projet scientifique - Institut de Combustion Aérothermique Réactivité

PROJET SCIENTIFIQUE
2012 – 2015
INSTITUT DE COMBUSTION, AEROTHERMIQUE,
REACTIVITE & ENVIRONNEMENT
CNRS – INSIS (UPR 3021)
SOMMAIRE
Projet scientifique 2012 - 2015 ........................................................................................................ 1
1. Eléments d’auto-analyse........................................................................................................... 1
2. Projets et objectifs scientifiques ............................................................................................... 3
3. Moyens de mise en œuvre ........................................................................................................ 5
Overview of the Research projects for 2012-2015........................................................................... 7
Thematic Research Group I: Combustion & reactive systems......................................................... 7
1. Research context and objectives............................................................................................... 7
2. Research projects...................................................................................................................... 8
2.1 High pressure combustion of liquid fuels........................................................................... 8
2.2 High pressure combustion of gaseous fuels ....................................................................... 9
2.3 Hydrogen generation by innovative processes ................................................................. 11
2.4 Oxy-fuel combustion of gaseous fuels ............................................................................. 11
Thematic Research Group II: Atmosphere & Environment........................................................... 14
1. Research context and objectives............................................................................................. 14
2. Research projects.................................................................................................................... 14
2.1 Chemical degradation processes of volatile and semi-volatile organic compounds ........ 14
2.2 Heterogeneous Chemistry ................................................................................................ 15
2.3 Chemistry related to the upper troposphere – lower stratosphere (UT-LS) ..................... 17
2.4 Experimental plate-form for atmospheric processes studies and atmospheric trace gas
measurements ......................................................................................................................... 17
2.5 Atmospheric dispersion of pollutants............................................................................... 18
Thematic Research Group III: Space propulsion ........................................................................... 19
1. Research context and objectives............................................................................................. 19
2. Research projects.................................................................................................................... 19
2.1 Electric propulsion ........................................................................................................... 19
2.2 High-speed flow ............................................................................................................... 21
2.3 Chemical propulsion......................................................................................................... 23
Organigramme général ................................................................................................................... 24
Projet scientifique 2012 - 2015
1. Eléments d’auto-analyse
Nous avons déjà présenté les points forts d’ICARE dans la partie bilan de ce document, en nous
appuyant sur des éléments qualitatifs et quantitatifs indéniables. Nous souhaitons insister ici sur le
fait que les opportunités de consolidation et surtout de rattrapage des effectifs perdus d’ICARE ne
manquent pas. Les thématiques de recherche d’ICARE sont au cœur de plusieurs problématiques
socio-économiques et technologiques, dont l’importance et par conséquent les opportunités
d’investissements pour la recherche de solutions innovantes ne peuvent aller qu’en augmentant.
ICARE possède de multiples atouts pour répondre à ces sollicitations.
En effet, le besoin de solutions innovantes aux problèmes de grande ampleur comme l’énergie,
l’environnement ou la propulsion aérospatiale, nécessite souvent de s’inscrire dans des
problématiques et des approches nouvelles très souvent inter et multidisciplinaires. La
composition disciplinaire et les expertises scientifiques et techniques dont disposent aujourd’hui
ICARE, lui permettent d’occuper un rôle de premier plan dans l’espace de recherche français et
européen. ICARE contient en effet en son sein de multiples expertises qui vont de la cinétique à la
dynamique de la combustion et des systèmes réactifs, de la réactivité atmosphérique à la
mécanique des fluides, des écoulements diphasiques à la physique des plasmas. Parmi les points
forts d’ICARE citons donc tout d’abord le potentiel de synergies entre les composantes « énergie,
environnement et propulsion» d’ICARE et entre ses différentes expertises disciplinaires.
Signalons également que les approches expérimentales, la modélisation et la simulation
numérique sont simultanément développées à ICARE. Dans ces dernières années, ICARE a en
effet renforcé ses activités dans le domaine de la modélisation et simulation numérique,
notamment en ce qui concerne les écoulements complexes à grande vitesse.
Il est cependant bien évident qu’ICARE est un laboratoire surtout caractérisé par ses multiples
installations expérimentales, souvent uniques (voir, les fiches descriptives de la Plateforme
Expérimentale d’ICARE, dans l’Annexe 1). Par conséquent, il est d’abord reconnu par la qualité
de ses résultats expérimentaux, grâce notamment aux compétences de son personnel ingénieur et
technicien, qui constitue un groupe de soutien technique à la recherche avec toutes les expertises
requises et complémentaires. Ce potentiel permet à ICARE de diversifier et de renforcer ses
installations en permanence : en témoignent l’évolution récente de PIVOINE vers une nouvelle
génération qui permet aujourd’hui de développer et de tester des propulseurs à plasma de plus
forte puissance pour la propulsion spatiale ; le développement et la mise en service de nouvelles
chambres de combustion à haute pression et d’installations d’accélération de flammes et de tubes
de détonation ; la mise en service prochaine de la soufflerie SAPHYR qui permettra d’étudier des
écoulements supersoniques ionisés et à haute enthalpie ; la chambre de simulation atmosphérique
HELIOS qui augmentera le potentiel des études sur la réactivité atmosphérique, pour ne citer que
ces exemples, sans oublier bien entendu la diversification constante des techniques de mesures
optique et laser et analytiques dont disposent ICARE. L’importance de la présence d’un soutien
technique de qualité est ainsi évidente pour développer et utiliser de telles installations.
Ajoutons que les compétences des services administratifs et financiers d’ICARE ont aussi été
reconnues par les résultats très positifs de l’audit que les services de la Délégation Régionale
Centre Poitou-Charentes a effectué fin 2008.
Les points forts d’ICARE sont donc en nombre importants et réels. Ce qui ne veut pas dire qu’il
ne présente pas (ou ne présentait pas) des points faibles. Les deux premières années, après la
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fusion des UPR 4211 et 9020, ont bien montré que la réussite de la fusion de deux unités avec des
« cultures » de fonctionnement différentes, de types d’installations différents et aussi de nombres
de personnel différents, n’était pas si aisée. La construction d’une cohésion d’ensemble a
nécessité des efforts permanents de la part de l’ensemble du personnel et de la gouvernance.
Les départs massifs à la retraite et quelques départs volontaires se sont aussi fait sentir durement.
Nous pouvons signaler le caractère lourd de cette évolution en précisant qu’entre 2004 et 2011,
ICARE a subi un déficit net de 14 permanents. En effet, entre 2004 et 2011, ICARE comptabilise
29 départs (12 chercheurs et enseignants-chercheurs et 17 ITA) contre 15 recrutements (6
chercheurs et enseignants-chercheurs et 9 ITA), soit un déficit net de 14 personnes, autrement dit
un taux de remplacement des départs de 51,7%. Si on compare la situation future de l’après 1er
janvier 2012 à celle du début de la fusion au 1er janvier 2007, on observe les évolutions suivantes :
au début de la fusion, le personnel permanent d’ICARE était au nombre de 55 (16 chercheurs
CNRS, 14 enseignants-chercheurs et 25 ITA). Au premier janvier 2012, sans recrutement d’ici là,
le nombre du personnel permanent d’ICARE sera de 41 (11 chercheurs CNRS, 13 enseignantschercheurs et I7 ITA). Pour résumer, sur ses 55 permanents au début 2007, ICARE en aura donc
perdu 14 (le quart). Au début 2007, le rapport ITA / (chercheurs+enseignants-chercheurs) était de
0,83. Au 1er janvier 2012, sans recrutement, ce rapport sera de 0,71.
Ces départs massifs à la retraite influent évidemment sur le nombre des HDR d’ICARE. Ce
nombre était 18 début 2007, il sera au mieux de 10 au 1er janvier 2012, avec la soutenance
souhaitée d’au moins 3 HDR. Une conséquence évidente est aussi la réduction du nombre de
doctorants qui passe de 29 au début 2007 (sans compter les co-tutelles) à 20 au 30 juin 2010 (avec
les co-tutelles). Le départ en détachement de Laurent Catoire, depuis le 1er juillet 2010, va aussi
certainement entraîner la réduction d’une partie de nos activités en cinétique chimique et par
conséquent notre potentiel d’encadrement doctoral.
La réduction importante des effectifs d’ICARE, notamment chercheurs et ITA CNRS, et une
certaine difficulté à recruter de nouveaux chercheurs, constituent manifestement la plus grande
faiblesse d’ICARE.
D’un autre côté, il faut admettre que la fin de cette période de réduction « naturelle » des effectifs
d’ICARE est très proche ; autrement dit la vague des départs à la retraite va bientôt s’estomper.
