Structured grid method and system for dividing wire-wrapped triangular array rod bundle assemblies

Abstract

The application discloses a kind of structural grid methods and systems of dividing triangular arrangement rod bundle assembly with wire winding, it is related to nuclear reactor core thermal-hydraulic analysis and calculation field, by using structured hexahedral grid to divide the flow channel of triangular arrangement rod bundle with wire winding, grid quality is higher, and calculation efficiency is more optimal;When establishing the structured grid of the flow cross section of triangular arrangement rod bundle assembly with wire winding, we fully consider the geometric characteristics of wire winding, thereby improve the geometric reduction degree of grid model;According to the calculation requirement, the number and distribution of grid nodes can be flexibly adjusted, and the axial length is shortened accordingly, so as to not affect the calculation precision, reduce the number of grids, save the calculation resource, and ensure the calculation quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear reactor core thermal-hydraulic analysis calculation, and particularly relates to a structured grid method and system for dividing a wire-wrapped triangularly arranged rod bundle assembly. BACKGROUND

[0002] Currently, in the operation of nuclear reactors, fuel assemblies work in a harsh environment of high temperature, high pressure and strong radiation. In order to ensure the fixed position of fuel rods and enhance the heat transfer between the coolant and the fuel rods, a positioning device is usually used, in which the wire is wound around the single rod. The positioning wire not only fixes the position of the fuel rod and enhances the heat transfer between the coolant and the fuel rod, but also makes the flow field in the rod bundle exhibit complex asymmetric characteristics. Therefore, accurately determining the thermal-hydraulic characteristics of the wire-wrapped triangularly arranged rod bundle assembly is crucial for the design and safety evaluation of the nuclear reactor core.

[0003] Currently, CFD simulation has become a common method for calculating detailed flow fields in wire-wrapped triangularly arranged rod bundle assemblies. However, due to the presence of wire-wrapped components, the flow channel in the wire-wrapped triangularly arranged rod bundle assembly has a highly complex geometric structure with irregular channel shapes and obvious anisotropic characteristics. These complex structural features pose significant challenges to the wire-wrapped triangularly arranged rod bundle assembly. Grid division usually uses pre-processing software to automatically generate tetrahedral or polyhedral unstructured grids. Compared with structured grids, unstructured grids have lower fidelity in reproducing the geometric structure of the wire-wrapped triangularly arranged rod bundle, grid quality, and space utilization efficiency, and the number of grids is huge, which will consume more computing resources. Therefore, the grid division scheme for the wire-wrapped triangularly arranged rod bundle assembly needs to consider multiple factors to achieve efficient grid division. In recent years, some scholars have proposed a new method, i.e., in the process of dividing the structured grid of the wire-wrapped triangularly arranged rod bundle assembly, the geometric features of the wire can be first ignored, and the structured grid of the bare rod is first divided, then the grid elements where the wire is located are marked in the CFD software through the parameter equation of the wire. Finally, the marked grid elements can be deleted to obtain the structured grid of the fuel rod with the spiral positioning line. This method is simply referred to as "grid marking method" to better preserve the overall geometric features of the fuel rod.

[0004] However, since the wire-wrapped surface is relatively rough due to the wire-wrapped being obtained by deleting the grid, the flow resistance of the spiral positioning line can be overestimated, and errors can be caused in the CFD simulation results. Meanwhile, there is also a method of dividing by stretching the two-dimensional grid, but this method is only limited to the pressurized water reactor containing the wire-wrapped, and the rod bundle distribution is in the rectangular distribution, which can be used. In this case, the rod bundle spacing is large, and for triangularly distributed rod bundles, the wire-wrapped is close to the fuel rod. The stretched method inevitably causes the grid around the rod to overlap, so that the CFD calculation cannot be performed.

