Investigation On High-Speed Rotating Blade Vibration Monitoring Method

It's a great advantage for blade tip timing vibration measurement technology to simultaneously monitor the vibration of the entire blade.Modern large rotating machinery has the characteristics of high rotating speed and large number of blades.As a key component of energy conversion of large rotating machinery,the occurrence and expansion of cracks on the blades threaten its safe and reliable operation.This paper mainly studied the key technology of the BTT vibration measurement system of high-speed rotating blade.In addition,the location offset discrimination method was used to determine whether there were cracks on the blades.Finally,a set of blade tip timing monitoring and analysis system of high-speed rotating blade based on LabVIEW was developed.The main research work of this paper is as follow:(1)Based on virtual instrument,a set of high-speed rotating blade tip timing vibration measuring system was developed.The system integrated high-speed acquisition,data optimization,data noise reduction,data analysis and auxiliary functions,with a friendly interface and complete functions.At the same time,the effectiveness of the system was verified by simulation experiment,blade condition monitoring experiment and system universality experiment.(2)In view of the characteristics of modern large rotary machinery,such as high speed and large number of blades,etc.,this paper proposed a high-speed data flow management scheme based on dynamic frame value method and high-speed data storage strategy.Finally,the high precision acquisition technology of vibration signals of high-speed rotating blades was realized.The high precision acquisition function of the BTT system was tested by simulation experiment.The results showed that the measuring precision of BTT system for the blade vibration signal is up to 0.01 mm.(3)Considering the practical engineering application,the Online data optimization algorithm and zeroing algorithm were developed respectively,which effectively solved the some problems.(4)In this paper,the location offset discrimination method was used to determine whether there were cracks on the blades.By means of fault implantation method,the cracked blade was implanted on the rotor simulation test bench for sweep experiment to study the vibration characteristics of various modes of blade vibration,generated by cracks at different positions of blades(blade tip and root).The results showed that the location offset discrimination method was more sensitive to the root crack,and the deeper the crack was,the larger the location offset discrimination was.