Continuous Scanning Laser Doppler Vibrometry And Its Application

Accurate acquisition of the dynamic characteristics of engine and its components is of great importance for the safe and reliable operation of engines.Modal test is an important means to obtain structural dynamic characteristics.Acceleration sensors are often used in traditional modal testing.Due to the contact measurement,limited frequency and additional mass influence,it is difficult to meet the requirement of modal test under light and small structure,high frequency and high temperature.Laser Doppler Vibrometry(LDV)has been widely applied in aeronautics,astronautics and other fields due to its advantages of non-contact vibration measurement,high accuracy,high test efficiency and large test frequency range.Continuous Scanning Laser Doppler Vibrometry(CSLDV),developed in recent years,is an efficient measurement of high measuring point resolution Operational Deflection Shape(ODS)of structure under single frequency excitation through the continuous movement of laser on the structure surface.However,Continuous Scanning Laser Doppler Vibrometry is mostly aimed at plate,beam,disk and fan blades and other geometric structure,difficult to apply to the actual structure.In this paper,the CSLDV testing technique is further studied.In the aspect of excitation mode,the mutil-frequency excitation is introduced into the CSLDV testing,the CSLDV testing method under mutil-frequency excitation is developed and the efficiency of the CSLDV testing is improved.In the aspect of scanning method,the methods of line scanning and surface scanning are improved,and the curve continuous scanning and non-rectangular area continuous scanning testing methods are developed,and the ODS of the engine elbow and the compressor blade is effectively tested.In other applications,the CSLDV testing method is applied to structural modal parameter testing under high temperature environment,and the modal parameters at different temperatures of the blade are effectively obtained,which lays the foundation for the further study of the thermal modal parameters by CSLDV testing.In this paper,the research and technology implementation of CSLDV testing technology has filled gaps in related technologies at home and abroad,expanded the application scope of CSLDV testing technology,and greatly promoted the development of CSLDV testing technology from laboratory research to practical engineering application.