An irregular impedance cavitator and calibration method

Abstract

The present invention discloses a special-shaped impedance void meter and a calibration method, which relate to the field of nuclear energy technology. The principle of the special-shaped impedance void meter proposed in this solution is that two symmetric impedance void components are powered on, and the two symmetric impedance void components respectively correspond to the transmitting electrode and the receiving electrode of the calibration device. The special-shaped impedance void meter is applicable to the full flow regime range from bubbly flow to annular flow, can be applicable in the full flow regime range, and can conveniently measure the void fraction in the spiral cross rod bundle channel, providing a database for establishing a flow regime transition model and a drift flow model. The calibration method of this solution can conveniently and accurately calibrate the special-shaped impedance void meter, and the calibration curve is obtained by fitting the void fraction - dimensionless voltage change characteristic diagram. This special-shaped impedance void meter has a wide range of applications, can realize the measurement of the void fraction in the spiral cross rod bundle channel in the full flow regime range, is convenient to calibrate, has a high calibration accuracy, and is simple to operate.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear energy, and specifically relates to a special-shaped impedance void meter and a calibration method. Background Technique

[0002] Nuclear energy is an important clean energy source, which is widely used in power generation, heating, seawater desalination, hydrogen production, etc. Especially in power generation, it has the characteristics of cleanliness, high efficiency and stability. For decades, the improvement of reactor fuel assemblies has been developing in the direction of changing geometric structures and dimensions. The spiral cross fuel is a relatively excellent fuel type. Although there is no positioning grid in the spiral cross rod bundle channel, it is still a highly heterogeneous and complex channel, and the cross flow and secondary flow generated by the internal flow mixing will exacerbate the complexity of the interface transport mechanism. The void fraction is one of the most important parameters in gas-liquid two-phase flow. For the calculation of the two-phase flow pressure drop, it is the parameter that needs to be obtained first, and it has a great influence on boiling heat transfer.

[0003] Traditional impedance void fraction meters are generally in the shape of a flat plate or a ring and are embedded in the flow channel wall or the rod wall. For example, Chen et al. (Chen S-W, Ruan P-S, Lin M-S, et al. Experimental investigation on local / global void distribution of air-water two-phase flow in a 3 × 3 rod bundle channel under low-flow conditions [J]. International Journal of Heat and Fluid Flow, 2020, 85: 108623.), Ye et al. (Ye T-p, Pan L-m, Ren Q-y, et al. Experimental study on distribution parameter characteristics in vertical rod bundles [J]. International Journal of Heat and Mass Transfer, 2019, 132: 593-605.), and Wan et al. (Wan J, Gao L, Sun W, et al. Experimental investigation on effect of rod bowing on subchannel void fraction in 5 × 5 rod bundles [J]. Progress in Nuclear Energy, 2024, 170: 105125.) used flat impedance void fraction meters or subchannel impedance void fraction meters to measure the average void fraction in the flow channel. When studying the two-phase phase distribution in the rod bundle channel, the central part of the core component is generally taken as the research object, which makes it necessary to retain the shape of a part of the fuel rods on the flow channel wall. Therefore, in the helical cross-rod bundle channel, the impedance void fraction meter is a special-shaped impedance void fraction meter with a helical cross-fuel structure.

[0004] The object of the present invention is to overcome the shortcomings of the above-mentioned existing experimental measurement device design, design a special-shaped impedance void fraction meter capable of measuring the average void fraction in the helical cross-rod channel, and at the same time provide a calibration method for the special-shaped impedance void fraction meter to improve the experimental measurement accuracy, and provide a rich experimental database for establishing a flow pattern transition model and a drift flow model applicable to the helical cross-rod bundle channel.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] To solve the above technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0007] A special-shaped impedance cavitometer, comprising:

[0008] A sleeve;

[0009] A number of spiral cross rod bundles, which are commonly arranged through the inner wall of the sleeve;

