Influence of orifices on stability of rotor-aerostatic bearing system

This paper has studied the influences of both the number and locations of entry holes on the stability of a rigid rotational rotor supported by two double-row, orifice compensated aerostatic bearings. The air is assumed to be perfect gas, undergoing the adiabatic process and passing through entry holes into the bearing clearance, is governed by Reynolds equation including the coupled effects of wedge due to rotor rotation and squeezed film due to rotor oscillation. The Ph-method is used to analyze Reynolds equation which is then solved by the finite difference method and numerical integration to yield static and dynamic characteristics of air film. The equation of motion of the rotor-bearing system is obtained by using the perturbation method and the eigen-solution method is used to determine the stability threshold and critical whirl ratio. The eccentricity, rotor speed, and restriction parameter are considered in the analysis of the whirl instability of the rotor–aerostatic bearing system for the comparisons between various designs in the number and locations of entry holes of aerostatic bearings.