GT2009-59108 Turbocharger: Engine Induced Excitations Kostandin Gjika Engineering& Technology Fellow Honeywell Turbo Technologies ASME TURBO EXPO 2009,

GT2009-59108 Turbocharger: Engine Induced Excitations

Kostandin GjikaKostandin GjikaEngineering& Technology Fellow

Honeywell Turbo Technologies

ASME TURBO EXPO 2009, Power for Land, Sea and Air

Luis San AndrésLuis San AndrésMast-Childs Professor

Fellow ASME

Turbocharger Nonlinear Response Turbocharger Nonlinear Response

with Engine-Induced Excitations: with Engine-Induced Excitations:

Predictions and Test DataPredictions and Test Data

ASME Paper GT 2009-59108

Ash MaruyamaAsh MaruyamaResearch Assistant (05-07)

Texas A&M University

Sherry XiaSherry XiaRotordynamics Manager

Honeywell Turbo Technologies

Supported by Honeywell Turbocharger Technologies (HTT)

Accepted for journal publication


Oil Inlet

Compressor Wheel

Shaft

TC Center Housing

Semi-Floating Bearing Anti-Rotating Pin

Turbine Wheel

• Increase internal combustion (IC) engine power output by forcing more air into cylinder

• Aid in producing smaller, more fuel-efficient engines with larger power outputs

Turbochargers:


RBS With Fully Floating Bearing

RBSWith Semi Floating Bearing

RBSWith Ball Bearing

RBS: TC Rotor Bearing System(s)

Desire for increased IC engine performance & efficiency leads to technologies

that rely on robust & turbocharging solutions


Bearing Types:

Shaft

Ball Bearing

Squeeze Film

Inner Race

Locking Pin

Outer Race

Ball-Bearing

Shaft

Inner Film

Outer Film

Oil Feed Hole

Floating Ring

Locking Pin

Semi-Floating Ring Bearing

(SFRB)

Floating Ring Bearing(FRB)

• Low shaft motion• Relatively expensive• Limited lifespan

• Economic• Longer life span• Prone to

subsynchronous whirl


Shaw & Nussdorfer (1949): Test results show superior performance of FRBs over plain journal bearings

Tatara (1970): Initially unstable FRB-supported test rotor becomes stable at high speeds, ring speed reaches constant speed

Li & Rohde (1981): Numerically show FRB-supported rotors whirl in stable limit cycles

Trippett & Li (1984): Shows lubricant viscosity changes cause unusual floating-ring speed behavior, isothermal analysis is incorrect

ENGINE INDUCED Vibrations:

Literature Review

Kirk et al. (2008): Measure shaft motions of TC on FRB attached to diesel ICE. Engine-attributed low frequency amplitudes comparable to TC subsynchronous amplitudes. Little to no insight on RBS analysis

Ying et al. (2008): TC-RBS NL analysis with engine foundation excitation. Rotor response is quite complicated showing chaos at the lowest shaft speed. Little to no insight on test data


TAMU-HTT VIRTUAL TOOL for Turbocharger NL Shaft Motion Predictions XLTRC2® based with a demonstrated 70% cycle time reduction in the development of new CV TCs. Since 2006, code aids to developing PV TCs with savings up to $150k/year in qualification test time

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

ASME DETC2007-34136

Measured shaft motion


• TC linear and nonlinear rotordynamic codes – GUI based

• Measure ring speeds with fiber optic sensors

• Realistic thermohydrodynamic bearing models

• Novel methods to estimate imbalance distribution and shaft temperatures

Literature Review: San Andres and students

Tools for shaft motion prediction with effect of engine excitation needed –benchmarked by tests 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. TribologyIJTC 2006-12001

2007 ASME DETC2007-34136


Objectives:

TAMU-HTT publications show unique -one to one- comparisons between test data and nonlinear predictions

• Refine rotordynamics model by including engine-induced housing excitations

• Deliver predictive tools validated by test data to reduce the need for costly engine test stand qualification

• Further understanding of complex TC behavior

quantification


TC rotor & bearing system 2 shaft model

Compressor Turbine

126.44 mm

Spacer

RBS with Semi Floating Bearing


Shaft2585449

Shaft245 Shaft1

44

4035

30252015105Shaft1

1

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0 0.02 0.04 0.06 0.08 0.1 0.12

Axial Location, meters

Sh

aft

Ra

diu

s,

me

ters

Rotor C.G.

