Flow Field And Fluid-structure Coupling Analysis Of Hybrid Journal Bearing Considering Viscous-temperature Effect

With the advancement of the times,science and technology have become more developed.As the basis of science and technology,the mechanical manufacturing industry has a great impact on the development of national eco nomy.Bearings,which constitute an important part of machinery,are also an important part of affecting the processing accuracy.In all kinds of machine tools and other processing machinery,the structure and accuracy of the spindle system is the most basic factor of machine tool processing.The bearing of the supporting parts directly contacted with the main shaft and other journals will significantly affect the accuracy of the Journal movement.In order to ensure the stability and accuracy of the Journal movement,the journal and bearing bush are separated by lubricating oil,so as to achieve the functions of support,shock absorption and pressure reduction.In this paper,three kinds of hydrodynamic and hydrostatic journal bearings with different structures are studied.Two-dimensional and three-dimensional models of hydrodynamic and hydrostatic journal bearings are established to simulate the flow field in Matlab and Fluent respectively.The specific research contents are as follows:Firstly,a two-dimensional hybrid journal bearing model based on Reynolds equation is established,and the flow field is simulated by using Matlab software.The effects of the film cavitation distribution,film pressure and rotational speed on the flow field of hybrid journal bearings are studied.The three-dimensional dynamic and static journal bearing model based on N-S equation is established.Fluent software is used to simulate the three-dimensional pressure and cavitation distribution of hybrid journal bearings,and the flow field trends of hybrid journal bearings under different working conditions are compared.The influence of the change of two-dimensional model and three-dimensional model on the cavitation characteristics is compared and analyzed.The results of N-S equation and R-E equation are basically the same.The oil film pressure calculated by R-E equation has obvious hysteresis,and the peak value is higher than that calculated by N-S equation.Secondly,through the joint simulation of Matlab and Fluent,the oil film thickness equation at the initial position is calculated by considering the instantaneous load as a stable load.The Reynolds equation is solved by finite difference method,and the bearing capacity is obtained.The position and velocity parameters of the journal at the next moment are obtained by Euler method.Finally,the trajectory curve of the journal center and the movement law of the journal center of the hydrodynamic and hydrostatic journal bearing are obtained.Fluent is used to calculate the flow field of hydrodynamic and Hydrostatic Journal bearings,and the change trend of internal flow field is obtained from the beginning of calculation to the stability.Thirdly,the user-defined function module in Fluent is used to correlate the oil film temperature of hybrid journal bearings with the viscosity of lubricating oil,and the oil film temperature field distribution more in line with the actual working conditions is obtained.The calculated results of oil film pressure and load-carrying capacity after considering the effect of viscosity-temperature are greater than those of the same viscosity.The reason for this phenomenon is that the increase of temperature leads to the decrease of viscosity,which reduces friction and power loss.Finally,the results of pressure field and temperature field calculated by fluid are loaded on the coupling surface of bearing bush model through ANSYS Workbench platform.The fluid-solid coupling problem between bearing bush and oil film is calculated,and the stress distribution,deformation and temperature distribution of bearing bush are obtained.The transient changes of stress field and temperature field of bearing bush are studied.