Transient Analysis Method and System for Helium Leakage in Nuclear Fusion Devices

Abstract

This invention discloses a method and system for transient analysis of helium leakage in a nuclear fusion device, relating to the field of nuclear fusion safety analysis technology. The method includes the following steps: obtaining the structural parameters and operating parameters of the Dewar radiator of the nuclear fusion device; dividing the internal space of the Dewar radiator into multiple interconnected control volumes based on the structural parameters; establishing a set of transient analysis equations containing target physical quantities for each control volume based on the operating parameters; solving the transient analysis equations using a variable step-size integration method to obtain the transient time histories of the target physical quantities in each control volume; and converting the transient time histories of the target physical quantities into load data files recognizable by the target engineering analysis platform. This method, by dividing the internal space of the Dewar radiator into control volumes and solving the helium leakage transient process based on the divided structures, can accurately predict the pressure and temperature evolution under leakage accidents and generate load files that can be directly used for structural safety assessment, thus improving the efficiency of safety analysis and design optimization capabilities.

Description

Technical Field

[0001] This invention relates to the field of nuclear fusion safety analysis technology, and in particular to a method and system for transient analysis of helium leakage in a nuclear fusion device. Background Technology

[0002] Helium leakage may occur in nuclear fusion devices during operation due to various reasons. The process is accompanied by complex transient phenomena such as high-speed jetting, local pressure fluctuations, and diffusion mixing. Rapid and accurate calculable analysis is required to provide key load inputs for design and safety assessment.

[0003] Currently, two main analytical methods are used in engineering for helium leak analysis: The first is the simplified lumped parameter method, which treats the entire Dewar space as a single, uniform control volume. While this method is fast, it cannot reflect the uneven pressure distribution, local blockages, and differences in diffusion paths caused by the complex internal structure, often resulting in overly conservative or distorted analysis results. The second method is detailed simulation based on computational fluid dynamics. Although this method has high accuracy, the modeling is complex and the computation time is too long, making it difficult to meet the needs of rapid iteration and multi-condition comparison in the early stages of design.

[0004] Furthermore, existing methods suffer from a disconnect between physical process simulation and engineering load output. The ultimate goal of safety analysis is to provide accurate load inputs for structural design and evaluation, but traditional analysis results often lack automatic conversion interfaces, requiring extensive manual post-processing to generate pressure and temperature time-history loads usable by structural analysis software, which is inefficient and prone to errors. Summary of the Invention

[0005] The purpose of this invention is to propose a transient analysis method and system for helium leakage in nuclear fusion devices, so as to reasonably characterize the influence of the complex interconnected structure inside the Dewar on the gas flow and heat exchange process, achieve efficient solution of transient processes, and directly output standardized engineering loads, thereby supporting rapid safety assessment and design optimization.

[0006] In a first aspect, embodiments of the present invention propose a transient analysis method for helium leakage in a nuclear fusion device, comprising the following steps: obtaining the Dewar structural parameters and operating parameters of the nuclear fusion device; dividing the internal space of the Dewar into multiple interconnected control volumes based on the structural parameters; establishing a transient analysis equation set containing a target physical quantity for each control volume based on the operating parameters; solving the transient analysis equation set using a variable step-size integration method to obtain the transient time history of the target physical quantity in each control volume; and converting the transient time history of the target physical quantity into a load data file recognizable by the target engineering analysis platform.

[0007] In some embodiments, the structural parameters include at least: the effective gas volume inside the Dewar, the layout of the internal partitions and supporting components, and the location and geometric parameters of the connecting channels, gaps, valves, pressure relief ports and exhaust ports; the operating parameters include at least: the location and equivalent leakage area parameters of the helium leakage source, the upstream pressure and temperature parameters on the helium source side, the initial pressure and temperature distribution inside the Dewar, and the material properties and thermal boundary conditions of the walls or cryogenic components that exchange heat with the gas inside the Dewar.

[0008] In some embodiments, dividing the internal space of the Dewar into multiple interconnected control bodies includes: determining the boundaries of the control bodies based on the physical separation of the internal partitions and the narrowness of the passageways; and dividing the areas adjacent to leakage sources, pressure relief ports, exhaust ports, or strong heat exchange walls into independent control bodies.

[0009] In some embodiments, the transient analysis equation set includes a mass conservation equation and an energy conservation equation, wherein:

[0010] The mass conservation equation is: ;

[0011] The energy conservation equation is as follows:

[0012] in, For time, For control body Internal helium mass, To control adjacent entities Inflow control body mass flow rate, To control body Flow to adjacent control bodies mass flow rate, Injecting helium leak source into control body mass flow rate, For control body Internal gas relative to internal energy For control body Enthalpy of internal gas For control body Net heat exchange capacity with the wall or component.

[0013] In some embodiments, the mass flow rate of the helium leakage source is dynamically selected based on the real-time pressure ratio between the upstream and downstream. When the pressure ratio is lower than the critical pressure ratio, a choked flow model is used for calculation; when the pressure ratio is higher than the critical pressure ratio, a non-choked flow model is used for calculation.

[0014] In some embodiments, the mass flow rate between adjacent control volumes is calculated using the following formula:

[0015]

[0016] in, For control body Internal gas density, For control body With adjacent control bodies The channel flow coefficient of the connected channel. For control body With adjacent control bodies The equivalent circulation area of ​​the passageway, including the channel. For control body pressure, For control body pressure, It is a symbolic function.

[0017] In some embodiments, the target physical quantities include at least the pressure, temperature, and helium mass of each control volume; the load data file includes a pressure time history file, a temperature boundary time history file, or a heat flux boundary time history file.

[0018] In some embodiments, the step size in the variable step size integration method is expressed by the following formula:

[0019]

[0020] in, For time step, , For control coefficients, For the maximum allowed time step, , These are the rate of change in mass and the rate of change in temperature, respectively.

[0021] In some embodiments, the method is implemented using Matlab.

[0022] Secondly, embodiments of the present invention propose a transient analysis system for helium leakage in a nuclear fusion device, comprising: an acquisition module for acquiring the Dewar structural parameters and operating parameters of the nuclear fusion device; a partitioning module for dividing the internal space of the Dewar into multiple interconnected control volumes based on the structural parameters; an establishment module for establishing a transient analysis equation set containing target physical quantities for each control volume based on the operating parameters; a solution module for solving the transient analysis equation set using a variable step-size integration method to obtain the transient time history of the target physical quantity in each control volume; and a conversion module for converting the transient time history of the target physical quantity into a load data file recognizable by the target engineering analysis platform.

