Evaluation method for flow-induced vibration of spiral coil in liquid metal environment
Based on the dynamic characteristics of spiral coils and experimental data on internal flow-induced vibration, combined with the calculation of internal and external fluid excitation forces, a nonlinear dynamic analysis was performed using a unidirectional coupling method. This solved the problem of evaluating the flow-induced vibration of spiral coils in a liquid metal environment and enabled an accurate assessment of the coil vibration response and failure risk.
Patent Information
- Application Number
- CN202510808964.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2026-01-20
AI Technical Summary
Existing technologies are insufficient to effectively evaluate the flow-induced vibration of spiral coils in a liquid metal environment, especially considering the complex interaction between the internal two-phase flow and the external liquid metal on the coil.
Based on the dynamic characteristics of the spiral coil and experimental data of internal flow-induced vibration, the key models and parameters in the computational fluid excitation force and vibration response process are determined. The nonlinear dynamic analysis of the spiral coil is carried out by applying internal and external fluid excitation forces using a unidirectional coupling method to evaluate its vibration response and failure risk.
A highly reliable method for evaluating the flow-induced vibration of spiral coils is provided, which can accurately calculate the internal and external fluid excitation forces, assess the dynamic response and failure risk of the coil, and ensure the safety of spiral coils in liquid metal environments.
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Figure CN121365536A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of reactor structure mechanics, and particularly relates to a spiral coil flow-induced vibration evaluation method under a liquid metal environment. BACKGROUND
[0002] Liquid metal coolant material has the characteristics of stable chemical properties, strong heat conduction, etc., and has good neutron performance, so that the liquid metal reactor has become the main development reactor type. The steam generator is a key equipment of the liquid metal reactor, which is not only the main hub of heat exchange between the primary loop and the secondary loop, but also plays an important role in the radioactive shielding isolation of the primary loop. The coolant in the liquid metal reactor has a high temperature, the thermal expansion difference generated by the heat exchange equipment is large, and the structural arrangement is relatively compact, which puts forward higher requirements for the steam generator. The spiral coil steam generator can meet the above requirements due to its special structure and unique advantages. The fluid outside the tube of the spiral coil steam generator is liquid metal coolant, and the fluid inside the tube is water. The working medium inside the tube continuously absorbs the heat of the liquid metal coolant outside the tube, and the temperature continuously rises, which will experience a series of complex vapor-liquid two-phase flow and heat exchange processes from subcooled liquid, nucleate boiling, film boiling to superheated steam.
[0003] The most important vibration mechanism of the spiral coil flow-induced vibration is turbulent excitation. The spiral coil is not only subjected to the action of the axial flow of the inner flow, but also subjected to the tangential force of the viscous friction of the liquid viscosity and its speed. Due to its structural characteristics, it is also subjected to the transverse scouring of the centrifugal force perpendicular to the spiral axis. In addition, there is the Coriolis force (also known as the gyroscopic force) generated by the interaction of the rotational motion and the linear motion of the fluid. Under the joint action of these forces, the spiral coil structure begins to participate in the dynamic process. On the shell side of the steam generator, the liquid metal coolant flows transversely through the spiral coil, which will also inevitably generate a scouring force on the spiral coil, thereby inducing the vibration of the spiral coil. Therefore, it is necessary to simultaneously consider the vibration caused by the two-phase flow inside the tube (inner flow) and the vibration caused by the transverse flow of the liquid metal outside the tube (outer flow). SUMMARY
[0004] The technical problem solved by the present application is to provide a spiral coil flow-induced vibration evaluation method under a liquid metal environment, based on the dynamic characteristics of the spiral coil and the experimental data of the inner flow-induced vibration, to carry out the calculation of the fluid excitation force of the two-phase flow inside the tube and the fluid excitation force of the liquid metal scouring tube bundle outside the tube, and to obtain the response of the spiral coil by using the one-way coupling method to load the excitation force and determining the amplitude size to give the evaluation of the failure of the heat transfer tube.
