Engine Dynamic Torque Prediction and validation of … · Engine Dynamic Torque Prediction and...

Engine Dynamic Torque Prediction and validation

of TCI CRDE engine using GT Power

1Copyright © 2012 Mahindra & Mahindra Ltd. All rights reserved.

� Padmavathi Ramadandi

� Saravanan Muthiah

� Date:16/09/2013

Date:7th Jan, 2013

Objective: To model ,Predict and validate the Full throttle dynamic Torque of an common

rail turbocharged intercooled engine as a part of establishing a process for dynamic torque

estimation at powertrain development concpet phase . All engine parameters air ,fuelling

boost pressures and turbocharger lags measured and compared with simulations at various

gear ratios.

Introduction:


Introduction:

Engine dynamic torque is defined as the torque delivered by the engine at 100% throttle

position at specified gear engaged transient condition from low idle to high idle engine

speed.

The main limiting factors for engine dynamic torque delivery are:

1. Air availability or Turbocharger lag

2. Combustion stability or smoke

3. Power Train oscillations

Activated/calibrated Common rail injection Fuel limiting parameters for engine protections are:

1. Active surge dampening(for crankshaft and power train oscillations),

2. Smoke limitation for engine combustion and air availability

consideration for smoke limitation,


consideration for smoke limitation,

3. Engine protection for high TC speed, high fuel injection quantity

limitation, overheat protection

Schematic representation of transient calculations flow

Metering

4***The above picture is from: “Diesel engine transient operation” Book By: Constantine D.Rakopoulos, Evangelos and G

Giakoumis

Metering

_unit

Methodology

1.Engine modeling and validation for steady state engine

performance

2.Converting steady state model

to transient model from low idle to

high idle speeds 2.Modeling controllers for Fuelling

1.. Loading vehicle Elements into

to engine environment with various gear ratios


high idle speeds 2.Modeling controllers for Fuelling

,Turbo charger vane position and ECU logics

3.Dynamic torque prediction andvalidation. With fuelling limitations:

Results discussion

4. Summary and Conclusions

BS

FC

En

gin

e

[g/(

kW

.h)]

220

240

260

Test data_FTP

GT POWER_simulated

1.Engine Modeling and Validation For Steady State

Complete engine with turbocharger intercooler is modelled using GT power . The engine

full throttle performance is validated with test data . Engine power torque bsfc, airflow

rate and fuel flow rates are correlated very well at steady state condition.

Air

flo

w r

ate

(k

g/h

) [k

g/h

]

400

500

600Test data_FTP

GT POWER_simulated


1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000Speed [rpm]

To

rqu

e E

ng

ine

1 (

N.m

) [N

.m]

160

240

320

400

Po

we

r E

ng

ine

1 (

kW

) [k

W]

0

30

60

90

120

BS

FC

En

gin

e

[g/(

kW

.h)]

180

200

220

Engine BSFC

Engine power

Engine torque

1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000Speed [rpm]

Fu

el

FL

ow

ra

te (

kg

/h)

[kg

/h]

0

10

20

30

40

Air

flo

w r

ate

(k

g/h

) [k

g/h

]

0

100

200

300

400

Total air flow rate

Total fuel flow rate

2. Converting Engine steady state model into Transient:

1. Run set up to load mode

2. Modelling combustion as function of airfuel ratios

3. Injection profiles as tables

4.Turbocharger modelling with compressor maps and different turbocharger vane position


4.Turbocharger modelling with compressor maps and different turbocharger vane position

maps.

5.Run set up change to time and continuous

6. Engine cylinder wall temperatures remained constant as steady state.

-----limitation of material temperatures of cylinders & piston walls

7.Engine inertia &turbocharger shaft inertias added.

8. Intercooler effectiveness as tables

GT Power Engine Model_scorpio_88kwEngine gas Exchange

& combustion

calculations

Intercooler component

parameters

2.1 GT Power Engine Model Transient model


Vehicle Fuelling & injection parameters control INCA data set maps

Vehicle load calculations

ECU Logic_Min Fuellig selection

99

1. Acc pedal position

2. Acc pedal torque MAP

3. Friction Torque map

4. FMTC MAP

5. Eng protection limitation

9Engine transient Performance Simulations |

Acc pedal Input

Fuel Limitation

Boost

pressure VGT

control

6. Smoke limitation MAP

7. LIG Gov

8. ASD

9. Minimum QTY to injector

Not applied

Vehicle load modelling:Calculations

1010

Drag force

Velocity

acceleration

Instantaneous vehicle

velocity V= N*Gr*Fdr

Drag force:

calculation:

