Method for determining working load environment of aero-engine rotor connecting structure

Abstract

The invention provides a method for determining the working load environment of an aero-engine rotor connection structure, belongs to the field of dynamic analysis and design of aero-engine rotors, and aims at a rotor structure system with a connection structure in an advanced aero-engine to determine the type of a load possibly borne by the connection structure. Based on a rotor finite element model and aerodynamic thermodynamic parameter input of an engine, aerodynamic load analysis, temperature distribution simulation, rotor dynamic characteristic simulation and the like are carried out respectively, and working load amplitudes of a connection structure under different working conditions are obtained. The energy differential method is innovatively adopted to obtain the bending moment at the connecting structure, and the accuracy of bending moment calculation is improved. According to the method, the working load environment of the rotor connection structure can be accurately obtained, accurate load boundary conditions are provided for mechanical property simulation of the rotor connection structure, so that the simulation analysis precision is improved, and meanwhile, reliable data support can be provided for the mechanical property of the connection structure and rotor dynamics optimization design.

Description

Technical Field

[0001] The present invention relates to the field of aero-engine rotor dynamics analysis and design, and particularly to a method for determining the working load environment of an aero-engine rotor connection structure. Background Art

[0002] With the development of aero-engines towards high load and lightweight, on the one hand, the working load environment of the rotor is more severe. The loads that the rotor will receive under working conditions include high rotational speed load of the rotor, high ambient temperature, aerodynamic load, etc.; on the other hand, the rotor mostly adopts lightweight design, which brings a significant decrease in the bending stiffness of the rotor. These two factors together lead to inevitable bending deformation of the rotor under working conditions. And as the main discontinuous point on the rotor, the bending deformation of the rotor will cause problems such as interface slip and fatigue damage at its contact interface. Therefore, in order to effectively suppress the interface contact damage of the connection structure, optimize the mechanical properties of the connection structure and the rotor dynamics characteristics, obtaining the mechanical properties such as stiffness, damping and deformation of the connection structure under working conditions through finite element simulation analysis and mastering the key influencing factors is an efficient and convenient means.

[0003] In order to ensure the accuracy of the simulation results of the mechanical properties of the connection structure, in addition to the accuracy of the finite element model itself, accurate input of load boundary conditions is also a necessary condition to improve the accuracy of the simulation results. However, currently, when performing simulation analysis on the rotor connection structure, there is often a lack of a comprehensive and detailed method for obtaining the working load environment of the connection structure, focusing more on a single factor of rotational speed while ignoring the comprehensive influence of temperature, axial tug-of-war force and bending moment, resulting in the simulation results being difficult to truly reflect the working state of the rotor. In addition, the traditional method for obtaining bending moment is usually based on the direct extraction of nodal forces or sectional moments, which may have problems such as large influence of local stiffness and uneven load distribution leading to calculation errors. Therefore, it is necessary to propose a method for determining the load environment of the rotor connection structure that can truly reflect the working state, provide load boundary inputs such as rotational speed, temperature, aerodynamic load and bending moment for the finite element simulation of the mechanical properties of the rotor connection structure, and while improving the simulation accuracy, provide more accurate data support for subsequent rotor structure design and dynamics analysis. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for determining the working load environment of an aero-engine rotor connection structure, which can organically combine key factors such as rotational speed, aerodynamic load, temperature load and bending moment to accurately obtain the load environment of the connection structure under working conditions.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for determining the working load environment of a rotor connection structure of an aeroengine, comprising the following steps:

[0007] Step 1: Establish a finite element model of the rotor;

[0008] Step 2: Conduct aerodynamic load analysis to obtain the axial tug-of-war force;

[0009] Step 3: Conduct steady-state thermal analysis to obtain the temperature load;

[0010] Step 4: Conduct rotor dynamics analysis to obtain the bending moment;

[0011] Step 5: Form a load environment data set to provide real boundary conditions for subsequent analysis of the mechanical properties of the connection structure.

[0012] Further, the said Step 1 includes:

[0013] According to the structural characteristics of the rotor, construct a solid model of the rotor and conduct mesh division, so as to obtain the finite element model of the rotor.

[0014] Further, the said Step 1 also includes: Based on this finite element model, according to the actual working environment of the rotor, set the corresponding material properties, contact relationships and constraint conditions, laying a model foundation for subsequent loading of aerodynamic load, temperature load and unbalance.

[0015] Further, the said Step 2 includes:

[0016] Based on the aero-thermodynamic design input of the engine and empirical formulas, obtain the aerodynamic force of each stage of blades, the unloading force generated by the pressure difference of each unloading chamber and the axial force at the bearing under a certain working condition, and accumulate them to obtain the axial tug-of-war force acting on the rotor connection structure.

