FIRST Project Summary of Achievements

26 Pages·2014·1.25 MB·English

FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

FIRST Project Participants
A2 Photonic Sensors (A2PS) MTU Aero Engines AG (MTU)
ARTTIC (ARTTIC) Office National d’Etudes et de Recherches
Aerospatiales (ONERA)
Centre Europeen de Recherche et de Formation
Avancee en Calcul Scientifique (CERFACS) Rolls-Royce Deutschland (RRD)
Centre National de la Recherche Scientifique Rolls-Royce PLC (RRUK)
(CNRS-CORIA / CNRS-LEGI)
SCITEK Consultants (SCITEK)
EnginSoft (EST)
SNECMA (SN)
GE AVIO (Avio Aero)
TURBOMECA (TM)
German Aerospace Center (DLR) FIRST Project
Universita Degli Studi Di Bergamo (UNIBG)
Imperial College of Science, Technology and
Universita Degli Studi Di Firenze (UNIFI)
Medicine (IMPERIAL) Summary of
Université Pierre et Marie Curie – Paris 6 (UPMC)
Karlsruher Institut fuer Technologie (KIT)
Achievements:
Loughborough University (LU)
Advancements in
Project Coordinator
Spray & Soot
Darren Luff Research
SRC Combustion Labs Coordinator
Rolls-Royce Plc
Moor Lane
Derby
DE24 8BJ
United Kingdom
[phone]
[email protected]
This project has received funding from the European Union’s Seventh Framework Programme for research,
technological development and demonstration under grant agreement no 265848
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Introduction
The FIRST project (Fuel Injector Research for The FIRST project has delivered a step change in
Sustainable Transport) was a collaborative project the detail and accuracy of the fuel spray boundary
that ran for 48 months from December 2010 to conditions and the propagation to downstream
2014. Its 7.2M euros budget was partly funded by the conditions. This has been achieved through the
European Union 7th Framework Programme and the implementation of advanced experimental diagnostic
20 industrial and academic project partners. measurements, the development of novel physics
based modelling techniques and the derivation of
Aviation’s environmental impact must be reduced to
sophisticated correlations.
allow sustainable growth to benefit European industry
and society. This is captured in ACARE’s 2020 goals of FIRST has also delivered improved CFD soot models,
reducing CO2 by 50%, NOx by 80% and in SRA1/2 thereby, enabling the reduction of soot in aero-engine
proposed reductions in soot and the development of combustors. These calculations require the improved
alternative fuels. fuel spray boundary conditions provided within the
project and also need the higher fidelity physical and
Consequently, the aims of the FIRST project were
chemical models describing the soot production and
to deliver key enabling technologies for combustion
consumption processes provided from FIRST.
emissions reduction by developing improved design
tools and techniques for modelling and controlling The potential use of future alternative aero fuels
fuel sprays and predicting soot emissions. CFD will be enhanced by the FIRST project as it has
simulations have for many years relied upon over- provided information for performing predictions and
simplistic definitions of the fuel spray for model measurements of both fuel sprays and soot across a
boundary conditions. By understanding and controlling number of different alternative fuel types.
the complex physics of fuel atomisation and the
subsequent mixing the emissions predictions can be
directly improved leading to more competitive aero
combustor designs.