F=a+b*V^2

Acceleration:

dV/dt:Vi-Vi-1

Inertia force:[Me+Mv]*dV/dt

Engine

speed

GT Power Vehicle Module

10

Load torque = [Resistance

force+ inertia force]*DRR

Total force :=Drag force + inertia force

Load Torque on to the Engine:

=Total force *DRR/[GR*FDR*gear eff*fd

efficiency]Me=Inertia Equivalent weightMv=vehicle weightGr=gear ratioFDR=final drive ratiodV/dt=change in vehicle velocitya,b =coast down valuesDRR=dynamic rolling radius

Measured Vs simulated dynamic Torque 1st gear

1111

200

250

300simulated

measured

En

gin

e t

orq

ue

Nm

Initially 50 nm difference .

Observations:

�1 st gear estimated dynamic torque at

1000rpm is high compared to measured.

�The reason may be the ASD&LIG fuel

limitation.

� parameter or the turbine inertia, or the

instantaneous combustion properties.

3. Dynamic Torque Prediction and Validation

11

50

100

150

1000 2000 3000 4000 5000

En

gin

e t

orq

ue

Nm

difference . Simulations are on higher side

Engine speed rpm

instantaneous combustion properties.

0

20

40

60

80

100

120

0 1 2 3 4

accpedal signal

accpedal …

Time sec

1212

Dynamic torque simulated Vs Measured

150.00

200.00

250.00

300.00

dynamictorque_1stgear150

200

250

300

5thgear 4thgear

Measured Predicted

12

50.00

100.00

1000 1500 2000 2500 3000 3500 4000 4500 5000

dynamictorque_2ndgear

dynamictorque_3rdgear

dynamictorque_4thgear

dynamictorque_5thgear

50

100

1000 1500 2000 2500 3000 3500 4000 4500 5000

5thgear 4thgear

3rdgear 2ndgear

1stgear

� Predicted Dynamic torque from 1 st

gear to 5 th gear is showing the

increasing trend same as measured .

�But the initial torque at 1000 rpm is high in case of predicted torque compared to measured

0

20

40

60

80

100

120

0 1 2 3 4

accpedal signalaccpedal signal

Time sec

Comparison Fuelling limitation

smokelimited_fuel

Final limted(ASD)_Fuel

1313

�Fuelling limited by the ASD is smoothed curve

�Where as actual smoke limited curve is very un even

�That may be the reason for the ASD application

13

0 1 2 3 4 5 6 7

1000 1500 2000 2500 3000 3500 4000 4500 5000

ASD limited_torque

Measured_torque

smoke limted_torque

1414

0

1000

2000

3000

4000

5000

6000

Time Vs Engine speed_simulation

Time VSEngine speed_measured

Dynamic torque Nm measured Vs simulated

Measured Vs simulated dynamic Torque _1st gear_with actual Fuel as input

Engine speed and dynamic torque

is matching with measured performance

141000 1500 2000 2500 3000 3500 4000 4500 5000

sim test

Dynamic torque Nm measured Vs simulated

After updating ASD limited fuelling.

Engine parameters Estimation at 1 st gear

1515

sim_air

test_airflow

Air flow rate kg/hr

P2_Boost pressure

p2_sim_actual

p2sim_desired

test_act

Desired

15

P3

b

ar

ab

s

P3_PressureBF TC

P3_test

p3_sim

Simulated boost pressures is following the desired boost pressure after the turbo lag. But the actual measurement shows the is not.Reasons may be1. The dynamic turbocharger inertia/vane

inertia 2. Or the PID delay in actual3. Choke limitation in simulation 4. But performance does not effect

Time secTime sec

Time sec

Engine dynamic operating points on compressor

1616

16

Operating points limited within map only.

