A low-pressure turbine shaft spatial layout design method

Abstract

The application belongs to the field of overall structure design of an aero-engine, and relates to a low-pressure turbine shaft spatial layout design method. The overall performance input parameters and temperature boundary parameters of a low-pressure shaft are given first to determine the overall structure cavity spatial layout scheme, the preliminary layout, size and material range of the low-pressure shaft, and then the basic physical performance of the low-pressure shaft is determined by selecting the material of the low-pressure shaft. The initial values of the inner diameter size and shaft length of the low-pressure shaft and the initial static strength design parameters are given first, and then the other key control sizes of the low-pressure shaft scheme are obtained through program iterative calculation. Since the program automatic iterative calculation is adopted, the scheme design is fast and convenient. In the subsequent static strength analysis, machinability analysis and bearing DN value analysis, due to the reduction of variables, the numerical values that need to be improved can be quickly determined, so that the final design of the low-pressure turbine shaft scheme can be quickly completed. The application is convenient to use, high in design efficiency, short in calculation period and low in work cost.

Description

Technical Field

[0001] This application belongs to the field of overall structural design of aero-engines, and specifically relates to a spatial layout design method for a low-pressure turbine shaft. Background Technology

[0002] The overall structural layout design of an aero-engine refers to proposing an overall structural layout scheme that meets the product's functional and performance requirements based on the engine's operational needs, environmental conditions, and functional requirements. In the aero-engine design process, the spatial layout of the low-pressure turbine shaft is a crucial component of the overall layout scheme.

[0003] The existing design methodology for the low-pressure turbine shaft space layout of a dual-rotor turbine engine includes nine design steps:

[0004] 1. Determine overall performance input parameters; 2. Determine temperature boundaries; 3. Determine material selection parameters; 4. Determine shaft inner / outer diameter dimensions; 5. Strength analysis; 6. Strength criterion judgment; 7. Machinability analysis; 8. Bearing DN value analysis; 9. Output low-pressure shaft space dimensions.

[0005] The current technical solution has the following drawbacks:

[0006] 1. Existing methods do not consider the dynamic characteristics of low-pressure shafts, and there is a risk of the solution being overturned in subsequent design processes;

[0007] 2. Existing methods, in the static strength analysis process, first provide the initial structural dimensions, then perform static strength evaluation, and find structural parameters that meet the strength requirements through continuous manual calculations. Since static strength analysis involves many parameters, multiple iterative calculations are required in steps 3-6, resulting in low design efficiency and a long design cycle.

[0008] Therefore, how to design low-pressure turbine shafts more quickly and efficiently is a problem that needs to be solved. Summary of the Invention

[0009] The purpose of this application is to provide a spatial layout design method for low-pressure turbine shafts to solve the problems of low design efficiency and long design cycle of low-pressure turbine shafts in the prior art.

[0010] The technical solution of this application is: a method for designing the spatial layout of a low-pressure turbine shaft, comprising: determining overall performance input parameters and performing a preliminary overall structural chamber spatial layout design; determining the temperature boundary parameters of the low-pressure shaft according to the overall structural chamber spatial layout scheme; determining the material parameters of the low-pressure shaft according to the temperature boundary of the low-pressure shaft; giving appropriate initial values ​​for the inner diameter and shaft length of the low-pressure shaft; selecting initial static strength design coefficients for the low-pressure shaft, including: yield strength coefficient, ultimate strength coefficient, failure strength coefficient, and torsional instability strength coefficient; obtaining key structural parameters and strength design parameters based on the inner diameter, shaft length, and static strength design coefficients of the low-pressure shaft, wherein the key structural parameters include the outer diameter of the low-pressure shaft; performing static strength analysis and judging the results of the static strength analysis; if the strength design criteria are met, proceeding to the next step; performing machinability analysis; if the machinability is met, proceeding to the next step; analyzing the DN value of the outer bearing of the low-pressure shaft; if the strength design criteria are met, completing the dynamic key characteristic evaluation and proceeding to the next step; outputting the spatial dimensions of the low-pressure turbine shaft and the final static strength design coefficients as inputs for the low-pressure shaft structural design.

[0011] Preferably, after the DN value of the outer bearing of the low-pressure shaft is determined, a dynamic feasibility analysis is performed on the low-pressure shaft. The feasibility of the dynamic scheme is estimated by analyzing the corresponding dynamic control parameters. If it is feasible, the next step is executed; if it is not feasible, the initial values ​​of the inner diameter and the shaft length of the low-pressure shaft are given again, and the calculation is repeated until the requirements are met.

