Fluid Structure Interaction Research On Water-lubricated Stern Tube Bearings Based On Partial Contact

Water-lubricated rubber bearings are widely used in marine propulsion system,in virtue of their simple structure, anti-pollution, vibration reduction and shockresistance. However, due to the gravity of the propeller of ships, the stern shaft willbe a certain bent which lead to partial contact between stern shaft and bearing. Inthis case, the bearing will be poor lubrication cooling, the temperature rises, damageaccident and so on.In order to improve the partial contact conditions and lubrication properties ofbearing, the water lubricated rubber stern bearing will be selected as object for thestudy, rule-asperity texture will be introduced into the bearing surface, FSI model ofbearings will be used to study the influence of operating conditions, rule-asperitytexture parameters and structural arrangement on the partial contact conditions andlubricating properties of water lubricated bearings, The conclusions are as follows:1. Operating conditions effects. Improve the stern shaft speed and watervelocity, pressure or the carrying capacity of water film increasing, the contactforce acting on the bearing educing, the shaft sinking displacement reduction thosehelp to improve partial-contact conditions and lubrication performance of waterlubricated rubber stern bearing. Increases pressure ratio will cause the bearings’contact force increase, the maximum effective stress and maximum deformationincreases. However, due to the elastic deformation of rule asperity, especially underheavy load conditions, the water film thickness can be reduced to some extent,which can improve the carrying capacity of the water film.2. Structural parameters effects. Height or the radius of the rule-asperity willchange the water pressure distribution and carrying capacity, thus changing thewater lubricated bearings partial contact condition and lubrication properties. Studyfound that with a degree of radius increases or height decreases, the pressure and thecarrying capacity of the water film will increase, the total contact force acting on thebearing and the bearing stress and deformation reduce and also the shaftdisplacement.3. Structural arrangement effects. The spacing between adjacent asperity decreases or increases will influence water film pressure and carrying capacity. Wefound that only when axial spacing is less than the critical value l, or circumferentialspacing greater than the critical value α, the film of water will produce a certaincarrying capacity, which can help to improve the partial contact situation andlubrication properties. After comparative analysis, it was found that densityincremental of asperity will produce maximum pressure and support force,minimum total contact force acting on the bearing.