System and method for measuring void fraction of rod bundle section

Abstract

The invention discloses a system and a method for measuring the void fraction of a rod bundle section. The device comprises a pipe body, a rod bundle assembly, a two-phase flow device, a first detection part, a second detection part and a camera shooting part, and the rod bundle assembly is arranged in the pipe body; the two-phase flow device is used for preparing a gas-liquid two-phase flow substance and conveying the gas-liquid two-phase flow substance into the first cavity; the first detection component is used for detecting the pressure at a plurality of pressure measuring point positions in the first cavity and the pressure difference between at least part of the pressure measuring point positions; the second detection part is used for identifying the section void fraction of the first cavity section corresponding to the second detection part; the camera shooting component is used for shooting gas-liquid two-phase flow substances in a partial section in the first cavity. According to the invention, the flow characteristic of the steam-water flowing through the reactor core can be simulated, and parameters are obtained through a plurality of detection means, so that important support is provided for research of two-phase flow manifold, calculation of section gas content and qualitative evaluation of friction pressure drop, and void fraction measurement of two-phase flow.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power technology, specifically relating to a system and method for measuring the cavitation fraction of rod bundle cross sections. Background Technology

[0002] Large-break accidents are the design baseline accidents for nuclear power plants and one of the key accidents that nuclear power plant safety analysis software needs to analyze. To fully exploit the safety margins in nuclear power plant design, related technologies commonly employ optimal estimation plus uncertainty analysis for large-break accident safety analysis. This method requires extensive testing at each stage of the large-break accident to assess and quantify uncertainty. However, while some experimental data can be obtained through collaboration, some crucial data remains unavailable, hindering the validation and widespread adoption of nuclear power plant safety analysis software. Summary of the Invention

[0003] This invention is based on the inventor's discoveries and understanding of the following facts and problems:

[0004] The inventors recognized that during a large breach accident, the core fluid rapidly transitions to a two-phase state due to factors such as coolant reduction, decreased flow velocity, and system pressure drop. Analysis of the two-phase flow and heat transfer phenomena in typical pressurized water reactor cores, along with precise measurement of relevant parameters, is crucial for obtaining data for the verification and widespread application of nuclear power plant design safety analysis software.

[0005] The inventors also recognized that in the experimental apparatus for two-phase flow in the related technology, the gas-liquid flow direction in the test section is from bottom to top, and the cross-sectional cavitation fraction is mainly measured by differential pressure. However, when the two-phase flow is from top to bottom in the test section, due to the lack of understanding of the flow pattern, there is a lack of effective support when using the differential pressure method to calculate the cavitation fraction.

[0006] The present invention aims to at least partially solve one of the technical problems in the related art.

[0007] Therefore, embodiments of the present invention propose a system for measuring the cavitation fraction of a rod bundle cross section, which can be used for the simulation and study of two-phase flow patterns.

[0008] A system for measuring the cavitation fraction of a rod bundle cross section according to an embodiment of the present invention includes:

[0009] A tube body having a first cavity and extending along a first direction;

[0010] A rod bundle assembly, wherein the rod bundle assembly is disposed within the first cavity;

[0011] A two-phase flow device, wherein the outlet end of the two-phase flow device is connected to the first cavity, and the two-phase flow device is used to configure gas-liquid two-phase flow substances and transport them into the first cavity;

[0012] A first detection component is connected to the tube body and is used to detect the pressure at multiple pressure measurement points in the first cavity and the pressure difference between at least some of the pressure measurement points.

[0013] A second detection component is connected to the tube body and is used to identify the cross-sectional cavitation fraction at the first cavity cross-section corresponding to the second detection component.

[0014] A camera component is used to capture images of a portion of the gas-liquid two-phase flow material in the first cavity to obtain the two-phase flow profile.

[0015] The cylinder fraction measurement system for rod bundle cross sections of this invention can simulate the flow characteristics of steam and water flowing through the reactor core and obtain parameters through various detection methods. This provides important support for the study of two-phase flow patterns, calculation of cross-sectional gas content, and qualitative evaluation of frictional pressure drop, and is crucial for measuring the cylinder fraction of two-phase flow.