[0005] The technical scheme adopted by the present application is as follows:
[0006] A spiral coil flow-induced vibration evaluation method under a liquid metal environment, comprising the following steps:
[0007] S10, based on the dynamic characteristics of the spiral coil and the flow-induced vibration experimental data, determine the key models and parameters required for calculating the fluid excitation force and the dynamic response of the spiral coil;
[0008] S20, calculate the flow-induced excitation force of the spiral coil under phase change conditions;
[0009] S30, liquid metal fluid excitation force calculation outside the tube;
[0010] S40, spiral coil vibration response calculation;
[0011] S50, spiral coil flow-induced vibration evaluation.
[0012] The step S10 specifically comprises the following steps:
[0013] S101, spiral coil dynamic characteristics experiment, obtain the natural frequency, mode shape and contact stiffness of the spiral coil;
[0014] S102, spiral coil two-phase flow-induced vibration test, during the test, the thermal parameters and fluid excitation force parameters under different working conditions in the coil are obtained, and the flow field calculation model under the same conditions is established.
[0015] The spiral coil dynamic characteristics experiment specifically comprises:
[0016] The test uses a force hammer to knock the coil excitation point to make the coil vibrate, and a laser displacement sensor is used to measure the vibration characteristics of the preset measurement points, so as to obtain the natural frequency and mode shape of the spiral coil at different positions.
[0017] The contact stiffness is obtained, specifically:
[0018] Based on the experimental results, the same structure finite element model is established and compared with the experimental results; in view of the differences between the experimental and simulation results, the contact model type and the constraint position contact stiffness are adjusted to match the different simulation results with the experimental results.
[0019] The spiral coil two-phase flow-induced vibration test specifically comprises:
[0020] Deionized water is delivered by the main pump to the preheating section for heating, and after reaching the preset temperature, it flows into the spiral coil; by gradually increasing the heating power of the spiral coil, the deionized water in the tube is heated to phase change, when the outlet thermal equilibrium contains more than 1, the outlet fluid is all vapor phase, realizing the two-phase flow of full flow type boiling in the tube; the vibration response of the coil measurement point is collected by the laser displacement sensor, and the thermal parameters and fluid excitation force parameters under different working conditions in the coil during the test are collected by the measurement and control system.
[0021] The flow field calculation model under the same condition is established, specifically: through the comparison of the thermal parameters and fluid excitation force parameters under the experimental conditions, the key parameters of the turbulent flow model, two-phase flow model, boiling heat transfer model, turbulent intensity and turbulent length scale are obtained.
[0022] The flow excitation force in the helical coil under the phase change condition is calculated, specifically:
[0023] Based on the turbulent flow model, two-phase flow model, boiling heat transfer model determined in step S102, and the key parameters of turbulent intensity and turbulent length scale under different working conditions, the turbulent flow calculation is carried out through Realizable k-ε turbulent flow model, the two-phase calculation is carried out through Eulerian multi-fluid model, and the boiling heat transfer process related calculation is carried out through CHF wall boiling model, to obtain the fluid force of the inner flow to the helical coil; the in-pipe flow field model is established, and the transient computational fluid dynamics calculation is carried out.
[0024] The transient computational fluid dynamics calculation is carried out, specifically: the fluctuating pressure of the wall position node is integrated on the wall surface to obtain the excitation of the fluid force on the inner wall of the pipe.
[0025] The pipe outer liquid metal fluid excitation force calculation is carried out, specifically: the pipe outer liquid metal fluid excitation force is obtained through the theoretical method based on the equivalent power spectral density and the analysis method based on computational fluid dynamics.
[0026] The theoretical method based on the equivalent power spectral density is:
[0027] The relationship between the equivalent power spectral densities of different pipe geometries is represented by the following formula:
[0028]
[0029] In the formula, is a reference equivalent power spectral density related to any reference length L0 and D0, L is the effective pipe length, and D is the outer diameter of the helical coil;
[0030] In order to separate the physical control parameters and compare the data of different configurations, a dimensionless form of the reference equivalent power spectral density needs to be defined, two scaling parameters f0 and p0 are used, f0 is used to scale the frequency, and p0 is used to scale the pressure, so that the dimensionless reference equivalent power spectral density is defined as:
[0031]
[0032] f0=U p / D (4)
[0033] In the formula, f R is the reduced frequency, U p represents the pitch flow velocity, and p is the density of the liquid metal;
[0034] The equivalent power density spectrum is defined as follows:
[0035] Inside the spiral coil:
[0036] Inlet of the spiral coil:
[0037] The analysis method based on computational fluid dynamics: a spiral coil tube outside flow field model is established, an SST k-w turbulence model is selected, and calculation is carried out according to the actual tube outside flow.
