Nonlinear Dynamic Analysis of High-Speed Aerostatic Conical Bearing–Rotor System with Micro-Orifice Frictional Loss

Aerostatic conical bearings with micro-orifices (ACBMOs) can simultaneously withstand both radial and axial external loads and have high power density. Nevertheless, due to the larger surface-to-volume ratio and length-to-diameter ratio of micro-orifices, the gas flow through micro-orifices is more susceptible to frictional loss. Since frictional loss in micro-orifices has been ignored in the literature, an aerostatic conical bearing lubrication model with frictional loss in micro-orifices and a transient model of their nonlinear dynamics are established. The effects of the micro-orifice length-to-diameter ratio and relative roughness on lubrication performance, nonlinear behaviors, and ACBMO–rotor system stability are investigated, followed by experimental validation. The results indicate that the gas mass flow rate of the micro-orifices, gas film pressure, and load capacity in the ACBMOs decrease with the increase in micro-orifice relative roughness and length-to-diameter ratio, which cannot be observed in the conventional model without frictional loss. Meanwhile, both the onset speed of instability and the failure speed decrease when frictional loss occurs in micro-orifices are considered.