Mesh fast generation method for typical components of nuclear engineering

Abstract

The present application relates to the technical field of nuclear engineering mechanics simulation, and specifically discloses a grid fast generation method for a nuclear engineering typical component, comprising: obtaining a geometric model of a nuclear engineering typical component to be processed and grid generation control parameters input by a user in a command stream mode; performing region identification according to a topological structure and geometric features of the geometric model, and determining a grid division strategy of the geometric model according to a result of the region identification and the grid generation control parameters, wherein the grid division strategy at least includes the result of the region identification of the geometric model and a grid division adaptation mode adapted to the result of the region identification of the geometric model, and the grid division adaptation mode at least includes a grid division preselected mode; and performing grid division on the result of the region identification of the geometric model according to the grid division strategy, to obtain a grid generation result of the nuclear engineering typical component. The grid fast generation method for the nuclear engineering typical component can improve grid generation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear engineering mechanics simulation, and in particular to a method for rapidly generating a mesh for a typical component of nuclear engineering. BACKGROUND

[0002] In the field of nuclear engineering, the design of nuclear power plant buildings and containment equipment is a crucial link. Structural simulation analysis of typical components such as reactor pressure vessels and steam generators is essential to ensure the safety and reliability of nuclear facilities. The finite element method is a common means of structural simulation, and mesh generation is a key pre-step for finite element analysis. With the continuous advancement of technology, the requirements for accuracy and efficiency are continuously improving.

[0003] Currently, the traditional mesh generation method has many shortcomings when dealing with typical components of nuclear engineering. On the one hand, the geometry of typical components of nuclear engineering is complex, containing a large number of irregular surfaces, holes, and variable thickness regions, etc. The existing general mesh generation algorithm is difficult to accurately and efficiently generate high-quality meshes that meet the analysis requirements. For example, for the nozzle part of the reactor pressure vessel, due to its irregular shape and complex connection structure with the cylinder, the mesh generated by the traditional method is prone to distortion and poor quality, affecting the accuracy of the analysis results. On the other hand, the requirements for mesh density of typical components of nuclear engineering are different in different parts. For example, fine mesh is needed in stress concentration areas to accurately capture the stress distribution, while in some relatively small stress change areas, the mesh density can be appropriately reduced to reduce the amount of calculation. However, the existing mesh generation method is difficult to flexibly control the adaptive mesh density according to the structural characteristics and analysis requirements of the component. In addition, when meshing large-scale typical components of nuclear engineering, the UI-based meshing method is inefficient, consuming a lot of time and manpower.

[0004] Therefore, how to improve the efficiency of mesh generation has become a technical problem to be solved by those skilled in the art. SUMMARY

[0005] The present application provides a method for rapidly generating a mesh for a typical component of nuclear engineering, which solves the problem of low mesh generation efficiency of typical components of nuclear engineering in the related art.

[0006] As an aspect of the present application, a method for rapidly generating a mesh for a typical component of nuclear engineering is provided, comprising:

[0007] Obtaining a geometry model of a nuclear engineering typical component to be processed and a mesh generation control parameter input by a user in a command stream manner, the geometry model comprising any one or more of a nuclear power plant building structure, a storage container and a transport container, and the mesh generation control parameter comprising at least a mesh size, a mesh topology type and a mesh division pre-selected mode, the mesh division pre-selected mode comprising one or more of a free division, a mapped division and a swept division;

[0008] According to a topological structure and a geometry feature of the geometry model, performing region identification, and determining a mesh division strategy of the geometry model according to a result of the region identification and the mesh generation control parameter, wherein the mesh division strategy comprises at least the result of the region identification of the geometry model and a mesh division adaptation mode adapted to the result of the region identification of the geometry model, and the mesh division adaptation mode comprises at least the mesh division pre-selected mode;

[0009] According to the mesh division strategy, performing mesh division on the result of the region identification of the geometry model, and obtaining a mesh generation result of the nuclear engineering typical component.

[0010] Further, according to a topological structure and a geometry feature of the geometry model, performing region identification, and determining a mesh division strategy of the geometry model according to a result of the region identification and the mesh generation control parameter, comprising:

[0011] According to the topological structure and the geometry feature of the geometry model, performing region identification on the nuclear engineering typical component, and obtaining a plurality of target regions to be divided, the target regions to be divided comprising at least a geometry regular region, a geometry irregular region and a physical connection simulation region, the geometry regular region comprising a geometry region capable of being expressed by a single parameter equation, the geometry irregular region comprising a region capable of being expressed by a segmented or combined parameter equation and a region capable of being expressed by any one or more of a fitting, a polynomial approximation and an approximate solution, and the physical connection simulation region comprising a region in which two physical connections are connected in a fixed manner and there is no geometric connection between the two physical connections;

[0012] According to the mesh generation control parameter, generating a mesh hard point seed of each geometry boundary of the target regions to be divided;

[0013] For each geometry feature of the target regions to be divided and the mesh division pre-selected mode, determining a mesh division adaptation mode adapted to the geometry feature of the target regions to be divided.

