A method and apparatus for measuring flow-induced vibration of a plate-type fuel assembly

Abstract

The application discloses a plate type fuel assembly flow-induced vibration measurement method and device, and belongs to the nuclear power field. The plate type fuel assembly flow-induced vibration measurement method comprises the following steps: firstly, flow-induced vibration test is carried out on fuel plates fixed at both ends, and strain data and displacement data of measuring points on the fuel plates are measured; a simulation model of the fuel plates is established, flow-induced vibration behavior is simulated, and the calculation result is verified with the measurement data; according to the verification result, the simulation model is iterated to obtain a calibration model with an error less than a given threshold value; flow-induced vibration test is carried out on a plate type fuel assembly test piece with multiple fuel plates, and strain data of corresponding measuring points of the fuel plates are measured; and the calibration model is used to give corresponding flow-induced vibration displacement data according to the strain data. The application further provides a plate type fuel assembly flow-induced vibration measurement device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of nuclear power, and particularly relates to a flow-induced vibration measurement method and device for plate-type fuel assemblies. BACKGROUND

[0002] The plate-type fuel assembly is a fuel form commonly used in research reactors. Since the fuel in the plate-type fuel assembly is in a thin plate structure, the flow-induced vibration behavior of the plate-type fuel assembly under the interaction of fluid force, damping force and elastic force has a significant impact on the safety and reliability of the fuel assembly.

[0003] Currently, the measurement techniques for flow-induced vibration are mainly developed based on electrical principles, optical principles and acoustic principles. Considering the adaptability to the plate-type fuel assembly, the flow-induced vibration measurement techniques developed based on electrical principles or acoustic principles are preferred. However, the measurement method of the eddy current sensor based on electrical principles will lose the structural integrity of the fuel plate, and the resistance method is strongly affected by the fluid conductivity; and the ultrasonic measurement method based on acoustic principles is difficult to apply to the application scenarios with a gap of less than 10 mm. Therefore, it is of positive significance to provide a flow-induced vibration measurement method suitable for the plate-type fuel assembly to improve the safety and reliability of the reactor core of the research reactor. SUMMARY

[0004] The purpose of the present application is to provide a flow-induced vibration measurement method for a plate-type fuel assembly, and to improve the measurement accuracy of the flow-induced vibration of the plate-type fuel assembly. The present application also provides a flow-induced vibration measurement device for a plate-type fuel assembly.

[0005] According to an embodiment of one aspect of the present application, a flow-induced vibration measurement method for a plate-type fuel assembly is provided, which comprises the following steps:

[0006] Step a): providing a fuel plate, clamping both ends of the fuel plate, and providing a fluid environment, setting a plurality of measurement points on the fuel plate, and measuring the displacement and strain of the measurement points;

[0007] Step b): establishing a simulation model of the fuel plate as a prediction model, taking the clamping state in step a) as a boundary condition, and calculating the displacement and strain of the measurement points in the fluid environment by using the prediction model;

[0008] Step c): verifying the calculation result of step b) by using the measurement result of step a), when the difference between the calculation result of step b) and the measurement result of step a) is greater than a given threshold, iteratively adjusting the prediction model parameters in step b) until the difference between the calculation result of step b) and the measurement result of step a) does not exceed the given threshold, and taking the prediction model at this time as a calibration model;

[0009] Step d): Providing a plate-type fuel assembly test piece, the plate-type fuel assembly test piece comprising an end fixture and a plurality of fuel plates, the plurality of fuel plates being arranged in parallel between two of the end fixtures; placing the plate-type fuel assembly test piece in a flow field, and measuring strain data at the measurement points of at least some of the fuel plates in the plate-type fuel assembly test piece;

[0010] Step e): Substituting the strain data of the measuring point obtained in step d) into the calibration model obtained in step c), and calculating the displacement data of the measuring point using the calibration model.

