A numerical simulation method and system for non-synchronous vibration response of a compressor rotor blade

Abstract

The present application relates to the field of gas turbine engine compressor design, and discloses a kind of compressor rotor blade non-synchronous vibration response numerical simulation method and system, obtain the non-synchronous airflow excitation frequency of compressor rotor blade tip and the surface pressure load of blade at different time by CFD full circumference unsteady numerical simulation, obtain the vibration mode and natural frequency of rotor blade by finite element modal simulation, determine non-synchronous vibration mode and natural frequency according to minimum frequency difference;Non-synchronous airflow excitation under the aerodynamic damping of rotor blade is calculated based on dynamic mesh technology, and surface pressure load at different time, aerodynamic damping and the like are applied to harmonic response analysis, obtain the vibration stress and vibration frequency of rotor blade under non-synchronous airflow excitation, complete compressor rotor blade non-synchronous vibration response numerical simulation evaluation.The analysis method of the present application can be used for compressor rotor blade non-synchronous vibration evaluation in the initial design stage of compressor, and has good practical value and broad application prospect.

Description

Technical Field

[0001] This invention relates to the field of compressor design for gas turbine engines, and discloses a numerical simulation method and system for asynchronous vibration response of compressor rotor blades. Background Technology

[0002] Advanced aero-engines place increasingly higher performance demands on compressor components. Lightweight design requirements lead to continuously increasing aerodynamic loads on single compressor stages, necessitating smaller axial spacing between multi-stage compressors to reduce weight. In addition to bearing significant centrifugal forces and the periodic aerodynamic forces generated by upstream and downstream blade wake potential flows, rotor blades also endure alternating aerodynamic loads caused by strong unsteady flows such as tip separation vortices. This results in continuously increasing blade vibration stress, making high-cycle fatigue failure due to flow-induced vibration of rotor blades increasingly prominent. Therefore, to ensure the safe operation of compressor components, blade design must consider a balance of aerodynamic, structural, and strength performance.

[0003] The flow-induced vibration of compressor blades is essentially an aeroelastic process coupled with unstable fluid and blade structure. Common aeroelastic problems in compressor rotor blades mainly include forced vibration and asynchronous vibration. Forced vibration primarily originates from the aerodynamic excitation of the compressor's circumferential changes, such as the periodic unsteady aerodynamic forces generated by the upstream blade wake and the potential flow between blade rows. Its characteristic is that the airflow excitation frequency is an integer multiple of the rotor speed, which can be avoided in engineering by frequency tuning using the resonant speed diagram. Asynchronous vibration mainly originates from the airflow excitation of the unstable circumferential flow at the rotor blade tips. Because the unstable flow itself moves around the rotor circumferentially, its airflow excitation frequency is asynchronous with the rotor speed, exhibiting a non-integer multiple relationship. Furthermore, asynchronous vibration also possesses frequency-locked and phase-locked characteristics, which can generate significant vibration stress, posing a serious threat to the reliability and safety of the rotor blades. Compared to forced vibration, asynchronous vibration is more difficult to predict in engineering because the circumferential unstable airflow excitation frequency cannot be given in advance. Summary of the Invention

[0004] The purpose of this invention is to provide a numerical simulation method and system for the asynchronous vibration response of compressor rotor blades, which can conduct asynchronous vibration assessment of blades during the design process of aero-engine compressors and solve the problem of asynchronous vibration of compressor blades.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0006] A numerical simulation method for the asynchronous vibration response of compressor rotor blades includes:

[0007] Based on the compressor aerodynamic design data and compressor rotor-stator blade shape data, a multi-stage compressor full-circumference unsteady numerical simulation model is established. The unsteady flow field of the compressor rotor blade under asynchronous vibration conditions is obtained by simulation analysis using the unsteady numerical simulation model.

[0008] Data on the change of rotor blade surface pressure load over time and the change of compressor rotor tip pressure fluctuation over time in the unsteady flow field are extracted. The asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip is obtained from the data on the change of compressor rotor tip pressure fluctuation over time using the Fourier transform method.

[0009] Modal analysis of prestressed rotor blades was carried out under asynchronous vibration conditions to obtain the rotor blade mode shape and natural frequencies Fg of each order. The natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades was determined as the mode shape of the asynchronous vibration condition.

