ASME Turbo Expo 2009: Power for Land, Sea, and Air
Thermohydrodynamic Analysis of
Bump Type Gas Foil Bearings: A
Model Anchored to Test Data
Luis San Andrés
Mast-Childs Professor
Tae Ho Kim
Research Associate
Texas A&M University
ASME GT2009-59919
Accepted for J. Eng. Gas Turbines Power (In-Press)
This material is based upon work supported by NASA Research Announcement
NNH06ZEA001N-SSRW2, Fundamental Aeronautics: Subsonic Rotary Wing
Project 2 # 32525/39600/ME and the Turbomachinery Research Consortium
Gas Foil Bearings – Bump type
 Series of corrugated foil structures
(bumps) assembled within a bearing
sleeve.
 Integrate a hydrodynamic gas film in
series with one or more structural layers.
PROVEN TECHNOLOGY!!
Applications: Aircraft ACMs, micro gas
turbines, turbo expanders, turbo compressors,
 Damping from dry-friction and operation with
limit cycles
 Tolerant to misalignment and debris, also
high temperature
 Need coatings to reduce friction at start-up &
shutdown
 Often need cooling flow for thermal
management of rotor-GFB system
Gas Foil Bearings (+/-)
 Increased reliability: large load capacity (< 100
psi)
 No lubricant supply system, i.e. reduce weight
 High & low temperature capability (up to 1,200º F)
 No scheduled maintenance with increased life
 Less load capacity than rolling or oil bearings
 Thermal management (cooling) issues
 Little test data for rotordynamic force
coefficients
 Predictive models lack validation.
Difficulties in accessing full test data – geometry
and operating conditions
Overview – GFB computational models
 Heshmat (1983), Carpino and Talmage (2003, 2006), Kim and San
Andrés (2005, 2007), Lee, et al. (2006), Le Lez, et al. (2008):
Predict static/dynamic performance of bump-type GFBs with isothermal
flow model and simple to complex foil models
Thermohydrodynamic (THD) model predictions:
 Salehi et al. (2001): Couette flow approximation to estimate bearing
temperatures.
 Peng and Khonsari (2006): Thermal management of GFB from cooling
gas stream underneath top foil.
 Le Lez et al. (2007): Nonlinear elastic bump model. THD model predicts
larger load capacity than isothermal flow model.
 Feng and Kaneko (2008), San Andrés and Kim (2009): FE top foil &
support structure model. Predicted bearing temperatures in agreement with
test data (Radil and Zeszotek, 2006), obtained at room temperature (~21°C)
without cooling flow.
Overview – Rotordynamic measurements
 Ruscitto et al (1978): Load
capacity tests on simple GFB. Full
test data & bearing geometry
 Heshmat (1994):
Demonstrates maximum speed of 132 krpm,
i.e. 4.61 ×106 DN. Ultimate specific load (~100 psig). Most
designs operate at 10 psig or below.
 DellaCorte and Valco (2000):
Review open literature and estate
Rule of Thumb to estimate load capacity of GFBs.
 San Andrés et al. (2006, 2008):
Large imbalances cause
subsync. whirl motions due to FB structure hardening.
 Radil and Zeszotek (2006):
Measure temperatures in foil
bearing operating with changes in load and rotor speed.
 Salehi et al. (2001) :
Measure temperatures in foil bearing
operating with axial cooling stream flow.
Foil Bearing Research at TAMU
2003-2009: Funded by NSF, Capstone Turbines, NASA GRC,
Turbomachinery Research Consortium
Test Gas Foil Bearing (Bump-Type)
Generation II. Diameter: 38.1 mm
25 corrugated bumps (0.38 mm of height)
Reference: DellaCorte (2000)
Rule of Thumb
T∞
THD model
GFB with
cooling flows
Outer flow
stream
x z
Bearing housing
“Bump” layer
Bearing housing
Top foil
PCo, TCo
Pa
Thin film flow
(inner and outer)
ΩRSo
PCi, TCi
Inner flow
stream
Y
Z
z=0
z=L
X
Hollow shaft
Gas film Reynolds equation with inlet swirl effect
3
 Pf    h3f Pf
 Pf 
  h f Pf
  Pf h f