[0023] The transient analysis method and system for helium leakage in a nuclear fusion device according to embodiments of the present invention first acquires the structural parameters and operating conditions of the Dewar radiator of the nuclear fusion device during helium leakage transient analysis. Then, based on the structural parameters, the internal space of the Dewar radiator is divided into multiple interconnected control volumes. Next, for each control volume, a set of transient analysis equations containing target physical quantities is established based on the operating conditions, and the transient analysis equations are solved using a variable step-size integration method to obtain the transient time histories of the target physical quantities in each control volume. Finally, the transient time histories of the target physical quantities are converted into load data files recognizable by the target engineering analysis platform. Therefore, by dividing the internal space of the Dewar radiator into control volumes and solving the helium leakage transient process based on the divided structures, the pressure and temperature evolution under leakage accidents can be accurately predicted, and load files that can be directly used for structural safety assessment can be generated, improving the efficiency of safety analysis and design optimization capabilities. Attached Figure Description

[0024] Figure 1 This is a flowchart of the transient analysis method for helium leakage in a nuclear fusion device according to an embodiment of the present invention;

[0025] Figure 2 This is a flowchart of a transient analysis method for helium leakage in a nuclear fusion device according to a specific embodiment of the present invention;

[0026] Figure 3 This is a structural block diagram of the transient analysis system for helium leakage in a nuclear fusion device according to an embodiment of the present invention. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] For helium leakage accidents that may occur during the operation or testing of helium working system in nuclear fusion devices (including but not limited to cryogenic helium loops, valve boxes and distribution pipelines, vacuum chamber surrounding space and related equipment compartments), existing engineering analysis methods generally suffer from problems such as "difficulty in balancing accuracy and efficiency, inability to support long-term processes, and difficulty in forming reusable multiphysics coupling analysis links." Based on this, the technical problems to be solved by this invention can be summarized as follows:

[0029] (1) High-efficiency transient solution problem under large-scale complex geometry

[0030] In nuclear fusion device models characterized by large scale, complex spatial structures, numerous obstacles, and tortuous flow paths, traditional 3D CFD (Computational Fluid Dynamics) methods require extremely large mesh sizes and small time steps to maintain numerical stability and accuracy. This results in long computation cycles and high resource consumption, making it difficult to meet the requirements for rapid assessment and parameter iteration over long periods (from the initial leakage injection to the diffusion stabilization / ventilation dissipation stage) under leakage accident conditions. Therefore, a method and system are needed that can significantly reduce computational costs and improve transient solution efficiency while maintaining engineering-usable accuracy.

[0031] (2) Problem description of "system-level response + spatial distribution"

[0032] Helium leakage involves not only jetting and compressible effects near the local leak point, but also is closely related to upstream helium supply loops, valve opening changes, cavity coupling, ventilation boundaries, and heat exchange conditions. In existing technologies, system-level tools often struggle to provide spatial distribution data, while space-level CFD struggles to efficiently incorporate complex piping networks and dynamic boundaries, resulting in fragmented analysis chains. Therefore, a unified modeling and solution mechanism is needed that can dynamically update the leakage source strength as the system state changes, and output the time histories of key spatial field quantities, all within a single platform or unified framework.

[0033] (3) Traceable output of time histories of key field quantities and engineering loads

[0034] In engineering, it is not only necessary to obtain the concentration or leakage rate, but also to form a load input that can be directly used for subsequent verification and evaluation, such as:

[0035] ① Pressure-time curve and pressure fluctuation envelope inside the Dewar fusion device;

[0036] ② Temperature-time curves, temperature drop rates, and boundaries required for thermal shock assessment of key components;

[0037] ③ Equivalent heat transfer boundary, convective heat transfer coefficient, or heat flux time history for thermal-structural or fluid-structure interaction.

[0038] Existing methods generally lack a unified standard and automated process for “engineering-oriented, load-oriented, and interface-oriented output” of leakage transient results, which leads to subsequent analysis relying on manual extraction and conversion, affecting efficiency and traceability.

[0039] (4) Open coupling with mainstream engineering simulation platforms and process automation issues

[0040] Because the design verification of nuclear fusion devices typically requires further multidisciplinary work, including thermal-structural analysis, structural strength verification, localized frost risk assessment, and equipment-level reliability assessment, helium leak transient analysis must possess data interfaces, boundary mapping, and batch processing workflows with mainstream tools such as Abaqus, ANSYS, Fluent, and STAR-CCM+. Existing dedicated accident analysis software or closed-source tools have limitations in secondary development, result controllability, and data exchange standardization, making it difficult to form a scalable engineering workflow. Therefore, a simulation system based on an open platform is needed, capable of supporting model parameterization, batch operating condition calculations, automatic result export, and multiphysics coupling.

[0041] (5) Parametric modeling and rapid scenario evaluation for engineering applications

[0042] Nuclear fusion devices involve various combinations of leakage scenarios during the design and operation phases, such as leak orifice size, leak location, initial pressure / temperature, valve action strategies, ventilation conditions, and compartment connectivity. Existing technologies struggle to complete a large number of scenario scans and sensitivity analyses within an acceptable timeframe and lack a unified parameter management and result comparison mechanism. Therefore, an integrated method and system is needed that enables parameterized input of operating conditions, automatic solution, indexed output, and comparative evaluation.

[0043] To address the aforementioned technical problems, this invention proposes a transient analysis method and system for helium leakage in nuclear fusion devices. It establishes a unified transient solution framework encompassing the internal space of the nuclear fusion device's Dewar fin and its boundaries with the cryogenic system, pipelines, and valve boxes, connecting the leakage source, the internal space of the Dewar fin, the structural and thermal boundaries, and external coupling software. This framework significantly improves the efficiency of long-term process analysis while ensuring engineering-usable accuracy, and can automatically convert the results into load inputs required for thermal-structural / fluid-structure interaction.

[0044] The transient analysis method and system for helium leakage in a nuclear fusion device according to embodiments of the present invention are described below with reference to the accompanying drawings.

[0045] Figure 1 This is a flowchart of the transient analysis method for helium leakage in a nuclear fusion device according to an embodiment of the present invention.

[0046] In embodiments of the present invention, the transient analysis method for helium leakage in a nuclear fusion device is implemented using Matlab. For example... Figure 1 As shown, the transient analysis method for helium leakage in a nuclear fusion device includes the following steps:

[0047] S11, obtain the Dewar structural parameters and operating parameters of the nuclear fusion device.

[0048] In some embodiments of the present invention, the structural parameters include at least: the effective gas volume inside the Dewar, the layout of the internal partitions and supporting components, and the location and geometric parameters of the connecting channels, gaps, valves, pressure relief ports and exhaust ports; the operating parameters include at least: the location of the helium leakage source (such as the helium supply pipe section) and the equivalent leakage area parameters, the upstream pressure and temperature parameters on the helium source side, the initial pressure and temperature distribution inside the Dewar, and the material properties and thermal boundary conditions (such as temperature or thermal resistance) of the walls or cryogenic components (such as cold shields, supports, linings, etc.) that exchange heat with the gas inside the Dewar.

[0049] For example, the internal space of the Dewar can be parameterized in Matlab (including structural and operational parameters), providing a unified data structure for subsequent discretization and solution. It should be noted that this step uses engineering data as input, without limitation on the geometric format; it can come from simplified CAD results, field surveys, or existing modeling libraries.

[0050] S12, based on structural parameters, divides the internal space of the Dewar into multiple interconnected control volumes.

