A lead bismuth alloy flow-induced vibration characteristic parameter measuring device and measuring method

Abstract

This invention discloses a device and method for measuring the characteristic parameters of flow-induced vibration of lead-bismuth alloys. The existing methods for measuring displacement characteristic parameters are not suitable for experimental research on flow-induced vibration in multi-rectangular narrow channels. Therefore, to address the limitations of existing strain measurement methods in estimating displacement parameters, this invention proposes a reasonable mechanical model and assumptions. This invention uses two stainless steel plates to form a rectangular narrow channel for the flow of lead-bismuth alloys. The inlet and outlet areas are connected by a rectangular variable-diameter chamber and a cylindrical chamber, respectively. The rectangular narrow channel is fixed laterally and longitudinally by bolt connections. A heating element is placed on the outside of the rectangular channel plate in the experimental parameter measurement area to independently monitor and control the temperature on the outside of the channel plate. The displacement parameters of the channel plate obtained by the traditional visualization imaging method and the strain-deflection integration method are compared, and the two sets of results are mutually verified. This invention is used for measuring the characteristic parameters of flow-induced vibration of lead-bismuth alloys.

Description

Technical Field

[0001] This invention relates to a vibration characteristic parameter measuring device and method, specifically to a device and method for measuring the flow-induced vibration characteristic parameters of a lead-bismuth alloy in a rectangular narrow channel. Specifically, it measures key parameters such as amplitude and acceleration of the rectangular channel plate and compares the results calculated by high-speed photogrammetry and strain-deflection integral method. It mainly involves the technical fields of fluid mechanics, structural mechanics, vibration dynamics, and materials mechanics. Background Technology

[0002] Liquid lead-bismuth alloy coolant has the characteristics of high boiling point, high thermal conductivity, and low melting point, which allows the reactor to operate at atmospheric pressure, reduces the pressure requirements of the primary loop equipment, makes the reactor less prone to criticality under severe accidents, and has high safety. In addition, it has a weak neutron moderation capability and a small absorption cross section, which has good neutron economy. Due to its good chemical inertness, it avoids sodium fire accidents, reduces the probability of accidents in the reactor, and ensures the safety of the reactor.

[0003] The rectangular narrow channel consists of plate-shaped fuel elements and rectangular coolant channels. The fuel plates are narrow, long, and extremely thin, with a spacing of only 2–3 mm, resulting in a compact structure. The high-speed flow of coolant between the fuel plates can induce strong flow-induced vibrations, potentially threatening the safe operation of the reactor. Therefore, research on flow-induced vibrations induced by coolant flow within the rectangular narrow channel is of great significance.

[0004] Current research on the flow-induced vibration of lead-bismuth alloys mainly focuses on numerical simulations in rod bundle channels and helical tube channels, emphasizing the mechanism of induced flow-induced vibration. Experimental studies on flow-induced vibration in rectangular narrow channels are mostly conducted with water flowing through a single channel, exploring the influence of structural parameters such as the fixing method of the rectangular plate, the dimensions of the rectangular channel plate, and the flow parameters of the medium on the flow-induced vibration phenomenon. Due to the significant difference in physical properties between lead-bismuth alloys and water, and the unique structure of rectangular narrow channels, the design of experimental setups and the exploration of parameter measurement methods for flow-induced vibration of lead-bismuth alloys in rectangular narrow channels have significant engineering value and theoretical significance.

[0005] Chinese patent CN114608774A discloses an experimental apparatus and method for lead-bismuth flow-induced vibration. This invention connects the flange to the test section shell via a flange, facilitating the replacement of different rod bundle structures. Furthermore, the fiber optic strain gauge and accelerometer can simultaneously measure strain and acceleration, enabling the measurement of both low-frequency and high-frequency strain. However, this invention uses sensors to measure parameters such as rod bundle strain and acceleration. If the strain measurement method is used to deduce displacement parameters in the study of flow-induced vibration in rectangular narrow channels, a reasonable mechanical model and assumptions are required.

[0006] Chinese patent CN115112323A discloses an experimental device and method for the flow-induced vibration of a liquid lead-bismuth slicked wire-wound positioning rod bundle. This invention can meet the requirements for the experimental study of the flow-induced vibration of the liquid lead-bismuth slicked wire-wound positioning rod bundle under high temperature and high flow rate conditions, and capture the changes in characteristic parameters such as displacement, velocity, and acceleration during the vibration response of the wire-wound rod bundle. However, the measurement technology of this invention is applied to the rod bundle structure, and the displacement characteristic parameter measurement method cannot be applied to the experimental study of flow-induced vibration in multi-rectangular narrow channels.

[0007] In summary, existing methods for estimating displacement parameters using strain measurement in the study of flow-induced vibration in rectangular narrow channels require the formulation of reasonable mechanical models and assumptions. Furthermore, existing methods for measuring displacement characteristic parameters are not applicable to experimental studies of flow-induced vibration in multiple rectangular narrow channels. Summary of the Invention

[0008] The purpose of this invention is to address the problem that existing methods for calculating displacement parameters using strain measurement in the study of flow-induced vibration in rectangular narrow channels require reasonable mechanical models and assumptions, and that displacement characteristic parameter measurement methods are not applicable to experimental research on flow-induced vibration in multiple rectangular narrow channels. Therefore, this invention provides a device and method for measuring the characteristic parameters of flow-induced vibration in lead-bismuth alloys.

[0009] The technical solution of this invention is as follows: A device for measuring the characteristic parameters of flow-induced vibration of a lead-bismuth alloy includes two cylindrical chambers and two rectangular chambers. A rectangular chamber is installed on one horizontal end face of each cylindrical chamber. The two rectangular chambers are arranged adjacent to each other and maintain a distance equal to the length of the rectangular channel of the experimental section. The two cylindrical chambers are arranged coaxially. It also includes a rectangular narrow channel, a heating cable, a clamping device, an electric heating wire, an experimental section fixing plate, a variable diameter fixing plate, a visual imaging experimental displacement marker, a reference fixing plate, an equipment mounting fixing plate, a high-speed camera, an acceleration sensor, and multiple fiber optic strain sensors. The two rectangular chambers are sealed together through the rectangular narrow channel. The heating cable is spirally wound around the outer surface of the rectangular narrow channel. An electric heating wire is spirally wound on the outer wall of each cylindrical chamber. The clamping device clamps the two cylindrical chambers, and both ends of the clamping device are fixed... The experimental section is fixedly mounted on a horizontally parallel plate; one end of a variable-diameter plate is mounted on the upper and lower ends of the rectangular narrow channel, and the other end of the variable-diameter plate is fixed to the experimental section plate; a visual imaging experimental displacement marker is vertically mounted in the middle of the rectangular narrow channel; an equipment mounting plate is mounted on the front side of the rectangular narrow channel, and a high-speed camera is mounted on the equipment mounting plate. The high-speed camera and the visual imaging experimental displacement marker are at the same horizontal level, and the protruding section of the visual imaging experimental displacement marker is parallel to the equipment mounting plate; a reference plate is located on the rear side of the rectangular narrow channel and connected to the experimental section plate; a groove is opened on the reference plate and a reference image indicating the position of the marker is laid on it; an acceleration sensor is mounted on the end of the visual imaging experimental displacement marker; multiple fiber optic strain sensors are arranged in groups along the short side of the rectangular narrow channel.

