Study on the vibration characteristic of turbine rotor eccentricity based on FFT

Due to the manufacturing error, the worm deflection and other problems caused by the turbine rotor eccentricity, in the impeller vortex will cause the internal flow field of time pulsation, which leads to the additional flow excitation and noise. In this paper, the simulation of the centripetal turbine in eccentric rate stable condition, effect of rotor eccentricity on the exciting force, and the fast Fourier transform (FFT) and the results are analysed by fluent simulation program. Numerical simulation results show that in steady condition, the centripetal turbine rotor eccentricity will lead to cyclical changes in the exciting force effect on turbine blades, on the X axis and the Y axis direction, the blade is subject to the cycle and amplitude of the force are basically the same with a period of about 12T₂, The force curve is similar to the sine signal, but the signal at the peak of the cycle is more complex, and the fluctuation is obvious, Cycle of about 12T₂. The amplitude is about 10.342. At the peak, the stress change is complicated, and there is obvious fluctuation. The FFT spectrum is shown as four independent frequencies, which are located in 1X, 2X, 3X, 4X, and, where the 3X component has a more pronounced fractional resonance.