Rapid grid generation method for nuclear engineering typical component

Abstract

The invention relates to the technical field of nuclear engineering mechanical simulation, and particularly discloses a rapid grid generation method for nuclear engineering typical components, which comprises the following steps: acquiring a geometric model and grid generation control parameters of a nuclear engineering typical component to be processed input by a user in a command stream mode; carrying out region identification according to the topological structure and the geometric features of the geometric model, and determining a grid division strategy of the geometric model according to a region identification result and grid generation control parameters, the grid division strategy at least comprises a region identification result of the geometric model and a grid division adaptation mode adapted to the region identification result of the geometric model, and the grid division adaptation mode at least comprises a grid division preselection mode; and according to a grid division strategy, performing grid division on a region identification result of the geometric model to obtain a grid generation result of the nuclear engineering typical component. According to the grid rapid generation method for the nuclear engineering typical component, the grid generation efficiency can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear engineering mechanics simulation, and in particular to a method for quickly generating a grid for typical components of nuclear engineering. Background Art

[0002] In the field of nuclear engineering, the design of nuclear power plants and container 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 meshing is a key prerequisite for finite element analysis. With the continuous advancement of technology, the requirements for its accuracy and efficiency are also continuously improving.

[0003] At present, traditional mesh generation methods have many shortcomings when dealing with typical components of nuclear engineering. On the one hand, the geometric shapes of typical components of nuclear engineering are complex, including a large number of irregular surfaces, holes, and variable thickness areas. The existing general meshing algorithms are 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, which affects the accuracy of the analysis results. On the other hand, the requirements for mesh density of typical components of nuclear engineering in different parts are quite different. For example, fine meshes are required in stress concentration areas to accurately capture stress distribution, while in some areas with relatively small stress changes, the mesh density can be appropriately reduced to reduce the amount of calculation. However, it is difficult for the existing mesh generation methods to flexibly realize adaptive mesh density control according to the structural characteristics and analysis requirements of the components. In addition, when meshing typical components of large-scale nuclear engineering, the UI-based meshing method is inefficient and consumes a lot of time and manpower.

[0004] Therefore, how to improve the efficiency of grid generation has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] The present invention provides a method for quickly generating a grid for a typical component of a nuclear engineering, which solves the problem of low efficiency in generating a grid for a typical component of a nuclear engineering in the related art.

[0006] As one aspect of the present invention, a method for quickly generating a grid for a typical component of a nuclear engineering is provided, which comprises: Obtain the geometric model of typical nuclear engineering components to be processed and the grid generation control parameters input by the user in the form of a command stream. The geometric model includes any one or more of nuclear power plant building structures, storage containers, and transportation containers. The grid generation control parameters at least include grid size, grid topology type, and preselected grid division methods. The preselected grid division methods include one or more of free meshing, mapped meshing, and swept meshing; Perform region recognition based on the topological structure and geometric features of the geometric model, and determine the grid division strategy of the geometric model according to the results of the region recognition and the grid generation control parameters. Among them, the grid division strategy at least includes the results of the region recognition of the geometric model and the grid division adaptation method adapted to the results of the region recognition of the geometric model. The grid division adaptation method at least includes the preselected grid division methods; Perform grid division on the results of the region recognition of the geometric model according to the grid division strategy to obtain the grid generation result of the typical nuclear engineering component.

[0007] Further, performing region recognition based on the topological structure and geometric features of the geometric model, and determining the grid division strategy of the geometric model according to the results of the region recognition and the grid generation control parameters includes: Perform region recognition on the typical nuclear engineering component according to the topological structure and geometric features of the geometric model to obtain multiple target regions to be divided. The target regions to be divided at least include geometric regular regions, geometric irregular regions, and physical connection simulation regions. The geometric regular regions include geometric regions that can be expressed by a single parametric equation. The geometric 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 physical connection simulation regions include regions where two physics are connected by a fixed method and there is no geometric connection; Generate grid hard point seeds for each geometric boundary of the target region to be divided according to the grid generation control parameters; Determine the grid division adaptation method 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 preselected grid division methods.

[0008] Further, determining the grid division adaptation method adapted to the geometric features of each target region to be divided according to the geometric features of each target region to be divided and the preselected grid division methods includes: When the current target region to be divided is a geometric regular region, determine the grid division adaptation method according to whether the preselected grid division method is adapted to the geometric features of the geometric regular region; When the current target area to be partitioned is a geometrically irregular area, determine the corresponding mesh partitioning adaptation method according to the irregular type of the geometrically irregular area, and the irregular type of the geometrically irregular area at least includes the area type with stress concentration and the area type with stress checking requirements; When the current target area to be partitioned is a physical connection simulation area, determine the mesh partitioning adaptation method according to the physical connection method.