Boost Pressure in all gears

1717

P2_simulated

P2_measured

Desired

Time sec

p2_sim

P2_Test

Desired

1st gear

2nd gear

17

Time sec

P2_test

P2_simulated

Desired

3rd gear

P2_Simulated

P2_tested

Desired

4th gearTime sec

Time SecTime sec

Effect of Intercooler Effieciency

1818

sim_air

test_airflow

Air

flo

w r

ate

Kg

/hr

Simulated airflow rates matches with actual

after correcting steady

Airflow rate started deviating much after boost pressure development

18

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

sim_air

test_airflow

�Intercooler effectiveness

needs to be corrected for

transient condition

compared to steady state

measured

�Because of very less time

availability for heat transfer

after correcting steady IC effectiveness

Air

flo

w r

ate

Kg

/hr

Measured Vs Simulated engine speed response: 1st 2nd 3rd 4th gears

1919

1000

2000

3000

4000

5000

6000

Simulated_speed

measured_speed0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

2nd gear_simulated

2nd gear_measured

2nd gear

Time sec

En

gin

e s

peed

1st gear

En

gin

e s

peed

19

0

Time sec

0

500

1000

1500

2000

2500

3000

3500

4000

4500

sim_4thgear

test_4thgear

4th gear

Time sec 0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

tested _engine speed

simulated_enginespeed

3rd gear

Time sec

Time sec

En

gin

e s

peed

En

gin

e s

peed

Measured Vs Simulated Dynamic Torque 2nd 3rd 4th 5th gears

2020

1000 1500 2000 2500 3000 3500 4000 4500 5000

1st gear_measured

1st_gear_simulated

To

rqu

e N

M

1000 1500 2000 2500 3000 3500 4000 4500 5000

2nd_ gear_measured

2nd_gear_simulated

To

rqu

e N

M

1 st gear 2nd gear

20

1000 1500 2000 2500 3000 3500 4000 4500 5000 1000 1500 2000 2500 3000 3500 4000 4500 5000

1000 2000 3000 4000 5000

3rd gear_measured

3rd_gear_simulated

3rd gear

To

rqu

e N

M

1000 2000 3000 4000 5000

4th gear_measured

4th_gear_simulated

4th gear

To

rqu

e N

M

1000 2000 3000 4000 5000

5th gear_measured

5th_gear_simulated

5th gear

To

rqu

e N

M

2121

Dynamic torque simulated Vs Measured

150

200

250

300

350

FTP GR1_Torque

measured

To

rqu

e N

M

FTP GR1_Torque

Predicted

To

rqu

e N

M

21

� Predicted Dynamic torque from 1 st gear to 5 th gear is showing the increasing trend same as measured .�Torque in each gear is smoothened after reaching FTP line 0

50

100

150

0 1 2 3 4

input accpedal signal

Time sec

0

50

100

1000 2000 3000 4000 5000

Engine speed in 'rpm'

GR2_Torque GR3_Torque


1000 2000 3000 4000 5000

Engine speed in 'rpm'

FTP GR1_Torque



To

rqu

e N

M

Simulated Turbocharger lag _Target Vs actual Boost pressure response

2222

1st gear_boostpressure 2nd_gear_boost 3rd_gear_boost

4th_gear_boost 5th_gear_boost Des_boost

1st gear lag

Bo

ost

pre

ssu

re b

ar

22Engine speed

2nd gear lag

3 rd gear

lag

Bo

ost

pre

ssu

re b

ar

Engine parameters_Dynamic condition

2323

airflowrate_1stgear

airflowrate_2ndgear

airflowrate_3rdgear

airflowrate_4thgear

airflowrate_5thgear

Fuelflow_1st gear

Fuelflow_2nd gear

Fuelflow_3rd gear

Fuelflow_4th gear

Fuelflow_5th gear

23

1000 2000 3000 4000 50001000 2000 3000 4000 5000

1000 2000 3000 4000 5000

lambda_1st gear

lambda_2nd gear

lambda_3rd gear

lambda_4th gear

lambda_5th gear

0

50000

100000

150000

200000

1000 2000 3000 4000 5000

TC speed_1st gear

TC speed_2nd gear

TC speed_3rd gear

TC speed_4th gear

Correlation%

2424

Engine performance %deviation in timeMeasured to simulations

800 rpm to 4000 rpm in 1st gear 4.4%

800 rpm to 4000 rpm in 2nd gear 4.3%

Vehicle dynamic response % deviation simulations to actual-% at sudden 100% acc pedal

24

800 rpm to 4000 rpm in 2 gear 4.3%

800 rpm to 4000 rpm in 3rd gear 6.2%

800 rpm to 3500 rpm in 4th gear 1.5%

800 rpm to 3000 rpm in 5th gear 2%

4.Conclusions and summary

� Engine dynamic torque is limited by smoke limitation and smoothend by powertrain

oscillations

� Engine dynamic torque behaviour is not linear without surge dampening calibration.

� Turbocharger lag in each gear successfully predicted using GT simulations tool.

� Engine dynamic torque behaviour is predicted to accury above 94% .

2525

25

� Turbocharger dynamic moment of inertia or vane hysterysis needs to be included in

the model to improve the boost pressure predictive capability to a better level

especially at very high engine speeds in lower gears

� Engine ECU logics &controls ,and TC modelling is very convinient in GT power tool

Further actions:

� 1.Dynamic Tc moment of inertia modelling & ASD LIG ECU logic adding to model

� 2. Extending the mode to predict the part throttle driveabilty & BSFC prediction in

NEDC cycle by modelling full vehicle and temperature solvers.

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