Harmonic Analysis of a Centrifugal Impeller with non-cyclic exciting forces
XIAO Jun1,2 ZHAO Yuanyang1,2 SHU Yue1,2
1. Hefei General Machinery Research Institute, National Key Laboratory of Compressor Technology, Hefei 230031；
2. Hefei General Environmental Control Technology Co., Ltd., Hefei 230031
Abstract：In order to investigate the forced vibration problems of centrifugal impellers subjected to gas excitation in the flow fields, an algorithm to calculate the harmonic responses of impellers under non-cyclic exciting forces is realized using the cyclic model. The cyclic symmetry of structure is considered in the programming. For the spatially periodic inflow conditions, firstly the load vector is constructed according to the phase differences of periodic excitations among the sectors, and then by utilizing the modal shape data of different nodal diameters the harmonic response dynamic equations are established under the modal coordinate system to calculate the displacement response. Finally, the harmonic analyses of a radial impeller under non-cyclic aerodynamic exciting forces are carried out. The displacement response results obtained from the cyclic model agree well with those from the integral model. The responses under the exciting frequencies near two resonance points both show relatively higher amplitudes. All the results manifest the correctness of algorithm and its effectiveness to predict the resonance caused by gas excitation.
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