PIV/PLIF investigation of two-phase vortex–flame interactions: effects of vortex size and strength

The evolution of flame surface area and rate of CH layer extinction are measured during the interaction of a two-phase counterflow diffusion flame with fuel-side vortices of varying size and strength. Planar laser-induced fluorescence (PLIF) of CH is used to mark the flame front and particle-image velocimetry (PIV) is used to measure the strain rate field at various phases of the interaction process. Vortices of similar initial circulation but differing in size showed widely disparate peak strain rates and CH decay rates because of varying levels of flame-induced vortex dissipation. Vortex size is also found to have a significant effect on flame surface area evolution during and after extinction, with the presence of droplets playing a significant role in the latter. Implications of these results for the fundamental understanding of vortex–flame interactions are discussed.