Research On The Vibration Characteristics Of Rubbing Rotor

Rotor-to-stationary element rub is a serious malfunction in turbo-generator machinery that may lead to catastrophe failure during operation. It is an important nonlinear transient rotordynamic problem discussed widely in the nearly years.Based on the former researches, the Jeffcott rotor system with mass eccentricity is analyzed in this paper. The friction force and angular moment of the rotor is characterized by Coulomb model. And the differential equations for rubbing rotor are established. Numerical analysis for rubbing characteristics is processed with the standard four-step Runge-kutta method. The influences of parameters, such as rotating velocity, mass eccentricity, and clearance on rubbing, are discussed thoroughly. Then it can be concluded that from the beginning of rotor rubbing, fraction and multiple frequencies of rubbing vibration always appear concomitantly. As the speed is low, multiple frequencies are the main component. With the speed increasing, multiple frequencies decrease and fraction frequencies increase. Moreover the amplitude of fraction frequencies always varied from low to high, then to low. Another conclusion is that the influences from mass eccentricity and clearance on rubbing are distinct. The larger mass eccentricity or smaller clearance the rotor has, the more complexly the rotor motion behaves. Based on above modeling of rub, Multi-DOF rotor systems are discussed. The rotor-bearing system is well modularized. Then the differential equations for rubbing multi-DOF rotor systems are established with the finite element method. And the rubbing on rotor dynamics of a 200MW unit is calculated and some useful results are achieved. Lastly all of the calculation results are validated with a test rig based on Jeffcott rotor model.