Method and device for measuring flow-induced vibration of plate-type fuel assembly

Abstract

The invention discloses a method and device for measuring flow-induced vibration of a plate-type fuel assembly, and belongs to the field of nuclear power. The flow-induced vibration measurement method for the plate-type fuel assembly comprises the following steps: firstly, carrying out a flow-induced vibration test on a fuel plate of which the two ends are clamped and fixed, and carrying out measurement to obtain strain data and displacement data of a measurement point location on the fuel plate; establishing a simulation model of the fuel plate, simulating a flow-induced vibration behavior, verifying a calculation result and measurement data, and iterating the simulation model according to a verification result to obtain a calibration model with an error smaller than a given threshold value; a plate-type fuel assembly test piece with a plurality of fuel plates is used for carrying out a flow-induced vibration test, strain data of corresponding measurement points of the fuel plates are measured, and corresponding flow-induced vibration displacement data are given according to the strain data by using a calibration model. The invention further provides a plate type fuel assembly flow-induced vibration measuring device.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to a method and a device for measuring flow-induced vibration of a plate-type fuel assembly. Background Art

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

[0003] At present, the measurement technology for flow-induced vibration is mainly developed based on electrical principles, optical principles, acoustic principles, etc. Considering the compatibility with plate-type fuel assemblies, the development of flow-induced vibration measurement technology based on electrical principles or acoustic principles is the preferred technical route. However, the measurement method of eddy current sensors 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 application scenarios with gaps less than 10 mm. Therefore, providing a flow-induced vibration measurement method suitable for plate-type fuel assemblies has positive significance for improving the safety and reliability of research reactor cores. Summary of the invention

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

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

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

[0008] 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;

[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 of the measurement points of at least part 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 using the calibration model to calculate the displacement data of the measuring point.

[0011] This method establishes the correspondence between the displacement and strain of the fuel plate at the measurement point in the flow field through the calibration model. This correspondence can be used to measure the strain of the fuel plate at the corresponding measurement point in the test flow field in the plate-type fuel assembly test piece, and then obtain the displacement data of the fuel plate. This method effectively simplifies the measurement method of the displacement data of densely arranged fuel plates, and avoids the problem that the acoustic or electrical displacement measurement process is easily interfered by factors such as the volume of hardware equipment and fluid conductivity.

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

[0013] Furthermore, in some embodiments, 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 setting 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 to the strain data measured by the strain sensor.

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

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

[0017] Further, in some embodiments, in the step a), at least some of the measuring points are set 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 the step c), the given threshold does not exceed 3%.

[0020] Furthermore, in some embodiments, in the step d), the fuel plate for strain measurement includes at least a fuel plate disposed outside the plate-type fuel assembly and a fuel plate disposed in the middle of the plate-type fuel assembly test piece.

[0021] The outer fuel plate and the middle fuel plate are arranged at the same time so that the vibration behavior of the fuel plate under different flow field environments can be measured.

[0022] Furthermore, in some embodiments, the step d) also includes a step of measuring the displacement of the end fixing device.

[0023] Furthermore, in some embodiments, 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.

[0024] According to another embodiment of the present invention, a plate-type fuel assembly flow-induced vibration measurement system is provided, and the system is used for the plate-type fuel assembly flow-induced vibration measurement method provided in any of the above embodiments. The system comprises:

[0025] A calibration system, the calibration system comprising a clamping mechanism, a fuel plate and a calibration measuring device, the clamping mechanism being arranged at both ends of the fuel plate and vertically clamped on the surface of the fuel plate to provide clamping limit for the fuel plate; the calibration measuring device comprising a strain gauge and an eddy current sensor, the strain gauge being arranged at a measuring point on the surface of the fuel plate, the eddy current sensor being arranged relative to the measuring point on the surface of the fuel plate to measure the displacement of the measuring point;

[0026] A measurement system, the measurement system comprising a plate-type fuel assembly test piece and a strain measurement device, the plate-type fuel assembly test piece comprising an end fixture and a fuel plate, a plurality of the fuel plates being arranged in parallel between two of the end fixtures, the end fixtures providing the fuel plates with the same constraints as in actual working conditions of a research reactor; the strain measurement device comprising a plurality of strain gauges, the plurality of strain gauges being arranged at measurement points on at least a portion of the surface of the fuel plate in the plate-type fuel assembly test piece;

[0027] A computing device, the computing device comprising a memory and a processor, the memory storing 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 for plate-type fuel assemblies provided in any of the aforementioned embodiments based on the data provided by the calibration system and the measurement system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of a calibration system in one embodiment;

[0029] Figure 2 This is a schematic diagram of the structure of a measurement system in one embodiment;

[0030] Figure 3 Schematic diagram of the fuel plate structure in a plate-type fuel assembly test piece in one embodiment.