[0005] Therefore, in view of the above problems, how to provide a structured grid method and system for dividing a triangularly arranged rod bundle assembly with wire-wrapped is a problem that those skilled in the art need to solve. SUMMARY

[0006] Therefore, the present application provides a structured grid method and system for dividing a triangularly arranged rod bundle assembly with wire-wrapped to solve the problems in the prior art.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] On the one hand, a structured grid method for dividing a triangularly arranged rod bundle assembly with wire-wrapped is provided, comprising:

[0009] Step 1, establishing a three-dimensional geometric model of a flow channel of a triangularly arranged rod bundle assembly with wire-wrapped;

[0010] Step 2, dividing the geometric body into a plurality of unit segment assembly models by using the model established in step 1;

[0011] Step 3, performing structured hexahedral grid division on the near-rod region, and dividing the unit segment assembly model into a near-rod channel and a gap channel according to the geometric shapes of the fuel rod and the wire-wrapped;

[0012] Step 4, respectively matching the geometric features on the near-rod channel and the gap channel, and setting the number of nodes and the distribution mode to generate corresponding structured grids;

[0013] Step 5, dividing the boundary layer of the near-rod region, setting the distance of the nodes and the edge end points, and generating the boundary layer of the wire-wrapped and the near-rod region;

[0014] Step 6, after the grid division of each unit segment assembly model is completed, rotating the unit segment grid structure to splice into a structured grid of the flow channel of the triangularly arranged rod bundle assembly with wire-wrapped.

[0015] Optionally, in step 2, the angle of the winding angle of the unit segment assembly model is not greater than 30°.

[0016] Optionally, the method for matching the geometric features of the near-bar channel and generating a structured mesh in step 4 specifically includes:

[0017] Step 4-1: Use a three-dimensional plane to divide the interface between the near-rod channel region and the gap channel, and use this to construct auxiliary surfaces to help establish the surface association of the block, ensuring that the surface mesh and the volume mesh in the block are regularly distributed.

[0018] Step 4-2: Create a cuboid block in the non-wire-wound part of the near-rod region, set the number of nodes and distribution method according to the calculation accuracy requirements, and generate a structured mesh for the non-wire-wound part.

[0019] Step 4-3: In the inclined portion of the wire-winding region near the rod, the inclined portion and the vertical line are Y-shapedly divided to generate a structured mesh for the inclined portion of the wire-winding region.

[0020] Step 4-4: In the section where the wire connects to the fuel rod wall in the near-rod region, a triangular prism is formed by merging two opposite sides of the quadrangular prism surrounding the fuel rod wall. This triangular prism is then connected to the triangular prisms on either side of the corresponding wire. The number and distribution of nodes are set to generate a structured mesh for the section where the wire connects to the fuel rod wall.

[0021] Optionally, the method for matching the geometric features of the gap channels to generate a structured mesh in step 4 specifically includes:

[0022] The gap channels are divided into regular square prism blocks. The inner face of the regular square prism block matches the outer face of the near-bar channel. The two opposite sides of the inner face of the regular square prism block are merged to form a triangular prism. Y-shaped subdivision is performed to form a structured mesh for the gap channels.

[0023] Optionally, in step 3, the near-bar channel refers to the area around the wire bundle assembly adjacent to the fuel rod, and the gap channel refers to the gap between adjacent near-bar channel members.

[0024] Optionally, the Y-shaped partitioning, wherein the height of the triangular prism block is the width of the near-rod region, the length is the height of the geometric model, and the distribution method and the number of nodes are set in the same way as in step 4-2.

[0025] On the other hand, a structured mesh system for dividing a bundle of wire-wound triangularly arranged rods is provided, comprising the following modules:

[0026] The 3D geometry model building module is used to build a 3D geometry model of the flow channel of the wire-wound triangularly arranged rod bundle assembly.

[0027] The structured hexahedral mesh generation module is used to perform structured hexahedral mesh generation on the near-rod region and divide the unit segment component model into near-rod channels and gap channels according to the geometry of the fuel rod and the winding wire.