[0010] The vibration mode is mapped to the unsteady numerical simulation model in the form of a moving mesh motion, and the aerodynamic damping of the rotor blades under asynchronous vibration conditions is analyzed and obtained.

[0011] Based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, the modal superposition method is used to conduct harmonic response analysis of the rotor blades to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation. In the harmonic response analysis, the data of the change of the pressure load on the rotor blade surface in the unsteady flow field with time is applied to the rotor blade surface in time sequence.

[0012] Furthermore, in the process of analyzing and obtaining the aerodynamic damping of the rotor blades under asynchronous vibration conditions, the compressor outlet back pressure value is consistent with the compressor outlet back pressure obtained by simulation analysis using the unsteady numerical simulation model when the compressor rotor blades are in an unsteady flow field under asynchronous vibration conditions.

[0013] Furthermore, the prestress is the average temperature, average aerodynamic force, and centrifugal force of the rotor blades under asynchronous vibration conditions.

[0014] Furthermore, in the process of conducting harmonic response analysis of rotor blades using the modal superposition method, the frequency range of the harmonic response analysis covers the natural frequency F. g Asynchronous airflow excitation frequency F n The frequency range between.

[0015] To achieve the above technical effects, the present invention also provides a numerical simulation system for the asynchronous vibration response of compressor rotor blades, comprising:

[0016] The simulation analysis module is used to establish a multi-stage compressor full-circumference unsteady numerical simulation model based on the compressor aerodynamic design data and compressor rotor-stator blade modeling data. The unsteady numerical simulation model is used to simulate and analyze the unsteady flow field of the compressor rotor blade under asynchronous vibration conditions.

[0017] The data extraction module is used to extract data on the change of rotor blade surface pressure load over time and the change of compressor rotor tip pressure fluctuation over time in the unsteady flow field, and to obtain the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip in the data on the change of compressor rotor tip pressure fluctuation over time using the Fourier transform method.

[0018] The mode shape analysis module is used to perform modal analysis of prestressed rotor blades under asynchronous vibration conditions, obtain the mode shape and natural frequencies Fg of each order of rotor blades, and determine the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of each order of rotor blades as the mode shape of the asynchronous vibration condition.

[0019] The aerodynamic damping analysis module is used to map the vibration mode into the unsteady numerical simulation model in the form of a moving mesh motion, and to analyze and obtain the aerodynamic damping of the rotor blades under asynchronous vibration conditions.

[0020] The harmonic response analysis module is used to perform harmonic response analysis of the rotor blades based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, using the modal superposition method, to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation; wherein, during the harmonic response analysis, the data of the change of the pressure load on the rotor blade surface in the unsteady flow field over time is applied to the rotor blade surface in chronological order.

[0021] Furthermore, in the process of analyzing the aerodynamic damping of the rotor blades under asynchronous vibration conditions, the compressor outlet back pressure value of the aerodynamic damping analysis module is consistent with the compressor outlet back pressure obtained by simulation analysis using the unsteady numerical simulation model when the compressor rotor blades are in an unsteady flow field under asynchronous vibration conditions.

[0022] Furthermore, the prestress in the vibration mode analysis module is the average temperature, average aerodynamic force, and centrifugal force of the rotor blades under asynchronous vibration conditions.

[0023] Furthermore, in the harmonic response analysis module, the frequency range of the harmonic response analysis covers the natural frequency F. g Asynchronous airflow excitation frequency F n The frequency range between.

[0024] Compared with the prior art, the beneficial effects of this invention are as follows: This invention obtains the asynchronous airflow excitation frequency of the compressor rotor blade tip and the surface pressure load of the blade at different times through full-cycle unsteady numerical simulation; obtains the mode shape and natural frequency of the rotor blade through finite element modal simulation; determines the asynchronous vibration mode shape and natural frequency based on the minimum frequency difference; calculates the aerodynamic damping of the rotor blade under asynchronous airflow excitation based on dynamic mesh technology; applies the surface pressure load and aerodynamic damping at different times to harmonic response analysis; obtains the vibration stress and vibration frequency of the rotor blade under asynchronous airflow excitation; completes the numerical simulation evaluation of the asynchronous vibration response of the compressor rotor blade; and realizes its use in the initial design stage of the compressor for the evaluation of asynchronous vibration of the compressor rotor blade. Attached Figure Description

[0025] Figure 1 This is a flowchart of the numerical simulation method for the asynchronous vibration response of the compressor rotor blades in Example 1 or 2.

