Research On Aero-Engine Blade Tip Clearance Measurement Method Based On Laser Self-Mixing Interference

Turbofan aero-engine is the current mainstream aero-engine.The tip clearance between the top of its rotating blade and the engine casing is one of its most important detection parameters.On-line measurement technology of tip clearance can monitor the reliability of aero-engines.It is of great significance.This article focuses on the related problems in the measurement of aero-engine blade tip clearance,and proposes an aero-engine tip clearance measurement method based on laser self-mixing interference.From the simulation analysis of the aero-engine tip clearance,the laser self-mixing interference research has been carried out on ranging theoretical models,measurement system design,and measurement signal processing.The main research contents are as follows:(1)Based on the fluid-structure coupling numerical analysis method of ANSYS Workbench platform,considering the influence of aerodynamic load,centrifugal load and temperature load,numerically calculate the tip clearance of the high-pressure turbine of aeroengine under the set working conditions,and calculate the numerical value.The calculated results are compared with the results of related papers,and the law of its changes is analyzed.(2)Starting from the modified rate equation model based on L-K and the three-mirror FP cavity model,the characteristics and similarities and differences of the two theoretical models are compared by comparing the power equations and frequency equations of the lasers obtained by the two methods,and deduced based on a theoretical model of laser self-mixing interference distance measurement based on triangular wave current modulation,and a non-parametric calibration method to directly construct the relationship between signal frequency and measurement distance.(3)The design of the laser self-mixing interference system is briefly introduced from the aspects of laser selection,laser drive circuit design,photocurrent detection circuit design,rotor simulation platform,etc.,and combined with actual research work.,Supplementary explanations of related practices are given to some of the content.(4)The simulation analysis is carried out by studying the related methods of IFFT and combining with the numerical modeling method of laser self-mixing interference.Relying on the designed and built laser self-mixing interferometry system,the distance measurement experiment is designed to obtain the laser self-mixing interference signal,and the abovementioned method is used to process the signal.Before the experiment,a distance calibration method based on a linear CCD camera was used to calibrate the distance,and the value read by the spiral micrometer was used as the true value to compare the experimental results,and finally the error of the measurement using this method was obtained.