阅读说明：本技术 一种铅铋堆气泡堆芯分布实验的空泡份额测量方法及装置 (Cavitation share measuring method and device for lead-bismuth reactor bubble reactor core distribution experiment ) 是由 郭超 严明宇 申亚欧 邓坚 黄代顺 王啸宇 隋海明 孙伟 李仲春 于 2021-07-15 设计创作，主要内容包括：本发明堆芯测量技术,具体涉及一种铅铋堆气泡堆芯分布实验的空泡份额测量方法及装置。搭接测量装置,包括截面为套筒、固定于套筒内的电加热棒,以及通气管,电加热棒外壁上设有热电偶,套管内填充不透明流体；利用热电偶4测量对应位置的温度,记录温度随时间的变化；等到热电偶测量温度稳定后,从套管下部间隔的向气体通道内通入气泡,采用过程中热电偶测得温度,记录温度随时间的变化；在相邻的轴向高度分别获得壁面平均温度,取差值得到对应的空泡份额。能够准确得到冷却剂通道不同位置的空泡份额,进而得到气泡进入堆芯的分布行为。(The invention relates to a reactor core measuring technology, in particular to a cavitation share measuring method and device for a lead bismuth reactor bubble reactor core distribution experiment. The lap joint measuring device comprises a sleeve with a section, an electric heating rod fixed in the sleeve and a vent pipe, wherein a thermocouple is arranged on the outer wall of the electric heating rod, and opaque fluid is filled in the sleeve; measuring the temperature of the corresponding position by using the thermocouple 4, and recording the change of the temperature along with the time; after the temperature measured by the thermocouple is stable, introducing bubbles into the gas channel at intervals from the lower part of the sleeve, measuring the temperature by adopting the thermocouple in the process, and recording the change of the temperature along with the time; and respectively obtaining the average temperature of the wall surface at the adjacent axial heights, and taking the difference to obtain the corresponding void fraction. The void fraction of the coolant channel at different positions can be accurately obtained, and then the distribution behavior of bubbles entering the reactor core is obtained.)

1. The utility model provides a cavitation share measuring device of plumbous bismuth pile bubble reactor core distribution experiment which characterized in that: the electric heating device comprises a sleeve (2) with an N-edge-shaped section, a plurality of electric heating rods (1) fixed in the sleeve (2), and a vent pipe (3) used for ventilating the sleeve (2) from the lower end;

the electric heating rod (1) comprises an electric heating rod (1-1) which is positioned at the center and is coaxially arranged with the sleeve (2), and other electric heating rods (1-2) which are uniformly arranged at the periphery of the electric heating rod (1-1) at the center in the circumferential direction;

the circle centers of the cross sections of all the three adjacent electric heating rods (1) are positioned on the corners of an equilateral triangle, namely all the electric heating rods (1) are arranged in the form of the equilateral triangle in the cross section direction of the sleeve (2);

the centers of the cross sections of all other electric heating rods (1-2) are sequentially connected to form an N-shaped edge which is parallel to the corresponding edge of the cross section of the sleeve (2);

the outer wall of the electric heating rod (1) is provided with a plurality of thermocouples (4);

distances are reserved between all other electric heating rods (1-2) and the inner wall of the sleeve (2);

a distance is reserved between the adjacent electric heating rods (1) in the cross section direction;

the sleeve (2) is filled with opaque fluid.

2. The apparatus for measuring the void fraction in the bubble core distribution experiment of the lead-bismuth reactor as claimed in claim 1, wherein: the thermocouples (4) are arranged on the outer wall of the electric heating rod (1), 6 thermocouples are uniformly and circumferentially arranged on the outer wall of the central electric heating rod (1-1) at the same cross section position, and 2 thermocouples are arranged on the outer walls of other electric heating rods (1-2) facing to the inner side of the center; in the same arrangement, such a group of thermocouples (4) is arranged along the axial direction at cross-sectional positions at intervals of 10-15 cm.

3. The apparatus for measuring the void fraction in the bubble core distribution experiment of the lead-bismuth reactor as claimed in claim 1, wherein: the number of the electric heating rods (1) is 7, one electric heating rod (1-1) is positioned in the center and is coaxially arranged with the sleeve (2), namely the circle center of the section of the electric heating rod is positioned in the axial direction of the sleeve (2); besides the central electric heating rod (1-1), 6 other electric heating rods (1-2) are additionally arranged, and the centers of the cross sections of the electric heating rods are sequentially connected to form a hexagon; the section of the sleeve (2) is hexagonal.

