CN108197360B - Automatic division system and method for steam turbine rotor grids - Google Patents

Automatic division system and method for steam turbine rotor grids Download PDF

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CN108197360B
CN108197360B CN201711405395.3A CN201711405395A CN108197360B CN 108197360 B CN108197360 B CN 108197360B CN 201711405395 A CN201711405395 A CN 201711405395A CN 108197360 B CN108197360 B CN 108197360B
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seed
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CN108197360A (en
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宋为平
初世明
郑宏伟
李光磊
赵建立
李岩
刘海旭
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Harbin Turbine Co Ltd
Hadian Power Equipment National Engineering Research Center Co Ltd
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Abstract

An automatic meshing system and method for a steam turbine rotor relates to a meshing system and method. The method aims to solve the problem that the grid division for ensuring the finite element simulation precision can not be carried out aiming at the steam turbine rotors with different sizes at present. The invention comprises a rotor model characteristic acquisition module for collecting characteristic information of an imported rotor model; the characteristic value analysis module is used for numbering each characteristic edge and each characteristic node and classifying the characteristic edges according to characteristic coordinates; the characteristic edge seed distribution module is used for inputting the preposed characteristic ratio and the postposed characteristic ratio into a logic library to search for the most suitable seed distribution mode, controlling the curvature of the seeds and taking charge of characteristic edge seed distribution; to pre-characteristic ratio R1And a post-characteristic ratio R2A logic library for performing logic judgment; a mesh division module for dividing and dividing hexahedron meshes for the characteristic model and limiting geometric eccentricity factors; and the grid information storage module stores the node number applied by the seed marking unit into the unit database. The invention is suitable for automatic division of the rotor grids of the steam turbine.

Description

Automatic division system and method for steam turbine rotor grids
Technical Field
The invention relates to a meshing system and a meshing method, in particular to an automatic meshing system and a meshing method for a steam turbine rotor.
Background
The finite element method has become an important means for calculating the strength of the steam turbine rotor in the steam turbine industry, the grid division is more and more emphasized as a limiting condition of finite element calculation precision, and a proper grid must be divided for improving the calculation precision of the rotor strength and ensuring the operation safety of the steam turbine. At present, the meshing of the steam turbine rotor in China is still in a manual meshing stage, and the automatic meshing system of the rotor is still in a blank stage, mainly because: the structure of the steam turbine rotor is complex and the form is not uniform, the functional structure is more, and the uniform grid division rule can not be established; the difference between the large size and the small size of the steam turbine rotor is more than one order of magnitude, and a uniform seed distribution rule cannot be formed; the steam turbine blade root groove and the balance drum root are small-sized concentrated places and are also positions where stress concentration often occurs, namely strength limiting positions, grid encryption work needs to be carried out on the positions to ensure accuracy, but the grid quantity is too large, the occupied computing resources are more, and the contradiction between the computing accuracy and the computing resources is caused; due to different grid division ideas of calculation and analysis personnel, the method lacks relevant industrial standards, has different accuracy and calculation efficiency, and is difficult to realize the improvement of the working efficiency and the large-scale application.
Disclosure of Invention
The invention aims to solve the problem that the grid division for ensuring the finite element simulation precision can not be carried out on the steam turbine rotors with different sizes under the condition of less calculation amount at present. Further provides an automatic division system and method for the rotor grids of the steam turbine.
