Research On Pressure Drop Characteristics Of Aerostatic Journal Bearings And Efficient Simulation Methods

Aerostatic journal bearings have the advantages of low frictional resistance,high accuracy,long service life,pollution-free,low energy consumption,high reliability,convenient maintenance,and adaptability to various extreme environments.So they are widely used in multiple fields.Using Fluent software for numerical simulation can systematically analyse the pressure,density,gas flow rate,temperature and other characteristics of the gas film in aerostatic bearings,but it requires complex and time-consuming pre-processing,calculation,and post-processing.To save calculation time,the simplified Reynolds equation is often used to calculate its pressure distribution and load capacity.Although this method is convenient to calculate,the calculation results cannot reflect the pressure drop phenomenon in complex gas film flow fields.Currently,the pressure drop phenomenon can only be accurately obtained through Fluent simulation,resulting in significant errors between the simplified Reynolds equation calculation results and the Fluent calculation results,making it difficult to truly apply in engineering practice.To address the above issues,this study establishes a dual row five orifice aerostatic journal bearing model for analysis.The finite difference method is used to simplify the Reynolds equation into a first-order linear form for calculate it and simulate it with Fluent.By studying the changes in the gas film flow field in aerostatic bearings,it was found that the occurrence of pressure drop is related to vortices and shock waves in the gas film.The vortices and shock waves generated by the gas flow near the outlet of the orifices will reduce the pressure of the convective field to a certain extent,and an increase in the supply pressure will increase the incident energy of the shock waves.The degree of pressure drop will increase as the supply pressure and gas film thickness increase.Thus,two different methods can be used to correct the Reynolds equation: density as the independent variable and supply pressure as the independent variable.Based on the pressure contour maps,density contour maps and pressure change curve maps at characteristic points near the orifice at different positions of the aerostatic journal bearing under the condition of different eccentricity,certain functional relations are found that between the gas film pressure and density,as well as between the gas film pressure and the supply pressure,and then the correction formula of the pressure drop area is constructed.The corrected simplified Reynolds equation can quickly obtain the pressure distribution curve of the aerostatic bearing,which can clearly reflect the pressure drop phenomenon,and also can obtain a more practical load capacity situation.Compared with the Fluent numerical simulation,which requires more time and energy,using the Reynolds correction equation proposed in this study is more convenient for modeling,has shorter calculation time,and subsequent data processing is more simply.It can easily and quickly obtain similar pressure distribution curves,and the calculation results have the error does not exceed 5% compare with the Fluent calculation results.Therefore,the Reynolds correction equation proposed in this study has significant computational advantages and can provide a theoretical basis for simplified engineering calculations of the pressure distribution and bearing load capacity characteristics of aerostatic journal bearings under large supply pressure and thick gas film conditions.