System and method for measuring phase interface concentration of gas-liquid two-phase flow in channel

Abstract

The invention discloses a system for measuring the phase interface concentration of gas-liquid two-phase flow in a channel. A spiral cross-shaped fuel rod bundle is fixed in a rod bundle experiment section; the gas-water mixer is connected to the bottom of the rod bundle experiment section, receives gas and water, mixes the gas and the water to form gas-liquid two-phase flow, and then the gas-liquid two-phase flow is introduced into the rod bundle experiment section. The silk screen probe sensors are horizontally arranged in the rod bundle experiment section, each silk screen probe sensor comprises two layers of silk screen probes, and each layer of silk screen probe comprises an emitting electrode, a receiving electrode and a measuring point. And the circuit acquisition module is in signal connection with the silk screen probe sensor and is used for providing excitation voltage for the silk screen probe and outputting different electric signal values after passing through a loop so as to identify different phase states in the rod cluster experiment section. The circuit acquisition module outputs different electric signal values to identify different phase states, the phase volume fraction of the gas-liquid two-phase flow field can be calculated based on the distance between the screen probes, and refined basic experimental data including phase distribution can be obtained more effectively.

Description

Technical Field

[0001] The invention belongs to the field of multiphase flow parameter measurement and nuclear reactor thermal hydraulics, and in particular relates to a system and method for measuring the phase interface concentration of a gas-liquid two-phase flow in a channel. Background Art

[0002] Under accident conditions, the gas-liquid flow formed in the rod bundle channel of a boiling water reactor or a pressurized water reactor has multidimensional transient flow characteristics. As a new type of reactor fuel assembly, spiral cross fuel has many advantages such as short heat conduction distance, strong mixing ability, and no need for positioning racks. It can effectively improve the power of the core while ensuring the safety margin of the reactor. Compared with simple pipelines, the dynamic behaviors of bubble aggregation, fragmentation and migration in the spiral cross rod bundle channel are more complex. From the perspective of reactor thermal hydraulics, a comprehensive understanding of the spatiotemporal distribution of each phase in the rod bundle channel is directly related to the structural design and heat dissipation performance of the rod bundle, and to the economy and reliability of the reactor. In addition, the verification of multidimensional gas-liquid flow analysis codes (such as sub-channel analysis), the establishment of computational fluid dynamics (CFD) calculation models, and the establishment of rod bundle gas-liquid flow theory must rely on the database of gas-liquid two-phase flow in the rod bundle channel.

[0003] In view of the dynamic behavior of the gas-liquid two-phase flow formed in the spiral cross fuel bundle area of ​​a pressurized water reactor, people mainly use methods such as high-speed cameras and radiation technology to study the gas-liquid flow in the channel. However, although high-speed cameras can identify the flow state in the bundle channel, they cannot accurately obtain the cavitation fraction and phase interface concentration of the two-phase flow; due to the influence of the wall and the limitation of time resolution, radiation technology cannot accurately capture the rapid fluctuations of the void fraction in the dynamic flow of gas and liquid. In addition, the design and construction of this measurement technology is very complex and expensive. Due to the limitations of existing measurement technology, there is a lack of refined basic experimental data on the gas-liquid two-phase flow in the spiral cross fuel bundle channel, and the phase content evolution behavior generated during the accident process is unclear, resulting in a relative lack of relevant experimental mechanisms and physical models.

[0004] Therefore, it is currently necessary to develop measurement technology that can be applied to the spiral cross fuel bundle channel and has high temporal and spatial resolution to analyze the coordinated measurement of the gas-liquid two-phase flow field and phase interface concentration in the structural pipeline, to achieve the acquisition of basic experimental data, and to provide a guarantee for the development of mechanism research. Summary of the invention

[0005] The technical purpose of the present invention is to provide a system and method for measuring the phase interface concentration of gas-liquid two-phase flow in a channel, so as to solve the problem of lack of basic experimental data of gas-liquid two-phase flow in a spiral cross fuel bundle channel.

