Coupling phase distributed two-phase flow measurement sensor

Abstract

The invention discloses a two-phase flow measurement sensor with coupled phase distribution. A to-be-measured two-phase flow is arranged in the insulated measurement pipeline, and the internal space of the insulated measurement pipeline is an effective measurement domain of the sensor; the flanges are arranged at two ends of the insulated measuring pipeline; the flexible circuit board adopts a multi-layer printed circuit board technology and comprises two completely identical flexible measuring electrode arrays, three flexible axial shielding rings and a flexible circuit insulating layer; the flexible axial shielding rings are respectively arranged in the middle and at the two ends of the two groups of flexible measuring electrode arrays, and the two groups of flexible measuring electrode arrays are respectively used as an upstream phase distribution sensor and a downstream phase distribution sensor; and an insulating sleeve and a shielding cover are arranged outside. The existing multi-electrode capacitance sensor for measuring the phase distribution of the low-temperature fluid applied to an electrical capacitance tomography (ECT) system is improved, a double-ECT sensor cross-correlation measurement scheme is provided, and the flow of two-phase flow is measured by measuring the cross-correlation of phase distribution information.

Description

Technical Field

[0001] This invention relates to the fields of cryogenic refrigeration engineering technology, fluid flow process monitoring, two-phase flow measurement and sensor science and technology, and in particular to a two-phase flow measurement sensor with coupled phase distribution. Background Technology

[0002] Cryogenic gas-liquid two-phase flows are widely used in important fields such as aerospace, energy, and chemical engineering, specifically in key projects such as aerospace propellant transportation and LNG loading and unloading, and are an important component of industrial fluid transportation research. Obtaining accurate flow rate data of the working fluid is crucial for understanding its real-time state. However, due to the nature of cryogenic gas-liquid two-phase flows and the limitations of existing flowmeters, the direct, accurate, and rapid measurement of two-phase flow rates remains a challenging problem.

[0003] Low-temperature gas-liquid two-phase flows exhibit complex flow patterns and unique physical properties, such as significantly lower surface tension and viscosity compared to ambient-temperature two-phase flows, as well as a larger gas-liquid density ratio. This makes traditional single-phase flowmeters based on homogeneous working fluids often inadequate for measuring low-temperature gas-liquid two-phase flows. For example, electromagnetic flowmeters are only suitable for homogeneous liquids; throttling flowmeters experience flow field disturbances during measurement, and their accuracy is significantly affected by cavitation; ultrasonic flowmeter performance is affected by flow field disturbances; Coriolis mass flowmeters have poor zero-point stability, resulting in lower accuracy for low-density fluids, and decoupling and compression effects also cause substantial errors. In conclusion, existing theoretical models of single-phase flowmeters struggle to achieve ideal accuracy under two-phase flow conditions. Therefore, low-temperature gas-liquid two-phase flow measurement methods that couple phase distribution information should be considered to expand the application scenarios of low-temperature flowmeters.

[0004] Electrical Capacitance Tomography (ECT) technology utilizes the difference in dielectric properties between gas and liquid phases. By applying an electric field within the measurement pipe, the dielectric distribution information is reflected in measurable capacitance data, and then an inversion algorithm is used to reconstruct the phase distribution image of the fluid. The sensor is the front end of the ECT system, and its core component is an electrode array. The capacitance signal acquisition unit at the back end measures the capacitance value between each pair of electrodes in the electrode array and transmits it to the imaging display system on the host computer. The inversion algorithm on the host computer then processes the data to obtain the phase distribution image. The shielded electrodes and shielding cover in the sensor prevent interference from external electric fields and reduce measurement noise. Compared with other phase distribution measurement methods such as capacitance probe methods, radiographic methods, MRI, and radio frequency methods, ECT, as a non-invasive measurement method, has advantages such as convenient assembly, fast imaging speed, low cost, no interference with the flow field, and the ability to simultaneously obtain phase content and phase distribution data. Therefore, there has been extensive research on ECT in the field of image reconstruction of room temperature fluids, and in recent years, the feasibility of applying ECT to the measurement of phase content and phase distribution reconstruction of low-temperature gas and liquid two-phase flows has also been effectively demonstrated.

