Objective - unina.itwpage.unina.it/anddanna/capri/capri definitivo/13a... · Objective Compression Ignition Diesel Engine Gasoline Engine HCCI Engine Spark Ignition Homogeneous Charge

1

Non interfering diagnostics for the study of thermofluidynamic processes in

ICEB. M. Vaglieco

Istituto Motori – CNR

Napoli, ITALY

Study of chemical and physical phenomena in internal combustion engine by non intrusive

techniques at high spatial (< micron) and temporal resolution (nanosecond)

Objective

CompressionIgnition

Diesel Engine Gasoline Engine HCCI Engine

SparkIgnition

Homogeneous ChargeCompression Ignition

Fuelinjector

NOsoot

Sparkplug

Flame frontNO

Hot Flame Low temperature combustion

Combustion

Engine parameters

Exhaust emissionsHC, O2, CO, CO2, NOXparticulate mass concentration

UV-IR analyzer and opacimeter

In-cylinder pressurequartz piezoelectric pressure transducer

CONVENTIONAL MEASUREMENTS

spark and injectioncurrent and voltage sensors

PiezoelectricPressure transducer

Determination of Start of Combustion

The heat release indicates : in the absolute minimum the overcoming of the first exothermic combustion reactions with respect to endothermic due to the evaporation of fuel injected

The variation of slope of pressurecurve

2

-10 0 10 20 30 40 50

Crank Angle Degree

0

10

20

30

40

50

Pre

ssur

e [b

ar]

GAS90

ST=13 CAD BTDC

ST=3 CAD BTDC

(d)

0 10 20 30 40

Crank Angle Degree

-1.2

-0.8

-0.4

0

0.4

0.8

1.2

knoc

k pr

essu

re [b

ar]

(d)

ST=13 CAD BTDC

Pressure measurements

•Non intrusive techniques

•High spatial and temporal resolution

Non interference on phenomena

Capability to follow stationary phenomena and to measure “in situ”

Interaction light-matter

Qualitative and quantitative characterization on transient phenomena in optically accessible combustion system

EXCITATIONOccurs when an electron in an atom is given energy causing it to jump to a higher orbit. This can happen through collisions or photon absorption (the photon absorption must exactly match the energy jump).

The excited atom usually de-excites in about 100 millionth of a second.The subsequent emitted radiation has an energy that matches that of the orbital change in the atom. This emitted radiation gives the characteristic colors of the element involved

Radio waves are produced byelectrons moving up and down an antenna

Visible light is produced byelectrons changing energy states in an atom

ELECTROMAGNETIC SPECTRUMEM WavesRadio WavesMicrowavesInfraredVisibleUltravioletX-raysGamma rays

SourcesVibrating chargesMolecular rotationsMolecular vibrationsAtomic vibrationsAtomic vibrationsAtomic vibrations Nuclear vibrations

Emission SpectraContinuous Emission Spectrum

Prism

Photographic Film

Slit

White LightSource

Emission Spectra of Hydrogen

Prism

Photographic Film

Film

Slit

Low DensityGlowing

Hydrogen Gas

Discrete Emission Spectrum

3

Discrete Absorption Spectrum

Absorption Spectraof Hydrogen

Prism

Photographic Film

Film

Slit

White LightSource

Discrete Emission Spectrum

Hydrogen Gas

ABSORPTION SPECTRA

•Frequencies of light that represent the correct energy jumps in the atom will be

absorbed.

•When the atom de-excites, it emits the same kinds of frequencies it absorbed.

•However, this emission is in all directions.

INCANDESCENCE

Electron transitions occur not only in the parent atom but in adjacent atoms as well

FLUORESCENCE

•Some materials that are excited by UV emit visible.

•These materials are referred to as fluorescent materials.PHOSPHORESCENCE

•Electrons get "stuck" in excited states in the atoms and de-excitation occurs at different times for different atoms.

•A continuous glow occurs for some time.

