Large eddy simulation of transient flame-vortex interactions during explosions of hydrogen-enriched methane/air mixtures

Large Eddy Simulation (LES) was used to study transient interactions between hydrogen-enriched methane/air premixed flames and toroidal vortex structures at the wake of a circular orifice. Computations were run for stoichiometric mixtures with hydrogen mole fraction in the fuel (hydrogen plus methane), xH2, varying in the range of 0-0.5. LES predictions reproduce well previously obtained experimental data, confirming that the intensity of the flame-vortex interaction increases with increasing xH2. This is a direct result of the higher reactivity (i.e., higher laminar burning velocity) of the hydrogen-enriched mixtures that produces faster flame propagation upstream of the orifice and, thus, higher rotational velocity for the toroidal vortex at the orifice wake, leading to further increase in the burning rate resulting from the interaction. © 2013, AIDIC Servizi S.r.l.