Research On Real-Time Efficiency Enhancement Of Water Lubrication Based On The Secondary Lubricant

In the context of China’s active advocacy of green development concept,water-lubricated bearings,with its low cost,good heat dissipation and environmentally friendly advantages,gradually become the best choice to replace the traditional oil-lubricated bearings in China’s ship and marine engineering equipment industry.However,due to the low viscosity of water,poor film-forming ability and other shortcomings,water-lubricated bearings in the encounter of harsh conditions,easy to produce the rupture of the water film between the friction pairs,resulting in bearing wear and tear,affecting its service life.To address this problem,the group proposes to use trace lubricant as the second lubricating medium to temporarily inject it into the contact area when the water-lubricated bearing encounters harsh working conditions,so as to improve the bearing capacity of the water-lubricated bearing and achieve the purpose of temporary hedging.This paper selects emulsified oil as the second lubricating medium,and uses MRH-3 high-speed block-on-ring test rig to evaluate the friction and wear performance of nitrile rubber material and Thordon material under different working conditions under pure water lubrication and after the injection of trace emulsified oil,and analyzes the difference of the wear surface of different material test blocks by confocal microscope observation.The main contents and conclusions are as follows:1.Study on the influence of different oil supply and load on the critical speed of trace emulsified oil assisted water lubrication.The critical speed decreases with the increase of oil supply when the test load and oil supply rate are constant and only the oil supply changes.In the case of constant oil supply and oil supply rate,only the load is changed,the critical speed increases with the increase of load.Under different working conditions,no matter the friction coefficient of the friction pair increases or decreases after the injection of emulsified oil,the wear marks of the test block are narrower than those of the test block under pure water lubrication.2.Experimental study on oil supply method to enhance water lubrication of trace emulsified oil.Oil supply mode 1 is parallel oil injection at the inlet end,and oil supply mode 2 is oil injection on the surface of the test block at the inlet end.Compared with oil supply mode 1,oil supply mode 2 has better friction coefficient reduction effect.With the increase of rotational speed,the difference of friction coefficient between the two becomes larger.3.Study on the effects of different oil supply rates on the decrease of friction coefficient under oil supply mode 2 and oil supply mode 3.In the low speed region,the smaller the oil supply rate,the greater the friction coefficient decreases.When the speed increases,the difference in the friction coefficient reduction caused by different oil supply rates is smaller than that at low speed,and the greater the oil supply rate,the better the reduction effect.The oil supply rate has little effect on the friction reduction effect under oil supply mode 3.4.Simulation study on the performance of enhanced water lubrication by oil supply mode and oil supply rate.Under oil supply mode 2,different oil supply rates will affect the velocity of the countercurrent at the inlet,and the volume fraction of oil in the contact area will also change with the oil supply rate under oil supply mode 2.Under the oil supply mode 3,the oil supply rate does not affect the speed and direction of the lubricating oil entering the contact area,nor does it affect the oil volume fraction in the contact area.After extending the simulation time to ten minutes,the oil film is still attached to the contact area and the surface of the steel ring,which verifies that the scheme improves the durability of the friction.5.Experimental study on enhanced water-lubricated friction and wear of Thordon material.The results show that when the load,oil supply and oil supply rate are kept unchanged,the friction coefficient of the Thordon material will change with the different rotational speeds after the injection of trace emulsified oil in the water environment.The surface of the test block after the test was observed by confocal microscopy.It was found that under the same working conditions,after the injection of emulsified oil,the wear scar width of the Thordon material was wider than that of the nitrile rubber material.There are rolling wear marks on the surface of both materials,and the wear depth of the outlet area is deeper.Comparing the surface of the Thordon test block under different working conditions,it was found that the surface wear scar width of the Thordon material gradually increased with the increase of load and speed.