[0010] Furthermore, the rectangular narrow channel includes two stainless steel rectangular plates, two sealing strips, two sets of fixing pads, and multiple sets of fixing bolts. The two stainless steel rectangular plates are arranged in parallel, and the two sealing strips are embedded on both sides between the two stainless steel rectangular plates. The two stainless steel rectangular plates and the two sealing strips together form a rectangular cavity. The two sets of fixing pads are respectively installed on the outside of the two stainless steel rectangular plates, and the rectangular narrow channel is fixedly connected by multiple sets of fixing bolts passing through the two stainless steel rectangular plates and the two sealing strips.

[0011] Furthermore, the rectangular narrow channel also includes a stainless steel gasket, which is installed between the inner wall of the stainless steel rectangular plate and the outer wall of the sealing strip.

[0012] Furthermore, a high-temperature resistant sealant is applied between the inner wall of the stainless steel rectangular plate and the outer wall of the sealing strip.

[0013] Furthermore, it also includes aluminum silicate insulation cotton, with the outer walls of the cylindrical and rectangular chambers wrapped with aluminum silicate insulation cotton.

[0014] Preferably, both the sealing strip and the fixing pad are elongated strips.

[0015] Furthermore, each set of fiber optic strain sensors is installed horizontally with a denser arrangement in the middle and a sparser arrangement on both sides.

[0016] The present invention also provides a measurement method using a lead-bismuth alloy flow-induced vibration characteristic parameter measuring device, which includes the following steps:

[0017] Step 1: Simultaneously perform visual imaging and sensor measurements;

[0018] Step 11: Use visual photography to directly obtain data:

[0019] S111: A visual imaging experiment displacement marker with a diameter of 1mm and a length of 100mm is vertically welded to the center point of the outer side of a stainless steel rectangular plate.

[0020] S112: When the rectangular channel plate vibrates under the impact of lead-bismuth alloy at different flow rates, it will cause the displacement marker of the visualization imaging experiment to vibrate.

[0021] S113: Using a high-speed camera at the same horizontal height as the displacement marker in the visualization experiment, the positional change of the displacement marker in the visualization experiment is captured laterally. The reference plane for the positional change of the displacement marker in the visualization experiment is symmetrically arranged with the axis of the displacement marker in the visualization experiment as the axis of symmetry and the high-speed camera, so as to capture the real-time position of the marker change caused by vibration.

[0022] Steps one and two: Sensor measurements include acceleration measurement and strain measurement:

[0023] Step 121: Acceleration measurement includes the following steps:

[0024] S1211: An accelerometer is positioned at the end of the displacement marker in the visualization experiment.

[0025] S1212: Acceleration parameters at the center of a rectangular narrow channel can be obtained by connecting the hardware and transmitting the analog voltage signal to the NI acquisition system;

[0026] Step 122: Strain measurement includes the following steps:

[0027] S1222: Fiber optic strain sensors are arranged in groups at different vertical heights parallel to the short side outside a rectangular narrow channel.

[0028] S1223: The voltage signal output by the fiber optic strain sensor is imported into the host via the USB interface and interacts with the LabVIEW software;

[0029] Step 2: Verify the data obtained from visual imaging and sensor measurements:

[0030] Step 21: Measure the maximum position of the stainless steel rectangular plate, i.e., the displacement at the center of the stainless steel rectangular plate, using the visualization shooting method in Step 11. At the same time, measure the strain values ​​at different positions on the outside of the stainless steel rectangular plate using the sensor measurement method in Step 121. The purpose is to calculate the deflection of the stainless steel rectangular plate caused by the lead-bismuth alloy flowing through the rectangular narrow channel using the integration method, and compare the numerical relationship between the displacement and deflection at the center of the stainless steel rectangular plate.

[0031] Step 22: Calculate the strain-deflection integral using the strain measurement data collected in Step 122;

[0032] By comparing the results of the visualization imaging method and the strain-deflection integral method, the optimal data was obtained through mutual verification, thus realizing the parameter measurement of the flow-induced vibration characteristics of lead-bismuth alloy.

[0033] Furthermore, step two-two of the strain-deflection integral method calculation includes the following steps:

[0034] S221: The integral method data acquisition points of the stainless steel rectangular plate are all arranged at different heights along the x-direction.

[0035] S222: The fiber optic strain sensor measures the normal strain of the stainless steel rectangular plate 14 in the x and y directions. After ignoring the shear stress and normal stress in the thickness direction, the normal strain in the y direction is ignored due to the cylindrical bending of the thin plate.

[0036] Therefore, the physical equation for the bending of a rectangular narrow channel is equation (1).

[0037]

[0038] Equation (2) represents the numerical relationship between strain and deflection of a thin plate.

[0039]

[0040] In the formula ε x For experimentally measuring strain values, h is the thickness of the plate;

[0041] Integrating equation (2) yields the explicit expression (3) for the relationship between deflection and strain.

[0042]

[0043] In equation (3), the strain in the x-direction is measured using a fiber optic strain sensor;

[0044] S223: According to the completed numerical simulation results, when the bending of the long side is ignored, the deflection distribution of the short side at different lateral positions at the same height conforms to the formula (3), and there is a deflection extreme value at the center line of the rectangular plate. Then, the formula (3) is expressed as the formula (4), and the x range is always [-b / 2, b / 2], and k is an undetermined coefficient.

[0045]

[0046] In thin plate bending, the strain on the neutral plane is assumed to be 0, that is, the deflection parameter at each point is w = w(x,y). Therefore, the lateral displacement is only a function of x and y, and each point on any normal line on the neutral plane has the same lateral displacement.

[0047] After introducing the assumption of cylindrical bending, the deflection distribution of the rectangular thin plate along the short side at different heights can be simplified to the bending of a strip beam, with the maximum deflection at the midpoint of the beam. Therefore, it is assumed that the maximum displacement of the rectangular thin plate at different heights is at the central axis of the plate.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] 1. In the measurement method of this invention: the flow-induced vibration parameters of lead-bismuth alloy in a rectangular narrow channel under different working conditions are measured. The main parameters such as acceleration and amplitude can be obtained by using an accelerometer and a high-speed camera. The strain at different positions of the channel plate is measured by using an optical fiber strain sensor. The deflection at different positions of the channel plate is obtained based on the strain-deflection integral method. The results of the mechanical analysis method and the visualization imaging method can be mutually verified. The reasonable and reliable mechanical analysis model can not only be applied to the measurement of flow-induced vibration parameters in a single channel, but more importantly, it plays an important role in the measurement environment of flow-induced vibration parameters in a multi-channel channel where the visualization method cannot be applied. The vibration displacement parameters of each sub-channel plate can be calculated by strain.

