Sleeve finite element model establishment method for numerical calculation of heat flow field and related device

Abstract

The invention belongs to the technical field of engineering, and discloses a sleeve finite element model building method for numerical calculation of a heat flow field and a related device.A two-dimensional axial symmetry model of a sleeve is built according to the structural characteristics of a preset sleeve, and the structural characteristics comprise a solid area and a fluid area of the sleeve; repairing geometric defects in the two-dimensional axisymmetric model, and dividing a fluid region in the two-dimensional axisymmetric model into a geometric shape containing two groups of opposite sides to obtain a preprocessed two-dimensional axisymmetric model; drawing a grid of a fluid area and a grid of a solid area on the processed two-dimensional axisymmetric model to obtain a two-dimensional axisymmetric finite element model; and rotating the two-dimensional axisymmetric finite element model around the symmetry axis of the sleeve by a circle to obtain a sleeve finite element model for numerical calculation of a heat flow field. On the basis of the sweeping method, the casing heat flow field unstructured grid can be efficiently and accurately drawn, and then the accuracy and efficiency of casing heat flow field analysis are improved.

Description

Technical Field

[0001] The present invention belongs to the field of engineering technology, and particularly relates to a method for establishing a sleeve finite element model for numerical calculation of a thermal flow field and related devices. Background Art

[0002] As an important component in power equipment, the thermal flow field distribution of the sleeve is crucial for the operation safety and efficiency of the equipment. The axial length of the sleeve is often much larger than the radial length, and it contains many complex structures inside. Traditional mesh generation methods are difficult to obtain suitable meshes according to the geometric characteristics of the sleeve structure and the flow characteristics of the fluid inside the sleeve, and the generated meshes often lead to problems such as large computational amount and insufficient accuracy in the numerical calculation of the thermal flow field. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a method for establishing a sleeve finite element model for numerical calculation of a thermal flow field and related devices. Based on the sweeping method, the present invention can efficiently and accurately draw unstructured meshes of the sleeve thermal flow field, thereby improving the accuracy and efficiency of the sleeve thermal flow field analysis.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for establishing a sleeve finite element model for numerical calculation of a thermal flow field, comprising: Establish a two-dimensional axisymmetric model of the sleeve according to the structural characteristics of the preset sleeve, wherein the structural characteristics include the solid region and the fluid region of the sleeve; Repair the geometric defects in the two-dimensional axisymmetric model, and divide the fluid region in the two-dimensional axisymmetric model into geometric shapes including two sets of opposite sides to obtain a preprocessed two-dimensional axisymmetric model; Draw the mesh of the fluid region and the mesh of the solid region on the processed two-dimensional axisymmetric model to obtain a two-dimensional axisymmetric finite element model; Rotate the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the sleeve to obtain the sleeve finite element model for numerical calculation of the thermal flow field.

[0005] Preferably, the solid region of the sleeve includes a conductor, a flange and a core, and the fluid region of the sleeve includes air and oil.

[0006] Preferably, when repairing the geometric defects in the two-dimensional axisymmetric model, divide the geometric defects into geometric shapes including two sets of opposite sides.

[0007] Preferably, the geometric defects include sharp corners and slits, and the geometric shapes including two sets of opposite sides include rectangles or trapezoids.

[0008] Preferably, on the rotating surface of the casing in the processed two-dimensional axisymmetric model, a mapping method is used to draw the grid of the fluid region to generate a mapped grid; a free triangular mesh generation method is used to draw the grid of the solid region to generate a free triangular mesh.

[0009] Preferably, when drawing the grid of the fluid region and the grid of the solid region on the processed two-dimensional axisymmetric model, the grid size is refined to the standard of grid-independent solution. The determination process of the grid-independent solution includes multiple trials. By comparing the calculation results under different grid densities, the lower limit of the grid size that meets the accuracy requirements is found.

[0010] Preferably, on the processed two-dimensional axisymmetric model, first, according to the requirements of the heat flow field analysis, the grid size requirements of the fluid region along the axial and radial directions are determined, and the grid size requirements of the solid region along the axial and radial directions are determined, so that the degree of grid refinement is sufficient to capture the key features of the heat flow field. Then, the grid of the fluid region and the grid of the solid region are drawn.

[0011] The present invention also provides a system for establishing a casing finite element model for numerical calculation of a heat flow field, including: A two-dimensional modeling module: used to establish a two-dimensional axisymmetric model of the casing according to the structural characteristics of the preset casing, where the structural characteristics include the solid region and the fluid region of the casing; A model repair module: used to repair the geometric defects in the two-dimensional axisymmetric model, divide the fluid region in the two-dimensional axisymmetric model into a geometric shape including two sets of opposite sides, and obtain a preprocessed two-dimensional axisymmetric model; A grid drawing module: used to draw the grid of the fluid region and the grid of the solid region on the processed two-dimensional axisymmetric model to obtain a two-dimensional axisymmetric finite element model; A three-dimensional modeling module: used to rotate the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the casing to obtain the casing finite element model for numerical calculation of the heat flow field.