Après les prochains départs à la retraite, l’âge médian des chercheurs CNRS et des enseignantschercheurs sera de 41 ans et celui des ITA de 43 ans. Ainsi, l’âge moyen relativement jeune des
personnels de toutes les catégories devrait être un élément de dynamisme certain et au moins de
stabilité en termes de nombre de personnel permanent. Il est cependant capital d’utiliser
intelligemment les prochains départs à la retraite (il y en aura 2 IT et un professeur d’ici fin 2013)
comme élément de politique de recrutement durable. De même, les bonnes relations avec
l’Université d’Orléans devraient permettre à ICARE de recruter tant du côté CNRS que du côté de
l’Université d’Orléans.
La lecture des projets des 3 Groupes Thématiques d’ICARE montrera la place importante des
sujets de grande ampleur socio-économique et technologique parmi ses axes de recherche
prioritaires. Tout d’abord, la question couplée « énergie-environnement » est au cœur des
expertises et préoccupations d’ICARE, qu’ils s’agissent de la réduction des émissions polluantes
issues de la conversion chimique de l’énergie, des problèmes de sécurité des installations
énergétiques, de l’imagination de nouveaux procédés de combustion pour faciliter le captage du
gaz carbonique, de la caractérisation des performances énergétiques et environnementales des
biocarburants pour la propulsion aérospatiale et automobile ou du développement de procédés
innovants pour la production d’hydrogène. Les projets d’ICARE sont au cœur des agendas des
gouvernances nationale, européenne et internationale et constituent donc pour ICARE des
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opportunités indéniables. Celles-ci seront d’autant mieux transformées en contributions
exceptionnelles à la question « énergie-environnement » si les synergies entre les expertises
d’ICARE en cinétique et dynamique de la combustion et des systèmes réactifs sont renforcées.
Parmi les opportunités dans ce domaine, citons aussi les bonnes relations de collaboration
d’ICARE avec les laboratoires orléanais voisins et experts dans les sciences des matériaux, ce qui
permet de développer des approches très complètes en intégrant les contraintes imposées aux
matériaux par les nouvelles technologies de l’énergie, comme par exemple celles de la corrosion
dans les procédés de conversion hydrothermale de la matière organique.
Ces opportunités évidentes liées à l’importance de la question « énergie-environnement » sont
renforcées par le développement continuel du potentiel de recherche d’ICARE dans le domaine de
la réactivité atmosphérique et de la qualité de l’air. Les études sur la réactivité atmosphérique
profiteront de plusieurs opportunités tant internes qu’externes : le développement d’une
installation exceptionnelle comme HELIOS et le développement des études de dispersion
atmosphérique en bénéficiant des expertises en dynamique des écoulements d’ICARE sont des
opportunités internes évidentes. La montée en force de l’Observatoire des Sciences de l’Univers
du Centre, les bonnes relations de collaboration d’ICARE avec les autres partenaires de l’OSUC
et enfin les collaborations internationales soutenues d’ICARE avec ses partenaires européens,
mais aussi plus récemment avec des partenaires chinois, sont autant d’opportunités externes. La
transformation de ces opportunités en contributions exceptionnelles dans ce domaine nécessite
cependant le renforcement du potentiel technique d’ICARE pour opérer et gérer efficacement sa
plateforme expérimentale comportant plusieurs chambres de simulation atmosphérique et une
instrumentation sophistiquée.
La propulsion spatiale pour les applications civiles et pour la défense est un autre domaine de
forte expertise d’ICARE. Les recherches de solutions et de technologies innovantes pour la
propulsion et le maintien en orbite des satellites de télécommunications, pour les lanceurs
réutilisables, pour les ergols er propergols plus respectueux de l’environnement, pour la sécurité
des engins spatiaux lors des rentrées atmosphériques, pour l’augmentation des performances des
missiles sont autant d’opportunités pour l’utilisation des expertises et des installations
exceptionnelles d’ICARE. Il est cependant évident que ces opportunités seront d’autant mieux
transformées en contributions durables si le potentiel en personnel chercheur et ingénieur du
Groupe Thématique Propulsion Spatiale est significativement renforcé.
2. Projets et objectifs scientifiques
Le projet scientifique d’ICARE pour la période 2012-2015, voire au-delà, s’appuie bien entendu
solidement sur ses expertises développées depuis de longues années et aussi sur la consolidation
de sa structuration scientifique pendant la période en cours. Comme expliqué dans le document
portant sur le bilan, ICARE ne pouvait pas ne pas se restructurer suite à la réduction drastique de
ses effectifs concernant toute les catégories de son personnel. Ces restructurations et
consolidations ont été résumées dans le bilan de l’Unité ; elles concernent tout autant la réduction
du périmètre de ses activités que la réorganisation de ses thématiques et équipes. La structure
scientifique à laquelle ICARE a abouti à la suite de ses efforts de consolidation se décline en 4
thématiques, que nous rappelons ici :
* Cinétique chimique de la combustion et des systèmes réactifs
* Dynamique de la combustion et des systèmes réactifs
* Propulsion spatiale et écoulements à grande vitesse
* Réactivité atmosphérique
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Durant les deux dernières années, il est devenu clair que la distinction entre les thématiques
Cinétique et Dynamique de la combustion et des systèmes réactifs était difficile à soutenir ; en
effet les équipes « cinéticiennes » et « dynamiciennes » d’ICARE travaillent de plus en plus
ensemble dans des projets communs faisant intervenir ces deux expertises d’ICARE. Pour la
période future, il est donc proposé de réunir ces deux thématiques. Ainsi, les activités de
recherche d’ICARE se développeront à travers ses 3 groupes thématiques, qui sont :
* Combustion
* Atmosphère et Environnement
* Propulsion spatiale
Comme le montre, l’organigramme fonctionnel cible ci-joint, une plateforme expérimentale
spécifique d’ICARE vient appuyer chacun de ses groupes thématiques.
Les projets des groupes thématiques sont présentés en détail dans ce document (également en
anglais comme le bilan des résultats scientifiques). Faisons ici quelques remarques générales
préalables.
Rappelons à nouveau que cette structure scientifique épouse parfaitement les contours des
missions de l’UPR3021 qui sont ainsi énoncées :
« Développer les domaines de la combustion et la détonation, la propulsion aérospatiale et
automobile, la réactivité atmosphérique, les nouvelles ressources et matériaux pour
l’énergétique »
Rappelons également que cette consolidation avancée de la structuration des activités de
recherche d’ICARE est aussi en phase avec la politique scientifique de l’Université d’Orléans,
notamment avec le regroupement d’une partie de ses laboratoires dans un institut « Energies et
Matériaux », ainsi qu’avec les projets prioritaires que nous mettrons en place dans le cadre de la
Fédération de Recherche EPEE, en collaboration avec le GREMI et l’Institut PRISME.
Comme il apparaîtra clairement de la lecture de ses projets, le Groupe Thématique Combustion
s’intéresse en fait à plusieurs sous-domaines de la conversion chimique de l’énergie et de ses
conséquences environnementales : les phénomènes de combustion, d’explosions ou de
détonations et de gazéification ou de vaporisation, avec aussi un fort intérêt sur les aspects liés à la
sécurité de ces systèmes. Ce groupe est par conséquent plus important en nombre par rapport aux
autres groupes. Cependant deux collègues professeurs de ce groupe partiront à la retraite en 2012
et ce groupe contient 7 autres enseignants-chercheurs qui ont de très fortes activités liées à
l’enseignement, ce qui pondère donc l’effet de masse apparent. Par ailleurs, plusieurs chercheurs
de ce groupe interviendront aussi de plus en plus dans les actions de recherche des deux autres
groupes thématiques, comme le montre la lecture des projets des Groupes Thématiques.
Le groupe thématique Propulsion spatiale a fortement réduit le périmètre de ses activités et s’est
focalisé sur ses domaines d’excellence, comme le montre aussi son nouvel intitulé. Par ailleurs,
deux ingénieurs de recherche font partie intégrante de ce groupe thématique. ICARE est aussi
décidé à mettre une forte priorité pour augmenter les effectifs de ce groupe ; c’est déjà le cas dans
les demandes de ressources pour 2011.
Le groupe thématique Atmosphère & Environnement continuera à renforcer sa présence nationale
et européenne, notamment par la mise en service d’ici fin 2011 de la nouvelle chambre de
simulation atmosphérique à irradiation naturelle, HELIOS, pour la réalisation de laquelle ICARE
s’est beaucoup investi et a mobilisé des ressources financières et humaines très conséquentes. Le
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renforcement du potentiel technique de ce groupe thématique est l’une des priorités immédiates
d’ICARE. La modification de l’intitulé de ce groupe thématique indique aussi la volonté
d’ICARE de mettre en place des projets entre ses expertises sur la réactivité atmosphérique et
celles sur la combustion et la dynamique des fluides. Le récent projet sur la dispersion
atmosphérique des polluants émis suite à des accidents chimiques, témoigne de cette volonté.
