Effect of low-temperature reactivity on the turbulent combustion of n-octane/iso-octane mixtures in a reactor-assisted turbulent slot burner

Common liquid transportation fuels are composed of many different types of large hydrocarbons, some of which are quite reactive at low temperatures. It has been shown previously that the low-temperature chemistry of certain reactive fuels can influence the turbulent flame structure when pre-flame fuel oxidation occurs. This study seeks to answer how blends of fuels with different reactivities, analogous to a real fuel, experience this low-temperature ignition turbulent regime. A reactor-assisted turbulent slot burner with the capacity for elevated burner exit temperatures is used to investigate the turbulent premixed flames of n-octane/iso-octane blends. The experimental results reveal that the blends with significant amounts of n-octane experience pre-flame low-temperature fuel oxidation at elevated burner exit temperatures, which leads to noticeable effects on the flame structure and the turbulent burning velocity. This regime change is not seen for the blends composed primarily of iso-octane, which confirms the role of low-temperature reactivity in modifying the turbulent flame.