[0050] 2. The experimental section (referring to the measuring device) of this invention is designed with cylindrical chambers and rectangular variable diameters at both the inlet and outlet. Both of these have a storage and buffering effect on the flow of lead-bismuth alloy, ensuring the flow stability of lead-bismuth alloy flowing into the rectangular narrow channel area and effectively avoiding the problem of inaccurate vibration parameter measurement caused by flow instability.

[0051] 3. This invention transforms the flow-induced vibration problem of lead-bismuth alloy in a rectangular narrow channel into a rectangular thin-plate cylindrical bending problem in structural mechanics by strictly defining the size range of the channel plate (referring to stainless steel rectangular plate 14). Through reasonable assumptions, a physical model is proposed to calculate the displacement parameters of the channel plate using the strain-deflection integral method.

[0052] 4. This invention compares the channel plate displacement parameters obtained by the traditional visualization imaging method with those obtained by the strain-deflection integral method. The two sets of results are mutually verified, and an integral method model applicable to different experimental conditions and channel structure parameters is proposed. The integral method effectively solves the problem that visualization methods cannot be applied to the study of multi-channel flow-induced vibration problems, which helps to simplify experimental equipment and improve the accuracy of experimental research. Attached Figure Description

[0053] Figure 1(a) is a three-dimensional structural schematic diagram of the thin plate described in this invention; Figure 1(b) is a front view of Figure 1(a); Figure 1(c) is a schematic diagram of the thin plate undergoing cylindrical bending;

[0054] Figure 2A This is a schematic diagram illustrating the short-side deflection distribution in the thin-plate cylindrical bending simulation analysis of this invention. Figure 2B This is a schematic diagram of the long-side deflection distribution in the simulation analysis of thin-plate cylindrical bending according to the present invention;

[0055] Figure 3 This is an isometric view of the experimental system when the measuring device of the present invention is installed in the experimental system device;

[0056] Figure 4A This is an isometric view of the measuring device of the present invention. Figure 4B yes Figure 4A A longitudinal sectional view;

[0057] Figure 5A This is an exploded view of the measuring device of the present invention from the axial side. Figure 5B yes Figure 5A The front view of the exploded diagram;

[0058] Figure 6 This is a schematic diagram of the overall structure of the experimental system device of the present invention;

[0059] Figure 7 This is a longitudinal schematic diagram of the measuring device of the present invention;

[0060] Figure 8 This is a horizontal schematic diagram of the measuring device of the present invention;

[0061] Figure 9 This is a schematic diagram of the measuring point arrangement of the measuring device of the present invention. Detailed Implementation

[0062] Specific implementation method one: Combining Figures 4A to 5B , Figures 7 to 9This embodiment describes a lead-bismuth alloy flow-induced vibration characteristic parameter measuring device comprising two cylindrical chambers 12 and two rectangular chambers 13. A rectangular chamber 13 is mounted on one horizontal end face of each cylindrical chamber 12. The two rectangular chambers 13 are arranged adjacent to each other and maintain a distance equal to the length of the rectangular channel of the experimental section. The two cylindrical chambers 12 are arranged coaxially. It also includes a rectangular narrow channel, a heating cable 17, a clamping device 15, an electric heating wire 50, an experimental section fixing plate 18, a variable diameter fixing plate 16, a visual imaging experimental displacement marker 23, a reference fixing plate 25, an equipment mounting fixing plate 28, a high-speed camera 27, an acceleration sensor, and multiple fiber optic strain sensors 24. The two rectangular chambers 13 are sealed together via the rectangular narrow channel. The heating cable 17 is spirally wound around the outer surface of the rectangular narrow channel. An electric heating wire 50 is spirally wound around the outer wall of each cylindrical chamber 12. The clamping device 15 clamps the two cylindrical chambers 12. The two ends of the device 15 are fixedly installed on the experimental section fixing plate 18 arranged in parallel left and right; one end of the variable diameter fixing plate 16 is installed on the upper and lower ends of the rectangular narrow channel, and the other end of the variable diameter fixing plate 16 is fixed on the experimental section fixing plate 18; the visual imaging experimental displacement marker 23 is vertically installed in the middle of the rectangular narrow channel; the equipment mounting fixing plate 28 is installed on the front side of the rectangular narrow channel, and the high-speed camera 27 is installed on the equipment mounting fixing plate 28. The high-speed camera 27 and the visual imaging experimental displacement marker 23 are located at the same horizontal height, and the protruding section of the visual imaging experimental displacement marker 23 is parallel to the equipment mounting fixing plate 28. The reference fixing plate 25 is located on the rear side of the rectangular narrow channel and is connected to the experimental section fixing plate 18. The reference fixing plate 25 has a groove and is covered with a reference object 26 that can indicate the position of the marker; the acceleration sensor is installed at the end of the visual imaging experimental displacement marker 23; multiple fiber optic strain sensors 24 are arranged in groups along the short side of the rectangular narrow channel.

[0063] The present invention provides a device for measuring the flow-induced vibration characteristic parameters of lead-bismuth alloy. This device is an experimental apparatus for measuring the flow-induced vibration parameters of lead-bismuth alloy in a rectangular narrow channel. The lead-bismuth alloy in the experimental system is powered by an electromagnetic pump. An air-cooled heat exchanger is used to cool the high temperature of the lead-bismuth alloy caused by the work of the electromagnetic pump, so as to ensure that the temperature of the lead-bismuth alloy entering the experimental apparatus meets the experimental requirements.

[0064] This invention uses two stainless steel plates 14 to form a narrow rectangular channel for the flow of lead-bismuth alloy. The inlet and outlet areas of the experimental section are respectively connected to a cylindrical chamber and a rectangular variable diameter section to store and buffer pressure fluctuations of the lead-bismuth alloy. In the experimental device, the channel plate is fixed laterally and longitudinally by bolts, the contact surfaces of the stainless steel components are fixed by welding, and the cylindrical chamber and the rectangular variable diameter section are fixed by mechanical clamping devices. The above fixing methods ensure sufficient stability of the experimental section. High-temperature resistant sealant is used to seal the gaps at the connection points of the experimental device components to prevent lead-bismuth alloy leakage. A heating tape is placed on the outside of the rectangular channel plate in the experimental parameter measurement area to independently monitor and control the temperature on the outside of the channel plate, so as to ensure that the lead-bismuth alloy generated by the induced flow-induced vibration phenomenon has a stable flow state and physical properties.

