Rubbing Vibration Response Theoretical Analysis and Experimental Verification for a Double Rotor Support Casing System

Taking double rotor support casing system as the reference, a dynamic model of rub-impact coupled system with considering the coupling of the high and low pressure rotor intermediate bearings, the elastic deformation and motion of the casing. The dynamic response of the modal is solved by using the Newmark-β numerical integration method. The effects of rotational speed, rotor eccentricity and rub-impact stiffness on the dynamic characteristics of the system are analyzed. At the same time rub-impact tests are carried out. The results show that the doubling frequency and combined frequency of the rotor will appear in the spectrum diagram when the rub-impact fault occurs in the high pressure rotor. It can be used as the characteristic signal to judge the occurrence of local rubbing. With the increase of eccentricity and rub-impact stiffness, the rub-impact amplitude response of high pressure rotor becomes more obvious and the degree of rubbing is also getting worse. The attenuation of the transmission process should be considered in the subsequent theoretical modeling process, because the vibration value of the casing become smaller. The results of this study can provide a reference for further exploration of rub-impact fault mechanism and rub fault diagnosis. © 2019 Journal of Mechanical Engineering.