Aerodynamic thrust and journal bearings

Thrust and aerodynamic bearings operate on the same principles as those lubricated with oil or water (see Note). Their particularity lies in the very low viscosity of the lubricating gases - both an advantage and a disadvantage - to which are added the specific features brought about by compressibility. They are therefore used in small, high-precision machines where high speeds and low backlash are required (measuring equipment, medical industry).

The article presents the main static (load capacity, torque) and dynamic (dynamic coefficients, stability, unbalance response) characteristics of thrust and aerodynamic bearings, as well as the problems raised when integrating them into a rotating machine. The particularities arising from lubricant compressibility are discussed for air, but the conclusions apply to any other perfect gas.

The article focuses on the physical and technological considerations that need to be taken into account when considering the use of thrust bearings or aerodynamic bearings. The integration of these components into a rotating machine is presented, assuming a rigid rotor.