4. The apparatus for measuring the void fraction in the bubble core distribution experiment of the lead-bismuth reactor as claimed in claim 3, wherein: on the same section, 6 thermocouples (4) are uniformly and circumferentially arranged on the outer wall of the central electric heating rod (1-1); 2 thermocouples (4) are arranged on the outer wall of the other electric heating rods (1-2) facing to the inner side of the center; on the same cross section, all the electric heating rods (1) are arranged in 18 in total; in the same arrangement, such a group of 18 thermocouples (4) is arranged at intervals of ten centimeters in the axial direction.

5. The apparatus for measuring the void fraction in the bubble core distribution experiment of the lead-bismuth reactor as claimed in claim 1, wherein: the opaque fluid is liquid lead bismuth.

6. The apparatus for measuring the void fraction in the bubble core distribution experiment of the lead-bismuth reactor as claimed in claim 1, wherein: the upper end and the lower end in the sleeve (2) are respectively and fixedly provided with an upper fixed grillwork (2-1) and a lower fixed grillwork (2-2), the upper fixed grillwork (2-1) and the lower fixed grillwork (2-2) have the same shape and structure, and the plate surface of the upper fixed grillwork (2-1) is provided with mounting holes corresponding to the electric heating rods (1).

7. The apparatus for measuring the void fraction in the bubble core distribution experiment of the lead-bismuth reactor as claimed in claim 1, wherein: the distance between all other electric heating rods (1-2) and the inner wall of the sleeve (2) is less than or equal to the section circle radius of the electric heating rods (1).

8. The apparatus for measuring the void fraction in the bubble core distribution experiment of the lead-bismuth reactor as claimed in claim 1, wherein: the distance between all adjacent electric heating rods (1) in the cross section direction is less than or equal to the radius of the cross section circle of the electric heating rods (1).

9. A cavitation fraction measuring method for a lead bismuth reactor bubble reactor core distribution experiment is characterized by comprising the following steps:

1) building a cavitation share measuring device for the lead bismuth reactor bubble reactor core distribution experiment; the central electric heating rod (1-1) and the part surrounded by the three central axes of any adjacent 2 other electric heating rods (1-2) form a gas channel (5) with an equilateral triangle section;

2) filling opaque fluid in the sleeve (2); measuring the temperature of the corresponding position by using a thermocouple (4), and recording the change of the temperature along with the time;

3) electrifying all the electric heating rods (1) for preheating;

4) after the temperature measured by the thermocouple (4) is stable, introducing bubbles into the gas channel (5) at intervals from the lower part of the sleeve (2), measuring the temperature by adopting the thermocouple (4) in the process, and recording the change of the temperature along with the time;

5) closing the electric heating rod and the thermocouple, and processing data;

5.1) averaging the temperature measured by all thermocouples of each gas channel (5) at the same axial height to obtain the average temperature of the wall surface at the height.

5.2) for the same gas channel (5) in step 5.1), additional wall surface average temperatures are obtained at adjacent axial heights, and the difference between the two wall surface average temperatures is used to obtain the void fraction through the region between the two axial heights of the gas channel (5).

10. The method for measuring the void fraction of the lead-bismuth reactor bubble core distribution experiment as claimed in claim 9, wherein the method comprises the following steps: 3 thermocouples (4) of each gas channel (5) at the same axial height are provided, and the vacuole share passing through the area between the two axial heights of the sub-channel is obtained by using the formula (1) in the step 5.2);

wherein X is the void fraction, P is the electrical heating power generated by the electrical heating rod 1 between two axial heights, m₀Is the thermal capacity of the fluid between two axial levels,respectively measuring the temperature of three thermocouples at the axial height position in the step 5.1),and 5.2) respectively measuring the temperature of the three thermocouples at the axial height position.

11. The method for measuring the void fraction of the lead-bismuth reactor bubble core distribution experiment as claimed in claim 10, wherein the method comprises the following steps: and 4) after the temperature measured by the thermocouple (4) is stable, introducing bubbles from the lower part of the sleeve (2) by using the vent pipe (3), stopping introducing the bubbles after 5 seconds of introducing the bubbles, introducing the bubbles again for 5 seconds after 10 seconds, then stopping introducing the bubbles, measuring the temperature by using the thermocouple (4) in the process, and recording the change of the temperature along with the time.

12. The method for measuring the void fraction of the lead-bismuth reactor bubble core distribution experiment as claimed in claim 10, wherein the method comprises the following steps: in the step 3), the heating power of the electric heating rod (1) is 50W.

