Vibration fault identification of a turbojet engine based on cepstrum analysis

Abstract

A vibration fault identification method based on vibration state characteristics of a turbojet engine and cepstrum analysis technology was proposed in this paper, and the application of cepstrum in vibration analysis of an aero-engine was also discussed. The vibration data of the turbojet engine in three different test cases of 0.8 rated state, max power state, and afterburning state were analyzed using the cepstrum analysis method. The periodic components and the characteristics of multi-component side-frequency complex signals in the dense overtone vibration signals were separated and extracted, which reflected the sensitivity of the positions of the compressor casing and the turbine casing to the harmonic vibration components of high- and low-pressure rotors and the characteristic difference of different vibration parts. Thus, effective identification of vibration faults was achieved. The results shows that the cepstrum analysis technique applied to the vibration analysis of the turbojet engine can better identify the sideband components of the frequency domain modulated signal and enhance the recognition capability of the fault frequency component, which is helpful to identify the engine vibration fault quickly and accurately.