Soot distributions in a planar diffusion flame wrapped by a line vortex

摘要

Soot formation in flames has been extensively studied in the combustion community. Experimental and computational studies of laminar and turbulent flames have been conducted with majority of the research being focused on laminar flames. As a bridge between laminar and turbulent flames, some studies have focused on modulation of laminar diffusion flames by external forcing and soot formation in the vortical structures. More recently Shaddix et al. studied normal (fuel jet bounded by oxidizer) and inverse (oxidizer jet bounded by fuel) diffusion flames in planar slot jet configuration with and without external forcing of the center jet. They found that soot yield increases with modulation of the flame and the inverse flames produce somewhat less soot than normal flames. They attributed this to the formation of the buoyant vortical structures near the natural buoyant puffing frequency towards the outer stream, i.e. fuel side for the inverse flames. In the same spirit, flame-vortex interactions have been studied in a variety of contexts to provide an important link between laminar and turbulent reacting flows as reviewed by Renard et al.. The problem considered here is the interaction of a line vortex with a planar diffusion flame and the resulting soot distributions. This type of vortex interaction was employed earlier to study mixing in liquids and gases. Planar configuration lends itself for planar laser diagnostics of soot using laser induced incandescence (LII). In the following, we briefly describe the experimental set-up and measurement techniques and present the results.