[0038] The wall surface grid of the coil is locally encrypted; the fluctuating pressure of the wall surface position node is integrated on the wall surface to obtain the excitation of the fluid force on the outer wall of the pipeline.
[0039] The spiral coil vibration response calculation, specifically:
[0040] According to the actual structure of the spiral coil, the excitation of the fluid force on the inner wall of the pipeline and the excitation of the fluid force on the outer wall of the pipeline are taken as inputs, while considering the nonlinear contact force caused by the gap between the tube and the support, a nonlinear dynamics analysis model of the coil is established; the finite element analysis of the nonlinear dynamics analysis model of the coil is realized through the computational fluid dynamics software, the one-way coupling method is used to load the fluid excitation inside and outside the spiral coil, and the vibration response of the coil under the action of the internal two-phase flow and the external liquid metal is obtained; the vibration response is processed to obtain the maximum amplitude y max of the spiral coil in statistics.
[0041] When performing finite element analysis of the nonlinear dynamics analysis model of the coil, there is a nonlinear contact force between the coil and the support, which provides a constraint at the gap between the coil and the support, and the constraint is the contact stiffness obtained by S101.
[0042] The spiral coil flow-induced vibration evaluation, specifically:
[0043] According to the relationship between the wear depth, the wear coefficient and the amplitude of the heat transfer tube, according to the engineering experience and the experimental data of the wear coefficient, under the joint action of the internal two-phase flow field and the external liquid metal transverse flow field of the spiral coil, the amplitude of the spiral coil is less than 0.015 times the outer diameter of the spiral coil, that is, under this working condition, the spiral coil has no failure risk caused by the turbulent excitation mechanism, that is:
[0044] y max ≤0.015d (5)
[0045] In the formula, y max is the maximum amplitude of the spiral coil, and d is the outer diameter of the spiral coil.
[0046] The beneficial effects of the present application are as follows:
[0047] (1) The present application provides a spiral coil flow-induced vibration evaluation method in a liquid metal environment. Based on the dynamic characteristics of the spiral coil and the experimental data of the flow-induced vibration of the internal flow, the two-phase model, the turbulence model, the phase change model, the turbulence intensity, the length scale required in the process of calculating the fluid excitation force, and the contact stiffness, the nonlinear contact setting required in the process of calculating the vibration response of the heat transfer tube are determined, and the calculation result has high reliability.
[0048] (2) The present application provides a spiral coil flow-induced vibration evaluation method in a liquid metal environment. Based on the CHF wall boiling model and the Euler two-phase model, the spiral coil internal flow excitation force under the phase change condition is calculated, and the transient calculation is carried out, so that the detailed frequency domain information of the excitation force can be obtained.
[0049] (3) The present application provides a spiral coil flow-induced vibration evaluation method in a liquid metal environment. The external liquid metal transverse flow field and the fluid excitation force are considered at the same time, the flow numerical simulation of the external liquid metal transverse flow scouring the tube bundle is carried out, and the pressure fluctuation data acting on the surface of the coil bundle are obtained.
[0050] (4) The present application provides a spiral coil flow-induced vibration evaluation method in a liquid metal environment. Based on the one-way coupling method, the nonlinear contact effect between the coil and the support is considered, and the fluid excitation force load inside and outside the tube is loaded at the same time, so that the dynamic response characteristics of the spiral coil are obtained.