[0016] In some embodiments, the rod bundle assembly includes a positioning grid and a plurality of rod bundles arranged in parallel and spaced apart, the rod bundles extending along a first direction, and the rod bundles being connected to the tube body via the positioning grid.

[0017] In some embodiments, each of the positioning grids is provided with pressure measuring points on both sides in the first direction;

[0018] And / or, the cross-section of the first cavity is square, and the plurality of the rod bundles are arranged in an N*N rectangular array;

[0019] And / or, the second detection component is arranged in the middle or lower middle part of the first cavity;

[0020] And / or, the tube is transparent.

[0021] In some embodiments, the first detection component is a differential pressure sensor, which has multiple measuring points arranged along a first direction within the first cavity to detect the pressure at the inlet end of the first cavity and the pressure difference between adjacent measuring points.

[0022] And / or, the second detection component is a linear array sensor;

[0023] And / or, the imaging component includes a light source and a camera, the light source and the camera being disposed opposite to each other.

[0024] In some embodiments, the first direction is a vertical direction, the upper part of the tube is provided with a first inlet, and the lower part of the tube is provided with a first outlet.

[0025] In some embodiments, the two-phase flow device includes:

[0026] A mixer, the outlet end of which is connected to the inlet end of the tube, is used for mixing gas-liquid two-phase substances;

[0027] A gas supply assembly, connected to the mixer, is used to supply gas into the mixer;

[0028] A liquid supply assembly is connected to the mixer and is used to supply liquid into the mixer.

[0029] In some embodiments, the air supply assembly includes an air compressor, an air delivery pipe, and a first regulating component disposed on the air delivery pipe;

[0030] The liquid supply assembly includes a water tank, a water supply pipe, a first pump and a second regulating component installed on the water supply pipe, and a return water pipe is provided between the outlet end of the pipe and the water tank.

[0031] In some embodiments, the first regulating component includes a pressure reducing valve, a gas flow meter, a gas flow regulating valve, and a first thermometer arranged on the gas pipeline, wherein the gas flow meter and the gas flow regulating valve are a set or multiple sets arranged in parallel on the gas pipeline.

[0032] And / or, the second regulating component includes a first valve, a liquid flow meter, a liquid flow regulating valve and a second thermometer arranged on the water supply pipeline, wherein the liquid flow meter and the liquid flow regulating valve are a set or multiple sets are arranged in parallel on the water supply pipeline;

[0033] And / or, it also includes a check valve, said check valve being disposed on the water supply pipeline;

[0034] And / or, it also includes a branch pipe, which is located between the outlet end of the first pump and the water tank, and the branch pipe is equipped with a second valve;

[0035] And / or, the water tank is provided with a baffle to divide the inner cavity of the water tank into two water chambers, the upper parts of the two water chambers are connected, the water tank is provided with an exhaust port, a water inlet and a feeding port, and the bottom of the water tank is provided with a drain port.

[0036] In some embodiments, a data acquisition and processing system is further included, which is connected to the two-phase flow device, the first detection component, the second detection component, and the camera component to acquire and process the acquired data.

[0037] The method for measuring the cavitation fraction of a rod bundle cross section disclosed in this invention includes the following steps:

[0038] The above-described embodiment of the system for measuring the cavitation fraction of a rod bundle cross section is arranged such that the tube extends vertically and the gas-liquid two-phase flow material in the first cavity flows from top to bottom;

[0039] Configure the operating parameters of the two-phase flow device and start its operation;

[0040] Based on the formula Δp=Δp fu +Δp a +Δp g and Δp g =-ρ m gh=-[ρ g α+(1-α)ρ l ]gh, where Δp is the total pressure drop in the pipeline, Δp fu Δp is the frictional pressure drop during the vertical descent segment. a To accelerate the pressure drop, and Δp a =0, Δp g For the pressure drop due to gravity, ρ g ρ is the gas phase density. l ρ is the density of the liquid phase. m Given the average density of the two-phase flow and α as the cross-sectional void fraction, we can know that:

[0041]

