Abstract:The nonlinear dynamic characteristics of hybrid gas bearings-flexible rotors for rotating ramjet was studied where the inlet compressed flow forces were considered which were generated from the whirl of the rotor. Firstly the internal flow of compressed inlet flow was analyzed and the nonlinear complex forces model which acted on the rotor was obtained; the hybrid gas bearing-rotor system (multi-degree freedom) of rotating ramjet was modeled by employing the finite element method, and then this model was solved coupling with the gas lubricated Reynolds equation with time terms. The trajectory and frequency spectrum of the system for different supply pressure and eccentricities were obtained by the numerical simulation. The results indicated that if the supply pressures and eccentricities were chosen properly, the vibration amplitudes can be reduced and the stability would be improved.