[0014] Further, for each geometry feature of the target regions to be divided and the mesh division pre-selected mode, determining a mesh division adaptation mode adapted to the geometry feature of the target regions to be divided, comprising:

[0015] when the current target region to be divided is a geometrically regular region, determining a grid division adaptation mode according to whether the grid division preselected mode is adapted to the geometric feature of the geometrically regular region;

[0016] when the current target region to be divided is a geometrically irregular region, determining a corresponding grid division adaptation mode according to the irregular type of the geometrically irregular region, the irregular type of the geometrically irregular region at least including a stress concentrated region type and a region type having stress checking requirement;

[0017] when the current target region to be divided is a physically connected simulation region, determining a grid division adaptation mode according to the physical connection mode.

[0018] Further, when the current target region to be divided is a geometrically regular region, determining a grid division adaptation mode according to whether the grid division preselected mode is adapted to the geometric feature of the geometrically regular region, comprising:

[0019] if the current target region to be divided is a geometrically regular region, judging the type of the grid division preselected mode;

[0020] if the type of the grid division preselected mode is mapping subdivision, judging whether the current geometrically regular region is a normalized rectangular face in a parameter space;

[0021] if the current geometrically regular region is a normalized rectangular face in the parameter space, determining that the grid division adaptation mode is the grid division preselected mode;

[0022] if the current geometrically regular region is a non-normalized rectangular face in the parameter space, prompting the user of grid division failure;

[0023] if the type of the grid division preselected mode is free subdivision, performing partition processing on the current geometrically regular region to obtain a plurality of normalized rectangular faces, and determining that the grid division adaptation mode of each normalized rectangular face is mapping subdivision.

[0024] Further, according to the grid division strategy, performing grid division on the region recognition result of the geometric model to obtain a grid generation result of the nuclear engineering typical component, comprising:

[0025] for a plurality of geometrically regular regions recognized by the geometric model region recognition, generating a structured quadrilateral face grid for the geometrically regular region one by one according to the mapping subdivision mode;

[0026] optimizing the quadrilateral face grid according to a grid smoothing algorithm.

[0027] Further, when the current target region to be divided is a geometric irregular region, a corresponding grid division adaptation mode is determined according to an irregular type of the geometric irregular region, including:

[0028] If the irregular type of the current geometric irregular region is a stress concentrated surface region, the determination of the grid division adaptation mode includes free division and mapping division, wherein the stress concentrated surface region at least includes a thin-walled region and an open hole region;

[0029] If the irregular type of the current geometric irregular region is a body region with stress checking requirement, the determination of the grid division adaptation mode includes free division and sweep division, wherein the body region with stress checking requirement at least includes a nozzle region and a foundation region.

[0030] Further, the grid generation result of the typical component of the nuclear engineering is obtained by performing grid division on the region identification result of the geometric model according to the grid division strategy, including:

[0031] For the stress concentrated surface region identified from the geometric model, a source surface grid is generated according to the free division or mapping division mode; for the body region with stress checking requirement identified from the geometric model, the body region with stress checking requirement is divided into a body grid unit according to the sweep division mode.

[0032] Further, when the current target region to be divided is a physical connection simulation region, a grid division adaptation mode is determined according to a physical connection mode, including:

[0033] If the current target region to be divided is a welding region, the determination of the grid division adaptation mode includes contact element simulation;

[0034] If the current target region to be divided is a rigid connection region, the determination of the grid division adaptation mode includes constraint element simulation.

[0035] Further, a grid hard point seed of each geometric boundary of the target region to be divided is generated according to the grid generation control parameter, including:

[0036] Hard points are set on each geometric boundary of the target region to be divided according to the grid size in the grid generation control parameter;

[0037] The spacing of the hard points is adjusted to make the hard points of two adjacent target regions to be divided completely coincide.

[0038] Further, after the step of performing grid division on the region identification result of the geometric model according to the grid division strategy, the following steps are further included:

[0039] A grid quality check file is generated, and the grid quality check file includes multiple grid quality evaluation indexes;

[0040] According to the checking result of the grid quality check file, it is determined whether there is a grid unit that does not meet the requirements;

[0041] If there is, the grid unit that does not meet the requirements is optimized according to a grid smoothing algorithm.

[0042] The grid generation method for the nuclear engineering typical component provided by the application comprises the following steps: obtaining a geometry model of a nuclear engineering typical component to be processed and grid generation control parameters input by a user in a command stream mode; performing region identification and other processing on the geometry model; and determining a grid division strategy corresponding to each region after the region identification, so that the grid division of the nuclear engineering typical component can be performed according to the determined grid division strategy. The grid generation method for the nuclear engineering typical component provided by the application realizes the acquisition of user input information in the form of a command stream, and then realizes the grid division, without the need for manual operation of the user and the need for too much interaction with the user to automatically realize the grid division, thereby effectively improving the grid generation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0043] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and are used together with the following detailed description to explain the application, but do not constitute a limitation on the application.

[0044] Figure 1 The flowchart of the grid generation method for the nuclear engineering typical component provided by the application is shown.

[0045] Figure 2 The geometry model receiving and display schematic diagram provided by the application is shown.

[0046] Figure 3 The geometry model region identification schematic diagram provided by the application is shown.

[0047] Figure 4 The geometry attribute assignment display schematic diagram provided by the application is shown.

[0048] Figure 5 The method flowchart for determining the grid division strategy of the geometry model provided by the application is shown.

[0049] Figure 6 The method flowchart for generating the grid hard point seed provided by the application is shown.