[0026] Figure 2 This is a block diagram of the numerical simulation system for the asynchronous vibration response of the compressor rotor blades in Example 1;

[0027] The module includes: 1. Simulation analysis module; 2. Data extraction module; 3. Vibration mode analysis module; 4. Aerodynamic damping analysis module; and 5. Harmonic response analysis module. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0029] Example 1

[0030] See Figure 1 and Figure 2 A numerical simulation method for asynchronous vibration response of compressor rotor blades, comprising:

[0031] Based on the compressor aerodynamic design data and compressor rotor-stator blade shape data, a multi-stage compressor full-circumference unsteady numerical simulation model is established. The unsteady flow field of the compressor rotor blade under asynchronous vibration conditions is obtained by simulation analysis using the unsteady numerical simulation model.

[0032] Data on the change of rotor blade surface pressure load over time and the change of compressor rotor tip pressure fluctuation over time in the unsteady flow field are extracted. The asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip is obtained from the data on the change of compressor rotor tip pressure fluctuation over time using the Fourier transform method.

[0033] Modal analysis of prestressed rotor blades was carried out under asynchronous vibration conditions to obtain the rotor blade mode shape and natural frequencies Fg of each order. The natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades was determined as the mode shape of the asynchronous vibration condition.

[0034] The vibration mode is mapped to the unsteady numerical simulation model in the form of a moving mesh motion, and the aerodynamic damping of the rotor blades under asynchronous vibration conditions is analyzed and obtained.

[0035] Based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, the modal superposition method is used to conduct harmonic response analysis of the rotor blades to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation. In the harmonic response analysis, the data of the change of the pressure load on the rotor blade surface in the unsteady flow field with time is applied to the rotor blade surface in time sequence.

[0036] In this embodiment, the asynchronous airflow excitation frequency at the compressor rotor blade tip and the surface pressure load at different times are obtained through CFD full-cycle unsteady numerical simulation. The mode shapes and natural frequencies of the rotor blades are obtained through finite element modal simulation, and the asynchronous vibration mode shapes and natural frequencies are determined based on the minimum frequency difference. The aerodynamic damping of the rotor blades under asynchronous airflow excitation is calculated using dynamic mesh technology. The surface pressure load and aerodynamic damping at different times are applied to harmonic response analysis to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation, thus completing the numerical simulation evaluation of the asynchronous vibration response of the compressor rotor blades. The analysis method of this embodiment can be used for asynchronous vibration evaluation of compressor rotor blades in the initial design stage of the compressor, and has good practical value and broad application prospects.

[0037] Based on the same inventive concept, this embodiment also provides a numerical simulation system for the asynchronous vibration response of compressor rotor blades, including:

[0038] Simulation analysis module 1 is used to establish a multi-stage compressor full-circumference unsteady numerical simulation model based on compressor aerodynamic design data and compressor rotor-stator blade modeling data, and to use the unsteady numerical simulation model to simulate and analyze the unsteady flow field of compressor rotor blades under asynchronous vibration conditions.

[0039] Data extraction module 2 is used to extract data on the change of rotor blade surface pressure load over time and the change of compressor rotor tip pressure fluctuation over time in the unsteady flow field, and to obtain the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip in the data on the change of compressor rotor tip pressure fluctuation over time using the Fourier transform method.

[0040] The mode shape analysis module 3 is used to perform modal analysis of prestressed rotor blades under asynchronous vibration conditions, obtain the mode shape and natural frequencies Fg of each order of rotor blades, and determine the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of each order of rotor blades as the mode shape of the asynchronous vibration condition.

[0041] Aerodynamic damping analysis module 4 is used to map the vibration mode into the unsteady numerical simulation model in the form of dynamic mesh motion, and analyze and obtain the aerodynamic damping of the rotor blades under asynchronous vibration conditions.

[0042] The harmonic response analysis module 5 is used to perform harmonic response analysis of the rotor blades based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, using the modal superposition method, to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation; wherein, during the harmonic response analysis, the data of the change of the pressure load on the rotor blade surface in the unsteady flow field over time is applied to the rotor blade surface in chronological order.

