VIRTUAL ENGINE CALIBRATION USING 1D- SIMULATION MODELS · Virtual engine calibration using 1D-simulation models, BMW Group Ulrich Knoll, 24.10.2011 Page 3 VIRTUAL ENGINE CALIBRATION

VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS EUROPEAN GT-SUITE CONFERENCE – FRANKFURT AM MAIN – 24.10.2011 ULRICH KNOLL

BMW-Group, EA-71, 24.10.2011

Virtual engine calibration using 1D-simulation models, BMW Group

Ulrich Knoll, 24.10.2011 Page 2

VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS. CONTENT.

– Objectives for virtual engine calibration

– Virtual engine calibration tasks

– Adjustments on air mass flow

– Combustion UserModel including turbulence model

– Application examples



VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS. OBJECTIVES FOR VIRTUAL ENGINE CALIBRATION.

Objectives for modern engine development with increasing complexity:

– reduction of development time

– reduction of engine test bench effort

– reduction of development costs

BMW Group uses 1D-simulation models for virtual engine calibration




Engine complexity:

– valve timing (intake and exhaust) variability: 70° CA

– intake valve lift: continuous up to 10 mm

– boost pressure: up to 2 bar absolute

– direct injection: timing, pressure and splitting




Replacing engine measurements with 1D-simulations:

– more operating points in less time

– engine variants are easy to estimate

– few measured operating points needed for calibration

faster, cheaper and earlier











VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS. VIRTUAL ENGINE CALIBRATION TASKS.

– load detection

air mass in cylinder in current operating point (engine speed,

valve timing, valve lift, wastegate and throttle angle, etc.)?

– torque structure

engine torque in current operating point (air mass in cylinder,

engine speed, ignition timing)?

– exhaust temperature model

fuel energy via in-cylinder heat transfer to walls (engine speed,

load, air-fuel-ratio)?











VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS. ADJUSTMENTS ON AIR MASS FLOW.

Existing full load model has to be adjusted in part load operating points

air mass flow error: measurement - full load model




– adjusting turbine map in low speed points

– editing discharge coefficients of valves (reverse)*

– special focus on valve overlap

– adjusting controller for wastegate and throttle for convergence issues

* method introduced by:

Christian Roithmeier, Virtuelle Applikation von Motorsteuerungsfunktionen am Beispiel der Lasterfassungsfunktion und der

Fahrdynamikfunktionen. PhD thesis, TH Karlsruhe, 2011.

Christian Roithmeier, Nico Neuweiler, Christoph Luttermann, and Alexander Mitterer. Calibration methods for air charge

determination based on measurement and simulation data. In Automotive Workshop Spa, 2006.

Refined model improves part load operating points




air mass flow error: measurement – adjusted model

now further modeling steps can use the air charge inputs











VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS. COMBUSTION USER-MODEL INCLUDING TURBULENCE MODEL.

Turbulence model:

source: Sebastian Grasreiner, Combustion modeling for virtual SI engine calibration with the help of 0D/3D methods.

TU Bergakademie Freiberg, PhD thesis, 2011.




Turbulence model (Validated with CFD data):

source: Ulrich Knoll, One-dimensional simulation of a turbocharged spark ignition engine with direct injection and variable valvetrain for virtual

calibration purposes. Hochschule für angewandte Wissenschaften München, master thesis, 2011.

C.f. Sebastian Grasreiner, Quasi-dimensional modeling of turbulence and global charge motion for new BMW spark ignition engines.

8th Syposium POWERTRAIN CONTROL SYSTEMS FOR MOTOR VEHICLES, 2011.

eng

ine

load

engine speed




Combustion model:

User-Routine built as 0D entrainment model

burned area

entrained flame

area (incl. burned area)

unburned area




Combustion model:

gross imep error: measurement - adjusted model











VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS. APPLICATION EXAMPLES.

Load detection:




Torque structure:

late early

ignition

source: Ulrich Knoll, One-dimensional simulation of a turbocharged spark ignition engine with direct injection and variable

valvetrain for virtual calibration purposes. Hochschule für angewandte Wissenschaften München, master thesis, 2011.




Torque structure:

optimal indicated torque optimal ignition timing

source: Sebastian Grasreiner, Combustion modeling for virtual SI engine calibration with the help of 0D/3D methods.

TU Bergakademie Freiberg, PhD thesis, 2011.




Exhaust gas temperature model:

ECU function model:

normed heat transfer to cylinder wall

source: Sebastian Grasreiner, Combustion modeling for virtual SI engine calibration

with the help of 0D/3D methods. TU Bergakademie Freiberg, PhD thesis, 2011.



VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS. CONCLUSION.

– Adjustments on GT-Power model necessary

air mass flow

combustion and turbulence model

– BMW Group uses physical models for virtual engine calibration as tool

in serial engine production.



VIRTUAL ENGINE CALIBRATION USING 1D-SIMULATION MODELS.

Thank you for your attention.

Questions?

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VIRTUAL ENGINE CALIBRATION USING 1D- SIMULATION MODELS · Virtual engine calibration using 1D-simulation models, BMW Group Ulrich Knoll, 24.10.2011 Page 3 VIRTUAL ENGINE CALIBRATION