Abstract: The frequency characteristics of aerodynamic load and the resonance of compressor impeller are studied for the fatigue failure of compressor impeller. The frequency, amplitude and phase of aerodynamic load are obtained from the unsteady computational fluid dynamics(CFD) results of compressor impeller using fast Fourier transform(FFT). The aerodynamic excitation phase between adjacent blades is analyzed in detail. For typical load with cyclic symmetric distribution of phase difference between adjacent blades, the interference diagram is used to determine the resonance modal. For non-typical load with non-cyclic symmetric distribution of phase difference, the resonance modal is determined by the result of dynamic stress in all nodal diameters under aerodynamic excitation frequency. Fatigue analysis is performed based on the static stress and resonance dynamic stress of impeller, which shows that the predicted fatigue position matches with the actual crack position. The zero nodal diameter resonance excited by non-typical fluid load with non-cyclic symmetric distribution of phase difference is proved to be the main cause of impeller fatigue failure.

Key words: fatigue, fluid excitation, impeller, phase, resonance