| Sliding bearing,as a supporting component directly,affects the performance of the rotor system.Sliding bearings are fluid-lubricated and have the advantages of low friction,low nergy loss,and reliable operation.They are widely used in large-scale heavy-duty rotating machinery systems.The bearing performance needs to be able to meet the requirements of current rotating machinery working conditions.Therefore,new structures of high-performance sliding bearings are emerging in endlessly,and the performance of the bearing-rotor system is mainly affected by the nonlinearity of the oil film whirl.In order to quickly analyze the nonlinear dynamics of the bearing-rotor system,it is necessary to establish an approximate analytical solution model of the radial sliding bearing.For bearings with circumferential pressure grooves on the bearing lobe,such as elliptical bearings,offset bearings and three-lobe bearings,the corresponding approximate analytical solutions were established respectively under the dynamic π oil film boundary conditions,and nonlinear dynamic characteristics of the system supported by different bearings were researched through simulation.The main research is as follows:(1)For the elliptical radial sliding bearing with circumferential pressure groove on the bearing lobe,based on the circumferential dynamic π oil film boundary conditions and the axial physical boundary conditions,the approximate analytical solution of the oil film pressure distribution of the elliptical bearing was decomposed into the sum of a special solution and a general solution.Respective boundary conditions and solving equations for special solutions and general solutions were established,and the Reynolds equation was quickly solved with the separation variables,and then the pressure in the positive pressure oil film domain was integrated to obtain the nonlinear oil film force of the finite-length elliptic sliding bearing.The accuracy of the analytical solution model was verified by comparing with the numerical solution model with higher accuracy.(2)In this thesis,the influence of eccentric azimuth angle of the rotor and bearing structure parameters(wrap angle,preload,slot width and oil supply pressure)on oil film force was researched according to the approximate analytical solution model.(3)An elliptical sliding bearing-rigid rotor dynamic model was established and made dimensionless.The dynamic equation was solved with numerical integration to research the influence of bearing structure parameters on the systematic dynamic characteristics.According to the simulation results,it was found that the oil supply pressure in the groove and the groove width directly affect the dynamic characteristics of the system,and that when the shaft center whirls,the rotor speed can be changed by changing the oil supply pressure in the bearing circumferential groove.(4)The physical model of the misaligned pad and three-oil wedge bearing is established,and the nonlinear oil film force is solved and substituted into the bearing-rigid rotor dynamic equation.Fourier was applied to analyze the vibration components of the rotor to explore the influence of rotor imbalance,bearing structure parameters,oil supply pressure,etc.on the vortex trajectory of the shaft.(5)The sliding bearing test bench was determined and built according to the requirements.The speed of the test rotor is increased to the required speed through a high-speed gearbox,and the gearbox is tested and inspected.The results show that its vibration and temperature indicators meet the design standards. |
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