Automatic grid partitioning system for a steam turbine rotor, comprising:
the rotor model characteristic acquisition module is used for collecting characteristic information of the imported rotor model, wherein the characteristic information comprises characteristic information such as coordinates of each endpoint of the rotor model, length of each characteristic edge, angle and the like;
the eigenvalue analysis module is used for numbering each characteristic edge and each characteristic node, classifying the characteristic edges according to characteristic coordinates, simultaneously acquiring length information of each characteristic edge, and respectively enabling the length n of each characteristic edge to be equal to the length n of the preposed characteristic edge2Length n of the postpositional characteristic edge3Making ratios to respectively obtain leading feature ratios
Figure BDA0001520194820000011
Ratio of postpositional features
Figure BDA0001520194820000012
A feature edge seeding module for seeding a leading feature ratio R1And a post-characteristic ratio R2Inputting the data into a logic library to search for the most suitable seed distribution mode, performing curvature control on the seeds, and limiting the maximum deviation factor by performing curvature control through the maximum deviation factor and the minimum size factor; completing characteristic edge seed distribution until the seeds of the cloth meet all the requirements;
logical library to pre-eigen ratio R1And a post-characteristic ratio R2Carrying out logic judgment; the logic of (1) is as follows:
to pre-characteristic ratio R1The judgment is carried out, and the judgment is carried out,
if R is1Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000021
Minimum size of
Figure BDA0001520194820000022
If 3. ltoreq.R1Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000023
Minimum size of
Figure BDA0001520194820000024
If 1. ltoreq.R1Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000025
Minimum size of
Figure BDA0001520194820000026
If R is1< 1, no offset of seed, grid size set to
Figure BDA0001520194820000027
To the postposition characteristic ratio R2The judgment is carried out, and the judgment is carried out,
if R is2Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000028
Minimum size of
Figure BDA0001520194820000029
If 3. ltoreq.R2Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000210
Minimum size of
Figure BDA00015201948200000211
If 1. ltoreq.R2Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000212
Minimum size of
Figure BDA00015201948200000213
If R is2< 1, no offset of seed, grid size set to
Figure BDA00015201948200000214
The grid division module divides and divides the hexahedral grid for the feature model in a sweeping mode according to the positions of the seeds arranged on the feature edges, and limits the geometric eccentricity factor; and discretizing the rotor solid model into a finite number of units based on mesh division;
and the grid information storage module stores the coordinates of all nodes into a node database according to the sequence of the node numbers of the divided seeds, stores the node numbers applied by the units into a unit database according to the sequence of the unit numbers of the divided units, and integrates the node database and the unit database to form an inp file which can be directly read by the general finite element software.
The automatic division method of the rotor grid of the steam turbine comprises the following steps:
step 1, establishing a rotor model by applying modeling software;
step 2, feature classification and feature value analysis:
step 2.1, collecting characteristic information of the imported rotor model, wherein the characteristic information comprises characteristic information of coordinates of each endpoint of the rotor model, length of each characteristic edge, angles and the like;
step 2.2, numbering each characteristic edge and characteristic node, wherein the characteristic edge refers to edge information of a rotor model, classifying the characteristic edges according to characteristic coordinates, if a plurality of characteristic edges share one common node, classifying the characteristic edges into the same class, distributing a front characteristic and a rear characteristic for each characteristic edge, one characteristic edge has two characteristic nodes, defining the characteristic edge as a front node and a rear node according to the number size, edges sharing the front node except the characteristic edge are called front characteristics, and edges sharing the rear node except the characteristic edge are called rear characteristics; acquiring length information of each characteristic edge, and respectively comparing the length n of each characteristic edge with the length n of the preposed characteristic edge2Length n of the postpositional characteristic edge3Making ratios to respectively obtain leading feature ratios
Figure BDA0001520194820000031
Ratio of postpositional features
Figure BDA0001520194820000032
Step 2.3, leading the characteristic ratio R1And a post-characteristic ratio R2Inputting the seeds into a logic library to search for the most suitable seed arrangement mode, namely, preliminarily arranging the seeds according to the requirements of the logic library; the logic of the logic library is as follows:
