Annular bearing with diffuser and inlet flow guide

A diffuser and inlet flow guide for an annular fluid film bearing of the type having a rotatable element mounted for rotation about an axis of the bearing and a stationary element mounted concentrically about the rotatable element and spaced radially therefrom such that an annular clearance is defined therebetween for the flow of fluid therethrough from an inlet end of the annular clearance to an outlet end thereof, the diffuser and inlet flow guide comprising:

• a ring defining a axis and having an outer surface and an inner surface spaced radially inward of the outer surface, and front and rear end faces that extend between the outer and inner surfaces and define opposite ends of the ring;
• the ring defining a plurality of slots formed in the inner surface, each slot extending from the front end face to the rear end face and extending at least partially through a radial thickness of the ring defined between the inner and outer surfaces thereof, each slot having an entrance portion originating at the front end face and extending in a first direction defining a positive helix angle relative to the ring axis, each slot having an exit portion extending in a second direction defining a negative helix angle relative to the ring axis, and each slot defining a flow area that increases from the front end face to the rear end face such that fluid flowing through the slot is diffused.

A method of enhancing dynamic stability of an annular fluid film bearing of the type having a rotatable element mounted for rotation about an axis of the bearing and a stationary element mounted concentrically about the rotatable element and spaced therefrom by a radial clearance such that an annular clearance is defined therebetween for the flow of fluid therethrough, the fluid entering the annular clearance having a tangential component of velocity in the direction of rotation of the rotatable element caused at least in part by entrainment of fluid with the rotatable element, the method comprising:

• turning the fluid entering the annular clearance so as to reduce the tangential velocity thereof in the direction of rotation of the rotatable element;
• and
• diffusing the fluid so as to increase the static pressure of the fluid entering the annular clearance.