Blanc SIMI 9 - Blanc - SIMI 9 - Sciences de l'ingéniérie, matériaux, procédés, énergie

Kinetic and Hydrodynamic Effects in Plasma-Flame Interactions – PLASMAFLAME

PLASMAFLAME

Kinetic and hydrodynamic effects in plasma-flame interactions

Objectivs of the Project

The vision behind this project is to provide a novel method to control combustion in internal combustion engines, especially finding new ways to control ignition delays, speed of flame propagation, combustion efficiency, and to reduce pollutant production. Over the past decade, many experiments have demonstrated that plasma discharges can significantly enhance combustion processes, and it is important to note that these effects can be obtained with plasma powers that are much lower than the power released by the flame, thus making the process of plasma-assisted combustion a highly realistic candidate for improving combustion strategies. However, two questions must still be considered. First, what is the effect of the active species (radicals, electronically excited species, …) created by the plasma on the flame kinetics. Indeed, most combustion mechanisms have not been validated for the high levels of radicals, mainly O atoms, produced by the discharge. Furthermore the effect of these active species might be especially important in the low and intermediate temperature regimes that precede autognition, and in where kinetic mechanisms of combustion are very complex. Second, what is the effect of hydrodynamic interactions between the active species created inside the discharge and the overall fuel/air flowfield.<br />Therefore, the overall scientific objective of the project is to provide a clear understanding of these two main modes of interaction of the plasma discharge with the flame, namely via kinetic mechanisms and hydrodynamic transport of active species. <br />

The Project PLASMAFLAME focuses on a comprehensive fundamental experimental and numerical study of the influence of low temperature nonequilibrium plasma on combustion process. Ignition and combustion, which are sustained by nonequilibrium plasma, are caused by the interaction of a number of physical and chemical phenomena. To give an adequate physical description of plasma-assisted ignition/combustion it is necessary to combine detailed fundamental knowledge in gas discharge physics, hydrodynamics, and chemical kinetics. Targeted experiments to obtain quantitative data on active species produced by a discharge, on ignition delay times and to gain a profound understanding of the role of hydrodynamics in plasma-flame interaction combined with detailed numerical modeling are proposed. Experiments will be carried out at relatively low initial temperatures (about 1000 K) and high pressures (5-40 bars) combining pulsed nanosecond plasma reactors with rapid compression machines. The discharge impact and combustion process will be subdivided in time, the total duration of the discharge will be a few orders of magnitude less than the typical ignition delay time; in situ measurements in nanosecond and millisecond time scales will be conducted with high spatial and temporal resolution. Chemical kinetics of discharge and combustion initiated/sustained by plasma will be analyzed in detail. The numerical codes to describe plasma assisted ignition and plasma-flame hydrodynamics interaction under low temperatures and high pressures will be developed. Finally, the results obtained will culminate in practical testing in a real automotive engine facility to assess the impact of the advances obtained in the project.

- LPP: System of high-voltage electrodes for rapid compression machine has been developed and successfully tested; ANDOR spectrometer available in the laboratory has been repaired and used for the experiments to measure the electric field in a surface nanosecond dielectric barrier discharge (SDBD) in non-combustible gases;
- EM2C: System of high-voltage electrodes for application of NRP discharges is being setup in a fixed volume combustion chamber. The Schlieren system has been developed and implemented. Spectroscopic equipment and laser imaging are also in place.
- PC2A: First tests on the rapid compression machine with combustible mixtures (CH4 and C4H10 as combustible components) with oxygen or air diluted with nitrogen or argon has been performed. The RCM has been prepared for the experiments on plasma-assisted ignition. The preliminary experiments to verify the regimes available both for autoignition and for plasma assisted ignition have been carried out;
- PPRIME: a first meeting between EM2C and PPRIME has been organized on the 20th of April 2012 in Poitiers. The characteristics of the experimental setup that will be used in PPRIME to study plasma in non-reactive conditions have been defined.
- IFPEN: Experiments will be performed in the 4th year of the project on a single cylinder internal combustion engine with optical access. Various laser diagnostic techniques will be employed in order to evaluate the influence of the NRP device on engine combustion characteristics. A dedicated project team (project leader, engineer and technician) will be assigned to this experimental study.

