1 Luis San Andrés Mast-Childs Professor, Fellow ASME Texas A&M University On the Effect of Thermal...

1

Luis San AndrésLuis San AndrésMast-Childs Professor, Fellow ASME Texas A&M University

On the Effect of Thermal Energy Transport to the Performance of (Semi) Floating Ring Bearing Systems for Automotive Turbochargers

ASME Turbo Expo 2012 June 11-15, 2012, Copenhagen, Denmark

Accepted for journal publicationGT2012-68355

2

AuthorsAuthors

Supported by Honeywell Turbocharger Technologies (HTT)

Thermal Energy Transport to the Performance of (Semi) Floating Ring Bearing Systems for Automotive Turbochargers

Vince BarbarieAvijit Bhattacharya

Kostandin Gjika

Honeywell Turbo TechnologiesTorrance, CA 90504

Honeywell Turbo Technologies,Thaon-les-Vosges, France

Luis San AndrésTurbomachinery Laboratory Texas A&M University

GT2012-68355

3

Fully Floating Bearing Semi Floating Bearing Ball Bearing

Types of bearing supports

Increased IC engine performance & efficiency demands of robust turbocharging solutions

The driver:

Oil lubricated bearings are economic with longer life span; but prone to harmful subsynchronous whirl & depend on engine oil condition.

Low shaft motion, expensive, limited

lifespan

4

Major challenges

extreme operating conditions:• - Low Oil Viscosity, e.g. 0W30 or 0W20

• - High Oil Temperature (up to 150°C)

• - Low HTHS (2.9); Low Oil Pressure (1 bar),

• - Increased Max. Turbocharger Speed 5 kHZ

• - Variable Geometry Turbo Technology & Assisted e-power start up

• - High Engine Vibration Level• - More Stringent Noise Requirements

Need predictive too to reduce costly engine test stand qualification

Thermal management & reduce thermal loading

5

• TC linear and nonlinear rotordynamic codes – GUI based – including engine induced excitations

• Realistic bearing models: thermohydrodynamic

• Novel methods to estimate imbalance distribution and shaft temperatures

• NL analysis for frequency jumps (internal & combined resonances) and noise reduction

• Measured ring speeds with fiber optic sensors

Literature Review: TAMU work

Predictive tool for shaft motion benchmarked by test data

2004 IMEchE J. Eng. Tribology

2005 ASME J. Vibrations and Acoustics ASME DETC 2003/VIB-48418 ASME DETC 2003/VIB-48419

2007 ASME J. Eng. Gas Turbines Power ASME GT 2006-90873

2007 ASME J. Eng. Gas Turbines Power ASME GT 2005-68177

2007 ASME J. Tribology IJTC 2006-12001

2007 ASME DETC2007-34136

2010 ASME J. Eng. Gas Turbines Power ASME GT2009-59108

2010 IFToMM Korea

6

VIRTUAL TOOL for TC NL shaft motions

Tool demonstrated 70% cycle time reduction in the development of new CV TCs. Since 2006, code aids to develop PV TCs with savings up to $1XX k/year in qualification test time

ASME DETC2007-34136

Predicted Steady-State Waterfall / Y DisplacementRBS with ODminIDmax / Oil Texaco-Havoline Energy 5W30, 150°C, 4bar

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

Frequency (Hz)

Mo

tio

n A

mp

litu

de

Subsynchronous ComponentsSynchronous Component

Predicted Steady-State Waterfall / Y DisplacementRBS with ODminIDmax / Oil Texaco-Havoline Energy 5W30, 150°C, 4bar

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

Frequency (Hz)

Mo

tio

n A

mp

litu

de


Measured Steady-State Waterfall / Y DisplacementRBS with ODminIDmax / Oil Texaco-Havoile Energy 5W30, 150°C, 4bar

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

Frequency (Hz)

No

rma

lize

d N

on

lin

ea

r R

es

po

ns

e


Measured Steady-State Waterfall / Y DisplacementRBS with ODminIDmax / Oil Texaco-Havoile Energy 5W30, 150°C, 4bar

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

Frequency (Hz)