[0012] Preferably, the calculation program for the corresponding parameters is edited. After obtaining the inner diameter, shaft length and initial static strength design coefficient of the low-pressure shaft, the obtained strength parameters are input into the calculation program as input values ​​for iterative calculation to obtain the key structural parameters and final static strength design coefficient of the low-pressure shaft.

[0013] Preferably, during the static strength analysis, if the strength design criteria are not met, the material parameters of the low-pressure shaft are first re-given for another iterative calculation and determination. If the design requirements are still not met, the initial value of the inner diameter of the low-pressure shaft is re-given, and iterative calculation continues until the strength criteria are met.

[0014] Preferably, during the process of performing the machinability analysis, if the machinability requirements cannot be met, the initial values ​​of the inner diameter and shaft length of the low-pressure shaft are redefined, and the calculation is repeated iteratively until the machinability criteria are met.

[0015] Preferably, during the determination of the DN value of the low-pressure shaft bearing, if the design criteria are not met, the initial values ​​of the inner diameter and shaft length of the low-pressure shaft are redefined, and the calculation is repeated iteratively until the DN value criteria of the bearing are met.

[0016] This application discloses a spatial layout design method for a low-pressure turbine shaft. By first providing overall performance input parameters and temperature boundary parameters for the low-pressure shaft, the overall structural chamber spatial layout scheme, preliminary layout, dimensions, and material range of the low-pressure shaft are determined. Then, the basic physical properties of the low-pressure shaft are determined by selecting the appropriate material. Initial values ​​for the shaft's inner diameter and length, as well as initial static strength design parameters, are given first. Then, key control dimensions for other low-pressure shaft schemes are obtained through iterative calculations. Due to the use of automatic iterative calculations, the scheme design is fast and convenient. In subsequent static strength analysis, machinability analysis, and bearing DN value analysis, the reduced number of variables allows for rapid identification of values ​​requiring improvement, thus quickly completing the final design of the low-pressure turbine shaft scheme. This method is convenient to use, highly efficient, has a short calculation cycle, and low operating costs. It can solve both the problems of predicting the dynamic characteristics and static strength of low-pressure shafts. Furthermore, this invention can be widely used in the overall structural design of different types of conventional aero-engines and ground-based gas turbines, with a broad range of applications. Attached Figure Description

[0017] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0018] Figure 1 This is a schematic diagram of the overall process of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0020] A spatial layout design method for a low-pressure turbine shaft is proposed. Compared with the prior art, which initially selects the inner and outer diameters of the low-pressure shaft, the accuracy of these inner and outer diameters cannot be determined, thus requiring repeated trial and error and resulting in low efficiency. This application adopts a method of first giving a standard low-pressure shaft size and then deriving the numerical range of other sizes in reverse. Through this reverse derivation method, the data can be selected quickly, thereby ensuring the efficiency of the design.

[0021] like Figure 1 As shown, the specific design includes:

[0022] Step S100: Determine the overall performance input parameters and conduct preliminary overall structural chamber space layout design;

[0023] The overall performance input parameters of an aero-engine include the type of aero-engine, its usage method, and flight status. Then, appropriate overall performance state points and parameters such as the functions of its low-pressure system are selected as input parameters for the spatial boundary layout design.

[0024] Step S200: Based on the overall structural chamber space layout scheme, determine the temperature boundary parameters of the low-pressure shaft. The temperature boundary parameters of the low-pressure shaft limit the size design range of the low-pressure shaft. The temperature boundary parameters can be obtained through heat transfer analysis.

[0025] Step S300: Determine the material parameters of the low-pressure shaft based on the temperature boundary of the low-pressure shaft; the necessary material properties include elastic modulus, Poisson's ratio, and fatigue life. The material parameters of the low-pressure shaft determine the initial weight of the power turbine shaft design.

[0026] Step S400: Estimate the dynamic characteristics of the low-pressure shaft by giving appropriate initial values ​​for the inner diameter and length of the low-pressure shaft.

[0027] Compared to the existing low-pressure shaft inner and outer diameter dimensions, which cannot be determined to be suitable, the initial values ​​of the low-pressure shaft inner diameter and shaft length are directly suitable values ​​given here through subsequent calculations. Other variables are then obtained through iterative calculations by the program. Since at least two variables are reduced during the calculation process, the calculation efficiency is greatly improved and the number of iterations is reduced.