[0050] Figure 7 The grid hard point seed point display schematic diagram provided by the application is shown.

[0051] Figure 8The method flow chart for determining the grid division adaptation mode provided by the present application.

[0052] Figure 9 The structured grid schematic diagram of the typical component provided by the present application.

[0053] Figure 10 The grid schematic diagram generated by free division provided by the present application.

[0054] Figure 11 The grid schematic diagram generated by sweep division provided by the present application.

[0055] Figure 12 The grid batch generation schematic diagram of the contact unit and the constraint unit provided by the present application.

[0056] Figure 13 The schematic diagram of directly cutting the triangular grid into quadrilateral grid when the quadrilateral grid division fails provided by the present application. DETAILED DESCRIPTION

[0057] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0058] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0059] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0060] In the present embodiment, a grid rapid generation method for nuclear engineering typical components is provided, Figure 1 The flow chart of the grid rapid generation method for nuclear engineering typical components provided by the present embodiment of the present application is shown inFigure 1 As shown in the figure, comprising:

[0061] S100, acquire the geometry model of the nuclear engineering typical component to be processed and the mesh generation control parameter input by the user in the command stream mode, the geometry model includes any one or more of the nuclear power plant building structure, the storage container and the transport container, the mesh generation control parameter at least includes the mesh size, the mesh topology type and the mesh division pre-selected mode, the mesh division pre-selected mode includes one or more of the free division, the mapping division and the sweep division;

[0062] In the embodiment of the application, the user inputs the geometry model of the nuclear engineering typical component to be processed in the command stream mode, and can also input the mesh generation control parameter in the command stream mode. Specifically, the command stream can be an APDL command stream.

[0063] Specifically, the nuclear power plant building structure can specifically include a nuclear power plant workshop, etc.; the mesh size in the mesh generation control parameter can be the maximum side length of the mesh face, or the maximum length of the diagonal line of the mesh face, etc.; the mesh topology type can be the shape of the mesh face; the mesh division pre-selected mode can be understood as the mesh division mode pre-selected by the user, in the embodiment of the application, the mesh division pre-selected mode includes one or more of the free division, the mapping division and the sweep division, wherein the free division is applicable to both the face mesh generation and the volume mesh generation, the mapping division is only applicable to the face mesh generation, and the sweep division is only applicable to the volume mesh generation. It should be noted that if the user does not check the mesh division mode, the default is the free division mode.

[0064] Specifically, as shown in the figure, Figure 2 The embodiment of the application takes the geometry model of a three-leg container as an example to illustrate the geometry model of nuclear engineering mechanics, after the user completes the modeling work or imports the model, the embodiment of the application can display the geometry model, the geometry model of the container contains 267 geometric faces.

[0065] S200, according to the topological structure and the geometry feature of the geometry model, region identification is performed, and according to the result of region identification and the mesh generation control parameter, the mesh division strategy of the geometry model is determined, wherein the mesh division strategy at least includes the result of region identification of the geometry model and the mesh division adaptation mode adapted to the result of region identification of the geometry model, and the mesh division adaptation mode at least includes the mesh division pre-selected mode;

[0066] In the embodiment of the present application, the region recognition is based on the topology of the geometric model. Specifically, the geometric features in the geometric model can be recognized by a feature recognition algorithm, and the recognized features can be classified. Specifically, in the example of the present application, various geometric features in the container are recognized by using the feature recognition algorithm based on the geometric topology information. The recognized features are classified into simple features and complex features. In this example, as shown in Figure 3 different colors. Different mesh generation strategies will be used for different types of features in the subsequent process.

[0067] Therefore, in the embodiment of the present application, the blocking algorithm based on geometric feature recognition decomposes the geometric model of the typical component of nuclear engineering into target regions to be divided with simple geometric features. Different mesh division adaptation modes are determined in combination with the mesh generation control parameters for different target regions to be divided, so as to obtain the mesh division strategies for different target regions to be divided.

[0068] S300, mesh division is performed on the result of the region recognition of the geometric model according to the mesh division strategy, and the mesh generation result of the typical component of nuclear engineering is obtained.

[0069] In the embodiment of the present application, the mesh division is performed on the result of the region recognition of the geometric model, i.e. the result of the region division of the typical component of nuclear engineering, by using the determined mesh division strategy, and the mesh generation result is obtained.

[0070] Therefore, the method for quickly generating mesh for the typical component of nuclear engineering provided by the present application can obtain the geometric model of the typical component of nuclear engineering to be processed and the mesh generation control parameters input by the user in the form of a command stream, and then perform region recognition and other processes on the geometric model, and determine the mesh division strategy corresponding to each region after the region recognition. Therefore, the mesh division of the typical component of nuclear engineering can be realized according to the determined mesh division strategy. The method for quickly generating mesh for the typical component of nuclear engineering provided by the present application realizes the acquisition of user input information in the form of a command stream, and then realizes the mesh division without manual operation of the user and automatic realization of the mesh division without too much interaction with the user, so as to effectively improve the mesh generation efficiency.

[0071] In the embodiment of the present application, specifically, the mesh generation control parameters can further include physical properties such as materials, element types, cross sections, real constants, coordinate systems, etc. set on the geometric model. These properties will be attached to the mesh after the mesh division is completed, becoming the physical properties of the mesh. As shown in Figure 4 the materials, cross sections, real constants, element types, etc. are defined first, and then the values such as the material number, element type number, cross section number, real constant serial number, and coordinate system number of the container example are added to the geometric face information.

