Simulation test piece design method for verifying acoustic solid coupling of blade disk annular cavity

Abstract

The application provides a simulation test piece design method for verifying acoustic-structure coupling of a blade disc annular cavity, comprising the following steps: exciting the blade disc annular cavity through a sound source to obtain a sound excitation frequency of the blade disc annular cavity; determining key geometric parameters of the simulation test piece; taking the key geometric parameters of the simulation test piece as variables and the sound excitation frequency as a target, and obtaining optimal parameters of the key geometric parameters by making a cavity natural frequency of the simulation test piece substantially equivalent to the sound excitation frequency; establishing a finite element model of disc coupling resonance analysis to obtain a resonance mode of the disc; carrying out traveling wave vibration analysis to determine whether the blade and the disc can be excited to vibrate; carrying out acoustic cavity resonance simulation test to verify the sound excitation frequency, the cavity natural frequency and whether acoustic-structure coupling vibration occurs; if acoustic cavity resonance occurs, the design is ended; if the cavity resonance cannot be excited, the key geometric parameters of the simulation test piece are redesigned, and the above process is repeated.

Description

Technical Field

[0001] This application belongs to the field of aero-engine testing technology, and specifically relates to a design method for a simulation test piece used to verify acoustic-structure coupling in the annular cavity of a blade disk. Background Technology

[0002] With the increasing thrust-to-weight ratio of aero-engines, the internal excitation environment of the compressor becomes increasingly complex, especially for the annular cavity composed of blades and the rotor, which is highly susceptible to acoustic-structure interaction (ASI) vibration. Similar to flow-induced vibration (FIV), when the frequency of the sound source within the cavity approaches the natural frequency of the blade, the blade will undergo forced vibration. Large-amplitude, severe vibration can lead to high-cycle fatigue failure. Particularly for inlet fan rotor blades, noise not only causes significant blade vibration but also generates additional noise, preventing the engine from meeting the noise requirements stipulated in airworthiness regulations. Therefore, it is necessary to conduct ASI analysis of the annular cavity of the blade and rotor during the design phase to ensure that the overall structure of the blade and rotor does not experience large-amplitude vibration and avoid ASI fatigue failure.

[0003] In existing technologies, compressors and fans are usually not designed with consideration for blade vibration problems caused by flow field sound generation, sound propagation, and acoustic-structure interaction. There is also a lack of understanding and research on acoustic cavity resonance and acoustic-induced non-integer vibration. Summary of the Invention

[0004] The purpose of this application is to provide a design method for a simulation test piece for verifying acoustic-structure coupling in annular cavities of blade disks, in order to solve or mitigate at least one of the problems in the background art.

[0005] The technical solution of this application is: a design method for a simulation test piece for verifying acoustic-structure interaction in annular cavities of blade disks, characterized in that the method includes:

[0006] The acoustic excitation frequency of the blade disk annular cavity is obtained by exciting the annular cavity of the blade disk with a sound source.

[0007] Determine the key geometric parameters of the simulated test specimen;

[0008] By taking the key geometric parameters of the simulated test piece as variables and the acoustic excitation frequency as the target, the optimal parameters of the key geometric parameters are obtained by making the natural frequency of the cavity of the simulated test piece basically equivalent to the acoustic excitation frequency.

[0009] A finite element model for disk coupling resonance analysis is established. In this finite element model, the disk and the drum are treated as a whole for modal analysis to obtain the resonance modes of the disk.

[0010] The frequency of the simulated test piece is analyzed. When the simulated test piece rotates, it will generate traveling wave vibration. The forward and backward traveling wave frequencies of the simulated test piece are observed in the stationary coordinate system. By using the noise excitation in the stationary coordinate system and the disk vibration frequency in the rotating coordinate system, traveling wave vibration analysis is carried out to determine whether the blades and disk can be excited to vibrate.

[0011] Conduct acoustic cavity resonance simulation tests on the simulated test piece to verify the acoustic excitation frequency, the natural frequency of the cavity, and whether acoustic-structure coupling vibration occurs. If acoustic cavity resonance occurs, the design ends. If cavity resonance is not excited, the key geometric parameters of the simulated test piece are redesigned, and the above process is repeated.

[0012] Furthermore, the sound source is a point sound source.

[0013] Furthermore, the key geometric parameters include the casing diameter D1, hub diameter D2, hub-to-casing clearance T, cavity depth D, cavity length L, and disc thickness t of the simulated test piece.