[0028] a structured hexahedron mesh generation module for matching the geometric features on the near-rod channel and the gap channel respectively, and setting the number and distribution of nodes to generate corresponding structured meshes;

[0029] a boundary layer division module for dividing the boundary layer of the near-rod region, setting the distance of nodes and edge end points and the growth ratio, and generating the boundary layer around the wire and the near-rod region;

[0030] a structured mesh splicing module for rotating the unit segment mesh structure to splice and form the structured mesh of the flow channel of the triangularly arranged rod bundle assembly with wire after the mesh division of each unit segment component model is completed.

[0031] Optionally, the structured hexahedron mesh generation module further comprises:

[0032] an auxiliary surface establishment module for dividing the interface between the near-rod channel region and the gap channel by using a three-dimensional plane, and constructing an auxiliary surface to assist in establishing the surface correlation of the block and ensuring the regular distribution of the surface mesh and the body mesh in the block;

[0033] a structured mesh generation module for the non-wire portion for establishing a cuboid block in the non-wire portion of the near-rod region, setting the number and distribution of nodes according to the calculation accuracy requirement, and generating the structured mesh of the non-wire portion;

[0034] a structured mesh generation module for the wire inclined portion for generating the structured mesh of the wire inclined portion by dividing the inclined portion into a triangular prism block with a vertical line;

[0035] a structured mesh generation module for the gap channel for dividing a right quadrangular prism block of the gap channel, matching the two opposite edges of the internal surface of the right quadrangular prism block with the external surface of the near-rod channel, merging the two opposite edges of the internal surface of the right quadrangular prism block to form a triangular prism, and performing Y-type sectioning to form the structured mesh of the gap channel.

[0036] According to the technical solution, compared with the prior art, the present application has the following beneficial effects:

[0037] 1. The present application uses structured hexahedron mesh to divide the flow channel of the triangularly arranged rod bundle with wire, which has higher mesh quality and better calculation efficiency;

[0038] 2. When establishing the structured mesh of the flow cross section of the triangularly arranged rod bundle assembly with wire, the geometric features of the wire are fully considered, thereby improving the geometric restoration degree of the mesh model;

[0039] 3、The application can flexibly adjust the number and distribution of grid nodes according to the calculation requirement, and the axial length is correspondingly shortened, so as to not affect the calculation precision, reduce the number of grids, save the calculation resources, and ensure the calculation quality;

[0040] 4、The application can be applied to the grid division of the triangular rod bundle distribution, and the wire winding and the near-rod channel are overlapped, and has a wider application range. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0042] Figure 1 The method flowchart of the embodiment 2 of the present application is shown in the figure;

[0043] Figure 2-1 The three-dimensional geometric schematic diagram of the 7-wire winding rod bundle assembly of the lead-bismuth fast reactor is shown in the figure;

[0044] Figure 2-2 The geometric structure schematic diagram of the intercepted section is shown in the figure;

[0045] Figure 2-3 The geometric auxiliary surface construction schematic diagram is shown in the figure;

[0046] Figure 3 The overall block diagram is shown in the figure;

[0047] Figure 4-1 The Y-type split schematic diagram is shown in the figure;

[0048] Figure 4-2 The wire winding inclined portion block diagram is shown in the figure;

[0049] Figure 4-3 The wire winding and fuel rod wall surface connection portion block diagram is shown in the figure;

[0050] Figure 4-4 The node distribution schematic diagram is shown in the figure;

[0051] Figure 5 The three-dimensional structure grid detail part schematic diagram with boundary layer is shown in the figure;

[0052] Figure 6 The three-dimensional structure grid schematic diagram of the triangular arrangement rod bundle assembly with wire winding is shown in the figure;

[0053] Figure 7 The three-dimensional structure grid top view of the triangular arrangement rod bundle assembly with wire winding is shown in the figure. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0055] Embodiment 1 of the present application discloses a method for dividing a structured grid of a wire-wound triangular arrangement rod bundle assembly, comprising the following steps:

[0056] Step 1, establishing a three-dimensional geometric model of a flow channel of a wire-wound triangular arrangement rod bundle assembly.

