Static characteristics at the start of the operation are theoretically investigated in a porous journal bearing with sealed ends lubricated only by the oil initially provided within its pores. This is a preliminary study for estimating the variation of these characteristics with running time. A simple analytical model of the mixed lubrication regime is proposed on the basis of the assumption that the external forces acting on the journal, i.e., the applied static load, the oil-film force and the force at the boundary friction part, are balanced. Numerical results show that air penetrates into the porous matrix at the oil-film rupture zone due to negative pressure in the porous matrix; this causes the reduction of oil content within the porous matrix and contributes to formation of the oil film in the bearing clearance. The oil leakage from the porous matrix induced by the air penetration suggests that, even if hydrodynamic lubrication conditions are possible at the start of operation, the lubrication mode will become mixed or boundary lubrication conditions with running time. The numerical data on the static characteristics are presented in graphical form, illustrating the effects of the Sommerfeld number in the hydrodynamic and mixed lubrication regimes.

1.
Beavers
G. S.
,
Sparrow
E. M.
, and
Magnuson
R. A.
,
1970
, “
Experiments on Coupled Parallel Flows in a Channel and a Bounding Porous Medium
,”
ASME Journal of Basic Engineering
, Vol.
92
, No.
4
, pp.
843
848
.
2.
Braun
A. L.
,
1982
, “
Porous Bearings
,”
Tribology International
, Vol.
15
, No.
5
, pp.
235
242
.
3.
Chandra
M.
,
Malik
M.
, and
Sinhasan
R.
,
1981
, “
Investigation of Slip Effects in Plane Porous Journal Bearings
,”
Wear
, Vol.
73
, pp.
61
72
.
4.
Cusano
C.
,
1972
, “
Lubrication of Porous Journal Bearings
,”
ASME JOURNAL OF LUBRICATION TECHNOLOGY
, Vol.
94
, No.
1
, pp.
69
73
.
5.
Cusano
C.
,
1979
, “
An Analytical Study of Starved Porous Bearings
,”
ASME JOURNAL OF LUBRICATION TECHNOLOGY
, Vol.
101
, No.
1
, pp.
38
47
.
6.
Darius Gnanaraj
S.
, and
Raman
R.
,
1992
, “
Experimental Studies on Wear in Oil-Impregnated Sintered Bearings
,”
Wear
, Vol.
155
, pp.
73
81
.
7.
Goldstein, M. E., and Braun, W. H., 1971, “Effect of Velocity Slip at a Porous Boundary on the Performance of an Incompressible Porous Bearing,” NASA Technical Note TN D-6181.
8.
Hashimoto
H.
, and
Komiyama
H.
,
1994
, “
Effects of Journal Surface Shear Stress on the Stability of Turbulent Bearings (1st Report, Theoretical Analysis by Short Bearing Theory)
,”
JSME Transactions
, Vol.
60
, No.
580
, pp.
4283
4288
(in Japanese).
9.
Hashimoto
H.
, and
Komiyama
H.
,
1995
, “
The Effects of Journal Surface Shear Stress on the Stability of Turbulent Bearings (2nd Report, Theoretical Analysis by Finite Bearing Theory)
,”
JSME Transactions
, Vol.
61
, No.
581
, pp.
198
203
(in Japanese).
10.
Ikeuchi
K.
,
Mori
H.
, and
Nishida
T.
,
1988
, “
A Face Seal With Circumferential Pumping Grooves and Rayleigh-Steps
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
110
, No.
2
, pp.
313
319
.
11.
Kaneko
S.
,
Ohkawa
Y.
, and
Hashimoto
Y.
,
1994
, “
A Study on the Mechanism of Lubrication in Porous Journal Bearings: Effects of Dimensionless Oil-Feed Pressure on Static Characteristics Under Hydrodynamic Lubrication Conditions
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
116
, No.
3
, pp.
606
611
.
12.
Kaneko
S.
,
Hashimoto
Y.
, and
I
H.
,
1997
, “
Analysis of Oil-Film Pressure Distribution in Porous Journal Bearings Under Hydrodynamic Lubrication Conditions Using an Improved Boundary Condition
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
119
, No.
1
, pp.
171
178
.
13.
Morgan, V. T., and Cameron, A., 1957, “Mechanism of Lubrication in Porous Metal Bearings,” Conference on Lubrication and Wear, The Institution of Mechanical Engineers, London, Paper 89, pp. 151–157.
14.
Morgan
V. T.
,
1969
, “
Porous Metal Bearings
,”
Powder Metallurgy
, Vol.
12
, No.
24
, pp.
426
451
.
15.
Prakash
J.
, and
Vij
S. K.
,
1974
, “
Analysis of Narrow Porous Journal Bearing Using Beavers-Joseph Criterion of Velocity Slip
,”
ASME Journal of Applied Mechanics
, Vol.
96
, No.
2
, pp.
348
354
.
16.
Yong-Xin
Quan
,
Ji
Ma
,
Yi-Geng
Tian
,
Gui-Ru
Zhou
,
Gao-Yi
Shi
, and
Guo-Liang
Wang
,
1985
, “
Investigation of Sintered Bronze Bearings Under High-Speed Conditions
,”
Tribology International
, Vol.
18
, No.
2
, pp.
75
80
.
17.
Raman
R.
, and
Vinod Babu
L.
,
1984
, “
Tests on Sintered Bearings With Reduced Oil Contents
,”
Wear
, Vol.
95
, pp.
263
269
.
18.
Rouleau
W. T.
, and
Steiner
L. I.
,
1974
, “
Hydrodynamic Porous Journal Bearings. Part I—Finite Full Bearings
,”
ASME JOURNAL OF LUBRICATION TECHNOLOGY
, Vol.
96
, No.
3
, pp.
346
353
.
19.
Tanaka, M., Fukuda, K., and Hori, Y., 1983, “Friction of Porous Metal Bearings: Effects of Reduced Oil Content,” Proceedings of JSLE, Oct., pp. 381–384 (in Japanese).
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