Research For No-contact Measurement Method Of Blade Dynamic Stress Based On Tip-timing

Rotating machinery is a key component of modern industrial system,which is widely used in important areas of aviation,electric power,chemicals and so on.Aero-engine has become the focus of scientific research as the core equipment of large aircraft project,meanwhile the compressor and turbine as the key components of power,which determine the airplane high-speed,stable and long flight.The rotor blades has become the main reason for the engine failure due quantity and poor working conditions as the core components.The reason of rotor blade failure in addition to blade instantaneous overload fracture by foreign object impact,the most associated with the dynamic stress of blade vibration producing.The traditional contact strain measurement method is complex by operating and can not be on-line monitoring,which is inconvenience in practical applications.Therefore,the real-time monitoring of dynamic stress of the blade has been very necessary in the development and use of aircraft engines.This paper has solved the key technology of dynamic stress inversion through to the blade modeling analysis.Based on this,a new method for non-contact measurement of rotating blades dynamic stress based on tip-timing vibration technology is proposed.In view of the method proposed in this paper,some related experiments is carried out respectively in mechanical engineering experimental center of tianjin university,high-speed rotating machinery laboratory of zhejiang university,the results show that the method can realize the non-contact measurement of rotating blade dynamic stress.This main work includes:1.A method using finite element modeling analysis to obtain the ratio of blade surface dynamic stress and the tip displacement ratio to inverse blade dynamic stress based on tip-timing is proposed through theoretical derivation.2.A data acquisition card which can meet the requirements of blade tip-timing vibration measurement system is designed and developed,the former system is optimized.3.Finite element method is used to build the model and make analysis on blade,the ratio of blade surface dynamic stress and tip amplitude is obtained for static and rotating conditions,and which is taken as a basis for the dynamic stress inversion.4.The vibration table blade vibration and rotating blade vibration monitoring experiments are designed and conducted,static excitation experiment using strain gauge and laser measure instrument on individual blade and strain amplitude is tested;rotation test installed at the same time tip timing vibration measurement system and a slip ring electric strain gauge measurement system to test.The test results verify that the method presented in this paper.