[0028] Given suitable low-pressure shaft inner diameter and initial values, and shaft length initial values ​​within a range, there are multiple sets. In the actual process, only one set of suitable specific coefficients can be given, and then the determination is made through subsequent design.

[0029] Step S500: Based on the parameters in steps S100-S300 and the type of engine, estimate the strength of the low-pressure shaft and select the initial static strength design coefficient of the low-pressure shaft, including: yield strength coefficient, ultimate strength coefficient, failure strength coefficient and torsional buckling strength coefficient.

[0030] Static strength analysis is not performed here either. Instead, appropriate static strength design coefficients are given directly. Although the set of static strength design coefficients given here and the set of coefficients given in step S400 both meet the initial design requirements, there is a possibility that the static strength design data and the low-pressure shaft size data may conflict, which needs to be determined in subsequent design.

[0031] Step S600: Based on the inner diameter, shaft length and static strength design coefficient of the low-pressure shaft, obtain the key structural parameters and the final strength design parameters. The key structural parameters include the outer diameter of the low-pressure shaft.

[0032] By calculating and obtaining the key structural parameters and strength design parameters of the low-pressure shaft, the external structure of the low-pressure shaft and the design parameters of the bearings are determined, thus completing the design of the initial model of the low-pressure shaft. The design can be a finite element model or other models.

[0033] To improve design efficiency, a calculation program for corresponding parameters was designed. After obtaining the inner diameter, shaft length, and static strength design coefficient of the low-pressure shaft, these parameters are input into the program for iterative calculation. This involves steps such as data calculation, parameter data classification, data storage, and data display to obtain the key structural parameters and final static strength design coefficient of the low-pressure shaft. Because the design involves relatively few variables, the calculation is fast. Furthermore, the use of a program significantly improves efficiency and accuracy compared to manual calculation.

[0034] Step S700: Perform static strength analysis, and determine the results of the static strength analysis. If the strength design criteria are met, proceed to the next step.

[0035] By performing static strength analysis, the loads that the low-pressure shaft can withstand at various locations were obtained. If all deterministic loads meet the design criteria, it means that the size design and static strength design parameters of the low-pressure shaft are reasonable; otherwise, it means that they are unreasonable and there is a conflict between the data, so at least one of the parameters needs to be redefined.

[0036] Among the key factors affecting the static strength of the low-pressure shaft, material and size are critical. If the strength design criteria are not met or the program cannot converge, the material parameters of the low-pressure shaft are first re-given and the calculation and judgment are repeated again, that is, the process returns to step S300. If the design requirements are still not met, the process returns to step S400, the initial value of the inner diameter of the low-pressure shaft is re-given, and the calculation continues until the strength criteria are met.

[0037] Step S800: Perform a manufacturability analysis. If the requirements are met, proceed to the next step.

[0038] The machinability of the low-pressure shaft is only affected by its dimensions. If there are certain locations where the machinability requirements cannot be met, the process returns to step S400, where the initial values ​​of the inner diameter and shaft length of the low-pressure shaft are given again, and the calculation continues iteratively until the machinability criteria are met.

[0039] Step S900: Analyze the DN value of the outer bearing of the low-pressure shaft. If the design criteria are met, the evaluation of key dynamic characteristics is completed, and the next step is executed.

[0040] The DN value of the outer bearing of the low-pressure shaft is only affected by the size of the low-pressure shaft. Therefore, if the designed bearing does not meet the design criteria, it is necessary to return to step S400, the initial value of the inner diameter of the low-pressure shaft and the initial value of the shaft length, and continue to iterate until the bearing DN value criterion requirement is met.

[0041] In step S1000, after determining the DN value of the outer bearing of the low-pressure shaft, a dynamic feasibility analysis is performed on the low-pressure shaft. The failure risk at each location is assessed, and the feasibility of the dynamic scheme is predicted by analyzing the corresponding dynamic control parameters. If feasible, proceed to the next step; if not feasible, return to step S400, re-determine the initial values ​​of the inner diameter and shaft length of the low-pressure shaft, and repeat the calculation until the requirements are met. By performing a dynamic feasibility analysis, the rationality of the spatial layout of the low-pressure turbine shaft can be determined more accurately, ensuring the quality of the design.

[0042] Step S1100 outputs the low-pressure turbine shaft space dimensions and the final static strength design coefficient as inputs for the low-pressure shaft structure design.