[0072] In the embodiment of the present application, the region identification is performed according to the topological structure and geometric characteristics of the geometric model, and the grid division strategy of the geometric model is determined according to the result of the region identification and the grid generation control parameters, as shown in the following formula: Figure 5

[0073] S210, region identification is performed on the typical component of the nuclear engineering according to the topological structure and geometric characteristics of the geometric model, and a plurality of target regions to be divided are obtained, the target regions to be divided at least include a geometric regular region, a geometric irregular region and a physical connection simulation region, the geometric regular region includes a geometric region capable of being expressed by a single parameter equation, the geometric irregular region includes a region capable of being expressed by a segmented or combined parameter equation and a region capable of being expressed by any one or more combinations of fitting, polynomial approximation and approximate solution, and the physical connection simulation region includes a region connected by a fixed mode in two physical connections and not geometrically connected;

[0074] It should be understood that, based on the topological structure of the geometric model, it is decomposed into a plurality of combinations of planes, curved surfaces and bodies through the region identification, that is, a plurality of target regions to be divided are obtained, these target regions to be divided include a plurality of types, which can specifically include a geometric regular region, a geometric irregular region and a physical connection simulation region, and for different types of target regions to be divided, the corresponding grid division strategy can be determined.

[0075] It should be noted that the geometric regular region specifically refers to a regular geometric region with a parameter equation, and the geometric irregular region cannot be described by a single parameter equation. The geometric irregular region can specifically include a stress concentration region and a region with stress checking requirement, and the physical connection simulation region specifically refers to a region with physical connection characteristics between components.

[0076] It should be noted that in the embodiment of the present application, the geometric irregular region can be further divided into a simple geometric irregular region and a complex geometric irregular region according to the complexity of computer programming, wherein the simple geometric irregular region can specifically include a region capable of being expressed by a multi-segment or combined parameter equation; the complex geometric irregular region is a region that cannot be accurately expressed by a parameter equation, and can specifically include a region expressed by fitting, polynomial approximation and approximate solution, such as high genus algebraic curve, ill-conditioned curve, geometric equation without closed solution and some high-order polynomial implicit surface.

[0077] S220, generating grid hard point seeds of each geometric boundary of the target region to be divided according to the grid generation control parameters;

[0078] ​It should be understood that, in order to avoid the occurrence of intersecting grids in the grid generation process, the embodiment of the present application generates grid hard point seeds on the geometric boundaries of the target region to be divided after the region is identified, which can effectively prevent the occurrence of intersecting grids, so as to generate grids that meet the simulation requirements and the displacement coordination.

[0079] In the embodiment of the present application, the grid hard point seeds of each geometric boundary of the surface region are generated according to the grid generation control parameters, as shown in the following formula: Figure 6

[0080] S221, setting hard points on each geometric boundary of the target region to be divided according to the grid size in the grid generation control parameters;

[0081] S222, adjusting the spacing of the hard points so that the hard points between two adjacent target regions to be divided are completely overlapped.

[0082] Specifically, the hard points are set on the geometric boundaries of each surface region according to the grid size, and the spacing is adjusted to ensure that the hard points between the surfaces are completely overlapped. In addition, during the grid division process, no new nodes are generated between the hard points, as shown in the following formula: Figure 7 The hard point marks on the boundaries of the example container do not have new nodes, which ensures the displacement coordination.

[0083] It should be noted that, when generating grid hard point seeds, the parameterization control of the grid hard points is performed according to the geometric boundaries of each target region to be divided, which can specifically include: equal interval segmentation according to a preset grid size, or directly setting hard points according to a preset segmentation number. According to the segmentation setting of the boundary, if the size setting of the common boundary conflicts, the priority of line size> surface size> global size is used for re-setting. According to the boundary segmentation setting of each sub-region, local adjustment is performed to meet the principle that the boundary segmentation is as even as possible, and the segmentation numbers of similar opposite edges are consistent. According to the density of the hard point seeds, the Lagrange interpolation algorithm is used to smooth the spacing of the seeds between adjacent boundaries to avoid sudden changes in the grid size.

[0084] S230, determining a grid division adaptation mode adapted to the geometric features of the target region to be divided according to the geometric features of each target region to be divided and the grid division preselected mode.

[0085] In the embodiment of the present application, the grid division adaptation mode adapted to the geometric features of the target region to be divided is determined based on the geometric features of the target region to be divided and in combination with the grid division preselected mode input by the user.

[0086] Specifically, the grid division adaptation mode adapted to the geometric features of the target region to be divided is determined according to the geometric features of each target region to be divided and the grid division preselected mode, as shown in the following formula:​Figure 8 As shown, comprising:

[0087] S231, when the current target region to be divided is a geometric regular region, determining a grid division adaptation mode according to whether the grid division preselected mode is adapted to the geometric characteristics of the geometric regular region;

[0088] It should be understood that if the current target region to be divided is a geometric regular region, in addition to the grid division preselected mode, it is further necessary to determine whether the geometric regular region is a normalized rectangular surface, and then determine the grid division adaptation mode adapted thereto.

