Method and system for generating cold blade machining coordinates based on ANSYS-APDL language

Abstract

A method for generating cold blade machining coordinates developed based on the ANSYS-APDL language comprises the following steps: first, establishing a hot blade control point sub-model based on the hot blade control point coordinates; defining a cutting boundary based on the hot blade control point sub-model; storing a hot blade control point sub-model database file in APDL; interpolating the cutting boundary of the hot blade control point sub-model using the CBDOF command in APDL based on the hot blade finite element model and the hot-to-cold blade deformation calculation results; obtaining the node deformation of the hot blade control point sub-model; and obtaining an updated hot blade control point sub-model using the UPGEOM command in APDL; the updated node coordinates of the hot blade control point sub-model are the cold blade machining coordinates. The present invention also provides a cold blade machining coordinate generation system. The present invention significantly reduces the degree of manual intervention and improves the efficiency of generating cold blade machining coordinates.

Description

Technical Field

[0001] The present invention belongs to the technical field of impeller machine blades and relates to a method and system for generating cold blade machining coordinates developed based on the ANSYS-APDL language. Background Art

[0002] The aerodynamic performance of turbomachinery blades is usually assessed under the design state. Under the design state, the blades are subjected to a composite load including thermal load, centrifugal load and aerodynamic load. At this time, the blade profile is usually called a hot blade profile. However, in the processing state, the blades are not subjected to the above composite loads. At this time, the blade profile is usually called a cold blade profile. Due to the effect of the complex load, there is a certain difference between the hot blade profile and the cold blade profile. This difference often has a negative impact on the aerodynamic performance of the blade, especially for high-load impeller blades. The impact of this blade profile difference on aerodynamic performance is more significant. Therefore, before processing the blade, it is necessary to obtain the blade processing coordinates based on the cold blade profile.

[0003] Using structural finite element software, although the finite element model of the cold blade can be obtained through iterative calculation based on the hot blade finite element model, the nodes of the blade finite element model are usually relatively sparse, which makes it impossible to accurately model the areas with large curvature of the leading and trailing edges of the blade, and the nodes of the finite element model are arranged in a disorderly manner. The above factors make it impossible to use the finite element model to directly generate the processing coordinates of the cold blade.

[0004] At present, the methods for obtaining cold blade machining coordinates mainly include:

[0005] (1) Patent No. CN201510915701.2, “Method and Apparatus for Generating Production Coordinates of Impeller Blades,” proposes to obtain blade processing coordinates by sorting, interpolating, and encrypting nodes based on a cold blade finite element model. This invention overcomes the difficulty of generating cold blade processing coordinates based on a structural finite element model, but the method requires a high mesh density of the finite element model, resulting in a large amount of calculation and a long time consumption.

[0006] (2) The invention with patent number CN202110640447.5, “A method and device for generating blade processing coordinates”, constructs a cold blade profile through grid interpolation and modeling approximation. When calculating the conversion between cold and hot blade profiles, a finite element model with relatively low grid density is used to reduce the amount of calculation. However, the method still cannot avoid sorting and interpolating the nodes in the finite element model. The steps are relatively cumbersome and require more manual intervention.

[0007] (3) The paper "Application of Hot and Cold State Conversion of Turbine Blade Profiles in Liquid Rocket Engines" uses a BP neural network to project the deformation of the cold blade finite element model nodes onto the contour surface blade control points, thereby obtaining the coordinates of the blade control points in the processed state. This method requires extracting the coordinates and deformation of all nodes in the blade finite element model and then performing iterative calculations to obtain the mapping relationship between the blade surface node coordinate position and deformation. This method also has the problems of large computational complexity and long time consumption.

[0008] Therefore, there is an urgent need to design an efficient, convenient and highly automated method for outputting cold blade processing coordinates. Summary of the Invention

[0009] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology and propose a cold blade processing coordinate generation method and system developed based on the ANSYS-APDL language, which greatly reduces the degree of manual intervention and improves the efficiency of cold blade processing coordinate generation.

