Study On Vibration Characteristics Of Marine Magnetic Pump Water-lubricated Bearing

The water-lubricated bearing plays a key role in the marine magnetic pump,and has a great influence on the shafting and vibration of the marine magnetic pump,which is directly related to whether the marine magnetic pump can run smoothly with low vibration.In recent years,more and more studies have shown that water-lubricated bearings have an important effect on the vibration of machinery.Meanwhile,water-lubricated bearings have become a hot topic in the field of hydraulic machinery.The influence of water-lubricated bearings on the vibration of marine magnetic pump is one of the important research directions.In this paper,the lubrication characteristics of water-lubricated bearings are calculated,and the dynamic characteristics of bearings are studied based on the lubrication characteristics.Finally,the influence of water-lubricated bearings on the vibration of marine magnetic pump is analyzed,in order to provide some reference for the low vibration design of marine magnetic pump.The research contents and main achievements of this dissertation are as follows:1.The research status of lubrication characteristics,dynamic characteristics of water-lubricated bearings and vibration of marine magnetic pump are summarized.2.The influences of bearing clearance,eccentricity and aspect ratio on the lubrication performance of water-lubricated bearings were analyzed numerically.First,the flow field in the marine magnetic pump under various working conditions was numerically calculated and the experimental verification was carried out.Then,the lubrication characteristics of the water film were calculated with the calculation structure of the pump as the boundary condition.The results show that:(1)The error between the calculated value of head and the test value is 2.3%and the calculation error of efficiency is 2.8 percentage points under the rated working condition;(2)With the increase of bearing clearance from 0.07mm to 0.109mm,the maximum water film pressure and water film stiffness decrease gradually,and the water film bearing capacity increases gradually;(3)With the increase of bearing eccentricity rate from 0.3 to 0.7 and length-to-diameter ratio from 0.6 to 1.4,the maximum water film pressure,water film bearing capacity and water film stiffness increase gradually.3.The effects of bearing clearance,eccentricity and length-to-diameter ratio on the dynamic characteristics of marine magnetic pump bearing/rotor system under0.8Q_d,1.0Q_d and 1.2Q_d working conditions were numerically analyzed by transient dynamics analysis.The results show that:(1)when the bearing clearance increases from 0.08mm to 0.1mm,the rotation fit accuracy of the rotor gradually deteriorates and the bearing vibration gradually increases;under 0.8Q_d,1.0Q_d and 1.2Q_d,the peak value of bearing vibration velocity increases by 26.1%,31.7%and 54.2%,respectively.(2)When the bearing eccentricity increases from 0.4 to 0.6,the rotor rotation coaxiality becomes worse and the bearing vibration gradually increases;the peak vibration velocity increases by 42.3%,30.3%and 52.2%at 0.8Q_d,1.0Q_d and1.2Q_d,respectively.(3)When the aspect ratio of the bearing increases from 0.8 to 1.2,the ability of the bearing to support rotational stability is enhanced,and the vibration of the bearing decreases gradually;at 0.8Q_d,1.0Q_d and 1.2Q_d,the peak vibration velocity decreased by 31.5%,24.2%and 48.6%,respectively.4.The effects of water lubrication bearing on the vibration characteristics of marine magnetic pump under 0.8Q_d,1.0Q_d and 1.2Q_d working conditions are analyzed numerically.The results show that:(1)Under the rated working conditions,the vibration velocity level of the pump increases gradually with the increase of bearing clearance,and the maximum increase is 4.6%;With the increase of bearing eccentricity,the vibration velocity level of the pump gradually increases,and the maximum increase is 2.1%.With the increase of bearing length-diameter ratio,the vibration velocity level of the pump decreases gradually,and the maximum decrease is 2.9%.(2)When the clearance is 0.08mm,the eccentricity is 0.3,and the aspect ratio is 1.2,the induced vibration of the water-lubricated bearing to the pump is the least.(3)It can be seen that:Among the three factors,the clearance has the greatest influence on the pump vibration,the length-diameter ratio has the second influence,and the eccentricity has the least influence on the pump vibration.