Influence of rotating speed on the coupled bending and torsional vibrations of turbo-generator unit with rub-impact

Rub-impact fault causes complicated vibration to the rotor system and is one of the main reasons for the system instability. The increment transfer matrix method is used to analyze the dynamic response of the coupled bending and torsional vibrations of turbo-generator shafts with rub-impact in this work. Aimed at a turbo-generator unit with different rotating speed, the vibration character of rub-impact fault is analyzed. The research results show that the influence of rotating speed on vibration amplitude is obvious. When the speed is lower than the first order inherent frequency, rubbing will cause bending and torsional vibration amplitudes of each shaft segment increase largely. When the speed is higher than the first order inherent frequency, vibration amplitudes slightly change by rubbing. The sensitive to rubbing position is different for increased vibration amplitude of each shaft segment. The shaft segment is more near to the rubbing position, the increased vibration amplitude is more obvious.