Technical Field

The invention belongs to a reactor core measuring technology, and particularly relates to a cavitation share measuring method and device for a lead bismuth reactor bubble reactor core distribution experiment.

Background

In the case of a steam generator heat transfer tube breakage accident of the lead bismuth reactor, bubbles entering the primary loop from the secondary loop may be entrained to enter the reactor core, and the safe operation of the reactor is threatened. The distribution behavior of the bubbles entering the core rod bundle channel needs to be researched by adopting an experimental method, so that the influence of the bubbles on the heat transfer of the core can be accurately evaluated.

Lead and bismuth belong to opaque liquid metal, are opaque fluid, and can not adopt the traditional laser ray method to measure the bubble distribution behavior.

The measurement of the bubble distribution behavior is carried out, namely, the void fraction in a certain area needs to be measured, and then the distribution behavior of the bubbles in the reactor core under the opaque fluid environment is determined through the change of the void fraction along with time.

Disclosure of Invention

The invention aims to provide a method and a device for measuring void fraction in a bubble reactor core distribution experiment of a lead bismuth reactor, which can accurately obtain void fractions at different positions of a coolant channel so as to obtain the distribution behavior of bubbles entering a reactor core.

The technical scheme of the invention is as follows:

a cavitation share measuring device for a lead bismuth reactor bubble reactor core distribution experiment comprises a sleeve with an N-shaped section, a plurality of electric heating rods fixed in the sleeve, and a vent pipe used for ventilating the sleeve from the lower end;

the electric heating rods comprise an electric heating rod positioned at the center and coaxially arranged with the sleeve, and other electric heating rods which are uniformly arranged at the periphery of the electric heating rod at the center in the circumferential direction;

the centers of the cross sections of all the three adjacent electric heating rods are positioned on the corners of the equilateral triangle, namely all the electric heating rods are arranged in the equilateral triangle form in the cross section direction of the sleeve;

the circle centers of the cross sections of all other electric heating rods are sequentially connected to form an N-shaped edge which is parallel to the corresponding edge of the cross section of the sleeve;

the outer wall of the electric heating rod is provided with a plurality of thermocouples;

distances are reserved between all other electric heating rods and the inner wall of the sleeve;

a distance is reserved between the adjacent electric heating rods in the cross section direction;

the sleeve is filled with opaque fluid.

The thermocouples are arranged on the outer wall of the electric heating rod, on the same section position, the outer wall of the central electric heating rod is uniformly and circumferentially arranged, and the outer walls of other electric heating rods facing the inner side of the center are arranged with 2 thermocouples; in the same arrangement, such a set of thermocouples is arranged along the axial direction at cross-sectional locations spaced apart by 10-15 cm.

The number of the electric heating rods is 7, the central electric heating rod is positioned in the center and is coaxially arranged with the sleeve, namely the circle center of the section of the central electric heating rod is positioned in the axial direction of the sleeve; besides the central electric heating rod, 6 other electric heating rods are additionally arranged, and the centers of the cross sections of the other electric heating rods are sequentially connected to form a hexagon; the section of the sleeve is hexagonal.

On the same cross section, 6 thermocouples are uniformly and circumferentially arranged on the outer wall of the central electric heating rod; 2 thermocouples are arranged on the outer walls of the other electric heating rods facing the inner side of the center; on the same cross section, all the electric heating rods are arranged in 18 numbers; in the same arrangement, such a group of 18 thermocouples was arranged every ten centimeters in the axial direction.

The opaque fluid is liquid lead bismuth.

The upper end and the lower end in the sleeve are respectively and fixedly provided with an upper fixed grid and a lower fixed grid, the upper fixed grid and the lower fixed grid are the same in shape and structure, and mounting holes corresponding to the electric heating rods are processed on the surfaces of the upper fixed grid and the lower fixed grid.

The distance between all other electric heating rods and the inner wall of the sleeve is less than or equal to the section circle radius of the electric heating rods.

The distance left between all adjacent electric heating rods in the cross section direction is less than or equal to the radius of the cross section circle of the electric heating rods.

