Influence of Support Shapes on the Efficiency of Bulb Tubular Pumps

摘要

In a multiple-stage centrifugal pump rotor with 3000kW power, the influence of journal bearing stiffness under the critical speeds is studied, which shows great impact of bearing stiffness on critical speeds at certain extent. In the light of above, physical models of the bearings are founded up, taking into consideration the stiffness of oil film and the impact of rotor speed on the stiffness coefficient of bearings at the meanwhile. Since the thickness of oil film changes with rotor speed according to relevant laws, the stiffness of oil filM is calculated in different conditions based on short bearings theory. In addition, a range of natural frequencies are calculated with the help of Ansys software, and the relevant campbell diagram are made as well, thus the critical speed of the rotor is obtained. It shows that when the rotor speed is not high, the stiffness of bearings has great impact on critical speeds of lower steps, while the influence on critical speeds of higher steps is not obvious.