No

rma

lize

d N

on

lin

ea

r R

es

po

ns

e


Predicted shaft motion Measured shaft motion

TC testing is expensive and time consuming

Predictive tool saves time and resources

7

Thermal energy analysis in TCs complicated b/c of a) Hot gas -work and heat flow from turbine b)Cold gas +work and heat flow from the

compressorc) internal heat flow across shaft from T to C and

radially thru bearingsd)Mechanical drag power in bearingse) Heat flow to/from casing to ambient (convective and

radiant)

Conjugate heat transfer in TCs

Engine lubricated bearings: (a) low friction-load support (b) oil carries away heat (cooling)

8

turbinecompressor

Heat flows & energy transfer in a TCHot air (energy) in

-Hot air (energy) out

Heat conducted (casing)

Heat conducted (shaft)

Cold air (energy) in

Compressed hot air (energy) out


Bearing drag power generation

Oil in

Oil out

Baines, N., Wygnant, K., Dris, A., 2010, J Eng Gas Turb. Power, 042301


work

9

a) Lumped parameter models with empirical formulas for heat transfer coefficients and simplified formulas for drag power, flow & heat flow in the lubricated bearings

b)Current 3D modeling stresses on solids with over-simplified coupling to the lubricant flows

Thermal energy analyses in TCs use

avoid oil coking, optimize flow rates, ensure proper clearances,

eliminate seizure.

Engineered thermal management to avoid severe thermal loading with improved reliability of bearing system:

GOAL

10

SFRB system in engine-oil lubricated TC

turbine

compressor

Semi-floating

ring bearing

Compressor side bearing oil supply holesto inner and outer filmsOil supply

holes to inner film

Turbine side bearing Outer film with ½ moon groove

Oil supply at

Psup, Tsup

Anti-rotation pin

shaft

casing

Oil discharges at

ambient pressure Pa

Lubricant flow paths into bearings on turbine and compressor sides

11

Definitions:X,Y: fixed (inertial) coordinate systemg : direction of gravity

Circumferential coordinate

X

gRing rotation

R

0º

Oil supply hole

DRo

DB

Y

Z

Lo

outer film

shaft

Ring

Casing

Y

½ moon groove

LG

Shaft rotation

inner film

Li

ShaftDRi

DJ

Geometry & coordinate system for typical SFRB

12

Kinematics of journal and ringNomenclature: : journal rotational speed

R: ring rotational speed

Circumferential (angular) coordinate

co : radial clearance outer film

ci : radial clearance inner film

ho: outer film thickness

hi : inner film thickness

eRX, eRY: Ring center eccentricity components

eX, eY: Shaft (journal) center eccentricity components

eJX, eJY : Eccentricity of journal relative to ring

X

Y

OR

eReJ

e

R

ring

journal

ring rotation

Journal rotation

cos sinX Yo o R Rh c e e cos sin

X Yi i J Jh c e e

Inner film thickness

=e eR eJ+

Journal rotation

X

Y

OR

eRX

eRY

eX

eY

eJX

eJY

eReR

eJeJee

R

OJ

ring

journal

ring rotation

=e eR eJ+=e eR eJ+=e eR eJ+ee eReR eJeJ+Outer film thickness

13

Shaft, TS

Casing, TC

Ring, TR(r)

Inner film, Ti(,z)

Outer film, To(,z)

R TRi

TRo

TRM

Ro

Ri

RM

Pi,Ti

Po,To

TS

TC

Oil inlet,Psup, Tsup

Feedhole

Inlet½ moongroove

zRs

Rc

PA, ambientpressure

PA

z

Axial view of inner and outer films: nomenclature

14

Hydrodynamic pressure generation

3 3

2

( ) ( )

1

12 12

2

i i i i

J i T i T

i iR

h P h P

R z z

h h

t

Nomenclature

P : film pressure

h : film thickness

: viscosity, fn (T)

Major assumptions:Laminar flow without fluid inertia effectsAverage viscosity across film thickness

V ST TS e

3 3

2

( ) ( )