[0051] In some embodiments of the present invention, the internal space of the Dewar is divided into multiple interconnected control bodies, including: determining the boundaries of the control bodies based on the physical separation of the internal partitions and the narrowness of the passages; and dividing the areas adjacent to the leakage source, pressure relief port, exhaust port or strong heat exchange wall into independent control bodies.

[0052] Specifically, the internal space of the Dewar can be divided into several Control Volumes (CVs) based on structural parameters, and the connecting channels (channels / gap / valve / openings) between each control volume can be defined to form a spatial network model. Each control volume includes at least state variables such as volume, gas mass, pressure, and temperature, and each connecting channel includes parameters such as flow area and equivalent flow resistance / flow coefficient, all of which can be derived from operating parameters.

[0053] The equation of state for controlling helium gas in the atmosphere (either an ideal gas or a modified model) is as follows:

[0054]

[0055] in, For control body Pressure, unit: Pa; For control body Effective volume, in m³; For control body Mass of internal helium gas, in kg; For control body Temperature, in Kelvin (K). is the gas constant of helium, in J / (kg·K).

[0056] By abstracting the complex internal space and connecting channels of the Dewar into a "control volume and connected network", efficient solutions can be obtained for the long-term history of subsequent helium leakage while ensuring the accuracy available for engineering applications.

[0057] S13, for each control body, establish a set of transient analysis equations containing the target physical quantities based on the operating parameters.

[0058] In some embodiments of the present invention, the transient analysis equation set includes a mass conservation equation and an energy conservation equation, wherein:

[0059] The mass conservation equation is: ;

[0060] The energy conservation equation (primarily controlling the internal energy of gases within the body) is:

[0061] in, Time, in seconds; For control body Mass of internal helium gas, in kg; To control adjacent entities Inflow control body Mass flow rate, in kg / s; To control body Flow to adjacent control bodies Mass flow rate, in kg / s; Injecting helium leak source into control body Mass flow rate, in kg / s; For control body Internal energy specific to internal gases, expressed in J / kg; For control body Specific enthalpy of internal gas, unit J / kg; For control body Net heat exchange capacity with a wall or component (heat input is positive), in W.

[0062] If we use the ideal gas approximation, we have: , .in, Specific heat capacity at constant volume, unit: J / (kg·K); Specific heat capacity at constant pressure, unit: J / (kg·K); For control body Temperature, measured in Kelvin (K).

[0063] For example, the mass flow rate of the helium leakage source is dynamically selected based on the real-time pressure ratio between the upstream and downstream. When the pressure ratio is lower than the critical pressure ratio, the choked flow model is used for calculation; when the pressure ratio is higher than the critical pressure ratio, the non-choked flow model is used for calculation.

[0064] Specifically, a source strength model can be established for the leak point from "upstream (helium supply side) to downstream (Dewar internal control body)". Based on the real-time pressure ratio between upstream and downstream, critical (blocked) flow and non-blocked flow can be automatically identified. Then, based on the identification results, a calculation model can be selected to calculate the leak mass flow rate. .

[0065] The congested flow model is expressed by the following equation:

[0066]

[0067] The non-blocking flow model (expressed using a compressible orifice) is represented by the following equation:

[0068]

[0069] in, The mass flow rate of the helium leak source is expressed in kg / s. Flow coefficient / outflow coefficient, unitless; The equivalent area of ​​the leak is expressed in m². The upstream total pressure of the leak is expressed in Pa. The total upstream temperature of the leak, in Kelvin (K). The leakage downstream pressure (corresponding to the pressure of a certain control body inside the Dewar), in Pa; Specific heat ratio, isobaric specific heat capacity / isochoric specific heat capacity, unitless; is the gas constant of helium, in J / (kg·K).

[0070] By incorporating the leakage source strength, valve and discharge boundary actions, mass exchange between control bodies, and gas-wall heat exchange into the same time-progressive process, transient evolution calculations with traceable results can be achieved.

[0071] In some examples, the mass flow rate between adjacent control volumes is calculated using the following formula:

[0072]

[0073] in, For control body Internal gas density, in kg / m³; For control body With adjacent control bodies The channel flow coefficient of the connected channel, without units; For control body With adjacent control bodies The equivalent flow area of ​​the passageway, including the passageway itself, in m². For control body Pressure, unit: Pa; For control body Pressure, unit: Pa; It is a symbolic function with no unit.

[0074] Specifically, a "pressure difference driven" mass flow rate model can be established for the connecting channels between control volumes, as shown in the above equation. In engineering applications, an equivalent orifice model (which is also compressible) or a simplified resistance model can be used. This model is suitable for small pressure differences and rapid engineering evaluation. For valve actions and pressure relief port opening, these can be controlled in Matlab using a "time-opening curve" or logical conditions. or This enables dynamic boundaries.

[0075] In some embodiments of the present invention, heat transfer modeling of the gas-structure / wall inside the Dewar is also performed, that is, convective heat transfer model and conductive thermal resistance model are established for key walls / components inside the Dewar (e.g., cold shield, inner wall, support members).

[0076] Convection heat transfer:

[0077]

[0078] in, For control body The amount of heat transferred in convective heat transfer, expressed in W; For control body The corresponding convective heat transfer coefficient, in W / (m²·K); For control body Heat exchange area, in m²; To control the body Temperature of a wall or component undergoing convective heat transfer, in Kelvin (K). For control body Gas temperature, in Kelvin (K).

[0079] Conductive thermal resistance model, i.e., wall heat capacity model (wall temperature can participate in transients):

[0080]

[0081] in, To control the body Equivalent mass of a wall or component in convective heat transfer, in kg; To control the body Specific heat of walls or components undergoing convective heat transfer, expressed in J / (kg·K); To control the body The heat power absorbed by a wall or component in convective heat transfer, measured in W; To control the body The heat power released by a wall or component undergoing convective heat transfer, measured in W.

[0082] S14. The transient analysis equations are solved using the variable step-size integration method to obtain the transient time history of the target physical quantities in each control volume.

[0083] In some embodiments of the present invention, the step size in the variable step size integration method is expressed by the following formula:

[0084]

[0085] in, The time step is expressed in seconds (s). , This is a control coefficient (stability / accuracy parameter), without units; The maximum allowed time step, in seconds; , These are the rate of change of mass (unit: kg / s) and the rate of change of temperature (unit: K / s), respectively.

[0086] Specifically, the system of ordinary differential equations obtained in step S14 is integrated over time in Matlab. To balance the rapid changes in the initial stage of leakage with the slow diffusion / heat transfer in the later stage, adaptive time step control can be introduced, for example, based on a relative rate of change constraint, as shown in the above equation. Therefore, stability and efficiency can be guaranteed through time integration and adaptive step size control.

[0087] S15 converts the transient time history of the target physical quantity into a load data file that can be recognized by the target engineering analysis platform.

[0088] In some examples, the target physical quantities include at least the pressure, temperature, and helium mass of each control volume; the load data files include pressure time history files, temperature boundary time history files, or heat flux boundary time history files.

[0089] Specifically, the transient results of each control volume within the Dewar interior space can be converted into engineering-usable outputs, including:

[0090] ①Key areas inside Dewar , , , ;

[0091] ② Pressure load time history and temperature boundary time history for structural analysis;

[0092] ③ Convective boundary facing thermal-structural coupling ( , Or equivalent heat flux).

