International Journal of Engineering Trends and Technology (IJETT) – Volume X Issue Y- Month 2013
Analysis of Pressure for 3lobe Hydrodynamic Journal Bearing
Dinesh Dhande1, Dr D W Pande2, Vikas Chatarkar3
1. Assistant Professor, AISSMS College of Engineering, Pune -1
2. Professor and Dean R&D, College of Engineering, Pune-5
3. Assistant Professor, RMD Sinhgad College of Engineering,Pune
Abstract— Hydrodynamic multilobe journal bearings are
analysed by using Computational fluid dynamics (CFD). Journal
bearing models are developed for different speeds and
eccentricity ratios to study the static pressure effect and elastic
behaviour of the bearing. The static pressure find out from CFD
analysis are use to find out force acting at center of bearing.
Cavitations in the bearing are neglected by setting all negative
pressures to ambient pressures. The CFD results were compared
in order to validate the model with the experimental work
carried by Ferron et al [8] and a good agreement were found. It
is observed that static pressure and force at the centre of bearing
increase with increasing eccentricity ratio or by increasing
angular velocity for considering or neglecting negative pressure
It is observed that the static pressure of the bearing are
significant and should be considered in order to predict accurate
performance of the hydrodynamic journal bearings.
Keywords— Force, Static Pressure, multilobe bearing
II. ANALYSIS
The geometry and the co-ordinate system of the plain and
multilobe journal bearing are as shown in fig 1 and fig 2
respectively. The journal rotates with a angular velocity, 
which lead to attitude angle The journal remains in
equilibrium position under the action of external load, W
which lead to eccentricity and developed hydrodynamic
pressure. The journal centre O is eccentric to the bearing
centre O’. The film thickness h() varies from its maximum
value hmax at bearing angle  = 0 to its minimum value, hmin
at  = .
Y

h max
I. INTRODUCTION
Recently output of internal combustion engine has
been increased and their weight has been reduce As result of
this bearing is used under the very severe operating condition
and deformation of housing of connecting rod big-end bearing
and main bearing have a significant influence upon the
bearing characteristics. It increases the bearing load. The
increase in the bearing loads and the desire to reduce the
dimensions and component masses in modern combustion
engines. These all responsible for modification in bearing. To
meet this requirement symmetrical lobe has been develop and
it is found that it will be more stable than plain and other
recess bearing. It create more pressure generate thin oil film
that separate shaft and bearing and prevent metal to metal
contact.
Lots of Study is done on multi lobe bearing
Stanislaw Strzelecki [1] worked on “Effect of lobe profile on
load capacity of 2-lobe journal bearing “. Stanislaw Strzelecki
and Sobhy M Ghonheam[2] worked on “dynamically loaded
cylindrical journal bearing with recess ” . Both also somewhat
worked on “Thermal problem of multilobe bearing
tribosystem” J D Knight and L E Barret [3] worked on
“Approximate solution technique for multi lobe journal
bearing with thermal effect with comparison to experiment”.
Dr G Bhushan and Dr S Ratan Dr N P Mehata worked on
“Effect pressure Dam And relief track on performance of four
lobe bearing”
ISSN: 2231-5381
W
Rb
X
O'
Rj
e
O


h min

Fig 1. Schematic of Journal bearing geometry
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Fig 2. Schematics of Multi Lobe Bearing
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International Journal of Engineering Trends and Technology (IJETT) – Volume X Issue Y- Month 2013
III. MATHEMATICAL FORMULATION
Mathematical model is made with help of Governing
equation and combination of dependant and independent
variable and relative parameter in the form of set of
differential equation which differ physical phenomenon for
approximation and idealization. Transport equation for
standard K-ԑ model is:
Where turbulence velocity
In this Equation Gk represent generation turbulence
kinetic energy due to mean velocity gradient, Gb represent
generation turbulence kinetic energy due to buoyancy
IV. ASSUMPTIONS
Initially a journal bearing with rigid bushing as
shown in fig.1 is considered in order to find hydrodynamic
forces with steady state condition. The flow is laminar and
isothermal and a constant vertical load W is applied on the
journal.
V. METHODOLOGY
Main objective in this case is to find out maximum
static pressure for different eccentricity and different Angular
speed RPM and whatever may be the force at the centre of
shaft for these respective different eccentricity and RPM
VI. GEOMETRICAL MODEL
The bearing dimensions for schematic diagram fig 2
used in the present work are as given below:
TABLE I
JOURNAL BEARING PROPERTIES
Symbol
Quantity
Values
Rb
Journal Radius
50 mm
L
Bearing Length
80 mm
C
Radial Clearance
145 m
Rl
Lobe Radius
4mm
Angle between lobes
1200
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N
Rotational Speed Range
4000- 10000
RPM