[0011] This method uses a calibration model to establish a correspondence between displacement and strain at measurement points in the fuel plate's flow field. This correspondence can be used to measure the strain at corresponding measurement points in the test flow field within the fuel plate assembly test specimen, thereby obtaining fuel plate displacement data. This method effectively simplifies the measurement of displacement data for densely packed fuel plates and avoids interference from factors such as hardware volume and fluid conductivity during acoustic or electrical displacement measurements.

[0012] Furthermore, in some embodiments, the simulation model in step a) is configured as a finite element model.

[0013] Furthermore, in some embodiments, in step a), the displacement of the measurement point is measured by an eddy current sensor, and the strain of the measurement point is measured by providing a strain sensor on the surface of the fuel plate.

[0014] The eddy current sensor can measure the normal displacement of the measuring point in a non-contact manner and correspond the normal displacement with the strain data measured by the strain sensor.

[0015] Furthermore, in some embodiments, in step a), when clamping the two ends of the fuel plate, only a clamping force is provided along the normal direction of the fuel plate.

[0016] Normal clamping can simplify the boundary conditions of the prediction model and improve the efficiency of model calculation and iteration.

[0017] Furthermore, in some embodiments, in step a), at least some of the measurement points are located at a middle position between two fixed ends of the fuel plate.

[0018] The measurement point is set in the middle of the fuel plate to measure the maximum displacement.

[0019] Furthermore, in some embodiments, in step c), the given threshold does not exceed 3%.

[0020] Further, in some embodiments, the step d) further comprises measuring the displacement of the end fixing device.

[0021] Meanwhile, the outer fuel plate and the middle fuel plate can be used to measure the vibration behavior of fuel plates under different flow field environments.

[0022] Further, in some embodiments, the step d) further comprises measuring the displacement of the end fixing device.

[0023] Further, in some embodiments, the step e) further comprises establishing the correspondence between the vibration behavior of the fuel plates in the plate type fuel assembly and the fluid parameters in the flow field according to the displacement data of the measuring points.

[0024] According to another aspect of the embodiments of the present application, a plate type fuel assembly flow induced vibration measurement system is provided, which can be used in the plate type fuel assembly flow induced vibration measurement method provided in any of the above embodiments. The system comprises:

[0025] a calibration system, which comprises a clamping mechanism, a fuel plate and a calibration measurement device, the clamping mechanism is arranged at both ends of the fuel plate and clamps the surface of the fuel plate vertically to provide clamping limit for the fuel plate; the calibration measurement device comprises a strain gauge and an eddy current sensor, the strain gauge is arranged at a measuring point on the surface of the fuel plate, and the eddy current sensor is arranged opposite to the measuring point on the surface of the fuel plate to measure the displacement of the measuring point;

[0026] a measurement system, which comprises a plate type fuel assembly test piece and a strain measurement device, the plate type fuel assembly test piece comprises end fixing devices and fuel plates, a plurality of the fuel plates are arranged in parallel between two end fixing devices, and the end fixing devices provide the same constraint as the actual working condition of the research reactor for the fuel plates; the strain measurement device comprises a plurality of strain gauges, which are arranged at measuring points on the surface of at least part of the fuel plates in the plate type fuel assembly test piece;

[0027] a calculation device, which comprises a memory and a processor, the memory stores a calculation program, and when the calculation program is executed by the processor, the calculation device can execute the calculation step in the plate type fuel assembly flow induced vibration measurement method provided in any of the above embodiments based on the data provided by the calibration system and the measurement system. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Fig. 1 is a structural schematic diagram of the calibration system in an embodiment;

[0029] Figure 2 Fig. 1 is a schematic diagram of a measurement system structure in an embodiment.

[0030] Figure 3 Fig. 2 is a schematic diagram of a fuel plate structure in a fuel assembly test piece in an embodiment.

