Mercredi 7 février à 10h, salle de séminaires IRPHE
Jorge Yanez and Mike Kuznetsov, Institute for Thermal Energy Technology and Safety, Karlsruhe, Germany
séminaire 1:
Near Limit Flame Propagation in a Hele-Shaw Cell Geometry at Very Low Peclet Numbers
An analysis of experiments near the limit of hydrogen flame propagation in a Hele-Shaw Cell Geometry is presented. A semi-open vertical combustion chamber of 90x20 cm with a gap from 1 to 10 mm was used in the tests. Test mixtures were ignited at the open end of the chamber so that the flame propagated towards the closed end. Approaching the flame propagation limit, the planar or wrinkled continuous flame surface degrades to fragmented dendritic flames or even to isolated one- or two-head flame balls due to the energy losses and local extinction. Flame shape morphology and its dynamic are analyzed.
séminaire 2:
2D self-drifting flame-balls
Combustion taking place in a slit between parallel plates suffers an anomalous burning regime observed for Peclet number (gap size normalized by the laminar flame thickness) smaller than 15. The oddity is characterized by a division of the continuous flame front into a set of tiny flame cells separated by fresh gas. Four propagation regimes were until now identified, and attributed to heat losses, as an outcome of our theoretical development. Still, the phenomenon remains mostly not understood. We are now presenting the reinterpretation of the experiments in heat loss terms to understand and verify the exactness of our theory. Simultaneously, we will show a classification of the flame typologies for the complex regimes that do have splitting. We believe that the understanding of this phenomena, will significant impact in fuel cell design and hydrogen safe handling, one of the main energy vectors of the future decarbonized societies.