Time-Resolved Particle Image Velocimetry of dynamic interactions between hydrogen-enriched methane/air premixed flames and toroidal vortex structures

Time-Resolved Particle Image Velocimetry was used to study transient interactions between hydrogen-enriched methane/air premixed flames and toroidal vortex structures. Lean and stoichiometric mixtures with hydrogen mole fraction in the fuel (hydrogen plus methane), x H 2 , varying in the range of 0–0.5 were investigated. s have shown that the hydrogen presence affects the flow field both quantitatively (increase of the velocity of the main toroidal vortex) and qualitatively (generation of different sub-vortices within the main vortex), enhancing the intensity of the interaction. Regardless of the mixture stoichiometry, the hydrogen substitution to methane leads to a transition from a regime in which the vortex only wrinkles the flame front ( x H 2 < 0 . 2 ) to a more vigorous regime in which the interaction almost results in the separation of small flame pockets from the main front ( x H 2 > 0 . 2 ). This transition was characterised in terms of time histories of flame surface area and burning rate.