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Table of Contents Glossary
5 Glossary
6 Sprays: Experimental Measurements AMR Adaptive mesh refinement
7 Fundamental mechanisms of assisted atomisation and spray characteristics CARS Coherent Anti-Stokes Raman Scattering
8 Planar liquid sheet atomisation
CFD Computational Fluid Dynamics
9 Fiber optic sensor for sprays: improvements and performance
CPU Central Processing Unit
10 Combined Break-Up Length and Droplet Size and Velocity Distribution Measurements
11 Experimental investigation of the onset of film breakup in an annular prefilmer DFT Density Functional Theory
12 Effect of linear geometrical scaling and aerodynamic boundary conditions of a double swirl airblast DNS Direct Numerical Simulation
atomizer on GSMD
EE/EL Eularian/Lagrangian
13 Characterisation of the Pre-filming Inlet Velocity Field
FGM Flamelet Generated Manifold
14 Time-Resolved Measurements of Fuel Film Thickness on Representative Fuel Injector Geometries
15 Engine Injector Spray Characterisation GSMD Global Sauter Mean Diameter
16 Sprays: Numerical Modelling of Academic Configurations ILIDS Interferometric Laser Imaging Droplet Sizing
17 Development and evaluation of numerical methods for the simulation of primary atomization in aeronautical KS Kinematic Simulation
injection systems
LES Large Eddy Simulation
18 A Multi-Scale Approach For Primary Atomization Modelling
19 Primary break-up modelling using SPH LIF Laser-Induced Fluorescence
20 Modelling of liquid jet primary break-up in swirl atomisers LII Laser-Induced Incandescence
21 Modelling of spray formation in a ULN injector
nPB n-Propyl Benzene
22 A Phenomenological Model for Droplet Dispersion and Clustering
OC Optical Connectivity
23 Sprays: Numerical Modelling of Ideal and Real Injectors
OH Hydroxyl Radical
24 Secondary breakup CFD models
PAH Poly-cyclic Aromatic Hydrocarbon
25 Numerical methods to compute dense spray inside the injector
26 Assisted atomisation process: advanced simulations and comparison with experiments PDA Phase Doppler Anenometer
27 Identification of Spray Boundary Conditions from Measurements PDF Probability Density Function
28 Exploitation film model
PFR Plug-Flow Reactor
29 Exploitation of phenomenological models
PSD(s) Particle Size Distribution
30 Exploitation of phenomenological models
31 Validation of the VOF approach in regards to primary atomization in a model injector PSR/JSR Perfectly Stirred Reactor / Jet-Stirred Reactor
32 Thin film model for prefilming airblast atomizers RANS Reynolds Average Navier Stokes
33 Expert system for liquid breakup RDF Radial Distribution Function
34 Exploitation of spray models
SMD Sauter Mean Diameter
35 Exploration and Exploitation of fundamental models
SPH Smoothed Particle Hydrodynamics or Spherical Particle Hydrodynamics
36 Soot: Experimental and Numerical Investigation of Soot Production
ULN Ultra Low Nox
37 Advanced modelling for complex combustion systems including PAH and soot BINs
38 Improved Soot Nucleation and Oxidation Mechanisms and Links to Surrogate Fuel Chemistry VOF Volume of Fluid
39 Characterisation of a Lean Burn Module Air Blast Pilot Injector with Laser Techniques WSR Well-Stirred Reactor
40 Validation data from sooting, turbulent flames
41 Validation of advanced soot modelling for complex combustion systems
42 Cost-effective numerical simulation of soot formation
43 Exploitation of soot models
44 FIRST Project Participants Directory
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Fundamental mechanisms of assisted
atomisation and spray characteristics (CNRS-LEGI)
1. State of the Art before the FIRST
project
Assisted atomisation is widely exploited for fuel injection
in aero-engines, but the involved complex break-up
phenomena are only partly understood. Prior to the
FIRST project, some data and a few phenomenological
models were available to evaluate the size of drops
formed by stripping. Much less was known on the
large-scale instabilities of jets.
2. Research & Development
Activities Performed
Extensive finely controlled experiments were
performed to identify the influence of flow conditions
and of injection geometrical parameters on spray
characteristics. Dedicated measuring techniques
were developed together with stability and/or
phenomenological analysis. These activities also
benefited from advances in phase detection probes
and in direct simulations as developed by partners of
the FIRST project.