  
  U m ( z )

 x  12 f  gT f  x   z  12 f  gT f  z 
 x   gT f



THD model governing equations
Side view of GFB with hollow shaft
X=RΘ
Top foil
Bump strip layer
Hollow shaft
Y
Thin film flow
- Gas viscosity,
 v T
- Gas Specific heat (cp)
and thermal conductivity
(κg) at an effective
temperature
Bearing housing
External fluid
medium
X
  P T
g
Inner flow stream
Outer flow stream
Ω
- Ideal gas with
density,
Bulk-flow film temperature transport:




   f hf U f Tf
  f hf Wf Tf 
  h fF T f  TF  hSf TS  T f
cpf 

i
o


x
z


 Pf
 Pf  12 f  2 1

2
  U f h f
Wf hf

W

U

U

U

 f
m
f
m 

x

z
h
3

f 








Convection of heat by fluid flow + diffusion to bounding surfaces = compression work + dissipated energy
Numerical solution procedure
Configuration of control volume for
integration of flow equations (Ψ = Pf or Tf)
x
Bulk-flow equations of continuity,
momentum and energy transport
x
 M  e   M   w   M   n   M   s  S
ΨN
Axial direction
Mn
ΨW
Ψw
Mw
Ψn
ΨP
Ψs
Ms
Control
volume
Ψe
Me
z
(n, s, e, w denote the north, south, east and west faces )
ΨE
 1
Conservation of mass equation
  U x Transport of circ. momentum velocity
z
ΨS
Circumferential direction
Subscripts E,W,N,S for east, west, north, and south
nodes; and subscripts e,w,n,s for east, west, north, and
south faces of control volume
  U z Transport of axial momentum velocity
 T
Transport of energy
S : Source term
Numerical solution of Reynolds and
thermal energy transport equations
implement exact advection control
volume model (Faria and San
Andrés, 2000)
Ω
Heat flux paths in rotor - GFB system
Heat flow
model
Heat conduction
through shaft
RSi
QCi
RSo
Hollow
shaft
TCi
TSi
QSC
Heat carried
by inner flow QSi
stream
RFi RFo
Top
foil
Bump
layer
RBo
Bearing
housing
External
fluid
dӨ
Ω
TS
TSo
Tf
QCo
QSo
QS f
TFi
TFo
Qf F
TO
QF
TBi
Q
Heat
F O
carried by
thin film
flow
RBi
QB
Drag
dissipation
power (gas
film)
TBo
QF Bi
QB
QOBi
QB
Heat carried
by outer flow
stream
Simple
representation
in terms of
thermal
resistances
within a GFB
supporting a
hot hollow
shaft
T∞
Heat conducted
into the bearing
Cooling gas
stream
carries away heat
Q =Rq
: Heat
(+)
: Heat
(-)
Equivalent heat transfer coefficients
Without outer cooling flow stream
: Heat transfer from film flow to outer bearing cartridge
1
heqB

1
1


F

h fF
RBi
 hFo  hBo
tF

RFi

1




 B RFi
 F RBeq
Gas film -> top foil ->
1
R 
RFi ln  Bo 
RBi 



bump strip layer
B
RFi
hB RBo
-> bearing cartridge
With outer cooling flow stream (simplified model)
: Heat transfer from film flow to outer cooling flow
1
heqO
RFi
tF
1



h fF  F RFo hFO
Gas film -> top foil -> outer cooling flow
With inner cooling flow stream
: Heat transfer from film flow to inner cooling flow
 RSi
RSo ln 
RSo
1
1