•Bioluminescence

MAGIC BOXMAGIC EYE

pros•non-intrusive method•simultaneous multispecies detection (spectroscopy)•differentiation at same wavelength (chemiluminescence)•cons•line-of-sight method• low signal/noise

UV-visible natural emission

Quartz window

UV mirror

Quartz window

UV mirrorhν

hν

hν

hν

h CFD and optical measurement are suitable tools for explanation of complicated combustion mechanism.

h If the other sub-models (spray,etc) are effective, recent CFD with detailed kinetics model is though to be robust or adaptable to the various combustion and emission description.

4

Commercial cylinder head

Common Rail InjectorConditioned

intake Air

section view

Coolant temperature control system

Non lubricated condition(Bronze-Teflon Ring)

Exhaust gas

Transparent diesel engine Transparent engine

13

13

2 Toroidal bowl optical access diameter = 34mm;Lateral window diameter =14mm

Lateral and Top Cross-Sections

upper edge ofbowl

edge of quartz window in bottom piston

upper edge ofbowl

edge of quartz window in bottom piston

FRONT VIEW

exhaust valve replaced by quartzwindow

injector

pressure transducer

upper edge ofbowl

TOP VIEWOUT IN

Optical Setup

Common Rail

Pump

PC

Unit Control

Electric Engine

UV-Mirror

Injector

Encoder

CCD

CCD

Digital imagingCCD camera 640x480 pixels - Minimum exposure time 10 μs

1cad=166.66μs @1000rpm

Common Rail

Pump

PC

Unit Control

Electric Engine

UV-Mirror

Injector

Encoder

CCD

CCD

Common Rail

Pump

PC

Unit Control

Electric Engine

UV-Mirror

Injector

Encoder

CCDCCD

CCDCCD

Digital imagingCCD camera 640x480 pixels - Minimum exposure time 10 μs

1cad=166.66μs @1000rpm

Acquisitionthrough pistoncrown window

CCD

DIGITAL IMAGINGof fuel spray and combustion phase

Pre+Main InjectionInj. Pressure 600 bar

-30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30crank angle [degree]

0

10

20

30

40

50

60

70

Com

bust

ion

Pres

sure

[bar

]

0

20

40

60

80

100

RO

HR

[kJ/

kg/C

AD]

0

10

20

Driv

e C

urre

nt [A

mpe

re]

Pre+M

PSOC Pre

PSOC M

-30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30crank angle [degree]

0

10

20

30

40

50

60

70

Com

bust

ion

Pres

sure

[bar

]

0

20

40

60

80

100

RO

HR

[kJ/

kg/C

AD

]

0

10

20D

rive

Cur

rent

[Am

pere

] M PSOC

Main Injection

Experiments vs ModellingPre

7.0 BTDC

6.5 BTDC

2.5 ATDC

3.5 ATDC

Main

Autoignition

R1) H + O2 = O + OH

R2) O + H2 = H + OH

R3) H2 + OH = H2O + H

H2 as fuel

Heywood, 1988

5

Autoignition phase of pre injection occurs during the first times of main injection

Spectra at Autoignition of Pre + Main

0

100000

200000

300000

400000

500000

Emis

sion

inte

nsity

[a.u

.]

220 250 280 310 340 370 400 430 460Wavelength [nm]

α

β

γ

OH

αβγ

0

100000

200000

300000

400000

500000

Emis

sion

inte

nsity

[a.u

.]

220 250 280 310 340 370 400 430 460Wavelength [nm]

α

β

γ

OH

αβγ

αβγ

1.5° BTDC=1.5°ASOCpre

OH

220 250 280 310 340 370 400 430 460

Wavelength [nm]

0

10000

20000

30000

40000

Em

issi

on in

tens

ity [a

.u.]

α

β

γOH

CH3° BTDC=SOCpre

220 250 280 310 340 370 400 430 460

Wavelength [nm]

0

100000

200000

300000

400000

Emis

sion

inte

nsity

[a.u

.]