3. Advancement of Capability due to
the FIRST project
Beside the production of a data base over a wide
range of flow conditions and more than 10 injector
geometries, our understanding of atomisation
process has been significantly improved. In particular,
quantitative agreements between stability theory and
4. Additional information
experiments have been obtained for the first time
on the interfacial instabilities leading to the stripping Application: Fuel injection in aero-engines
of drops off the liquid film. The size of drops due Research area: Fundamental mechanisms controlling
to stripping remains strongly controlled by internal assisted atomisation
injector design, with a diameter evolving from a few Technology readiness level: 3
Sprays: s
(at high gas velocities representative of take-off) up Owner of IPR: CNRS – LEGI t
n
to 20 (at low gas velocity representative of cruise FIRST Task: T3.1.1 me
regime) times the gas vorticity thickness at injection. Main author and contact: Alain Cartellier, CNRS re
u
For large scale instability, new data were gathered on s
a
flapping frequency, size distributions, fluxes and their e
M
evolution with control parameters: the corresponding al
Experimental Measurements drops happen to be typically ten times larger than nt
e
those due to stripping. Moreover, hidden parameters m
acting on the axial instability that open the way to new eri
p
atomisation control strategies were also unveiled. x
E
These advances provide useful guidelines for optimal s:
y
injector design and the data bases are helpful to test a
r
p
DNS or to feed numerical codes. S

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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Fiber optic sensor for sprays:
Planar liquid sheet atomisation (ONERA) improvements and performance (A2PS)
1. State of the Art before the FIRST 1. State of the Art before the FIRST
project project
Before the start of the FIRST project there was a lack The technology of fiber optic probe for bubbly flow
of information about the influence of air thickness spray characterisation (liquid concentration, bubble/
and air ambient pressure on a liquid sheet behaviour drop size and velocity) was initially developed in the
and atomization. 90s by an academic lab then transferred in 2007 to
the company A2 Photonic Sensors for improvement,
2. Research & Development industrialisation and commercialisation. Commonly
Activities Performed used in bubbly flows, this sensor was also used in
sprays, but was limited to the analysis of droplets no
ONERA conducted an experiment on liquid
smaller than 15 µm and drop velocities no higher than
sheet atomization with variable air flow around a
25 m/s, and was therefore not fully responding to
liquid sheet and investigated this under pressure.
the requirements of turbomachinery and aeronautic
Different measurement techniques were used to engine injector studies.
characterise the liquid sheet atomization. The use of
optical techniques based on visualisation and image 2. Research & Development
analysis coupled with conventional techniques of fluid Activities Performed
mechanics, hot wire or Pitot allowed information
A2PS has improved its spray analysis fiber optic sensor
obtained to be merged from the gas phase and the
by optimising the sensing element, improving the data
liquid phase to improve knowledge on this phenomena.
analysis algorithm and implementing it with easy-to-
use software. In addition, a large part of the activities
3. Advancement of Capability due to
were dedicated to testing and qualifying the sensor
the FIRST project performance in terms of small drop size detection
The most important results were obtained on the capabilities and maximum velocity reachable, as well
influence of the surrounding air, specifically its thickness as testing the sensor in spray conditions representative
and the characteristics of the resulting boundary of real engine injector study case. 4. Additional information
layer. As expected the role of the boundary layer is
3. Advancement of Capability due to Application: Fuel injector and nozzle of aero
of primary importance on the liquid sheet behaviour.
