Numerical simulation method and system for asynchronous vibration response of rotor blade of gas compressor

Abstract

The invention relates to the field of gas turbine engine gas compressor design, and discloses a gas compressor rotor blade asynchronous vibration response numerical simulation method and system, and the method comprises the steps: obtaining the asynchronous airflow excitation frequency of a gas compressor rotor blade tip and the surface pressure load of a blade at different moments through CFD full-cycle unsteady numerical simulation; the vibration mode and the inherent frequency of the rotor blade are obtained through finite element modal simulation, and the vibration mode and the inherent frequency of asynchronous vibration are determined according to the minimum frequency difference; the aerodynamic damping of the rotor blade under the excitation of the asynchronous airflow is calculated based on a dynamic grid technology, the surface pressure loads, the aerodynamic damping and the like at different moments are applied to harmonic response analysis, the vibration stress and the vibration frequency of the rotor blade under the excitation of the asynchronous airflow are obtained, and the numerical simulation evaluation of the asynchronous vibration response of the rotor blade of the gas compressor is completed. The analysis method can be used for evaluating the asynchronous vibration of the rotor blade of the gas compressor in the initial design stage of the gas compressor, and has good practical value and wide application prospect.

Description

Technical Field

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

[0002] Advanced aircraft engines place increasing demands on the performance of compressor components. Lightweight design requirements are driving up aerodynamic loads on single-stage compressors. To reduce weight, multi-stage compressors employ smaller axial spacing between stages. In addition to withstanding significant centrifugal forces and the periodic aerodynamic forces generated by the wake potential flow from upstream and downstream rows, rotor blades also face alternating aerodynamic loads caused by strong unsteady flows, such as tip vortices. This increases blade vibration stresses, and high-cycle fatigue failures due to flow-induced vibration are becoming increasingly prominent. Therefore, to ensure the safe operation of compressor components, blade design must balance aerodynamic, structural, and strength performance.

[0003] The flow-induced vibration of compressor blades is essentially an aeroelastic process resulting from the coupling of an unstable flow and blade structure. Common aeroelastic problems affecting compressor rotor blades primarily include forced vibration and asynchronous vibration. Forced vibration primarily arises from circumferentially varying aerodynamic excitations in the compressor, such as the periodic, unsteady aerodynamic forces generated by upstream blade wakes and inter-row potential flow. Its characteristic is that the frequency of the airflow excitation is an integer multiple of the rotational frequency, which can be avoided in engineering through frequency modulation of the resonant speed profile. Asynchronous vibration primarily arises from the airflow excitation of unstable circumferential flow around the rotor blade tips. Because the unstable flow itself moves around the rotor circumference, its airflow excitation frequency is asynchronous with the rotational frequency and is a non-integer multiple. Furthermore, asynchronous vibration exhibits frequency-locked and phase-locked characteristics, generating significant vibration stresses and 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 frequency of the circumferentially unstable airflow excitation cannot be determined in advance. Summary of the Invention

[0004] The purpose of the present invention is to provide a numerical simulation method and system for the asynchronous vibration response of compressor rotor blades, which can carry out asynchronous vibration evaluation of blades during the design process of aircraft engine compressors and solve the asynchronous vibration problem of compressor blades.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is: A numerical simulation method for asynchronous vibration response of a compressor rotor blade, comprising: Based on the compressor aerodynamic design data and the compressor rotor and stator blade modeling data, a full-circumference unsteady numerical simulation model of a multi-stage compressor is established, and the unsteady flow field of the compressor rotor blade under the asynchronous vibration condition is obtained by simulation analysis using the unsteady numerical simulation model; Extracting the data of the rotor blade surface pressure load changing with time in the unsteady flow field and the data of the compressor rotor blade tip pressure fluctuation changing with time, and obtaining the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor blade tip from the data of the compressor rotor blade tip pressure fluctuation changing with time by Fourier transform method; Performing modal analysis of a prestressed rotor blade under an asynchronous vibration condition to obtain vibration modes and natural frequencies Fg of the rotor blades, and determining that the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades is the onset vibration mode of the asynchronous vibration condition; Mapping the attack vibration mode to the unsteady numerical simulation model in the form of dynamic mesh motion, and analyzing and obtaining the aerodynamic damping of the rotor blade under the asynchronous vibration condition; Based on the aerodynamic damping of the rotor blade under the asynchronous vibration condition, the modal superposition method is used to carry out the harmonic response analysis of the rotor blade to obtain the vibration stress and vibration frequency of the rotor blade under the excitation of the asynchronous airflow; wherein, during the harmonic response analysis process, the data of the time-varying pressure load on the rotor blade surface in the unsteady flow field is applied to the rotor blade surface in chronological order.

