Detection and quantification of oil whirl instability in a rotor-journal bearing system using a novel dynamic recurrence index

This paper presents a new Dynamic Recurrence Index (DRI) to detect the occurrence and quantify the evolution of oil whirl instability in the rotor-journal bearing system by measuring the dynamical similarity between the normal working condition and unstable operating states of the system. In this method, two signals, one normal operating condition signal as the reference signal and one unstable operating condition signal, are reconstructed into the same phase space before the Cross-Recurrence Plots (CRP) are prepared. Then, the structure of these CRPs is analyzed by applying the Cross-Recurrence Quantification Analysis (CRQA) to estimate the dynamical difference between the normal operating condition and unstable operating states of the rotor-journal bearing system. Finally, those CRQA variables are mapped by Support Vector Data Description (SVDD) into a dynamic recurrence index to monitor the evolution and evaluate the severity degree of the oil whirl instability. The simulation and experimental results show that the CRQA variables and DRI are sensitive to the occurrence of oil whirl instability, and the proposed method is a practical approach to monitoring the oil whirl instability for the rotor-journal bearing system.