The improved understanding of the principles of ignition and combustion control by nonequilibrium plasma will help develop high pressure plasma research in France, potentially enabling a wide variety of applications such as ignition and flame stabilization in fast flow reactors, flame control under conditions of lean combustible mixtures, initiation of ignition in the operating conditions of homogeneous charge compression ignition engines and so on. By maintaining regular participant meetings, by students, researchers and PIs participation in French and international scientific conferences, and by publishing the results in well-recognized scientific journals, the obtained results will be rapidly disseminated to the scientific community on a world-wide scale.

Kick-off meeting for the Project PLASMAFLAME has been organized in Palaiseau, Ecole Polytechnique, by Laboratory for Plasma Physics (LPP), on 14 of March 2012.
- LPP/PC2A:
PhD student (Mohamed Amine BOUMEDHI), starts from September 2012. He has been already participated in his first training on Rapid Compression Machine (RCM) and high-voltage nanosecond surface dielectric barrier discharge (SDBD) and has been taken part in the first series of experiments in combined RCM-SDBD reactor in PC2A in Lille in July 2012.
- EM2C: Schlieren experiments have started in quiescent air mixtures, showing the gas heating zone and associated shock waves, under the influence of a Nanosecond Repetitively Pulsed (NRP) discharge. The simulations tools are also being developed for the simulations of plasma/flow interactions.
- PPRIME: A grant for a Ph D student has been obtained. The selected Ph D student (Allassane SEYDOU MOUMOUNI) will start his research work in October 2012.

Ignition of fuel-containing mixtures is an important problem in fundamental and applied combustion research. In spite of the fact that the principle of spark ignition and autoignition has long been known and used in the automotive industry, there are different applications where the use of other plasma systems may be of significant benefit. Here we can point to ignition of fuel-air mixtures at moderate gas densities and high-velocity gas flows, including ignition in supersonic flows, combustion support or enhancement by plasma at atmospheric pressure, stimulation of combustion of lean or diluted mixtures.

The Project PLASMAFLAME focuses on a comprehensive fundamental experimental and numerical study of the influence of low temperature nonequilibrium plasma on combustion process. Ignition and combustion, which are sustained by nonequilibrium plasma, are caused by the interaction of a number of physical and chemical phenomena. To give an adequate physical description of plasma-assisted ignition/combustion it is necessary to combine detailed fundamental knowledge in gas discharge physics, hydrodynamics, and chemical kinetics. Targeted experiments to obtain quantitative data on active species produced by a discharge, on ignition delay times and to gain a profound understanding of the role of hydrodynamics in plasma-flame interaction combined with detailed numerical modeling are proposed. Experiments will be carried out at relatively low initial temperatures (about 1000 K) and high pressures (5-40 bars) combining pulsed nanosecond plasma reactors with rapid compression machines. The discharge impact and combustion process will be subdivided in time, the total duration of the discharge will be a few orders of magnitude less than the typical ignition delay time; in situ measurements in nanosecond and millisecond time scales will be conducted with high spatial and temporal resolution. Chemical kinetics of discharge and combustion initiated/sustained by plasma will be analyzed in detail. The numerical codes to describe plasma assisted ignition and plasma-flame hydrodynamics interaction under low temperatures and high pressures will be developed. Finally, the results obtained will culminate in practical testing in a real automotive engine facility to assess the impact of the advances obtained in the project.

In addition to the broad fundamental goals, the proposed Project will also reflect many of the stated ANR criteria for broader impact. In particular, the improved understanding of the principles of ignition and combustion control by nonequilibrium plasma will help develop high pressure plasma research in France, potentially enabling a wide variety of applications such as ignition and flame stabilization in fast flow reactors, flame control under conditions of lean combustible mixtures, initiation of ignition in the operating conditions of homogeneous charge compression ignition engines and so on. By maintaining regular participant meetings, by students, researchers and PIs participation in French and international scientific conferences, and by publishing the results in well-recognized scientific journals, the obtained results will be rapidly disseminated to the scientific community on a world-wide scale.

Project coordination

Svetlana Starikovskaya (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS) - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR OUEST ET NORD) – svetlana.starikovskaya@lpp.polytechnique.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

PC2A UNIVERSITE DES SCIENCES ET TECHNOLOGIE DE LILLE 1
P' ECOLE NATIONALE SUPERIEURE DE MECANIQUE ET D'AEROTECHNIQUE (ENSMA)
IFP Energies nouvelles IFP ENERGIES NOUVELLES
LPP (EP) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS) - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR OUEST ET NORD
EM2C CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS) - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR OUEST ET NORD

Help of the ANR 749,999 euros
Beginning and duration of the scientific project: November 2012 - 48 Months

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