3. Moyens de mise en œuvre
Ce paragraphe contient quelques commentaires sur les moyens de mise en œuvre du projet
d’ICARE. Le bilan de la période passée a démontré qu’ICARE a toujours su mobiliser les moyens
financiers nécessaires pour ses projets. Par contre, il paraît évident que les forces humaines
d’ICARE doivent être renforcées pour être parfaitement en adéquation avec ses projets. A moyen
terme, chacune des 3 plateformes expérimentales d’ICARE doivent être renforcées par un IR/IE.
Les besoins concernent plus spécifiquement, la gestion des installations de haute pression de la
plateforme Combustion, la gestion des chambres de simulation atmosphérique de la plateforme
Atmosphère & Environnement et la gestion du moyen national d’essais PIVOINE. Du point de
vue des chercheurs, les domaines concernant la propulsion électrique, la combustion turbulente et
les accélérations de flammes, ainsi que les écoulements à haute vitesse doivent être renforcés.
Ces priorités de recrutement découlent des réflexions partagées émanant du Conseil Scientifique
de l’Unité. Le rôle de ce conseil sera renforcé dans la prochaine période. Le directeur entouré des
responsables des 3 groupes thématiques pourrait constituer son bureau exécutif. De même, le rôle
de la cellule de coordination des services techniques sera renforcé. Un groupe de pilotage
constitué des chargés de mission actuels de cette cellule et des responsables des 3 plateformes
expérimentales d’ICARE pourraient s’organiser pour mettre en place une gestion plus efficace de
la prévision de la charge de travail des divers services communs, en introduisant un mode de
gestion par projet. Une nouvelle instance d’aide à la gouvernance sera aussi mise en place pour
créer un milieu d’échange entre la Direction de l’unité et ses différents correspondants (pour la
communication, formation permanente), l’ACMO, et le responsable du pôle administratif.
L’année 2011 sera mise à profit pour mettre en place cette instance et revoir les missions et les
modes de fonctionnement de celles existantes (CS et cellule de coordination technique).
La politique des séminaires interne d’ICARE sera poursuivie ; ils sont en effet un excellent moyen
pour accroître la communication scientifique entre les différentes expertises d’ICARE et susciter
des idées et projets entre elles.
Le bilan des activités de la période en cours et les projets de la période future montrent qu’ICARE
est impliqué dans des actions partenariales multiples. Ces actions partenariales sont bien réparties
entres les 3 groupes thématiques ; les ressources propres du laboratoire permettent aussi de mettre
en place un fonds pour financer des actions d’intérêt commun mais pas vraiment des recherches
prospectives qui n’ont pas encore de ressources propres récurrentes. Un effort sera fait dans ce
sens et ce sera l’une des nouvelles missions du Conseil Scientifique renforcé de décider des
modalités de la mise en œuvre de cette politique. Le CS proposera aussi des actions pour
augmenter la participation des différentes expertises d’ICARE à des programmes européens. En
effet, contrairement à une excellente participation à des projets ANR ou régionaux et à des actions
contractuelles directes avec des partenaires industriels ou les agences nationales, la participation
d’ICARE aux programmes européens pourrait être améliorée.
De même, l’implication d’ICARE dans des projets soutenus par des Pôles de compétitivité
pourrait être améliorée. Une difficulté inhérente à cette situation est l’absence de grands pôles de
compétitivité en Région Centre dans les domaines d’excellence d’ICARE. Une politique de
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concertation avec les Pôles de compétitivité des régions voisines et aussi avec les laboratoires de
recherche de ces mêmes régions sera mise en place. Il s’agit notamment des Régions d’Ile de
France, de la Haute Normandie et de Poitou-Charentes.
Comme c’est le cas aujourd’hui, ICARE continuera à s’impliquer fortement dans des actions de
diffusion de l’information scientifique et technique par ses différentes interventions publiques,
participation aux journées portes-ouvertes et accueil de stagiaires de divers niveaux
Les paragraphes suivants présentent en détail les principaux projets des trois Groupes
Thématiques d’ICARE.
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Overview of the Research projects for 2012-2015
Thematic Research Group I: Combustion & reactive systems
1. Research context and objectives
Combustion studies constitute one of the principal expertise areas of ICARE. During its long
history, dating back to its Parisian period at La Sorbonne first and later at the Université Pierre et
Marie Curie (Paris VI), chemical kinetics of combustion was initially the dominating expertise
area developed at ICARE. Progressively, starting in early 1980’ies, dynamics of combustion
studies started to emerge. For long years however, these two research paths did not really cross
each other. A new pattern is observed since late 1990’ies. First, chemical kinetics groups initiated
studies integrating dynamic aspects of combustion, such as criteria for flame acceleration due to
obstacles or determining laminar propagation velocities to validate kinetic mechanisms. More
recently, those involved in combustion dynamics also started to integrate chemical kinetics
considerations, for example in metal particle combustion studies, high pressure flame dynamics
enriched by hydrogen or diluted by CO2 or in oxygen enriched air or in biomass gasification
studies. Still, however, during the past 4 years, the thematic groups of combustion chemical
kinetics and combustion dynamics existed separately, albeit cooperating strongly. In the coming
period, the full integration of the chemical kinetics and flow and flame dynamics approaches to
combustion studies is aimed. This objective is all the more timely and necessary that energetic and
pollution aspects of combustion studies are now totally connected. The best example of this
extreme trend is certainly the absolute necessity of mitigating CO2 emissions from combustion,
whereas maximum CO2 generation was, not before long, the only indicator of good combustion.
This trend is obviously much better expressed by the “zero emission” concept which of course
includes all the harmful emissions from combustion.
The considerable expertise present at ICARE in combustion studies with its exceptional facilities
(also grouped in this new area into one integrated experimental platform of combustion and
reactive systems facilities together with their associated diagnostics) will be devoted to solving
this dilemma by following three main research directions.
* One direction will consist in focusing on new fuels, both liquid and gaseous, not directly
originating from fossil hydrocarbons, but either on reformulated and synthetic ones and those
directly issuing from bio-resources by anaerobic digestion or by gasification (also of coal). The
combustion and emission performances of these fuels will be investigated. For all these new fuels,
but especially for those involving hydrogen, flame acceleration and detonation criteria will also be
investigated.
* A second direction will concentrate on oxygen enriched combustion of gaseous (natural gas)
and solid fuels (coal). As above, both chemical kinetics and flow and flame dynamics aspects will
be explored. In addition, the potential role of magnetic forces in aiding the various segments of
oxy-fuel burning processes will be explored.
* Finally, a third direction will explore innovative paths for hydrogen generation based on
chemical conversion of various resources, such as low temperature oxidation of aluminum
particles and hydrothermal gasification of organic resources (biomass and organic waste).
The general features of the projects along these directions are developed below. Obviously, we
insist here on those orientations in line with the new challenges for the energy and environment
interactions. When necessary, more conventional research actions will be performed capitalizing
on the expertise of ICARE on several combustion problems in the continuation of those developed
in the past years.
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2. Research projects
2.1 High pressure combustion of liquid fuels
These studies will first concentrate on the chemical kinetics of heavy hydrocarbons, first and
second generation biofuels and reformulated or synthetic liquid fuels. They will combine
experimental studies (in jet-stirred reactors, shock tubes with spray injection) and chemical kinetic
modeling. New optical diagnostics will be implemented (especially CRDS) to enrich those
already used at ICARE. Chemical kinetic studies will be complemented by mainly experimental
studies on the structure and dynamics of laminar and turbulent flames of liquid fuels in
prevaporized, partially prevaporized and fully two-phase conditions.
2.1.1 Chemical kinetics of oxygenated biofuels
(P. DAGAUT, G. DAYMA, N. CHAUMEIX)
Experimental and kinetic modeling studies concerning oxygenated compounds (esters, alcohols,
ethers), either as fuel or as additives will be performed in the frame of existing collaborations
especially with IFP (on the combustion of ethanol in Diesel engines) and with TOTAL In addition
to mechanistic studies, auto-ignition delay times and laminar flame velocities for different initial
conditions in terms of pressure, temperature and equivalence ratios of different compounds
relevant to either gasoline or diesel fuels will be determined. Collaborations with the University of
Galway on the acquisition of fundamental data regarding the combustion of ketones and with MIT
on the validation of automatically generated kinetic mechanisms of methylformate oxidation will
be pursued.
2.1.2 Oxidation kinetics of reformulated kerosene
(P. DAGAUT, G. DAYMA)
The kinetics of oxidation of reformulated kerosene was studied in the frame of the ‘CALIN’
project funded by the Ministry of Industry and the Pôle de Compétitivité Aerospace Valley
involving collaborations with Airbus, CERFACS, IFP, INSA-Toulouse, ONERA, SNECMA.