[0093] The heat flux time history of a typical boundary can be generated using the following formula (for structural thermal analysis):

[0094]

[0095] in, Heat flux per unit area, in W / m²; The convective heat transfer coefficient is expressed in W / (m²·K). The mainstream gas temperature (which can be taken as the corresponding control volume temperature), in K; The temperature is the wall surface temperature, in Kelvin (K).

[0096] The aforementioned time histories can be automatically exported as load files (such as CSV / tabular time histories / amplitude curves) recognizable by the target engineering analysis platform (such as Abaqus, ANSYS, Fluent, STAR-CCM+), and a mapping relationship between the "control volume and structural surface" can be provided to achieve rapid coupling and calling. By automatically converting the transient calculation results of the Dewar interior space into load time histories such as pressure, temperature, and convection boundary loads that can be directly used for structural and thermal analysis, and outputting mapping relationships and logs, manual processing and interface inconsistency issues can be reduced.

[0097] In some embodiments of the present invention, the accuracy and efficiency of transient calculation can be improved by "reconstruction of the Dewar internal space adaptive control volume and online identification of connectivity parameters".

[0098] Specifically, in the early stage of leakage (when the pressure and temperature gradients are steep), the control volume of key areas and the equivalent parameters of connecting channels (such as equivalent flow area, flow coefficient, and local volume ratio) are automatically refined. In the later stage of leakage (when the field changes gradually slow down), the control volumes are automatically merged to reduce the equation scale. At the same time, the existing measurement points (pressure, temperature, flow rate, or helium leak detection signals) in Dewar are used to identify and correct the uncertain parameters in the model online. This enables the model to achieve dual self-adaptation of "dynamically adjusting resolution with the process and dynamically correcting parameters with the data" without introducing a three-dimensional CFD mesh, thereby maintaining a balance between high efficiency and engineering accuracy under long-term process conditions.

[0099] Therefore, based on the characteristics of pressure and temperature changes and the monitoring rules for key areas, the system automatically refines local spaces and merges slowly changing areas, achieving a dynamic balance of "high resolution in the early stages of leakage and high efficiency in the later stages." By utilizing existing measurement data from Dewar's, rolling corrections can be made to connectivity and heat transfer correction parameters that are difficult to define precisely, reducing the impact of uncertainties on calculation conclusions and improving consistency with reality.

[0100] In some embodiments of the present invention, the availability and traceability of coupling analysis can be improved by “automatic compression of load time history and generation of structural surface mapping for multi-physics coupling”.

[0101] Specifically, for the time-history data such as pressure, temperature, and convective heat transfer coefficient obtained from the internal space of the Dewar, key feature points are automatically extracted and error-controlled time-history compression is performed (e.g., piecewise linearization based on the rate of change threshold and energy conservation error constraints), significantly reducing the size of the load data; and based on the predefined "control volume-structure surface" association rules, partitioned load files and boundary condition sets that can be directly called by structural platforms such as Abaqus / ANSYS are automatically generated, realizing end-to-end automation from leakage transient solution to the application of thermal-structural / fluid-structure interaction loads, reducing the errors and time costs caused by manual processing and format conversion.

[0102] Therefore, by automatically compressing load curves such as pressure and temperature while retaining event points and extreme points, the amount of data can be reduced, the efficiency of subsequent coupling import and calculation can be improved, and engineering errors can be kept under control.

[0103] The transient analysis method for helium leakage in a nuclear fusion device according to the present invention is described below through three embodiments:

[0104] Example 1: Transient rapid analysis and load-based output of helium leakage in the Dewar interior space of a nuclear fusion device

[0105] This embodiment presents a transient analysis method for helium leakage in nuclear fusion devices implemented on the Matlab platform. It focuses on illustrating the complete implementation process from data input, spatial discretization, transient solution to result loading and derivation, including the following steps:

[0106] Step 1: Input Data Preparation and Project Object Definition

[0107] (1) Acquisition of internal spatial information of Dewar

[0108] Obtain overall layout information of the internal space of the Dewar, including the effective gas space inside the Dewar shell, the distribution of typical partitions / supports / cold shields and other components, and the connection paths between different areas (such as connecting holes, gaps, openings, ventilation channels, etc.).

[0109] The above information may come from simplified results of the device design model, assembly drawings, system interface diagrams, or field survey data.

[0110] (2) Definition of boundary and operating condition parameters

[0111] Create a working condition parameter table in Matlab that includes at least the following:

[0112] ① The area where the leak occurred (corresponding to a specific spatial partition within the Dewar).

[0113] ② Leakage type (orifice, crack, or equivalent small opening) and its equivalent geometric parameters;

[0114] ③ Initial state parameters (pressure, temperature) of the upstream helium supply side and the way in which they change over time (constant, step, segmented change, or triggered by valve action);

[0115] ④ Initial state parameters inside the Dewar (initial pressure and temperature of each zone, including initial gas composition assumptions if necessary);

[0116] ⑤ The boundary between the Dewar and the outside environment for discharge / pressure relief / ventilation (opening location, equivalent flow capacity, and whether valve action logic exists);

[0117] ⑥ Wall / component boundaries related to gas heat exchange (cold screen or wall temperature setting method, whether wall heat capacity is considered, whether insulation thermal resistance is considered, etc.).

[0118] (3) Definition of Coupling Output Requirements

[0119] Based on the subsequent analysis objectives, the output items and output frequencies are defined as follows:

[0120] ① Pressure load time history for structural analysis (output by region or by specified surface partition);

[0121] ② The time history of the temperature boundary or convection boundary used for thermal analysis;

[0122] ③ Key indicators used for safety assessment (e.g., time to reach a certain pressure threshold, temperature drop in a certain area, cumulative leakage mass, etc.).

[0123] Step 2: Discretization of the Dewar interior space and construction of the network model

[0124] (1) Control body division

[0125] The interior space of the Dewar is divided into several control volumes based on functional regions or geometric connectivity. Each control volume represents a subspace with an "approximately homogeneous gas state." The division principles include:

[0126] ① Areas with obvious structural partitions and narrow passages should be prioritized as partition boundaries;

[0127] ② Prioritize the subdivision of spaces adjacent to leak points, discharge outlets, ventilation openings, and areas requiring strong heat exchange in cold shields;

[0128] ③ For areas far from the leak source and with slow changes, appropriate merging can be used to reduce the computational scale.

[0129] (2) Definition of connectivity

[0130] Define connectivity attributes for each pair of adjacent control bodies, including channel type (hole, slot, valve, opening, etc.), equivalent flow capacity, and whether it changes over time.

[0131] For valves or controllable openings, provide a description of how their opening changes over time (e.g., a piecewise function or event-triggered logic) so that connectivity can be dynamically updated during transient processes.

[0132] (3) Structured storage of state variables and parameters

[0133] In Matlab, a unified data structure is constructed to store the volume, initial state, heat transfer boundary information of each control volume, as well as the connectivity attributes and action logic of each channel. At the same time, a mapping table of "control volume number - physical region name - output load partition" is established to prepare for post-processing and coupled export.