[0051] (5) The present application provides a spiral coil flow-induced vibration evaluation method in a liquid metal environment. The criterion based on the maximum amplitude of the spiral coil is proposed, and whether the spiral coil has the risk of failure caused by turbulent excitation is evaluated. BRIEF DESCRIPTION OF DRAWINGS
[0052] In order to more clearly illustrate the embodiments of the present application, the following will briefly describe the drawings needed in the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can be obtained according to the following drawings without creating labor.
[0053] Figure 1 A flow chart of a spiral coil flow-induced vibration evaluation method in a liquid metal environment provided by the present application is shown in the figure.
[0054] Figure 2 A schematic diagram of the excitation point of the modal test is shown in the figure.
[0055] Figure 3 A comparison diagram of the experimental and calculated wall temperature along the axial position is shown in the figure.
[0056] Figure 4 For 12 layer position vertical direction transient vibration displacement: (a) numerical calculation; (b) test
[0057] Figure 5 For 12 layer position vertical direction vibration spectrum: (a) numerical calculation; (b) test
[0058] Figure 6 For example, the displacement time history response of the spiral coil;
[0059] Figure 7 For example, the displacement frequency domain response of the spiral coil. DETAILED DESCRIPTION
[0060] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.
[0061] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like are the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.
[0062] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0063] As Figure 1 shown, the present application provides a spiral coil flow-induced vibration evaluation method in a liquid metal environment, which comprises the following steps:
[0064] S10, based on the dynamic characteristics of the spiral coil and the flow-induced vibration experimental data of the internal flow, determining the key models and parameters required in the calculation of fluid excitation force and spiral coil dynamic response process
[0065] S101, Spiral coil dynamic characteristic experiment
[0066] The spiral coil dynamic characteristic experiment is carried out, and the natural frequency and mode shape of the spiral coil under different sizes and constraint conditions are obtained, which provides a reference for subsequent flow-induced vibration analysis. Figure 2 As shown in the figure, the test uses a force hammer to knock the coil excitation point to make the coil vibrate, and a laser displacement sensor is used to measure the vibration characteristics of the preset measuring point, so as to obtain the natural frequency and mode shape of the spiral coil at different positions.
[0067] According to the experimental results, the same structure finite element model is established and compared with the experimental results. In view of the differences between the experimental and simulation results, the contact model type and the constraint position contact stiffness are adjusted to match the different simulation results with the experimental results.
[0068] The natural frequency, mode shape and contact stiffness obtained in the above process are important inputs for subsequent structure modeling to ensure the accuracy of the model.
[0069] S102, Spiral coil two-phase flow-induced vibration test
[0070] The spiral coil two-phase flow-induced vibration test is carried out. Deionized water is transported by the main pump to the preheating section for heating, and after reaching the preset temperature, it flows into the spiral coil. By gradually increasing the heating power of the spiral coil, the deionized water in the coil is heated to change its phase. When the outlet thermal equilibrium contains more than 1, the outlet fluid is all vapor phase, realizing the two-phase flow of full flow type boiling in the pipe. The vibration response of the coil measuring point is collected by the laser displacement sensor, and the thermal parameters and fluid excitation force parameters under different working conditions (deionized water flow rate, heating power, etc.) in the coil during the test are collected by the measurement and control system.
[0071] For different working conditions, the flow field calculation model under the same conditions is established. By comparing the thermal parameters and fluid excitation force parameters under the experimental conditions, the key parameters such as turbulent flow model, two-phase flow model, boiling heat transfer model, turbulent intensity and turbulent length scale are obtained as input parameters for subsequent fluid force calculation.
[0072] S20: Calculate the flow excitation force in the spiral coil under phase change conditions
[0073] Based on the turbulence model, two-phase flow model, boiling heat transfer model determined in step S102, and key parameters such as turbulence intensity and turbulence length scale under different working conditions, the Realizable k-ε turbulence model is used to carry out turbulence calculation, the Eulerian multi-fluid model is used to carry out two-phase calculation, and the CHF wall boiling model is used to carry out related calculation of boiling heat transfer process, to obtain the fluid force of the inner flow on the spiral coil; the pipe inner flow field model is established, and transient computational fluid dynamics calculation is carried out: the fluctuating pressure of the wall surface position node is integrated on the wall surface to obtain the excitation of the fluid force on the inner wall of the pipe, which is used as the input of the subsequent steps of the embodiment.