[0010] The solution of the present invention is:

[0011] A cold blade machining coordinate generation method developed based on ANSYS-APDL language includes:

[0012] Obtain the coordinates of the hot-state blade control points, read the coordinates of the hot-state blade control points in APDL using the *VREAD command in a cyclic manner, and establish a hot-state blade control point sub-model based on the coordinates of the hot-state blade control points;

[0013] Based on the hot blade control point sub-model, a cutting boundary is defined, and the cutting boundary node information is output using the NWRITE command in APDL;

[0014] Store the hot blade control point sub-model database file in APDL;

[0015] Obtain the hot blade finite element model database file and the hot-to-cold blade deformation calculation result file. Based on the hot blade finite element model and the hot-to-cold blade deformation calculation results, use the CBDOF command in APDL to perform cutting boundary interpolation on the hot blade control point sub-model.

[0016] In APDL, the cutting boundary displacement interpolation result is used as the mandatory displacement constraint to load and solve the hot blade control point sub-model to obtain the node deformation of the hot blade control point sub-model;

[0017] In APDL, the UPGEOM command is used to subtract the node deformation of the hot blade shape control point sub-model from the node coordinates of the hot blade shape control point sub-model to obtain the updated hot blade shape control point sub-model.

[0018] In APDL, the updated hot blade profile control point sub-model node coordinates are written out using the *VWRITE command in a cyclic manner. The updated hot blade profile control point sub-model node coordinates are the cold blade processing coordinates.

[0019] Preferably, the hot blade profile control point sub-model is established based on the hot blade profile control point coordinates as follows:

[0020] Establish nodes based on the coordinates of hot blade control points;

[0021] A mass unit is established for each node to realize the modeling of the hot blade profile control point sub-model.

[0022] Preferably, the cutting boundary is all nodes of the hot blade profile control point sub-model.

[0023] Preferably, when the cutting boundary interpolation is performed using the CBDOF command, the value range of the parameter item interpolation tolerance TOLOUT in the CBDOF command is 0.4 to 0.5.

[0024] Preferably, when the UPGEOM command is used to update the hot blade profile control point sub-model, the value of the parameter item proportional coefficient FACTOR in the UPGEOM command is -1.

[0025] Preferably, the coordinates of the hot blade profile control points are stored in a data file or text file format.

[0026] A cold blade machining coordinate generation system developed based on the ANSYS-APDL language includes a hot blade profile control point sub-model establishment module, a cutting boundary definition module, a cutting boundary interpolation module, a node deformation calculation module, a hot blade profile control point sub-model update module, and a cold blade machining coordinate acquisition module.

[0027] Hot-state blade profile control point sub-model establishment module: obtains the hot-state blade profile control point coordinates, reads the hot-state blade profile control point coordinates in APDL using the *VREAD command in a cyclic manner, establishes the hot-state blade profile control point sub-model based on the hot-state blade profile control point coordinates, and stores the hot-state blade profile control point sub-model database file in APDL;

[0028] Cutting boundary definition module: defines cutting boundaries based on the hot blade control point sub-model, and uses the NWRITE command in APDL to output cutting boundary node information;

[0029] Cutting boundary interpolation module: obtains the hot blade finite element model database file and the hot-to-cold blade deformation calculation result file, and uses the CBDOF command in APDL to perform cutting boundary interpolation on the hot blade control point sub-model based on the hot blade finite element model and the hot-to-cold blade deformation calculation results. The interpolation result is sent to the node deformation solution module;

[0030] Node deformation solution module: In APDL, the cutting boundary displacement interpolation result is used as the mandatory displacement constraint to load and solve the hot blade control point sub-model, obtain the node deformation of the hot blade control point sub-model, and send it to the hot blade control point sub-model update module;

[0031] Hot blade control point sub-model update module: Use the UPGEOM command in APDL to subtract the hot blade control point sub-model node deformation from the hot blade control point sub-model node coordinates to obtain the updated hot blade control point sub-model and send it to the cold blade processing coordinate acquisition module;

[0032] Cold blade processing coordinate acquisition module: Use the *VWRITE command in APDL in a cyclic manner to write out the updated hot blade control point sub-model node coordinates. The updated hot blade control point sub-model node coordinates are the cold blade processing coordinates.

