Study on critical speed of rotation in the multistage high speed centrifugal pumps rotors

Abstract

Apart from hydraulic performance, the critical rotate speed in wet operating condition (the liquid lubricant state) is an important parameter in the designing of the multistage high speed centrifugal pumps rotors. In this paper, the finite element dynamic model of the rotor in dry state (without lubricate) is analysed by the lubricant fluid applied to the disk and cylinder parts, and a resistance equation of the influence of the fluid is proposed based on the analysis. This resistance is then coupled into the dry state finite element dynamic model to obtain that of the wet state, which is considered as the fluid-solid coupled interaction. With this model, the study further studies the influence of several factors on the inherent frequency of the rotor, and simulates the bending and torsion formation of the physical model. Simulation results show that, when the fluid's influence is considered, the inherent frequency of the rotor is very different from that of the dry state, and hence this influence cannot be neglected in the designing of the rotor. These results are also verified by corresponding experiments.

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