α

β

γ

OH

CH2.4° BTDC=0.6°ASOCpre

α

βγ

α

βγ

Black body

• Brightness versus color curve for different temperatures

(measured in Kelvins)

0.0

0.1

0.1

0.2

0.2

0 500 1000

Wavelength (nm)

Rel

ativ

e E

nerg

y

Tf ∝

3° btdc

Visible FlameTemperature Soot

2500

Temperature scale [K]

1850 3000KL factor scale

0 15

Soot mass concentration[mg/m3]

0 44

Imaging, Temperature and Soot concentration1000 rpm - Pinj 600 bar

-10 0 10 20 30 40 50 60Crank angke [degree]

0

10

20

30

RO

HR

[kJ/

kg/C

AD

]

0

10

20

30

Curr

ent [

Am

pere

] 2° btdc


2500



0 15


0 44



0

10

20

30

RO

HR

[kJ/

kg/C

AD

]

0

10

20

30

Curr

ent [

Am

pere

]

tdc


2500



0 15


0 44



0

10

20

30

RO

HR

[kJ/

kg/C

AD

]

0

10

20

30

Curr

ent [

Am

pere

] 16° atdc


2500



0 15


0 44



0

10

20

30

RO

HR

[kJ/

kg/C

AD

]

0

10

20

30

Curr

ent [

Am

pere

]

6

New concepts for diesel combustion

P. Pinchon at al., IFP – Thiesel 2004

Late injection

MK Concept Nissan Motors

HiMIcs HINO Motors

UNIBUS - PCI

PREDIC/MULDIC

HCCI Denbratt

Injections per cycle

1 4 2 3 (with 3 injectors) 5

Compression ratio 18:1 16:1 18:1 Varied

12:1 to 21:1 16.5:1 Varied 17:1 to 11.5:1

Displacement [cc] 488 - 622 2147 915 - 2000 2004 480

Fuel wall impingement

very limited yes yes yes yes

EGR rate [%] high low high high high

Load range limited large large very limited large

Test speed [rpm] 1200 - 2000 1000 - 1600 1000 1000 2000

Knock at high load

no no high high no

NOx very low low very low very low very low

Smoke very low low very low improved very low

Early injection

Engine speed: 1000rpm - Fuel amount: 8 mm3/stroke

Injection strategies

-40 -30 -20 -10 0 10 20 30 40crank angle [degree]

0

10

20

30

40

50

60

70

Com

bust

ion

Pres

sure

[bar

]

0

20

40

60

80

100

RO

HR

[kJ/

kg/C

AD]

0

10

20

Driv

e C

urre

nt [A

mpe

re]

Pinj = 600 bar

-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40crank angle [degree]

0

10

20

30

40

50

60

Com

bust

ion

Pre

ssur

e [b

ar]

0

20

40

60

80

100

RO

HR

[kJ/

kg/C

AD

]

0

10

20

Driv

e C

urre

nt [A

mpe

re]

Pinj = 700 bar

CR HCCI

Pinj

[bar]Tin

[°C]

Pin

(abs) [bar]

Fuel [Kg/h]

BMEP [bar]

SOI Pilot

[°]

ET Pilot [μs]

SOI Pre [°]

ET Pre [μs]

SOI Main

[°]

ET Main [μs]

SOI Post

[°]

ET Post [μs]

SOI After

[°]

ET After [μs]

CR Pre+Main+Post 600 44 1.33 0.32 3.0 \ \ -9 400 -4 625 11 340 \ \

HCCI 700 35 1 0.30 2.4 -70 400 -60 400 -50 400 -40 400 -30 400

-70 -60 -50 -40 -30 -20 -10 0 10 20 30Crank angle [degree]

0

40

80

Rate

Of H

eat R

elea

se [k

J/kg

/CA

D]

0102030

Driv

e cu

rren

t [Am

pere

]