[0033] Preferably, the hot airfoil control point sub-model establishing module establishes the hot airfoil control point sub-model based on the hot airfoil control point coordinates in the following manner:

[0034] Establish nodes based on the coordinates of hot blade control points;

[0035] A mass unit is established for each node to realize the modeling of the hot blade profile control point sub-model.

[0036] Preferably, when the cutting boundary interpolation module uses the CBDOF command to perform cutting boundary interpolation, the value range of the parameter item interpolation tolerance TOLOUT in the CBDOF command is 0.4 to 0.5.

[0037] Preferably, when the hot-state blade profile control point sub-model updating module uses the UPGEOM command to update the hot-state blade profile control point sub-model, the value of the parameter item proportional coefficient FACTOR in the UPGEOM command is -1.

[0038] The beneficial effects of the present invention compared with the prior art are:

[0039] (1) The present invention makes full use of the orderliness and high density of the hot blade profile control points, avoids the sorting and interpolation encryption of the blade finite element model nodes, and greatly reduces the workload and improves the processing efficiency from the perspective of the operation process.

[0040] (2) The present invention develops an automated program for generating cold blade machining coordinates based on the ANSYS-APDL language, which greatly reduces the degree of manual intervention and improves calculation efficiency.

[0041] (3) The present invention finally obtains the cold blade processing coordinates on the basis of interpolating the hot blade profile control point sub-model based on the hot-to-cold blade deformation, which means that the finite element model used in the hot-to-cold blade profile conversion calculation only needs to meet the convergence accuracy requirements, and there is no need to further refine the finite element model grid from the perspective of encrypting the blade profile control points. Therefore, it is beneficial to reduce the amount of finite element calculation when converting the hot-to-cold blade profile. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart for generating cold blade machining coordinates proposed by the present invention;

[0043] Figure 2 This is a schematic diagram of a typical hot-state blade control point sub-model node;

[0044] Figure 3 It is a typical hot blade finite element model and hot blade profile control point sub-model;

[0045] Figure 4 Schematic diagram of displacement constraint loading for a typical hot blade control point sub-model. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementations.

[0047] On the premise that the coordinates of the hot blade profile control points are known and the hot-to-cold blade profile conversion calculation is completed to obtain the hot-to-cold blade deformation, the present invention adopts a cold blade processing coordinate generation method based on sub-model analysis developed based on ANSYS-APDL language to obtain the cold blade processing coordinates.

[0048] Figure 1 The flowchart of the cold blade machining coordinate generation method proposed by the present invention and developed based on the ANSYS-APDL language is shown, which includes the following steps:

[0049] Step 1: Create an array in APDL based on the coordinates of the hot blade control points, and write the coordinates of the hot blade control points into the array using the *VREAD command in a loop. Enter the pre-processing module, define the unit type and unit real constants, the unit type is MASS21, and the unit real constant corresponding to the unit mass can be set to any value greater than zero, which will not affect the calculation results. Use a loop to create nodes based on the hot blade control point coordinates stored in the array, and then create mass units based on the nodes, thereby completing the modeling of the hot blade control point sub-model. The established hot blade control point sub-model is as follows: Figure 2 .

[0050] Step 2: Based on the hot blade control point sub-model, all nodes are selected as cutting boundaries in APDL, and the cutting boundary node information is output using the NWRITE command.

[0051] Step 3: Store the model data file of the hot blade control point sub-model in APDL.

[0052] Step 4: Get the hot blade finite element model database file and the hot-to-cold blade deformation calculation result file, enter the post-processing module in APDL, read in the hot blade finite element model data file, and read in the hot-to-cold blade deformation calculation result file. The spatial relative position of the hot blade finite element model and the hot blade control point sub-model is as follows: Figure 3 .

