Research On Monitoring And Control Method Of Torsional Vibration Of Rotating Machinery

As the application of variable frequency speed control technology on compressors/fans becomes more and more extensive,the problem of torsional resonance caused by harmonics generated by frequency converters is becoming more and more prominent.The monitoring and control of torsional vibration is of great significance for maintaining the safety performance of rotating machinery systems.However,the torsional vibration of the rotating machine is not easily detected.On a conventional torsional vibration measuring instrument,phase demodulation is performed by detecting a pulse sequence signal generated by a gear or an optical encoder connected to a shaft to obtain a torsional vibration.In this paper,the existing equipment for torsional vibration monitoring and control is inconvenient to install in large units,and the non-contact tooth measurement method is limited to the problem that the unit has an equal division mechanism,combined with the hardware and virtual instrument platform for vibration measurement of rotating machinery blades.A rotor torsion vibration measurement and control method and system based on blade tip timing method was designed and developed.Strive to achieve the monitoring and control of the torsional vibration of the shafting while measuring the vibration of the rotating machine blades.The measurement and control system adopts the rapid identification method of torsional vibration fault based on pulse timing counting,and multiplies the difference between the actual arrival time difference of the adjacent blades and the theoretical arrival time difference by the blade tip angular velocity to obtain the real-time torsional vibration angular displacement of the shaft system.This paper mainly studies the theory of torsional vibration of the shaft and the calculation theory of torsional vibration natural frequency,summarizes the general steps of torsional vibration analysis,and sorts out the correct ideas of torsional vibration research to understand the nature of torsional vibration.This paper introduces the finite element model of simplifying the complex rotary mechanical shaft system by simplifying it into shaft unit,concentrated mass unit and coupling unit,and analyzing its structural characteristics and various types of vibration characteristics.The accuracy and feasibility of the torsional vibration measurement method and control system proposed in this paper are verified by simulation and experiment.The pulse timing signal reflected by the compressor impeller blades is measured,and the torsional vibration signal is obtained and the natural frequency of the torsional vibration of the shafting is analyzed.Using the pulse signal of the toothed disc of the torque meter at the coupling to design the solution of the undersampling fault of the sensor,and improve the function of the system to quickly identify the faulty faulty blade,and explain the scalability and versatility of the monitoring system..The system speed control module is used to manufacture constant frequency fluctuations on the high-speed torsion blade test bench to monitor the change of the torsional amplitude value of the experimental unit during the start-stop phase.The main factors affecting the torsional amplitude value are analyzed by changing the speed change rate.The method of reducing the damage of torsional vibration to rotating machinery by controlling the rate of change of rotational speed in actual production is proposed,and the practicability of the system is further illustrated.The research results show that the method and system of rotor torsional vibration measurement and control based on blade tip timing have reliable accuracy and can be used in practical engineering testing,providing a new way for rotational mechanical torsional vibration measurement and control.