[0005] However, the application of ECT (Electro-Conduction Sensor) in the measurement of flow rates in cryogenic gas-liquid two-phase flows has been rarely studied. Compared with existing flow measurement methods, the coupled phase distribution flow measurement method has the advantages of: the ECT sensor used in this method is non-invasive and non-contact, which can greatly reduce the impact on the flow field; the ECT sensor can quickly obtain the instantaneous phase distribution and phase content information of the flow field cross section, and can collect the phase distribution information at different locations as capacitance signals and transmit them to the host computer for comprehensive processing to obtain the flow rate, realizing the simultaneous measurement of phase distribution, phase content and flow rate. However, the difficulty lies in the measurement of velocity, because the two-phase velocity may exhibit slippage, and the characteristics of slippage vary depending on the flow state, requiring further experimental verification.

[0006] Cross-correlation velocimetry is a common velocity measurement method used for ambient temperature two-phase flows (such as gas-solid two-phase flows). The general idea is to place a sensor upstream and downstream of the flow channel to record signals reflecting certain properties of the fluid at those points. As the fluid flows past the upstream and downstream sensors, due to instabilities in the two-phase flow (such as changes in bubble distribution or local volume fraction), the signals recorded by the two sensors will exhibit similarities and time delays. The fluctuation characteristics of the signal are known as the cross-correlation, and the degree of correlation can be described by the cross-correlation function: Through calculation By determining the peak position, the time delay corresponding to the maximum correlation between signals can be obtained. The velocity can be considered as the time it takes for the same fluid segment to move from one sensor to another. Combined with the known sensor spacing, the flow velocity can be calculated. In reality, in most cases, two-phase flows exhibit velocity slip, which is closely related to the flow pattern. Therefore, a slip model should be introduced to correct the velocity calculation results. However, few studies directly utilize the phase distribution information of the fluid at upstream and downstream sensors to calculate the cross-correlation function and thus obtain the flow velocity.

[0007] Zhang Xiaobin, Xie Huangjun, Xia Tao, Gao Xinxin, Tian Zenan, and Ren Ziru, among others, from the Institute of Refrigeration and Cryogenics at Zhejiang University, have made significant contributions to the application of electro-conductive imaging (ECT) technology in the measurement of cryogenic gas-liquid two-phase flows. Xie Huangjun (Theoretical and Experimental Study on Cryogenic Two-Phase Flow Inversion Based on Multi-Electrode Capacitive Sensor [D]. Zhejiang University, 2021.) first verified the feasibility of cryogenic applications of ECT technology and conducted numerical simulation experiments to measure the phase distribution and phase content of two-phase flows. Xia Tao (Theoretical and Experimental Study on Cryogenic Phase Content Sensor Based on Capacitive Tomography [D]. Zhejiang University, 2022.) optimized the electrode plates of the ECT sensor and conducted numerical simulation experiments on the cryogenic application of three-dimensional capacitive tomography (ECVT). Gao Xinxin and Tian Zenan et al. (A Hybrid Deep Learning Model for ECT Image Reconstruction of Cryogenic Fluids [J]. Flow Measurement and Instrumentation, 2022, 87; Experimental Imaging and Algorithm) Two inversion imaging algorithms based on deep learning were proposed in *OptimizationBased on Deep Neural Network for Electrical Capacitance Tomography for LN2-VN2 Flow*, and numerical simulation experiments and liquid nitrogen two-phase flow imaging experiments were carried out. Gao et al. (*Study on Spatial Resolution of Electrical Capacitance Tomography for Cryogenic Fluid*, *Measurement*, 2025, 251: 117333.) also determined the definition and calculation method of imaging resolution parameters for cryogenic ECT systems. Ren et al. (*Research on Cryogenic Two-phase Flow Imaging of Spherical Container Based on Electrical Capacitive Volume Tomography*, *Cryogenics*, 2025: 104103.) studied the application of ECVT in the measurement of phase distribution of two-phase flow in spherical containers.These studies primarily focus on measuring the phase distribution or phase content of cryogenic gas-liquid two-phase flows, with an emphasis on obtaining two-dimensional or three-dimensional inversion images. Straiton et al. (Capacitance-based Measurement of Volume Fraction, Velocity, and Mass Flow Rate of Cryogenic Nitrogen Two-phase Flow [C] / / IOP Conference Series: Materials Science and Engineering. IOP Publishing, 2024, 1301(1): 012081; Capacitance-based Mass Flow Rate Measurement of Two-phase Hydrogen in a 0.5in. Tube [J]. Cryogenics, 2024, 144: 103983.) based on a scheme from Tech4Imaging, independently measured the phase content of cryogenic gas-liquid two-phase flows in a tube using two identical, parallel-connected capacitive sensors. The phase content information was then aggregated into a signal processing unit, and the velocity was calculated using a cross-correlation method. These studies designed sensors with only four electrodes per group, and could only obtain phase content information, not inversion images.

