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National Advisory Committee for Aeronautics, Technical Notes - Investigation of 75 Millimeter Bore Cylindrical Roller Bearings at High Speeds - II - Lubrication Studies - Effect of Oil Inlet Location, Angle, and Velocity for Single Jet Lubrication

An experimental investigation of the effect of several oil
introduction parameters on the temperature of 75-millimeter-bore
(size 215) cylindrical-roller, inner-race-riding cage-type bearings
over a range of DH values (product of the bearing bore in mm and the
shaft speed in rpm) from o_.3-x 106 to 1.45 x 106 and static radial loads
to 568 pounds with single-Jet circulating oil feed is reported herein.

For the oil-Jet positions investigated, the inner- and outer-race
bearing temperatures were found to be at a minimum when the oil was
directed at the cage-locating surface perpendicular to the bearing
face. In consequence of the foregoing findings, all subsequent
investigtions were conducted with the lubricant directed at the cage-
1ocating surface and perpendicular to the bearing face; and therefore '
the following results and conclusions apply only under such a. lubri-
cating condition.

For all values of oil flow and all oil-Jet diameters investigated,
the outer-race mumum temperature increased linearly with an increase
in DN value; however, the inner-race temperature increased with DN
value at a rate slightly greater than linear.

An increase in oil inlet velocity at a given flow decreased both
the outer-race and inner-race temperatures. It appeared that a point
of diminishing returns regrding the effectiveness of an increase of
oil inlet velocity occurred at about 60 feet per second for the
operating conditions investigated.

Heat-transfer considerations indicated that to minimize the
number of parameters when dealing with inner-race temperatures the
variables to be plotted should be) where
(Tm-T01) is the difference between. the inner-race bearing temperature
and the oil inlet temperature, DH is the product of the bearing bore
in millimeters and the shaft speed in rpm, d is the oil-Jet diameter,
M is the oil flow, and n and y are constants. It was found
empirically, however, that the variable (do'e/M)n @ve better
correlation than did (d/M).