[0031] Legend of reference numerals: 1 - fuel plate; 2 - strain gauge; 3 - eddy current sensor; 4 - clamping mechanism; 5 - end fixing device; 6 - container.

[0032] The above-described drawings are intended to provide a detailed description of the present application, so that those skilled in the art can understand the technical concept of the present application, and are not intended to limit the present application. For the sake of brevity, the above-described drawings only schematically show the structures related to the technical features of the present application, and do not strictly show the complete structures and all details according to the actual proportions. DETAILED DESCRIPTION

[0033] The present application will be further described in detail through specific embodiments in combination with the drawings.

[0034] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase that the phrase in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of one another. Those skilled in the art will understand that an embodiment of the application described herein can be combined with another embodiment in a manner not specifically mentioned in the specification.

[0035] In the description herein, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connecting", and the like should be understood in a broad sense, for example, can be movable connection, or fixed connection or integral. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0036] In the description herein, the terms indicating the orientation or position relationship such as "upper", "lower", "left", "right", "transverse", "longitudinal", "height", "length", "width", and the like are intended to accurately describe the embodiments and simplify the description, and are not intended to limit the parts or structures involved to have a specific orientation, to be installed or operated in a specific orientation, and cannot be understood as limiting the embodiments herein.

[0037] In the description herein, the terms "first", "second", and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the number, specific order or primary and secondary relationship of the technical features described. In the description herein, the meaning of "a plurality of" is at least two.

[0038] Flow-induced vibration is a vibration phenomenon caused by the interaction of fluid force, damping force and elastic force of the structure immersed in fluid or transmitting fluid. The parameters for evaluating the flow-induced vibration behavior mainly involve vibration amplitude, vibration frequency, vibration displacement, vibration mode, etc. In the field of nuclear engineering, the problem of flow-induced vibration has always been highly concerned by relevant researchers, designers, operators and other relevant personnel.

[0039] The plate-type fuel assembly is a new type of fuel assembly with compact structure, which mainly consists of a plurality of fuel plates, side plates for fixing the fuel plates, and a tube seat. Since the flow channel is separated by the fuel plates and the side plates, the coolant in the plate-type fuel assembly cannot be mixed between adjacent water gaps. Due to the disturbance splitting effect of the inlet structure of the plate-type fuel assembly, the flow of each water gap is unevenly distributed, and eventually leads to complex flow-induced vibration behavior of the fuel plate and the entire assembly. When the flow-induced vibration frequency is close to or equal to the natural frequency, it will cause severe vibration of the fuel assembly, and even cause the cladding to break, which brings great safety hazards to the stable operation of the reactor. Therefore, it is of great significance to carry out research on the flow-induced vibration of the plate-type fuel assembly.

[0040] In order to accurately measure the flow-induced vibration behavior of the plate-type fuel assembly, a suitable measurement technology needs to be developed according to its special structural characteristics. At present, the measurement technology for flow-induced vibration is mainly developed based on electrical principle, optical principle, acoustic principle, etc. Considering the adaptability to the plate-type fuel assembly, the flow-induced vibration measurement technology developed based on electrical principle or acoustic principle is the preferred technical route. According to the literature research, the measurement method based on electrical principle using eddy current sensor loses the structural integrity of the fuel plate, and the flow-induced vibration behavior of the fuel plate has a strong correlation with the structural characteristics and flow field characteristics, so this measurement method is not the best solution. The measurement technology developed based on ultrasonic principle is only applicable to the plate spacing of more than 10 mm. The measurement accuracy of the flow-induced vibration measurement technology developed based on resistance principle has a strong correlation with the fluid conductivity, and in actual application, the fluid conductivity needs to be kept constant, and the calibration method adopts a linear method. Considering the measurement accuracy and implementation method, this technology does not have popularization value.

[0041] In order to solve the above problems, an embodiment of one aspect of the present application provides a plate-type fuel assembly flow-induced vibration measurement method, which can more accurately measure the flow-induced vibration behavior of the plate-type fuel assembly, and provides technical support for studying the flow-induced vibration characteristics of the plate-type fuel assembly.