combustors
the FIRST project
Differences in the flapping frequencies and on the
Research area: Spray and atomization
breakup length linked to the type of air boundary layer, Improvement of the optical probe technique led to a
4. Additional information measurements: drop size & velocity, flux
laminar or turbulent, at the beginning of the liquid measurement system fully functional in unidirectional
Technology readiness level: 7 or 8
sheet were shown. The wall shear stress seemed Application: Fuel injection sprays with droplet sizes down to 10 µm and velocity
Owner of IPR: A2PS
to be an important parameter but not the only one. Research area: Liquid film atomization up to 60 m/s. The capability to measure precise flow
FIRST Task: T3.1.1 & T3.1.3
Technology readiness level: 3 rate and flux was demonstrated even with a very high
To examine the pressure influence on atomization Patent: none
s Owner of IPR: ONERA droplet number per volume (very dense spray). In s
nt study it is necessary to work in a confined environment. Main author and contact: Stéphane Gluck, A2PS nt
e FIRST Task: T3.1.1 addition, a comparison with a PDA system showed e
m In these conditions, the droplet size measurements m
re are difficult and the systems currently used are not Main author and contact: Pierre Berthoumieu, good results agreement and more importantly, a clear re
u ONERA advantage to the optical probe system due to its user- u
s able to give primary droplets sizes due to their non s
a a
e friendliness with its very short installation time and very e
M spherical shape. The pressure effect on final drop size M
al is visible and it improves the atomization process, easy set-up and use. As a result, A2PS are convinced al
t that the optical probe technique will become an t
n but it is difficult to determine where the effect is n
me greater, on primary or on secondary atomization essential instrument for spray analysis in addition to me
ri already existing techniques. ri
e due to the lack of information on primary breakup. e
p p
x x
E E
s: s:
y y
a a
r r
p p
S S
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Combined Break-Up Length and Droplet Size and Experimental investigation of the onset of film
Velocity Distribution Measurements (IMPERIAL) breakup in an annular prefilmer (KIT)
1. State of the Art before the FIRST The break-up length of the liquid sheet was measured 1. State of the Art before the FIRST 3. Advancement of Capability due to
by the LIF technique, and the measurements
project project the FIRST project
were reported for different Reynolds number
Prior to FIRST, ILIDS for the simultaneous Prior to FIRST, experimental investigations of the onset During the FIRST Project a model research nozzle
of water flow for the same air flow rate. Finally,
measurement of droplet size and velocity had only of film breakup in an annular prefilmer were difficult to which produces a homogeneous laminar liquid film
the statistics including the fluctuations of droplet
been performed on automotive fuel injectors. While perform. The reasons were the poor homogeneity in flow was designed and a measurement technique
concentration and its correlation with the droplet
the OC technique for determining the break-up length the circumferential direction of the liquid film flowing to capture the liquid film thickness was developed.
velocity, which are vital for understanding the
had never been applied to pre-filming atomizers. through the annular prefilmer for small liquid mass flow The generated experimental data can be used in
droplet cluster formation, were measured.
rates and incorrect arrangements of laser sheet and order to validate software programs calculating film
2. Research & Development camera position. flows. Furthermore, the experimental facility can be
Activities Performed used for future research work in order to extend the
2. Research & Development
IC was the first to apply the ILIDS and OC techniques experimental data base.
Activities Performed
on a prefilming airblast atomiser, typically found in
aero-engine combustion systems and pioneered The Engler-Bunte-Institute (EBI) of KIT has designed a
the concurrent application of both techniques. model research nozzle which generates homogeneous
Instrumentation and data processing algorithms laminar film flow without any support of air flow and
were developed for the simultaneous collection of developed a measurement technique to determine the
measurements and their interpretation. The spray film thickness and detect the onset of the film breakup.
characteristics of two prefilming atomizers (designed One of the crucial points in detecting the film thickness
at IC and ONERA) were reported. Experiments were was the position of the camera capturing the film at the
performed for different air and water flow test conditions. illuminated surface with a light source.