[0009] Furthermore, when the current target area to be partitioned is a geometrically regular area, determine the mesh partitioning adaptation method according to whether the preselected mesh partitioning method is adapted to the geometric characteristics of the geometrically regular area, including: If the current target area to be partitioned is a geometrically regular area, then judge the type of the preselected mesh partitioning method; If the type of the preselected mesh partitioning method is mapped meshing, then judge whether the current geometrically regular area is a normalized rectangular surface in the parameter space; If the current geometrically regular area is a normalized rectangular surface in the parameter space, then determine the mesh partitioning adaptation method as the preselected mesh partitioning method; If the current geometrically regular area is a non-normalized rectangular surface in the parameter space, prompt the user that the mesh partitioning fails; If the type of the preselected mesh partitioning method is free meshing, then perform zoning processing on the current geometrically regular area to obtain multiple normalized rectangular surfaces, and determine that the mesh partitioning adaptation method for each normalized rectangular surface is mapped meshing.

[0010] Furthermore, perform mesh partitioning on the result of the area recognition of the geometric model according to the mesh partitioning strategy to obtain the mesh generation result of the typical component of the nuclear engineering, including: For multiple geometrically regular areas identified in the geometric model area, generate structured quadrilateral surface meshes for the geometrically regular areas one by one according to the mapped meshing method; Optimize the quadrilateral surface mesh according to the mesh smoothing algorithm.

[0011] Furthermore, when the current target area to be partitioned is a geometrically irregular area, determine the corresponding mesh partitioning adaptation method according to the irregular type of the geometrically irregular area, including: If the irregular type of the current geometrically irregular area is a surface area with stress concentration, then determine that the mesh partitioning adaptation method includes free meshing and mapped meshing, where the surface area with stress concentration at least includes a thin-walled area and an opening area; If the irregular type of the current geometric irregular region is a volume region with stress checking requirements, it is determined that the mesh division adaptation method includes free meshing and swept meshing, where the volume region with stress checking requirements includes at least a nozzle region and a foundation region.

[0012] Further, according to the mesh division strategy, mesh division is performed on the result of region recognition of the geometric model to obtain the mesh generation result of the typical nuclear engineering component, including: For the surface region with stress concentration identified in the geometric model region, source surface meshes are generated according to the free meshing or mapped meshing method; for the volume region with stress checking requirements identified in the geometric model region, the volume region with stress checking requirements is meshed according to the swept meshing method to obtain volume mesh elements.

[0013] Further, when the current target region to be divided is a physical connection simulation region, the mesh division adaptation method is determined according to the physical connection method, including: If the current target region to be divided is a welding region, it is determined that the mesh division adaptation method includes contact element simulation; If the current target region to be divided is a rigid connection region, it is determined that the mesh division adaptation method includes constraint element simulation.

[0014] Further, according to the mesh generation control parameters, mesh hard point seeds are generated for each geometric boundary of the target region to be divided, 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 regions to be divided completely coincide.

[0015] Further, it also includes the following steps after the step of performing mesh division on the result of region recognition of the geometric model according to the mesh division strategy: Generate a mesh quality inspection file, and the mesh quality inspection file includes various mesh quality evaluation indicators; Judge whether there are mesh elements that do not meet the requirements according to the inspection result of the mesh quality inspection file; If so, optimize the mesh elements that do not meet the requirements according to the mesh smoothing algorithm.

[0016] The grid rapid generation method for typical components in nuclear engineering provided by the present invention inputs the geometric model of the to-be-processed typical components in nuclear engineering and grid generation control parameters by obtaining the user's existing command stream, and then performs processing such as region recognition on the geometric model, and determines the grid division strategy corresponding to each region after region recognition, so that the grid division of the typical components in nuclear engineering can be realized according to the determined grid division strategy. This grid rapid generation method for typical components in nuclear engineering of the present invention realizes the acquisition of user input information in the form of command stream, and then realizes grid division. It does not require manual operation by the user and can automatically realize grid division without excessive interaction with the user, thus effectively improving the grid generation efficiency. Brief Description of the Drawings

[0017] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and are used to explain the present invention together with the following specific embodiments, but do not constitute a limitation to the present invention.

[0018] Figure 1 It is a flowchart of the grid rapid generation method for typical components in nuclear engineering provided by the present invention.

[0019] Figure 2 It is a schematic diagram of receiving and displaying the geometric model provided by the present invention.

[0020] Figure 3 It is a schematic diagram of region recognition of the geometric model provided by the present invention.

[0021] Figure 4 It is a schematic diagram of displaying the assignment of geometric attributes provided by the present invention.

[0022] Figure 5 It is a flowchart of the method for determining the grid division strategy of the geometric model provided by the present invention.

[0023] Figure 6 It is a flowchart of the method for generating grid hard point seeds provided by the present invention.

[0024] Figure 7 It is a schematic diagram of displaying the grid hard point seed points provided by the present invention.

[0025] Figure 8 It is a flowchart of the method for determining the grid division adaptation method provided by the present invention.

[0026] Figure 9 It is a schematic diagram of the structured grid of the typical component provided by the present invention.

[0027] Figure 10 It is a schematic diagram of the grid generated by free meshing provided by the present invention.

[0028] Figure 11Schematic diagram of the mesh generated by sweeping dissection provided by the present invention.

[0029] Figure 12 Schematic diagram of batch generation of the contact unit and constraint unit meshes provided by the present invention.