Further investigations are currently performed on this topic through the FP7 project ‘Alfabird’
(2009-2012). We are currently preparing an extension to the CALIN project to be submitted in
2010. Ongoing collaborations with the Universities of Toronto and Texas A&M will continue.
2.1.3 Chemical kinetics of fuel oxidation under HCCI conditions
(P. DAGAUT, G. DAYMA, L. PILLIER, S. de PERSIS, N. CHAUMEIX, S. ABID)
There are still many uncertainties associated with the chemical kinetics of fuel oxidation under
HCCI combustion conditions where massive EGR rates are used. The interactions between burnt
gases and fuel ignition and combustion are complex and need further studies. We will focus on a
better understanding of the kinetics of HO2 and H2O2 reactions. A new experimental setup will be
developed and used to measure HO2 by CRDS in a JSR to provide constraining data for the
kinetic modeling. Additional studies will concern the better understanding of the combustion of
cetane improvers added to induce a decrease of the auto-ignition delay of a diesel fuel and to
induce faster combustion of the mixture in the engine chamber. This will be achieved by
constructing a new chemical kinetic mechanism based on data obtained using high pressure shock
tubes (auto-ignition delay times, major decomposition products).
8
2.1.4 Structure and dynamics of liquid fuel flames
(C. CHAUVEAU, I. GOKALP, L. PILLIER, N. CHAUMEIX)
These studies will concern the structure and dynamics of laminar and turbulent liquid fuel flames.
Several complementary facilities will be used (laminar opposed jet flames, spherical combustion
chambers, facilities for the study of the vaporization and burning of single and interacting droplets
and droplet clouds). All these facilities allow high pressure studies and the use of optical
diagnostics, and reproduce conditions relevant for various liquid fuel combustion regimes.
For fully pre-vaporized combustion regimes, the high pressure laminar burner facilities of ICARE
will be adapted to allow the vaporization of liquid fuels, the kinetics of which are studied in
parallel. Laser diagnostics such as LIF, Raman, CRDS, and Rayleigh scattering will be used to
study the flame structures and dynamics. Studies on the laminar flame propagation of spherical
expanding flames will be pursued in collaboration with TOTAL. Since the spherical chamber
facility can be heated up to 250°C, liquid fuels can be vaporized and mixed with air before their
ignition. A first project concerns the peculiar fuels of F1 racing cars, as it is fundamental to have
better criteria to adjust the "right fuel" for a given engine. For this purpose, laminar flame velocity
does not constitute a sufficient global criterion for fuel ranking, and the behavior of the flame
regarding the instabilities characterized by the Markstein length is an important feature. A
systematic study will be carried out in order to obtain the fundamental properties of these fuels
such as the laminar flame velocity, Markstein length and the maximum pressure rise rate.
For partially vaporized combustion regimes, the expertise of ICARE on single and interacting
droplet vaporization and burning will be extended to study flame propagation in a heterogeneous
medium, in particular a liquid fuel (ethanol) dispersed in an aerosol form. This requires full
characterization of the aerosols produced in the combustion apparatus, which will be performed
using a laser diffraction particle sizing system. The use of the parabolic flights, in order to reduce
gravitational acceleration, will make it possible to study the flame propagation in homogeneous
two-phase mixtures. Results of this experimental study, supported by the CNRS/CNES GDR
Microgravity, will be confronted with the numerical results obtained in collaboration with the
laboratory M2P2, University of Marseille.
2.2 High pressure combustion of gaseous fuels
These studies will concern both the chemical kinetics of oxidation and pollutant formation,
laminar and turbulent flame structure and dynamics, flammability limits, flame acceleration and
detonation criteria of various mixtures containing hydrogen, biogas and syngas and other gaseous
species such as methane, H2O or CO2. The effects of reactive mixture composition, initial
pressure and temperature and the presence of water droplets or metallic particles will be
investigated to determine relevant basic parameters for flame propagation, heat release rate and
safety analysis and modeling.
2.2.1 Chemical kinetic reaction mechanisms for the combustion of natural gas
(P. DAGAUT, G. DAYMA, S. JAVOY, L. PILLIER, S. de PERSIS)
ICARE participates to the on-going international effort to validate a chemical kinetic reaction
mechanism for the combustion of natural gas. PrIMe—Process Informatics Model— is a new
approach to develop such models through international collaboration using cyber-infrastructures.
In this context, a shock-tube technique coupled with Atomic Resonance Absorption
Spectrophotometry (ARAS) will be used to better assess the rate constants of elementary chemical
reactions involving O or H atoms, especially those of HCN and CH2O kinetics which remain to be
refined. In addition, the ANR project “NO-mecha”, aiming at revisiting the NOx formation
mechanisms in low pressure (PC2A, Lille) and high pressure (ICARE) natural gas flames, will be
continued.
9
2.2.2 Structure and dynamics of laminar and turbulent gaseous fuel flames
(C. CHAUVEAU, L. PILLIER, N. CHAUMEIX, I. GOKALP)
This research axis will concern the structure and dynamics of premixed laminar and turbulent
flames, especially of natural gas substitutes such as biogas, syngas or hydrogen enriched natural
gas. Complementary high pressure burners and combustion chambers together with various laser
diagnostics will be used. High pressure syngas/air and biogas/air laminar premixed flames will be
studied in opposed flame configuration using optical diagnostics such as Raman scattering for
temperature and major species measurements and CRDS for absolute concentration measurements
of minor species in flames. Spherical combustion chambers will be used to complement these
studies in terms of flammability limits, Marsktein lengths and Zeldovich numbers as well as
maximum explosion pressure rise rate. Such fundamental data are necessary not only as input for
combustion modeling but also explosion safety analysis purposes. In addition, the same facility
will be used to determine both the ignition energies and flammability limits of low calorific gases
such as biogas and their laminar propagation properties. Laser ignition techniques will be
compared to spark ignition in cooperation with the company CILAS in the continuation of the
ongoing joint projects.
Laminar flames stabilized on Bunsen burners for the same mixtures will also be used under high
pressures and coupled to laser induced Rayleigh scattering technique, making it possible to
determine the evolution of the flame thickness according to the pressure. Concerning turbulent
flame studies, the development of the biplanar Rayleigh scattering diagnostic will be continued.
This technique will allow the determination of the internal structure of the instantaneous flames,
in particular regarding the 3D effects. Parametric studies in terms of pressure, reactive mixture
composition and equivalence ratio will be performed for biogas/air and syngas/air flames. Main
parameters for validating premixed turbulent combustion models such as flame surface density
will be obtained for these new fuels under various conditions.
2.2.3 Flame acceleration and transition to detonation
(N. CHAUMEIX, G. DUPRE, S. ABID)
The work conducted at ICARE on flame acceleration phenomenon will be pursued through
collaborations both at a national level (IRSN, INERIS, CEA) and European programs in FP7
Severe Accident Research Network of Excellence (SARNET-2) and FP7 Euratom project
Advanced High-Temperature Reactors for Cogeneration of Heat and Electricity R&D
(ARCHER).
The further understanding of this transition from slow flames to fast flames will be improved by
measuring key parameters such as the velocity of the fresh gases ahead of the flame during its
propagation, the level of turbulence induced by the flame itself or by the presence of obstacles. To
do so, a new high speed PIV system has been acquired and will be coupled with the ENACCEF
facility of ICARE. These studies will target H2/O2/Air mixtures and H2/Air mixtures either
containing solid particles such as metallic or graphite particles (for ITER-safety analysis) or water
droplets (for Pressurized Water Reactor safety analysis). Moreover, the flammability limits of
hydrogen mixtures containing a variety of gases (He-CO-CO2-H2O-CH4) and water droplets will
be determined over a wide temperature range (20-250°C) and pressures (1-10 bars), and droplet
concentrations and sizes.
Detonation studies of these mixtures aiming at the determination of their dynamic parameters
(detonation cell size, detonation speed, overpressure) will also be pursued emphasizing on the
chemical kinetics mechanisms involved within the detonation wave through studies using the
classical shock tube technique (auto-ignition delay times and species profiles behind reflected
shock waves).
10
2.3 Hydrogen generation by innovative processes
Hydrogen could be an important emission free energy vector if its production from non-fossil
sources is mastered. Two approaches will be continued at ICARE to contribute to this
development.
2.3.1 Biomass gasification in supercritical water
(C. CHAUVEAU, I. GOKALP)
Biomass is an important resource for CO2 neutral energy generation. One approach for biomass
conversion is its gasification. Auto-thermal gasification processes are not suitable for wet organic
materials (humid biomass or organic waste). The so called allo-thermal processes, with the
addition of external energy to aid gasification, are envisaged in some cases. Gasification of wet
biomass or organic waste in supercritical water is one of the innovative processes investigated at
ICARE, with the support of ANR, Region Centre and CPER, for syngas or hydrogen generation.
As this process also has important technological issues to be solved concerning materials sciences
(corrosion issues especially), fruitful collaborations with neighboring laboratories such as
CEMHTI and CRMD are established. Very detailed basic studies on the hydrothermal conversion
of wet organic materials into gaseous components, and especially hydrogen, will be conducted
using the hydrothermal diamond anvil cell facility as well as batch and continuous flow pilot
reactors.