[0042] In the preferred embodiment, the method comprises the following steps:

[0043] Step a): as shown in Figure 1 , first, the data of the flow-induced vibration behavior of the fuel plate 1 under the constraint condition is measured. As shown in Figure 1The calibration system is shown, the clamping mechanism 4 is used to clamp both ends of the fuel plate 1. According to the size of the fuel plate 1, a plurality of measuring points are selected on the fuel plate 1, which can be arranged in a uniform matrix or a row of equidistant arrangement at the midpoint between the two clamping mechanisms 4. Strain gauges 2 are arranged at the measuring points to measure the strain of the fuel plate 1 at the measuring points in real time. In the preferred embodiment, the thickness of the strain gauge 2 is not more than 0.3mm, and the surface of the strain gauge 2 is coated with a waterproof coating with a thickness of not more than 0.5mm; the diameter of the data transmission line of the strain gauge 2 is also not more than 0.3mm. The calibration system is immersed in a fluid environment, such as a flowing water environment or other medium environment, the vibration behavior of the fuel plate 1 under different conditions is excited by controlling the fluid parameters, and the normal displacement at the measuring point is measured by using the eddy current sensor 3 arranged opposite to the measuring point. In the preferred embodiment, the distance between the eddy current sensor and the surface of the fuel plate 1 is set to 0.9mm-1mm.

[0044] In the preferred embodiment, the clamping mechanism 4 only provides a normal clamping force to the fuel plate 1 to simplify the constraint conditions of the fuel plate 1 and facilitate subsequent simulation analysis.

[0045] In other embodiments, the clamping mechanism 4 can also be arranged in the same fixed manner as the plate-type fuel assembly in the research reactor under actual working conditions, but in some embodiments, the fixed form under the actual working condition will hinder the measurement.

[0046] Step b): Establish a simulation model of the fuel plate 1 as a prediction model, and Figure 1 the clamping state of the clamping mechanism 4 as a boundary condition, and calculate the strain and normal displacement of the fuel plate 1 at the measuring point in the fluid environment by simulation. In the preferred embodiment, the prediction model uses the priority original model.

[0047] Step c): The measurement results of step a) are used to verify the simulation calculation results of step b). When the difference between the calculation results of step b) and the measurement results of step a) exceeds a given threshold, the prediction model parameters used in step b) are iterated, such as modifying the division method of the finite element mesh, changing the type of finite element, etc., and re-calculated. The specific iteration method can be reasonably selected by those skilled in the art according to the actual data and common knowledge. Until the calculation results of step b) and the measurement results of step a) are less than the error tolerance range, the prediction model parameters at this time are fixed as the calibration model. In the preferred embodiment, when the difference between the calculation results of step b) and the measurement results of step a) is not more than 3%, the model accuracy is considered acceptable. The calibration model can be used to establish a functional relationship between the strain and the normal displacement.

[0048] Step d): Establish a function relationship between the strain and the normal displacement of the fuel plate 1 as Figure 2The measurement system shown in the figure includes a plate-type fuel assembly test specimen, which includes two end fixtures 5. Multiple fuel plates 1 are arranged in parallel between the two end fixtures 5. Strain gauges 2 are installed at measurement points on some of the fuel plates 1 as strain measurement devices. The end fixtures 5 have the same limiting structures as those used in actual research reactor operating conditions, providing the same fixed constraints on the fuel plates 1 as in actual operating conditions. In some embodiments, in addition to providing normal clamping of the fuel plates 1, the end fixtures 5 also provide end limits along the extension direction of the fuel plates 1. The parallel fuel plates 1 can be arranged with the same spacing as in actual operating conditions, or with a gradient spacing distribution or other layout that meets analytical requirements. The plate-type fuel assembly test specimen is immersed in a flow field within a container 6. Vibrations of the fuel plates 1 are excited by setting the fluid parameters of the flow field, and strain data at the measurement points on the fuel plates 1 are measured using strain gauges 2.