[0008] Chinese patent CN117871621A discloses a visual capacitance tomography system. The invention is applicable to low temperature environments and uses a circular tube as the applicable pipe structure. Electrode sheets are arranged on the outside of the circular tube, enabling real-time monitoring of flow patterns in two-dimensional imaging.

[0009] Chinese patent CN120629284A discloses a volume tube phase flow state monitoring device and method based on capacitance tomography. This invention introduces the ECT method in the volume tube to realize the detection of the gas-liquid two-phase flow distribution state, and the applicable temperature environment is room temperature.

[0010] Chinese patent CN120467599A discloses a cryogenic safety valve leakage detection device and method based on capacitance tomography (ECT). The capacitance measurement system includes multiple sets of copper electrode plates and a processing module. Each set of copper electrode plates includes two copper electrode plates arranged on opposite sides of a water tank, used to capture bubbles formed by cryogenic gas in the chamber and acquire capacitance signals. This invention is applicable to cryogenic environments and achieves accurate measurement of the leakage rate of cryogenic valves by introducing the ECT method.

[0011] Chinese patent CN219200519U discloses a precise gas-liquid two-phase measurement device. When the input gas-liquid two-phase flow is under low pressure, the device directly reads the high-pressure mass flow meter to obtain the precise measurement results of parameters such as mass flow rate and volumetric flow rate of the gas-liquid two-phase flow. When the input gas-liquid two-phase flow is under high pressure, the device splits the gas-liquid two-phase flow and then measures the parameters of the gas flow under low pressure to calculate the various parameters of the gas-liquid two-phase flow under high pressure. This device is suitable for the precise measurement of mass flow rate and other parameters of gas-liquid two-phase flow under flexible input pressure conditions.

[0012] In summary, given the complex flow patterns and unique properties of low-temperature gas-liquid two-phase flows, and the superiority of ECT in phase distribution identification, it is necessary to design a two-phase flow measurement sensor that couples phase distribution. Summary of the Invention

[0013] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a two-phase flow measurement sensor with coupled phase distribution. This sensor measures the capacitance between pairs of electrode plates in the upstream and downstream flexible measuring electrode arrays, transmits the data to a host computer, and uses a corresponding inversion algorithm to reconstruct the phase distribution images of the corresponding locations within the measuring pipe. By combining the phase distribution information of the two-phase flow at the upstream and downstream sensors, a cross-correlation function is calculated to obtain the flow velocity. This sensor is non-invasive, can accurately obtain the two-phase flow rate without affecting the flow regime, and can obtain the phase distribution inversion image in real time.