0 2 4 6 8 10 12 14 16Time ASOI [ms]

0

100

200

300

400

500

600

700

800

900

1000

Tem

pera

ture

[K]

Ignition delay LTR HTR

Heat release rate for HCCI68° btdc 58° btdc 48° btdc 38° btdc 28° btdc

I II III IV V

I II III IV V

0.5°ASOI

1.0°ASOI

1.5°ASOI

2.0°ASOI

-80 -70 -60 -50 -40 -30 -20Crank angle [degree]

0

5

10

15

20

Cyl

inde

r Pre

ssur

e [b

ar]

0

10

20

Driv

e C

urre

nt [A

mpe

re]

HCCI injection phase

ASOI = After Start Of Injection66° btdc 56° btdc 46° btdc 36° btdc 26° btdc

Pinj = 700 bar

Chemiluminescence Measurements

# 2008-01-0027

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

2000

4000

6000

8000

10000

Em

issi

on in

tens

ity [a

.u.]

OH

CH

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

500

1000

1500

2000

2500

3000

3500

Em

issi

on in

tens

ity [a

.u.]

γ

OH

CH

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

500

1000

1500

2000

2500

3000

3500

Em

issi

on in

tens

ity [a

.u.]

αOH

CH

HCHOHCO

OH is the most important radical for driver the ignition process. It is producing by the decomposition of H2O2 at 1100 K (ref.

2001-01-2077) GAYDON

6° atdc

αβγ

β

-5 -2.5 0 2.5 5 7.5 10 12.5 15Crank angle [degree]

0

40

80

120

RO

HR

[kJ/

kg°]

SOI EOI SOC

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

100000

200000

300000

400000

500000

Emis

sion

inte

nsity

[a.u

.]

β

HCOHCHO

OH

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

20000

40000

60000

80000

Em

issi

on in

tens

ity [a

.u.]

αOH

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

100000

200000

300000

400000

500000

Emis

sion

inte

nsity

[a.u

.]

γ

OH

Chemiluminescence Measurements

10° atdc

αβγ


0

40

80

120

RO

HR

[kJ/

kg°]

SOI EOI SOC

7

10° atdc 12° atdc 14° atdc

Chemiluminescence MeasurementsIn the whole chamber

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

20000

40000

60000

80000

Em

issi

on in

tens

ity [a

.u.]

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

50000

100000

150000

200000

250000

300000

Em

issi

on in

tens

ity [a

.u.]

300 325 350 375 400 425 450 475 500Wavelength [nm]

0

20000

40000

60000

80000

100000

120000

Em

issi

on in

tens

ity [a

.u.]


0

40

80

120

RO

HR

[kJ/

kg°]

SOI EOI SOC

OH radical is a good marker of LTC combustion process

HCCI vs CR visible combustion

13° BTDC 12° BTDC 10° BTDC 8° BTDC9° BTDC 7° BTDC11° BTDC

-15 -10 -5 0 5 10 15 20 25 30 35 40Crank angle [degree]

0

0.2

0.4

0.6

Mea

n K

L fa

ctor

for H

CC

I stra

tegy

0

20

40

60

Rat

e O

f Hea

t Rel

ease

[kJ/

kg/c

ad]

-15 -10 -5 0 5 10 15 20 25 30 35 40Crank angle [degree]

0

2

4

6

Mea

n K

L fa

ctor

for C

R s

trate

gies

0

20

40

60

Rat

e O

f Hea

t Rel

ease

[kJ/

kg/c

ad]

CRHCCI

3° BTDC TDC 4° ATDC 10° ATDC 15° ATDC 21° ATDC17° ATDC

1 10 100 1000diameter [nm]

1.0x100

1.0x104

1.0x108

1.0x1012

num

ber c

once

ntra

tion

[par

t*cm

-3]

