Research On Characteristics And Influencing Factors Of Water-lubricated Bearings Under Fluid-solid Interaction

Water-lubricated shaft bearings are widely used in naval vessels,ships,and water pumps due to their environmental friendliness,pollution-free,simple structure,vibration and noise reduction.Water-lubricated bearings have the characteristics of low lubricating medium viscosity,easy to produce cavitation,bearing material is mostly non-metal,low strength and easy to deform.Therefore,the influence of fluid-solid coupling must be considered.Firstly,in this paper,a computational fluid dynamics model for water-lubricated bearings based on two-phase flow is established to investigate the influence of eccentricity and speed on water film pressure,bear load,deflection angle,and cavitation,and to analyze the changes caused by bearing grooves.The research results show that the water film pressure,bearing load and water film vaporization ratio all increase with the increase of eccentricity and speed.After grooving,the maximum pressure of the water film at the same rotation speed is reduced,the carrying capacity is weakened,and the cavitation rate is reduced.After grooving,the bearing flow rate increases,and the heat dissipation and pollution discharge capacity is enhanced.Secondly,a numerical analysis model of water-lubricated bearing based on the two-way fluid-solid coupling is established,the flow field characteristics and bearing deformation of the water-lubricated bearing after coupling are calculated,and the influence of rotation speed and eccentricity on the effect of fluid-solid coupling is analyzed.The research results show that after considering the coupling,a convex peak is generated at the junction of positive and negative pressures and a convergent wedge is formed,resulting in the dynamic pressure effect,which increases the pressure at the convergent wedge,extends the positive pressure zone and shortens the negative pressure zone.As a result,the maximum water film pressure decreases by18.14%,the load decreases by 2.73%,and the water film vaporization ratio decreases by 73.94%under the same eccentricity.The deformation of the bearing bush is caused by the water film pressure.The bearing bush is compressed in the positive pressure zone and protruded in the negative pressure zone.With the increase of eccentricity,the deformation degree of the bearing bush increases.At high speed,the junction of positive and negative pressure,the intersection of negative pressure endpoint and positive pressure start point are prominently convex,forming a convergent wedge,and the local dynamic pressure effect is significant,resulting in a decrease in the maximum pressure of the water film but a slight increase in the load.Finally,considering the fluid-solid-heat coupling effect,a solution model for the temperature field and pressure field of the sliding bearing is established,and the reason for the deformation of the sliding bearing bush is studied.Taking a bearing as an example,the temperature and pressure distribution in the bearing bush and the deformation of the bearing bush caused by the two are calculated.It is found that both temperature and pressure will cause deformation of sliding bearing bushes,pressure is the main cause of deformation of waterlubricated bearings,and temperature is the main cause of oil-lubricated bearings.On this basis,the influence of the thermal deformation of the bearing bush on the measurement result of the journal center position is further analyzed.Combined with field experiments,the abnormal deviation of the journal center position occurred during the speed increase,and the load operation process is explained.It shows that ignoring the thermal deformation of the bearing bush caused by the temperature rise of the lubricating oil will cause a large error in the measurement result of the journal center position.