[0134] Step 3: Leakage source modeling and source strength calculation implementation

[0135] (1) Leakage source location

[0136] The leak point is bound to a control body and injected into the downstream space as the leak source; the upstream side can correspond to the boundary node of the helium supply circuit or a simplified helium supply cavity.

[0137] (2) Source strength model selection and calculation logic

[0138] A general interface for calculating leakage source strength is established in Matlab, supporting different leakage types (orifice / crack) and different upstream boundaries (constant supply, segmented changes caused by valve action, etc.).

[0139] During the source strength calculation, the system automatically selects the appropriate calculation branch based on the upstream and downstream pressure states (e.g., different calculation models correspond to different pressure difference ranges) and updates the leakage mass inflow at each time step.

[0140] (3) Safety constraints and physical consistency check

[0141] Add a reasonableness check to the source strength calculation:

[0142] ① If the downstream pressure is close to the upstream pressure, the source strength will be automatically reduced or the system will enter the "micro-leakage" branch to avoid non-physical oscillations;

[0143] ② If abnormal input occurs (e.g., geometric parameters are zero or boundaries are undefined), an error message will be given and logged to facilitate engineering traceability.

[0144] Step 4: Transient solution process (numerical implementation of mass-energy conservation)

[0145] (1) Solver selection

[0146] The transient response of the control volume network model is solved using numerical integration of ordinary differential equations in Matlab. To account for both the rapid changes in the initial stage of leakage and the slow process in the later stage, a variable step size integration method is adopted, and a maximum step size and error control strategy are set to ensure stability and efficiency.

[0147] (2) Update order within a time step

[0148] Within each time step, update in the following order:

[0149] ① Update the valve / opening action status to obtain the current flow capacity of each connected channel;

[0150] ② Calculate the leakage source strength to obtain the leakage injection volume;

[0151] ③ Calculate the exchange flow rate between control volumes (determined by pressure difference and channel capacity);

[0152] ④ Update the mass status of each control entity;

[0153] ⑤ Calculate the heat exchange between each control volume and the wall / component, and update the gas temperature status;

[0154] ⑥ Update the derived states such as pressure, and check whether the set event conditions have been met (such as reaching the pressure relief threshold, entering the discharge stage, etc.).

[0155] (3) Heat transfer boundary treatment

[0156] There are two approaches to the heat transfer boundary: if the wall temperature can be considered to be controlled by the cryogenic system and approximately constant, then the wall temperature is used as a given boundary in the heat transfer calculation; if the wall heat capacity effect needs to be considered, then an equivalent heat capacity node is established on the wall, so that its temperature changes with the heat transfer process and is updated iteratively together with the gas state.

[0157] Both of these methods are configurable options to adapt to different design stages and accuracy requirements.

[0158] (4) Results recording and key indicator extraction

[0159] During the solution process, the pressure and temperature time history of each control body are recorded at a preset sampling frequency, and key engineering indicators are statistically analyzed simultaneously.

[0160] ① Cumulative mass of leakage and duration of leakage;

[0161] ② Peak pressure, minimum temperature, and the timing of their occurrence in key areas inside the Dewar;

[0162] ③ The cumulative emission mass of each emission channel is used to assess emission capacity or the effectiveness of ventilation strategies.

[0163] Step 5: Result Loading Output and Multiphysics Coupling File Generation

[0164] (1) Pressure load time history output

[0165] Based on the mapping relationship between "control volume - structural surface partition", the pressure time history of the corresponding control volume is converted into a load data file that can be used for structural analysis. The output format can be a general table time history file, or a partition load set can be generated according to the target software interface requirements.

[0166] (2) Temperature / Heat Transfer Boundary Output

[0167] The temperature time history of the control volume is output as the boundary conditions for thermal analysis; if the convective boundary method is used, the heat transfer coefficient and reference gas temperature of the corresponding region are output at the same time, so that the structural thermal analysis can be directly called.

[0168] (3) Traceability and Reproducibility Guarantee

[0169] The system automatically outputs a list of operating parameters, model partitioning information, channel and valve action logic, and calculation logs, so that each analysis can be reproduced under the same parameter set, and facilitates design comparison and review traceability.

[0170] Example 2: Transient Analysis of Adaptive Control Volume Reconstruction and Online Identification of Connectivity Parameters in Dewar's Internal Space

[0171] Based on Example 1, this embodiment further presents an improved method that is easy to implement and highly adaptable to engineering: during the transient analysis of helium leakage, the system can automatically adjust the control volume division according to the "characteristics of changes in the internal space state of the Dewar" and use existing measurement point data inside the Dewar to perform online correction of key connectivity parameters, thereby improving computational efficiency and result reliability without introducing a three-dimensional CFD mesh.

[0172] 1. Applicable Scenarios and Objectives

[0173] This embodiment is applicable to any of the following situations: drastic pressure and temperature changes in the initial stage of leakage, where a fixed control body cannot simultaneously account for local changes and overall calculation efficiency; the Dewar contains several connecting gaps, channels, or valves, whose equivalent flow capacity is difficult to accurately define in engineering, resulting in large prediction errors; the Dewar contains monitoring points for pressure, temperature, or flow rate, and it is desirable to use the measurement data to dynamically calibrate the model, making the calculation results traceable and closer to reality.

[0174] The objectives of this embodiment include: automatically refining key regions in the early stages of leakage to improve the ability to capture transient spikes and gradients; automatically merging slowly changing regions in the later stages of leakage to reduce the equation size and improve the efficiency of long-term computation; and identifying key equivalent parameters of connected channels online to reduce errors caused by model parameter uncertainties.

[0175] 2. Adaptive Control Module Reconstruction Strategy (Dynamic Refinement and Merging)

[0176] (1) Monitoring of change characteristics and triggering conditions

[0177] The system performs a rapid evaluation of the state changes of all control entities at each calculation step or fixed time interval. The evaluation metrics include at least:

[0178] Does the rate of pressure change exceed the set threshold?

[0179] Does the rate of temperature change exceed the set threshold?

[0180] Whether the pressure difference or temperature difference between the control body and the adjacent control body exceeds the set threshold;

[0181] Does the state of the target output area (e.g., near the leak point, near the discharge port, near the cold shield strong heat exchange zone) change abruptly?

[0182] When any of the above indicators meet the triggering conditions, the system will mark the corresponding control body as a candidate object that "needs refinement" or "needs merging".

[0183] (2) Control volume refinement method

[0184] For control volumes that "require refinement," the system divides the control volume into several sub-control volumes based on its geometric connectivity and boundary origin. This division can be achieved using one or more of the following methods:

[0185] Split along the main connecting channel to create a smaller control volume near the leak injection or discharge path;

[0186] The area near the cold screen or strong heat exchange surface is separated into a sub-control volume to more accurately express the local temperature drop;

[0187] The control zone at the leak source is divided into a "near-jet zone" and a "far-diffusion zone," which allows for better capture of the rapid changes in the early stages of the leak.