[0065] The invention includes equipment used for parameter measurement such as high-speed photography cameras, displacement markers, displacement references, acceleration sensors, and fiber optic strain sensors, as well as mechanical analysis models.

[0066] In practical use, this invention, such as Figure 6 The experimental system for measuring the flow-induced vibration parameters of lead-bismuth alloy in a rectangular narrow channel consists of experimental device 1 (referring to the measuring device), lead-bismuth storage tank 2, thermal oil furnace 9, air-cooled heat exchanger 6, filtration system 3, heat tracing system, valve system, argon gas supply system, vacuum system, measurement system, data acquisition system, power supply system, instruments, pumps and pipelines, etc.

[0067] This invention combines multiple displacement measurement schemes. It uses visualization imaging and deflection-strain mechanics model to calculate the displacement parameters generated after the flow of lead-bismuth alloy in a rectangular narrow channel induces channel vibration. The two research schemes can be mutually verified, providing a more novel and beneficial solution for measuring flow-induced vibration displacement parameters.

[0068] The lead-bismuth alloy of this invention is driven by a circulating pump and flows into the experimental device after being cooled by a heat exchanger. It is first stored and buffered in a cylindrical chamber. The cylindrical chamber and the experimental section body are connected by a rectangular variable diameter connection. The lead-bismuth alloy flowing through the rectangular variable diameter can achieve full development, ensuring strong flow stability after flowing into the experimental section body. When the lead-bismuth alloy with different flow velocities flows through the experimental section body, it interacts with the rectangular channel plate to produce flow-induced vibration. The experimental parameters are measured by visual imaging and sensor measurement methods.

[0069] The clamping device 15 in this embodiment includes two symmetrically arranged clamping units. Each clamping unit includes an arc-shaped plate and a rectangular plate. The arc-shaped plate is vertically arranged and its inner side is used to clamp the cylindrical cavity 12. The rectangular plate is horizontally arranged and fixedly connected to the outer side of the arc-shaped plate.

[0070] Specific Implementation Method Two: Combining Figures 5A to 5B This embodiment describes a rectangular narrow channel comprising two stainless steel rectangular plates 14, two sealing strips 21, two sets of fixing pads 22, and multiple sets of fixing bolts 19. The two stainless steel rectangular plates 14 are arranged in parallel, and the two sealing strips 21 are embedded on both sides between the two stainless steel rectangular plates 14. The two stainless steel rectangular plates 14 and the two sealing strips 21 together form a rectangular cavity. The two sets of fixing pads 22 are respectively installed on the outside of the two stainless steel rectangular plates 14, and the rectangular narrow channel is fixedly connected by multiple sets of fixing bolts 19 passing through the two stainless steel rectangular plates 14 and the two sealing strips 21.

[0071] In this configuration, the rectangular channel plate is horizontally fixed by placing stainless steel gaskets between the two plates and fixing blocks on the outside, then connecting them with bolts for through-hole fixation. Both the upper and lower sections of the channel plate are welded to the rectangular reducer. Horizontal fixing plates are vertically installed on both sides of the rectangular reducer and connected to the experimental platform fixing plate. The horizontal fixing plates are longitudinally fixed to the external blocks of the channel plate by bolts to enhance the stability of the fixing blocks. This fixing method ensures that the rectangular channel plate is firmly fixed on all four sides. Other components and connections are the same as in Specific Implementation Method 1.

[0072] Specific implementation method three: Combining Figure 8 This embodiment further includes a stainless steel gasket 20 in the rectangular narrow channel. The stainless steel gasket 20 is installed between the inner wall of the stainless steel rectangular plate 14 and the outer wall of the sealing strip 21. This arrangement allows the stainless steel gasket to both support and seal the rectangular narrow channel and to position the long side of the channel's cross-section. The fixed gasket also improves the strength of the rectangular narrow channel. Other components and connections are the same as in specific embodiments one or two.

[0073] Specific implementation method four: Combination Figure 8 In this embodiment, a high-temperature resistant sealant is applied between the inner wall of the stainless steel rectangular plate 14 and the outer wall of the sealing strip 21. This arrangement results in a good sealing effect. Other components and connections are the same as in specific embodiments one, two, or three.

[0074] Specific Implementation Method Five: Combining Figure 7 This embodiment further includes aluminum silicate insulation cotton 51, which is wrapped around the outer walls of the cylindrical chamber 12 and the rectangular chamber 13. With this configuration, the main body area of ​​the experimental device of the present invention, which requires the placement of various precision measuring devices for flow-induced vibration parameters, cannot be covered with aluminum silicate insulation cotton for heat preservation. Therefore, a heating wire is wound around the outside of the channel plate to provide real-time heating and insulation to the rectangular narrow channel area, ensuring that the lead-bismuth alloy flowing through the rectangular narrow channel has no temperature fluctuations. Other components and connections are the same as in specific embodiments one, two, three, or four.

[0075] Specific Implementation Method Six: Combination Figures 4A to 5B In this embodiment, both the sealing strip 21 and the fixing pad 22 are elongated strips. This design results in a simple structure and convenient connection. Other components and connections are the same as in specific embodiments one, two, three, four, or five.

[0076] Specific implementation method seven: Combining Figure 9 In this embodiment, each group of fiber optic strain sensors 24 is horizontally installed with a denser arrangement in the middle and a sparser arrangement at the sides. This arrangement, based on the theories of thin plate bending and cylindrical bending, ensures that each group of fiber optic strain sensors is densely packed in the middle and sparsely spaced at the sides. The longitudinal arrangement of the fiber optic strain sensors follows the principle of having a larger and denser number of groups in the inlet and outlet areas and a smaller and sparser number in the central area. Other components and connections are the same as in any of the specific embodiments one through six.

[0077] In this embodiment, each group of fiber optic strain sensors 24 is arranged with the characteristics of "dense in the middle and sparse on both sides". The purpose is to obtain as many data samples as possible in the central axis area and accurately obtain the distribution of the strain-deflection integral model calculation results.

[0078] In addition, according to the analysis results of the cylindrical bending theory, the deflection distribution of the stainless steel rectangular plate 14 along the long side almost shows the characteristics of "large gradient at the edge and zero gradient in the middle". Therefore, the fiber optic strain sensor 14 can be arranged in the longitudinal direction according to the principle of "more and denser groups in the inlet and outlet areas and fewer and sparser groups in the central area", so as to make reasonable and effective use of experimental resources.

[0079] Specific Implementation Method 8: Referring to Figures 1 to... Figure 9 This embodiment describes a measurement method that includes the following steps:

[0080] Step 1: Simultaneously perform visual imaging and sensor measurements;

[0081] Step 11: Use visual photography to directly obtain data:

[0082] S111: A visual imaging experiment displacement marker 23 with a diameter of 1 mm and a length of 100 mm is vertically welded to the outer center point of a stainless steel rectangular plate 14.