[0030] Figure 13 Schematic diagram of directly cutting a triangular mesh into a quadrilateral mesh when the pure quadrilateral mesh division fails provided by the present invention. Detailed implementation manners

[0031] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0032] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to describe the embodiments of the present invention here. In addition, the terms "comprising" and "having" 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 need to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] In this embodiment, a method for quickly generating a mesh for typical components in nuclear engineering is provided. Figure 1 It is a flowchart of the method for quickly generating a mesh for typical components in nuclear engineering provided by the embodiment of the present invention, as Figure 1 shown, including: S100. Obtain the geometric model of the typical component in nuclear engineering to be processed and the mesh generation control parameters input by the user in the form of a command stream. The geometric model includes any one or more of nuclear power plant building structures, storage containers, and transportation containers. The mesh generation control parameters at least include a mesh size, a mesh topology type, and a mesh division preselection method. The mesh division preselection method includes one or more of free dissection, mapped dissection, and sweeping dissection; In an embodiment of the present invention, the user inputs the geometric model of a typical nuclear engineering component to be processed in the form of a command stream, and at the same time, the mesh generation control parameters can also be input in the form of a command stream. Specifically, the command stream can specifically be an APDL command stream.

[0035] Specifically, the nuclear power plant building structure can specifically include a nuclear power plant building, etc.; the mesh size in the mesh generation control parameters can specifically be the maximum side length of the mesh surface, or the maximum length of the diagonal of the mesh surface, etc.; the mesh topology type can specifically be the shape of the mesh surface; the preselected mesh division method can be understood as the mesh division method preselected by the user. In an embodiment of the present invention, the preselected mesh division method includes one or more of free meshing, mapped meshing, and swept meshing. Among them, free meshing is applicable to both surface mesh generation and volume mesh generation, mapped meshing is only applicable to surface mesh generation, and swept meshing is only applicable to volume mesh generation. It should be noted here that if the user does not check the mesh division method, the default is the free meshing method.

[0036] Specifically, as Figure 2 shown, an embodiment of the present invention takes the geometric model of nuclear engineering mechanics as the geometric model of a three-leg container as an example to illustrate. After the user completes the modeling work or imports the model, an embodiment of the present invention can display the geometric model. The geometric model of this container contains 267 geometric surfaces.

[0037] S200. Perform region recognition according to the topological structure and geometric features of the geometric model, and determine the mesh division strategy of the geometric model according to the result of the region recognition and the mesh generation control parameters. Among them, the mesh division strategy at least includes the result of the region recognition of the geometric model and the mesh division adaptation method adapted to the result of the region recognition of the geometric model. The mesh division adaptation method at least includes the preselected mesh division method; In an embodiment of the present invention, region recognition is performed based on the topological structure of the geometric model. Specifically, the geometric features in the geometric model can be recognized through a feature recognition algorithm, and the recognized features are classified. Specifically, in this example of the present invention, based on geometric topology information, a feature recognition algorithm is used to recognize various geometric features in the container. The recognized features are classified into simple features and complex features. This example includes heads, cylinders, supports, bottom plates, etc. As Figure 3 shown, different regions are marked with different colors. For different types of features, different mesh generation strategies will be adopted subsequently.

[0038] Therefore, the block algorithm based on geometric feature recognition in the embodiments of the present invention decomposes the geometric model of typical components in nuclear engineering into target regions to be partitioned with simple geometric features. For different target regions to be partitioned, different grid division adaptation methods are determined in combination with grid generation control parameters, so as to obtain grid division strategies for different target regions to be partitioned.

[0039] S300. Perform grid division on the result of region recognition of the geometric model according to the grid division strategy to obtain the grid generation result of the typical component in nuclear engineering.

[0040] In the embodiments of the present invention, for the result of region recognition of the above geometric model, that is, for the result of region division of typical components in nuclear engineering, the determined grid division strategy is adopted for grid division to obtain the grid generation result.

[0041] Therefore, the method for quickly generating grids for typical components in nuclear engineering provided by the present invention inputs the geometric model of the typical component to be processed and the grid generation control parameters in the form of a user's command stream, and then performs processing such as region recognition on the geometric model, and determines the grid division strategy corresponding to each region after region recognition. Thus, the grid division of typical components in nuclear engineering can be realized according to the determined grid division strategy. This method for quickly generating grids for typical components in nuclear engineering of the present invention realizes the acquisition of user input information in the form of a command stream, and then realizes grid division, without the need for manual operation by the user, and can automatically realize grid division without excessive interaction with the user, thereby effectively improving the grid generation efficiency.

[0042] In the embodiments of the present invention, specifically, the grid generation control parameters may further include physical attributes such as materials, element types, cross-sections, real constants, and coordinate systems set on the geometric model. These attributes will be attached to the grid after grid division and become the physical attributes of the grid. As Figure 4 shown, first define information such as materials, cross-sections, real constants, and element types, and then attach numerical values such as the material number, element type number, cross-section number, real constant serial number, and coordinate system number of this container example to the geometric surface information.

