Title master format by click treat - Gamma Technologies, LLC · © by VKA – all rights reserved. Confidential – no passing on to third parties -60-40-20 0 20 40 60 80 100 120

© by VKA – all rights reserved. Confidential – no passing on to third parties

Title master format by click treat

Institute for Combustion Engines

RWTH Aachen University

Prof. Dr.-Ing. Stefan Pischinger

1 Institute for Combustion Engines RWTH Aachen University 2 FEV GmbH, Aachen

Modeling of Axial Forces on

Turbocharger Rotors

Frankfurt, October 26th, 2015

Max Stadermann1, Johannes Scharf2


Enhanced part load simulation accuracy

– Prediction of fuel consumption in driving cycles (GT-Drive)

– Set point for load step simulations

Design of TC thrust bearings

– One of the most frequent causes for TC failure

Definition of boundary conditions for TC bearing

simulations

Precise consideration of TC bearing losses for TC

efficiency calculation

Do we need thrust load modeling?

2 [email protected]

BM

EP

/ b

ar

0

4

8

12

16

20

Engine speed / 1/min

1000 2000 3000 4000

1.5 l TC DI WLTP

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4

Tu

rbin

e E

ffic

ien

cy η

T/ -

.

Turbine Pressure Ratio p3t/p4 / - .

)hh(m

P)hqh(m

stis,4,tot3,T

Ftot1,Ctot2,Vadis,T,

Isentropic adiabatic efficiency

)hh(m

P)hh(m

stis,4,tot3,T

Ftot1,tot2,VisT,

Isentropic efficiency

)hh(m

)hh(m*

stis,4,tot3,T

tot1,tot2,VTCm,isT,

Net turbine efficiency


Agenda

3 [email protected]

General Behavior of TC Friction Losses

Overview of TC Thrust Load Modeling

Impact of TC Friction Losses on Engine Modeling

– Full Load Operation at Rated Power Condition

– Transient Response during Load Steps at Low Engine Speeds

Conclusion


Main Influential Parameters on TC Bearing Friction

Thrust Load Difficult to Predict during TC Operation

4 [email protected]

-60 -40 -20 0 20 40 60Axialkraft / N

Axial Load Fax / N

pOil = 4 bar (abs.)

TOil = 90 °C

nTC = 120 000 1/min

nTC = 80 000 1/min

nTC = 40 000 1/min

0

50

100

150

200

250

300

350

400

450

500

550

0 40000 80000 120000 160000

ATL Drehzahl / 1/min

pOil = 4 bar (abs.)

TOil = 90 °C

FAx = 0 N

TC Speed nTC / 1/min

TC

Be

arin

g F

riction

PF /

W


TC Friction Test Bench

Independent Speed and Thrust Load Control

5 [email protected]

Electric Drive

Toil,out

MF

Toil,in, poil Thrust Load Actuator

Fax


Agenda

6 [email protected]






Conclusion


Overview of Thrust Load Modelling

Model Validation using Strain Gage and Pressure Sensors

7 [email protected]

C,1mF

CS,F

CWheel,F

TWheel,F

TS,F

T,4mF

Tp4,FCp1,

F

2p

1p

3p

4p

BFC,p

BFT,p

Model has been calibrated using TC test bench data and works for

different temperature and pressure boundary conditions


Agenda

8 [email protected]






Conclusion


Impact of Friction Losses on Engine Modelling

Calculation of Thrust Load Based on 3-Cylinder GT-Power Model

9 [email protected]

Look-up table based on friction test bench results

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

220000

240000

260000

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

100100

100

300300

300

600600

600

2525

25

5050

50

150150

150

200200

200

400400 400

500500 500

700700 700

803748831

Thrust Load Fax / N

TC

Sp

ee

d n

TC / 1

/min

PF / W

p3 = f(° CA)

p2 = f(° CA)

Thrust Load Model

Fax = f(° CA)

Input for thrust

load model

p1 = f(° CA) p4 = f(° CA)

nTC = f(° CA)

TC Geometry Data Loss Coefficients


-60

-40

-20

0

20

40

60

80

100

120

0 60 120 180 240 300 360 420 480 540 600 660 720

Th

rust L

oa

din

g F

ax

/ N

Crank Angle / ° CA

Thrust Loading During an Engine Cycle (neng = 5500 1/min WOT)

Maximum amplitude reaches ΔFax,max = 42 N

10 [email protected]

Thrust Load

Compressor

Turbine

Turbine+Compressor


-60

-40

-20

0

20

40

60

80

100

120

0 60 120 180 240 300 360 420 480 540 600 660 720

Th

rust L

oa

din

g F

ax

/ N

Crank Angle / ° CA




Thrust Load

Compressor

Turbine

Turbine+Compressor


-60

-40

-20

0

20

40

60

80

100

120

0 60 120 180 240 300 360 420 480 540 600 660 720

Th

rust L

oa

din

g F

ax

/ N

Crank Angle / ° CA




Thrust Load

Compressor

Turbine

Turbine+Compressor

ΔFax,max = 42 N Sign change before and after

each blow down phase


Contribution of Friction Losses to Overall Compressor Power

Friction needs to be Considered in Part Load


Engine Speed

En

gin

e L

oa

d

0

20

40

60

80

100

Turbine Power BearingFriction

BearingFriction (Fax)

