In order to reveal the nonlinear dynamic behavior of the supercritical carbon dioxide turbine rotor system under the coupling effect of seal aerodynamic effect and bearing oil film support. A rotor-bearing-seal coupled whirling model is established. The nonlinear oil film force of the short bearing and the differential equation of rotor system motion are coupled by flow field simulation to realize the joint solution of rotor nonlinear dynamic theory and the aerodynamic effect of seal flow field. The influence of the coupled effect of oil film force and seal aerodynamic effect on the motion and dynamic characteristics of the rotor is investigated. The results show that after considering the nonlinear oil film force of bearing support

the additional displacement of journal increases the whirl radius and lateral offset displacement of the rotor

and the seal aerodynamic effect in the high frequency region is enhanced. The change of the logarithmic decrement of sealing force is more obvious at the rated frequency and frequency multiplication. The additional stiffness and damping effect of bearing oil film make the seal dynamic characteristic coefficient more stable during the change in whirl frequency

decrease the range of effective damping of seal and the stability of rotor system in the high frequency range.