A method for optimizing a blade cover volume based on multi-parameter description

Abstract

The application discloses a kind of blade cover quantity optimization methods based on multi-parameter description, adopt multiple parameters to establish the mathematical expression of the description engine blade three-dimensional space accumulation axis appearance, wherein, the axial accumulation offset of blade (i.e. axial cover quantity) and the circumferential accumulation offset (i.e. circumferential cover quantity) are all in the form of sine function and linear function superposition, and the radial height of each base section of blade remains unchanged.Through modeling software changes above-mentioned parameter, realize the adjustment of blade space accumulation axis, and with the aid of commercial finite element software analysis the maximum stress of blade under different accumulation axis, finally adopt optimization software obtains the axial and circumferential cover quantity of blade stress distribution optimum.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of engine structure strength, and particularly relates to a blade shroud quantity optimization method based on multi-parameter description. BACKGROUND

[0002] The initial profile of an engine blade is given by aerodynamic design, but in order to make the blade meet the requirements of strength, service life and deformation, etc., the profile of the blade needs to be adjusted under the premise of ensuring its aerodynamic performance. A commonly used method for optimizing the profile of an engine blade is to ensure that the profile of the blade in the blade height direction is unchanged, and to adjust the axial and circumferential positions (shroud quantity) of the profile, so as to reduce the maximum stress or maximum deformation on the blade and make the stress distribution of the blade basin and blade back as uniform as possible.

[0003] In order to facilitate the shroud quantity optimization of the blade, the traditional method sets the blade root as a fixed constraint, and the shroud quantity of the blade root section is unchanged, and the shroud quantity of the section in the blade height direction changes linearly. By changing the axial and circumferential shroud quantity of the blade tip section, the adjustment of the stacking axis of the blade is realized, so as to reduce the maximum stress of the blade basin / blade back or the deformation of the blade tip. However, with the development of the aviation industry, more advanced technologies and methods are applied to the development of engines, and the stacking axis of the rotor blade of a large engine is becoming more and more complex. It is difficult to achieve the optimization target by linearizing the change of the shroud quantity of the blade section along the blade height. For a high-performance small engine, the fan blade has the characteristics of a small hub ratio and a composite sweep, and therefore, the result obtained by simply taking the blade as an optimization target cannot well meet the requirements of structural strength, and the influence of the disc on the stress and deformation of the blade needs to be considered.

[0004] Therefore, in order to improve at least one of the defects in the above method, a more accurate blade shroud quantity optimization method is needed. SUMMARY

[0005] In order to solve the problems existing in the prior art, the purpose of the present application is to provide a blade shroud quantity optimization method based on multi-parameter description.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] A blade shroud quantity optimization method based on multi-parameter description comprises the following steps:

[0008] (1) According to the initial blade profile data of aerodynamic design, an initial shroud quantity equation of the blade is established in the form of a combination of a sine function and a linear function;

[0009] (2) A modeling software is used to generate a three-dimensional entity model of the initial blade data, and the initial shroud quantity equation established in step (1) is written into the input file of the modeling software through a parameterized modeling method, and then the modeling process is written into a batch processing file through secondary development;

[0010] (3) importing the three-dimensional entity model generated by the modeling software into the finite element software, writing the blade stress analysis process into an executable file through secondary development, and writing the maximum stress of the blade as an optimization target into an output file;

[0011] (4) writing a batch processing file of the finite element software to call the executable file generated in step (3) to perform blade stress analysis and result output;

[0012] (5) taking the input file written in step (2) as an input of the optimization process, taking the batch processing file as a control file of the modeling process in the optimization process, taking the output file written in step (3) as an output of the optimization process, and finally taking the batch processing file written in step (4) as a control file of the finite element analysis in the optimization process;

[0013] (6) selecting the parameters in the input file as optimization variables, the maximum stress in the output file as an optimization target, and setting the optimization direction as a minimum value;

[0014] (7) determining the circumferential and axial cover amounts of the blade according to the optimal result given by the optimization software.

