Research And Development Of Aeroengine Blade Static Frequency Detection System

Blade is one of the most important parts of an aeroengine,which is subjected to multiple varying loads.When the exciting force frequency is close to the resonance frequency of the blade,the blade will resonate,which will easily lead to the fatigue failure of blade.In order to avoid blade resonance effectively,the resonance frequency of blades need to be checked whether the resonance frequency of the blade meets the requirements before assembly.Therefore,it is necessary to research and develop the blade static frequency detection system.This paper mainly completes the following work:(1)According to the research of finite element dynamics theory,the blade model and simplified models are established,and modal analysis and harmonic response analysis are completed in ANSYS software.It is determined that:the vibration direction of blade tip of first-bend and second-bend,first-tortion and second-tortion is reversed;the tip of air-inlet edge is the best acquisition point of blade vibration signal;the sinusoidal steady-state scanning frequency signal is taken as excitation signal;the resonance frequency can be obtained by looking for the position of the resonance peak.(2)According to the research of CZT algorithm,the programming of multi-step CZT is completed.By comparing CZT with FFT,ZFFT and STFT,it is determined that CZT can obtain the frequency spectrum of arbitrary computational resolution from arbitrary starting frequency,which is more flexible and accurate in short sampling and single frequency signal processing.Multi-step CZT improves the analysis accuracy to a certain extent,and is suitable for vibration signal analysis of blade frequency detection system.(3)Designing the objective,hardware and software framework of blade frequency detection system,three parts of the system are completed:the construction of the hardware system;By analyzing the frequency distribution probability,design and implement the segmented frequency sweep strategy,the simulation shows that the efficiency is increased by 69.27%compared to the sequential sweep.,and complete database compilation;Write the software system,realizing the functions of user system,frequency measurement module and data system.(4)The repetitive frequency measurement test and continuous frequency measurement test on the blade frequency detection system are carried out.The repetitive frequency measurement accuracy level is 0.1,and the maximum reference error of continuous frequency measurement is 0.101%.The results show that the blade frequency detection system has smaller frequency measurement error,better repeatability,higher measurement precision and accuracy,which verifies the feasibility of the system,and improves the frequency measurement efficiency by 57.97%.The optimization of excitation,signal acquisition and analysis of frequency measurement system is discussed.The simulation blade loading analysis with different amplitude ratios is carried out.The results show that the amplitude ratio parameter has certain practical significance in the blade matching.The static blade frequency detection system studied and developed in this paper has perfectly realized the functions from frequency measurement task acquisition to frequency measurement and data management,and carries out frequency measurement test,improving the efficiency of blade frequency measurement.