The simulation and experimental investigation
3. Advancement of Capability due to performed for different positions of the camera have
the FIRST project proved that different positions of the camera gave 4. Additional information
different results for a predefined film thickness at the
ILIDS measurements were reported for different Application: Fuel injector of aero combustors
same boundary conditions. These investigations lead to
axial and radial positions away from the nozzle Research area: Experimental study on primary
the fixing of an arrangement of laser sheet and camera
exit and axis respectively. The increase in SMD of breakup
position which detects a predefined film flow precisely.
droplets towards the spray edge for both atomizers Technology readiness level: 3
Based on this validated arrangement, investigations
was explained on the basis of larger centrifugal force Owner of IPR: KIT
of film breakup were performed with two main
acting on the bigger size droplets due to the swirling FIRST Task: T3.2.3.1
results. The first one concerns the Momentum
flow. The average droplet velocity plots in case of the Main author and contact: Mulubrhan Gebretsadik,
Ratio (MR) between air and liquid flow. In contrast
model atomizer showed the presence of an induced KIT
to existing research on film breakup we found that
vortical flow structure causing flow reversal near nozzle
MR is not sufficient to characterise the beginning of
axis, which arose due to the swirling motion of the
primary atomization. The second one deals with the
air. Away from the nozzle axis, the droplet velocity
s comparison of swirling and not swirling air flow. For s
nt was downward and increased till the droplets lost nt
e 4. Additional information the same air pressure drop the swirling flow generates e
m momentum near the edge of the spray. Apart from m
e a thinner liquid film thickness. e
r the basic velocity statistics, the spatial droplet-droplet Application: Fuel injector for aero combustors r
u u
as velocity correlations (Rdd) and RDF are presented for Research area: Combined Break-Up Length and as
e e
M different droplet size classes. Measurements of Rdd Droplet Size and Velocity Measurements M
al quantified the strength of the intra-phase coupling Technology readiness level: 3 al
t t
en of the droplet flow field in both the axial and radial Owner of IPR: Imperial College London en
m m
directions. The RDF for the different droplet size FIRST Task: T3.2.2
ri ri
pe classes indicated that the larger droplets (45-60 µm) Main author and contact: Yannis Hardalupas, pe
Ex showed greater tendency to form instantaneous Imperial College Ex
s: droplet clusters in the sprays. The average cluster s:
y y
a dimension decreased towards the spray edge. a
r r
p p
S S
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Effect of linear geometrical scaling and
aerodynamic boundary conditions of a double swirl Characterisation of the
airblast atomizer on GSMD (KIT) Pre-filming Inlet Velocity Field (LU)
1. State of the Art before the FIRST 1. State of the Art before the FIRST 3. Advancement of Capability due to
project project the FIRST project
The evaluation of the GSMD for the whole spray is very Modern fuel injectors often incorporate a pre-filmer An aerodynamically representative data set was
difficult because it requires the radial SMD and liquid surface onto which liquid fuel is introduced. Both generated which captures key flow features along the
mass flow distribution. Therefore, the existing data computational and experimental studies were done pre-filmer passage. These include the influence of fuel
base on GSMD for different performance conditions which examine the development of the liquid film and blockage, vane wake stretching and migration, resultant
is very limited. Based on this limited experimental data its subsequent break-up. However, these studies have variations in mean velocity and turbulence adjacent to
base the developed correlations predict the GSMD as invariably utilised simplified geometries which may the pre-filmer and total pressure loss development.
a function of the Weber number (We = (ρ·u2·D)/ρ). not capture the significant aerodynamic flow features The data provides inlet boundary conditions for
present within a representative injector geometry. numerical (CFD) predictions relating to fuel injector
2. Research & Development Such aerodynamic features were thought to be flows. As the data charts the flowfield development
Activities Performed prominent in the development of the two phase flow along the pre-filming passage, it also provide a means
The Engler-Bunte-Institute (EBI) of Karlsruhe Institute of field and therefore should be resolved. of validating the numerical predictions.
technology (KIT) has developed a method to evaluate
2. Research & Development
the GSMD of a spray produced by double swirl airblast
Activities Performed
atomizer by a combination of two measurement
techniques. The radial distribution of the liquid mass flow A large scale representative fuel injector geometry was
is captured by a patternator, whilst the radial distribution designed and manufactured. This facilitated detailed
of the SMD is evaluated from PDA data. A prototype 2-D aerodynamic measurements at multiple planes
and a scaled version of the prototype injector with a within the pre-filming passage. Mean and fluctuating
linear geometric scaling factor of two were investigated measurements were acquired, with and without
at different boundary conditions to determine the fuel present, capturing the development of the
effect of different parameters explicitly on GSMD. aerodynamic flowfield within the pre-filming passage.