Lubricant viscosity
0.0277 Pa-sec

Lubricant density
860 kg/m3
Cp
Lubricant Specific Heat
2000 J/kg C
Using above dimension geometry is created in
CATIA V5 R20. The step file of geometry is use for meshing.
The mashing is done in Hypermesh 10.0 and boundary
condition is provided in Gambit 2.4.6 software For meshing,
the fluid ring is divided into two connected volumes. Then all
thickness edges are meshed with bearing (100×3) and lobe
(20×3) intervals i.e 360 interval for total bearing, and then
volumes are meshed with the “Hex/Wedge e cooper” method.
A hexahedral structure mesh is used. 100 divisions were taken
along the length. So the total number of elements is
approximately 75840. As the load is assumed to be constant,
the eccentricity ratio depends on the pressure equilibrium over
the journal surface. The mesh was generated for different
values of eccentricity ratios from 0.2 mm to 0.8. The mesh
quality is always around 0.5 for all generated elements where
as aspect ratio is less than 20 for all cases.
After providing boundary condition .msh file is
imported in Ansys fluent for CFD analysis First of all find out
pressure contour by considering negative pressure and then for
this .cas and .dat file Using User define function (UDF)
neglect negative pressure.
VII.
BOUNDARY CONDITIONS
The bearing wall is considered as stationary and
journal is modelled as moving wall. The sides of the lubricant
volume have been assigned with a zero pressure condition,
meaning that the lubricant is free to flow there. The cavitation
within the lubricant was modelled using the half Sommerfeld
boundary condition.
The half Sommerfeld condition, utilized in the
present work, neglects all negative pressures in the diverging
part of the fluid film, which are physically unrealistic. The
half Sommerfeld condition, offers sufficient accuracy, fast
convergence, and is selected in this work to accelerate the
solution of the CFD problem. The use of zero pressure
boundary condition at the sides of the bearing implies the
leakage of the lubricant at the sides. The boundary condition
for entry of the lubricant would simply be unnecessary
because of the half Sommerfeld boundary condition. In other
words, since the lubricant enters the bearing space at
atmospheric pressure, a separate boundary condition for the
lubricant inlet would be overplayed to half Sommerfeld and
thus would be redundant. The Reynolds boundary condition,
not utilized here, assumes that the positive pressure curve
terminates with a zero gradient in the divergent part of the
film; it gives in some cases more accurate results than the half
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International Journal of Engineering Trends and Technology (IJETT) – Volume X Issue Y- Month 2013
Sommerfeld boundary condition. Nonetheless, it is still an
approximation to the transition from single-phase flow to
multi-phase flow, and is computationally more demanding.
The external surface of the bearing was fixed. The lubricant
film was created in the CFD module of the software.
(Journal) at constant 4000rpm angular velocity along
circumferential direction
Case2: For different RPM on Shaft (Journal) at constant 0.6
VIII.
RESULTS
Static pressure for different cases is as follows:
Case 1: For Different eccentricity ratio on shaft
(Journal) at constant 4000rpm angular velocity
eccentricity ratio
Fig5 Static Pressure by considering negative pressure
Fig 5 shows Static Pressure increase with increasing angular
velocity RPM by considering negative pressure at constant 0.6
eccentricity ratio
Fig3 Static pressure by considering negative pressure
Fig3 shows Static pressure increase with increasing
eccentricity ratio by considering negative pressure shaft
(Journal) at constant 4000rpm angular velocity along
circumferential direction
Fig4 Static pressure by neglecting negative pressure
Fig 4 shows Static pressure increases with increasing
Eccentricity ratio by neglecting negative pressure for shaft
Fig.6 Static pressure by neglecting negative pressure
