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