Rotor finite element model: 2 shaft model

Shaft measurements (STN 3)& predictions

Rotor: 6Y gramSFRB: Y gram

Static gravity load distribution Compressor Side: Z

Turbine Side: 5Z

Compressor TurbineSFRB

Thrust Collar

Validate rotor

model with measurem

ents of free-fee modes(room Temp)

C T

u


-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0 0.02 0.04 0.06 0.08 0.1 0.12


Sh

aft

Ra

diu

s,

me

ters

Measured (Freq = 1.799 kHz)

Predicted (Freq = 1.823 kHz)

Compressor End Turbine End

First mode

Second mode

measuredprediction

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0 0.02 0.04 0.06 0.08 0.1 0.12


Sh

aft

Ra

diu

s,

me

ters




First mode

Second mode

measuredprediction

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0 0.02 0.04 0.06 0.08 0.1 0.12


Sh

aft

Rad

ius,

mete

rs




First mode

Second mode

measuredprediction

-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0 0.02 0.04 0.06 0.08 0.1 0.12


Sh

aft

Rad

ius,

mete

rs




First mode

Second mode

measuredprediction

Free-free mode natural frequency & shapes:

Measured and predicted free-free natural frequencies and mode shapes agree: rotor model validation

measured Predicted % diff

KHz KHz -

First 1.799 1.823 1.3

Second 4.938 4.559 7.7


(Semi) Floating Bearing Ring :• Actual geometry (length, diameter, clearance) of inner and outer films, holes size and distribution• Supply conditions: temperature & pressure• Lubricant viscosity varies with temperature and shear rate (commercial oil)• Side hydrostatic load due to feed pressure • Temperature of casing • Temperature of rotor at turbine & compressor sides derived from semi-empirical model: temperature defect model

XLBRG® thermohydrodynamic fluid film bearing model predicts operating clearance and oil viscosity (inner and outer films) and eccentricities (static and dynamic) as a function of shaft & ring speeds and applied (static & dynamic) loads.


– TC speed ranges from 48 krpm – 158 krpm

– Engine speed ranges from 1,000 rpm – 3,600 rpm

– 25%, 50%, 100% of full engine load

– Nominal oil feed pressure & temperature: 2 bar, 100°C

Operating conditions from test data:

Compressor Housing

Air Inlet

Engine

Proximity Probes (X, Y)

accelerations are collected with three-axis accelerometers.

Fig. 4 Turbocharger Engine Test Facility Stand

Compressor Housing

Air Inlet

Engine


TC Engine Test Facility Stand


(S)FRB Predictions :

90

100

110

120

130

140

150

160

170

0 20000 40000 60000 80000 100000 120000 140000 160000 180000Shaft speed (rpm)

Max

imu

m t

emp

era

ture

(C

)

100% Engine Load - Inner Film 100% Engine Load - Outer Film50% Engine Load - Inner Film 50% Engine Load - Outer Film25% Engine Load - Inner Film 25% Engine Load - Outer FilmLubricant Supply Temperature

Peak film temperatures

Supplytemperature

Inner film

Outer film

Increase in power losses (with speed) lead to raise in inner film & ring temperatures.

No effect of engine load


0

1

2

3

4

5

6

7

0 20000 40000 60000 80000 100000 120000 140000 160000 180000Shaft speed (rpm)

Eff

ecti

ve v

isco

sit

y (

cP)

100% Engine Load - Inner Film 100% Engine Load - Outer Film50% Engine Load - Inner Film 50% Engine Load - Outer Film25% Engine Load - Inner Film 25% Engine Load - Outer Film

(S)FRB Predictions : Oil effective viscosity

SupplyViscosity: 8.4 cP

Inner film

outer film

LUB: SAE 15W-40

Increased film temperatures determine lower lubricant viscosities. Operation parameters

independent of engine load

Lubricant type:

SAE 15W - 40


0.80

0.85

0.90

0.95

1.00

1.05

1.10

1.15

1.20

0 20000 40000 60000 80000 100000 120000 140000 160000 180000Shaft speed (rpm)

