Externally pressurized: A separate external supply of air is fed under pressure between the two surfaces being kept apart.
It is a continuous flow system where pressurized gas from the source flows through restrictors into the clearance between the bearing surfaces escaping to the atmosphere at the outside edges of the bearing.
Types: Simple orifice fed, Pocketed orifice, Slot fed and Porous.
Self-generating: The supporting film is generated by the relative motion of the two surfaces being kept apart.
An aerodynamic bearing can be of several types. The design characteristics differ greatly between journal and axial bearings and they can suffer problems of instability.