Effects of CO2-H2O dilution on the characteristics of CH4-air-O2 flames

International audience Study of non-premixed turbulent flames stabilized by a swirler Control of pollutant emissions / emissions standards Improve performances of combustion plants Investigations on flame characteristics Effects of oxygen enrichment Effects of steam and CO2 dilution Effects of swirl intensit

Density functional method for nonequilibrium electron transport

We describe an ab initio method for calculating the electronic structure, electronic transport, and forces acting on the atoms, for atomic scale systems connected to semi-infinite electrodes and with an applied voltage bias. Our method is based on the density functional theory (DFT) as implemented in the well tested Siesta approach (which uses non-local norm-conserving pseudopotentials to describe the effect of the core electrons, and linear combination of finite-range numerical atomic orbitals to describe the valence states). We fully deal with the atomistic structure of the whole system, treating both the contact and the electrodes on the same footing. The effect of the finite bias (including selfconsistency and the solution of the electrostatic problem) is taken into account using nonequilibrium Green's functions. We relate the nonequilibrium Green's function expressions to the more transparent scheme involving the scattering states. As an illustration, the method is applied to three systems where we are able to compare our results to earlier ab initio DFT calculations or experiments, and we point out differences between this method and existing schemes. The systems considered are: (1) single atom carbon wires connected to aluminum electrodes with extended or finite cross section, (2) single atom gold wires, and finally (3) large carbon nanotube systems with point defects.Comment: 18 pages, 23 figure

Simulation numérique de la combustion turbulente fournie par un brûleur à jets séparés

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Predictive analysis of combined burner parameter effects on oxy-fuel flames

International audienceThe present paper aims at studying the influence of burner parameters with a separated jet configuration, namely nozzles diameters and separation distance between the jets, on the flame characteristics (lift-off positions of flame and flame length). The experimental layout considers the use of OH-chemilumenescence to measure the flame characteristics for different combinations of processing conditions. The predictive analysis is based on a neural computation that considers the correlations between the inputs and the outputs of a combustion system using a configuration of separated jet. The predictive analysis show that a good agreement is found between numerical and experimental results in the case where the predictions are within the process window. The exploration of other process parameter combinations beyond that window gives less convincing results. This is mainly attributed to the fact that steady state characteristics are predicted numerically whereas it is expected experimentally that some of burner parameter combinations can lead to an increase of the parameters characterizing the flame

Experimental and numerical investigation of NG+H2/Air+O2 normal diffusion flame

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Etude numérique de la flamme d’oxy-combustion issue d’un brûleur à jets séparés

International audienc

Etude numérique de la flamme d’oxy-combustion issue d’un brûleur à jets séparés

International audienc

Swirl effects on dynamics characteristics of a coaxial jet

International audienc