[0014] According to a first aspect of the present invention, the present invention provides a two-phase flow measurement sensor with coupled phase distribution, comprising an insulated measuring pipe, a flange, a flexible circuit board, an insulating sleeve, and a shielding cover; The insulating measuring pipe is a cylindrical pipe with both ends open; The flanges are located at both ends of the insulating measuring pipe and are coaxially fitted. They can move axially along the insulating measuring pipe and rotate circumferentially to connect and seal with external pipes. The flexible circuit board is detachably fixed to the outer peripheral wall of the insulated measuring pipe, uniformly and tightly attached to the outer surface of the insulated measuring pipe. The flexible circuit board includes a flexible measuring electrode array, a flexible axial shielding ring, and a flexible circuit insulation layer. First, a flexible circuit insulation layer is set on the outer wall surface of the insulated measuring pipe. Then, a flexible axial shielding ring is set on the flexible circuit insulation layer at the center position of the insulated measuring pipe. Then, with the flexible axial shielding ring as the axis of symmetry, a set of flexible measuring electrode arrays is symmetrically set at both ends. Then, a flexible axial shielding ring is set at the unshielded end of each of the two sets of flexible measuring electrode arrays, so that the axial distance from each flexible axial shielding ring to the end of the adjacent flexible measuring electrode array is the same. The insulating sleeve is detachably coaxially fitted with the insulated measuring pipe after the flexible circuit board is fixed. The shielding cover is detachably fixed to the outer peripheral wall of the insulating sleeve, uniformly covering the outer surface of the insulating sleeve.

[0015] According to a preferred embodiment of the present invention, the two flexible measuring electrode arrays are identical, each flexible measuring electrode array comprising the same eight rectangular electrode plates, the rectangular electrode plates being arranged at equal intervals along the circumference of the insulated measuring pipe; The circumferential coverage of the flexible measurement electrode array is 0.75~0.85, and the circumferential width of each rectangular electrode sheet is... ,in This refers to the circumferential coverage of the electrodes. For the number of electrodes, For measuring the diameter of insulated pipes; The axial length of the rectangular electrode sheet in the flexible measuring electrode array is , For measuring the diameter of an insulating pipe.

[0016] Furthermore, the flexible axial shielding ring is an annular electrode sheet with a circumferential length equal to the outer perimeter of the cross-section of the insulated measuring pipe and an axial width equal to the circumferential width of the rectangular electrode sheet of the flexible measuring electrode array.

[0017] Furthermore, each electrode in the flexible measurement electrode array has a pad on its top layer for electrical connection with an external coaxial shield.

[0018] Furthermore, the flexible axial shielding ring is electrically connected to the shielding cover by welding wires.

[0019] Furthermore, the flexible measuring electrode array, flexible axial shielding ring, and flexible circuit insulation layer integrated in the flexible circuit board present a dual-capacitance tomography sensor structure. Within one measurement cycle of each flexible measuring electrode array, an excitation voltage is sequentially applied to eight electrode plates within it. When any electrode plate becomes the excitation electrode, the remaining seven electrode plates sequentially switch to detection electrodes. The detection electrode and the excitation electrode form a measuring electrode pair. The six electrodes outside the measuring electrode pair are grounded, and the effective capacitance value between the measuring electrode pairs is measured. That is, one measurement cycle acquires a total of one [value missing]. =Capacitance vector of 28 independent capacitors According to a second aspect of the present invention, the present invention also provides a two-phase flow meter system with coupled phase distribution, comprising a capacitance signal acquisition unit, a host computer, and the aforementioned two-phase flow measurement sensor with coupled phase distribution. The two-phase flow measurement sensor with coupled phase distribution is connected to the capacitance signal acquisition unit via a coaxial shielded cable, and the capacitance signal acquisition unit is connected to the host computer. The capacitance signal acquisition unit is used to measure the effective capacitance value between each electrode plate and transmit it to the host computer. The host computer is used to process the capacitance data and calculate the real-time phase distribution and flow rate.

[0020] According to a third aspect of the present invention, the present invention provides a two-phase flow rate measurement method based on the aforementioned system, comprising the following steps: 1) Let the two-phase flow to be measured flow through the insulated measuring pipe of the two-phase flow measurement sensor with the coupled phase distribution; 2) Within one measurement cycle of each flexible measurement electrode array, the capacitance signal acquisition unit sequentially applies excitation voltage to the eight electrode plates of the flexible measurement electrode array. When any electrode plate becomes the excitation electrode, the remaining seven electrode plates sequentially switch to detection electrodes, forming a measurement electrode pair with the excitation electrode. The six electrodes outside the measurement electrode pair are grounded, and the effective capacitance value between the measurement electrode pairs is measured. Let the signal acquisition time step be one measurement cycle of the flexible measurement electrode array, then each flexible measurement electrode array acquires a signal containing... =28 effective capacitance values ​​are used as the capacitance signal; 3) The capacitance signal acquisition unit transmits the capacitance signals acquired by the flexible measuring electrode arrays located upstream and downstream to the host computer in real time; the host computer calculates the instantaneous mass flow rate of the two-phase flow to be measured.