[0083] S112: When the rectangular channel plate vibrates under the impact of lead-bismuth alloy with different flow rates, it will cause the displacement marker 23 of the visualization imaging experiment to vibrate.

[0084] S113: Using a high-speed camera 27 at the same horizontal height as the visual shooting experiment displacement marker 23, the position change of the visual shooting experiment displacement marker 23 is captured laterally. The reference plane for the position change of the visual shooting experiment displacement marker 23 is symmetrically arranged with the axis of the visual shooting experiment displacement marker 23 as the axis of symmetry and the high-speed camera 27, so as to capture the real-time position of the marker change caused by vibration.

[0085] Steps one and two: Sensor measurements include acceleration measurement and strain measurement:

[0086] Step 121: Acceleration measurement includes the following steps:

[0087] S1211: An accelerometer is positioned at the end of displacement marker 23 in the visualization and imaging experiment.

[0088] S1212: Acceleration parameters at the center of a rectangular narrow channel can be obtained by connecting the hardware and transmitting the analog voltage signal to the NI acquisition system;

[0089] Step 122: Strain measurement includes the following steps:

[0090] S1222: Fiber optic strain sensors 24 are arranged in groups at different vertical heights parallel to the short side outside the rectangular narrow channel;

[0091] S1223: The voltage signal output by the fiber optic strain sensor 24 is imported into the host via the USB interface and interacts with the LabVIEW software;

[0092] Step 2: Verify the data obtained from visual imaging and sensor measurements:

[0093] Step 21: Measure the maximum position of the stainless steel rectangular plate 14, i.e., the displacement at the center of the stainless steel rectangular plate 14, using the visualization imaging method in Step 11. At the same time, measure the strain values ​​at different positions on the outer side of the stainless steel rectangular plate 14 using the sensor measurement method in Step 121. The purpose is to calculate the deflection of the stainless steel rectangular plate 14 caused by the lead-bismuth alloy flowing through the rectangular narrow channel using the integration method, and to compare the numerical relationship between the displacement and deflection at the center of the stainless steel rectangular plate 14.

[0094] Step 22: Calculate the strain-deflection integral using the strain measurement data collected in Step 122;

[0095] By comparing the results of the visualization imaging method and the strain-deflection integral method, the optimal data was obtained, and the parameter measurement of the flow-induced vibration characteristics of lead-bismuth alloy was realized.

[0096] The present invention has a complete implementation scheme, reasonable experimental parameter measurement method, convenient data acquisition, and two parallel measurement schemes for the displacement parameters studied by convective vibration. The visualization method and mechanical analysis method are compared and verified with each other, which has strong innovation.

[0097] In this embodiment, the lead-bismuth alloy is driven by a circulating pump, cooled after passing through a heat exchanger, and then flows into the experimental apparatus. Experimental parameter measurement methods include visual imaging and sensor measurement. Visual imaging involves using a high-speed camera to capture the positional changes of a marker (referring to the visual imaging experimental displacement marker 23) at the same horizontal height. The reference plane for the marker's positional changes is symmetrically arranged with the marker's axis as the axis of symmetry and the high-speed camera. Sensor measurement is used for acceleration measurement and channel plate strain measurement. Accelerometers are positioned at the end of the cylindrical marker, and the acquisition system obtains the acceleration parameters at the center of the channel plate by acquiring analog voltage signals. Fiber optic strain sensors are arranged in groups at different longitudinal heights parallel to the short side of the rectangular channel plate.

[0098] Visual imaging requires welding displacement markers at the center of two rectangular channel plates. In this invention, a marker with a diameter of 1mm and a length of 100mm is vertically welded to the center point of the outer side of the channel plate. When the channel plate vibrates, it will cause the cylindrical marker to vibrate. A high-speed camera is used to capture the change in the position of the marker laterally at the same horizontal height as the marker. The reference plane for the change in the position of the marker is symmetrically arranged with the axis of the marker as the axis of symmetry and the high-speed camera. This method can accurately and clearly capture the real-time position of the marker caused by vibration.

[0099] The sensor measurement scheme includes acceleration measurement and channel plate strain measurement. Accelerometers are positioned at the end of cylindrical markers, and the analog voltage signal is transmitted to the NI acquisition system via hardware connection to obtain the acceleration parameters at the center of the channel plate. Fiber optic strain sensors are arranged in groups at different vertical heights parallel to the short side of the rectangular channel plate. The output voltage signal of the fiber optic strain sensors is imported into the host computer via USB interface and interacts with LabVIEW software.

[0100] This invention utilizes visual imaging to measure the maximum displacement of a rectangular channel plate, specifically at its center. Simultaneously, it employs sensor measurement to measure strain values ​​at different locations on the outer side of the channel plate. The aim is to calculate the deflection of the channel plate caused by lead-bismuth alloy flowing through a narrow rectangular channel using an integral method, and to compare the numerical relationship between the displacement and deflection at the channel plate's center. This integral method for estimating the maximum displacement can be widely applied in studies where visual imaging methods are not feasible, such as the study of flow-induced vibration problems in rectangular multi-channel systems. The specific principle of the strain-deflection integral method is as follows:

[0101] The stainless steel rectangular plate 14 in this invention is a thin plate. The definition of a thin plate, based on thin plate bending theory, is that when the ratio h / l of the rectangular plate is within the range of [1 / 80~1 / 100, 1 / 5~1 / 8], the rectangular plate can be considered a "thin plate," and its stress characteristics are that the shear deformation caused by transverse shear force is negligible compared to the bending deformation. Thin plate bending occurs in both the x and y directions, but under specific conditions, most areas of the rectangular thin plate bend in only one direction, forming a cylindrical surface, as shown in Figure 1. The conditions for cylindrical bending of the thin plate are: 1) the aspect ratio l / b > 2.5; 2) the load perpendicular to the plate does not change along the long side. The dimensions of the rectangular channel plate used in this invention must meet the "thin plate" condition and the cylindrical bending condition. Therefore, in this invention, the data acquisition points for the integral method are arranged at different heights along the x-direction.

[0102] This invention proposes that fiber optic strain sensors can measure the normal strain of a rectangular thin plate in the x and y directions. After ignoring the shear stress and normal stress in the thickness direction when the thin plate is bent, the normal strain in the y direction is also ignored due to the cylindrical bending of the thin plate. Therefore, the physical equation of the bending of the rectangular channel plate in this invention is Equation (1), and Equation (2) is the numerical relationship between strain and deflection of the thin plate. Integrating Equation (2) yields the explicit expression (3) between deflection and strain. In Equation (3), the strain in the x direction is measured using a fiber optic strain sensor.