S
heqc hSf


  RSo
hSc RSi
Gas film -> hollow shaft -> inner cooling flow
Thermal energy mixing process
At gap in between trailing and leading edge of top foil.
R
Inlet (mixing)
air flow
Fresh air
flow
Recirculation
air flow
Ω
mup
Tup
top foil
Upstream end
(trailing edge)
mInlet
TInlet
msupply
Tsupply
Thin foil
Journal
Y
Structural
bump
Housing
top foil
X
Downstream pad
(leading edge)
mass conservation and energy balances at feed gap:
mInlet =  mup  mSupply
mInletTInlet =  mupTup + mSupplyTSupply
λ : empirical thermal mixing coefficient
enforced. Top foil detachment doest not allow for gas
Pf  Pa film pressure to fall below ambient pressure. No
ingress of fresh gas
Balance of thermal energy transport
Width of arrow denotes
intensity of energy transport
11 %
Advection of heat by
gas film flow
Conduction into
bearing cartridge
2%
Dissipated energy
+
compression work
Forced heat convection
into outer cooling
stream
100%
Heat conduction
into shaft
5 %
Example only
82 %
Model Validation: geometry & operating conditions
GFB model: Generation I GFB with single top foil and bump strip layer
Parameters
Value / comment
Parameters
Value
Gas properties at 21 °C
Bearing cartridge
Bearing inner radius
25 mm Ref. [7]
Gas Constant
Bearing length
41 mm Ref. [7]
Viscosity
Bearing cartridge thickness
5 mm Assumed
Nominal radial clearance
20 μm Assumed
Top foil and bump strip layer
Conductivity
287 J/(kg-°K)
10-5 Pa-s
0.0257 W/m°K
Density
1.164 kg/m3
Top foil thickness
127 μm Ref. [21]
Specific heat
1,020 J/kg°K
Bump foil thickness
127 μm Ref. [21]
Ambient pressure
1.014 x 105 Pa
Bump half length
1.778 mm Assumed
Bump pitch
4.064 mm Assumed
Bump height
0.580 mm Assumed
Number of bumps x strips
Bump foil Young’s modulus
Bump foil Poisson’s ratio
Bump foil stiffness
Gas viscosity, density &
conductivity, foil material
props., and clearance
change with temperature
39 x 1 Assumed
200 GPa
0.31
10.4 GN/m3
Ref. [7, 21]:
Radil and Zeszotek, 2004
Dykas and Howard, 2004
Predicted peak film temperature
Ω
Load
240
Peak temperature [° C]
50,000 rpm
200
40,000 rpm
Tshaft=Tbearing =Tambient = 21 °C
160
30,000 rpm
120
20,000 rpm
80
40
Test data
(Mid-plane)
0
0
50
100
Static load [N]
200
Series4
Comparison
to test data (Radil
50,000 rpm
and Zeszotek, 2004)
Test data - 30 krpm
40,000 rpm
Test data - 40 krpm
Predictions
(Mid-plane)
150
Static load (vertical:180°)
Test data - 50 krpm
rpm °C
30,000
TSupply
=21
250
300
Series10
20,000 rpm
Predictions - 30 krpm20um_0.6_20
W/LD= 16 psi= 1.1
data
Testbar
Predictions
Predictions - 40 krpm20um_0.6_20
(Mid-plane)
(Mid-plane)
Peak film temperature grows as static load increases
and as rotor
Predictions - 50 krpm20um_0.6_20
speed increases.
Peak film temperatures higher than ambient temperature, even for
small load of 9 N.
Mid-plane & edge film temperatures
Ω
Load
Peak temperature [° C]
240
200
Predictions
(Mid-plane)
Predictions
(Edge)
160
40,000 rpm
Tshaft=Tbearing =Tambient = 21 °C
Static load (vertical:180°)
.
120
20,000 rpm
80
Predictions
Comparison
to test data (Radil
Series4
Predictions
(Mid-plane)
40,000 rpmand Zeszotek, 2004)
(Edge)Series7
40
Test data
(Mid-plane)
Test data
(Edge)
0
Test data - 40
krpm
Series5
TSupply20,000
=21 rpm
°C
Series10
0
50
100
150
200
250
300
Series3
Static load [N]
Test
Test data
data
(Mid-plane)
Predictions - 40
(Edge)
krpm-
20um_0.6_20 (axial
Difference in film temperatures at mid-plane and edge
Series1
thermal gradient) increases as rotor speed increases.
Higher film temperatures at bearing mid-plane evidence absence of
axial cooling flow path
Film axial temperature
Ω
Load
Temperature [°C]
200
Test data
Test data
Predictions
Tshaft=Tbearing =Tambient = 21 °C
