Lubrication Characteristics And Dynamics Of Floating Ring Bearing-rotor System

Floating ring bearings are often used in many power machineries because of their good stability and long service life.As a key component of power machinery,the performance of floating ring bearings has a very important impact on the stable operation of the entire power machinery.Taking the floating ring bearing as the object,this thesis studies the static and dynamic characteristics of the floating ring bearing,the influence of the stability and thermal effect on the lubrication performance,and investigates the nonlinear dynamic characteristics of the floating ring bearing-rotor system.The main contents are as follows:1.The static performances of floating ring bearing are analyzed.The lubrication model of oil film of the bearing is established.The PDE toolbox is used to solve the lubrication Reynolds equation of the oil film,and the pressure profile of the oil film are solved.Based on this,the static characteristics of floating ring bearing such as bearing capacity and attitude angle are analyzed,and the change rule with eccentricity is analyzed.2.The dynamic performances and stability of floating ring bearings are analyzed.The partial derivative equation of the inner and outer oil film lubrication equation of the floating ring bearing is derived.Based on solving the dynamic characteristics of the bearing such as stiffness and damping coefficients,the motion equation of the bearing and the characteristic equation of the system are constructed.The stability of the floating ring bearing is distinguished by R-H criterion,and the instability speed,dimensionless critical mass and other parameters are calculated and analyzed.3.The lubrication model of floating ring bearing considering thermal effect is established.The viscosity-temperature equation,the energy equation and the Reynolds equation of the bearing which considering the thermal effect are combined to solve the temperature field distribution of oil film of the bearing and the pressure profile of the oil film under the condition of the thermal effect.The friction power consumption,side leak flow and other characteristics are obtained,which are compared with the results under the isothermal condition.The influence of thermal effect on lubrication characteristics is also analyzed.4.On the basis of nonlinear inner and outer oil film force models and kinetic models of floating ring bearings,the nonlinear dynamic equations of the floating ring bearing-rotor system are established.The dynamic equation of the system is calculated by the Runge-Kutta method.The time series,center trajectories and Poincare mapping of the floating ring and the journal center under different rotation speeds are analyzed.Meanwhile,the effect of the rotation speed on the nonlinear dynamic characteristics of the floating ring bearing-rotor system is investigated.