to pre-characteristic ratio R1The judgment is carried out, and the judgment is carried out,
if R is1Not less than 5, the seed is shifted to the direction of the common node, the networkThe maximum size of the grid is
Figure BDA0001520194820000033
Minimum size of
Figure BDA0001520194820000034
If 3. ltoreq.R1Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000035
Minimum size of
Figure BDA0001520194820000036
If 1. ltoreq.R1Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000037
Minimum size of
Figure BDA0001520194820000038
If R is1< 1, no offset of seed, grid size set to
Figure BDA0001520194820000039
To the postposition characteristic ratio R2The judgment is carried out, and the judgment is carried out,
if R is2Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000310
Minimum size of
Figure BDA00015201948200000311
If 3. ltoreq.R2Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000312
Minimum size of
Figure BDA00015201948200000313
If 1. ltoreq.R2Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000314
Minimum size of
Figure BDA00015201948200000315
If R is2< 1, no offset of seed, grid size set to
Figure BDA00015201948200000316
Carrying out curvature control on the seeds, and carrying out curvature control through a maximum deviation factor and a minimum size factor to limit the maximum deviation factor and the minimum size factor;
completing characteristic edge seed distribution until the seeds of the cloth meet all the requirements;
step 3, dividing the characteristic model into grids:
dividing and dividing hexahedral meshes for the characteristic model in a sweeping mode according to the positions of seeds arranged on the characteristic edge, and limiting geometric eccentricity factors;
if the meshing is failed, returning to the step 2 to perform feature classification and feature value analysis again, adjusting the seed arrangement sequence until the meshing is completed and no error unit exists, if the meshing cannot be completed for ten times, rechecking the feature model, and reestablishing and importing the rotor model;
discretizing the rotor solid model into a finite number of cells based on meshing;
and 4, storing the coordinates of all nodes into a node database according to the sequence of the node numbers of the divided seeds, storing the node numbers applied by the units into a unit database according to the sequence of the unit numbers of the divided units, and integrating the node database and the unit database to form a file which can be directly read by the general finite element software.
Further, the maximum deviation factor of the limit described in step 2 is 0.1.
Further, the minimum size factor described in step 2 is set to 0.1.
Further, the constrained geometric eccentricity factor described in step 3 is less than 0.2.
The invention has the following effects:
aiming at the steam turbine rotors of different types, the invention automatically identifies the characteristic information of the input steam turbine rotor model, screens and classifies the characteristic information, determines the action and the relation of each characteristic edge in a fuzzy identification mode, selects an optimal seed distribution mode in a seed distribution type library, and disperses the rotor into hexahedron units with reasonable shapes, thereby realizing the automatic grid division function of the steam turbine rotor, simultaneously realizing the automatic grid division function of the steam turbine rotors of different types, almost realizing the grid division aiming at more than 90 percent of the steam turbine rotor models, avoiding the overlarge number of grids, occupying more computing resources and having good computing accuracy aiming at the steam turbine rotors of different sizes. As long as the established model is reasonable, the invention divides the meshes of the turbine rotor, the output result can ensure the precision of the finite element simulation result, can provide technical support for the finite element calculation of the turbine strength, and meets the requirement of the rotor strength design in the turbine industry.
Meanwhile, a large number of interfaces are reserved in the system, secondary development is facilitated, a continuous entity is dispersed into a limited number of units and nodes by the system, and technical support can be provided for the strength calculation of the steam turbine rotor by using a limited unit method.
Drawings
FIG. 1 is a general diagram of the meshing effect of the system of the present invention;
FIG. 2 is a detailed view of the effect of the system of the present invention on meshing of intensity key points;
FIG. 3 is a flow chart of logic determination;
FIG. 4 is a diagram illustrating the deviation between the grid edge and the actual model edge.
Detailed Description
The invention establishes a set of automatic meshing system of the steam turbine rotor, carries out automatic meshing work on the rotor model led into the system, and reserves a large number of secondary development interfaces, thereby achieving the purpose of providing technical preparation work for strength and dynamics analysis of the steam turbine rotor by using a finite element method and providing an engineering basis for safety accounting of the steam turbine rotor.