1

12 12

2

o o o o

B o T o T

o oR

h P h P

R z z

h h

t

Innerfilm

Outerfilm

journal rotational speed

R ring rotational speed

circumferential coordinateZ axial coordinate

RJ: Shaft (journal) radius

RB: Bearing casing inner diameter

Reynolds equations for inner & outer films

TRM

Ring

Pi,Ti

Po,To

TS

Casing TC

shaft

15

shaft

Ring

TS

casing

Outer film

Inner filmTRi

TRo

TC

Ti

To

Heat flow from shaft Mechanical

drag power

Heat flow into ring

Mechanical drag power

Heat flow into casing

Flow outer

Flow inner

Heat flow

carried

by oil

Heat flows & power in a FRB

16

NomenclatureTi: inner film temperature

TJ, TRi : shaft (journal) and ring ID temperatures

hJ, hRi : heat convection coefficients

z i iv i i i i J i J R i R i

J

C m T m T h T T h T TR z

i im hU

Zi im hW

222( ) 212

12 2i T B R B R

i i ii

R RW U

h

with circ. and axial mass flow rates:

Inner film mechanical energy dissipation:

2

( )12i i

ii T

h PW

z

2

( )12 2i i R

i Ji T J

h PU R

R

Thermal energy transport in inner film

TRM

Pi,Ti

Po,To

TS

Casing TC

shaft

17

TRM

Pi,Ti

Po,To

TS

Casing TC

shaft

Thermal energy transport in outer filmNomenclature

To: outer film temperature

TB, TRo : bearing casing and ring OD temperatures

hB, hRo : heat convection coefficients

z o ov o o o o B o B R o R o

B

C m T m T h T T h T TR z

o om hU

Zo om hW

2 2( ) 212

12 2o T B R B R

o o oo

R RW U

h

with circ. and axial mass flow rates:

Outer film mechanical energy dissipation:

2

( )12o o

oo T

h PW

z

2

( )12 2o o B R

oo T B

h P RU

R

18

0R

R R R R R RA

q k T q dA

Heat conduction in semi-floating ringNomenclature

TR: ring temperature

TJ, TRi : shaft (journal) and ring ID temperatures

hJ, hRi : heat convection coefficients

kR: ring material conductivity

qR : heat flow

Major assumptions:Steady state, no heat flow in

axial direction,No effect of ring rotation

10R R

T Tr

r r r r r

r

19

Heat conduction in semi-floating ring

Major simplificationRadial heat conduction only

10R R

T Tr

r r r r r

r

1

0RT

rr r r

( )

ln2r M

M

RR R

R R

Q rT T

L R

TRM

Ring

Pi,Ti

Po,To

TS

Casing TC

shaft

Nomenclature

TR: ring temperature

QR: radial heat flow

kR: ring material conductivity

Ring

R

TR

TiInner film

i ii R R i R RiQ h T T R z

oR o R Ro o RoQ h T T R z

ToOuter film

r

20

1 Reynolds/Colburn Analogy), Nu=3 Pr0.33

2 Kays and Crawford - constant wall temperature, Nu =7.54

3 Kays and Crawford - constant wall heat flux, Nu =8.22

4 Haussen - thermally developing constant wall temperature, Nu >3.657

5 Shah - thermally developing constant wall heat flux, Nu > 4.364

6 Stephan - Simultaneous developing, constant wall temp, Nu >3.66

7 Stephan - Simultaneous developing constant wall heat flux, Nu > 4.364

Heat flow: Q = h A (TS – Ti)A: wetted area for heat transfer

h: heat convection coefficient, a function of Nusselt #, oil conductivity and hydraulic diameter (=clearance).

Nusselt # =depends on flow conditions (Prandtl # and Reynolds #)

Ti

Ts

; Re,Proil

H

kh Nu Nu f

D

Pr ; Rep

oil

C Rc

k

Heat convection Models

21

Numerical method of solution

a) Finite element method for Reynolds Eqns.

WN

WP

UEUW

PPPE

PS

WS

PW

x=R

z

PN

UP

U,P=T,W-cvs

TN

TW TE

TS

TP

e

x=R

z Nodal pressures

q Flow rate

Flowdomain

b) Control volume method for energy transport Eqns.

Includes balance of drag torques, material properties f(T), bearing clearance changes due to temperature rise, etc.