2.3.2 Low temperature oxidation of Aluminum particles in water
(C. CHAUVEAU, I. GOKALP)
Hydrogen production on demand is an important issue to minimize the problems associated with
the development of hydrogen technologies especially for hydrogen transport and storage
segments. Some lightweight metametals or their hydrides can produce hydrogen through reactions
with water. For example, the theoretical hydrogen production rate is 1.244 l of hydrogen for 1 g of
aluminum with bayerite/boehmite formation. Compared to other systems, aluminum has favorable
features, such as cost-effectiveness, non-reactivity at normal conditions, easy storability, safety
during transportation, and non-toxicity. In order to enhance the reactivity of aluminum particles in
water at low temperatures, two approaches will be explored, first by investigating the reactivity of
nanosize aluminium particles and, second, by aluminum activation processes, which requires the
use of metal-alloys as activator (gallium-indium eutectics). The expertise of ICARE on metal
particles combustion, and especially aluminum, will play a crucial role in this new orientation.
2.4 Oxy-fuel combustion of gaseous fuels
Combustion in pure oxygen or oxygen enriched air is one of the foreseen approaches to ease CO2
capture from fossil fuel burning large scale facilities (thermal power plants, steel, cement or glass
industries). The idea is to increase the concentration of CO2 in flue gases to facilitate its capture
by membrane technologies which are less energy demanding compared to solvent absorption postcombustion carbon capture technologies. Several aspects of oxy-fuel combustion processes will
be investigated. The membrane capture aspect will be conducted in cooperation with LRGP in
Nancy.
2.4.1 Chemical kinetics of oxygen enriched air combustion of methane and natural gas
(L. PILLIER, S. de PERSIS, P. DAGAUT, G. DAYMA, S. JAVOY)
The chemical kinetics of natural gas combustion in oxygen enriched air will be modeled in order
11
to predict the flue gas composition versus the oxygen enrichment rate. In particular, the impact of
oxygen enrichment on the heat release rate and pollutant emissions will be investigated. One
important issue is the determination of NOx and SOx concentrations which can be determinant for
the CO2 capture technology using membranes. Combustion simulation software packages such as
OPPDIF/CHEMKIN or CANTERA will be used. They allow integrating large detailed chemical
kinetic mechanisms in the modelling of laminar opposed diffusion flames. To determine missing
rate constants under oxy-fuel combustion conditions, Resonance Absorption Spectroscopy will be
used at high temperature (1200-2800K) and high pressure (1-10 bars) to assess the rate constants
of elementary reactions important in the oxygen enriched air combustion of methane and natural
gas. Molecular Resonance Absorption Spectrometry (MRAS) will be developed to record
simultaneously H or O-atom and CO-molecule concentration profiles. Finally, soot formation in
typical oxyfuel - CO2 atmospheres, and the possible chemical effects of high CO2 levels on the
oxidation process of various fuels will be investigated, in cooperation with Saragossa University
within the frame of the COST CM0901 “Detailed chemical kinetic models for cleaner
combustion” (2010-2014).
2.4.2 Laminar and turbulent premixed and non premixed flames in oxygen enriched air
(I. GOKALP, C. CHAUVEAU, P. GILLON, L. PILLIER, B. SARH, T. BOUSHAKI,
V. GILARD, J-N. BLANCHARD)
A new ANR project will start in early 2011 on the characterization of the flame and emission
characteristics of premixed and non-premixed, methane – oxygen enriched air mixtures. The
experimental study will be conducted in the laminar and turbulent combustion chambers of
ICARE. The study mainly relates to the flue gas characterization for various oxygen enrichment
rates. To this end, an automatic uninterrupted gas analysis system will be acquired. It will allow
the analysis of the composition of gas emissions on the ICARE experimental facilities but also on
the demonstrator that will be developed during the project in cooperation with project partners.
This system will make it possible to analyze gases such as CO, CO2, NO (NOx), SO2, O2, by
implementing analysis techniques such as infra-red spectroscopy, galvanic or paramagnetic
probes (for oxygen) and chemiluminescence (for NO, NOx). The dynamic and thermal structure
of the turbulent diffusion flame of methane and oxygen enriched air flames will also be
experimentally characterized and modeled.
2.4.3 Magnetic forces enhanced separation and aggregation techniques for oxygen enrichment and
particulates mitigation
(P. GILLON, B. IZRAR)
To separate any mixture one has to find a factor by which its components differ and which will
lead to an effective separation. Paramagnetic and diamagnetic gases experience a counter
magnetic force in a magnetic field gradient. Studies of the effect of magnetic field on flames and
gas flow are already developed at ICARE. Paramagnetic oxygen has relatively high and positive
volume susceptibility. Diamagnetic nitrogen has relatively low and negative volume
susceptibility. This shows a possibility of oxygen enrichment from atmospheric air by use of a
strong magnetic field gradient. However, the magnetic force acting on oxygen molecules is very
small, and the gas turbulence and the molecular diffusion may easily lead to the remixing of
oxygen and nitrogen. Feasibility in different configurations of gas flow and of the magnetic field
gradient will be carried out and the process will be qualified in terms of efficiency and flow
characteristics.
Inhalable particulate matter generated by combustion is a serious environmental concern. Due to
their small size and light weight, conventional removal facilities from flue gases are less effective
on very fine particles. We propose to investigate the effects of a magnetic field on a flow
containing combustion emitted particles of different nature. Enhanced separation or concentration
12
of fine particles in a part of the flow combined to possible aggregation could be a solution to the
removal of fine particles from the flues gases of combustion processes. The control of a particle
trajectory will result from competing forces acting on it. They include hydrodynamic drag forces,
magnetic and gravitational forces and a diffusive force from the intrinsic Brownian motion. An
important role will be played by the inter-particles forces such as Helmhotz double layer
interaction, dipole-dipole interaction, Van der Waals attraction as well as diffusion, double layer
interaction and drag force.
13
Thematic Research Group II: Atmosphere & Environment
(A. MELLOUKI, V. DAELE, Y. BEDJANIAN, G. LE BRAS)
1. Research context and objectives
A sound scientific understanding of the factors affecting the environment is essential to guarantee
the sustainable development of the world’s economic and societal activities. Many environmental
issues such as air quality and climate change are intimately linked to atmospheric chemistry and
physics and research in these areas is therefore of tremendous importance. Both, anthropogenic
and biogenic emissions contribute greatly to the chemical composition of the atmosphere. Even
though the atmosphere is a self-cleaning system through its photochemically driven reactions, the
hazardous direct impacts of primary and secondary pollutants on human health, and ecosystems,
are observable and have been evidenced on different scales from local to global (e.g. ozone hole,
climate change, air quality …). The chemical processing of the species present in the atmosphere
is one of the most important players in driving the evolution of the atmosphere.
Despite a large number of studies over the past decades, which have improved our understanding,
many processes fundamental to atmospheric chemistry are still poorly understood or need to be
described in greater detail, in order to furnish a scientifically sound basis for the forging of better
assessment tools in terms of chemical and physico-chemical process modules which can be
included in numerical models of our atmospheric environment. The Atmospheric Reactivity
Group of ICARE has been involved for a number years in the field of the atmospheric chemical
processes studies, both in the gas and heterogeneous phases. Over the years, the group has
contributed to different national and international programmesprograms as described in the report
for the last four years.
Among the topics that will be further studied within the group in the following years, emphasis
will be put on (i) Chemical degradation processes of volatile and semi-volatile organic
compounds (ii) Heterogeneous Chemistry, (iii) Chemistry related to the upper troposphere – lower
stratosphere, (iv) Experimental plate-form for atmospheric processes studies and atmospheric
trace gas measurements, and (v) Atmospheric dispersion of pollutants in cooperation with the
Thematic Research Group on Combustion & Reactive Systems.
2. Research projects
2.1 Chemical degradation processes of volatile and semi-volatile organic compounds
The degradation of volatile and semi-volatile organic compounds (VOCs and sVOCs) in the
troposphere leads to the production of a range of secondary pollutants such as ozone, peroxyacyl
nitrates, and secondary organic aerosols. VOCs and sVOCs are emitted directly into the
atmosphere from biogenic sources and from solvent and fuel additives use, and are also formed in
the tropospheric oxidation of all hydrocarbons. They play an important role in determining the
oxidizing capacity of the troposphere both on a regional and a global scale. A considerable body
of experimental data on the gas-phase oxidation of these compounds has been reported. However,
further understanding of some chemical processes is required such as degradation pathways for
loss of higher molecular weight and polyfunctional species which have not been well
characterized. Other needs are linked to the atmospheric chemistry of unsaturated VOCs.
Vegetation produces large quantities of hydrocarbons and other volatile organic compounds that
dominate global gas emissions. Alkenes are the major class of VOCs emitted from vegetation, and
are also emitted from anthropogenic sources, including vehicle exhaust and solvent industries.
