In order to optimize the matching of impeller with extra-thick blades and volute in a centri-fugal pump, the structure displacement, equivalent stress and modes of different volutes were simulated by one-way coupling Fuild-Structure Interaction method. The ratio between basic circle diameter of volute and impeller diameter(D3/D2)is the main impact on the dynamic characteristics of volute, so it was chosen to design the simulation. When D3/D2 is small(case A), the un-uniform velocity distribution induced by jet-wake in blade outlet leads to the strong pressure pulsation and vibration of volute. However, dynamic parameters are weakened and tend to be stable when the ratio D3/D2 gradually increases(case B,C). Under the design conditions, the maximum displacement in case A is 544 μm, and the maximum equivalent stress is 15.7 MPa. In case B and C, the maximum displacement is reduced to 2.6%, 2.8% of case A, respectively, and the maximum equivalent stress is reduced to 14.8%, 22.9%, respectively. The numerical results of the three cases show that case A and B have similar dynamic characteristics, while case B is more stable. Consequently, it is recommended that, D3/D2 should be plausible around 1.13,which is chosen in case B, in designing a volute of centrifugal pumps with extra thick blades, for a good dynamic characteristics.
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