Dynamic Analysis of Vertical Rotor Mass-Visco Fluid System Enhancing Subsequent Rub

Taking into account the coupling effect of a viscous fluid and a vertical rotor in permanent contact with a fixed stator has proven to be a complex and challenging task in fault diagnosis. In this paper, an isotropic vertical rotor-stator model that take into account the longitudinal, lateral and torsional vibrations in a viscous fluid is analyzed. Fluid resistance forces established based on the 2D model of Navier-Stokes equations are fed into the rotor-stator system resulting in a highly nonlinear fluid-vertical rotor system. Based on the complexity of the governing equations obtained, it was necessary to perform the Wavelet Synchrosqueezed Transform (WST) to extract the rubbing fault in a fluid medium and its oscillating modes. The analysis demonstrated through the time-frequency spectrum that the combined unbalance and rub is the leading cause of parametric resonance. The effect of the viscous fluid around the rotor-stator surface contact point generates viscous drag resistance forces and reduces the fluctuation of the rotor's oscillating frequencies.