Study On Aerodynamic And Mechanical Characteristics Of Double-Mode Gas Bearing For Turbine Engine

The spindle of the turbine engine is prone to collision in the start and stop stage,which leads to abnormal wear of the spindle diameter and bearing wall,and reduces the service life and running stability of the spindle.Because of the low viscosity,no pollution and easy access to gas,traditional bearings are gradually replaced by gas bearings.Gas bearings are mainly divided into static pressure and dynamic pressure.The static pressure gas bearing needs continuous high pressure gas supply and its structure is relatively complex.The dynamic pressure gas bearing has serious wear and poor stability at the start and stop stage,but no high pressure gas source is needed.Dual mode gas bearing has both advantages and disadvantages;In the working process of the turbine engine main shaft,particles caused by insufficient filtration,overload collision,wall shedding and other reasons will produce erosion wear on the wall surface,reduce the service life of the main shaft and affect the bearing capacity of the main shaft.However,the relatively complex structure of the dual-mode gas bearing will increase the collision probability between particles and the wall surface,and increase the erosion wear degree of the main shaft and bearing wall.So the research content of this paper will be mainly carried out from two aspects;First,study on the bearing characteristics of the flow hydrostatic gas bearing with spiral groove and small section;Second,the erosion wear of the main shaft and bearing wall of the flow hydrostatic gas bearing with spiral groove orifice joint.The main research technical routes are as follows;(1)according to the Navier-Stokes equations of fundamental air lubrication,the compressible and precarious Reynolds equations and the countenance of the bearing capacity of radial gas bearings under static pressure with small grooves in spiral grooves were derived by making assumptions about gases and bearings.(2)Catia software was used to establish a three-dimensional spiral groove orifice section flow hydrostatic gas bearing figure,Fluent simulation software and CFD technology were used to directly solve the basic gas lubrication equation Navier-Stokes equation,and the influence of changes in eccentricity,spindle speed,groove distance proportion,groove breadth ratio and groove depth ratio on bearing performance was analyzed.The gas film pressure distribution law under different structural arguments and working parameters was studied.Through the analysis and majorization of the gas film bearing capacity under different structural parameters,the optimized model was obtained.At the same time,the comparison of the models before and after optimization shows that the bearing ability of the optimized model is Significantly higher than that of the primitive model under the equal running environment,but the gas flow under the same operating condition is lower than that of the initial model.(3)Based on the optimized model,considering the impact on the erosion wear rate of the spindle and bearing wall,through the particle erosion model analysis,theoretical summary,force analysis and gas phase dynamics governing equation research,the particle sources of this model were analyzed,the particles suitable for this model were selected,and different erosion model application occasions were sorted out.Select the erosion model suitable for the content of this study.(4)With the help of Fluent simulation software,the selected particle flow was imported into the study model,and the erosion wear trend of bearing wall and the movement of particle flow in the air film gap were analyzed under different intake pressure,spindle speed and particle size.The erosion wear rule of particle flow on the wall under different operating conditions in the study model was obtained.