[0057] Step 2, segmenting the geometric body by using the model established in step 1 to divide the geometric model into N unit segment assembly models with a winding angle γ, the angle γ is less than 30° to ensure that the wire winding does not affect the grid quality, and the winding angle is preferably evenly divided by 30° to facilitate the subsequent geometric splicing, and the unit segment can also be non-uniformly divided.

[0058] Step 3, performing structured hexahedral grid division on the near-rod region, and dividing the unit segment assembly model into a near-rod channel and a gap channel according to the geometric shapes of the fuel rod and the wire winding.

[0059] The near-rod channel refers to a region around the wire-wound rod bundle assembly adjacent to the fuel rod, and the gap channel refers to the gap between adjacent near-rod channel pieces.

[0060] Step 4, respectively matching the geometric features on the near-rod channel and the gap channel, and setting the number of nodes and the distribution mode to generate corresponding structured grids.

[0061] Step 5, dividing the boundary layer of the near-rod region: setting the distance between the nodes and the edge end points, which is the thickness of the first layer boundary layer, and setting the growth ratio, generally 1.2-1.3 is appropriate, to generate the boundary layer of the wire winding and the near-rod region.

[0062] Step 6, after the grid division of each unit segment assembly model is completed, the unit segment grid structure is rotated and spliced to form a full segment structured grid.

[0063] In one specific embodiment, step 4 further comprises:

[0064] Step 4-1, according to the geometry of the fuel rod and the wire winding, the unit segment model is divided into a near-rod channel and a gap channel, the dividing surface of the near-rod channel region and the gap channel region is divided by using a three-dimensional plane, and an auxiliary surface is constructed by using the dividing surface, so as to assist in establishing the surface correlation of the block and ensure the regular distribution of the surface grid and the volume grid in the block.

[0065] Step 4-2, a cuboid block is established in the wire-free part of the near-rod region, the number of nodes and the distribution mode are set according to the calculation accuracy requirement, and the structured grid of the wire-free part is generated.

[0066] Step 4-3, in the inclined part of the wire winding region, the wire winding rotates downward and forms a certain angle with the central axis, the Y-type section of the three-prism block formed by the inclined part and the vertical line is performed, the height of the three-prism block is the width of the near-rod region, and the length is the height of the geometric model, so as to set the number of nodes and the distribution mode according to the calculation accuracy requirement, generate the structured grid of the wire winding inclined part, the distribution mode is set in the radial direction as in step 2-2, and the number of axial nodes can be referred to the radial node spacing, so that the axial node spacing is close to the radial node spacing, so as to ensure the aspect ratio of the grid.

[0067] Step 4-4, for the part where the wire winding is connected with the fuel rod wall surface, two opposite edges of the four-prism block surrounding the fuel rod wall surface are combined to form a three-prism block, which is connected with the corresponding three-prism blocks on both sides of the wire winding, and the number of nodes and the distribution mode are set, because the connection part is a three-prism block of the wire winding inclined part, the number of nodes and the distribution mode are consistent with those of the block in the wire winding inclined region, or the connection part is directly synthesized, the nodes corresponding to the edges of the synthesized connection part are automatically matched, so that the number of nodes and the distribution of the edges are consistent, and finally the structured grid of the part where the wire winding is connected with the fuel rod wall surface is generated.

[0068] In one specific embodiment, step 4 further comprises:

[0069] The four-prism block of the gap channel is divided, the inner surface of the four-prism block matches the outer surface of the near-rod channel, and the part where the gap channel is adjacent to the wire winding inclined part is connected in the same way as the fuel rod wall surface, that is, a three-prism block is divided and Y-sectioned to correspond to the three-prism block, and finally the overall block structure is formed.