[0043] Example 2

[0044] See Figure 1 A numerical simulation method for asynchronous vibration response of compressor rotor blades, comprising:

[0045] Step 1: Based on the compressor aerodynamic design data and compressor rotor-stator blade modeling data, establish a multi-stage compressor full-circumference unsteady numerical simulation model, and use the unsteady numerical simulation model to simulate and analyze the unsteady flow field of the compressor rotor blades under asynchronous vibration conditions.

[0046] In this embodiment, a multi-stage compressor full-circumference CFD unsteady numerical simulation model is established using compressor aerodynamic design data and blade shape data. For the working condition of asynchronous vibration of compressor rotor blades, a multi-stage compressor full-circumference CFD unsteady flow field numerical simulation is carried out.

[0047] Step 2: Extract the data on the change of rotor blade surface pressure load over time and the data on the change of compressor rotor tip pressure fluctuation over time in the unsteady flow field, and obtain the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip in the data on the change of compressor rotor tip pressure fluctuation over time using the Fourier transform method.

[0048] In this embodiment, the full-circumference CFD unsteady flow field simulation results in step one are post-processed to extract the rotor blade surface pressure load at different times under the convergence state of the CFD numerical simulation, forming blade surface pressure load files at different times. The total physical time of the pressure load files is not less than 0.05s.

[0049] Data on the variation of rotor tip pressure fluctuations over time under the convergence state of numerical simulation are extracted, and the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip in the relative coordinate system is obtained by using the fast Fourier transform method.

[0050] Step 3: Conduct modal analysis of the prestressed rotor blades under asynchronous vibration conditions to obtain the rotor blade mode shape and natural frequencies Fg of each order. Determine the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades as the mode shape of the asynchronous vibration condition.

[0051] In this embodiment, a finite element model of the compressor rotor blade is established using three-dimensional geometric modeling software. Modal analysis of the prestressed rotor blade is then performed using the finite element software to obtain the rotor blade mode shape and natural frequencies Fg of each order. The prestress is the average temperature, average aerodynamic force, and centrifugal force of the rotor blade under asynchronous vibration conditions.

[0052] The mode shape with the smallest frequency difference between the rotor blade's natural frequency and the asynchronous airflow excitation frequency is determined. The formula for calculating the frequency difference is (Fn-Fg) / Fn×100%. The mode shape with the smallest frequency difference is defined as the asynchronous vibration mode shape.

[0053] Step 4: Map the vibration mode into the unsteady numerical simulation model in the form of a moving mesh motion, and analyze and obtain the aerodynamic damping of the rotor blades under asynchronous vibration conditions.

[0054] In this embodiment, the asynchronous vibration mode can be mapped to the full-circumference CFD unsteady numerical simulation model in step one using the energy method and dynamic mesh technology, and the aerodynamic damping of the rotor blades under asynchronous vibration can be calculated. The compressor outlet back pressure value calculated in step four is consistent with that calculated in step one, thus obtaining the magnitude of the aerodynamic damping of the rotor blades under asynchronous airflow excitation.

[0055] Step 5: Based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, the modal superposition method is used to conduct harmonic response analysis of the rotor blades to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation.

[0056] The rotor blade surface pressure load files generated in step two at different times are applied to the blade surface in chronological order. The aerodynamic damping in step four is applied to the harmonic response analysis. At the same time, the frequency range of the harmonic response analysis is defined to cover the frequency range of the natural frequency Fg and the asynchronous airflow excitation frequency Fn. Through the harmonic response analysis, the vibration stress and vibration frequency of the rotor blade under asynchronous airflow excitation are obtained, and the asynchronous vibration response calculation of the compressor rotor blade is completed.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A numerical simulation method for the asynchronous vibration response of compressor rotor blades, characterized in that, include: Based on the compressor aerodynamic design data and compressor rotor-stator blade shape data, a multi-stage compressor full-circumference unsteady numerical simulation model is established. The unsteady flow field of the compressor rotor blade under asynchronous vibration conditions is obtained by simulation analysis using the unsteady numerical simulation model. Data on the change of rotor blade surface pressure load over time and the change of compressor rotor tip pressure fluctuation over time in the unsteady flow field are extracted. The asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip is obtained from the data on the change of compressor rotor tip pressure fluctuation over time using the Fourier transform method. Modal analysis of prestressed rotor blades was carried out under asynchronous vibration conditions to obtain the rotor blade mode shape and natural frequencies Fg of each order. The natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades was determined as the mode shape of the asynchronous vibration condition. The vibration mode is mapped to the unsteady numerical simulation model in the form of a moving mesh motion, and the aerodynamic damping of the rotor blades under asynchronous vibration conditions is analyzed and obtained. Based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, the modal superposition method is used to conduct harmonic response analysis of the rotor blades to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation. In the harmonic response analysis, the data of the change of the pressure load on the rotor blade surface in the unsteady flow field with time is applied to the rotor blade surface in time sequence.

