Nonlinear dynamic behaviors of a rod fastening rotor supported by fixed-tilting pad gas-lubricated bearings

【作者】 吕延军； Di Hei； Yongfang Zhang； Zunyou Lu；

【Author】 Yanjun Lu;Di Hei;Yongfang Zhang;Zunyou Lu;School of Mechanical and Precision Instrument Engineering,Xi’ an University of Technology;State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi’ an Jiaotong University;School of Printing and Packaging Engineering,Xi’ an University of Technology;

【机构】 School of Mechanical and Precision Instrument Engineering,Xi’an University of Technology； State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi’an Jiaotong University； School of Mechanical and Precision Instrument Engineering,Xi’ an University of Technology； School of Printing and Packaging Engineering,Xi’an University of Technology；

【摘要】 A rod fastening rotor with the fixed-tilting pad gas-lubricated bearings support is modeled.The rod fastening rotor is not integral,and the rotor is connected by rods.The torque is transmitted by the rods and interfacial friction of both disks.The rods are considered as bending resistance spring.The contact effect of both disks has the influence of nonlinearity on the stiffness of the rotor,so the contact effect of both disks can be considered as resistance bending springs with nonlinearity.The gyroscopic effect of the disks is considered in the modeling of the rod fastening rotor-gas bearing system.The rotational inertia of the tilting-pads is also considered.The multi-grid finite element method is employed to solve the nonlinear gas film forces of fixed-tilting pad bearings.The pendulum angles of pads can be obtained by solving the motion equations of rod fastening rotor and tilting pads simultaneously.Then,the nonlinear dynamic behaviors of the rod fastening rotor are analyzed by the improved Newmark method.Because the calculation error exists in each step,the Newmark method only satisfies the motion constrained condition,but does not satisfy dynamics equation simultaneously.The Newmark method is improved by compensating the calculating error in each step.The improved Newmark method not only satisfies the motion constrained condition but also satisfies dynamics equation,and the improved Newmark method can reduce the computing error and improve computing stability.Finally,the nonlinear unbalanced responses of the rod fastening rotor with fixed-tilting pad gas bearings support are investigated by the orbit diagrams,the time series,the frequency spectrumdiagrams,and the Poincare maps.The orbits of the rod fastening rotor and the pendulum angles of pads are also investigated at different preloads and pivot ratios.更多还原

【Abstract】 A rod fastening rotor with the fixed-tilting pad gas-lubricated bearings support is modeled.The rod fastening rotor is not integral,and the rotor is connected by rods.The torque is transmitted by the rods and interfacial friction of both disks.The rods are considered as bending resistance spring.The contact effect of both disks has the influence of nonlinearity on the stiffness of the rotor,so the contact effect of both disks can be considered as resistance bending springs with nonlinearity.The gyroscopic effect of the disks is considered in the modeling of the rod fastening rotor-gas bearing system.The rotational inertia of the tilting-pads is also considered.The multi-grid finite element method is employed to solve the nonlinear gas film forces of fixed-tilting pad bearings.The pendulum angles of pads can be obtained by solving the motion equations of rod fastening rotor and tilting pads simultaneously.Then,the nonlinear dynamic behaviors of the rod fastening rotor are analyzed by the improved Newmark method.Because the calculation error exists in each step,the Newmark method only satisfies the motion constrained condition,but does not satisfy dynamics equation simultaneously.The Newmark method is improved by compensating the calculating error in each step.The improved Newmark method not only satisfies the motion constrained condition but also satisfies dynamics equation,and the improved Newmark method can reduce the computing error and improve computing stability.Finally,the nonlinear unbalanced responses of the rod fastening rotor with fixed-tilting pad gas bearings support are investigated by the orbit diagrams,the time series,the frequency spectrum diagrams,and the Poincare maps.The orbits of the rod fastening rotor and the pendulum angles of pads are also investigated at different preloads and pivot ratios.更多还原