[0042] Based on the detection data from the first detection component, the total pressure drop Δp in the pipeline is obtained;

[0043] Based on the imaging component, the two-phase flow pattern is identified, and the frictional pressure drop Δp in the vertical descent section is obtained by combining the first empirical formula. fu ; and / or, adjust the extension direction of the tube to a second direction, which is orthogonal to the first direction, collect detection data under this working condition, and obtain the frictional pressure drop Δp in the vertical descent section. fu To verify the first empirical relation;

[0044] Obtain the cross-sectional cavitation fraction α and compare it with the cross-sectional cavitation fraction identified by the second detection component. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of the rod bundle cross-section cavitation fraction measurement system according to an embodiment of the present invention.

[0046] Figure label:

[0047] 1. Pipe body;

[0048] 2. Rod bundle assembly; 21. Positioning grid; 22. Rod bundle;

[0049] 3. First detection component;

[0050] 4. Second detection component;

[0051] 5. Camera components; 51. Camera; 52. Light source;

[0052] 6. Data acquisition and processing system;

[0053] 7. Gas supply components; 71. Air compressor; 72. Gas pipeline; 73. Pressure reducing valve; 74. Gas flow meter; 75. Gas flow regulating valve; 76. First thermometer;

[0054] 8. Liquid supply assembly; 81. Water tank; 811. Baffle; 812. Vent; 813. Inlet; 814. Feeding port; 815. Drain; 82. Water supply pipeline; 83. First pump; 84. First valve; 85. Liquid flow meter; 86. Liquid flow regulating valve; 87. Second thermometer; 88. Branch pipeline; 89. Second valve; 90. Check valve; 91. Return water pipeline; 92. Third valve;

[0055] 9. Mixer. Detailed Implementation

[0056] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0057] like Figure 1 As shown, the rod bundle cross-section cavitation fraction measurement system according to an embodiment of the present invention includes a tube body 1 and a rod bundle assembly 2. The tube body 1 has a first cavity and extends along a first direction. The rod bundle assembly 2 is disposed in the first cavity, thereby constructing a test section for simulating the flow characteristics of steam and water flowing through the reactor core.

[0058] The system for measuring the cross-sectional void fraction of rod bundles also includes a two-phase flow device, a first detection component 3, a second detection component 4, and a camera component 5. The outlet end of the two-phase flow device is connected to the first cavity, and the two-phase flow device is used to configure the gas-liquid two-phase flow material and transport it into the first cavity. The first detection component 3 is connected to the tube body 1, and the first detection component 3 is used to detect the pressure at multiple pressure measurement points in the first cavity and the pressure difference between at least some of the pressure measurement points. The second detection component 4 is connected to the tube body 1, and the second detection component 4 is used to identify the cross-sectional void fraction at the first cavity cross-section corresponding to the second detection component 4. The camera component 5 is used to photograph the gas-liquid two-phase flow material in a portion of the first cavity to obtain the two-phase flow profile.

[0059] The two-phase flow device forms a gas-liquid two-phase flow by mixing gas and liquid and delivers it into the first chamber. During the flow of the gas-liquid two-phase flow through the first chamber, data is collected by the first detection component 3, the second detection component 4 and the camera component 5, thereby obtaining the flow characteristics of the two-phase flow, studying the flow pattern of the two-phase flow, calculating the cross-sectional gas content and qualitatively evaluating the friction pressure drop.

[0060] In this embodiment of the invention, the first detection component 3 is used to monitor the pressure at multiple pressure measurement points and obtain the pressure difference between adjacent pressure measurement points. The second detection component 4 can identify the cross-sectional cavitation fraction at its corresponding position in real time. The camera component 5 can perform real-time imaging of the gas-liquid two-phase flow material, more intuitively identify the two-phase flow pattern, and then calculate the cross-sectional cavitation fraction based on the measured pressure difference data. The cross-sectional cavitation fraction data is compared with the cross-sectional cavitation fraction data detected by the second detection component 4 to verify the validity of the pressure difference measurement results. This provides effective support for the measurement and data analysis of the cross-sectional cavitation fraction of the rod bundle 22 under high temperature and high pressure conditions.

