Design Of Resonance Frequency Measurement System For Composite Blades Of Centrifugal Impeller Of Aircraft Engine

Rotor blade is one of the components with high failure rate in aero-engine repairing.When the rotor rotates at high speed,if the forced vibration frequency is close to the natural frequency of blade,the blade will be destroyed by resonance,which will lead to failure or even accident.According to the requirement of measuring the first-order resonance frequency of DF-××centrifugal impeller combination made by the ××××factory of the Chinese People's Liberation Army(PLA),this paper puts forward a method of measuring the vibration signal by hammering method and sound pressure sensor,and designs the hardware and software of this method to form the resonance frequency of thin-walled compact small-sized blades.Test equipment and technology.In this paper,the general method of blade resonance frequency measurement system is analyzed.The traditional mechanical system resonance frequency measurement system is improved from the aspects of blade vibration mode,excitation method,signal picking up method,signal processing method,data storage and reading method.The DF-×× centrifugal impeller combined blade harmonic is proposed.According to the main indexes of the system,the software is divided into three functional modules,which can realize three functions: real-time measurement,data storage,data reading and display,and the implementation process and key technologies of these three functions are introduced one by one.A testing system consisting of a copper hammer,a sound pressure sensor,a preamplifier,a signal conditioner,a data acquisition device and a special measuring software is formed.In addition,the method of measuring resonant frequency and the method of uncertainty analysis for DF-××centrifugal impeller combined blades are introduced in detail,and the typical test results are compared with the results obtained by traditional test methods.The problem of fast measuring resonant frequency of thin-walled compact small-sized blades is effectively solved.This paper mainly completed the following work:1.Summarize the development history and current situation of blade resonance frequency measurement method and measurement system,and put forward the development trend of blade resonance frequency measurement system.2.The main influencing factors of blade resonance frequency measurement are analyzed.From three aspects of blade vibration mode and excitation method,vibration signal picking technology and vibration signal processing technology,the overall framework,technical index,software structure and composition of blade resonance frequency measurement system based on hammering and sound pressure measurement technology are proposed.Modular.3.According to the actual design and development process of the project,the design and implementation of three software modules,real-time measurement,data storage,data reading and display,are introduced.4.After completing the hardware and software design of the measurement system,the method of measuring the resonant frequency of centrifugal impeller combined blade and the method of evaluating the uncertainty of measurement results are put forward.5.Full testing and test verification of the software and hardware of the measurement system,including comparative analysis of the uncertainty of measurement results and measurement results,product installation test,etc.,show that the research project of this subject can prevent the centrifugal impeller assembly of this type of aero-engine from running because the blade vibration characteristics are not satisfactory.Good causes damage and then causes accidents.