40° ATDC52° ATDC66° ATDC

Exhaust particle size distribution

1 10 100 1000

1.0x100

1.0x101

1.0x102

1.0x103

1.0x104

1.0x105

1.0x106

1.0x107

1.0x108

1.0x109

Primary and secondaryparticles at exhaust

Electrical Low Pressure Impactor

Experimental method for exhaust characterization

SOOT

Nitrogen Oxides

OPACIMETER SMOKE METER CHEMICALANALYSIS

N% FSN DRYSOOT

SOF

OPACIMETER SMOKE METER CHEMICALANALYSIS

N% FSN DRYSOOT

SOF

PARTICULATEMASS

CONCENTRATION

EXTINCTION

VOLUME FRACTION

OPTICAL TECHNIQUE

SCATTERING

PARTICLE SIZE NUMBER

DISTRIBUTION

NUMBERCONCENTRATION

CHEMILUMINESCENCE ANALYSER

INFRARED ANALYSER

NUMBERCONCENTRATION


INFRARED ANALYSER

NUMBERCONCENTRATION


INFRARED ANALYSER

NUMBERCONCENTRATION


INFRARED ANALYSER

OPTICAL TECHNIQUE

OPTICAL TECHNIQUE

ABSORPTION CROSS

SECTION

ABSORPTION SPECTROSCOPY

OPTICAL TECHNIQUE

OPTICAL TECHNIQUE

ABSORPTION CROSS

SECTION


ABSORPTION CROSS

SECTION


Experimental Apparatus

in

Nd:YAG

1064nm

extinction

scattering

Gas analysers ELPI

DILUTER

Opacimeter

PLANO-CONVEX

LENS

Nd:YAG

BEAM SPLITTER

out

Spectrometer

ICCD

BICONVEX LENS

CDPF

Still plugvalve

PLANO-CONVEX

LENS

Pulsed nanosecond light source: laser

induced optical breakdown

EXTINCTION and SCATTERING SPECTRA

200 250 300 350 400 450 500 550wavelength [nm]

0.0x100

2.0x10-3

4.0x10-3

6.0x10-3

8.0x10-3

1.0x10-2

1.2x10-2

1.4x10-2

1.6x10-2

1.8x10-2

extin

ctio

n co

effic

ient

[cm

-1] NO

soot

1500rpm - 2bar

1500rpm - 5bar

200 250 300 350 400 450 500 550wavelength [nm]

0.0x100

2.0x10-3

4.0x10-3

6.0x10-3

8.0x10-3

1.0x10-2

1.2x10-2

1.4x10-2

1.6x10-2

1.8x10-2

extin

ctio

n co

effic

ient

[cm

-1] NO

soot

1500rpm - 2bar

1500rpm - 5bar

200 250 300 350 400 450 500 550wavelength [nm]

0.0x100

5.0x10-7

1.0x10-6

1.5x10-6

2.0x10-6

2.5x10-6

3.0x10-6

3.5x10-6

4.0x10-6

4.5x10-6

scat

terin

g co

effic

ient

[cm

-1 s

r-1]

1500rpm - 2bar

1500rpm - 5bar

200 250 300 350 400 450 500 550wavelength [nm]

0.0x100

5.0x10-7

1.0x10-6

1.5x10-6

2.0x10-6

2.5x10-6

3.0x10-6

3.5x10-6

4.0x10-6

4.5x10-6

scat

terin

g co

effic

ient

[cm

-1 s

r-1]

1500rpm - 2bar

1500rpm - 5bar

8

1 10 100 1000Diameter [nm]

0.0x100

1.0x1010

2.0x1010

3.0x1010

Num

ber C

once

ntra

tion

[#/c

m3 ] Discr = 11%

graphitic10 min

1 10 100 1000Diameter [nm]

0.0x100

1.0x104

2.0x104

3.0x104

Num

ber C

once

ntra

tion

[#/c

m3 ] Discr = 8%

soot15 min

1 10 100 1000Diameter [nm]