[0053] Step 5: Using the CBDOF command in APDL, based on the hot blade finite element model and the deformation calculation results of the hot-to-cold blade, perform cutting boundary interpolation on the hot blade control point sub-model;

[0054] Step 6: Read the model database file of the hot blade control point sub-model in APDL, and load the hot blade control point sub-model by defining the node forced displacement constraint using the cutting boundary interpolation result. Figure 4 , and solve it in the solution module to obtain the deformation calculation results of the hot blade control point sub-model;

[0055] Step 7: Use the UPGEOM command in APDL to update the model, subtract the deformation of the hot blade control point sub-model from the node coordinates of the hot blade control point sub-model, and thus obtain the updated hot blade control point sub-model;

[0056] Step eight, in APDL, use the *VWRITE command in a loop to output the updated hot blade profile control point sub-model node coordinates to a data file in the specified format. The updated hot blade profile control point sub-model node coordinates are the cold blade processing coordinates.

[0057] In the present invention, the coordinates of the hot blade profile control points are stored in a data file or text file format, for example, POINTS.DAT or POINTS.TXT.

[0058] The hot-to-cold blade profile conversion calculation is completed based on the hot blade finite element model, which is stored in a database file format, for example, MODEL.DB.

[0059] The hot-to-cold blade deformation is the hot-to-cold blade profile conversion calculation result, and the hot-to-cold blade profile conversion calculation result is stored in a result file format, for example, MODEL.RST.

[0060] When using the CBDOF command to perform cutting boundary interpolation, the typical value range of the interpolation tolerance TOLOUT parameter in the CBDOF command is 0.4 to 0.5.

[0061] When using the UPGEOM command to update the hot blade control point sub-model, the typical value of the parameter scale factor FACTOR in the UPGEOM command is -1.

[0062] The present invention makes full use of the orderliness and high density of hot blade profile control points, avoids the sorting and interpolation encryption of the blade finite element model nodes, and greatly reduces the workload and improves the processing efficiency from the perspective of the operation process. The finite element model used in the hot-to-cold blade profile conversion calculation of the present invention only needs to meet the convergence accuracy requirements, and there is no need to further refine the finite element model grid from the perspective of encrypting the blade profile control points. Therefore, it is beneficial to reduce the amount of finite element calculations when converting the hot-to-cold blade profile. The degree of manual intervention is greatly reduced and the calculation efficiency is improved.

[0063] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in this field.

Claims

1. A cold blade machining coordinate generation method based on ANSYS-APDL language, characterized in that include: Obtain the coordinates of the hot-state blade control points, read the coordinates of the hot-state blade control points in APDL using the *VREAD command in a cyclic manner, and establish a hot-state blade control point sub-model based on the coordinates of the hot-state blade control points; Based on the hot blade control point sub-model, a cutting boundary is defined, and the cutting boundary node information is output using the NWRITE command in APDL; Store the hot blade control point sub-model database file in APDL; Obtain the hot blade finite element model database file and the hot-to-cold blade deformation calculation result file. Based on the hot blade finite element model and the hot-to-cold blade deformation calculation results, use the CBDOF command in APDL to perform cutting boundary interpolation on the hot blade control point sub-model. In APDL, the cutting boundary displacement interpolation result is used as the mandatory displacement constraint to load and solve the hot blade control point sub-model to obtain the node deformation of the hot blade control point sub-model; In APDL, the UPGEOM command is used to subtract the node deformation of the hot blade shape control point sub-model from the node coordinates of the hot blade shape control point sub-model to obtain the updated hot blade shape control point sub-model. In APDL, the updated hot blade profile control point sub-model node coordinates are written out using the *VWRITE command in a cyclic manner. The updated hot blade profile control point sub-model node coordinates are the cold blade processing coordinates.