[0089] Specifically, when the current target region to be divided is a geometric regular region, determining a grid division adaptation mode according to whether the grid division preselected mode is adapted to the geometric characteristics of the geometric regular region, comprising:

[0090] 1) If the current target region to be divided is a geometric regular region, determining the type of the grid division preselected mode;

[0091] 2) If the type of the grid division preselected mode is mapping subdivision, determining whether the current geometric regular region is a normalized rectangular surface in the parameter space;

[0092] 3) If the current geometric regular region is a normalized rectangular surface in the parameter space, determining that the grid division adaptation mode is the grid division preselected mode;

[0093] 4) If the current geometric regular region is a non-normalized rectangular surface in the parameter space, prompting the user that the grid division fails;

[0094] 5) If the type of the grid division preselected mode is free subdivision, performing partition processing on the current geometric regular region to obtain a plurality of normalized rectangular surfaces, and determining that the grid division adaptation mode of each normalized rectangular surface is mapping subdivision.

[0095] It should be understood that firstly, the type of the mesh partition pre-selection mode for the current geometric regular region is judged, if the type of the mesh partition pre-selection mode is mapping partition, it is further judged whether the geometric regular region is a normalized rectangular surface, only if the geometric regular region is a normalized rectangular surface, the mapping partition can be directly adapted, if the geometric regular region is not a normalized rectangular surface, since the user input mesh partition pre-selection mode is mapping partition, it cannot be executed according to the mesh partition pre-selection mode, therefore, the user is prompted with a mesh partition failure prompt information. If the type of the mesh partition pre-selection mode is free partition (the type of the free partition can be divided into two cases, one case is that the user really pre-selects the free partition, and the other case is that the user does not select any mode and defaults it to the free partition), whether the current geometric regular region is a normalized rectangular surface or not, the partition processing is performed to obtain a plurality of normalized rectangular surfaces, and then the mesh partition is performed according to the mapping partition mode, that is, when the mesh partition pre-selection mode is the free partition, the automatic mesh partition is performed according to the mapping partition mode, that is, the finally determined mesh partition adaptation mode is the mapping partition.

[0096] In the embodiment of the present application, the mesh generation result of the nuclear engineering typical component is obtained by performing mesh partition on the result of the region identification of the geometric model according to the mesh partition strategy, which comprises:

[0097] (1) For the plurality of geometric regular regions identified from the geometric model, the structured quadrilateral surface mesh is generated for the geometric regular regions one by one according to the mapping partition mode;

[0098] (2) The quadrilateral surface mesh is optimized by a mesh smoothing algorithm.

[0099] It should be understood that when the mesh partition is specifically performed, for the geometric regular region, the mesh partition is performed according to the determined mesh partition strategy, since it is the mesh partition of the geometric regular region, the finally obtained is a structured mesh.

[0100] In the embodiment of the present application, the structured mesh generated by the mapping partition mode can specifically include: establishing a parameter coordinate system for a standard geometric body such as a cylinder (surface), a cuboid (surface), a sphere (surface), and realizing isoparametric transformation mesh partition through coordinate mapping.

[0101] In addition, the quadrilateral mesh proportion threshold is set in the free mesh region, when the pure quadrilateral mesh is required and the free mesh quality does not meet the preset index, the triangular mesh is automatically switched, and each triangle is cut into three quadrilaterals.

[0102] Specifically, based on the shape and parameter definitions of components, typical component geometry can be simplified into basic geometric shapes or combinations of basic geometric shapes such as lines, planes, spheres, ellipsoids, circular arcs, cuboids, and spheres. According to the enterprise standard specification "Classification and Establishment of Parametric Models for Typical Nuclear Engineering Components," the geometric models of various typical nuclear engineering components can be preprocessed, decomposing the geometric models into combinations of different basic geometric shapes and saving them as a general preprocessing template for similar typical nuclear engineering components. In the specific scenario of generating parameterized structural meshes for components, the type of component must first be obtained. Then, a preprocessing template of the same type can be applied to decompose the component into corresponding basic geometric shapes. Simultaneously, the shape parameters of the basic geometric shapes are calculated based on the given component geometric parameters. To ensure the integrity and consistency of the structural mesh, the number of seed points on opposite edges within the same geometric shape must be consistent, and the distribution of seed points on the same edge across different geometric shapes must also be consistent. In this embodiment of the invention, the container head is a sphere, and a spherical template is used to generate the structural mesh; the container cylinder is a cylinder, and a cylindrical template is used to generate the structural mesh, as shown below. Figure 9 As shown.

[0103] Therefore, for geometrically regular regions, a generation function from a pre-set mesh structured partitioning library is selected based on the geometric characteristics and parametric equations of the geometrically regular regions. The mesh size and hard points are then passed into the generation function based on the boundary hard points of the geometrically regular regions to generate a structured mesh.

[0104] S232. When the target area to be divided is a geometrically irregular area, the corresponding mesh division adaptation method is determined according to the irregularity type of the geometrically irregular area. The irregularity type of the geometrically irregular area includes at least the area type of stress concentration and the area type with stress verification requirements.

[0105] In this embodiment of the invention, for geometrically irregular regions, the corresponding mesh generation adaptation methods are determined for region types with stress concentration and region types with stress verification requirements.