40,000 rpm
150
Static
load 133 N (vertical:
Predictions
180°) for rotor speeds: 20 - 40
30,000 rpm
100
40,000 rpmSerie
20,000 rpm
krpm.
s8
W/LD=
9.5 psi= 0.64 bar
Serie
s4
30,000 rpmSerie
s5
50
Comparison
to test data (Radil
Serie
s7
20,000 rpm and Zeszotek, 2004)
Serie
s3
TSupply=21 °CSerie
s1
0
1
Side
edge
(rear)
6
AxialMid-plane
node
11 number
16
Side edge
21
(front)
- Edges
Film temperature is maximum at bearing mid-plane, and drops
slightly at side edges (circumferential angle ~190°).
Predictions in good agreement with test values
More predictions of GFB performance
Gas film (a) pressure and (b) temperature fields
Dimensionless
pressure, p/pa
(a) Pressure
Ω
Load
Axial node
number
Circumferential angle
[deg]
Temperature [° C]
P
(b)
(b) Temperature
Temperature
Axial node
number
Circumferential angle [deg]
Static load: 89N
20 krpm
W/LD= 6.32 psi= 0.43 bar
Tshaft=Tbearing =Tambient = 21 °C
0 < θ < 200 °:
Temperature rises due
to shear induced
mechanical energy
θ > 200 °:
Temperature drops due
to gas expansion
(cooling gas film)
Dimensionless pressure, p/pa
Film pressure and temperature at mid-plane
3
222 N
(a) Pressure
222 N
2.5
178 N
133 N
89 N
44 N
9N
2
1.5
1
178 N
Static load
increases
133 load
N
Static
increases
89 N
Tshaft=Tbearing =Tambient = 21 °C
44 N
9N
Predictions - 40
krpm20um_0.6_20
Series1
Ω
Load
0.5
Series2
0
Series3
0
90
180
270
360
120
Temperature [° C]
At 20 krpm
Circumferential angle [deg]
(b) Temperature
Static load
222 N
100
increases
178 N
133 N
89 N
44 N
9N
80
60
Series4
Series5
Both peak pressure and
Static load
increases
temperature
increase as
static load increases.
Predictions - 40
krpm20um_0.6_20
Series1
222 N
40
Note peak film
temperature
at trailing
133 N
89 N
edge of top foil with
44 N
smallest load of 9 N.
178 N
Series2
TSupply=21 °C
20
0
90
180
270
Circumferential angle [deg]
360
Series3
Series4
Series5
Radial peak temperature profile
Ω
Load
Tf
TSi
TSo
80
TFo
TBi
TBo
70°C
67°C
70
68°C
Tshaft=Tbearing =Tambient = 21 °C
60
50
Static load 89 N
rotor speed= 20 krpm
40
30
Ω
Temperature [°C]
TFi
20
10
TCi
T∞
TCo
Radial direction
0
So
1 1. 2 2.RSi 3 3. 4 R4.
5RFi 5.RFo 6 R6.Bi 7 7. RBo8 8. 9
5
5
5
5
5
5
5
5
Hollow
shaft
Top
foil
Bump
layer
Radial location
Bearing
housing
External
fluid
dӨ
Natural convection
on exposed surfaces
of bearing OD and
shaft ID
Without forced cooling streams, GFB shows nearly uniform
radial temperature distribution.
Predicted static load performance
Ω
Load
Isothermal
20
THD
c' = 17 μm
15
25
20
15
10
THD
5
10
5
Isothermal
0
0
0
50
100
150
200
250
Minimum film thickness [μm]
Journal eccentricity [μm]
25
Isothermal
THD
40 krpm
Tshaft=Tbearing =Tambient = 21 °C
c' = 17 μm
THD
Series7
Series5
Isothermal
300
Series2
Static load [N]
W/LD= 16 psi= 1.1 bar
Series1
As static load increases, journal eccentricity increases and
minimum film thickness decreases.
Larger minimum film thickness (smaller journal eccentricity)
for THD model .
Predicted static load performance
Ω
Load
0.03
80
70
THD
60
0.02
Isothermal
50
40
30
0.01
20
Drag torque [N-m]
Journal attitude angle [deg]
90
40 krpm
Tshaft=Tbearing =Tambient = 21 °C
Series5
Isothermal
10
Series7
THD
0
0
50
100
150
200
Static load [N]
250
0.00
300
Series1
W/LD= 16 psi= 1.1 bar
Series2
As static load increases, journal attitude angle decreases and
drag torque slightly increases.
Larger drag torque and smaller journal attitude angle for THD
model .
Conclusions
ASME GT2009-59919
GFB model with thermal energy transport, axial cooling flow, and
thermoelastic deformation of top foil and bump strip layers
Predicted film peak temperature increases as static load
increases and as rotor speed increases