[0049] In a preferred embodiment, strain gauges 2 are placed on at least the outer fuel plates 1 (position A) and the central fuel plates 1 (position B) of the plate-type fuel assembly test specimen (when the total number of fuel plates is odd, the central fuel plate 1 is selected; when the total number of fuel plates is even, one or both fuel plates 1 may be selected). In a further preferred embodiment, strain gauges 2 are placed on one or more fuel plates 1 from the outermost to the central portion of the plate-type fuel assembly test specimen at uniform or gradient intervals to ensure that the flow field characteristics of the fuel plates 1 at different positions are covered and the simulated flow-induced vibration behavior can represent the typical vibration modes of the fuel plates 1.

[0050] Specifically, if Figure 3 As shown, in a preferred embodiment, the measurement points of the fuel plate 1 are arranged in the middle of the width direction of the fuel plate 1 and arranged in a row in the vertical direction, and a strain gauge 2 is arranged at each measurement point for measurement.

[0051] Arrangement e): Substitute the strain data measured in step d) into the calibration model obtained in step c). The calibration model can provide the corresponding relationship between the strain and the normal displacement at the measurement point, thereby calculating the displacement data corresponding to the measurement data in step d).

[0052] In a preferred embodiment, Figure 3 As shown, there are multiple measurement points arranged longitudinally on the fuel plate 1. After measuring the strain at each measurement point and calculating the corresponding normal displacement, the overall vibration behavior of the fuel plate 1 can be further given according to the finite element model, and on this basis, the flow-induced vibration characteristics of the fuel plate 1 can be further analyzed.

[0053] In some embodiments, the measurement system is further provided with a point eddy current sensor 3 for measuring the displacement of the end fixture 5, such asFigure 3 As shown, the eddy current sensors 3 are arranged at the same height as the strain gauges 2, and by measuring the displacement of the end fixing device 5 during the test, further correction can be made when analyzing the overall flow-induced vibration characteristics of the fuel plate 1, so as to improve the accuracy of the flow-induced vibration analysis. The distance between the eddy current sensors 3 and the end fixing device 5 is set to 0.9-1 mm.

[0054] An embodiment of another aspect of the present application provides a fuel plate assembly flow-induced vibration measurement system for the fuel plate assembly flow-induced vibration measurement method provided in any of the foregoing embodiments, and comprises a calibration system, a measurement system, and a computing device. The calibration system adopts the calibration system as shown in Figure 1 The measurement system adopts the measurement system as shown in Figure 2 The computing device comprises a memory and a processor, wherein the memory stores a flow-induced vibration calculation program, and when the flow-induced vibration calculation program is executed by the processor, the calculation simulation steps in steps b), c), and e) can be performed based on the measurement data in steps a) and d) of the foregoing embodiments, so as to obtain the displacement data of the measurement points of the fuel plate 1, and further flow-induced vibration simulation analysis results.

[0055] Specifically, the computing device can adopt a general-purpose computer, a special-purpose computing device, a virtual machine, a cloud computing device, or the like. The flow-induced vibration calculation program can be based on a general-purpose program, or a specially developed special-purpose program.

[0056] The above embodiments are intended to further illustrate the present application in conjunction with the accompanying drawings, so that those skilled in the art can understand the technical concept of the present application. Within the scope of the present application, optimization or equivalent replacement of the method steps or part structures involved, and combination of the embodiments in different embodiments without structural and principle conflicts, all fall within the protection scope of the present application.