[0106] Specifically, when the target region to be divided is a geometrically irregular region, the corresponding mesh division adaptation method is determined according to the irregularity type of the geometrically irregular region, including:

[0107] 1) If the irregularity type of the current geometrically irregular region is a stress-concentrated surface region, then the mesh generation adaptation method is determined to include free meshing and mapped meshing, wherein the stress-concentrated surface region includes at least thin-walled regions and open-hole regions.

[0108] It should be understood that for the stress concentration area type of thin-walled, medium-thick plate structure and opening area, a plurality of regular grids are first generated in the opening area, and the remaining area is divided by a free grid of mixed triangles and quadrilaterals.

[0109] 2) If the irregular type of the current irregular geometry region is a body region with stress checking requirements, it is determined that the grid division adaptation mode includes free division and sweep division, wherein the body region with stress checking requirements at least includes a nozzle region and a foundation region.

[0110] Specifically, for the body region with stress checking requirements such as the nozzle root, the equipment connection part, the plant foundation and the containment bottom plate region, a sweep division mode can be used to generate a mixed grid of hexahedrons and triangular prisms.

[0111] In the embodiment of the present application, the grid generation result of the nuclear engineering typical component is obtained by grid dividing the region identification result of the geometry model according to the grid division strategy, including:

[0112] 1) For the face region of stress concentration identified by the geometry model region, a source face grid is generated according to the free division or mapping division mode;

[0113] Specifically, for the thin-walled and opening region, after generating a structured transition grid at the opening according to the mapping division or free division mode, the remaining part is free divided to generate a mixed face grid.

[0114] In the embodiment of the present application, for the opening region, 3-5 layers of regular quadrilateral transition grids are generated at the opening edge, and then gradually transition to the remaining free grid region; for the free grid region, if the subsequent simulation solver requires pure quadrilateral grid, and the free grid quality does not meet the preset index, or the division fails, automatically switch to triangular grid, and then cut each triangular grid into three quadrilateral grids by taking the center of gravity and the midpoint of the edge line.

[0115] Further specifically, when performing unstructured grid division, the seed point positions on the boundaries of each region are strictly fixed by preset grid size, and then free grid division is performed. For volume grid, the face grid division on all faces is completed first, and then the internal volume grid is free divided. As shown in Figure 10 The container example in the embodiment of the present application needs to be free divided in the region of the support, and there is no opening on the support. Directly apply Delaunay triangular division to free divide to generate triangular grid, and then merge the triangles to generate quadrilaterals to form a mixed grid.

[0116] 2) For the body region with stress checking requirement identified in the geometric model region, the body region with stress checking requirement is meshed according to the sweeping section mode, and a body mesh cell is obtained.

[0117] Specifically, for the nozzle, foundation and other regions, a basic surface is generated first, and then a body mesh is generated by sweeping.

[0118] It should be understood that, for the nozzle section, foundation surface and other information in the geometric model, a mapping mesh division or free mesh division method is used to divide the basic source surface mesh for sweeping. Specifically, the topology direction of the sweeping path is defined according to the nozzle axis, foundation depth direction and other information in the geometric model; according to the sweeping path, hard point seeds on the path are defined by setting the mesh size; according to the sweeping path and the basic surface mesh, the body mesh is generated by sweeping according to the mesh size parameter; according to the body mesh generated by sweeping, a local remapping algorithm is used to ensure the normal consistency and volume stability of the hexahedral cell.

[0119] Further specifically, in the embodiment of the present application, the nozzle is ignored when the container itself is simulated and analyzed, and the container itself uses shell cells. When the nozzle on the container is analyzed for stress analysis at the welding position, local modeling and meshing of the nozzle are required, and at this time, the whole body mesh is used, and the container wall, nozzle and weld seam all use the body mesh cells generated by sweeping, as shown in Figure 11 .

[0120] S233, when the current target region to be divided is a physical connection simulation region, the mesh division adaptation mode is determined according to the physical connection mode.

[0121] It should be understood that, for the container cylinder and the surrounding support, a search algorithm is used to automatically establish a surface-to-surface contact pair and generate a point-to-surface contact element CONTA175 and a target element TARGE170, which are used to simulate physical problems such as welding and rigid device fixation; for the container cylinder and the anti-falling fixation device, the degrees of freedom are coupled CP to define the node degrees of freedom at a specific height of the cylinder, which are used to simulate rigid connection problems.

[0122] Therefore, when the current target region to be divided is a physical connection simulation region, the mesh division adaptation mode is determined according to the physical connection mode, including:

[0123] If the current target region to be divided is a welding region, the mesh division adaptation mode is determined to include contact element simulation.

[0124] If the current target region to be divided is a rigid connection region, the mesh division adaptation mode is determined to include constraint element simulation.

[0125] It should be noted that the contact unit includes face-face contact pairs and point-face contact pairs, and the constraint unit includes multi-point constraints and rigid area constraints.

[0126] In the embodiment of the present application, the contact unit and the constraint unit are generated based on the generated component grid, comprising:

[0127] According to the parts that need to be welded in the geometric component, the contact unit is generated in batches, the face-face contact pair is generated, or the mass point unit is created first, and then the point-face contact pair is created;

[0128] According to the parts that need to be externally rigidly constrained in the geometric component, the constraint unit is created, and the degree of freedom is set.