[0014] Furthermore, the optimal parameters for obtaining the key geometric parameters satisfy:

[0015] Find: X(D1,D2,D,L,T,t)

[0016]

[0017] In the formula, fA is the acoustic excitation frequency and fB is the natural frequency of the cavity.

[0018] Furthermore, when analyzing the frequency of the simulated test piece, the natural frequencies of the rotating ring considering the influence of centrifugal force are:

[0019]

[0020] In the formula, ω d ω represents the dynamic frequency. s Indicates a static frequency. Ω is the dynamic frequency coefficient, m is the number of pitch diameters, and Ω is the rotation frequency of the wheel.

[0021] Furthermore, observing the forward and backward traveling wave frequencies of the simulated test piece in a stationary coordinate system, the following conditions are met:

[0022] f 静 =f 动 +mΩ

[0023] f 静 =f 动 -mΩ

[0024] In the formula, f 静 f represents the frequency of the stationary coordinate system. 动 This indicates the frequency of the moving coordinate system.

[0025] The acoustic-structure coupling simulation test specimen design method proposed in this application can effectively ensure that noise can excite the vibration of the blade and disk as a whole structure through acoustic excitation analysis, key parameter determination and vibration analysis, thereby simulating the resonance phenomenon of the internal acoustic cavity of the compressor or fan, and providing support for the determination of the failure mechanism of the compressor or fan blade. Attached Figure Description

[0026] 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.

[0027] Figure 1 This is a flowchart of the design method for acoustic-structure coupling simulation test specimens in this application.

[0028] Figure 2 This is a schematic diagram of the key geometric parameters of the simulated test specimen of this application.

[0029] Figure 3 This is a schematic diagram of the assembly of the simulated test piece in this application.

[0030] Figure 4 This is a schematic diagram of the finite element simulation model of the simulated test piece in this application. Detailed Implementation

[0031] 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.

[0032] The purpose of this application is to provide a design method for a simulation test piece for acoustic-structure coupling in the annular cavity of a bladed disk. This simulation test piece can generate acoustic cavity resonance, thereby simulating the impact of internal noise excitation of a compressor or fan on the overall structure of the bladed disk under complex excitation environments.

[0033] like Figure 1 As shown, the simulation test specimen design method for verifying acoustic-structure interaction in the annular cavity of a blade disk provided in this application includes the following steps:

[0034] S1, Sound Excitation Analysis

[0035] The annular cavity (or acoustic cavity) of the blade disk is excited by a sound source to obtain the natural frequency of the acoustic cavity resonance, so as to ensure that the vibration of the simulated test piece can be effectively excited. The sound source used in this application is a point sound source.

[0036] The specific process is as follows: a virtual microphone is placed in the acoustic cavity of the ACTRAN acoustic software. The sound excitation frequency is obtained by analyzing the sound field response curve of the virtual microphone. At the same time, the sound pressure distribution of the entire acoustic cavity is observed to obtain the main acoustic mode distribution of the acoustic cavity.

[0037] S2. Determine key geometric parameters

[0038] Many parameters influence the vibration modes of the simulated test specimen. Since the simulated test specimen is an axisymmetric model, projecting the three-dimensional simulated test specimen can form a... Figure 2 The diagram shows the key geometric parameters, where D1 is the casing diameter, D2 is the hub diameter, T is the clearance, D is the cavity depth, and L is the cavity length. These key geometric parameters have a significant impact on the cavity frequency. Additionally, since the wheel thickness t determines the wheel's mass and stiffness, it also has the greatest impact on the frequency of the simulated test piece; therefore, the wheel thickness t is also included as a key geometric parameter.

[0039] S3, Parametric Intensity Analysis

[0040] Using the key geometric parameters from step 2 as variables and the acoustic excitation frequency from step 1 as the target, optimal parameters are obtained through parametric intensity analysis. These parameters ensure that the cavity frequency of the simulated test piece is approximately equal to the acoustic excitation frequency, thereby guaranteeing that the acoustic excitation can effectively induce vibration in the cavity.

[0041] Find: X(D1,D2,D,L,T,t)

[0042]

[0043] In the formula, fA is the acoustic excitation frequency and fB is the natural frequency of the cavity.