2222

Example Semi FRB for PV turbine bearing

Oil: SAE 5W-30120C

213C

Shaft (journal)

RING

CASING

Oil inlet

Bearing dimensionsInner Film Outer film

Diameter 7.9 14.1 mmlength 4.6 6.2 mm

Cold clearance 7.5 35 m

Oil supply temperature 120 C Turbine temperature 700 CSupply pressure 4 bar Defect temperature ratio 0.16 CInlet presure loss 0.9

Journal Temperature 213 CCasing Temperature 120 C

Speed range 30-240 krpm

Average load 44.1 NOil supply temperature 120 C Turbine temperature 700 CSupply pressure 4 bar Defect temperature ratio 0.16 CInlet presure loss 0.9

Journal Temperature 213 CCasing Temperature 120 C

Speed range 30-240 krpm

Average load 44.1 N

2323

Meshes for inner and outer flow domains

X

=132 ºY

Z

Casing½ moon groove

Feed hole x 4

groove

journal

ring

132o

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45

S1

S3

S5

S7

S9

S11

0.05.010.0

15.0

20.0

circ coordinate (node #)

axial coordinate

15-20

10-15

5-10

0-5

Inner Film

Filed name: Clearances_outer

1 4 7

10

13

16

19

22

25

28

31

34

37

40

43

46

49

52

S1

S4

S7

S10

0.01.02.03.04.05.0

clearance


axial coordinate

4-5

3-4

2-3

1-2

0-1

Inner Film

Filed name: Clearances_inner

½ moon grooveCirc. groove

Oil supply hole(4x) Axial groove

(4 x)

Mesh: outer film

Mesh: inner film

NEX=45, NEY=12

NEX=52, NEY=12

z

z

Engineered design to improve flow delivery and reduce temperature rise

24

1 6

11 16

21

26

31

36

41

46

51S

1 S7 S13

0

50

100

150

200

250

circ coordinate (node #)axial

coordinate

200.0-250.0

150.0-200.0

100.0-150.0

50.0-100.0

0.0-50.0Inner Film

Temperature

(b) Temperature field (C)

z

1

6

11

16

21

26

31

36

41

46

51

S1

S6

S11

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0


axial coordinate

5.0-6.0

4.0-5.0

3.0-4.0

2.0-3.0

1.0-2.0

0.0-1.0

-1.0-0.0

Inner Film

Pressure

(a) Pressure field (bar)

z

Tsup=120C

TS=213C

240 krpm

Feed hole & axial groove

Predictions for inner film at

1 4 7

10

13

16

19

22

25

28

31

34

37

40

43

46

49

52 S1

S4

S7

S10

0.01.02.03.04.05.0

clearance


axial coordinate

4-5

3-4

2-3

1-2

0-1

Inner Film


inner film

z

Oil heats quickly along axial plane

25

0.00.10.20.30.40.50.60.70.80.91.01.1

0 40 80 120 160 200 240

rotor speed (krpm)

Max

. fi

lm t

emp

erat

ure

s [-

]

Oil inlet temperature

Lubricant flash temperature ~ 1.18

Temperatures: maximum in films sup

supS

T TT

T T

Shaft Temp

inner film

outer film

exit mixed films

Inner film temperature

shaft T (< flash T).Outer film

relatively cold.

26

0.00.10.20.30.40.50.60.70.80.91.01.1

0 40 80 120 160 200 240

rotor speed (krpm)

Ave

rag

e fi

lm t

emp

erat

ure

s [-

]

Oil inlet temperature

Lubricant Flash point ~ 1.2

Temperatures: average in films sup

supS

T TT

T T

Inner film much hotter than

outer film. Exit mixing lubricant

temperature nearly constant

> 90 krpm

Shaft Temp

inner film

outer film

exit mixed films

27

0.00.10.20.30.40.50.60.70.80.91.01.1

0 40 80 120 160 200 240

rotor speed (krpm)

Rin

g t

emp

erat

ure

[-]

Oil inlet temperature=Casing temperature

Ring Temperatures: ID, OD and mean sup

supS

T TT

T T

Large radial temperature

gradient across ring.