[0006] 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 when the unsteady flow field of the compressor rotor blades under asynchronous vibration conditions is obtained by simulation analysis using the unsteady numerical simulation model.

[0007] Furthermore, the prestress is the average temperature, average aerodynamic force and centrifugal force of the rotor blades under asynchronous vibration conditions.

[0008] Furthermore, in the process of 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 and the asynchronous airflow excitation frequency F n The frequency range between .

[0009] To achieve the above technical effects, the present invention further provides a numerical simulation system for the asynchronous vibration response of compressor rotor blades, comprising: A simulation analysis module is used to establish a full-circumference unsteady numerical simulation model of a multi-stage compressor based on the compressor aerodynamic design data and the compressor rotor and stator blade modeling data, and to obtain the unsteady flow field of the compressor rotor blade under the asynchronous vibration condition by simulation analysis using the unsteady numerical simulation model; a data extraction module for extracting data on the time-varying pressure load on the rotor blade surface and the time-varying pressure fluctuation on the compressor rotor blade tip in the unsteady flow field, and obtaining the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor blade tip from the time-varying pressure fluctuation on the compressor rotor blade tip by a Fourier transform method; An onset vibration mode analysis module is used to perform modal analysis of prestressed rotor blades under asynchronous vibration conditions, obtain the vibration modes and natural frequencies Fg of the rotor blades, and determine that the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades is the onset vibration mode of the asynchronous vibration condition; an aerodynamic damping analysis module, configured to map the attack vibration mode into the unsteady numerical simulation model in the form of a dynamic mesh motion, and analyze and obtain the aerodynamic damping of the rotor blade under the asynchronous vibration condition; A harmonic response analysis module is used to perform harmonic response analysis of the rotor blades using a modal superposition method based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, and obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation; wherein, during the harmonic response analysis process, data on the time-varying pressure load on the rotor blade surface in the unsteady flow field is applied to the rotor blade surface in chronological order.

[0010] 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 simulating and analyzing the unsteady flow field of the compressor rotor blades under asynchronous vibration conditions using the unsteady numerical simulation model.

[0011] Furthermore, the prestress in the attack vibration mode analysis module is the average temperature, average aerodynamic force and centrifugal force of the rotor blade under the asynchronous vibration condition.

[0012] Furthermore, in the harmonic response analysis module, the frequency range of the harmonic response analysis covers the natural frequency F g and the asynchronous airflow excitation frequency F n The frequency range between .

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: the present 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-circle unsteady numerical simulation, obtains the vibration mode and natural frequency of the rotor blade through finite element modal simulation, and determines the asynchronous vibration vibration mode and natural frequency according to the minimum frequency difference; calculates the aerodynamic damping of the rotor blade under asynchronous airflow excitation based on the dynamic grid technology, applies the surface pressure load and aerodynamic damping at different times to the 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 the asynchronous vibration evaluation of the compressor rotor blade in the initial design stage of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Flowchart of the numerical simulation method for the asynchronous vibration response of the compressor rotor blades in Example 1 or 2; Figure 2 This is a structural block diagram of the numerical simulation system for the asynchronous vibration response of the compressor rotor blades in Example 1; Among them, 1. Simulation analysis module; 2. Data extraction module; 3. Vibration mode analysis module; 4. Aerodynamic damping analysis module; 5. Harmonic response analysis module. DETAILED DESCRIPTION

