Study on nonlinear vibration mechanism of fluid machinery rotor system
In order to solve the problem that it is difficult for the linear vibration model of the existing rotor to precisely describe nonlinear vibration of rotor,a nonlinear motion model for rotor-seal-bearing system based on the Muszynska nonlinear seal fluid force model was established.The nonlinear motion equations were solved by the fourth-order Runge-Kutta partial differential solution method.The axis orbit diagram at 3000,8500,12000 and 15000 r/min were analyzed to solve the vibration bifurcation diagrams under such parameters as rotating speed,rotor structure and bearing size.Based on the established nonlinear vibration model,a rotor-seal-bearing system test bench was built to explore the influence of pressure on the vibration of the rotor axis trajectory,and finally the vibration law of the rotor was explored from two aspects:simulation and experiment,which provides a basis for the next optimization.The results show that with the increase of the rotational speed from 3000 r/min to 12000 r/min,the axis orbit diagram of the rotor is gradually changed from a dimensionless radius of 0.4 circle to a double-period circle.When the speed exceeds 15000 r/min,the rotor vibration becomes lawless,and turns to the chaos graph.From the bifurcation diagrams under difference influence parameters of the rotor,it can be found that the amplitude of the rotor system is proportional to the rotational speed and seal length,and is inversely proportional to seal clearance and bearing lubrication length.When designing the rotor structure,the amplitude can be reduced by increasing the seal clearance or extending the lubrication length of the bearing.In the rotor system,the biggest influence factor is rotor speed,followed by the rotor structure.
muszynska nonlinear seal fluid excitation forcerotor-seal-bear system modelvibration characteristics
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