[0044] S4, Disk Coupled Resonance Analysis

[0045] like Figure 3 As shown, during the actual assembly of the model test piece, the two disks are connected by a drum, and the disks and drum are locked together with bolts. The drum has a significant impact on the frequency of the simulated test piece. Therefore, in this application, during the disk coupling resonance analysis, the disks and drum are treated as a whole for modal analysis, and a modal analysis is established as follows: Figure 4 The finite element simulation model shown is used to model a portion of the circumference, such as 1 / 10 of the circumference. Based on the finite element simulation model, disk coupling resonance analysis is carried out to obtain the resonant modes of the disk.

[0046] S5, Traveling Wave Vibration Analysis

[0047] The natural frequency of the simulated test piece is analyzed using the following formula, considering the influence of centrifugal force on the rotating ring:

[0048] In the formula, ω d ω represents the dynamic frequency. s Indicates a static frequency. Ω is the dynamic frequency coefficient, m is the number of pitch diameters, and Ω is the rotation frequency of the wheel.

[0049] When the wheel rotates, it will generate traveling wave vibrations. Observing the frequencies of the traveling waves before and after rotation in a stationary coordinate system, the frequencies are:

[0050] Where f_static represents the frequency of the stationary coordinate system, and f_moving represents the frequency of the moving coordinate system.

[0051] By using noise excitation in the stationary coordinate system and the disk vibration frequency in the rotating coordinate system, traveling wave vibration analysis is conducted to determine whether the blades and disk can be excited to vibrate.

[0052] S6. Test and verify. If the requirements are met, the test ends; otherwise, return to revise the cavity geometry parameters.

[0053] By conducting acoustic cavity resonance simulation tests, the acoustic excitation frequency, the cavity's natural frequency, and whether acoustic-structure coupling vibration occurs are verified. If typical acoustic cavity resonance occurs, the design ends; if cavity resonance is not induced, the simulation disk cavity parameters are redesigned.

[0054] The acoustic-structure coupling simulation test specimen design method proposed in this application can effectively ensure that noise can excite the vibration of the blade and disk as a whole structure through acoustic excitation analysis, key parameter determination and vibration analysis, thereby simulating the resonance phenomenon of the internal acoustic cavity of the compressor or fan, and providing support for the determination of the failure mechanism of the compressor or fan blade.

[0055] 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 design method for a simulation test piece used to verify acoustic-structure interaction in annular cavities of blade disks, characterized in that, The method includes: The acoustic excitation frequency of the blade disk annular cavity is obtained by exciting the annular cavity of the blade disk with a sound source. The key geometric parameters of the simulated test piece are determined, including the casing diameter D1, hub diameter D2, hub-to-casing clearance T, cavity depth D, cavity length L, and disk thickness t. Using the key geometric parameters of the simulated test piece as variables and the acoustic excitation frequency as the target, the optimal parameters of the key geometric parameters are obtained by making the natural frequency of the cavity of the simulated test piece comparable to the acoustic excitation frequency. The optimal parameters satisfy: ； In the formula, fA is the acoustic excitation frequency and fB is the natural frequency of the cavity; A finite element model for disk coupling resonance analysis is established. In this finite element model, the disk and the drum are treated as a whole for modal analysis to obtain the resonance modes of the disk. The frequency of the simulated test piece is analyzed. The simulated test piece will generate traveling wave vibrations when rotating. The natural frequency of the rotating ring considering the influence of centrifugal force is as follows: In the formula, Indicates frequency. Indicates a static frequency. Here, m is the dynamic frequency coefficient, and m is the number of nodal diameters. Given the rotation frequency of the wheel, observe whether the forward and backward traveling wave frequencies of the simulated test piece satisfy the following conditions in a stationary coordinate system: In the formula, f 静 f represents the frequency of the stationary coordinate system. 动 The frequency of the moving coordinate system is used to conduct traveling wave vibration analysis by combining the noise excitation of the stationary coordinate system with the vibration frequency of the wheel in the rotating coordinate system, in order to determine whether the blades and the wheel can be excited to vibrate. Conduct acoustic cavity resonance simulation tests on the simulated test piece to verify the acoustic excitation frequency, the natural frequency of the cavity, and whether acoustic-structure coupling vibration occurs. If acoustic cavity resonance occurs, the design ends; if cavity resonance is not excited, the key geometric parameters of the simulated test piece are redesigned.

2. The design method for a simulation test piece for verifying acoustic-structure coupling in the annular cavity of a blade disk as described in claim 1, characterized in that, The sound source is a point sound source.

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