The first embodiment is as follows:
automatic grid partitioning system for a steam turbine rotor, comprising:
the rotor model characteristic acquisition module is used for automatically collecting characteristic information of the imported rotor model, wherein the characteristic information comprises characteristic information such as coordinates of each endpoint of the rotor model, length of each characteristic edge, angle and the like;
the eigenvalue analysis module is used for numbering each characteristic edge and each characteristic node, classifying the characteristic edges according to characteristic coordinates, simultaneously acquiring length information of each characteristic edge, and respectively enabling the length n of each characteristic edge to be equal to the length n of the preposed characteristic edge2Length n of the postpositional characteristic edge3Making ratios to respectively obtain leading feature ratios
Figure BDA0001520194820000051
Ratio of postpositional features
Figure BDA0001520194820000052
A feature edge seeding module for seeding a leading feature ratio R1And a post-characteristic ratio R2Inputting the data into a logic library to search for the most suitable seed distribution mode, performing curvature control on the seeds, and limiting the maximum deviation factor by performing curvature control through the maximum deviation factor and the minimum size factor; completing characteristic edge seed distribution until the seeds of the cloth meet all the requirements;
logical library to pre-eigen ratio R1And a post-characteristic ratio R2Carrying out logic judgment; the logic of (1) is as follows:
to pre-characteristic ratio R1The judgment is carried out, and the judgment is carried out,
if R is1Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000053
Minimum size of
Figure BDA0001520194820000054
If 3. ltoreq.R1Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000055
Minimum size of
Figure BDA0001520194820000056
If 1. ltoreq.R1Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000057
Minimum size of
Figure BDA0001520194820000058
If R is1< 1, no offset of seed, grid size set to
Figure BDA0001520194820000059
To the postposition characteristic ratio R2The judgment is carried out, and the judgment is carried out,
if R is2Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000510
Minimum size of
Figure BDA00015201948200000511
If 3. ltoreq.R2Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000512
Minimum size of
Figure BDA00015201948200000513
If 1. ltoreq.R2Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000514
Minimum size of
Figure BDA00015201948200000515
If R is2< 1, no offset of seed, grid size set to
Figure BDA00015201948200000516
The grid division module divides and divides the hexahedral grid for the feature model in a sweeping mode according to the positions of the seeds arranged on the feature edges, and limits the geometric eccentricity factor; and discretizing the rotor solid model into a finite number of units based on mesh division;
and the grid information storage module stores the coordinates of all nodes into a node database according to the sequence of the node numbers of the divided seeds, stores the node numbers applied by the units into a unit database according to the sequence of the unit numbers of the divided units, and automatically integrates the node database and the unit database to form an inp file which can be directly read by the general finite element software.
Aiming at the steam turbine rotors of different types, the invention automatically identifies the characteristic information of the input steam turbine rotor model, screens and classifies the characteristic information, determines the action and the relation of each characteristic edge in a fuzzy identification mode, selects an optimal seed distribution mode in a seed distribution type library, and disperses the rotor into hexahedron units with reasonable shapes, thereby realizing the automatic mesh division function of the steam turbine rotors, simultaneously realizing the automatic mesh division function of the steam turbine rotors of different types, and almost realizing the mesh division aiming at more than 90 percent of the steam turbine rotor models. As long as the established model is reasonable, the output result can ensure the precision of the finite element simulation result and the strength of the key point by dividing the meshes of the turbine rotor through the method. The general diagram of the grid division effect of the system of the invention is shown in figure 1; the detailed graph of the meshing effect of the system on the intensity key points is shown in figure 2.
Meanwhile, a large number of interfaces are reserved in the system, secondary development is facilitated, a continuous entity is dispersed into a limited unit and a node by the system, technical support can be provided for the steam turbine rotor to perform strength calculation by using a limited unit method, and the requirement of rotor strength design in the steam turbine industry is met.
