Application of empirical mode decomposition method to friction fault diagnosis for gas turbo

A combined fault diagnosis method based on Empirical Mode Decomposition (EMD) method and traditional signal processing technique was proposed. With this method, the original signal was decomposed into several Intrinsic Mode Functions (IMFs) with EMD, the instantaneous frequency of each IMF was obtained with Hilbert transform, and the spectrum of the instantaneous frequency was accordingly calculated with Fast Fourier Transform (FFT), where the spectrum represented the modulation frequency of corresponding IMF; the EMD-based orbit was formed with corresponding IMFs, and it exactly expressed the running condition of axis. The proposed method was applied to friction fault diagnosis for gas turbo in an oil refinery. The characters of friction fault signals, such as colored noise, modulation of operating frequency IMF and reversal of EMD-based orbit were found. The results show that the proposed method is effective in friction fault diagnosis for rotating equipment.