Numerical Simulation of ‘Wet’ State Critical Speed of the Wet Submersible Motor Rotor System

The water friction generated by the viscosity of axial cooling water in wet submersible motor could affect the rotor dynamic characteristics, which is applied to rotor outer surface in a prestressed manner. We take an 850QS-3200 type wet submersible motor as the research object. In this work, the internal fluid flow is simulated based on the numerical simulation through ANSYS Fluent software. For studying the quantitative relationship the surface roughness of rotor outer surface, rotor speed and axial cooling water flow rate between stator and rotor. After this, the finite element method is used to get ‘wet’ state critical speed by loading the water friction on the rotor system. Then the quantitative relationship is compared and analyzed between the ‘wet’ and ‘dry’ state critical speed of rotor system. Results show that the rotor rotating speed has a great influence on the ‘wet’ state critical speed, but the water friction upon that is negligible. The simulation analysis is verified through vibration experiment. The results of this study would provide a theoretical basis for the improvement of the rotor system in wet submersible motor.