Research On Blade Vibration Parameter Identification Based On Tip Clearance Corrected Timing Data

As the core component of an aero engine,rotating blades will vibrate due to a variety of complex forces during high-speed rotation.Blade vibration will cause fatigue cracks and even breakage of the blades.Therefore,it is very important to monitor the vibration state of the blade in real time and obtain the vibration parameters of the blade during the rotation process.The tip-timing method only needs to install a few sensors along the stationary casing to realize the full-period monitoring of blade vibration.It is currently the most effective real-time monitoring method for blade vibration.However,the traditional blade tip timing signal processing method does not consider the impact of tip clearance changes on the accuracy of the tip-timing system.A large timing error is introduced in the measurement,which ultimately affects the identification accuracy of blade vibration parameters.In response to this problem,this thesis carried out a research on blade vibration parameter identification based on tip clearance corrected timing data.The main research contents are as follows:(1)Based on the principle of blade tip clearance measurement based on the eddy current method,a static calibration system experimental platform was built.By statically calibrating the experimental data and combining the characteristics of the pulse signal,a method to improve the accuracy of the tip-timing system is proposed.The error of the traditional method and this method when the blade tip clearance changed is compared through the static circumferential calibration curve.(2)Establish a model of the blade tip-timing vibration measurement system.Make the clearance between the tip of the blade and each tip-timing sensor probe different,and perform simulation analysis of the tip-timing vibration measurement system.It is verified that the quadratic curve fitting timing method can effectively reduce the timing error introduced when the blade tip clearance changed compared with the traditional rising edge timing method.Based on the multi-sensor vibration parameter identification algorithm of arbitrary angular distribution,the parameter identification of the timing values measured in the simulation of the two methods is carried out.By comparing with the assumed parameters,it is verified that the timing value measured by the quadratic curve fitting timing method when the blade tip clearance changes still has high parameter identification accuracy.(3)Based on the GUI programming module of MATLAB,the simulation software and experimental software for the identification of synchronous vibration parameters of the constant speed blades are respectively designed to quickly and accurately identify the vibration parameters of the blades.(4)Based on the principle of non-contact measurement of the vibration of the rotating blade,an experimental platform for timing measurement of the tip of the blade was built,and the experimental measurement of the constant speed of the blade disk system was carried out.The experimental data verifies that the quadratic curve fitting timing method can effectively improve the accuracy of the tip-timing system when the tip clearance changed compared to the traditional rising edge timing method.In the 0.4～1.05 mm measurement range,the maximum absolute error of the difference between the timing values obtained by the quadratic curve fitting timing method is 26.0359 us.In the constant-speed blade synchronous vibration parameter identification experiment,the vibration parameters of the NO0 blade were identified when the blade tip clearance changed,and the identification showed that the average value of the vibration amplitude of the NO0 blade was 1.0881 mm.By comparing with the identification results when the blade tip clearance does not change,the errors are0.0036 mm and 0.0017 mm,respectively.The error is extremely small,which verifies that the timing value obtained by the quadratic curve fitting timing method when the blade tip clearance changed can also accurately identify the vibration parameters of the blade.