[0129] Specifically, in the typical components of nuclear engineering, there are often parts that need rigid devices and welding fixation. In this case, through the targeted contact unit batch creation method, the nodes and units that need to be matched can be selected first, then the KNN algorithm is called to obtain the nearest node pair, and finally the batch creation of the contact unit is performed. As shown in Figure 12 The orange ring in the middle of the container is the iron hoop for fixation in reality, and the remaining orange triangular parts are the contact units established on the container. Therefore, compared with the prior art, since there is no point-to-body contact unit type in ANSYS, point-to-point contact is used for simulation. In this way, when creating the connection between the flange, support and other components and the cylinder, a large number of node matching is required, which is time-consuming and laborious for manual operation and prone to errors. The efficiency can be effectively improved and the accuracy can be improved.

[0130] In the embodiment of the present application, after the line, surface and volume grid division is completed, quality inspection and local optimization are performed, specifically, further comprising:

[0131] 1) Generate a grid quality inspection file, the grid quality inspection file comprising a plurality of grid quality evaluation indexes;

[0132] 2) Determine whether there are grid units that do not meet the requirements according to the inspection results of the grid quality inspection file;

[0133] It should be understood that according to the hybrid grid, Jacobian matrix, volume distortion rate and aspect ratio detection are performed to obtain the substandard area.

[0134] 3) If there are, the grid units that do not meet the requirements are optimized according to the grid smoothing algorithm.

[0135] It should be understood that for the substandard area, the front push method is used for local grid reconstruction while maintaining the node continuity of the adjacent sub-area grid.

[0136] In the embodiments of the present application, specifically, after mesh division, a mesh quality check text file is output, and various mesh quality evaluation indexes are used, such as the aspect ratio of mesh elements, the Jacobian determinant value, the warping degree, etc., to evaluate the quality of the optimized mesh. For mesh elements whose quality does not meet the requirements, a mesh smoothing algorithm such as Laplace smoothing algorithm is used to adjust the position of the mesh nodes to improve the mesh quality. In the adjustment process, the constraint condition is used to ensure that the mesh fitting degree with the component geometry shape does not change. For example, for a quadrilateral mesh element with an excessively large aspect ratio, the positions of the four vertices are adjusted by the algorithm to make the aspect ratio close to a reasonable range, while ensuring that the mesh can still accurately cover the corresponding geometric area of the component. At the same time, if the solver requires pure quadrilateral mesh and free division fails, a triangular mesh is generated, and then the center of gravity and the midpoint of the edge of each triangle are taken to divide each triangle into three quadrilaterals. As shown in the following figure. Figure 13

[0137] In summary, the method for quickly generating mesh for typical components in nuclear engineering provided by the present application can automatically call mesh attribute setting, mesh size setting and mesh division functions through command stream execution according to the requirements of mesh quick generation, to generate the required high-quality simulation mesh. Through the pre-set mesh division strategy of the typical components in nuclear engineering, the designer only needs to adjust the key parameters and then drive the command stream to run, so that the mesh remapping and updating can be completed in a short time, avoiding tedious UI operation and improving the mesh generation efficiency. At the same time, the method provides a method for batch defining contact elements, which solves the special mesh problem in the mechanical structure analysis of nuclear engineering and further improves the mesh generation efficiency. Therefore, the method for quickly generating mesh for typical components in nuclear engineering is compatible with APDL command stream to realize mesh division, without manual operation, and improves the mesh division efficiency. In addition to providing various mesh generation methods such as free section, mapping section, and sweep section for building components in nuclear engineering, such as walls, boards, beams, columns, and end covers, cylinder bodies, supports, etc. in nuclear engineering container equipment, the method also provides a batch creation algorithm for contact elements, so that the mesh division work for typical components in nuclear engineering can be quickly, efficiently and accurately completed, providing strong support for engineering application in the field of nuclear engineering.

[0138] It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present application, and the present application is not limited thereto. Those skilled in the art can make various modifications and improvements without departing from the spirit and essence of the present application, and these modifications and improvements are also considered to be within the protection scope of the present application.​