[0017] Further, the said Step 3 includes:

[0018] According to the actual working condition temperature in the engine flow path, obtain the temperature boundary condition at the contact position between the rotor and the main flow path under a certain working condition, and then based on the airflow and air system design, obtain the temperature boundary condition at the contact position between the rotor and the secondary flow path.

[0019] Further, the said Step 5 also includes: Apply a forced convection heat transfer boundary condition to other interfaces, conduct steady-state thermal analysis on the rotor finite element model, so as to obtain the temperature load at local positions of the connection structure.

[0020] Further, the said Step 4 includes:

[0021] According to the unbalance control requirements of each component of the rotor, load the unbalance excitation into the rotor finite element model, establish an analysis model for the dynamic response characteristics of the rotor, and calculate the bending moment of the connection structure under a certain rotational speed working condition.

[0022] Further, step 4 further includes:

[0023] If it is difficult to directly extract the bending moment, the magnitude of the bending moment on the connection structure is deduced by the vibration response, local strain energy, and local stiffness relationship generated by the rotor bending deformation.

[0024] Further, step 5 includes:

[0025] Select several typical working conditions, repeat steps 2 to 4 to obtain the corresponding aerodynamic, temperature, and bending moment parameter points, and use specific interpolation estimation to further obtain the working load environment of the rotor connection structure under different working conditions, forming a load environment data set.

[0026] Further, the typical working conditions include ground idle, in-air idle, and maximum thrust state.

[0027] Further, the specific interpolation can adopt linear interpolation, polynomial interpolation, quadratic interpolation, or other suitable interpolation methods.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. More comprehensive load acquisition. When analyzing the mechanical characteristics of the rotor connection structure of an aeroengine, the present invention not only considers the rotational speed load of the rotor, but also comprehensively considers key factors such as aerodynamic load, temperature load, and bending moment, and can truly reflect the various load environments suffered by the rotor connection structure under the working state. Compared with the prior art that only considers a single rotational speed or local load, the present invention greatly improves the systematicness and accuracy of load input.

[0030] 2. More accurate bending moment calculation. The present invention obtains the bending moment through the relationship between local strain energy and angular displacement, and uses the energy differential calculation method to make the extraction of the bending moment more accurate. It can not only truly reflect the stress state of the connection structure under complex loads, but also effectively avoid the calculation error caused by local stiffness changes, thereby improving the accuracy and applicability of the calculation.

[0031] 3. Improve the simulation accuracy. By accurately applying the corresponding aerodynamic load and temperature field distribution under each rotational speed condition in the rotor finite element model, and considering the influence of the bending moment caused by the rotor bending deformation, the simulation analysis of the rotor connection structure is closer to the actual working state, thereby improving the prediction accuracy of the stress, stiffness, deformation, and fatigue damage of the connection structure, and providing more reliable data support for the optimized design of the rotor connection structure.

[0032] 4. Provide support for structural optimization and dynamic design. Through the load environment dataset established by the present invention, the load boundary conditions under corresponding working conditions can be quickly called in subsequent structural optimization and dynamic analysis, improving the design efficiency and accuracy, and providing reliable technical guarantee for the dynamic design of aero-engine rotors. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic flow chart of a method for determining the working load environment of a rotor connection structure of an aero-engine according to the present invention;

[0034] Figure 2 It is a schematic diagram of a turbine front flange-bolt connection structure of a certain type of aero-engine. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] The present invention aims at a rotor structure system with a connection structure of an advanced aero-engine, uses a rotor finite element model to extract the load environment of the connection structure under full-speed working conditions, and forms a load environment dataset, thereby providing reliable data support for subsequent mechanical characteristics of the connection structure and dynamic optimization design of the rotor.

[0037] As Figure 1 shown, a method for determining the working load environment of a rotor connection structure of an aero-engine according to the present invention includes the following steps:

[0038] Step 1): Establish a rotor finite element model

[0039] According to the structural characteristics of the rotor, construct a solid model of the rotor and perform mesh division to obtain a finite element model of the rotor. Based on this finite element model, set corresponding material properties, contact relationships, and constraint conditions according to the actual working environment of the rotor, laying a model foundation for subsequent loading of aerodynamic loads, temperature loads, and unbalances;

[0040] Step 2): Aerodynamic load analysis and axial tug-of-war force acquisition

[0041] Based on the aero-thermal design input of the engine and empirical formulas, obtain the axial aerodynamic force of each stage of rotor blades under a certain working condition , the axial force generated by the pressure difference in each stage of disk cavities and the axial force at the bearing , where , , respectively represent the number of rotor stages, the number of disk cavity, and the number of bearings generating axial force. Project the above forces vectorially and accumulate them axially to the rotor to obtain the axial tug-of-war force acting on the rotor connection structure :

[0042] ;

