| Bump foil gas thrust bearings are often used in turbomachinery,such as air compressors,turbochargers,and gas turbines.With the high speed requirements of modern rotating machinery,thrust bearings often need to withstand greater axial loads.Long-term working will cause temperature accumulation and make the bearings in an extreme working environment.The previous bearing calculation models often ignore the influence of temperature on the running state of the bearing.However,for thrust bearings working at high speeds and heavy loads,temperature has become a factor that cannot be ignored in the bearing design process,so bearing design requires more accurate theoretical calculations model.Establish the 2D thin-plate element finite element model of the top foil and a spring model with a certain stiffness of bump foil.In the calculation process,the top foil and the bump foil together constitute the structural stiffness of the bearing.Thus,the gas film thickness equation considering the elastic deformation of the top foil is obtained.Secondly,a complete fluid thermodynamic model(THD)of the bearing system is established,including various subunit models,the energy transfer model in the lubricating gas film,the convection and heat transfer model of the foil structure,the one-dimensional radial heat conduction model of the thrust plate,and the inlet Zone gas mixing model,and the corresponding sub-model energy transfer equation is discretely solved,and the gas film three-dimensional temperature distribution is obtained.The gas viscosity is updated according to the calculated temperature conditions,and the film thickness is updated by considering the thermal expansion of the foil structure.Combine the non-isothermal Reynolds equation and the gas film three-dimensional energy transfer equation to solve the problem,and Calculate the final convergent three-dimensional temperature and gas film pressure distribution,.The temperature distribution law of the bearing is shown by calculation.Analyze the relationship between the bearing temperature and the change of the load and the speed,and consider the change trend of the cooling gas flow rate on the bearing temperature.The static characteristics of the bearing under the isothermal model and the THD model are compared and analyzed,and the influence of the bearing structure parameters on the static characteristics of the bearing is studied,including the initial minimum air film thickness,slope height,pitch ratio,and the number of sector tiles,which provide information for bearing structure design.Finally,the influence of the inclination of the thrust plate on the temperature and pressure distribution on each sector tile is studied.Designed and built the thrust bearing test bench,and carried out static loading and unloading experiments and rotor operation experiments under different operating conditions on the experimental bearings.The bearing axial displacement,friction torque,and top foil temperature distribution under different speeds and loads are analyzed,and the experimental conclusions are compared with the simulation results to verify the rationality of the calculation model. |
