A LAMINAR VORTEX INTERACTING WITH A PREMIXED FLAME - MEASURED FORMATION OF POCKETS OF REACTANTS

A single toroidal, laminar vortex in created and a laminar premixed flame is propagated over the vortex in order to study the fundamental interaction process and to compare results with the numerical solutions of the Navier-Stokes equations obtained by Poinsot, Veynante, and Candel. Results quantify the degree of flame roll-up, the flame perimeter increase due to wrinkling, the minimum vortex size that wrinkles the flame, and the boundary of the pocket formation (corrugated flame) regime. The measured trends indicate that viscous attenuation of the vortex by the hot, viscous products is important. The importance of flame stretch is verified; as Lewis number is varied it is found that in order to form pockets, diffusionally stable flames require a vortex strength that is three times larger than that required by the diffusionally unstable flames.