The Thermal Structure of the Blue Whirl using Different Liquid Fuels

摘要

Recent experiments have resulted in the discovery of the blue whirl - a small, stable fire whirl which burns normally sooty hydrocarbons without producing soot. When these hydrocarbons were ignited in a self-entraining configuration, they consistently generated this new, stable, soot-free regime. Previous experiments were performed with n-heptane ignited over a water surface. In the experiments reported here, a variety of liquid fuels including iso-octane and cyclohexane were used, all of which eventually transitioned to a stable blue whirl. Fuels ignited over a smooth, flat metal surface also produced blue whirls. Thin-filament pyrometry was used to measure 2D temperature profiles, which were compared with previous measurements of the blue whirl generated using n-heptane. The temperature profiles were found to be independent of both fuel and surface type used in this study. Qualitative observations of OH~* chemiluminescence in the blue whirl were obtained using a UV camera to identify the primary reaction zones. The highest concentrations of OH~* were observed in the vortex rim, irrespective of the fuel.