Difference in predicted film temperatures at mid-plane and
edge (axial thermal gradient) increases as rotor speed
increases.
 THD model predicts smaller journal eccentricity (larger
minimum film thickness) and larger drag torque than
isothermal flow model

Model predictions benchmarked against published test
data !!

09 AHS paper shows predictions with cooling flow and
rotordynamic measurements in a HOT rotor-GFB test rig
Acknowledgments

NASA GRC
NASA Research Announcement NNH06ZEA001N-SSRW2,
Fundamental Aeronautics: Subsonic Rotary Wing Project 2 #
32525/39600/ME
Thanks to Dr. Samuel Howard for his interest and support

Turbomachinery Research Consortium
Learn more: Visit http://phn.tamu.edu/TRIBGroup
More predictions
Forced cooling flows - Film temperature
Temperature [°C]
Temperature field
Tshaft=Tbearing =Tambient = 21 °C
Ω
Static load 89 N (vertical)
rotor speed= 20 krpm.
Load
(a) Without cooling flow
Temperature field
Axial node
number
Circumferential angle [deg]
Temperature [°C]
T
(b) Outer cooling flow
(350 lit/min)
Outer
cooling
flow
Bearing
cartridge
Hollow shaft
Ω
Temperature field
Axial node
number
T
Temperature [°C]
T
Axial node
number
Circumferential angle [deg]
(c) Inner (350 lit/min) and outer
(350 lit/min) cooling flows
Bearing
cartridge
Outer
cooling
flow
Hollow shaft
Inner
cooling
flow
Circumferential angle [deg]
Ω
With forced cooling
streams, inlet gas
film temperature at ~
0 deg (top foil leading
edge) and peak film
temperature at ~ 200
deg decrease
significantly
Radial peak temperature profiles
Ω
Load
Tf
TSi
TSo
80
TFo
TBi
TBo
70°C
66°C
70
68°C
Tshaft=Tbearing =Tambient = 21 °C
(a) Without cooling flow
60
Static load 89 N (vertical)
rotor speed= 20 krpm
50
40
38°C
30
33°C
20
10
(b) Outer cooling flow
(350 lit/min)
40°C
38°C
Ω
Temperature [°C]
TFi
TCi
37°C
35°C
T∞
TCo
(c) Inner (350 lit/min) and outer (350
lit/min) cooling flows
Radial direction
0
So
1 1. 2 2.RSi 3 3. 4 R4.
5RFi 5.RFo 6 R6.Bi 7 7. RBo8 8. 9
5
5
5
5
5
5
5
5
Hollow
shaft
Top
foil
Bump
layer
Radial location
Bearing
housing
External
fluid
dӨ
Natural convection
on exposed surfaces
of bearing OD and
shaft ID
With forced cooling streams, GFB operates 30 °C cooler.
Outer cooling stream is most effective to take away heat from
the back of the top Foil.
Advection of heat by gas film
flow - AXIAL (20.2 W)
(a) Without cooling flow
57.5%
Heat conduction into
bearing cartridge (3.09 W)
Mechanical
dissipated energy
(43.35 W)
+ compression
work (-8.23 W) =
8.8%
Natural heat convection
into outer gap (4.11 W)
35.12 W
Static load 89 N (vertical)
rotor speed= 20 krpm
11.7%
100%
Heat conduction
into shaft (7.72 watt)
22.0%
(b) Outer cooling flow
(350 lit/min)
11.2%
Ω
Load
1.5%
81.9 %
Forced heat convection
into outer cooling
stream (23.46 W)
