Advanced Research in Diesel Fuel Sprays Using X-rays From The Advanced Photon Source

Christopher F. PowellArgonne National Laboratory

DEER 2003, Newport, RI 26 Aug, 2003

DOE Program Manager:Gurpreet Singh

Project Motivation• Goal: Understand the mechanisms of spray atomization

– In-Nozzle effects - cavitation, nozzle structure– Aerodynamic effects - air entrainment, stripping, coalescence– Relative magnitudes unknown– Difficult to develop accurate spray models

• Accurate modeling is important for emissions– Engine testing is time-consuming, expensive– Modeling supplements real-world tests

• Current spray models assume an initial fuel distribution– Initial conditions uncertain– Little quantitative data exists in near-nozzle region– Visible light techniques limited by scattering– Lack of existing data, lack of reliable models

• X-Ray technique– Scattering is negligible– Quantitative measurement of fuel, even near the nozzle– Provide data necessary for accurate models– Unique diagnostic tool

Schematic of X-Ray Setup

( )MII Mµ−= exp0

I0I

I0 Incident x-ray intensity

I Measured x-ray intensity

µM Fuel absorption constant

M Mass of fuel in x-ray beam

Direct relation between x-ray intensity and fuel mass

X-Ray Image Reconstruction

• Image is built from measurements at over 1500 different positions

• Image represents line-of-sight mass distribution

Axial Position (mm)

500

35

1.6

-1.60

0

Mass/Area (µg/mm2)

0 2.000 4.000 6.000 8.000 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00 32.00 34.00 36.00 38.00 40.00 42.00 44.00 46.00 48.00 50.00

Injection Pressure = 500 barAmbient Pressure = 1 bar N2200 µs after SOI

Measurement Conditions

Common rail diesel, mini-sac nozzle, single hole

Orifice diameter 180 µm

Fuel pressure 500 bar

Pulse duration 400 µs

Spray chamber gas N2 @ 1-10 bar, 25 °C

Fuel Additive Ce compound, 10%

Data Averaging 50-150 sprays

Sprays Under Different Ambient Pressures

Injection Pressure = 500 bar135 µs after SOI

Axial Position (mm)

1 bar N2

75

1501.0

-1.00

Mass/Area (µg/mm2) Tr

ansv

erse

Pos

ition

(mm

)

5 10 150

2 bar N2

0

1.0

-1.00

5 bar N2

1.0

-1.00

Animation of X-Ray Measurements

Injection Pressure = 500 bar

1 bar

0.6 0.6 1.01.0 0.20.2

0

0

0.2

-0.20.2

-0.2Tran

sver

se P

ositi

on (m

m)

Axial Position (mm)

Mass/Area (µg/mm2)

2 bar

5 bar

10 bar

120

60

180

0

Near-Nozzle Mass Distributions

Injection Pressure = 500 bar280 µs after SOI

Near-Nozzle Spray Structure

Smallwood and GülderAtomization and Sprays 10, 2000.

200

100

010 bar0.6 1.00.2

0

0.2

-0.2Tran

sver

se P

ositi

on (m

m)

Axial Position (mm)

Mass/Area (µg/mm2)

Future Work• Continue Analysis of Current Data

– Effects of ambient and injection pressure on atomization

• Collaborations with modeling groups– Develop new models of spray structure

• Measurements at Higher Ambient Pressure– Recent measurements at 10 bar.– Plans to measure up to 25 bar in 2004

• Measurements at High Pressure, Temperature– “Diesel-Like” conditions– Rapid Compression Machine for x-ray measurements

AcknowledgementsRobert Bosch GmbHPhillip BohlJohannes SchallerJochen Walther

Argonne National LabSeong-Kyun CheongJinyuan LiuSuresh NarayananJin WangSteve CiattiYong YueRoy CuencaDeming ShuRaj Sekar

Rhodia Rare EarthsPatrick Fournier-Bidoz

This work is supported by the U.S. Department of Energyunder contract W-31-109-Eng-38 and by the Office of

FreedomCAR and Vehicle Technologies. Experiments were performed at the 1-BM beamline of the Advanced Photon

Source, Argonne National Laboratory.

Department of EnergyGurpreet Singh

Challenges of X-Ray Measurements• Fuels inherently have low absorption

– Low energy (long wavelength) x-rays– Metal fuel additive– Average results from multiple sprays

• Combustion engines operate at high pressure– Pressurized gases attenuate x-rays– X-ray windows must support pressure without attenuation

1 bar 0.902 bar 0.815 bar 0.6010 bar 0.37

X-ray transmission through 50 mm N2

at 6 keV

Near-Nozzle Mass Distributions

-0.2 0.0 0.20.0

1.0

2.0

3.0

4.0

-0.2 0.0 0.20.0

2.0

4.0

6.0

8.0

-0.4 -0.2 0.00.0

1.0

2.0

3.0

4.0

5.0

1 bar

Mas

s of

Fue

l (µg

)

2 bar

Transverse Position (mm)

5 bar

200 µm from nozzleInjection Pressure = 500 bar115 µs after SOI

1 bar N2

0.8

-0.80

5 10 150

2 bar N2

0.8

-0.80

5 bar N2

0.8

-0.80

Maximum Volume Fraction

0.33 0.10 0.04

0.50 0.22 0.47

0.42 0.13 0.48Injection Pressure = 500 bar115 µs after SOI

Spray is Atomized 2 mm From Nozzle

2 mm from nozzleInjection Pressure = 500 bar115 µs after SOI

-0.4 -0.2 0.0 0.2 0.40.0

0.1

0.2

0.3

0.4

0.5

-0.4 -0.2 0.0 0.2 0.40.0

0.1

0.2

0.3

0.4

0.5

-0.6 -0.4 -0.2 0.0 0.20.0

0.1

0.2

0.3

0.4

0.5

1 bar

Fuel

Vol

ume

Frac

tion

2 bar

Transverse Position (mm)

5 bar

Rapid Compression Machine for X-Ray Studies

• Opposed Piston design to minimize vibration

• X-ray windows will be significant technical hurdle

• Operational in 2003• X-ray Measurements in 2004

Design GoalsPressure 40 barTemperature 400 C

• Injection chamber moves to probe different areas of spray• Image is measured one pixel at a time• Each pixel obtained by averaging results from many sprays• Measure thousands of individual pixels

• Fast detector, continuous measure of x-ray intensity• Time-resolved measurement of fuel mass

Schematic of X-Ray Setup

Advantages of X-Rays

• Techniques utilizing visible light are limited near nozzleScattering from droplets is likelyMultiple scattering prevents quantitative analysis

• X-rays have low scattering probabilityMultiple scattering negligibleAbsorption is most likely interaction

• Quantitative measurementsDirect measurement of the mass of fuelIntense beam, fast detector permit time-resolved measurement

Modeling the Cross Section of the Spray

Volume Fraction = density / bulk fuel density

( ) ( )taA

trMtrcπ2,, =

( ) ( ) ( )220 2exp, taytMtyM −=

Comparison of Different Ambient Pressures

Injection Pressure = 1000 bar45 µs after SOI

Axial Position (mm)

1 bar N2

75

1500.8

-0.80

Mass/Area (µg/mm2)

Tran

sver

se P

ositi

on (m

m)

-0.80

0.85 bar N2

5 10 150

2 bar N2

0

0.8

-0.80