[0070] In one aspect, the embodiment 2 of the present application discloses a method for dividing the structured grid of a triangularly arranged rod bundle assembly with wire winding, as shown in Figure 1 The method comprises the following steps:

[0071] Step 1, a three-dimensional geometric model of a triangularly arranged 7-rod bundle assembly with wire winding in a lead-bismuth fast reactor is established, and the geometric characteristics of the wire winding are built in the modeling, in this example, the length of the calculation region is 375 mm, and a wire winding pitch length is selected, as shown in Figure 2-1 The triangularly arranged rod bundle assembly with wire winding is divided into two small assembly models with a winding angle of 30°, as shown inFigure 2-2 as shown;

[0072] Step 2, the near-rod channel is structured hexahedral meshing, specifically:

[0073] Step 2-1, according to the geometry of the fuel rod and wire, the near-rod channel area is divided by three-dimensional plane, and an auxiliary surface is constructed, as shown in Figure 2-3 .

[0074] Step 2-2, the near-rod channel without wire is established, and the number of axial nodes is set to 30, the number of radial nodes is set to 5, and the distribution is uniform, and the structured grid of the wireless part is generated.

[0075] Step 2-3, in the inclined part of the wire area, the wire rotates down and forms a certain angle with the central axis, the inclined part is Y-type sectioned with the triangular prism block composed of the vertical line, the Y-type sectioning is to divide the triangular block into three quadrilateral blocks to improve the grid quality, the specific diagram is shown in Figure 4-1 , the height of the triangular prism block is the width of the near-rod area, and the length is the height of the geometric model, as shown in Figure 4-2 , the number of axial nodes is set to 30, the number of radial nodes is set to 5, and the distribution is uniform, and the structured grid of the wire inclined part is generated.

[0076] Step 3, for the part where the wire is connected with the fuel rod wall surface, two opposite edges of the quadrangular prism around the fuel rod wall surface are combined to form a triangular prism, which is connected with the corresponding triangular prism on both sides of the wire, as shown in Figure 4-3 , and the number of nodes and the distribution are set, the number of nodes and the distribution are the same as those of the wire inclined area, and the final node distribution is shown in Figure 4-4 , the structured grid of the part where the wire is connected with the fuel rod wall surface is generated.

[0077] Step 4, the right quadrangular prism block of the gap channel is divided, the inner surface of the quadrangular prism block matches the outer surface of the near-rod channel, and the place where the gap channel is adjacent to the wire inclined part is connected in the same way as the fuel rod wall surface, that is, the triangular prism is also divided and Y-sectioned, and finally the overall block structure is formed as shown in Figure 3 .

[0078] Step 5, the boundary layer of the near-rod area is divided, the distance between the nodes and the edge end points is set to 0.05mm, that is, the thickness of the boundary layer, and the growth ratio is set to 1.2, and the boundary layer of the wire and the near-rod area is generated.

[0079] Step 6, the generated three-dimensional structured grid is shown in Figure 6 , and the three-dimensional structured grid top view is shown in Figure 7As shown, after the mesh division of the two small segment component models with a helix angle of 30° is completed, the full segment structured mesh is formed by splicing every 60°.

[0080] In another aspect, a structured mesh system for dividing a wire-wrapped triangular arrangement rod bundle assembly is provided, comprising the following modules:

[0081] A three-dimensional geometric model establishing module is configured to establish a three-dimensional geometric model of a flow channel of a wire-wrapped triangular arrangement rod bundle assembly;

[0082] A structured hexahedral mesh division module is configured to perform structured hexahedral mesh division on a near-rod region, and divide a unit segment component model into a near-rod channel and a gap channel according to the geometric shapes of the fuel rod and the wire wrap;

[0083] A structured hexahedral mesh generation module is configured to match the geometric features on the near-rod channel and the gap channel respectively, and set the number and distribution of nodes to generate corresponding structured meshes;

[0084] A boundary layer division module is configured to divide the boundary layer of the near-rod region, set the distance and growth ratio of the nodes and edge end points, and generate the boundary layer of the wire wrap and the near-rod region;

[0085] A structured mesh splicing module is configured to rotate the unit segment mesh structure after the mesh division of each unit segment component model is completed, and splice to form a structured mesh of the flow channel of the wire-wrapped triangular arrangement rod bundle assembly.

