The Research On Characteristics Of Lubricating Oil And Sliding Bearing Flow Fied

In the large overload rotating machinery,the sliding bearing lubricated by oil has been widely used,which attributes to its heavy bearing capacity,good stability,long working life.The flow characteristics of lubricating oil existing in the bearing clearance directly affect the performance of the equipment,and determine the macro-properties of bearing including the bearing load of sliding bearing,temperature distribution and friction power consumption.In order to study the flow field characteristic of the sliding bearing,the dissertation uses the Reynolds equation to study the flow field characteristics in the positive pressure area of sliding bearing,and uses the CFD technology to study the flow field characteristics in the cavitation area of sliding bearing,which combines experiment and theory on the basis of lubricating oil physical property experimental research.Through the experiment research of viscosity-temperature characteristics and gas content of lubrication oil,it is achieved that the viscosity-temperature fitting formula of 32 turbine oil and the experimental method used to measure the gas content in oil.Then,the qualitative analysis of the two properties of oil is conducted.On the basis of hydrodynamic pressure lubrication theory,the numerical solution model of sliding bearing based on the generalized Reynolds equation is achieved,which combines the Reynolds equation considering viscosity change of oil and the finite difference numerical method.The numerical solution model is translated into programming language by means of the MATLAB.According to the related experimental data and viscosity-temperature formula,the influence of the temperature field on the static flow field characteristics is analyzed under different working conditions.It is found that the solution model which neglects the change of the circumferential temperature will bring some calculation error.Using the numerical solution of the Reynolds equation to analyze the working conditions of the fixed load and fixed speed,the results show that:in the fixed load,with the increase of the rotational speed,the relative increase of the horizontal component of the oil film force becomes larger,the rotor position is shifted,the eccentricity decreased,the offset angle increased,and the maximum oil film pressure decreased;in the fixed speed,with the increase of the load,the relative increase of the vertical component of the oil film force becomes larger,the rotor position sinks,the eccentricity increased,the offset angle decreased,and the maximum oil film pressure increased.A CFD fully mechanized cavitation model for sliding bearings is proposed based on the two-phase flow model and cavitation model of CFD.It is studied that the influence of lubrication oil physical properties and the operation condition on cavitation flow field.The related results show that:a critical region exists in the influent of non-condensable gas content on cavitation effect in which the total cavitation area and the maximum local gas ratio are lower than those in the local area.What's more,the results show that the larger oil supply pressure can weaken the cavitation effect.