Research On The Stability Of Multi-leaf Oil-foil Bearing Based On Fitting Nonlinear Oil-film Force

With the development of science and technology, also put forward higherrequirements for bearing, such as high speed, high temperature resistant, longservice life, etc. Under this background, the foil bearing arises. the foil bearing is akind of flexible bearings Which Has Many Advantages, high speed operation, littlevibration, high stability, high temperature resistance, wear resistance, resistance toimpact, etc. At present, a lot of work focused on the study of gas foil bearings,already to the third generation which has excellent dynamic and static characteristics.While few research concentrate on oil lubricated foil bearing, and most researchmainly for the dynamic characteristic parameters of the bearing. The stability ofrotor-Bearing system decides the application of bearing and it’s also the importantbasis for multi-leaf oil lubricated foil bearing design. Therefore, in this article wewill put some study on the nonlinear oil film force of multi-leaf oil lubrication foilbearings, analyze its change rule, get the expression of the oil film force by fitting,then study the stability of rotor-bearing system.In this article, analyzed the geometric characteristics of multi-leaf oillubrication foil bearing, oil film thickness calculation method is given. Using finitedifference method to solve the oil film pressure, applying complex of Simpsonintegral formula to get the oil film force, compared its space distribution to otherleafy type bearing and another foil bearing. Analyzes the reason of the smallnonlinear oil film force degree when eccentricity is small, it’s because the flexibleof foil, which can according to automatically adjust the bearing stiffness of differentoil film pressure, when the eccentricity is not very big, the weak nonlinear oil filmforce distribution appeared.Then more in-depth research put on the oil film force, analyzed the affect to thesteady state oil film force by rotational speed, oil viscosity, and various structuralparameters of multi-leaf oil lubricated foil bearing. Fitting the change rule of oilfilm force with these parameters, the specific expression of the steady state oil filmforce was obtained.Using the finite element method to discrete rotating system, completed therotor-bearing system dynamics modeling. Solutions of the first three order criticalspeed of the rotor system, found that multi-leaf oil lubricated foil bearing rotorsystem of the critical speed of the first two order critical speed is low, and the thirdorder critical speed is high. Studied the damping of multi-leaf oil lubricated foilbearing, fitted the damping and obtained transient oil film force which could be usedin dynamic response calculation. Using the Newmark method to study the stability of multi-leaf oil lubricated foil bearing. Discussed the influence to instabilityrotating speed of rotor system by different structural parameters, could be animportant reference to the design of multiple-leaf oil lubricated foil bearing.Finally, the experimental study of multiple-leaf oil lubricated foil bearingstability performance was taken, accurately measured the first order critical speed ofrotor system. And demonstrated the foil bearing with high speed stability. Thedefects in the test process was summarized and put forward the improvementscheme.