[0006] To solve the above problems, the technical solution of the present invention is:

[0007] A system for measuring the concentration of a gas-liquid two-phase flow interface in a channel, comprising:

[0008] Experimental device and circuit acquisition module;

[0009] The experimental device includes a rod bundle experimental section, a gas-water mixer and a plurality of wire mesh probe sensors; a spiral cross fuel rod bundle is fixed in the rod bundle experimental section; the gas-water mixer is connected to the bottom of the rod bundle experimental section, and is configured to receive gas and water respectively and mix them to form a gas-liquid two-phase flow, and then pass them into the rod bundle experimental section; a plurality of wire mesh probe sensors are horizontally arranged in the rod bundle experimental section, each wire mesh probe sensor includes two layers of wire mesh probes, and each layer of wire mesh probes includes an emitter, a receiver and a measuring point;

[0010] The circuit acquisition module is connected to the wire mesh probe sensor signal. The wire mesh probe, different phase fluid media in the rod bundle experimental section and the circuit acquisition module form a loop, and the different phase fluid media are in parallel with each other. The circuit acquisition module is configured to provide an excitation voltage to the wire mesh probe, and output different electrical signal values ​​after the loop to identify different phase states in the rod bundle experimental section.

[0011] Among them, the spiral cross fuel rod bundles in the rod bundle test section are set with equal diameter and pitch. The cross-section of the rod bundle test section is a square structure of 66.1mm×66.1mm. The hydraulic diameter of the rod bundle test section is 10.28mm, the diameter of the spiral cross fuel rod bundle is 9.5mm, the spacing between adjacent spiral cross fuel rod bundles is 12.6mm, and the hydraulic diameter of the flow field area directly surrounded by adjacent spiral cross fuel rod bundles is 8.321mm.

[0012] Specifically, each layer of the wire mesh probe includes a mesh-shaped wire mesh structure with a total of 32*32 intersections and a total of 1024 test points. The nodes on the connected ends on both sides of the wire mesh structure are the transmitting end and the receiving end respectively. The test points, the transmitting end and the receiving end are all provided with stainless steel with a diameter of 0.1mm as electrode wires, which are welded on a PCB circuit board with a thickness of 2mm. The spacing between adjacent electrode wires is 2mm, and the axial distance between adjacent wire mesh probes is 2mm.

[0013] Further preferably, 32 insulating connecting plugs of the same size are embedded between the transmitting end and the receiving end, and the electrode wires in contact with the cross-section of the insulating connecting plugs are covered with insulating glue.

[0014] The height of the gas-water mixer is 1500 mm, and a mixing channel with an inner diameter of about 1.2 mm and a length of 1000 mm is provided at the connection between the gas-water mixer and the rod bundle experimental section.

[0015] A method for measuring the concentration of a gas-liquid two-phase flow interface in a channel, configured in the above-mentioned system for measuring the concentration of a gas-liquid two-phase flow interface in a channel, comprises the following steps:

[0016] Water is supplied to the gas-water mixer through the liquid phase inlet, and gas is injected into the gas-water mixer through the gas phase inlet, so that the gas and liquid phases are fully mixed in the gas-water mixer;

[0017] The mixed gas-liquid two-phase flow enters the rod bundle experimental section;

[0018] When the gas-liquid two-phase flow passes through the wire mesh probe sensor, different electrical signals are generated due to the different electrical conductivities of the gas and liquid phases. The generated signals enter the circuit acquisition module through the receiving end. After data processing, the relevant parameters of the gas-liquid two-phase flow field and phase interface concentration in the rod bundle experimental section are obtained.

[0019] Specifically, the calculation of the phase interface satisfies the following formula:

[0020]

[0021] Among them, R i,j,k is the normalized signal collected at time k, is the local fluid conductivity passing through the wire mesh probe sensor, is the conductivity of the single-phase fluid in the rod bundle experimental section, a i,j,k is the vacuolar fraction at time k.

[0022] Specifically, the calculation of the local cavitation fraction satisfies the following formula:

[0023]

[0024] Among them, A i,j,in and A i,j,total are the flow channel area and total cross-sectional area of ​​the rod bundle experimental section, α area is the area average gas content, is the time-averaged cavitation fraction.

[0025] Specifically, the gas phase volume in the two-layer wire mesh probe meets the following functional relationship:

[0026]

[0027] The calculation of the phase interface concentration within the two-layer wire mesh probe meets the following formula:

[0028]

[0029] Among them, j g is the superficial gas velocity, j f is the superficial liquid velocity, A duct is the cross-sectional area of ​​the flow channel, tmeas The time for measurement.