[0015] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0016] Example 1 See also Figure 1 and Figure 2 A numerical simulation method for the asynchronous vibration response of a compressor rotor blade is provided, comprising: Based on the compressor aerodynamic design data and the compressor rotor and stator blade modeling data, a full-circumference unsteady numerical simulation model of a multi-stage compressor is established, and the unsteady flow field of the compressor rotor blade under the asynchronous vibration condition is obtained by simulation analysis using the unsteady numerical simulation model; Extracting the data of the rotor blade surface pressure load changing with time in the unsteady flow field and the data of the compressor rotor blade tip pressure fluctuation changing with time, and obtaining the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor blade tip from the data of the compressor rotor blade tip pressure fluctuation changing with time by Fourier transform method; Performing modal analysis of a prestressed rotor blade under an asynchronous vibration condition to obtain vibration modes and natural frequencies Fg of the rotor blades, and determining that the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades is the onset vibration mode of the asynchronous vibration condition; Mapping the attack vibration mode to the unsteady numerical simulation model in the form of dynamic mesh motion, and analyzing and obtaining the aerodynamic damping of the rotor blade under the asynchronous vibration condition; Based on the aerodynamic damping of the rotor blade under the asynchronous vibration condition, the modal superposition method is used to carry out the harmonic response analysis of the rotor blade to obtain the vibration stress and vibration frequency of the rotor blade under the excitation of the asynchronous airflow; wherein, during the harmonic response analysis process, the data of the time-varying pressure load on the rotor blade surface in the unsteady flow field is applied to the rotor blade surface in chronological order.

[0017] In this embodiment, the frequency of asynchronous airflow excitation at the compressor rotor blade tip and the surface pressure load at different times are obtained through full-cycle CFD unsteady numerical simulation. The vibration modes and natural frequencies of the rotor blades are obtained through finite element modal simulation, and the asynchronous vibration modes and natural frequencies are determined based on the minimum frequency difference. The aerodynamic damping of the rotor blades under asynchronous airflow excitation is calculated based on dynamic mesh technology. The surface pressure load and aerodynamic damping at different times are applied to the harmonic response analysis to obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation, 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 during the initial design stage of the compressor, and has good practical value and broad application prospects.

[0018] Based on the same inventive concept, this embodiment also provides a numerical simulation system for asynchronous vibration response of compressor rotor blades, comprising: Simulation analysis module 1 is used to establish a full-circumference unsteady numerical simulation model of a multi-stage compressor based on compressor aerodynamic design data and compressor rotor and stator blade modeling data, and to obtain the unsteady flow field of the compressor rotor blade under asynchronous vibration conditions by simulation analysis using the unsteady numerical simulation model; Data extraction module 2 is used to extract the data of the rotor blade surface pressure load changing with time in the unsteady flow field and the data of the compressor rotor blade tip pressure fluctuation changing with time, and obtain the asynchronous airflow excitation frequency Fn of the rotor blade tip unstable airflow from the data of the compressor rotor blade tip pressure fluctuation changing with time by Fourier transform method; An attack vibration mode analysis module 3 is used to perform modal analysis of a prestressed rotor blade under an asynchronous vibration condition, obtain the vibration mode of the rotor blade and each order natural frequency Fg, and determine that the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the various order natural frequencies of the rotor blade is the attack vibration mode of the asynchronous vibration condition; an aerodynamic damping analysis module 4, configured to map the attack vibration mode into the unsteady numerical simulation model in the form of a dynamic mesh motion, and analyze and obtain the aerodynamic damping of the rotor blade under the asynchronous vibration condition; The harmonic response analysis module 5 is used to perform harmonic response analysis of the rotor blades using a modal superposition method based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, and obtain the vibration stress and vibration frequency of the rotor blades under the excitation of the asynchronous airflow; wherein, during the harmonic response analysis process, the data of the time-varying pressure load on the rotor blade surface in the unsteady flow field is applied to the rotor blade surface in a chronological order.