[0074] Due to the turbulence effect of the spiral coil, the Scalable Wall Function is used for the wall function, and the Mixture model is selected for the turbulence multiphase model. Due to the strong secondary flow characteristics of the flow in the spiral pipe caused by the geometric structure of the spiral pipe, the Realizable k-ε turbulence model can best predict separation flow and complex secondary flow under all k-ε models.
[0075] The Eulerian multi-phase model can model multiple independent but interacting phases. These phases can be liquid, gas or solid in almost any combination. A single pressure is shared by all phases, while continuity equations, momentum equations and energy equations for each phase can be established and solved.
[0076] Compared with the non-equilibrium wall boiling model, the CHF wall boiling model considers the process of steam replacing liquid when CHF occurs, that is, the wall boiling deviates from the nucleate boiling region, and the process of the multiphase flow region changing from bubbly flow to mist flow.
[0077] S30: Calculation of liquid metal fluid excitation force outside the pipe
[0078] The flow field outside the spiral coil is single-phase flow, and compared with the complex two-phase flow in the pipe, it can obtain more accurate fluid excitation force without the need for experimental parameters correction. In this embodiment, the liquid metal fluid excitation force outside the pipe can be obtained through two technical paths: a theoretical method based on equivalent power spectral density and an analysis method based on computational fluid dynamics.
[0079] Theoretical method based on equivalent power spectral density:
[0080] The relationship between the equivalent power spectral densities of different pipe geometries is represented by the following formula:
[0081]
[0082] In the formula, is a reference equivalent power spectral density related to any reference length L0 and D0, L is the effective pipe length, and D is the outer diameter of the spiral coil.
[0083] To separate the physical control parameters and compare the data of different configurations, a dimensionless form of the reference equivalent power spectral density is defined, two scaling parameters f0 and p0 are used, f0 is used to scale the frequency, and p0 is used to scale the pressure. Thus, the dimensionless reference equivalent power spectral density is defined as:
[0084]
[0085] f0 = U p / D (4)
[0086] In the formula, f R = f / f0 is the reduced frequency. U p represents the pitch velocity, and p is the density of the liquid metal.
[0087] The equivalent power spectral density is defined as follows:
[0088] Inside the spiral coil:
[0089] At the inlet of the spiral coil:
[0090] Based on the computational fluid dynamics analysis method: a spiral coil outside the tube flow field model is established, the SST k-w turbulence model is selected, and the actual tube outside flow is calculated according to the example.
[0091] In order to better capture the pressure fluctuation characteristics near the wall region, the wall surface grid of the coil is locally encrypted; the fluctuating pressure of the wall position node is integrated on the wall surface to obtain the excitation of the fluid force on the outer wall of the pipe, which is used as the input of the subsequent steps of the example.
[0092] S40: Spiral coil vibration response calculation
[0093] According to the actual structure of the spiral coil, the excitation of the fluid force on the inner wall of the pipe and the excitation of the fluid force on the outer wall of the pipe are used as inputs, and the nonlinear contact force caused by the gap between the pipe and the support is considered. A nonlinear dynamic analysis model of the coil is established; the finite element analysis of the nonlinear dynamic analysis model of the coil is realized by using the computational fluid dynamics software, the one-way coupling method is used to load the fluid excitation inside and outside the spiral coil, and the vibration response of the coil under the action of the internal two-phase flow and the external liquid metal is obtained. The vibration response is processed to obtain the maximum amplitude y max of the spiral coil in statistics, which is evaluated in the next step.
[0094] When performing finite element analysis of the nonlinear dynamic analysis model of the coil, there is a nonlinear contact force between the coil and the support, and constraints need to be provided at the gap between the coil and the support, which are the key parameters such as contact stiffness obtained in S101.