[0015] In step (1), the expression of the initial cover amount equation is:

[0016] y c =a1*sin(2π*x)+b1*x (1)

[0017] y a =a2*sin(2π*x)+b2*x (2)

[0018] wherein y c , y a are the circumferential and axial cover amounts of the blade, a1, a2, b1, b2 are adjustable parameters, a1 and a2 represent the circumferential and axial cover amount amplitudes of the blade section, b1 and b2 represent the circumferential and axial cover amounts of the blade top section, and x is the ratio of the blade section radial height to the total height.

[0019] In the initial cover amount equation, the initial values of a1, a2, b1 and b2 are obtained by fitting the original blade profile cover amount data through the least square method.

[0020] In step (2), the modeling software is UG, a1, a2, b1 and b2 in the initial cover amount equation are written into the expression as variables and are assigned with the initial values fitted, y c and y a are written into the expression in the form of equation (1) and equation (2), and finally are exported into an input file in the.exp format.

[0021] In the step (2), the executable program UG_Update.exe is generated by using the secondary development function and the existing UG update code, and the generated three-dimensional entity model is saved as a.prt format file.

[0022] In the step (2), the UG_Update.exe, the input file.exp and the model file.prt are written into a batch file.bat, and the modified model file is output as an.x_t format file; the content of the batch file is: UG_Update.exe xx.prt xx.exp xx.x_t, wherein "xx" is the file name.

[0023] In the step (3), the finite element software is ANSYS, the.x_t model file is imported by using the classic interface, the unit type and material constant are set and the mesh is automatically divided; if the blade model is a rotating symmetric model with a disc, the rotating symmetric constraint is applied, otherwise the fixed constraint is applied at the blade root section; the given rotating speed is applied to the model, and the large deformation calculation is performed; after the calculation is completed, the general post-processing is entered, the NSORT and *GET commands are used to export the maximum effective stress obtained by the model calculation to a.txt file; finally, the entire finite element analysis process is exported to a.lgw file.

[0024] In the step (4), the finite element software is ANSYS, and the content of the batch file is: "**"-b-pANSYS-i xx.lgw-np 16-o xx.txt, wherein "**" is the installation path of the ANSYS classic interface software, and "xx" is the file name.

[0025] In the step (5), the optimization software is Isight, the Optimization module is selected as the execution task, and two Simcode modules are dragged into the optimization process; the first Simcode module functions as: taking the.exp file as the input file, defining the parameters a1, a2, b1 and b2, and taking the batch file written in the step (2) as the control file of the model update; the second Simcode module functions as: receiving the blade model transmitted by the first Simcode module, performing the stress analysis on the model by using the batch file written in the step (4), and outputting the result.

[0026] In the step (6), the single optimization time is ensured to be greater than the single finite element analysis time of the blade.

[0027] Beneficial effects: the application adopts multiple parameters to establish a mathematical expression describing the three-dimensional space accumulation axis appearance of the engine blade, wherein the axial accumulation offset of the blade (i.e. the axial cover amount) and the circumferential accumulation offset (i.e. the circumferential cover amount) are in the form of superposition of a sine function and a linear function, and the radial height of each base section of the blade remains unchanged. By changing the above parameters through modeling software, adjustment of the space accumulation axis of the blade is realized, and the maximum stress of the blade under different accumulation axes is analyzed by means of commercial finite element software, and finally the axial and circumferential cover amounts of the blade with the optimal stress distribution are obtained by using optimization software. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flow chart of the embodiment of the application;

[0029] Figure 2 is a schematic diagram of the blade cover amount in the embodiment of the application. DETAILED DESCRIPTION

[0030] The application will be further explained below in combination with the drawings.

[0031] Take the cover amount optimization of a small engine compressor blade as an example. As shown in Figure 1 , the blade cover amount optimization method based on multiple parameters described by the application comprises the following steps:

[0032] (1) According to the initial blade profile data of aerodynamic design, an initial cover amount equation of the blade is established in the form of combination of a sine function and a linear function;

[0033] and 4 parameters are selected as optimization variables:

[0034] y c =a1*sin(2π*x)+b1*x (1)

[0035] y a =a2*sin(2π*x)+b2*x (2)

[0036] wherein y c and y a are the circumferential and axial cover amounts of the blade, a1, a2, b1 and b2 are adjustable parameters, the initial values are obtained by least square fitting of the original blade profile cover amount data, specifically, a1 and a2 represent the circumferential and axial cover amount amplitudes of the blade section, and b1 and b2 represent the circumferential and axial cover amount of the blade top section; x is the ratio of the radial height of the blade section to the total height, i.e. the ratio of the radial height of the center of gravity point of the blade profile section to the total height of the blade profile. The initial cover amount is as shown in Figure 2

[0037] ​In this embodiment, a1=1.3mm, a2=1mm, b1=0.3mm, b2=0.9mm are obtained by fitting the original blade cover amount data by the least square method.