[0021] Furthermore, the host computer processes the capacitance signal based on the inversion algorithm, reconstructs the real-time distribution of gas and liquid phases at the corresponding cross-sections of the flexible measuring electrode arrays upstream and downstream of the pipeline, and calculates the volume fraction distribution information; performs cross-correlation analysis on the image sequences corresponding to the real-time phase distributions of the upstream and downstream cross-sections to obtain the axial velocity field of the two-phase flow; integrates the volume fraction distribution and velocity field on the cross-section, and combines the temperature and density models to directly calculate the instantaneous mass flow rate.

[0022] The beneficial effects that this invention can produce include: (1) The two-phase flow measurement sensor with coupled phase distribution provided by the present invention has a flexible circuit board that integrates measuring electrodes, shielding rings and insulating layers, and the shielding cover is directly covered on the outside. The sensor is quick and easy to assemble. It only needs to connect the flexible circuit board and the coaxial shielding wire and the shielding cover and fix them to the outer periphery of the insulated measuring pipe. It is especially suitable for on-site installation and debugging of low temperature sensors in application scenarios.

[0023] (2) The two-phase flow measurement sensor with coupled phase distribution provided by the present invention uses standardized multilayer PCB design and manufacturing technology for its flexible circuit board. The wiring and layout are symmetrical, which effectively reduces the discrete differences between different circuit boards, reduces the debugging when replacing circuit boards, and reduces the cost of using the sensor.

[0024] (3) The two-phase flow measurement sensor with coupled phase distribution provided by the present invention uses an integrated design for the flexible circuit board, and the wires are internal traces of the flexible circuit board, which reduces the connection steps in the manufacturing, installation and use process and effectively reduces sensor noise.

[0025] (4) The two-phase flow measurement sensor with coupled phase distribution provided by the present invention has internal components that can be easily and repeatedly installed, and the arrangement of the internal flexible electrode array can be adjusted according to the application scenario.

[0026] (5) The two-phase flow measurement sensor with coupled phase distribution provided by the present invention can effectively avoid the wrinkling of electrodes in low-temperature application scenarios.

[0027] (6) The two-phase flow measurement sensor with coupled phase distribution provided by the present invention organically combines ECT technology and cross-correlation velocity measurement method. It can obtain the flow field velocity by comparing the time difference of upstream and downstream sensor capacitance signals while obtaining the inversion image of low temperature gas and liquid two-phase flow in real time, thereby solving the problem of accurate and rapid measurement of low temperature two-phase flow. Attached Figure Description

[0028] Figure 1 This is an isometric view of the two-phase flow measurement sensor with coupled phase distribution according to the present invention.

[0029] Figure 2 This is a front view of the two-phase flow measurement sensor with coupled phase distribution according to the present invention.

[0030] Figure 3 This is a cross-sectional view of the two-phase flow measurement sensor with coupled phase distribution according to the present invention.

[0031] Figure 4 This is a CC cross-sectional view of the two-phase flow measurement sensor with coupled phase distribution according to the present invention.

[0032] Figure 5 This is an isometric view of the flexible measuring electrode array, flexible axial shielding ring, and flexible circuit insulation layer in the two-phase flow measurement sensor with coupled phase distribution of the present invention.

[0033] Figure 6 This is an isometric view of the flexible circuit insulation layer in the two-phase flow measurement sensor with coupled phase distribution of the present invention.

[0034] Figure 7 This is an isometric view of the shielding cover in the two-phase flow measurement sensor with coupled phase distribution of the present invention.

[0035] In the diagram: 1. Insulated measuring pipe, 2. Flange, 3. Flexible circuit board, 301. Flexible measuring electrode array, 302. Flexible axial shielding ring, 303. Flexible circuit insulation layer, 4. Insulating sleeve, 5. Shielding cover. Detailed Implementation

[0036] The invention will now be further described with reference to the accompanying drawings.