3. Advancement of Capability due to
the FIRST project
The combined experimental investigation of patternator
and PDA within the FIRST project has enabled
4. Additional information
the evaluation of the GSMD for the whole spray
Application: Fuel injector of aero combustors
produced by a specific boundary condition in double
Research area: Internal Velocity Field
swirl airblast atomizer. This helps to compare effects
Characterisation
of different parameters on the spray. The combined
Technology readiness level: 2
measurement technique reveals that the impacts of the
Owner of IPR: Rolls-Royce
variables in the We-Number in predicting the GSMD
nts are different. The air velocity, which is calculated FIRST Task: T3.3.2 nts
e Main author and contact: Ashley Barker, e
m from the pressure drop, has much higher impact on m
e 4. Additional information Loughborough University e
r the GSMD than the characteristic length at constant r
u u
as air to fuel ratio (AFR), surface tension and density. Application: Fuel injector of aero combustors as
Me Research area: Experimental study on spray Me
al Technology readiness level: 3 al
t t
n Owner of IPR: KIT n
e e
m FIRST Task: T3.2.3.2 m
eri Main Author and Contact: Mulubrhan Gebretsadik, eri
p p
x KIT x
E E
s: s:
y y
a a
r r
p p
S S
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Time-Resolved Measurements of Fuel Film Thickness Engine Injector Spray Characterisation
on Representative Fuel Injector Geometries (LU) (RRUK, SCITEK)
1. State of the Art before the FIRST 3. Advancement of Capability due to 1. State of the Art before the FIRST
project the FIRST project project
Prior to FIRST, 2-D measurements of fuel film Development of the instrumentation technique within Before the FIRST project there was very little
thickness had been made on an engine representative FIRST enabled refinement of the opto-mechanical information available to describe the properties of
injector at atmospheric conditions. They were setup, culminating in a robust portable system capable atomisation from Rolls-Royce aero engine rich and lean
obtained using a prototype instrumentation assembly of high-speed fuel film thickness measurements. burn fuel injectors. Lefebvre correlations were typically
which successfully demonstrated the capability, but The technique has been demonstrated at ambient used to estimate the fuel spray boundary conditions for
was unrefined and did not temporally resolve the pressure and at 4 Bar, and such measurements CFD modelling of these injectors in combustor flows.
dynamics of liquid structures on the pre-filming surface. will improve the identification and understanding of This coarse method used for numerical modelling
significant factors affecting the development of the made accurate prediction of combustor flow fields, and 3. Advancement of Capability due to
2. Research & Development liquid fuel film and thus the downstream two-phase consequently emissions, difficult. Actual measurements the FIRST project
Activities Performed flow field. As measurements have not previously of the fuel particle sizes and velocities were required The measurements of the spray from the fuel
LU has developed the instrumentation to make it more been available, this data will also facilitate improved before further progress could be made in improving injectors have now provided the boundary conditions
robust, increase portability and enable time-resolved methods for predicting such flow fields. Factors modelling techniques. required for CFD modelling of Rolls-Royce engine
measurements of fuel film thickness. Parametric studies have been identified which will facilitate further combustors and has described the progression of the
2. Research & Development
were completed to better understand the effects of advancement through acquisition of appropriate atomisation process as the flow moves downstream
Activities Performed
dye concentrations, optical filter choice, laser power/ hardware, such as improved temporal resolution away from the fuel injectors. This is vital information
uniformity and substrate surface finish. Software using higher powered lasers. A new test facility was built in the combustion for the improvement of numerical models to predict
development has facilitated rapid processing of the large laboratories in Rolls-Royce Derby that was specifically engine reacting flows. The CFD models can now be
quantities of data associated with such a measurement. designed to enable PDA measurements of fuel sprays validated against the spray measurements for a wide
from engine injectors. All PDA and flow visualisation
range of geometries and conditions and a step change
measurements were performed by SCITEK. Test
in modelling accuracy will be the result. Future
geometries were designed and made that represented
designs of aero engine combustors and fuel injectors
a single sector of an engine combustor so that the
will benefit from the improved modelling accuracy.
