Interaction between two premixed laminar V-shaped flame fronts at low Lewis number

Abstract

In studies of flamelets in premixed turbulent combustion, the interaction between laminar flames is of great importance. To study this, measurements have been made of the interaction between two premixed laminar V-shaped flames (“W” configuration) for a Lewis number less than 1. When the Lewis number differs greatly from unity, differential diffusion effects dominate and lead to considerable complexity. Flow visualization is used in association with laser Doppler velocimetry. Temperatures are measured with a thermocouple and species are sampled through a probe. The results show repulsion between the two oblique flame fronts separated by fresh mixture. This induces a divergent flow in the whole interaction zone and an overall shifting of the two V-shaped flames. The influence of the Lewis number is first noticeable on the unburned gases between the two flames since it induces preferential diffusion of hydrogen in the transverse direction. This leads to an increase of temperature inside the two V-shaped flames. As a consequence, it also prevents the intersection and coalescence of the two inner fronts as they propagate towards each other.