[0103] Based on the completed numerical simulation results, the deflection distribution of the rectangular thin plate of the present invention in the long and short side directions when it undergoes cylindrical bending is shown in Figure 2. It conforms to the above model simplification principle. When the bending of the long side is ignored, the deflection distribution at different lateral positions at the same height of the short side conforms to Equation (3). Furthermore, there is a deflection extremum at the center line of the rectangular plate. Then Equation (3) can be expressed as Equation (4), where x always ranges from [-b / 2, b / 2] and k is an undetermined coefficient.

[0104]

[0105]

[0106]

[0107]

[0108] In thin plate bending, the strain on the neutral plane is assumed to be 0, meaning the deflection parameter at each point is w = w(x,y). Therefore, the lateral displacement is only a function of x and y, and all points on any normal line on the neutral plane have the same lateral displacement. After introducing the assumption of cylindrical bending, the deflection distribution of a rectangular thin plate at different heights along the short side can be simplified to the bending of a slab beam, with the maximum deflection at the midpoint of the beam. Therefore, it is assumed that the maximum displacement of the rectangular thin plate at different heights is located at the central axis of the thin plate.

[0109] The heating equipment of the experimental system of this invention will be shut down after the lead-bismuth alloy circulation stabilizes. The work done by the circulation pump will cause the temperature of the lead-bismuth alloy to rise. In order to ensure that the temperature of the lead-bismuth alloy entering the experimental device meets the experimental requirements, it must be cooled to the specified temperature by a heat exchanger. The entire experimental system needs to fully insulate the equipment pipelines. Because the experimental body area of ​​the experimental device of this invention needs to be equipped with various precision measuring devices for flow-induced vibration parameters, it is not possible to cover it with aluminum silicate insulation cotton for insulation. Therefore, heating wires are wrapped around the outside of the channel plate to heat and insulate the rectangular narrow channel area in real time, ensuring that there is no temperature fluctuation of the lead-bismuth alloy flowing through the rectangular narrow channel.

[0110] The rectangular channel plate is laterally fixed by placing stainless steel shims between the two plates and fixing blocks on the outside, and then using bolts to fix it through. The upper and lower sections of the channel plate are welded to the rectangular variable diameter plate. The two sides of the rectangular variable diameter plate are vertically installed with transverse fixing plates connected to the platform fixing plate. The transverse fixing plates and the outer blocks of the channel plate are longitudinally fixed by bolts. The four sides of the rectangular channel plate are fixed by fixed support. The boundary conditions of the integral method model are set as follows: the deflection at the edge of the short side and the slope of the normal of the surface are both 0, as shown in equations (5) and (6). The aforementioned boundary conditions are used to modify the parameter k in equation (4). The following boundary conditions assume that the transverse bending at the edge of the plate caused by flow-induced vibration can be ignored, that is, the strain value is 0.

[0111]

[0112]

[0113] Specific Implementation Method Nine: Referring to Figures 1 to... Figure 9 This embodiment describes the following steps in step two: the strain-deflection integral method calculation.

[0114] S221: The integral method data acquisition points of the stainless steel rectangular plate 14 are all arranged at different heights along the x-direction.

[0115] S222: The fiber optic strain sensor 24 measures the normal strain of the stainless steel rectangular plate 14 in the x and y directions. After the stainless steel rectangular plate 14 is bent, the shear stress and normal stress in the thickness direction are ignored. The normal strain in the y direction is ignored because the thin plate undergoes cylindrical bending.

[0116] Therefore, the physical equation for the bending of a rectangular narrow channel is equation (1).

[0117]

[0118] Equation (2) represents the numerical relationship between strain and deflection of a thin plate.

[0119]

[0120] Integrating equation (2) yields the explicit expression (3) for the relationship between deflection and strain.

[0121]

[0122] In equation (3), the strain in the x-direction is measured using a fiber optic strain sensor;

[0123] S223: According to the completed numerical simulation results, when the bending of the long side is ignored, the deflection distribution of the short side at different lateral positions at the same height conforms to the formula (3), and there is a deflection extreme value at the center line of the rectangular plate. Then, the formula (3) is expressed as the formula (4), and the x range is always [-b / 2, b / 2], and k is an undetermined coefficient.

[0124]

[0125] In thin plate bending, the strain on the neutral plane is assumed to be 0, that is, the deflection parameter at each point is w = w(x,y). Therefore, the lateral displacement is only a function of x and y, and each point on any normal line on the neutral plane has the same lateral displacement.

[0126] After introducing the assumption of cylindrical bending, the deflection distribution of the rectangular thin plate along the short side at different heights can be simplified to the bending of a strip beam, with the maximum deflection at the midpoint of the beam. Therefore, it is assumed that the maximum displacement of the rectangular thin plate at different heights is at the central axis of the plate.

[0127] With this setup, the present invention measures the flow-induced vibration parameters of lead-bismuth alloys within a rectangular narrow channel under different operating conditions. Accelerometers and high-speed cameras are used to obtain key parameters such as acceleration and amplitude. Fiber optic strain sensors are used to measure strain at different locations on the channel plate, and the deflection at these locations is obtained based on the strain-deflection integral method. The results of the mechanical analysis method and the visualization imaging method can be mutually verified. The reasonable and reliable mechanical analysis model can not only be applied to single-channel flow-induced vibration parameter measurement, but more importantly, it plays a crucial role in multi-channel flow-induced vibration parameter measurement environments where visualization methods are not applicable. Vibration displacement parameters of each sub-channel plate can be calculated from the strain. Other components and connections are the same as any one of the specific embodiments one through eight.

[0128] Referring to Figure 1 to Figure 9 Explanation of the working principle of this invention:

[0129] like Figure 6The schematic diagram of the experimental system of this invention shows that the experimental system consists of an experimental device 1, a lead-bismuth storage tank 2, a filtration system 3, an air-cooled heat exchanger 6, an argon gas supply system 7, a vacuum system 8, a thermal oil furnace 9, a measurement system 10, a data acquisition system 11, a heat tracing system, a valve system, a power supply system, instruments, pumps, and pipelines. The heat tracing system heats and melts the solid lead-bismuth alloy stored in the lead-bismuth storage tank 2; the electromagnetic circulation pump 4 drives the lead-bismuth alloy to circulate within the experimental system; the air-cooled heat exchanger 6 cools the heated lead-bismuth alloy; before starting the measurement system 10 and the data acquisition system 11 to collect data from the experimental section, the filtration system 3 must be activated to filter and purify the lead-bismuth alloy throughout the loop; the argon gas supply system 7 and the vacuum system 8 protect the lead-bismuth alloy within the lead-bismuth storage tank 2.