Film

cle

aran

ceC

old

cle

aran

ce

100% Engine Load - Inner Film 100% Engine Load - Outer Film50% Engine Load - Inner Film 50% Engine Load - Outer Film25% Engine Load - Inner Film 25% Engine Load - Outer Film

Clearance thermal growth relative to nominal inner or outer cold radial clearance

(S)FRB Predictions : Film clearances

nominalclearance

Inner film

outer film

Inner film clearance grows and outer film clearance decreases – RING grows more

than SHAFT and less than CASING. Material parameters are important


TC housing acceleration measurements:

TC center housing and compressor housing accelerations measured with 3-axes accelerometers for three engine loads: 25%, 50%, 100% of full engine load

Accelerometers accelerometers

accelerations are collected with three-axis accelerometers.

Fig. 4 Turbocharger Engine Test Facility Stand

Compressor Housing

Air Inlet

Engine



TC housing acceleration analysis:

ΔtMax Time

# points in FFT Δf

Max FFT freq.

[μs] [s] -- [Hz] [Hz]

200 3.0 2,048 2.44 2,500

Last 2,048 (out of 15,000) time data points converted to frequency spectrum via

Fast Fourier Transformations (FFTs)

0 100 200 300 400 500 600 700 800 900 10000

100

200

300

Excitation frequency [Hz]

Am

plitu

de

0 100 200 300 400 500 600 700 800 900 10000

100

200

300

Excitation frequency [Hz]

Am

plitu

de

Combined manifold & TC system natural

frequencies

Center Housing

Comp. Housing

m/s2

m/s2

100% engine load

~300 Hz

~570 Hz

1000 rpm

3600 rpm


0 2 4 6 8 10 12 14 16 18 200

100

200

300

Order of engine frequency

Am

plitu

de

0 2 4 6 8 10 12 14 16 18 200

100

200

300

Order of engine frequency

Am

plitu

de

TC housing acceleration analysis:

Combined manifold & TC system natural

frequencies

Center Housing

Comp. Housing

m/s2

m/s2

100% engine load

~300 Hz

~570 Hz

1000 rpm

3600 rpm

2, 4, and 6 times engine

(e) main frequency contribute

significantly

1e order frequency

does not appear


0

50

100

150

200

250

300

350

400

450

500

0 500 1000 1500 2000 2500 3000 3500 4000

Engine Speed (rpm)

Ac

ce

lera

tio

n p

k-p

k (

m/s

ec

^2

)

Center Housing Acceleration

Compressor Housing Acceleration

Center and compressor housings do not vibrate as a rigid body

m/s2

TC housing total acceleration 100% engine load

Compressor housing

Center housing


Displacement transducers

Displacement transducers record shaft motion

relative to compressor housing

Rotordynamics model outputs absolute shaft

motion

shaft motion relative to compressor housing

needs of casing motion

Integration of housing accelerations into rotordynamics model

Note: TC Housing accelerations and TC shaft motions NOT recorded simultaneously


Housing accelerations into model

Center Housing

Compressor

Turbine

Semi Floating Ring Bearing Assembly

Shaft

Axial Bearing Assembly

Connection to engine mount

Compressor housing

Eddy current sensor

Accelerometer

Specified housing motiondue to engine

Basic assumptions– TC housings move as a rigid body– TC housing vibrations transmitted through bearing

connections– Each bearing transmits identical housing vibrations


Rotordynamics model

Z Vector of rotor & ring displacements & rotations along (X, Y) at the DOFs of interest

M, K, D, G() – Matrices of rotor & ring inertias, stiffness, damping &

gyroscopics at the rated rotor speed ()

Fext(t) Imposed time varying forces acting on the rotor & ring,

such as imbalances, aerodynamics, side loads

FB(t) Vector of bearing reactions forces including engine vibration

excitation

( ) ( )( ) t t B extM Z + D G Z + K Z F F

, ,

, , , , , , , , ,X YB R S S S S R B R B R B R BX Y

F x y x y x x y y x x y yf

Shaft motion (ring motion – base motion)


Housing accelerations into model

Center Housing

Compressor

Turbine

Semi Floating Ring Bearing Assembly

Shaft

Axial Bearing Assembly

Connection to engine mount

Compressor housing

Eddy current sensor

Accelerometer

Specified housing motiondue to engine

01

( ) cosFN

n e nn

a t A A n t

0

Fourier coefficient decomposition of housing acceleration time data

Double time integration

2

1

( ) cosFN

ne n

n e

Ax t n t

n

Procedure:Find first 10 Fourier coefficients (amplitude and phase) of center housing

acceleration and input into rotordynamics model.

