optical diagnostics and modeling tools applied to diesel hcci · caterpillar engine research diesel...

Caterpillar Engine ResearchDiesel & Emissions Technology

Optical Diagnostics and Modeling Tools Applied to

Diesel HCCI

Upul DeSilvaCathy Y. Choi

Caterpillar Engine Research


Optical Diagnostics and Combustion Modeling

• Diesel HCCI is being pursued in order to meet Diesel 2010 emissions requirements

• Optical Diagnostics– Used to gain fundamental understanding of Diesel

HCCI combustion

– Provide data to the combustion modeling team

• Multidimensional Combustion Modeling – To gain further insight into HCCI

– To optimize HCCI conditions to maximize performance


Caterpillar Optical Diagnostic Capabilities

• Non-vaporizing spray chambers– 300 and 400 psi chamber pressure capabilities

– Liquid spray penetration and geometry

– Droplet SMD

• Optically accessible reciprocating engine – Providing access for combustion laser

diagnostics

– Chemiluminescence studies (combustion species)

– PLIF (NO and OH)


Advanced Laser Spray Visualization Facility


Spray From a HCCI tip


Droplet Sizing

SOI + 1ms 1.8ms 2.6ms 3.2ms

3mm

23mm

33mm

43mmfromtip

Droplet SizeRed 150 ?

Light Green 80 ?Dark Blue 3 ?


Comparison of Conventional andHCCI Combustion

Conventional Diesel HCCI


Reactive CFD Modeling for Diesel HCCI Combustion

• Objective: Optimize HCCI combustion for engine emissions and performance.

• Proprietary multi-dimensional reactive CFD code

• LINUX based code• Portions parallelized to increase

computational speed


Computational Facilities

• CAT Engine Research LINUX cluster– ~40 nodes 1.2-1.66 Ghz AMD Athlon

single and dual processors– Cluster currently operates at 256

GigaFlops– Ranked 55 out of top 500

supercomputers in the world– Applications include both CFD codes and

metal stress analyses codes.


HCCI Modeling Issues

• HCCI needs detailed chemistry model– A new combustion model was implemented to

characterize unique aspects of HCCI combustion– Chemistry calculations have been parallelized– Simplified NOx chemistry – Detailed soot chemistry model

• Enhancements to spray submodels– Modified droplet collision model– Modified droplet drag model

-50 -40 -30 -20 -10 0 10 20 30 40 500

200

400

600

800

1000

1200

1400

1600H

RR

, J/d

eg

CA ATDC

• HCCI needs detailed chemistry model– A new combustion model was implemented to

characterize unique aspects of HCCI combustion– Chemistry calculations have been parallelized– Simplified NOx chemistry – Detailed soot chemistry model

• Enhancements to spray submodels– Modified droplet collision model– Modified droplet drag model


NOx Chemistry

Very high computational time

Moderate computational time

Least computational time

Predict NOPredict N2OPredict NO2

Predict other species

Predict NOPredict N2OPredict NO2

Predict NO

Above 2000 reactions

Simple reaction scheme ? 10 reactions

Simple 3 reactions

GRI MechCAT developedExt. Zeldovich


Comparison of NOx Models for a Premixed n-Heptane Flame

0.00E+00

2.00E-03

4.00E-03

6.00E-03

8.00E-03

1.00E-02

1.20E-02

1.40E-02

0 1 2 3 4

Phi

Sp

ecie

s M

ass F

racti

on

NO (Zeldovich)NO (GRI)NO2 (GRI)N2O (GRI)NO (TEB)NO2 (TEB)N2O (TEB)

0.00E+00

5.00E-07

1.00E-06

1.50E-06

2.00E-06

2.50E-06

3.00E-06

0.2 0.25 0.3 0.35 0.4

PhiS

pecie

s M

ass F

racti

on

Zeldovich NOGRI NOGRI NO2GRI N2OCAT NOCAT NO2CAT N2O


Comparison between Experiments and Simulations

Spray Rig Spray Simulation


Comparison of Convention Diesel to HCCI Combustion

Injection Timing: TDC Injection Timing: -20 CA ATDC

Early Injection Timing for HCCI


NOx Emissions Trends

Injection Timing, deg

NO

x, P

PM

Predicted (3171 Engine)Measured at different load (3171 Engine)


Prediction Comparison between CFD and Sandia Optical Engine Data

Sandia Optical Engine Combustion CFD Results


• HCCI combustion technology is being pursued in order to meet Diesel emissions requirements for upcoming 2010 regulations.

• Optical diagnostic and computational tools are being used to gain understanding of HCCI

• Continuing collaborations with National Labs and Universities

Summary

optical diagnostics and modeling tools applied to diesel hcci · caterpillar engine research diesel...

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