[0010] A number of impedance cavitation components are symmetrically arranged on both sides of the sleeve. The two symmetric impedance cavitation components are respectively the transmitting end and the receiving end, and the transmitting end and the receiving end respectively generate an alternating voltage and receive the corresponding electric potential;

[0011] The impedance cavitation component is hermetically penetrated by a first wire, and the first wire is electrically connected to the impedance cavitation component;

[0012] The impedance cavitation component includes an insulating support seat communicated with the inner wall of the sleeve. A fitting groove is formed on the inner wall of the insulating support seat, and an electrode module is hermetically fitted on the inner wall of the fitting groove. An installation seat is fixed on one side of the insulating support seat, and installation screws for fixing one side of the sleeve are arranged at the four corners of the installation seat.

[0013] Preferably, a number of sealing grooves are symmetrically formed on both sides of the sleeve, the insulating support seat is hermetically fitted on the inner wall of the sealing groove, and the installation seat is used for sealing and maintaining one side of the sealing groove.

[0014] Preferably, both ends of the sleeve are in a penetrating state, and the inner wall of the sleeve has the same shape as that of the spiral cross rod bundle.

[0015] Preferably, the electrode module has the same shape as the inner wall of the sleeve, and one side of the electrode module is electrically connected to the first wire.

[0016] Preferably, a calibration method for a special-shaped impedance cavitometer includes the following steps:

[0017] S1. The special-shaped impedance cavitometer replicates and prepares a calibration device in proportion, and establishes a cavitometer calibration system based on the calibration device;

[0018] S2. Measure the receiving electrode voltages V f and V g under the full liquid phase and full gas phase conditions of the calibration device respectively;

[0019] S3. Prepare a number of high-precision small balls to simulate the bubbles of the special-shaped impedance cavitometer. Put an appropriate amount of high-precision small balls into the calibration device, record the number of high-precision small balls with different diameters put into the calibration device, and calculate the total volume Vo sp, obtain the actual void fraction :

[0020] ;

[0021] Among them, Vo to is the total volume of the fluid domain between the two electrode modules;

[0022] S4. Fill the calibration device with water, record the voltage V measured by the receiving electrode at this time, and obtain the dimensionless voltage corresponding to the void fraction :

[0023] ;

[0024] S5. Change the number or size of the high-precision small balls, but the void fraction should remain unchanged. Repeat steps S3 to S4 to measure the actual void fraction and the dimensionless voltage ;

[0025] S6. Change the number or size of the high-precision small balls to change the void fraction . Repeat steps S3, S4, and S5. In this step, the void fraction is uniformly controlled to vary between 0 and 1;

[0026] S7. Plot the void fraction-dimensionless voltage variation characteristic diagram and perform polynomial fitting:

[0027] ;

[0028] Among them, a i are the polynomial coefficients respectively, i = 0, 1, 2, 3,... n;

[0029] S8. According to the void fraction-dimensionless voltage variation characteristic diagram, the calibration curve of the special-shaped impedance void meter is obtained through polynomial fitting:

[0030] - - + + .

[0031] Preferably, in S5, the multiple measurements are at least three times to eliminate the influence of random errors.

[0032] Preferably, the void meter calibration system includes a calibration device, the calibration device is electrically connected to a signal amplification circuit board, the signal amplification circuit board is electrically connected to a data collector, and the data collector is electrically connected to a computer.

[0033] Preferably, the diameter of the high-precision small ball is 1 - 6 mm, and the high-precision small ball is made of materials with low electrical conductivity and low relative dielectric constant, including POM engineering plastics or zirconia ceramics.

[0034] Preferably, the calibration device includes a calibration seat that is replicated in proportion to the casing. The inner wall of the calibration seat is provided with a transmitting electrode and a receiving electrode. Both the transmitting electrode and the receiving electrode are electrically connected to a second wire, and the second wire is hermetically penetrated through one side of the calibration seat. The inner wall of the calibration seat is provided with a number of rod bundle substrates that are replicated in proportion to the spiral cross rod bundle.