0.0x100

4.0x105

8.0x105

1.2x106

Num

ber C

once

ntra

tion

[#/c

m3 ]

Discr = 2%Soot & organic

35 min

0

40

80

120

160

200

0 10 20 30 40 50

Time [min]

Pres

sure

Dro

p [m

bar]

Regeneration

DOWNSTREAM

UPSTREAM

D= 20 nmsoot

t = 10 minD= 15 nmgraphitic-like

t = 35 min D2= 15 nm50% soot50% organic

D1= 30 nmsoot

t = 15 min D= 20 nmsoot

3000rpm-12bar

Transparent spark ignition engine

UV-45°

mirror

Abnormal combustionThe flame front may be started by hot surface either prior to or after spark ignition

Spark knockCan be controlled by the spark advance

Normal combustionThe combustion process startsat spark timings.The flame front moves across the combustion chamber in like-uniform manner.

Heywood J. B. - Internal Combustion Engine Fundamentals New York - McGraw-Hill 1988.

The knock is identified by intense pressure oscillations that arise around the maximum of pressure.

The frequencies of oscillations are typically higher than 5 kHz

-10 0 10 20 30 40 50 60 70CAD

0

20

40

60

Pre

ssur

e [b

ar]

12 22 32 42 52 62 72CAD ASOS

-1

0

1

knoc

k pr

essu

re [b

ar] 10 20 30 40 50 60

CAD

2000 rpm – 1400 mbarStart of Injection 130 CAD BTDC

Duration of injection 96 CADSpark 8 CAD BTDCHigh pass filter 5kHz

The knock is identified by intense pressure oscillations that arise around the maximum of pressure.

The frequencies of oscillations are typically higher than 5 kHz

29.6 CAD ASOS 30.4 CAD ASOS

2000 rpm – 1400 mbarStart of Injection 130 CAD BTDC

Duration of injection 96 CADSpark 8 CAD BTDC0

20000

31.6 CAD ASOS 33.6 CAD ASOS

34.0 CAD ASOS 34.4 CAD ASOS 36.0 CAD ASOS 36.4 CAD ASOS

12 22 32 42 52 62 72CAD ASOS

-1

0

1

knoc

k pr

essu

re [b

ar] 10 20 30 40 50 60

CAD

Knocking phase

Abnormal combustionA combustion process in which a flame front may be started by hot

surface either prior to or after spark ignition

Hot spots and Surface ignition

The hot spots correspond to very small centres of autoignitiondue to exothermic reactions.

In the same time of hot-spots appearancea flame front (ignition surface) starts from spark plug.

This flame is due to the thermal phase of knock (*)

(*)Maly, R.R.- 25th Symp.Int. on Combustion. Combustion Institute Ed. 1994.

9

33.6 CAD ASOS

Ignition surface

KnockHot-spots

DropletsHot-spots

KnockHot-spots

KnockHot-spots

Spark 8 CAD BTDC

[*] Witze, P. O. and Green, R. M.SAE Paper No. 970866, 1997.

Fuel films on cold walls do not fully vaporize during combustion, but instead accumulate over many cycles. [*]

As the engine warms, the lighter components of the film vaporize, leaving a film of increasingly heavy composition;

Eventually, the wall reaches a temperature where the film fully vaporizes.

Pool fire images of gasoline wall films duringa simulated cold start, observed through a

window in the piston [*].

Closed-valve injection Open-valve injection

Intake valves

[**] C. Arcoumanis et al.Int. J. Engine Research – Vol.1 n. 1, 2000.

Valve firingAbnormal combustion

46 CAD ASOS 70 CAD ASOS

0

120

Pool fire: soot concentrationKL

intake

exhaust

intake

exhaust

intake

exhaust

Objective - unina.itwpage.unina.it/anddanna/capri/capri definitivo/13a... · Objective Compression Ignition Diesel Engine Gasoline Engine HCCI Engine Spark Ignition Homogeneous Charge

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