[0012] The present invention also provides an electronic device, including: One or more processors; A storage device on which one or more programs are stored; When the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the method for establishing a casing finite element model for numerical calculation of a heat flow field as described above in the present invention.

[0013] The present invention also provides a storage medium, characterized in that a computer program is stored thereon, and when the computer program is executed by a processor, the method for establishing a casing finite element model for numerical calculation of a heat flow field as described above in the present invention is implemented.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The method for establishing a sleeve finite element model for numerical calculation of a thermal flow field according to the present invention uses a sweeping method to draw an unstructured grid for numerical calculation of the sleeve thermal flow field, and then establishes a sleeve finite element model for numerical calculation of the thermal flow field. The method of the present invention not only improves the efficiency of grid meshing, but also effectively reduces the computational complexity of the sleeve thermal flow field analysis, providing strong technical support for the design, optimization and safe operation of power equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flowchart of the method for establishing a sleeve finite element model for numerical calculation of a thermal flow field according to an embodiment of the present invention; Figure 2 is a schematic diagram of a sleeve model according to an embodiment of the present invention; Figure 3 is a diagram of mesh meshing of a rotating surface according to an embodiment of the present invention; Figure 4 is a cross-sectional view of a swept mesh according to an embodiment of the present invention; Figure 5 is a diagram of a free tetrahedral mesh according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, not all of the embodiments.

[0017] The method for establishing a sleeve finite element model for numerical calculation of a thermal flow field according to the present invention applies a sweeping method to the unstructured mesh meshing process of numerical calculation of the sleeve thermal flow field, which can meet the requirement of providing a swept mesh conforming to the sleeve structural characteristics when carrying out numerical calculation of the sleeve thermal flow field, improve the mesh meshing efficiency, reduce the number of redundant meshes, capture the flow characteristics of the fluid, and improve the operation efficiency while ensuring the accuracy of the numerical calculation of the thermal flow field.

[0018] See Figure 1 , specifically, the method for establishing a sleeve finite element model for numerical calculation of a thermal flow field according to the present invention includes the following processes: Determine the structural characteristics of the sleeve. The structural characteristics of the sleeve include a solid region and a fluid region. Among them, the solid region includes a conductor, a flange and a core, and the fluid region includes air and oil. Then, construct a two-dimensional axisymmetric model of these regions (i.e., the solid region and the fluid region), and clarify the axis of symmetry of the sleeve and the rotating surface that can form a complete sleeve by rotating along this axis of symmetry in the two-dimensional axisymmetric model; Preprocess the established two-dimensional axisymmetric model. During preprocessing, identify and repair geometric defects in the two-dimensional axisymmetric model that are difficult to directly mesh. The geometric defects include sharp corners and slits. Then, segment and reorganize the fluid region, dividing the originally complex fluid region into more regular and easier-to-process structures, such as geometric shapes like rectangles and trapezoids that contain two sets of opposite sides. The two-dimensional axisymmetric model after preprocessing can simplify the subsequent mesh generation process; According to the requirements of the heat flow field analysis, clarify the mesh size requirements of the fluid region and the solid region along the axial and radial directions to ensure that the mesh refinement degree is sufficient to capture the key features of the heat flow field. On the rotating surface of the casing in the processed two-dimensional axisymmetric model, use the mapping method to draw the mesh of the fluid region and generate the mapped mesh. At this time, the rotating surface of the casing can also be called the mesh surface; at the same time, use the free triangular mesh generation method in the solid region to generate free triangular meshes and obtain a two-dimensional axisymmetric finite element model; through the above mesh generation, it can handle complex geometric shapes and maintain the flexibility and computational efficiency of the mesh; Rotate the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the casing to obtain the casing finite element model for numerical calculation of the heat flow field. Specifically, the process of rotating the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the casing includes: rotating the two-dimensional axisymmetric model in the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the casing to form a three-dimensional model of the casing; rotating the rotating surface (i.e., the mesh surface) of the casing in the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the casing to form a complete three-dimensional swept mesh. Among them, when rotating the rotating surface of the casing in the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the casing (i.e., drawing a three-dimensional swept mesh along the rotation path), based on the generated mapped mesh and free triangular meshes, determine the overall size and distribution of the casing swept mesh to ensure the continuity and quality of the mesh during the sweeping process.