[0019] Example 2 See also Figure 1 A numerical simulation method for the asynchronous vibration response of a compressor rotor blade is provided, comprising: Step 1: Based on the compressor aerodynamic design data and the compressor rotor and stator blade modeling data, a full-circumference unsteady numerical simulation model of the multi-stage compressor is established, and the unsteady flow field of the compressor rotor blade under the asynchronous vibration condition is obtained by simulation analysis using the unsteady numerical simulation model; In this embodiment, a full-circle CFD unsteady numerical simulation model of a multi-stage compressor is established based on the compressor aerodynamic design data and blade shaping data. For the working condition where the compressor rotor blades exhibit asynchronous vibration, a full-circle CFD unsteady flow field numerical simulation of the multi-stage compressor is carried out.

[0020] Step 2: extracting the data of the rotor blade surface pressure load changing with time in the unsteady flow field and the data of the compressor rotor blade tip pressure fluctuation changing with time, and obtaining the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor blade tip from the data of the compressor rotor blade tip pressure fluctuation changing with time by Fourier transform method; In this embodiment, the full-circumference CFD unsteady flow field simulation results in step 1 are post-processed to extract the pressure load on the rotor blade surface at different times under the convergence state of the CFD numerical simulation, and form a pressure load file on the blade surface at different times. The total physical time of the pressure load file is not less than 0.05s.

[0021] The data of the rotor blade tip pressure fluctuation over time under the convergence state of numerical simulation is extracted, and the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor blade tip in the relative coordinate system is obtained by the fast Fourier transform method.

[0022] Step 3: Perform modal analysis of the prestressed rotor blade under asynchronous vibration conditions to obtain the vibration mode and natural frequencies Fg of the rotor blades, and determine that the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades is the onset vibration mode of the asynchronous vibration condition; In this embodiment, a finite element model of a compressor rotor blade is established using three-dimensional geometric modeling software, and a modal analysis of the prestressed rotor blade is performed using the finite element software to obtain the vibration mode and the natural frequencies Fg of each order of the rotor blade; wherein the prestress is the average temperature, average aerodynamic force and centrifugal force of the rotor blade under asynchronous vibration conditions.

[0023] Determine the vibration mode with the smallest frequency difference between the rotor blade natural frequency and the asynchronous airflow excitation frequency. The frequency difference calculation formula is (Fn-Fg) / Fn×100%. The vibration mode with the smallest frequency difference is defined as the asynchronous vibration onset vibration mode.

[0024] Step 4: Mapping the attack vibration mode to the unsteady numerical simulation model in the form of dynamic mesh motion, and analyzing and obtaining the aerodynamic damping of the rotor blade under the asynchronous vibration condition; In this embodiment, the asynchronous vibration mode shapes are mapped to the full-cycle CFD unsteady numerical simulation model in step 1 using the energy method and dynamic mesh technology. This allows calculation of the aerodynamic damping of the rotor blades under asynchronous vibration. The compressor outlet backpressure values ​​calculated in step 4 and step 1 are kept consistent, allowing the aerodynamic damping of the rotor blades under asynchronous airflow excitation to be determined.

[0025] Step 5: Based on the aerodynamic damping of the rotor blade under the asynchronous vibration condition, a modal superposition method is used to perform harmonic response analysis of the rotor blade to obtain the vibration stress and vibration frequency of the rotor blade under the asynchronous airflow excitation; The rotor blade surface pressure load files at different times generated in step 2 are applied to the blade surface in chronological order, and the aerodynamic damping in step 4 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 the asynchronous airflow excitation are obtained to complete the asynchronous vibration response calculation of the compressor rotor blade.

[0026] The above are only 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 in the scope of protection of the present invention.

