2013 Volume 55 Issue 173 Pages 264-271
This paper presents new application of microcombustion technologies to fuel reactivity measurement and research tool for combustion chemical kinetics. In prior works using a heated micro channel so called “micro flow reactor with a controlled temperature profile”, three kinds of flame dynamics were observed for a methane/air mixture: normal flames in the high flow velocity regime; flames with repetitive extinction and ignition in the moderate velocity regime; and weak flames in the low flow velocity regime. We focused on weak flames and theoretical background on the relation between weak flames and ignition is examined. Subsequently, experimental and computational results on weak flames of dimethyl ether/air and n-heptane/air mixture are examined. Three-stage reaction zones were observed in both experiment and computation. Investigating species profiles of the weak flames, it was found that transient, three-stage ignition (oxidation) process was realized as stable, three-stage reaction zones by the micro flow reactor. This micro flow reactor methodology was further applied to various fuels and effects of gasoline primary reference fuels on weak flames are introduced. Experiments and computations at elevated pressures (up to 5 atm) were conducted and pressure dependence of weak flames was investigated. Pressure dependence of weak flames for an ethanol/air mixture was computed using two different chemical kinetics and computed pressure dependence was different each other although the two chemical kinetics predict the same pressure dependence of mass burning velocity and ignition delay time. Finally, recent works using the micro flow reactor are introduced.
