Spray-Turbulence Interaction

Report
Spray-Turbulence Interaction
Anne Kösters
Ph.D. student
Spray-Turbulence Interaction
PhD student:
Project start:
Project finish:
Anne Kösters
February 2010
November 2014
Financed by:
Budget/ year:
1 090 000 SEK
Background
Diesel Spray
T ~ 900 K
Pgas= 60 bar
Pinj = 1350 bar
Experiments done in Chalmers Spray Rig by Chengjun Du
Goal
Goal is to investigate spray-turbulence and turbulencechemistry interaction, and to incorporate the findings into
spray combustion models.
Approach
• Implementation and improvement of models to predict
spray formation (VSB2) and turbulence-chemistry
interaction (VRFM, RIF) in OpenFOAM®
• Detailed investigation of Diesel spray behavior and
flame structure, maintained by the implemented models
Modeling of an evaporating spray
with combustion
Liquid
phase
Spray modeling
CFD solution
(gas)
Chemistry
Combustion
modeling
Spray
Method: VSB2 Spray Model
Kösters, A. & Karlsson, A., ”A Comprehensive
Numerical Study of Diesel Fuel Spray Formation in
OpenFOAM”, SAE Technical Paper, 2011-01-0842,
2011.
Journal Paper (submitted to Atomization and Sprays):
Kösters, A. and Karlsson, A., ”The VSB2 spray model
validated against Spray A and Spray H”
Experiments: Chalmers HP/HT Spray Rig
by Raúl Ochoterena
Pinj = 600bar
Pgas = 30 bar
Tgas = 500 °C
Pinj = 1200bar
Pgas = 30 bar
Tgas = 500 °C
Pinj = 600bar
Pgas = 70 bar
Tgas = 500 °C
Pinj = 1200bar
Pgas = 70 bar
Tgas = 500 °C
Baseline condition ECN*: liquid penetration vs time
ρ = 22.8 kg/m3; T = 900 K; pinj = 150 MPa
Penetration [mm]
Flame
lift-off
20
Spray A:
n-dodecane
18
CMT
PoliMI
16
Chalmers
ANL
14
SANDIA
Exp. (SANDIA - 675)
12
10
8
Ignition delay (baseline)
6
4
2
0
0.0
0.3
0.6
0.9
1.2
Time ASOI [ms]
*ECN : Engine Combustion Network, results from Workshop 3, 2014
www.sandia.gov/ecn
1.5
Baseline condition: axial mixture fraction at 1.5 ms
Vapor mixture Fraction [-]
1.00
Pure vapor
region
0.80
SANDIA
CMT
PoliMI
Chalmers
Exp
ANL
0.60
0.40
0.20
0.00
0.0
10.0
20.0
30.0
40.0
50.0
Liquid + VaporAxial Distance from injector nozzle [mm]
region
60.0
Combustion
Method: WS, VRFM+ and mRIF* model
A. , Golovitchev, V. & Karlsson, A., ”A Numerical
Study of the Effect of EGR on Flame Lift-off in n-Heptane
Sprays Using a Novel PaSR Model Implemented in
OpenFOAM”, SAE International Journal of Fuels and
Lubricants, vol. 5 no. 2 604-610, May 2012.
+ Kösters,
*Pitsch, H., Wan, Y.P. & Peters, N. ”Numerical Investigation of
Soot Formation and Oxidation Under Diesel Engine Conditions”,
SAE Paper 952357, 1995.
*Peters, N., Turbulent Combustion, Cambridge University Press,
2000.
Journal Paper (submitted to Combustion Theory and Modelling):
+ Kösters, A., Karlsson, A., Oevermann, M., D’Errico, G. and
Lucchini, T. ,” RANS predictions of turbulent diusion ames:
comparison of a reactor and a amelet combustion model to the
well stirred approach”
Comparison of combustion models
Chemistry
Computational costs
mRIF
VRFM
WS
Yi(Z,t)
(decoupled from flow field)
Yi(x,y,z,t)
Yi(x,y,z,t)
cheap
high
high
Computational
cell
30 flamelets
Computational
cell
Experiments:
ECN data of n-heptane spray
combustion (spray H)
Ignition delay
Lift-off length
Ignition delay
Lift-off length
Lift-off length
10% O2
Tgas = 1000 K,Combustion
pgas = 42 bar, O2 = 10 %
Summary PhD Project
•
•
•
•
•
•
•
•
•
•
VSB2 spray model implemented in OpenFOAM 1.6.x and 2.0.x
VSB2 spray model further developed
Validation against experimental data of Chalmers HP/HT Spray Rig
Validation against ECN data
Comparison with other groups/models within the ECN
Further results (sensitivity studies) are published
VRFM implemented in OpenFOAM 1.6.x and 2.0.x
VRFM further developed
Validation against ECN data
Detailed comparison to the direct chemistry approach and the multiple RIF
model
My Future Work
•
Defense of Ph.D. at November 7th
(others)
•
•
•
Future Work
Studying and understanding the processes close to
the nozzle exit
Multi-component evaporation
Coupling of premixed and diffusion combustion
models
Thank you for your attention

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