Study On Lubrication Characteristics Of Water Lubricated Bearing Based On Double Deformation Of Shaft And Bearing

At present,the lining of water-lubricated bearings is mostly made of soft materials,which will deform under the action of water film pressure.This deformation of the lining will affect the distribution of the lubricating water film,which in turn affects the lubricating characteristics of the water-lubricated bearing.The lining material of the water-lubricated bearing studied in this paper is Thordon,which is prone to deformation under the influence of water film pressure.It is necessary to consider the influence of the deformation of the bearing lining on the lubrication characteristics of the water-lubricated bearing.In addition,in the ship shafting,due to the cantilever action of the propeller,the stern shaft is often in a bent state,so that the axis at the stern bearing journal is not parallel or inclined to the centerline of the bearing hole,but in a bent state.The bending of the axis will affect the distribution of the lubricating water film,which will affect the solution of the lubricating performance of the water-lubricated bearing.Therefore,the influence of the double deformation of shaft and bearing on the lubrication characteristics of water lubricated bearing is comprehensively considered,so as to obtain the lubrication characteristics of water lubricated bearing more in line with the actual situation.The main research contents are as follows:(1)The finite element alignment calculation of the shafting is carried out,and the deflection of the shafting under different propeller loads is studied.The results show that for the whole shafting,the deformation mainly occurs at the tail shaft,and the propeller load has relatively little effect on the intermediate shaft and thrust shafts.(2)Based on the shafting deflection curve obtained by the alignment calculation,the water film thickness equation considering the shaft bending is deduced,and a three-dimensional water film model considering the shaft bending is established.The interaction between the three-dimensional water film model considering the shaft bending and the bearing lining is studied by using the bidirectional fluid-structure coupling technology,and a fluid-structure coupling simulation model of the water-lubricated bearing considering the shaft bending and bearing deformation is established.The magnitude and distribution of water film pressure under two models ignoring shaft bending and considering shaft bending are analyzed by fluid-structure interaction simulation calculation.The results show that ignoring the shaft bending will bring errors to the solution of the lubrication characteristics of water-lubricated bearings.(3)The effects of operating conditions,structure and material parameters on the lubrication characteristics of water lubricated bearing considering shaft bending and bearing deformation are studied.The effects of different parameters on the water film pressure,water film pressure distribution,friction coefficient,bearing lining deformation and equivalent stress distribution are analyzed.The research results show that both increasing the rotational speed and decreasing the load are beneficial to the formation of hydrodynamic pressure;Increasing the length-diameter ratio of the bearing and reducing the bearing clearance are both beneficial to improve the concentration of water film pressure;The changes of elastic modulus and Poisson’s ratio mainly affect the deformation and equivalent stress of bearing lining,and the influence of elastic modulus is more obvious than that of Poisson’s ratio.(4)The friction characteristics test and water film pressure test of water-lubricated bearing were carried out,and some simulation conditions were verified.The test results show that the friction coefficient of the bearing increases with the increase of the load,and decreases with the increase of the rotational speed;the maximum water film pressure of the water-lubricated bearing appears at the end of the bearing near the propeller,and gradually decreases along the axial direction.