14
Isoprene is the largest component of emissions from vegetation. Current models suggest that
isoprene emissions in unpolluted environments can overwhelm the ability of atmospheric oxidants
to remove ‘greenhouse’ and toxic gases by depleting the level of oxidants while in a polluted
atmosphere, isoprene emissions can substantially increase the amount of smog. Recent field work
has suggested that the impact of isoprene on the oxidants budget is less important than thought.
Hence, it has been suggested that a promising approach for developing global mapping of
isoprene is to make satellite observations of its oxidation products, but this requires an accurate
understanding of its oxidation processes and to characterize the reactions products.
Within national (e.g. CNRS-INSU, Primequal …) and European projects (e.g. Eurochamp 2), the
atmospheric chemistry of unsaturated VOCs will be studied. In particular, experiments that focus
on exploring the effects of the level of the NOx concentrations will be conducted for isoprene and
other terpenes. In fact, the current understanding of the low NOx oxidation of isoprene is poorly
represented in numerical models. Experiments will also be performed on a series of terpenes and
other biogenic VOCs aiming at improving atmospheric models with regards to the atmospheric
radicals budget. For example, the direct formation of HO2 and the unsaturated hydroperoxyaldehydes co-products from the reaction of OH-isoprene adducts with O2 and the photolysis of
these hydroperoxy-aldehydes will be investigated.
OH radical is an important, and sometimes dominant, loss process of alkenes in the atmosphere.
Reactions of OH with alkenes proceed by OH addition to the C=C double bond and by H-atom
abstraction from the C-H bonds of the alkyl substituent groups. Although rate constants for the
overall reaction of OH radicals with number of alkenes have been reported, very limited data are
available concerning the rate constants for H-atom abstraction. The ICARE has the ability to
conduct specific experiments by looking at the products (very often with small yields) attributed
to the H-atom abstraction channels. In addition to improving the atmospheric chemical models,
the data obtained will be used to develop the structure-reactivity estimation methods.
The contribution of the chemistry of unsaturated compounds of biogenic and anthropogenic
origins to the formation of the secondary organic aerosols (SOA) formation will be investigated
for the same chemical systems described above. SOA are produced in the atmosphere from the
oxidation of hydrocarbons by atmospheric oxidants (OH, O3, NO3). They consist mainly of
various acids, dicarbonyls, organic nitrates … Some of these compounds are of concern to human
health. As fines particles, they can contribute to the mortality associated with fine particles. They
can also influence the radiation budget of the atmosphere either directly or through their role as
cloud nuclei. However, the direct and indirect effects are both dependent on the size distribution
and chemical composition which drive the optical and hydroscopic properties of the aerosol.
The research will be conducted using the existing experimental facilities of ICARE (flow tubesMS and simulation chambers) as well as the large outdoor chamber (HELIOS) under construction
and the dedicated analytical instrumentation. To conduct the above studies, state of the art
analytical equipment such as SAMU for HOx (OH and HO2), SPectomètre In situ
Troposphérique-NO3 (SPIT-NO3), SPIRIT for HCOOH, HCHO, PTR-TOF MS for organic
compounds, and others will be combined to our facilities.
2.2 Heterogeneous Chemistry
2.2.1 Atmospheric aerosol – trace gas interactions
This part of our research project involves laboratory studies of chemical processes on the surface
of atmospheric aerosols. Atmospheric particles can directly influence the radiative budget of the
atmosphere (an extinction and absorption of solar and terrestrial radiation) and also indirectly as
they may serve as condensation nuclei for the formation of clouds The radiative effect of aerosols
depend on their initial chemical composition as well as on their processing during aging in the
atmosphere. In addition, airborne particles provide the surface area for heterogeneous reactions of
atmospheric trace gases and thus have an influence on the chemical composition of the
15
atmosphere via the interaction between gaseous species and particulate matter. The changes
caused by heterogeneous reactions can affect in particular the concentrations of stratospheric
ozone and the oxidizing capacity of the troposphere and its effects on concentrations of
greenhouse gases and pollutants.
This research activity is related to the chemical impact of aerosols and concerns the experimental
study of heterogeneous reactions of the trace atmospheric gases (ozone, nitrogen oxides, OH and
HO2 radicals, organics etc..) with different types of atmospheric particles (soot, minerals, sea salt).
In spite of the recent significant developments in the studies of atmospheric heterogeneous
processes, there remains a significant lack of reliable laboratory data on the gas-solid interactions.
In many cases, despite the availability of experimental data, it is very difficult or impossible to
make unreserved recommendations of the parameters like uptake coefficient, reaction products
etc. for atmospheric modeling. Clearly, multiphase processes currently represent one of the key
problems of the chemistry of the atmosphere.
Our program on aerosol chemistry although lying in the continuity of the studies that we have
carried out in the laboratory during recent years, provides however an extension and evolution of
these studies taking into account the current state of knowledge and recent developments in the
field. In most previous studies the emphasis was placed on the interaction of gaseous species with
aerosol in the absence of light. Recent results show that the UV/Visible irradiation can initiate
new potentially important heterogeneous processes almost unknown to date. In this respect, we
extend our activity on heterogeneous reactivity to studies of the photochemical heterogeneous
processes in the presence of light. This part of our research programme is currently developed
within two projects (2008-2012) and will be continued within new national and European
projects.
2.2.2 Impact of photocatalytic remediation processes on air quality
Traffic-generated pollutants include nitrogen oxides, volatile organic compounds and particulate
matter. The transformation of these compounds within the atmosphere leads to the formation of a
series of harmful intermediates or end products. In the very recent years, photo-catalytic selfcleaning and “de-polluting” materials have been suggested as remediation process (for NOx and
aromatic VOCs) in the polluted urban environment. These commercial products are based on the
photo-catalytic properties of a thin layer of TiO2 deposited at the surface of the material (such as
glass, pavement …) or embedded in paints or concrete. The use of TiO2 photocatalyst as a
friendly air pollution emerging control technology has been reported in many European areas.
However, both the effectiveness and the real impact on air quality of these relatively new
technologies have been tested in a limited manner before going into the European market.
The work conducted so far has shown that the photocatalytic technology could reduce the
concentrations of NOx and BTEX (Benzene, Toluene, Ethylbenzene and Xylenes) in air.
However, the formation of other species such as HONO (an important OH source) and other
hydrocarbons (aldehydes, PAN-type compounds …) as a result of the interaction between
NOx/VOCs/particles and surfaces containing TiO2 has not been assessed in atmospherically
relevant conditions. The production of these later species may represent an important source of
new pollutants in the urban environment and may have a strong impact on the radicals budget and
consequently on the building up ozone and photooxidants pollution. There is accordingly an
urgent need for a better characterization of such surfaces at atmospheric relevant conditions.
Recently, in collaboration with other national and European groups, the Atmospheric Reactivity
group has started a research activity aiming at assessing whether the above mentioned remediation
technologies may be efficient in achieving levels of air quality that do not give rise to significant
negative impacts on and risks to human health and the environment. This is done though
experiments performed using the ICARE simulation chambers where the behaviour of typical
atmospheric chemical components (NOx, O3, alkenes, aromatics …) are investigated. Kinetic and
mechanistic parameters to be used in atmospheric models are derived. This activity will be
16
conducted in the next few years within two European projects (Eurochamp2, 2009-2013 and life+,
2010-2014).
2.3 Chemistry related to the upper troposphere – lower stratosphere (UT-LS)
Within this section, important part of our activity will be focused on the studies of the reactions at
low temperatures relevant to the UTLS (Upper Troposphere - Lower Stratosphere). UTLS is a
chemically very complex area influenced by the emissions from the planetary boundary layer,
aircraft in situ emissions and the production of NOx by lightning. The oxidation reactions of
volatile organic compounds (VOCs) taking place in this region of the atmosphere lead, in
presence of NOx, to ozone production, which significantly contributes to the atmospheric
radiative budget. It is, therefore, important to know the composition of the UTLS and its future
development, because of the recognized role of this atmospheric region in the global change. The
models calculating the chemical composition of the UTLS need high-quality reactivity databases.
This is not the case so far as indicated, for example, by significant differences observed between
measured and calculated concentrations of numerous species. Most of the models simulating the
impact of different species on the chemistry of the UTLS are based on laboratory measurements
carried out at temperatures and pressures which significantly differ from those in the atmosphere.
Indeed, there is a lack of reliable kinetic and mechanistic data for many reactions at the low
temperatures of UTLS (200-250K). Such data must be determined experimentally because the
extrapolation of the available data at ambient temperature is very uncertain.