The second embodiment is as follows:
the automatic division method of the rotor grid of the steam turbine comprises the following steps:
step 1, building a rotor model by applying modeling software such as UG (Unigraphics) and the like;
the method can establish rotor models with different properties according to the rotor form, can establish two-dimensional axisymmetric models for T-shaped blade roots and double-T-shaped blade roots, and can establish three-dimensional circularly symmetric models for palm tree blade roots; storing the established rotor model into an stp format, and introducing the stp format into an automatic grid division system of the steam turbine rotor;
step 2, feature classification and feature value analysis:
step 2.1, automatically collecting characteristic information of the imported rotor model, wherein the characteristic information comprises characteristic information of coordinates of each endpoint of the rotor model, length of each characteristic edge, angles and the like;
step 2.2, numbering each characteristic edge and characteristic node, wherein the characteristic edge refers to edge information (including length, coordinate and angle information) of the rotor model, classifying the characteristic edges according to the characteristic coordinates, if a plurality of characteristic edges share a common node, classifying the characteristic edges into the same class, allocating a front characteristic and a rear characteristic to each characteristic edge, one characteristic edge has two characteristic nodes, the characteristic edge is defined as a front node and a rear node according to the number size, edges sharing the front node except the characteristic edge are called front characteristics, and edges sharing the rear node except the characteristic edge are called the rear characteristicThe edges of the put nodes are called post-characteristics; acquiring length information of each characteristic edge, and respectively comparing the length n of each characteristic edge with the length n of the preposed characteristic edge2Length n of the postpositional characteristic edge3Making ratios to respectively obtain leading feature ratios
Figure BDA0001520194820000071
Ratio of postpositional features
Figure BDA0001520194820000072
Actually, a public node can have at most three edges, and for a preposed node, there are a characteristic edge and two preposed characteristic edges, and at this time, for each preposed characteristic edge, a preposed characteristic ratio needs to be calculated, and a seed distribution mode is searched; the post node and the post characteristic edge are processed in the same way;
step 2.3, leading the characteristic ratio R1And a post-characteristic ratio R2Inputting the seeds into a logic library to search for the most suitable seed arrangement mode, namely, preliminarily arranging the seeds according to the requirements of the logic library; as shown in FIG. 3, the logic of the logic library is as follows:
to pre-characteristic ratio R1The judgment is carried out, and the judgment is carried out,
if R is1Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000073
Minimum size of
Figure BDA0001520194820000074
If 3. ltoreq.R1Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000075
Minimum size of
Figure BDA0001520194820000076
If 1. ltoreq.R1Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA0001520194820000077
Minimum size of
Figure BDA0001520194820000078
If R is1< 1, no offset of seed, grid size set to
Figure BDA0001520194820000079
To the postposition characteristic ratio R2The judgment is carried out, and the judgment is carried out,
if R is2Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000710
Minimum size of
Figure BDA00015201948200000711
If 3. ltoreq.R2Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000712
Minimum size of
Figure BDA00015201948200000713
If 1. ltoreq.R2Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure BDA00015201948200000714
Minimum size of
Figure BDA00015201948200000715
If R is2< 1, no offset of seed, grid size set to
Figure BDA00015201948200000716
The seed is a finite element term and refers to virtual nodes which are arranged on the characteristic edge and are established for dividing grids;
carrying out curvature control on the seeds, wherein the curvature control is a finite element term, and carrying out curvature control through a maximum deviation factor and a minimum size factor to limit the maximum deviation factor and the minimum size factor (minimum characteristic resolution); the deviation degree of the grid edge from the actual model edge, as shown in fig. 4, where h is the chord deviation, L is the chord length, and h/L is the deviation factor;
completing characteristic edge seed distribution until the seeds of the cloth meet all the requirements;
step 3, dividing the characteristic model into grids:
dividing and dividing hexahedral meshes for the characteristic model in a sweeping mode according to the positions of seeds arranged on the characteristic edge, and limiting geometric eccentricity factors;
sweeping is a mechanical term, which means that firstly, a quadrilateral surface grid is generated on the section of the rotor, and the surface grid is rotated along the circumferential direction of the rotor to form a hexahedral grid; the geometric eccentricity factor is a finite element term and represents the deviation condition of the divided unit edge and the model edge;
if the gridding division fails, analyzing the failure reason, returning to the step 2 to perform feature classification and feature value analysis again, adjusting the seed arrangement sequence until the gridding division is completed and no error unit exists, if the gridding division work can not be completed for ten times, prompting a dialog box of 'please check the rotor model again', re-checking the feature model, and re-establishing and importing the rotor model;
discretizing the rotor solid model into a finite number of cells based on meshing;
and 4, storing the coordinates of all nodes into a node database according to the sequence of the node numbers of the divided seeds, storing the node numbers applied by the units into a unit database according to the sequence of the unit numbers of the divided units, and automatically integrating the node database and the unit database to form an inp file which can be directly read by the general finite element software.