spray conditions were more closely representative of
reality. Lean and rich burn fuel injectors were tested at
4. Additional information
a range of conditions relevant to their respective engine
Application: Measurements of engine injector sprays
cycles and detailed measurements of droplet sizes and
for validating CFD modelling
velocities were made at numerous locations. The
Research area: Spray measurements from engine
work was extended to include sprays from alternative
injectors
fuels as a comparison to a standard kerosene spray.
Technology readiness level: 3
Owner of IPR: RRUK
4. Additional information
FIRST Task: Task 3.3.3
Application: Fuel injector of aero combustors Main author and contact: Darren Luff, Rolls-Royce
s s
nt Research area: Liquid film thickness measurements UK nt
e e
m Technology readiness level: 2 m
re Owner of IPR: Rolls-Royce re
u u
s FIRST Task: T3.3.2 s
a a
e e
M Main author and contact: Ashley Barker, M
al Loughborough University al
t t
n n
e e
m m
ri ri
e e
p p
x x
E E
s: s:
y y
a a
r r
p p
S S
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

Development and evaluation of numerical methods
for the simulation of primary atomization in
aeronautical injection systems (CNRS)
1. State of the Art before the FIRST
project
Primary atomization modelling has been an active
research topic over the last two decades with the
development of various numerical techniques for
the tracking of the interface motion (Volume-Of-
Fluid, Level Set) and for the capturing of the jump
conditions at the interface (Continuous Force, Ghost-
Fluid Method). All these techniques have been largely
validated for academic two-phase flows and very few
attempts have been conducted for realistic geometries
such as aeronautical injection systems.
2. Research & Development
Activities Performed
In the FIRST project, CORIA researchers have
developed and applied numerical methods for primary
atomization to realistic injectors. The aim of these
simulations was twofold: i) validate the numerical
strategy in terms of accuracy and robustness, ii) identify
the bottlenecks and the potential improvements.
The simulations of the triple injector, of the ONERA
liquid sheet with swirl and of the Turbomeca injector,
highlighted the need for high mesh resolution at the air/
liquid interface. Such resolution may only be obtained
through manual or automatic local mesh adaptation.
3. Advancement of Capability due to s
n
o
the FIRST project ti
a
During the project, various numerical techniques ur
g
were developed in order to improve the fidelity of fi
n
the simulations and enhance their comparison with o
C
experiments. Two major new capabilities of the c
mi
simulation tools are parallel adaptive mesh refinement 4. Additional information
Sprays: and segmentation techniques for the calculation of de
Application: Liquid fuel injection in aeronautical ca
droplet size distribution. All these capabilities have A
been designed for massively parallel LES with more burners of
Research area: Primary atomization modelling g
than 10,000 cores of modern super-computers. These n
simulations tools are now used by industrial partners in Technology readiness level: 2 elli
Owner of IPR: CORIA - CNRS d
the FIRST project to improve their understanding of o
FIRST Task: T2.2.2 M
Numerical Modelling of
primary atomization. Main author and contact: Vincent Moureau, CNRS- al
c
CORIA ri
e
Academic Configurations m
u
N
s:
y
a
r
p
S
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FIRST Project Summary of Achievements: Advancements in Spray & Soot Research FIRST Project Summary of Achievements: Advancements in Spray & Soot Research

A Multi-Scale Approach For Primary Atomization
Modelling (ONERA) Primary break-up modelling using SPH (KIT)
1. State of the Art before the FIRST 1. State of the Art before the FIRST
project project
Today most advanced LES simulations of aeronautical Before FIRST, reliable predictions of the fuel
combustors are performed with dispersed phase atomisation in aero combustors were not feasible
approaches for the fuel. The numerical droplets are using conventional grid based simulation techniques.