OD-ID Temperature difference ~

40oC.RING material

conductivity is important.

Shaft Temp

(mean radius)

RingID

RingOD

28

Oil viscosity (average): inner & outer films

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 40 80 120 160 200 240

rotor speed (krpm)

Vis

cosi

ty (

-)

(5.85 cPoise at 120C)outer film

inner film

outer film

inner film

Relative to supply: Inner film viscosity

decreases because of

increase in film temperature

(> Tsup)

Thermal effects can not be ignored

29

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0 40 80 120 160 200 240

rotor speed (krpm)

Shaft Temp.=213CCasing Temp.=120C

Oil inlet temp.=120CSupply pressure=3.6

Oil flow rates: inner & outer

outer film

inner film

Flow=1= out+in

Oil flow is minimum at top

speed. Outer/inner flow

decreases/increases because of

clearance shrinks/grows +

lower oil viscosity

30

Heat flows and drag power Low speeds: heat

from shaft dominates.

High speeds: drag power

losses increase. For all conditions

lubricant carries more energy that

casing soaks.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 40 80 120 160 200 240

rotor speed (krpm)

Shaft Temp.=213CCasing Temp.=120C

Oil inlet temp.=120CSupply pressure=3.6 bar

(S)FRB

Heat from shaft

Drag power(inner film)

Heat to lubricant

Heat to casing

Heat to ring

+ + =1=

31

Width of boxes denotes intensity of heat flows

Thermal energy transport and balance

Heat from shaft

100%

Heat to casing

Heat to fluid (i+o)Heat to fluid (i)

Heat to fluid (o)

Heat to ring97%

3%

36 % 27 %

74 %

10 %

64 %

low speed (45 krpm)

Drag Power (inner & outer)

Lubricant carries away heat from shaft mainly.

32

Width of boxes denotes intensity of heat flows

Thermal energy transport and balance

Heat from shaft

100%

Heat to casing

Heat to fluid (i+o)Heat to fluid (i)

Heat to fluid (o)Heat to ring

65%

35%

24 % 17 %

83 %

8 %

76 %

high speed (240 krpm)

Drag Power (inner & outer)

Drag power losses increase. Lubricant carries away largest portion of heat flow.

33

1

3

5

7

9111

315

S1

S5

S9

S13

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

speed (rpm)

axial [-]

Heat from shaft

35.0-40.0

30.0-35.0

25.0-30.0

20.0-25.0

15.0-20.0

10.0-15.0

5.0-10.0

0.0-5.0

1

3

5

7

9111

315

S1

S5

S9

S13

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

speed (rpm)

axial [-]

Drag power - inner film

12.0-14.0

10.0-12.0

8.0-10.0

6.0-8.0

4.0-6.0

2.0-4.0

0.0-2.0

30 krpm30 krpm

240 krpm 240 krpm

Heat from shaft (W)

Inlet plane

Exit plane

High power

low powerLow heat flow

High heat flow

Exit plane

1 4 7

10

13

16

19

22

25

28

31

34

37

40

43

46

49

52 S1

S4

S7

S10

0.01.02.03.04.05.0

clearance


axial coordinate

4-5

3-4

2-3

1-2

0-1

Inner Film


inner film

z

Drag power (W)

Drag power and heat from shaft

Drag power and heat from shaft are large at inlet because of inlet (cold) lubricant.

34

Conclusions (a) Heat flow from hot shaft into inner film is large; more so at

the inlet plane where oil is cold; (b) The inner film temperature increases quickly (viscosity

drops) due large heat flow from shaft and drag shear power;

(c) The floating ring has a large radial temperature gradient; (d) At all rotor speeds, the lubricant flows carry more than 70

% of the total energy input. The rest soaks into the TC casing. The bearing design must allow for adequate flow paths to cool components.

Tool integrated into sponsor engineering design practice to predict thermal loading and mechanical stresses and to ensure lubricant does not overheat (coking)

1 Luis San Andrés Mast-Childs Professor, Fellow ASME Texas A&M University On the Effect of Thermal...

Documents

Transcript of 1 Luis San Andrés Mast-Childs Professor, Fellow ASME Texas A&M University On the Effect of Thermal...