The third concrete implementation mode:
the maximum deviation factor of the limit described in step 2 of the present embodiment is 0.1.
Other steps and parameters are the same as in the second embodiment.
The fourth concrete implementation mode:
in step 2 of this embodiment, the occurrence of sharp cells due to the division of unnecessary features into grids is prevented, and the minimum size factor is set to 0.1.
Other steps and parameters are the same as in the second or third embodiment.
The fifth concrete implementation mode:
the restricted geometric eccentricity factor described in step 3 of this embodiment is less than 0.2.
The other steps and parameters are the same as in one of the second to fourth embodiments.

Claims (5)

1. Automatic system of dividing of steam turbine rotor net which characterized in that includes:
the rotor model characteristic acquisition module is used for collecting characteristic information of the imported rotor model, and the characteristic information comprises the coordinates of each end point of the rotor model, the length of each characteristic edge and angle characteristic information;
the eigenvalue analysis module is used for numbering each characteristic edge and each characteristic node, classifying the characteristic edges according to characteristic coordinates, simultaneously acquiring length information of each characteristic edge, and respectively enabling the length n of each characteristic edge to be equal to the length n of the preposed characteristic edge2Length n of the postpositional characteristic edge3Making ratios to respectively obtain leading feature ratios
Figure FDA0002889791440000011
Ratio of postpositional features
Figure FDA0002889791440000012
A feature edge seeding module for seeding a leading feature ratio R1And a post-characteristic ratio R2Inputting the data into a logic library to search for the most suitable seed arrangement mode, performing curvature control on the seeds, and performing curvature control through the maximum deviation factor and the minimum size factor to limit the mostA large deviation factor; completing characteristic edge seed distribution until the seeds of the cloth meet all the requirements;
logical library to pre-eigen ratio R1And a post-characteristic ratio R2The logic for making the logic determination is as follows:
to pre-characteristic ratio R1The judgment is carried out, and the judgment is carried out,
if R is1Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA0002889791440000013
Minimum size of
Figure FDA0002889791440000014
If 3. ltoreq.R1Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA0002889791440000015
Minimum size of
Figure FDA0002889791440000016
If 1. ltoreq.R1Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA0002889791440000017
Minimum size of
Figure FDA0002889791440000018
If R is1< 1, no offset of seed, grid size set to
Figure FDA0002889791440000019
To the postposition characteristic ratio R2The judgment is carried out, and the judgment is carried out,
if R is2Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA00028897914400000110
Minimum size of
Figure FDA00028897914400000111
If 3. ltoreq.R2Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA00028897914400000112
Minimum size of
Figure FDA00028897914400000113
If 1. ltoreq.R2Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA00028897914400000114
Minimum size of
Figure FDA00028897914400000115
If R is2< 1, no offset of seed, grid size set to
Figure FDA00028897914400000116
The grid division module divides a hexahedral grid for the feature model in a sweeping mode according to the positions of the seeds arranged on the feature edges, and limits geometric eccentricity factors; and discretizing the rotor solid model into a finite number of units based on mesh division;
and the grid information storage module stores the coordinates of all nodes into a node database according to the sequence of the node numbers of the divided seeds, stores the node numbers applied by the units into a unit database according to the sequence of the unit numbers of the divided units, and integrates the node database and the unit database to form an inp file which can be directly read by the general finite element software.