[0188] During the refinement process, the system is updated synchronously: volume allocation, connection channel reconstruction, inheritance rules for the initial state of sub-control volumes, and inheritance rules for the mapping relationship with the structural surface, to ensure the continuity and stability of the solution process.

[0189] (3) Control body merging method

[0190] For control entities that "need to be merged," the system will merge adjacent control entities that change slowly and have similar states. The merging can be based on the following principles:

[0191] The pressure and temperature differences between adjacent control volumes are maintained within a small range over a long period of time;

[0192] The area is far from the leak point and discharge outlet, and has little impact on key output indicators;

[0193] The topology of important connected paths will not be disrupted after merging.

[0194] During the merging process, the system conserves mass and energy and regenerates the parameters of the merged heat transfer boundary and connecting channels to ensure the traceability of analysis results.

[0195] 3. Online Identification of Connectivity Parameters and Model Correction

[0196] (1) Selection of parameters to be identified

[0197] The system sets parameters that are sensitive to the results and are not easily given accurately in engineering as the objects to be identified. Typical examples include:

[0198] Equivalent flow capacity of certain gaps / channels;

[0199] Conversion factor between valve opening degree and flow capacity;

[0200] Equivalent heat transfer coefficient correction factor related to local heat transfer (used to characterize heat transfer enhancement or attenuation near complex structures).

[0201] (2) Data access and error measurement at measurement points

[0202] The system uses existing measurement data within the Dewar unit as the basis for calibration. Measurement data types can include pressure, temperature, or flow rate. Within each update cycle, the system calculates the "deviation between the model prediction and the measurement data" and establishes a configurable error metric.

[0203] The main focus is on the pressure deviation at key measuring points;

[0204] Or it may be mainly due to temperature deviation;

[0205] Alternatively, a weighted deviation method combining multiple measurement points can be used, with the weights set based on the reliability or criticality of the measurement points.

[0206] (3) Online update method

[0207] The system uses a "rolling window" approach to update parameters within a limited time period. This allows parameter correction to respond quickly to transient changes in leakage while avoiding severe oscillations caused by noise. Online updates can be implemented using one of the following easily implemented strategies:

[0208] The parameters to be identified are updated in small steps according to the magnitude and direction of the deviation.

[0209] Immediately after the update, perform short-step prediction verification. If the deviation decreases, accept the update; otherwise, roll back and reduce the update magnitude.

[0210] The update frequency is automatically reduced during valve action or boundary abrupt changes to avoid misidentifying boundary changes as model parameter errors.

[0211] (4) Traceable output

[0212] The system records the time, magnitude, deviation, and operating conditions of each parameter update, and exports the parameter evolution curve and the final parameter set along with the results for easy review and reproduction.

[0213] 4. Output and Effects

[0214] Through adaptive control volume reconstruction, the system can more accurately capture rapid changes in pressure and temperature inside the Dewar in the early stages of leakage. At the same time, it reduces the solution scale by merging in the later stages, making long-term calculations more efficient. Through online identification, the system can correct key connectivity and heat transfer parameters without increasing the complexity of geometric modeling, improving consistency with actual measurement points and significantly reducing the workload of repeated manual parameter tuning.

[0215] Example 3: Multiphysics coupling generated by automatic load time history compression and structural surface mapping

[0216] Based on Example 1, this embodiment further presents an improved method for engineering coupling applications: automatically converting the transient results of the Dewar interior space into loads that can be directly called by structural and thermal analysis, and compressing the load time history with controlled error, thereby reducing the data size, improving coupling efficiency, and increasing the standardization of load application.

[0217] 1. Applicable Scenarios and Objectives

[0218] This embodiment is applicable to the following situations: when it is necessary to import the pressure, temperature or heat transfer boundary of the internal space of the Dewar into the structural platform for strength, deformation or thermal stress assessment; when the transient calculation process is long and the output sampling frequency is high, resulting in an excessive amount of load time history data, which affects the efficiency of subsequent platform import and calculation; and when it is necessary to realize batch coupled analysis of multiple working conditions, requiring the load generation process to be automated and reusable.

[0219] The objectives of this embodiment include: automatically converting "control volume results" into "structural surface partition loads"; extracting and compressing feature points from the load time history to significantly reduce file size while ensuring error control; and outputting load files and mapping lists that can be directly recognized by mainstream finite element platforms, reducing manual operations.

[0220] 2. Establishment of control volume-structure surface mapping rules

[0221] (1) Definition of mapping object

[0222] In Matlab, create a "load partition object". Each load partition corresponds to one or more surface regions on the structural model, such as a ring region of the inner wall of the Dewar, a panel region of the cold shield, or a surface region of the supporting component.

[0223] (2) Generation of mapping rules

[0224] The system provides two easy-to-implement methods for generating mapping relationships:

[0225] Based on the regional division rules in the design phase: the structural surface is divided into several regions according to spatial location (height, circumferential, radial, etc.) and bound to the control volume number;

[0226] Based on the imported identifier file: The structure platform pre-exports a list of surface partition names, which Matlab reads and automatically matches with the control volume region names to generate a mapping table.

[0227] (3) Mapping consistency check

[0228] The system automatically checks whether each structural surface partition has a corresponding control volume. If there is a missing or multiple mapping, it outputs an error message or generates a default processing rule (such as using the nearest neighbor control volume or using a weighted average) and records the log.

[0229] 3. Load time history generation and error-controlled compression

[0230] (1) Load time history generation

[0231] The system converts the pressure and temperature time histories of the corresponding control volumes into load curves usable for structural analysis according to the mapping relationship, and generates independent time history data for each load partition.

[0232] (2) Feature point extraction and compression strategy

[0233] To reduce the data size, the system performs automatic compression on each load curve. The compression rules can be implemented using the following methods:

[0234] Identify abrupt change points: including event points such as the onset of leakage, valve action, and opening of the discharge port, and ensure that these points are preserved;

[0235] Identify peak and inflection points: Automatically retain pressure peaks, temperature minimums, and several key points before and after them;

[0236] Linear interpolation is used to verify the error between adjacent points. If the error is lower than the set threshold, the intermediate point is deleted; otherwise, it is retained.

[0237] The above compression process uses an "error threshold" as a constraint. The error threshold can be set according to engineering requirements, such as pressure tolerance, temperature tolerance, or thermal stress sensitivity, and different thresholds can be used for different zones.

[0238] (3) Multi-curve consistency and synchronous sampling processing

[0239] To facilitate unified import of structural platform, you can choose to compress all partition loads and unify them into the same set of time nodes, or allow each partition to use an independent time node and output the corresponding import script or description file at the same time, reducing the complexity of coupled operations.

[0240] 4. Coupled file output and batch processing interface

[0241] (1) Load file output for structural platform

[0242] The system output includes: pressure time history files for each load zone, temperature boundary or convection boundary time history files for each load zone, a mapping list of load zone names and structural surface names, a table of operating parameters, and a table of compression threshold configurations, ensuring traceability.

[0243] (2) Batch processing and automated invocation

[0244] The system supports automatic cyclic execution of "transient solution - load generation - compression - export" for multiple leakage conditions, and automatically generates an independent directory and version number for each condition to form an auditable calculation file; at the same time, it reserves a script interface with the structural platform, so that structural analysis can automatically load loads and perform calculations according to the same mapping list.