[0019] In the above solution of the present invention, the establishment process of the two-dimensional axisymmetric model (also called the finite element analysis model of the heat flow field) is a conventional process in the art. This two-dimensional axisymmetric model is used to analyze the heat flow field distribution under the natural convection phenomenon generated when the fluid medium (such as air, oil) filled inside the casing is heated when the casing conductor is energized and generates heat. This two-dimensional axisymmetric model is a two-dimensional axisymmetric model containing detailed geometric information and material properties, and can accurately reflect the physical characteristics of each component of the casing (such as conductors, flanges, cores) and the surrounding fluid region.

[0020] In the above solution of the present invention, during preprocessing, the geometric shape division aims to simplify the mesh generation process while maintaining the ability to capture key features of the heat flow field, ensuring the quality of the mesh and the calculation accuracy. On the processed two-dimensional axisymmetric model, when drawing the mesh of the fluid region and the solid region, the mesh sizes of the fluid structure and the solid region are refined to the standard of mesh independent solution, that is, further refining the mesh will no longer significantly affect the calculation results, thereby optimizing the use of computing resources while ensuring the calculation accuracy. The determination process of the mesh independent solution includes multiple trial calculations. By comparing the calculation results under different mesh densities, the lower limit of the mesh size that meets the accuracy requirements is found. The size of the swept mesh also needs to be refined to the standard of mesh independent solution to ensure that the numerical simulation results of the entire casing heat flow field are both accurate and efficient.

[0021] Embodiment The refined electric field evaluation method for the transformer lead structure based on the sub-model in this embodiment includes the following steps.

[0022] Step 1): Establish a two-dimensional axisymmetric model of the casing, determine the solid regions including the conductor, flange, and core body in the casing structure, and the fluid regions including air and oil, and clarify the axis of symmetry and the rotation plane of the casing in the two-dimensional axisymmetric model.

[0023] Step 2): Preprocess the two-dimensional axisymmetric model of the casing, identify and repair geometric defects such as sharp corners and slits in the model that are difficult to directly mesh. Through the methods of segmentation and recombination, the originally complex fluid region is divided into structures with more regular shapes and easier to process.

[0024] Step 3): According to the requirements of heat flow field analysis, clarify the mesh size requirements of the fluid region and the solid region along the axial and radial directions. On the rotation plane of the casing, use the mapping method to draw the mesh of the fluid region. At the same time, in the solid region, use the free triangular mesh generation technology to construct a two-dimensional axisymmetric finite element model of the casing.

[0025] Step 4): Rotate the two-dimensional axisymmetric model around the axis of symmetry of the casing for one week to form a three-dimensional model of the casing; determine the overall size and distribution of the swept mesh of the casing, select the rotation plane of the casing as the source plane and the target plane of the swept mesh, and sweep the mesh of the rotation plane of the casing along the axis of symmetry for one week to form a complete three-dimensional swept mesh. Thus, a finite element model of the casing for numerical calculation of the heat flow field is obtained.

[0026] The mesh obtained by the above three-dimensional unstructured mesh drawing method based on the sweeping method is as Figures 2 - 4 shown, and the mesh drawn based on the free tetrahedron mesh method is as Figure 5As shown, the number of grids of the three-dimensional swept grid is 200,000, and the number of grids of the free tetrahedral grid drawn with the same size is 8,090,000. The number of grids of the swept grid is much smaller than that of the free tetrahedral grid. When calculating the thermal fluid field distribution of the casing using the finite volume method, the time taken for one iteration based on the free tetrahedral grid is 1289.3 s, and the time taken for one iteration based on the three-dimensional swept grid is 44.7 s.

[0027] As can be seen from the above solutions, the present invention not only improves the efficiency of grid meshing, but also effectively reduces the computational complexity of the thermal fluid field analysis of the casing, providing strong technical support for the design, optimization and safe operation of power equipment.

[0028] In addition, the embodiment of the present invention also provides a system for implementing the method for establishing a casing finite element model for numerical calculation of a thermal fluid field of the present invention. The system includes: Two-dimensional modeling module: used to establish a two-dimensional axisymmetric model of the casing according to the structural characteristics of the preset casing, where the structural characteristics include the solid region and the fluid region of the casing; Model repair module: used to repair geometric defects in the two-dimensional axisymmetric model to obtain a preprocessed two-dimensional axisymmetric model; Grid drawing module: used to draw grids for the fluid region and grids for the solid region on the processed two-dimensional axisymmetric model to obtain a two-dimensional axisymmetric finite element model; Three-dimensional modeling module: used to rotate the two-dimensional axisymmetric finite element model one week around the axis of symmetry of the casing, and then draw three-dimensional swept grids along the rotation path to obtain the casing finite element model for numerical calculation of the thermal fluid field.