[0061] The cylinder fraction measurement system for rod bundle cross sections of this invention can simulate the flow characteristics of steam and water flowing through the reactor core and obtain parameters through various detection methods. This provides important support for the study of two-phase flow patterns, calculation of cross-sectional gas content, and qualitative evaluation of frictional pressure drop, and is crucial for measuring the cylinder fraction of two-phase flow.

[0062] In some embodiments, the first direction is vertical, the upper part of the tube body 1 is provided with a first inlet, and the lower part of the tube body 1 is provided with a first outlet.

[0063] It should be understood that the gas-liquid two-phase flow material flows into the first cavity from the upper part of the pipe body 1 and flows out of the first cavity from the lower part of the pipe body 1, thus forming a top-down flow design. The embodiment of the present invention can overcome the buoyancy force and successfully complete the simulation test, and can simulate the entire flow pattern of the gas-liquid two-phase flow downward. Relevant data are obtained through the first detection component 3, the second detection component 4 and the camera component 5 respectively, which makes it more practical.

[0064] In some embodiments, the rod bundle assembly 2 includes a positioning grid 21 and a plurality of rod bundles 22, the plurality of rod bundles 22 being arranged in parallel and spaced apart, the rod bundles 22 extending along a first direction, and the rod bundles 22 being connected to the tube body 1 through the positioning grid 21.

[0065] It should be understood that the rod bundle 22 is fixed in the first cavity of the tube body 1 by the positioning grid 21, and the rod bundle 22 is spaced apart from each other. The positioning grid 21 adopts the prototype grid, and the rod bundle 22 adopts the rod body with the same size as the prototype.

[0066] For example, the rod bundle 22 uses solid stainless steel rods of the same size as the prototype to simulate the rod bundle 22 in the reactor core.

[0067] Optionally, the tube body 1 is transparent, which facilitates the observation and photography of the gas-liquid two-phase flow pattern in the first cavity.

[0068] Furthermore, the cross-section of the first cavity is square, and the multiple rod bundles 22 are arranged in an N*N rectangular array;

[0069] For example, tube 1 is made of transparent acrylic material, with a wall thickness of 20mm. The cross-section of the first cavity is a 50mm*50mm square. Multiple rod bundles 22 are arranged in a 3*3 rectangular array. The total length of tube 1 is 2400mm. The diameter of rod bundle 22 is 9.5mm, the center distance between two adjacent rod bundles 22 is 14.875mm, and the rod bundle 22 is divided into upper and lower sections, with the upper section being 750mm long and the lower section being 1340mm long.

[0070] The embodiments of this invention can simulate the size and arrangement of prototype fuel rods, providing important support for core two-phase flow research and core heat transfer research under prototype accident conditions. This invention can perform manifold identification and measurement of the void fraction of rod bundle 22 during top-down gas-liquid two-phase flow. It can also be used for the study of the manifold mechanism of core rod bundle 22 two-phase flow, measurement of cross-sectional void fraction, and verification of empirical formulas under large-break accidents.

[0071] Furthermore, each positioning grid 21 has pressure measuring points on both sides in the first direction. The distance between the pressure measuring point on the water-facing side of the positioning grid 21 and the positioning grid 21 is 10mm, and the distance between the pressure measuring point on the back side of the positioning grid 21 and the positioning grid 21 is 50mm.

[0072] In this embodiment of the invention, the second detection component 4 is arranged in the middle or lower middle part of the first cavity.

[0073] In this embodiment of the invention, multiple pressure measurement points are arranged at intervals along the first direction. By arranging the pressure measurement points reasonably, the differential pressure data can be obtained more accurately. By arranging the position of the second detection component 4 reasonably, the cross-sectional cavitation fraction can be identified more accurately in real time.

[0074] In some embodiments, the first detection component 3 is a differential pressure sensor having multiple measuring points arranged along a first direction within the first cavity to detect the pressure at the inlet of the first cavity and the pressure difference between adjacent measuring points. The second detection component 4 is a linear array sensor. The imaging component 5 includes a light source 52 and a camera 51, which are disposed opposite to each other.

