The Study On Elastohydrodynamic Lubrication Of Hole-entry Water-lubricated Hybrid Journal Bearing

Compared with the traditional lubricating medium,the environmental friendly water lubricating medium has a great difference between physical and chemical properties.The bearing capacity is low and it was easy to burn the bush during starting and the braking process when water is used as a bearing lubricating medium.This paper coupled hydrostatic and hydrodynamic hybrid lubrication and load capacity mechanism.The infinite Elastohydrodynamic Lubrication(EHL)theory model of hole-entry water-lubricated hybrid journal bearing was built.The EHL problems of water-lubricated journal bearing under hybrid lubrication condition were investigated.The fluctuation of water supply pressure,the control of maximum temperature in lubricating contact zone,the change of environmental temperature and the contamination of lubricant of water-lubricated hybrid journal bearing were discussed respectively.Firstly,the dynamic and hydrostatic cooperative lubrication model and the EHL model of the water-lubricated journal bearing were established,the static pressure support,which comes from the throttle device,for the hole-entry water-lubricated hybrid journal bearing was taken into account.The effects of water supply pressure on the hole-entry water-lubricated hybrid journal bearings under isothermal condition were studied.The effects of different forms of water supply pressure fluctuation which due to the instability of the throttle device on the film pressure and film thickness of the bearing contact zone were compared.The influence of speed and load on EHL under the fluctuating of water supply pressure was analyzed.The control criteria of pressure fluctuation under different working conditions were obtained.Secondly,the EHL model of hole-entry water-lubricated hybrid journal bearing was established by using the Reynolds equation with thermal effects.Different velocity and load numerical combinations have been studied when the local maximum temperature of lubricant reaches a critical value under certain water pressure,and the critical temperature curves of the above velocity and load were plotted.The influences of lubricant medium,bearing material and the variation of water pressure on the critical temperature curve were analyzed.Thirdly,variations in operating environment temperature of hole-entry water-lubricated hybrid journal bearings were considered,and the EHL model of bearing contact area was established considering the variation of external temperature environment temperature.Based on the control of the temperature boundary of the contact area,the influence of the ambient temperature on the temperature field of the contact zone is studied by using the multi-grid algorithm to simulate the actual bearing conditions such as season,region and external cooling.Then,the EHL model of the contaminated lubrication system of the hole-entry water-lubricated hybrid journal bearing was established considering the actual situation of lubricant contamination under extreme conditions.The effect of couple stress caused by pollutant was analyzed;the variation mechanism of fluid dynamic pressure at high speed centrifugation was discussed;the influence of velocity parameters on the viscosity of contaminated lubricant was studiedFinally,the contamination of lubricant in centrifugal bearing was simulated in the extreme high speed condition,and the EHL model of centrifugal attachment of pollutant was established.The influence of centrifugal attachment of contaminants on the surface texture of the bearing bush and the change of the pressure film thickness in the contact zone were studied;the influence of the clogging of the water inlet on the film pressure and film thickness in the contact zone was analyzed;the influence of pollutant attachment layer on temperature field in contact zone was investigated.