[0086] In one specific embodiment, the structured hexahedral mesh generation module further comprises:

[0087] An auxiliary surface establishing module is configured to divide the interface between the near-rod channel region and the gap channel using a three-dimensional plane, and construct an auxiliary surface to assist in establishing the surface association of the block and ensure the regular distribution of the surface mesh and the block body mesh;

[0088] A structured mesh generation module for the wire-wrapped portion is configured to establish a cuboid block in the wire-wrapped portion of the near-rod region, set the number and distribution of nodes according to the calculation accuracy requirement, and generate a structured mesh for the wire-wrapped portion;

[0089] A structured mesh generation module for the wire-wrapped inclined portion is configured to generate a structured mesh for the wire-wrapped inclined portion by performing a three-prism block operation on the inclined portion and a vertical line;

[0090] A structured mesh generation module for the gap channel is configured to divide a right quadrangular prism block of the gap channel, match the two opposite edges of the internal surface of the right quadrangular prism block with the external surface of the near-rod channel, combine the two opposite edges to form a three-prism, perform Y-type subdivision, and form a structured mesh for the gap channel.

[0091] The various embodiments described in this specification are presented by way of example, and each embodiment is presented with the understanding that it will not limit the present application to that embodiment alone. Each embodiment is presented in its own right, and the various embodiments are not mutually exclusive, but can be combined with each other. The various embodiments disclosed herein can be described in the general context of method steps, which can be implemented in software, hardware, or a combination thereof. The various embodiments can be described in the general context of acts to be performed in order to cause a computer to do work. The acts and the pertinence of the various embodiments described herein will become apparent to those of ordinary skill in the art from the following detailed description.