[0043] In the embodiments of the present invention, region recognition is performed according to the topological structure and geometric features of the geometric model, and the grid division strategy of the geometric model is determined according to the result of region recognition and the grid generation control parameters. As Figure 5 shown, it includes: S210. Identify regions of the typical nuclear engineering components based on the topological structure and geometric features of the geometric model, obtaining multiple target regions to be partitioned. The target regions to be partitioned at least include 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 regions where two physics are connected in a fixed manner and there is no geometric connection; It should be understood that based on the topological structure of the geometric model, it is decomposed into a combination of multiple planes, surfaces, and solids through region identification, that is, multiple target regions to be partitioned are obtained. These target regions to be partitioned include multiple types, specifically including geometrically regular regions, geometrically irregular regions, and physically connected simulation regions. For different types of target regions to be partitioned, corresponding mesh partitioning strategies can be determined.

[0044] It should be noted that the geometrically regular regions specifically refer to regular geometric regions with parametric equations, while the geometrically irregular regions cannot be described by a single parametric equation. The geometrically irregular regions can specifically include stress concentration regions and regions with stress checking requirements. The physically connected simulation regions specifically refer to regions of the physical connection characteristics between components.

[0045] In the embodiment of the present invention, it should also be noted that the geometrically irregular regions can be further divided into simple geometrically irregular regions and complex geometrically irregular regions according to the complexity of computer programming. Among them, the simple geometrically irregular regions can specifically include regions that can be expressed by multiple segments or combined parametric equations; the complex geometrically irregular regions are regions that cannot be accurately expressed by parametric equations, specifically including regions that are solved and expressed by methods such as fitting, polynomial approximation, and approximate solution, such as high genus algebraic curves, pathological curves, geometries with non-closed solutions of equations, and some high-degree polynomial implicit surfaces.

[0046] S220. Generate mesh hard point seeds for each geometric boundary of the target regions to be partitioned according to the mesh generation control parameters; It should be understood that in order to avoid the situation of intersecting meshes during the mesh generation process, in the embodiment of the present invention, mesh hard point seeds are generated for the geometric boundaries of the target regions to be partitioned after region identification. Based on this method, the appearance of intersecting meshes can be effectively prevented, so that meshes that meet the simulation requirements and displacement coordination can be generated.

[0047] In the embodiment of the present invention, mesh hard point seeds for each geometric boundary of the surface region are generated according to the mesh generation control parameters, such asFigure 6 As shown in the figure, it includes: S221. Set hard points on each geometric boundary of the mesh size in the control parameters for the target area to be divided; S222. Adjust the spacing of the hard points so that the hard points between two adjacent target areas to be divided completely coincide.

[0048] Specifically, hard points are set on the geometric boundaries of each surface area according to the mesh size, and the spacing is adjusted to ensure that the hard points between the surfaces completely coincide. In addition, during the mesh division process, no new nodes are generated between the hard points. As Figure 7 shown in the figure, there are no new nodes between the hard point marks on the boundaries of the example container, ensuring displacement coordination.

[0049] It should be noted that when generating mesh hard point seeds, parametric control of mesh hard points is performed according to the geometric boundaries of each target area to be divided. Specifically, it may include: performing equidistant segmentation according to a preset mesh size, or directly setting hard points according to a preset number of segments. According to the segmentation settings of the boundaries, if there are conflicts in the size settings of the common boundaries, they are reset with the priority of line size > surface size > global size. According to the boundary segmentation settings of each sub-region, local adjustments are made to meet the principle that the boundary segmentation is preferably even and the number of segments of similar opposite sides is consistent. According to the density of the hard point seeds, the Lagrange interpolation algorithm is used to smooth the seed spacing between adjacent boundaries to avoid sudden changes in mesh size.

[0050] S230. Determine a mesh division adaptation method adapted to the geometric characteristics of the target area to be divided according to the geometric characteristics of each target area to be divided and the preselected mesh division method.

[0051] In the embodiment of the present invention, a mesh division adaptation method adapted to the geometric characteristics of the target area to be divided is determined based on the geometric characteristics of the target area to be divided and in combination with the preselected mesh division method input by the user.

[0052] Specifically, a mesh division adaptation method adapted to the geometric characteristics of the target area to be divided is determined according to the geometric characteristics of each target area to be divided and the preselected mesh division method. As Figure 8 shown in the figure, it includes: S231. When the current target area to be divided is a geometrically regular area, determine the mesh division adaptation method according to whether the preselected mesh division method is adapted to the geometric characteristics of the geometrically regular area; It should be understood that if the current target area to be divided is a geometrically regular area, in addition to relying on the preselected mesh division method, it is also necessary to further determine whether the geometrically regular area is a normalized rectangular surface, and then determine the adapted mesh division adaptation method.

[0053] Specifically, when the target area to be partitioned currently is a geometric regular area, determine the grid partitioning adaptation method according to whether the grid partitioning preselection method matches the geometric characteristics of the geometric regular area, including: 1) If the target area to be partitioned currently is a geometric regular area, then determine the type of the grid partitioning preselection method; 2) If the type of the grid partitioning preselection method is mapping dissection, then determine whether the current geometric regular area is a normalized rectangular surface in the parameter space; 3) If the current geometric regular area is a normalized rectangular surface in the parameter space, then determine the grid partitioning adaptation method as the grid partitioning preselection method; 4) If the current geometric regular area is a non-normalized rectangular surface in the parameter space, then prompt the user that the grid partitioning fails; 5) If the type of the grid partitioning preselection method is free dissection, then perform zoning processing on the current geometric regular area to obtain multiple normalized rectangular surfaces, and determine that the grid partitioning adaptation method for each normalized rectangular surface is mapping dissection.