Claims

1. A method for rapid mesh generation for typical components in nuclear engineering, characterized in that, include: The system obtains the geometric model and mesh generation control parameters of a typical nuclear engineering component to be processed, input by the user in a command stream manner. The geometric model includes any one or more of nuclear power plant building structures, storage containers, and transport containers. The mesh generation control parameters include at least mesh size, mesh topology type, and mesh partitioning pre-selection method. The mesh partitioning pre-selection method includes one or more of free partitioning, mapped partitioning, and swept partitioning. Region identification is performed based on the topology and geometric features of the geometric model, and a mesh partitioning strategy for the geometric model is determined based on the results of the region identification and the mesh generation control parameters. The mesh partitioning strategy includes at least the results of the region identification of the geometric model and a mesh partitioning adaptation method adapted to the results of the region identification of the geometric model. The mesh partitioning adaptation method includes at least the mesh partitioning pre-selection method. Based on the region identification results of the geometric model according to the meshing strategy, mesh generation results of the typical nuclear engineering components are obtained. The process includes: identifying regions based on the topology and geometric features of the geometric model; and determining the mesh generation strategy of the geometric model based on the results of the region identification and the mesh generation control parameters, including: Based on the topology and geometric features of the geometric model, the typical components of the nuclear engineering are identified to obtain multiple target regions to be divided. The target regions to be divided include at least geometrically regular regions, geometrically irregular regions, and physically connected simulation regions. The geometrically regular regions include geometric regions that can be expressed by a single parametric equation. The geometrically irregular regions include regions that can be expressed by piecewise or combined parametric equations and regions that can be solved and expressed by any one or more combinations of fitting, polynomial approximation, and approximate solution. The physically connected simulation regions include two regions that are physically connected in a fixed way but are not geometrically connected. Based on the mesh generation control parameters, generate mesh hard point seeds for each geometric boundary of the target region to be divided; For each of the target regions to be divided, a mesh division adaptation method is determined that is compatible with the geometric features of the target regions to be divided, based on the geometric features of each target region to be divided and the mesh division pre-selection method. For each of the target regions to be divided, a mesh partitioning adaptation method is determined that matches the geometric features of the target region to be divided, based on the mesh partitioning pre-selection method. This includes: When the target region to be divided is a geometrically regular region, the mesh division adaptation method is determined based on whether the mesh division pre-selection method is compatible with the geometric features of the geometrically regular region; When the target region to be divided is a geometrically irregular region, the corresponding mesh division adaptation method is determined according to the irregularity type of the geometrically irregular region. The irregularity type of the geometrically irregular region includes at least the region type with stress concentration and the region type with stress verification requirements. When the target region to be divided is a physically connected simulation region, the mesh division adaptation method is determined according to the physical connection method. When the target region to be divided is a physically connected simulation region, the mesh division adaptation method is determined according to the physical connection method, including: If the target area to be divided is a welding area, then the mesh division adaptation method is determined to include contact element simulation; If the target region to be divided is a rigidly connected region, then the mesh division adaptation method is determined to include constraint element simulation.

2. The method for rapid mesh generation for typical nuclear engineering components according to claim 1, characterized in that, When the target region to be divided is a geometrically regular region, the mesh division adaptation method is determined based on whether the pre-selected mesh division method is compatible with the geometric features of the geometrically regular region, including: If the target region to be divided is a geometrically regular region, then determine the type of the pre-selected grid division method; If the type of the mesh division preselection method is mapping partitioning, then determine whether the current geometric regular region is a normalized rectangular surface in the parameter space; If the current geometric rule region is a normalized rectangular surface in the parameter space, then the mesh division adaptation method is determined to be the mesh division pre-selection method; If the current geometric region is a non-normalized rectangular surface in the parameter space, the user is prompted that the mesh generation failed. If the type of the mesh partitioning preselection method is free partitioning, then the current geometric regular region is partitioned to obtain multiple normalized rectangular surfaces, and the mesh partitioning adaptation method of each normalized rectangular surface is determined to be mapping partitioning.

3. The method for rapid mesh generation for typical nuclear engineering components according to claim 2, characterized in that, Based on the region identification results of the geometric model according to the aforementioned meshing strategy, mesh generation results of the typical nuclear engineering components are obtained, including: For the multiple geometric regular regions identified in the geometric model region, a structured quadrilateral mesh is generated for each of the geometric regular regions according to the mapping and partitioning method; The quadrilateral mesh is optimized using a mesh smoothing algorithm.

4. The method for rapid mesh generation for typical nuclear engineering components according to claim 1, characterized in that, When the target region to be divided is a geometrically irregular region, the corresponding mesh division adaptation method is determined according to the irregularity type of the geometrically irregular region, including: If the irregularity type of the current geometrically irregular region is a stress-concentrated surface region, then the mesh generation adaptation method is determined to include free meshing and mapped meshing, wherein the stress-concentrated surface region includes at least thin-walled regions and open-hole regions. If the irregularity type of the current geometrically irregular region is a volume region with stress verification requirements, then the mesh generation adaptation method is determined to include free meshing and swept meshing, wherein the volume region with stress verification requirements includes at least the pipe region and the foundation region.

5. The method for rapid mesh generation for typical nuclear engineering components according to claim 4, characterized in that, Based on the region identification results of the geometric model according to the aforementioned meshing strategy, mesh generation results of the typical nuclear engineering components are obtained, including: For the surface regions with stress concentration identified in the geometric model region, a source surface mesh is generated according to the free meshing or mapping meshing method; for the volume regions with stress verification requirements identified in the geometric model region, the volume regions with stress verification requirements are meshed according to the sweep meshing method to obtain volume mesh elements.

6. The method for rapid mesh generation for typical nuclear engineering components according to claim 1, characterized in that, Generate mesh hard point seeds for each geometric boundary of the target region to be divided according to the mesh generation control parameters, including: Hard points are set on each geometric boundary of the target region to be divided according to the mesh size in the mesh generation control parameters; The spacing of the hard points is adjusted so that the hard points between two adjacent target areas to be divided completely overlap.

7. The method for rapid mesh generation of typical nuclear engineering components according to any one of claims 1 to 6, characterized in that, This also includes the step of meshing the geometric model after the result of region identification based on the meshing strategy: Generate a mesh quality inspection file, which includes various mesh quality evaluation indicators; Based on the inspection results of the mesh quality inspection file, determine whether there are any mesh cells in the mesh that do not meet the requirements; If they exist, the grid cells that do not meet the requirements will be optimized according to the grid smoothing algorithm.

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