Vibrational signature of journal bearing oil starvation considering thermal effects and rotor unbalance variation

The occurrence of multiple faults in rotating machines is commonly observed, making fault diagnosis more challenging. In this work, journal bearing oil starvation and rotor unbalance signatures in the rotor vibrational response have been investigated by means of numerical simulations. A new mass conserving bearing model was developed, including 3D thermal effects and realistic oil injection conditions, then validated with experimental data. Results showed that decreasing bearing inlet oil flowrate, increasing inlet oil temperature or increasing rotor unbalance tend to increase synchronous forward and backward vibration's components in different proportions. Tracking simultaneously those vibration's components and their ratio allow the identification of inlet oil flowrates, inlet oil temperature and unbalance moment, contributing to monitor multiple faults in rotating machinery.