[0075] Multiple measuring points of the differential pressure sensor are arranged in a one-to-one correspondence with the pressure measuring points. The first detection component 3 can obtain the pressure of the gas-liquid two-phase flow at the inlet of the first cavity, and can also obtain the pressure difference between two adjacent measuring points in the vertical direction, thereby providing accurate and effective data parameters.

[0076] Linear array sensors have a large number of measurement points on the same cross section and high measurement accuracy, giving them a significant measurement advantage over optical tubes.

[0077] When performing visual measurements using camera 51, the manifold is not disturbed and can be identified. By reasonably setting the measurement position and light source 52, combined with data processing, the manifold characteristics and cavitation distribution can be reflected more intuitively.

[0078] The characteristics of gas-liquid two-phase flow determine that its measurement is a complex process involving multiple technologies and methods. To address the challenge of measuring the cavitation fraction in gas-liquid two-phase flow, various two-phase flow measurement techniques and schemes have been proposed. However, due to the inherent complexity of two-phase flow and the respective advantages and limitations of each measurement technique, it is difficult to find a single technique that can be used as a universal measurement method in scientific research and industrial monitoring.

[0079] In the actual measurement process, this invention selects or modifies measurement methods based on the geometry and operating conditions of the object under test, obtaining the cross-sectional void fraction through a combination of manifold identification and indirect or direct measurement. Specifically, based on the manifold changes of the two-phase flow from top to bottom in the test section, differential pressure, linear array sensors, and high-speed imaging are used to conduct two-phase flow manifold studies, calculate cross-sectional gas holdup, and qualitatively evaluate frictional pressure drop. The qualitative evaluation of frictional pressure drop provides crucial support for calculating the void fraction in the study of the two-phase flow characteristics of the high-temperature, high-pressure rod bundle 22CHF.

[0080] In some embodiments, the two-phase flow device includes a mixer 9, a gas supply assembly 7, and a liquid supply assembly 8. The outlet end of the mixer 9 is connected to the inlet end of the pipe body 1, and the mixer 9 is used for mixing gas and liquid two-phase substances. The gas supply assembly 7 is connected to the mixer 9 and is used to supply gas into the mixer 9. The liquid supply assembly 8 is connected to the mixer 9 and is used to supply liquid into the mixer 9.

[0081] In this embodiment of the invention, the gas supplied by the gas supply component 7 and the liquid supplied by the liquid supply component 8 are mixed to form a gas-liquid two-phase flow material, which is then transported into the first cavity. By controlling the parameters in the gas supply component 7 and the liquid supply component 8, the two-phase flow pattern can be simulated.

[0082] Furthermore, the air supply assembly 7 includes an air compressor 71, an air supply pipe 72, and a first regulating component disposed on the air supply pipe 72.

[0083] The liquid supply assembly 8 includes a water tank 81, a water supply pipe 82, a first pump 83 and a second regulating component installed on the water supply pipe 82, and a return water pipe 91 is provided between the outlet end of the pipe body 1 and the water tank 81.

[0084] The air compressor 71 provides compressed air, which is delivered into the mixer 9 via the air delivery pipe 72. At the same time, the pressure and flow rate of the gas are controlled by the first regulating component, and the flow rate and temperature can also be detected.

[0085] The water tank 81 is used to store water. The first pump 83 can be a variable frequency centrifugal pump. The first pump 83 is used to draw water from the water tank 81 and transport the water from the water tank 81 into the mixer 9 through the water supply pipe 82. At the same time, the flow rate and temperature of the water in the water supply pipe 82 can be detected by the second regulating component, and the opening and closing of the pipe and the water flow rate can be controlled.

[0086] A third valve 92 is installed on the return water pipe 91.

[0087] Optionally, in this embodiment of the invention, the first valve is a gate valve, and the second valve and the third valve position ball valve are...

[0088] Optionally, the first regulating component includes a pressure reducing valve 73, a gas flow meter 74, a gas flow regulating valve 75, and a first thermometer 76 arranged on the gas transmission pipeline 72. The gas flow meter 74 and the gas flow regulating valve 75 are arranged as a group or multiple groups are arranged in parallel on the gas transmission pipeline 72.