[0043] Step 3): Steady-state thermal analysis and temperature load acquisition

[0044] According to the actual working condition temperature in the engine flow path, obtain the temperature boundary condition at the contact position between the rotor and the main flow path under a certain working condition , and then based on the design of the air flow and air system, obtain the temperature boundary condition at the contact position between the rotor and the secondary flow path , where and are coordinate positions. At the same time, apply forced heat transfer boundary conditions to other interfaces (the ambient temperature and heat transfer coefficient are determined according to specific conditions), and perform steady-state thermal analysis on the rotor finite element model to obtain the average temperature load of a certain key connection surface at the local position of the connection structure ;

[0045] Step 4): Rotor dynamics analysis and bending moment acquisition:

[0046] According to the imbalance control requirements of each component of the rotor, load the imbalance excitation into the rotor finite element model, establish an analysis model for the dynamic response characteristics of the rotor, extract the stress and strain distributions of the elements, and integrally calculate the local strain energy at the connection structure :

[0047] ;

[0048] Among them, , are the stress and strain within the element respectively, is the volume.

[0049] At the same time, extract the local rotation angle of a certain key connection surface, and obtain the bending moment by using the relationship between the strain energy and the angular displacement. The relationship between the bending moment and the strain energy can be expressed by energy differentiation. When a certain local cross-section undergoes an angular change around its bending axis, the bending moment can be regarded as the partial derivative of the local strain energy with respect to the rotation angle:

[0050] ;

[0051] Step 5): Form a load environment data set

[0052] Select several typical working conditions, repeat steps 2) to 4) to obtain the corresponding axial tug-of-war forces, average temperature loads, and bending moment parameter points. Using specific interpolation estimation, further obtain the working load environment of the rotor connection structure under different working conditions, and form a load environment dataset to provide real boundary conditions for subsequent analysis of the mechanical properties of the connection structure.

[0053] Example 1

[0054] Step 1): Select a certain type of aero-engine turbine front flange - bolt connection structure, as Figure 2 shown, and establish its finite element model. To reduce the computational effort, a 1 / 24 model is adopted, and the full-scale model is simulated by rotational symmetry. According to the complexity of the rotor connection structure area, the meshes of the contact surface and the key stress concentration areas are appropriately refined to ensure the accuracy of subsequent load application and result analysis.

[0055] Step 2): According to the input of the engine aerodynamic and thermal design, obtain the axial aerodynamic forces on each stage of the compressor and turbine blades at the ground idle speed . To represent the direction of the axial force, the direction pointing to the front of the engine is defined as positive, and the direction pointing to the rear of the engine, i.e., the intake direction, is defined as negative, as shown in Table 1.

[0056] Table 1 Axial aerodynamic forces on each stage of rotor blades at the ground idle speed

[0057]

[0058] Sum up the aerodynamic forces on each stage of rotor blades, and the can be calculated.

[0059] The axial force generated by the pressure difference in each stage of the disk cavity can be calculated by , where is the pressure difference in the th disk cavity, and is the compressed area of the th disk cavity. Table 2 is calculated.

[0060] Table 2 Axial forces generated by the pressure difference in each stage of the disk cavity at the ground idle speed

[0061]

[0062] Sum up the axial forces generated by the pressure difference in each stage of the disk cavity, and can be obtained.

[0063] Since this rotor is supported by a ball bearing and a roller bearing, only one bearing transmits the axial force, and the axial force on the rotor at the bearing is .

[0064] Vectorially superpose the axial forces at the above-mentioned locations to obtain the axial tug-of-war force acting on the rotor connection structure under this rotational speed condition. In the finite element model of the connection structure, this axial tug-of-war force can be simplified into an equivalent force applied at the rotor connection part or the corresponding end face.

[0065] Step 3): According to the temperature boundary conditions at the contact positions between the engine rotor and the main flow path and between the rotor and the secondary flow path under the ground idle speed as well as the temperature boundary conditions at the contact positions between the rotor and the secondary flow path , combining heat transfer mechanisms such as convection, conduction, and radiation, apply thermal boundary conditions to the rotor and the main flow path, secondary flow path, and other heat exchange regions respectively to obtain the temperature distribution of the rotor under this operating condition. In the finite element analysis software, based on the rotor model established in Step 1), select the thermal analysis module, input the thermal conductivity characteristics of the rotor material and the above-mentioned thermal boundary conditions, and after solving, the overall temperature field of the rotor and the steady-state temperature of the local area of the connection structure can be obtained, and then the average temperature load of the sealing labyrinth disc and the turbine disc connection surface of this connection structure can be obtained. .