A cavitation bubble portion measuring method for a lead bismuth reactor bubble reactor core distribution experiment comprises the following steps:

1) building a cavitation share measuring device for the lead bismuth reactor bubble reactor core distribution experiment; the central electric heating rod and the part surrounded by three central axes of any adjacent 2 other electric heating rods form a gas channel with an equilateral triangle section;

2) filling opaque fluid in the sleeve; measuring the temperature of the corresponding position by using the thermocouple 4, and recording the change of the temperature along with the time;

3) electrifying all the electric heating rods for preheating;

4) after the temperature measured by the thermocouple is stable, introducing bubbles into the gas channel at intervals from the lower part of the sleeve, measuring the temperature by adopting the thermocouple in the process, and recording the change of the temperature along with the time;

5) closing the electric heating rod and the thermocouple, and processing data;

5.1) averaging the temperature measured by all thermocouples of each gas channel at the same axial height to obtain the average temperature of the wall surface at the height.

5.2) obtaining additional wall surface average temperatures at adjacent axial heights for the same gas channel in step 5.1), and obtaining the void fraction passing through the region between the two axial heights of the gas channel by taking the difference between the two wall surface average temperatures.

3 thermocouples are arranged at the same axial height of each gas channel, and the vacuole share passing through the area between the two axial heights of the sub-channel is obtained by using the formula (1) in the step 5.2);

wherein X is the void fraction, P is the electrical heating power generated by the electrical heating rod 1 between two axial heights, m₀Is the thermal capacity of the fluid between two axial levels,respectively measuring the temperature of three thermocouples at the axial height position in the step 5.1),and 5.2) respectively measuring the temperature of the three thermocouples at the axial height position.

And 4) after the temperature measured by the thermocouple is stable, introducing bubbles from the lower part of the sleeve by using a vent pipe, stopping introducing the bubbles after every 5 seconds, introducing the bubbles again for 5 seconds after 10 seconds, then stopping introducing the bubbles, measuring the temperature by using the thermocouple in the process, and recording the change of the temperature along with the time.

In the step 3), the heating power of the electric heating rod is 50W.

The invention has the following remarkable effects: the measuring device ensures the reliable realization of the method by designing the position of the electric heating rod and arranging the thermocouples at corresponding positions, determines the wall surface temperature average value difference value of two adjacent axial heights of one sub-channel, can calculate the flow and the void fraction passing through the area between two axial nodes of the sub-channel, processes the temperature curve and can obtain the change curve of the void fraction of the sub-channel at the position. The method is an observation method based on temperature measurement, can measure the distribution behavior of bubbles in a reactor core in the experimental process, and the change of gas-liquid share in a channel causes the influence of flow heat transfer, so that a thermocouple generates temperature change. Based on the mechanism, the bubble distribution behavior can be obtained according to the temperature change generated by the thermocouple, so that the measurement of the bubble distribution behavior is realized.

In the experiment, the electric heating rods can be arranged in a rod bundle in any form. Fig. 1 shows an example of the present invention, that is, when the bundle of rods is arranged in a triangular shape, six thermocouples should be arranged at an axial position of one electric heating rod, and the red dots in the figure are positions where the thermocouples are arranged.

In the experimental process, the electric heating rods are heated with low power, and bubbles are introduced from the bottoms of the rod bundles of the electric heating rods to obtain time-course curves of the temperatures of all measuring points of all the electric heating rods. By adopting the wall surface temperature average value difference of two adjacent axial heights of one sub-channel, the flow and the void fraction passing through the region between two axial nodes of the sub-channel can be calculated, and the time-course curve of the void fraction of the sub-channel at the position can be obtained by processing the temperature time-course curve. And (5) repeatedly carrying out a large number of experiments, and counting to obtain the bubble distribution behavior.

Drawings

FIG. 1 is a schematic diagram of the arrangement of an electric heating rod and a thermocouple in the measurement of void fraction in a bubble reactor core distribution experiment of a lead bismuth reactor;

FIG. 2 is a schematic diagram of a void fraction measuring device for a lead bismuth reactor bubble core distribution experiment;

in the figure: 1. an electrical heating rod; 2. a sleeve; 2-1, fixing a framework; 2-2, lower fixing grillwork; 3. a breather pipe; 4. a thermocouple; 1-1. a central electric heating rod; 1-2. other electrical heating rods; 5. a gas channel;

Detailed Description

The invention is further illustrated by the accompanying drawings and the detailed description.

The method is based on the basic principle of flow heat transfer, and thermocouples are arranged at different radial positions and axial positions of the electric heating rod and are used for obtaining wall surface temperature time-course curves of the electric heating rod at different positions.