[0035] Preferably, the rod bundle substrate material and the calibration seat include high-toughness resin or acrylic, and both the first wire and the second wire are shielded coaxial cables.

[0036] Beneficial effects:

[0037] The principle of the special-shaped impedance void meter proposed in this solution is that two symmetric impedance void components are powered on. The two symmetric impedance void components respectively correspond to the transmitting electrode and the receiving electrode of the calibration device. The transmitting electrode and the receiving electrode are connected to the excitation circuit and the receiving circuit of the signal amplification circuit board. An alternating voltage is input to the transmitting electrode. According to the electrical conductivity difference between the gas-liquid two-phase, the receiving electrode will generate a corresponding electric potential. The special-shaped impedance void meter of this solution is applicable to the full flow pattern range from bubbly flow to annular flow, can be applied in the full flow pattern range, and can conveniently measure the void fraction in the spiral cross rod bundle channel, providing a database for establishing a flow pattern transition model and a drift flow model;

[0038] This solution designs a calibration method for the special-shaped impedance void meter. This method can conveniently and accurately calibrate the special-shaped impedance void meter, and the calibration curve is obtained by fitting the void fraction - dimensionless voltage change characteristic diagram;

[0039] In summary, the special-shaped impedance void meter of this invention has a wide range of applications, can measure the void fraction in the spiral cross rod bundle channel in the full flow pattern range, is convenient to calibrate, has a high calibration accuracy, and is easy to operate.

[0040] The following further describes in detail the specific implementation manners of the present invention with reference to the accompanying drawings. Description of the Drawings

[0041] In the drawings:

[0042] Figure 1 is a three-dimensional structural schematic diagram of the special-shaped impedance void meter of the present invention;

[0043] Figure 2 is a three-dimensional sectional structural schematic diagram of the special-shaped impedance void meter of the present invention;

[0044] Figure 3 This is a schematic cross-sectional structure diagram of the special-shaped impedance cavitometer of the present invention in another direction;

[0045] Figure 4 This is a schematic structure diagram of the explosion of the special-shaped impedance cavitometer of the present invention;

[0046] Figure 5 This is a schematic structure diagram of the explosion of the impedance cavitation component of the present invention;

[0047] Figure 6 This is a schematic cross-sectional structure diagram of the special-shaped impedance cavitometer of the present invention;

[0048] Figure 7 This is a schematic structure diagram of the cavitometer calibration system of the present invention;

[0049] Figure 8 This is a three-dimensional schematic structure diagram of the calibration device of the present invention;

[0050] Figure 9 This is an operation schematic diagram of the calibration device of the present invention;

[0051] Figure 10 This is a calibration result curve graph of the special-shaped impedance cavitometer obtained by fitting the cavitation fraction - non-dimensional voltage change characteristic graph of the present invention.

[0052] In the figure: 1. Sleeve; 2. Spiral cross rod bundle; 3. Impedance cavitation component; 31. Mounting seat; 32. Insulating support seat; 33. Fitting groove; 34. Electrode module; 35. Mounting screw; 4. First wire; 5. Sealing groove; 6. Computer; 7. Calibration device; 71. Calibration seat; 72. Rod bundle base; 73. Transmitting electrode; 74. Receiving electrode; 75. Second wire; 8. Signal amplification circuit board; 9. Data collector. Detailed implementation method

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments in conjunction with the accompanying drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention.

[0054] The technical key point of the present invention lies in inventing a special-shaped impedance cavitometer for measuring the cavitation fraction in the spiral cross rod bundle channel and giving a calibration method therefor.