[0037] like Figures 1 to 7 As shown, in one specific embodiment of the present invention, an 8-electrode capacitance tomography method is employed. The insulating measurement pipe is made of plexiglass, and the cryogenic working fluid is saturated liquid nitrogen-nitrogen gas at 1 atm (77K).

[0038] like Figure 1 and 2 As shown, the main structure of the two-phase flow measurement sensor with coupled phase distribution of the present invention is an insulated measuring pipe 1; each end of the insulated measuring pipe 1 has a flange 2, which can move axially along the insulated measuring pipe 1 and rotate circumferentially to connect and seal with an external pipe; an insulated sleeve 4 is coaxially fitted with the insulated measuring pipe 1 at the corresponding position of the fluid measuring section, and covers the flexible circuit board 3 on the surface of the insulated measuring pipe; a shielding cover 5 is fixed outside the insulated sleeve 4 and covers the entire fluid measuring section to shield external noise.

[0039] like Figure 3 As shown, the flexible circuit board 3 is fixed to the outer periphery of the insulating measuring pipe 1, and is divided into two layers from the inner side close to the insulating measuring pipe 1 to the outer side. The first layer is as follows: Figure 6 As shown, this is the flexible circuit insulating layer 303; the second layer is as follows: Figure 5As shown, there are two flexible measurement electrode arrays 301 and flexible axial shielding rings 302. Each flexible measurement electrode array 301 contains eight identical rectangular electrode pieces (matching an 8-electrode capacitance tomography imaging method). The rectangular electrode pieces are arranged at equal intervals along the circumference of the insulated measurement pipe. The two sets of flexible measurement electrode arrays 301 serve as upstream and downstream phase distribution sensors, respectively. Three flexible axial shielding rings 302 are respectively located in the middle and at both ends of the two sets of flexible measurement electrode arrays 301, serving to reduce edge effects. A flexible circuit insulation layer 303 separates the two sets to ensure electrical isolation. The insulating sleeve 4 consists of insulating supports at both ends and an acrylic tube. The insulating supports are coaxially fitted with the insulated measurement pipe 1 and fix the flexible circuit board 3, which is tightly attached to the outer circumference of the insulated measurement pipe. The shielding cover 5 is as follows... Figure 7 As shown, the material is copper, and it is covered with an insulating sleeve 4 and fixed.

[0040] like Figure 4 As shown, flange 2 is coaxially fitted with insulating measuring pipe 1, flexible circuit board 3 is fixed to the outer periphery of insulating measuring pipe 1, and its exterior is surrounded by insulating sleeve 4, and shielding cover 5 is fixed to the outer periphery of insulating sleeve 4.

[0041] Specifically, for standard capacitance tomography applications, the circumferential coverage of the flexible measurement electrode array 301 is 0.75~0.85, and the circumferential width of each electrode is... ,in This refers to the circumferential coverage of the electrodes. For the number of electrodes, The diameter of pipe 1 is measured for insulation.

[0042] Specifically, for standard capacitance tomography applications, the electrode length of the flexible measurement electrode array 301 is... To reduce the edge effect of the electrode, The diameter of pipe 1 is measured for insulation.

[0043] Within one measurement cycle of each flexible measurement electrode array, the present invention sequentially applies an excitation voltage to eight electrode plates within it. When any electrode plate becomes the excitation electrode, the remaining seven electrode plates sequentially switch to detection electrodes. The detection electrode and the excitation electrode form a measurement electrode pair, and the six electrodes outside the measurement electrode pair are grounded. The effective capacitance value between the measurement electrode pairs is measured; that is, one measurement cycle acquires a total of one... =The capacitance vector of 28 independent capacitors is used as the capacitance signal.