[0054] It should be understood that first, determine the type of the grid partitioning preselection method for the current geometric regular area. If the type of the grid partitioning preselection method is mapping dissection, then it is necessary to further determine whether the geometric regular area is a normalized rectangular surface. Only when the geometric regular area is a normalized rectangular surface can it be directly adapted to mapping dissection. If the geometric regular area is not a normalized rectangular surface, since the grid partitioning preselection method input by the user is mapping dissection, it cannot be executed according to this grid partitioning preselection method. Therefore, a prompt message indicating that the grid partitioning fails will be displayed to the user. If the type of the grid partitioning preselection method is free dissection (the type of this free dissection can be divided into two cases. One case is that the user actually preselects free dissection, and the other case is that the user does not select any method and defaults it to free dissection), then regardless of whether the current geometric regular area is a normalized rectangular surface, zoning processing is performed to obtain multiple normalized rectangular surfaces, and then grid partitioning is performed on them according to the mapping dissection method. That is, for a geometric regular area, when the grid partitioning preselection method is free dissection, the grid partitioning will be executed according to the mapping dissection method automatically during the grid partitioning, that is, the finally determined grid partitioning adaptation method is mapping dissection.

[0055] In the embodiment of the present invention, perform grid partitioning on the result of the region recognition of the geometric model according to the grid partitioning strategy to obtain the grid generation result of the typical component of the nuclear engineering, including: (1) For multiple geometric regular areas recognized from the geometric model area, generate structured quadrilateral surface grids for the geometric regular areas one by one according to the mapping dissection method; (2)Optimize the quadrilateral surface mesh according to the mesh smoothing algorithm.

[0056] It should be understood that during the specific execution of mesh generation, for geometrically regular regions, the above-determined mesh generation strategy is followed. Since it is the mesh generation of geometrically regular regions, the finally obtained is a structured mesh.

[0057] In the embodiments of the present invention, generating a structured mesh by means of mapping dissection may specifically include: establishing a parametric coordinate system for standard geometric bodies such as a cylinder (surface), a cuboid (surface), a sphere (surface), etc., and realizing isoparametric transformation mesh generation through coordinate mapping.

[0058] In addition, set a proportion threshold of quadrilateral meshes in the free mesh area. When pure quadrilateral meshes are required and the quality of the free meshes does not meet the preset index, automatically switch to triangular meshes, and divide each triangle into three quadrilaterals.

[0059] Specifically, according to the shape and parameter definition of the component, the geometry of typical components can be geometrically simplified into basic geometric shapes or combinations of basic geometric shapes such as straight lines, planes, spherical surfaces, ellipsoidal surfaces, circular arc surfaces, cuboids, and spheres. According to the enterprise standard specification of "Classification and Establishment of Parametric Models of Typical Components in Nuclear Engineering", the geometric models of various typical components in nuclear engineering can be preprocessed, decomposed into combinations of different basic geometric shapes, and saved as a common preprocessing template for the same type of typical components in nuclear engineering. In the specific scenario of generating a parametric structural mesh for components, first, the type of the component needs to be obtained, and then the preprocessing template of the same type of component can be applied to decompose the component into corresponding basic geometric shapes. At the same time, according to the given geometric parameters of the component, the shape parameters of the basic geometric shapes are calculated. To ensure the integrity and consistency of the structural mesh, the number of seed points on opposite sides within the same geometric shape needs to be kept consistent, and the distribution of seed points on the same side in different geometric shapes also needs to be kept consistent. In the embodiments of the present invention, the container head is a spherical surface, and a spherical surface template is used to generate a structural mesh. The container cylinder is a cylindrical surface, and a cylindrical surface template is used to generate a structural mesh, as Figure 9 shown.

[0060] Therefore, for geometrically regular regions, according to the geometric characteristics and parametric equations of the geometrically regular regions, select the generation function in the preset mesh structuring library, and input the mesh size and hard points into the generation function according to the boundary hard points of the geometrically regular regions to generate a structured mesh.

[0061] S232. When the current target region to be meshed is a geometrically irregular region, determine the corresponding mesh generation adaptation method according to the irregular type of the geometrically irregular region. The irregular types of the geometrically irregular region at least include the region type with stress concentration and the region type with stress checking requirements; In the embodiments of the present invention, for geometrically irregular regions, they are specifically divided into a region type with stress concentration and a region type with stress checking requirements, and the corresponding mesh division adaptation methods are determined respectively.

[0062] Specifically, when the current target region to be divided is a geometrically irregular region, the corresponding mesh division adaptation method is determined according to the irregular type of the geometrically irregular region, including: 1) If the irregular type of the current geometrically irregular region is a surface region with stress concentration, it is determined that the mesh division adaptation method includes free meshing and mapped meshing, where the surface region with stress concentration includes at least a thin-walled region and an opening region; It should be understood that for stress concentration region types such as thin-walled, medium-thick plate structures, and opening regions, first, multiple circles of regular meshes are generated in the opening region, and the remaining region is meshed with a mixture of triangular and quadrilateral free meshes.