No

rmalized

Po

wer

/ %

5 %

0

20

40

60

80

100



No

rma

lize

dP

ow

er

/ %

66 %


Load Step 1500 rpm 2bar to WOT

Consideration of Thrust Load Leads to Slower Load Step

Normalized Time To Torque (TTT) Comment

14

. Both load steps start at the

same part load point

The WG has been closed before

and during the load step

Difference in response time only

caused by different friction

losses of the turbocharger

[email protected]

Load

t

0.8

0.9

1

1.1

1.2

1 2

no

rma

lize

d T

TT

PF = f(nTC) PF = f(nTC,Fax)

∼10 %

TTT

90 %

Increase TTT by 10 %


Conclusion



Motivation

Detailed Sub-Models enable Precise Modelling of Turbochargers

[email protected]

Extended turbine maps

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6

Tu

rbin

e E

ffic

ien

cy e

ta_

T /

-.

Turbine Pressure Ratio p3t/p4 / - .isentr

oper

adia

bate

rT

urb

inenw

irkun

gsgra

d η

is,a

d,T

Turbinendruckverhältnis p3t/p4

ηT

πT

Turbocharger Heat Flux Model

CoolantOil

Environment

Turbine housingCompressor housing Centre housing

Shaft

Compressor

wheelTurbine

wheel

TC

mcp mcp mcp

mcp mcpmcp

Extended compressor map

mcorC

.1.00

1.40

1.80

2.20

2.60

3.00

3.40

3.80

4.20

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

Co

mp

ress

or

Pre

ssu

re R

atio

p 2

t/p1t

/ -

.

Corr. Compressor Mass Flow Rate m_dot_cor_C / kg/s .

πC

Bearing friction losses

Fax


Main Influential Parameters on Bearing Friction

Thrust Load Difficult to Predict during TC Operation

4 [email protected]

-60 -40 -20 0 20 40 60Axialkraft / N

Axial Load Fax / N

pOil = 4 bar (abs.)

TOil = 90 °C

nTC = 120 000 1/min

nTC = 80 000 1/min

nTC = 40 000 1/min

40 60 80 100 120Öltemperatur / °C

Oil Inlet Temperature Toil / °C

pOil = 4 bar (abs.)

FAx = 0 N

nTC = 120 000 1/min

nTC = 80 000 1/min

nTC = 40 000 1/min

0

50

100

150

200

250

300

350

400

450

500

550

0 40000 80000 120000 160000

ATL Drehzahl / 1/min

pOil = 4 bar (abs.)

TOil = 90 °C

FAx = 0 N

TC Speed nTC / 1/min

TC

Be

ari

ng

Fri

ctio

n P

F/

W


Overview of Axial Force Modelling

Model Validation using Strain Gage and Pressure Sensors

7 [email protected]

C,1mF

CS,F

CWheel,F

TWheel,F

TS,F

T,4mF

Tp4,FCp1,

F

2p

1p

3p

4p

BFC,p

BFT,p

Model has been calibrated using TC test bench data and works for

different temperature and pressure boundary conditions


Contribution of Friction Losses to Overall Compressor Power

Friction needs to be Considered in Part Load


Engine speed

En

gin

e lo

ad

0

20

40

60

80

100



Po

wer

/ %

0

20

40

60

80

100



Po

wer

/ %


Enhanced part load simulation accuracy

– Prediction of fuel consumption in driving cycles (GT-Drive)

– Set point for load step simulations

Design of TC thrust bearings

– One of the most frequent causes for TC failure

Definition of boundary conditions for TC bearing

simulations

Precise consideration of TC bearing losses for TC

efficiency calculation

Do we need thrust load modeling?


BM

EP

/ b

ar

0

4

8

12

16

20

Engine speed / 1/min

1000 2000 3000 4000

1.5 l TC DI WLTP

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4

Tu

rbin

e E

ffic

ien

cy η

T/ -

.

Turbine Pressure Ratio p3t/p4 / - .

)hh(m

P)hqh(m

stis,4,tot3,T

Ftot1,Ctot2,Vadis,T,

Isentropic adiabatic efficiency

)hh(m

P)hh(m

stis,4,tot3,T

Ftot1,tot2,VisT,

Isentropic efficiency

)hh(m

)hh(m*

stis,4,tot3,T

tot1,tot2,VTCm,isT,

Net turbine efficiency


Special thanks to AiF and FVV !

[email protected] 16

Thank you for your Attention !

Documents

Title master format by click treat - Gamma Technologies, LLC · © by VKA – all rights reserved. Confidential – no passing on to third parties -60-40-20 0 20 40 60 80 100 120