[0038] (2) The initial blade data is generated into a three-dimensional entity model by using modeling software, and the initial cover amount equation established in step (1) is written into the input file of the modeling software by using the parameterized modeling method, and then the modeling process is written into the batch processing file by using secondary development;

[0039] In the modeling software UG, a1, a2, b1 and b2 in the initial cover amount equation are written into the expression as variables and are given the initial values obtained by fitting, and then y c and y a are written into the expression in the form of equation (1) and equation (2), and finally are exported to the input file in the.exp format.

[0040] An executable program UG_Update.exe is generated by using the secondary development function and the existing UG update code, and the generated three-dimensional entity model is saved as a.prt format file.

[0041] UG_Update.exe, the input file.exp and the model file.prt are written into the batch processing file.bat, and the modified model file is output as an.x_t format; the content of the batch processing file is: UG_Update.exe xx.prt xx.exp xx.x_t, wherein “xx” is the file name.

[0042] (3) The three-dimensional entity model generated by the modeling software is imported into the finite element software, the stress analysis process of the blade is written into the executable file by using secondary development, and the maximum stress of the blade is written into the output file as the optimization target;

[0043] In the finite element software ANSYS, the.x_t model file is imported by using the classic interface, the unit type and material constant are set and the mesh is automatically divided; if the blade model is a rotating symmetric model with a disc, the rotating symmetric constraint is applied, otherwise the fixed constraint is applied at the blade root section; the given rotating speed is applied to the model, and the large deformation calculation is performed; after the calculation is completed, the general post-processing is entered, the maximum effective stress calculated by the model is exported to the.txt file by using the NSORT and *GET commands; finally, the entire finite element analysis process is exported to the.lgw file.

[0044] (4) The finite element software batch processing file is written to call the executable file generated in step (3) to perform the blade stress analysis and result output;

[0045] Wherein, the finite element software is ANSYS, the batch file content written is: "**"-b-p ANSYS-ixx.lgw-np 16-o xx.txt, wherein "**" is the installation path of the ANSYS classic interface software, and "xx" is the file name.

[0046] (5) taking the input file written in step (2) as the input of the optimization process and the batch file as the control file of the modeling process in the optimization process by optimizing the software, taking the output file written in step (3) as the output of the optimization process, and finally taking the batch file written in step (4) as the control file of the finite element analysis in the optimization process;

[0047] Wherein, the optimization software is Isight, the Optimization module is selected as the execution task, and two Simcode modules are dragged into the optimization process; the first Simcode module functions as: taking the.exp file as the input file, defining the parameters a1, a2, b1 and b2, and taking the batch file written in step (2) as the control file of the model updating; the second Simcode module functions as: receiving the blade model transmitted by the first Simcode module, performing stress analysis on the model by using the batch file written in step (4) and outputting the results.

[0048] (6) taking the parameters in the input file as the optimization variables and the maximum stress in the output file as the optimization target, and setting the optimization direction as the minimum value;

[0049] Wherein, the optimization method and the time are set according to specific cases, and the single optimization time is ensured to be greater than the single finite element analysis time of the blade. In this embodiment, the optimization method is set as Hooke-Jeeves, the total optimization time is 50000s, the model updating module time is 500s, and the finite element analysis module time is 5000s.

[0050] (7) determining the circumferential and axial cover amounts of the blade according to the optimal result given by the optimization software.