The specific implementation process is as follows:

1) device for measuring cavitation share in bubble reactor core distribution experiment of lead-bismuth reactor

As shown in fig. 1 and 2, the measuring device includes 7 electric heating rods 1, a plurality of thermocouples 4 mounted on the outer wall of the electric heating rods 1, a sleeve 2 having a hexagonal cross-section, an upper fixed grid 2-1 and a lower fixed grid 2-2 for fixing the electric heating rods 1 on the upper and lower surfaces of the sleeve 2, and a ventilation pipe 3 mounted on the lower portion of the sleeve 2 and capable of ventilating the interior of the sleeve 2.

The upper fixing grid 2-1 and the lower fixing grid 2-2 are respectively fixed at the upper end and the lower end of the sleeve 2, and mounting holes corresponding to the positions of the electric heating rods 1 are processed on the grid plate surface, so that the electric heating rods 1 can be fixed through the upper fixing grid 2-1 and the lower fixing grid 2-2;

when the device is built, firstly, 7 electric heating rods 1 are arranged in a sleeve 2 through an upper fixed grillwork 2-1 and a lower fixed grillwork 2-2, so that the arrangement of all the electric heating rods 1 meets the following characteristics:

1) an electric heating rod 1-1 is positioned in the center and is coaxially arranged with the sleeve 2, namely the center of the cross section of the electric heating rod is positioned in the axial direction of the sleeve 2;

2) the circle centers of the cross sections of all the three adjacent electric heating rods 1 are positioned on the corners of an equilateral triangle, namely all the electric heating rods 1 are arranged in the form of the equilateral triangle in the cross section direction of the sleeve 2;

3) except the central electric heating rod 1-1 positioned on the axis in the characteristic 1), the centers of the cross sections of the other 6 electric heating rods 1-2 are sequentially connected to form a hexagon, and a distance is reserved between the electric heating rods 1-1 and the inner wall of the sleeve 2;

4) in addition, the center of the cross section of the 6 electric heating rods 1-2 forms a hexagon which has the same direction as the hexagon of the cross section of the sleeve 2, namely, each side is correspondingly parallel;

the portion surrounded by three axes of the electric heating rods 1-1 and 6 electric heating rods 1-2 in the center forms a gas channel 5 with an equilateral triangle section.

The thermocouple 4 is installed on the outer wall of the electric heating rod 1, and the arrangement mode is as follows:

on the same cross section, 6 central electric heating rods 1-1 are uniformly and circumferentially arranged on the outer wall; 2 electric heating rods 1-2 are arranged on the outer wall facing the inner side of the center, and the arrangement interval of the 2 electric heating rods is 6 intervals which are uniformly arranged;

then on the same cross section, 18 electric heating rods 1 are arranged;

in the same arrangement, such a group of 18 thermocouples 4 is arranged at intervals of ten centimeters in the axial direction;

the vent pipe 3 is communicated with any one gas channel 5 from the lower part, and in the test process, bubbles enter from the vent pipe 3 at the lower part of the sleeve, flow upwards through the rod bundle section through the gas channel 5 and are finally discharged from the upper part of the sleeve 2.

2) Opaque fluid, namely liquid lead bismuth is filled in the sleeve 2; measuring the temperature of the corresponding position by using the thermocouple 4, and recording the change of the temperature along with the time;

3) electrifying all the electric heating rods 1, and preheating with the heating power of the electric heating rods 1 being 50W;

4) after the temperature measured by the thermocouple 4 is stable, introducing bubbles from the lower part of the sleeve 2 by using the vent pipe 5, stopping introducing the bubbles after every 5 seconds, after 10 seconds, introducing the bubbles again for 5 seconds, then stopping introducing the bubbles, measuring the temperature by using the thermocouple 4 in the process, and recording the change of the temperature along with the time;

5) closing the electric heating rod and the thermocouple, and processing data;

5.1) each triangular gas channel 5 has three thermocouples at the same axial height (same section position), and the temperature measured by the three thermocouples is averaged to obtain the wall surface average temperature of the triangular gas channel at the height.

5.2) aiming at the same triangular gas channel 5 in the step 5.1), obtaining the wall surface average temperature difference of two adjacent axial heights (two adjacent section positions), and obtaining the void fraction passing through the region between the two axial heights of the sub-channel by using a formula 1;

wherein X is the void fraction, P is the electrical heating power generated by the electrical heating rod 1 between two axial heights, m₀Is the thermal capacity of the fluid between two axial levels,respectively measuring the temperature of three thermocouples at the axial height position in the step 5.1),and 5.2) respectively measuring the temperature of the three thermocouples at the axial height position.

The change in the temperature measured by the thermocouple with time can be calculated by the above calculation method to obtain the change in the void fraction of the subchannel at that point (between the two axial heights) with time.