[0055] As Figures 1 to 10 shown:

[0056] A calibration method for a special-shaped impedance cavitometer includes the following steps:

[0057] S1. Connect the calibration device 7, the signal amplification circuit board 8, the data acquisition card, and the computer 6 together through a wire with a shielding function to establish a cavitometer calibration system;

[0058] S2. Measure the voltages V f and V g of the receiving electrode 74 under the conditions of full liquid phase and full gas phase of the calibration device 7 respectively;

[0059] S3. Prepare an appropriate number of high-precision small balls respectively to simulate the bubbles passing through the special-shaped impedance cavitometer, with diameters ranging from 1 mm to 6 mm. The materials of the high-precision small balls should have the characteristics of low conductivity and low relative dielectric constant, such as POM engineering plastics or zirconia ceramics. Put an appropriate amount of high-precision small balls into the calibration device 7, record the number of high-precision small balls with different diameters placed in the calibration device 7, and calculate the total volume Vo sp of all high-precision small balls to obtain the actual void fraction :

[0060] ;

[0061] where Vo to is the total volume of the fluid domain between the two electrode modules 34;

[0062] S4. Fill the calibration device 7 with water, record the voltage V measured by the receiving electrode 74 at this time, and obtain the dimensionless voltage corresponding to the void fraction :

[0063] ;

[0064] S5. Change the number or size of the high-precision small balls, but keep the void fraction unchanged, and repeat steps S3 to S4 to measure the actual void fraction and the dimensionless voltage (this step should be repeated at least three times to eliminate the influence of random errors);

[0065] S6. Change the number or size of the high-precision small balls to make the void fraction change, and repeat steps S3, S4 and S5. In this step, the void fraction is uniformly controlled to vary between 0 and 1;

[0066] S7. Plot the void fraction-dimensionless voltage variation characteristic diagram and perform polynomial fitting:

[0067] ;

[0068] where a i are the polynomial coefficients respectively, i = 0, 1, 2, 3,...n;

[0069] S8. According to the void fraction - dimensionless voltage variation characteristic diagram, the calibration curve of the special-shaped impedance void meter was obtained by polynomial fitting:

[0070] - - + + 。

[0071] Specifically, as Figure 8 shown: The calibration device 7 includes a calibration seat 71 replicated in equal proportion to the casing 1. The inner wall of the calibration seat 71 is provided with a transmitting electrode 73 and a receiving electrode 74. Both the transmitting electrode 73 and the receiving electrode 74 are electrically connected to a second wire 75. The second wire 75 is hermetically penetrated through one side of the calibration seat 71. The inner wall of the calibration seat 71 is provided with a number of rod bundle substrates 72 replicated in equal proportion to the spiral cross rod bundle 2.

[0072] The calibration device 7 replicates the local structure of the special-shaped impedance void meter one-to-one. The calibration device 7 needs to ensure that all dimensions are the same as those of the original special-shaped impedance void meter, which can guarantee the accuracy and high precision of the calibration data.

[0073] The material of the rod bundle substrate 72 and the calibration seat 71 includes high-toughness resin or acrylic. The first wire 4 and the second wire 75 are both shielded coaxial cables.

[0074] The signal amplification circuit board 8 can generate an AC voltage with an excitation frequency of 100 kHz and 5 V, and internally includes a low-pass filter and an operational amplifier circuit.

[0075] The principle of the special-shaped impedance void meter proposed in this solution is that two symmetric impedance void components 3 are powered on. The two symmetric impedance void components 3 respectively correspond to the transmitting electrode 73 and the receiving electrode 74 of the calibration device 7. The transmitting electrode 73 and the receiving electrode 74 are connected to the excitation circuit and the receiving circuit of the signal amplification circuit board 8 together. An AC voltage is input to the transmitting electrode 73. According to the conductivity difference between the gas-liquid two-phase, the receiving electrode 74 will generate a corresponding electric potential. The current signal is electrically connected to the signal amplification circuit board 8 through the second wire 75. The output of the signal amplification circuit board 8 is communicatively connected to the data acquisition card, and the data collected by the data acquisition card is transmitted to the computer 6 for storage. The special-shaped impedance void meter of this solution is applicable to the full flow pattern range from bubbly flow to annular flow, can be applied in the full flow pattern range, and can conveniently measure the void fraction in the spiral cross rod bundle 2 channels, providing a database for establishing a flow pattern transition model and a drift flow model.