[0092] The foregoing description of the disclosed embodiments enables a person skilled in the art to implement or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of dividing a structured grid for a rod bundle assembly with wire-wrapped triangular arrangement, characterized by, The application relates to a method for generating a structured grid of a triangularly arranged fuel rod bundle assembly with wire wraps, which comprises the following steps: step 1, establishing a three-dimensional geometric model of a flow channel of a triangularly arranged fuel rod bundle assembly with wire wraps; step 2, dividing the geometric body into a plurality of unit segment assembly models by using the model established in step 1; step 3, performing structured hexahedral mesh division on a near-rod region, and dividing the unit segment assembly model into a near-rod channel and a gap channel according to the geometric shapes of fuel rods and wire wraps; step 4, respectively matching the geometric features on the near-rod channel and the gap channel, and setting the number and distribution mode of nodes to generate corresponding structured grids; step 5, dividing a boundary layer of the near-rod region, setting the distance of nodes and edge end points and the growth ratio to generate the boundary layer of the wire wrap and the near-rod region; step 6, after the mesh division of each unit segment assembly model is completed, rotating the unit segment grid structure to splice into the structured grid of the triangularly arranged fuel rod bundle assembly with wire wraps; the method for matching the geometric features of the near-rod channel in step 4 to generate the structured grid specifically comprises the following steps: step 4-1, dividing the interface between the near-rod channel region and the gap channel by using a three-dimensional plane, and constructing an auxiliary surface to assist in establishing the surface correlation of blocks and ensuring the regular distribution of surface grids and block body grids; step 4-2, establishing a cuboid block in the wire wrap-free part of the near-rod region, setting the number and distribution mode of nodes according to the calculation accuracy requirement to generate the structured grid of the wire wrap-free part; step 4-3, in the inclined part of the wire wrap region of the near-rod region, the structured grid of the wire wrap inclined part is generated by performing Y-type sectioning on the three-prism block formed by the inclined part and a vertical line; and step 4-4, in the junction part of the wire wrap and the fuel rod wall surface of the near-rod region, the structured grid of the junction part of the wire wrap and the fuel rod wall surface is generated by merging two opposite edges of the four-prism block surrounding the fuel rod wall surface to form a three-prism block, and the three-prism block is matched with the three-prism blocks on both sides of the wire wrap, and the number and distribution mode of nodes are set. In step 2, the angle of the winding angle of the unit segment assembly model is not greater than 30 DEG. In step 4, the method for matching the geometric features of the gap channel to generate the structured grid specifically comprises the following steps: a right quadrangular prism block of the gap channel is divided, the internal surface of the right quadrangular prism block is matched with the external surface of the near-rod channel, two opposite edges of the internal surface of the right quadrangular prism block are merged to form a three-prism block, Y-type sectioning is performed, and the structured grid of the gap channel is formed. In step 3, the near-rod channel refers to the region around the wire wrap fuel rod assembly adjacent to the fuel rod, and the gap channel refers to the gap between adjacent near-rod channels. The Y-type sectioning, wherein the height of the three-prism block is the width of the near-rod region, the length is the height of the geometric model, and the setting of the distribution mode and the number of nodes is the same as that in step 4-2. The application further discloses a method for generating a structured grid of a triangularly arranged fuel rod bundle assembly with wire wraps, which comprises the following modules: a three-dimensional geometric model establishing module for establishing a three-dimensional geometric model of a flow channel of a triangularly arranged fuel rod bundle assembly with wire wraps; a structured hexahedral mesh division module for performing structured hexahedral mesh division on a near-rod region, and dividing a unit segment assembly model into a near-rod channel and a gap channel according to the geometric shapes of fuel rods and wire wraps; and a structured grid generating module for respectively matching the geometric features on the near-rod channel and the gap channel, and setting the number and distribution mode of nodes to generate corresponding structured grids. ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein the structured grid of a rod bundle assembly with wire- wrapped triangular arrangement is divided into a plurality of cells, and each cell is assigned a cell type, and the cell type is determined by the number of rods in the cell and the number of wires in the cell. ​ 3. The method of claim 1, wherein the structured grid of a rod bundle assembly with wire- wrapped triangular arrangement is divided into a plurality of cells, and each cell is assigned a cell type, and the cell type is determined by the number of rods in the cell and the number of wires in the cell. ​ ​ 4. The method of claim 1, wherein the structured grid of a rod bundle assembly with wire- wrapped triangular arrangement is divided into a plurality of cells, and each cell is assigned a cell type, and the cell type is determined by the number of rods in the cell and the number of wires in the cell. ​ 5. The method of claim 2, wherein the structured grid of a rod bundle assembly with wire- wrapped divisions is characterized by, ​ 6. A structured grid system for dividing a band-wound triangular array rod bundle assembly, characterized by, ​ ​ ​ The structured hexahedral mesh generation module is used for matching the geometric features on the near-rod channel and the gap channel respectively, and setting the number and distribution of nodes to generate corresponding structured meshes; The boundary layer division module is used for dividing the boundary layer of the near-rod region, setting the distance of nodes and edge end points and the growth ratio, and generating the boundary layer around the wire and the near-rod region; The structured mesh splicing module is used for rotating the unit segment mesh structure to splice and form the structured mesh of the triangular arrangement rod bundle assembly flow channel with the wire after the mesh division of each unit segment component model is completed; The structured hexahedral mesh generation module further comprises: The auxiliary surface establishment module is used for dividing the boundary surface of the near-rod channel region and the gap channel by using a three-dimensional plane, and constructing an auxiliary surface to assist in establishing the surface correlation of the block and ensuring the regular distribution of the surface mesh and the body mesh in the block; The structured mesh generation module of the non-wire portion is used for establishing a cuboid block in the non-wire portion of the near-rod region, setting the number and distribution of nodes according to the calculation accuracy requirement, and generating the structured mesh of the non-wire portion; The structured mesh generation module of the wire inclined portion is used for generating the structured mesh of the wire inclined portion by dividing the inclined portion and the three-prism block formed by the vertical line in the inclined portion of the wire region; The structured mesh generation module of the gap channel is used for dividing the right quadrangular prism block of the gap channel, matching the two opposite edges of the internal surface of the right quadrangular prism block with the external surface of the near-rod channel, merging the two opposite edges to form a three-prism, performing Y-type sectioning, and forming the structured mesh of the gap channel.

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