The traditional dynamic characteristic analysis of the multi-stage centrifugal pump rotor system is developed assuming the bearing structural parameters with constant values. However, the manufacturing errors will cause the structural parameters to vary around their nominal values and then affect the dynamic characteristics of the bearing-rotor system. Thus, this paper proposes a method for analyzing the dynamic characteristics of the bearing-rotor system with uncertain bearing structural parameters. First, dynamic characteristic coefficients of the sliding bearing are identified to establish the dynamic model of the rotor system, and its dynamic characteristics are analyzed through finite element simulations. Next, the sliding bearing structural parameters are taken as the variables to establish an optimization model, which is solved by the improved particle swarming optimization algorithm to obtain the extreme critical speed of the rotor system. A case study was carried out on a multi-stage centrifugal pump. The obtained extreme values of the critical speeds were close to those calculated using the multiple samples generated by the Monte Carlo method, indicating that the proposed method can provide accurate variation ranges of critical speeds efficiently and lay a theoretical basis for selecting robust operational speeds and designing the rotor system of the multi-stage centrifugal pump.
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