Fig 6 shows Static Pressure increase with increasing angular
velocity RPM by neglecting negative pressure at constant 0.6
eccentricity ratio
Forces calculation cases are as follows:
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International Journal of Engineering Trends and Technology (IJETT) – Volume X Issue Y- Month 2013
TABLE II
FORCES FOR D IFFERENT ECCENTRICITY AT CONSTANT 4000 RPM
Eccentricity
0.2
0.4
0.6
0.8
Considering
negative
pressure
neglecting
negative
pressure
Force(N)
Force(N)
808
2342
9088
27244
76
285
1713
4272
Fig:8 Static pressure contour for Shaft by considering negative
pressure
Attitude
Angle
14.6
29.1
40
59.5
TABLE III
FORCES FOR D IFFERENT LOAD AT CONSTANT 0.6 ECCENTRICITY RATIO
RPM
4000
6000
8000
10000
Considering
negative
pressure
Neglecting
negative
pressure
Force (N)
9088
13772
18567
23628
Force(N`)
1713
2507
1996
3675
Fig:9 Static pressure contour for bearing by neglecting negative
pressure
Attitude
Angle
40
40
40
40
From both table we can conclude that force increase with
increasing eccentricity ratio at constant angular velocity and
force in increase with increasing angular velocity at constant
eccentricity ratio
Fig7 and fig 8 shows static pressure contour by
considering negative pressure at 4000 rpm and 0.2 eccentricity
Fig 9 and fig 10 shows static pressure contour by neglecting
negative pressure at 4000 rpm and 0.2 eccentricity
Fig7 Static pressure contour for bearing by considering negative pressure
Fig:10 Static pressure contour for Shaft by neglecting negative
pressure
IX. CONCLUSION
The static pressure distribution having maximum
value in 3 lobe bearing than simple bearing As the static
pressure increases it increase force at the centre of bearing.
The pressure distribution increase in 3lobe bearing with
increasing eccentricity and with increasing angular velocity. It
conclude that the load carrying capacity of lobe bearing is
more than the plain bearing and result show that presence of
lobe highly effect the performance of bearing
X. ACKNOWLEDGMENT
Author’s are thankful to Mr.Raj Gadvi, CAE Engineer ,
Vieston India Ltd, Pune for his help during meshing
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International Journal of Engineering Trends and Technology (IJETT) – Volume X Issue Y- Month 2013
XI. REFERENCES
Stanislaw Strzelecki, “Effect of lobe profile on load
capacity of 2-lobe journal bearing” july 5 2001Institute
of Machine Design, Poland, vol 44, supp.
[2] Stanislaw
Strzelecki
and
Sobhy
M
Ghonheam,“ dynamically loaded cylindrical journal
bearing with recess ” journal of kone international
combustion engin2004 vol 11pg 3-4
[3] J D Knight and L E Barret worked on “Approximate
solution technique for multi lobe journal bearing with
thermal effect with comparison to experiment”, vol 26,
issue 4, oct 1983, pg 331-339
[4] Mahesh Aher, Sanjay Belkar, R R Kharde,” Pressure
distribution analysis of plain journal bearing with lobe
journal bearing” IJERT, vol 2, Issue-1, Jan 2013, pg 4-5
[1]
[5] J. Ferron, J. Frene, R. Boncompain ,”A Study of the
Thermohydrodynamic Performance of a Plain Journal
Bearing Comparison Between Theory and Experiments” ,
Transactions of the ASME, Vol. 105, JULY 1983,
pg.422-428.
[6] Evgeny Kuznetsov a, Sergei Glavatskih a, b, n, Michel
Fillon, “THD analysis of compliant journal bearings
considering liner deformation”, Tribol Lett (2011) , doi:
10. 1016/ j. triboint. 2011 .05 .013
[7] Nabarun Biswas S K Hikmat, “Transient Analysis of 3
lobe bearing At 8000 rpm for Gas turbine” IJMECH, Vol
2, No 1, Feb 13 pg 22-30
[8] Qiang LI, Shu-lian LIU, Xiao-hong PAN, Shui-ying
ZHENG,” A new method for studying the 3D transient
flow of misaligned journal bearings in flexible rotorbearing systems, Journal of Zhejiang UniversitySCIENCE A (Applied Physics & Engineering), 2012
13(4):293-310.
[9] K.P.
Gertzos,
P.G.
Nikolakopoulos,
C.A.
Papadopoulos,”CFD analysis of journal bearing
hydrodynamic lubrication by Bingham lubricant”,
Tribology International 41 (2008) 1190– 1204
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