[0245] 5. Output and Effects

[0246] By automatically compressing the load time history, this embodiment significantly reduces the size of the load file while ensuring that key transient features are not lost and errors are controlled, thereby improving the efficiency of subsequent coupling import and structural solution. By automatically generating and checking the control volume-structure surface mapping, manual partitioning and load application errors are reduced, thereby improving the standardization and reusability of multi-condition batch coupling analysis.

[0247] The following is combined Figure 2 This invention describes a transient analysis method for helium leakage in a nuclear fusion device according to a specific embodiment of the present invention.

[0248] like Figure 2 As shown, the transient analysis method for helium leakage in a nuclear fusion device includes:

[0249] S21, Operating conditions and target definition;

[0250] Specifically, this includes: reading the leakage conditions, analysis duration, output requirements, and coupling targets.

[0251] S22, Import Dewar space and boundary data;

[0252] Specifically, this involves importing information on the internal space zoning of the Dewar, connectivity relationships, valve and discharge boundaries, and heat exchange boundaries.

[0253] S23, Initial parameter check and completion: Determine whether the parameters are complete and within a reasonable range?

[0254] If the parameters are complete and within a reasonable range, proceed to step S24; otherwise, return to step S22.

[0255] S24, Control volume partitioning and network modeling;

[0256] Specifically, this involves generating a set of control bodies and a set of channels, and establishing a mapping between region names and numbers.

[0257] S25, Preparation for structural surface mapping;

[0258] Specifically, this involves reading the list of structural surface partitions and establishing mapping rules from control volumes to surfaces.

[0259] S26, Mapping consistency check: Determine if there are missing or multiple mappings?

[0260] If there is a missing mapping or multiple mappings, return to step S25; otherwise, proceed to step S27.

[0261] S27, Solution and computation strategy configuration;

[0262] Specifically, this involves setting time step control, output frequency, event triggering rules, and logging strategies.

[0263] S28, Initialize transient state;

[0264] Specifically, this involves initializing the pressure and temperature states of each control body and establishing a result storage structure.

[0265] S29, enter the time step loop;

[0266] Specifically, it involves entering the transient solution loop and preparing to update the current state.

[0267] S210, Update valve and discharge boundary status;

[0268] Specifically, it involves updating the valve opening and discharge boundary capabilities based on the current time and event logic.

[0269] S211, Calculate the leakage source strength and channel exchange flow;

[0270] Specifically, the leakage injection amount is updated based on the upstream status and the current downstream status, the mass exchange between control volumes is calculated, and the channel direction and size are updated.

[0271] S212, Calculate and update the state;

[0272] Specifically, this includes updating the mass status, updating the heat exchange and temperature status, and updating the pressure and derived status.

[0273] S213, Determine adaptive reconstruction: Determine whether to refine the local control volume or merge the gradually changing region?

[0274] If the local control volume is refined or the gradually changing region is merged, then step S214 is executed; otherwise, step S215 is executed.

[0275] S214, Execution control body reconfiguration;

[0276] Specifically, this involves refining key areas or merging and reconstructing connectivity relationships in areas with gradual changes.

[0277] S215, Online Identification Judgment: Determine whether the online parameter correction conditions are met?

[0278] If the online parameter calibration conditions are met, proceed to step S216; otherwise, proceed to step S217.

[0279] S216, Perform online parameter calibration;

[0280] Specifically, this involves making small updates to the connectivity or heat transfer correction factor and recording the correction results.

[0281] S217, Time step and event convergence judgment: Is it stable and does the time step size need to be adjusted?

[0282] If the time step is stable and needs adjustment, proceed to step S218; otherwise, proceed to step S219.

[0283] S218, Results Recording and Key Indicator Updates.

[0284] Specifically, this involves recording the pressure and temperature time history and updating indicators such as peak value, minimum value, and cumulative leakage.

[0285] S219, Adjust time step and recalculate;

[0286] Specifically, this involves reducing the time step and recalculating after backtracking from the current step.

[0287] S220, Termination condition judgment: Has the simulation termination time been reached or has the termination condition been met?

[0288] If the simulation termination time is reached or the termination condition is met, proceed to step S221; otherwise, return to step S29.

[0289] S221, complete the load time history data;

[0290] Specifically, this involves generating the time histories of pressure and temperature loads required for the structure based on the mapping relationship.

[0291] S222, Load time history compression judgment: Should load compression be enabled and a compression strategy be selected?

[0292] If load compression is enabled and a compression strategy is selected, proceed to step S223; otherwise, proceed to step S224.

[0293] S223, Export the coupled files and report;

[0294] Specifically, this includes exporting load files, mapping lists, operating condition parameter tables, and calculation logs.

[0295] S224, Perform load compression;

[0296] Specifically, this involves retaining event points and peak points while deleting redundant points under error constraints.

[0297] S225, Batch processing judgment of operating conditions;

[0298] If there are still uncalculated working conditions, return to step S21 and proceed to the next working condition calculation; otherwise, execute step S226.

[0299] S226, End of calculation process;

[0300] Specifically, this means ending the calculation and archiving all data.

[0301] In summary, the transient analysis method for helium leakage in nuclear fusion devices according to embodiments of the present invention can achieve the following beneficial effects:

[0302] (1) Improve the efficiency of transient analysis of helium leakage inside Dewar space

[0303] Compared to traditional CFD methods that rely on large-scale 3D meshes and small time steps, this invention uses control volumes and connected networks to achieve transient solutions for the internal space of the Dewar, which can significantly reduce modeling and computation costs while maintaining engineering-usable accuracy, making it more suitable for rapid evaluation of long-term processes and multiple operating conditions.

[0304] (2) Simultaneously consider both "system dynamic impact" and "spatial zoning response"

[0305] Compared to fragmented solutions that can only perform system-level one-dimensional network responses or only local three-dimensional flow fields, this invention incorporates the leakage source, valve and discharge boundary actions, and zoned connectivity exchange and heat exchange processes into the same time-driven chain. This allows for obtaining pressure and temperature evolution results in different regions within the Dewar within a unified framework, facilitating engineering judgment and decision-making.

[0306] (3) Directly output load time histories that can be used for thermal and structural analysis, forming a closed-loop workflow.

[0307] Compared to existing technologies that require manual extraction of boundaries from simulation results, followed by format conversion and partitioning, this invention can automatically convert transient results into load time histories such as pressure, temperature, and convection boundaries, and output a mapping list and logs, making subsequent thermal-structural or fluid-structure interaction analyses more standardized, reusable, and traceable.

[0308] (4) Achieving a dynamic balance of "precise in the early stage and efficient in the later stage" through adaptive control volume reconstruction.

[0309] Compared to existing methods that use fixed discrete values, which either result in overly coarse discrete values ​​affecting transient spikes or overly fine discrete values ​​slowing down computation, this invention can automatically refine key regions and merge slowly changing regions based on the internal state change characteristics of the Dewar, allowing computational resources to be concentrated on key stages and key locations, thereby improving the overall performance in terms of accuracy and efficiency.

