) according to the liquid film thickness data of the plurality of probes (11); S4, adjusting the inclination angle between the circular tube (1) and the ground, and adjusting the angle between the circular tube (1) and the ground to a new preset angle; repeating steps S1-S3, and sequentially obtaining the phase interface characteristics of the annular flow in the circular tube (1) at different inclination angles, wherein the phase interface characteristics of the annular flow in the circular tube include the distribution of the circumferential liquid film thickness of the annular flow in the circular tube at different inclination angles.

7. The method for analyzing phase interface characteristics of annular flow in a circular tube under inclined conditions according to claim 6, characterized in that: The method further comprises: S5, transporting the droplets in the circular tube (1) after the test to a droplet measuring device for further gas-liquid separation, and collecting the separated liquid film and gas core droplets respectively.

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