Modeling
a Porous Slider Bearing With An External Reservoir
Participants: J. Braun (Mechanical Eng),
G. W. Young (Theo and Applied
Math)
The use of porous
bearings is widespread throughout industry. In classical cases, the porous
medium can be thought of as an external reservoir and so their use is ideal for
applications where an external oil supply is undesirable, impractical, or too
costly. In these cases, as the bearing moves and creates a pressure gradient,
the fluid from inside the porous layer is drawn into the film, further enabling
lubrication.
The purpose of
this project is to mathematically investigate the effects of modifying a slider
bearing to include a porous layer and a fluid reservoir. Using
the Darcy model for flow inside a porous medium, we consider a porous slider
bearing above an external reservoir. Order of magnitude analyses are performed
to simplify the governing equations inside the bearing. Further analysis of the
directional permeabilities allows for a modified
Reynolds equation to obtain a solution for the pressures inside all three
regions (lubricating film, porous medium, and reservoir) of the bearing. The
moving slider bearing establishes a pressure profile that circulates fluid
between the lubricating region and the reservoir. Simplifications are made to
allow for a semi-analytical solution to be constructed that can be easily
solved using a standard computational package such as Maple. It is shown that
the fluid is circulated inside the bearing to allow for load-carrying
capability as well as for no external oil supply and pump. Future work will
examine different bearing geometries using the porous medium/reservoir concept,
and the inclusion of heat transfer analyses to examine the feasibility of a
self-contained bearing. In the latter case the heat transfer must be sufficient
to cool the circulating fluid before it re-enters the lubricating film region.
Publications: