Effects from the stiffness and damping of O-rings on the stability and nonlinear dynamic characteristics of a rotor supported by flexible porous gas bearings

In the field of high-speed rotating machinery, it is a common phenomenon that the rotor is liable to lose stability when rotating at high speeds. Installing a layer of damping structure between the bearing and the housing is a potential means to restrain the vibration of the rotor. In this article, it is useful to improve the stability of the rotor in the way of increasing the damping of the bearing by installing several O-rings on the porous air journal bearing (PAJB). The rotor-bearing test rig is set up to study the vibration of the rigid rotor supported by PAJBs with three types of O-rings mounted for different supply pressures. Moreover, a nonlinear numerical model is established to predict the rotor responses. The accuracy of the numerical model is verified by comparing the calculated results with the data tested by the above experiment. Based on the experimental and simulation results, the effects of the supply pressures, stiffness and damping of O-rings on the stability of the rotor-PAJB system are investigated. The influence of the stiffness and damping of O-rings on the nonlinear dynamic characteristics of the systems is further studied by expanding the parameter range of the numerical simulation, and the relevant laws are summarized. The results demonstrate that both the stiffness and damping of O-rings have significant influence on the stability of the rotor-PAJB system. When the stiffness of O-rings is in the unstable stiffness interval, the stability of the rotor at high speeds will decrease. Meanwhile, larger damping produces better stability. By both the experimental and theoretical studies, the investigation is expected to promote the development of turbomachinery towards higher speeds and better stability.