Research of transient rotor dynamic characteristic of magnetic liquid double suspension bearing in double collision state

During the operation of magnetic liquid double suspension bearing(MLDSB),due to rotor resonance,assembly error and other factor,the vibration amplitude of the rotor in resonance state exceeds the original design clearance,resulting in the collision damage between the rotor and the stator,the rotor and the casing.This paper presents a method to simulate the influence of different factors on the dynamic characteristics of 5 degrees of freedom(DOF)rotor based on the dynamic model of MLDSB.Firstly,according to the second Lagrange equation,the dynamic equation of 5 DOF rotor is derived,and the mathematical model is established.Then,based on 5 DOF rotor dynamic equation,the rotor transient dynamic equation under collision state is obtained,and the rotor transient collision dynamic simulation model is established.Finally,the key influencing factors of rotor dynamic characteristics are extracted,and the influence mapping relationship of rotor displacement,axis locus and stress distribution under different factors is simulated by using ANSYS Workbench software.The experimental results show that this method can effectively reflect the influence of various factors on the dynamic characteristics of the rotor.This method can provide theoretical reference for the design and control of MLDSB.

Transient Simulation on Dynamic Response of Liquid Annular Seals

Transient change of the operating parameters has a serious influence on the stability of liquid annular seals.Take the liquid annular seals as a research object,a numerical method based on six-degree-of-freedom(6DOF)to analyze the dynamic response of liquid annular seals under gravity impact load.The variations of the force of liquid seal and pressure as well as the axis trajectory in time history are investigated.The influence of different sealing clearance,different liquid viscosity and different rotor speed is also studied.The results show that the maximum sealing pressure and sealing force of gravity direction will increase greatly in a very short time and then reduce rapidly.When sealing clearance increases,the displacement response amplitudes of axis trajectory,the maximum sealing force of gravity direction and maximum sealing pressure also increase.When liquid viscosity increases,the displacement response amplitudes of axis trajectory,the maximum sealing force of gravity direction and maximum sealing pressure decrease.We also found that different rotor speed has almost no influence on the maximum sealing force of gravity direction and maximum sealing pressure.