[0063] 2) If the irregular type of the current geometrically irregular region is a volume region with stress checking requirements, it is determined that the mesh division adaptation method includes free meshing and swept meshing, where the volume region with stress checking requirements includes at least a nozzle region and a foundation region.

[0064] Specifically, for volume regions with stress checking requirements such as the nozzle root, equipment connection parts, plant foundation, and containment floor regions, a swept meshing method can be specifically used to generate a mixture of hexahedrons and triangular prisms.

[0065] In the embodiments of the present invention, according to the mesh division strategy, the region recognition result of the geometric model is meshed to obtain the mesh generation result of the typical nuclear engineering component, including: 1) For the surface region with stress concentration identified in the geometric model region, source surface meshes are generated according to the free meshing or mapped meshing method; Specifically, for the thin-walled and opening regions, after generating structured transition meshes at the openings according to the mapped meshing or free meshing method, the remaining part is freely divided to generate mixed surface meshes.

[0066] In the embodiments of the present invention, for the opening region, 3 - 5 layers of regular quadrilateral transition meshes are generated at the opening edge, and then gradually transition to the remaining free mesh region; for the free mesh region, if the subsequent simulation solver requires pure quadrilateral meshes, and the free mesh quality does not meet the preset index, or the meshing fails, it is automatically switched to triangular meshes, and after taking the centroid and midpoints of the sides of each triangular mesh, it is divided into three quadrilateral meshes.

[0067] Further specifically, when performing unstructured mesh generation, the positions of the seed points on the boundaries of each region are strictly fixed by a preset mesh size, and then the mesh is freely generated. For volume meshes, first complete the surface mesh generation on all surfaces, and then freely generate the internal volume mesh. As Figure 10 shown, the region that needs to be freely meshed in the container example in the embodiment of the present invention is the support. There are no openings on the support, and Delaunay triangulation is directly applied to freely generate triangular meshes, and then the triangles are merged to form quadrilaterals to form a hybrid mesh.

[0068] 2) For the volume regions identified in the geometric model region that have stress checking requirements, mesh the volume regions with stress checking requirements according to the sweeping meshing method to obtain volume mesh elements.

[0069] Specifically, for regions such as nozzles and foundations, first generate the basic surfaces, and then sweep to generate volume meshes.

[0070] It should be understood that for information such as the nozzle cross-section and the foundation bottom surface in the geometric model, mapping mesh generation or free mesh generation methods are used to mesh the basic source surface meshes for sweeping. Specifically, for information such as the nozzle axis and the foundation depth direction in the geometric model, the topological direction of the sweeping path is defined; according to the sweeping path, hard point seeds on the path are defined by a set mesh size; according to the sweeping path and the basic surface mesh, volume meshes are swept and generated according to the mesh size parameters; according to the volume meshes generated by sweeping, a local remapping algorithm is used to ensure the normal consistency and volume stability of the hexahedron elements.

[0071] Further specifically, in the embodiment of the present invention, when performing simulation analysis on the container itself, the nozzles are ignored. The container itself uses shell elements. When performing stress analysis on the welded joints of the nozzles on the container, local re-modeling and mesh generation of the nozzles are required. At this time, volume meshes are used as a whole, and the container wall, nozzles, and welds all use the volume mesh elements generated by sweeping, as Figure 11 shown.

[0072] S233. When the current target region to be meshed is a physical connection simulation region, determine the mesh generation adaptation method according to the physical connection method.

[0073] It should be understood that for the container cylinder and the surrounding supports, a search algorithm is used to automatically establish surface-to-surface contact pairs, and point-to-surface contact elements CONTA175 and target elements TARGE170 are generated to simulate physical problems such as welding and rigid device fixation; for the container cylinder and the anti-drop fixation device, the degrees of freedom of the nodes at a specific height of the cylinder are defined by the degree-of-freedom coupling CP to simulate rigid connection problems.

[0074] Therefore, when the current target area to be partitioned is the physical connection simulation area, the grid partitioning adaptation method is determined according to the physical connection method, including: If the current target area to be partitioned is the welding area, it is determined that the grid partitioning adaptation method includes contact element simulation; If the current target area to be partitioned is the rigid connection area, it is determined that the grid partitioning adaptation method includes constraint element simulation.

[0075] It should be noted that the contact elements include surface-to-surface contact pairs and point-to-surface contact pairs, and the constraint elements include multi-point constraints and rigid region constraints.

[0076] In the embodiment of the present invention, contact elements and constraint elements are generated based on the generated component grids, including: According to the parts to be welded in the geometric component, contact elements are generated in batches to generate surface-to-surface contact pairs, or mass point elements are created first, and then point-to-surface contact pairs are created; According to the parts of the geometric component that need external rigid constraints, constraint elements are created and degrees of freedom are set.

