Vortex-coupled oscillations of edge diffusion flames in coflowing air with dilution

The unsteady characteristics of oscillating methane diffusion flames in coflowing air diluted with CO2 in earth gravity have been studied experimentally and computationally. The measured frequency of flame flickering due to buoyancy-driven large-scale vortices was bi-modal; it jumped from ≈11 Hz to ≈15 Hz with an increase in the air velocity (at ≈11 cm/s). As CO2 was added into coflowing air gradually, the base (edge) of the flame detached from...