| China is the main bearing demander and producer in the world.As the joint of various rotating mechanical equipment,journal bearing plays a pivotal role in the fields of aviation engines,ships,mechanical manufacturing,power generation equipment,petrochemical equipment and other fields.With the rapid development of global industrialization,a large number of mechanical equipment are increasingly tending towards complex work conditions with high power,high speed and heavy load.It is difficult to meet the requirements in vibration damping,bearing capacity and life for general journal bearing.Instead,the fluid pivot tilting pad bearing presents better bearing capacity,higher stiffness and damping because of static pressure hole and two-layer oil film structure of dynamic and static pressure,and is widely applied in electric power plant,marine propellers,ship turbines and other directions to meet requirements.However,domestic research on this bearing is still in the initial stage.At present,there are neither mature theories nor reliable experimental samples for reference in the bearing design.Based on the above situation,the paper takes a three-pad fluid pivot tilting pad bearing with an inner diameter of 125 mm as the research object,and aims to explore the rules of lubrication performance parameters of the bearing in actual engineering conditions.The numerical calculation model of the fluid pivot tilting pad bearing is established by MATLAB based on the two-dimensional Reynolds equation of the flow balance of the dynamic and static pressure layers.The paper focuses on the effects of rotational speed and external load on the lubrication performance parameters such as oil film pressure,temperature rise and shaft trajectory of the bearing.The main research contents of this paper are as follows:(1)Research on numerical calculation theory of the fluid pivot tilting pad bearing.Under the condition of internal and external flow balance,the formation mechanism of oil film in each stage of the fluid pivot tilting pad bearing is analyzed,the expression of oil film thickness is derived,and the calculation model of static characteristics of bearing is established by MATLAB.The results are compared with literature and show that relative errors of the maximum dynamic pressure and static pressure cavity oil film pressure are 2.98% and 5.58% respectively.(2)Design and construction of inverted the fluid pivot tilting pad bearing test bed.The overall scheme design of bearing test bed is proposed according to test requirements.The three-dimensional structural design,verification of parts and the machine of machine are completed by Solid Works.Complete the hardware selection and layout scheme of pressure,temperature and displacement sensors.The bearing performance test software is compiled based on Lab VIEW,and control system of the test bed is designed on Siemens human machine interface.(3)Experiment and analysis of lubrication performance of the fluid pivot tilting pad bearing.The oil film pressure distribution,oil film temperature rise and shaft trajectory test are conducted at 500,1000,1500 and 2000r/min speeds and 300,1300 and 2300N loads respectively for the three-pad fluid pivot tilting pad bearing with an inner diameter of 125 mm.In the test conditions,the maximum pressure at the oil film pressure and static pressure hole are 1.472 MPa and 0.776 MPa,respectively,and the influence of rotating speed on bearing load performance is more obvious than that of external load.The maximum average temperature rise of the oil film is about 18℃,and it is approximately linear with rotational speed.In the experiment,a little amount of misalignment and dynamic unbalance at 500r/min,while only a little amount of dynamic unbalance existed in other conditions.Moreover,the shaft trajectory gradually approaches circular as the speed increases. |
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