[0051] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for optimization of a vane shroud volume based on a multi-parameter description, characterized by: The method comprises the following steps: (1) according to the initial blade profile data of the aerodynamic design, an initial shroud amount equation of the blade is established in the form of a combination of a sine function and a linear function; The expression of the initial shroud amount equation is: (1) (2) wherein , are the blade circumferential and axial shroud amounts, respectively, , , , are adjustable parameters, and denote the blade section circumferential and axial shroud amount amplitudes, and denote the blade tip section circumferential and axial shroud amounts; x is the ratio of the blade section radial height to the total height. (2) a three-dimensional entity model is generated from the initial blade data by using modeling software, and the initial shroud amount equation established in step (1) is written into an input file of the modeling software by a parameterized modeling method, and then the modeling process is written into a batch processing file by secondary development; (3) the three-dimensional entity model generated by the modeling software is imported into a finite element software, a stress analysis process of the blade is written into an executable file by secondary development, and the maximum stress of the blade is written into an output file as an optimization target; (4) a batch processing file of the finite element software is written to call the executable file generated in step (3) to perform stress analysis of the blade and output results; (5) the input file written in step (2) is taken as an input of an optimization process and the batch processing file is taken as a control file of the modeling process in the optimization process, and the output file written in step (3) is taken as an output of the optimization process, and finally the batch processing file written in step (4) is taken as a control file of the finite element analysis in the optimization process; (6) parameters in the input file are taken as optimization variables, the maximum stress in the output file is taken as an optimization target, and an optimization direction is set to be a minimum value; (7) the circumferential and axial shroud amounts of the blade are determined according to the optimal result given by the optimization software.

2. The multi-parameter description based optimization method of blade shroud volume according to claim 1, characterized in that: In the initial cover quantity equation , , , The initial values ​​were obtained by fitting the original blade cover data using the least squares method.

3. The multi-parameter description based optimization method of blade shroud volume according to claim 1, characterized in that: In the step (2), the modeling software UG writes the initial mask amount equation , , , as variables in the expression and gives the initial values obtained by fitting, and then writes and in the form of equation (1) and equation (2) in the expression, and finally derives the input file in the.exp format.

4. The multi-parameter description based optimization method of blade shroud volume according to claim 3, characterized in that: In step (2), an executable program UG_Update.exe is generated by using the secondary development function and the existing UG update code, and the generated three-dimensional entity model is saved as a.prt format file.

5. The multi-parameter description based optimization method of blade shroud volume according to claim 4, characterized in that: In step (2), UG_Update.exe, the input file.exp and the model file.prt are written into a batch processing file.bat, and the modified model file is output as an.x_t format file; the content of the batch processing file is: UG_Update.exe xx.prt xx.exp xx.x_t, wherein "xx" is a file name.

6. The multi-parameter description based optimization of blade shroud volume method of claim 1, wherein: In step (3), the finite element software is ANSYS, the.x_t model file is imported by using a classic interface, the unit type and material constants are set and the mesh is automatically divided; if the blade model is a rotating symmetrical model with a disc, a rotating symmetrical constraint is applied, otherwise a fixed constraint is applied at the blade root section; a given rotating speed is applied to the model, and a large deformation calculation is performed; after the calculation is completed, a general post-processing is performed, the maximum effective stress calculated by the model is exported to a.txt file by using NSORT and *GET commands; Finally, the entire finite element analysis process is exported to a.lgw file.

7. The multi-parameter description based optimization method of blade shroud volume according to claim 1, characterized in that: In step (4), the finite element software is ANSYS, and the content of the batch processing file is: "**" -b -p ANSYS -i xx.lgw -np16 -o xx.txt, wherein "**" is the installation path of the ANSYS classic interface software, and "xx" is a file name.

8. The multi-parameter description based optimization of blade shroud volume method of claim 1, wherein: In the step (5), the optimization software is Isight, the Optimization module is selected as the execution task, and two Simcode modules are dragged into the optimization process; the first Simcode module functions as: taking the.exp file as an input file, defining parameters , , , , and taking the batch file written in the step (2) as a control file for model updating; the second Simcode module functions as: receiving the blade model transmitted by the first Simcode module, performing stress analysis on the model by using the batch file written in the step (4), and outputting the result.

9. The multi-parameter description based optimization of blade shroud volume method of claim 1, wherein: In step (6), it is ensured that the single optimization time is greater than the single finite element analysis time of the blade.

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