[0030] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0031] The present invention can measure the phase content change of the cross-sectional area of ​​the experimental section, convert the collected electrical signal into a conductivity signal, calculate the phase interface concentration in the rod bundle area through the processing system, the wire mesh probe is arranged in the entire flow channel cross section except the rod bundle, and the circuit acquisition module is connected to the wire mesh probe to provide an excitation voltage. When different fluid media flow through the wire mesh probe, the circuit acquisition module outputs different electrical signal values ​​to identify different phase states, and the phase content of the gas-liquid two-phase flow field can be calculated based on the wire mesh probe spacing. Compared with the prior art, the present invention can more effectively obtain refined basic experimental data including phase distribution, laying a foundation for related theoretical research. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the invention.

[0033] Figure 1 It is a structural schematic diagram of a system for measuring the concentration of a gas-liquid two-phase flow interface in a channel according to the present invention;

[0034] Figure 2 It is a physical schematic diagram of the wire mesh probe sensor of the present invention;

[0035] Figure 3 It is a schematic structural diagram of a spiral cross fuel bundle of the present invention;

[0036] Figure 4 It is a schematic diagram of a test cross section of a wire mesh probe sensor of the present invention;

[0037] Figure 5 The figure is a circuit diagram of the circuit acquisition module of the present invention.

[0038] Description of Reference Numerals

[0039] 1: Gas phase inlet; 2: Liquid phase inlet; 3: Gas-water mixer; 4: Positioning shelf; 5: Silk screen probe sensor; 6: Wire; 7: Probe circuit power supply; 8: Transmitter; 9: Receiver; 10: Signal acquisition circuit; 11: Bus. DETAILED DESCRIPTION

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0041] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0042] The following is a further detailed description of a system and method for measuring the concentration of a gas-liquid two-phase flow interface in a channel proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0043] See the embodiment Figures 1 to 5 This embodiment provides a system for measuring the concentration of the gas-liquid two-phase flow interface in a channel, which mainly includes an experimental device and a circuit acquisition module. Based on the electrical principle to measure the phase state, under normal experimental conditions, the wire mesh probe sensor is arranged in the flow channel of the experimental section body. The multiphase flow field consists of water and gas phase components, and the circuit acquisition module provides an excitation voltage for the wire mesh probe system. The current is introduced from the wire mesh probe sensor into the multiphase flow field. Based on the different electrical conductivities of the gas phase and the liquid phase, the gas-liquid two phases are identified. The equivalent circuit diagram is shown in the figure. Figure 5 As shown. When the wire mesh probe sensor is in contact with the gas phase component, the gas phase component is equivalent to the equivalent resistor in the equivalent circuit; similarly, when the wire mesh probe is in contact with the water phase component, the water phase component is equivalent to the equivalent resistor in the acquisition circuit. Based on the different electrical conductivities of the two-phase fluids, different electrical signal values ​​are output to distinguish the spatial distribution of the two-phase fluids. According to the cross-correlation analysis of the electrical signals between adjacent wire mesh probe sensors, the evolution speed of the phase interface and the change in phase content can be determined. Therefore, based on the wire mesh probe sensor, the coordinated measurement of the gas-liquid two-phase flow field and the phase interface concentration in the spiral cross fuel rod bundle channel can be realized.

[0044] Specifically, see Figure 1In this embodiment, the experimental device includes a rod bundle test section, a gas-water mixer and a plurality of wire mesh probe sensors. A positioning shelf is provided in the rod bundle test section, and the positioning shelf is used to fix the spiral cross fuel rod bundle. The bottom of the rod bundle test section is connected to a gas-water mixer, which can receive gas and water respectively and mix them to form a gas-liquid two-phase flow, and then pass into the rod bundle test section. A plurality of wire mesh probe sensors are horizontally arranged in the rod bundle test section, that is, arranged on the cross section of the rod bundle test section, and each wire mesh probe sensor includes two layers of wire mesh probes, and each layer of wire mesh probes includes an emitter, a receiver and a measuring point.

