Özet:

This paper dedicates on the non-dimensional nonlinear rotor dynamics analysis of a turbo expander under unbalanced bearing forces caused by the temperature difference. The turbo expander rotor system is abstracted to a strictly symmetric lumped parameter model. The influence of temperature difference is simplified to the ratio of oil viscosity, which is applied on Capone oil film model. 1-Dimensional and 2-Dimensional bifurcation analysis are implemented in order to obtain the dynamic characteristics of the turbo expander rotor system. It can be concluded that the compressor wheel and the expander wheel are of the same pattern of motion in spite of the existence of the temperature difference; High temperature difference results in a high entrance point of 1-periodic motion to quasi-periodic motion, but the entrance point keeps still when the ratio of viscosity reaches some critical value. The oil-whirl, first and second order oil whip of sliding bearings are the most important factors influencing the asymmetric vibration of the compressor wheel and the expander wheel.

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