2. The automatic grid dividing method for the steam turbine rotor is characterized by comprising the following steps of:
step 1, establishing a rotor model by applying modeling software;
step 2, feature classification and feature value analysis:
step 2.1, collecting characteristic information of the imported rotor model, wherein the characteristic information comprises the characteristic information of each endpoint coordinate, each characteristic edge length and angle of the rotor model;
step 2.2, numbering each characteristic edge and characteristic node, wherein the characteristic edge refers to edge information of a rotor model, classifying the characteristic edges according to characteristic coordinates, if a plurality of characteristic edges share one common node, classifying the characteristic edges into the same class, distributing a front characteristic and a rear characteristic for each characteristic edge, one characteristic edge has two characteristic nodes, defining the characteristic edge as a front node and a rear node according to the number size, edges sharing the front node except the characteristic edge are called front characteristics, and edges sharing the rear node except the characteristic edge are called rear characteristics; acquiring length information of each characteristic edge, and respectively comparing the length n of each characteristic edge with the length n of the preposed characteristic edge2Length n of the postpositional characteristic edge3Making ratios to respectively obtain leading feature ratios
Figure FDA0002889791440000021
Ratio of postpositional features
Figure FDA0002889791440000022
Step 2.3, leading the characteristic ratio R1And a post-characteristic ratio R2Inputting the seeds into a logic library to search for the most suitable seed arrangement mode, namely, preliminarily arranging the seeds according to the requirements of the logic library; the logic of the logic library is as follows:
to pre-characteristic ratio R1The judgment is carried out, and the judgment is carried out,
if R is1Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA0002889791440000023
Minimum size of
Figure FDA0002889791440000024
If 3. ltoreq.R1Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA0002889791440000025
Minimum size of
Figure FDA0002889791440000026
If 1. ltoreq.R1Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA0002889791440000027
Minimum size of
Figure FDA0002889791440000028
If R is1< 1, no offset of seed, grid size set to
Figure FDA0002889791440000029
To the postposition characteristic ratio R2The judgment is carried out, and the judgment is carried out,
if R is2Not less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA00028897914400000210
Minimum size of
Figure FDA00028897914400000211
If 3. ltoreq.R2Less than 5, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA00028897914400000212
Minimum size of
Figure FDA00028897914400000213
If 1. ltoreq.R2Less than 3, the seed is shifted to the direction of the common node, and the maximum size of the grid is
Figure FDA0002889791440000031
Minimum size of
Figure FDA0002889791440000032
If R is2< 1, no offset of seed, grid size set to
Figure FDA0002889791440000033
Carrying out curvature control on the seeds, and carrying out curvature control through a maximum deviation factor and a minimum size factor to limit the maximum deviation factor and the minimum size factor;
completing characteristic edge seed distribution until the seeds of the cloth meet all the requirements;
step 3, dividing the characteristic model into grids:
according to the positions of seeds arranged on the characteristic edge, dividing a hexahedral mesh for the characteristic model in a sweeping mode, and limiting a geometric eccentricity factor;
if the meshing is failed, returning to the step 2 to perform feature classification and feature value analysis again, adjusting the seed arrangement sequence until the meshing is completed and no error unit exists, if the meshing cannot be completed for ten times, rechecking the feature model, and reestablishing and importing the rotor model;
discretizing the rotor solid model into a finite number of cells based on meshing;
and 4, storing the coordinates of all nodes into a node database according to the sequence of the node numbers of the divided seeds, storing the node numbers applied by the units into a unit database according to the sequence of the unit numbers of the divided units, and integrating the node database and the unit database to form a file which can be directly read by the general finite element software.
3. The method for automatically meshing a turbine rotor according to claim 2, wherein said limiting maximum deviation factor in step 2 is 0.1.
4. The method for automatically meshing a turbine rotor according to claim 3, wherein the minimum size factor in step 2 is set to 0.1.
5. The method for automatically meshing a turbine rotor according to any one of claims 2 to 4, wherein said constraint geometric eccentricity factor in step 3 is less than 0.2.
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