[0045] Specifically, the gas-water mixer is provided with a gas phase inlet at its bottom, which is connected to the air compressor pipeline by a rubber tube. Furthermore, the gas-water mixer is provided with a liquid phase inlet at its side, which is also connected to the water pump pipeline by a rubber tube. In order to ensure the mixing of gas-liquid two-phase flow, the height of the gas-water mixer is 1500mm, and a mixing channel with an inner diameter of about 1.2mm and a length of 1000mm is provided at the connection between the gas-water mixer and the rod bundle experimental section, so that the gas-liquid mixed two-phase flow can be fully developed.

[0046] Next, the spiral cross fuel rod bundles in the rod bundle test section are set with equal diameter and equal pitch. The cross section of the rod bundle test section is the rod bundle channel, which is a square structure of 66.1mm×66.1mm. The hydraulic diameter of the rod bundle channel (hydraulic diameter is the ratio of four times the cross-sectional area of ​​the flow channel to the circumference of the fuel rod, and the cross-sectional area of ​​the flow channel is the cross-sectional area of ​​the rod bundle channel excluding the rod bundle) is 10.28mm. The diameter of the spiral cross fuel rod bundle is 9.5mm, the spacing between adjacent spiral cross fuel rod bundles is 12.6mm, and the hydraulic diameter of the subchannel (the flow field area directly surrounded by adjacent spiral cross fuel rod bundles) is 8.321mm. The wire mesh probe sensor is installed at 2250mm from the bottom of the rod bundle channel. The wire mesh probe sensor can collect two-phase flow data of the central subchannel (central area of ​​the subchannel), side subchannel (side area of ​​the subchannel), corner subchannel (corner area of ​​the subchannel) and sidewall subchannel (subchannel close to the wall) of the rod bundle channel.

[0047] See also Figure 1 , Figure 4 and Figure 5 , the wire mesh probe sensor is arranged at the cross section as Figure 4As shown in the figure, the cross structure is the cross section of the spiral cross fuel rod bundle, and the wire mesh structure is in the form of a mesh. The wire mesh structure has a total of 32*32 intersections, that is, it has 1024 test points, which are evenly distributed on the cross section of the rod bundle channel. The signal transmitting end is located on one side of the wire mesh structure, and the side vertically adjacent to the transmitting end is the receiving end of the signal. The test point, the transmitting end and the receiving end are all provided with stainless steel with a diameter of 0.1mm as electrode wires, which are welded on a PCB circuit board with a thickness of 2mm (the circuit board is used to support the electrode wires of the transmitting end and the receiving end). The spacing between adjacent electrode wires is 2mm, and the axial distance between adjacent wire mesh probes is 2mm. The test point ground data acquisition frequency is 5000Hz, and each record lasts for 20s. During the measurement process, the electrode at the transmitting end is continuously activated, while keeping all other transmitting electrodes at ground potential. In addition, 32 insulating connection plugs of the same size are embedded between the electrode wires of the transmitting end and the receiving end, and then the electrode wires in contact with the cross section of the insulating connection plugs are covered with insulating glue. Such a design ensures that only the intersection points in the spiral cross fuel bundle channel are in contact with the fluid, while the intersection points covered by the bundle cross section are not in contact with the fluid.

[0048] Next, see Figure 5 The circuit acquisition module and the wire mesh probe sensor are connected to each other through the probe lead wires arranged on the side wall of the experimental section body. The wire mesh probe, the different phase fluid media in the rod bundle experimental section and the circuit acquisition module form a loop, and the different phase fluid media are in parallel with each other. The circuit acquisition module includes an excitation circuit and a signal acquisition circuit. The excitation circuit is used to provide an excitation voltage to the wire mesh probe, and outputs different electrical signal values ​​after passing through the loop, which are collected by the signal acquisition circuit to identify different phases in the rod bundle experimental section.