[0076] As Figures 1 to 6 shown: A special-shaped impedance void meter includes a number of spiral cross rod bundles 2, which are commonly arranged through the inner wall of the casing 1;

[0077] On both sides of the casing 1, a number of impedance bubble components 3 are symmetrically arranged. The two symmetrical impedance bubble components 3 are respectively the transmitting end and the receiving end, and the transmitting end and the receiving end respectively generate an alternating voltage and receive the corresponding electric potential.

[0078] A first wire 4 is hermetically penetrated through the impedance bubble component 3, and the first wire 4 is electrically connected to the impedance bubble component 3.

[0079] The impedance bubble component 3 includes an insulating support base 32 communicated with the inner wall of the casing 1. A fitting groove 33 is formed on the inner wall of the insulating support base 32, and an electrode module 34 is hermetically fitted to the inner wall of the fitting groove 33. An installation base 31 is fixed on one side of the insulating support base 32, and installation screws 35 for fixing one side of the casing 1 are arranged at the four corners of the installation base 31.

[0080] To prevent water leakage, the surfaces of the first wire 4 and the second wire 75 are preferably sealed with Kraft sealant.

[0081] The above-mentioned special-shaped impedance bubble instrument is applicable to the full flow pattern range from bubbly flow to annular flow, with a liquid phase flow rate of 0 - 2.5 m / s and a gas phase flow rate of 0 - 10.5 m / s.

[0082] Specifically, as Figure 4 shown: A number of sealing grooves 5 are symmetrically formed on both sides of the casing 1. The insulating support base 32 is hermetically fitted to the inner wall of the sealing groove 5, and the installation base 31 is used for sealing and maintaining one side of the sealing groove 5.

[0083] The sealing groove 5 can maintain the sealing performance of the installation of the installation base 31 and can effectively prevent the internal water body from leaking.

[0084] Specifically, as Figure 2 shown: Both ends of the casing 1 are in a penetrating state, and the inner wall of the casing 1 has the same shape as the spiral cross rod bundle 2.

[0085] The fact that the inner wall of the casing 1 has the same shape as the spiral cross rod bundle 2 can ensure the uniformity of the internal environment.

[0086] Specifically, as Figure 5 shown: The electrode module 34 has the same shape as the inner wall of the casing 1, and one side of the electrode module 34 is electrically connected to the first wire 4.

[0087] In the above solution, the materials of the transmitting electrode 73 and the receiving electrode 74 are stainless steel, and additive manufacturing technology is adopted. The spiral cross rod bundle 2 and the casing 1 are made of insulating materials, such as acrylic or high-toughness resin. The first wire 4, the second wire 75 or other electrical connections all need to have shielding properties to shield electromagnetic interference, such as shielded coaxial cables.

[0088] This solution precisely designs and implements a calibration method for a special-shaped impedance void meter. This method establishes a calibration system, measures the voltage of the receiving electrode 74 under full liquid phase and full gas phase conditions respectively, uses high-precision small balls to simulate bubbles with different void fractions, records and calculates the relationship between the void fraction and the dimensionless voltage, and obtains the calibration curve.

[0089] First, by using high-precision small balls to simulate bubbles, the accuracy of the measurement data and the reliability of the calibration results are ensured. The material selection of the high-precision small balls has the characteristics of low conductivity and low relative permittivity, such as POM engineering plastics or zirconia ceramics, which avoids the influence of conductivity differences on the measurement results.

[0090] Second, the calibration device 7 replicates the local structure of the special-shaped impedance void meter one by one, ensuring the accuracy and precision of the calibration data. The calibration device 7 realizes the measurement through the transmitting electrode 73 and the receiving electrode 74. The signal amplification circuit board 8 generates a stable alternating voltage, and improves the stability and accuracy of the signal through the low-pass filtering and operational amplification circuit.

