Research On Torsional Vibration Measurement Technology Based On Fiber Optic Sensor And Pulse Timing Method

In rotating machinery in various fields,the stable operation of the shafting determines whether the entire equipment can operate safely and reliably.Torsional vibration is common in the various rotating shafting.Unlike bending vibration and axial vibration,its vibration occurs in the direction of rotation.Therefore,torsional vibration is not easy to be detected and identified.The presence of torsional vibration may cause shafting torsional resonance or fatigue damage,which seriously threatens the safe operation of the rotating machinery unit.Research on the measurement method of torsional vibration can improve the ability of the shaft torsional vibration detection,thereby prevent the occurrence of faults.Therefore,it is of great significance.This paper is supported by the university-enterprise cooperation project “Development and Application of Torsional Vibration Measurement System for Wind Tunnel Compressor Shafting System”(No.KY22-2018).In this paper,the related shafting torsional vibration measurement technology is studied by combining fiber optic sensor and pulse timing method,and the technology is applied in practice.The main contents are as follows:(1)The torsional vibration measurement method based on fiber optic sensor and pulse timing method is studied and verified from the two dimensions of theory and experiment.In theory,the principle and possible errors of this kind of torsional vibration measurement method are analyzed,and the corresponding error compensation scheme is presented.For principle errors that cannot be completely eliminated,the application scope of this measurement method in this paper is analyzed.In experiment,a torsional vibration test bench with adjustable amplitude,frequency and rotor inherent characteristics is built.The torsional vibration measurement method is used to test torsional vibration of the test bench rotor,which prove the feasibility of the measurement method.(2)The inherent characteristics of shafting torsional vibration are analyzed from two aspects of experiment and simulation.In the aspect of simulation,combined with the continuous mass model of shafting and finite element analysis method,the modal and harmonic analysis of the rotor is carried out,the natural frequency,mode shape and torsional resonance response are obtained.In the aspect of experiment,the torsional natural frequency and torsional resonance response of the rotor are analyzed by this kind of torsional vibration measurement method,the torsional natural frequency of the rotor is obtained by two test methods.The results of the simulation and experiment are very similar.(3)For the characteristic that the indexing error of this kind of torsional vibration measurement method has too much effect on the data analysis result,a data method based on indexing angle calibration is proposed according to the compensation principle of the indexing error and the time-domain synchronous average theory.This study solve the key problem that the measurement method is applied in practice.For the problem that the torsional vibration data obtained by variable frequency sampling is not convenient for spectrum analysis,a sampling frequency acquisition method in the process of torsional vibration data analysis is proposed.(4)For the practical application of the torsional vibration measurement method based on fiber optic sensor and pulse timing method,related hardware system is built,and software programs for detecting and analyzing torsional vibration are developed based on LabVIEW,then,a complete set of torsional vibration measurement system is established from hardware to software.This system is applied into the actual torsional vibration measurement of the centrifugal compressor spindle,and the relevant torsional vibration information is obtained.