[0066] Step 4): According to the unbalance control requirements of each component of the rotor, calculate or measure the position and mass eccentricity values of each stage of blades or discs under the ground idle speed, and input them as unbalance excitations into the finite element model to simulate the centrifugal force and unbalance excitations generated during rotor rotation. In the finite element analysis software, switch to the dynamic solution module, set the corresponding rotational speed conditions and consider the influence of the aforementioned aerodynamic loads, temperature loads, etc. on the system stiffness. After solving, extract the stress and strain distributions of the elements, and integrally calculate the local strain energy at the connection structure :

[0067] ;

[0068] Extract the local rotation angle of the connection surface between the sealing labyrinth disc and the turbine disc of the connection structure , and use the relationship between strain energy and angular displacement to obtain the bending moment :

[0069] ;

[0070] Step 5): Select the air idle speed and the rotational speed under the maximum thrust state , repeat the solution of Steps 2) to 4) to obtain the key parameter points such as aerodynamic loads, temperature loads, and bending moments under each operating condition. For the load environment under other non-typical rotational speed conditions, it is obtained by linearly interpolating according to the operating rotational speed:

[0071] Suppose in the rotational speed range There is known load data at the endpoints and , for a certain rotational speed within the interval , then there are:

[0072] ;

[0073] ;

[0074] ;

[0075] Thus, more refined load distribution data of the rotor connection structure is obtained, and a load environment data set is established, as shown in Table 3.

[0076] Table 3 Load Environment Data Set of Turbine Front Flange - Bolt Connection Structure

[0077]

[0078] Subsequently, when performing mechanical property simulations on the rotor connection structure, the load data under the corresponding working conditions can be directly called, which not only improves the analysis efficiency but also ensures the consistency and accuracy of the input conditions.

[0079] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for determining the working load environment of an aircraft engine rotor connection structure, characterized in that: The following steps are involved: Step 1: Establish a rotor finite element model; Step 2: Perform aerodynamic load analysis to obtain the axial tug-of-war force; Step 3: Perform steady-state thermal analysis to obtain temperature loads; Step 4: Perform rotor dynamics analysis to obtain bending moment; Step 5: Form a load environment data set to provide real boundary conditions for subsequent analysis of the mechanical properties of the connection structure.

2. A method for determining the working load environment of an aircraft engine rotor connection structure according to claim 1, characterized in that: The step 1 comprises: According to the structural characteristics of the rotor, a solid model of the rotor is constructed and meshed to obtain a finite element model of the rotor.

3. A method for determining the working load environment of an aircraft engine rotor connection structure according to claim 2, characterized in that: The step 1 also includes: based on the finite element model, according to the actual working environment of the rotor, setting corresponding material properties, contact relationships and constraints to lay a model foundation for subsequent loading of aerodynamic loads, temperature loads and unbalance.

4. The method for determining the working load environment of an aircraft engine rotor connection structure according to claim 1, characterized in that: The step 2 comprises: Based on the engine aerodynamic and thermodynamic design input and empirical formulas, the aerodynamic force of each stage of blades, the unloading force generated by the pressure difference of each unloading cavity and the axial force at the bearing under a certain working condition are obtained and added together to obtain the axial tug-of-war force acting on the rotor connection structure.

5. The method for determining the working load environment of an aircraft engine rotor connection structure according to claim 1, characterized in that: The step 3 comprises: According to the actual operating temperature in the engine flow channel, the temperature boundary conditions of the contact position between the rotor and the main flow channel under a certain operating condition are obtained, and then based on the airflow and air system design, the temperature boundary conditions of the contact position between the rotor and the secondary flow path are obtained.

6. A method for determining the working load environment of an aircraft engine rotor connection structure according to claim 5, characterized in that: The step 5 also includes: applying forced heat exchange boundary conditions to other interfaces, performing steady-state thermal analysis on the rotor finite element model, and thus obtaining the temperature load at the local position of the connection structure.

7. The method for determining the working load environment of an aircraft engine rotor connection structure according to claim 1, characterized in that: The step 4 comprises: According to the unbalance control requirements of each rotor component, the unbalance excitation is loaded into the rotor finite element model, and the rotor dynamic response characteristic analysis model is established to calculate the bending moment of the connection structure under a certain speed condition.

8. A method for determining the working load environment of an aircraft engine rotor connection structure according to claim 7, characterized in that: The step 4 also includes: If it is difficult to directly extract the bending moment, the magnitude of the bending moment of the connection structure can be inferred through the vibration response, local strain energy and local stiffness relationship caused by the rotor bending deformation.

9. The method for determining the working load environment of an aircraft engine rotor connection structure according to claim 1, characterized in that: The step 5 comprises: Select several typical working conditions, repeat steps 2 to 4 to obtain the corresponding aerodynamic, temperature and bending moment parameter points, and use specific interpolation estimation to further obtain the working load environment of the rotor connection structure under different working conditions to form a load environment data set.

10. A method for determining the working load environment of an aircraft engine rotor connection structure according to claim 9, characterized in that: The typical operating conditions include ground slow speed, air slow speed, and maximum thrust state.

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