directly injected by fixed numerical injectors whose By introducing the particle based method SPH, such
characteristics are obtained by empirical correlations. simulations including multiple fluids can be performed
These correlations demand an a priori knowledge more easily. Prior to FIRST, the method lacked
of the injector, defeating the purpose of predictive some basic boundary treatment capabilities such as
computations. generalised periodic boundaries and suitable inlet/
Simulation of a sheared planar liquid sheet. Turquoise:
outlet boundary conditions.
resolved liquid core; green: Lagrangian droplets.
2. Research & Development
Activities Performed 2. Research & Development
ONERA has developed a new approach for large-scale Activities Performed
unsteady simulations of primary atomization. It consists KIT has implemented a massively parallel software
of a coupled multi-fluid solver for the simulation of the based on the standard SPH methodology and
liquid core and a dispersed phase approach for the developed robust inlet/outlet boundary conditions and
generated cloud of droplets. This approach has been generic periodic boundaries. Some physical models
tested on different configurations, such as atomization were adjusted in order to handle fluid pairings with
of a sheared planar liquid sheet, film formation and re- high density and momentum ratios correctly. 2D
atomization and a realistic circular swirled injector. and 3D simulations of an academic air-blast atomizer
were performed and results have been validated by
3. Advancement of Capability due to
experiments. Additional software has been developed
the FIRST project for data reduction and visualisation of the results, even
Current industrial numerical simulations of combustion on a standard PC.
chambers cannot resolve the small-scale mechanisms
3. Advancement of Capability due to
of primary atomization. Injection of droplets is done by
ns fixed injection points. The ONERA multi-fluid method the FIRST project ns
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ti is able to reproduce the large scale instabilities of The advancement of the SPH method within FIRST ti
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ur primary atomization such as flapping motion and largest Simulation of droplet impact on a wall and subsequent enabled its applicability to the simulation of air assisted ur
g film re-atomization. 4. Additional information g
fi ligaments formation. The developed atomization atomizers. Detailed simulations, including very fine fi
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o model is able to detect the zone where the droplets spatial resolutions and large data sets are possible Application: Fuel injection in aero combustors o
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c are most likely to appear and to act subsequently as an 4. Additional information due to the low memory requirements of the method Research area: Liquid fuel atomization modelling c
mi advanced numerical injector, transferring the resolved and the highly parallelized code. The simulation Technology readiness level: 3 mi
de liquid to an appropriate distribution of numerical Application: Fuel injector of aero combustors of an academic atomizer at ambient pressure has Owner of IPR: KIT de
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Ac droplets. Taking account of the instabilities of the Research area: LES simulation of combustors injection been performed. The implemented additional post- FIRST Task: T2.2.4.2 Ac
of injection, it gives a more accurate initial position and Technology readiness level: 2 processing software facilitates and speeds up the Main author and contact: Samuel Braun, KIT-ITS of
g Owner of IPR: ONERA g
n velocity of each particle. The model naturally respects analysis of simulation results. The simulations help to n
elli the resolved liquid core and performs the conversion FIRST Task: T2.2.4.1 understand the complex phenomenon of primary elli
d Main Author and Contact: Davide Zuzio, ONERA d
o at realistic break-up lengths. The reciprocal model atomization, which in turn is a prerequisite for the o
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of droplets impact on resolved liquid structures or development of more environmentally friendly
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c wall has been developed as well. Implementation of combustion processes. c
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e the solvers and the model is straightforward in any e
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