work (- 7.64 W) =
28.66 W
Heat conduction
into shaft (1.57 W)
5.5 %
(c) Inner (350 lit/min) and outer
(350 lit/min) cooling flows
Conduction into bearing
cartridge (0.35 W)
1.2%
67.4 %
Forced convection to
outer cooling stream
(19.53 W)
28.46 W
100%
19.5%
Without cooling flow stream,
~ 58% of heat carried by gas film flow.
~12% convected naturally at back of top foil.
~ 31% conducted into bearing and shaft
With outer cooling flow stream,
11.9% Advection of heat by gas
flow (3.39 W)
Dissipated energy
(36.06 W)
+ compression
work (-7.60 W) =
Tshaft=Tbearing =Tambient = 21 °C
Advection of heat by gas film
flow (3.21 W)
Conduction into bearing
cartridge ( 0.43 W)
Dissipated energy
(36.31 W)
+ compression
100%
Thermal energy
transport & balance
Conduction thru shaft and forced
convection into inner cooling
stream (5.55 W)
~11% of heat advected by the gas film.
~82% carried by outer cooling stream. ~
7% conducted into bearing and shaft.
Inner cooling flow stream aids to further cool
gas film
Effect of strength of cooling stream
Cooling flow rate
increases
Peak temperature [° C]
Laminar flow
150
Outer cooling flow
100
ReD = 2300
No cooling
flow
Static load 89 N (vertica)
rotor speed= 20 krpm
Turbulent flow
Tshaft=Tbearing =
Tambient = 21 °C
40,000 rpm
50
Inner and outer
cooling flows
20,000 rpm
TSupply=21 °C
0
0
100
200
300
400
Cooling flow rate [lit/min]
Peak film temperature decreases with strength of cooling stream.
Sudden drop in temperature at ~ 200 lit/min (flow transitions from
laminar to turbulent flow conditions)
TAMU Hot GFB
Rotordynamic Test Rig
Hot GFB rotordynamic test rig
Test rig with a cartridge heater and instrumentation for
operation at high temperature
Infrared
thermometer
Insulated
safety cover
Tachometer
Eddy current
sensors
Hot heater inside
rotor spinning 30
krpm
Drive
motor
Cartridge
heater
Test hollow shaft
(1.1 kg, 38.1mm OD,
210 mm length)
Test
GFBs
Flexible
coupling
Drive motor (max. 65 krpm). Cartridge heater max. temperature: 360C
Air flow meter (Max. 500 L/min),
Schematic view of instrumentation
Drive end (DE) GFB
Free end (FE) GFB
Insulated safety cover
45º
45º
T1
T2
T6
g
g
Ω
Ω
Tamb
T7
T9
T4
T3
T12
T11
T5
Hollow
shaft
T8
T10
Coupling
cooling air
Th
T16
T14
T15
Drive motor
Cartridge heater
Heater stand
Cooling air
T13
Foil bearings
15 thermocouples : (4x2) GFB cartridges, (2) Bearing support housing surface,
(3) Drive motor, (1) Test rig ambient and (1) Cartridge heater +
Two noncontact infrared thermometers for rotor surface temperature
Cooling gas flow into GFBs
Side feed gas pressurization
(Max. 100 psi)
AIR SUPPLY
Typically foil
bearings DO not
require
pressurization.
Cooling flow needed
for thermal
management to
remove heat from
drag or to reduce
thermal gradients in
hot/cold engine