[0089] The second regulating component includes a first valve 84, a liquid flow meter 85, a liquid flow regulating valve 86, and a second thermometer 87 arranged on the water supply pipeline 82. The liquid flow meter 85 and the liquid flow regulating valve 86 are arranged as a group or multiple groups are arranged in parallel on the water supply pipeline 82.

[0090] Furthermore, the second regulating component also includes a check valve 90, which is installed on the water supply pipe 82. The check valve 90 ensures that the medium in the water supply pipe 82 can only flow in one direction, preventing backflow.

[0091] Furthermore, the liquid supply assembly 8 also includes a branch pipe 88, which is located between the outlet of the first pump 83 and the water tank 81, and a second valve 89 is provided on the branch pipe 88. The outlet of the first pump 83 and the water tank 81 form a loop, which can improve the stability of the entire liquid supply assembly 8.

[0092] Furthermore, a baffle 811 is provided inside the water tank 81 to divide the inner cavity of the water tank 81 into two water chambers, the upper parts of the two water chambers are connected. The water tank 81 is provided with an exhaust port 812, a water inlet 813, and a feeding port 814, and the bottom of the water tank 81 is provided with a drain port 815. By setting the baffle 811, the water flowing back into the water tank 81 from the pipe 1 can be separated from the water supplied to the first pump 83, avoiding the direct intake of the gas-liquid two-phase flow into the first pump 83, which would lead to an inaccurate ratio of the two phases in the mixer 9. The exhaust port 812 can timely discharge the gas in the water tank 81, ensuring that the water tank 81 is at normal pressure and reducing the gas content in the water in the water tank 81. The water inlet 813 and the feeding port 814 can share one for replenishing water or other materials into the water tank 81. The drain outlet 815 is used to drain the water in the water tank 81. Since the bottoms of the two water chambers are not connected, a drain outlet 815 is provided at the bottom of each of the two water chambers to facilitate the cleaning of the water tank 81.

[0093] In some embodiments, the system for measuring the cavitation fraction of a rod bundle cross section further includes a data acquisition and processing system 6, which is connected to a two-phase flow device, a first detection component 3, a second detection component 4, and a camera component 5 to acquire and process the acquired data.

[0094] Pressure difference is a relatively easy-to-obtain flow parameter in two-phase flow research. For two-phase flow in a vertical pipe, the pressure drop consists of the gravity pressure drop, friction pressure drop, acceleration pressure drop, and form drag pressure drop. The cavitation fraction is related to the two-phase flow density in the gravity pressure drop; therefore, the cavitation fraction can be determined by finding the gravity pressure drop. Pressure difference can be measured using instruments. Therefore, for two-phase flow in a vertical pipe, the pressure difference method is also a commonly used method for measuring the cross-sectional gas content. The key is to accurately separate the gravity pressure drop and friction pressure drop from the total pressure drop by combining pressure difference measurement.

[0095] The method for measuring the cavitation fraction of a rod bundle cross section disclosed in this invention includes the following steps:

[0096] S101. The arrangement is as described in any of the above embodiments for the rod bundle cross-section cavitation fraction measurement system, with the tube extending vertically and the gas-liquid two-phase flow material in the first cavity flowing from top to bottom;

[0097] S102. Configure the operating parameters of the two-phase flow device and start its operation.

[0098] S103, Based on the formula Δp=Δp fu +Δp a +Δp g and Δp g =-ρ m gh=-[ρ g α+(1-α)ρ l]gh, where Δp is the total pressure drop in the pipeline, Δp fu Δp is the frictional pressure drop during the vertical descent segment. a To accelerate the pressure drop, and Δp a =0, Δp g For the pressure drop due to gravity, ρ g ρ is the gas phase density. l ρ is the density of the liquid phase. m Given the average density of the two-phase flow and α as the cross-sectional void fraction, we can know that:

[0099]

[0100] It should be understood that, when measuring fluid in the vertical descent section using the differential pressure method, the momentum conservation equation is:

[0101]

[0102] in, The total pressure drop in the pipeline is denoted by Δp; τ0P / A is the frictional pressure drop within the vertical descent section, denoted by Δp. fu express; To accelerate the pressure drop, with Δp a It represents; gρ tp sinα is the pressure drop at the point of repose, and Δp is the pressure drop at the point of repose. g express.

