Nos dias 12 e 15 de dezembro, o Dr. Josué Melguizo Gavilanes irá apresentar seminários sobre sua pesquisa recente no Instituto de Física. Ambos seminários ocorrerão às 13h30 no Auditório do Instituto de Física. O Dr. Josué é pesquisador do Graduate Aerospace Laboratories, California Institute of Technology (GALCIT), Pasadena, CA USA e está visitando o Instituto de Física no âmbito do Edital PROPeq/UFMT de apoio a pesquisadores internacionais visitantes Edição 2016.
Segunda-feira, 12/12: Experimental and numerical study of the ignition of hydrogen-air mixtures by a localized stationary hot surface
Abstract: The ignition of hydrogen-air mixtures by a stationary hot surface (glowplug) has been investigated. The ignition process was characterized by the surface temperature when ignition occurs, as well as by the location where the initial flame kernel is formed. The experimental results indicate that the ignition temperature threshold is a function of equivalence ratio whereas the ignition location seems to be a function of the rate at which the glow plug is heated. Comparison with two-dimensional numerical simulations exhibits discrepancies in terms of the temperature threshold evolution with equivalence ratio. Results indicate that a number of parameters, including surface temperature non-uniformities, surface chemistry and reaction model used, could influence the ignition threshold as well as the location of ignition.
Quinta-feira, 15/12: Dynamics of ignition of stoichiometric hydrogen-air mixtures by moving heated particles
Abstract: Studying thermal ignition mechanisms is a key step for evaluating many ignition hazards. In the present work, two-dimensional simulations with detailed chemistry are used to study the reaction pathways of the transient flow and ignition of a stoichiometric hydrogen/air mixture by moving hot spheres. For temperatures above the ignition threshold, ignition takes place after a short time between the front stagnation point and separation location depending upon the sphere's surface temperature. Closer to the threshold, the volume of gas adjacent to the separation region ignites homogeneously after a longer time. These results demonstrate the importance of boundary layer development and flow separation in the ignition process.