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

[0032] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly follow the actual proportions to draw the complete structure and all details. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0034] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0035] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a movable connection, a fixed connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0036] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0037] In the description of this article, 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 quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0038] Flow-induced vibration refers to the vibration phenomenon caused by the interaction of fluid force, damping force and elastic force on structures immersed in fluid or transmitting fluid. The parameters for evaluating flow-induced vibration behavior mainly include vibration amplitude, vibration frequency, vibration displacement, vibration mode, etc. In the field of nuclear engineering, the problem of flow-induced vibration has always received great attention from relevant researchers, designers, operators, etc.

[0039] As a new type of fuel assembly with a compact structure, the plate fuel assembly is mainly composed of several fuel plates, side plates for fixing the fuel plates, and tube seats. Since the flow channel is separated by the fuel plate and the side plate, the coolant in the plate fuel assembly cannot mix between adjacent water gaps. And due to the disturbance diversion effect of the inlet structure of the plate fuel assembly, the flow of each water gap is unevenly distributed, and eventually the fuel plate and the entire assembly undergo complex flow-induced vibration behavior. When the flow-induced vibration frequency is close to or equal to its natural frequency, it will cause the fuel assembly to vibrate violently, and even cause the cladding to be damaged, posing a great safety hazard to the stable operation of the reactor. Therefore, it is of great significance to carry out research on the flow-induced vibration of plate fuel assemblies.

[0040] In order to accurately measure the flow-induced vibration behavior of plate-type fuel assemblies, it is necessary to develop appropriate measurement technology for its special structural characteristics. At present, the measurement technology for flow-induced vibration is mainly developed based on electrical principles, optical principles, acoustic principles, etc. Considering the compatibility with plate-type fuel assemblies, the development of flow-induced vibration measurement technology based on electrical principles or acoustic principles is the preferred technical route. According to literature research, the measurement method based on electrical principles using eddy current sensors 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 its measurement method is not the best solution. The measurement technology developed based on the ultrasonic principle is only applicable to the plate spacing with a water gap greater than 10mm. The measurement accuracy of the flow-induced vibration measurement technology developed based on the resistance principle is strongly correlated with the fluid conductivity. In practical applications, the fluid conductivity needs to be kept constant, and the calibration method uses a linear method. Considering the measurement accuracy and implementation method, this technology has no promotion value.

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

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

[0043] Step a): Figure 1 As shown in FIG. 1 , the flow-induced vibration behavior data of the fuel plate 1 under constraint conditions are first measured. Figure 1The calibration system shown uses a clamping mechanism 4 to clamp the two ends of the fuel plate 1. According to the size of the hormone fuel plate 1, multiple measuring points are selected on the fuel plate 1. The measuring points can be set as a uniformly distributed matrix, or a row of equally spaced arrangements can be set at the midpoint between the two clamping mechanisms 4. A strain gauge 2 is set at the measuring point to measure the strain of the fuel plate 1 at the measuring point in real time. In a preferred embodiment, the thickness of the strain gauge 2 does not exceed 0.3mm, and the surface of the strain gauge 2 is coated with a waterproof coating with a thickness of no more than 0.5mm; the diameter of the data transmission line of the strain gauge 2 does not exceed 0.3mm. The calibration system is immersed in a fluid environment, such as a flowing water environment or other medium environment, and the vibration behavior of the fuel plate 1 under different conditions is stimulated by controlling the fluid parameters, and the normal displacement at the measuring point is measured by using an eddy current sensor 3 set relative to the measuring point. In a preferred embodiment, the spacing between the eddy current sensor and the surface of the fuel plate 1 is set to 0.9mm-1mm.

[0044] In a 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 may also be set to the same fixing method as the plate-type fuel assembly in the research reactor under actual working conditions. However, in some embodiments, the fixing method under actual working conditions may hinder the measurement.

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

[0047] Step c): Use the measurement results of step a) to verify the simulation calculation results in 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 correcting the division method of the finite element mesh, changing the type of finite element, etc., and recalculating. The specific iteration method can be reasonably selected by those skilled in the art based on actual data and common sense. Until the calculation results of step b) and the measurement results of step a) are less than the allowable error range, the prediction model parameters at this time are fixed as the calibration model. In a preferred embodiment, when the difference between the calculation results of step b) and the measurement results of step a) does not exceed 3%, the model accuracy is considered acceptable. The calibration model can be used to establish a functional relationship between strain and normal displacement.