[0103] Therefore, the momentum conservation equation can be simplified to: Δp = Δp fu +Δp a +Δp g .

[0104] Based on the average density ρ of the two-phase flow m The model then has Δp g =-ρ m gh=-[ρ g Since there is no change in flow area in the straight pipe, the acceleration pressure drop can be ignored. Therefore, the cross-sectional gas content (cross-sectional cavitation fraction) is:

[0105]

[0106] In the formula, the total pressure drop Δp in the pipeline can be obtained by actual measurement. fu It can be calculated based on the manifold identified by the camera using empirical formulas, or it can be obtained by adjusting the test section, placing it horizontally, and measuring it through experiments.

[0107] S104. Based on the detection data of the first detection component, obtain the total pressure drop Δp in the pipeline.

[0108] S105. Based on the imaging component, identify the two-phase flow pattern, and combine it with the first empirical formula to obtain the frictional pressure drop Δp in the vertical descent section. fu ; and / or, adjust the extension direction of the tube to a second direction, which is orthogonal to the first direction, collect detection data under this working condition, and obtain the frictional pressure drop Δp in the vertical descent section. fu This is to verify the first empirical relation.

[0109] In this embodiment of the invention, the frictional pressure drop Δp within the vertical descent segment is obtained. fu The frictional pressure drop Δp within the vertical descent segment can be obtained through empirical formulas or experimental measurements. fu Verifying empirical relationships can provide important support for calculating the cavitation fraction in the study of two-phase flow characteristics after high-temperature and high-pressure rod bundle CHF.

[0110] S106. Obtain the cross-sectional cavitation fraction α and compare it with the cross-sectional cavitation fraction identified by the second detection component.

[0111] The calculated cross-sectional cavitation fraction α can be compared with the cross-sectional cavitation fraction identified by the second detection component, thereby improving the understanding of the manifold, enhancing its own advantages, obtaining more effective key data, and providing support for the verification and promotion of nuclear power plant safety analysis software.

[0112] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0113] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0114] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0115] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0116] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A system for measuring the void fraction in a rod bundle cross section, characterized in that, include: A tube body having a first cavity and extending along a first direction; A rod bundle assembly, wherein the rod bundle assembly is disposed within the first cavity; A two-phase flow device, wherein the outlet end of the two-phase flow device is connected to the first cavity, and the two-phase flow device is used to configure gas-liquid two-phase flow substances and transport them into the first cavity; A first detection component is connected to the tube body and is used to detect the pressure at multiple pressure measurement points in the first cavity and the pressure difference between at least some of the pressure measurement points. A second detection component is connected to the tube body and is used to identify the cross-sectional cavitation fraction at the first cavity cross-section corresponding to the second detection component. A camera component is used to capture images of a portion of the gas-liquid two-phase flow material in the first cavity to obtain the two-phase flow profile.

2. The system for measuring the cavitation fraction of a rod bundle cross section according to claim 1, characterized in that, The rod bundle assembly includes a positioning grid and multiple rod bundles, which are arranged in parallel and spaced apart. The rod bundles extend along a first direction and are connected to the tube body through the positioning grid.

3. The system for measuring the cavitation fraction of a rod bundle cross section according to claim 2, characterized in that, Each of the positioning grids has pressure measuring points on both sides in the first direction; And / or, the cross-section of the first cavity is square, and the plurality of the rod bundles are arranged in an N*N rectangular array; And / or, the second detection component is arranged in the middle or lower middle part of the first cavity; And / or, the tube is transparent.