[0077] Specifically, there are often parts in typical nuclear engineering components that require rigid devices and welding fixation. In this case, through a targeted method for batch creation of contact elements, the nodes and unit wholes that need to be matched can be selected first, and then the KNN algorithm is called to obtain the nearest node pairs, and finally the contact elements are created in batches. As Figure 12 shown, the orange ring in the middle of the container is the iron hoop for fixation in the real world, and the remaining orange triangular parts are the contact elements established on the container. Therefore, compared with the prior art, since there is no point-to-body contact element type in ANSYS, point-to-point contact is used for simulation. In this way, when creating the connection between components such as flanges and supports and the cylinder body, a large number of node matches are required, and the manual operation is time-consuming, laborious and error-prone. The efficiency can be effectively improved and the accuracy can be increased.

[0078] In the embodiment of the present invention, after the line, surface, and volume grid partitioning is completed, quality inspection and local optimization are performed. Specifically, it also includes: after the step of performing grid partitioning according to the result of region recognition of the geometric model according to the grid partitioning strategy: 1) Generate a grid quality inspection file, and the grid quality inspection file includes various grid quality evaluation indicators; 2) Determine whether there are grid elements that do not meet the requirements according to the inspection results of the grid quality inspection file; It should be understood that according to the hybrid grid, the Jacobian matrix, volume distortion rate, and aspect ratio are detected to obtain the non-compliant areas.

[0079] 3) If it exists, optimize the grid cells that do not meet the requirements according to the grid smoothing algorithm.

[0080] It should be understood that for non-compliant regions, the front-tracking method is used for local grid reconstruction while maintaining the node continuity of the grids in adjacent sub-regions.

[0081] In the embodiment of the present invention, specifically, after grid division, a grid quality inspection text file is output, and multiple grid quality evaluation indicators, such as the aspect ratio of grid cells, the value of the Jacobian determinant, the warping degree, etc., are used to evaluate the quality of the optimized grid. For grid cells with quality not meeting the requirements, a grid smoothing algorithm, such as the Laplace smoothing algorithm, etc., is used to adjust the positions of grid nodes to improve the grid quality. During the adjustment process, the fitting degree between the grid and the geometric shape of the component is ensured to remain unchanged through constraint conditions. For example, for a quadrilateral grid cell with an overly large aspect ratio, the positions of its four vertices are adjusted by the algorithm to make its aspect ratio close to a reasonable range while ensuring that the grid can still accurately cover the corresponding geometric area of the component. At the same time, if the solver requires pure quadrilateral grids and the free division fails, triangular grids are generated, and then the centroid and the midpoints of the sides of each triangle are taken to divide each triangle into three quadrilaterals. As Figure 13 shown.

[0082] In summary, the grid rapid generation method for typical components in nuclear engineering provided by the present invention, according to the requirements of grid rapid generation, automatically calls the grid attribute setting, grid size setting, and grid division functions through command flow to generate the required high-quality simulation grids; by presetting the grid division strategy for typical components in nuclear engineering, designers only need to adjust key parameters and then drive the command flow to run, and the grid remapping and update can be completed within a short time, avoiding cumbersome UI operations and improving the grid generation efficiency. At the same time, this method provides a method for batch defining contact elements to solve the special grid problems faced in the mechanical structure analysis of nuclear engineering and further improve the grid generation efficiency. Therefore, the grid rapid generation method for typical components in nuclear engineering is compatible with APDL command flow to achieve grid division, without manual operation, and improves the grid division efficiency. In addition to providing various grid generation methods such as free meshing, mapped meshing, and swept meshing for building components in nuclear engineering, such as walls, plates, beams, columns, and heads, cylinders, supports, etc. in nuclear engineering container equipment, it also provides a batch creation algorithm for contact elements, so as to be able to quickly, efficiently, and accurately complete the grid division work of typical components in nuclear engineering and provide strong support for engineering applications in the field of nuclear engineering.

[0083] It will be understood that the above embodiments are merely exemplary embodiments employed to illustrate the principles of the present invention, and the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A method for quickly generating grids for typical components in nuclear engineering, characterized in that, Including: Obtain the geometric model of typical components of nuclear engineering to be processed and grid generation control parameters input by the user in the form of a command stream. The geometric model includes any one or more of nuclear power plant building structures, storage containers, and transportation containers. The grid generation control parameters at least include grid size, grid topology type, and preselected grid division methods. The preselected grid division methods include one or more of free meshing, mapped meshing, and swept meshing; Perform region recognition according to the topological structure and geometric features of the geometric model, and determine the grid division strategy of the geometric model according to the results of the region recognition and the grid generation control parameters. Among them, the grid division strategy at least includes the results of the region recognition of the geometric model and the grid division adaptation methods adapted to the results of the region recognition of the geometric model. The grid division adaptation methods at least include the preselected grid division methods; Perform grid division on the results of the region recognition of the geometric model according to the grid division strategy to obtain the grid generation results of the typical components of nuclear engineering.

2. The grid rapid generation method for typical components in nuclear engineering according to claim 1, characterized in that Performing region recognition according to the topological structure and geometric features of the geometric model, and determining the grid division strategy of the geometric model according to the results of the region recognition and the grid generation control parameters, includes: Perform region recognition on the typical components of nuclear engineering according to the topological structure and geometric features of the geometric model to obtain a plurality of target regions to be divided. The target regions to be divided at least include 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 segmented 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 regions where two physics are connected by a fixed method and there is no geometric connection; Generate grid hard point seeds for each geometric boundary of the target regions to be divided according to the grid generation control parameters; Determine the grid division adaptation method adapted to the geometric features of the target regions to be divided according to the geometric features of each target region to be divided and the preselected grid division methods.