sections
Effect of cooling flow on heater temperature
High temp. (heater up to 360C). Cooling flow up to 150 L/min
Fixed rotor speed : 30 krpm
heater temperature
400
21C
Heater temperature, Th [ºC]
350
100C
360C
300C
200C
Th
300
No cooling&
50L/min
No cooling
Free End
100L/min Drive End
T1
T6
200L/min
300L/min
T11
250
200
100L/min
150
150L/min
Th
Due to limited heater power
100
T11
50
0
0
20
40
60
80
100
120
Time [min]
Cooling rates > 100 LPM cool the heater!
T12
Effect of cooling flow on bearing temperatures
High temp. (heater up to 360C). Cooling flow up to 150 L/min
Bearings temperature raises
Fixed rotor speed : 30 krpm
70
Cooling method
is effective for
flows above 100
L/min and when
heater at highest
temperature
21C
Temperature rise [ºC]
60
100C
360C
300C
200C
T1-Tamb
50
T6-Tamb
40
T1-Tamb
Cooling flow
increases
30
T6-Tamb
20
T1-Tamb
10
T6-Tamb
Th
Free End
T1
Drive End
T6
0
0
20
40
60
Time [min]
T11
T12
80
100
120
T
T
T1: FEflow
GFB cartridge
outboard
Effect of cooling
on
bearing temperature
T6: DE GFB cartridge outboard
High temp. (heater up to 360C). Cooling flow up to 150 L/min
Fixed rotor
speed : 30 krpm
35
Cooling flow
increases
30
Series3
Turbulent flow
> 100 LPM
Series2
Series4
Series1
Temperature rise [ºC]
25
Series6
200C
Series7
T6-Tamb
20
T1-Tamb
15
100C
10
No heating
5
Cartridge temperature
(Ths) increases
0
0
50
100
150
Th
Free End
T1
Drive End
T6
Cooling flow rate [L/min]
Bearing cartridge
temperature
T11
T12
Rotor OD temperature decreases with cooling flow rate.
TAMU predictions vs test data
Heat flux
60
DE Shaft and GFB
Bearing temperature rise [ºC]
(Shaft → bearing,
Shaft → outer stream)
45 °
50
Hot shaft
No cooling
DE GFB-test data (Isothermal)
Θ
DE GFB-predictionsOuter cooling
40
stream
Predictions
30
Series1
Ω
Series2
50L/min
Test data
Series5
20
125L/min
100L/min
g
Series6
Y
Spot weld
Bump strip
layer
Top foil
Bearing
cartridge
Series7
10
X
150L/min
Series8
0
0
20
40
60
Shaft temperature rise [ºC]
80
100
Measurements at
cartridge
outboard #T6.
TCo~21 °C.
Static load ~ 6.5 N,
30 krpm
Bearing & rotor cartridge temperatures
Code Executable & GUI :
for licensing by TAMU
Graphical User Interface (GUI)
Graphical User Interface (GUI)
INPUT DATA
Graphical User Interface (GUI)
OUTPUT DATA
ch 2nd GEN GAS FOIL BEARING
Radial
temperature distribution
Radial direction
Foster-Miller Tech 2nd GEN GAS FOIL BEARING
Peak temperature vs Load
Peak Temperature
Peak Temp
160.0
240.0
Mean Temp
Peak temperature [degC]
140.0
120.0
100.0
80.0
60.0
40.0
Ω
Temperature [degC]
180.0
20.0
0.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
Radial location
Hollow
shaft
Top
foil
Bump Bearing
layer housing
External
fluid
200.0
160.0
120.0
80.0
40.0
dӨ
0.0
0.00
10.00
20.00
30.00
40.00
Load-X [N]
50.00
60.00
70.00