An investigation of journal bearing behaviour in the superlaminar flow regime
Review of the literature clearly illustrated the need
for more information on journal bearings operating in
the transition vortex regime. Especially in the light
of recent information indicating that many real applications
may be operating in this region and to date most consideration
has been given to fully turbulent studies.
Accordingly, an experimental test rig was designed to
measure torque and both circumferential and axial pressure
profiles. The test bearing was circular and of central
circumferential supply groove design. LID ratio was
0.25 for each land and a clearance ratio of 0.00307 used
to conform with "real" modelling of high speed bearings.
Lubricant inlet and outlet temperature were measured
(with Rem based on the latter) together with shaft speed
and displacement. Three lubricants were used, Tellus 22,
Tellus RIO and water to allow a Reynolds number range of
30 - 10, 000 to be covered, and thus encompassing lamina_r,
transition and turbulent flow regimes.
Low Reynolds number results agreed well with laminar theory
and transition from laminar to vortex flow was observed
to occur around the speed predicted by Taylor. In
the transition region, inertial effects were found to be very small but were taken into consideration for
all comparisons between theory and experiment.
Existing super laminar theories were in poor agreement
with experiment. An empirical theory based on friction
factor results was developed including inertia and
led to much improved estimates of circumferential
pressure distribution. The best agreement being
observed in the mid transition region were a "hump"
in the friction factor v's Reynolds number results
had been measured.
Due to the method of measuring pressure profiles
interesting observations are reported on cavitation