Study On Torsional Vibration Measurement Of Rotational Machinery's Shafting

In recent decades, several great accidents such as shaft breaking occurred inrotary machinery, especially large-scale generating set, which makes the study oftorsional vibration of shafts or shafting(hereinafter referred to as shafting) of rotarymachinery go deep into development and torsional vibration monitoring is in greatsignificance. At present the study mainly concentrates on the fields of transmissionshafting of large-scale generating set, vehicles and shipping, an array of studies havebeen making such as the study on torsional vibration monitoring, eliminating dangerof torsional vibration, and fatigue life analysis and management among which thetorsional vibration measurement of shafting plays an important role.The torsional vibration measurement of shafting refers to measure thedeformation of arc length (torsional angle) and the angular frequency caused by thealternating angular velocity when the shaft rotates. In various methods for torsionalvibration measurement, the method based on pulse sequence counting principle hasmore advantages of high measurement accuracy and the high ratio of price toperformance, easy application for the engineering.The DK-III type torsional vibration measurement instrument were developedagainst to the shortcoming of DK-IIA, such as low integrated level, poor environmentadaptation, weak interface generality and portability The instrument, designed basedon pulse sequence counting, improves anti-interference capacity by introducing peaksequence detection and trace filtering at part of preceding signal processing, enhancesintegrated level of circuit design and decreases volume and intensifies stability byadopting CPLD large-scale programmable logical device to design counting andmanage logic, reinforces interface generality and portability by employing MCU andUSB interface in data transmission and data control.Measurement Software with PC for analysis and signal processing wereaccomplished by the mixing programming with Visual's Basic and Matlab, based onCOM's package technology, achieving the function of torsional vibration calculation,wave display, data saving, frequency spectrum and power spectrum analysis etc. Inorder to be used in engineering, the remote monitoring and manage software has beenworked out to upload the data of torsional vibration to the remote server.The DK-III torsional vibration measurement instrument was verified bysimulating real measurement environment on a small flexible rotor experiment bench.The free frequency and excitation frequency of a rotor shaft in torsional vibrationwere measured in the experiment and experimental results were compared with thatof measurement in traditional electric level translation circuit and theoreticalcalculation. Experiment results show that the measurement results are closer to that oftheoretical calculation than that of traditional measurement in complicated condition.DK-III torsional vibration measurement instrument can be used to realize high precisemeasurement of torsional vibration of shafting in complicated condition.