Run nonlinear time transient analysis and find absolute shaft motion response.

Subtract compressor housing displacements to obtain shaft motion relative to compressor


RBS damped natural frequencies

0

500

1000

1500

2000

2500

3000

0 20000 40000 60000 80000 100000 120000 140000 160000 180000

Shaft speed (rpm)

Dam

ped

natu

ral

freq

uen

cy (

Hz)

f=99.5 Hzd=.3161 zetaN=80000 rpm

f=546.5 Hzd=.2492 zetaN=80000 rpm

f=621. Hzd=.5294 zetaN=80000 rpm

f=2025.2 Hzd=.1408 zetaN=80000 rpm

1st elastic modecyl. turb. bear. ringing mode

cyl. comp. ringing mode

conical mode

1XCritical speed

100% engine load


RBS response to imbalance 100% engine load

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0 40000 80000 120000 160000 200000

Shaft Speed (rpm)

Am

pli

tud

e 0

-pk (

-)

Test Data

Nonlinear Pred. - No Housing Motion (1X)

Nonlinear Pred. Relative to Comp. Housing (1X)

Linear Pred. (1X)

Linear Pred.

Nonlinear Pred.

Test Data

Differences between

predictions and test data attributed to

inaccurate knowledge of

imbalance distribution

Test data

NL pred.

C T

u


Transient time NL rotor response

XLTRC2® Nonlinear numerical integration of equation of motion (time-marching ) with bearing forces evaluated at each time step.• Gear stiff method• Component mode synthesis• Post processing in frequency domain (Virtual Tools)

• Integration parameters CPU ~ 30’ per shaft speed

Δt Max Time# time steps Δf

Max FFT freq.

[μs] [s] -- [Hz] [Hz]

78.1 1 12,800 4 6,400

Results (amplitudes at) compressor nose vertical directionshown relative to maximum conical motion at the compressor shaft end


0

0.05

0.1

0.15

0.2

0.25

0 500 1000 1500 2000 2500 3000 3500 4000

Frequency (Hz)

Am

pli

tud

e 0

-pk

(-)

Predictions without Housing Acceleration

TC synchronous response

1.0 krpm

3.6 krpm

1.0 krpm

3.6 krpm

0

0.05

0.1

0.15

0.2

0.25

0 500 1000 1500 2000 2500 3000 3500 4000

Frequency (Hz)

Am

pli

tud

e 0

-pk

(-)

Test Data


1.0 krpm

3.6 krpm

0

0.05

0.1

0.15

0.2

0.25

0 500 1000 1500 2000 2500 3000 3500 4000

Frequency (Hz)

Am

pli

tud

e 0

-pk

(-)

Test Data


1.0 krpm

3.6 krpm

1.0 krpm

3.6 krpm

0

0.05

0.1

0.15

0.2

0.25

0 500 1000 1500 2000 2500 3000 3500 4000

Frequency (Hz)

Am

pli

tud

e 0

-pk (

-)

Predictions with Housing Acceleration


1.0 krpm

3.6 krpm

0

0.05

0.1

0.15

0.2

0.25

0 500 1000 1500 2000 2500 3000 3500 4000

Frequency (Hz)

Am

pli

tud

e 0

-pk (

-)

Predictions with Housing Acceleration


1.0 krpm

3.6 krpm

1.0 krpm

3.6 krpm

Housing accelerations induce broad range, low

frequency shaft whirl motions

Test data shows broad frequency response at low

frequencies (engine speeds)

Waterfalls of shaft motion at compressor end 100% engine load

1000 rpm

3600 rpm


0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0 500 1000 1500 2000 2500 3000 3500 4000

Shaft speed (rpm)

Am

pli

tud

e p

k-p

k (-

)

Test Data

Nonlinear Predictions

Good correlation

with test data for all shaft

speeds

Total shaft motion at compressor end (amplitude)

100% engine load

Test data

NL pred.

