Simultaneous imaging of soot concentration and temperature in ethylene diffusion flames

Abstract

The role of soot in combustion is important due to its environmental and health impact, in addition to its role in radiative heat transfer. While combustion processes involving soot have been applied for many years, the formation and destruction processes of soot in practical environments are still beyond the present capacity to understand adequately. A multitude of interdependent factors are fundamental to the understanding of soot; however, soot concentration and temperature remain significant. This work aims to develop laser-based thermometry techniques for simultaneous imaging of soot concentration and temperature in practical flames. Joint Laser-induced Incandescence (LII) and Non linear regime Two-Line Atomic Fluorescence (NTLAF) approach is demonstrated for ethylene diffusion flames on a Jet in Hot Co-flow (JHC) type burner. The present paper aims to assess the feasibility of the joint imaging approach. Particularly, the present paper aims to assess the potential interference due to the simultaneous application of the two methods. The present paper also aims to assess the effects of increasing soot concentration within flame on the techniques. Single-shot LII, fluorescence and background signals images from the diffusion flames are presented. No significant interference of the two methods on each other is observed. Background signals, however, are observed to with increasing soot concentration. This work demonstrates the applicability of the joint LII-NTLAF approach. This work also gives an indication on the operating range of the joint imaging approach, which is crucial to the establishment of joint LII-NTLAF approach as a viable laser diagnostics tool.