The classes of reactions we plan to study include the steps of chain oxidation of hydrocarbons
initiated by OH radical in the presence or absence of NOx. Experimental facilities needed for such
investigations are already available in our laboratory. The turbulent flow reactor-chemical
ionization mass spectrometer and the laser photolysis-laser induced fluorescence techniques allow
to work at these low temperatures and thus provide reliable kinetic and mechanistic data for
modeling the UTLS chemistry. This laboratory research aims to be strongly coupled with field
measurements and atmospheric modeling and theoretical calculations on the reactions. This
activity is currently developed within a project of the PRIMEQUAL program (2010-2011), whose
objective is to better characterize the processes of formation and destruction of organic nitrates in
order to assess the role of these NOx reservoir species in the redistribution of NOx over long
distances. This work also includes low temperature studies relevant for UTLS. We plan to
continue this research activity within new national and European projects.
2.4 Experimental plate-form for atmospheric processes studies and atmospheric
trace gas measurements
As mentioned above, there is still a need for more accurate and precise kinetic and mechanistic
parameters to improve the atmospheric models. This is, at least partly, achieved by the
development of precise and sensitive analytical methods and experimental facilities representing
the real atmosphere.
Atmospheric simulation chambers are the best tools to investigate the relationship between
chemical emission and photo-oxidant building. With the financial support of Région Centre,
FEDER and CNRS, ICARE is developing the largest outdoor simulation chamber in France (and
the third one in Europe), HELIOS (cHambrE de simuLation atmosphérique à Irradiation naturelle
d’OrléanS), http://www.era-orleans.org/ERA-TOOLS/helios.html. This national facility will be
operative in early 2012. It will be highly instrumented and open to the international scientific
community.
The Atmospheric Reactivity group is equipped with high quality instrumentation for atmospheric
processes investigation both in the laboratory and field for measurements of trace gases (HCHO,
HONO, VOCs …). In the recent years, the group has contributed to different field campaign for
air pollution studies in France and China (Shanghai). It is planned to pursue this research activity
17
within national and international projects such as the Chemistry-Aerosol Mediterranean
Experiment Campaign (ChArMEx) coordinated by INSU-CNRS.
2.5 Atmospheric dispersion of pollutants
(A. MELLOUKI, V. DAELE, P. DAGAUT, I. FEDIOUN, I. GÖKALP)
A new project has recently started on the generation and atmospheric dispersion of pollutants and
combines the combustion chemical kinetics, atmospheric reactivity and fluid dynamics expertise
areas of ICARE. It deals with the analysis and preparation of public safety regulations in the case
of the occurrence of an explosion or fire in an industrial site storing large quantities of chemical
products, including explosives, solvents etc. This project is supported by FEDER, Region Centre
and the Department of the Cher and will be conducted in cooperation with two regional partners,
Sucrerie de Toury near Orleans, and NEXTER Munitions near Bourges. The industrial sites of
these two partners will provide the necessary input in terms of stored chemicals and the site
topology, geography and urban environment. ICARE will characterize the emissions from the
combustion of selected chemical, their toxicity level, their atmospheric reactivity parameters
through experimental studies, such as the secondary species formation potential, the atmospheric
life time of all considered species and the atmospheric dispersion of some selected species using
the meteorological and topological characteristics of the considered site. This last part will use
existing CFD tools at ICARE to which atmospheric reactivity information will be integrated.
18
Thematic Research Group III: Space propulsion
1. Research context and objectives
ICARE naturally inherits valuable experience and reconnaissance in the area of spacecraft
propulsion from the two former entities at its origin, namely: the LCSR and the Aérothermique
laboratories. The LCSR was recognized for his work on liquid and solid propulsion and on the
development of advanced numerical tools dedicated to the modeling and computer simulation of
supersonic reactive flows. The Laboratoire d’Aérothermique was known on the one hand for his
expertise on high-enthalpy rarefied supersonic flows and on the other hand for the experimental
studies on shock waves with the use of high Mach number cold gas jets. Furthermore, in 1996 the
GdR “Propulsion Spatiale à Plasma” was created and the PIVOINE instrument, a ground-based
test chamber for electric propulsion, was built and associated to the laboratory. All present
research activities carried out at ICARE in the field of space propulsion concern state-of-the-art
applications like launchers, satellites, missiles and hypersonic aircraft to only name a few. They
cover many strategic areas like communication, Earth observation, solar system exploration and
defense. In terms of collaborations and contracts, strong relationships are established with space
agencies and leading edge companies like SNECMA, EADS, SNPE/SME, MBDA and
ASTRIUM.
Within this context, the main objectives in this field for the following years are:
* to pursue present activities and explore new routes, opening-up the way to new areas and
solutions,
* to answer scientific questions and resolve physical issues,
* to keep at high standard the research and expertise in the laboratory,
* to bring new, innovative and financially viable technologies.
We therefore foresee four main directions that rely on the use of wind tunnels, space environment
simulators and home-made numerical codes.
One direction will deal with electrical thrusters. Studies will firstly consist in investigating high
power Hall thrusters and negative ion thrusters and secondly in proposing alternative approaches
for improving performances, lifetime and compatibility with spacecraft components. A second
direction will concern the study of non-equilibrium effects in plasma flows. The aim is to better
understand the physics of re-entry flights, a necessary step for improving spacecraft design. Part
of the work will also be focused on rarefied plasma flow control by means of a magnetic field.
The two aforementioned research topics fit perfectly into the Cosmic Vision science program of
ESA for exploration of the solar system that requires innovative technologies and improvement
and consolidation of current systems. A third direction will concern the control of the thrust vector
of a rocket engine by a local change of the flow properties in the nozzle using either an additional
propellant injection or plasma application. A last direction will concern numerical investigations
of rotating detonation engines and hypersonic air breathing engines.
2. Research projects
2.1 Electric propulsion
(S. MAZOUFFRE)
As explained in the review section, ICARE benefits from recognized experience and expertise in
the field of electric propulsion for satellites and spacecrafts. During the next few years, the policy
and accompanying strategy for that particular research topic will aim at maintaining at ICARE a
high-quality level of fundamental research that is necessary to ensure for French and European
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companies and agencies a leading position on related technological aspects.
This obviously necessitates to build-up knowledge on the underlying physics by way of careful
reasoning, experiments and analysis. Yet, this is not sufficient. Our objectives also require:
- to prepare ourselves for the new organization that will be the follow-up of the French jointresearch program GdR 3021. Indeed, after 16 years, the latter is probably going to cease to exist at
the end of the year 2011. Of course, in view of the past activities and involvement, ICARE must
play a leading role in the definition of the new organizational scheme as well as in its
management.
- to strengthen existing links with CNES and ESA and companies like SNECMA and ASTRIUM.
- to better collaborate with laboratories located outside Europe, especially in the USA, for very
specific items solely connected with basic physics of ion sources. A fruitful collaboration with the
well-known group of Prof. A. Gallimore at the University of Michigan has already been
established.
2.1.1 Physics of Hall thrusters
The team shall continue detailed investigations of the physics of crossed-field discharges on
which Hall effect thrusters rely. We therefore propose:
* studies on scaling laws and sizing methodologies for the design of high-power Hall thrusters
(10-100 kW power range) needed for exploration of outer planets and asteroids,
* investigations on time-dependent electron properties in the discharge as well as in the plume
using probes and laser scattering techniques. Electrons are key species, the properties of which
drive to a large extent the thruster behavior and performances.
2.1.2 Innovative solutions
The examination of novel thruster architectures is crucial in order to circumvent present
drawbacks of the Hall thruster technology (together with the gridded ion engine technology) and
to increase the overall operating envelope. We suggest exploration of several axes:
* Alternative propellants for Hall thrusters and gridded ion engines. The idea is here to replace
Xenon, a rare and expensive gas, which is currently employed. These studies are of interest for
missions devoted to the exploration of the solar system as a large quantity of propellant is then
necessary. Two compounds are so far foreseen: Argon and Iodine. The former is cheap, easy to
store and allows to reach a large specific impulse; however, is has a high ionization energy. The
latter can be stored in solid state, it is easy to vaporize, it exhibits a large mass and it is relatively
easy to ionize. It is nevertheless highly corrosive and a fraction of the input power is lost in
dissociation and excitation of rovibrational modes. In order to compensate for a poor ionization
efficiency in the case of Ar and I2, a two-stage design with a RF ionization stage in will be
considered.
* PEGASES concept. Works on this ion-ion plasma based cathode-less thruster is presently
supported by ASTRIUM. The ultimate goal is to construct a prototype - or even a flight
demonstrator – and to measure the thrust and the efficiency, showing the sustainability of the
concept.
* Magnetic nozzle. The idea is to test this method of accelerating a plasma which is close to the
use of a de Laval nozzle for a neutral gas. The benefit is that the entire plasma is ejected out of the
thruster, so there is no need for a neutralizer. The main constraint is the necessary large plasma
temperature for generating a high exhaust velocity.
For the two previous tasks, most of experiments can be performed either in the PIVOINE-2g test
bench or, when less demanding, in the NExET chamber. However, the use of “exotic propellants”
and operation at power above 10 kW necessitate a size and a pumping capacity far above what
can be achieved with PIVOINE-2g. Therefore, together with space agencies and thruster
manufacturers, we will deliberate on the design, building and running of a new ground-based
facility.