Am

plit

ud

e p

k-p

k (-

)

Rotor speed (RPM)


0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0 500 1000 1500 2000 2500 3000 3500 4000Engine speed (rpm)

Am

pli

tud

e 0

-pk (

-)

Test DataTest Data Peak ValueNonlinear PredictionsPredicted Peak Value

Good agreement

b/w predictions

and test data from 1750 –

2750 rpm

Subsynchronous amplitudes vs engine speed

100% engine load

Test data

NL pred.

Engine speed (RPM)

Am

plit

ud

e 0

-pk

(-)


0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Orders of main engine speed

Am

plitu

de

0-p

k (

-)

Test Data


Fig. 13. Predicted and measured subsynchronous shaft motion amplitudes versus orders of engine speed (compressor nose, vertical direction)

TC shaft self-excited freq.

2e and 4e orders engine

frequency contribute

the most to shaft

motions

14e order is due to shaft self-excited

vibration (whirl from

bearings)

Subsynchronous amplitudes vs engine orders

100% engine load

Test data

NL pred.

Orders of main engine speed

Am

plit

ud

e 0

-pk

(-)


0

200

400

600

800

1000

0 40000 80000 120000 160000 200000

Shaft speed (rpm)

Su

b S

ynch

ron

ou

s F

req

uen

cy [

Hz]

Test Data


conical mode

cylindrical (comp. bearing ring) mode

cylindrical (turb. bearing ring) mode

System (manifold & TC) natural frequency ranges

~570 Hz

~300 Hz

Subsynchronous frequency vs. rotor speed

2e frequency shown in test data and

preds

4e frequency tracks rotor conical mode

Subsynchronous frequencies ~ super-harmonics of conical

mode

2e order freq.

4e order freq.

Group 1 (0.5 C)

Group 2 (2C)

Group 3 (4C)

Tes

t

1X

Su

bsy

nch

ron

ou

s fr

eq

uen

cy

(H

z)

Rotor speed (RPM)


order engine frequencies, most likely due to the engine firing

0

50

100

150

200

250

300

350

400

450

500

550

600

0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000

Engine speed (rpm)

Fre

qu

ency

[H

z]

Test Data


12e

2e

1e

3e

4e

5e

6e

7e

8e

9e10e11e

TC shaft self-excited freqs.

0

50

100

150

200

250

300

350

400

450

500

550

600

0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000

Engine speed (rpm)

Fre

qu

ency

[H

z]

Test Data


12e

2e

1e

3e

4e

5e

6e

7e

8e

9e10e11e

TC shaft self-excited freqs.

predictionmeasured

Fig. 15. Predicted and measured subsynchronous whirl frequencies

Subsynchronous freq. vs. IC engine speed

Subsynch. freqs. are

multiples of IC engine frequency

Higher engine

order frequencies

not predicted

100% engine load

Test

NL

Su

bsy

nch

ron

ou

s fr

eq

uen

cy

(H

z)

Engine speed (RPM)

TC manifold nat freq.


• Engines induce significant and complex, low frequency subsynchronous whirl in turbochargers

• 2e and 4e order frequencies contribute significantly to housing acceleration

• Center housing and compressor housing do not vibrate as a single rigid body

• Engine super-harmonics excite TC rotor damped natural frequencies.

• Whirl frequencies are multiples of engine speed

Conclusions

Good agreement between predictions and test data validates the nonlinear rotordynamics model!


Recommendations

• Validation against test data from different TCs is needed

• Housing accelerations and TC shaft motion must be recorded simultaneously and for longer periods of time (smaller frequency step size)

Work completed in 2008• Understand why higher order subsynchronous

frequencies are not predicted• Update model to account for unequal housing

excitations at each bearing location


Acknowledgments

Learn more at http://phn.tamu/edu/TRIBgroup

Honeywell Turbocharging Technologies (2000-2008)

TAMU Turbomachinery Laboratory Turbomachinery Research Consortium

(XLTRC2®)

Questions?

Documents

GT2009-59108 Turbocharger: Engine Induced Excitations Kostandin Gjika Engineering& Technology Fellow Honeywell Turbo Technologies ASME TURBO EXPO 2009,