[0091] In addition, by plotting the characteristic diagram of void fraction - dimensionless voltage change and using polynomial fitting, the calibration curve is obtained. This process is repeated multiple times to eliminate random errors, ensuring the accuracy and reliability of the calibration curve.

[0092] Finally, this solution realizes the accurate measurement and calibration of different void fractions and can be applied within the full flow pattern range from bubbly flow to annular flow. The calibration curve provides reliable data support for establishing the flow pattern transition model and the drift flow model. Through the design of the shielded coaxial cable and the signal amplification circuit board 8, electromagnetic interference is effectively shielded, improving the accuracy and stability of the measurement.

[0093] In summary, this solution provides a calibration method for a special-shaped impedance void meter with high precision and high reliability, which can accurately and effectively measure the void fraction and provides a solid data basis for further research and application.

[0094] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A calibration method for a special-shaped impedance cavitometer, characterized in that Including the following calibration methods: S1. Proportionally reproduce the calibration device (7) with a special-shaped impedance cavitator, and establish a cavitator calibration system based on the calibration device (7); S2. Measure the voltages V of the receiving electrode (74) of the calibration device (7) under the conditions of full liquid phase and full gas phase respectively f and V g ; S3. Prepare several high-precision small balls to simulate the bubbles of the special-shaped impedance cavitometer. Put an appropriate amount of high-precision small balls into the calibration device (7), record the number of high-precision small balls with different diameters placed in the calibration device (7), and calculate the total volume Vo of all high-precision small balls to obtain the actual void fraction sp , and obtain the actual void fraction : ； Among them, Vo to is the total volume of the fluid domain between the two electrode modules (34); S4. Fill the calibration device (7) with water to the brim, record the voltage V measured by the receiving electrode (74) at this time, and obtain the void fraction The corresponding dimensionless voltage : ； S5. Change the number or size of the high-precision small balls, but the void fraction needs to be kept unchanged, repeat steps S3 to S4 to measure the actual void fraction multiple times and the dimensionless voltage ; S6. Change the number or size of the high-precision small balls so that the void fraction changes, and repeat steps S3, S4, and S5. In this step, the void fraction is uniformly controlled to vary between 0 and 1; S7. Plot the cavitation fraction - dimensionless voltage change characteristic diagram, and use a polynomial for fitting: ； where a i are polynomial coefficients respectively, and i = 0, 1, 2, 3, ... n; S8. According to the cavitation fraction - dimensionless voltage change characteristic diagram, obtain the calibration curve of the special-shaped impedance cavitator through polynomial fitting: - - + + 。 2. The calibration method of a special-shaped impedance cavitometer according to claim 1, characterized in that In S5, measure at least three times to eliminate the influence of random errors.

3. A calibration method for a special-shaped impedance cavitometer according to claim 1, characterized in that, The cavitator calibration system includes a calibration device (7), the calibration device (7) is electrically connected to a signal amplification circuit board (8), the signal amplification circuit board (8) is electrically connected to a data collector (9), and the data collector (9) is electrically connected to a computer (6).

4. A calibration method for a special-shaped impedance cavitometer according to claim 1, characterized in that The high-precision small ball has a diameter of 1 - 6 mm, and the high-precision small ball is made of POM engineering plastic or zirconia ceramic.

5. A calibration method for a special-shaped impedance cavitometer according to claim 3, characterized in that The calibration device (7) includes a calibration seat (71) proportionally reproduced with the casing (1), the inner wall of the calibration seat (71) is provided with a transmitting electrode (73) and a receiving electrode (74), both the transmitting electrode (73) and the receiving electrode (74) are electrically connected to a second wire (75), the second wire (75) is hermetically penetrated through one side of the calibration seat (71), and the inner wall of the calibration seat (71) is provided with a number of rod bundle substrates (72) proportionally reproduced with the spiral cross rod bundle (2).

6. A calibration method for a special-shaped impedance cavitometer according to claim 5, characterized in that The material of the rod bundle substrate (72) and the calibration seat (71) is high-tough resin, and the second wire (75) is a shielded coaxial cable.

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