[0095] S50: Spiral coil flow-induced vibration evaluation
[0096] The wear depth of the spiral coil is generally not more than 40% of the wall thickness under long-period operation conditions, and the wear generally occurs at the contact position between the support and the heat transfer tube. According to the relationship between the wear depth and the wear coefficient and the heat transfer tube amplitude, and according to the engineering experience and the wear coefficient experimental data, under the combined action of the two-phase flow field in the spiral coil and the transverse flow field of the liquid metal outside the spiral coil, the amplitude of the spiral coil is less than 0.015 times the outer diameter of the spiral coil, that is, under the working condition, the spiral coil has no failure risk caused by the turbulent excitation mechanism, that is:
[0097] y max ≤0.015d (5)
[0098] In the formula, y max is the maximum amplitude of the spiral coil, and d is the outer diameter of the spiral coil.
[0099] In the embodiment, the maximum amplitude of the spiral coil is 39.5 μm, which is less than 0.015 times the outer diameter of the coil (270 μm), so for the spiral coil structure, constraints and fluid conditions inside and outside the tube considered in the embodiment, the spiral coil has no failure risk.
[0100] For those skilled in the art, although the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be considered as limiting the claims involved.
[0101] In addition, it should be understood that although the present application is described according to the embodiments, each embodiment does not contain only one independent technical solution, and the description manner of the specification is only for clarity, those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments that those skilled in the art can understand.
Claims
1. A method for evaluating flow-induced vibration of a helical coil in a liquid metal environment, characterized by, It comprises the following steps: S10, based on the dynamic characteristics of the spiral coil and the flow-induced vibration experimental data, determine the key models and parameters required in the calculation of fluid excitation force and the dynamic response of the spiral coil; S20, the flow-induced force of the spiral coil under phase change condition is calculated; S30, the liquid metal fluid excitation force outside the tube is calculated; S40, the vibration response of the spiral coil is calculated; S50, the spiral coil flow-induced vibration evaluation.
2. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 1, characterized by, The step S10 specifically comprises the following steps: S101, the spiral coil dynamic characteristic experiment is carried out to obtain the natural frequency, mode shape and contact stiffness of the spiral coil; S102, the spiral coil two-phase flow-induced vibration test is carried out, and the thermal parameters and fluid excitation force parameters under different working conditions in the test process are established to build the flow field calculation model under the same condition.
3. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 2, characterized by, The spiral coil dynamic characteristic experiment specifically comprises: The test uses a force hammer to knock the excitation point of the coil to make the coil vibrate, and a laser displacement sensor is used to measure the vibration characteristics of the preset measuring point, so as to obtain the natural frequency and mode shape of the spiral coil at different positions.
4. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 3, characterized by, The contact stiffness is obtained, specifically: For the experimental results, the same structure finite element model is established and compared with the experimental results; for the differences between the experimental and simulation results, the contact model type and the contact stiffness of the constraint position are adjusted to match the different simulation results with the experimental results.
5. The method for evaluating flow-induced vibration of a helical coil in a liquid metal environment according to claim 2, characterized by, The spiral coil two-phase flow-induced vibration test specifically comprises: Deionized water is delivered to the preheating section by the main pump for heating, and after reaching the preset temperature, it flows into the spiral coil; by gradually increasing the heating power of the spiral coil, the deionized water in the coil is heated to phase change, when the outlet thermal equilibrium contains more than 1 steam, the outlet fluid is all vapor phase, realizing the two-phase flow of full flow type boiling in the pipe, the vibration response of the coil measuring point is collected by the laser displacement sensor, and the thermal parameters and fluid excitation force parameters under different working conditions in the test process are collected by the measurement and control system.
6. The method for evaluating flow-induced vibration of a helical coil in a liquid metal environment according to claim 5, characterized by, The flow field calculation model under the same condition is established, specifically: by comparing the thermal parameters and fluid excitation force parameters under the experimental conditions, the key parameters of the turbulent flow model, two-phase flow model, boiling heat transfer model, turbulent intensity and turbulent length scale are obtained.
7. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 6, characterized by, The calculation of the flow-induced force of the spiral coil under the phase change condition is carried out, specifically: Based on the turbulent flow model, two-phase flow model, boiling heat transfer model, and the key parameters of turbulent intensity and turbulent length scale under different working conditions determined in step S102, the Realizable k-ε turbulent flow model is used to carry out turbulent flow calculation, the Eulerian multi-fluid model is used to carry out two-phase calculation, and the CHF wall boiling model is used to carry out related calculation of boiling heat transfer process, to obtain the fluid force of the inner flow to the spiral coil; The flow field model in the pipe is established to carry out transient computational fluid dynamics calculation.
8. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 7, characterized by, The transient computational fluid dynamics calculation is carried out, specifically: the fluctuating pressure of the wall position node is integrated on the wall surface to obtain the excitation of the fluid force on the inner wall of the pipe.
9. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 8, characterized by, The liquid metal fluid excitation force outside the tube is calculated, specifically: the liquid metal fluid excitation force outside the tube is obtained by the theoretical method based on the equivalent power density spectrum and the analysis method based on computational fluid dynamics.
10. The method for evaluating flow-induced vibration of a helical coil in a liquid metal environment according to claim 9, characterized by, The theoretical method based on the equivalent power spectral density: The relationship between the equivalent power spectral densities of different tube geometries is expressed by the following equation: wherein is a reference equivalent power spectral density associated with any reference length L0and D0, L is the effective tube length, and D is the helical coil outer diameter; To separate the physical control parameters and compare the data of different configurations, a dimensionless form of the reference equivalent power spectral density needs to be defined. Two scaling parameters f0 and p0 are used, f0 for scaling the frequency and p0 for scaling the pressure, so that the dimensionless reference equivalent power spectral density is defined as: f0 = U p / D (4) where f R = f / f0is the reduced frequency, U p represents the pitch velocity, and p is the density of the liquid metal. The equivalent power spectral density is defined as follows: Spiral coil interior: Spiral coil inlet:
11. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 10, characterized by, The analysis method based on computational fluid dynamics: a model of the flow field outside the spiral coil is established, the SST k-w turbulence model is selected, and the calculation is carried out according to the actual flow rate outside the tube.
12. The method for evaluating flow-induced vibration of a helical coil in a liquid metal environment according to claim 11, characterized by, The wall surface grid of the coil is locally encrypted; the fluctuating pressure of the wall surface position node is integrated on the wall surface to obtain the excitation of the fluid force on the outer wall of the pipe.
13. The method for evaluating flow-induced vibration of a helical coil in a liquid metal environment according to claim 12, characterized by, The spiral coil vibration response calculation, specifically: According to the actual structure of the spiral coil, the fluid force excitation on the inner wall of the pipe and the fluid force excitation on the outer wall of the pipe are taken as inputs, and a nonlinear dynamic analysis model of the coil is established by considering the nonlinear contact force caused by the gap between the pipe and the support; the finite element analysis of the nonlinear dynamic analysis model of the coil is realized by using a computational fluid dynamics software, the fluid excitation inside and outside the spiral coil is loaded by using a one-way coupling method, and the vibration response of the coil under the action of the internal two-phase flow and the external liquid metal is obtained; the vibration response is processed to obtain the maximum amplitude y of the spiral coil in statistics max .
14. The liquid metal environment helical coil flow-induced vibration evaluation method according to claim 13, characterized by, When performing finite element analysis of the nonlinear dynamics analysis model of the coil, there is a nonlinear contact force between the coil and the support, which provides a constraint at the gap between the coil and the support, and the constraint is the contact stiffness obtained by S101.
15. The method for evaluating flow-induced vibration of a helical coil in a liquid metal environment according to claim 14, characterized by, The spiral coil flow-induced vibration evaluation, specifically: According to the relationship between the wear depth, the wear coefficient and the heat transfer tube amplitude, according to the engineering experience and the experimental data of the wear coefficient, under the joint action of the internal two-phase flow field and the external liquid metal transverse flow field of the spiral coil, the amplitude of the spiral coil is less than 0.015 times the outer diameter of the spiral coil, that is, under this working condition, the spiral coil has no failure risk caused by the turbulent excitation mechanism, that is: y max ≤0.015d (5) In the formula, y max is the maximum amplitude of the spiral coil, and d is the outer diameter of the spiral coil.