2. The cold blade machining coordinate generation method developed based on ANSYS-APDL language according to claim 1 is characterized in that: The method of establishing the hot blade profile control point sub-model based on the hot blade profile control point coordinates is as follows: Establish nodes based on the coordinates of hot blade control points; A mass unit is established for each node to realize the modeling of the hot blade profile control point sub-model.

3. The cold blade machining coordinate generation method developed based on ANSYS-APDL language according to claim 1, characterized in that: The cutting boundary is all nodes of the hot blade control point sub-model.

4. The cold blade machining coordinate generation method developed based on ANSYS-APDL language according to claim 1, characterized in that: When using the CBDOF command for cutting boundary interpolation, the value range of the interpolation tolerance TOLOUT parameter in the CBDOF command is 0.4 to 0.

5.

5. The cold blade machining coordinate generation method developed based on ANSYS-APDL language according to claim 1, characterized in that: When using the UPGEOM command to update the hot blade control point sub-model, the value of the parameter item proportional coefficient FACTOR in the UPGEOM command is -1.

6. The cold blade machining coordinate generation method developed based on ANSYS-APDL language according to claim 1, characterized in that: The hot blade profile control point coordinates are stored in a data file or text file format.

7. A cold blade machining coordinate generation system developed based on ANSYS-APDL language, characterized by: It includes hot blade control point sub-model establishment module, cutting boundary definition module, cutting boundary interpolation module, node deformation solution module, hot blade control point sub-model update module, and cold blade processing coordinate acquisition module; Hot-state blade profile control point sub-model establishment module: obtains the hot-state blade profile control point coordinates, reads the hot-state blade profile control point coordinates in APDL using the *VREAD command in a cyclic manner, establishes the hot-state blade profile control point sub-model based on the hot-state blade profile control point coordinates, and stores the hot-state blade profile control point sub-model database file in APDL; Cutting boundary definition module: defines cutting boundaries based on the hot blade control point sub-model, and uses the NWRITE command in APDL to output cutting boundary node information; Cutting boundary interpolation module: obtains the hot blade finite element model database file and the hot-to-cold blade deformation calculation result file, and uses the CBDOF command in APDL to perform cutting boundary interpolation on the hot blade control point sub-model based on the hot blade finite element model and the hot-to-cold blade deformation calculation results. The interpolation result is sent to the node deformation solution module; Node deformation solution module: In APDL, the cutting boundary displacement interpolation result is used as the mandatory displacement constraint to load and solve the hot blade control point sub-model, obtain the node deformation of the hot blade control point sub-model, and send it to the hot blade control point sub-model update module; Hot blade control point sub-model update module: Use the UPGEOM command in APDL to subtract the hot blade control point sub-model node deformation from the hot blade control point sub-model node coordinates to obtain the updated hot blade control point sub-model and send it to the cold blade processing coordinate acquisition module; Cold blade processing coordinate acquisition module: Use the *VWRITE command in APDL in a cyclic manner to write out the updated hot blade control point sub-model node coordinates. The updated hot blade control point sub-model node coordinates are the cold blade processing coordinates.

8. The cold blade machining coordinate generation system developed based on ANSYS-APDL language according to claim 7, characterized in that: The hot blade shape control point sub-model establishment module establishes the hot blade shape control point sub-model based on the hot blade shape control point coordinates in the following manner: Establish nodes based on the coordinates of hot blade control points; A mass unit is established for each node to realize the modeling of the hot blade profile control point sub-model.

9. The cold blade machining coordinate generation system developed based on ANSYS-APDL language according to claim 7, characterized in that: When the cutting boundary interpolation module uses the CBDOF command to perform cutting boundary interpolation, the value range of the parameter item interpolation tolerance TOLOUT in the CBDOF command is 0.4 to 0.

5.

10. The cold blade machining coordinate generation system developed based on ANSYS-APDL language according to claim 7, characterized in that: When the hot blade profile control point sub-model update module uses the UPGEOM command to update the hot blade profile control point sub-model, the value of the parameter item proportional coefficient FACTOR in the UPGEOM command is -1.

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