Calculation And Test Of Journal Centre Motion Trajectories Of A Spiral Oil Wedge Journal Bearing

As a kind of important graphic describing vibration, journal centre trajectory of the rotating machinery contains quite a lot of information. Journal centre trajectory is a comprehensive behavior of journal bearing working condition. Journal centre trajectory analysis can be used to confirm index repeatability and the least oil film thickness, clearly reflect bearing lubrication conditions, determine bearing’s reliability when working, confirm bearing liquid under the condition of the lubrication to the minimum clearance and the precision and lube oil viscosity and the right inlet port position of the bearing, analyze and identify bearing fault, etc. Therefore, in the study of the sliding bearing, journal centre trajectory is very important, is the basis of the analysis of bearing lubrication. This project combined with a spiral oil wedge journal bearing support with the rotor-bearing system, the establishment of a computational model of the nonlinear core path, calculate the spiral oil wedge journal bearing as well as general journal bearings under different speed and simulate the vibration experiment of the journal centre trajectory.Firstly, the equations of motion of the rotor-bearing system is established, which is based on the equivalence of neck journal inertial force, non-linear oil film force and dynamic load, and the non-linear analysis model of journal centre trajectory is established, which is based on the nonlinear theory, to get the journal centre trajectory. Synchronously, based on linearization technique of oil film force the linear model, we established journal center whirl around its static equilibrium position for conveniently analyze. We also calculated the rigidity and the damping coefficient of oil film in balance position with the application of partial derivative method to get the linear journal centre trajectory.Secondly, we calculated the journal centre trajectory of the spiral angle from0.1-0.9with the speed in6000r/min, analyzed the influence of spiral angle to journal centre trajectory by comparing these data; we calculated the journal centre trajectory when speed is different in order to get the critical speed. Through the spectrum analyses, we compared the spiral oil wedge bearing and common round bearings in each of the critical speed respectively under the characteristics of journal centre trajectory.Thirdly, as a result of different structure between the bearing the spiral oil wedge and round bearing two, under the sine excitation force,we compared and analyzed both bearing journal centre trajectory, researched the dynamics process and resonance,and finally by MATLAB simulation we obtained curve of the amplitude frequency response as well as resonance frequencyFinally, the actual journal centre trajectory is gotten in the sliding bearing test bench. According to the experimental test we acquired the practical journal centre displacement data. We draw the actual graphics of the journal centre trajectory through analyzing the measured signal by FFT and extracting useful signal. The results shows the method discussed in the paper can also conform to the experimental test.