Claims

1. A numerical simulation method for the asynchronous vibration response of a compressor rotor blade, characterized in that: include: Based on the compressor aerodynamic design data and the compressor rotor and stator blade modeling data, a full-circumference unsteady numerical simulation model of a multi-stage compressor is established, and the unsteady flow field of the compressor rotor blade under the asynchronous vibration condition is obtained by simulation analysis using the unsteady numerical simulation model; Extracting the data of the rotor blade surface pressure load changing with time in the unsteady flow field and the data of the compressor rotor blade tip pressure fluctuation changing with time, and obtaining the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor blade tip from the data of the compressor rotor blade tip pressure fluctuation changing with time by Fourier transform method; Performing modal analysis of a prestressed rotor blade under an asynchronous vibration condition to obtain vibration modes and natural frequencies Fg of the rotor blades, and determining that the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades is the onset vibration mode of the asynchronous vibration condition; Mapping the attack vibration mode to the unsteady numerical simulation model in the form of dynamic mesh motion, and analyzing and obtaining the aerodynamic damping of the rotor blade under the asynchronous vibration condition; Based on the aerodynamic damping of the rotor blade under the asynchronous vibration condition, the modal superposition method is used to carry out the harmonic response analysis of the rotor blade to obtain the vibration stress and vibration frequency of the rotor blade under the excitation of the asynchronous airflow; wherein, during the harmonic response analysis process, the data of the time-varying pressure load on the rotor blade surface in the unsteady flow field is applied to the rotor blade surface in chronological order.

2. The numerical simulation method for the asynchronous vibration response of a compressor rotor blade 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 when the unsteady flow field of the compressor rotor blades under asynchronous vibration conditions is obtained by simulation analysis using the unsteady numerical simulation model.

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

5. A numerical simulation system for asynchronous vibration response of compressor rotor blades, characterized in that: include: A simulation analysis module is used to establish a full-circumference unsteady numerical simulation model of a multi-stage compressor based on the compressor aerodynamic design data and the compressor rotor and stator blade modeling data, and to obtain the unsteady flow field of the compressor rotor blade under the asynchronous vibration condition by simulation analysis using the unsteady numerical simulation model; a data extraction module for extracting data on the time-varying pressure load on the rotor blade surface and the time-varying pressure fluctuation on the compressor rotor blade tip in the unsteady flow field, and obtaining the asynchronous airflow excitation frequency Fn of the unstable airflow at the rotor blade tip from the time-varying pressure fluctuation on the compressor rotor blade tip by a Fourier transform method; An onset vibration mode analysis module is used to perform modal analysis of prestressed rotor blades under asynchronous vibration conditions, obtain the vibration modes and natural frequencies Fg of the rotor blades, and determine that the natural frequency with the smallest frequency difference from the asynchronous airflow excitation frequency Fn among the natural frequencies of the rotor blades is the onset vibration mode of the asynchronous vibration condition; an aerodynamic damping analysis module, configured to map the attack vibration mode into the unsteady numerical simulation model in the form of a dynamic mesh motion, and analyze and obtain the aerodynamic damping of the rotor blade under the asynchronous vibration condition; A harmonic response analysis module is used to perform harmonic response analysis of the rotor blades using a modal superposition method based on the aerodynamic damping of the rotor blades under the asynchronous vibration condition, and obtain the vibration stress and vibration frequency of the rotor blades under asynchronous airflow excitation; wherein, during the harmonic response analysis process, data on the time-varying pressure load on the rotor blade surface in the unsteady flow field 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 and obtaining the aerodynamic damping of the rotor blades under asynchronous vibration conditions, the aerodynamic damping analysis module maintains the compressor outlet back pressure value consistent with the compressor outlet back pressure obtained by simulating and analyzing the unsteady flow field of the compressor rotor blades under asynchronous vibration conditions using the unsteady numerical simulation model.

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

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 and the asynchronous airflow excitation frequency F n The frequency range between .

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