Study of coast-up vibration response for rub detection

Early detection of the rub malfunction is essential to avoid damage it might bring to the rotating machines. The coast-up lateral vibration response of the rotor–stator rub is investigated in present study. Rub detection at its initiation stage is attempted for the first time. Shift in resonance speed and the directional nature of the rub fault are observed. Potential of Hilbert–Huang transform over wavelet transform is examined. Appearance of the sub-synchronous frequencies in HHS is suggested for early rub detection.