[0130] Figure 7 and Figure 8 The diagram shows the structure of the experimental section of this invention. The lead-bismuth alloy in the lead-bismuth alloy circulation pipeline is first stored in the cylindrical chamber 12. The cylindrical chamber 12 is a "bridge" connecting the lead-bismuth alloy circulation pipeline and the experimental device, and has the functions of storage and buffering. A rectangular chamber 13 is welded between the cylindrical chamber 12 and the experimental body. The rectangular chamber 13 has a cross-section with the same size as the rectangular narrow channel. It is wrapped with aluminum silicate insulation cotton for heat preservation. The rectangular chamber 13 can buffer the lead-bismuth alloy flowing out of the cylindrical chamber 12, ensure that the flow of lead-bismuth alloy flowing into the rectangular narrow channel is fully developed, and reduce the inlet and outlet effects and flow instability.

[0131] The experimental section body (referring to the rectangular narrow channel) is enclosed by stainless steel rectangular plates 14. The narrow side dimension of the rectangular narrow channel is determined by the absolute distance between two stainless steel rectangular plates 14. The long side dimension of the rectangular narrow channel is determined by placing stainless steel gaskets 20 between the stainless steel rectangular plates 14. The stainless steel gaskets 20 serve to support and seal the rectangular narrow channel components. Fixing blocks 22 are installed on the outside of the rectangular channel plates, which serve to clamp the channel plates and have threaded holes for installing fixing bolts 19 to fix and support the stainless steel rectangular plates 14 of the experimental section. High-temperature resistant sealant is applied between the stainless steel rectangular plates 14 and the stainless steel gaskets 20 and distributed between the component connection gaps and threaded hole gaps to seal and prevent lead-bismuth alloy leakage.

[0132] A heat tracing cable 17 is wrapped around the outer wall of the stainless steel rectangular plate 14. After the lead-bismuth alloy circulates stably in the experimental system, the heat tracing cable will stop working. Since the stainless steel rectangular plate 14 is exposed to the environment and no effective heat preservation measures can be taken in this area, it is necessary to independently monitor and control the temperature of this area during the experimental data acquisition process to ensure the temperature of the lead-bismuth alloy flowing through the narrow rectangular channel is stable.

[0133] The experimental apparatus of this invention is mainly fixed by welding, bolting, and clamping. The connection and fixing scheme between the experimental apparatus and the experimental platform is as follows:

[0134] The outlet section of the cylindrical chamber 12 of the experimental section is welded to the upper surface of the experimental platform; the cylindrical chamber 12 is fixed by a mechanical clamping device 15, which is welded to the experimental section fixing plate 18; the variable diameter fixing plate 16 is vertically welded to the outside of the rectangular variable diameter 13 and welded to the experimental section fixing pad 22, the variable diameter fixing plate 16 is welded to the experimental section fixing plate 18, and the variable diameter fixing plate 16 and the fixing pad 22 are fixed in the longitudinal direction by bolts.

[0135] like Figure 9 The diagram shows the arrangement of the measuring device on the outer side of the single-sided channel plate of the present invention. The displacement marker 23 for visualization and imaging experiments is positioned at the center of the stainless steel rectangular plate 14 and welded together. Displacement reference fixing plates 25 and equipment mounting fixing plates 28 are installed on both sides of the experimental device. A high-speed camera 27 is mounted and fixed on the equipment mounting fixing plate 28 to capture the position image of the position marker 23. The displacement reference fixing plate 25 has a grooved surface and is covered with reference objects 26 that indicate the position of the marker. The displacement reference fixing plate 25, the equipment mounting fixing plate 28, and the experimental section fixing plate 18 are welded and spliced ​​together and fixed to the upper surface of the experimental platform.

[0136] An acceleration sensor is positioned at the end of position marker 23 and connected to a data acquisition system to monitor and store in real time the acceleration parameters of channel plate 14 caused by the lead-bismuth alloy flowing through the rectangular narrow channel.

[0137] Based on the requirements of thin plate bending theory and cylindrical bending theory, fiber optic strain sensors 24 are arranged in groups along the short side of stainless steel rectangular plate 14. This invention simplifies the fixing method of the four sides of stainless steel rectangular plate 14, focusing the data acquisition work on the area near the central axis of the channel plate. Therefore, each group of fiber optic strain sensors 24 has the characteristics of "dense in the middle and sparse on both sides", with the aim of obtaining as many data samples as possible in the central axis area and accurately obtaining the distribution of the strain-deflection integral model calculation results.

[0138] According to the analysis results of the cylindrical bending theory, the deflection distribution of the stainless steel rectangular plate 14 along the long side almost shows the characteristics of "large gradient at the edge and zero gradient in the middle". Therefore, the fiber optic strain sensor 14 can be arranged in the longitudinal direction according to the principle of "more and denser groups in the inlet and outlet areas and fewer and sparser groups in the central area", so as to make reasonable and effective use of experimental resources.

[0139] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make other changes within the spirit of the invention and apply it to fields not mentioned in the invention. Of course, all such changes made in accordance with the spirit of the invention should be included within the scope of protection claimed by the invention.

Claims

1. A device for measuring the characteristic parameters of flow-induced vibration of a lead-bismuth alloy, comprising two cylindrical chambers (12) and two rectangular chambers (13), wherein a rectangular chamber (13) is installed on one side of the horizontal end face of each cylindrical chamber (12), the two rectangular chambers (13) are arranged adjacent to each other and maintain a spacing equal to the length of the rectangular channel of the experimental section body, and the two cylindrical chambers (12) are arranged coaxially. characterized in that It also includes a rectangular narrow channel, a heat tracing cable (17), a clamping device (15), an electric heating wire (50), an experimental section fixing plate (18), a variable diameter fixing plate (16), a visual imaging experimental displacement marker (23), a reference fixing plate (25), an equipment mounting fixing plate (28), a high-speed camera (27), an accelerometer, and multiple fiber optic strain sensors (24). Two rectangular chambers (13) are sealed together by a narrow rectangular channel. A heating cable (17) is spirally wound around the outer surface of the narrow rectangular channel. An electric heating wire (50) is spirally wound on the outer wall of each cylindrical chamber (12). A clamping device (15) clamps the two cylindrical chambers (12). The two ends of the clamping device (15) are fixedly installed on the experimental section fixing plates (18) arranged in parallel on the left and right sides. One end of the variable diameter fixing plate (16) is installed at the upper and lower ends of the narrow rectangular channel, and the other end of the variable diameter fixing plate (16) is fixed on the experimental section fixing plate (18). A visual imaging experimental displacement marker (23) is vertically installed in the middle of the narrow rectangular channel. The equipment mounting fixing plate (28) is installed on the... On the front side of the rectangular narrow channel, a high-speed camera (27) is mounted on the equipment mounting plate (28). The high-speed camera (27) and the visual shooting experiment displacement marker (23) are at the same horizontal level, and the extended section of the visual shooting experiment displacement marker (23) is parallel to the equipment mounting plate (28). The reference plate (25) is located on the rear side of the rectangular narrow channel and is connected to the experimental section plate (18). The reference plate (25) has a groove and is covered with a reference (26) that can indicate the position of the marker. An acceleration sensor is installed at the end of the visual shooting experiment displacement marker (23). Multiple fiber optic strain sensors (24) are arranged in groups along the short side of the rectangular narrow channel. The rectangular narrow channel includes two stainless steel rectangular plates (14), two sealing strips (21), two sets of fixing pads (22), and multiple sets of fixing bolts (19). Two stainless steel rectangular plates (14) are arranged in parallel, and two sealing strips (21) are embedded in the two sides between the two stainless steel rectangular plates (14). The two stainless steel rectangular plates (14) and the two sealing strips (21) together form a rectangular cavity. Two sets of fixing pads (22) are installed on the outside of the two stainless steel rectangular plates (14) respectively, and the rectangular narrow channel is fixedly connected by multiple sets of fixing bolts (19) passing through the two stainless steel rectangular plates (14) and the two sealing strips (21). The stainless steel rectangular plate (14) is a thin plate.