4. The system for measuring the cavitation fraction of a rod bundle cross section according to any one of claims 1 to 3, characterized in that, The first detection component is a differential pressure sensor, which has multiple measuring points arranged along a first direction in the first cavity to detect the pressure at the inlet of the first cavity and the pressure difference between adjacent measuring points. And / or, the second detection component is a linear array sensor; And / or, the imaging component includes a light source and a camera, the light source and the camera being disposed opposite to each other.

5. The system for measuring the cavitation fraction of a rod bundle cross section according to claim 1, characterized in that, The first direction is vertical, the upper part of the tube has a first inlet, and the lower part of the tube has a first outlet.

6. The system for measuring the cavitation fraction of a rod bundle cross section according to claim 1, characterized in that, The two-phase flow device includes: A mixer, the outlet end of which is connected to the inlet end of the tube, is used for mixing gas-liquid two-phase substances; A gas supply assembly, connected to the mixer, is used to supply gas into the mixer; A liquid supply assembly is connected to the mixer and is used to supply liquid into the mixer.

7. The system for measuring the cavitation fraction of a rod bundle cross section according to claim 6, characterized in that, The gas supply assembly includes an air compressor, a gas pipeline, and a first regulating component disposed on the gas pipeline; The liquid supply assembly includes a water tank, a water supply pipe, a first pump and a second regulating component installed on the water supply pipe, and a return water pipe is provided between the outlet end of the pipe and the water tank.

8. The system for measuring the cavitation fraction of a rod bundle cross section according to claim 7, characterized in that, The first regulating component includes a pressure reducing valve, a gas flow meter, a gas flow regulating valve, and a first thermometer arranged on the gas transmission pipeline. The gas flow meter and the gas flow regulating valve are arranged in a set or multiple sets are arranged in parallel on the gas transmission pipeline. And / or, the second regulating component includes a first valve, a liquid flow meter, a liquid flow regulating valve and a second thermometer arranged on the water supply pipeline, wherein the liquid flow meter and the liquid flow regulating valve are a set or multiple sets are arranged in parallel on the water supply pipeline; And / or, it also includes a check valve, said check valve being disposed on the water supply pipeline; And / or, it also includes a branch pipe, which is located between the outlet end of the first pump and the water tank, and the branch pipe is equipped with a second valve; And / or, the water tank is provided with a baffle to divide the inner cavity of the water tank into two water chambers, the upper parts of the two water chambers are connected, the water tank is provided with an exhaust port, a water inlet and a feeding port, and the bottom of the water tank is provided with a drain port.

9. The system for measuring the cavitation fraction of a rod bundle cross section according to claim 1, characterized in that, It also includes a data acquisition and processing system, which is connected to the two-phase flow device, the first detection component, the second detection component and the camera component to acquire and process the acquired data.

10. A method for measuring the void fraction in a rod bundle cross section, characterized in that, Includes the following steps: The system for measuring the cavitation fraction of a rod bundle cross section is arranged as described in any one of claims 1 to 9, wherein the tube extends vertically and the gas-liquid two-phase flow material in the first cavity flows from top to bottom; Configure the operating parameters of the two-phase flow device and start its operation; Based on the formula Δp=Δp fu +Δp a +Δp g and Δp g =-ρ m gh=-[ρ g α+(1-α)ρ l ]gh, where Δp is the total pressure drop in the pipeline, Δp fu Δp is the frictional pressure drop during the vertical descent segment. a To accelerate the pressure drop, and Δp a =0, Δp g For the pressure drop due to gravity, ρ g Let ρ be the density of the gas phase and ρ be the density of the liquid phase. m Given the average density of the two-phase flow and α as the cross-sectional void fraction, we can know that: Based on the detection data from the first detection component, the total pressure drop Δp in the pipeline is obtained; Based on the imaging component, the two-phase flow pattern is identified, and the frictional pressure drop Δp in the vertical descent section is obtained by combining the first empirical formula. fu ; and / or, adjust the extension direction of the tube to a second direction, which is orthogonal to the first direction, collect detection data under this working condition, and obtain the frictional pressure drop Δp in the vertical descent section. fu To verify the first empirical relation; Obtain the cross-sectional cavitation fraction α and compare it with the cross-sectional cavitation fraction identified by the second detection component.

Images