An experimental study on the flame behavior of opposed flow diffusion flames in narrow channels

Abstract

The flammability limits of opposed flow diffusion flame in a narrow channel were investigated experimentally and theoretically. Various flame behaviors were observed. Due to the confined structure of the combustor in this study, diffusion flames at very narrow strain rates could be stabilized and their characteristics were investigated. There were three extinction modes corresponding to high strain rate (HSR), low strain rate (LSR) and fuel dilution ratio (FDR) limits. To investigate these limits, a theoretical study was followed by focusing on the flow and the heat transfer characteristics. Consequently, a dead space was important even for a diffusion flame to reveal the heat loss mechanism in a narrow channel at LSR condition. This study will be helpful to understand overall flame behavior of non-premixed flame in a narrow combustion space, and will also be useful to develop meso-scale combustors.