[0029] The embodiment of the present invention also provides a corresponding electronic device and a computer-readable storage medium for implementing the solution provided by the embodiment of the present invention.

[0030] Among them, the device includes a memory and a processor. The memory is used to store instructions or codes, and the processor is used to execute the instructions or codes so that the device executes the method for establishing a casing finite element model for numerical calculation of a thermal fluid field according to any embodiment of the present application.

[0031] A computer program is stored on the storage medium. Among them, when the computer program is executed by the processor, it implements the method for establishing a casing finite element model for numerical calculation of a thermal fluid field according to any embodiment of the present application.

[0032] Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for establishing a finite element model of a casing for numerical calculation of thermal flow field, characterized in that: include: According to the preset structural features of the casing, a two-dimensional axisymmetric model of the casing is established, wherein the structural features include a solid region and a fluid region of the casing; Repairing geometric defects in the two-dimensional axisymmetric model, dividing the fluid region in the two-dimensional axisymmetric model into geometric shapes containing two sets of opposite edges, and obtaining a preprocessed two-dimensional axisymmetric model; On the processed two-dimensional axisymmetric model, draw the mesh of the fluid region and the mesh of the solid region to obtain a two-dimensional axisymmetric finite element model; The two-dimensional axisymmetric finite element model is rotated around the symmetry axis of the sleeve for one circle to obtain the sleeve finite element model used for numerical calculation of thermal flow field.

2. The method for establishing a finite element model of a casing for numerical calculation of a thermal flow field according to claim 1, characterized in that: The solid area of ​​the bushing includes the conductor, flange and core, and the fluid area of ​​the bushing includes air and oil.

3. The method for establishing a finite element model of a casing for numerical calculation of a thermal flow field according to claim 1, characterized in that: The geometric shapes including two sets of opposite sides include rectangles and trapezoids.

4. The method for establishing a finite element model of a casing for numerical calculation of a thermal flow field according to claim 1, characterized in that: Geometric imperfections include sharp corners and narrow gaps.

5. The method for establishing a finite element model of a casing for numerical calculation of a thermal flow field according to claim 1, characterized in that: On the rotating surface of the casing in the processed two-dimensional axisymmetric model, the mapping method is used to draw the mesh of the fluid area to generate a mapped mesh; the free triangle meshing method is used to draw the mesh of the solid area to generate a free triangle mesh.

6. The method for establishing a finite element model of a casing for numerical calculation of thermal flow field according to claim 1, characterized in that: On the processed two-dimensional axisymmetric model, when drawing the grid of the fluid area and the grid of the solid area, the grid size is refined to the standard of the grid-independent solution. The process of determining the grid-independent solution includes multiple trial calculations. By comparing the calculation results under different grid densities, the lower limit of the grid size that meets the accuracy requirements is found.

7. The method for establishing a finite element model of a casing for numerical calculation of a thermal flow field according to claim 1, characterized in that: On the processed two-dimensional axisymmetric model, first determine the mesh size requirements in the axial and radial directions of the fluid region and the mesh size requirements in the solid region according to the needs of the thermal flow field analysis, so that the mesh is refined enough to capture the key features of the thermal flow field, and then draw the mesh of the fluid region and the mesh of the solid region.

8. A casing finite element model building system for thermal flow field numerical calculation, characterized in that: include: Two-dimensional modeling module: used to establish a two-dimensional axisymmetric model of the casing according to the preset structural features of the casing, wherein the structural features include the solid area and the fluid area of ​​the casing; Model repair module: used to repair geometric defects in the two-dimensional axisymmetric model, divide the fluid area in the two-dimensional axisymmetric model into geometric shapes containing two sets of opposite edges, and obtain the pre-processed two-dimensional axisymmetric model; Mesh drawing module: used to draw the mesh of the fluid area and the mesh of the solid area on the processed two-dimensional axisymmetric model to obtain a two-dimensional axisymmetric finite element model; Three-dimensional modeling module: used for rotating the two-dimensional axisymmetric finite element model around the symmetry axis of the sleeve for one circle to obtain the sleeve finite element model used for numerical calculation of thermal flow field.

9. An electronic device, characterized in that: include: one or more processors; a storage device having one or more programs stored thereon; When the one or more programs are executed by the one or more processors, the one or more processors implement the method for establishing a finite element model of a sleeve for numerical calculation of a thermal flow field as described in any one of claims 1 to 7.

10. A storage medium, characterized in that: A computer program is stored thereon, wherein when the computer program is executed by a processor, the method for establishing a finite element model of a sleeve for numerical calculation of a thermal flow field as described in any one of claims 1 to 7 is implemented.

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