[0043] In the process of designing the spatial layout of the low-pressure turbine shaft, the overall structural chamber spatial layout scheme, preliminary layout, dimensions, and material range of the low-pressure shaft are determined by first providing the overall performance input parameters and temperature boundary parameters of the low-pressure shaft. Then, the basic physical properties of the low-pressure shaft are determined by selecting the material. Initial values ​​for the inner diameter and shaft length of the low-pressure shaft, as well as initial static strength design parameters, are given first, and then key control dimensions for other low-pressure shaft schemes are obtained through iterative calculations by the program. Due to the use of automatic iterative calculations, the scheme design is fast and convenient. In subsequent static strength analysis, machinability analysis, and bearing DN value analysis, the reduced number of variables allows for the rapid identification of values ​​requiring improvement, thus quickly completing the final design of the low-pressure turbine shaft scheme. This method is convenient to use, highly efficient, has a short calculation cycle, and low operating costs. It can solve both the problem of predicting the dynamic characteristics and the problem of predicting the static strength of the low-pressure shaft. Furthermore, this invention can be widely used in the overall structural design of different types of conventional aero-engines and ground gas turbines, with a broad range of applications.

[0044] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for designing the spatial layout of a low-pressure turbine shaft, characterized in that, include: Determine the overall performance input parameters of the aero-engine and conduct preliminary overall structural chamber space layout design; Based on the overall structural chamber space layout scheme, the temperature boundary parameters of the low-pressure turbine shaft are determined; The material parameters of the low-pressure turbine shaft are determined based on the temperature boundary of the low-pressure turbine shaft. Given suitable initial values ​​for the inner diameter and length of the low-pressure turbine shaft; The initial static strength design factors for the low-pressure turbine shaft are selected, including: yield strength factor, ultimate strength factor, failure strength factor, and torsional buckling strength factor; Based on the inner diameter, shaft length, and static strength design coefficient of the low-pressure turbine shaft, the key structural parameters and the final static strength design parameters are obtained. The key structural parameters include the outer diameter of the low-pressure turbine shaft. Perform static strength analysis, evaluate the results, and proceed to the next step if the strength design criteria are met. Perform a processability analysis; if the requirements are met, proceed to the next step. Analyze the DN value of the outer bearing of the low-pressure turbine shaft. If it meets the design criteria, complete the assessment of key dynamic characteristics and proceed to the next step. Output the space dimensions of the low-pressure turbine shaft and the final static strength design parameters as inputs for the low-pressure turbine shaft structure design; The overall performance input parameters of the aero-engine include the type of aero-engine, usage method, and flight status. Then, an appropriate overall performance state point and its low-pressure system functional parameters are selected as input parameters for the space boundary layout design. The material parameters of the low-pressure turbine shaft include elastic modulus, Poisson's ratio, and fatigue life; the material parameters of the low-pressure turbine shaft determine the initial weight of the power turbine shaft design. The temperature boundary parameters were obtained through heat transfer analysis; The design of the rapid structural calculation program involves obtaining the inner diameter, shaft length, and initial static strength design coefficient of the low-pressure turbine shaft, and then inputting the obtained strength parameters as input values ​​into the calculation program for iterative calculation to obtain the key structural parameters and final static strength design coefficient of the low-pressure turbine shaft. Through the steps of data calculation, parameter data classification, data storage, and data display, the key structural parameters and final static strength design coefficients of the low-pressure turbine shaft are obtained. After the DN value of the outer bearing of the low-pressure turbine shaft is determined, a dynamic feasibility analysis is performed on the low-pressure turbine shaft. The feasibility of the dynamic scheme is estimated by analyzing the corresponding dynamic control parameters. If it is feasible, the next step is executed; if it is not feasible, the initial values ​​of the inner diameter and the shaft length of the low-pressure turbine shaft are given again, and the calculation is repeated until the requirements are met. During the static strength analysis, if the strength design criteria are not met, the material parameters of the low-pressure turbine shaft are re-assigned for another iterative calculation and determination. If the design requirements are still not met, the initial value of the inner diameter of the low-pressure turbine shaft is re-assigned, and iterative calculation continues until the strength criteria are met. If the machinability requirements cannot be met during the machinability analysis, the initial values ​​of the inner diameter and shaft length of the low-pressure turbine shaft are redefined, and the calculation is repeated iteratively until the machinability criteria are met. During the determination of the DN value of the low-pressure turbine shaft bearing, if the design criteria are not met, the initial values ​​of the inner diameter and shaft length of the low-pressure turbine shaft are redefined, and the calculation is repeated iteratively until the DN value criteria of the bearing are met.

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