[0310] (5) Use measurement point data to calibrate key parameters online, improve consistency with reality and reduce parameter adjustment costs.

[0311] Compared to the current situation where gap connectivity, valve equivalence, or heat transfer intensity need to be determined based on experience and repeatedly adjusted manually, this invention supports access to measurement data such as internal pressure and temperature of the Dewar, performs rolling correction and recording output of key parameters, improves prediction reliability and reduces the amount of manual iteration work.

[0312] (6) Controlled compression of load time history error reduces the size of coupled data and improves engineering operability.

[0313] Compared to the problems of large file size, difficult import and low coupling efficiency caused by long-term high-frequency output, this invention automatically compresses load curves while retaining event points and extreme points, making the data volume smaller and the import faster, while keeping engineering errors controllable and facilitating automated coupling calculations for batch working conditions.

[0314] (7) The platform is open and easy to integrate, which is conducive to project promotion and secondary development.

[0315] Compared to dedicated accident analysis software with high learning costs or closed interfaces, this invention is based on Matlab, which facilitates data interaction and workflow scripting integration with mainstream simulation platforms. It also facilitates the subsequent expansion to more leakage scenarios, ventilation strategies, or multi-physics coupling capabilities, thus better meeting the actual needs of nuclear fusion device engineering design and operational safety assessment.

[0316] Figure 3 This is a structural block diagram of the transient analysis system for helium leakage in a nuclear fusion device according to an embodiment of the present invention.

[0317] like Figure 3As shown, the transient analysis system 100 for helium leakage in a nuclear fusion device includes: an acquisition module 10, a partitioning module 20, an establishment module 30, a solution module 40, and a conversion module 50.

[0318] In an embodiment of the present invention, the acquisition module 10 is used to acquire the structural parameters and operating parameters of the Dewar of the nuclear fusion device; the partitioning module 20 is used to divide the internal space of the Dewar into multiple interconnected control volumes based on the structural parameters; the establishment module 30 is used to establish a set of transient analysis equations containing target physical quantities for each control volume based on the operating parameters; the solution module 40 is used to solve the set of transient analysis equations using a variable step-size integration method to obtain the transient time histories of the target physical quantities in each control volume; and the conversion module 50 is used to convert the transient time histories of the target physical quantities into load data files that can be recognized by the target engineering analysis platform.

[0319] It should be noted that other specific embodiments of the helium leakage transient analysis system 100 for nuclear fusion devices in this embodiment of the invention can be found in the specific embodiments of the helium leakage transient analysis method for nuclear fusion devices described above.

[0320] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0321] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0322] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A transient analysis method for helium leakage in a nuclear fusion device, characterized in that, Includes the following steps: Obtain the Dewar structural parameters and operating parameters of the nuclear fusion device; Based on the aforementioned structural parameters, the internal space of the Dewar is divided into multiple interconnected control volumes; For each of the control bodies, a set of transient analysis equations containing the target physical quantities is established based on the operating parameters; The transient analysis equations are solved by using the variable step-size integration method to obtain the transient time history of the target physical quantity in each control volume; The transient time history of the target physical quantity is converted into a load data file that can be recognized by the target engineering analysis platform; The division of the Dewar's interior space into multiple interconnected control volumes includes: The control body boundary is determined based on the physical separation of the internal partitions and the narrowness of the channels inside the Dewar; the area adjacent to the leakage source, pressure relief port, exhaust port or strong heat exchange wall is divided into an independent control body.

2. The transient analysis method for helium leakage in a nuclear fusion device according to claim 1, characterized in that, The structural parameters include at least: the effective gas volume inside the Dewar, the layout of the internal partitions and supporting components, and the position and geometric parameters of the connecting channels, gaps, valves, pressure relief ports and exhaust ports; The operating parameters include at least: the location and equivalent leakage area parameters of the helium leakage source, the upstream pressure and temperature parameters of the helium source side, the initial pressure and temperature distribution inside the Dewar, and the material properties and thermal boundary conditions of the wall or cryogenic components that exchange heat with the gas inside the Dewar.

3. The transient analysis method for helium leakage in a nuclear fusion device according to claim 2, characterized in that, The transient analysis equations include the mass conservation equation and the energy conservation equation, wherein: The mass conservation equation is: ; The energy conservation equation is as follows: in, For time, For control body Internal helium mass, To control adjacent entities Inflow control body mass flow rate, To control body Flow to adjacent control bodies mass flow rate, Injecting helium leak source into control body mass flow rate, For control body Internal gas relative to internal energy For control body Enthalpy of internal gas For control body Net heat exchange capacity with the wall or component.

4. The transient analysis method for helium leakage in a nuclear fusion device according to claim 3, characterized in that, The mass flow rate of the helium leakage source is dynamically selected based on the real-time pressure ratio between the upstream and downstream sides, using a calculation model whereby, When the pressure ratio is below the critical pressure ratio, the choked flow model is used for calculation; When the pressure ratio is higher than the critical pressure ratio, a non-blocking flow model is used for calculation.

5. The transient analysis method for helium leakage in a nuclear fusion device according to claim 3, characterized in that, The mass flow rate between adjacent control volumes is calculated using the following formula: in, For control body Internal gas density, For control body With adjacent control bodies The channel flow coefficient of the connected channel. For control body With adjacent control bodies The equivalent circulation area of ​​the passageway, including the channel. For control body pressure, For control body pressure, It is a symbolic function.

6. The method according to claim 1, characterized in that, The target physical quantities include at least the pressure, temperature and helium mass of each control volume; The load data file includes a pressure time history file, a temperature boundary time history file, or a heat flux boundary time history file.

7. The transient analysis method for helium leakage in a nuclear fusion device according to claim 1, characterized in that, The step size in the variable step size integration method is expressed by the following formula: in, For time step, , For control coefficients, For the maximum allowed time step, , These are the rate of change in mass and the rate of change in temperature, respectively.

8. The transient analysis method for helium leakage in a nuclear fusion device according to any one of claims 1-7, characterized in that, The method is implemented using Matlab.

9. A transient analysis system for helium leakage in a nuclear fusion device, characterized in that, include: The acquisition module is used to acquire Dewar-related data of the nuclear fusion device, wherein the Dewar-related data includes Dewar-related structural parameters and operating parameters; The partitioning module is used to divide the internal space of the Dewar into multiple interconnected control volumes based on the structural parameters. A module is established for each of the control bodies to establish a set of transient analysis equations containing target physical quantities based on the operating parameters. The solver module is used to solve the transient analysis equations using a variable step-size integration method to obtain the transient time history of the target physical quantity in each control volume; The conversion module is used to convert the transient time history of the target physical quantity into a load data file that can be recognized by the target engineering analysis platform; The division of the Dewar's interior space into multiple interconnected control volumes includes: The control body boundary is determined based on the physical separation of the internal partitions and the narrowness of the channels inside the Dewar; the area adjacent to the leakage source, pressure relief port, exhaust port or strong heat exchange wall is divided into an independent control body.

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