Claims

1. A method for measuring flow-induced vibration of a plate-type fuel assembly, characterized in that: The following steps are involved: Step a): providing a fuel plate, clamping both ends of the fuel plate, providing a fluid environment, setting a plurality of measurement points on the fuel plate, and measuring the displacement and strain of the measurement points; Step b): establishing a simulation model of the fuel plate as a prediction model, using the clamping state in step a) as a boundary condition, and using the prediction model to calculate the displacement and strain of the measurement point in the fluid environment; Step c): using the measurement result of step a) to verify the calculation result of step b), when the difference between the calculation result of step b) and the measurement result of step a) is greater than a given threshold, iterating the prediction model parameters in step b) until the difference between the calculation result of step b) and the measurement result of step a) does not exceed the given threshold, and using the prediction model at this time as a calibration model; Step d): Providing a plate-type fuel assembly test piece, the plate-type fuel assembly test piece comprising an end fixture and a plurality of fuel plates, the plurality of fuel plates being arranged in parallel between two of the end fixtures; placing the plate-type fuel assembly test piece in a flow field, and measuring strain data at the measurement points of at least some of the fuel plates in the plate-type fuel assembly test piece; Step e): Substituting the strain data of the measuring point obtained in step d) into the calibration model obtained in step c), and calculating the displacement data of the measuring point using the calibration model.

2. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1, characterized in that: The simulation model in step a) is configured as a finite element model.

3. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1 or 2, characterized in that: In the step a), the displacement of the measuring point is measured by an eddy current sensor, and the strain of the measuring point is measured by a strain sensor provided on the surface of the fuel plate.

4. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1 or 2, characterized in that: In the step a), when clamping the two ends of the fuel plate, only the clamping force is provided along the normal direction of the fuel plate.

5. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1 or 2, characterized in that: In step a), at least some of the measurement points are located in the middle between the two fixed ends of the fuel plate.

6. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1 or 2, characterized in that: In the step c), the given threshold does not exceed 3%.

7. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1 or 2, characterized in that: In the step d), the fuel plates for strain measurement include at least a fuel plate arranged outside the plate-type fuel assembly and a fuel plate arranged in the middle of the plate-type fuel assembly test piece.

8. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1 or 2, characterized in that: The step d) further includes the step of measuring the displacement of the end fixing device.

9. The method for measuring flow-induced vibration of a plate-type fuel assembly according to claim 1 or 2, characterized in that: In the step e), a corresponding relationship between the vibration behavior of the fuel plate in the plate-type fuel assembly and the fluid parameters in the flow field is established based on the displacement data of the measurement points.

10. A plate-type fuel assembly flow-induced vibration measurement system, characterized in that: A method for measuring flow-induced vibration of a plate-type fuel assembly according to any one of claims 1 to 9, comprising: A calibration system comprising a clamping mechanism, a fuel plate, and a calibration measurement device, wherein the clamping mechanism is disposed at both ends of the fuel plate and perpendicularly clamps the surface of the fuel plate to provide a clamping limit for the fuel plate; the calibration measurement device comprises a strain gauge and an eddy current sensor, wherein the strain gauge is disposed at a measurement point on the surface of the fuel plate, and the eddy current sensor is disposed relative to the measurement point on the surface of the fuel plate to measure the displacement of the measurement point; A measurement system comprising a plate-type fuel assembly test specimen and a strain measurement device, wherein the plate-type fuel assembly test specimen comprises end fixtures and fuel plates, wherein a plurality of the fuel plates are arranged in parallel between two end fixtures, wherein the end fixtures provide the fuel plates with constraints identical to those in actual operating conditions of a research reactor; and wherein the strain measurement device comprises a plurality of strain gauges disposed at measurement points on at least a portion of the fuel plate surfaces in the plate-type fuel assembly test specimen. A computing device comprising a memory and a processor, wherein the memory stores a computing program, and when the computing program is executed by the processor, the computing device is capable of performing the computing steps in the flow-induced vibration measurement method of a plate fuel assembly as described in any one of claims 1 to 9 based on the data provided by the calibration system and the measurement system.

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