3. The grid rapid generation method for typical components in nuclear engineering according to claim 2, characterized in that Determining the grid division adaptation method adapted to the geometric features of the target regions to be divided according to the geometric features of each target region to be divided and the preselected grid division methods, includes: When the current target region to be divided is a geometrically regular region, determine the grid division adaptation method according to whether the preselected grid division method is adapted to the geometric features of the geometrically regular region; When the current target region to be divided is a geometrically irregular region, determine the corresponding grid division adaptation method according to the irregular type of the geometrically irregular region. The irregular types of the geometrically irregular regions at least include the region types with stress concentration and the region types with stress checking requirements; When the current target region to be divided is a physically connected simulation region, determine the grid division adaptation method according to the physical connection method.

4. The grid rapid generation method for typical components in nuclear engineering according to claim 3, characterized in that When the current target area to be partitioned is a geometric regular area, determine the mesh partitioning adaptation method according to whether the mesh partitioning preselection method matches the geometric characteristics of the geometric regular area, including: If the current target area to be partitioned is a geometric regular area, then determine the type of the mesh partitioning preselection method; If the type of the mesh partitioning preselection method is mapped dissection, then determine whether the current geometric regular area is a normalized rectangular surface in the parameter space; If the current geometric regular area is a normalized rectangular surface in the parameter space, then determine the mesh partitioning adaptation method as the mesh partitioning preselection method; If the current geometric regular area is a non-normalized rectangular surface in the parameter space, then prompt the user that the mesh partitioning fails; If the type of the mesh partitioning preselection method is free dissection, then perform zoning processing on the current geometric regular area to obtain multiple normalized rectangular surfaces, and determine that the mesh partitioning adaptation method for each normalized rectangular surface is mapped dissection.

5. The grid rapid generation method for typical components in nuclear engineering according to claim 4, characterized in that Perform mesh partitioning on the result of the region recognition of the geometric model according to the mesh partitioning strategy to obtain the mesh generation result of the typical component of nuclear engineering, including: For multiple geometric regular areas recognized in the geometric model area, generate structured quadrilateral surface meshes for the geometric regular areas one by one according to the mapped dissection method; Optimize the quadrilateral surface mesh according to the mesh smoothing algorithm.

6. The grid rapid generation method for typical components in nuclear engineering according to claim 3, wherein When the current target area to be partitioned is a geometric irregular area, determine the corresponding mesh partitioning adaptation method according to the irregular type of the geometric irregular area, including: If the irregular type of the current geometric irregular area is a surface area with stress concentration, then determine that the mesh partitioning adaptation method includes free dissection and mapped dissection, where the surface area with stress concentration includes at least a thin-walled area and an opening area; If the irregular type of the current geometric irregular area is a volume area with stress checking requirements, then determine that the mesh partitioning adaptation method includes free dissection and sweep dissection, where the volume area with stress checking requirements includes at least a nozzle area and a foundation area.

7. The grid rapid generation method for typical components in nuclear engineering according to claim 6, characterized in that Perform mesh partitioning on the result of the region recognition of the geometric model according to the mesh partitioning strategy to obtain the mesh generation result of the typical component of nuclear engineering, including: For the surface area with stress concentration recognized in the geometric model area, generate a source surface mesh according to the free dissection or mapped dissection method; for the volume area with stress checking requirements recognized in the geometric model area, perform mesh partitioning on the volume area with stress checking requirements according to the sweep dissection method to obtain volume mesh elements.

8. The grid rapid generation method for typical components in nuclear engineering according to claim 3, characterized in that, When the current target area to be partitioned is a physical connection simulation area, determine the mesh partitioning adaptation method according to the physical connection method, including: If the current target area to be partitioned is a welding area, then determine that the mesh partitioning adaptation method includes contact element simulation; If the current target area to be partitioned is a rigid connection area, then determine that the mesh partitioning adaptation method includes constraint element simulation.

9. The grid rapid generation method for typical components in nuclear engineering according to claim 2, characterized in that Generate mesh hard point seeds for each geometric boundary of the target area to be partitioned according to the mesh generation control parameters, including: Set hard points on each geometric boundary of the target area to be divided according to the mesh size in the generated control parameters of the mesh; Adjust the spacing of the hard points so that the hard points between two adjacent target areas to be divided completely coincide.

10. The grid rapid generation method for typical components in nuclear engineering according to any one of claims 1 to 9, characterized in that, It also includes the steps carried out after the step of dividing the mesh according to the result of the area recognition of the geometric model according to the mesh division strategy: Generate a mesh quality inspection file, and the mesh quality inspection file includes a variety of mesh quality evaluation indicators; Judge whether there are mesh elements that do not meet the requirements according to the inspection results of the mesh quality inspection file; If there are any, optimize the mesh elements that do not meet the requirements according to the mesh smoothing algorithm.

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