[0049] Further preferably, the present embodiment also provides a method for measuring the phase interface concentration of the gas-liquid two-phase flow in the channel, and the measurement system for the phase interface concentration of the gas-liquid two-phase flow in the above-mentioned channel includes the following steps: using a water pump to supply water to the gas-water mixer through the liquid phase inlet, and using an air compressor to inject gas into the gas-water mixer through the gas phase inlet, and the gas and liquid phases are fully mixed in the gas-water mixer. The mixed gas-liquid two-phase flow enters the rod bundle experimental section. When the gas-liquid two-phase flow passes through the wire mesh probe sensor, different electrical signals are formed due to the different electrical conductivities of the gas and liquid phases. The generated signals enter the signal acquisition circuit through the receiving end, and are summarized to the host computer through the bus for data processing to obtain the gas-liquid two-phase flow field and phase interface concentration and other related parameters in the rod bundle experimental section. After passing through the experimental section, the gas-liquid two-phase flows out from the top of the rod bundle channel, and the two phases are separated by the gas-water separator. The separated gas phase is discharged into the atmosphere, and the separated liquid phase enters the water tank.

[0050] Preferably, the signal acquisition circuit filters the noise signal used by setting a very low threshold, identifies the core area of ​​the bubble and assigns the peripheral elements of the bubble to the identified bubble using a cell automatic calculation method, thereby completing the identification of the bubble.

[0051] Preferably, the cross-correlation velocity is used as the gas phase velocity of the bubble. For a node P(i, j), the cross-correlation function of two layers of wire mesh probes of the same wire mesh probe sensor at the node satisfies the following formula:

[0052]

[0053] Among them, R i,j (Δk) is the mutual correlation coefficient of node P(i,j) when the delay frame number is Δk, f i,j (k) and g i,j (k) is the cavitation fraction value measured by two groups of wire mesh probes at the node P(i,j) at an instant.

[0054] Preferably, for the node P(i,j), the calculation of the phase interface satisfies the following formula:

[0055]

[0056] Among them, R i,j,k is the normalized signal collected at time k, is the local fluid conductivity passing through the wire mesh probe sensor, is the conductivity of the single-phase fluid in the rod bundle experimental section, a i,j,k is the vacuolar fraction at time k.

[0057] Preferably, this embodiment also uses the number of delayed frames corresponding to the peak value of the mutual correlation coefficient as the average phase velocity of the node P(i, j) within the measurement time, which satisfies the following function formula:

[0058]

[0059] Wherein, L is the axial distance between the two groups of wire mesh probes, and f is the imaging frequency.

[0060] Preferably, when calculating the bubble interface concentration in this embodiment, all elements of the bubble are first extracted, and the interface side length, area and bubble volume in the bubble region identified in each frame are calculated. The interface area in the identified bubble region satisfies the following formula:

[0061]

[0062] The volume of gas phase in the identified bubble region is:

[0063]

[0064] Where Δz = v i,j / f sample is the height between the double-layer wire mesh probe structures, f sample is the acquisition frequency of the probe, A i,j,k is the area inside the line of equal cavitation fraction in the region obtained by integrating the identified gas phase boundary.

[0065] Preferably, the calculation of the local cavitation fraction in this embodiment satisfies the following formula:

[0066]

[0067]

[0068] Among them, A i,j,in and A i,j,total are the flow channel area and total cross-sectional area of ​​the rod bundle experimental section, α area is the area average gas content, is the time-averaged cavitation fraction.

[0069] Preferably, the gas phase volume in the double-layer wire mesh probe structure measured satisfies the following functional relationship:

[0070]

[0071] Preferably, the measured interface concentration in the double-layer wire mesh probe structure satisfies the following functional relationship:

[0072]

[0073] Among them, j g is the superficial gas velocity, j f is the apparent liquid velocity, A duct is the cross-sectional area of ​​the flow channel, t meas The time for measurement.

[0074] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A system for measuring the concentration of the gas-liquid two-phase flow interface in a channel, characterized in that: include: Experimental device and circuit acquisition module; The experimental device comprises a rod bundle experimental section, a gas-water mixer and a plurality of wire mesh probe sensors; a spiral cross fuel rod bundle is fixed in the rod bundle experimental section; the gas-water mixer is connected to the bottom of the rod bundle experimental section, and is configured to receive gas and water respectively and mix them to form a gas-liquid two-phase flow, and then pass them into the rod bundle experimental section; a plurality of wire mesh probe sensors are horizontally arranged in the rod bundle experimental section, each of the wire mesh probe sensors comprises two layers of wire mesh probes, and each layer of the wire mesh probes comprises an emitter, a receiver and a measuring point; The circuit acquisition module is connected to the wire mesh probe sensor signal, the wire mesh probe, the different phase fluid media in the rod bundle experimental section and the circuit acquisition module form a loop, and the different phase fluid media are connected in parallel with each other. The circuit acquisition module is configured to provide an excitation voltage to the wire mesh probe, and output different electrical signal values ​​after the loop to identify different phase states in the rod bundle experimental section.