[0044] like Figure 1 and Figure 5As shown, when measuring the flow rate, a two-phase flow of saturated liquid nitrogen-nitrogen gas (77K) at 1 atm is made to flow uniformly through the insulated measuring pipe 1. The flexible measuring electrode array 301 near the inflow side is used as the upstream phase distribution sensor, and the one near the outflow side is used as the downstream phase distribution sensor. The upstream and downstream phase distribution sensors record the capacitance data of the fluid cross section at each time step according to a certain time step. The data is transmitted to the host computer through the capacitance signal acquisition unit. The phase distribution information at that time is generated by the inversion algorithm and imaged. The reconstructed image sequence corresponding to the phase distribution information that changes with time can be used as the basic signal for the next step of velocity calculation.

[0045] Specifically, the host computer processes the capacitance signal based on the inversion algorithm, reconstructs the real-time distribution of gas and liquid phases at the corresponding cross-sections of the upstream and downstream sensors in the pipeline, and calculates the volume fraction distribution information; performs cross-correlation analysis on the image sequences corresponding to the real-time phase distributions of the upstream and downstream cross-sections to obtain the axial velocity field of the two-phase flow; integrates the volume fraction distribution and velocity field on the cross-section, and combines the temperature and density models to directly calculate the instantaneous mass flow rate.

[0046] As fluid flows past the upstream and downstream sensors, due to instabilities in the two-phase flow (such as changes in bubble distribution or local volume fraction), the image sequence signals recorded by the two sensors will exhibit similarity and time delay. The fluctuation characteristics of the signal are known as the cross-correlation, and the degree of correlation can be described by the cross-correlation function: (1) In the formula: for Image sequence signal values ​​recorded by the upstream sensor at any given time. for The image sequence signal value recorded by the downstream sensor at a given time is the image sequence (vector) reconstructed based on the phase distribution at the corresponding cross-section at the corresponding time. This image sequence can be obtained by dividing the reconstructed image of that frame into several radial × axial blocks or pixel windows (ROIs). This is achieved through calculation... By determining the peak position, the time delay corresponding to the maximum correlation between signals can be obtained. This can be considered as the time it takes for the same fluid to move from one sensor to another. The distance between sensors... Given the information, the flow velocity can be calculated: (2) After obtaining the flow rate, the volume fraction distribution can be obtained from the phase distribution information recorded by the sensor, and the density can be calculated from the temperature model. The instantaneous mass flow rate can then be obtained by integration.

[0047] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A two-phase flow measurement sensor with coupled phase distribution, characterized in that, include: Insulated measuring pipe (1), flange (2), flexible circuit board (3), insulating sleeve (4) and shielding cover (5); The insulating measuring pipe (1) is a cylindrical pipe with both ends open; The flange (2) is provided at both ends of the insulating measuring pipe (1) and is coaxially fitted. It can move axially along the insulating measuring pipe (1) and rotate circumferentially to connect and seal with external pipes. The flexible circuit board (3) is detachably fixed to the outer peripheral wall of the insulating measuring pipe (1) and is uniformly and tightly attached to the outer surface of the insulating measuring pipe (1); the flexible circuit board (3) includes a flexible measuring electrode array (301), a flexible axial shielding ring (302), and a flexible circuit insulation layer (303); a flexible circuit insulation layer (303) is first set on the outer wall surface of the insulating measuring pipe (1), and then a flexible axial shielding ring (302) is set on the flexible circuit insulation layer (303) at the center position of the insulating measuring pipe (1). 2); Then, with the flexible axial shielding ring (302) as the axis of symmetry, a set of flexible measuring electrode arrays (301) are symmetrically arranged at both ends, and a flexible axial shielding ring (302) is arranged at the unshielded end of each of the two sets of flexible measuring electrode arrays (301), so that the axial distance from each flexible axial shielding ring (302) to one end of the adjacent flexible measuring electrode array (301) is the same; the insulating sleeve (4) is detachably coaxially fitted with the insulating measuring pipe (1) after fixing the flexible circuit board (3) externally; The shield (5) is detachably fixed to the outer peripheral wall of the insulating sleeve (4) and uniformly covers the outer surface of the insulating sleeve (4).