[0048] Step d): Create Figure 2The measurement system shown. The measurement system includes a plate-type fuel assembly test piece, which includes two end fixtures 5, and a plurality of fuel plates 1 are arranged in parallel between the two end fixtures 5, wherein strain gauges 2 are arranged at the measuring points of some fuel plates 1 as strain measurement devices. The end fixtures 5 have the same limiting structure as that in the actual working conditions of the research reactor, and provide the same fixed constraints to the fuel plates 1 as in the actual working conditions. In some embodiments, the end fixtures 5 provide end limits along the extension direction of the fuel plates 1 in addition to providing normal clamping to the fuel plates 1. The parallel-arranged fuel plates 1 can be arranged in the same spacing as in the actual working conditions, or in a gradient spacing distribution or other arrangement forms that meet the analysis requirements. The plate-type fuel assembly test piece is immersed in the flow field in the container 6, and the vibration of the fuel plates 1 is excited by setting the fluid parameters of the flow field, and the strain data of the fuel plates 1 at the measuring points are measured by the strain gauges 2.

[0049] In a preferred embodiment, strain gauges 2 are arranged at least for the fuel plates 1 arranged at the outside (A position) and the fuel plates 1 at the middle (B position) of the plate-type fuel assembly test piece (when the total number of fuel plates is an odd number, the fuel plate 1 in the middle is selected, and when the total number of fuel plates is an even number, one or both of the fuel plates 1 can be selected) to measure the strain. In a further preferred embodiment, one or more fuel plates 1 are selected from the outermost to the middle of the plate-type fuel assembly test piece at uniform intervals or gradient intervals to arrange the strain gauges 2, so as to ensure that the flow field characteristics of the fuel plates 1 at different positions can be covered, and the simulated flow-induced vibration behavior can represent the typical vibration mode of the fuel plate 1.

[0050] Specifically, Figure 3 As shown, in a preferred embodiment, the measurement point of the fuel plate 1 is 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 give the corresponding relationship between the strain and the normal displacement at the measuring point, thereby calculating the displacement data corresponding to the measured data in step d).

[0052] In a preferred embodiment, Figure 3 As shown, there are multiple measuring points arranged longitudinally on the fuel plate 1. After measuring the strain at each measuring 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 as Figure 3 As shown, these eddy current sensors 3 are arranged at the same height as the strain gauge 2. By measuring the displacement of the end fixture 5 during the test, further corrections can be made when analyzing the flow-induced vibration characteristics of the fuel plate 1 as a whole to improve the accuracy of the flow-induced vibration analysis. The spacing between the eddy current sensor 3 and the end fixture 5 is set to 0.9mm-1mm.

[0054] Another embodiment of the present invention provides a plate-type fuel assembly flow-induced vibration measurement system, which is used in the plate-type fuel assembly flow-induced vibration measurement method provided in any of the above embodiments, and includes a calibration system, a measurement system, and a computing device. The calibration system uses Figure 1 The calibration system shown in the figure, the measurement system uses Figure 2 The computing device includes a memory and a processor, wherein the memory stores a flow-induced vibration computing program. When the flow-induced vibration computing program is executed by the processor, the computing simulation steps in steps b), c) and e) can be executed based on the measurement data of steps a) and d) in the above-mentioned embodiment to obtain the displacement data of the measurement point of the fuel plate 1 and further flow-induced vibration simulation analysis results.

[0055] Specifically, the computing device may be a general-purpose computer, a dedicated computing device, a virtual machine, or a cloud computing device, etc. The flow-induced vibration computing program may be written based on a general-purpose computing program, or a specially developed dedicated computing program may be used.

[0056] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the method steps or part structures involved, and the combination of implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

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 measuring points on the fuel plate, and measuring the displacement and strain of the measuring points; 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 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 of the measurement points of at least part 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 using the calibration model to calculate the displacement data of the measuring point.

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 arranging a strain sensor 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 along the normal direction of the fuel plate is provided.

5. 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), at least part of the measuring points are arranged at a middle position between 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) also 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, the calibration system comprising a clamping mechanism, a fuel plate and a calibration measuring device, the clamping mechanism being arranged at both ends of the fuel plate and vertically clamped on the surface of the fuel plate to provide clamping limit for the fuel plate; the calibration measuring device comprising a strain gauge and an eddy current sensor, the strain gauge being arranged at a measuring point on the surface of the fuel plate, the eddy current sensor being arranged relative to the measuring point on the surface of the fuel plate to measure the displacement of the measuring point; A measurement system, the measurement system comprising a plate-type fuel assembly test piece and a strain measurement device, the plate-type fuel assembly test piece comprising an end fixture and a fuel plate, a plurality of the fuel plates being arranged in parallel between two of the end fixtures, the end fixtures providing the fuel plates with the same constraints as in actual working conditions of a research reactor; the strain measurement device comprising a plurality of strain gauges, the plurality of strain gauges being arranged at measurement points on at least a portion of the surface of the fuel plate in the plate-type fuel assembly test piece; A computing device, the computing device comprising a memory and a processor, the memory storing 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-type 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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