2. The system for measuring the concentration of the gas-liquid two-phase flow interface in the channel according to claim 1, characterized in that: The spiral cross fuel rod bundles in the rod bundle test section are arranged with equal diameter and pitch. The cross section of the rod bundle test section is a square structure of 66.1 mm×66.1 mm. The hydraulic diameter of the rod bundle test section is 10.28 mm. The diameter of the spiral cross fuel rod bundle is 9.5 mm. The spacing between adjacent spiral cross fuel rod bundles is 12.6 mm. The hydraulic diameter of the flow field area directly surrounded by adjacent spiral cross fuel rod bundles is 8.321 mm.

3. The system for measuring the concentration of the gas-liquid two-phase flow interface in a channel according to claim 1, characterized in that: Each layer of the wire mesh probe includes a mesh-shaped wire mesh structure, which has a total of 32*32 intersections and a total of 1024 test points. The nodes on the connected ends on both sides of the wire mesh structure are respectively the transmitting end and the receiving end. The test points, the transmitting end and the receiving end are all provided with stainless steel with a diameter of 0.1mm as electrode wires, which are welded on a PCB circuit board with a thickness of 2mm. The spacing between adjacent electrode wires is 2mm, and the axial distance between adjacent wire mesh probes is 2mm.

4. The system for measuring the concentration of the gas-liquid two-phase flow interface in the channel according to claim 3, characterized in that: 32 insulating connecting plugs of the same size are embedded between the transmitting end and the receiving end, and the electrode wires in contact with the cross-sections of the insulating connecting plugs are covered with insulating glue.

5. The system for measuring the concentration of the gas-liquid two-phase flow interface in a channel according to claim 1, characterized in that: The height of the gas-water mixer is 1500 mm, and a mixing channel with an inner diameter of about 1.2 mm and a length of 1000 mm is provided at the connection between the gas-water mixer and the rod bundle experimental section.

6. A method for measuring the concentration of a gas-liquid two-phase flow interface in a channel, configured in a system for measuring the concentration of a gas-liquid two-phase flow interface in a channel as claimed in any one of claims 1 to 5, characterized in that: The steps include: Water is supplied to the gas-water mixer through the water inlet, and gas is injected into the gas-water mixer through the gas inlet, so that the gas and liquid phases are fully mixed in the gas-water mixer; The mixed gas-liquid two-phase flow enters the rod bundle experimental section; When the gas-liquid two-phase flow passes through the wire mesh probe sensor, different electrical signals are generated due to the different electrical conductivities of the gas and liquid phases. The generated signals enter the circuit acquisition module through the receiving end. After data processing, the relevant parameters of the gas-liquid two-phase flow field and phase interface concentration in the rod bundle experimental section are obtained.

7. The method for measuring the concentration of the gas-liquid two-phase flow interface in a channel according to claim 6, characterized in that: The calculation of the phase interface satisfies the following formula: Among them, R i,j,k is the normalized signal collected at time k, is the local fluid conductivity passing through the wire mesh probe sensor, is the conductivity of the single-phase fluid in the rod bundle experimental section, a i,j,k is the vacuolar fraction at time k.

8. The method for measuring the concentration of the gas-liquid two-phase flow interface in a channel according to claim 7, characterized in that: The calculation of the local cavitation fraction satisfies the following formula: Among them, A i,j,in and A i,j,total are the flow channel area and total cross-sectional area of ​​the rod bundle experimental section, α area is the area average gas content, is the time-averaged cavitation fraction.

9. The method for measuring the concentration of the gas-liquid two-phase flow interface in a channel according to claim 6, characterized in that: The gas phase volume in the two layers of the wire mesh probes measured satisfies the following functional relationship: The calculation of the phase interface concentration within the two layers of the wire mesh probes measured satisfies the following formula: Among them, j g is the superficial gas velocity, j f is the apparent liquid velocity, A duct is the cross-sectional area of ​​the flow channel, t meas The time for measurement.

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