2. The numerical simulation method for asynchronous vibration response of compressor rotor blades according to claim 1, characterized in that, In the process of analyzing and obtaining the aerodynamic damping of the rotor blades under asynchronous vibration conditions, the compressor outlet back pressure value is consistent with the compressor outlet back pressure obtained by simulation analysis using the unsteady numerical simulation model when the compressor rotor blades are in an unsteady flow field under asynchronous vibration conditions.

3. The numerical simulation method for asynchronous vibration response of compressor rotor blades according to claim 1, characterized in that, The prestress is the average temperature, average aerodynamic force, and centrifugal force of the rotor blades under asynchronous vibration conditions.

4. The numerical simulation method for asynchronous vibration response of compressor rotor blades according to claim 1, characterized in that, In the process of conducting harmonic response analysis of rotor blades using the modal superposition method, the frequency range of the harmonic response analysis covers the natural frequency F. g Asynchronous airflow excitation frequency F n The frequency range between.

5. A numerical simulation system for the asynchronous vibration response of compressor rotor blades, characterized in that, include: The simulation analysis module is used to establish a multi-stage compressor full-circumference unsteady numerical simulation model based on the compressor aerodynamic design data and compressor rotor-stator blade modeling data. The unsteady numerical simulation model is used to simulate and analyze the unsteady flow field of the compressor rotor blade under asynchronous vibration conditions. The data extraction module is used to extract data on the change of rotor blade surface pressure load over time and the change of compressor rotor tip pressure fluctuation over time in the unsteady flow field, and to obtain the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor tip in the data on the change of compressor rotor tip pressure fluctuation over time using the Fourier transform method. The mode shape analysis module is used to perform modal analysis of prestressed rotor blades under asynchronous vibration conditions, obtain the mode shape and natural frequencies Fg of each order of rotor blades, and determine the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of each order of rotor blades as the mode shape of the asynchronous vibration condition. The aerodynamic damping analysis module is used to map the vibration mode into the unsteady numerical simulation model in the form of a moving mesh motion, and to analyze and obtain the aerodynamic damping of the rotor blades under asynchronous vibration conditions. The harmonic response analysis module is used to perform harmonic response analysis of the rotor blades based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, using the modal superposition method, to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation; wherein, during the harmonic response analysis, the data of the change of the pressure load on the rotor blade surface in the unsteady flow field over time is applied to the rotor blade surface in chronological order.

6. The numerical simulation system for asynchronous vibration response of compressor rotor blades according to claim 5, characterized in that, In the process of analyzing the aerodynamic damping of the rotor blades under asynchronous vibration conditions, the aerodynamic damping analysis module ensures that the compressor outlet back pressure value is consistent with the compressor outlet back pressure obtained by simulation analysis using the unsteady numerical simulation model when the compressor rotor blades are in an unsteady flow field under asynchronous vibration conditions.

7. The numerical simulation system for asynchronous vibration response of compressor rotor blades according to claim 5, characterized in that, The prestress in the vibration mode analysis module refers to the average temperature, average aerodynamic force, and centrifugal force of the rotor blades under asynchronous vibration conditions.

8. The numerical simulation system for asynchronous vibration response of compressor rotor blades according to claim 5, characterized in that, In the harmonic response analysis module, the frequency range of the harmonic response analysis covers the natural frequency F. g Asynchronous airflow excitation frequency F n The frequency range between.

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