2. The two-phase flow measurement sensor with coupled phase distribution as described in claim 1, characterized in that, The two flexible measuring electrode arrays (301) are identical, each containing the same eight rectangular electrode plates, which are arranged at equal intervals along the circumference of the insulated measuring pipe; The circumferential coverage of the flexible measurement electrode array (301) is 0.75~0.85, and the circumferential width of each rectangular electrode sheet is... ,in This refers to the circumferential coverage of the electrodes. For the number of electrodes, For measuring the diameter of insulated pipes; The axial length of the rectangular electrode sheet in the flexible measurement electrode array (301) is , For measuring the diameter of an insulating pipe.

3. The two-phase flow measurement sensor with coupled phase distribution as described in claim 1, characterized in that, The flexible axial shielding ring (302) is an annular electrode sheet with a circumferential length equal to the outer perimeter of the cross-section of the insulated measuring pipe (1) and an axial width equal to the circumferential width of the rectangular electrode sheet of the flexible measuring electrode array (301).

4. The two-phase flow measurement sensor with coupled phase distribution as described in claim 1, characterized in that, Each electrode in the flexible measurement electrode array (301) has a pad on its top layer for electrical connection with an external coaxial shield.

5. The two-phase flow measurement sensor with coupled phase distribution as described in claim 1, characterized in that, The flexible axial shielding ring (302) is electrically connected to the shielding cover (5) by welding with a wire.

6. The two-phase flow measurement sensor with coupled phase distribution as described in claim 1, characterized in that, The flexible circuit board (3) integrates a flexible measurement electrode array (301), a flexible axial shielding ring (302), and a flexible circuit insulation layer (303), presenting a dual capacitance tomography (ECT) sensor structure. Within one measurement cycle of each flexible measuring electrode array, an excitation voltage is sequentially applied to eight electrode plates within it. When any electrode plate becomes the excitation electrode, the remaining seven electrode plates sequentially switch to detection electrodes. The detection electrode and the excitation electrode form a measuring electrode pair. The six electrodes outside the measuring electrode pair are grounded, and the effective capacitance value between the measuring electrode pairs is measured. That is, one measurement cycle acquires a total of one [value missing]. =A capacitance vector of 28 independent capacitors.

7. A two-phase flow meter system with coupled phase distribution, characterized in that, The device includes a capacitance signal acquisition unit, a host computer, and a two-phase flow measurement sensor with coupled phase distribution as described in any one of claims 1-6. The two-phase flow measurement sensor with coupled phase distribution is connected to the capacitance signal acquisition unit via a coaxial shielded cable, and the capacitance signal acquisition unit is connected to the host computer. The capacitance signal acquisition unit is used to measure the effective capacitance value between each electrode plate and transmit it to the host computer. The host computer is used to process the capacitance data and calculate the real-time phase distribution and flow rate.

8. A method for measuring the flow rate of a two-phase flow based on the system of claim 7, characterized in that, Includes the following steps: 1) Let the two-phase flow to be measured flow through the insulated measuring pipe of the two-phase flow measurement sensor with the coupled phase distribution; 2) Within one measurement cycle of each flexible measurement electrode array, the capacitance signal acquisition unit sequentially applies excitation voltage to the eight electrode plates of the flexible measurement electrode array. When any electrode plate becomes the excitation electrode, the remaining seven electrode plates sequentially switch to detection electrodes, forming a measurement electrode pair with the excitation electrode. The six electrodes outside the measurement electrode pair are grounded, and the effective capacitance value between the measurement electrode pairs is measured. Let the signal acquisition time step be one measurement cycle of the flexible measurement electrode array, then each flexible measurement electrode array acquires a signal containing... =28 effective capacitance values ​​are used as the capacitance signal; 3) The capacitance signal acquisition unit transmits the capacitance signals acquired by the flexible measuring electrode arrays located upstream and downstream to the host computer in real time; 4) The host computer processes the capacitance signal based on the inversion algorithm, reconstructs the real-time distribution of gas and liquid phases at the corresponding positions of the flexible measuring electrode arrays in the upstream and downstream of the pipeline, and calculates the volume fraction distribution information; performs cross-correlation analysis on the image sequences corresponding to the real-time phase distribution of the upstream and downstream sections to obtain the axial velocity field of the two-phase flow; integrates the volume fraction distribution and velocity field on the cross section, and combines the temperature and density models to directly calculate the instantaneous mass flow rate.

Images