2. The lead-bismuth alloy flow-induced vibration characteristic parameter measuring device according to claim 1, characterized in that: The rectangular narrow channel also includes a stainless steel gasket (20), which is installed between the inner wall of the stainless steel rectangular plate (14) and the outer wall of the sealing strip (21).

3. The lead-bismuth alloy flow-induced vibration characteristic parameter measuring device according to claim 2, characterized in that: High-temperature resistant sealant is also applied between the inner wall of the stainless steel rectangular plate (14) and the outer wall of the sealing strip (21).

4. The lead-bismuth alloy flow-induced vibration characteristic parameter measuring device according to claim 3, characterized in that: It also includes aluminum silicate insulation cotton (51), and the outer walls of the cylindrical chamber (12) and the rectangular chamber (13) are covered with aluminum silicate insulation cotton (51).

5. The lead-bismuth alloy flow-induced vibration characteristic parameter measuring device according to claim 4, characterized in that: Both the sealing strip (21) and the fixing pad (22) are long strips.

6. The lead-bismuth alloy flow-induced vibration characteristic parameter measuring device according to claim 5, characterized in that: Each group of fiber optic strain sensors (24) is installed horizontally in a manner that is dense in the middle and sparse on both sides.

7. A measuring method using the flow-induced vibration characteristic parameter measuring device of any one of claims 2 to 6, characterized in that: It includes the following steps: Step 1: Simultaneously perform visual imaging and sensor measurements; Step 11: Use visual photography to directly obtain data: S111: A visual imaging experiment displacement marker (23) with a diameter of 1 mm and a length of 100 mm is vertically welded to the center point of the outer side of a stainless steel rectangular plate (14); S112: When the stainless steel rectangular plate (14) vibrates under the impact of lead-bismuth alloy with different flow rates, it will cause the visual imaging experimental displacement marker (23) to vibrate. S113: Using a high-speed camera (27) at the same horizontal height as the visual shooting experiment displacement marker (23), the position change of the visual shooting experiment displacement marker (23) is captured laterally. The position change reference plane of the visual shooting experiment displacement marker (23) is symmetrically arranged with the axis of the visual shooting experiment displacement marker (23) as the axis of symmetry and the high-speed camera (27) to capture the real-time position of the marker change caused by vibration. Steps one and two: Sensor measurements include acceleration measurement and strain measurement: Step 121: Acceleration measurement includes the following steps: S1211: An accelerometer is positioned at the end of the displacement marker (23) in the visualization experiment. S1212: Acceleration parameters at the center of a rectangular narrow channel can be obtained by connecting the hardware and transmitting the analog voltage signal to the NI acquisition system; Step 122: Strain measurement includes the following steps: S1221: Fiber optic strain sensors (24) are arranged in groups at different vertical heights parallel to the short side outside the rectangular narrow channel; S1222: The voltage signal output by the fiber optic strain sensor (24) is imported into the host via the USB interface and interacts with the LabVIEW software; Step 2: Verify the data obtained from visual imaging and sensor measurements: Step 21: Measure the maximum position of the stainless steel rectangular plate (14) using the visualization shooting method in Step 11, that is, the displacement at the center of the stainless steel rectangular plate (14). At the same time, measure the strain values ​​at different positions on the outside of the stainless steel rectangular plate (14) using the sensor measurement method in Step 122. The purpose is to calculate the deflection of the stainless steel rectangular plate (14) caused by the lead-bismuth alloy flowing through the rectangular narrow channel using the integration method, and compare the numerical relationship between the displacement and deflection at the center of the stainless steel rectangular plate (14). Step 22: Calculate the strain-deflection integral using the strain measurement data collected in Step 122; By comparing the results of the visualization imaging method and the strain-deflection integral method, the optimal data was obtained through mutual verification, thus realizing the parameter measurement of the flow-induced vibration characteristics of lead-bismuth alloy.

8. The method of measuring according to claim 7, wherein: Step 22, the strain-deflection integral method calculation, includes the following steps: S221: The integral data collection points of the stainless steel rectangular plate (14) are all arranged at different heights along the x direction. S222: Fiber optic strain sensor (24) measures the normal strain of stainless steel rectangular plate (14) in the x and y directions. Stainless steel rectangular plate (14) is a thin plate. After the stainless steel rectangular plate (14) is bent, the shear stress and normal stress in the thickness direction are ignored. Due to the cylindrical bending of the thin plate, the normal strain in the y direction is ignored. Then: The physical equation for the bending of a rectangular narrow channel is equation (1). Equation (2) represents the numerical relationship between strain and deflection of a thin plate. In the formula For experimentally measuring strain values, h is the thickness of the plate; Integrating equation (2) yields the explicit expression (3) between deflection and strain. In equation (3), the strain in the x-direction is measured using a fiber optic strain sensor; S223: According to the completed numerical simulation results, when the bending of the long side is ignored, the deflection distribution of the short side at different lateral positions at the same height conforms to the formula (3), and there is a deflection extreme value at the center line of the rectangular plate. Then, the formula (3) is expressed as the formula (4), and the x range is always [-b / 2, b / 2], and k is an undetermined coefficient. In thin plate bending, the strain on the neutral plane is assumed to be 0, that is, the deflection parameter at each point is w=w(x,y). Therefore, the lateral displacement is only a function of x and y, and each point on any normal line on the neutral plane has the same lateral displacement. After introducing the assumption of cylindrical bending, the deflection distribution of the thin plate along the short side at different heights can be simplified to the bending of a strip beam, with the maximum deflection at the midpoint of the beam. Therefore, it is assumed that the maximum displacement of the thin plate at different heights is at the central axis of the thin plate.

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