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2.1.3 Advanced diagnostics
We will develop advanced tools for diagnosing the discharge and the plume of various kind of
thrusters.
* Coherent Thomson scattering system for probing the electrons energy distribution function. It is
the appropriate technique for probing electrons in a magnetized discharge where the Langmuir
probe fails.
* E×B probe for measuring both negative (PEGASES) and positive (Hall, electrostatic
accelerators) ion velocity in a thruster plume. This instrument would also find applications in the
field of plasma processing where ions play an important role.
* laser photodetachment for measuring the local negative ion density.
2.2 High-speed flow
These research activities concern two different subjects: non-equilibrium plasma flows
encountered during high-speed flights in the upper layer of planetary atmospheres and active
control of nozzle exhaust jets for space propulsion purposes. The first topic mostly concerns reentry of spacecrafts and capsules into the Earth, Mars and Titan atmospheres. The second topic is
directly linked to the development of new launchers and to the design of versatile spacecraft
propulsion devices. Experiments carried out at ICARE in the high-speed flow field utilize the
FAST platform, a set of wind-tunnels able to generate supersonic plasma jets as well as cold gas
jets over a broad range of pressures and Mach numbers.
2.2.1 Non-equilibrium plasma flows: Re-entry studies
(V. LAGO)
The resurgence of interest for the development of hypersonic transportation systems generates two
relevant fields of research, namely: the aerodynamic performance of hypersonic vehicles with
studies on flow control and the “real gas effects” due to the high temperatures during hypersonic
flights, which influences the shock stand–off-distances, the peak thermal loads, hence the heat
transfer from the gas to the vehicle, and finally the drag force on the vehicle. These phenomena
concern multi species, high temperature chemically reacting gas mixtures in high speed flows.
They involve non-equilibrium chemical and thermal relaxation, radiation and ionization and
magnetohydrodynamic phenomena in rarefied flow regimes. Physico-chemical models and
experimental data bases must still be improved and an important area of fundamental studies
concerns the coupling between the translational and internal modes of molecular energies whose
mutual exchange processes can take place on a time scale comparable to the hypersonic flow
characteristic time.
The experimental capabilities of ICARE with the platform FAST offers a set of facilities to
perform research on non-equilibrium physico-chemical phenomena involved in various kinds of
high speed flows. The facilities are equipped with a large set of diagnostics that allows for a
complete experimental characterization of the flows: VUV-visible-IR spectroscopy, Langmuir
probes, time of flight with electrostatics probes, fast imaging with intensified CCD camera,
fluxmeters, Pitot probes.
For the near future, we propose to continue the experimental investigations on non-equilibrium
flows carried on since many years and recently consolidated with the ANR project Rayhen,
oriented towards advanced techniques to control the flow past a space vehicle during the
atmospheric re-entry.
In this topic, one promising technology is the use electro-magnetically generated forces acting on
the ionized component of the flow impacting the vehicle. Although the ionized component is only
a small part of the whole flow downstream of the shock wave, when a proper magnetic field
topology is created in the vicinity of the surface body, a global body force can be exerted on the
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entire flow, the so-called MHD/EHD interaction. For example, concerning the blunt body parts
like the nose, the interaction can produce an upstream displacement of the bow shock or an
increase of the shock stand-off distance, followed by a relative decrease of the heat flux and
increase of the drag. This can be done in several ways depending on the characteristics of the
trajectory (i.e. using the natural plasma if ionization is present or using a dedicated device to
produce the plasma), the vehicle shape, and the used devices.
This electro – magnetic interaction of the flow could potentially reduce locally the heat flux via
shock stand-off distance increase (MHD interaction), manipulate wave drag and therefore the
ballistic coefficient, manipulate black out periods and therefore optimize communication links,
and also could be used to control the flow for stability and trimming resulting in simplification or
elimination of flaps and/or RCS (EHD control). Test facilities which can be used to perform
experiments for electromagnetic flow control are those which can achieve an enthalpy flow of not
less than 4-5 MJ/kg in air. These high enthalpy conditions can only be obtained in shock-heated or
arc-heated facilities like PHEDRA. Regarding magnetic flow control applications, collaboration
with Mme Pascale Gillon will be established. In addition in collaboration with the “Dynamique
des phénomènes hors equilibre” team from the IUSTI (Jean Denis Parisse), a numerical approach
is currently being developed. A two-temperature rarefied flow model that includes chemical
reactions is used to simulate air and CO2-N2 flows as well as their interaction with a model. In the
next few years, MHD coupling effects will be considered in order to explore specific physical
effects due to the presence of electro-magnetic forces.
2.2.2 Flow control
(E. DEPUSSAY, L. LEGER)
International competition on civil market of launchers encourages engineers to design more
efficient engines and to test new ideas concerning rocket propulsion and rocket trajectory control.
In this context, ICARE will continue to develop a scientific activity centered on the control of
supersonic flow actuators (plasma type and fluidic type actuators).
2.2.2.1 Supersonic flow control by secondary flows
The goal of this study is to obtain supersonic air nozzle jet flow vectorization. Our aim is to
increase the maneuverability of a flying device, e.g. missile or rocket. This research field began in
2009 with the PhD thesis of Vladetta Zmijanovic supported by the CNES. In the future, it will be
continued by non-stationary blowing to stimulate a specific jet flow mode. This kind of flow
control can induce jet noise and mixing properties modifications. Mixing properties and
secondary injection penetration length can also have a great interest for combustion applications.
This experimental work will be performed in the EDITH wind tunnel. In addition, numerical
analysis with the CNES-Bertin CPS (Code for Space Propulsion) will be conducted by solving
compressible Navier-Stokes equations on 3D unstructured grid using 2-equations turbulence
models. The complicated flow structure, which is encountered in supersonic cross-flows,
represents a real test for the numerical schemes conventionally used. We shall also continue our
collaboration on numerical simulations with the LMEE laboratory of the University of Evry.
2.2.2.2 Supersonic jet flow control or modification by plasma actuators:
This topic concerns the comparison between flow control by plasma actuators and by secondary
flow injection (blowing). The advantage of flow control by plasma is the lack of moving parts and
wide possibilities of control as it relies on electrical currents and power. This experimental work
will be realized in the EDITH wind tunnel. A high voltage power supply able to produce short
pulses of various shapes will be developed in collaboration with the Chemical Physics Laboratory
in Minsk. A specifically designed high voltage radio frequency discharges is indeed able to
control the flow in a wide range of flow parameters.
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2.3 Chemical propulsion
(I. FEDIOUN, D. DAVIDENKO)
The projects presented in this section concern, on the one hand, promising concepts of detonationbased engines and, on the other hand, hypersonic flights in the Earth atmosphere. Modern rocket
and air breathing engines based on the constant-pressure cycle (also known as Brayton cycle) are
almost at the highest level of perfection. The use of a detonation-based cycle can potentially push
the today’s limits of the engine performance. In this respect, interest in the rotating detonation
application is quickly growing in the world and starts competing with the pulse detonation
application. In France, this is also a topic of great interest due to the well-developed aerospace
industry. Hypersonic air breathing flight is an important dual problem as it can have several civil
and military applications. In France, studies in this field are led by the ONERA and MBDA
France. There are different international collaborative programs with European countries
(LAPCAT2 project), as well as with Russia (LEA project) and Japan.
2.3.1 Numerical studies on the rotating detonation engine
Since 2007, theoretical and numerical studies on the continuous detonation wave rocket engine
(CDWRE), conducted at ICARE, have permitted to develop several collaborations with MBDA
France that will continue within two projects. A FEDER project is currently prepared to create a
CDWRE demonstrator, which will be tested by MBDA France at the Subdray test centre, near
Bourges. The participation of ICARE in this project will consist in providing theoretical and
numerical support to design the demonstrator, predict its characteristics, and analyze the
experimental results. Another project is prepared for the Space program of FP7 to analyze the
applicability of the rotating detonation mode to the turbojet cycle. Within this project, ICARE will
also collaborate with SNECMA and Turbomeca. ICARE’s role will be to evaluate the engine
performances and simulate continuous detonation operation of a turbojet combustor.
2.3.2 Shock-induced supersonic combustion
The WENO code developed at ICARE allows the large eddy simulation of shocked, turbulent, and
reacting flows in simple geometries. A collaborative program with ONERA is currently
undertaken to study the effects of vitiation on the ignition of a hydrogen jet issuing from a flat
plate at angle of attack in a Mach 12 incident flow. The study aims to compare the MILES results
of our WENO code to RANS and LES calculations performed at ONERA DEFA/PRA with the
code CEDRE. Experiments are conducted in the F4 ONERA hypersonic wind tunnel, in the HEG
of DLR in Germany, and in the HIEST of JAXA in Japan.
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Organigramme général
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